GB647163A - Improvements in or relating to presses for use in piercing material, and piercing devices therefor - Google Patents

Abstract

647,163. Punching. REDMAN TOOLS & PRODUCTS, Ltd., FROST, A. F., and REDMAN, A. M. Oct. 17, 1947, Nos. 27897/47 and 17074/48. [Class 83 (iv)] A piercing unit for use in a press comprises a punch, a sleeve surrounding and concentric with the punch and supporting a stripper and a stripping spring surrounding the punch and bearing at its lower end on the stripper and at its upper end on a shoulder of the punch. In one form, Fig. 1, a punch 20 is housed within a tubular member 12 having at its lower end a stripper bush 28 and at its upper end an apertured plate 34 serving to guide the upper end of the punch. The punch is normally held in retracted position by a helical spring 38 bearing on the bush 28 and on a washer 36 secured around a neck 24 in the punch. The housing 12 is mounted in an opening in the upper arm of a U-shaped frame 8 by means of screws or studs 16 so as to be movable axially within the frame. It is normally urged to its upper position by a lighter helical spring 46 bearing between the upper part of the frame and the bottom of a flange 14 at the top of the tubular housing. The punch is in alignment with a die 50 mounted in boss 48 upstanding from the lower arm of the frame 8. A curved passage 54 in the boss serves to discharge the punched-out slugs. The frame 8 is adapted to be accurately positioned on the bed of a press by means of a recess 58 co-operating with a pin on the bed and to be clamped by a bolt passing through an elongated slot 56 in the frame. On the descent of the press ram, the housing 12 is first moved down bodily against the action of the spring 46 so that the bush 28 engages the work or until the limit of its movement is reached and then the punch descends relatively to the housing to pierce the work. In a modified form, the member 12 and the die 50 are carried by separate arms instead of by, a complete U-frame. In another modification, Fig. 4, the upper part of the punch 90 is a close sliding fit within a tubular housing 74, the heavier spring 102 bears between the top of the housing and a head 88 on the punch while the lighter spring 104 bears at its lower end on the top of the frame 8 and at the top is anchored to the tubular member 74. A screw or pin 112 carried by the member 74 projects into a slot 100 in the punch. Alternatively, the lower end of the spring 104 may be anchored in a bayonet slot in the member 74 and itself project through into the slot 100 in the punch as shown in Fig. ,7. A number of frames containing punch housings and dies may be bolted to a false bed which is in turn bolted to the bed of a press so that a number of holes may be pierced in the work by a single movement of the press ram. Alternatively a number of punch housings and dies may be mounted in a single elongated. frame. Any punch housing may readily be replaced by another having a punch of a different size if a different-sized hole is required.