On this section, we’ll go through the most common causes of damaged wefts in a rapier weaving machine. Here are some of the most common reasons of weft breakage at the weft guide, as well as some recommended fixes.
- The left sword head has poor yarn clamping.
First, the yarn gripper on the left of the sword head is too unsteady to grasp the yarn. The bottom yarn grasping piece may be loose, the rubber pad degummed or dropped, or the top yarn gripper pressing component is misshapen or contains burrs. Use elastic glue to prevent the rubber pad from getting firm and losing elasticity while attaching the bottom yarn clip.
This may easily lead to poor gripping force on the sword head because to the weft yarn being cut prematurely. As a consequence of the unstable position of the left sword, the weft yarn will become loose during weaving, resulting in weft breakage. Because the shearing of the weft occurs at an inopportune moment, with a clamping position at the rear, and with the thin yarn being weaker and more readily torn than the thick and special yarn, the weft might come out of the left sword, damage the sword head, and even cause punching. A broken sword belt and a shattered sword head were found. Weft breakage may be attributed to the weft yarn shearing time, which requires a lot of experimentation and careful correction.
Another problem that might occur over time is a worn or colliding rear yarn guide rod, which can cause damage to the weft yarn’s hanging position before it can enter the yarn clipping piece or be in its regular position when it is cut, leading to yarn clipping. Weft breaks as a consequence of a poor or failed transfer. Repair and polish or replace the left rapier and examine and adjust the position of the yarn guide rod and the rapier at the same time as the solution is found.
- The weft selecting finger should not be in the incorrect position.
When selecting a weft, it’s simple to break the weft if the finger is too high. Because the weft selection is too low, it’s easy to get duplicate weft. Ensure that the weft yarn is stable when the rapier clamps the yarn down, while at the same time ensuring that the weft does not rub against the heald frame by adjusting the height of the weft selection finger so that the threading hole is 2 mm to 3 mm away from the yarn guide rod and 5 mm to 7 mm lower than the yarn guide rod.
guide for the weft
The weft guide’s placement is critical. There is a risk of weft breakage when the reed and weft guide are too close together during weft beating and squeezing. If the weft guide is too far away from the reed, the weft will have difficulty entering the guide hook smoothly. During weft insertion shearing, the weft yarn does not enter the shearing position, which causes weft breakage. Setting the weft guide’s height to a precise level is essential. Overly high weft tension prevents the weft from passing through to the guide hook in the first place. As a consequence, if the weft scissors are too low, the weft will collide with the weft scissors, resulting in weft breakage. While shearing, beating, and inserting the weft, it is important that the blade groove is slightly higher than 1 mm above the support plate so that the weft may enter the weft guide accurately and smoothly throughout the shearing process.
A pair of weft scissors is the fourth piece of equipment.
There will be no smooth cutting of weft if the location of the weft scissors is not correctly set. Weft breakage is likely to occur. In order to make the necessary adjustments, spin the loom’s main shaft 30 degrees, unlock the weft shear cam locking screw, set the lower scissors to their lowest setting, undo the scissor arm locking screw, and then set the lower scissors’ blades to be 5 millimeters away from the green flannel. It is recommended to start with 20 mm between each piece of fabric and then fine-tune the spacing based on how long it takes to cut each piece.
In addition to a fair shearing duration, the weft yarn must be cut smoothly and the rapier must correctly grasp the weft yarn to ensure excellent scissors collaboration. Incorrectly matched scissors might result in broken weft or damage to the rapier and machine components while cutting weft yarn. Having shifted the scissors’ position, correct their blades’ fit.
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If the position of the weft scissors isn’t right, the weft yarn won’t be able to get into the cutting opening, so the weft yarn won’t be cut smoothly, which will cause the weft to break. First, turn the loom’s main shaft 30 degrees, loosen the weft shear cam locking screw, adjust the lower scissors to the lowest level, loosen the locking screw on the scissors arm, adjust the lower blade to be 5 mm away from the green flannels, and adjust the upper scissors. The distance between the pieces is 20 mm from the green flannel. Then, the cutting time is used to adjust the distance between the two pieces.
