Stitching-starting thread-drawing device for automatic thread-cutting sewing machine

Abstract

The invention relates to a threading tension device for a sewing machine, in particular to an automatic control tension device for the sewing machine, namely a stitching-starting thread-drawing device for an automatic thread-cutting sewing machine. In the stitching-starting thread-drawing device for the automatic thread-cutting sewing machine, a thread-drawing electromagnet and a link mechanism are arranged on the conventional threading tension adjusting and thread loosing device; and the thread-drawing electromagnet and a thread loosing electromagnet are controlled to alternately act by a controller of a sewing machine motor to drive a swinging thread hook when stitching is started each time, pull back a needle and a thread at a needle starting point upwards, and passingly reposition theswinging thread hook by using the action of the thread loosing electromagnet after automatic cutting when the stitching is finished each time, so that the length of thread ends of stitching-starting threads can be shortened, and the operation of manually removing the redundant thread ends is omitted.

Description

technical field [0001] The invention relates to an upper thread tension device of a sewing machine, in particular to an automatic tension control device of a sewing machine. Background technique [0002] The automatic thread-cutting sewing machine of the prior art will keep a section of needle thread on the needle when the automatic thread-cutting action is completed after the sewing is finished, and the length of the thread end from the needle hole is about 40mm, so as to avoid the thread end from slipping out of the needle hole when the next sewing starts. Causes the hassle of needing to rethread. However, this section of needle thread will be drawn into the bottom of the fabric by the needle and then pulled down by the rotary hook at the next sewing start, and will form a bunch of redundant thread ends under the first stitch of the fabric, which will easily cause poor appearance or require manual re-threading. Trim excess thread length. [0003] Then, there is a sewing ...

AI Technical Summary

Problems solved by technology

[0002] The automatic thread-cutting sewing machine of the prior art will keep a section of needle thread on the needle when the automatic thread-cutting action is completed after the sewing is finished, and the length of the thread end from the needle hole is about 40mm, so as to avoid the thread end from slipping out of the needle hole when the next sewing starts. Causes the hassle of rethreading

However, this section of needle thread will be drawn into the bottom of the fabric by the needle and then pulled down by the rotary hook at the next sewing start, and will form a bunch of redundant thread ends under the first stitch of the fabric, which will easily cause poor appearance or require manual re-threading. Trim excess thread length

[0003] Then, there is a sewing machine manufacturing industry to develop a way to reduce the length of the seam head, such as the disclosed Chinese invention patent publication number CN 101372797A "sewing machine and the method for sewing the seam head with this sewing machine", which is in the existing Three sets of electromagnets for timing control are added to the automatic thread cutting sewing machine with advanced technology, but because of its complex mechanism and high cost, it still does not meet the needs of use in actual use.

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