Bottom and upper thread shearing structure of sewing machine

Abstract

The invention provides a bottom and upper thread shearing structure of a sewing machine and belongs to the technical field of sewing machines. The technical problem that bottom threads and upper threads obtained through the bottom and upper thread shearing structure of an existing sewing machine are still long and the like is solved. The sewing machine comprises a rack and a needle plate, wherein a knife holder is fixed to the lower plate face of the needle plate, and a guiding through groove is formed in the knife holder. The thread shearing structure comprises a lower thread shearing knife and an upper thread shearing knife, the lower thread shearing knife is arranged in the guiding through groove and is sequentially provided with a lower cutting edge and a thread hooking groove from front end to rear end, a driving source I making the lower thread shearing knife to move along the guiding through groove back and forth is arranged on the rack, the upper thread shearing knife is arranged in the guiding through groove, and a driving source II making the upper thread shearing knife to move along the guiding through groove back and forth is arranged on the rack. The bottom and upper thread shearing structure has the advantages that thread residues of bottom threads and upper threads can be short after thread shearing.

Description

technical field [0001] The invention belongs to the technical field of sewing machines, and relates to a thread trimming structure for bottom threads of a sewing machine. Background technique [0002] The lower thread is set in the hook of the sewing machine, and the fabric is sewn by interlacing with the upper thread. When the last stitch is sewn, the upper thread and the lower thread will be intertwined under the needle plate. The intertwined upper thread and lower thread need to be cut off. The common method is to pull out the intertwined upper thread and lower thread It can be cut off, but this method will make the thread ends of the bottom thread and the upper thread longer, and the thread ends of the bottom thread and the upper thread need to be trimmed, and the operation is more cumbersome and less efficient. [0003] In order to solve the above problems, the Chinese patent literature discloses a simultaneous thread trimming mechanism for the bottom and upper threads...

AI Technical Summary

Problems solved by technology

This patent hooks the bottom thread back through the moving knife and cuts the bottom thread through the cooperation between the moving knife and the fixed knife, which improves the efficiency, but the position of the fixed knife in this patent is fixed, that is, the fixed knife is opposite to the needle. The position of the hole is fixed. In order to ensure normal sewing, the fixed knife must keep a certain distance from the pinhole. The position of the fixed knife is far away from the pinhole, so the displacement of the moving knife is also relatively large, and the pinhole is also far away from the position where the bottom thread is cut. A section that is connected to the fabric so that the lower and upper thread ends are still longer

Images