Spinning principle

Editors-in-Chief: Wang Jiankun, Li Fengyan, Zhang Shujie

Executive summary

This book is a ministerial and commission-level planning textbook for general higher education in the 13th Five-Year Plan, and is one of the first-class disciplines of textile science and engineering and the first-class professional construction textbooks for textile engineering undergraduates.

This book highly condenses the basic principles and common knowledge of different fiber spinning, summarizes and sorts out the knowledge points from the two dimensions of the spinning process theory system and students' learning cognition, and strives to be accurate, objective and concise. The book consists of nine chapters, including introduction, raw material selection, opening, carding, combing, drafting, twisting, winding, new yarn formation, etc., systematically explaining the basic principles of the whole process of staple fiber spinning and processing, and timely integrating the latest applications and research results in new spinning technology, new technology, new equipment and other aspects. At the same time, the book also sets up forward-looking discussion topics in some chapters, in order to lead readers to think about the development trend of modern spinning technology and the social responsibility of environmental protection and ecological spinning and processing.

This book is a textbook for textile engineering in higher textile colleges, and can also be used as a reference for textile engineering technicians and scientific researchers.

前 言

The textbook "Principles of Spinning" is compiled to meet the training requirements of higher textile education with a solid foundation and wide caliber and the latest development of the textile industry, and is a special textbook for the core course of textile engineering undergraduate major, "Principles of Spinning".

The book is divided into nine chapters, the first chapter is an introduction, which outlines the basic principles of spinning, the main systems and the use and classification of yarns, so that readers have a preliminary understanding of the theoretical system, technological process and yarn of the spinning process; Chapters 2 and 8 respectively expound the basic concepts and principles of raw material selection, opening, carding, combing, drafting, twisting and winding in spinning and processing, as well as their application in the yarn forming process. Through a high degree of condensation and in-depth analysis of the basic principles of spinning different fibers such as cotton, wool, silk, and linen in different spinning systems, readers can master the common knowledge of spinning. At the same time, through the analysis of its specific application in the yarn forming process, the readers can master the characteristic knowledge of different spinning systems, and realize the combination of theory and practice, which is conducive to the readers to better understand and master the basic principles and application laws of spinning processing. Chapter 9 focuses on the principles and practical applications of new structure ring spinning and new spinning, which can enable readers to further grasp the development and innovation of spinning process theory and technology.

The division of labor for the compilation of this book is as follows: Chapter 1, Wang Jiankun, Tianjin Polytechnic University; Chapter 2, Hu Yanli and Li Fengyan, Tianjin Polytechnic University, Liu Yueling, School of Textile Arts, Taiyuan University of Technology; Chapter 3, Peng Haokai and Zhang Shujie, Tianjin Polytechnic University; Chapter 4, Zhang Meiling, Tianjin Polytechnic University, Cao Jipeng, Eastern Liaoning University; Chapter 5, Li Cuiyu and Li Fengyan, Tianjin Polytechnic University; Chapter 6, Wang Jiankun and Li Xinrong, Tianjin Polytechnic University; Chapter 7, Li Fengyan, Tianjin Polytechnic University; Chapter 8, Hu Yanli, Li Fengyan, Wang Jiankun, Tianjin Polytechnic University, Zhao Bo, Zhongyuan Institute of Technology; Chapter 9, Zhang Shujie, Tianjin Polytechnic University.

The whole book was drafted by Wang Jiankun, Li Fengyan, and Zhang Shujie, and reviewed and approved by Wang Jiankun.

In addition, in the process of compiling this book, doctoral students Fu Lisong, Jiang Xiaodong and Guo Jing from the School of Textile Science and Engineering and School of Mechanical Engineering and Automation of Tianjin Polytechnic University, and Liu Lidong and Sang Caixia, master's students, have done a lot of work in drawing and retouching.

Limited to the level of editors, it is inevitable that there will be shortcomings and errors in the book, and readers are invited to criticize and correct any inappropriateness.

编 者

June 2020

目录

Chapter 1 Introduction 1

Section 1 Fundamentals of Spinning 1

First, the main role of spinning 1

Second, spinning auxiliary role 3

Section 2 Spinning Process System 4

1. Cotton spinning system 4

2. Wool spinning system 6

3. Silk spinning system 8

Fourth, hemp spinning system 10

Section 3 Classification and Use of Yarn 11

1. Classification according to the composition of fiber raw materials 11

2. Classification according to the thickness of the yarn 11

3. Classification according to spinning system 12

IV. Classification by use 12

V. Other classification methods 12

Chapter 2 Raw material selection 14

Section I Overview 14

1. Fiber raw materials and their process properties 14

Second, the purpose and principle of raw material selection 15

3. Options in the spinning system 16

Section 2 Natural Fiber Selection 16

1. Cotton fiber optional 16

Second, the wool fiber optional 22

3. Other natural fibers are optional 28

Section 3 Chemical staple fiber selection 32

1. Selection of fiber varieties 32

2. Determination of blending ratio 32

3. Fiber properties are optional 35

Section 4 Selection of reused raw materials 36

1. Sources of reused raw materials 36

2. Reuse of raw materials 38

3. Reuse raw materials 40

CHAPTER III. 44

Section I Overview 44

I. Purpose and requirements of opening 44

2. Opening effect in spinning system 45

Section 2 Fundamentals of Opening 46

I. Tear and open 46

Second, the blow to open 48

4. Factors influencing the opening effect 55

5. Evaluation of opening effect 60

Section 3 Removal of impurities in the process of opening 61

1. Chemical impurity removal 61

2. Physical impurities removal 66

3. Evaluation of impurity removal effect 83

Section 4 Mixing in the Opening Process 84

1. Purpose and requirements of raw material mixing 84

Second, the index calculation of the mixture 85

III. Mixing Methods 88

IV. Evaluation of the Mixing Effect 94

Chapter 4 Carding 98

Section I Overview 98

I. Purpose and requirements of carding 98

2. Carding in the spinning system 99

Section 2 Card clothing for carding 100

1. Metal card clothing 100

2. Elastic card clothing 103

3. Comparison of metal card clothing and elastic card clothing 104

Fourth, the basic requirements of the spinning process for card clothing 105

Section 3 Basic Principles of Carding 105

1. Force and movement of fibers in the carding process 105

2. The principle of action of the two needles on the fiber 109

3. Analysis of the work of the action zone 112

Section 4 Loading and distribution of needle fiber layer 123

1. Significance and types of needle surface load 123

2. The process and function of needle surface load formation 123

3. Distribution coefficient 128

Section 5 Other Main Roles in the Carding Process 129

I. Uniform action 129

II. Mixing Effect 130

III. Impurity removal 133

Chapter 5 Combing 139

Section I Overview 139

I. Purpose and requirements of combing 139

2. Combing in the spinning system 140

Section 2 Combing Preparation 142

1. Purpose and requirements of combing preparation 142

II. Preparation Methods 143

3. Supporting process after combing 144

Section 3 Combing process and motion coordination 144

1. The process of combing 144

Second, the working cycle of combing and the movement of coordination 147

Section 4 Basic Principles of Combing 152

I. Basic Concepts 152

II. Analysis of the effect of feeding 155

3. Analysis of the carding effect 164

IV. Analysis of separation and bonding 171

Section 5 Timing and positioning of the combing process 177

1. Clamp plate movement timing 177

Second, Xilin positioning 178

3. Top comb positioning 179

Fourth, the separation of the roller rotation timing 180

CHAPTER VI DRAFTING 182

Section I Overview 182

I. Purpose and requirements of drafting 182

2. Conditions for the realization of roller drafting 183

4. Drafting in spinning systems 186

Section 2 Fundamentals of Drafting 186

1. Friction boundary 186

2. Classification and quantity distribution of fibers in the drafting area 189

3. Force analysis of planktonic fibers in the drafting zone 191

4. Distribution of fiber movement and variable speed points in the drafting area 197

Section 3 Additional Friction Boundaries and Their Applications 203

1. Ideal friction boundary distribution and additional friction boundary 203

2. Additional friction boundary device and its requirements 205

3. Additional friction boundary device and its application in drafting process 205

Section 4 Parallel Straightening of Fibers During Drafting 215

1. Fiber morphology and straightening coefficient in whiskers 215

2. Basic conditions for fiber straightening during drafting 216

3. Drafting multiples and the straightening effect of hook fibers 218

Section 5 Uneven and Homogeneous Sliver 223

1. Uneven classification of yarn strips 223

2. Analysis of uneven yarn sliver 224

3. Homogeneous mixing effect of merging 226

4. Self-leveling 231

Chapter VII Twisting 242

Section I Overview 242

1. Purpose and requirements of twisting 242

2. Twisting in the spinning system 243

Section 2 The Basic Process of Twisting 243

1. Formation of twist and twist angle 243

2. Twist and twist direction 244

3. Transfer, twisting and blocking twisting 245

Section 3 Basic Principles of Twisting 247

I. The Essence of Twisting 247

Second, the real twist plus twist 248

3. False twist and twist 251

Section 4 Measurement of the degree of twisting 254

1. Single yarn 254

Second, the strand 257

Section 5 Application of twisting in yarn forming process 258

1. Application in roving forming 258

2. Application in spinning forming 265

3. Application in strand processing 274

CHAPTER VIII WINDING 286

Section I Overview 286

1. Purpose and requirements of winding 286

2. Winding in the spinning system 287

Section 2 Fundamentals of Winding 287

I. Basic Types of Winding 287

2. Winding equation 288

3. Winding tension 289

Section 3 Application of winding in yarn forming process 291

1. Fiber coil winding 291

Second, the coil strip winding 293

3. Roving winding 298

Fourth, spinning winding 306

5. Package yarn winding 312

Section 4 Tension and Breakage in the Winding Process 318

1. Roving winding tension and breakage 318

2. Spinning winding tension and broken end 321

Chapter 9 New Yarn 335

Section 1 Overview 335

I. Limitations of Traditional Yarn Forming Methods 335

2. Classification of new yarn forming methods 341

Section 2 Ring spindles are concentrated into yarn 342

1. The purpose of the ring spindle agglomeration into yarn 342

2. The principle of ring spindle agglomeration into yarn 342

3. Characteristics of agglomeration spinning yarn (compact spinning yarn) 348

Fourth, the way and application of ring spindle agglomeration into yarn 348

Section 3 Ring spindle composite yarn 353

First, the purpose of the ring spindle composite into yarn 353

2. The principle of ring spindle composite yarn 353

3. Characteristics of composite yarns 357

Fourth, the way and application of ring spindle composite yarn 358

Section 4 Free End Yarn 367

1. The purpose of free end yarn 367

Second, the basic principle of free end yarn 367

3. Characteristics of free-end yarn 369

Fourth, the application of free end yarn 370

Section 5 Non-free end yarn 385

1. The purpose of non-free end yarn 385

2. Basic principles of non-free end yarn formation 386

3. Characteristics of non-free end yarn 387

Fourth, the application of non-free end yarn 388

Ref. 407

Chapter 1 Introduction

What you need to know in this chapter:

1. The basic principle of spinning.

2. Various spinning process systems.

3. Classification and use of yarn.

Section 1 Basic Principles of Spinning

Yarn is a collection of fibers according to certain requirements, and spinning is an engineering technology gradually formed in long-term practice in order to achieve this requirement, with strong applicability and practicality. Fiber raw materials come from a wide range of sources, variety, and performance, and the performance of most fibers will be affected by environmental conditions such as ambient temperature and humidity. Therefore, in addition to the traditional mechanical, airflow and chemical methods used in modern spinning engineering, new processes and technologies such as optical, electrical, magnetic and biological technologies are constantly applied to meet the increasing and higher requirements of subsequent processing, practical application and natural environment for yarn and its production process.

Most of the state of fiber raw materials before spinning has the characteristics of large quantity, close connection between fibers, messy arrangement, containing impurities, etc., spinning is essentially the transformation of the fiber in this state into a process of longitudinal order arrangement according to certain requirements, mutual cohesion and hugging of yarn, to go through the preliminary processing of raw materials, selection, opening, impurities, mixing, carding, combing, drafting, evening, twisting, winding and other links. The principle of spinning is to study the basic laws of the changing structure, morphology and composition of the internal and external aspects of the fiber aggregate in these functions, which is mainly reflected in the fiber kinematics and dynamics.

First, the main role of spinning

In order to transform a large number of tightly tangled, disorderly arranged and impurity-containing fiber raw materials into yarns that meet the requirements, it is necessary to first completely remove the original local horizontal connection of the fiber, which is called "loosening", and then firmly establish the longitudinal connection of the end to the end, this process is called "collection". The loosening process of fiber processing from block to single fiber cannot be completed at one time, but must be completed gradually through opening, carding and drafting, so as not to damage the fiber and crush impurities; In the same way, the fibers are arranged in a chaotic order from a messy to a longitudinal sequence and the thickness meets the requirements is not completed at one time, but can only be completed after carding, drafting and twisting.

Loosening and collection are mainly completed gradually through opening, carding, drafting and twisting, opening is the preliminary of loosening, carding is the continuation of loosening, and drafting is the complete completion of loosening; At the same time, carding is the preliminary of the set, drafting is the continuation of the set, and twisting is the final realization of the set. Figure 1-1 shows the relationship between the two parties.

Figure 1-1 The main role of spinning and related relationships

(1) Opening effect

In this process, the contact force between fibers and impurities is correspondingly weakened, so that the impurities contained in the fibers can be removed, and the opening and impurities are carried out at the same time, and the opening is the premise of removing impurities. Breaking the interconnection between fibers is mainly done by tearing, blowing, splitting and other opening modes of action, and there are multiple processes in the spinning process of equipment configuration opening parts, so that the opening and impurities removal are gradually realized. In addition, the preliminary processing of fiber raw materials is also to open and remove impurities, such as ginning is to separate cotton fibers from cottonseeds by pulling to remove cottonseeds, and wool oil, sweat and weeds should be removed by chemical actions such as washing and carbonization. The opening process can also realize the mixing of raw materials, also known as bulk fiber mixing, which is one of the main mixing methods in spinning engineering. It can be seen that opening, impurities removal and mixing are often carried out at the same time, opening is the means, and impurities removal and mixing are the goals.

(2) Carding role

Carding is a modern loosening technology, through the carding machine parts covered with dense steel needles or sawtooth to repeatedly comb the fiber, basically remove the transverse connection between each fiber, so that small pieces, small bundles of fibers into a single fiber state, on this basis, further remove the fine impurities mixed between the fibers, and realize the fine mixing between the fibers, combing and perfecting the loosening, so that the removal and mixing effect is more sufficient. After carding, the fibers are output in a net-like manner, and the fibers can be arranged in a longitudinal order to form slender strips by bunching or cutting the net, so as to achieve a preliminary collection, but most of the internal fibers are buckling and hook-shaped, and the fibers still have a certain transverse connection due to mutual hooking.

