Patent GB-1048285-A (GB)
Title: Improvements in surface grinding machines
Inventor: BOSEBECK HELMUT
IPC: F15B11/044
Filed: 1963-07-22
Abstract: 1,048,285. Grinding. ROBERT BLOHM. July 22, 1963, No. 28886/63. Heading B3D. [Also in Divisions F1 and F2] A surface grinder of the type in which the workpiece is carried by a work-table reciprocated past a grinding-wheel by a double-acting hydraulic piston motor is provided with rate control means for controlling the rate of flow of the pressure fluid pumped to the pressure side of the motor and with additional rate control means for controlling the rate of the return flow of fluid leaving the motor, whereby the surface grinder may be used either for fine grinding with a small depth of cut and highspeed movement of the table or for rough grinding with a deep cut and slow-speed movement of the table. The output of a constant capacity pump 1, Fig. 1, e.g. a gear pump, passes through an adjustable throttle valve 3 to a reversing valve 5 for the double acting motor 4 which reciprocates the work-table. An oil cooler 7 and relief valve 8 are provided. Return flow from the valve 5 passes to a selector valve 10. In one position of the valve 10 return flow passes directly to the sump and the motor piston 12 moves at a fast speed, e.g. 40-45 m./min., determined by the setting of the valve 3. In the other position of the valve 10 returns flow passed to the sump through a manually adjustable throttle valve 11 so that the piston 12 moves at a slow speed, e.g. 20 mm./min. For moving the table rapidly from one zone of slow speed movement to another such zone, a valve 13 in parallel with the valve 11 is operated manually or electromagnetically under the control of switches operated by dogs on the table. In a modification, Fig. 2 (not shown), control of the return flow to obtain the slow speed is effected by a pump 15 with manually adjustable capacity. In a modification, Fig. 3 (not shown), the motor 4 is reversibly operated by a reversible variable capacity pump 18. Overload valves 19 and make-up check valves 21 are provided on both sides of the pump. When the piston 12 is moving from left to right control of the return flow is effected by the selector valve 10 and the throttle valve 11, provided with the by-pass valve 13, to obtain slow speed movement. At the end of this movement the pump 18 is reversed, the selector valve 10 being positioned to give rapid return of the piston 12. In a modification, Fig. 4 (not shown), slow speed movement in either direction is obtained by throttle valves 11<SP>1</SP> provided with by-passing one-way valves 24. When the table is executing a slow-speed movement its kinetic energy may be insufficient to operate reversing means at the end of its movement. To overcome this, the reversing valve 5, Figs. 1 and 2 (not shown), or the reversible pump 18, Figs. 3 (not shown) and 4 (not shown), may be reversed at the end of the table movement by a load-and-fire device. This comprises, Figs. 5 (not shown) and 6 (not shown), a housing 31 adjustable by a screw 38 relative to a member 39 adjustably located on the table by a catch 40 engaging a rack secured to the table. The housing 31 carries a spring-loaded plunger 29 co-operating with a roller 48 on a part 47 secured to a shaft 49 effecting the reversal. The part 47 has a handle 43. A part 44 secured to the part 47 has two notches 45 engageable alternately by a spring-pressed pin 51. Alternatively, the reversal of the table at the end of its stroke may be effected hydraulically or electrically.