Patent GB-191214682-A (GB)
Title: Improvements in Work-holders for Buttonhole Sewing Machines.
Inventor: FAIRWEATHER WALLACE
IPC: D05B3/06
Filed: 1912-06-24
Granted: 1913-06-12
Abstract: 14,682. Fairweather, W., [Singer Manufacturing Co.]. June 24. Button - hole sewing - machines. - The workclamp table comprises a U-shaped plate 35, the arms 34 of which slidingly engage the outer undercut edges of upstanding ribs on the worktable, and a plate 39 mounted for transverse movement over the plate 35 by means of a spindle 37 and guide-lips 40. The plates 35, 39. respectively, are reciprocated by means of levers 193, 197 operated by the feed-cam 178. Upon the plate 39 two plates 45, 46 are detachably mounted, their pivot-pins being held in place by a plate 50 hinged to a plate 39 and locked in position by a screw 52. The two plates 45, 46 are drawn together by springs 56 secured to them by detachable snap-plates 54 and are serrated at 48 to form the lower members of a pair of clamping-jaws. The upper members 68, are adjustably secured to pivot blocks, which are carried in brackets 63 adjustably secured upon the plates 45, 46. In each clamp, the upper member is forced downwards against the spring 77 by means of a cam on a shaft 70, the slope of which is so light that no other means is required to hold the clamp closed. The shaft 70 also carries a finger-lever 91, a clamp-closing lever 78, a clamp-opening lever 73, and, on one clamp, a lever 86 which engages with a corresponding lever on the other clamp to ensure simultaneous operation. The clamp is closed by means of the buttonhole-cutting gear. The cutter mechanism, which is described in Specification 9459/12, comprises upper and lower cutting-members carried by levers 21, 22 pivoted upon a sliding carriage 20, which is moved into and out of operative position by means of a pitman 30 and a cam 28 on the transverse cutter shaft 8. The rear of the lower lever 22 rests upon an inactive cylindrical sleeve 25 and the rear of the upper lever 21 is engaged by a cam 26. A lever 84 is pivoted upon the lever 22 at 80 of the pin-and-slot connexion 82 with the lever 21. When the levers 21, 22 are moved forward, the lever 84 presses upon a cam edge of the clamp-closing lever 78 and depresses it, thereby partly closing the clamp. In this movement, the end of the lever 84 passes over the corner 79 of the lever 78, and when the lever 21 is subsequently operated to cut the buttonhole, the lever 84 is rotated by means of its pin-andslot connexion 82, and completes the closing of the clamp. The withdrawal of the buttonholecutting levers occasions the forward movement of a pivoted cam-lock 130, Fig. 11, the shank 133 being in gear with a pinion which also gears with a rack upon the carriage supporting the cutting-levers. The end of the cam-block engages with a finger 124 and rotates it until a second finger 125 integral with it slips into a notch 141 in a detent lever 144. The fingers 124, 125 are integral with a cam-button 121, Fig. 2, which lies between steel plates 120 on the undersides of the clamp-plates 45, 46, and, being rotated with the fingers, forces the clampplates apart and so spreads the buttonhole. At the close of the buttonholing operation, a thread-cutting finger 161 is operated by a cam 171 geared to rotate uniformly with the feedcam, and the bar 164 which communicates the motion to the thread-cutter also engages the arm 144, Fig. 11, and in removing the detent 141 from the finger 125 permits a spring to return the clamp-spreading cam-button 121. The clamps are opened by a finger 95 which engages with the clamp-opening lever 73. The finger 95 is secured to a rod 96 connected to a lever which is operated by the plunger-block of the usual stop-gear, when the latter enters the stop notch in the stopping-cam. The feed-cam is fed normally step-by-step by a silent ratchet, but, as described in Specification 9458/12, the feed-cam is subsequently operated by a pawl 201 at a higher speed to bring the operative part of the thread-cutter cam 171 into action. The stitch-forming mechanism used is described in Specification 9460/12.