Patent GB-904613-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B57/14
Filed: 1957-11-26
Abstract: 904,613. Sewing-machines. BRITISH UNITED SHOE MACHINERY CO. Ltd. (United Shoe Machinery Corporation). Nov. 25, 1958 [Nov. 26, 1957], No. 36770/57. Class 112. In a shoe-sole sewing-machine comprising a straight hooked needle, a shoe-entering horn provided with a needle-threading whirl, and a rotary shuttle, the needle may be disconnected from its driving means and stopped at one end of its stroke, when the shuttle is also disconnected from the driving means but is free to continue its rotation after movement of the needle has been stopped. The needle is stopped in its uppermost position, and the shuttle disengages the loop of thread therefrom and sets the previously-formed stitch. The thread take-up also continues to operate and draws the loop of needle thread from the shuttle relatively close to the upper surface of a workpiece on the horn into a position in which both the needle and the shuttle threads may be severed close to the work. Starting and stopping.-A treadle 76 is connected by a rod 74 to a lever 72 pivoted at 66, and is biased upwardly by springs 94 and 196. Downward movement of the treadle serves to connect a motor 78 via a clutch 80 with a vertical shaft 88 provided at its upper end with a gear 90 which meshes with a gear 184 to drive a hand wheel 188. On release of the treadle a brake block 192 carried by lever 72 engages a flange 190 on the hand wheel to stop-shaft 88. Stitch-forming; disconnecting needle-drive ; threads, controlling.-A gear 92, meshing with gear 90, drives a shaft 8 provided with a crankpin 44 which engages a cam slot 42 in a lever 40 to oscillate the latter about a pivot 38. A lever 36, also pivoted at 38, is connected by a link 34 to a block 33 fixed to the needle bar 32 carrying a hooked needle 6. A latch 46, pivoted at 48 to lever 36, is biased by spring means on pivot 48 to engage its lower hooked end with a pin 50 on lever 40 for coupling the latter to lever 36 while the starting treadle 76 remains depressed. A locking-lever 54, pivoted at 56, is formed with an inverted L-shape slot 52 engaged with the pivot pin 48. An arm 60, rigid with lever 54, is connected by a link 62 to a lever 64 pivoted at 66. When the treadle 76 moves to the raised position, a block on lever 72 by engaging a finger on lever 64 turns the latter clockwise, whereby the locking lever 54 is turned anticlockwise. A pin 58 on lever 54 thus swings latch 46 to disengage the latter from pin 50, and pivot 48 is carried into the upper horizontal arm of slot 52 to lock the disconnected needle bar in its raised position. When pedal 76 is depressed, a spring associated with pivot 66 rocks lever 54 clockwise, whereby latch 46 &c. engages pin 50, and pivot 48 oscillates in the vertical arm of slot 52. The shuttle 7, which contains a thread case 28, is included at an angle to position the beak 29 adjacent the needle in the loop-seizing position. A shuttle driver 31, fixed to a shaft 110, extends through a slot 30 in the shuttle and drives the shuttle continuously in one direction. A rounded forward extension of the shuttle driver is adapted to engage the shuttle thread 14 and by imparting a bend to the latter, as at 116, both keeps the latter from contact with the beak 29 and also withdraws an additional length of thread from the case to assist in stitch formation. Shaft 110 is connected by a universal coupling 108 to a shaft 106 which is journalled in the boss of a gear 98 and carries a slidable collar 104 formed with a radial ridge which engages a radial groove in a collar 100 fixed to said boss, a spring 112 biasing the ridge and groove together. Gearing is driven by a gear 96 on shaft 88. The arrangement provides a yieldable connection which may slip if rotation of the shuttle is prevented. The needle thread is taken from a cop in a holder 124 via a tensioner 118 and a thread lock comprising a shoe 127 moved periodically against a plate 138, through a wax pot 126 to a take-up 120 and thence to the needle-threading whirl 4 in a rotary horn 2. When treadle 76 is released for stopping the machine, the needle 6 is locked in its raised position with a thread loop engaged therewith, but as the other parts continue to rotate under their momentum, said loop is opened by the spreader 117 to receive the shuttle beak 29, whereby the previously-formed stitch 12 is set. Finally the take-up draws the needle thread loop from the shuttle close to the surface of the work, when both needle and shuttle threads may be cut by hand simultaneously close to said surface. The thread lock is carried by a bracket 132 fixed to the cover 134 of the wax pot. The stationary plate 138 is fixed to said bracket and the shoe 127 is carried by one arm of a lever 128 carried by a spindle pivoted in a bearing 130 on said bracket. The shoe 127 is biased against plate 138 by a spring 158 acting on another arm of lever 128, and is moved away by an arm 140 which is fixed to the pivot of lever 128 andcarries a roller 142 co-operating with a camplate 144 on a gear 146 carried by a shaft 148 driven by gears 150, 152 from shaft 88. A crank-pin 154 on gear 146 operates the take-up 120. During normal sewing operations the cam plate 144 allows the thread lock to close before each needle loop is pulled from the shuttle by the take-up. To enable thread to be drawn freely from the horn at the end of a seam, a detent 160 is moved under a lug 159 on an arm of lever 128, when the machine is stopped, to hold the thread lock open. A pivot 162 carries both detent 160 and an arm 166 provided with an eye 167 through which passes a rod 168 pivoted to the treadle 76. When the latter is released, a collar 172 on rod 168 engages eye 167 to tilt the detent under lug 159, the thread lock having previously been opened. Rising of the treadle is retarded by a dashpot 176 to enable the take-up to draw the final loop of needle thread from the take-up. Rotary horns; thread cutters.-The tip of the horn is formed as a frame portion 198 provided with the bearing for the whirl 4, and accommodating a cap 200 having a needle-receiving aperture 202. A shank portion of the cap fits in a recess 206 in the frame 198 and is secured therein by a screw 204. The shank, where it emerges from the recess, is formed with an undercut shoulder 208 engaging a corresponding shoulder in the frame 198. A thread-end trimming knife of L-shaped form has a base 214 secured between said shank and the frame 198, while the blade 210 lies between the sides of said shank and recess. The cutting edge 212 of the blade lies within a recess 216 in the side of the cap opposite the shoulder 208. The thread end 218, withdrawn from the whirl at the beginning of a seam, is held in the operator's hand, and, as the seam progresses, is carried into the recess 216 and against the edge 212 to be severed close to the first stitch after the formation of two or three stitches 220. Specifications 285,487 and 347,269 are referred to.