Principle of rotor spinning
Rotor spinning is a new method of free end spinning. It called the free end spinning is to turn the raw materials (fiber sliver or roving) into single fibers first, and then the central process of rotor spinning is twisting cup. The twisting cup is a small metal cup with an air vent on it. The inner chamber of the cup is separated from the outside with a gland. The only way to communicate between the inside and outside of the cup is the cotton conveying channel and the yarn guide tube. When the cup rotates at a high speed, it is equivalent to a small centrifugal fan, which discharges the air inside the cup outwards, causing the air pressure in the cup to decrease. Under the single pressure difference of opening, it is absorbed into the cup through the cotton conveying channel, and condenses to the groove with the largest diameter in the cup - the condensation groove by the centrifugal force and the rotary airflow. At the same time, if a piece of yarn is put into the yarn guide tube, because of the same reason, the yarn head is also quickly attracted to the condensation tank, and joins with the condensed fiber bundle. With the cup rotating at a high speed, it is twisted into yarn, and then the yarn is continuously pulled out by the yarn guide roller, and is led to the tank cylinder to be rolled into a package.
Self twist spinning is a method of low speed and high yield. The spinning speed is 10-20 times that of ring spinning, the process flow is short, the spinning count range is small, the fiber damage is small, the power, the floor area, labor intensity, and flower return are greatly reduced.
Compared with ring spun yarn, self twist yarn has a special structure. It is a kind of double or multi ply yarn. This kind of strand is different from other strands. It has a twisting area (right twisting, untwisted, left twisting) with alternating positive and negative twisting directions, as shown in Figure 3-2.
Structure Diagram of Self Twisted Yarn
Due to the existence of untwisted area in the self twisted yarn, the yarn is soft and its strength is lower than that of ring spun yarn with the same count. After the fabric is made of different twist directions in each area of the yarn body, it is easy to have streaks, streaks, etc. on the surface. It can be overcome by adding twist in combination with appropriate technological measures.
Compared with ring spinning, rotor spinning is two spinning methods with different mechanisms, and the yarn structure has its own characteristics.
Rotor spinning is free end spinning. The fiber is fed in a fixed amount, and the yarn is formed by coagulation and twisting. It does not need to be drawn (drawn). Therefore, the evenness of rotor spinning is good. Rotor spinning strengthens the opening and cleaning process in the front spinning area, and the fibers are fully opened to remove impurities. Therefore, the neps and impurities of rotor spun yarn are 30% less than those of ring spun yarn. The yarn body structure is loose, so the water absorption is strong, the dyeing rate is high, and the yarn is rich. However, its strength is 5~io% lower than that of ring spun yarn, so the rotor spun fabric is characterized by smooth surface, clear grain (twill), straight body and good wear fastness.