GB542767A - Improvements in or relating to fluid-operated work pressing means - Google Patents

Abstract

542,767. Hydraulic presses. BRITISH UNITED SHOE MACHINERY CO., Ltd. (United Shoe Machinery Corporation). July 25, 1940, No. 12129. [Class 69 (ii)] [Also in Group V] A fluid-operated press has a quick-advance small area piston combined with a high final pressure large area piston. The system is shown applied to a double-headed work-pressing machine having stationary lower press anvils and moving upper presses carried by arms 14 pivoted each to a head 18 on a piston rod 20 carrying a small piston 22 and a large piston 30. A spring-pressed valve 42, 52, 48 is exposed on descent of the piston 22 to the fluid pressure above said piston, and is thus forced back to allow the fluid to enter the space between the pistons by way of a port 44. The valve head 50 does not quite reach the wall face of the cylinder 24, and a disc 52 behind it fills the valve chamber 40 when valve is open to prevent escape of fluid to reservoir 38. The pistons and upper press may be raised by a manually operated valve introducing pressure fluid beneath the piston 30, and in rising the fluid above piston 30 passes by way of port 44 and hollow part 42 of the valve to a duct 36 leading into the reservoir 38. Alternatively the two heads may be made to function alternately by operating a control valve 84 by a handle 94, and automatic locking of the handle 94 in two extreme positions may be effected by spring catches releasable each by a handle which has to be moved prior to the actuation of and held during the initial movement of the handle 94. The heads 18 are further connected to the ends of a rocking lever 103. Fluid pressure is obtained by a pump 74 rotated by a power pulley 70 and forcing the fluid by way of pipe 78 and valve 84 to piston and cylinder units in turn. The valve 84 has counter-ports cut in the rotary part to balance the fluid pressure and prevent selfactuation.