1 Analysis of the causes of yarn defects
1.1 Thick and thin weft yarn defects
(1) When the joint is thick and thick, the lap is too long or too short or the wrapping ring is too tight or too loose to form a thick and thin weft.
(2) The parts where the cotton sliver and the yarn sliver pass through (such as the concentrator, the bell mouth, the flyer channel, etc.) are not smooth, and the sliver is brought into the yarn sliver.
(3) During the transportation of the sliver, the sliver is touched or the barrel mouth of the sliver is damaged to form an uneven thickness of the weft.
(4) When the roving is broken, the whisker sliver floats into the adjacent sliver, and the double yarn is fed to form a coarse weft.
(5) When processing and rough winding the rubber roller and roller, the thin strips are not pulled clean
(6) The self-stopping device for the broken ends of the drawing frame fails to stop, resulting in a fine weft.
(7) After the roving frame, the sliver hangs on the sliver and loses the batch. The duty lathe does not find it in time, and feeds the roving to form a fine weft.
(8) Improper operation of the roving frame when changing teeth, movement of the rubber roller when unloading pressure, or transmission inertia when switching the car on and off, etc., resulting in fine weft.
1.2 Slub yarn
(1) Do not follow the operation method, so that the velvet board flowers in the combing, bundling and roughing processes, the short piles at the bell mouth and various accumulated flowers are brought in, the flying flowers are moved, etc., to form the velvet board slub yarn.
(2) The position of the drawing pressure bar is improper, and the meshing of the coarse transmission gear is too loose, and the keyway or shaft hole is worn out and loose to produce intermittent cotton nets, forming slub yarns.
(3) The surface of the ganging rubber roller is rough, the roller groove is not clean and has burrs, and the passage of each part of the yarn is not clean, and there are sticking and blocking phenomena, forming slub yarn.
(4) The coarse cleaning device fails, the loop does not rotate, the suction force of the suction device is too small, the velvet plate under the roving does not contact the roller or is not cleaned, causing the velvet board flower to attach and form the velvet board yarn.
(5) The bottom of the car belly is not cleaned in time after carding, which causes the car belly flower to enter the sliver and form slub yarn.
(6) In the process of flat wiping, poor work or careless cleaning will form oily slub yarn.
1.3 Uneven yarn defect
Unevenness Yarn defects are divided into regular unevenness and irregular unevenness. Regular unevenness is generally a sudden yarn defect, mainly due to poor mechanical parts; irregular unevenness is mainly caused by the drafting force being greater than the control force, improper process parameters, fluctuation of raw materials, and sudden changes in temperature and humidity in the workshop. The main reasons are:
(1) The draw frame concentrator is damaged, the opening is too small and not smooth, the width of the guide frame is too large, and the pressure of the rubber roller fails.
(2) The rubber roller bearing core is short of oil, and the suction force of the drawing air suction device is too large.
(3) The distance between the rough and thick rollers is improper.
(4) The transmission gears are poorly meshed, and the gears are non-standard parts.
(5) There is a big difference in the gap between the swing pin jaws of the roving frame, slippage or loose positioning screws, deviation of the lower rubber ring, defects, etc.
(6) The roving fails to be pressurized, and there are velvet flowers in the bundle or the whiskers are not in the central collector.
(7) The roving sliver frame is not running well, and the sliver is stretched unexpectedly.
2 Solutions
In view of these three types of defects that are often found in pure cotton carded varieties, we have taken corresponding measures from the aspects of operation management and equipment through observation and analysis to effectively solve such problems.
2.1 Operation management
(1) The on-duty workers will make frequent tours, strengthen the work of picking out miscellaneous defects, and enhance work enthusiasm and sense of responsibility.
(2) Put an end to the barbaric operations such as "fan, blow, pat, hit" by the turner on duty, and avoid flying flowers from moving.
(3) Strengthen the cleaning work of carding, and remove the rear belly and leaking bottom in time.
(4) The accumulated flowers on the roving aprons should be removed in time.
(5) Regularly check whether there are white flowers in the flowers of the drawing bellows, and repair in time if white flowers are inhaled.
(6) Strengthen the inspection of the self-stopping device for broken ends by the quality inspectors and duty workers. If they find that they are not working or do not stop, they must be repaired before driving.
(7) After the manual pressurization of the drawing frame value car, the sliver must be rubbed to check whether the evenness is normal.
(8) Comb, merge, and rough supply to the table, solve problems in time, and shorten the transportation route of full barrels as much as possible. It must be handled gently to avoid touching the wool.
(9) Carry out technical training activities before and after the shift and on rest days to improve the operation level and ensure the quality of joints and tie-ups.
(10) Sugar-removing raw cotton with a sugar content of more than 3%.
(11) Strengthen the control of temperature and humidity in the workshop, record the work of air conditioners, and adjust them in time.
(12) Replace the damaged and rotten sliver barrels in time; the springs in the sliver barrels are appropriately soft and hard, and the unqualified springs should be replaced in time.
2.2 Equipment aspects
(1) The quality and quantity of the flat wiping car are guaranteed, so that each yarn passage is smooth and clean, the loops rotate flexibly, and the cleaning device is in good condition.
(2) The maintenance workers regularly check the rollers, rubber rollers and transmission gears to ensure that they are in good condition and refuel in time. Timely wipe the surface of the roller groove with cotton wax, dirt, rust spots, etc. with a wiping cloth dipped in gasoline or alcohol to avoid roller entanglement.
(3) Optimize the process and select the process to get on the car. For example, the roller gap in the middle and rear area of the FA311 draw frame is appropriately enlarged, and the speed of the car is appropriately slowed down under the condition of ensuring the supply.
(4) Ensure that the parallel and roughing gear guide racks are in good operation, do a good job in the maintenance of the rubber rollers, rollers and gears of the paralleling and roughing machine, check the integrity of the equipment from time to time, and deal with problems in time.
Through the above measures, the number of yarn defects of 100,000 meters has gradually decreased, which shows that certain results have been achieved. When dealing with specific situations, it is necessary to carry out specific scientific analysis, implement the responsibility system layer by layer, do a good job in basic work, focus on the small, take the word "strict" first, fully mobilize employees, rely on employees, focus on prevention, prescribe the right medicine, and check at every level.
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