Patent GB-128432-A (GB)
Title: Improvements in Punching Machines.
Inventor: BENNIE HUGH OSBOURNE
IPC: B21D28/04
Filed: 1918-12-30
Abstract: 128,432. Bennie, H. O. Dec. 30, 1918. Punching; punches.-In a metal-punching machine of the type in which the punching head is capable of being disengaged from the moving arm or eccentric by which it is operated, and in which the head, when disengaged, is counterbalanced so that it may rest at any required height above the die; the punch itself is also independently balanced by a spring or countershaft &c., so that the punch may be raised from the work with the slightest effort and movement of the work effected without any appreciable resistance from the pressure of the punch. The punch 1, Fig. 4, is' attached to a plunger 2 having a flange at its upper end so that the weight of the punch may be taken by the spring 5, and a small vertical movement is allowed the plunger so that slightly bent or twisted plates may be adjusted to the required position without any appreciable resistance. In the form shown in Fig. 1, the punching head 4 is operated by a moving arm 17, the downward stroke being effected through a counterweighted tumbler 41, pivoted on the arm 17 at 39 and moved into position above the head 4 by a wiper 38, rod 40, and two wipers 36, 37 which are pivoted at 34 and operated by a treadle 47 through a wire cord 44. The upstroke is effected by stepped links 16 carried on the spindle 39, which engage underneath the cotter 18 on the punching head 4. The links 16 are connected by rods 25 to a quadrant 23 and to a wiper 24 keyed to opposite ends of the spindle 22, and are held back against the action of a spring 29 by a stepped wiper 33 which engages a pin 35 on the quadrant. The wiper 33 is keyed to the spindle 34, and is released from the pin on pressing the treadle, so that, during the downstroke of the arm 17 the links are pressed forward by the spring underneath the cotter. The treadle is released when a hole is punched in the plate 19, and the counterweight 43 moves the tumbler 41 and wiper 33 to the position shown. The head 4 is raised by the links 16 until the bracket 27 on the arm 17 engages the nut 28 on a rod 26 pivoted to the quadrant, whereupon the quadrant is pressed back against the action of its spring and is held in position by the stepped wiper 33. The head 4 is thus freed from the driving mechanism, and is held in the desired position by a spring 7 connected thereto by a bell-crank lever 8. The strength of the spring may be adjusted by nuts 13 on the eye bolts 12 to vary the position of the head 4. The plate 19 may now be moved under the punch to place it in position for punching the next hole. The head 4 may be in a position such that the lower end of the punch just touches the work, the punch being made with a slight conical point to engage centrepunch indentations in the work to ensure accurate punching. In order to lift the punch without putting the tumbler into action, the treadle 47 may be depressed a short distance so as to release the pin 35 from the wiper 33. The gear for disconnecting the head from the moving arm may be operated by clutch and cam mechanism from the main shaft 48, Fig. 6. In this form the treadle is carried by a counterweighted spindle 64, on which are mounted the wipers 63, 74. The wiper 74 is connected by a rod 73 to a lever 72 which engages a cam 51 on the clutch sleeve 49 so as positively to return the treadle to its normal position should the operator forget to release it. the wiper 63 is connected by a rod 62 to a plunger 61 which in its raised position engages a scroll 59 on the clutch sleeve so as to disengage the clutch 53 during the upward stroke of the arm 17. The clutch is put into engagement, when the plunger is withdrawn on pressing the treadle, by a lever 68 controlled by a spring 66. The clutch sleeve has a cam surface 50 which engages a lever 54 connected by a rod 57 to a lever keyed to the spindle 34, Fig. 1, so as to operate the tumbler and the wiper 33, as shown in Fig. 1. In this form the lifting mechanism cannot be put into operation without the tumbler. In a third form, the quadrant 23, stepped wiper 33, and rod 26 are omitted, the spring for pressing forward the links 16 being mounted at one end on swivelling eyed rods attached to the links and at the other end acting against swivelling blocks on a lever keyed on the spindle 34, the locking mechanism being thus dispensed with. The treadle lever may be replaced by a hand-lever in all forms.