Patent GB-164858-A (GB)
Title: Buttonhole sewing machine
IPC: D05B73/12
Filed: 1920-03-17
Abstract: 164,858. Fairweather, W., (Singer Manufacturing Co.). March 17, 1920. Button-hole sewing-machines.-The movement of the work - clamp is determined by the usual feed-wheel 59 and is the same for all lengths of buttonhole. During stitching, the feed-wheel is rotated step by step by a pin-wheel 107, a special toothed wheel 108, and toothed gearing 111, 112, 121, To move the work from cutting position to stitching position and back again when the stitching is completed, rapid rotary movement is given to the feed-wheel by a continuously-operated pawl 140 which engages with ratchet teeth 130. These teeth and a cam-surface 136, 137, which determine at what points in the feed-wheel cycle the stitching shall start and stop, are carried by an easily removable control disc 129. Interchangeable control discs, Fig. 9, are provided for different lengths of button hole. A one-way ratchet drive is interposed between the gearwheels 112, 121 to permit the rapid movement of the feed-wheel without disconnecting the slow drive parts 107, 108, 112. Interchangeable wheels 121 are provided for different spacings of the stitches and, to accommodate wheels of different diameters, the wheels 112, 121 are carried on an adjustable bracket 114. The lateral movement of the work clamp, necessary when eyed buttonholes are being stitched, is provided by a camlever 70 having a pin 75. For straight buttonholes, the pin 75 can be withdrawn from engagement with the work-clamp plate. The buttonhole is cut after stitching and the cutting can be prevented by means of a hand-lever 330, Fig. 1. Work-clamps, closing, spreading, and opening. -The upper clamping-members 47 are mounted upon coaxial spindles 46 connected so as to rotate together by levers 56, 57 and are closed on to the clamp-plates by cam parts 50 of a lever 181 when the latter is engaged by the lever arm 177 in starting the machine. The cam-plates are pivoted on the plate 35 at 41 and are moved apart to spread the work, after the clamps are closed, by means of toggle-lever 195, 197, Fig. 2, operated by a lever 192 and a latch lever 188 connected to a depending lever arm 178. The lever arms 177, 178 are parts of a three-armed lever and the other arm 176 carries a spring-pressed pin 174 in a socket 175 which is normally held in an inoperative position by a latch-lever 238. When the starting-treadle is depressed, a lever 219 carries the latch-lever, which is pivoted at 240, away from the pin 174, and the latter thereupon enters a cam groove in a continuously rotating belt pulley 171. After a single revolution of the pulley, during which the clamps are closed and spread, the pin 174 is ejected from the cam-groove by a projection 173 and is re-engaged by the latch-lever 238, which for this purpose has been disengaged from the starting-lever 219 by the engagement of the pin 174 with the tail of a latch 237. The work-clamps are opened only after a cutting operation and by means of a cam 347 on the singlerevolution cutter shaft 170 which engages a lever 344 and, by means of a push-rod 339 and a lever arm 338, turns the cams 50 into inoperative positions. At the same time, a cam 213 on the cutter-shaft actuates a slide 212 and, by means of a tappet-lever 209, bends the toggles 195, 197 to permit the work-clamps to move towards one another. The plate 35 supporting the workclamps has depending lugs which slide laterally upon a rod 37 carried by a plate 38. The plate 35 may be moved laterally by the pin 75 on the camlever 70, and the plate 38 is moved longitudinally by a cam-lever 63. Rapid actuation of feed-cam. - The pawl bar 141 is reciprocated continuously by a lever 144 linked to an eccentric strap on the stitching drive pulley 151. The pawl is held out of action during stitching by a bowl 152 which passes under the pawl bar when its lever 154, 155 is free to move inwards. At the commencement of a buttonholing operation the parts are as shown in Fig. 3. A shaft 166 is given one complete oscillation, by means of connections 214, 215 with the lever-arm 176, and on its return and forward movement, the latch 163 on a lever 165 presses upon an inclined surface of an arm on the inner side of the boss 155 and moves the bowl 152 outwards and away from the pawl-bar. The pawl falls into engagement with the feed-wheel and actuates it up to the end of the series of teeth 130 and is