Device for changing needle rod range of sewing machine

Abstract

The utility model relates to a sewing machine needle bar stroke changing device which can change the needle bar stroke correctly and surely. The device is provided with a needle bar crank installed on the upper shaft, a connecting rod rotatably pivoted in the middle of the needle bar, and an eccentric embedded shaft on the left and right, which are respectively connected to the needle bar crank and the connecting rod. The eccentric pin changes the aforementioned needle bar stroke by changing the embedded state of the aforementioned needle bar crank and the aforementioned eccentric pin, and at least At the same time as a recess, a protrusion is provided on the hole of the aforementioned needle bar crank used to embed the eccentric pin. When changing the stroke of the needle bar, the eccentric pin slides axially from the needle bar crank and rotates 180°. Refit the recess and the protrusion of the needle bar crank.

Description

technical field [0001] The invention relates to a device for changing the stroke of a needle bar which is linked with the upper shaft of a sewing machine and moves up and down. Background technique [0002] As disclosed in Japanese Patent Publication No. 63-57078, this sewing machine is provided with a needle bar crank mounted on an upper shaft, and a connecting rod rotatably pivoted at the middle of the needle bar, both of which are connected by an eccentric pin. The eccentric pins have their own eccentric embedded shafts on the left and right. One side of the left and right embedded shafts is inserted into the needle bar crank, and the other side is inserted into the connecting rod. The needle bar crank has a set screw for fixing the eccentric pin. The procedure for changing the needle bar stroke is as follows. Firstly, loosen the positioning screw of the needle bar crank, and secondly, rotate the eccentric pin relative to the needle bar crank in the circumferential dir...

AI Technical Summary

Problems solved by technology

[0003] However, if the existing sewing machine changes the stroke of the needle bar in this way, it cannot be seen visually, so the relative rotation of the eccentric pin cannot be made correctly, so that the eccentric pin is screwed to the needle bar in a state where the relative rotational position of the eccentric pin has been shifted. problem on the crank

Also, there is a problem that the eccentric pin is screw-fixed to the needle bar crank at a position different from the desired relative rotation position due to an error in the relative rotation.

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