| 摘要 |
A buttonhole machine has a vertically reciprocal needle, a horizontally displaceable material support plate, a rotary stitch plate below the needle, mechanism for feeding a lower thread up through the stitch plate, clamps for holding material on the material plate at the stitch plate, and a drive for rotating the stitch plate in one rotational sense, simultaneously displacing the material plate, and reciprocating the needle to form a buttonhole in the fabric and for rotating it in an opposite return rotational sense after formation of the buttonhole. Such a machine also feeds an upper thread down through the needle to the stitching location and also normally lays a thick cording thread into the buttonhole to reinforce it. This machine is equipped with a feed arm carried by and jointly rotatable with the stitch plate, engaging the lower thread, and pivotal for freeing a length of the lower thread and feeding same to the stitch plate. A pivotal blade carried by the material plate can coact with a fixed blade on the material plate. The operation of this pivotal blade and arm is controlled by cams at least partially on the stitch plate for pivoting the blade during return rotation of the stitch plate to sever the lower thread and for synchronously pivoting the feed arm to make slack in the lower thread.
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