Patent GB-567667-A (GB)
Title: Improvements in or relating to means for effecting forming or shaping operations in the manufacture of nails, tacks, rivets, eyelets or like articles
IPC: B21K1/58
Filed: 1943-08-20
Abstract: 567,667. Forging nails, rivets, etc.; power hammers. BRITISH UNITED SHOE MACHINERY CO., Ltd., COOPER, B. P., and HENSHAW, J. N. Aug. 20, 1943, No. 13567. [Class 83 (iv)] Machines for forging nails, tacks, rivets, &c., or for stamping eyelets, have the ram operated by means adapted to cause the approach of the dies in a yieldable manner that is modified to prevent contact of the dies, or to avoid contact with shock, if a blank be absent or misplaced. The die 3, Fig. 1, is carried by a ram 9 slidable in the frame at 6 and hollow to receive the end 13 of a striker 7 operated, through a thrust member 15, by a lever 17 on a rock-shaft 19 actuated by a spring 5. A collar 31 sliding on the striker 7 carries trunnions engaging slots in the ends of a bifurcated lever straddling the collar, rocking on a pivot 23 and actuated by a rotary cam 27. A spring 33 is interposed between the collar and the end of the ram 9. Levers 37 pivoted at 35 on the ram 9 carry - screws 41 that engage a lever 43, pivoted to the frame at 45 under the control of a spring 49, and carrying a roller 47 that engages a wedge-shaped projection 51 on the striker 7. Inclined slots 39 in the levers engage the reduced ends 29 of the trunnions. After a blank W has been headed, the cam 27 swings the lever 21 to retract the ram 9 through the levers 37. The end 11 of the bore in the ram engages the end of the striker which is pressed back, rocking the lever 17 and loading the spring 5. The projection 51 cams down the lever 43 and the spring 49 returns it, latching the parts with the spring 5 loaded. The blank W has been ejected and a fresh blank inserted. The lever 21 now commences its forward stroke. Until the die 3 meets the blank, there is not any appreciable resistance to movement of the ram 9 and the ends 29 of the trunnions remain on the bottom of the slots 39, the striker 7 being held up by the latch 51. On contact with the work, the ends 29 ride up the slots, camming down the levers 37 so that the screws 41 depress the lever 43, tripping the latch 51 and allowing the spring 5 to drive the striker forward, delivering a blow at 11. The fit between the parts 13 and 9 is sufficiently loose to prevent air cushioning. Should a blank be absent or improperly located so that contact with the die is not made, the striker remains latched and the blow is not struck. In a modification, particularly for forming the flanged heads of eyelets or tubular rivets, the striker 61, Fig. 3, is acted on at 59 by the spring-controlled lever 17 as before, but has a yoke 65 with an abutment 71 engaging a snail cam 67 for loading and tripping the striker. The die is carried by the closed end of a sleeve 57 slidable in the ram 75 as limited by a screw 93 engaging a slot in the sleeve. A spring 79 is confined between the end of the sleeve and a head 77 screwed into the ram. A shoulder is formed on the sleeve at 73 and is engaged by the end of a sleeve 81, screwed into the ram, adjustably locked at 83, and closing air ports 89 leading from the interior of the sleeve 57. Projections 95 from the head 77 are engaged by cams 97 and lateral projections (not shown) receive the thrust of springs that maintain contact. In operation, the cams 97 press the die on to the work before the cam 67 trips the striker, and when work is present and correctly positioned the tool and sleeve 57 are arrested just prior to the completion of the stroke of the ram 75, compressing the spring 79 and opening the ports. 89. The striker is then tripped and delivers the blow, air trapped at 63 passing freely through the ports. A port 107 provides for re-entry of air on the return stroke. If work be absent, the ports 89 are not opened and though the striker is tripped, its blow is cushioned by the air at 63.