GB214727A - Improvements in foundry moulding machines - Google Patents

Abstract

214,727. Waterhouse, H. Jan. 26,1923. Moulding-machines of the jar-ram type are controlled by a single distributing valve having two equal diameter piston-heads 14, 15, Fig. 1, connected by a single part 16 of reduced diameter. In the position shown the working fluid passes through the ports 21, 22, 23 to the bottom of the cylinder 1, the valve being held in the position shown by a spring 31. An exhaust port is provided at 30. As the ram 8 rises the end below the necking 26 closes the exhaust port 27 and subsequently connects ports 29, 28 admitting pressure fluid below the valve which rises and exhausts the cylinder 1 through the ports 23, 24, 25. At the close of the return stroke of the ram the space below the valve is exhausted through the ports 28, 27 and the spring returns the valve completing the cycle. The ports 23, 24, 25 may be duplicated. Machines of large size have the ram fitted with a cup leather and the piston ports are then arranged as shown in Figs. 3 and 4, and cooperate with a spring-pressed shoe 42, the valve 15 being constructed as before. As the ram rises the port 36 admits fluid through the port 44 and pipe 38 below the piston valve, and on the close of the return stroke this fluid is exhausted through the ports 44, 37, 27. Premature exhaust through the port 36 is prevented by a ball valve 45. The spring 31, Fig. 1 may be replaced by a constantly open air supply port so proportioned in relation to the exhaust port 30 that a constant reduced pressure is exerted on the head of the valve. In a modification the valve is maintained in its upper position by a spring.