Improvements in or relating to the control of hydraulic or other fluid-pressure operated presses

摘要

549,123. Fluid-pressure presses. MILLS & CO. (LLANIDLOES), Ltd., J., and MILLS, R. G. July 10, 1941, No. 8734. [Class 69 (ii)] [Also in Group XXVI] In a hydraulic or other fluid-pressure press a spring-loaded ram 1 mounted in a press cylinder 2 acts in the first place to apply pressure to the press ram 19 and higher pressures are built up when the ram 19 is acted upon by fluid pressure admitted to the cylinder by a pipe 5 from a supply unit 6 comprising a low-pressure pump 7 and a high-pressure pump 9 driven by eccentric mechanism including an adjustable link 13. The ram 1 then acts in opposition to the fluid pressure. The building up of pressure in the press is at a rate depending upon the rate of discharge of fluid from the unit 6. The building up of pressure commences when a byepass valve 18 is closed, and the pumps then discharge fluid to the pipe 5 via spring-loaded valves 14, 15. When the ram 19 contacts with the work the valve 14 cuts out the low pressure system owing to the rise in pressure in chamber 16, which initially receives both the high and low pressure fluid. The low pressure fluid is then byepassed to the supply tank via a relief valve 20. The pipe 5 is fitted with a high pressure relief valve 21. The ram 1 may be loaded by a single spring 3 or by two or more rams, or by air-pressure. In a modification the work table 22 may be supported by a ram 1 in a cylinder 23 connected by a pipe 24 to the press cylinder 2, and springs 25 load the table against the action of the fluid pressure.