There are many yarn defects in pure cotton yarn, which not only affects the cotton yarn rating, but also affects the appearance of the cloth, the intrinsic quality and use value of the cotton cloth. This not only brings disadvantages to the yarn mill, but also brings disadvantages to the weaving production and operation, directly affecting the manufacturer. vital interests. Based on the production practice of our company’s carded cotton yarn, we now summarize three common causes and solutions of yarn defects in carded roving.
1 Analysis of causes of yarn defects
1.1 Thick and thin weft defects
(1) When thickening joints, the lap is too long or too short or the wrapping is too tight or too loose, resulting in thick and thin wefts.
(2) The parts that the cotton sliver and yarn sliver pass through (such as the bundler, the bell mouth, the flyer channel, etc.) are not smooth, causing hanging flowers and bringing the yarn sliver into it.
(3) During the transportation of the sliver, the sliver is damaged or the mouth of the sliver barrel is damaged, resulting in uneven thickness and weft.
(4) When the roving is broken, the whiskers float into the adjacent yarn strips and the double yarns are fed to form a thick weft.
(5) When handling and roughly winding rubber rollers and rollers, the thin strips are not pulled clean
(6) The automatic stop device for draw wire breakage fails and a few wires continue to stop, resulting in thin wefts.
(7) The sliver behind the roving frame is stuck with wool and the batch is dropped. The lathe on duty did not find it in time and fed the roving to form a fine weft.
(8) Improper operation when changing the teeth of the roving frame, the movement of the rubber roller when unloading and applying pressure, or the transmission inertia when turning on and off the machine, etc., resulting in thin wefts.
1.2 Slub yarn
(1) Failure to follow the operation method will cause the pile board flowers in the carding, combining and roughing processes, the short velvet at the bell mouth and various accumulated flowers to be brought in, fly and move, etc. to form the pile board slub yarn.
(2) The drawing pressure rod is in an improper position, and the coarse transmission gear meshing is too loose, and the keyway or shaft hole is worn out and loose, resulting in intermittent cotton webs and slub yarns.
(3) The surface of the thickened rubber roller is rough, the roller groove is not smooth and has burrs, and the yarn passages in each part are not smooth and have sticking and blocking phenomena, forming slub yarn.
(4) The coarse cleaning device fails, the pile loops do not rotate, the suction force of the suction device is too small, the pile plate under the roving does not contact the roller, or it is not cleaned, causing pile flowers to attach and form pile yarn.
(5) After carding, the bottom of the car belly is not cleaned in time, causing the car belly flowers to enter the card sliver and form slub yarn.
(6) During the flat wiping process, oily slub yarn is formed due to poor work or careless cleaning work.
1.3 Uneven yarn defects
Uneven yarn defects are divided into regular uneven evenness and irregular uneven evenness. Regular uneven evenness is generally caused by sudden yarn defects, mainly due to poor mechanical parts; irregular uneven evenness is mainly caused by drafting force greater than control force, improper process parameters, raw material fluctuations, and sudden changes in workshop temperature and humidity. The main reasons are:
(1) The drawing bundler is damaged, the opening is too small and not smooth, the width of the guide frame is too large, and the rubber roller pressure 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 spacing between thickening rollers is improper.
(4) Each transmission gear has poor meshing and the gears are non-standard parts.
(5) The gap between the swing pin jaws of the roving frame is greatly different, the positioning screw is slipping or the positioning screw is loose, and the lower rubber ring is deflected or damaged, etc.
(6) The roving pressurization fails, there are pile strips in the bundler or the whiskers are not in the central zone bundler.
(7) The roving guide frame is not functioning properly, rotating and stopping, causing unexpected elongation of the sliver.
2 solutions
In view of these three types of defects that often occur in pure cotton carded varieties, through observation and analysis, we have taken corresponding measures from the aspects of operation management and equipment to effectively solve such problems.
2.1 Operation management
(1) On-duty lathe workers patrol frequently, strengthen the work of sorting and catching defects, and enhance work enthusiasm and sense of responsibility.
(2) Put an end to barbaric operations such as “fanning, blowing, slapping, and beating” by on-duty workers to avoid flying flowers and moving.
(3) Strengthen the carding and cleaning work, and clean the rear belly and leakage bottom in time.
(4) Remove the accumulation of roving apron in time.
(5) Regularly check whether there are white flowers in the draw frame bellows, and repair them promptly if any white flowers are found.
(6) Strengthen the inspection of the auto-stop device by quality inspectors and on-duty workers. If it is found that it is not working or does not stop, it must be repaired before driving.
(7) After the draw frame operator manually applies pressure, he must rub the sliver to check whether the sliver is normal.
(8) Combing, combining and roughing are supplied to the station, problems are solved in time, and the transportation route of the full barrel of sliver is shortened as much as possible. The sliver must be handled with care and avoid touching the sliver.
(9) Carry out technical training activities before and after work and on rest days to improve operational levels and ensure the quality of joints and joints.
(10) Remove sugar from raw cotton with a sugar content exceeding 3%.
(11) Strengthen workshop temperature and humidity control, record air conditioning work, and make timely adjustments.
(12) Replace damaged or rotten sliver barrels in a timely manner; the springs in the sliver barrels should be soft and hard, and replace unqualified springs in a timely manner.
2.2 Equipment
(1) The flat wiper ensures both quality and quantity, making each yarn passage smooth and clean, the pile loops rotating flexibly, and the cleaning device in good condition.
(2) Maintenance workers regularly check rollers, rubber rollers, and transmission gears to ensure they are in good condition and refuel in time. Timely use a wiping cloth dipped in gasoline or alcohol to clean the cotton wax, dirt, rust spots, etc. on the surface of the roller groove to prevent the roller from getting entangled.
(3) Optimize the process, select the process and put it on the car,�Appropriately enlarge the distance between the rollers in the middle and rear areas of the FA311 draw frame, and slow down the vehicle speed appropriately while ensuring supply.
(4) Ensure that the paralleling and coarsening transmission gear rack is in good operating condition, do a good job in maintenance of the rubber rollers, rollers, and gears of the paralleling and coarsening machine, check the integrity of the equipment from time to time, and deal with any problems found in a timely manner.
Through the above measures, the number of yarn defects in 100,000 meters of yarn has gradually shown a decreasing trend, which shows that certain results have been achieved. When dealing with specific situations, it is necessary to conduct detailed and scientific analysis, implement the responsibility system at all levels, do basic work well, focus on small things, put the word “strict” first, fully mobilize employees, rely on employees, focus on prevention, prescribe the right medicine, and check at all levels.
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