An experimental investigation of yarn tension in simulated ring spinning

Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed rig, which can rotate a yarn at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yarn rotating speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions, a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns.     

The interaction of moving yarns with stationary surfaces

Ever since the spinning process was developed, numerous research studies have been conducted and many precision instruments have been developed to control the tension in moving yarn. These efforts, however, have remained insufficient because many factors that need to be considered have not been handled in an integrated manner. To overcome this limitation, various parameters that affect the tension must be examined and the relationships among them must be discovered. Hence, the present paper reviews a variety of parameters for yarn moving from a ring spinning machine to a winding machine. These two machines, in particular, involve a series of phenomena in which the yarn passes over a stationary surface. In addition, the relevant parameters related to force, tension, and yarn motion need to be separately investigated in each spinning section (e.g., the balloon, the section from the bobbin to the traveler, and the section from the bobbin to the unwinding package) and at each part (e.g., the traveler, yarn guide, package, and tensioner).     

Study on Spinning triangles in the common ring spinning and Super draft ring spinning systems

In the paper, one kind of super draft ring spinning frame with four drafting rollers and corresponding three drafting zones were introduced. The yarn qualities spun by the super draft ring spinning frame were analyzed by studying the shape of spinning triangles. Using the high speed camera system OLYMPUS i-speed3 and one kind of transparent front top roller, the spinning triangles were captured, and the geometry size of spinning triangle were measured. Then, according to the theoretical model of fiber tension in the spinning triangle, fiber tension distributions in the spinning triangles were presented by using Matlab software. Using the combed roving of 350 tex as raw material, three kinds of cotton yarns, 27.8 tex (21^S), 18.2 tex (32^S) and 14.6 tex (40^S), were spun in the common ring spinning frame with three different suitable spindle speeds, travelers and twist factors. Using the combed roving of 350 tex and 500 tex as raw material, 14.6 tex cotton yarns were spun in the super draft ring spinning frame with three different drafting ratios at back zone. It is shown that with the increasing of spindle speed, a more asymmetric shape of spinning triangle would be produced, and lead to worsen yarn evenness. With the decreasing of traveler weight, the height and horizontal deviation of the spinning triangle is decreased, and may lead to better yarn evenness and less long hairiness. By taking suitable large yarn twist factors, the comprehensive qualities can be improved. Comparing with the common ring spinning, the spinning triangle is larger in the super draft ring spinning. That is, in the super draft ring spinning, the fibers in the strand in the front roller nip are more dispersed, and not benefit for yarn qualities. Therefore, the compact device was introduced into the super draft ring spinning, and the cotton pure yarns and blend yarns were spun, and the yarn qualities were measured and analyzed.     

Tension dynamics of the fibers in a triangular plane flow of bundle

The ring spinning method is broadly used for manufacturing various forms of yarns in various application fields in thanks of the outstanding yarn characteristics and the well established processing technology. However, applying the ring spinning for manufacturing functional yarn, for example, the core-spun yarn, often raises serious yarn quality problems. Especially, surface defects make it difficult to extend the technology to various end-purposes. Dynamic state of the tension of fibers in the spinning triangle that is considered as a triangular plane flow field plays an important role in causing the defects. In this study, a theoretical model describing the tension behavior of the fibers in the triangular plane flow field was derived and the availability of the model was tested experimentally. Results showed that the steady-state experiments brought good corresponding results with those from the theory, which identifies the effectiveness of the theoretical model. The tension dynamics of the fibers in spinning triangle could be expressed as a 1st order system, while the spinning triangle length and the process velocity could majorly affect the tension dynamic characteristics.     

Theoretical study of fiber tension distribution at Solospun spinning triangles

Spinning triangle is a critical region in the spinning process of staple yarn. Its geometry influences the distribution of fiber tension in the spinning triangle and affects the properties of spun yarns. Taking appropriate measures to influence the spinning triangle geometry and improve the quality of yarn has attracted great interesting recently. Solospun technology is one of the most important representatives, which is implemented by dividing ring spinning triangle into several small primary triangles and one final triangle using a Solospun roller. Therefore, theoretical study of fiber tension distributions at Solospun spinning triangles is presented in this paper. First, a theoretical model of the fiber tension distributions in Solospun spinning triangles is given by using the principle of minimum potential energy. Second, the relationships between fiber distributions and spinning triangle parameters are analyzed theoretically. Especially, the effects of horizontal offset of the twisting point to triangle symmetric axis of nip line d on fiber tension distributions are discussed and numerical simulations are given. Finally, the properties of spun yarns are evaluated and analyzed by using the simulation results.     

