The Morphology of Ring Spinning Hairiness and Its Related Properties
The excessive hairiness of ring-spun yarn not only affects the appearance of the fabric, but also affects other properties of the fabric, and also reduces the production efficiency of the subsequent process, especially the loom. For yarns with more hairiness, the texture of the fabric is not clear, it is easy to pilling, there are many broken ends in the post-processing process, the production efficiency is low, and a large amount of falling objects affects the production rate. In addition, it will also cause uneven dyeing of the fabric, and defects such as hanging warp, jumping flowers, and weft bars.
1.1 Hairiness morphology of ring-spun yarns
From the cross-section of the yarn: there is hairiness the yarn. Viewed along the axial direction of the yarn, the hairiness protruding from the yarn body has different shapes and lengths.
Generally divided into three basic forms:
End hairiness: The ends of the fibers protrude from the surface of the yarn core, while the rest is wrapped by the yarn.
For end hairiness, it is divided into head hairiness, tail hairiness, and bidirectional hairiness according to the running direction of the yarn. Typically, end hairiness accounts for the majority of the hairiness of ring-spun yarns.
Loop hairiness: The ends of the fiber are wrapped in yarn and the middle arches out to form a loop or loop.
Floating hairiness: Loose fibers attached to the surface of the yarn.
1.2 The formation mechanism of ring spinning hairiness
According to the formation mechanism of hairiness, the hairiness of ring-spun yarn is divided into twisting hairiness and process hairiness.
1.2.1 Formation mechanism of twisting hairiness
The twisting hairiness is mainly formed by the whiskers during the twisting process. The whiskers output by the front roller are in a flat state, and the fibers are arranged parallel to the yarn axis. The twisting produced by the traveler’s rotation is transmitted to the front roller jaws so that the whiskers at the jaws rotate around the axis, the width of the whiskers gradually shrinks, and the two sides are gradually folded and rolled into the center of the yarn, forming a twisting triangle area. In the twisting triangle area, the width and cross-section of the whiskers change, gradually forming a nearly cylindrical shape from a flat ribbon.
Under the action of spinning tension, the fibers outside the center of the twisting triangle are subjected to centripetal pressure, so that the edge fibers are squeezed toward the center, and the center fibers are squeezed toward the edge. When the edge fiber is squeezed into the center, the centripetal pressure it receives tends to zero, and it is squeezed out by some edge fibers. When the head end of the fiber is extruded and released from the cohesion with other fibers because there is no tension and centripetal pressure, it is no longer pressed to the inside, so it remains on the surface of the yarn body to form hairiness.
Therefore, the twisted triangle plays a decisive role in the formation of yarn surface hairiness. Controlling the width of the output sliver of the front roller is the key factor to control the yarn twisting hairiness (small width, small fluctuation range of centripetal pressure on the fiber, which is beneficial to reduce hairiness), which has been verified by the compact spinning process. At the same time, the fiber structure state, short-staple content, fiber cohesion, and spinning tension in the sliver also have a crucial influence on the yarn hairiness.
1.2.2 The formation mechanism of process hairiness
Process hairiness is mainly the hairiness formed by the yarn scraping with the yarn channel during the spinning process. The cohesion of the fibers in the sliver and roving is poor. If the channel is not clean or is collided by an external force, it is easy to fluff to form hairiness; if the spun yarn channel is not clean, the original short hairiness will be scratched and stretched, and both ends have been buried in the yarn body. The middle section of the fiber is scraped and broken, and the fiber head-end originally in the yarn body is scraped out, so that the hairiness has further deteriorated or new hairiness is formed.
The main factor causing process hairiness is scratching, which is closely related to the finish of the yarn passage, yarn tension, static electricity, etc. In particular, the state of the spinning ring, traveler, and grooved drum has a great influence on the yarn hairiness. In addition, the surrounding arc length of the yarn on the grooved drum, winding speed, fiber oil content, environmental humidity, etc. also seriously affect feathers.
Main methods and measures to control hairiness
The control of hairiness is mainly to control the harmful hairiness, that is, the hairiness of 3mm and above.
2.1 Use of raw materials
(1) The greater the torsional and bending stiffness of the fiber, the more difficult it is to twist and bend the fiber. On the one hand, it is difficult to completely twist it into the yarn body; on the other hand, the fiber end that has been twisted into the yarn body may be The yarn body is ejected to increase the hairiness.
