Patent GB-845983-A (GB)
Title: Improvements in or relating to machines adapted for use in the manufacture of ceramic ware
Inventor: CHOICE FRANK COLEMAN
IPC: B28B11/18
Filed: 1955-07-25
Abstract: 845,983. Making pottery. BRITISH UNITED SHOE MACHINERY CO. Ltd., and CHOICE, F. C. Oct. 23, 1956 [July 25, 1955; Oct. 19, 1956], Nos. 21403/55 and 31829/56 Class 87(1) [Also in Group XXIII] A machine for towing a workpiece in the manufacture of an article of ceramic ware includes edge-fettling and edge-towing tools. The machine frame 30 comprises a table 34 supporting by pillars 36 a platform 38; the frame 30 supports an electric motor 46. The work support S comprises a metal disc 48 carrying a plaster head 50 the rim 52 of which has a felt covering 54. The disc 48 is secured to a sleeve 58 supported in bearings 60, 62 in the platform 38 and table 34. A clutch member 90 keyed to the sleeve 58 is movable to engage either a friction surface 88 on a gear 72 rotatably supported by the bearing 62 or a friction surface 86 on a flange 82 secured to a gear 76 rotatably supported by the sleeve 58. The gears 72, 76 mesh with gears 1.20, 122 on a shaft driven, through bevel gears 116, 118, from a shaft 114 driven, through belt 108, by the motor 46. The gear ratios are such that the slow speed of the work support is 50 R.P.M. and the fast speed 500 R.P.M. The clutch member 90 is moved up or down from its neutral position by a yoke 98 pivoted at 100 to the frame 30 and connected at 104 to a treadle rod 106. The treadle rod 106 is operated by a pedal 132 so constructed that initial depression causes the slow speed to be engaged and further depression causes the fast speed to be engaged. When the pedal 132 is returned to its rest position by a spring 134 a brake 144 is applied to a collar 64 on the sleeve 58. A rotatable yieldable towing tool T comprises a circular brush 182 with radial bristles and a disc of felt 184; the tool spindle runs in a housing 186 mounted by opposed axially-aligned screws 188, 188 on a slide 190; an adjusted position of the housing 186 about the axis of the screws 188 is determined by stop screws 192, 192. The slide 190 has an arcuate tongue riding in an arcuate groove 200 in a composite rocking arm 196; a screw 202 passes through one of two holes in the arm 196 and into a tapped hole in the slide 190. The tool is driven, through a belt 206, from a shaft 224 driven, through a belt 226, from the shaft 114 which drives the work spindle. One guide pulley 212 for the belt 206 is so mounted as to keep the belt at substantially constant tension despite movements of the tool. The rocking arm 196 carrying the tool T comprises two aluminium alloy castings 240, 242 coupled together by rods 244, 246, and is pivotally mounted by pins 252, 254 on a carrier 250. The rear end of the casting 242 carries a weight 256 urging the arm to rock upon the pins to lift the tool T. The rod 246 passes through an arcuate slot 261 in a cam-follower arm 258 mounted upon the pin 254 and carrying a cam roll 260; the weight 256 is not heavy enough to lift the arm 258. The carrier 250 is supported by a link 262, being pivoted thereto at 268; the link 262 hangs from a spindle 266 mounted on a pedestal 264 on the platform 38. Also pivoted to the carrier 250 at 268 is a hollow bracket 269 pivotally supported by a spindle 304 in a casing 310 and coaxial with the spindle 266. Pivoted to the bracket 269 at 271 is a handle 270 having an elongated slot 272 with three recesses 274, 275, 276 selectively receiving a pin 280 mounted on the platform 38, so that the bracket 269 and link 262 can assume any one of three positions according to the shape of the workpiece. The cam roll 260 rests upon a cam plate 282 replaceably mounted on the platform 38 and having a cam surface 288 with the contour desired for the workpiece along a radius of the upper surface; the plate 282 has a rear abutment 290 to determine a position of rest of the arm 258 and a forward stop 292. In use, the operator rocks the arm 196 about the pins 252, 254 to bring the rod 246 to the forward end of the slot 261 and the carrier 250 is then rocked about the axis 268 causing the arm 258 to push the cam roll 260 forwardly along the cam surface 