1 roving twist factor
When the roving twist coefficient is large, the roving density increases, the cohesion is good, the friction resistance between fibers increases, and the traction response increases. Under the condition that the back zone gauge and the back zone draft ratio remain unchanged, the yarn can not be untwisted effectively, and the yarn can enter the main draft zone with a large twist back, resulting in the phenomenon of draft not being opened. But the twist factor of roving should not be too small. If it is too small, it is easy to produce unexpected draft and details when feeding into the spinning frame, which will affect the product quality.
2 spinning guide range
When the moving direction of the yarn guide travel is the same as the twist direction of the sliver, the drawing force is the largest, and the holding force is less than the traction force, which leads to the phenomenon of draft failure. When the twist direction of the sliver is opposite to the moving direction of the yarn guide travel, the draft force is smaller, which is beneficial to reduce the draft failure.
3. The increase of roving ration roving ration means the increase of drafting force. Under the same cot condition and certain drafting ratio and roving twist coefficient in back zone, the gripping force of heavy ration roving is greater than that of light ration roving, so the gripping force of roving ration is higher. The ration of roving should be adapted to the gap between the nips, so as to avoid the violent fluctuation of the draft force at the nips during the spinning drafting process, which will affect the normal drafting of the spinning.
4 spinning roller gauge small roller gauge is conducive to the control of floating fiber in the whisker, so that the stretch force of the whisker is increased in the process of drafting, which is easy to cause the phenomenon of non opening. With the increase of roller spacing, the ability to control the floating fiber in the whisker is weakened, so that the fiber can be well controlled and drawn normally, and the phenomenon of no drawing is avoided.
5 drafting in the back area of spinning. With the increase of drafting multiple in the back area of spinning, the number of fibers in the cross section of the whisker entering the main drafting area is reduced, and the drafting force is reduced, which is conducive to the control of the fiber in the whisker by the drafting jaw, and reduces the phenomenon of draft failure. But generally speaking, it is not conducive to the improvement of yarn quality. At present, most of the production enterprises adopt larger center distance of spinning back roller, smaller back draft ratio and larger roving twist factor.
6. The nip gauge block with smaller nip gauge is helpful to strengthen the control ability of apron nip to draft yarn, and has better control ability to the edge fiber of the yarn when the fiber changes speed, so as to improve the yarn evenness. When the gauge block is increased, the control force of the apron jaw on the whisker is weakened, which can reduce the phenomenon of draft failure, but has a certain impact on the yarn quality.
7 spinning roller pressure roller pressure is small, drafting jaw control of the fiber is weak, resulting in the fiber in the strip can not be well controlled and the phenomenon of draft does not open. When the roller pressure increases, the friction boundary of the drafting jaw increases, so that the fibers in the whisker can be well controlled and drawn normally. The pressure of the front, middle and back of the cradle should be reasonably distributed to avoid the phenomenon that the draft fails in the rear area.
For the new Cots with coating layer on the surface, the surface coating is thicker, the surface holding force of COTS is greatly weakened, and the slippage rate of COTS is higher in the drafting process, so that the yarn can not be effectively controlled and the yarn is easy to get out of the stiff end. However, the coating layer on the surface of the old cot is thin, the friction coefficient on the surface of the cot is large, the holding force of the cot to the yarn is greater than the drawing force of the yarn, and the yarn can be drawn normally. Because there is no chemical treatment on the surface of the untreated cot, the cot surface can directly contact with the whiskers, with large friction coefficient, large gripping force, and can overcome the large stretching force, which is an effective measure to solve the problem of draft failure. In winter, because of the low temperature, the leather roller is hard without treatment, the slip rate is increased, and it is easy to get hard head.
In daily production, the raw materials are always in a state of change, the fiber quality length in sliver is longer (such as increasing the content of combed sliver) or the length uniformity is good, the friction coefficient between fibers in the sliver becomes larger, and the traction response increases during the drafting process. Under the condition of the same spinning process, the drafting jaw can not effectively control the fibers in the sliver, As a result, the sliver can't be drawn normally and the phenomenon of drawing can't be opened, so other processes need to be adjusted.
10. When the humidity of the temperature and humidity workshop increases, the friction coefficient between the fibers in the whisker increases and the friction resistance response increases, which increases the stretching force of the whisker. Under the condition of constant spinning process, the drafting jaw can not effectively control the fibers in the whisker, resulting in the phenomenon of drafting failure. The workshop should reasonably control the temperature and humidity according to the seasonal changes, raw material conditions and other factors to ensure normal production and avoid the phenomenon of draft failure.
