Wire shearing device of sewing machine

Abstract

This invention provides a wire shearing device of sewing machine, includes: a suture tension adjusting unit (33) arranged on the upside of the sewing machine body (32) and providing either a tension clamping state or a clamping release state by means of shifting to the position of a clamping facial line (A) and a bottom line (C); a movable blade (35) moves forward and backward under the needle board (34) and shears the facial wire (A) and bottom wire(C); A swing arm (38), of which One end part is freely connected to the sewing machine body by means of angular displacement; a driven wheel (37) is connected between the other end and one end of the swing arm (38); a long hole (39) is formed in the cam part (40) , thereof , the swing arm (38) finishes an angular displacement from one direction to another direction through the displacement of the cam part (40) ; a first connection unit (42) transmits the displacement of the other end of the swing arm (38) to the suture tension adjusting unit (33) and a second connection unit (43) transmits the drive force of drive unit (41) to the movable blade (35) so as to drive it forward or backward.

Description

technical field [0001] The invention relates to a thread trimmer of a sewing machine. Background technique [0002] Fig. 6 is a perspective view showing the structure of a thread cutting device 1 of a conventional sewing machine. This prior art is described in, for example, Japanese Utility Model Registration No. 3136842. The thread trimmer 1 of the sewing machine of the prior art adopts the following structure: one end of the linkage shaft 5 is connected to the piston rod 3 of the pneumatic cylinder 2 through the connecting block 4, and the cam member fixed on the other end of the linkage shaft 5 6Clamp the upper thread and the lower thread on a thread tension adjusting device (not shown in the figure) called the "needle thread holder" to give it the desired tension, and release the clamped state to release the upper thread (needle thread). ) and the lower thread (ル一パコ) tension, and at the same time make the approximately C-shaped movable blade 12 arranged under the needl...

AI Technical Summary

Problems solved by technology

[0010] The thread trimmer 1 of the sewing machine of the above-mentioned prior art owing to adopting the first and the second cam surfaces 6a, 6b formed on the top of the cam member 6 is carried and arranged on the second The driven wheel 20 on one end of the swing arm 19 has a structure in which the connecting rod 23 moves up and down in the directions of the arrows C1 and C2 by moving the cam member 6 in the directions of the arrows A1 and A2. The first and second cam surfaces 6a, 6b are formed on the above-mentioned cam member 6 so that the clamping state of the upper thread and the bottom thread by the above-mentioned suture tension adjusting device can not be released when the movable blade 12 advances in the direction of the arrow B1, and the upper thread and the bottom thread cannot be moved from the upper thread. The moving wheel 20 follows smoothly, and there is a problem that the clamping state of the upper thread and the lower thread by the thread tension adjusting device cannot be released at the most appropriate timing while the movable blade 12 is advancing in the direction of the arrow B1.

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