Sewing machines

Abstract

The patent relates to a sewing machine 1 in which a needle thread loop 101 is formed by the co-operation of a needle 6 and a semi-rotating shuttle to perform lock stitch. This sewing machine 1 includes a needle thread take-up lever 14 for taking up the needle thread loop 101, a main shaft motor 7 for driving the needle 6 and the needle thread take-up lever 14, a fixed knife 27 fixed in the vicinity of the semi-rotating shuttle, a movable knife 28 capable of freely approaching and separating from the fixed knife 27, a pulse motor 21 for driving the movable knife 28, and a control device 8 for controlling the pulse motor 21 and the main shaft motor 7. The movable knife 28 is stopped immediately before the movable knife 28 meets the fixed knife 27 at the final stitch under the control of the control device 8, and then the needle thread take-up lever 14 is raised and stopped. After that, the movable knife 28 is moved to cut the needle thread and the bobbin thread with the fixed knife 27. The sewing machine is capable of stabilize the so-called remaining length of a needle thread without lengthening the time required for cutting the needle thread.

Description

technical field [0001] The present invention relates to a sewing machine having a movable cutter for cutting noodle threads, a fixed cutter, and a cutter drive mechanism for driving the movable cutter, and particularly relates to a method for combining the above-mentioned drive mechanism with a so-called sewing drive source. Set of sewing machines. Background technique [0002] In previous sewing machines, the power of the main motor rotating the main shaft is transmitted to the needle and the thread take-up lever on the machine head through the main shaft, so that the needle and the thread take-up lever can move up and down. In addition, the power of the main motor is also The hook is driven by the lower shaft being transmitted to the hook inside the machine. [0003] In addition, it is well known that conventional sewing machines have an upper thread cutting device for cutting the upper thread. The upper thread cutting device has a fixed cutter fixed close to the rotary ...

AI Technical Summary

Problems solved by technology

If the remaining length is long, the end of the upper thread exposed from the needle drop point at the beginning of the next sewing will be long, and the appearance of the sewn product will be deteriorated. Therefore, the operator must remove the upper thread end by hand after sewing. head cut off, its work efficiency is low

On the other hand, if the remaining length is short, the upper thread is pulled out from the threading hole of the needle when the needle is lowered at the next sewing start, and then the needle is lowered to the fabric, and the needle remains on the fabric to be sewn. Useless needle drop traces reduce the grade of sewing products

Moreover, it is necessary to restart sewing after threading the thread onto the needle, which also reduces work efficiency

[0006] On the other hand, when the thread take-up operation is reduced to a low speed in order to suppress the pulling force of the thread take-up lever on the upper thread, since the thread take-up operation is synchronized with the movable cutter, the time required for the upper thread cutting operation becomes shorter. long, reducing work efficiency

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