(3) Drafting

Drafting is the processing process of elongating and stretching the strip after carding, obtaining the required fineness, its essence is that the fiber produces a variable speed in drafting, when the fast fiber is forcibly drawn out of the slow fiber bundle one by one, the friction between the fibers makes the buckling of the fiber gradually straightened, and the hook is gradually eliminated, which will be possible to completely remove the residual horizontal connection between the fibers, and lay the foundation for the firm establishment of a regular end-to-end cohesion relationship. Thus, drafting is both the completion of the release and the further refinement of the set. However, drafting will bring unevenness of yarn, in addition to the reasonable configuration of drafting devices and process parameters to control the generation of uneven drafting, but also use the homogenization effect to reduce unevenness.

(4) Twisting

Twisting is the process of twisting the drawn fiber strip (whisker) around its own axis, so that the fiber parallel to the axial direction of the whisker is spiral, so as to generate radial pressure to fix the longitudinal connection between the fibers. Due to the drafting, the whiskers are getting thinner and thinner, the number of fibers in the cross-section is getting less and less, and the fibers are more parallel and straight, but the axial connection is getting weaker and weaker, which is easy to cause the accidental elongation of the whiskers, and even the broken end cannot be yarn. Therefore, it must be fixed by twisting to achieve the final set. After twisting, it is called yarn, and its performance has changed, with a certain strength, elasticity, wear resistance, feel, luster, etc., which meets certain use requirements. In addition, depending on the application requirements, two or more single yarn strands can be twisted into strands. Different twisting methods will also affect the structure and properties of the finished yarn.

Second, the auxiliary role of spinning

Opening, carding, drafting and twisting are the main lines of spinning, which play a decisive role in whether the yarn can be formed. In addition, spinning also includes many links or functions that do not have a decisive impact on whether or not it can be spun into yarn, including:

Optional can stabilize production and product quality, rational use of raw materials;

Impurity removal, mixing, and homogenization are often carried out at the same time as the main functions of opening, carding, and drafting, which can make the yarn cleaner and more uniform;

Combing can remove unsatisfactory short fibers and fine impurities, and meet the needs of special fine, high requirements or special purpose yarns;

Winding connects the front and rear processes with each other, which is an indispensable link in the spinning process under the current technical conditions. Including the winding of fiber rolls, fiber strips, rovings, spinning yarns, package yarns, etc.

Spinning is a complex process, in order to better understand the theoretical system and basic principles of spinning, the above functions can be divided into the main line, secondary line and insertion line, if you want to spin a good quality yarn, all of them are indispensable.

(1) Main line: opening, combing, stretching and twisting, which determines the possibility of yarn.

(2) Auxiliary line: including selection, impurity, mixing, combing, and leveling, which cooperates with the main line to determine the quality of the yarn and the smoothness of processing.

(3) Insertion line: It consists of winding between every two adjacent intermittent processes.

Section 2 Spinning Process System

Textile products for different purposes require different types of yarns and their quality standards. Fiber raw materials come from a wide range of sources, with large differences in performance, requiring different spinning methods and processing techniques. In the production practice, different cotton spinning, wool spinning, hemp spinning, silk spinning and chemical fiber spinning and other special processes and corresponding spinning systems have been formed, and there are different technological processes such as general combing (carding), combing, semi-combing and blending, waste spinning in the same spinning system, the specific equipment used and its permutations and combinations are quite different, but the basic principle of spinning is the same, and its main role is to open, card, draft, twist throughout each spinning process system.

Choosing the right spinning process system is related to the spinnability and utilization of the fibers, as well as the quality and production costs of the yarn. The source and type of fiber raw materials is one of the important bases for choosing a spinning process system. At the same time, according to the physical properties of the fiber and the yarn formation requirements, different spinning process systems will be selected for the same type of fiber.

1. Cotton spinning system

The raw materials used in the production of cotton spinning are cotton fiber and cotton-type chemical fiber, and its products include pure cotton yarn, purified chemical fiber yarn and various blended yarns. In the cotton spinning system, according to the quality of raw materials and yarn quality requirements, it is divided into carding system, combing system and waste spinning system.

(1) Carded cotton spinning system

The carding system is the most widely used in cotton spinning, and is used to process fiber lengths and linear densities between 16-40 mm and 1.3-1.7 dtex. It is generally used to spin coarse and medium special yarns for weaving ordinary fabrics. The process flow, main function, semi-finished products and finished product names are shown in Figure 1-2.

Figure 1-2 Flow of carded cotton spinning system

The cleaning part of the cotton spinning system has two configurations: cleaning and carding or opening and carding, and the cleaning and carding are combined to realize the process combination and the technology is advanced. The following are all represented by the comb coupling.

(2) Combed cotton spinning system

The combing system is used to spin high-grade cotton yarn, special yarn or cotton and chemical fiber blended yarn. Because of its poor length uniformity and more impurities, cotton fiber blending with chemical fiber needs to be added to the combing preparation and combing process before combing and before combing, the purpose is to remove the short fiber and fine impurities below a certain length, further straighten and parallel fiber, and make the yarn structure more uniform and smooth. Figure 1-3 shows the process flow, main functions and names of semi-finished products and finished products of the combing system.

Figure 1-3 The process of combed cotton spinning system

(3) Waste spinning system

In spinning production, some scraps are constantly produced, such as broken seeds, carded cotton and chopping flowers, roving heads and silk returns. In order to make full use of raw materials and reduce costs, a waste spinning system can be used to process low-cost coarse cotton yarn, as shown in Figure 1-4.

Figure 1-4 The process of the waste spinning system

(4) Chemical fiber and cotton blending system

When polyester (or other chemical fibers) and cotton are blended, due to the different properties and impurities of polyester and cotton fibers, they cannot be mixed and processed in the carding process. The process flow of carding and worsted spinning is shown in Figure 1-5.

Figure 1-5 The process of chemical fiber and cotton blending system

The process of the cotton spinning system after the spinning system varies depending on the purpose of the product. For example, strands need meridian tubes, yarn merging, twisting and other processes; Yarn sales need to be processed such as meridian tubes, yarn shaking, and bales.

New yarn forming methods such as rotor spinning, air-jet vortex spinning, and friction spinning are generally spun directly into fine yarn with cotton slivers, which can save the roving process.

2. Wool spinning system

The wool spinning system is the whole production process of pure wool yarn, purified fiber yarn and various blended yarns spun on wool spinning equipment using wool fiber and wool chemical fiber as raw materials. In the wool spinning system, according to the different product requirements and processing technology, it is mainly divided into two spinning systems: carded wool spinning and worsted wool spinning. Among them, because the fluff raw material contains a large number of impurities, it must go through preliminary processing such as sorting, wool washing (opening, washing, drying), carbonization, etc. The hair that has undergone preliminary processing is called washed wool (carbonized net hair).

(1) Carded wool spinning system

The process and main functions of the carded wool spinning system are shown in Figure 1-6.

Figure 1-6 The process of carding and spinning system

Among them, the main difference between the woolen carding machine and the cotton carding machine is that it is equipped with a strip machine, which divides the wool net output by the carding machine into dozens of very narrow mesh belts, and then kneades them into strips to form roving. Because the drafting is only carried out on the spinning frame, the straightness and uniformity of the fibers in the yarn are poor, but it is conducive to the shrinkage of the product.

The carded wool spinning system is suitable for spinning coarse yarns with high thread density, mainly for weaving woollen wool, blankets and industrial fabrics as well as woollen knitted fabrics. The carded wool spinning system has good adaptability to raw materials, and can be used to develop woolen products with a variety of fibers such as wool, cashmere, camel hair, yak hair, rabbit hair, chemical fiber and recycled wool, so that fibers with different thread densities and lengths can be used reasonably. Woollen wool fabric has the characteristics of good pile shrinkage, plump feel, good elasticity and strong warmth.

(2) Combed wool spinning system

The worsted wool spinning process system has many processes and long processes, which can be divided into two parts: strip making and spinning, and the whole process of the spinning system is shown in Figure 1-7.

Figure 1-7 The whole process of the worsted wool spinning system

The production of the strip making part is also called topless manufacturing, and a separate factory can be set up, and its product, combed tops, can be sold as a commodity. Figure 1-8 shows the manufacturing process of wool tops.

Figure 1-8 Strip making process of combed wool spinning system

Some worsted woolen mills do not have a strip-making process, using commodity combed wool tops as raw materials, the production process includes pre-spinning and post-spinning, most factories also have strip dyeing and re-combing processes for tops dyeing and re-combing, re-combing refers to the second combing after the tops are dyed, and the process of re-combing is similar to that of strip-making. Figure 1-9 shows the flow of the combed wool spinning system without the re-combing process:

Figure 1-9 Combed wool spinning process without strip making

In addition, there is a semi-worsted spinning process system between combing and carding, which differs from the combing system in that it does not use a combing machine. The yarn produced is fluffier and softer than combed yarn, smoother and uniform than carded yarn, and the product style is between worsted and woollen yarn.

Velvet production generally uses a combed wool spinning system. Carpets and blankets generally use carded wool spinning systems. Yarns for knitting of special animal fibers are also mostly produced by carded wool spinning systems. The production of yarn for high-count fleece knitting and weaving in a combed wool spinning system or a cotton-wool spinning system through equipment modification and process adjustment can greatly increase the added value of the product.

3. Silk spinning system

The silk spinning process system includes the silk spinning system and the silk spinning system. The former has a small spinning density and is used to weave thin high-grade silk silk; The latter spinning yarn is dense, loose and fluffy, and has a unique style.

(1) Silk spinning system

1. Refining engineering

The silk processed from the cocoon and waste silk that cannot be reeled is used for weaving silk. Because the cocoon and waste silk contain a large number of impurities such as sericin, grease and wax, it is necessary to remove the grease and most of the sericin on the silk fiber through the refining process, so that the fiber is white and shows an inherent luster, and it is easy to loosen and open during spinning and processing. Refining is also known as the preliminary processing of silk, and the raw materials after refining are called fine cotton.

2. Cotton making project

The process flow of the cotton making project is shown in Figure 1-10. The task is to properly mix, carefully open and repeatedly comb the fine and dry cotton, remove impurities, cotton particles and short fibers, and make fine cotton with good fiber straightening parallelism, good separation and a certain length. The cotton making process of silk spinning is similar to the topless manufacturing of combed wool spinning systems.

Because the silk fiber is very long, it is necessary to use cotton cutting to cut the silk fiber into a certain length for the subsequent process of carding and drafting; The short fibers and impurities and defects are then eliminated by a circular combing or combing process.

Figure 1-10 Cotton making process

3. Silk spinning system

Figure 1-11 shows the spinning process of silk yarn after combing cotton, which is composed of drawing drawing engineering (including cotton distribution, two extensions, and three drawing frames (stripping)), roving engineering (including twisting and roving), spinning engineering, and post-processing processes such as twisting and finishing.

Figure 1-11 The process of the spinning system

(2) Silk spinning system

Silk spinning is the use of the cotton in the cotton making project in the final comb machine as raw materials, cotton spinning carding system, rotor spinning system or carded wool spinning system. The silk is particularly numerous, soft to the touch, and the surface has hairy and cotton knots, and its fabric is called cotton silk. Figure 1-12 shows the process flow of silk spinning.

Figure 1-12 Silk spinning process

Fourth, hemp spinning system

There are three spinning systems for hemp spinning: ramie, jute and flax.

(1) Ramie spinning system

Generally, the combed wool or silk spinning system is borrowed, and only partial improvements are made on the equipment. Raw hemp must first be pretreated and processed into fine and dried hemp. The spinning process is shown in Figure 1-13. Short ramie and flax can generally be processed in the cotton spinning system.

Figure 1-13 Ramie spinning system process

(2) Linen spinning system

The raw material of flax spinning is when it is beaten into hemp, and it is processed by the flax long linen spinning system, and the spinning process is shown in Figure 1-14, wherein the roving of long linen spinning yarn is processed after scouring. The falling hemp and back hemp of long hemp spinning enter the short hemp spinning system, and the process flow is shown in Figure 1-15.

Figure 1-14 The process of flax long linen spinning system

Figure 1-15 Flow of flax and staple linen spinning system

(3) Jute spinning system

The process flow of jute spinning is: raw materials→ raw materials preparation→ carding→ drawing → spinning

To sum up, the processing equipment of different spinning systems is different, but all spinning processes need to be processed by opening, impurities, mixing, carding, drafting, and twisting equipment.

Section 3 Classification and use of yarn

In general, yarn is used as a semi-finished product, mainly for weaving, including weaving (weaving), knitting, weaving, as well as sewing, embroidery, rope making, etc., and the yarn must meet the requirements of these downstream users for continued processing and final product application.

According to different divisions, yarns can be divided into many kinds.

1. Classification according to the composition of fiber raw materials

According to the fiber raw materials that make up the yarn, the yarn can be divided into pure spun yarn and blended yarn. Pure spinning yarn is a yarn spun from a kind of fiber, such as cotton yarn, wool yarn, hemp yarn and silk spinning yarn, polyester yarn, etc., cotton yarn is the largest type of pure spun yarn; Blended yarn is a yarn spun from two or more fibers, such as polyester and cotton blended yarn called polyester-cotton yarn, wool and viscose blended yarn, etc. Blended yarn fabrics can highlight the advantages of various fibers, and promote the strengths and avoid the weaknesses. Polyester-cotton blended yarn and its polyester-cotton blended fabric are the largest type of blended products.

2. Classification according to the thickness of the yarn

According to the thickness of the yarn, the yarn can be divided into coarse special yarn, medium special yarn, fine special yarn and extra fine special yarn. Taking cotton yarn as an example, coarse yarn refers to yarn of 32 and above, or 18 inch and below in the imperial system. This type of yarn is suitable for thick fabrics such as tweed, coarse plain cloth, etc. Medium yarn refers to 21~32 special, or 19~28 inch yarn in the imperial system. This type of yarn is suitable for medium-thick fabrics, such as medium plain cloth, gabardine, khaki, etc. Fine yarn refers to 11~20 special, or inch 29~54 inch yarn. This type of yarn is suitable for thin fabrics such as muslin, poplin, etc. Extra-fine yarn refers to yarn of 10 or less, or 60 and above in the British system, which is suitable for high-end fine fabrics, such as high-count shirts, worsted close-fitting wool sweaters, etc. The fineness unit of wool yarn is used to use the metric count, and the specific numerical range of coarse, medium and fine yarns is different from that of cotton yarn.