(2) The fiber length is long, the number of fibers per unit length of the yarn is reduced, and it is easier to be twisted and twisted to make the structure compact, which is conducive to reducing hairiness.
(3) The influence of the fineness of the fiber on the hairiness is that the coarse fiber has more hairiness and the fine fiber has less hairiness.
(4) Strictly control the proportion of back flowers, because the fiber is damaged by repeated blows, which will cause increased hairiness, and the use of back flowers should not exceed 5%.
(5) The cotton bales should be loosened in advance to balance the moisture absorption of the fibers, so as to control the hairiness. When selecting raw materials, it is necessary to control the fineness, length, and uniformity of the fibers to create good conditions for reducing hairiness. When spinning chemical fibers, attention should be paid to the oil content. A small content is easy to generate static electricity, causing the yarn to be hairy; a high content is easy to contaminate the channel, making the channel astringent and pulling the beard, which will increase hairiness, and will also cause poor carding and drafting. Product quality declines.
2.2 Requirements for reducing hairiness on equipment, technology, special equipment, operation, temperature, and humidity in each process
2.2.1 Blowing process
(1) The focus is on reducing fiber damage. The chemical fiber contains almost no impurities, which reduces the speed of each beater and enlarges the distance between the gripping points, which can effectively reduce yarn hairiness and neps.
(2) Unobstructed airflow, no choking or traffic jam. Unsmooth airflow can easily lead to choking, and choking is the main factor that causes cable neps, and these cables will produce a lot of short piles when carding, which will greatly increase hairiness. The smooth airflow can remove part of the short lint dust, which is beneficial to the subsequent processing.
(3) Due to the oily agent of chemical fiber, the cotton conveying pipeline is easy to produce oily dirt, which increases the resistance. It is necessary to remove the oily dirt regularly and keep it smooth. Especially, the Qinggang Federation should pay more attention.
(4) Maintain a certain humidity, so that the fiber to the carded cotton is in a dehumidified state, so as to facilitate the carding of the carded cotton and reduce short staples and neps. The moisture regains of viscose fiber sliver is controlled at about 10%, which is beneficial to subsequent processing and hairiness control.
2.2.2 Carding process
(1) In the process, it is necessary to reduce damage, multi-row short piles, and improve the straightness and parallelism of fibers. A lower licker-in rotation speed (less than 800r/min) can be adopted, a larger tin thorn ratio, and an appropriate increase in the licker-in-feeder spacing.
(2) On the equipment, it is important to ensure the mechanical state and the state of the card clothing. After the licker-in is decelerated, the inspection of the licker-in state should be strengthened. The back-toothed needles on the licker-in roller must be repaired in time, and the dust-removing suction port on the machine must maintain sufficient negative pressure.
(3) It is necessary to strengthen cleaning during operation to prevent short lint from being attached. Remove the dirt on the carding cluster horn and coiler in time, and require the carding blocker to thoroughly clean the cluster horn and coiler with a cotton-wrapped cloth dipped in alcohol before each shift. Keep the cylinder and doffer triangle area clean at all times, keep the dust removal suction port free from blockage and dust accumulation, and clean the bottom of large and small leaks thoroughly when parking.
2.2.3 Drawing process
(1) The focus of the drawing process is to optimize the drafting process and improve the straightness and parallelism of the fibers. The number of pre-merging and total drafting ratio of the head should be small rather than large, the drafting ratio of the rear area should be large but not small, and the spacing of the rear area should be large and not small; The draft ratio is smaller than that of the head unit, and the gap in the rear area should be large rather than small; the combined number of the three units is basically the same as the total draft ratio. Small, the front and rear areas should be heavily pressurized, have tight spacing, and have strong control.
(2) Keeping the drawing channel clean is an effective measure to reduce yarn defects and hairiness. When the barrel capacity is appropriate and the fixed-length is very long, it will cause a lot of friction and fluff on the upper sliver, which will seriously affect the quality. In addition, the poor quality of the can and serious static electricity will affect the surface finish of the sliver. If the height of the sliver in the back of the machine is not appropriate or the position of the barrel is not suitable, the sliver will be seriously touched and pulled, resulting in increased hairiness in the subsequent process.
2.2.4 Roving process
The key is to increase the tightness of the whiskers, improve the straightness and parallelism of the fibers, and improve the finish of the roving.
(1) It is better to control the total draft ratio of roving if it is too small, the rear area gap is too large to control, and the rear area draft ratio is too small to control.