Analysis of resistance torque on the compact spinning with suction groove

The compact spinning with suction groove can eliminate or decrease the spinning triangle by airflow compacting and shape condensing of the groove, so the yarn hairiness can be reduced effectively for long staple fiber. But the resistance torques produced by the spinning tension and the negative pressure of airflow influence the twist propagation. This paper analyzes variation of the friction coefficient between the fiber bundles and the groove. The transfer process of the moment of the spinning tension and airflow is studied in the variation of the friction coefficient. The expression of the resistance torque is established in the gathering area. The results show that the many factors influence the resistance torque, such as the horizontal friction coeffecient between the fiber bundles and the groove, the spinning tension and the negative pressure, as well as the angle between two suction holes etc. The proper negative pressure and the spinning tension can prevent twist propagation, and can reduce the yarn hairiness and improve the yarn quality.     

Reducing ring spun yarn hairiness via spinning with a contact surface

In this study, spinning with a contact surface was introduced as a simple and energy-saving method to reduce spun yarn hairiness. Theoretical analysis indicated that yarn hairiness could be reduced via a sufficient long contact surface applied in other part of yarn formation zone in addition to spinning triangle. Then, a simple contact apparatus was installed on ring frame to validate the theoretical analysis. Results proved that yarn hairiness was reduced via a contact surface in the yarn formation zone. However, unevenness was deteriorated for most yarns spun with contact apparatus during the spinning, which might be due to fiber mass concentration. Most of yarns spun with contact apparatus had a lower strength than the conventional yarns. This might be because evenness deterioration to decrease yarn strength overpowered hairiness reduction to increase yarn strength for most yarns spun with a contact surface.     

Studies on reduction of yarn hairiness by nozzles in ring spinning and winding by airflow simulation

Reduction of yarn hairiness by nozzles in ring spinning and winding is a new approach. Simulation of the airflow pattern inside the nozzles provides useful information about actual mechanism of hairiness reduction. The swirling air current inside the nozzles is capable of wrapping the protruding hairs around the yarn body, thereby reducing yarn hairiness. Since production rate of winding is very high and the process itself increases yarn hairiness any method to reduce the hairiness of yarns at this stage is a novel approach. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern inside the nozzles using Fluent 6.1 software. In this study, both S- and Z-type nozzles having an axial angle of 50° and diameter of 2.2 mm were used for simulation studies. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential to the inner walls of the nozzles. S- and Z-twisted yarns of 30 tex were spun with and without nozzles and were tested for hairiness, tensile and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e. the S3 values) for yarn spun with nozzle is nearly 49–51 % less than that of ring yarns in case of nozzle-ring spinning, and 15 % less in case of nozzle-winding, while both the yarn types show little difference in evenness and tensile properties. Upward airflow gives best results in terms of hairiness reduction for nozzle-ring and nozzle wound yarns compared to ring yarns. Yarn passing through the centre of the nozzle shows maximum reduction in S3 values.     

A novel method to reduce hairiness level of ring spun yarn

The quality of ring spun yarns is largely determined by its level of hairiness. The existence of hairiness inevitably affects the quality of ring spun yarns. This paper presents an innovative method on lowering the level of hairiness of ring spun yarns. This can be achieved by shooting compressed air to the yarn, through a swirl nozzle comprising a yarn duct and an airjet nozzle attached to a traditional ring spin frame. When compressed air is applied from the air-jet nozzle to the yarn duct, the swirling air flow tucks surface fibers of the ring spun yarns into its body. Four controllable variable parameters for the process, supplied pressure, nozzle position, twist factor and spindle speed, and their effects on the lowering of yarn hairiness will be clarified. Their impact on the quality of the yarn is statistically analyzed, and the optimum outcome of the combination of parameters for the process, will thus be determined.     

Study on the packing density of structurally modified ring spun yarn

Fibres being the structural unit of a yarn, its nature, composition and arrangement can influence structure and properties. The performance of yarn changes with arrangement of its constituent fibres. Arrangement of fibres in a yarn being system specific, different spinning system results different arrangement of fibres causing variation in product performance. A change in the arrangement of fibres in an already formed yarn can be brought about by suitable physical and/or chemical treatment. A treatment to remove a component is expected to cause changes in final arrangement of fibres in a yarn. In the present study, polyester/PVA blended yarn was modified through dissolution of the later component. The resultant change in structural arrangement on dissolution was assessed by the change in radial packing distribution of fibres. Migration index, helped in identifying the location that was influenced more in the redistribution. In the parent yarn, PVA had a preferential tendency to predominate near the core. On dissolution of PVA, creation of open space was expected and collapsing of the structure led to a possible rearrangement of fibres and reduction in diameter of yarn. Fibre denier, blend ratio and twist factor were also found to influence packing density both in parent and modified yarn. Unlike published reports, interestingly, an increase in fibre packing density was observed on dissolution of PVA. Average packing density in parent yarn was found to lie at a yarn radius between 0.07 mm to 0.09 mm while for the modified yarn it was between 0.05 mm to 0.07 mm.     

