Patent GB-521484-A (GB)
Title: Improvements in or relating to presses
IPC: B21J9/12
Filed: 1938-11-21
Abstract: 521,484. Metal-working presses ; stamping. LINDNER, P. J. Nov. 21, 1938, No. 33853. Convention date, Aug. 16, 1938. [Class 83 (iv)] [Also in Groups XXIV and XXIX] A hydraulic press has a work turret rotatable on the frame and a ram for co-operating therewith acting through a selected die on a multiple die carrier. The press may be used to form flanged heads on cartridge cases in two pressing operations and utilises hydraulic and electric operating means under electric control. The bed 11 is connected to the head 10 by three columns 12 one of which forms the shaft about which the turret 14 is rotated. The turret is supported by the bed during pressing but during rotation by the D.C. motor 183 it is supported by a, bearing in a yoke elevated by hydraulic means 200. The use of a D.C. motor enables dynamic braking to be used to slow down the turret as it approaches an indexing, position. The turret is made in halves, for bolting around the column 12 and has six tubular turret stations 172 with die supports 173. It is provided with an internal toothed ring 179 gearing with a pinion 181 on the motor 183, and is locked in the pressing position by a spring-pressed pin 216 which may be withdrawn by a solenoid 233. A switch is provided to enable the turret to be operated apart from the press. A hydraulically operated ejector is provided to loosen the workpiece. When operated it engages a die plunger extending through the interior of the cartridge case. A manually controlled, pneumatically operated motor 103, Fig. 7, is provided for hoisting the workpiece out of the turret, by a rod 105 carrying a yoke 106 mounted in a slide and provided with pivoted gripper arms adapted to engage the flanged head of the cartridge case. A pair of dies 78 are carried by a member 77 which can be reciprocated in a guide 74 bolted to the platen 15 by pneumatic means controlled by a valve operated in one direction by a spring and in the other by a solenoid. The dies are alternatively effective at the same work station. The platen 15 is guided by the columns 12 and is connected by a split ring 18 to a double acting plunger 17 in a hydraulic cylinder 25 having connections 29, 30 with a motor driven reversible pump 33, of the radial piston type containing a shift ring serving as a flow-control member. A surge valve 37, constructed according to U.S.A. Specification 1,892,568, is mounted in the top of the cylinder. This valve comprises a member 43 supported against a seating by a spring 44 and which. opens, as the piston moves on its downward. stroke but closes when the pressing operation starts. On the return stroke the plunger 50 is depressed against spring 54 to hold valve member 43 in the open position. Pipes 63, 34 are fitted with relief valves 61, 60 and are interconnected by a main cylinder relief and bye-pass valve 64 constructed as described in U.S.A. Specification 1,956,758, and serving to relieve the pressure above the piston 26 at the instant of reversal of the pump to effect the upward stroke. Sleeves 73 with annular grooves engaging collars on the columns 12 limit the movement of the piston. A control panel 121 carries the various gauges and switches. A press control :rod 131 which may be manually operated by lever. 139 carries a collar 132 adapted for engagement by an arm 133 secured to the platen, a collar 142 for engaging a switch 316, and a collar engaging a bell crank lever coupled to a solenoid and the control valve rod of the servomotor of pump 33. The arm 133 carries a rod 140 adapted to operate switches 317, 318. 'The turret carries cams 341, 342 for operating switches 313, 320. Switches 314, 315 are arranged for operation by movement of the die carrier and other switches are arranged for operation by movement of the locking and ejector pins. The plant is operated from an A.C. supply and includes a motor generator set for supplying the D.C, turret motor. Two sets of cycle start press buttons are provided, each requiring two hands for operation, whereby operation of the press is prevented when the hands of the operators are in the working area of the press. One set may be short-circuited if the press is to be managed by a single operator. Emergency stop switches are provided. The operator closes the switches to start the pump motor and the motor generator set and then depresses the cycle starting buttons. The solenoid 233 becomes energized to withdraw the turret locking pin with consequent closure of a switch associated therewith and operating the turret motor. As the turret approaches the working position cam 341 opens switch 320 to effect insertion of resistances in the turret motor circuit to slow down the motor. Cam 342 then opens switch 313 and the locking pin solenoid 233 is de-energized and the pin moves to open a switch to stop the motor, then locks the turret, and closes a second switch with consequent energization of the servomotor solenoid and operation of the press plunger. When the desired pressure has been applied to the work a pressure responsive switch opens and the solenoid is de-energized. The pump flow is then reversed by a spring. As the piston ascends switches 317, 318 are opened and the solenoid associated with the control valve of the die carrier motor is de-energized. Spring action shifts the valve so that the die carrier is reciprocated to move the second die into the operating position. As the piston reaches its top position switch 316 is closed with consequent reversal of the pump. The second pressing operation follows but on the subsequent upstroke the opening of switch 318 prevents the subsequent closure of switch 316 and completes a circuit through the pump solenoid and the press plunger stops. The turret is lifted and the ejector is depressed during the press cycle but such movements are harmless and enable the use of a simple control circuit.