Patent GB-507363-A (GB)
Title: Improvements in or relating to hydraulic shapers or other machine tools
IPC: B23D1/08
Filed: 1938-04-01
Abstract: 507,363. Hydraulic machines. ROCKFORD MACHINE. TOOL CO. April 1, 1938, No. 10002. Convention date, April 8, 1937. [Class 69 (ii)] [Also in Group XXII] A hydraulic shaper or other machine tool has a hydraulic system for reciprocating a ram or carriage including a reversing-valve controlled by a pilot valve which together with its casing is located internally of the machine and is operated by means mounted on the reciprocating ram or carriage. As applied to a shaping machine the ram 13 reciprocates in guides 12 and the work table 19 which carries a tiltable vice 24 is fed transversely along a rail 17 which in turn is vertically adjustable along guides 18' by a screw 20 coacting with a nut which is manually rotated from a shaft 21. The transverse table feed is effected either manually from a lead screw 22 or automatically from a hydraulic cylinder 23. The ram is reciprocated by a hydraulic ram motor 15 fed from a pump 30 driven from a motor 31. The pump delivers through a volume-control and relief valve 33 which may be set by a handle 331 so that it passes a pre-determined volume through a line 49 to the start, stop and speed selector valve 34 operated from a handle 34<1>. In the "stop" position shown in Fig. 2 the fluid in line 49 passes through the line 62 back to the reservoir. When the valve is moved partially to the right fluid passes through the passage 80 to a reversing valve 35 and is directed to one end or other of the ram cylinder. The piston rod 40 is of large size so that a quick return movement of the ram is obtained. In the position of the reversing valve shown in Fig. 2 fluid may pass to the right-hand end of the ram cylinder through passages 70<1>, 43, to give the slow working stroke. The exhaust fluid from the back of the piston passes along passage 44, back-pressure valve 37, line 64, groove 55, passages 81, 82 and grooves 56, 57 to exhaust line 63. The back pressure valve 37 serves to prevent irregular movement of the ram against variable resistance. When the valve 34 is moved fully to the right, Fig. 2, the inlet groove 53 communicates with both the channels 80, 81, and fluid discharged from the back of the piston flows, reversely through the valve 37 to the front of the piston together with the pump discharge so that a high operative speed is obtained. When the reversing valve 35 is moved to the left, fluid from passage 80 flows through grooves 76, 77, passage 81, line 64, valve 37, which offers no resistance in this direction and passage 44 to give a quick return, while fluid at the front of the piston passes through grooves 74, 75 and passage 79 to the exhaust line 62. The reversing-valve is controlled by a pilot valve 36 which is automatically rotated through 45 at each end of the stroke by adjustable dogs 105, 106 on the ram. A choke 101 maintains pressure in the, pilot valve circuit independently of the pressure in the main circuit. In one position of the Pilot, fluid flows from lihe 93 to line 95 to move the reversing-valve to the left while in the other position the valve is similarly moved to the right. In order to control the movement of the reversing-valve the exhaust from this valve is progressively throttled. Thus in the first part of the movement exhaust may escape freely through a passage 126. This passage is this closed, the fluid may then escape through a port 127 which is controlled by an adjustable grooved plug. Finally the last part of the fluid escapes through a further restricted port 128. The end of the valve movement is cushioned by a dashpot obtained by the engagement of member 119 with a bore in the valve end. When the pilot valve is operated to shift valve 35 to forward position, fluid is admitted to a line 167, tube 166, cylinder 165 and conduit 168 to move a piston 136 against the pressure of a return spring 139 and apply cross-feed to the work. The cylinder 165 serves to obviate the necessity of flexible connections to the table. The piston movement is communicated to the feed screw 22 through pinion 146, one-way clutch 150 and reversing bevel gearing 154. 'The movements of the piston 136 are also cushioned by means of oil dashpots formed by recesses in the piston coacting with projections on the cap 137 and in the stroke controlling screw 170 respectively. The cylinder 38 is formed as an integral part of a large casting 42 which forms also the housing of valves 34 and 35 and provides other passages shown in Fig. 2. The pilot valve 36 is mounted on top of the cylinder 38 and projects upwards through the ways 12 and partially into the hollow ram. The operating dogs are also secured within a recess of the ram and are adjusted by the external handles 107.