Roving frame plays a key role in connecting the past and future in the textile industry. How to make good use of roving equipment? We have summarized the following four practical experiences to share with you.
01 Roving frame selection, installation quality and equipment maintenance quality control
(1) Equipment selection: There are currently many roving frame manufacturers on the market, with nearly a dozen different models at home and abroad. The equipment produced by each manufacturer has its advantages and disadvantages. You can choose and buy it based on the manufacturer’s product variety, product grade, and financial status. Find the device model that suits you. The purpose of selection must be to meet production needs without wasting corporate funds, and to ensure that the equipment is always in good operation.
(2) Equipment installation: After selection, installation work is an important link to ensure product quality and is also the most basic work. Those who are able to install it themselves and have poor conditions are the best. Ask the equipment manufacturer or technicians with better skills to install and debug it, and be sure to find professionals to strictly control it, so that in future production, you can easily carry out various production tasks.
(3) Maintenance quality: Carrying out daily maintenance well is the most basic daily management. The key point is to be thorough, comprehensive, and leave no “dead corners”, which means real maintenance. in place.
(4) Purpose of maintenance: to ensure that the equipment is always in good condition.
02 Control of roving tension
(1) To make the roving smoothly wound onto the roving tube, the The winding speed must be slightly greater than the speed of the front roller outputting the yarn, so tension and tension draft are generated on the yarn between the front roller and the thick tube. This is the key to roving production. It not only affects whether the roving life is easy to make, but also affects the quality of the roving. Moreover, it directly affects the quality of yarn.
(2) According to the requirements of spinning quality, the maximum elongation is generally not more than 3%. The yarn room of the same machine size, the front and rear rows and the same type of machine and The elongation difference between machines should be controlled below 1.5%.
(3) The yarn section from the front roller to the top of the spindle flyer has a small twist due to the twisting phenomenon, and the distance is long. At the same time, when the spindle flyer rotates at high speed, there is Jitter phenomenon is most likely to cause unexpected elongation. According to experience, it should be adjusted to: when the small yarn is wound from the starting point to the lower part of the bobbin for the second layer, the yarn can shake slightly, but it is better not to cause waves. If the upper yarn is tight, it means that the winding speed is too fast and the elongation is too large. The starting position of the cone pulley belt should be moved upward to the big end of the cone pulley. The non-cone pulley should be controlled and adjusted from the inverter. The ultimate goal is to achieve consistent Slightly jittery. If the yarn gradually becomes tight during the spinning process, it means that the conical pulley belt moves too little each time, and the number of tension teeth should be reduced. Otherwise, the number of tension teeth should be increased.
(4) Factors that affect changes in roving tension include: changes in roving basis weight, front roller speed, twist, raw cotton quality, temperature, humidity, and mechanical state. Therefore, a roving quality ledger should be established during production, which is completely necessary to ensure production. The size, difference and unevenness of the roving tension will affect the evenness and weight unevenness of the roving. It is an important indicator that affects the quality of the roving, so it must be strictly controlled. Because there are much less fiber slivers in the cross-section of the roving and the twist is lower than that of the spun yarn, it is easy to produce unexpected elongation after being subjected to greater tension, worsening the evenness of the roving and increasing breakage.
(5) When the tension difference is large, the roving weight unevenness increases significantly, and should generally be controlled within 1.0%. When the roving tension is small, the roving becomes loose and difficult to store, transport and unwind, which not only affects the quality of the roving itself, but also increases the uneven weight and weight deviation of the spun yarn. For example, when spinning pure cotton roving on a roving frame with a poor false twist effect, the quality index of the front row is worse than that of the rear row. Under the same spinning conditions, different tensions in the front and rear rows will cause quality differences. Of course, under conditions where the false twist effect is good, the spinning tension of the rear row may be greater than that of the front row. Therefore, in terms of roving quality management, in addition to paying attention to the influence of the drafting part on quality, we should also grasp the changes in roving tension.
03 Process control of roving frame
The process parameters of roving frame mainly include: basis weight, spindle speed, draft, roller Grip distance and apron jaw spacing, roller pressure, twist coefficient, winding density, collector and trumpet diameter, pressure palm winding number.