(2) The twist coefficient of the roving is too large under the premise of satisfying the normal drafting of the spun yarn.
(3) The four-roller drafting form of the roving with a finishing area is beneficial to reduce hairiness.
(4) Appropriate collector openings should be used. Whether the collector is clean or not, the size and geometry of the opening have a great influence on the yarn hairiness. The opening of the collector should not be small, but it must be able to collect the whiskers well and make the roving tight. , smooth, and do not fluff due to friction between the sliver and the collector; choosing a suitable false twister is beneficial to reduce hairiness.
(5) Pay attention to the smoothness of the components and flyers in the drafting area. The upper and lower aprons and top rollers are cleaned and replaced periodically. The jaws formed by the upper pin and the upper apron are close to the lower pin and are flush with the lower pin to effectively control the fiber movement. Clean the flyer regularly to keep the flyer clean.
(6) Protective measures should be taken when storing and transporting rovings to prevent hair on the roving surface.
2.2.5 Spinning process
The spinning process is not only the point of generating twisting hairiness, but also the point of increasing process hairiness, and it is the key process to control hairiness.
184.108.40.206 Optimal spinning process
(1) The roving is light in weight, and the larger the draft ratio of the spun yarn, the more hairiness.
(2) Appropriately increase the twist of the roving under the premise of ensuring the smooth drafting of the spun yarn.
(3) Appropriately increase the roller spacing in the rear area of the spun yarn.
(4) Appropriately reduce the draft ratio in the rear area of the spun yarn.
(5) Select the appropriate spinning speed. The higher the spindle speed, the more hairiness grows.
(6) Appropriately increase the front impulse of the front rubber roller to the front roller, which is conducive to the transmission of twisting, and reduces the length and width of the twisting triangle, so as to achieve the effect of reducing hairiness.
220.127.116.11 Reasonable selection of textile equipment
(1) The upper pin is made of nylon upper pin with automatic tension adjustment.
(2) The selection of high-quality rubber rollers with low hardness and high elasticity is conducive to the control of fibers, thereby reducing hairiness.
(3) Use internal and external pattern rubber rings.
(4) Choose a traveler with good adaptability and a short maturity period to ensure a wide yarn channel and prevent the yarn channel from intersecting with the traveler’s runway to cause friction and cutting; The yarn separator, in the case of fewer broken ends, is more focused on mastering. Special attention should be paid to the cycle management of the traveler. When the traveler is severely worn, it is easy to generate channel crossing, and the yarn will be shaved at the worn gap to produce more hairiness.
(5) The surface hardness of the steel ring is required to be moderate, which can be adapted to the traveler; the inner and outer runways are smooth, and the friction coefficient is small and uniform; The parallelism of the top surface of the ring and the parallelism of the top surface and the bottom surface are better. The length of use of the ring also has a serious impact on hairiness, and the ring should not be used over time.
(6) The smaller the diameter of the yarn guide hook, the better the improvement of hairiness; the yarn guide hook should be smooth and wear-resistant. The use of front collectors for spun yarns is a very effective measure to reduce yarn hairiness.
18.104.22.168 Strengthen equipment management to ensure parts are in good condition and clean
If the yarn guide hook is worn and grooved, it is easy to scrape the yarn sliver, and the worn yarn guide hook should be replaced in time. The spun yarn guide hook, the steel ring, and the spindle are not concentric, causing the balloon to be out of alignment so that the yarn sliver rubs and collides with the yarn separator, and rubs against the top of the bobbin, which increases the hairiness exponentially. When the distance between the traveler cleaner and the steel ring is too large, the cleaning effect will be invalid, the hanging flowers of the traveler will increase, and the hanging flowers will grind the yarn. Keep the gauze plate clean, free from fouling, and prevent the air ring from colliding to increase hairiness. During production, the sliver channel must be kept clean, attention should be paid to equipment maintenance, and the equipment should be kept in good condition.
22.214.171.124 Strengthen operation management
Do a good job of cleaning all parts, make a tour in time, deal with broken ends, and strictly prevent sticking and blocking. Eliminate the floating hairiness formed by the attachment of accumulated flowers, short piles, and flying flowers. Strengthen the cleaning of the drafting part and the winding part. After each doffing, remove the spindle wrapping wire and the cleaning device.
