Patent GB-568746-A (GB)
Title: Hydraulic table reciprocating mechanism
IPC: B24B47/06
Filed: 1943-08-04
Abstract: 568,746. Grinding. NORTON CO. Aug. 4, 1943, No. 12608. Convention date, Aug. 21, 1942. [Class 60] [Also in Group XXIX] The reciprocating table of a grinding-machine is operated by fluid-pressure means comprising a cylinder on the table operated through a two-part piston type reversing valve, the actuation of which is initiated by a reversing- lever and adjustable dogs, the actual reversing movement of the valve being effected by fluid pressure. The machine has a base 10 on which is slidable the table 11 to which is secured a cylinder 12 containing two pistons 15, 16 connected by hollow rods 17, 18 respectively with hollow brackets 19, 20 on the base 10; the base has therein a reservoir 21, from which fluid is drawn by a pump 23, and to which exhaust fluid returns. A valve 25 is provided having two operative parts, namely, a stem 28 having thereon pistons 29, 30, and slidable thereon a reversing-valve member 32 formed with pistons 33 ... 35, the pistons 29, 30 being of smaller diameter than the others ; as shown, exhaust fluid may pass from the chamber 43 at the right-hand end of the cylinder 12, through the valve 25 and a pipe 49 to a speed control and start-stop valve 51. The fluid passes into the valve through a V-shaped port 59 which may be covered more or less by rotation of the valve stem 55 to bring the inclined end of a piston 57 over the port, fluid passing from the valve through a pipe 54 to the reservoir 21. The piston 57 is adjusted rotatably by a knob 58 on the stem 55, and is held in adjusted position by a serrated portion 60 on the stem engaged by a spring plunger 61 ; this allows axial movement of the valve without rotation, the axial movement being effected by a lever 65 pivoted at 66 and serving to start or stop the reciprocation of the table 11. When in the stop position, the port 59 is covered by the piston 57 and a space 82 between piston 57 and a piston 56 allows communication between pipes 80 and 81 leading to the hollow brackets 19, 20 respectively, whereby movement of the table is not resisted by fluid pressure. Movement of the reversing-valve 25 is initiated by a lever 85 carried by a shaft 86 to which also is secured a lever 88 engaging the valve stem 28 ; the lever 85 is actuated by dogs 92, 93 adjustably mounted on the table 11 to engage the lever 85 at the ends of the strokes of the table. The valve 25 has a chamber 100 between piston 29 and piston 33, and a port 101 may connect the chamber 100 to a reservoir 102, and a port 103 may connect pressure fluid in the valve passage 36 with the chamber 100 ; a chamber 105, ports 106 and 108, and a reservoir 109 similarly are provided at the other end of the valve. When the lever 85 is moved by a dog, it serves to move the valve parts 28, 32 together until the exhaust end of cylinder 12 is shut off ; this movement also opens one of the ports 101, 108 to allow fluid to move the valve part 32 rapidly to open and close the ports necessary to admit pressure fluid to pipe 40 or 45, and to allow exhaust fluid to pass through pipe 49 to effect the reversal of movement of the table 11. Specifications 463,334 and 535,227, [Group XXIX], are referred to.