1. Twisting process of spun yarn
(1) Twisting and winding process
1. Twisting of spun yarn : The essence of twisting yarn is to use the relative angular displacement between the cross sections of the yarn to cause the originally straight and parallel fibers to tilt the yarn axis to change the structure of the yarn. The yarn strips are formed into an approximate cylindrical shape from a flat shape.
2. Winding of spun yarn: Twisting and winding of spun yarn are carried out at the same time. Because the wire ring is subject to friction and air resistance on the track, the speed of the steel ring lags behind the spindle speed, and the speed difference between the two causes winding.
3. Without considering twist and shrinkage, the yarn winding speed is equal to the front roller output whisker speed:
It can be seen that the rotation speed of the rigid wire loop or the twist added to the yarn changes with the change of the winding diameter. When winding a large diameter, the speed of the traveler is fast, and when winding a small diameter, the speed is slow. The speed difference between these diameters is about 1.5%, so the twist of the bobbin differs by about 1.5%. However, during the subsequent axial unwinding, the difference will be compensated without affecting the yarn twist.
(2) Selection of twist coefficient and twist direction of spun yarn
1. Selection of twist coefficient of spun yarn Select
The larger the twist coefficient, the greater the twist of the spun yarn, the higher the strength of the spun yarn, and the fewer ends of the spun yarn, but the hand feels harder and the spun yarn output is lower. The twist coefficient of the spun yarn should be determined according to the product use and the quality requirements of the spun yarn.
Warp yarns and weft yarns: The warp yarns bear tension and friction during the weaving process, so the strength requirements are high, and the twist coefficient needs to be larger; the weft yarns bear less tension during the weaving process and are too large. The number is prone to weft shrinkage defects, and the twist coefficient should be smaller. Generally, the warp yarn is 10-15% higher than the weft yarn with the same special number.
The twist coefficient of knitting yarn is lower than that of woven yarn, and is generally close to the twist coefficient of weft yarn. Because generally knitted fabrics need to be soft.
The finer the spun yarn, the twist coefficient should be smaller. Because when the yarn is thin, the number of fibers is small and the strength is low.
The general twist coefficient is 330-400.
2. Selection of twist direction of spun yarn: Z twist is generally used. When blending chemical fibers, in order to obtain different textures in the weave style, often using different twist directions.
2. Spun yarn winding process
1. Cop yarn Forming requirements: tight winding, clear layers, and no entanglement during high-speed unwinding. The forming of the bobbin requires tight winding, clear layers and no entanglement, which is conducive to high-speed unwinding in subsequent processes. In addition to the direct weft yarn being limited by the size of the shuttle cavity, the package size or capacity of the bobbin should be increased as much as possible to reduce the number of tube changes during doffing in the spinning process and unwinding in subsequent processes, and improve equipment utilization and labor productivity. .
2. The winding method of spun yarn: conical cross-winding.
3. Spun yarn winding process
(1) Short-stroke lifting of the ring plate At a time, wrap the yarn two layers.
(2) When the ring plate rises, the denser yarn winding is called the winding layer; when the steel ring plate descends, the denser yarn winding is called the binding layer.
(3) The ring plate rises a certain distance after each lift, which is called the step-up of the ring plate.
(4) In the tube bottom forming part, the winding height and level of each layer of yarn gradually increase; after the tube bottom forming is completed, the winding height and level of each layer of yarn increase to one. constant.
(5) The bobbin forming angle is γ/2=12.5-140.
(6) The movement requirements of the ring plate, the winding equation of the spinning machine, the winding speed, and the lifting speed. </p
