How to reduce weaving defects on air-jet looms during fabric production?

Causes of shrinkage

Improper release time of the yarn blocking needle, inaccurate opening and closing time of the nozzle solenoid valve, and too high or too low nozzle pressure will cause the weft yarn to fly forward and backward, and the weft yarn cannot fly straight through the shed. Causes weft shrinkage; the closing time of the right side hem is too late, and the weft yarn is not clamped in time, and the weft yarn retracts; the weft insertion time is too early, and the opening height is not enough, causing the weft shrinkage to increase; conversely, the weft insertion time is too late, and the weft yarn reaches the angle late, resulting in shedding The height is relatively small, and the head end of the weft yarn collides with the warp yarn, causing the weft yarn to be blocked and cause shrinkage. In addition, improper injection time will also cause shrinkage.

The temperature and humidity in the workshop are low, the elasticity between fibers is relatively enhanced, and the friction is reduced, which promotes the increase in reverse twisting torque and causes weft shrinkage.

Solution

If the compressed air is not pure, you can install a double-layer filter at the air inlet. The filter should be cleaned and maintained regularly. If there is moisture on the cloth surface, you should check whether the drying system is operating normally. During daily maintenance, it is necessary to Carefully clean the solenoid valve with an ultrasonic vibrator.

At the beginning of machine installation, the heald frame and shedding stroke must be adjusted according to the process requirements, and when adjusting the heald frame, attention should be paid to the consistency of the processes on both sides of the heald frame. On air-jet looms with pedal openings, the steel wire rope is a flexible carrier for lifting the healds. It can be easily stretched in a leisure state. Generally, the height of the heald frame is checked once a week. This can not only eliminate the impact of the stretched wire rope, but also troubleshoot the operation of the repair machine. The weft shrinkage caused by uneven heald frames or incorrect heights caused by workers and machine workers frequently working on machines, repairing broken machines, and improper adjustments.

The temperature and humidity in the workshop are unstable, which changes the performance of the warp and weft yarns and affects the clarity of the shed. It must be adjusted in time. Generally, the temperature of the air-jet loom is 22℃~26℃, and the relative humidity is 72%~78 %between.

Cause of double latitude

The rebound spring of the yarn blocking needle of the weft storage device fails, causing the opening and falling angle of the yarn blocking needle to be inaccurate and unstable. The weft yarn easily comes out of the yarn blocking needle; the yarn blocking needle is worn and does not hit the center of the yarn blocking needle. On the yarn drum, the weft yarn slips out from the yarn storage drum; the distance between the weft feeder and the pressurized nozzle is too close, and the yarn loop swings violently when the weft yarn retreats from the weft feeder, and is easily thrown out from the yarn blocking needle; Problems such as the failure of the pressure nozzle to align with the center of the weft feeder, irregular yarn circles, and incorrect angle to the main nozzle will cause double weft defects.

Solution

Replace the yarn blocking needle spring of the weft feeder; replace the yarn blocking needle; adjust the distance from the weft feeder to the booster nozzle or install a balloon breaker; adjust the height and angle of the weft feeder to the appropriate Position; replace and repair the left scissors, press the forward button to check, there should be no weft yarn nap when cutting yarn. The reason for the common weft yarn twist coefficient is relatively small, and the strength of the spinning yarn is low. The twist is increased by 5% to 9%, which can effectively reduce the weft yarn breakage. The use of rotor spinning can effectively reduce the details of the spinning yarn; strengthen the control Maintenance of the weft detection device, timely cleaning of the flying particles produced by the weft detection device; reducing the normal pressure of the main nozzle, and controlling the nozzle pressure to a small value when the weft yarn can pass smoothly; strengthening technical training, improving the work responsibility of the operator, and strictly executing the operation Law.

Causes of dense roads

Cloth fell displacement. When the loom is stopped, both the cloth surface and the warp yarns are subjected to a large tension on the machine. At this time, the cloth fell and the reed are separated. Due to the creep and relaxation of the warp, the cloth fell deviates from its corresponding position during normal weaving. The size of the deviation changes with the length of the stop time. When restarting the machine, if the position of the fabric mouth is not handled properly, a dense road will be formed on the cloth surface. Other idle machines have too many idling times, insufficient tension in the stab ring and winding mechanism, which will also cause displacement of the fabric mouth.

Device status is bad. With the long-term continuous operation of the loom, some mechanical parts and components gradually wear out or even fail, resulting in a decrease in leisure accuracy, or the beating force of the weft after starting is insufficient, and the weft cannot be fully driven into the fabric felling; or the yarn breaks. When the brake is not applied in time, there is a gap in the weft yarn and a failure in the warp let-off and take-up.

Solution

Reduce the frequency of shutdowns. Stopping and shutting down vehicles is the main cause of dense roads. Improving the quality of semi-finished products to reduce vehicle shutdowns is an effective measure to reduce defects on dense roads. During production, lathes should promptlyManage the stop to prevent the formation of dense weft defects; or configure an automatic weft break processing device to shorten the weft stop time and remove dense wefts.

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