Spun Polyester

The causes of various broken ends in spinning and the ways to avoid them
Yarn breakage is the main harm in spinning production: it affects the output of spinning frame, reduces the production efficiency; increases the labor intensity of blocking people; it is easy to cause the increase of fabric defects, resulting in a large range of quality fluctuations; it increases the consumption of flyback, loopback and machine materials; therefore, yarn breakage is the obstacle to the development of high-yield, high-quality, low consumption and large package production.

Yarn breakage can be generally divided into two categories: yarn breakage before yarn formation and yarn breakage after yarn formation.

1. Analysis of yarn breaking before yarn forming

It refers to the end breakage before the spinning of the front roller. The main reasons are as follows:

1.1 roving breakage

If the roving always breaks near the upper commutation, it may be caused by the small twist of the roving; if the roving always breaks near the lower commutation, it may be caused by the high position of the spinning guide rod; the roving details caused by the front spinning machinery may also cause the increase of the yarn breakage.

1.2. The bad sense of responsibility, unclean cleaning and infrequent tour of the car stopper result in the accumulation of flower on the bell mouth and empty roving, as well as the broken ends of spinning caused by the bad temperature and humidity in the workshop, such as the rubber roller, leather ring and roller.

2. Analysis of yarn breakage

Refers to the break of the yarn from the front roller to the bobbin during the twisting and winding process. The main reasons are as follows:

2.1 influence of ingot speed

When the spindle speed is increased, the broken ends are increased. The reason is that after the spindle speed is increased, the centrifugal force produced by the rotation of the steel ring is increased, and the tension of the yarn is also increased, resulting in the increase of the end breakage. When the spindle is rotating at a constant speed, the distribution of yarn drop and breakage is as follows: small yarn is the most, large yarn is the least, medium yarn is the least, and its proportion is 5:2:3. After eliminating the factors such as bad air conditioning, mechanical operation and cleaning work, bad bobbin and roving, etc., the causes of yarn breakage can be reduced by about 30 percentage points by using frequency converter to adjust speed.

2.2 influence of wire coil weight

The weight of the coil affects the spinning tension. The heavy steel ring and the large spinning tension increase the friction between the steel ring and the yarn and increase the yarn breakage; the light steel ring, the small spinning tension and the large air ring cause the yarn to collide with the separation plate, and cause the interference between the adjacent two spindles, resulting in the increase of the yarn breakage. When selecting the weight of the coil, the following factors should be considered:

2.2.1 yarn type

The coarser the yarn is, the stronger the single yarn is, the heavier the weight of the steel ring is. When spinning the chemical fiber, the elasticity of the chemical fiber is better and it is easy to stretch. Under the condition of the same weight of the steel ring, the friction coefficient between the chemical fiber yarn and the steel ring is larger and the tension of the gas ring is smaller, so the formation of the gas ring is larger and the head is easy to break. Therefore, the weight of the steel ring when spinning the chemical fiber is 2-3 than that of the cotton, and 6-8 when spinning the medium and long fiber 。

2.2.2 ingot speed

When the spindle speed is high, the centrifugal force and the tension of the yarn increase, so the weight of the steel ring should be reduced properly to reduce the breakage rate.

2.2.3 influence of service time of steel ring

Under the same conditions, the number of steel rings varies with the running time of the ring. When a new or repaired ring gets on the train, the friction coefficient between the ring and the ring is large, and the ring must be controlled slightly; with the increase of the ring service time, the friction coefficient between the ring and the ring decreases, and the ring should be increased properly; when the ring declines to the later stage, the runway wear becomes deformed, and the weight of the ring should be reduced appropriately. The service cycle of the ring is related to the variety and structure of the yarn and the spindle speed. The smaller the yarn number is, the longer the service life of the ring will be; the faster the spindle speed is, the shorter the service life of the ring will be. The service life of the flat collar is 12 months, and it is repaired once every 6 months; the service life of the cone collar is 16 months; however, with the small batch, diversification of products, and the increase of number changing, the service life of the ring is shortened to: the flat collar is repaired once every 4 months, and it is scrapped in 8 months; the cone collar is scrapped in 13 months; in this way, the broken ends can be reduced and the yarn quality can be guaranteed.

