GB1235416A - Improvements in or relating to a device for controlling the feeding of hydraulic power devices - Google Patents

Abstract

1,235,416. Hydraulic presses. V. L. A. BIANCHI. 16 April, 1969 [10 May, 1968], No. 19414/69. Heading B5F. [Also in Divisions B3 and F1] A device for controlling the feeding of hydraulic power devices, in particular power devices for actuating the pressing element of a press or a shearing machine, to maintain a parallel displacement of the element, has fluid delivered by pump 34 via distributer 36 and pipe 37 into conduit 16a so as to push cylindrical element 11 downwards. The front face 11a moves down and touches the rear faces 7c of rods 7 of feed pistons 6 so that the latter are also driven downwards and discharge the hydraulic fluid contained in chambers 2a into chambers 26 of power devices 27. The pistons 28 of the power devices move upwards and drive pressing plate 29 along with them. Fluid is sucked from container 35 through pipe 41 into chamber 8b (see Fig. 3) by the vacuum created during the downward motion of the cylindrical element 11 until the pressing plate meets the workpiece. At this point the resistance offered to its feed motion leads to an abrupt increase in the pressure of the fluid which opens calibrated valve 39 so that fluid penetrates into the chamber 8b and closes valve 40. The action of this fluid provides an additional thrust which is much greater than the thrust caused by the fluid in chamber 14a (see Fig. 3), thus providing the extra force required for the pressing or shearing operation. The cylindrical element 11 continues to move downwards until its front face 11a meets the upper face 1a of block 1. At this moment distributer 36 is reversed so that fluid passes into the chamber 14b through pipe 38 and conduit 16b, thus driving the cylindrical element 11 and feed pistons 6 upwards. The pistons 6 suck the fluid contained in chambers 26 of the power devices 27 so that the pistons 28 move downwards. The feed pistons 6 stop when they touch shoulder 23 whereas cylindrical element 11 continues upwards until its rear face touches side-plate 5. This movement frees apertures 10, thus communicating chamber 8a with chambers 2a, allowing hydraulic fluid to be sucked in from pin 18 if any leakage has occurred in the power devices 27. In a second embodiment chamber 55a is fed with fluid through pipe 37 so that piston 60 moves from left to right (see Fig. 4) and drives pistons 56 along with it. The hydraulic fluid in chambers 54a is delivered into chambers 26 of power devices 27 so that pressing plate 29 comes into contact with the workpiece. The vacuum produced in chambers 54b causes fluid to be sucked from container 35 through pipe 41, valves 40 and pipes 42. When pressing plate 29 meets the workpiece the increase in fluid pressure in pipe 37 opens calibrated valve 39 and closes valve 40 so that fluid enters chambers 54b, thus resulting in a considerable increase in thrust exerted on the pistons 28. When the pistons 56 and 60 reach the right-hand end of their travel the distributer 36 is reversed so that fluid enters chamber 55b and drives the pistons 60 and 56 back to their initial position in Fig. 4. When the pistons 56 and 60 reach the end of their travel to the left, rod 68 moves valve 64 from its bearing position on mouths 67, so that if hydraulic fluid does not fill the chamber 54a, fluid makeup takes place by suction of fluid from pan 18.