The uneven twist of the double twister will make the fiber cohesion in each section of the strand different, and the inclination of the surface fiber will be inconsistent, which will affect the physical mechanical properties and appearance characteristics of the strand such as strength, elasticity, elongation, gloss and wear resistance. The style and quality of the fabric. For the problem of uneven twist of the double twister, look down.
01
cause
Dragon belt tension is uneven
Because the double-twisting machine relies on the dragon belt friction drive spindle to twist the strands, the tension of the dragon belt directly affects the spindle speed of the entire car. Because the dragon belt itself has a certain elasticity, and its tension is greatly affected by the climate. When parked in autumn and winter and for a long time, the shrinkage of the dragon belt causes the tension to increase, which increases the speed of the ingot, and the opposite in spring and summer.
Tension wheel in and out position deviation
The position of each tension wheel will directly affect the spindle speed of two adjacent spindles. The technical conditions of the equipment have strict requirements for the position of the tension wheel. It has been found in practice that the deviation of each adjustment unit will affect the proximity of the dragon belt and the spindle, increasing the deviation of the spindle speed.
Insufficient spindle lubrication
The spindle rotates at high speed under the friction drive of the dragon belt. It simultaneously acts with two moments, one is the rotation torque caused by the friction force of the dragon belt, and the other is the resistance torque caused by the friction force of the spindle and the spindle foot bearing. The magnitude of these two moments directly affects the speed of the spindle. The role of the spindle oil is to form an oil film between the tip and the spindle to reduce the frictional resistance of the bearing to the spindle. Therefore, the lubrication of the spindle directly affects the spindle speed. The change of spindle speed will inevitably cause uneven twist of the strand, and the uneven twist will increase with the increase of the difference rate of spindle speed.
Clamp bearing size is not flexible
Double-twisting machine chucks rely on two small bearings to rotate and wind the package. If the chuck bearing rotation is not flexible or the clamping force of the cradle on the package is insufficient, it may affect the normal yarn speed. The speed of the yarn drawing speed will inevitably cause uneven twisting of the strand, and the greater the difference in the yarn drawing speed, the more serious the uneven twisting of the strand.
Incorrect operation of spindle
If the production environment of the twisting machine is not good, such as flying hairs or poor machine cleaning, it will cause flower hairs to be pinched between the spindle and the spindle tube, which will cause a setback phenomenon when the spindle rotates, resulting in uneven twist.
Improper setting of tension spring parameters
TDN-120 type double twister used by our company in the early stage of production, the twist unevenness of several double twisters has been high, once more than 3.5%. After research, it was found that the main reason is that the setting value of the tension spring in the spindle tensioner is too small, resulting in uneven twisting.
02
solution
technological design
Adjustment of spinning tension. Different varieties use different spinning tension. The basis for judging the tension is that it is more appropriate to wind the yarn from the spinning wheel on the spindle for 1.5 to 2.0 turns, and the maximum should not exceed 2.5 turns.
Reasonably determine the spindle speed. Under normal circumstances, it should be determined according to the situation of the broken head at 1,000 spindles. For fine yarns and high-end varieties, the number of broken ends is controlled within 5 and the medium and thick yarns are controlled within 10, and the maximum spindle speed can be achieved on the basis of meeting the output and quality requirements. After random sampling inspection, the twist unevenness can be controlled within 5%, and the unevenness of the entire vehicle can be controlled within 2.5%.
Correctly select the overfeed rate. The change of overfeed rate affects the winding tension and thus changes the winding density of the package. In the case of forming, the overfeed rate is selected according to the fineness of the yarn, which is generally about 160%, so as to reduce the increase in the breakage caused by the winding tension and reduce the chance of uneven twisting.
Equipment status maintenance
Guarantee the tension of the belt. Replace the inflexible running belt and the running belt, adjust the tension to ensure that the tension of the belt conforms to the specified standard, and ensure that the tension between the machine and the spindle is consistent. When calibrating with special rules, ensure that the distance between the dragon belt and the spindle wheel is about 2 mm or more, and the distance between the dragon belt and the tension roller is about 2 mm or more.
Adjust the pressure the dragon brings to the spindle wheel. Large tension of the dragon belt can increase the contact surface with the spindle wheel and reduce uneven twist, but at the same time it will increase the loss of the spindle belt. Therefore, under the premise of satisfying the quality, the pressure of the dragon belt to the spindle wheel is too small to control, 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 table, it is necessary to timely check the wear of the tension head, tension rod and tension head seat in the tension device. For the tension head that is not flexible, it should be replaced and repaired in time; replace the damaged tension rod and tension head seat and other components to ensure that the tension difference of each spindle is minimum, and adjust the position of the spindle in time so that it contacts the dragon belt The noodles are in a more reasonable position.
Check the spindle bearing. Inspect and lubricate the spindle drive bearings of the double twister, and replace the spindle bearings that are malfunctioning and damaged with the stop, to ensure that the spindle speed difference between the spindles is controlled within the internal control index, and the chance of weak twisting is reduced. Strengthen the inspection of spindle operation, remove 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
The combined yarn process reflects the setting of fixed length. According to user requirements, the overall yarn and overall doffing modes are adopted to reduce the number of joints in the double twisting process.
Strictly implement the operation method, improper brake release time will also cause local unevenness, and prevent non-twisted yarn and weakly twisted yarn caused during the joint process. When the stopper found a broken head during the tour, he stepped on the brake disc joint. When the joint was completed, he twisted the joint by hand and released the brake disc for 5 s-10 s. When the yarn section in the non-twist zone was fully twisted Then loosen your hand and wind up on the bobbin. The period of time from the release of the brake disc to the winding of the knot yarn onto the package is selected according to the twist size, 7 s to 10 s with a large twist, and 5 s to 7 s with a small twist.
The stopper should do the cleaning work after doffing, and the residual yarn on the spindle wheel should be handled in time to eliminate the decrease in spindle speed caused by the entangled yarn and reduce the chance of weak twist.
The equipment has a great influence on the twist after being shut down and restarted. In the production, it was found that the twist unevenness of the machine before the power failure was 2.9%, and the start-up test after the power failure was 4.3%. When you need to stop on holidays, you must ask for an empty car to be delivered, and then drive and retry the drive.
