GB505916A - Prefill valves for hydraulic presses - Google Patents

Abstract

505,916. Hydraulic presses. BLISS CO., E. W. Nov. 22, 1937, No. 32099. Convention date, Nov. 20, 1936. [Class 69 (ii)] In a hydraulic press a prefill valve for opening and closing liquid communication between the ram chamber and a source of supply of liquid at substantially atmospheric pressure, comprises a port through which such liquid may pass into and out of the ram chamber, and a reciprocating valve element having a portion adapted to extend into and close said port and held in such closed position by hydraulic pressure acting in opposition to pressure within the ram chamber tending to move said element to an open position; the adjacent surfaces of the valve element and port which coact to close the latter are so relatively formed that said port is opened gradually during the withdrawal of the valve element from within the port whereby to prevent an instantaneous release of high pressure within the ram chamber. The valve element 15, Fig. 1, has oblique and vertical seating surfaces 15a and 15b respectively coacting with corresponding surfaces 29a, 29b on the valve seat. Grooves 32 of different lengths are provided in the surface 15b, of the valve element, for the purpose stated. The valve is opened by a spring 30 and closed by pressure liquid introduced through a port 14b, and passing, when the valve has closed, through a check valve 21 in the valve into the ram chamber 16a. In a modification, Fig. 2 (not shown), the oblique seating surfaces are. below the vertical ones, grooves being provided as before in the vertical seating surface of the valve element. In a modification, Fig. 5 (not shown), the grooves are provided in the vertical seating surface of the valve seat. In a modification, Fig. 4, the vertical seating surface 34 of the valve element is inclined relative to the corresponding surface 29b of the valve seat; alternatively, as in Fig. 6 (not shown), the vertical seating surface of the valve seat is inclined relatively to the corresponding surface of the valve element.