Patent GB-151203-A (GB)
Title: Improvements in and relating to sewing machines
IPC: D05B65/00
Filed: 1920-02-09
Abstract: 151,203. Imrie, H., (Reece Button Hole Machine Co.). Feb. 9, 1920. Button - hole sewing- machines; loop-stitching; stopping and starting gear; thread-cutters and thread-end holders.-In a button-hole sewing- machine having an upper and an under thread and means for severing the threads beneath the work at the completion of sewing and adapted to come to rest with the upper needle clear of the work, the looper operating below the work is retarded in the last stitch-forming cycle to prevent its engagement with the upper thread loop, whereby that loop is pulled up through the work and its severing is avoided. The work W is held between the clamp 3 and the plate 1 and is moved from button-hole cutting to sewing position and back and during sewing by a cam 19, which also rotates the upper and under thread handling mechanisms to sew round the ends of the button-hole. The sewing-shaft 24 carrying fast and loose pulleys is automatically thrown into operation when the work reaches sewing position and is stopped at the completion of sewing by a stop cam 43 and a member 44 carried by an axially sliding rod 42 operated by the cam 19. The loop of thread carried through the work and loop of under thread by the eyed needle 5 is retained beneath the work by the looper 10, Fig. 6, mounted in the rotary turret 8, while a loop of under thread is passed through the upper loop by the needle 9, said looper and needle being oscillated by a rod 20 reciprocated by a cam on the shaft 24 through the link 23 and lever 21. The thread-severing devices comprise a block 57 and knife 530, Fig. 3, carried by levers 51, 52 respectively, carried by a plate 55 secured to the movable work plate 1, and normally held open by a spring 54. Toggle links 61 engage the levers and are straightened to sever the threads by a lever 63 also carried by the plate 1, the end 66 of which lever contacts with the shoulder 69 of a fixed plate 68 when the plate 1 returns to buttonhole cutting position. A thread-end holding device comprises an arm 27 carried by a rockshaft 29 mounted in the turret 8. A second arm 32 of the shaft 29 engages a stationary dog 33, normally held by a spring 35 against a stop 37, as the turret turns clockwise during the return of the work to button-hole cutting position, whereby the arm 27 is swung to the left, its hooked end 28 engaging and holding the thread ends beneath the throat slate 13. The lever 21 is pivoted on a pin 22 having eccentric ends 80 one of which carries an arm 81 connected bv a link 82 to a lever 83 having an extension 86. The stop member 44 carries a projection 87 which overlies the extension 86 and contacts therewith as the member 44 is depressed during the braking action of the cam 43 while the shaft 24 is being .stopped. By this means the pivot of the lever 21 is shifted during the last stitching cycle and the motion of the looper is so retarded as to prevent the looper from engaging the upper needle loop, with the result that the under thread and stay cord only are cut by the severing devices. A spring 100 returns lever 21 to position for operating the looper normally when the member 44 is shifted to commence serving.