Patent GB-1134194-A (GB)
Title: Grinding machine
IPC: B24B47/20
Filed: 1966-04-01
Abstract: 1,134,194. Grinding. HEALD MACHINE CO. 1 April, 1966 [29 April, 1965], No. 14599/66. Heading B3D. A grinding machine comprises a wheelhead support and a workhead support relatively movable by means of an hydraulic feed actuator on a base, means for presenting fluid to the actuator at one side of an element of the actuator at a controlled pressure during feeding movement, and means connected to the actuator at the other side of the element to permit escape of fluid at a selected rate during feeding movement and, alternatively, to present a fixed pressure fluid during retraction movement. The arrangement provides for a controlled force method of grinding free from vibration or erratic movement of the wheel toward the workpiece. The actuator consists of a piston 21 which is fixed to upstanding abutments 143, 144, 145 on the base 11, and the cylinder of the actuator is formed by a bore 22 in portions 146, 148 of a wheelhead table 12 and heads 147, 149, the table carrying in spindle 18 for a grinding wheel which engages a workpiece, such as a ball-bearing race, which is rotated and supported on shoes 15 of a workhead 14 movable axially on the base 11. The head 147 at one end of the cylinder is connected by a line 92 to a cross-slide valve (85, Fig. 3), high and low force regulating valves (82, 83) in turn connected to a 500 p.s.i. line (38); the line 92 is also connected by a line (87) to a cross-slide feed valve (88) to a 5 p.s.i. line (60). The head 149 at the other end of the cylinder is formed with an adjustable throttle 152 connected by a line 151 and valves (96, 98) to a 125 p.s.i. line (41). A line (103) is also connected to the head 149 and include a cross-slide damper valve (102) which is also connected to the valves (96, 98) and 125 p.s.i. line (41) by-passing the throttle 152 and to a damper by-pass valve (113) by a line (114), the valve (113) being joined to the 500 p.s.i. line (38) and to a drain line (42). The hydraulic circuit of the machine also includes a cylinder (20) for effecting axial movement of the workhead 14, a wheelhead swivel cylinder (27), gauge-in cylinders (28, 29), diamond turner cylinders (31, 32), table index valve (52), a loading cylinder (25), a cylinder (26) for compensating for dressing of the grinding wheel, and various compensating and damping cylinders. In operation, to disengage the wheel from the workpiece, the grinding wheel is initially backed-off from the workpiece by fluid from the 500 p.s.i. (38) line passing through a valve (105) line (97), valve (98) and valve (102) to cylinder (22), and the work and dresser arm are then moved axially past the wheel by means of cylinder (20) and returned. During grinding, the pressure of the supply of fluid to cylinder 22 through line (92) is controlled by the high and low force regulating valves (82, 83), and fluid from the other end of the cylinder passes through the adjustable throttle 152 to the drain line (42), valve (102) being closed. To withdraw the wheel, valve (113) is operated to open valve (102) so that fluid is admitted through line (103) to the cylinder 22 from the 125 p.s.i. line (41), fluid being exhausted through line (92), valve (88) and line (89) to the low pressure line (60). The adjustable throttle is formed on a rod 154 mounted on a differential screw 164, 165 on the apron 153 of the table 12.