Stitch ravelling prevention method and its device

Abstract

The invention provides a stitch ravelling prevention method and its device, capable of keeping the whole compact of the device and simultaneously making a thread end of a curved stitch thread in a cloth completely short in no need of treating the thread end. The device comprises: a supporting cutter at the retreating position side of the curved stitch, a hook capable of reciprocating together with the supporting cutter, a limit unit for limiting the advance and retreatment of the hook, a path changing mechanism for changing the reciprocating path of the hook, furthermore comprises: a control mechanism for controlling the following process: the hook is made to come out at the end of sewing, so as to be fastened with the annular stitch thread and the curved stitch thread of the curved stitch and when the hook treats and after the curved stitch thread is captured, the limit unit is used for making the front end of the hook stop behind the annular stitch thread and after the hook stops, the reciprocating path of the hook is changed, simultaneously the sewing machine is driven by one stitch amount to advance the curved stitch again, thus the hook reciprocates and comes out to be fastened with the annular stitch thread captured by the curved stitch and simultaneously fastened with the annular stitch thread and the curved stitch thread of the curved stitch and then the fastening parts of threads are cut off by the supporting cutter by the reciprocation.

Description

technical field [0001] The present invention relates to a method and a device for preventing seam fraying from the sewing end side of the seam when forming a double loop seam or a flat seam on a cloth by a sewing machine. Background technique [0002] As a prior art seam opening preventing device, the following scheme is known: when the sewing ends, the looper moves forward to the forward position, and the hook is engaged with the looper thread from the endless machine needle thread to the looper, Cut off the engaging part of the looper thread with the backer knife arranged on the side of the looper's retreat position, and then, after driving the sewing machine for one stitch, catch the looped needle thread caught by the looper and the looped needle thread with the hook. The looper thread to the looper is cut with the above-mentioned carrier knife (for example, refer to Patent Document 1). By the operation of this device, the end of the seam formed on the cloth is prevented...

AI Technical Summary

Problems solved by technology

[0004] However, in the prior art seam opening prevention device, the amount of pullback of the looper thread formed by the U-shaped thread guide and the L-shaped thread guide when driving the sewing machine for one stitch is only a small amount. The length of the thread end drooping at the end of the fabric cannot be shortened sufficiently

Therefore, in order to make the appearance of the sewn product beautiful, there is a difficulty that the sewing operator must take out the end of the thread from the cloth with tweezers or the like, or cut off the end of the end of the thread again with scissors or the like.

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