Effect of Spinning Triangle and Production Speed of Hollow-Spindle System on the Bouclé Yarn Structure

This study aims to show the impact of both the width of the base of the spinning triangle and the production speeds of hollow-spindle spinning machines on the structure of ultimate multiple-thread-structure bouclé yarns and similar fancy yarns. A hollow-spindle spinning machine was used and bouclé yarns were made of a core thread, an effect thread and a (multifilament) binder. Initially, five bouclé yarns were made by setting the widths of the base of the spinning triangle at five levels, i.e. 4.5 mm, 7.5 mm, 10 mm, 13 mm and 16 mm. A further six bouclé yarns were made to show the changes that occur to the spinning triangle at various production speeds. The resulting fancy bouclé yarns were assessed by measuring the size, number and circularity ratio of bouclé profiles. It was found that at low production speeds, i.e. at start-up, that the spinning triangle was unstable, which adversely affected the structure of the final bouclé yarns. However, at production speeds higher than 17 m/min, the spinning triangle became stable, though such a stable spinning triangle had no impact on the structure of the resulting fancy bouclé yarns. The results of this study may help fancy yarn manufacturers to avoid making defective fancy yarns.

Investigation into four-roller compact spinning with air damper for improving yarn performance

Compact spinning, as a new kind of spinning technology, has gained wide attention because of its great reduction in spinning triangle and yarn hairiness. In order to meet the demand of high-grade clothing, research on further improving the performance of compact spun yarn is the emphasis. Of all the existing compact spinning systems, the four-roller compact spinning with lattice apron is most widely used at present because of its low cost. Therefore, this paper aims to put forward a new kind of device to improve yarn performance for four-roller compact spinning systems. Related experiments have been done to verify the efficiency of the device, and the mechanism is analyzed by computational fluid dynamics. The numerical simulation shows that the device can change the direction of airflow and increase the velocity in the directions of transverse condensing and thickness. It is shown that the air damper is convenient to use and has potential applications in spinning compact yarns with better performance.

Numerical Simulation and Analysis of Airflow in the Condensing Zone of Compact Spinning with Lattice Apron

The airflow field pattern in the condensing zone plays a vital role in the pneumatic compact spinning, which significantly affects the yarn's qualities. This study aimed to analyze the effects of the different negative air pressures on fiber condensing in compact spinning with lattice apron using ANSYS. The results of airflow simulations reveal that by increasing the negative pressure, the flow velocity increases, leading to a more tremendous increase in the transverse condensing effects. Additionally, a better convergence led to reduced fiber width and eliminated the spinning triangle. Experimental results showed that the three yarns spun with the highest negative pressure had better strength, hairiness, and evenness than those spun with lower negative pressure.

Theoretical study of the effects of the shape of the spinning triangle

The spinning triangle is an important area in the spinning process, and the shape of the spinning triangle influences the yarn qualities. This paper aims to theoretically study the effects of the spinning parameters on the shape of the spinning triangle. In this paper, a model of the spinning triangle considering force equilibrium and torque equilibrium was built. The initial strain of fibers in the spinning triangle was determined by the profile of the spinning triangle. The initial height of the spinning triangle was obtained by the width of the spinning triangle and the twist angle. Based on the initial condition and boundary condition in the model, the displacements of the twisting point were obtained. With the displacements of the twisting point, the height of the spinning triangle and the deviation angle of the center fiber in the final spinning triangle, which represent the shape of the spinning triangle, were calculated. In the analysis, the spinning tension, yarn twist, and yarn radius were chosen as the independent parameters to analyze the geometric change of the spinning triangle.

Theoretical research of spinning triangle division on spun yarn torque

Purpose The purpose of this paper is to theoretically study the effects of ring spinning triangle division on spun yarn torques. Design/methodology/approach The case that the spinning triangle is divided into two parts, primary triangles and final triangle, is investigated. Theoretical model of yarn torque was given by linking the fiber tension in the spinning triangle to yarn torque under the assumption that the arrangement of fibers (substrands) in the substrands (yarn) is hexagonal close packing. Then, as an application of the proposed method, 14.6tex cotton yarns were taken as an example for the numerical simulations. Findings The fiber tensions in the divided spinning triangles and corresponding yarn torques were simulated numerically by using MATLAB software. The effects of division proportions and number of primary triangles on spun yarn torques are analyzed theoretically. Originality/value It is shown that suitable spinning triangle division is benefit for reducing yarn torque.

Theoretical study of the effects on yarn strength in a modified ring spinning system

A modified ring spinning system using a dynamic twist-resistant device has been employed to produce yarn. The modified device blocks twist to propagate to the spinning triangle, which changes the distribution of twist in the spinning area and increases the height of the spinning triangle. In this paper, two kinds of yarn counts (30 and 40 Ne) are spun in the conventional and modified ring spinning with twist multipliers of 3.2, 3.6, and 4.0. The results show that the yarn spun by the modified ring spinning system possesses a higher strength compared with the conventional yarn except in the higher twist multiplier. The increase in yarn strength was theoretically analyzed according to the model of yarn strength. The yarn strength was calculated by considering the original fiber strain in the yarn and the fiber strain due to yarn strain. In the model, the fiber migration was considered and the fiber entanglement caused by fiber migration was ignored to simplify the calculation. Four potentially important parameters of the spinning triangle, the height of the spinning triangle, the migration coefficient, the inclination angle, and the spinning tension, were proposed and their individual and interaction effects on yarn strength were analyzed. The results demonstrate that yarn strength increased with the increase of height of the spinning triangle and the migration coefficient. The inclination angle and the spinning tension have a relatively small influence on yarn strength when the height of the spinning triangle is higher.

Research on the mechanism of the modified ring-spinning system using a dynamic twist-resistant device and its yarn quality

The spinning triangle is a critical area in the ring-spinning process; the geometry of the spinning triangle influences the distribution of the fiber tension, and affects the qualities of the spun yarn. In this paper, a kind of dynamic twist-resistant device that can affect the geometry of the spinning triangle is employed for improving the conventional ring-spinning system. The yarn twists between the front roller nip and dynamic twist-resistant device were captured in the spinning process using a high-speed camera. Comparing yarn twists of the two types of yarn, the modified yarns have a lower twist angle, indicating that the device can produce resistant torque. Particle Flow Code software was used to simulate the acts of the device on the yarn, and the results verified the existence of resistant torque. The resistant torque on the yarn affects the geometry of the spinning triangle and the distribution of fiber tension. In addition, 19.4 and 14.5 tex cotton yarns with three different twists, 700, 800 and 900 tpm, were produced by the modified and conventional ring spinning. The comparative study revealed that the modified yarns have a better performance in terms of yarn strength and hairiness, and show no significant difference in terms of the yarn evenness when compared with the conventional yarns at the same twist level. The mechanism of the effect of the dynamic twist-resistant device on yarn qualities is discussed by analyzing the distribution of fiber tension.