- the twisting process of the spun yarn
(1) Twisting winding process
①The twisting of the spun yarn: the twisting of the sliver, the essence of which is to use the relative angular displacement between the cross-sections of the strips to make the original parallel and parallel fibers and the yarn axis tilt to change the structure of the strip. The sliver forms an approximately cylindrical shape from a flat shape.
②Winding of the spun yarn: the twisting and winding of the spun yarn are carried out simultaneously. Since the traveler is subjected to frictional resistance and air resistance on the runway, the speed of the steel ring lags behind the speed of the spindle, and the speed difference between the two causes winding.
③Regardless of contracture, the winding speed is equal to the speed of the front roller output.
It can be seen that the rotational speed of the wire loop or the twist applied to the sliver varies with the winding diameter. When the large diameter is wound, the speed of the wire ring is fast, and when the small diameter is wound, the rotation speed is slow, and the difference between the diameter and the diameter is about 1.5%, so that the twist of the bobbin is different by about 1.5%. However, in the subsequent axial unwinding, this difference will be compensated by itself without affecting the yarn twist.
(2) Selection of yarn twist coefficient and orientation
①Selection of yarn twist coefficient
The larger the twist coefficient, the greater the twist of the spun yarn, the higher the spun yarn strength, the less the yarn breaks, but the harder the hand and the lower the yarn yield. The yarn twist factor should be determined according to the product use and the quality requirements of the yarn.
Warp and weft: Warp yarns are subjected to tension and friction during the weaving process, and the strength requirements are high. The twist factor needs to be larger; the weft yarns are less stressed during the weaving process, and the excessive number is prone to weft shrinkage, and the twist factor should be smaller. Generally, the warp yarn is 10-15% higher than the weft yarn compared to the special number.
The twist factor of the knitting yarn is lower than that of the woven yarn, and is generally close to the twist coefficient of the weft yarn. Because the general knitwear is soft.
The finer the spun yarn, the smaller the twist factor. When the yarn is fine, the number of fibers is small and the strength is low.
The general twist coefficient is 330-400.
②the choice of fine yarn orientation: generally choose z twist, in the chemical fiber blending, in order to make the woven to get different styles, often use different directions.