Method for preventing fraying of stitches and sewing machine

Abstract

The invention provides a ripped seam prevention method for a stitch and a sewing machine. According to the method, after general sewing of double lock stitch is finished, a needle and thread loop of a needle positioned on an advancing side of a curved needle is at least caught and retained by the aid of a thread retaining component, the needle drops into the retained needle and thread loop, the needle and thread loop is automatically connected by the aid of the retained needle and thread of the needle, and the tip of the needle projects from the lower surface of a needle plate and drops into the range of the lower surface of the curved needle when the needle and thread loop is caught by the thread retaining component, and the thread retaining component catches the upstream portion of the needle and thread loop caught by the curved needle relative to the curved needle. Skipped stitching and cutoff of the needle and thread loop can be prevented, the needle and thread loop is prevented from being enlarged after seams are ripped, and a driving device is miniaturized.

Description

technical field [0001] The present invention relates to a thread fray prevention method for preventing fraying at a seam at the end of sewing in stitches of double-thread lockstitch formed by a needle thread and a looper using a sewing machine such as a double-thread lockstitch sewing machine and a lockstitch sewing machine, and its implementation. The sewing machine of the fraying prevention method. Background technique [0002] The stitches of the double-thread lockstitch are captured by the looper that enters in the above-mentioned direction of the arrangement of the needles, and the looper thread held by the looper The above-mentioned needle threads are interconnected and formed on the sewing material that is fed and moved on the above-mentioned needle plate. [0003] However, the stitches of such double overlock stitches have the disadvantage that the whole stitches are easy to unravel when the final stitches are untied, so it is known to implement a technology to prev...

AI Technical Summary

Problems solved by technology

[0006] However, the method and device for preventing fraying of stitches proposed in this patent document 1 have the following problems: that is, if Figure 12 As shown, when the hook 131 approaches the looper 101 to catch the needle thread loop held by the looper 101, the needle 102 is located above the sewing material S' placed on the needle plate P'

[0011] However, as mentioned above, if the needle thread loop 106a is large, the needle thread loop 106a cannot tighten the end portion 106b of the needle thread, so the needle thread 6 passing through the thread loop is easy to come out, and the effect of preventing fraying is lost.

[0012] In addition, since the moving distance S1 of the thread hook 131 becomes longer, the structure itself for driving the thread hook 131 becomes larger, and the entire sewing machine becomes larger, which has adverse effects such as difficulty in handling the sewing product during sewing.

[0013] In addition, if Figure 13 As shown, the hook 131 catches the needle thread loop relative to the downstream part of the looper 101, that is, the part on the side where the stitch has been formed, and holds it on the rear side of the above-mentioned looper 101, so it is easy to form the stitches that have been sewn. Usually, the thread of the stitch in the sewn part is pulled out from the sewing material S', causing the shape of the stitch to be skewed, affecting the appearance, and reducing the quality and price of the sewn product

[0014] Moreover, the needle thread loop pulled to the holding position by the thread hook 131 will also rub against the looper 101, and the needle thread loop will be cut off, and the sewing operation must be carried out again, or the sewing product will be damaged. drop in quality

[0015] In addition, since the needle thread loop moved by the thread hook 131 as a whole moves relative to the needle toward the direction in which the looper 101 enters, the needle thread and the looper thread may be skipped without being entangled.

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