3. Classification according to spinning system

According to the spinning system, it can be divided into worsted yarn, woolen yarn, waste spinning yarn, etc. Worsted yarn, also known as combed yarn, refers to the yarn spun through the combing process. The fibers in the yarn have high parallel straightness, uniform dryness, smooth and clean, and are generally fine or extra-fine special yarns. Combed yarn is mainly used for high-grade fabrics, such as fine spinning, gabardine, tweed, woolen sweaters, etc. Woolen yarn, also known as carded wool yarn or carded cotton yarn, is a yarn spun by a woolen spinning system or a carded spinning system. In woolen yarn, there is more content of short fibers, poor parallel straightness of fibers, loose structure, more hairiness, and poor quality. It is used for general fabrics, such as woolen woolen fabrics, cotton fabrics above medium and special levels, etc. Waste spinning refers to yarn spun from textile scraps (waste cotton) or low-grade raw materials. The yarn is of poor quality, soft, uneven drying, contains a lot of impurities, and has poor color, and is generally only used to weave low-grade products such as cotton blankets, thick flannel cloth and packaging cloth.

Fourth, according to the use of classification

Yarn can be divided into woven yarn, knitting yarn and other yarns according to its use. Woven yarn refers to the yarn used to process woven fabrics or woven fabrics, which are divided into warp yarn and weft yarn. Warp yarn is used as a longitudinal yarn of fabric, which has the characteristics of large twist, high strength and good wear resistance; The weft yarn is used as a transverse yarn of the fabric, which has the characteristics of less twist, lower strength, but softer. Knitting yarn is the yarn used in knitted fabrics, with high yarn quality requirements, small twist and moderate strength. Other yarns include sewing threads, embroidery threads, braided threads, miscellaneous threads, industrial threads, ropes, cables, cables, etc. Depending on the application, the requirements for these yarns are different, and the spinning process is also different.

5. Other classification methods

According to the dyeing, finishing and post-processing technology of yarn, it can be divided into white yarn, bleached yarn, dyed yarn, singeing yarn, mercerized yarn, etc.; According to the spinning method, it can be divided into ring yarn, agglomeration yarn, composite yarn, rotor yarn, air-jet yarn, air-jet vortex yarn, vortex yarn, self-twisting yarn, etc.; According to the morphological structure of yarn, it can be divided into short fiber yarn, including single yarn, strand, rope and cable; filament yarn, including monofilament, multifilament, twisted yarn, textured yarn, etc.; Special yarns, including core-spun yarns, fancy yarns, bulky yarns, network yarns, etc.

Topic 1: Smart Spinning

Food for Thought:

1. What are the main functions of spinning? How?

2. What are the auxiliary functions of spinning? How?

3. How is the spinning system classified?

4. The process flow, main function and the name of semi-finished products and finished products of cotton spinning carding and combing system?

5. The process flow, main function and name of semi-finished products and finished products of wool spinning carding and combing system?

6. What are the classifications and uses of yarn?

Chapter 2 Raw material selection

What you need to know in this chapter:

1. Characteristics of fiber raw materials for spinning and their main process properties.

2. The purpose and principle of raw material selection.

3. Selection of natural fibers. Focus on mastering the selection method of cotton fiber, combed and carded wool fiber selection method.

4. The selection of chemical staple fiber varieties, the determination of blending ratio and the selection of fiber properties.

5. Selection of reused raw materials. Understand the source and treatment method of reused raw materials; Focus on mastering the selection of cotton spinning and wool spinning reuse raw materials.

概述

Fiber raw materials and their process properties

With the development of science and technology, on the basis of the original commonly used textile fibers, differentiated fibers, functional fibers, and high-performance fibers are more and more widely used in spinning production and product development; Today, when natural resources are protected, biomass fibers developed using biological technologies and waste fibers recovered by various treatment methods are bound to become important fiber raw materials for textile processing in the future. The emergence of these fiber materials has changed the raw material structure of traditional textile processing, the technical content of many textile fiber products has been greatly increased, the added value of textile products has been improved, and the application field of textile products has been further expanded, which has undoubtedly greatly promoted the development and progress of the textile industry.

For the spinning process, the variety of fibers that can be processed is also increasing, with different process properties. Table 2-1 shows the main process properties of commonly used fibers. In addition, the impurities and origin of the fiber are also the main process properties that affect the spinning process and the quality of its products.

Table 2-1 Main process properties of several commonly used fibers

Second, the purpose and principle of raw material selection

(1) The purpose of raw material selection

In the process of spinning and processing, the cost of fiber raw materials accounts for 65%~80% of the total cost of yarn, and raw materials need to be selected before being put into production. By combining fiber raw materials of different varieties, grades, properties and prices according to a certain proportion, the following purposes can be achieved:

1. Maintain the relative stability of product quality and production

Different fiber varieties have different properties. For natural fibers, there are differences in length, fineness and grade of the same fiber from different origins and different growth cycles. If the raw materials used in production and processing remain single in terms of variety, source and other aspects, due to their limited quantity, the production time can be short, which will inevitably lead to frequent replacement of raw materials, which is easy to cause fluctuations in the production process and product quality. Therefore, through the combination of a variety of raw materials, the comprehensive properties of the mixture can be kept stable, so as to maintain the relative stability of product quality and production process.

2. Rational use of raw materials

Depending on the purpose of the finished yarn, the requirements for its quality and characteristics are also different; Different spinning processes have different requirements for the performance of raw materials; On the premise of ensuring the quality of finished yarn, the cost of raw materials should be reduced. Therefore, through the selection of fiber raw materials, the raw materials can be used rationally and the production cost can be reduced.

3. Increase the variety of colors

In addition to the commonly used fibers such as cotton, wool, silk, linen and polyester, nylon, acrylic, etc., new biomass fibers such as soybean protein, bamboo, and Tencel, as well as functional fibers that are water-soluble, electrically conductive, radiation-proof, and ultraviolet-resistant, have been used in spinning production. At the same time, some high-performance fibers such as aramid, polyphenylene sulfide and polyimide have gradually entered the spinning field, and high-performance staple fiber yarns have been developed. Therefore, through the reasonable selection of different textile fibers and the use of their different properties, yarns with different characteristics can be developed, and the variety of designs and colors can be increased to meet the various needs of wearing, decorative and industrial yarns.

(2) The principle of raw material selection

1. Raw materials are selected according to the product use

Textile products have a wide range of applications, and their requirements for yarn properties are different, so the requirements for the selection of yarn raw materials are also different. In general, fine special yarn, combed yarn, single yarn, yarn for high-density fabrics, yarn for knitting, etc., have higher quality requirements for raw materials; Coarse special yarn, carded yarn, stranded yarn, printing and dyeing grey cloth yarn, sub-brand yarn, etc., have low quality requirements for raw materials; Yarns for special purposes should be made from raw materials according to different uses and the characteristics required by the product. Therefore, it is necessary to comprehensively consider the end use of the product and the different needs of users for the selection of raw materials.

2. Raw materials are selected according to process requirements

The spinnability of each raw material is different, and the spinning process suitable for spinning is different for the length and fineness of the fiber raw material; For a specific spinning process, under normal circumstances, the fiber length, linear density, impurity and other properties of each component in the mixture should not be too different from each other, so as not to cause processing difficulties and affect product quality and productivity. Therefore, it is necessary to select raw materials according to the requirements of the spinning process.

3. Options in the spinning system

All kinds of fiber raw materials that have been processed need to be selected and then entered into the various spinning systems. For pure spinning yarn or blended yarn with similar fiber properties and processing technology, the raw materials are mainly mixed in the form of bulk fibers, and their selection is generally located before the opening and processing of each spinning system, such as: the selection of cotton spinning system is carried out before the opening and cleaning process, and the selection of wool spinning system is completed before adding wool oil. For blended yarns with different processing properties, the various fiber raw materials are mostly mixed in the form of fiber slivers, and their selection takes place before the drawing process or the carding process.

　
Natural fibre options

1. Cotton fiber selection

Textile mills generally do not spin cotton fiber raw materials with a single mark, but use several with each other, which is called cotton blending. Due to the different varieties, origins, growth conditions, and initial processing techniques of cotton fiber raw materials, the length, linear density, maturity, impurities, moisture, and strength of the fibers are also quite different. The yarn quality and spinning process of cotton fiber are very closely related to the above factors. Therefore, the reasonable selection of cotton fiber raw materials and the use of a variety of marks are a very important work for the production of textile mills. There are two methods of cotton fiber selection, namely traditional cotton matching (classification and queuing method) and modern cotton matching (computer cotton matching method).

(1) Traditional cotton blending methods

The traditional cotton blending method, also known as the classification and queuing method, is generally used by the cotton blending engineer to select the appropriate raw materials from several raw materials for a certain yarn variety and determine the mixing ratio. This is a wide-ranging, large-scale work that relies on a wealth of practical experience.

1. Classification

According to the nature of raw materials and the different requirements of various yarns, the raw cotton suitable for the production of a certain product or a certain special number and purpose of yarn is selected and divided into a category, which can be divided into several categories. Generally speaking, in the same type of raw cotton, the grade difference of the fiber should be within 2~3 grades, the length difference should be within 2~4mm, and the linear density difference should be within 800 cm.

2. Queue up

On the basis of classification, the raw cotton in a certain cotton blending category is lined up according to the region, performance, length, linear density and strength and other indicators to facilitate batch use. After a certain batch number is used up, the raw cotton that is successively replaced (batched) in the same team should not have a significant impact on the performance of mixed raw materials. Generally speaking, in the same team of raw cotton, the grade difference of the fiber should be 1~2 grades, the length difference should be less than 2mm, and the linear density difference should be within 500~800 cm; Before and after receiving batches, the grade difference between the blended cotton is controlled within 1 grade, the length difference is less than 2mm, and the linear density difference is within 500 cm.

What to consider when sorting queues

The first thing to pay attention to when matching cotton is: (1) Highlight the main body. A few batches with similar properties are the main body, generally accounting for about 70%, but it should be noted that there should be no double peaks, but the allowable length is mainly in certain batches, and the linear density is mainly in other batches; (2) The number of teams is appropriate. If the total amount of cotton is large or the amount of raw cotton in each batch is small, the number of teams is more; The difference in the nature of raw cotton is small, and the number of teams can be less. Generally, 5~6 teams are better, and if the number of teams is small, the mixing percentage of each team is large, and the maximum should not exceed 25%; (3) Cross-offset. When receiving batches, the number of batches received on the same day should not exceed 2 batches, and the mixing percentage should not exceed 25%.

Table 2-2 lists the general control range of the main performance differences of raw cotton during batch acceptance.

Table 2-2 Control range of differences in raw cotton properties

Note: The average property index of blended cotton can be calculated according to the weighted average of the property index of each raw cotton in the blend and the percentage of mixed weight.

In addition, in the process of traditional cotton blending, the following factors need to be considered:

(1) to the cotton trend

For raw cotton with little stock and few sources, especially those with outstanding characteristics, it should be used less to ensure the sustainable supply of raw materials; Although there is a large stock, the raw cotton with difficult sources should also be used less; Although the stock is small, but the source is abundant, it can be appropriately used more.

(2) Balance of yarn quality indicators

There is often an imbalance in the quality indicators of yarn, such as some indicators are good and others are not good, or multiple indicators are good and a certain index is particularly poor, so corresponding adjustments should be made when cotton is matched.

(3) Climate change

Climate change has a great impact on the spinning process and yarn quality, such as high temperature and high humidity in summer, the fiber is easy to entangle rollers, rubber rollers and card clothing during processing, the number of broken ends increases, and the appearance defects of the yarn also increase.

(2) Modern cotton blending method

Modern cotton matching method, also known as computer cotton matching, uses artificial intelligence methods to simulate the whole process of cotton matching, through the analysis of raw material performance and yarn quality prediction, scientific selection of raw materials, can overcome the drawbacks such as large calculation workload and experience errors that vary from person to person, and realize the scientific management of cotton matching process.

1. The method of computer cotton matching system

At present, the theories and methods of natural fiber computer cotton matching system mainly include linear programming method, neural network method and genetic algorithm.

Linear programming

The basic theory of linear programming is fuzzy discriminant plus linear programming. Firstly, the fuzzy mathematical comprehensive evaluation technology was applied to select the raw material varieties, that is, the cotton distribution marks were determined by fuzzy calculation. Then, through linear regression analysis, a linear model of the relationship between raw material performance and yarn quality was dynamically established. Finally, the optimization algorithm was used to optimize the mixing ratio of the selected marks. The theory of this method is rigorous, and the cotton matching scheme can be optimized, but the premise of the implementation of this method is that the specific data of the performance index of the single mark and the quality of the yarn must be obtained (often obtained through the trial spinning of the single mark), so the method has a very large dependence on the test data, and at the same time, the dependence of fuzzy discrimination on the expert is very large, and the optimized ratio usually does not meet the requirements of the whole package of ingredients.

Neural network technology

A neural network consists of many nodes, each of which is a function that uses the weighted sum of the values of neighboring nodes that are input to the node. For spinning ingredients, a neural network system can be designed due to the variety of raw materials available, as shown in Figure 2-1. When it was first used, the scheme output by the neural network system was compared with the batching scheme designed by textile experts, and the neural network system was trained, and finally the optimal design of intelligent raw material indicators for spinning ingredients was realized. It is important to note that the learning and training of a neural network system may take a long time, and the results obtained are generally local best values.

Figure 2-1 Neural network of cotton matching

Genetic algorithms

Genetic algorithm is a new optimal spatial search method, which is different from neural networks, which continuously generates new offspring through mating between initial populations, and then generates new populations from newly generated offspring through survival of the fittest. And so on, and so on, and new populations continue to evolve until the desired evolutionary goal is reached. Therefore, the results of the optimization by gene algorithm are generally the global optimal or better, and the global optimal (better) scheme of the ingredients formed is generally not the only one, giving the decision-maker greater freedom.

2. Mathematical model of computer cotton matching system

In order to optimize the cotton blending project, an economic mathematical model should be established, for example, the objective function Z(X) of the total cost of the components of various mixed raw materials is:

k m

Z (X) = Σ Σ SiXij ( 2-1 )

i=1 j=1

where: S — the cost of component i in the mixed raw material; X _ij —J is a component of the mixed composition of i in the cotton mixture.

