Patent GB-317693-A (GB)
Title: Buttonhole sewing machine
IPC: D05B73/12
Filed: 1928-11-29
Abstract: 317,693. Fairweather, W., (Singer Manufacturing Co.). Nov. 29, 1928. Buttonhole sewing-machines.-In a buttonhole machine, mechanism is provided to vary the sequence of the stitch-forming and cutting devices and for ensuring the opening of the workclamp subsequent to these operations. The stitch-forming and stopping mechanisms and their controlling means are the same as described in Specifications 179,278, 183,873, 184,134, and 184,135, except that the looper bar 8<1> is reciprocated by a link-connection 8<a> with the lever arm 8<c> fulcrumed on the stud 8<d>. The lever arm 8<c> has a follower 8<e> entering a cam groove 8<f> in the disc 8<g> on the main shaft 9. The period of action of the stitch-forming mechanism is controlled by the usual stop-motion device comprising the lever 10, Fig. 2, with a tooth 13 co-operating with the cam 14 on the main shaft 9. The operation of the stopping lever 10 is controlled by the pattern-cam 17 on the shaft 18, the cam acting on the lever 19. When the shaft 18 turns, the cam 22 of the pattern cam 17 engages the nose 23 on the lever 19 to tilt the lever 10 to start the sewing. When the cut-away shoulder 24 comes opposite the nose 23, the spring 16 is free to restore the lever 10 to stopping position. Work clamp. The work clamp comprises the lower plates 25 and upper feet 26 mounted in the usual manner in the machine bed to carry the work from buttonhole cutting to stitching position, then in a path for placing the stitches around the buttonhole and back to the cutting position. The movements are derived from the usual feed-wheel 27 and pattern wheel 17 through the usual connections such as described in Specification 183,873. During the portion of the work cycle when stitching is being effected, the feedwheel is driven step-by-step from the shaft 9 through the usual pin and star-wheel drive and gearing train 30. During the portions of the cycle preceding and following the sewing period when the work clamp is being carried to and away from sewing position, the feed-wheel is driven continuously at a more rapid speed from the shaft 31. The clamping feet 26 are depressed to grip the work by clock-wise movement of the shaft section 61, Fig. 1, by the roller 62 on the arm 63 of the three-armed lever 63 - - 65, as described in 184,135. Buttonhole cutting mechanism. This mechanism is the same as that described in Specification 183,873 and comprises upper and lower cutter levers 83, 84 pivoted at 85 on the block 86 which slides longitudinally in the machine bed and are operatively connected to the cutter-shaft 87. The cutter-clutch and controlling-lever 88 are the same as described in Specifications 197,463, 197,629, and 198,628. At the close of a cycle of operations, the work-clamp is automatically opened and unspread. The opening is accomplished by a bar 95, Fig. 2, pivoted to the arm 97 of the bell-crank lever 97, 98 on the machine frame. A rocking impulse of the lever projects the front end of the rod 95 into engagement with the arm 100 fixed to the work clamp rock shaft 61 to open the clamp. Previous to this, the tripper 101 on the rod 95 engages the tail 102 of the latch-lever 103 to lock the clamp in closed position. On the forward movement of the rod 95, the arm 105 engages the lever 106 of the clamp-spreading toggle and unspreads the clamp. Buttonhole formation. The control mechanism for varying the sequence of automatic operation to produce (a) the " cut-first" buttonhole or (b) the " cut-after " buttonhole is as follows:-A control lever 117 is pivoted to the machine at 116 and is secured at 118 to the leaf-spring arm 119 slotted at 120 to embrace the screw 121 fixed to the arm 117. The screw 121 limits the outward movement of the arm 119, which is slotted at 122 to engage the pin 123 slidably mounted in the arm 117. The lever 117 is manually moved to either of its operative positions by the operator after withdrawing the pin 123 by manipulation of the spring-arm 119. Fig. 8 shows the " cut-first " position in full lines and the " cutafter " position in dotted lines. When the lever is set for the cut-first type of buttonhole, a push on the starting button 72 trips the clamp closing and spreading device into operation which starts the buttonhole cutting mechanism through the push bar 134. The cutting mechanism operates through the cam tooth 141 and follower 139, Figs. 1 and 8, to start the rapid feed mechanism which acts through the pattern cam 17 to start the stitch-forming and feed mechanisms which are in turn stopped by the shoulder 24. The tooth 13 on the stopping lever 10 causes the rapid-feed mechanism to return the. work clamp to initial position, during which return the tooth 170 raises the lever 171 to open and unspread the work clamp, Fig. 2. When the control lever is set for the " cut-after " buttonhole, a push on the button 72 trips the clamp closing and spreading mechanism into action as before, but the mechanism now operates through the pin 148 to depress the lever 142 and start the rapidfeed mechanism which, as before, starts the stitch-forming and sewing-feed mechanisms. These are stopped by the shoulder 24. The action of the tooth 13 on the stopping lever 10 starts the rapid-feed mechanism to return the work-clamp to initial or cutting position and acts through the tooth 172 on the gear 28 to tilt a lever to start the buttonhole cutting mechanism through a cam 166 to unspread the work-clamp. The machine is provided with a clutch-locking device as described in Specification 201,298 for preventing accidental operation of the cutting mechanism.