低扭矩环锭纺纱原理及其单纱的结构和性能

本文主要回顾了低扭矩环锭纺纱技术的发展。通过讨论其纺纱三角区的特点,利用高速摄影技术对纺纱区捻度和张力分布的观察分析,系统地介绍了低扭矩纱的成纱原理。此外,结合示踪纤维技术,利用纱线结构连续测量分析系统对低扭矩环锭单纱和传统环锭单纱的内部结构进行分析,揭示了低扭矩纱独特的结构特点,如非同轴异形螺旋线结构,纤维片段局部反转现象等。这些特点解释了低扭矩纱及其织物具有优良物理性能的原因。同时,通过多个生产厂家提供的测试数据,对比分析了几代低扭矩环锭纱与传统环锭纱及其织物的物理性能,结果表明低扭矩环锭纱具有低捻高强、低残余扭矩和毛羽少等特点,其针织物经多次水洗后歪斜变形小和手感好,机织物具有较好的撕裂强力,断裂强力和耐磨擦性。最新一代低扭矩环锭纺纱技术显著地改善了高支纯棉纱的物理性能。     

Research on Sirospun yarn torque using airflow false twisting device

Yarn torque is one of the most important indexes of yarn quality, which is determined on the mechanical state of the constituent fibers and their configuration in the yarn. The fiber tension within a yarn was proposed to be the most influential factor governing the magnitude of yarn torque by Bennett and Postle. Therefore, the research on Sirospun yarn torque is investigated by analyzing the fiber tension at spinning triangle in this paper. Firstly, theoretical models of the fiber tension distributions at primary and final spinning triangles are presented, and corresponding residual torque within a yarn due to the fiber tension is given. The relationships between the yarn torque and the spinning triangle parameters are analyzed theoretically. Secondly, as an application of the proposed method, a modified Sirospun spinning system with an airflow false twisting device which can change spinning triangle parameters are investigated, and the properties of spun yarns produced by the modified system are evaluated and analyzed. It is shown that with the increasing airflow pressures, the Sirospun yarn shows a more and more uniform distribution of tensile and compressive stress within a yarn, and thus the yarn torque decreases correspondingly.     

Research on spun yarn qualities in a modified ring-spinning system using airflow-twisting device

In this paper, a kind of airflow-twisting devices which can produce the twist by the high vortex airflow is employed for improving the twist propagation process of ring-spinning system. Firstly, three different kinds of yarns Ne20, Ne40, and Ne60 are spun in this modified ring-spinning system with five different airflow pressures and two different swirling directions, including anticlockwise and clockwise, and the qualities of spun yarns, including hairiness, strength, evenness, and number of snarling characterizing the yarn residual torque, are measured. Secondly, the images of spinning triangles are captured by using a high speed camera system OLYMPUS i-speed3, and the mechanism of the effects of vortex airflow on yarn qualities is discussed by analyzing the fiber tension distributions in the spinning triangle. It is shown that for the ‘Z’ twist spun yarn, the spinning triangle decreases with the increasing of clockwise airflow pressures, whereas the triangle becomes more and more symmetrical with the increasing of anticlockwise airflow pressures. Meanwhile, the comprehensive qualities of spun yarn are improved with the increasing of both directions of airflow pressures to a certain extent. However, the hairiness and strength of spun yarn will be mainly improved with clockwise airflow, whereas yarn residual torque mainly reduced with anticlockwise airflow.     

Research on yarn qualities modified by mechanical false-twisting device

Abstract

In the ring-spinning process, the area between the front roller nip and twisting point is spinning triangle, and its geometry influences the fiber tension distribution in the spinning triangle directly and determines the properties of spun yarns. Therefore, in the paper, one kind of mechanical false-twisting device was introduced on the ring spinning, which can affect the twist propagation and change the spinning triangle geometry actively. First, the modification of the false-twisting device on the DTM129 ring-spinning frame was introduced. Taking the medium cotton yarn spinning as an example, corresponding ring yarn, Sirospun yarn, compact yarn were spun on the modified spinning frame under different designed twist factors, and the applicability of the false-twisting device on different spinning method was discussed. It is shown that comparing with the common yarn, the Hairiness and Strength of the modified yarns are all improved, and the effect of false-twisting device on yarn qualities is more effective for the low-twist yarn. Comparing with the ring spinning, the improvement degree of the modified compact spinning is a little smaller. Then, the long-staple cotton ring yarn, polyester and medium cotton blend ring yarn, polyester ring yarn were spun on the modified spinning frame under different designed twist factors, and the applicability of the false-twisting device on different fibers was discussed. It is shown that the influence of the false-twisting device on the long-staple cotton yarn and polyester yarn is little. That is, the false-twisting device given in the paper would be more applicable on the short fiber spinning under the low designed twist factor.     

