Patent GB-1017813-A (GB)
Title: Improvements in or relating to machines adapted for use in making pottery
Inventor: PEARCE NORMAN
IPC: B23B31/30
Filed: 1961-12-08
Abstract: 1,017,813. Grinding; machine tool details. SERVICE (ENGINEERS) Ltd. Dec. 6, 1962 [Dec. 8, 1961], Nos. 44055/61 and 13475/62. Headings B3B and B3D. A machine for smoothing the outer surfaces of hollow-ware blanks in the manufacture of pottery comprises a rotatable work support 32, Fig. 1 (not shown), on which a blank C may be gripped, and a work-engaging element 28 which is moved so as to stroke a side-wall of the blank. The work support grips the blank C in an inverted position and rotates it while the work engaging element 28 strokes its side, a second element 30 smooths its bottom, and a third element abrades its edge. The blank may be in the form of a cup without a handle and is held on the work support by a rubber annulus 40, Fig. 10 (not shown), which is expanded to grip the blank upon movement of a flanged member 44 towards a part 38 when air under pressure is supplied to a space 52. The part 38 is adjustably mounted on a rod 68 having at its lower end one member 84 of a clutch for co-operation with a second member 82, which is secured to a pulley 80 continuously rotated during operation of the machine, when the rod 68 is lifted by a lever 98 having a follower 102 co-operating with a cam 106 on a shaft 108. The vertical movement of the rod also lifts the blank from a gauge 120 adjustably secured to a sleeve 72 on a mounting plate 24, the gauge serving to position the blank prior to its being gripped by expansion of the member 40. The side of the blank is smoothed during rotation by one of three sponge pads 146, Fig. 6 (not shown), of the first work-engaging element 28. Each pad is secured to a holder 144 at the end of an arm 124 which is urged to a work-engaging position about a pivot 130 by a spring 138, the pivots being mounted on a disc 126 keyed to a shaft 156 and adjustable axially thereof by a threaded spindle 162. The shaft 156 is connected to a gear 170, Fig. 3 (not shown), meshing with a gear 180 which is mounted on an arm 178 and is joined to a pulley 184 driven by a belt 186 from a pulley 188 on a cam-shaft 190 continuously rotated by a chain 326 during operation of the machine so that the shaft 156 rotates 120 degrees during each cycle of the machine to bring each pad 146 in succession into engagement with successive workpieces mounted on the work support. The arm 178 has a follower 192 on its lower end engaging a cam 194 on the shaft 190 so that during each cycle the arm 178 and gear 180 are rocked about the axis of the shaft 156 whereby, after the pad has moved over the side wall of the blank, the rotation of the shaft 156 is stopped and reversed to bring the pad back into engagement with the edge of the blank before rotation of the shaft is continued to bring the following pad into engagement with the next blank positioned on the support. After leaving the blank, the pad passes through a trough 201, Fig. 1, of water and then between a plate 207 and roll 203 which squeezes surplus water from the pad. A second cam 236 on the shaft 190 co-operates with a follower 234 on one arm 232 of a lever, the other arm 228 of which has a quadrant engaging a second quadrant 226 connected to a lever 220 which is thereby rocked during each cycle of the machine to bring the second work-engaging element 212 comprising a sponge pad into engagement with the bottom of the blank. A third cam 274 on the shaft 190 co-operates with a follower 270 on a lever 268 connected by an adjustable link 266 to a lever 264 mounted on a shaft 260 which is rotatably mounted in the housing 26 of the machine and carries an arm 252 supporting an abrasive stone 254 which is thereby brought into engagement with the edge of the blank once during each cycle of the machine. The machine is driven from an electric motor 290, Fig. 4, connected by a belt 296 to a variable-diameter pulley 298 which is mounted on a bell-crank lever 302 movable about a pivot 304 by a rotatable spindle 336 to vary the tension in the belt and hence the diameter of the pulley 298 and the speed of the machine, the pulley being connected by a belt 314 and transmission 320 to the shaft 108 carrying the cam 106 for operating the clutch 82, 84 on the work support, a cam 110 controlling a valve 112 for supplying air to the space 52 of the work support, and a sprocket 322 connected by the chain 324 to the cam-shaft 190. The machine may have two or more heads and the blanks may be fed from a conveyer to the heads by a transfer device which subsequently removes them to the same or another conveyer.