Patent GB-146587-A (GB)
Title: Buttonhole sewing machine
IPC: D05B3/08
Filed: 1919-04-05
Abstract: 146,587. Fairweather, W., (Singer Manufacturing Co.). April 5, 1919. Button-hole sewing-machines; starting and stopping gear.-An independently-driven singlerevolution auxiliary shaft is used to cause the closing of the work clamp, the cutting of the button-hole and the spreading of the clamp before the stitching and a second such auxiliary shaft is used to cause, after the completion of the stitching, the cutting and nipping of the thread, the opening of the work clamp and the completion in one sweep of the revolution of the feed-wheel. The cycle of operations is initiated by the manual tripping into action of the buttonhole-cutting shaft 38. Towards the end of its single revolution, this shaft by means of a cam 90 depresses an arm 88. The action of the stoplever 85, being thereby removed, the stitching commences and continues until a pin 91 on the feed-wheel forces laterally a lever 92 which removes a detaining-latch 87<1> from the stop-gear and permits the stop-lever to become operative again. The movements of the stop-gear close the single-revolution clutch of a shaft 100. A crank 152, Figs. 2 and 5, on this shaft is coupled by a pitman 130 and a universal joint 132, 134 to a lever 136 carrying a pawl 139. In the completion of the stitching operation, the movement of the feed-wheel has brought one of a few teeth 141 into engagement with the pawl 139, and in the movement of the lever 136 the feed wheel is carried in one sweep through, the remainder of a revolution and into its initial position. By means of a cam 153 on the shaft 100, the other actions incidental to the completion of the' cycle are effected. A plate 154 is pivoted to a threadtension releasing-lever 155, slidingly pivoted to the hand stopping-lever 163, and is supported at its end 166 on the periphery of the cam 153. At the commencement of a cycle, the end 166 rests as shown in Fig. 11, and the inward movement of the upper end of the stop-lever 85 pushes the end over the edge 188, thereby reinstating the thread tensions at the commencement of stitching. In the revolution of the shaft 100 the cam portions 182, 183, 185 successively raise the plate 154 and thereby effect the release of the thread tension, the tripping of the thread-cutter and the tripping of the work-clamp opening device. The clutch operating the shaft 100 comprises a continuously rotating wheel 103, Figs. 2 and 9, having six inwardly projecting teeth 105 and a driven disk 109 having a sliding block 111, Figs. 5 and 8, spring-pressed outwards to engage with the teeth 105. The block 111 is normally held away from the teeth 105 by means of a stopblock 118<x> carried by a lever 117, and is released when the lever is moved anti-clockwise from the position shown in Fig. 2. In the stopping of the main-shaft, the usual stop-block 94, Fig. 8, rides up on the cam 95, the further end of the lever 143 is depressed, and a latch 145 slips under an arm 123 of the lever 117. When the block 94 drops into the positive stopping notch 98, the latch 145 rises with the lever 143 and the lever 117 is turned away from the disk 109. The block 111 is thereby released, moves outwards into engagement with one of the teeth 105, and the shaft commences its revolution. In the course of the revolution one rib of the crank 152 hits a plate 151 on a trip lever 147, removes the latch 145, and permits the lever 117 to move into position in readiness to engage the block 111 at the completion of its first revolution, and to withdraw it from engagement with the teeth 105. The work-clamp is described in Specification 141,888. It is locked in the clamping position by a latch lever 52. When the plate 154 is raised by the cam 153, it depresses a lever 176 into contact with a lever 172, and that lever is then used to lift the latch lever 52. The threadcutting and nipping blades are carried bv a lever 69, Fig. 1, and operates between slightly resilient tongues on the work-clamp. The operating rod 71 is normally held by a latch lever 78, and when the latter is tripped by means of the lever 172, a spring 75 actuates the parts to cut and nip the thread. The rod 71 can be pushed forwardly to release the thread at the commencement of stitching either by hand or by a lever 79 actuated, on the first revolution of the upper stitching shaft 11, by means of a switch-cam 84.