Patent GB-506976-A (GB)
Title: Improvements in and relating to grinding and lapping machines
IPC: B24B5/04
Filed: 1938-07-28
Abstract: 506,976. Grinding. NORTON CO. July 28, 1938, No. 22503. Convention date, July 31, 1937. [Class 60] A machine for grinding and lapping cylindrical work-pieces comprises means for supporting and rotating the work, a carriage which is reciprocable along a path transverse to the work axis and carries a grinding-wheel and a lapping- wheel, and means for moving the carriage to bring the grinding wheel and the lapping- wheel successively into engagement with the work. The machine comprises abase 10 supporting a reciprocable worktable 11 adjustably carrying a headstock 14 and a tailstock 15 to support the workpiece 18; which is driven, through belting 28, by a variable speed electric motor or 25 mounted on the headstock and controlled by a rheostat 31. The table 11 may be moved manually, through rack gearing, by a hand wheel 32, and may be reciprocated automatically for traverse grinding and lapping or may be stationary for plunge cut grinding etc.; for producing the reciprocation of the table, fluid pressure operated mechanism may be employed similar to that described in Specification 463,334 and comprising a cylinder carried by the table and having therein a piston carried by a rod 44 secured to the base by brackets 45. Fluid to the cylinder is supplied by a pump under control of a valve unit comprising a speed control throttle 52, and a reversing. valve operated by a lever 55 actuated by adjustable dogs mounted on the table. The grinding- wheel 75 and the lapping-wheel 101 are carried by independently adjustable slides mounted on a carriage 70 movable transversely on ways 71, 72 on the bed 10, the carriage extending beneath the work table 11. On the carriage 70 is slidable a grinding-wheel slide 74 carrying the grinding-wheel 75 belt driven from an electric motor 80, the slide 74 being adjustable on the carriage 70 by a screw 91 operated through gearing 89, 90 by a hand wheel 87. The carriage 70 also carries a slide 100 on which is mounted the lapping-wheel 101 arranged to be belt-driven from an electric motor 105, either, through gearing, at a slow speed for lapping, or direct, at a higher speed for trueing the wheel. The speed reduction gearing consists of a gear 114, Fig. 4, on the armature shaft 113 of the motor, driving a gear 115 on a shaft 116, which drives, through two worm gearings 117, 118 and 119, 121, a shaft 122 carrying a belt pulley 108 for driving the wheet 101. The gear is put into and out of action by two clutch members 125, 135 slidable by a yoke 127 moved by a hand lever 131 ; for direct drive, the clutch member 135 is disconnected and the clutch member 125 connects the shaft 13 to the shaft 122. The lapping-wheel during operation, may be reciprocated axially to break up the grinding lines on the work, by means of a worm 150 on the spindle 102 of the wheel, the worm engaging a worm wheel 151 on a shaft carrying a crank plate 152 acting through a connecting rod 153 to oscillate a lever 155 pivoted at 156 to the frame. A stud 157 on the lever engages a groove on the worm 150'to oscillate the spindle, and oscillation may be stopped or started by a hand lever. The slide 100 is adjustable manually on the carriage by a screw 164 in a manner similar to the adjustment of the slide 74. The carriage 70 is moved by hydraulic pressure means to feed the grinding wheel 75 rapidly up to the work, and then at a slower speed until grinding is completed, after which the wheel is rapidly withdrawn, by movement of the carriage 70, thus bringing up rapidly the lapping-wheel 101, the speed then being reduced until lapping is completed. These movements are produced by a cylinder 180 in the base 10, in which is movable a piston 181 on a 'rod 182 connected to the carriage 70, movements of the piston being controlled by a reversing-valve 188 operated by a hand lever 200. The valve .188 comprises a stem 189 with pistons thereon forming three chambers 190, 191, 192, and fluid is fed by a pump 185 from a reservoir 184 by a pipe 187 to the valve, ports 193, 196 leading from the valve to the cylinder 180; an exhaust pipe 197 leads to the reservoir. The slow feed of the wheel 75 for grinding is controlled by a dash-pot regulator comprising a cylinder 210 on the cylinder 180 having therein a piston 211 slidable on the rod 182, and pressed outwardly by a spring 212. When the wheel 75 approaches the work, an adjustable sleeve 213 on the rod 182 engages the piston 211, the speed of movement of which is controlled by the rate of flow of fluid from the cylinder 210 as controlled by a needle valve. Infeed of the wheel continues until an adjustable sleeve 214 engages the end surface of the cylinder 210. A similar feed regulator 215 &c. is provided at the other end of cylinder 180 for the lapping- wheel 101, lapping being stopped by the engagement of a sleeve 219 with the end face of the cylinder 215; the slow feeds controls may be rendered ineffective, grinding and lapping proceeding rapidly until stopped by the stop sleeves 214, 219 respectively. Specification 6784/01, [Class 60], is referred to.