Patent GB-723843-A (GB)
Title: Improvements in or relating to punching machines
IPC: C14B5/00
Filed: 1953-11-11
Abstract: 723,843. Punching-machines. BRITISH UNITED SHOE MACHINERY CO., Ltd., BOOT, H. W., and SIMMS, E. H. Nov. 11, 1953 [Nov. 11, 1952], No. 28331/52. Class 31 (2). [Also in Groups XIX and XXIV] A power-driven machine for punching a row of holes in a strap comprises means for automatically stopping the machine after a predetermined number of holes have been punched. A shaft 14, Fig. 2, is adapted to be rotated, to cause the strap to be punched once for each revolution of the shaft, from a continuouslydriven pulley 140 through the intermediary of a spring-urged rotary clutch 142. The shaft 14 has fixed at one end thereof a cam 32 having a cam groove 34 in which ride three cam rollers 36, 58 and 139, Fig. 1. The cam roller 36 imparts a vertical reciprocating movement to a vertically.adjustable hollow punching die 30 to punch holes in the work. The die co-operates with an anvil formed at the upper end of an adjustable bolt 74, Fig. 1. The work is guided between a pair of members 98, 106, Fig. 2, which are jointly adjustable towards or away from each other by being mounted on screwthreads 92, 94 of opposite hand provided on a rotatable rod 80. Material punched from the work passes up through the die and falls into a shoot 31. The work is stripped from the punching die by means of a vertically-adjustable member 124. The cam roller 58 causes the punching die to swing, while in a hole it has punched in the work, to feed the work rearwardly one step; the punching die is then withdrawn from the work and returns to its former position above the work. The amount by which the punching die is swung and hence the distance between adjacent holes is adjustable by changing the position of a member 64, Fig. 1, in a slot 62, the position being indicated by a graduated scale 70. The cam roller 139 brings a plunger 137, Fig. 5, into action between feed steps to compress a spring 131 and thus increase the pressure on a member 116 which presses continuously on the work through a portion 117, the pressure on the member 116 during feed steps are described with reference to Fig. 11 (not shown). The clutch 142 has a cam groove 160 which is adapted to be engaged by a cam roller 158, Fig. 3, carried by a rockable bell-crank lever 152. This lever is operatively connected to a treadle by means of a bar 168 and is rocked, by depressing the treadle, into its inoperative position, against the action of a spring 162, to start the machine. As the lever 152 rocks, a face 312, Fig. 7, thereof is raised to allow a lever 318, 320 to rock anticlockwise and two co-operating spring-urged pawls 208, 210 to engage a ratchet-wheel 204. The lever 152 is held in its inoperative position by means of a spring-pressed pin 176, Fig. 6, carried by the lever being received in one end of a bore 184 passing through the frame of the machine. The pawls 208, 210 rotate the ratchet-wheel 204 in a clockwise direction in timed relation to the revolutions of the shaft 14. After part of a revolution of the ratchet-wheel, corresponding to the number of holes to be punched, a lug 206, Fig. 7, on the rear thereof presses on a reduced portion 190 of a plunger 192 in the bore 184 to push the pin 176 out of the other end of the bore to release the lever 152 from its inoperative position. At the same time, a lug 282, Fig. 7, on the front of the ratchet-wheel rocks a pivotally-mounted lever 292 to push the bar 168 connected to the treadle out of the way of the lever 152 whereupon the latter rocks under the action of the spring 162 to place the cam roller 158 in the cam groove 160 of the clutch 142 to stop the machine. As the lever 152 rocks into its operative position, it bears on a screw 314, Fig. 7, to cause the lever 318, 320 to rock clockwise and the pawls 208, 210 to be successively disengaged from the ratchet-wheel 204, which automatically returns to its initial position under the action of a spring 248. The number of holes punched in the strap is determined by the initial position of the ratchetwheel which can be varied by varying the position of an abutment face 284, Fig. 2, on a member 250, against which the lug 282 comes into engagement as the ratchet-wheel returns to its initial position. The predetermined number of holes for which the machine is set is indicated by a pointer 286, Fig. 2, moving over a fixed dial. Latch mechanism is described for moving the clutch 142 into a neutral position to enable the shaft 14 to be turned by hand while the pulley 140 is still driven. The machine may be provided with mechanism to enable it to be used, if desired, for punching holes without stopping automatically after punching a predetermined number of holes. Specifications 10487/02, [Class 31], and 716,798, [Group XXIV], are referred to.