End-breakage in air-end spinning is one of the common phenomena in air-end spinning production. End-breakage will have a certain impact on the output, quality and manufacturing rate of cotton yarn. The higher the end-breakage rate, the greater the harm. The increase in the end-break rate and the number of splices will inevitably cause thick knots and screw heads in the splices, thus affecting the quality of the yarn. At the same time, end-breaks are a concrete reflection of the level of management in the spinning production process. Therefore, minimizing the occurrence of broken ends during production is an important way to achieve high productivity, efficiency, and high quality.
Causes of end-breakage in open-end spinning
The main cause of end-breakage in air-jet spinning is caused by the strong weak loop in the yarn during the fiber cohesion and merging process. The rotor speed of the air-jet spinning machine is very high, the centrifugal force is large, and the negative pressure in the rotor is very high, so the fibers in the rotor experience large air resistance during the twisting process. When the fiber bundle is still in the sliver stage and is peeled off from the cohesion tank, its ability to resist flexing is very poor because it has less twist. If the strength of the fiber bundle is less than the tension formed by the friction resistance, air resistance and centrifugal force in the rotor, the yarn will break. Practice has proved that the majority of rotor yarn breakage occurs in the sliver section between the peeling point and the false twist end. Specifically, it can be divided into two types: decapitation before twisting and decapitation after twisting. The main reason for end breakage before twisting is that when the fibers are transported to the cohesion tank, the fiber arrangement is damaged by different forces during the cohesion and merging process, resulting in advanced or lagging movement. The focus is on the sliver. impurities, dust, dead cotton bundles, and unstable operation and negative pressure. End breakage after twisting is mainly caused by the large loss of twist and changes in the volume and twist of the yarn during the twist transfer process.
Control measures for end-break in air-end spinning
Air-end spinning Beheading is divided into: general beheading, repeated beheading, partial beheading, and large-area beheading.
01 Control measures for general head breakage
Causes of general head breakage The reason is very accidental and has little to do with the process, temperature and humidity, and is mostly caused by random factors. Specific emphasis is placed on control of operating equipment. Operational control measures: pay attention to the quality of local cleaning, yarn fly, broken sliver, failure to replace empty cans in time, sliver defects and other factors. Equipment control measures: Mainly caused by machine vibration and other accidental factors that cause weak links when fibers agglomerate and merge. When controlling, pay attention to the accidental factors, such as end breakage caused by accumulation of cotton rollers.
02 Control measures for repeated head breakage
Repeated head breakage is It refers to two or more consecutive breakages of the same single spindle. This decapitation has the most harmful effects. When controlling, focus on process reasons and equipment reasons. When repeated ends are broken in a large area, operational reasons, temperature and humidity factors, raw material factors, rotor cleaning effect, etc. should be considered.
1) Control measures for operating reasons
Catch regular defects in the cotton sliver in a timely manner. The internal cleaning effect of the spinning device must be good, and the carding cavity must be free of impurities and fine dust.
2) Equipment cause control measures
Focus on the timely maintenance of the cotton feeder board, cotton feeder roller, carding roller, fiber transport channel deformation, damage and sluggishness maintain.
3) Control measures for raw material factors
After repeated ends breakage occurs, when the accumulated dust in the spinning rotor continues to increase after cleaning, please pay attention Due to the impurities contained in raw cotton, adjust the mixing ratio of reused cotton.
4) Control measures for process reasons
Excessive winding tension can easily cause repeated breakage. The negative pressure of the spinning rotor remains stable, and the pressure of the rubber roller and the yarn take-up roller is unified. If it is too small or too large, it will cause repeated breakage. The rotor speed and rotor diameter must match, otherwise it will cause insufficient negative pressure and cause repeated ends breakage in a large area.
03 Control measures for partial breakage
Partial breakage is obvious For different varieties, comprehensive factors are considered; for some machines, the control of mechanical factors and process factors is emphasized. Raw material factors: The control of partial breakage of different varieties focuses on raw material factors and reasonable selection of processes. The adjustment of raw materials should be based on the number of yarns being spun. Control of operating reasons: Reasonably grasp the time when the spinning rotor accumulates impurities, and clean the air-jet spinning device according to different types. Partial machine end breakage focuses on process control. Pay attention to whether the negative pressure of yarn introduction and process exhaust pressure are reasonable, and whether the winding tension, rubber roller pressure, and spinning rotor speed meet the process requirements. During production, a reasonably designed rotor speed and yarn take-up speed should be selected based on the number of yarns being spun, cotton distribution, equipment operating status, and quality of accessories. The yarn number is fine, the cotton distribution is relatively good, and important mechanical parts such as the rotor, carding roller, and false twister are also in better working condition. At this time, the rotor speed can be selected higher, and the yarn introduction speed can also be higher. In terms of equipment, we pay attention to the maintenance cycle, mechanical condition and effect.
04 Control measures for large-area breakage
Large-area breakage Heading refers to the phenomenon of broken ends on some varieties and machines. The main reasons for this phenomenon are the process negative pressure, temperature and humidity, and the configuration of raw materials.
1) Temperature and humidity control measures
If the relative humidity is too high, the fiber will not be easy to open, impurities will be difficult to remove, and fiber clusters and fiber bundles will easily cause breakage. When the relative humidity is too low, the fiber will be fluffy and the fiber cohesion will be poor, which will easily cause strong weak rings during the twisting process and cause large-area breakages. Selection range: summer temperature 32 ℃ ~ 33 ℃, relative humidity 67��～70%; in winter, the temperature is 26℃～28℃, and the relative humidity is 63%～65%. At the same time, the temperature and humidity of pre-spinning are reasonably controlled to reduce the phenomenon of wrapping in production.
2) Negative pressure process control measures
Negative pressure is one of the important factors affecting end breakage, and it is also an important factor affecting yarn quality. The impact of process negative pressure on large-area breakages is mainly related to the operating status of the machine exhaust and dust removal units. In actual production, the miscellaneous box must be cleaned in time to prevent low wind and poor exhaust.
3) Raw material factor control measures
While other conditions remain unchanged, increasing the cotton level can significantly reduce yarn breakage. occur.
4) Control measures for process reasons
The cotton picking machine should reduce the picking depth as much as possible to ensure uniform mixing; card the cotton to reduce fiber damage and control the growth of short staples. In principle, the effect of carding and impurity removal is taken into account, the waste is unified, and the spacing is unified to reduce table differences; the drawing process prevents the coiling disc from scratching the sliver.
5) Control measures for operating reasons
Intensify cleaning efforts to reduce the attachment of fly flakes; increase efforts to capture defects in drawing slivers . The operator should perform cleaning work according to the prescribed time and requirements to keep the air supply ports and channels of the spinning machine unobstructed. When changing the sliver barrel, do not press the sliver too much to prevent the sliver from sticking. On the other hand, tampons should not be left for too long.
6) Equipment cause control measures
The parts that come into contact with cotton fibers must be smooth and clean, and no hanging phenomena may occur. It is necessary to ensure the sharpness of the tooth ring of the combing roller, and there should be no undercutting. The spinning rotors, carding rollers, false twisters, and cotton transport channels are repaired and replaced periodically. Refuel and replace the spinning rotor and opening roller regularly. To sum up, end-breakage in air-end spinning is a comprehensive reflection of various factors such as technology, equipment, operations, raw materials, temperature and humidity in the air-end spinning process. When reducing end-breakage, it will affect general end-breaks, repeated end-breaks, partial end-breaks, etc. Different control measures are adopted for large-area breakage, and strengthening management can effectively reduce breakage. </p
