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The drawing process has a greater impact on the quality of the spun yarn

Update:12-09-2020
Summary:

In the spinning process, when the spinning tension is g […]

In the spinning process, when the spinning tension is greater than the strength of the cotton yarn, it will break, which is the essence of spun yarn breakage. Therefore, increasing the minimum value of cotton yarn strength and reducing the single-strength CV value is a systematic project.

Drawing process

The drawing process is an important process for improving the parallelism of fiber straightening, ensuring the normal draft of the spun yarn, and improving the yarn strength. It has a greater impact on the unevenness of the spun yarn quality and the formation of long segment details.

Grasp 5 technical measures

1) For varieties with large fluctuations in the quality of card sliver, the combined number of drawing slivers can be changed from 6×8 to 8×8. Improve the combined effect and improve the unevenness of the final combined quality.

2) Reduce the CV value of cooked bar quality. The first is to pay attention to the quality control of card sliver; the second is to appropriately increase the number of quality inspections for semi-cooked slivers; the third is to run three shifts to inspect the quality three times per shift, and each quality CV is used for control; the fourth is to track and analyze in time when the quality CV exceeds the standard. Is it caused by the high quality difference of the input sliver, or the rubber roller or the pressure mechanism, the automatic stop mechanism when the sliver is broken or missing, the drafting mechanism is too large and unstable, and it must be taken in a targeted manner Measures; Fifth, stable temperature and humidity control.

3) Prevent the long details of the spun yarn caused by the bad factors of the drawing process. Spinning from the drawing through the roving drafting about 7.5 times, the spun yarn about 40 times drafting, and the total drafting is 300 times. The long warp of the spun yarn cannot be solved in the roving and spinning process. Therefore, the drawing process should be eliminated. Reduce the CV of cooked sliver under the premise of long details. This involves whether the process design is reasonable, whether the drafting element and the pressure mechanism are normal, whether the operation management and the machine are clean and tidy.

 

 

4) Reasonably configure the drafting process to improve fiber straightness and parallelism. Based on experience: the draft in the front and rear zone is 1.75 times, the draft in the front zone is within 3.5 times, the draft in the end and rear zone is about 1.25 times, and the corresponding draft in the front zone is 6.5 to 7 times, so that the fibers enter the front zone. The increase in the number results in an increase in the drafting force. Special attention: whether the gripping force of the front rubber roller is greater than the drafting force, to prevent the critical state due to the minimum gripping force being greater than or equal to the maximum drafting force. When the quality or state structure of the input sliver after the machine fluctuates and causes the spun yarn to produce long details and long thick yarn defects, the draft ratio or roller gauge of the rear zone can be appropriately enlarged. This is a negative method to reduce the drafting force. It is more reasonable to use positive methods to increase the grip strength.

5) Eliminate drawing mechanical waves. The mechanical waves in the drawing process may not significantly deteriorate the CV of the spun yarn evenness, but the thick details of the long fragments will be formed after high drafting in each process. If the quality of the cotton yarn is too light and the yarn section overlaps with the uneven details, the strength of the cotton yarn will decrease and there will be a strong weak ring. Therefore, we must prevent the occurrence of mechanical waves in the cooked strips.

Do 4 management tasks

1) Regularly check the sensitivity of the self-stop mechanism when the bar is missing, and the operator should repair it in time if the sensitivity of the bar is not good.

2) Strengthen operation management, improve the level of operator's operation, prohibit slivering, prevent poor cotton wrapping, input sliver overlap, clean output light slivers and other defects, and keep the machine clean and prevent flowers from being attached to the sliver.

3) Measure the cooked and even CV of all machines every day or every shift. The machine should be repaired in time for the deterioration of mechanical wave and even CV, and research and improvement should be made on the parts and processes that often cause such defects.

4) It is strictly forbidden for the stopper to cut the rubber roller with a knife or improperly handle the rubber roller. Special personnel regularly check the running status of the rubber roller and the bearing. The running stopper can regularly wipe off the wax melted oil on the surface of the rubber roller with a special anti-winding cleaning agent.

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