利用喷嘴减少苎麻纱毛羽的探讨

本文从喷嘴在纺纱中的几个实例出发，根据它们产品毛羽少的共性，在苎麻纺纱实验中采用了喷嘴与环锭纺的方法，以期减少苎麻环锭纱的毛羽。     

Stability analysis of the yarn ballooning without air drag

In this paper, under the assumption of yarn constant tension, the steady motion analysis of yarn ballooning without air drag for various yarn forming process and the stability analysis for the yarn ballooning equation are presented in a different way. The stable and instable areas are yielded by means of some control conditions.     

An experimental study of influence of filament and roving location on yarn properties during embeddable and locatable spinning

This study was focus on the influence of filament and roving location on yarn properties during embeddable and locatable spinning (ELS). ELS composite yarns were produced with various filament and roving locations on an experimental ring spinning frame. Besides yarn formation zone configurations, ELS yarn properties were compared including yarn hairiness, unevenness and tensile properties. Results showed that spinning triangles became larger; however, the reinforced composite spinning strand length kept constant. With a constant filament-roving spacing on each side of ELS, Filament spacing variations caused no significant changes of spun yarn hairiness, tenacities, imperfections and unevenness CV. For roving location variations with constant filament spacing, the reinforced strand length became longer as the roving spacing increased. Hairs exceeding 3 mm were lower for ELS yarn spun with 4 mm and 10 mm roving spacings than that spun with 6 mm, 8 mm and 12 mm roving spacings. Roving spacing variations had a trivial influence on ELS yarn unevenness; whereas, yarn tensile index variation coefficients fluctuated dramatically due to hairiness variations for different roving spacings.     

Quality Improvement of Upland Cotton (Gossypium hirsutum L.)

Abstract

Quality of cotton can be defined through seed or fiber properties, but is most often associated with fiber properties that influence processing into yarn and textile products. Global competition in the production and consumption of cotton fiber combined with technological evolution of yarn manufacturing has spurred renewed efforts to enhance cotton fiber quality. Cotton fiber quality can be improved through genetics, crop management, and postharvest processing. Knowledge of the effects of fiber properties on processing and their inheritance, relationships, and environmental influences is necessary to formulate improvement strategies. Breeding to improve fiber quality has traditionally focused on enhancing measures of the longest fibers or fiber strength for ring yarn manufacturing systems. With the technological evolution of yarn manufacturing from solely ring-based spinning to predominately rotor and potentially in the near future air-jet spinning, needs for fiber profiles have been revised for these spinning systems. Successful rotor spinning requires high fiber strength for all yarn counts, along with fiber fineness for fine count yarns. The even more productive air-jet spinning requires a minimum, but uniform fiber length, fiber fineness, and to a lesser extent strong fiber. In contrast, ring spinning requires a minimum fiber length, fiber strength, and to a lesser extent fiber fineness. Breeders do not conduct direct selection for yarn properties because of impracti-calities, thus they select for fiber properties that influence processing, so-called indirect selection. The inherent environmentally induced variability in fiber properties presents challenges to enhance them through breeding or biotechnological approaches. Because variability in fiber properties is problematic to fiber processing, future-breeding and biotechnological approaches should simultaneously focus on enhancing fiber properties and reducing variation. This paper will review strategies to enhance fiber profiles through genetic approaches while ameliorating their variation.     

Structural analysis of finer cotton yarns produced by conventional and modified ring spinning system

Yarn structure plays an important role in determining the properties of spun yarns. Recently, a modified spinning technique has been developed for producing a low torque and soft handle singles yarn by modifying the fiber arrangement in a yarn. Comparative studies revealed that the finer modified yarns possess significantly higher strength and lower hairiness over the conventional yarns of the same twist level, implying a different structure of finer modified yarn. Thus this paper aims to quantitatively study the structures of the finer conventional and modified cotton yarn (80 Ne) produced at the same twist level. Various measuring techniques, namely the Scanning Electron Microscope (SEM), cross section technique and tracer fiber technique, are adopted to analyze their structural characteristics, including fiber configuration, fiber spatial orientation angle, fiber packing density, yarn surface appearance, and fiber migration behavior. Results showed that finer modified yarns exhibit a smoother surface and much more compact structure with less hairiness. The fibers in the finer modified yarn have a complicated fiber path with relatively lower fiber radial position, larger migration frequency and magnitudes. In addition, it was noted that 73% of fibers in the finer conventional yarn follow concentric conical helix, which is contrary to those in the coarser conventional yarn. The analyses conducted in this paper provide deep insights into the mechanism of modified spinning technique and evidential explanations on the difference of properties between the finer conventional and modified yarns.     

