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Cause Analysis And Treatment Of Weft Stop In Air-jet Loom
Aug 15, 2017

  Cause analysis and treatment of weft stop in Air-jet loom

  I. Gas ROAD

  1.1 air filter

  Because the compressed air contains a certain amount of dust and impurities, the work must be blocked after the filter, not timely cleaning will cause the main spray and auxiliary spray pressure drop, valve spool fouling, valve core action is not sensitive, thus directly affect the weft effect, resulting in weft stop. Therefore, Air-jet loom filter filters to regular and timely cleaning, plugging more serious to timely replacement.

  1.2 Main Nozzle

  The main function of main jet is to overcome the resistance of weft insertion. Too little pressure will affect the arrival time of weft, the same pressure too much, in the main jet flow when the impact is too large and easy to blow off weft caused weft stop. Moreover, when the main jet pressure is large, the fluctuation of the weft head in the duct increases, which will increase the chance of weft stop. Air-jet loom General pressure control in 0. 3MPa or so, to the weft can accurately arrive as a reference standard.

  Variety CJ14.5/14.5 523.5/393.5 tabby. Auxiliary spray pressure 0.45MPa, to set to 90 °. The main jet flow relative to the electromagnetic needle, open too early or close too late can cause weft stop. Generally the earliest in the electromagnetic needle opened 10° left and right. At the latest 40 ° close before the electromagnetic needle close, open the degree of 60°~80°. The main spray breeze is too big, easy to make the weft twist, Air-jet loom the fiber slipped off, the strength drops, in the weft insertion process blowing off weft. The breeze is too small the weft may escape from the main nozzle, sometimes the weft is cut back by scissors, the head end curl and affect the next pitch. When parking in front of the main nozzle gently stir the weft, slightly feel a little tension can be, the pressure is generally 0.08MPa or so.

  1.3 Auxiliary Nozzle

  Auxiliary nozzle mainly plays the role of the relay nozzle, the auxiliary spray pressure is small, the weft is not easy to be straightened thereby causing weft stop. If the auxiliary spray pressure is too large, the electromagnetic needle after closure easy to blow off the weft, the general auxiliary spray pressure than the main injection pressure 0.15MPa, the final spray pressure equals the auxiliary spray pressure. Auxiliary spray pipe rupture, nozzle blockage, auxiliary injection solenoid valve iron core is not flexible can cause the jet air disconnection, lag, resulting in weft stop. Air-jet loom The height and angle deviation of the auxiliary spraying is too large, it is easy to cause the jet airflow direction to skew, which causes the weft to change in the direction of the weft.

  II. Bobbin Rack and weft device

  The height of the parts on the bobbin rack and improper installation angle will increase the resistance of weft insertion, especially the leaf spring pressure assembly, so that the resistance of weft insertion increases obviously and the stopping of weft-stop is caused.

  Weft electromagnetic needle opening and closing time is improper, the gap between the electromagnetic needle and the long board is too large or too small, it is also easy to cause error, the gap is generally 1.5mm~0 8mn. The electromagnetic needle is not centered on the long plate, the electromagnetic needle wear, Air-jet loom the endothelium gasket wear, the spring elasticity is insufficient or too strong, it is possible to cause errors in the weft and parking.

  Three, left side shears

  After the end of the projection, the left side of the shear should be accurate in time to cut the weft, guarantee the next pitch. Premature or late shearing time not only affects the weft and tension after shearing, but also affects the next pitch, and the general shearing time is 25° around. Scissors cutting edge, can not smooth timely cut the weft, shearing time will be prolonged, directly affect the next pitch. Scissors cutting edge to be replaced in a timely manner, the installation must pay attention to the top and bottom position of the scissors, the correct adjustment of the opening amount of shear time and shear position.

  Four, weft detector

  The weft is normal, and the detection of weft detector error, resulting in no parking, the main reason for two points.

  (1) If the weft detector is damaged or the surface is not clean, the effect of weft insertion should be changed or cleaned up in time. When cleaning regularly, the optical surface of the light source and photoelectric element can be cleaned with anhydrous ethanol.

  (2) The sensitivity and detection pulse number of the weft detector is improper, the detection is not allowed, the sensitivity of the left-sided probe can be increased, Air-jet loom the detection pulse number is reduced, or the sensitivity of the right weft detector is reduced, and the detection pulse is increased.

  V. Opening part

  We have done the investigation of the juice, more than 70% of the weft stop is not clear caused by openings. The Air-jet loom is a free end weft insertion, and the weft ends fluctuate forward when the weft is introduced, so long as it encounters several roots or even a warp opening, it will cause the weft to stop. In order to fundamentally solve the weft stop, it must be from the opening part of the staff. The main factors influencing the opening are the following aspects.

  (1) Yarn quality and workshop temperature and humidity. The quality of raw yarn and sizing, especially the hairiness, have a great influence on the clarity of the openings. When the relative humidity of the workshop is high, the warp is more hygroscopic, which makes the warp opening adhesion unclear.

  (2) Mechanical state. Tread cam wear, pedal wear, wheel wear, wire rope elongation, the spring rally is not enough, the timing is improper and the installation angle is not correct, the full card off, the high and low position of the box, Air-jet loom reed damage deformation or raising defects, auxiliary nozzle top yarn. can cause openings to be unclear.

  (3) Weaving process. The effect of weaving process on openings is obvious, in order to make the weft with a clearer spindle mouth, it can increase the warp tension, increase the opening motion, the opening time ahead, the time delay, increase the throughput, reduce the rear depth of the spindle, reduce the difference of the upper and lower layer warp, and decrease the speed.

  In the selection or adjustment of these processes, we should consider the characteristics of the fabric and the requirements of the process, Air-jet loom the original yarn and semi-finished products, the quality of the machinery itself, and other factors, as far as possible to reduce other negative effects, especially the warp end, must not be loss.

  VI. Summary

  Weft stop to carefully observe the location and shape of the weft, which can help us find the cause of the weft stop, and then the destination to take measures. In short, as long as the original yarn and sizing quality to ensure the premise of reasonable selection of weaving technology, and further strengthen equipment management, Air-jet loom weft stop can be controlled.