Patent GB-371686-A (GB)
Title: Improvements in and relating to thread trimmer and holder for buttonhole sewing machines
IPC: D05B65/00
Filed: 1931-07-01
Abstract: 371,686. Sewing-machines. HUGHES, R. M., 72, Cannon Street, London.-(International Button Hole Sewing Machine Co. ; 502, Harrison Avenue, Boston, U.S.A.) July 1, 1931, No. 19001. [Class 112.] Thread - cutters and thread end holders.- The under thread in a buttonhole sewing- machine is held by a thread-gripping device situated beneath the work clamp-plate and actuated by the initial movement of a sliding member on the sewing-machine frame, and is severed by a cutter situated above the clampplate but beneath the work and actuated by the continued movement of the sliding member. In one form, shown in Figs. 1 and 3 applied to a buttonhole sewing-machine, having a work-feeding clamp 46 moving back and forth on an arm 2 of the machine frame, the forward movement of the clamp 46 at the beginning of a buttonhole is caused, by an abutment 47 thereon, to trip a thrust-bar 48 connected at one end to a pivoted arm 55 and at the other to one end of a lever 50, the other end of which carries a pin 52, Fig. 3, which engages a cam face 53 on a rearward extension of one of a pair of thread-gripping jaws 32, 33, to open the jaws and release the thread. The jaws 32, 33 are held open during sewing and are closed, when the buttonhole is completed, by a return-spring 54 on the thrust-bar 48, the abutment 47 having by then been carried back off the end of the rod 48. The jaw 32 is carried on an arm 35 on a plate 36 secured adjacent to a slide member 20, and the jaw 33 is pivoted at 41 to the jaw 32 and is held closed by a spring 42. A finger 19 extending from the slide 20 engages a depending pin 18 on a block 16 supported from a block 12, Fig. 2, below the work-plate 3. The block 12 has pivoted thereto a thread-cutter 9 of known construction, which is moved, by a pin 14 thereon engaging an inclined slot 15 in the plate 3, to carry the thread across the sewing opening 8 in the work-plate. The slide 20 is movable longitudinally of the buttonhole slit on completion of the buttonhole, by a cam device 21 of known construction which is normally idle during sewing and which actuates an arm 22 the lower end of which engages a slot in the rear end of the slide 20. The slide is returned to normal position, shown in Fig. 3, by a spring 30, and an arm 31 engages the pin 18 to return the cutter to normal position. When the buttonhole is completed, the slide 20 is moved upwards from the position shown in Fig. 3, to carry, in its initial movement, the jaws 32, 33 beneath the sewing opening 8, to engage the under thread between the curved edges of the jaws, the jaw 33 swinging backwards to allow the thread to find lodgment in a notch 45 in the jaw 32. Continued movement of the slide 20 after the thread is engaged brings the arm 19 into contact with the pin 18 to actuate the cutter 9 and sever the under thread between the work and the gripper. In a modified form shown in Fig. 7, the gripping jaws 57, 58 are situated on the opposite side of the sewing opening to that shown in Figs. 1, 2, and 3, the jaw 58 being pivoted to the jaw 57 at 59, and the jaw 57 being slidable on the work-plate 3. The operative movements are obtained from the slide 20 with an amount of lost motion as before between the threadgripping and cutting operations. The jaws are carried forward by the slide to engage the thread in a notch and the jaw 58 is then swung open by a latch member 73 against a spring 72 to permit the thread to enter. The jaw 58 is then released to grip the thread, the latch 73 being formed for this purpose with a lug 78 which is engaged by a pin 70 actuated by a lever 65 during continued movement of the slide 20. Return movement of the slide engages a pin 68 thereon in a notch 67, to restore the lever 65 to initial position and release the thread.