JPS61164684U - - Google Patents

Description

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view, Fig. 2 is a partially omitted plan view of the conventional example, Fig. 3 is a partially omitted side view of the conventional example, and Fig. 4 is an embodiment of the present invention. FIG. 5 is an explanatory diagram of the operation of cutting the bobbin thread in another embodiment. In the figure, 1 is the needle plate, 3, 3 is the lower thread groove, 3a is the blade of the lower thread groove, 3b is the end corner of the lower thread groove, 4, 4 is the knife hole, 5, 5 is the movable knife, 6 is the 6a and 6b are groove walls, 6c is a cutting edge of the groove, and 6d is an end corner of the lower thread groove.

Claims (1)

[Scope of Claim for Utility Model Registration] A throat plate 1 which is arranged horizontally on the sewing machine bed and has a diagonal hole through which a needle that moves up and down passes, and a needle plate extending from the needle hole in the cloth feeding direction on the upper surface of the throat plate to accommodate the bobbin thread. The bobbin thread passes through the bobbin thread groove up and down, keeping a distance from the needle hole, so as to cut the bobbin thread to a length that will form the next stitch in cooperation with the bobbin thread groove 3 and the upper thread. A circular female hole 4, 4 with a blade formed on one side of the end corner of the groove and an end corner of the bobbin thread groove on the front side in the cloth feeding direction, and a circular female hole 4, 4 that rotatably fits into the female hole and has an upper end surface thereof. A concave groove is formed in the lower thread groove, and a blade is provided to shear the lower thread in cooperation with the blade of the lower thread groove. movable knives 5, 5 having end corners of concave grooves for holding the bobbin thread between the movable knives 5, 5, and drive mechanisms 9, 10, 11, 12 connected to the movable knife so as to rotate the movable knife in forward and reverse directions. In the bobbin thread trimming mechanism of the sewing machine, when the movable knife rotates forward, after the bobbin thread is pinched by the end angle of the bobbin thread groove and the concave groove of the movable knife, the blade of the movable knife cuts the bobbin thread groove. The distance between the blade of the movable knife and the blade of the bobbin thread groove is larger than the end angle of the concave groove of the movable knife and the end angle of the bobbin thread groove so that the bobbin thread is cut between the blade of the movable knife and the blade of the bobbin thread groove. The bobbin thread trimming mechanism of the sewing machine is characterized by: