Patent GB-604260-A (GB)
Title: Automatic dimpling machine
IPC: B21D22/04
Filed: 1945-12-28
Abstract: 604,260. Dimpling. CHICAGO PNEUMATIC TOOL CO. Dec. 28, 1945, No. 35070. Convention date, Jan. 15. [Class 83 (iv)] An automatic dimpling - machine comprising opposed dimpling-tools, a fluid pressure piston adapted to move one tool towards the other to dimple the work and then to allow the tools to separate and a valve for controlling the movements of the piston is characterised by control means for actuating the said valve, including a movable contact associated with one of the tools and positioned so as to be moved by a work sheet when placed in proper position to be dimpled and including also means actuated in response to a predetermined pressure between the tools for causing the separation of the tools at the completion of a dimpling operation. The machine comprises a base supporting a column 24 and a yoke 21 having upper and lower jaws 22, 23, Fig. 2. A tool holder 27 mounted in the upper jaw is adapted to be depressed by a lever 28 pivoted at 29. A cylinder 32 on the yoke may be supplied with compressed air at either end to effect movement of a piston 33 whose rod 34 carries rollers 35 moving over the top of the lever 28 which is depressed on the forward stroke of the piston. Within the holder 27 is a punch-holder 78 secured by a screw. The punch-holder 78 carries a dimpling-punch 83 secured by a set-screw. Around the exterior of the punch-holder is a resilient pad 86 held between a plate 88 and a washer 87 which is retained in place by a split ring 89 longitudinally slidable in an annular groove 91. On the lower end of the punch, below a flange 94 is mounted an interchangeable dimpling-sleeve 95, while surrounding the flange 94 and sleeve 95 and subject to the pressure of the pad 86 is an outer work-holding sleeve 99 retained by a ring 100 and depending to approximately the lower end of a frusto-conical portion 98 of the punch. In the lower jaw 23 is secured a bush 108 into which is screwed a sleeve 107. A dolly 103 is secured within a sleeve 104 mounted within the sleeve 107. The dolly is surmounted by a dimpling-die 109 having a dimpling recess 114 in its upper face. A pilot pin 116 passing through the die rests on the prongs 118 of a sleeve 119 resting on a washer 121 supported by a spring 122 within the sleeve 104. The die is surrounded by a dimpling-sleeve 124 normally projecting above the upper face of the die and resting on a ring 125 supported by a cross-bar 127 against the underside of which abuts a push-rod 137 which extends down into a housing 151 containing an electric switch which is actuated through the push-rod by the weight of the work when placed over the pilot pin 116 to rest on the sleeve 124 which is thus depressed. The lower end 142 of the dolly sleeve 107 carries a knurled ring 143 by which the position of the sleeve within the bush 108 may be adjusted, the lower ends of the members 108 and 142 having scales to indicate their relative positions. In addition to the switch within the housing 151, the starting of the machine is controlled by the pedal of a foot switch and the stopping of the machine after a dimpling operation is controlled either by a switch 45 actuated by the advance of the plunger-operating rollers 35 or by a switch 70 which is operated by a given amount of relative movement of the yoke jaws. A U-shaped member 59 fixed at one end to the lower jaw extends at its other end into a switch housing 64 carried by the upper jaw so that a relative movement apart of the jaws resulting from a certain dimpling pressure causes a movement between the member and the switch housing which is utilized to operate the switch. In operation, the work is placed on the die 109 with the pin 116 projecting through the hole, the edge of which is to be dimpled. The plunger is then moved down so that the pin 101 projecting from the dimpling-punch passes through the hole and depresses the pin 116 against the action of the spring 122 until finally the upper surface of the sheet is dimpled by the frusto-conical portion 98 of the punch. Admission of compressed air to the plunger-operating cylinder is controlled by a valve 53 actuated by a solenoid 56. In a modified form, Fig. 7, intended for the dimpling of the underside of the work, the die 109 is carried by the holder 195 mounted on the tool-holder 27 in the upper jaw 22. In the lower jaw 23, the punch-adjusting sleeve 201 is adjustably screwed into the bush 108 and carries the punch-holder 206 on which is mounted the resilient pad 86 between a lower adjustable plate 88 and an upper washer 87  secured in place by a split ring 89 movable longitudinally within the limits of a groove 211. The flange 94 of the punch 83 rests on the top of the holder 206 and the surrounding sleeve 214 is carried by a ring 125 mounted on the cross-bar 127 bearing on the upper end of the switch-actuating push-rod 137.