The evenness CV value level of the yarn is not only directly related to the single yarn strength of the yarn and the unevenness of the yarn strength, but also produces uneven yarn defects such as thick and thin details, which in turn affects the weaving preparation stage. process, causing weaving breakage, and in severe cases, it will affect the fabric style and cause the machine to stop during the weaving process. The spinning process is the most critical process that affects the CV value of the yarn line. Therefore, a reasonable and scientific basic configuration of the spinning process and how to better optimize some accessories of the drafting process of the ring spinning machine are carried out, so as to Improving uneven yarn evenness is an important quality issue that textile companies must face.
The influence of basis weight on yarn formation
In production practice, if a larger draft ratio is used, the probability of additional unevenness of the yarn will increase. When spinning the same yarn number, using a roving with a larger basis weight requires a larger draft of the spinning machine, and the greater the additional unevenness of the yarn. The ordinary ring spinning machine EJM128K and rovings of different basis weights were used for yarn forming tests. It can be seen that the spinning process uses rovings with larger basis weights, and the evenness CV value of the spun yarn continues to increase, and the evenness tends to deteriorate. , and the thick places and neps in the yarn also increase. A large roving weight can reduce the workload of the spinning operator in changing tubes. However, the larger the roving weight, the yarn evenness may deteriorate. Therefore, it is recommended that the workshop use a roving weight of 4.3 g/(10 m). Combed cotton roving.
The influence of the twist coefficient on the finished yarn
The influence of the roving twist coefficient on the evenness
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The reasonable selection of twist coefficient directly affects the yarn quality, evenness CV value, thickness, details and other indicators of spun yarn. From the analysis of various indicators, it is known that the additional friction force generated by the twist of the roving can effectively control the movement of the fiber. A reasonable twist coefficient increases the tightness of the yarn, thereby increasing the pressure on the contact points between the fibers in the yarn. , increasing the cohesion between fibers, the drafting strands are closely connected without splitting, and are held by the upper and lower rubber rings without flipping; during the spinning process, try to make the fiber speed-changing points concentrated, stable and forward The jaw transfer requires that the control force of the rear jaw fibers on the floating fibers in the yarn sliver is greater than the guiding force of the front jaws on the floating fibers, which will be more conducive to improving the evenness of the sliver. The test shows that the evenness level of the yarn is the best when the roving twist coefficient is 114. Considering that the roving used in the test is made from low-grade short-staple cotton, the cotton fiber length is short and the fiber grade is Therefore, using a higher twist coefficient is conducive to twisting the roving, so it is more reasonable to select a roving twist coefficient of 114.
The influence of spinning twist coefficient on evenness
Production practice shows that reasonable design of spinning twist coefficient It has great relevance to process production. The evenness, thickness and details of spun yarn will tend to deteriorate after the winding process. Scientific and reasonable twist coefficient design can effectively control the degree of deterioration.
The roller spacing rubber roller presses the left and right yarns
Front The distance between the middle rollers is related to the balance of the holding force and drafting force in the front area, the length of the floating area in the front area, and directly affects the CV value of the yarn line. The use of small roller spacing makes the floating fiber area in the front drafting zone, which originally bears most of the drafting, smaller, and the flow range of floating fibers is also restricted, which is conducive to shortening the length of the floating zone in the front area, fundamentally The fiber distance deviation is reduced, so the evenness CV value of the yarn is improved. In actual production, the front and middle roller gauge should be selected according to the length of the cotton fiber. If the fiber length is short, a small roller gauge should be selected, and vice versa, a larger roller gauge should be selected.
The influence of different front rubber roller pressure on the yarn evenness CV is inconsistent. As the pressure of the front rubber roller increases, the yarn evenness CV value There is a decreasing trend, indicating that evenness has been improved. The pressure of the front rubber roller is also related to the yarn count being spun. If the yarn count is thick, the pressure of the rubber roller should be appropriately reduced; if the yarn count is fine, the pressure of the rubber roller should be increased. However, excessive pressure on the front rubber roller will reduce the service life of the rubber roller. Considering all aspects, it is not suitable for long-term use, so the front rubber roller pressure is selected to be 160 N/double spindle.
Reasonable selection of spinning equipment and technology
Cots directly have a significant impact on yarn quality , the spinning performance of large-diameter cots is better than that of small-diameter cots. This is because under the same pressure conditions, the larger the diameter of the cot, the contact area between the cot and the roller will increase, and the control of the fiber will be strengthened. This is because the friction force boundary generated after the contact area between the rubber roller and the roller increases, which reduces the active area of floating fibers, causing the speed change point to shift forward, and the CV value of the yarn line is therefore improved. The larger the diameter of the rubber roller, the more fully and more stably it will hold the slivers during the drafting process; the yarn quality has been significantly improved by using large-diameter rubber rollers. It is recommended to use large-diameter rubber rollers in production and should not be used. For rubber rollers with too high surface hardness, usually choose soft elastic rubber rollers with a surface hardness of around 65 degrees Shore hardness.
It can be found that during the spinning process, the number of fibers with controlled cross-sections in the front drafting area is small, so the fiber control in the spinning drafting area is concentrated on a limited cross-section. It has strong control over the fiber movement state, so it changes the draft of the front area.The size of � has a relatively small impact on the uniformity of yarn formation. In the experiment, we focused on how to optimize and configure the process for the back draft area.
The reasonable configuration of the back drafting process parameters has a great impact on yarn quality. At present, small back zone draft multiples are commonly used in production. The back zone of woven yarns The draft ratio is generally 1.20 times to 1.40 times, and the draft ratio of the back area of knitting yarn is generally 1.04 times to 1.30 times. The center distance of the back rollers used in this article is 55 mm, the diameters of the middle and back rollers are both 25 mm, the spacing between the middle and back rollers is 30 mm, and the roving twist coefficient is 114. The yarn obtained by this process setting is not only good in yarn sliver , and can also reduce the time for workshop workers to change the machine; when the draft ratio of the rear area changes within a small range or the length of the cotton fiber does not change much, there is no need to adjust the gauge, which facilitates daily production management.
As the draft ratio of the back zone becomes smaller, the CV value of the yarn line shows a trend of first becoming smaller and then increasing. The draft ratio of the back zone is fixed with the spinning machine itself. The drafting gear is directly related. In actual production, the drafting multiple should be reasonably selected according to the configuration of different types of spinning frames and the roving twist coefficient. Generally, in actual production, it is recommended to select a smaller drafting multiple in the rear area. </p