(1) The ration of roving is determined based on the drafting capacity of the spinning machine, the number of spinning yarns, and the quality of the product, mainly based on the number of spinning yarns. The heavier the spun roving, the thicker the yarn, but if it is too heavy, the fine yarn will increase with the draft multiple, which will have an impact on the yarn evenness. Nowadays, the basis weight is increased to 10g/10m, and the spun yarn is changed to a “V” shape draft. The finished yarn is also good and deserves to be promoted.
In short, the total draft ratio of the roving frame is determined not only based on the number of spinning yarns and the ration of cooked strips, but also the drafting form of the roving frame. With the development of high draft ratio, the roving can be configured with a lower draft ratio, which is beneficial to the quality. When using double short apron drafting roving, the drafting ratio can be slightly higher than the three up and four down curve drafting, generally 5 times to 12 times.
(2) The drafting distribution of the roving frame is determined according to the drafting mode and the total drafting multiple. When the drafting capacity of the main drafting zone is large, the main drafting The drafting multiple of the area should be large. Double short apron drafting is a type of drafting area with greater capacity. Practice has proved that when the feeding sliver ration and roving ration remain unchanged, the greater the rear drafting multiple. , the roving is dryTherefore, when the process conditions in the main drafting area are good, the rear drafting multiple should be controlled on the small side.
(3) Post-draft ratio: Post-draft ratio has a great influence on the evenness of the roving. In general, the double rubber ring drafting device has strong friction in the rubber ring part and an elastic jaw, which can stabilize the drafting force and move the fiber speed change point forward, which is both concentrated and stable. Therefore, the general post-draft ratio is configured between 1.08 times and 1.4 times. In production practice, we use 1.1 times the post-draft on the A454, FA468E, FA458A, and FA421 roving frames to achieve optimal roving evenness. Of course, the dry quality is also related to the pressure of the apron roller. When determining the rear draft ratio, you should first understand the slippage rate of the lower apron to the center roller, and try to reduce the slippage rate of the upper and lower apron rings. In addition, when the basis weight of the roving is too heavy, in order to prevent the delamination of the whiskers, a larger post-draft ratio can be used. When spinning knitting yarn, in order to prevent the details of long segments of fine yarn, a smaller total draft ratio should be used. In this case, the draft ratio of the rear area should also be controlled on the small side. For the three-up-four-down drafting mode, due to the anti-enveloping arc on the third roller in the rear area, when the cooked strip weight is light, the drafting multiple in the rear area should also be controlled on the small side, generally 1.17 times to 1.36 times.
(4) When using a large package and high roving frame, the spindle speed can reach 1000r/min~1500r/min. The roving weight should not be too light, otherwise it will increase unexpected drafting. This leads to an increase in breakage of coarse and fine yarns, making life difficult.
(5) Twist coefficient: When the fiber is long, uniform and fine, the twist number should be small, otherwise it should be large. Only when the roving has twist can it withstand winding. and the tension during unwinding, and is beneficial to the control of fibers by drafting in the rear area of the spun yarn. But if the twist coefficient is too large, not only will the strength of the rovings be uneven, but the spun yarns will also cause rubber roller slippage, hard ends, and increased breakages; conversely, if the twist coefficient is too small, accidental drafting will occur, and breakages will increase, making the product uneven.
(6) Roller spacing and pressure: The roller spacing should be determined according to the fiber length. If it is too small, it will damage the fiber and even produce hard ends. If it is too large, the fiber movement will be irregular and deteriorate. CV value quality index, the purpose of roller pressurization is to ensure that the roller jaws have sufficient holding force and prevent the yarn from slipping and excessive delamination under the roller jaws. During the drafting process, whether the roller jaws can effectively control the fiber directly affects the evenness and weight unevenness and the occurrence of roving defects. On a roving frame pressurized by a spring cradle, the upper pin and The jaws are controlled by the pin apron under the ladder, and the original spacing of the jaws is determined according to the quantitative change of the roving. When the quantitative quantity is above 5g/10m, the original spacing of 4.5mm, 5mm, 5.5mm, and 6mm should be used. When selecting, it should be equipped with a smaller jaw under sufficient spring pressure conditions, which is beneficial to the uniformity of the product, but it should be Calibrate the spring pressure regularly. If the pressure is inconsistent, it will cause large differences between ingots. If the jaw is too small, it is easy to spit out hard heads.