Investigation of the quality properties of open-end spun recycled yarns made from blends of recycled fabric scrap wastes and virgin polyester fibre

Recycled fibre obtained from fabric scrap wastes is characterized by its low quality properties in terms of inhomogeneous fibre type and non-uniformly distributed short fibre lengths, both of which negatively influences the production process and the quality of the recycled yarns made from it. One of the common ways to utilize recycled fibre in yarn production is to blend it with virgin fibres. In this research article, the quality properties of the open-end spun recycled yarns produced in different material and spinning parameters from blends of recycled fabric scrap wastes and virgin polyester fibres are investigated. As material and spinning parameters, yarn count, blend ratio, waste type, waste origin, twist coefficient and rotor diameter are selected and their effects on the quality properties of the recycled yarns are evaluated through statistical methods. Statistical results reveal that especially blend ratio, yarn count and twist coefficient significantly affect the quality properties. In general, incorporation of virgin polyester fibre to recycled fibre tends to bring about improvement in yarn quality.     

羊绒/羊毛/涤纶复合纺及成纱拉伸性能分析

选择羊绒、羊毛和涤纶长丝在传统的环锭纺系统上进行三组分复合纺纱。通过改变三组分的喂入位置、喂入张力来获得不同结构和风格的纱线。试纺了不同捻度和混纺比的3种复合结构纱,即股线、包芯和包缠结构纱,分析了其拉伸性能。纺纱实验和测量结果表明:通过复合改善了羊绒纱的强度;纱线拉伸性能与混纺比、捻度、纱线结构之间存在相关;随着捻度的增加,3种结构复合纱的拉伸性能均符合经典临界捻度理论;复合纱的力学性能因结构不同而不同,股线结构纱拉伸性能最好,包芯结构纱次之,包缠结构纱拉伸性能则最差。     

An approach to predict the tensile strength of a two-ply yarn from single filament yarn

It is considered that the strength of the ply yarn consisting of continuous filaments mainly depends on the properties of the single yarn and the cohesion forces among the single yarns, thus a mathematical model with relatively few parameters under given assumptions is established to predict the tensile strength of a two-ply yarn from single filament yarn. Relative relationships of the tensile force part and the interaction part are developed, respectively. The single yarn is tested to obtain fundamental data e.g. yarn strength and breaking elongation. After two strands of filament yarns are twisted into the ply yarns under different twist levels, the tensile strength, breaking elongation and structure parameters are measured or calculated for verifying the model later. Finally, the results show good agreement with the experimental values, and this model can be used to predict the performance of the finished strand yarns in actual productions.     

Predicting torque of worsted singles yarn using an efficient radial basis function network-based method

The torque in single-spun yarns is an inherent property of the twisting and bending of staple fibres during the formation of yarn combined with the effect of applied tension on the yarn. The consequences of yarn torque are well known and are widely observed as yarn instability, e.g., yarn rotation under tension; local snarling and entanglement at low loads, and as distortion in fabric, i.e., edge-curl and skewing in knitted fabric. In this paper, a method for predicting the yarn torque based on the radial basis function networks is presented and evaluated. This method uses a “universal approximator” based on neural network methodology to minimize noise during training of the network and to approximate the yarn torque as a function of the geometrical and physical parameters of yarns (twist, linear density) and the applied load. The current method is an integral radial basis function network-based approach suitable for textile engineering and gives very good prediction of yarn torque across a range of yarn structural parameters and test conditions.     

空心锭包覆纺纱的芯纱残留捻回及其应用

为探讨空心锭包覆纺纱过程中外包缠纱对芯纱的假捻作用与应用,以黑、白两色涤纶长丝纱组成双芯纱,黑色涤纶长丝纱为外包缠纱,纺制了不同纺纱工艺的包覆纱,分析了芯纱残留捻回的捻向和捻度特征以及锭速、引纱速度、芯纱张力对芯纱残留捻度的影响;对利用芯纱残留捻度纺制段彩纱的原理与段彩特征进行了探讨,并给出了应用实例。结果表明:外包缠纱对芯纱缠绕的假捻作用,会使芯纱上形成残留捻向变化、捻度不等的捻回分布;残留捻回的捻度随锭速的增大、引纱速度的降低、芯纱张力的减小而增大;利用芯纱残留捻回的片段呈色效应,可用异色芯纱纺制具有段彩外观的“纱/纱”复合段彩纱,这种段彩纱具有区别于常规段彩纱的“闪色”特征。     