The purpose of cotton blending is to minimize the objective function, but the following constraints must also be met:

(1) The relative breaking strength of the spinning yarn spun from the J cotton composition shall not be lower than the relative breaking strength of the spinning yarn specified in the national standard, and the constraints are:

Σ（R_ij—R_j）X_ijαi≥0 ( 2-2 )

where: R _ij — the relative breaking strength of the j mixed components in the cotton mixture i spun into a spinning yarn (cN/tex) according to the formula of A.H. Soloviev;

Rj—the relative breaking strength of spinning yarn specified in the national standard (cN/tex);

α-i component spinning yarn production rate quota (%).

(2) The constraints of the average fiber characteristics of mixed raw materials are as follows:

k

ΣZ_iX_ij≤Z_j ( 2-3 )

i=1

where: the parameters of the fiber characteristics of the Z-i mixed component;

The allowable average value of a certain characteristic parameter of the fiber in the composition of Z-j cotton.

(3) The constraints of inventory quantity are as follows:

m

ΣB_jX_ij≤0.01A_iα_i ( 2-4 )

i=1

Where: B—the spinning planning task (t) produced by the cotton component of j;

Ai — the stock (t) of the mixed components in the warehouse at the beginning of the calculation.

(4) The constraints of the mixed components of I in the J cotton blend composition are:

0．01α_ij≤X_ij≤0.01b_ij ( 2-5 )

Where: α _ij and b _ij set the percentage range for the i mixed component in the j compound.

By using the computer to solve the above equations, you can get a reasonable combination of the mixed components of raw cotton, that is, the best selection.

3. The functional module of the computer cotton distribution system

The computer cotton matching system mainly includes three modules, namely raw cotton inventory management, automatic cotton distribution and yarn quality analysis. Among them, the theory and technology of automatic batching are the most complex. At present, with the diversification of spinning raw materials and yarn varieties, the computer batching system not only adapts to the automatic selection of natural fibers, but also can automatically select colored fibers and simulate the color yarn effect after the selection of colored fibers; With the rapid development of information technology, automatic batching has developed from single-objective optimization and selection to multi-objective optimization and selection.

Each subsystem of computer cotton distribution is provided with a plurality of specific functional modules, and each functional module can not only repeat its own operation independently, but also can return to the main control module to request the command to perform a new operation. Figure 2-2 is a block diagram of the computerized cotton distribution management system.

Figure 2-2 Block diagram of the computerized cotton distribution management system

(1) Raw cotton inventory management subsystem: The main function of this system is to do a good job in the account management of raw cotton inventory, provide data and basis for cotton distribution, and is the basis of computer cotton distribution. Its specific functions include raw cotton warehousing, raw cotton warehousing, inventory inquiry, account modification, and settlement at the end of the month.

(2) Yarn quality analysis subsystem: The main function of this system is to establish a dynamic mathematical model to provide data for analyzing the influence of mixed cotton performance and process parameters on yarn quality, as well as predicting yarn quality. It is a key link in computer cotton matching, and its specific functions include data input, establishment of dynamic mathematical models, query and modification, printing and tabulation, and providing analysis data for production for production reference.

(3) Automatic cotton matching subsystem: the main function of this system is to select the best replacement cotton batch, determine the appropriate composition percentage, and complete the cotton matching schedule according to the basic requirements of cotton matching work such as ensuring quality, stable production and reducing costs.

In actual production, computer cotton matching has been integrated into the ERP management system of the enterprise.

(3) Examples of cotton matching

Table 2-3 shows the composition and classification queuing table of cotton when spinning JC9.7tex and JC11.6tex yarns in a factory. The raw materials are divided into 8 teams, and the table lists the cotton batch, the percentage of cotton consumption and the fiber performance index after batching of the variety on different days.

Table 2-3 JC9.7tex/JC11.6tex classification and batching table of a factory

Second, the wool fiber is optional

Wool products have certain requirements for their strength, elasticity, wear resistance, style and performance, which are not only related to the characteristics of fiber raw materials, but also have a close relationship with the processing technology, therefore, the selection of raw materials must also be combined with the processing technology system.

(1) Selection of combed woolen raw materials

According to the characteristics of combed wool textiles, the requirements for combed wool yarn are: yarn count height, generally 45 ^s ~ 52 ^s , up to 100 ^s ； The fibers are arranged in parallel and straight, the surface of the yarn is smooth and clean, the uniformity of the strip is good, and the twist of the yarn is high. Therefore, the combed wool yarn also has high requirements for the quality of raw materials, mainly because the fiber should be fine, the fineness dispersion coefficient should be small, the length of the fiber should be long, and the length dispersion coefficient should be small. However, due to the different origins, varieties and properties of wool, in order to meet the quality requirements of combed wool tops and combed wool yarns, the method of wool matching is often used in production to reasonably match and use raw materials, so as to achieve the purpose of learning from each other's strengths, expanding batches, reducing costs and stabilizing product quality. The experience of wool production practice in China proves that when combed wool textiles use national wool raw materials, they adopt a planned collocation (i.e., wool distribution) according to region, quality, variety and use, which is extremely important to improve the quality of worsted products.

In the combed wool spinning system, there are two ways to select raw materials, namely comb strip with wool (loose wool selection) and mixed strip with wool (wool top selection).

1. Comb strips with hair

Comb strip with wool, also known as loose wool selection, that is, several different fiber raw materials are appropriately matched to ensure the quality of the finished wool top, and to keep the quality of the same batch of wool tops stable, to meet the requirements of improving the quality of combed wool yarn. In the design of comb wool matching, one or two batches of raw materials with similar quality should be selected as the main hair, and then other raw materials that can make up, improve and improve the mixed quality should be selected as the wool matching, which is called the main body hair matching method. The selection of the main body hair is generally based on length and linear density.

(1) Based on linear density

The linear density of the main body wool and the mating wool is determined according to the requirements of the wool strip standard, and the amount of use should be considered. When the linear density of the main body hair is thicker than the standard hair, the mating hair should be finer; On the contrary, the mating hair should be coarse. In general, the difference in average linear density between the main hair and the mating hair should not exceed 2 μm. The average linear density of the mixed wool should be about 0.5 μm thinner than the standard average linear density of the finished wool tops, so as to prevent the average linear density of the fibers in the finished wool tops from becoming thicker due to the elimination of combed wool during processing.

(2) Based on length

Generally, a kind of hair with a short hair bush length is selected as the main hair, and the main hair component accounts for more than 70% of the total hair composition. A portion of the longer length of the wool is added to improve the average length, reduce the content of short fibers, and reduce the dispersion coefficient of the length. Fine-branched wool with a hair bush length of more than 95 mm and wool that is too short should not be used as the main hair. The difference in the length of the hair bush between the main body hair and the mating hair is generally not more than 20mm. The total amount of mating wool should not exceed 30%. If the difference in the average length of the hair bush is less than 10mm, it can be divided into the main hair and the mating hair.

2. Mixed strips with wool

Mixed strips with wool are also known as wool strip selection. As the name suggests, the fiber semi-products used in this kind of wool matching are wool tops, that is, the wool tops of different colors and different properties are evenly mixed to meet the requirements of increasing the variety of colors and ensuring product quality. When mixing pure wool tops, the linear density index of the fiber is mainly considered. Because a certain number of fibers should be maintained in the yarn cross-section. When the density of the yarn is the same, the finer the fiber, the more the number of fibers in the yarn cross-section, and the higher the yarn strength. When the number of fibers in the yarn section is constant, the finer the fiber, the finer the yarn can be spun. Under normal circumstances, if there are more than 40 fibers in the cross-section of worsted pure wool yarn, the spinning process can be carried out smoothly. The line density of raw materials is generally selected according to this principle. Table 2-4 shows the relationship between the quality of the top and the actual spinning density of the yarn.

Table 2-4 Relationship between the quality of wool tops and the yarn spun density

If the fiber length is long, the length dispersion coefficient is small, the short hair rate is low, the linear density dispersion coefficient is also small, and the strength and holding force are good, the average number of fibers in the yarn section can be reduced to no less than 35.

The length of the fiber is closely related to the strength of the yarn and the dryness. The average length of the fiber is long, and the yarn strength is high; There is a large difference in length, and the yarn strip is poorly dry. Generally, the average length is required to be more than 70mm. If several batches of wool tops with different average lengths are selected, the difference in the length of each batch shall not exceed 10mm, so that the uneven drying rate of the finished yarn will not be too large.

(2) Selection of raw materials for carded wool spinning

There are many varieties of carded wool fabrics, a wide range of uses, small batches of products, a wide range of fiber raw materials, and large performance differences. Therefore, it is particularly important for the raw materials to match each other, learn from each other's strengths, and mix them thoroughly. However, this also makes the selection of raw materials more complex than other products, and it is necessary to understand the characteristics of carded wool spinning raw materials, according to the different requirements of the product, style characteristics, production costs and different processing technologies.

1. Fiber raw materials for carded wool spinning

The carded wool spinning process is short, the number of spinned wool yarns is low, the spinning yarn draft is small, and the adaptability to raw materials is high, so most of the fibers can be processed on the carded wool spinning process. As far as wool is concerned, there are improved wool, outer wool, soil seed wool, combed short wool, lower foot hair and regenerated wool; In addition to wool fibers, other animal fibers such as cashmere, mohair, camel hair, rabbit hair, viscose, nylon, polyester, acrylic fiber, and hemp and cotton fibers can be used as woolen raw materials for blending with wool fibers. It not only expands the raw material resources of wool spinning processing and reduces the cost of products, but also through blending, it can also use the more uniform physical properties of other fibers to make up for the lack of some physical and mechanical properties of wool fibers, improve the process conditions and product quality, improve the spinning performance of the mixture, and enhance the fastness of the fabric.

2. Selection of fiber raw materials for carded wool spinning

(1) Selection is made according to the characteristics of the fiber raw material

(1) Blending of different varieties of wool

Regardless of improved wool and soil wool, the properties of wool in different regions and varieties are very different. When designing fabrics and selecting raw materials, fibers with similar linear density should be selected as much as possible. In addition to the linear density, factors such as the origin, length, strength, feel, elasticity, shrinkage performance, luster, and impurities should also be considered. If it is a high-count, thin, light-fleece, non-drawn fabric, it is necessary to choose a mixture of fibers with uniform thread density and slightly longer length.

(2) Blended with chemical fibers

When selecting chemical fibers and wool for blending, the selection of chemical fiber parameters and the mixing ratio have a great relationship with product quality and processing technology, and the length, linear density and mixing ratio of chemical fibers need to be considered when selecting.

The length uniformity of chemical fiber is good, and the proper selection can improve the uniformity of fiber length distribution in the mixture, which is conducive to improving the drafting conditions and improving the quality of spinning. In the production, with the different length of the blended wool, the length of the chemical fiber also has different specifications, when blended with fine wool, the length of the chemical fiber can be 55~65mm; When blended with semi-coarse wool, the length of chemical fiber should be 60~70mm.

The linear density of chemical fibers is uniform, while the linear density of wool fibers is more discrete, and the discrete degree of fiber linear density in the mixture can be reduced after mixing, which is higher than that of wool alone. Spinning performance is closely related to fiber thread density, the finer the fiber, the higher the number of spinning threads. In order to improve the number of spinning counts of the mixture, chemical fibers thinner than wool are often used, but the difference should not be too large, otherwise the uniformity of the fiber thread density in the mixture will be reduced, which will affect the uniformity of the strip drying. In addition, the chemical fiber is too fine, and the carded steel wire card clothing cannot be combed, and the hair particles increase. Therefore, the selection should be based on two factors. Generally, the thread density of chemical fibers blended with fine wool is 2.25~3.6dtex, and the density of chemical fibers blended with semi-coarse wool is 3.6~5.4dtex.

Chemical fibers can improve some physical and mechanical properties of blended yarn in blending, but also reduce some properties, such as pile shrinkage, softness, appearance, etc. Therefore, when choosing the blending ratio, in addition to considering the product use and cost, the style and feel of the fabric should also be considered. Generally, when spinning heavy shrinkage fabrics, the proportion of chemical fiber should be smaller; When used for light-fleece fabrics, the proportion of chemical fibers is larger. Production practice has proved that the amount of chemical fiber mixture is less than 30%, and the fabric can still maintain the wool feeling.

(3) Blended with other animal fibers

Woolen products are often mixed with certain rabbit hair, cashmere, camel hair, yak hair and other special animal fibers to produce high-end products.

For example, rabbit/wool products. Rabbit fur is characterized by softness, good luster, well-developed aerated pith layer, light fibers, good warmth, and its thermal performance is much better than that of sheep wool. However, there is no curl (rabbit fluff has a shallow wavy curl), and the pidulla layer is well developed, so the holding force is very poor. If the mixing ratio is too large, it is more difficult to spin. The breaking strength of single fibers of rabbit hair is much lower than that of wool, and the large mixing ratio will reduce the strength of the yarn. Usually rabbit hair is mixed with 40%~50%, which can make the product show the characteristics of softness, good luster and beauty.

Another example is the cashmere coat. Cashmere has bright luster, good linear density, and the average diameter of fluff is 14.5~16.5μm, with irregular curls. The villi fibers are made up of a layer of scales and a cortical layer, and there is no pith of the hair, so it is soft to the touch. Generally, cashmere can be mixed with 50%~60% or lower in the mixture.

(4) Blended with natural cellulose fibers

The use of cotton fibers in blends can increase the strength of yarn and fabric, but will reduce the pile shrinkage and elongation of the fabric, which used to be only slightly incorporated into some products such as flannel, and has been rarely used in recent years. Mixing part of the hemp fiber into the mixture can increase the strength of the product, but the elongation, down shrinkage, hand feel, and elasticity will be reduced, so it should be controlled within 30% when used.

(2) Select raw materials according to the style characteristics and quality requirements of the fabric

For different types, different uses and different styles of fabrics, there are different requirements for the composition of the mixture.

In fine woolen fabrics, such as melton, made of fine wool, heavy shrinkage, non-brushing, tight texture fabric, the surface is full, fine and smooth, not exposed, the body bones are tight and firm, elastic, wear-resistant, and pilling-resistant. Therefore, the raw materials used in pure wool melton should be 64 ^s or more than 80% ^s of the quality of the wool is close to 64, and the proportion of combed short wool is less than 20%; More than 50% ^s of the raw materials used in blended melton ^s are 64 or the number of quality is close to 64, less than 20% is combed short wool, and 30% is chemical fiber. Navy, generally made of fine wool, after shrinking or shrinking the fleece lightly drawn plain fabric, the surface is required to be plump and flat, basically not exposed, feel very solid and elastic, pilling resistance. The raw materials used in pure wool navy tweed should be 60 ^s wool or 70% ~ 90% of the first ~ second grade wool, 10% ~ 30% of the combed short wool, and the raw materials of blended navy tweed should be 60 ^s wool or more than 40% of the first ~ second grade wool, less than 30% of the combed short wool, and 30% of the chemical fiber.