Correlation of yarn tension with parameters in the knitting process

Tension control is an important factor in producing high quality knitted products and in maintaining good processing condition. Yarn tension during knitting is subject to be affected from many elements of the machine and process parameters. Several factors including yarn feeding speed, feeding angle, and needle gauge that are considered to influence on the tension variation were investigated. Yarn feeding speed did not show high contribution to the tension variation but feeding angle of yarn did show high correlation with the tension. No or negative correlation of the tension with needle gauge was found from the results. In order to keep well-determined process condition in the knitting manufacturing, it is strongly suggested that all knitting elements and parameters should be in the integrated control circumstance.     

The effect of spinning parameters on mechanical and physical properties of core-spun yarns produced by the three-strand modified method (TSMM)

The effect of spinning parameters on core-spun yarns properties manufactured using three-strand modified method (TSMM) was analyzed. Of the various spinning parameters, strand spacing, yarn linear density and yarn twist have a crucial effect on core-spun yarn properties. To achieve the objectives of this research, general physical properties of core-spun yarns together with existing standards were thoroughly studied. First of all, the strand spacing and yarn linear density were optimized. Afterwards, the effects of variation of yarn twist and sheath roving linear density on core-spun yarns properties were investigated. Finally, the physical and mechanical properties of TSMM yarns were compared with those of siro and conventional ring core-spun yarns counterparts. It was found that, the best strand spacing and yarn linear density to produce core-spun yarns are 8 mm and 45 tex, respectively. Results showed that, tenacity of TSMM yarns increases up to a certain twist level beyond which it reduces. The result confirmed that 45 tex yarns produced by three rovings of the same count are superior with regards to tenacity and hairiness. The optimized yarns produced by three-strand modified method enjoy superior physical and mechanical properties in comparison to the ring and siro core-spun yarns.     

Influence of the core-sheath weight ratio and twist on the tensile strength of the ring core yarns with high tenacity filaments

Core spun yarns are applied for various purposes that especially require the multi-functional performance. This research reports on the core spinning effect on the yarn strength. We prepared various core yarns by combining different kinds of high tenacity filaments in core with cotton staples in sheath with various twist levels in the ring spin system. And the tensile strength was tested to investigate the contribution of the core-sheath structure to the core yarn strength. The influence of the twist level was also checked up on the relationship between the core-sheath structure and the yarn strength. Results turned out that the core-sheath weight ratio had influence on the tensile properties of the ring core-spun yarns in different ways according to the core filaments used for the yarn. Increasing the twists yielded a monotone decreasing strength for the aramid and the basalt core yarns, while the PET core yarns showed almost unchanged strength, which could be ascribed to the extensional property of the filaments.     

Scaling up the production rate of nanofibers by needleless electrospinning from multiple ring

Mass production of nanofibers is crucial in both laboratory research and industry application of nanofibers. In this study, multiple ring spinnerets have been used to generate needleless electrospinning. Multiple polymer jets were produced from the top of each ring in the spinning process, resulting in thin and uniform nanofibers. Production rate of nanofibers increased gradually with the increase of the number of rings in the spinneret. Spinning performance of multiple ring electrospinning, namely the quality and production rate of the as-spun nanofibers, was dependent on experimental parameters like applied voltage and polymer concentration. Electric field analysis of multiple ring showed that high concentrated electric field was formed on the surface of each ring. Fiber diameter together with production rate of needleless electrospinning was dependent on the strength and distribution of the electric field of the spinneret. Needleless electrospinning from multiple ring can be further applied in both laboratory research and industry where large amount of nanofibers must be employed simultaneously.     

Comparative study of cellulase treatment on low stress mechanical properties of cotton denim fabric made by torque-free ring spun yarn

Cellulase is useful for bio-polishing cotton fabrics which enhances their aesthetic performance instead of stonewashing process. Torque-free ring spun process is a widely used technique to produce newly low-twist and balanced torque yarns with soft hand. In this paper, denim fabrics woven with torque-free ring spun yarn and conventional ring spun yarn respectively were treated with cellulase under the same condition and their fabric handle, expressed as low stress mechanical properties, such as tensile strength, bending, shearing, compression and surface performance were investigated by Kawabata Evaluation System for Fabric (KES-F). After cellulase treatment, both denim fabrics revealed better flexibility, elasticity recovery, raised shearing stiffness, fluffier and improved smoothness. While torque-free ring spun yarn made denim fabric showed a better fabric handle than conventional ring spun yarn made denim fabric.