Sewing machine for double chain stitch

Abstract

In a double chainstitch sewing machine, a movable thread guide is fixed to the lower end of a needle bar. A fixed thread guide and a thread take-up cam are fixed to a jaw of a sewing machine arm. The thread take-up cam has a cam section to be engaged with needle threads from the fixed thread guide to the movable thread guide, and takes up the needle threads oscillating up and down by vertical motion of the movable thread guide. Thread take-up members such as movable thread guide, fixed thread guide, and thread take-up cam are disposed centrally at the lower end of the needle bar near the needle and in the jaw 43a of the sewing machine arm. As a result, there is no member for thread take-up moving at the upper side and front side of the sewing machine arm, and dangerous positions for the operator can be decreased. Further, the thread pathway length from the workpiece to the thread tension device is shortened, and the effects of thread stretch of properties can be decreased.

Description

technical field [0001] The present invention relates to a stitch-forming double chain stitch sewing machine for sewing decorative threads on the underside or top and bottom of cloth. Background technique [0002] Fig. 11 shows an example of a double-strand stitch sewing machine for stitching decorative threads on the lower surface of the cloth, which has: the head 111a of the sewing machine arm 111 is vertically passed through and supported by a shaft, and the main shaft is linked to reciprocate up and down. The moving needle bar 112; the shaft is supported on the sewing machine arm 111, swings with the up and down movement of the needle bar 112, and the swing shaft 113 whose extension protrudes from the front of the sewing machine arm 111; is arranged on the base of the sewing machine arm 111, A plurality of thread adjusters 117 for adjusting the thread tension; and a fixed thread guide 114 through which the threads drawn out from the thread adjusters 117 pass. A movable t...

AI Technical Summary

Problems solved by technology

Therefore, it is easy to be affected by the expansion and contraction characteristics of the wire, and it is difficult to obtain the optimal wire feeding amount.

[0006] Especially for a thread with high stretchability such as wool thread, the movable thread guide, the first thread feeding member and the second thread feeding member also cause the thread feeding function to be unstable because the effect of thread elongation greatly exceeds the thread feeding function

Since it is difficult to adjust the amount of thread feeding by both the first and the second, there are double-strand stitches that are difficult to obtain the desired feel.

In addition, because the upper decorative thread is fed synchronously with the needle thread, it is difficult to obtain the desired double-sided decorative double chain stitches.

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