GB416346A - Improvements in and relating to buttonhole sewing machines - Google Patents

Abstract

416,346. Sewing-machines. HUGHES, R. M., 72, Cannon Street, London.-(International Button Hole Sewing Machine Co.; 502, Harrison Avenue, Boston, U.S.A.) May 28, 1934, No. 15804. [Class 112.] In a buttonhole sewing- machine in which the stitch-forming and workholding means have different relative positions during the sewing and cutting of the buttonhole slot, these means occupy still another relative position, between the two previously mentioned ones, when the machine is brought to rest, such final position ensuring that the work is not snagged on the needle during removal. When the stitching on the buttonhole is completed, the positions of the stitch frame 1 gives the needle a position indicated by the dotted line b of Fig. 1. The shift of the stitch frame from stitching position to buttonhole cutting position will carry the needle from the dotted line relative position b to the dotted line position a. In usual machines of this kind, the stitch frame then moves to give the needle the relative position g for the stopping position so that the needle is in advance of the work clamps 2, the removal of the work 4 from the opened clamps then requiring care to prevent snagging on the needle. In the present invention, instead of moving from g to a on stopping, the needle stitch frame is started on its return journey and the needle 6 assumes as the stopping position, the position shown in full lines. This movement is obtained partly through the shape of the cam groove 14 in the main cam 12 which operates the stitch frame, and partly through a clutch-disengaging cam carried by the clutch controlling lever 22. The clutch-disengaging cam disconnects a pulley 19 from the shaft 18 at the proper time in the reverse journey from the buttonhole cutting position towards stitching position and comprises a cam 44 with a limited movement between shoulders 46, 47 and a stop pin 48.