How to deal with the “three-jump” defect of rapier loom?

1. Start with each process of spinning and semi-finished products

1. In cleaning the fallen objects, by adjusting the distance between the dust rods a036 and a076, the falling object rate changes from 2.57% to 4.43%; in carding the falling objects, by adjusting the distance between the rear car belly and the falling objects, the falling object rate changes from 2.57% to 4.43%. 5.2% became about 6.5%. After adjustment, the number of hemp and hemp on the yarn surface will be reduced, and the chance of mixing during weaving will also be reduced, which can reduce “three-jump” defects by 20% to 30%.

2. Rapier looms have higher quality requirements for raw yarns. The smaller the unevenness of long segments, the better. The general requirements are 3% to 4%. The evenness CV value is 20% to 25%. Single yarn The strong CV value is between 18% and 20%.

3. Improve the quality of joints. The end length is generally 1.5mm to 4mm. Special precautions should be taken for joints with larger twists.

4. Warping requires the “three spirits” to be ensured, that is, the tension ring can rotate flexibly, brake flexibly, and end-breaking can stop automatically. At the same time, the side yarns are slightly heavier to make the warp tension uniform throughout the entire width.

5. Improve the quality of sizing, improve the clarity of warp openings, reasonably select sizing materials and set the sizing rate according to the variety. Generally, the sizing rate of linen and cotton is 8% to 9%, which can form a smooth and wear-resistant sizing film on the surface of the warp yarns. . It is necessary to correctly control the moisture regain. If the relative humidity of the weaving workshop is above 80%, the moisture regain of the sizing yarn can be controlled at about 7% to 8%; the elongation of the sizing yarn should be reasonably controlled, and the sizing fabric should be controlled below 1%; the reinforcement rate range is within About 10% to 15%, which can meet the requirements of rapier loom fabrics.

2. The timing of opening the mouth and entering the sword should be properly coordinated

Yarn skipping defects generally occur more often on the side of the weft-feeding sword. Therefore, different configurations can be used to adjust the weaving parameters on both sides. That is, the advancing time of the weft-feeding sword should be appropriately delayed, and the advancing time of the weft-receiving sword should be advanced appropriately. , so that the weft-feeding sword enters a clearer weaving mouth.

Generally, the opening time of linen and cotton varieties should be 290°~300°, and the rapier advance time should be 70°~75°. When the rapier is advanced, the position of the weft rapier head is 4 to 6 guide rails away from the weaving mouth, and the position of the weft rapier head is 4 to 6 guide rails away from the weaving mouth. There are 2 to 4 guide rails at the weaving edge, and the sword must be slow to enter and the sword to be withdrawn quickly, so that the sword has enough time to pass through the clear sword path and reduce the chance of yarn skipping.

3. Adjustment of the warp position line

Adjust the height of the position line. Generally, you only adjust the height of the drop frame and the back beam.Low. When the drop frame and the back beam are raised, the tension difference between the upper and lower warp yarns increases. When the cloth fell is fully open, the lower warp yarns are tight and the upper warp yarns are loose, so that the warp yarns are arranged evenly and a fuller cloth surface can be obtained.

If it is raised too high, the upper warp yarns will be too loose and the warp yarns will stick to each other, making the opening unclear and prone to star jumps. Generally, the height of the back beam of linen and cotton varieties is 70mm ~ 80mm, the height of the drop frame is 30mm ~ 40mm, and both ends should be kept level.

IV. Correct hanging harness specifications

Generally, it is better to control the lower warp yarn to be slightly lower than higher, so that the sword head enters the weaving mouth without encountering the upper and lower warp yarns. During lifting and maintenance work, the lifting healds must be adjusted to ensure that the “three things are in perfect order”, namely, the heald frames are straight, the tread heald rods are straight, and the pedals and rotors are straight. “Four levels” means the heald frames (heald bars) are flat, the lifting heald bolts are flat, the lifting heald plates are flat, and the tread heald rods are flat.

If it is unqualified, you should also check whether the heald clamp has fallen off, whether the tread plate top wire is loose, whether the lifting heald bearing pad is worn, whether the lifting heald belt is deformed, etc. Generally, the front and rear position of the lifting heddle shaft is about 220mm ~ 120mm, the movement does not exceed 0.8mm, and the height of the lifting heddle is 400mm ~ 410mm.

The above measures have been tested on GA747 loom weaving 8s×8s42×38 linen and cotton plain weave. The loom efficiency increased from 50% to 65%, and the “three-jump” defects in 90m cloth were reduced from 500 to 200. This data is tracked by a dedicated station.