GB809516A - Improvements relating to automatic grinding machines - Google Patents

Abstract

809,516. Grinding. NUFFIELD TOOLS & GAUGES Ltd. Sept. 4, 1957 [June 7, 1956], No. 17579/56. Class 60. The feed of the grinding wheel 7 of an automatic grinding machine is stopped by actuation of one of a pair of cam-operated hydraulic piston-type valves 19, 20 connected by a mechanical linkage 43, 44 to a pivotal feeler gauge 40 which, upon the workpiece 6 being ground to a prescribed size, swings from its initial position in contact with the workpiece to a position on the other side of a diametral plane of the latter. The workpieces, such as poppet valves, are fed from a conveyer and successively advanced up to a stop 5 in a collet chuck 4 by a hydraulically-operated plunger 2, the feeler 40 being held in a raised inoperative position. The grinding wheel, which is carried on a spindle 8 belt-driven from a motor 10, is mounted on an inclined slide 11 reciprocable to and from the workpiece by a piston-andcylinder device 12 supplied with fluid pressure from pipes 13, 14 and a valve unit 15 containing the valves 19, 20 controlled by cams 30, 31 respectively. The cams are mounted on a shaft connected to a free-wheel device, the driven member of which can be released by actuation of a solenoid-operated pawl. Rotation of the cam 31 displaces a follower 45 and the linkage 43, 44 to lower the feeler about its pivot 41, Fig. 3, into contact with the workpiece, the opposite side of the follower displacing the valve 20 so that fluid pressure is connected by the pipe 13 to the cylinder 12 to feed the grinding wheel towards the workpiece. When the workpiece has been ground to the predetermined size, the feeler pivots through the diametral plane of the workpiece with consequential movement of the linkage 43, 44 and follower 45, and the valve 20 is set to supply fluid pressure to both pipes 13, 14, thus preventing movement of the slide 11 and providing a dwell until the cam 30 has rotated sufficiently to operate the valve 19 and connect pipe 13 to exhaust and return the grinding wheel to its starting position. The chuck 4 is then automatically opened and the workpiece ejected by a hydraulic mechanism 48. The feeler may be provided with a roller 42 for contact with the workpiece and its pivot adjusted to suit the size to be ground on the workpiece ; the solenoid actuated pawl can be manually disengaged to assist the setting-up procedure. The grinding wheel can be dressed by a diamond 52 making two traverses across the wheel surface and the reduction in diameter of the wheel compensated by axial adjustment of the piston of the device 12 by means of mechanism in a casing 17. The Provisional Specification describes the mechanism for this purpose as comprising a pawl-and-ratchet device set into operation by the insertion of a workpiece into the chuck and arranged after one revolution of the ratchet wheel to actuate through a valve a piston-and-cylinder device and pawl-operated gearing which feeds the diamond 52 into dressing position and adjusts the position of the piston of the device 12.