GB1442101A - Grinding machines - Google Patents

Abstract

1442101 Grinding SUNDSTRAND SYRACUSE Inc 14 June 1974 [14 June 1973] 26408/74 Heading B3D A grinding machine comprises a number of work-tables 14 mounted on an index table 12 rotatable to bring the work-tables in sequence to a grinding station having grinding means 30, such as a grinding wheel or abrasive belt, means for moving the index table and grinding means relative to each other so as to provide translatory movement of a workpiece on the worktable at the grinding station, and means for simultaneously rotating the work-tables relative to the index table. As described, the index table mounts three work-tables 14 and is indexed to present the tables successively to a load/unload station 18, a rough grinding station 24 having grinding means 30 and a finish grinding station 26 having grinding means 32. The index table 12 consists of a circular plate 42 which is mounted for rotation about a vertical axis in bearings 46 and is formed with a gear 52 engaging a gear 50 of an hydraulic motor 48 connected by lines to a swash-plate type pump 60. The pump is controlled so as to drive the index table and sequentially present the work-tables to the stations 18, 24, 26. With a work-table at a grinding station, the swash plate of the pump is oscillated both sides of its neutral position under the control of trip dogs 72 and switches 70 to effect oscillation of the index table. Each work-table 14 is rotatably mounted in bearings 90 on the index table and has a gear 83 engaged by a gear 82 of an hydraulic motor 80 connected by lines to a valve 94 and a source 106. The valve can be positioned to prevent flow to the motor 80 when its table is at the load/unload station 18, to cause rotation of the table in one direction at one of the grinding stations, but to cause rotation in the opposite direction at the other grinding station. During grinding, the work-table is rotated at a relatively low speed determined by the back pressure of a valve 114. During spark out, a valve 118 is opened so that the back pressure is reduced by flow through valves 114, 116 and the rotational speed of the work-table is relatively high. The grinding stations 24, 26 are identical apart from the grade of the grinding means. Each station has a column 28 mounted for pivotal movement about a horizontal axis provided by bearings 121, Fig. 2, the centre of gravity acting, together with an hydraulic cylinder 122, to urge the grinding means upwardly and away from the work-tables. The circuit to the cylinder 122 includes a check valve 142 and adjustable orifice 144 connected to a source 146. A valve 148 can be to set regulate the pressure supplied to the cylinder and biasing the column away from the work-table. A jack 126 acts against the force of cylinder 122 and gravity acting on the column to pivot the column about the axis of the bearings 121. The jack is mounted on the base 10 of the machine and has an extensible element 174 consisting of a plunger 176 which is slidable in a bore 178 when fluid pressure is supplied through a passage 180 and has a concave-shaped shoe 172 engaging a spherical bearing surface 170 on the underside of the column. In the event of malfunction of the machine, relief of pressure in passage 180 results in a relatively large movement of the grinding means away from the workpiece. The passage 180 is connected by a line 182 to a check valve 184, adjustable orifice 186 and pressure regulating valve 194. The lower end of the extensible element 174 is connected by a bearing 202 to a screw 200 which is rotatable relative to a nut 206 and has a splined bore in engagement-with a splined shaft 222 connected to a gear 224. A worm-wheel 214 secured to the nut can be rotated by a worm 216 and hand crank 218 to effect initial adjustment of the grinding means, infeed of the grinding means being effected by rotation of the screw by rotation of the splined shaft 222 as a result of movement of a rack 226 engaging the gear 224. The rack is movable by an hydraulic cylinder 230 to effect rapid and fine infeed and retraction controlled by adjustable orifices 236, 244, 252 and valves 240, 262 actuated by dogs 270, 272 on an extension 228 of the rack operating switches 274, 276, 278. Switch 276 terminates the infeed to provide "spark-out" grinding and actuates valve 118 to effect the rapid rotation of the work-table, as referred to earlier. Each column 28 has a pair of side plates 290, 292 housing a motor 34 connected by a belt 296 to a shaft 298 mounted in a bearing 300 and supporting an abrasive belt 302. The side plates are supported by shafts 318, 320 in the bearings 121. The shaft 320 has an eccentric portion 322 within its bearing 121 and is rotatable by gearing 324, 326 and a hand wheel to cant the column and adjust the parallelism between the abrasive belt and the workpiece.