GB372591A - Thread-cutter operating mechanism for sewing machines - Google Patents

Abstract

372,591. Button-hole sewing-machines. FAIRWEATHER, W., 65, Chancery Lane, London.-(Singer Manufacturing Co. ; Elizabeth, New Jersey, U.S.A.) June 16, 1931, No. 17439. [Class 112.] The thread-cutter, tension device, and work clamp of a button-hole sewing-machine are operated from a shaft 28 which is rocked by the recovery motion of a buffer device described in Specification 309,771. The impulse is imparted to the shaft by a hooked lever 67 which on the recovery motion engages with shoulders 74 of a cam 69 adjustably secured to a gear 47, containing the buffer springs. The lever 67 is held out of engagement until the recovery motion by a stud 76 secured to the stop-motion lever 57. Thread cutters.-The cutter is pivoted to the work clamp and is connected by a link 23 to a sliding rod 24. When sewing down the return side of the buttonhole, the rod 24 encounters a, latch arm 27 and its motion is arrested while the continued motion of the work clamp opens the thread cutter. When sewing is completed the thread cutter, which is held open by the latch arm 27, is released by the actuation of the rock shaft 28. Tension devices.-The tension release rock shaft 31 is rocked from the shaft 28 by a bent arm 29 and link 30, and an arm 32 is arranged close to the tension discs 33 so that the tension device is opened before the cutter is released. Work clamps.-The work clamp 19 is operated from the shaft 28 by a bell-crank lever 34, 35 and a rod 39 which carries the work clamp lifting roller 41. On the rocking of the shaft 28, the roller 41 depresses the tail 18<1> of the work-clamp lever 18 and raises the clamp foot 19. The bell-crank lever 34, 35 is locked during sewing by lever 43 which is provided with a lip 44 engaging an arm 45 on the shaft 28. It is unlocked by the same movement of the shaft 28 which releases the thread cutter and opens the tension device.