Weft yarn must be cut smoothly, and scissors must work together well. In addition to a reasonable amount of time for cutting, there must be good scissors cooperation. In this case, the weft yarn will not be cut smoothly, which could break the weft or damage the rapier and the machine parts. After moving the scissors, make sure the two blades fit together.
- The yarn on the left sword head doesn’t stay in place.
First, the yarn gripper on the left side of the sword isn’t stable enough to hold the yarn. The lower yarn gripping piece could be loose, the rubber pad could be degummed or dropped, or the upper yarn gripper pressing piece could be bent or have burrs. It’s best to glue the lower yarn clip in place, but you should use elastic glue to keep the rubber pad from becoming hard and losing its shape.
As a second problem, too early cutting of the weft yarn will make the sword head too loose or not strong enough. There is a problem with the position of the left sword clamping yarn. This will cause the weft yarn to come loose during the weaving process, which will cause the weft to break. Because the weft is cut too late, the clamping position is in back. The thin yarn is weak and easy to break, while the thick yarn is strong. This makes it easy for the weft to come out of a sword, damage the head, or even cause a punch. Damage to the head of the sword is also noticeable. So, the time it takes for the weft yarn to be sheared is one of the main causes of the weft breakage, which requires a lot of testing and careful adjustments.
This is the third thing that will happen after a long time. The rear yarn guide rod will get worn or bump into a rapier on the right. This will make it hard for the weft yarn to get into a clipping piece or stay in a normal position when the yarn is clipped. Poor or bad handover, which caused the weft to break. To fix it, polish or repair the left rapier. Also, check and adjust the connection point between a yarn guide rod and a rapier at the same time.
- The weft selection finger is in the wrong place.
If the height of the weft selection finger is too high, it is very easy to break the weft. Selecting the weft means that the weft is too low, which makes it easy to make double weft. When the weft selection finger is at its lowest point, adjust the height of the weft selection finger so that the threading hole is 2 mm to 3 mm away from the yarn guide rod and 5 mm to 7 mm lower than the yarn guide rod. This will make sure that the weft yarn is stable when the rapier clamps the yarn down, and will also make sure that the weft does not rub against the heald frame.
- The weft is a guide.
It is very important where the weft guide is. To make sure that the weft isn’t broken when it’s weft-beaten, you should be close enough to the reed that there isn’t any friction between the reed and guide when the weft is being beat. In this case, it is very easy to get a shear failure, and the weft yarn does not get into the correct position when the weft is inserted. This results in weft breakage. Weft guides should be set at a certain height. If it’s too high, the weft won’t get into the guide hook. A lot of weft will be broken if it is too low. The weft scissors will hit the weft when it is cut. The right place for the weft guide is 1 mm from the weft scissors, 1 mm from the edge of the reed, and the blade groove is slightly higher than 1 mm from the support plate. This way, the weft can be inserted smoothly and correctly into the weft guide during beating, weft insertion, and cutting.
This is the fourth thing you need: Weft scissors
If the position of the weft scissors isn’t right, the weft yarn won’t be able to get into the cutting opening, so the weft yarn won’t be cut smoothly, which will cause the weft to break. First, turn the loom’s main shaft 30 degrees, loosen the weft shear cam locking screw, adjust the lower scissors to the lowest level, loosen the locking screw on the scissors arm, adjust the lower blade to be 5 mm away from the green flannels, and adjust the upper scissors. The distance between the pieces is 20 mm from the green flannel. Then, the cutting time is used to adjust the distance between the two pieces.
Weft yarn must be cut smoothly, and scissors must work together well. In addition to a reasonable amount of time for cutting, there must be good scissors cooperation. In this case, the weft yarn will not be cut smoothly, which could break the weft or damage the rapier and the machine parts. After moving the scissors, make sure the two blades fit together.
