Yarn Quality: Reasonable Selection Of Spinning Equipment And Technology

The CV level of yarn not only directly affects the yarn strength and yarn strength irregularity, but also produces uneven yarn defects such as coarse and fine yarn, which will affect the weaving preparation stage, resulting in weaving breakage, and seriously affecting the fabric style, causing the machine to stop during weaving.

Spinning process is the most critical process to affect yarn yarn dry CV value. Therefore, it is an important quality problem for textile enterprises to carry out rational and scientific spinning process basic configuration and how to optimize parts of the drafting process of ring spinning frame so as to improve yarn evenness.

Effect of quantitative twist factor on yarn quality

In practice, the greater the drafting multiple is, the greater the probability of additional unevenness will be.

When spinning the same yarns or the same yarn, the larger the roving is, the larger the drafting ratio is, and the additional irregularity of the yarn will also increase.

The spinning test of ordinary ring spinning frame EJM128K and different quantitative roving can be used. It can be seen that the CV value of spinning yarn is increasing and the evenness is deteriorating, and the coarse and NEP yarn also increases.

A large quantity of roving can reduce the workload of spinning rovers, but the larger the roving amount is, the worse the yarn evenness will be. Therefore, it is recommended that the roving yarn should be 4.3 grams /10 meters in workshop.

。

The roving twist factor is of great importance to the reasonable layout of the frictional boundary of the spinning frame.

The reasonable twist factor selection directly affects the yarn quality, yarn CV value, roughness, detail and so on.

According to the analysis of various indexes, it is known that the additional friction field produced by roving twisting can effectively control the movement of the fibers, and the reasonable twist coefficient increases the yarn tightness so as to increase the pressure on the contact points between the fibers and increase the cohesion between the fibers. The drafting system must be tightly split without being held by the upper and lower leather rings without turning over. In the spinning process, we should try to make the fiber's speed change point centralized and stable and move forward to the jaws. This requires that the control force of the post jaw fiber on the floating fibers in the yarn is greater than that of the front jaw on the floating fiber dimension, which will be more conducive to improving the evenness of the yarn.

The test shows that the yarn evenness is the best when the roving twist factor is 114. Considering that the roving used in the experiment is shorter than the lower staple cotton ratio, the length of the cotton fiber is shorter and the fiber grade is poorer. Therefore, the higher twist factor is beneficial to the twisting of the roving yarn, so the roving twist coefficient 114 is more reasonable.

The effect of twist factor on yarn evenness.

Production practice shows that reasonable design of yarn twist factor has great relevance to process production. The evenness, roughness and detail of yarn will deteriorate after winding process. Scientific and reasonable design of twist coefficient can effectively control its deterioration.

The roller roller is pressurized to make yarn.

The distance between the front and middle rollers is related to the balance between the grip force and the pulling force in the front area, which is related to the length of the floating zone in the front area, and directly affects the yarn CV value.

Through a simple pformation of the roller seat of the EJM128K type spinning frame, a smaller distance of 17 mm is obtained and compared with the 18 mm and 19 millimeter distance of 18 mm and 19 mm without modification. When the distance is 17 mm, 18 mm and 19 mm, the CV value of the yarn is 12.61%, 12.79% and 13.05% when spinning the distance of the roller is 17 mm, 18 millimeter and 19 millimeter.

It can be seen that the level of yarn evenness is improved by decreasing the distance between the front and middle rollers.

This is because the small rollers are used to make the floating fiber area smaller than the original draft area which originally assumed most drafting, and the flow range of the floating fiber has also been restrained, which is conducive to shortening the length of the floating zone in the front area and fundamentally reducing the fiber offset. The yarn CV is worth improving.

In actual production, the distance between the front and middle rollers should be selected according to the length of the cotton fiber. The small roller spacing should be chosen for the short fiber length, whereas the larger roller spacing should be chosen.

Through the drafting test on the EJM128K spinning frame produced on the two spinning machine in Shanghai, we analyzed and compared the yarn CV value. It was found that the effect of different front roller pressure on yarn evenness CV was obviously inconsistent. With the increase of the pressure of the front cot, the yarn dry CV value decreased, indicating that the evenness of the yarn was improved.

The amount of pressure on the front rubber roller is also related to the thickness of the yarn that is spun. Under the condition of coarse yarn, the pressure of the rubber roller should be reduced appropriately.

However, the pressure of the front rubber stick is too much to reduce the service life of the cots. Considering it is not suitable for long-term use, the pressure of the front rubber stick is 160N/ double spindle.

{page_break}

Reasonable selection of spinning equipment and technology

Theoretically, cots have a direct effect on yarn quality. The spinning performance of large diameter rubber rollers is superior to that of small diameter cots. This is because the larger the diameter of COTS is, the greater the contact area between cots and rollers under the same pressure condition, and the control of fibers will be strengthened.

This is due to the larger friction area caused by the contact area between the cots and the rollers, which reduces the active area of the floating fibers, and makes the shifting point move forward, so the yarn CV value is improved.

The larger the diameter of the cots is, the more adequate and stable the grip is on the drawing process. The quality of the yarn is obviously improved by using the large diameter cots. It is suggested that the rubber cots with large diameters should be used in production, and the rubber cots with high surface hardness should not be used. Usually, the soft elastic Cots with a surface hardness of about 65 degrees of hardness are chosen.

We can find that in the spinning process, the front zone drafting is controlled by the cross section.

Therefore, the control of fibers in the spinning drafting area is concentrated on a limited cross-section and has strong control over the movement state of the fibers. Therefore, the effect of changing the drafting ratio of the front zone on yarn evenness is relatively small. In the experiment, we will mainly consider how to optimize and configure the drawing process in the back zone.

The reasonable allocation of drawing parameters in the back zone has a great influence on yarn quality. At present, the small draft area is generally used in the production. The draft area of the woven yarn is generally 1.20 times ~1.40 times, and the draft area of the knitting yarn is generally 1.04 times to 1.30 times.

The center area of the rear roller is 55 mm in this paper. The middle and rear roller diameters are 25 mm, the middle rear roller gauge is 30 mm, the roving twist coefficient is 114. The yarn obtained from this process is not only good for yarn, but also can reduce the change time of the workers in the workshop. When the draft area changes within a small range or the cotton fiber length changes little, it does not need to adjust the gauge, which is convenient for daily production management.

With the smaller drafting ratio in the back zone, the yarn CV value shows a trend of becoming smaller and then larger. The drafting ratio of the back zone is directly related to the draft tooth wheel fixed by the spinning frame itself. In actual production, the draft ratio should be selected according to the different types of spinning frame configuration and roving twist coefficient. In general, it is suggested to choose smaller draft area multiple draft in the actual production.