Patent GB-1390567-A (GB)
Title: Generating a surface of revolution
IPC: B24B41/06
Filed: 1973-02-21
Abstract: 1390567 Grinding RCA CORPORATION 21 Feb 1973 [28 Feb 1972] 8452/73 Heading B3D [Also in Division B8] A machine for generating a surface of revolution 210, Fig. 8a, on a hollow workpiece 174, such as a deflection yoke of ferro-magnetic material for a television receiver, substantially concentric with the mean axis 202 of an irregular inner surface of revolution 201 of the workpiece, the workpiece having a surface 213 concentric with the axis, comprises a base 12, Figs. 1 and 2, a workhead 16 mounted on the base, workpiece support means 100 on the workhead, indexing means 92 connected to rotate the workhead and cause the support to move to a workstation 72, and a wheelhead 20 mounted on the base and having a wheel 27 movable into engagement with a workpiece at the workstation, the workpiece support including a plurality of spaced resiliently-mounted support members 246, Fig. 6, engaging points on the irregular inner surface of the workpiece and including a mandrel 256 for gripping the surface 213 to make the mean axis 202 of the workpiece intersect the apparatus axis 222 of the workpiece support As described, the workhead has six workstations 70 ... 75. A workpiece is loaded on to a support at station 70 and indexed successively through station 71 where it is clamped to the support, station 72 where the surface 210 is formed by a grinding head 20, station 73 where a surface 208 is formed by a grinding head 30, station 74 for the grinding of surface 206 by a head 40, and station 75 where the workpiece is transferred by a device 60 to a station 80 of a second workhead 18. The workpiece is clamped to a rest 142 at station 80 and the workhead indexed to carry the workpiece to station 81 where a surface 204 is formed by a grind head 50, the workpiece then being indexed through station 82 for unloading at station 83. The workhead 16 consists of a table 90 mounted on an indexing head 92 which also drives through a coupling 134 the workhead 18 for simultaneous indexing movement. The support at each workstation consists of a housing 220, Fig. 6, for a shaft 240 which is mounted in bearings in the housing and has a truncated conical head portion 244. Three rigid support members 246 are mounted on the head portion in a plane 252, Fig. 7, slightly below a plane 254 containing three resilient support members 248, all of the support members being arranged in an imaginary cone 249 having its apex 250 on the apparatus axis 222, and the support members being arranged to engage the inner surface 201 of the workpiece. The head portion 244 also has a recess into which the mandrel 256 is secured. The mandrel consists of a block 258 in which areapluralityof fingers 260 mounted on pivots 261 in the block 258 and which can be urged by a cam 277 into gripping engagement with the surface 213 of the workpiece. When the workpiece is placed on the support it is received by the resilient members 248 which, as the fingers 260 are caused to grip and centre the workpiece, permit the workpiece to be tilted and axially displaced, if necessary, until it engages at least one of the rigid support members 246. The tilting of the workpiece is also effected by a surface 284 of a drive ram housing the cam 277 which is resiliently supported on a stud 274 in a bushing 270 on which is supported for sliding movement against springs 280 a sleeve 272 having a rubber washer 282 providing the drive surface 284, the bushing being secured to a shaft 172. Each support has an associated drive ram on a shaft 172 which is carried for axial movement and rotation in a bearing box 170, Fig. 3, from a plate 162 supported by struts 122 and a column 124 from plate 90 of the workhead 16. The shaft is axially moved by a pneumatic ram 188 between an upper, inoperative position, and is lowered to engage the cam 177 with the fingers 260 and the surface 284 with the workpiece. In the lower position, a bevel gear 180 is engaged with a gear 168 of a respective motor 164 mounted on the plate 162. The upper end of the column 124 is rotatable relative to a member 312 secured to an assembly carried by an arm 126 on a post 126 secured to the base 12, the arm and post providing pneumatic and electrical supply to the rams 188 and motors 164. Cams 344 and 346 are mounted on the member 312 and acuate limit switches 326 and valves 314 to control the rams 188 and motors 164. The arrangement is such that the motors rotate the work supports at the stations 72, 73 and 74 for grinding of the workpieces by the units 20, 30, 40. The grinding wheels, which are of diamond, are advanced tangentially in the units 20, 30, and radially in the unit 60 by pneumatichydraulic means 25, 35, 46 and are rapidly retracted pneumatically. After grinding of surface 206 at station 74, the workpieces are indexed to station 75 and the shaft 172 raised at that station to release the workpieces. The workpiece is transferred from station 75 on workhead 16 to station 18 on workhead 19 by the device 60 which has a pair of clamping fingers 382, 384, Fig. 10, movable about pivots by a toggle linkage 376 actuated by a ram 374 to grip the surface 208 of the workpiece. The ram and linkage are mounted on an arm 372 of a shaft 356 which is axially movable by a cylinder device 354 to raise the workpiece until a gear 368 on the shaft engages a rack 392 movable by a cylinder 394 to rotate the shaft and position the workpiece over a rest 142, Fig. 2, at station 80 whereupon the workpiece is released to drop on to the rest. The arm 372 can only be lowered above station 75 when a pin 362 secured to the shaft engages a hole in a fixed member 360. The transferred workpiece is clamped on to the rest 142 by spring-pressed finger-like jaws 138. After grinding of the surface 204 by a radially-movable grinding wheel 51 of unit 50, the workpiece, which is not rotated on the workhead 18, passes through station 82 to station 83 wherein the jaws are forced against a spring 144 to release the workpiece for unloading by air-operated assemblies 146, 147. The operation of the machine is automatically controlled by an electrical circuit.