In the coarse woolen fabric, such as uniforms, it is a plain fabric that is lightly brushed after being shrunk or shrunk by coarser raw materials, which requires a smooth surface, an inconspicuous exposed bottom, a solid feel, and pilling. Therefore, the raw materials used in pure wool uniforms are 3~4 grade wool accounting for 70%~85%, and combed short hair 15%~30%; The raw materials used in blended uniforms are 3~4 grade wool and combed short wool, accounting for 70% and chemical fiber 30%. Volkswagen is a fleece fabric made of fine combed short wool and recycled wool blend, which requires a fine and smooth surface, basically no bottom, a tight texture, and pilling resistance. Therefore, 40%~60% of pure wool is used for pure wool and above hair, and 40~60% is used for combed short hair and lower foot hair; Blended Volkswagen is less than 30% of the second-grade wool, more than 35% of the combed short hair, more than 35% of the lower foot hair, and more than 35% of the chemical fiber.

In the heavy pile fabrics, such as the wool coat, the fabric that has been shrunk and brushed, has a rich texture and good warmth, and requires the suede to be dense and neat, well shaped, fat, and soft and not loose. Therefore, the raw materials used in pure wool hair coats are more than 80% of the wool above grade 4 (the length is required to be long, and there is a good luster, usually mixed with some mohair), and the combed short hair is less than 20%. The blended wool coat is made of more than 50% of the fourth-grade wool, less than 20% of the combed short wool, and 30% of the chemical fiber.

Water pattern jacquard blanket, rich texture, water ripple on the surface, good luster heavy lifting fabric. When selecting raw materials, longer fibers should be used as the main raw materials (the average length is more than 65mm), accounting for 80%, and the fiber should be glossy.

For non-shrinking or light-shrinking non-brushing products, raw materials with uniform fineness, good hand feel and medium to long length should be selected.

(3) Raw materials are selected according to the requirements of yarn use

Due to the different requirements for the strength of the warp and weft yarns during weaving, there are different requirements for the mixing composition of the warp and weft yarns. The breaking length of the warp raw material should be higher than that of the weft raw material. Generally, the warp yarn is made of fibers with greater strength and longer length to ensure that the warp yarn has sufficient strength; Some shorter fibers can be used for weft yarns, such as some combed short hairs, to improve the feel of the fabric and increase the downage. For weft, also pay attention to the fiber luster.

(4) Select raw materials according to the requirements of processing technology

When selecting raw materials, it is necessary to take into account whether the processing process can be guaranteed to run smoothly. If the number of spinning yarns is high, the linear density of the selected raw materials should be fine, the dispersion coefficient of linear density should be small, and the proportion of long hair should be larger, otherwise it will increase the spinning breakage. If the spinning yarn count is low, the raw materials used can be poorer, the short hair content can be larger, and some regenerated wool can be mixed. If there is more scraps and recycled wool in the mixture, a certain amount of viscose fiber can be incorporated to improve the average linear density of the mixture, increase the strength and reduce the breakage. The length and linear density of various fibers that make up the mixed raw materials should not be too different, otherwise it will increase the difficulty of processing.

(5) Select raw materials according to the color requirements of the product

As far as the color of wool fabrics is concerned, there are plain fabrics and floral fabrics; As far as fabric dyeing is concerned, there are two types of dyeing, horse dyeing and loose hair dyeing. The so-called plain fabrics (i.e., single colors) are mostly horse dyed, and the pattern fabrics are mostly scattered dyed. In recent years, according to the different properties of different fibers to different dyes, different fibers are used to form textures during weaving, and the colors are obtained after dyeing.

Color mixing refers to the fiber part or all of the mixture is dyed, generally including more than two colors, called color spinning, in the textile industry, color spinning accounts for about 15%. Wool yarns and fabrics made from colour blends do not need to be dyed. This method is also suitable for cotton spinning production.

When configuring the color mixture according to the color of the finished product, the following points must be noted:

(1) The raw materials that are tangled into blocks shall not be added to the color mixture, because it is not easy to mix with other fibers evenly;

(2) The color to be displayed on the fabric should be dyed on the wool with bright color, and its length should be shorter and the fineness should be coarse;

(3) In order to ensure uniform distribution in the mixture, the colored components should be pre-combed once on the carding machine;

(4) Due to the relationship between the amount of hair falling of the carding machine, it is necessary to do a small amount of hair matching, test combing, and verify the color to meet the requirements of the finished product;

(5) In the dyeing and finishing process, because the washing, shrinking, carbonization and other processes need to be reacted by chemical agents such as soap, alkali and acid, which will cause color changes, and must be considered in the design of the mixture.

(6) Raw materials are selected according to the cost of fiber raw materials

The raw material cost of wool textiles usually accounts for more than 75% of the total cost, and the composition of mixed raw materials has a great relationship with the cost of wool textiles, so it should be considered when selecting raw materials. On the premise of ensuring product quality, try to select lower-grade raw materials and weave higher-grade products with lower-grade raw materials.

3. Other natural fibers are optional

(1) Hemp fiber selection

The selection of hemp fiber raw materials is mainly based on the linear density, strength, degumming and defects of single fibers or process fibers.

1. Optional flax fiber

The selection of flax fibers basically adopts the classification and queuing method. Flax fibers include beaten hemp (long and short fibers) and carded hemp (long and short fibers). Classification is to stack the beaten hemp and carded hemp according to the origin, hemp number and color. The queuing is basically similar to the queuing in the cotton fiber option. The selection of flax fiber is divided into long hemp spinning with hemp and short hemp spinning with hemp.

(1) Long hemp spinning with hemp

(1) The range of difference control between the components in the hemp preparation scheme is: the difference in splitting degree (linear density) is not greater than 100dtex (100 metric branches); The difference in strength is not more than 58.8N (6kgf), the difference in length is not more than 100mm, and the difference in deflection is not more than 10mm.

(2) The difference between the combination scheme and the replacement scheme adopted in the queue is as follows: the difference in splitting degree is not more than 200 dtex (50 metric branches), the strength difference is not more than 9.8N (1kgf), the length difference is not more than 50mm, and the deflection difference is not more than 5mm.

(3) Wet-spun long hemp yarn should be equipped with fibers with high splitting degree, that is, fibers less than 20 dtex (more than 500 metric counts). Dry-spun long linen yarns can be made with fibers with a fineness greater than 20 dtex.

(4) The precautions for long hemp with hemp are as follows:

a. The splitting degree of carding into hemp should be about 2.5 tex (400 metric branches);

b. The content of hemp shavings should not be too much when wet spinning;

c. The correlation between the strength and splitting degree of carded flax fiber is: the strength of fiber 9.8N (1kgf) is equivalent to 33.3 tex (30 male branches) splitting degree, which can be adjusted with reference to this index when mixing hemp;

d. The deflection of the fiber is 1mm, and the strength is 0.98N (0.1kgf);

e. When the length of the hemp bundle is different, it is necessary to match the hemp on the drawing frame separately after the stripping machine is formed.

(2) Short hemp spinning with hemp

(1) The range of difference control between the components in the hemp blending scheme is that the difference in splitting degree is not more than 10tex (100 metric branches), the difference in strength is not more than 49N (5kgf), the difference in length is not more than 40mm, and the difference in deflection is not more than 10mm.

(2) The difference between the hemp matching scheme and the replacement scheme used in the short hemp queuing is that the difference in splitting degree is not more than 20 tex (50 metric branches), the strength difference is not more than 0.49N (0.5kgf), the length difference is not more than 20mm, and the deflection difference is not more than 5mm.

(3) The precautions for short hemp with hemp are as follows:

a. Coarse linen or impermeable linen from the flax raw material factory, the wet spinning process can spin low-count yarn;

b. The correlation between the strength and splitting degree of carded staple hemp fiber is: the strength of fiber 9.8N (1kgf) is equivalent to 40 tex (25 cm) splitting degree, which can be adjusted with reference to this index when mixing hemp;

c. The content of staple fibers below 50 mm should be strictly controlled;

d. Wet-spun staple linen yarn should consider hemp particles (hemp knots) index, while dry-spun staple linen yarn can not be considered.

In short, the selection of flax fiber is based on the special number of carded hemp, and the fiber length is considered. The fine yarn should be combed into a fiber with high hemp splitting, fine linear density, long length, less impurities and high strength. Combed yarn should be made of hemp fiber with good length uniformity and less short fiber content. The linen yarn used for pickling cloth of primary color should be spun with fiber with the same color to avoid defects such as fancy spots in the product.

2. Optional ramie fiber

Peeling off the cortex, including hemp and bast, from ramie stems is called peeling. Peeling off the hemp skin is called scraping. The bast obtained after peeling and scraping is called raw hemp after drying, that is, ramie textile raw materials. The quality of raw hemp from different origins, varieties, grades and harvest seasons varies greatly, even in different parts of the roots, middle and tips of the same plant. Therefore, it is necessary to scientifically manage raw hemp and use it rationally to meet the needs of different products. Raw hemp selection is the most important part of raw hemp management, which is of great significance for stabilizing production and reducing costs.

Raw materials are selected according to the density of fiber threads

When selecting, the linear density of the fiber is first considered, combined with its length. Because the thread density is fine, the fiber with long length can be spun into fine special yarn to produce light and thin high-grade fabrics; Medium-density fibers are used for mid-range fabrics; Coarse fibers are commonly used in industrial yarns and heavy fabrics.

In general, the fine yarn is below 20tex (more than 50 nm), the fiber density is less than 5.56 dtex (more than 1800 nm), the medium yarn is more than 21.7tex (less than 46 nm), and the fiber density is 6.25 dtex ~7.14 dtex (1400 Nm ~1600 nm); The coarse yarn is above 62.5tex (below 16Nm), and the fiber density is 7.14 dtex ~10.00 dtex (1000 Nm ~1400Nm) of raw hemp.

While considering the density of the fiber thread, it is also necessary to consider whether the spun yarn is used for clothing or non-clothing; whether it is used for pure spinning, blending or interweaving; Warp or weft and so on. The linear density, strength and other performance differences of each batch of raw hemp used should be minimized.

(2) Raw materials are selected according to the processing technology

The selection of ramie is directly related to the processing technology. If the wool spinning process is adopted, all kinds of fine and dried hemp are opened separately into rolls, and the hemp cake is mixed in proportion when fed on the carding machine. If the silk spinning process is adopted, all kinds of fine and dry hemp are sorted separately and mixed in proportion on the extension machine. The replacement of mixed ingredients should be carried out in a single way, and the proportion of replacement should not be too large, and the quality of the replacement hemp should be as close as possible.

(2) Silk cotton fiber selection

The selection of silk spun wool is commonly known as blending, and the selection of spun wool is usually carried out in two stages. The first stage is the selection of fine cotton, and the second stage is the selection of fine cotton.

1. Dry cotton is optional

All kinds of silk spinning raw materials are refined and degummed to make fine cotton. According to the source of raw materials, the nature and the quality requirements of the spun silk, several kinds of fine cotton (including cocoon clothes) are mixed into mixed cotton in a certain proportion for the use of fine cotton. The number of types of mixed foam mainly depends on the size of the factory, the variety of products, the supply of raw materials and the cotton making process.

Factory size

The large-scale factory that adopts the circular carding cotton making process has many machines and a large amount of raw materials, and can produce a variety of silk at the same time. Therefore, there are more types of hybrid foams. There are fewer small factories.

Carding process

When the circular carding process is adopted, the comb fold and fiber length of the high-grade and high-grade raw materials are quite different, and according to the characteristics of the raw materials, there are more varieties of mixed cotton. Under normal circumstances, the lean cotton of large factories is mixed into 3~4 kinds of mixed cotton, and small factories are mixed into two kinds. When the combed cotton process is used, there is no significant difference in the carding and fiber length of the high-grade and low-grade raw materials, so regardless of the size of the factory, only two kinds of mixed cotton are usually formulated.

Cotton matching method

In order to control the quantity, adapt to the characteristics of the intermittent work of the cotton opener and better mixing, most of the lean cotton adopts the small amount of cotton blending method. According to the requirements of the number of cotton matching processes, the various components of the fine cotton are weighed respectively, and the mixed cotton is prepared into a part, each part is a blended cotton ball, and the raw materials of mulberry silkworm silk spinning weigh 400~500g per ball, and are processed separately with a cotton machine. According to the advantages and disadvantages of the raw materials used, the blended cotton balls are divided into special grade, grade A, grade B, grade C and grade D. The premium ball is mainly composed of long vomit; Both the C and D balls are made from a combination of low-grade raw materials.

The raw materials of silkworm silk spinning are relatively simple, and the production of silk is less, so most of the mixed cotton is mixed into two. The weight of the blended cotton balls can also be slightly heavier.

2. Cotton is optional

The fine cotton is combed by 2~3 round combs and then made into fine cotton. The quality of these fine cotton varies greatly, not only in length, uniformity, linter rate, etc., but also in color, cotton particles, fiber strength and other aspects. Therefore, in order to stabilize the quality of silk and reduce quality fluctuations, it is necessary to select fine cotton.

At present, the method of fine cotton selection is still based on experience, preliminarily determining the composition of cotton, through trial spinning, and then adjusting the composition of cotton according to the quality of the test spinning product until the specified quality indicators are reached. In the selection of fine cotton, the average length of the fiber, the length uniformity and the short fiber rate and other factors are mainly considered, and the mixed cotton of fine special silk is mainly Grade A ball No. I fine cotton, and some No. II fine cotton can be appropriately mixed according to the quality requirements of the silk; The mixed cotton of medium and special silk is mainly No. 2. fine cotton of Ball A or No. 1 fine cotton of B ball, and a small amount of fine cotton can be mixed into Ball A No. 1 as appropriate; Coarse special silk can be used in low fine cotton.

Section 3 Selection of chemical staple fibers

Chemical staple fiber is a large category of spinning raw materials, which can be pure spinning, blended with various natural fibers, and blended with different chemical staple fibers. Its purpose is to give full play to the excellent characteristics of various fibers, learn from each other's strengths, meet the requirements of different uses of products, increase the variety of colors, expand the source of raw materials and reduce costs. The selection of chemical staple fibers includes the selection of fiber varieties, the determination of blending ratio and the selection of fiber properties.

