The Twist Unevenness of the double twister will make the Fiber Cohesion in each segment of the strand different and the inclination degree of the surface fiber different, which will affect the physical and mechanical properties such as the strength, elasticity, elongation, luster and wear resistance of the strand, as well as the appearance characteristics, as well as the style and quality of the fabric. In view of the Twist Unevenness of the double twister, look down quickly.
01
Causes
Uneven tension of the belt
Because the double twisting machine twists the strand by the spindle driven by the belt friction, the tension of the belt directly affects the spindle speed of the whole car. Because the Dragon belt itself has certain elasticity, and its tension is greatly affected by the climate. When parking in autumn and winter and for a long time, the large contraction of the Dragon belt will increase the tension and speed of the ingot, while in spring and summer, the opposite is true.
Tension wheel in and out position deviation
The in and out position of each tensioning wheel will directly affect the spindle speed of two adjacent spindles. There are strict requirements for the in and out position of the tensioning wheel in the technical conditions of the equipment. It is found that the deviation of each adjusting unit will affect the proximity of the belt and the spindle, and increase the spindle speed deviation.
Insufficient spindle lubrication
When the spindle rotates at high speed under the belt friction drive, it simultaneously acts on two torques, one is the rotating torque caused by the belt friction and the other is the resistance torque caused by the friction between the spindle and the spindle foot bearing. The two torques directly affect the spindle speed. The role of spindle oil is to form an oil film between the spindle tip and the spindle liner to reduce the friction resistance of the bearing on the spindle. Therefore, the lubrication of the spindle directly affects the spindle speed. The Twist Unevenness will be caused by the change of spindle speed, and will increase with the increase of the difference rate of spindle speed.
The big and small collet bearings are not flexible
The size of the double twister collet is realized by the rotation of two small bearings. If the collet bearing does not rotate flexibly or the cradle has insufficient clamping force on the collet, the normal yarn drawing speed may be affected. The speed of yarn drawing is bound to cause unevenness of yarn twist, and the greater the difference of yarn drawing speed, the more serious the unevenness of yarn twist.
Poor operation of ingot wing
If the production environment of the double twister is not good, such as the flurry of flower hairs or the poor cleaning of the machine, flower hairs will be sandwiched between the spindle wing and the spindle tube, which will make the spindle wing falter when rotating, thus causing uneven twist.
Improper setting of tension spring parameters
At the beginning of production, the Twist Unevenness of TDN-120 double twister used by our company is always high, once over 3.5%. After the research, it is found that the main reason is that the setting value of tension spring in spindle tensioner is too small, resulting in the high twist unevenness.
02
Solutions
process planning
Adjustment of spinning tension. Different varieties need different spinning tension. The basis for determining the tension is that it is more appropriate to wind the yarn 1.5-2.0 turns on the spinning wheel, and the maximum is not more than 2.5 turns.
Determine the ingot speed reasonably. In general, it should be determined according to the condition of breaking the head in 1000 ingots. The broken ends of fine yarn and high-grade variety are controlled within 5 pieces and medium and coarse yarn within 10 pieces. On the basis of meeting the requirements of output and quality, the maximum spindle speed is obtained. After random sampling inspection, the unevenness of twist can be controlled within 5%, and the unevenness of the whole trolley can be controlled within 2.5%.
Select the overfeeding rate correctly. The change of overfeeding rate affects the winding tension, thus changes the winding density of the package. Under the condition of forming, the overfeeding rate is selected according to the fineness of the yarn. Generally, the overfeeding rate is about 160%, so as to reduce the increase of broken ends caused by winding tension and the chance of uneven twisting.
Equipment status maintenance
Ensure the tension of the belt. Replace the winding belt with inflexible and bouncing operation, adjust its tension, ensure that the winding belt tension meets the specified standard, and ensure that the tension between the machine and the ingot is consistent. When using the special fixed gauge for correction, ensure that the distance between the belt and the spindle wheel is more than 2mm, and the distance between the belt and the tension roller is more than 2mm.
Adjust the pressure of the spindle wheel brought by the dragon. The high tension of the belt can increase the contact surface with the spindle wheel, reduce the unevenness of twisting, but at the same time increase the loss of the belt. Therefore, on the premise of satisfying the quality, the pressure of the spindle wheel brought by the dragon is relatively small, so as to extend the service life of the Dragon belt.
Check the tension device. For the peak twist of single spindle appearing on the machine, check the wearing condition of tension head, tension rod and tension head seat in the tension device in time. The tension head with inflexible expansion shall be replaced and repaired in time; the damaged tension rod, tension head seat and other components shall be replaced to ensure the minimum tension difference of each spindle, and the position of spindle shall be adjusted in time to make it in a reasonable position with the Dragon belt contact surface.
Check spindle bearing. Check and refuel the spindle drive bearing of the double twister, replace the spindle bearing that is not working well or damaged with the stop of the machine, ensure that the spindle speed difference between the spindles is controlled within the internal control index, and reduce the chance of weak twisting. Strengthen the inspection of spindle operation, eliminate the deteriorated spindle, reduce the spindle speed difference and yarn tension difference of the whole machine, and ensure the consistency of the whole machine.
Operation management
According to the user's requirements, the mode of overall yarn loading and overall yarn dropping is adopted to reduce the number of joints in the double twisting process.
Strictly implement the operation method, improper control of the brake release time will also cause local unevenness, and eliminate the untwisted yarn and weak twist yarn caused in the joint process. In the process of touring, when the stopper finds the end broken, step on the brake disc joint. When the joint is finished, twist the joint by hand, release the brake disc for 5-10 s, and when the yarn section in the untwisted area is fully twisted, loosen the hand roll and wind it onto the drum. The time from releasing the brake disc to winding the knotted yarn to the bobbin is selected according to the twist size, 7-10 s for large twist and 5-7 s for small twist.
After doffing, the stopper shall do a good job of cleaning. The residual yarn on the spindle wheel shall be treated in time to eliminate the reduction of spindle speed caused by winding and reduce the chance of weak twisting.
It is found that the unevenness of twist is 2.9% before power failure and 4.3% after power failure, so the stopping time and times of double twister should be minimized. When it is necessary to stop on holidays, it is necessary to ask for empty car delivery, and then drive again for trial driving.
