Common problems and solutions in the use of cots and aprons
In spinning production, problems such as wrapping cots, cracking cots, concave aprons, broken aprons and clamping aprons are often encountered, which directly affect spinning quality and normal production. So, what are the common problems in the use of cots and aprons? How to solve it?
The most prominent problem in the production and use of COTS is the frequent occurrence of winding problems, resulting in production difficulties, affecting yarn quality and normal production. The use of soft elastic cots without treatment has a very significant effect on improving the yarn evenness, but the problem of winding is serious. There are two ways to solve the problem, one is to improve the winding resistance of cots, the other is to improve the production conditions (environment) and improve the adaptability of cots.
1) In order to improve the windability of cots, the surface of high hardness cots is usually coated with coating, a: B component is 1:2-1:3, and a few drops of D component (special winder) are added; the surface of cots can be micro treated by medium hardness cots, and a: B component is 1:10-1:15. The surface of low hardness cots is treated with special anti winding agent. The A: B component is 1:11 ~ 1:18, which can greatly improve the anti winding property of cots and has little effect on the yarn evenness.
2) The higher the sugar content of cotton, the easier it is to wrap the cot. Pay attention to control the use proportion of polysaccharide cotton. It is better not to exceed 30% in summer and 60% in winter. The cotton with high sugar content needs special sugar remover for pretreatment. The proportion of sugar remover can reach 100% in summer. In winter, a small amount or no sugar remover can be used according to the actual production situation.
3) Environmental temperature and humidity have a great influence on cot winding. Generally, the sugar content of Xinjiang cotton or Gansu cotton is more, which is more sensitive to the relative humidity of the workshop. The relative humidity of the spinning workshop should not exceed 60% in production. For the soft elastic cots that are not treated, the spinning workshop temperature in winter should be no less than 28 ℃, so as to maintain the elasticity and holding force of cots and reduce the phenomenon of draft failure.
4) Due to the electrostatic effect of spinning cellulose varieties, such as viscose, modal, Tencel, bamboo pulp fiber, etc., the cots are very easy to return to flower in the final parallel process, which not only has many broken ends, difficult to drive, but also has many defective products. Spraying antistatic oil agent on the surface of cellulose raw material package can effectively solve the problem that the cots in the final blending process are easy to return to flower.
Knotty yarn and draft problem
In the actual production, "lumpy yarn" often appears on the drawing frame and roving frame, and the spinning frame often fails to open, resulting in the increase of broken ends, yarn defects and production difficulties. Through analysis, the problem is mainly caused by the improper use of the cot apron in the draft area and the corresponding process configuration.
1) In order to improve the yarn evenness, the drafting technology of "tight separation, heavy pressure" or "two big and one small" (i.e. big roving twist, big spinning back separation and small spinning back draft multiple) is usually adopted. When it is in the critical process, although the yarn evenness is the best, it is also the most dangerous and prone to quality accidents, so the critical process should be avoided as much as possible.
2) According to the principle of spinning drafting, in order to make the drafting work smoothly, the actual holding force of the jaw composed of cot (apron) and roller should be adapted to the drawing force, and the drafting condition that the minimum holding force is greater than the maximum drawing force should be met. When the gripping force is not enough to overcome the stretching force, it will cause "pimple yarn" on the drawing frame and roving frame, and the phenomenon of drafting failure on the spinning frame.
3) When "lumpy yarn" appears on the drawing frame and roving frame or the drafting cannot be opened on the spinning frame, the first step is to check whether the draft components such as cots, aprons, rollers, upper and lower pins, pressure bars and cradle are in good condition, and replace the defective components in time; adjust the process configuration to avoid excessive drafting; the drawing frame can raise the pressure bar properly, enlarge the roller spacing or increase the draft spacing properly Increase the draft ratio of the back area; the roving frame and the spinning frame can be replaced by a larger spacing block, and the roller spacing can be appropriately enlarged or the draft ratio of the back area can be increased.
4) When the moisture regain rate of semi-finished products is large, it is also easy to produce "lumpy yarn" or draft phenomenon, especially when the raw materials are raining, rainy weather or holiday time is long, semi-finished products are more susceptible to moisture. As the moisture regain of semi-finished products increases, the friction coefficient between fibers increases accordingly, which makes drafting difficult. Therefore, when the moisture regain rate of semi-finished products is large, the relative humidity of the pre spinning process should be properly reduced, and the heat preservation and dehumidification work should be done well in advance during the holiday driving.
Problems such as concave in rubber ring
Sometimes, the spinning frame has concave upper apron, bent lower apron or back draft area. It is mainly caused by improper drafting technology in the middle zone.
1) When spinning polyester cotton varieties, the selected spacing block is small, which will cause the rubber ring jaws to be too tight, the movement of the upper rubber ring is not stable, resulting in slippage and dented, forming the middle concave of the upper rubber ring. Therefore, enlarging the spacing block properly can eliminate the concave phenomenon of the upper rubber ring.
2) The iron roller plays a driving and controlling role in the operation of the upper rubber ring. In the long-term use process, affected by the temperature and humidity and the residual acid substances on the surface of the rubber ring, the surface of the iron roller is easy to rust and pollute and rust the inner layer of the rubber ring, making the rubber ring unstable and broken. At present, the new technologies, such as the middle rubber roller, the middle and upper roller of carbon fiber, the middle and upper roller of aluminum lining, the middle and upper roller of reticulation and the upper pin of carbon fiber, are widely used, which can effectively solve the problem of drawing control in the middle area.
3) When spinning pure polyester or its blended varieties, it is easy to clamp the apron. The main reason is that after the end of spinning is broken, the front rubber roller or roller is twined with flowers, and the grip strength of the front jaw is reduced, while the polyester fiber is long and the traction force is large, which still drives the rubber ring to move forward, and the movement of the lower rubber ring at the lower pin is blocked, resulting in the clamping of the rubber ring. The other is the tension failure of the lower apron tension frame, which causes the lower apron to slip. Therefore, it is necessary to reduce yarn breakage as much as possible, make frequent rounds of the shift workers, deal with the breakage in time, and replace the failed tension frame in time.
4) The draft area after spinning must be loose. It is mainly caused by the insufficient holding power of the middle roller and the iron roller. First, check and replace the bad draft parts in the middle area, move the iron roller forward properly, increase the holding force in the middle area, and also increase the draft multiple in the back area.
Cot apron is an important spinning equipment which has great influence on yarn quality. All spinning enterprises should attach great importance to the management of cots. In view of all kinds of problems in the use of cots and aprons, they should be carefully analyzed and solved in combination with the actual production of the enterprise.