Research on flow field in a modified ring spinning system with the air nozzle

Twisting is one of the most important steps in the yarn spinning, which influences the geometry of spinning triangle and determines the properties of spun yarns. Airflow is one of the most important measures on improving yarn spinning. In this paper, a kind of air nozzle with vortex guiding channel was designed and used on the modification of ring spinning system, and the spun yarn qualities was studied by analyzing the airflow field in the nozzle. Firstly, the three-dimensional physical model of nozzle was given using CAD software according to the geometrical size of the practical nozzle model. Then, the numerical simulations of the three-dimensional flow field in the nozzle were given using Fluent software. Finally, two different kinds of yarns 10Ne and 20Ne were spun in the modified ring spinning system with the nozzle installed. The airflow pressure 0.01 Mpa and two different swirling directions, anticlockwise and clockwise, were chosen. The qualities of spun yarns, hairiness, strength, evenness, and number of snarling were measured and analyzed. It is shown that the high vortex airflow can be produced in the nozzle, and then corresponding twist can be produced. For the Z(S) twisting spun yarn, under the effects of the clockwise (anticlockwise) vortex airflow, the pre-twisting would be produced and the yarn twist can be strengthened, while under the effects of the anticlockwise (clockwise) vortex airflow, the untwisting effect would be produced, and the yarn twist can be decreased.     

Effects of directed movement of fibres in a twist triangle on yarn quality

This work investigates the effect of directed flow of the fibres in a twist triangle on yarn properties. This is done using different clip‐on attachments positioned on the front rollers of a ring spinning frame. Seven sets of rollers (plain non‐grooved; 75°‐biased left‐to‐right grooved; 75°‐biased right‐to‐left grooved; 15°‐, 45°‐ and 75°‐biased grooved from both sides towards the centre and solo) are made and positioned immediately below and parallel to the top front draft rollers of the laboratory ring spinning frame (tester model 82 KA) so that they can interact with the emerging drafted fibre strand before twist insertion. Afterwards, a 0.495‐ktex (2.02 Nm) finisher worsted roving composed of 55% polyester and 45% wool is fed into each unit of the ring spinning frame to produce a yarn with a yarn count of 30 Nm and a twist factor of 125. The rollers affect the flow of the fibres in the triangle zone and, as a result, the quality of the yarns is affected. A comparison of the yarns produced shows that directing the fibres in the triangle zone could improve the yarn quality. The results indicate that the 75°‐biased grooved (from both sides towards the centre) rollers improve the yarn quality in terms of hairiness, elongation and imperfections.     

基于图像的喷气涡流纺纱线捻度测试方法探讨

为探究适用于喷气涡流纺纱线捻度测试的有效方法,在对比分析喷气涡流纺纱线与传统环锭纺纱线结构的基础上,借助扫描电子显微镜,分别通过喷气涡流纺纱线的外观图像和横截面图像,测试了喷气涡流纺纱线捻度.并采用Photoshop软件处理喷气涡流纺纱线横截面图像,探究喷气涡流纺纱线内外层纤维数量比与其捻度的关系,提出了用喷气涡流纺纱...     

A comparative study on properties of dual-core yarns

Core-spun yarns containing Spandex have been widely used for the production of elastic textile materials. However, it has been encountered various problems not only during the usage but also during textile processes due to its high recovery property. In order to solve these problems, multicomponent core-spun yarns called as dual-core (DC) yarns, have been developed. DC yarns can be produced on the modified ring spinning machine in two different ways. In the first method, previously combined two core yarns are fed simultaneously, whereas in the second method, two core yarns are given separately into the centre of sheath fibre bundle. In present study, it was aimed to research the effect of these production methods on yarn features. Polyester and Spandex core components and cotton wrapping fibres were brought together in both two ways and the properties of multicomponent core-spun yarns were compared with cotton ring counterparts for three different yarn counts.     

A study on siro-, solo-, compact-, and conventional ring-spun yarns. Part I: structural and migratory properties of the yarns

Properties of spun yarns are mainly affected by fiber properties and yarn structure. Yarn structure is principally influenced by the spinning system. In fact, each spinning system tends to produce a distinctive yarn structure. Recent refinements in spinning technologies have yielded significant improvement in yarn structure. Siro, solo and compact spinning are the new spinning systems to have made a breakthrough until recently. Of the various structural parameters for staple yarns, fiber migration has a crucial influence on the yarn mechanical properties. Thus, the need for precise and concise information about fiber migration becomes important for better understanding of yarn structure and hence yarn mechanical behavior. The work presented here aims to analyze fiber migration in siro-, solo-, compact-, and conventional ring-spun yarns by varying the twist factor. The results demonstrate that the siro-spun yarns exhibit the highest fiber migration parameters, followed by compact-spun yarns, solo-spun yarns, and conventional ring-spun yarns.     

