Patent GB-134924-A (GB)
IPC: D05B65/00
Abstract: 134,924. Fairweather, W., (Singer Manufacturing Co.). Nov. 13, 1918. Button-hole sewing-machines; starting and stopping-gear; threadcutters and thread-end holders.- Relates to machines for forming detached groups of stitches, as button-hole sewing machines, and consists in providing a plurality of thread cutting and nipping devices which act successively to cut the short end of thread at the beginning of a stitching cycle, and cut the thread and hold the end at the termination of a stitch ng cycle. Means for releasing the thread tension and pulling off a supply of thread for the succeeding stitching operation are also described. The invention is described as applied to a button-hole sewing machine .comprising a movable work-holder, rotary stitch-forming devices, automatic stop-motion, and buttonhole-cutting devices of a usual kind. The rearward upper clamping-foot 37 is formed with an extension 45 provided with recesses in which are mounted the thread-cutting and thread-end holding devices coacting with the walls of the recesses. A combined thread cutting and holding finger 53 is mounted in the upper recess by a stud 50 which carries a crank 57 connected to a rod 60 slidingly mounted in the block 40 carrying the clamping-foot. The rod is actuated by a spring 64 to cause the finger 53 to sever the thread leading from the work to the needle at the end of a sewing operation, and is actuated by a lever 72 to retract the finger. The slide bar 112 which actuates the stitch-forming devices in moving round the eyelet of the button-hole carries a spring latch 118 which engages the lever 72 and retracts the finger 53 at this period of the stitching cycle. At the end of the stitching cycle, the latch 118 is disengaged by a rod 192 depressing the end 120. The rod 192 is connected to a lever 169, to which the movements of the slide block 139 of the stopping-gear are communicated through the link 189, lever 186, and link 172. The link 172 is normally held down by a spring 176 and is connected to the lever 186 by a spring pawl 182 and pin 185 which allows the connexion to be broken in starting the machine and automatically completes it in stopping. The lever 169 carries a cam 168 for releasing the thread tension and may also actuate a pull-off lever 200 to provide a supply of thread for the next stitching operation. In the lower recess in the extension 45 is pivotally mounted a spring-actuated cutting-finger 75, which is held inoperative by a spring-actuated detent 79. The detent is released after the first few stitches of a sewing operation, to allow the finger to sever the short end of thread leading from the holder to the work, by a slide-bar 94 connected to a bell-crank lever 96 with a cam.shaped notch in its end 98 and carried by the block 40. The feed movement of the block 40 causes the end 98 of the bell-crank lever to ride over a cam 105 which is mounted on a horizontally pivoted plate 102 secured to a fixed part of the machine. The return movement of the block causes the end of the lever to swing the cam-plate sideways against a spring 108 and snap into normal position behind the cam. The finger 75 is returned to normal inoperative position by a projection 90 on the crank 57 engaging a pin 89, during the movement of the crank which places the finger 53 in its inoperative position in preparation for its active movement. A current of air is supplied to remove the thread cuttings, from a pump driven by friction from the driving-belt of the cutter shaft. A deflecting-flange 203 is formed on the extension 45 for grinding the cuttings clear of the work. Specification 17998/03 is referred to.