(7) The front and middle area collectors of the roving frame also function as an additional friction force boundary, and their caliber size is: the front area should be compatible with the roving quantitative , the middle area should be consistent with the quantity of cooked strips.
(8) The spindle is vertical and has no swing, and is controlled within 0.03mm. The bending is too large, resulting in increased breakage and irregular thickness.
(9) The spindle flyer must be dynamically and statically balanced, not skewed, the passage is smooth, and the pressing palm should be appropriately tight. If the yarn is too tight, it will be hairy, and if it is too loose, it will easily fall off. If the arm opening is large, it will collide with each other; if the arm opening is small, it will be frosted. If the curvature of the pressing palm is unqualified, the roving winding will be tight and the ration will be uneven, and even defective products will be produced, resulting in increased ends breakage. In order to maintain the normal operation of the machine and reduce wear and tear, it must be calibrated and wiped regularly.
04 The impact of drafting force on process quality
The drafting force itself is not a process problem. However, the drafting force must be considered when designing the drafting process parameters. It is related to the following factors:
(1) The relationship between drafting force and drafting multiple: When the drafting multiple is equal to 1, there is no relative movement between fibers, and the drafting force is equal to 0. As the drafting multiple increases, the drafting force increases sharply. Later, as the fibers begin to slide, the drafting force increases slowly. When the drafting multiple approaches the maximum, the drafting force is the maximum, and the maximum drafting force will increase with the feed. It changes with the number, roller spacing, dense arrangement of yarn strips, fiber straightness, etc.
(2) The relationship between the drafting force and the twist of the feed roving. The higher the twist of the fed roving, the greater the drafting force. When the drafting multiple is low, the rovings with different twists will The drafting forces are relatively close. This is because when the drafting multiple is large, the twists of the roving are disbanded and the influence of twist is not significant.
(3) The relationship between drafting force and roller spacing: When the roller spacing is very large, reducing it will have almost no effect. If it continues to decrease, the drafting force will gradually increase. , after the gauge is small to a certain extent, the drafting force increases sharply. This is because the tail ends of some fibers extend into the rear jaws, increasing the traction force.
(4) The relationship between drafting force and sliver density: If the sliver density is increased in the drafting zone, the drafting force will increase accordingly. When the yarn passes through the collector, the friction between fibers also increases, so the smaller the opening of the collector, the greater the drafting force.
(5) The relationship between drafting force and fiber fineness, length and straightness: When the fiber is thin and long, the drafting force will be due to the large friction resistance between fibers. increase. If the fibers are in a state of curling and intertwining, the friction force will be greater and the drafting force will be greater. On the contrary, the more straight and parallel the fibers are, the smaller the drafting force will be.
(6) Relationship with the relative humidity of the workshop. For every 10% increase in relative humidity within the range of 35% to 75%, the drafting force increases by 8%. When the relative humidity is extremely high, hard heads will appear.
05 Conclusion
The above are some experiences of using roving frame. Correct use of roving frame is It is a key link in textile engineering. Only by deeply understanding the connotations can we make better use of the roving frame and spin high-grade products.
The �� force is large and the drafting force is also large. On the contrary, the more straight and parallel the fibers are, the smaller the drafting force will be.
(6) Relationship with the relative humidity of the workshop. For every 10% increase in relative humidity within the range of 35% to 75%, the drafting force increases by 8%. When the relative humidity is extremely high, hard heads will appear.
05 Conclusion
The above are some experiences of using roving frame. Correct use of roving frame is It is a key link in textile engineering. Only by deeply understanding the connotations can we make better use of the roving frame and spin high-grade products. </p