气流槽聚型集聚纺纱条捻度传递的力学分析

 为深入了解集聚纺纱系统,提高纱线的品质性能,重点探讨气流槽聚型集聚纺纱系统的捻度传递机制,介绍气流槽聚型集聚纺纱系统的结构特点,分析捻度传递过程中的纺纱张力变化,给出纺纱张力的求解过程,分析纱条在捻度传递过程中外力产生的阻力矩,及其与纱线自身回转产生的扭矩的关系。研究结果表明：纺纱张力、吸气管负压以及集聚罗拉的结构参数对纱条捻度的上传有一定的影响;通过调整纺纱张力与吸气管负压可以保证该系统所纺纱线的品质。     

21—STT YARNS: TECHNOLOGICAL ASPECTS OF TWISTED SELF-TWIST YARNS

The STT system is one in which unidirectional twist is added to self-twist yarns to produce two-ply weaving yarns. The added twist required for the elimination of fabric patterning due to cyclic twist variation in the yarn has been determined and has been expressed in terms of the amount of self-twist in the yarn. Fabrics woven from STT yarns have been evaluated, and the dependence of fabric properties on initial self-twist and on added-twist levels has been investigated. This has resulted in recommendations for the spinning and twisting of STT yarns for use in making high-quality worsted fabrics.     

双股线几何强力模型的建立与其影响因素

 股线的强力增强效应一直都还停留在定性描述上,作为组成纱线强力的两大因素,纤维性能和纱线结构对强力的贡献情况尚不明朗。为了量化这两部分,从建立双股线模型的几何配置出发,分析了单纱短片段在拉伸载荷下轴向和径向的力学状态对拉伸行为的影响,体现在拉伸模量与单纱性能参数和捻回角的关系;并且考虑了单纱之间的抱合力作为组成股线强力的一部分,推导了单纱在无滑移情况下的股线强力表达式,并定量分析讨论了单纱性能参数与纺纱参数对股线最大强力的影响情况,其结果符合一般认识,可用于开发纱线新产品的强力预测。     

亚麻长麻/涤纶长丝复合纱的纺制及其性能比较

为比较不同复合加工方法所纺亚麻长麻/涤纶长丝复合纱的性能,通过现有纺纱设备改造设计了纺纱工艺,纺制了具有相同捻度的5种复合纱;对复合纱的外观特征、拉伸性能和毛羽进行了测试与分析。结果表明:采用不同成纱方法的复合纱均具有明显的捻度分布不匀特征;包缠结构复合纱相对于捻合结构复合纱具有更好的包覆效果;相对于断裂强力而言,复合加工对亚麻纱最小强力的提高效果更好,并可显著降低强力不匀率;除同捻向包缠纱外,各复合纱均可实现免浆织造;赛络菲尔纺和并捻复合对提高成纱断裂伸长率效果显著,而包缠复合降低亚麻纱毛羽的效果最好。     

Research on the influence of yarn parameters on the ultraviolet protection of yarns

Considering both the yarn parameters and the light interaction (reflectance and transmittance) between two adjacent yarns, an optical model was presented to understand the ultraviolet (UV) light penetrating a single undyed yarn and a lot of yarns. The optical model was verified with results of diffuse reflectance spectra measurement on wool yarn samples. This optical model was used to predict the factors influencing UV protection, including fibre diameter, yarn linear density, yarn twist, transmittance index and refractive index. The statistical predictive model was also set up to show the relationship between the yarn parameters and the UV protection (UPF values) of the yarns. Yarns with the fine diameter, large yarn linear density and low yarn twist had the high UV protection.     

Influence of fibre strength and yarn structural characteristics on tensile failure of blended spun yarns: a prediction model

The study reports on the static failure behaviour of P/V blended ring, rotor and air-jet spun yarns explained on the basis of fibre failure coefficient. Fibre failure coefficient is an index introduced to represent fibre break and slip in combination occurring during tensile failure. Fibre break/slip during tensile failure is found dependent on fibre strength, fibre cohesiveness and internal structural developments in yarns. Tensile failure behaviour of ring, rotor and air-jet yarns found to be different owing to their difference in fibre consolidation mechanism. The contribution of individual components towards fibre failure coefficient varies with the spinning technology. An attempt has been made to develop mathematical models to explain the spun yarn failure behaviour under static condition. The developed mathematical models have incorporated the fibre property (fibre strength) and few structural characteristics of yarns which are strategically selected to justify the essence of models to enhance the prediction capability. Individual models are developed for ring, rotor and air-jet yarns owing to their structural changes caused by their inherent fibre consolidation mechanism. The developed mathematical models are free from assumptions and based on pure applied mathematics and have very high potential for prediction of spun yarn failure behaviour.