Sewing machine thread trimming device and sewing machine

Abstract

The invention provides a sewing machine thread trimming device, comprising a lower shaft, a thread trimming cam fixed on the lower shaft, a moving cutter assembly which can swing around the lower shaft, a thread trimming driving shaft, a thread trimming power source, and a thread trimming driving crank and a thread trimming crank fixed on the thread trimming driving shaft, and a driving assembly. The moving cutter assembly comprises at least a moving cutter. The outer peripheral surface of the thread trimming cam is provided with a thread trimming driving cam surface. The thread trimming driving crank is provided with a crank arm. A movable roller pin shaft passes through the crank arm. The roller pin shaft is provided with a roller. When the device trims a thread, the thread trimming power source drives the roller pin shaft to move, so the roller moves to the direction close to the thread trimming cam and cooperates with the thread trimming driving cam surface. The thread trimming crank is connected with the moving cutter assembly through the driving assembly, and drives the moving cutter assembly to swing. The thread trimming driving crank in the device has and only has one crank arm, so the device is simplified in structure, and a transmission chain of the sewing machine thread trimming device is simplified, so as to improve transmission efficiency and transmission reliability and reduce production cost.

Description

technical field [0001] The invention relates to a garment sewing device, in particular to a sewing machine thread cutting device and a sewing machine. Background technique [0002] At present, sewing machines (especially lockstitch machines) are equipped with an automatic thread trimming mechanism, which is used to cut off the bottom thread and the upper thread at the rotary hook after each sewing. Such as figure 1 As shown, the automatic thread trimming mechanism in the existing sewing machine generally includes a rotatable lower shaft 100, a cam 200 fixed on the lower shaft 100, a thread trimmer shaft 300 parallel to the lower shaft 100, a swingable thread trimmer crank assembly 400, The disc 500 positioned at one end of the thread-cutting shaft 300, the thread-cutting crank 600 fixed at the other end of the thread-cutting shaft 300, the thread-cutting connecting rod 700, the moving knife rest 800, the moving knife 900 fixed on the moving knife rest 800, and the fixed Th...

AI Technical Summary

Problems solved by technology

Therefore, in the above-mentioned automatic thread trimming mechanism of the sewing machine, the thread trimming crank assembly includes three extension arms, the structure is very complicated, and it cooperates with the thread trimming shaft through a sliding pair, which makes the overall structure of the automatic

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