2.2.4 diameter of ring and length of bobbin

When the ring diameter increases, it is mainly when the winding diameter is small, the tension increases more. If a heavier steel ring is used, the air ring shape is more straight at the position of large winding diameter and small diameter, which is more likely to cause large yarn breakage. Therefore, when the diameter of the ring increases, the weight of the steel ring should be reduced; the increase of the height of the bobbin will increase the yarn tension and the maximum radius of the air ring, resulting in the increase of the broken end, so the steel ring should be increased to solve the problem.

2.2.5 ring model

In practice, it is found that the weight of steel ring should be selected according to the type of ring. Under the same conditions, the use of taper ring spinning is more important than the use of flat ring spinning, which can increase the volume capacity, reduce the number of doffing and reduce the breakage.

2.3. The selection of ring and ring models and the influence of matching on the end breakage

The type and coordination of ring and ring affect the yarn channel size of ring and the balance state of ring operation, thus affecting the yarn breakage. In practice, it is found that the suitable sizes of flat rings are more extensive, but the broken ends increase under the current situation of small batch, multi variety production and frequent number change; while the cone ring can adapt to frequent number change, but the broken ends are more when spinning fine and medium-sized yarns. In the actual production, the type of ring is generally determined, and the type of steel ring needs to be selected. When choosing the type of steel ring, it is necessary to consider such factors as suitable spinning type, yarn thickness and spindle speed.

2.4 reasonably determine the service cycle of steel wire ring

With the high-speed operation of the steel ring, the wear to a certain extent, the coordination between the steel ring and the steel ring is poor, the running stability is poor, the yarn tension fluctuates greatly, and the broken ends increase; therefore, the service cycle of the steel ring must be reasonably determined. The service cycle of the coil is closely related to the raw material, yarn number, spindle speed and winding. Under normal circumstances, the coarser the yarn number, the higher the spindle speed, and the larger the package, the shorter the cycle of steel wire ring exchange. In practice, it is found that when the taper ring is used to spin medium and fine sized yarn, the steel ring will be replaced as soon as it falls behind in spinning, otherwise large area of end breakage will occur.

2.5 effect of twist on break

The twist of yarn increases in a certain range, and the strength of yarn increases, which is beneficial to reduce the breakage. When the quality of raw cotton is poor, there are many short fibers, the maturity is poor, and the fiber is thin, increasing the twist by about 2% can effectively reduce the end breakage, but increase the yarn hairiness.

Safety operation rules for spinning maintenance workers

1. Be familiar with and implement the relevant safety operation regulations of the car stopper and the ingot belt worker.

2. Before working, cut off the power supply first, and remove the drive belt after the machine stops stably, then dismantle all parts.

3. The removal and lifting of long parts shall be coordinated with each other, under the command of a specially assigned person, and the actions shall be consistent.

4. When comparing the hands with the roller, tie the roller firmly to prevent the roller from falling and hurting people.

5. The removed parts shall be placed properly.

6. Dismantle the roller top screw, add gasoline regardless of the accuracy, and inform the white iron worker after adding other oil.

7. During the test run, it is necessary to check whether other people work on the machine and say hello before driving.

8. Strengthen the management of oil, acid, alkali, etc., and wear protective equipment when using acid and alkali.

9. The safety operation regulations of the air compressor must be implemented when taking care of the air compressor.

10. The oven is only allowed to bake steel bell, and it is forbidden to bake inflammable articles.

11. When the machine is running, it is forbidden to adjust the tension of the drive belt.

12. The doffer repairman must know the safety knowledge of electrician and implement the safety operation regulations of fitter.

13. Strictly implement the general safety technical regulations and the safety operation regulations of common tools.