126.96.36.199 Strengthen air conditioning management and strictly control workshop temperature and humidity
(1) Temperature and humidity affect the rigidity and conductivity of fibers. Relatively high humidity, some fibers are softer, easy to be twisted into the yarn body, and static electricity is easy to eliminate. On the premise that the rubber roller is not wound, increasing the relative humidity is conducive to eliminating static electricity and improving winding conditions, and is beneficial to reducing hairiness.
(2) The airflow in the workshop is turbulent, and the flying flowers and short piles increase, which will cause the increase of floating hairiness; the regional temperature and humidity differences are large, which is not conducive to hairiness control. When adjusting the air conditioner, do not cause disturbance of airflow, and minimize the difference in temperature and humidity in the area.
2.2.6 Winding process
Low speed and low tension are the keys. The winding process is the one with the largest increase in hairiness, which is generally increased by about three times, especially the increase in hairiness of 3mm and above, which is a geometric increase, which is mainly caused by the friction of various machine parts on the yarn. Due to the high wind speed and the different winding speeds at each point of the conical bobbin, the yarn will have a large slip during the winding process. As a result, the hairiness of the cop after winding will severely deteriorate. Therefore, the winding process is the serious generation point of hairiness in the yarn process, and it is also another key point to solve the hairiness problem.
Variety: Cationic polyester T/R 65/35 18.4tex, test conditions: YG172A yarn hairiness tester, test speed: 30m/min, test length: 60m, winding speed: 1300m/min
188.8.131.52 Do a good job in optimizing the process to control the growth of self-winding hairiness
(1) Optimizing the winding speed and winding tension, the winding tension and winding speed of the automatic winder have a great influence on hairiness. Winding speed and winding tension should be regarded as a whole during process adjustment. If only one process parameter is considered, it will be counterproductive. When combined with each other, the effect of high-speed operation with little increase in hairiness can be achieved.
Variety: Cationic polyester T/R 65/35 18.4tex, test conditions: YG172A yarn hairiness tester, test speed: 30m/min, test length: 60m.
(2) Optimize the winding density and optimize the winding tension. The winding density of the bobbin increases, the pressure of the bobbin contacting the tank decreases (the higher the P4 air pressure, the lower the contact pressure), and the growth rate of hairiness decrease.
184.108.40.206 Strengthening operation management
(1) Clean the yarn passages, trays, splicers, the inside of the bobbin holder, and the suction nozzles. During shift cleaning, it must be stopped at the same time to reduce the attachment of flying flowers.
(2) Do a good job in the transfer protection of the spun bobbins when they are transported to the winding to prevent the occurrence of the phenomenon of pressing the yarn in the yarn basket.
(3) The relative humidity is controlled at 70-73%. Properly increasing the humidity in the winding workshop is beneficial to reduce hairiness.
3.1 Maintenance and management of rubber rollers
Cleaning cycle, drawing frame once a week, roving once every half month, spun yarn, and traveler synchronization. Because the chemical fiber contains oily agents, the cots and aprons are easy to accumulate oily dirt, so they should be cleaned periodically with a cleaning agent with strong oil and dirt removal, and then dried before use. In view of the actual situation that chemical fibers are prone to static electricity, antistatic agents should be added to the coating after the rubber roller is made.
3.2 Adjust the management center according to seasonal conditions
The seasonal change of hairiness is very strong. In autumn, the static electricity generated by chemical fibers is not easy to eliminate, and the hairiness increases more. The air conditioner should increase the humidity to eliminate static electricity. In autumn, the flying flowers in the production process also increase greatly, and the hairiness grows rapidly, which shortens the cleaning cycle of the machine and reduces the feathers. When necessary, the production process appropriately reduces the speed, which is also helpful for controlling hairiness.
(1) The hairiness increases as the draft increases and the output speed increases and has an impact on the production efficiency and product quality of the subsequent process. Reducing hairiness, especially harmful hairiness of 3mm and above, is an important aspect of improving yarn quality.
(2) Solving the problem of hairiness is a systematic project, which should be carefully and effectively managed from the aspects of raw material characteristics, equipment management, operation management, process setting, equipment selection, temperature, and humidity adjustment, etc., so as to achieve reasonable process, complete equipment, and smooth channels, The machine has no sticking and clogging, the environment is clean, the logistics are orderly, continuous improvement, and the harmful hairiness is minimized.
(3) Hairiness is mainly formed in spun yarn and grows in the winding. Spinning is a key process for controlling hairiness. After the cop yarn is wound, the hairiness will seriously deteriorate. The winding process is the serious generation point of the hairiness in the yarn process, and it is also another key point to solve the hairiness problem.