GB1487407A - Fluid pressure-operated device - Google Patents

Abstract

1487407 Shearing; punching; caulking M ISHIHARA 10 Dec 1974 [14 Dec 1973 30 May 1974] 53293/74 Headings B3W and B3U A fluid-pressure operated device, e.g. for shearing steel bars, comprises a cylinder 20 divided by a piston 21 into a high pressure chamber 23 and a low pressure chamber 17b, a spring 40 urging the piston towards the chamber 23. A pump 31 feeds fluid to the chamber 23 to move the piston 21 and thus a shear blade 57 through a working stroke which is terminated by the opening of at least one return valve 41 when valve rod 43 engages a stop 49. Raising of the valve head 46 from an opening 47 in the piston 21 allows fluid to flow through passage 45 from chamber 23 into chamber 17b. As pressure in chamber 23 decreases a spring 48, compressed by the stop 49 before the rod 43 contacted it, moves the rod 43 to the right and a spring 50 holds the valve open until the piston 21 has been returned by the spring 40 to Fig. 1 position. The pump 31 comprises a cam rod 32 eccentrically mounted on a motor-driven shaft 26 and acting on a plurality of plungers 34 to force fluid from reservoir section 17a through passage 37, one-way valve 38 and passage 39. A safety valve 60 in a passage 59 can be opened manually to allow fluid to pass from chamber 23 to chamber 17b so that material which has proved to be too hard to shear may be removed. A flexible bag 63 compensates for variation in the volume of the reservoir during reciprocation of the piston 21. Alternatively, a piston (72), Fig. 5 (not shown), in a cylinder (69) communicating with the reservoir is movable against the pressure of light spring (73) in response to volume variation. A combination of flexible bag (74) and piston (75) is shown in Fig. 6. The shear blades 57, 58 may be replaced by a punch and die or caulking tools.