GB825711A - Improvements in or relating to hydraulic synchronizer - Google Patents

Abstract

825,711. Hydraulic presses. U.S. INDUSTRIES Inc. June 6, 1956 [July 20, 1955], No. 17459/56. Class 69 (2). To ensure parallel movement of the slide of a press, each end of the slide 2 is actuated by a piston 4 in a cylinder supplied with liquid by a pump 7. The output of each pump is controlled by a servomotor 12. Pressure liquid is supplied from a line 15 to one side of each servo piston 13 through a line 17, and to the other side through a throttle valve 28; this last side is also connected through a line 21 or 21<SP>1</SP> to a synchronizing valve 24. Valve 24 comprises inner and outer sleeves 33, 30 respectively rotated by pinions 45, 48 meshing with racks 46, 49 on the slide 2. Uneven movement of the slide will cause relative rotation of the sleeves 30, 33 in such a direction that the requisite line 21 or 21<SP>1</SP> is opened to an exhaust line 27, thus actuating the associated servomotor and so reducing the delivery to the leading end. The outer sleeve 30 of the valve 24 carries spring-urged detents engaging depressions in the inner sleeve 33 so that the force of the springs has to be overcome before relative rotation of the sleeves can occur, thus reducing any tendency for the slide to rock. The pumps 7 also supply pull-back cylinders and for this reason lines 21, 211 are connected to valve 24 through a reversing valve (not shown) so that parallel movement may be obtained on the return stroke.