Patent GB-554629-A (GB)
Title: Improvements in presses for drawing metal and other material in strip or sheet form
IPC: B21D24/00
Filed: 1942-01-09
Abstract: 554,629. Cupping presses. CROWN CORK & SEAL CO., Inc. Jan. 9, 1942, No. 371. Convention date, Jan. 3, 1941. [Classes 83 (ii) and 83 (iv)] [Also in Group XXIV] Presses for punching and cupping blanks from strip material, particularly in the manufacture of cans, have a stationary draw-ring with a stationary blanking out ring surrounding it. The punch reciprocates within the draw-ring and the movable die co-operates with the rings and the punch. The press has special actuating control and safety mechanism for the die parts and roller feed and scrap cutting mechanism for the stock. The press may, if desired, operate upon preformed blanks. The sheet is preferably passed from an uncoiler to the feed rollers so that the duty of the latter is confined to regulation and control. The strip is kept against a wear strip 180, Fig. 17, in the guides 176, 177 being supported by a plate 178, Fig. 2, gripped in this region of the feed rolls 174, 184. On the opposite side a guide strip 385 on a sliding finger portion is engaged with the strip by a spring 388. The feed rolls have a spring controlled lateral float on their shafts to permit accurate guiding of the sheet and between each intermittent feed step the rolls are separated from the stock to permit them to recenter with respect to the float controlling means. Rolls 185 between the feed rolls do not have feeding engagement but act as hold-downs. A lever 233 on a rock shaft 229 is operated, by a collar 241 on a rod 240 operated by a lever 307 and cam on the main shaft 300, to raise the rods 187 attached to the upper feed roll bearings and so relieve the grip on the sheet. Springs 189 effect their return. A hand lever is provided to relieve the grip at other times when required, for example, when feeding in a strip initially. The rod 240 is linked at 98, 99 to a rock shaft 106 segmentally geared to a parallel rock shaft 96. Arms on these shafts are linked to rods 90 carrying the ejectors 86 and passing through the hollow double spherical ended links 75 connecting the punch rams to the head 63. The head carries two punches on each side those on one side being staggered with respect to those on the other. A crank pin on the end of the shaft 300 is linked through a rock shaft 335 to a rod 337 connected to a rack engaging a segmental gear on a ratchet lever swinging a pawl 198, Fig. 21, about the axis of the lower feed roll. At the start of the feed stroke a shield 201 maintains a detent 202 free of the ratchet wheel 195, but is released to prevent over-run at the close of the stroke which rotates the wheel half a revolution. The feed rolls may be operated by a hand wheel 207. A cross bar 51, Fig. 15, on the frame supports through interposed members 55, 59 the blanking die 60 and the draw-ring 61 engaged by an annular piston 57 backed up by fluid pressure supplied by ports 58 in the member 55 connected to a supply pipe 361, Fig. 16. At the start of the drawing stroke the piston 340 is at the top of its stroke and holds a valve 354 open admitting full pressure through a port 350 from a pipe 366 supplied through a control valve 368, and relief valve 367 from a tank 362<SP>1</SP> fed by a reducing valve 364 and control valve 363 from a supply 362. As the stroke proceeds the piston, that is linked at 344 to a member 346 carried by one of the side links 70 that actuates the head 63, descends and the valve closes shutting off supply from the port 350. As the span above the piston increases the pressure in the pipe 361 falls and the pressure on the draw-ring is gradually decreased. A byepass 366 with reducing valve 370 makes up any leakage from the annular cylinders. The links 70 are connected to arms on a rock shaft having two relatively adjustable arms carrying rollers engaging cams on the shaft 300 to provide positive movement in each direction. The ejected stampings C, Fig. 15, strike a deflector 1221 and are discharged laterally through openings in the frame. The lower slide 113, Fig. 2, that carries the dies 119 and stripper plate 120 carried by a series of spring pins, is connected by a nut 126 to a screwed ram 129 operated through a toggle 130 linked through a connecting rod 145 to a multiarmed lever 160 actuated by cams on the main shaft. The small end 146, Fig. 13, of the connecting rod is carried by a square shank 147 sliding in a corresponding socket in the large end 144. The parts are normally maintained rigidly connected by interengaging bevel-edged blocks 157, 156, the latter being spring pressed by a plunger 150. Under abnormal pressure the block 156 yields and the toggle is not straightened. The nut '126 carries a worm wheel 127 meshing with a worm driven by a telescopic shaft, fitted with universal joints, from a motor 141. A cap 135 acts as a stop to limit the upper position of the slide 131 and a stop 134 determines the lower position in which the increased separation of the parts permits access to the dies. Limit switches operated by the slide automatically stop the motor at the ends of the traverse. The main shaft 300 is gear driven from a pinion 292 on a shaft 279, driven through an air operated clutch which may be of the type described in U.S.A. Specification 2,013,144, and fitted with a brake. Drive is taken from a fly wheel and belt pulley 278 from the main motor 276. A scrap cutter 250 is carried by a slide linked to a lever 255 oscillated by a link 262 from the head 63. The scrap cutter frame is pivoted and can be swung to the dotted line position, Fig. 2, by a toggle 269 actuated from a hand crank through worm gearing. The frame is partly balanced by spring devices 271 and when raised affords access to the punches from the rear. A solenoid operated valve controlling the clutch and brake is in series with a number of switches and if any of them be open the clutch cannot be engaged or if any be opened during running the clutch is disengaged and the brake applied. One switch is closed by nut 126 when in the raised position, another is closed by the pressure in the line 361 and opens if the pressure on the draw-ring is inadequate or fails, and a third is opened if the stock buckles in :front of the dies owing to obstruction to feed.