First, the selection of fiber varieties

The selection of chemical fiber varieties plays a decisive role in blended products, therefore, different varieties should be selected according to the different uses, quality requirements and processing performance of chemical fibers. There are many varieties of chemical fibers, but the most widely used in spinning are polyester, viscose, acrylic, nylon and other staple fibers.

(1) Select fibers according to the use of the product

Different products have different uses and require different fabric styles and wearing properties. For example, the yarn used for knitted underwear is required to be soft, evenly dry, and hygroscopic, so it is advisable to choose viscose fiber, vinylon or acrylic fiber blended with cotton; The materials used for sports and leisure outerwear are required to be strong and wear-resistant, soft and shaped, and polyester, nylon, spandex and cotton blends are mostly used; Woolen woolen wool requires a rich and fine surface and a soft feel, and can be blended with viscose, acrylic and wool.

(2) Select fibers according to product performance requirements

Due to the different use environment and conditions, the product has different requirements for one or several properties, and the selection of appropriate fibers can play a role in improving and reinforcing. For example, due to the high price of wool products, people often want to improve the wool spinning performance and fabric wear resistance, and can use more than two chemical fibers and wool blends to complement each other's strengths and reduce costs; In order to improve the wrinkle resistance and elasticity of hemp fabrics, polyester and hemp blends or polyester, strong fibers (high-strength viscose) and hemp blends can be used; Cupra fiber pure spinning or blended with wool and synthetic fibers, its fabric style is similar to silk, very drape, and has excellent wearing performance, suitable for knitting and woven underwear, shirts, windbreakers, coats, etc. In addition, through the selection of differentiated fibers, special properties can also be obtained, such as the selection of cationic polyester and wool fiber blending, can be dyed at room temperature and pressure, the product has different hemp ash dyeing effect, but also reduce the cost of fabric.

Second, the determination of the blending ratio

(1) Determine the blending ratio according to the product use and quality requirements

There are a number of factors to consider in determining the blending ratio, mainly the product use and quality requirements. For example, the materials used in the outerwear are required to be crisp, wear-resistant, shape-keeping, iron-free, anti-pilling, etc. The materials used in underwear are required to be hygroscopic, breathable, soft, and clean. In addition, it is necessary to consider the post-processing conditions such as processing, dyeing and finishing, and the cost of raw materials.

With the increase of the proportion of polyester fiber, the strength, wear resistance, crispness, shape retention, and iron-free properties of products containing polyester fiber have improved, but at the same time, their moisture absorption, air permeability, stain resistance, dyeing, and pilling resistance have become poor, and the difficulty of spinning has also increased. When polyester and cotton fiber are blended, the proportion is mostly 65% polyester and 35% cotton, and the comprehensive performance of the fabric is the best; When it contains more than 80% polyester, the air permeability of the fabric is significantly worse, and the spinning performance is also poor; When it contains 40%~50% polyester, it has better moisture absorption and air permeability, but the iron-free property is significantly worse than that of 65% polyester, which is suitable for underwear; When it contains 35% polyester, it is easy to dye and fleece, which is suitable for making fleece fabrics; When the polyester content is less than 20%, the properties of polyester cannot be revealed. When polyester is blended with wool, it can significantly improve wrinkle recovery, abrasion resistance and shrinkage. Polyester and linen blends, if the proportion of polyester is too high, the moisture absorption and comfort performance of the same blended fabric will deteriorate.

In the blended products of viscose fiber and other fibers, the proportion of viscose fiber is generally about 30%. At this time, the wool/viscose fabric still has a hairy feel; When the viscose fiber is 50%, the hair shape becomes worse; When it contains 70% viscose, it shows the style of viscose products, and the wrinkle resistance is very poor, and it is easy to form a bag. The use of viscose fibers in polyester can improve the moisture absorption and wearing comfort of the fabric, ease the porulation of the fabric, and reduce pilling and static electricity.

Acrylic and other fibers are blended, which can give full play to the fluffy and soft, warm and brightly dyed characteristics of acrylic, and the mixing ratio is generally 30%~50%. With the increase of the mixing ratio, the abrasion resistance and wrinkle recovery of the fabric become poorer.

When nylon is blended with other fibers, although the mixing ratio is small, it can also significantly improve the strength and abrasion resistance of the fabric. Cotton/nylon, viscose/brocade blended with 15%~30% brocade is appropriate, if the content exceeds 50%, pilling and static electricity will be aggravated. Wool/brocade blending is better with 7% ~ 10% brocade, when the brocade is more than 20%, the tensile performance of the fabric becomes poor, easy to pill and not resistant to ironing.

When vinylon is blended with other fibers, cotton/dimension and viscose/dimension are better to contain 50% of vinylon, if there is too much vinylon, the fabric will be stiff and the spinning performance will be poor.

Spandex is blended with cotton, wool, polyester and other fibers, the fabric is silky and more elastic and elastic recovery properties, the fabric has good extensibility, and it is more comfortable to wear. However, the proportion of spandex is generally very small, less than 10%, and the proportion of most products is about 5%, but the fabric has about 15% of the comfort and elasticity. At the same time, in woolen products, 5% spandex and wool blended products can be marked with pure wool to reduce the cost of raw materials.

(2) The effect of blending ratio on yarn performance

The strength of blended yarn depends not only on the strength of each component fiber, but also on the difference in the elongation at break of each component fiber. Fibers with different elongations at break are blended with each other, and when stretched by external force, the fibers of each component of the blended yarn produce elongation at the same time, but the stress inside the fibers is different. First, the fiber with a large initial amount is subjected to stress, and when it continues to stretch until the elongation exceeds the elongation at break of the fiber with lower elongation, the fiber breaks first. In this case, the load is all borne by the fibers with a large elongation that are not broken. Soon, the fibers break. The different temporalities of fiber fracture of each component make the strength of the blended yarn usually much lower than the weighted average of the strength of the pure spinning yarn of each component. Therefore, the blending ratio has an impact on the strength and elongation at break of the blended yarn.

When the same blending composition and blending ratio are different, there is the lowest strength point of blended yarn at a certain blending ratio, and the blending ratio at this time is called "critical blending ratio", and its value should be determined by actual experiments. For example, when polyester and cotton are blended, when the polyester content is less than 50%, the strength of the blended yarn decreases with the increase of polyester content; When the polyester content is higher than about 50%, the properties of the two fibers are different, but the strength of the blended yarn increases with the increase of polyester content. When the polyester content is about 50%, the strength of the blended yarn is at the lowest value, as shown in Figure 2-3. Curve 1 is 14.5 tex polyester/cotton yarn (high-strength and low-stretch polyester), and curve 2 is 14.5 tex polyester/cotton yarn (ordinary polyester). However, with the improvement of people's living standards, more attention is paid to the style and comfort of products, and no longer the pursuit of wear-resistant and durable products, as well as the improvement of processing technology, the blending ratio of polyester/cotton products on the market is about 50:50.

Figure 2-3 Relationship between polyester/cotton blend ratio and strength of blended yarn

From the perspective of improving the strength of blended yarn, the selection of the strength and elongation of the fibers of each blended component should be as close as possible. When using high-strength and low-elongation polyester and cotton blending, because the strength and initial amount of polyester are higher than cotton, the utilization rate of fiber strength can be improved, and the yarn strength is high, which can improve the spinning and weaving production efficiency; When ordinary polyester and cotton blends are selected, the strength and abrasion resistance of the fabric can be improved because the elongation at break and the breaking work of polyester are larger than those of cotton, but the utilization rate of fiber strength is reduced, and the yarn strength is also reduced. At present, it is mostly blended with medium-strength medium-stretch polyester and cotton. If polyester is blended with wool, low-strength and high-elongation should be used to make its strength and elongation close to that of wool.

3. Fiber properties are selected

After the variety and blending ratio of chemical staple fiber are determined, the performance of the product cannot be completely determined, because the various properties of the blended fiber, such as the difference in length, linear density and other indicators will directly affect the performance of the blended yarn product.

(1) Selection of the length of chemical staple fibers

The length of chemical staple fiber is divided into different specifications such as cotton type, medium length type and wool type. The length of cotton-type chemical fiber is 32 mm, 35 mm, 38 mm and 42 mm, which is close to cotton fiber but slightly longer, and can be processed on cotton spinning equipment; The length of medium-length chemical fibers is 51 mm, 65 mm and 76 mm, etc., and is usually processed on cotton-type medium-length equipment or carded wool spinning equipment; The lengths of wool chemical fibers are 76 mm, 89 mm, 102 mm and 114 mm, etc., and are generally processed on wool worsted equipment.

The length of the fiber also affects its distribution in the yarn cross-section. Usually longer fibers are easy to concentrate in the core of the yarn, so the chemical fiber blend that is longer than the natural fiber is selected, and most of the natural fibers in the yarn will be in the outer layer, so that the appearance of the yarn is closer to the natural fiber.

(2) Selection of linear density of chemical staple fibers

The linear density of cotton-type chemical fiber is 1.1~1.7 dtex, which is close to that of cotton fiber. The linear density of medium-length wool-like chemical fibers is 2.2~3.3dtex; The linear density of wool chemical fiber is 3.3~13dtex. Both medium-length and wool-type chemical fibers are slightly thinner than those blended with them. The finer the fiber, the more fiber roots in the cross-section of the same special yarn, the higher the fiber strength utilization rate, and the more uniform the yarn sliver, but the fiber is too fine and easy to produce granulation. Fine, well-fastened fibers tend to form small particles (pilling) on the surface of the fabric.

It is generally believed that when the linear density and length of chemical staple fibers conform to the following equation, the spinnability and yarn formation of chemical fibers are better:

L=230 H （ 2-6 ）

Where: L — fiber length (mm);

H — Fiber linear density (tex).

(3) Thermal shrinkage

Thermal shrinkage includes dry heat shrinkage and shrinkage in boiling water. If the heat shrinkage of chemical fibers varies greatly from batch to batch and the mixing is uneven, wrinkles and uneven defects will be formed on the cloth surface due to different degrees of shrinkage when the product is subjected to heat treatment during the dyeing and finishing process. Therefore, it is required that the thermal shrinkage of each batch of chemical fibers should be small, and the difference between batches should be small. However, in wool spinning, the difference between wool, rabbit hair, viscose and acrylic heat shrinkage performance is used to spin fluffy, plump and elastic acrylic bulking yarn.

(4) Dyeability of chemical fibers

Due to the instability of polymerization components or spinning processes in the production of chemical fibers of the same name, the fiber properties will be different, among which the dyeing performance is particularly sensitive. Therefore, when batching, it should be noted that different grades of the same chemical fiber cannot be arbitrarily increased or decreased in mixed proportions, or substituted for each other, otherwise it is easy to cause color difference.

(5) Selection of other properties of chemical fibers

Many chemical fibers have both conductive, flame retardant, antibacterial and other properties, and when blended with cotton, wool and other fibers, different blending ratios can be used to obtain the performance indicators required by the product, which are used in special environments such as work clothes, combat clothing and protective materials. In short, there are many varieties and different properties of chemical fibers, and products with different styles and functions can be obtained by making full use of the special properties of fibers. For example, Tencel G100 has fibrillation characteristics, through primary fibrillation, enzymatic treatment and secondary fibrillation, it can produce peach skin velvet style products, while Tencel A100 has no fibrillation characteristics, and can produce a smooth and smooth fabric with a neat surface after enzymatic treatment.

Section 4 Selection of reused raw materials

With the continuous development of China's economy and the shortage of natural resources, the industry has paid more and more attention to the research of fiber raw material reuse technology. Making full use of these spinnable recycled fibers in the spinning process can reduce production costs on the one hand, reduce carbon emissions on the other, protect the environment, and build a sustainable circular society.

Recycled raw materials can be widely used in various industries such as furniture decoration, clothing, home textiles, toys and automotive industry. For example, recycled cotton fibers are blended with other fibers to make denim with a coarse yarn count. Recycled fibers that cannot be spun with short lengths can be used as raw materials for industrial nonwovens, such as thermal insulation of automobiles and sofa cushions. Recycled fibers can also be used as the skeleton material of composite materials after treatment.

First, the source of reused raw materials

(1) Spinning and processing

In various spinning systems, when the fiber raw material is processed in different processes, reusable fibers such as impurities, backfills, filaments and scraps containing fibers will be produced.

1. Backflowers

It refers to the semi-finished products in the process of broken ends and joints in each process before yarn formation, as well as the semi-finished products that do not meet the specifications or are taken out by the test, including broken cotton rolls, broken cotton slivers, broken cotton nets, roving heads, leather roller flowers, and various untwisted waste wool fibers generated in the wool spinning process. Table 2-5 lists the sources of backflower in the cotton spinning process.

Table 2-5 Sources and characteristics of cotton spun backflowers

It can be seen that these backflower fibers have undergone the preliminary spinning process, and the overall performance is good, as long as they are classified and simply opened, they can be reused.

2. Miscellaneous categories

It refers to the impurities containing fiber removed in the process of spinning and processing, including chopping flowers, Xilindorf needle flowers, combed cotton drops, broken seeds under the cotton cleaning machine and good quality foot flowers in the process of cotton spinning, as well as combed short hair, sweeping hair, needle hair, car belly hair and various fallen hairs in the wool spinning process. Table 2-6 lists the sources of miscellaneous reused raw materials (including reused cotton and feet) in the cotton spinning process.

Table 2-6 Sources and characteristics of cotton spinning and reused cotton and feet

As can be seen from Table 2-6, these impurity fibers contain impurities, some of the fibers are damaged in terms of processing properties such as strength and elasticity, and some fibers are too short in length, and their overall properties are worse than those of backflower fibers, and they must be treated before they can be used as reused raw materials in the spinning process.

3. Filaments

It refers to the fiber waste generated in the yarn forming and post-processing process, including the scattered fibers generated by splices, spindles, winding, bunging and strands, as well as knitting yarn back.

These fibers have a certain twist and are generally non-spinnable raw materials, but after treatment, most of them can be used for woollen processing.

(2) Garment processing

In the garment processing process, such as washing, boiling, steaming, cutting, etc. in the woolen garment processing process, various leftovers will be produced, which need to go through a series of complex processing processes to obtain clean monofilamentous raw materials, which can be used as recycled fibers in the spinning process.

(3) Waste textiles

Waste textiles mainly come from consumption, such as waste clothing and home textiles that are eliminated after the completion of the service life cycle. China produces nearly 35 million tons of waste textiles every year, but only 5% of them have been recycled, and the rest are landfilled or incinerated as waste, which not only causes a waste of resources, but also due to the poor degradability of most of the fibers in waste textiles, which can remain on the surface for thousands of years without decaying, which greatly increases the environmental burden. Therefore, the recycling and reuse of waste textiles is in line with the important strategy of national circular economy development, and is also related to the sustainable development of China's textile industry.

