Patent GB-565338-A (GB)
Title: Improvements in or relating to hydraulic presses
IPC: B21D24/14
Filed: 1942-10-30
Abstract: 565,338. Hydraulic moulding presses. ERNST, W. Oct. 30, 1942, No. 15274. [Class 69 (ii)] [Also in Groups V and XXII] A hydraulic press comprises a ram which is opposed during the pressing movement thereof by a cushioning member which supports the work-piece and recedes against a hydraulic pressure, the member later acting as an ejector for the shaped work-piece. The hydraulic connections may be so manipulated that either the cushioning effect or both the cushioning effect and ejector action is suppressed. The press shown includes a main ram 9, a clamping platen 14 which engages the edges of the workpiece whilst the " drawing " action is taking place (see Fig. 6), plungers 182 which lift the ram at the end of the downward stroke of the latter, and a die 237 supported on ejector members 191 carried by a cushioning plunger 188. The ram may descend, rise and stop, or descend and rise continuously. Operation : (1) Plunger 188 acting as a cushion and as an ejector.-The operator presses a push button to energize solenoid 114 which, via lever mechanism 111, 126, 131 moves a servo-motorcontrolled pump 43 to deliver pressure liquid through conduit 65 to the ram cylinder, conduit 67a being the intake. The ram descends, liquid being allowed to escape from the ram-raising piston cylinders 185 to the intake 67a through a bore 73 in one of the four strain rods 3 which connect the head and base of the press. As the ram descends, three things happen: (1) Four hollow plungers 19 secured to the ram suck liquid into clamping-platen cylinders 10 from a reservoir 21 via conduit 154, valve 135 and conduit 164. (2) Just before platen 14 engages the work-piece, a pin 149 carried by ram 9 engages a groove 147 in a push-rod 142 and depresses the latter, thereby closing valve 135 and trapping liquid in cylinders 10 ; the pin passes on, the platen engages the work-piece, the ram continues to descend, and pressure (which may be adjusted by regulating relief valves 173) builds up in cylinders 10 and, via plungers 13, holds the platen firmly on the workpiece. (3) A second pin 101 engages a groove 99 in a push-rod 92 and depresses the latter, thereby closing valve 81 and trapping liquid in the cushion bore 189. As the ram begins its drawing action (Fig. 6) pressure is built up in the bore 189 and in the cushion cylinder 187 (by-pass valve 231 and shut-off valve 232 being closed). Excess pressure in bore 189 and cylinder 187 escapes through adjustable relief valves 235 and 218 to the intake 67a and the cylinder 6 respectively; if relief valve 218 fails, safety valve 203 vents excess pressure from cylinder 187 to reservoir 21. When the ram reaches its lowermost position, tonnage control valve 119 opens and breaks an electric circuit, thereby de-energizing solenoid 114, whereupon spring 133 reverses pump 43. Pressure liquid then raises plungers 182, the ram being thus raised, and a valve 42 (which was prepared by initial flow of liquid through conduits 65, 64) is opened to allow liquid to escape from cylinder 6 to reservoir 21 via port 29a, conduit 41a and valve 42 ; also, pressure in conduits 39, 37 opens a valve 20, whereby cylinder 6 is vented directly into the reservoir. As the ram rises, pins 149, 101 re-engage the push-rods 142, 92 (but this time in grooves 148, 100) to open the valves 135, 81 ; opening of valve 135 vents cylinders 10 to the reservoir, thus releasing the clamping platen 14, and opening of valve 81 allows pressure-fluid to pass from conduit 67a and bore 73 to cushion bore 189, the cushion being thus raised and the shaped article ejected. As the cushion rises, liquid is sucked in to the cylinder 187 from cylinder 6 via a conduit, strain rod bore 73a, conduit 79a and valve 208. As the ram approaches its acme a collar 122 thereon lifts a rod 106 to rock lever 109 and move pump 43 into a no-delivery position ; alternatively for continuous automatic action, rod 106 closes the circuit of solenoid 114. Both the cushioning effect and the ejector action may be suppressed by bringing the cushion to its lowermost position and isolating it by closing valves 198, 208 ; but the article may be ejected, after the ram has risen, by opening these two valves, whereupon pressure liquid from the ram-raising cylinders 185 enters bore 189. To suppress the cushioning effect only, valves 198, 208, 231 and 232 are opened ; when the cushion is depressed, liquid escapes through these valves, and when the ram rises liquid returns through the valves to raise the cushion. Valves 208, 232 may be interconnected by a lever system or gear train for simultaneous action. The tonnage control valve may be that described in Specification 519,824, [Group XXV]. The valve 20 (a " surge " valve) may be that described in U.S.A. Specification 1,892,568.