GB880089A - Universal grinding machine - Google Patents

Abstract

880,089. Hydraulic apparatus. HEALD MACHINE CO. May 24, 1960 [July 13, 1959], No. 18246/60. Class 69 (2). [Also in Group XXIII] The wheel head table of a grinding machine (Group XXIII) is mounted on the base for sliding movement longitudinally thereof, the movement being effected by a pair of singleacting hydraulic linear actuators connecting the wheel head table to the base, each actuator consisting of a tubular body having a bushing at one end and a headless rod extending through the bushing, a passage extending axially through the rod for supplying pressure fluid to the interior of the body, at least one of the actuators having a damper formed therein to resist relative movement of the rod and the body at the end of a stroke. Hydraulic pressure unit 28, Fig. 16, mounted at the rear of the base 11 comprises a sump 172 having mounted on its upper wall a motor 173 driving a rotary hydraulic pump 174 delivering through conduit 175 to a valve box 26, a return line 177 connecting the valve box 26 to the sump 172. The wheel head table 15, Fig. 6, is reciprocated by opposed single-acting hydraulic linear actuators 66, 98 connected to the valve box 26 by conduits 79, 176. The actuator 66, Fig. 5, comprises a piston rod 67 secured to the base 11 and a cylinder 68 fastened by a collar 69 to the underside of the table 15. One end of the cylinder is closed by a cap 71 welded thereto and having an opening with a plug 73. The other end of the cylinder has a bronze bushing 74 retained in a counterbore by a snap ring 75. The piston rod has a bore 77 connected to the conduit 79. A piston 81 has a portion 82 in the bore 77 and a portion 83 projecting from the bore towards the cap 71. A bore 85 in the piston portion 83 is closed by a plug 86 and contains a spring 87 pressing a ball 88 against a seat leading into a small passage 89 opening into a bore 91 in the piston portion 82. The bore 85 communicates through radial ports 94 with the cylinder. The piston 81 is urged to the left by a spring 92 and is prevented from leaving the piston rod by a snap ring 84. An annular groove 95 formed in the wall of the bore 77 adjacent the inner end of the piston 81 communicates through radial ports 96 with the cylinder. The piston portion 82 has a flat 97 adjacent the groove 95. During the operation stroke, oil supplied through conduit 79 flows through the bore 77, presses the ball 88 away from its seat and flows through passage 89, bore 85 and ports 94 into the cylinder. During the return stroke, oil passes from the cylinder through ports 96 and groove 95 to the bore 77 and thence to the conduit 79; towards the end of the stroke the cap 71 strikes the piston 81 and displaces it so as to cover the groove 95, oil then escaping only through the space afforded by the flat 97, thus damping the movement.