GB627675A - Improvements in or relating to sewing machine - Google Patents

Abstract

627,675. Buttonhole sewing-machines. INTERNATIONAL BUTTON HOLE SEWING MACHINE CO. Aug. 8, 1947, No. 22012. Convention date, July 11, 1941. [Class 112] In a buttonhole sewing-machine, the buttonhole is cut, the last stitch set and the thread cut during the last revolution of the machine shaft and the actuation of the stitch-setting and thread-cutting plate 75 is dependent upon the proper return of the buttonhole cutter. The stop-lever 34 is fixed on a shaft 35 which, in starting the machine, is moved by a lever 68 towards the left in the plan view, Fig. 2, and is detained by a detent 69 entering a recess 70 in the shaft. In this movement the belt-shifter 33 carries the driving belt 30 on to the fast pulley 31. Before the last stitch is made, the detent 69 is withdrawn, the shaft 35 moves to the right under the pressure of a spring 65 and the stop-lever is returned into the stopping position, bringing a nose 43, Fig. 5, on the stop-lever into the path of the stop-cam 44. The cam-rise b tilts the stop-lever against the pressure of a spring 45 and thereafter the nose falls into the gap c and engages the stopping face d. The nose 43 is part of a rod 41 slidingly mounted in the stop-lever and pressed to the right by a spring 42 which takes the shock of the positive stop. A pin 57 on the stop-lever 34 has a sliding-turning engagement with the buttonhole cutter lever 51 so that the upward tilt of the stop-lever moves the cutter to cut the buttonhole. The return movement of the stop-arm under the pressute of the spring 45.raises the buttonhole cutter clear of the work and brings a lug 84 on the rod 41 into a gap 83 on a link 80 connected to a shaft 78 which actuates the plate 75. The movement of the rod 41 to the left, Fig. 5, in the positive stopping action actuates the plate 75 to set the last stitch and cut the thread. If the buttonhole cutter jambs, the spring 45 will not depress the lever 34 and the lug 84 will not enter the gap 83. The stopping face d is, however, sufficiently long to engage the nose 43 and cause the machine to stop, but the lug 84 will not move the link 80 and the plate 75 will not be actuated. The plate 75 has a blunt part e which engages the needle side of the last thread loop, which is on one of the loopers, to set the stitch and in the further movement of the plate a knife edge f cuts the other side of the loop. U.S.A. Specifications 714,284, 749,776, 1,088,652, 1,402,073 and 1,483,307 are referred to.