Patent GB-553495-A (GB)
Title: Improvements in or relating to hydraulic presses
IPC: B30B15/16
Filed: 1942-11-05
Abstract: 553,495. Hydraulic presses; stamping metals. MULLER, J. A. Nov. 5, 1942, No. 15594. [Class 69 (ii)] [Also in Group XXII] A multiple action hydraulic press, which is applicable for shaping metal, is constructed with two fluid operable plungers movable towards each other for exerting shaping pressure on a workpiece 142, and the first plunger comprises a platen 7 to which a die 141 is secured adapted to coact with a lower die 143 to perform the first shaping operation as shown in Fig. 3, and the second plunger 15 is arranged inside the die 143 and is raised relatively thereto to perform the second shaping operation to produce the complete article shaped as shown in Fig. 4. The platen 7 is surrounded by fluidpressure operated clamps 13 which can move relatively thereto to a limited extent and which press the workpiece 142 against the outside of the die 143 prior to the shaping operation. The platen 17 is carried by a central piston 32 and by the plungers of reversible pistons 30, 31 which assist the retraction. Starting from the position shown in Fig. 1 a oneway variable discharge pump 6 and two reversible pumps 5, 4 are started and solenoids 63, 63a are energized to cause linkage 62, 62a to set the pumps 4, 5 to full-stroke forward position. Pressure liquid is supplied to the cylinders 33, 34, 35 from a tank 3 through surge valves 36, 37, 38, and the pumps 4, 5 deliver through a spring-pressed valve 116 to a pipe 101 leading via pipe 47 to the cylinder 33. Valves 39, 40 of the kind described in Specification 540,166 act as cylinder relief and pump byepass valves to facilitate the retraction-stroke of the platen 7. The pipe 47 also receives liquid from the pump 6. When the platen clamps 13 engage the work plungers 22a thereon move upwards relatively to cylinders 22 and pressure builds up in the cylinders 33, 34, 35 closing the surge valves. At the same time n valve control rod 137 is moved by a pin 139 arranged in an arm 140 of the platen to operate a valve 106 which connects the cylinders 34, 35 also to the outlets of the pumps 4, 5, 6. The outlets of cylinders 34, 35 are connected by a pipe 50 to the suction side of pumps 4, 5, and liquid from the tank 3 may pass via check valves 58, 59 to the pipe 50. When the first shaping action is completed pressure builds up in a tonnage control valve 109 and a solenoid 123 is operated to reverse the valve 116 so that the output of the pumps 4, 5 is directed to a pipe 131 connected to the bottom of a cylinder 14 in which the plunger 15 which operates the lower die 16a is fitted. The valve 109 may be of the kind described in Specification 519,824, [Group XXXVII]. Liquid from pump 6 still presses on the platen and clamps which retain their position until a tonnage control valve 133 de-energizes the magnets 63, 63a, and 123, to cause the pumps 4, 5 to be reversed and to return the valve 116 to its original position so that the upper ends of the cylinders 33, 34, 35 are connected to exhaust and pressure liquid is directed to the lower ends of the cylinders 34, 35 to cause the pistons 30, 31 to retract the platen and die 141, and also to retract the lower die. The clamp 13 remains in contact with the upper part of die 143 to enable the dies to be stripped from the article, until finally eyes 24 on the platen 7 operate bolts which raise the clamp. Finally a rod 64 is operated by the platen to shift the pumps 4, 5 to no-stroke position. The clamping pistons 22a are connected by hollow pistons 20 movable in cylinders 19 which can receive liquid from the tank 3 through check valves and are connected to relief valves 82, 83, 84 from which pressure can be relieved when the lower die comes into action. In a modification, Fig. 5 (not shown), the lower.die comprises two shaping members adapted to produce a completed article of different shape.