2. Reuse raw material treatment

At present, in addition to some recycled fiber raw materials can be used directly, most of the reused raw materials need to undergo special treatment before they can be used as processing raw materials for various purposes. Common treatment methods include mechanical, chemical, physical, energy, etc. However, at present, the reused raw materials that can be used for spinning processing are mainly treated by mechanical and chemical methods.

(1) Mechanical law

Mechanical recycling is to directly process the unseparated textile waste into recycled fibers and spin them into yarn after opening to remove impurities and staple fibers, and weave usable textile products. As shown in Figure 2-4, the general process of mechanical processing of textile raw material reuse.

Figure 2-4 Mechanical processing of textile raw material reuse process

1. Cotton spinning and reuse raw material treatment

Generally, cotton spinning mills that mainly produce pure cotton and blended yarn are equipped with waste cotton workshops, which are usually equipped with machinery such as seed breaker (commonly known as Vero machine), vertical cotton opener, leather roller flower machine, fiber impurity separator, roving head machine, etc.

Considering the improvement of the treatment effect and the cleanliness of the workshop environment, some of the equipment with higher efficiency of opening and removing impurities used in the opening and cleaning process is also used in the waste cotton treatment system, such as axial flow cotton opener, three-thorn roller cotton cleaning machine, etc., and the process is generally: cotton grabber → metal impurity removal→ axial flow cotton opener or three-thorn roller cotton cleaner→ waste cotton processing unit → baler, in which the waste cotton machine processing unit is composed of four parts: cotton condenser, upper cotton storage box, beater impurity remover and fiber impurity separator. It has the advantages of high impurity removal efficiency, less land occupation, good sealing, good production environment and less energy consumption.

2. Wool spinning and reuse raw material treatment

The main source of wool spinning reused raw materials is various leftovers produced in the process of garment processing, which are processed by mechanical tearing by wet and dry methods.

The wet process is suitable for woolen fabrics and fabrics with a compact structure, so that the fabric is torn in a state of impregnation in cold water, which can reduce fiber damage, and the process route is: raw material → pretreatment→ wet tearing→ dehydration→ drying.

The dry process is suitable for loose structural fabrics such as wool and chemical fiber, and its process route is: raw material → pretreatment → dry tearing.

The process equipment of the dry process is relatively simple, while the wet process requires sufficient water source (because the fabric relies on the flow of water source), the equipment is larger, and it should be equipped with dehydration, drying and other equipment, generally according to different types of raw materials, respectively, the processing procedures are as follows.

(1) Clothing pieces include new films, old woolen pieces, knife edges, blank heads, etc., and the processing procedures are: pretreatment→ mixing and refueling→ opening machine→ returning wire machine→ carding machine (applicable when the yarn ribs are more after springing back the silk).

(2) Silk return includes worsted yarn return and knitting yarn return, etc., and its processing procedures are: classification→ shearing wet →→ mixing and stuffing→ returning silk machine→ carding machine (applicable when the yarn rib is more after springing back silk); Sorting→ cutting→ soaking in water→ crushing→ dehydration→ drying.

(2) Chemical method

The chemical method is the use of chemical reagents to treat reusable textiles, that is, the degradation or depolymerization of polymer materials into small molecules, intermediates or reaction monomers, and then repolymerization into polymers.

There are two ways to recycle waste polymer materials such as polyester: one is to use melting or dissolving methods to recycle these polymer materials and directly use them for other purposes; The second is to further crack the recycled polymer materials into polymer monomers, repolymerize and respin them into fibers. For example, about 30% of polyester staple fiber in the United States is now produced from recycled raw materials. The price of recycled polyester fiber is low, only 60% ~ 70% of the price of conventional polyester fiber, with a wide range of uses, quality indicators close to or up to the standard of conventional polyester fiber, and is in short supply in the textile and chemical fiber market.

The lower corners of wool spinning with more weeds, such as combed wool, can be carbonized to remove weeds and then reused, and wool carbonization is also a chemical method. The process is as follows: classification→ dust removal→ (hair washing) → (carbonization).

3. Selection of reused raw materials

At present, the reused fiber raw materials are mainly reused in cotton spinning and carded wool spinning systems. Therefore, the selection of reused raw materials is mainly based on cotton spinning and wool spinning reused raw materials.

(1) Raw materials for cotton spinning

Cotton spinning back flower fiber is long, less impurities, almost no twist, the quality is close to the mixed raw materials, except for the roving head and roller flowers, can be directly mixed with mixed raw materials after tearing. In production, factories often still reuse this branch for raw material blending. Cotton spinning and reuse must be used after packaging, generally in proportion to the cotton pile of the cotton grabber, the height should be close to other cotton bales, placed in the center position, in order to avoid uneven cotton mixing, the amount of mixing should generally not exceed 5%.

The cotton spinning combing rate is about 20%, and the effective fiber in the combed cotton accounts for about 80%, which is also directly reused, but when reused, it is generally used in the medium and coarse yarn above 18.4tex, and the mixing amount does not exceed 20%, otherwise the surface of the fabric is easy to pill, such as mixing 5~20% in the coarse special yarn, and 1%~5% in the medium special yarn.

In the process of cotton spinning, the clear flower drop rate is about 3%, and the carding cotton drop rate is 6%~7%. These reused cotton can be spun with less fiber, short fiber, containing more small impurities, and is often mixed in yarn or sub-brand yarn with higher thread density after different mechanical treatments; The chopping flower of the carding machine is generally used in low-quality products such as nonwovens, carpets and socks produced by rotor spinning; Because of its neat fiber and low twist, the roving head and the leather roller flower have less fiber damage after the roving head machine and the leather roller flower machine are opened, and the length uniformity is maintained well. In addition, there are such as oil flowers, silk and other feet, dust, defects, fiber content is very small, after mechanical treatment is not available, directly sold.

(2) Wool spinning reused raw materials

In the wool spinning reuse raw materials, the length of the short fibers dropped by combing processing is generally less than 30mm, and this part of the fiber can be reused in the cotton spinning system. In addition, most of the other fibers are mainly used in woolen processing. In order to reduce costs and improve the production rate, without affecting the quality of the product, we should try to use this batch of reply slips, drop off hair, etc. The use of recycled wool should be appropriate, and attention should be paid to its impurities, color, pure spinning or blending. Table 2-7 lists the quality requirements for wool spinning reused raw materials.

Table 2-7 Quality requirements for reused woolen raw materials

The wool returned in the process of wool spinning, due to the lack of twist, as long as it is classified and simply torn and opened, can be reused in carded wool spinning, and the amount of reuse varies according to the style characteristics and quality requirements of the fabric.

Combed short wool and wool contain a large amount of available fibers, which are reused in carded wool spinning products after mechanical treatment, and are used to produce woolen heavy fabrics, and the mixed raw materials can account for more than 30% in some carded wool products.

The fiber length of the clothing piece and the silk return is short after mechanical treatment (generally the length is 10~20mm), and it is also used in carded wool products, but most of the wool yarn produced is used to produce socks, blankets and other products, or used as flocculent materials after combing, such as making wool warm quilts.

(3) Raw materials for hemp spinning

The length uniformity of ramie fine dry hemp and flax beaten hemp is poor, and a lot of flax will inevitably be produced in the process of carding and processing, and it is particularly important to classify these flax according to the length for reuse.

Ramie fine dry hemp after combing carding, the short fiber separated from the long fiber is combed flax, ramie combed hemp fiber length is less than 45mm, so it is generally used in the cotton spinning system for reuse, can also be spun in the ramie spinning system for lower quality requirements and fineness coarse (lower count) ramie yarn. In the process of carding flax, the staple fibers combed by the carding machine, as well as the coarse linen (one coarse and two coarse) obtained during the initial processing of flax raw materials, are re-separated from flax staple fibers for short hemp spinning system, accounting for about 55%~65% of flax yarn. The combing flax produced by the comber machine generally has no use value and is no longer reused for spinning.

(4) Raw materials for silk spinning

In the process of spun silk processing, whether the circular carding cotton process or the combed cotton making process is adopted, a considerable amount of foot cotton will be produced. The average length of these fallen cotton fibers is short (about 25-45mm), the uniformity is poor, the linear density is small, and there are many cotton particles and debris impurities, especially the combed cotton loss. However, as far as its fibers are concerned, they still have the excellent characteristics of natural silk, and in actual production, these feet are fully reused in the silk spinning system to expand the variety of silk fiber products. The number of silk spinning is generally 33tex (less than 30 cm), and the tussah silk is above 5tex (less than 20 tex), made into woven fabrics or knitted fabrics, and the cotton silk woven into a single yarn generally feels soft and plump, and the fabric has a rough style, which is suitable for clothing, decorative fabrics, etc., but there are obvious grains on the surface.

Topic 2: Reuse of spinning raw materials and environmental protection

Food for Thought:

1. What is the purpose of fiber raw material selection? What is the principle of mating?

2. What is the Sorting and Queuing Method? What is the computerized cotton blending method?

3. What is comb strip and mixed strip hair?

4. What are the basis for the selection of carded wool fiber raw materials?

5. What is the effect of the mixing ratio of chemical staple fibers on the performance of blended yarns?

6. What are the sources of reused fiber raw materials? Briefly describe the mechanical processing equipment and treatment process of recycled fiber raw materials used in cotton spinning and wool spinning.

7. How to select raw materials for cotton spinning and wool spinning reuse fiber?

Chapter 3 Opening

What you need to know in this chapter:

The purpose and requirements of opening

The principle of tearing, blowing, and splitting the opening effect, the factors affecting the opening effect, and the evaluation of the opening effect.

The principle of chemical and physical impurity removal and the evaluation of impurity removal effect.

Calculation of the index of the mixture, mixing method, evaluation of the mixing effect.

Section 1 Overview

Most of the raw materials used for spinning are transported into the factory in the form of compacted bales, and the fibers are large and bundled, and they are entangled with each other and arranged in disorder, and contain various impurities and defects (chemical fiber raw materials contain a small amount of hard wire, parallel wire, ultra-long fiber and other defects). Therefore, in order to spin smoothly and obtain high-quality yarn, the first task is to open the raw material and remove various impurities and defects, while achieving the initial mixing of the raw material.

First, the purpose and requirements of opening

(1) The purpose of opening

1. Preliminary loosening of raw materials. The tightly packed fiber raw materials are preliminarily loosened, so that the fibers in the raw materials that are large and large bundles are transformed into small pieces and small bundles, and the weight per unit volume is reduced, so as to create conditions for the carding process to further loosen the fiber raw materials into single fibers.

2. Remove large and small impurities in fiber raw materials. The opening exposes the impurities (large impurities) that are large in size, heavy in weight and weak in adhesion with fibers in the raw materials, which is conducive to their removal, and some small impurities will also be removed with the drop of a small amount of fibers, which improves the spinnability and product quality of the subsequent process.

3. Preliminary blending of different fiber raw materials. The better the opening, the smaller the fiber bundle and the higher the degree of mixing, the more uniform and the higher the quality of the semi-finished product in terms of composition, proportion, structure, etc.

(2) Requirements for opening

1. The opening effect should be appropriate. If it is too violent, it is easy to damage the fibers or break the impurities; If it is too gentle, the effect of opening and removing impurities is not good. The requirements for opening are not only to fully open, but also to reduce damage to fibers and broken impurities. Therefore, in the process of opening, the process principle of "slow down first, then drama, gradual opening, less injury and less breaking" should be followed. In the specific implementation, it is advisable to adopt the order of free opening first, and then holding and opening.

2. The removal of impurities should be based on the characteristics of impurities and the difficulty of elimination. The impurities that are heavier and larger and easy to break and adhere weakly to the fiber should be eliminated as soon as possible to avoid increasing cotton dropping and damaging the fiber.

3. While fully opening and removing impurities from the fiber raw materials, the fibers of different characteristics (pure spinning), types (blended) and even colors (color spinning) are preliminarily blended.

The opening effect is the means of fiber release, and the release of fiber is the prerequisite for removing impurities and mixing, along with the opening of raw materials, constantly removing impurities and realizing the mixing of fiber raw materials.

Second, the opening effect in the spinning system

According to the difference in the type and nature of the fiber, the steps, processes and equipment of the opening effect are different in different spinning systems, and the main processes include the initial processing of raw materials, the opening of cotton, the wool, the opening of hemp, the opening of cotton, etc., as well as the feeding part of carding.

(1) Cotton spinning system

The opening effect of raw materials in cotton spinning is mainly completed in the processes of ginning, opening and carding. The seed cotton passes through the leather roller cotton ginner or the sawtooth cotton gin, and the cottonseed and the fiber are separated from each other through the action of the leather roller and the blade, or the sawtooth, and the obtained fibers are called the leather roller cotton and the sawtooth cotton respectively, and then packed for storage and transportation; The cotton bales are grabbed by the cotton grabbing machinery and opened into small pieces at the same time, and then through the cotton blending machinery based on the mixing effect and the cotton opening and cleaning machinery based on the opening effect, the cotton bag is further loosened, and the cotton block is gradually reduced to a small cotton bundle; The feeding part of the carding machine uses the barbed roller serration to divide the cotton bundle in the holding state, and the fiber is initially reached a single state. In the process of opening, it is accompanied by the removal and mixing of impurities, and most of the impurities and linters, and the defects are removed.

(2) Wool spinning system

There are many impurities in the plush fibers, although the plush after picking up is torn by hand, the connection between the fibers is weakened, and some impurities are picked up, but the fibers are still relatively tight, and there are a large number of impurities. In order to ensure the smooth progress of hair washing, the hair block should be opened by the hair opening machinery before hair washing, and the impurities such as sand and manure should be removed to the greatest extent to reduce the burden of hair washing. Before the fluff fiber after preliminary processing (washing) enters the carding machine, it is first necessary to add an appropriate amount of additives (and crude oil) to improve the surface properties of the raw wool after washing and drying, so that the spinning can be smooth. At this time, in order to mix the crude oil and the raw wool evenly, it is necessary to go through 1~3 times of opening and mixing with the wool machinery, so that the wool block can be further opened, and the large wool block will be changed into a smaller wool block or hair bundle, and the mixing will be more uniform. In the same way, the fibers can be further loosened by serrations in the feeding part of the carding machine.

