Patent GB-1092624-A (GB)
Title: Improvements in and relating to grinding machines
IPC: B24B49/18
Filed: 1964-11-13
Abstract: 1,092,624. Grinding. C. JONES (Landis Tool Co.). Nov. 13, 1964, No. 46253/64. Heading B3D. A grinding machine for grinding cylindrical workpieces comprises a grinding wheel 12, Fig. 1, rotatably mounted on a support 11 slidably mounted on a bed 10 for movement transversely toward and from a workpiece W, feeding means for moving the support towards and from the workpiece, a dressing tool D, means 130, Fig. 3, for traversing the roller across the grinding wheel, a gauge 40 adapted to provide a signal when the workpiece has been ground to a predetermined size, and control means directly connected by a circuit to said gauge for actuating the dressing traverse in response to said signal to initiate a dressing operation immediately the workpiece is ground to said predetermined size. The feeding means for moving the support 11 consists of a piston-and-cylinder device 50, 51 for effecting a rapid movement of the support and a piston-and-cylinder device 190, 191, Fig. 5, formed with a rack 192 engaging a gear 193 on a hand wheel shaft 194 for effecting a fast and slow feed of the support. The workpiece W is mounted between a headstock 17 and a tailstock on a swivel table 16 on a carriage 15 longitudinally movable relative to the grinding wheel. A steady frame 20 is pivotally movable about a pivot 21 on the table 16 by a piston-and-cylinder device 30, 31, the frame also carrying a gauge 40. The dressing tool D is mounted at the rear of the grinding wheel and the roller 80 is carried by a shaft 90, Fig. 2, which is supported in bearings in a housing 81 and is rotated by a motor 92. The housing 81 is mounted on a bar 71 which is movable in a housing 70 towards and from the grinding wheel by a hand wheel 75 or mechanism which automatically compensates for reduction in wheel diameter. The housing 70 is movable longitudinally and transversely by means of ball guides 111, 112, Fig. 3, on a slide member 113 on a bracket 60 mounted on the machine frame. A profile bar 120 is secured to the member 113 and a follower 121 on the bar 71 is urged towards the profile bar 120 by a fluid pressure device 140, 141 and the roller is traversed past the grinding wheel by a fluid pressure device 130, 131, the profile bar and follower being so dimensioned that the roller dresses the face of the grinding wheel and forms radii on its edges. Coolant is supplied to the dressing roller by way of passages 100, 101, 102 and a cone-shaped nozzle 103. The dressing device is actuated by a relay 57CR which is connected to a selector switch 155 having four contacts 1, 2, 3 and 4, each of which is connected to a separate control means actuated at different points in the grinding operation. With the switch 155 set at contact 1, the dressing device is operative immediately the work is to size, the gauge 40 completing the circuit through contact 1 and the dressing relay 57CR. The dressing device may be operated when the grinding wheel is in its retracted position through actuation of a limit switch 1LS completing the circuit to the dressing relay 57CR through contact 2. With the selector switch set to contact 3, the dressing device is operated at the end of the rapid feed by the piston-andcylinder device 50, 51 under the control of a dashpot, the rod 52 of the piston actuating a positive stop 54 from which fluid is being discharged to increase the pressure in the circuit and actuate a pressure switch 2PS which makes a circuit through contact 3 of switch 155 and the dresser relay 57CR. The feed of the grinding wheel is continued by operation of the piston-and-cylinder device 190, 191 during the dressing operation, the dressing operation ending before or during round out as determined by a timer relay. Finally, with the selector switch set to contact 4, dressing may be effected at the end of the fast feed when the piston 191 has uncovered a port 195 so that fluid pressure can act on a pressure switch 7PS which completes a circuit through a timer and contact 4 to the dresser relay 57CR. The circuit may be arranged such that dressing is completed before further slow feed of the grinding wheel or may be effected with the slow feed. At the end of the feed by piston 191, a further port is uncovered so that fluid pressure actuates a pressure switch 3PS which operates a timer that in turn controls a pneumatically operated circuit having a piston-and-cylinder device 160, 161, movement of the piston acting through a ratchet mechanism 166 to rotate an incremental feed screw 167 of the grinding wheel.