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 How to eliminate the "three jumps" defects of rapier looms


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

(1) For cleaning the falling objects, the falling object rate is changed from 2.57% to 4.43% by adjusting the A036 and A076 dust bar gap; the carding falling objects, by adjusting the rear belly falling object gap, the falling object rate is changed from 5.2% It becomes around 6.5%. After adjustment, the number of hemp rods and skins on the surface of the yarn is reduced, and the chance of mixing during weaving is also reduced, which can reduce "triple jump" defects by 20% to 30%.

(2) Rapier looms have higher requirements on the quality of the raw yarn, the longer the unevenness of the long segment, the better, the general requirement is 3% to 4%, the evenness CV value is 20% to 25%, and the single yarn strength CV The value is between 18% and 20%.

(3) To improve the quality of joints, the end length is generally 1.5mm ~ 4mm is the best, and the joints with larger twists should be specially prevented from small braids.

(4) The warping requirements ensure the "three spirits", that is, the tension ring rotates flexibly, brakes flexibly, and the ends are automatically stopped. At the same time, the side yarns are slightly heavier to make the full warp tension uniform.

(5) Improve the quality of sizing, improve the definition of warp shedding, choose sizing reasonably according to the variety and formulate the sizing rate. Generally, the sizing rate of hemp and cotton is 8%-9%, which can meet the requirement of forming a smooth and wear-resistant sizing film on the surface of the warp yarn. To correctly grasp the moisture regain, the relative humidity of the weaving workshop is above 80%, the sizing regain can be controlled at about 7% to 8%; the elongation of the sizing is controlled reasonably, and the sizing fabric is controlled below 1%; the enhancement rate is in the range About 10% to 15%, which can meet the requirements of rapier loom fabrics.

2. The timing of opening and entering the sword should be appropriate
Yarn skipping defects generally have more opportunities on the side of the weft sword. Therefore, different configurations can be used to adjust the weaving parameters on both sides. The weft sword enters the clearer weaving mouth. Generally, the opening time of linen and cotton varieties should be 290°～300°, and the time of entering the sword should be 70°～75°. When entering the sword, the position of the weft feeding sword head is 4-6 guide pieces from the weaving mouth, and the position of the weft connecting sword head is 2 from the weaving mouth. ~ 4 guide rails, but also to ensure that the sword enters slowly and exits quickly, so that the sword has enough time to pass through the clear kendo and reduce the chance of yarn skipping.

3. Adjustment of warp position line
Adjust the height of the position line, generally only adjust the height of the warp stop and the rear beam. When the warp drop frame and the back beam are raised, the tension difference between the upper and lower layers of warp yarns increases. When the weaving mouth is fully opened, the lower layer warps are tight and the upper layer warps are loose, so that the warp yarns are evenly arranged and a fuller cloth surface can be obtained. If it is lifted too high, the upper warp yarns are too loose, and the warp yarns stick to each other, making the opening unclear and prone to star jumps. The height of the back beam of general linen and cotton varieties is 70mm～80mm, the height of the warp stop is 30mm～40mm, and both ends should be kept level.

4. Correct hoisting heald specifications
Generally, the lower warp yarns should be slightly lower and not higher. It is better to avoid the collision of the upper and lower warp yarns when the sword head enters the weaving mouth. The upper shaft and maintenance work should be adjusted to the hoisting healds to ensure that the "three aligns" are all heald frames, heald rods, and pedals and rotors. "Siping" means that the heald frame (heald rod) is flat, the heddle bolt is flat, the heddle plate is flat, and the heald rod is flat. If it is unqualified, check whether the heald clamp is off, whether the top wire of the tread plate is loose, whether the heald pad is worn out, whether the heald belt is deformed, and so on. Generally, the front and rear position of the hoisting heald shaft is about 110mm～120mm, the movement does not exceed 0.8mm, and the height of the hoisting heald is 400mm～410mm. The above measures have been used to weave 8s×8s42×38 hemp cotton plain weave on GA747 loom. The efficiency of the loom has been increased from 50% to 65%, and the "triple jump" defect has been reduced from 500 to about 200 in 90m cloth. These data are tracked by dedicated stations.