During the spinning process, when the spinning tension is greater than the strength of the cotton yarn, the yarn will break. This is the essence of yarn breakage. Therefore, it is a systematic project to increase the minimum value of cotton yarn strength and reduce the CV value of single strength.
Drawing process
The drawing process is to improve the straightness and parallelism of the fiber and ensure the normal spinning Drafting is an important process to improve the strength of the yarn. It has a great influence on the uneven quality of spun yarn and the formation of long segment details.
Five technical measures
1) For varieties with large fluctuations in raw sliver quality , the number of draw combinations can be changed from 6×8 to 8×8. Improve the merging effect and improve the quality unevenness of the final merging.
2) Reduce the CV value of cooked strips. The first is to pay attention to the quality control of raw sliver; the second is to appropriately increase the number of half-cooked sliver quality inspections; the third is to run three shifts and inspect the quality three times per shift, and control each time with quality CV; the fourth is to conduct timely tracking and analysis when the quality CV exceeds the standard, and distinguish Is it caused by the high difference in the quality of the input sliver, or is it caused by defects such as the rubber roller or the pressurizing mechanism, the automatic stop mechanism for broken or missing slivers, or the drafting mechanism’s vacuum suction is too large and unstable, etc., and targeted measures must be taken. Measures; Fifth, temperature and humidity control is stable.
3) Prevent long spun yarn details caused by undesirable factors in the drawing process. The defects of long warp knots in spun yarn caused by drawing, which is about 7.5 times of draft of roving and about 40 times of spun yarn, and a total draft of 300 times, cannot be solved in the roving and spun yarn processes. Therefore, the drawing process should be eliminated. Reduce the CV of cooked strips while maintaining long details. This involves whether the process design is reasonable, whether the drafting elements and pressurizing mechanism are normal, whether the operation management and machine cleaning are good, etc.
4) Properly configure the drafting process to improve fiber straightness and parallelism. According to experience: the draft of the front area is 1.75 times, the draft of the front area is within 3.5 times, the draft of the end area is about 1.25 times, and the corresponding draft of the front area is 6.5 to 7 times, so that the fibers entering the front area As the number increases, the drafting force increases. Pay special attention to whether the holding force of the front rubber roller is greater than the drafting force to prevent the critical state where the minimum value of the holding force is greater than or equal to the maximum value of the drafting force. When the quality or state structure of the sliver input behind the machine fluctuates, causing long details and long slub yarn defects in the spun yarn, the drafting multiple or roller spacing in the rear area can be appropriately enlarged. This is a negative method to reduce the drafting force. It is more reasonable to use active methods to increase grip strength.
5) Eliminate drawing mechanical waves. The mechanical wave in the drawing process will not necessarily significantly deteriorate the CV of the spun yarn, but it will form long segments of thick details after high-power drafting in each process. If the cotton yarn is of lighter quality and overlaps with uneven evenness details, the strength of the cotton yarn will decrease and a weak loop will appear. Therefore, it is necessary to prevent mechanical waves from occurring in cooked bars.
Do a good job in 4 management tasks
1) Regular inspection and automatic stop when broken or missing bars The sensitivity of the mechanism. If the operator finds that the strip is missing and the sensitivity is poor, it should be repaired in time.
2) Strengthen operation management, improve the operating level of lathe operators, strictly prohibit stripping, prevent cotton yarn from being poorly wrapped, overlapping input cotton slivers, and remove defective products such as output light strips Keep the machine clean and tidy to prevent tampons from being attached to flowers.
3) Test the CV of cooked strips on all machines every day or every shift. Machines with deteriorated mechanical wave and dry CV should be repaired in time. Machines that often suffer from such defects should be repaired promptly. Problems such as parts and processes should be studied and improved.
4) It is strictly prohibited for stop workers to cut the rubber roller with a knife or to damage the rubber roller if handled improperly. Special personnel should regularly check the running status of rubber rollers and bearings. Operation stop workers can regularly use anti-winding tools. Use a special cleaning agent to wipe away the melted cotton wax oil on the surface of the rubber roller.
Roving process
Roving quality control Spun yarn quality has a direct impact. The roving drafting process should be reasonably configured through process selection to reduce the evenness CV and quality unevenness of the roving as much as possible, and create good conditions for improving the evenness and strength of the spun yarn.
1) The twist coefficient of roving is closely related to the quality of spinning yarn and the configuration of process parameters. Appropriately increasing the twist coefficient of the roving is beneficial to the control of fibers in the drafting area of the spinning yarn, improving the yarn evenness, and preventing the formation of details due to accidental drafting during the unwinding process of the roving. However, an excessively high twist coefficient often results in poor drafting of the spun yarn, an increase in coarse details, or even failure to draft, resulting in a large number of ends broken. In actual production, factors such as roving quantity, fiber condition, performance of spinning drafting mechanism and drafting process parameters should be comprehensively considered for reasonable configuration.
2) The monitoring of roving mechanical waves should be strengthened through periodic testing, and outdated spindles and machines that produce more harmful mechanical waves should be promptly organized and repaired to eliminate them. The twist of the roving is less, and the cohesion between the fibers is loose. It is necessary to pay attention to the role of the false twister to prevent the poor fiber structure caused by factors such as the roving channel being not smooth and the condition of the collector being poor, affecting the draft of the spun yarn and increasing the details of the yarn.
3) The roving elongation not only affects the evenness and quality unevenness of the roving, but also has a greater impact on the quality unevenness, evenness and strength unevenness of the spun yarn. , efforts should be made to reduce the elongation of rovings and strictly control the differences in elongation between front and rear rows of rovings, large and small yarns, and between spindles. At the same time, attention should be paid to reducing the accidental drafting of the mature sliver on the elevated guide bar after the machine, ensuring that the anti-detail device of the roving frame works normally, and eliminating the impact of the details of the roving frame’s switching on and off on the spun yarn breakage. </p