(3) Hemp spinning system

The fine and dry hemp fibers obtained by degumming ramie are too long, the length unevenness is large, the fibers are compacted, and after being stored and stored by soft hemp, wet oiling, stacking, although the moisture regain rate of fine and dry hemp is increased, the softness is increased, but it is still not suitable for spinning requirements. Following the principle of gradual opening, it is first necessary to preliminarily open the fine and dry hemp, so that the excessively long fibers are torn off to a suitable fiber length, and a certain amount of hemp strips are made and rolled into hemp rolls to meet the feeding requirements of the carding machine. The flax filaments used in the flax spinning mill are the degummed hemp and are carded before carding. The purpose of the primary carding is to comb out the long and neat carded hemp and the short and disordered carded short hemp (machine short hemp) from the beaten hemp of humidification and oil, health preservation and bunching; The beaten hemp will be further split into finer process fibers to remove some impurities such as hemp chips and hemp skin; Thus improving the fiber state and structure of flax.

(4) Silk spinning system

The opening effect of the spinning system is mainly completed in the refining and opening process. Refining is mainly to remove sericin, oil and other impurities contained in the raw materials of silk spinning to make clean and loose lean cotton. The opening of the cotton is to use the sawtooth of the cotton machine to open the various fine cotton that is composed of the blending ball by the cotton, so that the large piece of fine cotton becomes a small bundle, and the fiber has a certain parallel straightness, remove some impurities in the fine cotton, mix the various fine cotton in the blending ball, and finally make a certain specification, uniform thickness of the open cotton.

Section 2 Basic Principles of Opening

The opening effect is to use the moving parts with angle nails, serrations, blades or comb needles on the surface to tear, hit, and divide the fiber block, and break the large fiber block into small fiber bundles.

According to the different ways of feeding the fiber raw materials to the opening parts, the opening can be divided into two forms: free opening and holding opening, and free opening is the role of the raw materials in a free state to accept the opening parts; Holding opening is the opening effect of the opening machine when the raw material is held by the feeding machine (usually a pair of feeding rollers or a combination of feeding rollers and feeding plates) to the feeding machine. According to the different modes of mechanical action, it can be divided into three types of opening: tearing, blowing, and splitting.

Tear and open

Tearing and loosening includes the tearing action of one moving corner nail or two opposing moving corner nail parts on the raw material, and the prerequisite for pulling loose is that the corner nail has the ability to grasp the fiber.

(1) The loosening effect of a corner nail on the raw material

When the corner nail on the corner nail curtain of the automatic cotton blender or the automatic wool feeder pierces into the pile of raw materials input by the horizontal curtain, the connection force between the raw material blocks and the fibers is destroyed, and with the movement of the corner nail curtain, it is torn into smaller blocks or bundles, and the force of the corner nail is shown in Figure 3-1. In the figure, P is the vertical pressure of the raw material on the surface of the corner nail, which is parallel to the plane of the nail. A is the resistance of the raw material to the corner nail when the corner nail curtain moves upward, which is parallel to the plane of the nail planting; T is the horizontal thrust of the diagonal nail curtain of the raw material conveyed by the horizontal curtain, which is perpendicular to the planting nail plane.

Figure 3-1 Loosening of a corner nail

Let the resultant force of the three forces be , which can be decomposed into the component force along the direction of the corner nail working face and the component force of the vertical corner nail working face . Wherein, the component force points to the nail, which is called the grasping force, and the friction action of the component force and the angle nail and the fiber block forms the grasping resistance. If the angle between the working surface of the corner nail and the plane of the nail is called, it is also called the working angle of the angle nail.

则有：

（3-1）

From equation (3-1), it can be seen that when decreasing, the grasping force increases and decreases, which is conducive to the penetration of angle nails.

(2) The loosening effect of two corner nails on the fiber block

The opening effect between the corner nail curtain and the cotton (wool) roller of the automatic cotton blending machine or automatic wool feeding machine is the tearing effect of two opposing moving corner nails on the fiber block. As shown in Figure 3-2, when the cotton block grabbed by the corner nail curtain of the cotton blender moves forward and encounters the uniform cotton roller, when the thickness of the cotton block is greater than the distance between the uniform cotton roller and the corner nail curtain, the corner nail of the uniform cotton roller grabs the cotton block, and two corner nails that move relative to each other tear the cotton block, and the cotton block is divided into two parts, one part is taken away by the corner nail curtain, and the other part is thrown back to the cotton box by the uniform cotton roller by centrifugal force, and the opening of this cotton block belongs to pulling loose. In Figure 3-2, points A and B represent the application points of the cotton roller and the corner nail curtain on the cotton block, respectively.

Figure 3-2 Loosening of two corner nails

In the process of pulling loosening, the tearing force on the cotton block is . Due to the small distance between the corner nail curtain and the uniform cotton roller, the direction of the force can be approximately considered to be the direction of movement along the corner nail curtain. Break down the force into a component force (gripping force) in the direction of the corner nail and a component force (positive pressure) in the direction of the vertical corner nail by the magnitude of:

Where: —the angle between the corner nail and the horizontal curtain, that is, the working angle of the corner nail; — the component of the cotton block that sinks into the root of the corner nail; – the positive pressure generated by the cotton block pressing against the corner nails; – frictional resistance caused by , which prevents the cotton block from moving towards the root of the corner nail, the value of which is:

Where: —the coefficient of friction between the cotton block and the corner nail. For the corner peg to have the ability to grip, it is necessary to make > , ie

Therefore (3-2)

It can be seen from equation (3-2) that in order to strengthen the grasping effect of the corner nail on the cotton block, the angle should be reduced, but the angle is too small, and the cotton block is embedded in the corner nail too deep, and then the fiber is affected to be separated from the corner nail curtain. Due to the difference in fiber length and state, the difficulty of grasping the corner nail curtain is different, therefore, the angle of the corner nail is different in different spinning systems. In cotton spinning, the fiber is shorter, not easy to be grabbed by corner nails, and the general angle is 3050. In wool spinning, due to the long fiber and more curl, it is easy to be grabbed by angle nails, and the general angle is 4560.

Second, crack down on opening

Blow opening is a high-speed rotating percussion mechanism (also known as a beater) equipped with blades, fins, corner nails or needle teeth to strike at raw materials, destroy the connection between fibers and between fibers and impurities, and achieve the purpose of loosening fiber blocks and removing impurities.

(1) Free loosening

The process of loosening the fiber block by the blow of the high-speed striking mechanism in the free state is called free loosening. The basic principle of free loosening is that the fiber block is driven by the negative pressure of the air flow in the striking area (beater room), but because the movement speed of the striking mechanism is much greater than the speed of the fiber block, the free blow effect is generated, causing oscillation, so that the fiber block is loosened.

Figure 3-3 shows the fiber block when it is subjected to a free blow. The fiber block is composed of two parts of fiber blocks with the mass m ₁ and m ₂ that are interconnected with each other, and the center of mass is at points A and B respectively. If there is a striking force P at point A, its direction is along the tangent direction of the thug's trajectory. The force P is decomposed into P ₁ and P ₂ , and the direction of P ₁ is along the direction of the line between A and B, and under the action of P ₁ force, the fiber block of mass m ₁ is torn instantaneously, and the fiber block is torn apart. If the connection between the fiber block m ₁ and m ₂ is small, the fiber block is opened into two parts. If there is a large enough connection force between the fiber block m ₁ and m ₂ to tear apart, the fiber block either moves in the direction of the beater's velocity or rotates around point B under the action of P ₂ force to avoid the action of the beater, thus reducing the fiber damage. Due to the mild opening action in the free state, the degree of fiber damage and impurity fragmentation is small, so it is suitable for the initial stage of opening.

Figure 3-3 Force analysis of fiber block during free blow

The axial flow rollers of the cotton spinning axial flow opener, the multiple rollers of the multi-roller cotton opener, and the cylinder of the wool spinning three cylinder opener all belong to the free-style blow opening.

(2) Loosen the grip

The blade beater with high-speed rotation strikes the feeding raw material that is being held, so that the raw material gets impulse and is opened, which is called gripping loosening. The basic principle of the grip strike effect is that one end of the raw material is controlled, and the inertia that can rotate freely cannot be obtained when it is hit, and the blow can only be borne and not avoided, so the blow is strong, but the blade cannot penetrate the raw material, and its opening effect is not detailed enough.

Figure 3-4 shows the opening of the blow between the cotton roller and the beater's blade on the cotton spinning machine. The cotton layer is slowly fed to the cotton roller, and the high-speed rotating thug strikes the exposed cotton layer at the jaws, and the striking force P is in the tangential direction of the thug's movement trajectory. The cotton layer is struck by the thug, so that the exposed fibrous whisker bushes gain striking strength and are loosened into smaller fiber bundles, and some of the finer impurities are separated. Strike strength is usually measured by the punch impulse and number of blows indicators.

Figure 3-4 Analysis of the striking force of a fighter in the gripping state

1. Strike impulse

The strike impulse represents the product of the striking force and the time of the strike. In order to break the connection between the fibers, it is necessary to have a large striking impulse. Let the striking impulse acting on any small section of feeding whisker bush as:

Then the striking impulse J on the entire feeding whisker bush is equal to the sum of the impulses acting on all the parts of the whisker above:

（3-3）

where: — striking force on the entire bush;

– striking force on a small section of whisker bushes;

— Strike time.

From equation (3-3), it can be seen that with the increase of the striking force, the striking force will increase, and the opening effect will be strengthened, but the fibers are easily damaged and the impurities are easy to break. Therefore, according to the position and form of the beater, the opening strength should be appropriately configured.

2. Number of blows

The number of blows refers to the number of blows to the blade on the fiber per unit weight fed. If the number of blows is large, the opening effect is good, and the calculation formula is:

（3-4）

Where: — number of blows, times/g;

— the number of blades of the beater;

— thug speed, r/min;

– the length of the fiber layer fed per minute, cm/min;

– Feed the fiber layer per centimeter weight, g/cm.

As can be seen from Eq. (3-4), the number of blows is directly proportional to the speed of the beater and the number of blades, and inversely proportional to the weight of the fiber layer per minute. The light dosage and short length of each feed will result in a small fiber bundle that will be torn off, which is good for opening, but the yield will be reduced.

The wing beater of the cotton spinning machine and the porcupine beater of the porcupine opener belong to the grip type blow opening effect.

3. Divide and open

Segmentation and opening is to penetrate the fiber layer by serrations or comb needles to divide the fibers, so that the fiber bundles can be opened more finely. Usually the serration or comb needle is pierced in the state of the fiber layer being held and divided, so it is a grip opening. It is used in the feeding part of silk spun openers, wool and linen roller carding machines and cotton cover carding machines. Segmentation parts are often made with a thug or roller covered with metal serrations or implanted with a comb needle.

(1) Segmentation and opening process

As shown in Figure 3-5(a), the silk cotton is fed in the grip of the cotton feeding thorn roller and the cotton holding knife on the cotton opener, and the cotton is split and opened by the cotton cylinder; Figure 3-5(b) shows that on the carding machine (carding machine), the wool (hemp) fiber layer is fed in the holding state of a pair of rollers, and is divided and opened by the thorn roller or the hair (hemp) roller and the breast cylinder; Figure 3-5(c) shows that on the carding machine, the cotton layer is fed in the position of the cotton roller and the cotton feeding board, and the barbed roller is split and opened.

Figure 3-5 Segmentation and opening process

Take the cotton opener as an example to illustrate the process of segmentation and opening, see Figure 3-5(a). The cotton layer is fed in the state of feeding the cotton thorn roller and the cotton holding knife, and the fiber bundle (block) fed into the cotton layer is grabbed by the comb needle of the cotton cylinder for tearing, and the cotton layer is opened. In the process of opening, when the grasping force P of the comb of Ruokai cotton cylinder for the fiber bundle (block) ₂ is less than the control force ₁ P of the feeding mechanism on the fiber bundle (block), and both are less than the strength of the fiber bundle, the exposed end of the fiber is affected by the comb needle of the sponge cylinder, so that the large fiber bundle is decomposed into smaller fiber bundles. When the forces P ₂ and P ₁ are greater than the strength of the fiber bundle, the fiber bundle is torn off, and part of it is taken away by the open cotton cylinder, leaving part to continue to be affected by the effect of the open cotton cylinder. When the gripping force and fiber bundle strength of Kaimian cylinder are greater than the control force, the fiber bundle is withdrawn from the feeding mechanism and transferred to Kaimian cylinder.

(2) Analysis of the opening effect of segmentation

1. The segmentation effect of the sawtooth

(1) The condition under which the serrations penetrate the fiber layer

Whether the serration can penetrate the fiber layer smoothly is the primary condition to determine the segmentation effect. Figure 3-6 shows the force applied to the serration of the barbed roller when it penetrates the fiber layer. When the sawtooth penetrates into the fiber layer, the fiber layer has a tangential reaction force along the circumference of the sawtooth to the sawtooth, which can be decomposed into the component N perpendicular to the sawtooth working face and the component parallel to the sawtooth working face . The component force has a tendency to make the fiber advance along the sawtooth working towards the pinroot, and when the fiber moves along the sawtooth working surface, the component force will produce frictional resistance that prevents the fiber from moving . If so, the fibers move along the working surface of the serration towards the tooth root, and the serration can penetrate the fiber layer and tear.

Because

where: —coefficient of friction between the serration and the fiber;

– the angle of the sawtooth working face;

—sawtooth working angle, .

In order for the serration teeth to smoothly penetrate the fiber layer for tearing, it must be satisfied . Therefore:

Then (3-5)

where: — the angle of friction between the serration and the fiber.

It can be seen that reducing the working angle (i.e., enlargement) is beneficial to the sawtooth penetrating into the fiber layer for opening, but too small, it is not conducive to the sawtooth impurity removal and fiber transfer, and it is easy to cause backflower (i.e., the fiber returns to the feeding place with the rotation of the barbed roller). When choosing the working angle, it is necessary to consider the sawtooth segmentation effect and ensure that there is no backflowering. Therefore, the working angle of spinning chemical fiber is larger than that of spinning cotton, so as to facilitate the transfer of fiber and reduce backflowering.

Figure 3-6 The force applied to the serration when it penetrates the fiber layer

(2) Analysis of the condition of the serrated holding fiber

The sawtooth not only divides the fiber layer, but also requires the sawtooth to be able to carry the fiber forward to avoid breaking away from the sawtooth and becoming a drop of fiber. For the serration to carry the fiber forward, the serration must have the conditions to hold the fiber.

Figure 3-7 shows the force analysis of the fiber bundle held by the serrated teeth.

Figure 3-7 The force of the serrated holding fiber

In the figure: – centrifugal force, along the radius of the barbed roller;

– air resistance, perpendicular to the direction of the barbed roller;