GB495836A - Improvements in and relating to hydraulically operated machine tools - Google Patents

Abstract

495,836. Hydraulically - operated machine-tools. TRIGGS, W. W. (Lapointe Machine Tool Co.) May 20, 1937, No. 14033. [Class 69 (ii)] A hydraulically-actuated broaching-machine comprises a cylinder 11 containing a piston 12, the rod 13 of which works over a fixed hollow tube 15; a reversible output pump P is provided. During the return stroke, the pump P delivers through 21, 23, 26, 27 to the interior of the tube 15 ; liquid displaced from the cylinder 11 to the left of the piston 12 escapes through 24, part going to the intake of the pump by 22, 20 and the remainder going by 25, 28 to the cylinder 11 to the right of the piston 12 ; the valve 30 controlling the passage 25 is held open by pump pressure acting through 33 on a piston 31. Liquid also passes into the cylinder 11 to the right of piston 12 from a reservoir T by non-return valve 55 and passage 44. On the working stroke, the pump delivery passes by 20, 24 to the cylinder 11 to the left of piston 12, valve 30 now closing under pump pressure acting through 34 on the piston 31 and aided by a spring 35. Liquid displaced from the tube 15 goes by 27, 26, 23, 21 to the intake of the pump ; some of the liquid displaced from the cylinder 11 to the right of piston 12 also goes by non-return valve 46 to passage 27 and thence to the pump intake ; the remainder goes to the reservoir T by passage 44 and back-pressure throttle valve 64 which can be adjusted to vary the opening, but which is not . moved by the pressure of the liquid in the system. A make-up valve 41 is also provided.