then lifted by the inclined surface 133. This actuation effects the movement of the work-clamp from cutting to stitching position and, at an intermediate point, a cam-projection on the clamp removes the latch 163 so that, when the pawl bar is lifted, that bowl 152 slips underneath it. At the completion of the stitching operation when the clutch 262 is disengaged and the stitching parts are stopped, the usual slide block 267, through parts 284, 288, Fig. 1, a cam-edged lever 291, Fig. 3, and a plunger carrying a pin 292, as it rises on the stop-cam, pushes the lever 154 aside and permits the pawl to fall into engagement with the series of ratchet teeth 130 which by the rotation of the feed-wheel has been brought beneath the pawl. When the large tooth 131 is reached the pawl bar is lifted again and the bowl 152 slips underneath it and retains it until another cycle is commenced. Button-holes, cutting.-Interchangeable cutter blocks 318 for different lengths of buttonholes are provided for the upper cutter lever 313, and the lower lever 314 is fitted with a slide carrying two cutters, one for eyed and the other for straight buttonholes. The slide can be fixed so that either cutter is operative. The cutter levers are mounted on a fixed axle, and are actuated from the single-revolution cutter shaft 170, which is put in action when the clutch-controlling lever 312 is turned upon its pivot 311 by a cam-lever 326; the latter being turned upon its pivot 327 by a cam projection 325 on a disc 324 mounted to rotate with the feed-cam. A catch 226 which holds the starting lever 219 in running position is mounted upon a lateral arm of the lever 312, and when the latter is turned to cause the cutting of a buttonhole the catch releases the starting- lever, which then returns to its initial position. A slide 329 in the lever 326 forms the operative end of that lever, and the cutting operation can be prevented by drawing the hand-lever 330 forwardly and so withdrawing the slide 329 out of reach of the lever 312. The lever 330 is linked to a lever 336 so that when the cutting operation is prevented, the lever 335 independently actuates the catch 226 and releases the starting- lever. Stitch-forming devices.-The sleeve carrying the laterally vibrating needle-holder and the turret for the looper parts are turned through half a revolution during stitching and returned afterwards by toothed racks 85, 90. The rack 85 is connected to a sliding-bar 86 which is reciprocated by means of a part 93 of a cam-actuated frame carrying the rack 90. The shaft 5 driving the under-thread loopers makes one revolution for two reciprocations of the needle. The needlethread passes through eyes in the ends of fixed arms 365, Fig. 3, and over the periphery of two adjacent plate-cams 362. The thread is prevented from being drawn round the cams by being passed through a slot in a plate 366 which passes between the cam-discs. The cams are carried by a sleeve shaft 15, which makes one revolution for two reciprocations of the needle. A thread lock 373 is operated by a cam 369 on the sleeve shaft. Needles, vibrating laterally.-The needle-holder 22, Fig. 24, slides upon a cross-bar 22<a> and carries a lever 26, having a pin 25 at its free end which enters the fork of a lever 24 when the needle is at the top of its stroke. A pin 27 is adjustably fixed at some intermediate point in the lever 26 and engages with a fixed slot in the cross-head of the needle-bar. The lever 24 moves the pin 25 from one extreme position to the other, and as the needle-bar reciprocates, the pin 25 moves in the corresponding groove of a pair formed in a stationary part 25<a>. The position of the pin 27 on the lever 26 determines the amplitude of the lateral vibration. Threads, controlling otherwise than in stitchforming.-When the lever 344 is operated by the cam 347 on the cutter-shaft, to open the workclamp, the cam-bowl 345 engages with and lifts a plate 355, which serves to release the needlethread tension device 351. The plate is held in its raised position by means of a lug 360, which engages a recess cut in the base of the lever 165. When the lever 165 is turned at the commencement of a buttonholing operation the plate is released, and in falling reinstates the needle-thread tension. Starting and stopping gear.-The positive stopping device is of a known type, and includes a clutch of the same general character as that described in Specification 18274/07.