The 2+2 ribbed dial and the needle groove of the needle cylinder are arranged alternately. When the needle plate and the needle barrel are arranged, one needle is drawn every two needles, which belongs to the needle drawing type rib tissue. Holes are prone to occur during the production process. In addition to the general adjustment methods, when weaving this type of rib structure, the distance between the cylinder mouths is generally required to be as small as possible. The purpose is to reduce the length of the settlement arc formed when the dial needle and the cylinder needle are interwoven.
The schematic diagram of the coil structure is shown in Figure 1. Because the size of L directly determines the distribution of loops, its other function is to generate torque due to the release of the twist of this segment of yarn, which pulls loop a and loop b together, closes and overlaps each other to form a unique fabric style. For the hole phenomenon, the size of L plays an important role. Because in the case of the same line length, the longer the L, the less the yarn length occupied by the loops a and b, and the smaller the loops formed; and the shorter the L, the longer the yarn length occupied by the loops a and b will form. The coil is also larger.
Reasons for the formation of holes and specific solutions
1. The fundamental reason for the formation of holes is that the yarn receives a force that exceeds its own breaking strength during the weaving process. This force can be generated during the yarn feeding process (the yarn feeding tension is too large), it may be caused by too large bending depth, or it may be caused by the steel shuttle and the knitting needle being too close, you can adjust the bending yarn The depth and the position of the steel shuttle are resolved.
2. Another possibility is that the old loop cannot be completely retracted from the needle after the loop is unlooped due to too small tension in the winding or too small bending depth of the needle plate. When the knitting needle is lifted again, the old loop will be broken.This can also be solved by adjusting the roll tension or the bending depth. Another possibility is that the amount of yarn hooked by the knitting needle is too small (that is, the cloth is too thick and the thread length is too short), which results in the loop length being too small, smaller than the circumference of the needle, and the loop is unlooped or unwound. Difficulty occurs when the needle is broken. This can be solved by increasing the amount of yarn fed.
3. The third possibility is that when the yarn feeding amount is normal, the L-segment yarn is too long due to the high cylinder mouth, and the loops a and b are too small, which makes it difficult to unwind and break off the loop, and eventually it will be broken. At this time, it needs to be reduced. The height of the dial and the distance between the cylinder mouths are reduced to solve the problem.
When the rib knitting machine adopts the post-position knitting, the loop is too small and it is often broken when the loop is retracted. Because when in this position, the dial needle and the cylinder needle are retracted at the same time, the loop length is much larger than the loop length required when the loop is released. When unlooping is carried out step by step, the needle cylinder knitting needles fall off the loop first, and then the needle plate falls off the loop. Due to the coil transfer, a large coil length is not required when uncoiling. When using counter-position knitting, when the loop is too small, the loop is often broken when it is unlooped. Because the old loop is taken off at the same time on the dial needle and the needle of the barrel when the position is aligned, although the unwinding is also performed at the same time, because the circumference of the needle (when the needle is closed) is larger than the circumference of the needle pin part, Therefore, the coil length required for uncoiling is longer than when uncoiling.
In actual production, if the common post-position knitting is adopted, that is, the needles of the cylinder are bent before the needles of the dial, the appearance of the fabric is often tight and clear in the cylinder loops, while the loops of the dial are loose. The longitudinal stripes on both sides of the fabric are spaced large, the fabric width is wider, and the fabric has poor elasticity. The reason for these phenomena is mainly due to the relative position of the dial cam and the needle cylinder cam. When using post-eating knitting, the needle of the needle cylinder will be released first, and the removed loop will become extremely loose after getting rid of the expansion of the needle of the needle cylinder. There are only two newly fed yarns in the loop, but at this time the dial is As the needle just enters the unlooping process, the old loop is stretched by the needle of the dial needle and becomes tight. At this time, the old loop of the needle cylinder has just finished unlooping and becomes very loose. Because the old stitches of the dial needle and the old stitches of the needle cylinder are formed by the same yarn, the old stitches of the loose needle cylinder needles will transfer part of the yarn to the old stitches of the tight dial needles to help the old needles of the dial needle. The coil unwinds smoothly.
Due to the transfer of the yarn, the old loops of the loose needle cylinder needle that have been unlooped become tight, and the old loops of the originally tight dial needle become loose, so that the unlooping is completed smoothly. When the dial needle is unlooped and the cylinder needle has been unlooped, the old loops that have become tight due to the loop transfer are still tight, and the old loops of the dial needle that have become loose due to the loop transfer are still slack after the completion of unlooping. If the cylinder needle and the dial needle have no other actions after completing the loop-off action and directly enter the next knitting process, the stitch transfer that occurs during the loop-off process becomes irreversible, which results in the formation of the post-knitting process. The back side of the cloth is loose and the front side is tight, which is why the stripe spacing and width have become larger.