THEORETICAL STUDY OF THE EFFECTS OF SPINNING TRIANGLE HORIZONTAL OFFSET ON YARN TORQUE

Yarn torque is one of the important indexes of yarn quality, which is determined on the basis of the translation of fiber tension at the spinning triangle. Therefore, the fiber tension within a yarn was proposed to be the most influential factor governing the magnitude of yarn torque by Bnenett and Postle. Meanwhile, fiber tension is determined by the geometry of spinning triangle mainly, especially the horizontal offset of the twisting point to the symmetric axis of nip line. Therefore, the effects of horizontal offset of the ring spinning triangle on yarn torque was investigated in this paper. Firstly, a theoretical model of the residual torque within a yarn due to the fiber tension was given. The relationships between the yarn torque and the spinning triangle horizontal offset were analyzed theoretically. Secondly, as an application of the proposed method, a modified ring spinning system with a pair of offset device which can change the horizontal offset continuously were used and the yarn torque was simulated numerically with the horizontal offset changing continuously correspondingly. It is shown that in a symmetric spinning triangle (d=0), the yarn shows a higher radial bias of the fiber tensile and compressive stress, while a more and more uniform distribution of tensile and compressive stress within a yarn with the increasing of the horizontal offset. Therefore, in a symmetric spinning triangle, the yarn shows the highest torque, and the yarn torque decrease with the increasing of the horizontal offset in theory correspondingly.