Spinning of spun yarn is the main hazard in spinning production: it affects the output of spinning frame and reduces the production efficiency; it increases the labor intensity of car stoppers; it is easy to cause fabric defects to increase and cause large-scale quality fluctuations; increase the number of flowers, yarns and machine materials Consumption; therefore, decapitation is an obstacle to the development of high-yield, high-quality, low-consumption, and large-package production.
Filament breaks can be broadly divided into two categories: yarn breaks before spinning and yarn breaks after spinning.
一 、 Analysis of yarn break before yarn forming
Refers to the end of the front roller before spinning the sliver, the main reasons are as follows:
1. Roving rupture: If the roving always breaks near the upper commutation, it may be due to 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 yarn guide rod; Caused by the roving details, the yarn ends are also increased.
2. Blockers have poor responsibilities, uncleanliness, flared flowers, empty rovings caused by poor touring, and rubber winding, aprons, and rollers caused by poor temperature and humidity in the workshop.
2. Analysis of broken ends after yarn formation
Refers to the breakage of the yarn from the front roller to the bobbin during twisting and winding. The reasons are mainly related to the following:
1, the effect of spindle speed
The increase in the spindle speed increases the yarn breakage after spinning. The reason is that after the spindle speed is increased, the centrifugal force generated by the traveler rotation increases, and the tension of the yarn is also increased, resulting in increased end breaks. When the spindle rotates at a constant speed, the distribution of doffing ends is as follows: the small yarn is the most, the large yarn is the least, and the medium yarn is the smallest. The ratio is 5: 2: 3.
The causes of yarn breakage After excluding air conditioning, poor mechanical operation and cleaning work, bobbin failure, and roving failure, etc., the use of a frequency converter to regulate the yarn breakage can reduce the yarn breakage by about 30 percentage points.
2, the influence of the wire loop weight
The weight of the traveler affects the amount of spinning tension. The traveller is too heavy, and the spinning tension is large, which increases the friction of the traveler on the yarn, and the yarn breakage increases; the traveler is too light, the spinning tension is small, and the balloon is too large, causing the yarn to hit the gauze plate, making Two adjacent spindles interfere with each other, resulting in increased head breaks. When selecting the traveller weight, consider the following factors:
1) Yarn variety
The thicker the yarn, the stronger the strength of the single yarn, the heavier the traveller's weight should be; when spinning chemical fiber, because the elasticity of the chemical fiber is better, it is easy to extend. Under the condition of the same weight of the traveler, the chemical fiber yarn and the traveler The friction coefficient is large and the balloon tension is small, so the balloon formation is large and the head is easy to break; therefore, the traveler weight should be 2-3 heavier than cotton when spinning chemical fiber, and 6-8 when weaving medium and long fiber.
2) Spindle speed
When the spindle speed is high, both the centrifugal force and the yarn tension of the yarn increase, so the weight of the traveller should be appropriately reduced to reduce the end break rate.
3) Influence of the use time of the ring
Under the same conditions, the number of travellers varies with the running time of the ring. When a new ring or a repaired ring gets on the train, the friction coefficient between the traveler and the ring is large, and the traveler must be mastered lightly; as the service life of the ring increases, the friction coefficient between the traveler and the ring decreases, and the wire The ring should be appropriately heavier; when the ring decays to the later stage, the runway wears out and deforms, and the hoes are heavy. There are many flying rings, and the number of broken ends will increase sharply. At this time, the traveller weight should be appropriately reduced. The service life of the ring is related to the variety of the yarn and the speed of the spindle. The smaller the yarn number, the longer the service life of the ring; as the spindle speed increases, the service life of the ring should be shortened. The service life of the flat steel ring is 12 months, and it is repaired once every 6 months; the service life of the tapered steel ring is 16 months; but with the small batch and diversification of the products, the number of times of changing the number of rings increases. The use cycle is shortened to: flat steel ring repair once every 4 months and scrapped in 8 months; tapered steel ring scrapped in 13 months; this way can reduce end breaks and ensure yarn quality.
4) The diameter of the ring and the length of the bobbin
When the diameter of the ring increases, the tension increases more when the small diameter is wound. If a heavier traveler is used, the balloon shape is flatter at the position where the large yarn is wound, and it is more likely to cause large yarn breaks. . Therefore, when the ring diameter increases, the weight of the traveler should be reduced; the increase in the tube height will increase the yarn tension and the maximum radius of the balloon, resulting in increased end breaks, so the traveler should be increased to solve it.
5) Ring model
In practice, it is found that the choice of the traveller weight also depends on the ring model. Under the same conditions, the use of tapered ring spinning is heavier than the traveller used for flat ring spinning, which can increase the package capacity, reduce the number of doffing, and reduce end breaks.
3.The influence of ring and traveller model selection and coordination on broken ends
The types of ring and travellers and their cooperation affect the size of the traveler's yarn channel and the balance of the traveler's operation, thus affecting the breakage of the yarn. It has been found in practice that flat steel ring types are suitable for a wide range of yarn numbers, but the number of broken ends has increased under the current situation of small batches, multiple varieties, and frequent number changes; while tapered ring can adapt to frequent number changes, but Suitable for spinning medium and thick yarns, especially when spinning fine yarns. In actual production, the type of ring is generally determined, and the type of traveller needs to be selected. When selecting the traveller model, factors such as suitable spinning variety, yarn thickness and spindle speed must be considered.
Four, reasonably determine the traveller service life
With the high-speed travel of the traveller, the wear reaches a certain level, the cooperation between the traveler and the ring is poor, the running is poor, the yarn tension fluctuates greatly, and the end breaks increase; therefore, the service life of the traveler must be reasonably determined . The traveller's service life is closely related to raw materials, yarn number, spindle speed and winding. Under normal circumstances, the thicker the yarn number, the higher the spindle speed, and the larger the package, the shorter the traveler cycle. It has been found in practice that when the cone-shaped steel ring is newly spun in the spinning and spinning of fine yarns, the traveler is replaced as soon as it is spun, otherwise it will cause a large area of broken ends.
5.The effect of twist on broken ends
Increase of yarn twist within a certain range increases the strength of the yarn, which is beneficial to reduce breakage. When the quality of raw cotton is poor, there are many short piles, the maturity is poor, and the fibers are fine, increasing the twist by about 2% can effectively reduce the breakage, but it will increase the yarn hairiness. Spinning derivative and traveller matching range.
