GB564727A - Improvements in and relating to hydraulic presses - Google Patents

Abstract

564,727. Hydraulic presses. BENCH, D. E., and FLOWERS, P. E. Sept. 2, 1943, No. 14338. Addition to 557,033. [Class 69 (ii)] A hydraulic press as described in the parent Specification in which a platen is operated by a number of fluid-operated motors supplied with pressure fluid which is controlled and varied automatically in response to a predetermined deviation or tilting movement of said platen, is modified by employing control valves respectively associated with said motors, each valve acting to control the supply of fluid to a motor in response to the tilting movement of the platen. As applied to a hydraulic press, Fig. 1, in which the cylinders 11, 12 of plungers 13, 14 bearing a platen 15, are supplied with fluid from a single pump 30 under control of a servomotor 48 and an operating-lever 52 actuated by an electromagnet 54 in a manner similar to that described in the parent Specification control valves 28, 39, Fig. 1, are arranged in the supply pipes to the cylinders 11, 12, and these valves are operated by electromagnets 36, 37 ; 36a, 37a to cut off the supply to a particular cylinder when due to tilting of the platen a greater relative supply is necessary to a co-operating cylinder in order to restore the level of the platen. The energization of the magnets operating the valves 28, 39 is effected by switches 69, 70 which are closed if the corresponding end of the platen moves downwards relatively to a reference member 62 provided with a plane surface 66 connected to the platen by a universal joint in such a way that it maintains its horizontal position. The valve 28 is normally kept open by a spring 38, and its position under the action of its electromagnet is controlled by an adjustable screw 35 so as to vary the flow restriction. In Fig. 3, the switch 69 is operated by lever mechanism which magnifies the differential motion of the platen 15 and reference member 66, motion being transmitted to the switch by a spring 89. The reference member may comprise two beams 92, 93, Fig. 5 (not shown), for use in a press having four plungers arranged at the corners of a rectangular platen. In the case of a very long platen 126, Fig. 9, actuated by a plurality of cylinders 102, 103 ... 107, each is associated with a valve 114, 115, 116 ... 119, controlled by switches 120, 121 ... 125. In this modification, a slight deviation may be corrected by actuation of either of the outermost switches 120, 125, but if a greater deviation occurs the other switches operate in succession to effect correction. In Fig. 10, the reference member 62 is replaced by a plurality of rods 127, 128 resting on the platen 15. Their movement is controlled by stationary guides 129, 130, 131, 132, and switches 135, 136 operate as in prior constructions to correct deviation of the platen. In a further modification, the reference member consists of a beam guided on stationary guides which may also be the same guiding members which guide the platen. The electrical control means may be replaced by mechanical or hydraulic control means. Specification 546,609 is also referred to.