Bojun Xu

Theoretical study of fiber tension distribution at the spinning triangle

The spinning triangle is a critical region in the spinning process of yarn. Its geometry influences the fiber tension distribution and thus affects the properties of spun yarns. In conventional ring spinning, on the one hand, the spinning triangles are often asymmetric due to the frictional contacts of fibers with the bottom roller, which interferes with the twist propagation into the spinning triangle zone, and thus leads to the migration of the axis fiber at the front roller nip. On the other hand, the yarn spinning tension has an obvious angle with the vertical axis perpendicular to the nip line. Therefore, in this paper, a theoretical model of the fiber tension distributions in the general spinning triangle has been proposed by considering both the inclination angle of the spinning tension and the migration of the axis fiber at the front roller nip according to the principle of minimum potential energy. Two shape parameters were introduced to describe the skew level of the geometry of the spinning triangle in the analysis. The effects of shapes of the spinning triangle on the fiber tension distributions were investigated. The results show that the fiber tension distribution at the spinning triangle tends to more non-uniformity with increasing the asymmetry of the spinning triangle. The effects of both shape parameters on the fiber tension distributions are similar under the assumption that the spinning triangle height H is constant. In addition, a more long-narrow shape of the spinning triangle shows more uniform fiber distributions.

Numerical simulation of a three-dimensional flow field in compact spinning with a perforated drum: Effect of a guiding device

Compact spinning with a perforated drum is one of the most important kinds of pneumatic compacting. It utilizes the transverse air force in a perforated drum to condense the fiber bundle in order to effectively eliminate the spinning triangle and improve the qualities of spun yarns. Therefore, the emphasis in research on a flow field in the condensing zone is always on the difficulty of pneumatic compact spinning. In this paper, the three-dimensional flow field of compact spinning of a perforated drum with a guiding device is investigated using Fluent software. First, a three-dimensional model, using AutoCAD Software, of the condensing zone is given. Then, the numerical simulations, by using Fluent software, of the three-dimensional flow field in compact spinning of a perforated drum with three guiding devices (type A, type B, and type C) and without a guiding device are presented, respectively. It is shown that the effective range of the negative pressure in the condensing zone of the compact spinning system with a perforated drum and guiding device increases significantly as compared with that of compact spinning without a guiding device. The flow field distribution is symmetric with respect to the central line of air-suction flume. The fiber strands move toward the center under the left–right symmetric transverse air force, which achieves transverse converging effects. Meanwhile, the static pressure shows a wavy distribution due to the influence of round holes. Furthermore, it is proved that the comprehensive effect of the type C guiding device is the best. Finally, the theoretical results obtained are illustrated by spinning experiments.

Research on the Compact-Siro Spun Yarn Structure

Compact-Siro spinning technology is one of the most widely used spinning methods. It is conducted on a compact ring frame by simultaneously feeding two rovings into the drafting zone at a predetermined separation. In fact, Compact-Siro spinning incorporates the features of both Compact and Siro-spinning systems. In this paper, the structure of CompactSiro spun yarn is investigated. By using a DZ3 video microscope, the horizontal structure of Compact-Siro spun yarn, Sirospun yarn, Compact yarn and Ring spun yarn were obtained. It is shown that compared with Compact single yarn, Compact-Siro spun yarn has a more compact and clear surface structure, a more uniform and smooth shape, and less hairiness. Then the cross section structure of Compact yarn and Compact-Siro spun yarn were obtained by using Hardy’s Y172 thin cross-section sampling device and the DZ3 video microscope. It is shown that compared with Sirospun yarn, the cross-section of Compact-Siro spun yarn is smoother and closer to being circular. Meanwhile in the Compact-Siro spun yarn body, the fibers of two substrands show axial symmetrical distribution approximately, which is beneficial for spun yarn qualities, especially for improving the yarn evenness and hairiness. Finally the results obtained were illustrated in spinning experiments.

Theoretical Study of the Effects of the General Division of a Ring Spinning Triangle on Fibre Tension

Su X, Gao W, Liu X, Xie C, Xu B. Theoretical Study of the Effects of the General Division of a Ring Spinning Triangle on Fibre Tension. FIBRES & TEXTILES in Eastern Europe 2016; 24, 2(116): 37-43. DOI: 10.5604/12303666.1191425 Theoretical Study of the Effects of the General Division of a Ring Spinning Triangle on Fibre Tension *Xuzhong Su1,2, **Weidong Gao1,2, Xinjin Liu1,2,3, Chunping Xie1,2, Bojun Xu1,2

Research on the Performance of a Drafting Device for the Four-Line Compact Spinning System

2Key Laboratory of Eco-Textile, Ministry of Education, Jiangnan University, Wuxi 214122, P. R. China **E-mail:gaowd3@163.com Abstract Compact spinning is one of the most important improvements of traditional ring spinning, which is implemented by adding a fibre condensing device to condense the fibre bundle and decrease the spinning triangle, thereby improving the qualities of yarn. Pneumatic compact spinning is the most widely used compact spinning method at present. Four-line compact spinning is one of the most important kinds of pneumatic compact spinning, which is implemented by using a Lattice apron to achieve fibre condensing, decrease the spinning triangle and improve the yarn qualities, especially reducing yarn hairiness. In this paper, the performances of drafting devices for Four-line compact spinning were studied. First the structure and performance of an SDDA2122PH pneumatic cradle equipped with a new kind of block top roller retaining bar were discussed and the pressure distribution of the cradle presented firstly. Then 7.3 tex T65/JC35 was spun on an EJM128K spinning frame equipped with an SDDA2122PH pneumatic cradle, the pressure distributions measured, and the spun yarn qualities were measured and analysed accordingly. Then the acting mechanism of three kinds of top pin: a common top pin without a press bar, a top pin with a front pressure bar, a top pin with a back pressure bar, with respect to yarn qualities was analysed firstly, and then JC 18.2 tex, JC60/T40 18.4 tex and T 18.4 tex yarns were spun on an EJM128K spinning frame equipped with different top pins. Then the qualities of the spun yarns were analysed according to the acting mechanism of the top pin. The results show that by using the new block top roller retaining bar, the pressure of the pneumatic cradle is larger and more stable, thereby improving the spun yarn’s comprehensive qualities. For cotton yarn, we can reduce yarn hairiness by using a top pin with a pressure bar; for chemical fibre and cotton blended yarn, yarn strength can be improved by using a top pin with a pressure bar, and for chemical fibre pure yarn, the usage of a top pin with a pressure bar is beneficial for improving yarn strength and evenness, but not for yarn hairiness and yarn thin and thick places.