Method for preventing seam ravel of multi-thread chain stitches, seam ravel preventing apparatus for multi-thread chain stitch sewing machine, and multi-thread chain stitch seam structure

Abstract

A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

Description

technical field [0001] The present invention relates to a stitch opening method for anti-double chain ring sewing, a stitch opening device for double chain ring sewing machine and a stitch structure for double chain ring sewing. A stitch of a double chain loop stitch is formed by a sewing thread and a looper thread, and generation of an open thread at a sewing end portion of the stitch of the double chain loop stitch is prevented. Background technique [0002] A general double-chain sewing machine such as a horizontal cylinder type includes: a needle that holds a suture thread and rises and falls; Direction forward and backward movement, by repeatedly using the forward movement of the above-mentioned looper to catch the suture loop formed by the above-mentioned needle under the needle plate, and use the looper thread held by the looper to inter-wind the above-mentioned suture, so that when sewing The stitching that forms the double chain loop seam on the fabric. [0003] T...

AI Technical Summary

Problems solved by technology

[0003] There are following problems in the structure of the stitches M of the general double-chain loop stitching formed by the double-chain loop sewing machine: Figure 27 As shown, the end of the looper thread 10 that is cut off at the end of sewing is Figure 27 When stretched in the direction indicated by the middle arrow, the looper thread 10 will be pulled out from the final suture loops 20a, 20b formed by the sutures 20, 20. There will be open lines on the whole of the stitch M

[0009] However, in the currently proposed anti-opening method, there are the following problems: Figure 28 and Figure 29 The y-direction of the looper thread 10 is easy to pull out from the final suture loops 20a, 20b when the tensile force is applied in the y direction. The whole stitch will produce open lines

[0011] Particularly, in the case of the stitches of the double chain loop stitching formed by one needle, the looper thread 10 is only interwoven with the last stitch loop 20a of the stitching thread 20 in the state of being intertwined, therefore, Pull-out occurs only by applying a slight tensile force, so the effect of preventing thread opening is very low

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