288. Power operated means for rocking the carrier 250 comprises a gear segment 300 secured to the carrier 250 and meshing with a gear 302 fixed on the spindle 304. A toothed clutch member 312 is secured on the spindle 304, and a complementary toothed clutch member 314 is slidably mounted to engage it; the clutch member 314 comprises a wormwheel 316 meshing with a worm on a vertical shaft driven through a belt 324 from a pulley 66 on the work spindle 58. Movement of the clutch member 314 is effected by a bell-crank lever 325 pivoted at 326, urged in one direction by a torsion spring 327 and operated in the other direction by a Bowden cable 334. The sleeve of the cable is secured at one end to the casing 310 and at the other end to a slide 342 adjustable on a latch 344 pivoted at 346 to the cam-follower arm 258 and having a depending part 348 co-operating with the stop 292 of the cam plate 282. The internal wire 332 of the cable is secured to a block 360 slidable on the slide 342 and having a lip 362. When the operator rocks the composite arm 196 about the pins 252, 254 to bring the rod 246 towards the forward end of the slot 261, a trip element 364 on the casting 242 engages and depresses the lip 362; -the latch 344 is biased by a spring 366 and the trip element 364 becomes lodged between the lip 362 and the slide 342 thus preventing the weight 256 from rocking the arm 196 back again and also keeping the wire 332 pulled relative to the sleeve so as to maintain the clutch members 312, 314 in engagement. The gear 302 thus rotates causing the carrier 250 to rock about the axis 268 so that the cam follower arm 258 is pushed to carry the cam roll 260 along the cam surface 288. After the tool T has reached the centre of the blank B the depending portion 348 of the latch 344 engages the stop 292 on the cam plate 282; further forward movement of the arm 258 causes the latch to rock about the pivot 346 to release the trip element 364 from between the lip 362 and slide 342. This release permits the arm 196 to rock, under the action of the weight 256, until the rod 246 engages the rear end of the slot 261 and also permits the spring 327 to disengage the clutch 312, 314. The spindle 304 is automatically returned to its starting position by a spring 372 connected to a wire 370 passing around a pulley 368 on the end of the spindle 304; the carrier 250 and arm 258 are thereby returned to positions of rest determined by engagement of the cam roll 260 with the abutment 290 on the cam plate 282, so concluding an operating cycle. The cam plate 282 has a slot 380 to receive a holder 382 for tools for fettling and towing the edge of the workpiece. The holder 382 comprises a block 384 slidable in the slot 380 and having legs 386 engaging the sides of the plate 282; the position of the holder is determined by a screw 388 passing through holes in the legs 386 and the plate 282. The holder 382 also comprises a fettling tool support 392 and an edge-towing tool support 394, both mounted on the block 384 by a pivot 396. Pivoting of the support 394 in one sense is limited by an abutment 398 of the support engaging a pin 390 and in the other sense by an adjustable stop screw 400 engaging the pin. Pivoting of the support 392 is similarly limited by an abutment 402 and screw 404. The supports 392, 394 have co-operating abutment surfaces allowing only small relative movement. The supports 392, 394 are urged into their rest positions by springs 406, 408 and have handles 412, 414 by which they can be rocked. The support 392 carries a fettling tool F comprising a strip 416 of spring steel with a V-shaped notch at one end. The support 394 carries an edge-towing tool E comprising a bar 420 secured to the support; a block 422 is secured to the bar by a headed screw 426 and spring washer 428 so that the block can be turned against frictional resistance about the axis of the screw. The block 422 has a recess 424 in which is held by screws 430 a member 432 around which is a circular band 434 of towing material, viz., emery paper on a flexible rubber backing. The band 434 is long enough to form a loop within the member 432, this loop engaging the edge of the workpiece. The band 434 is held in position by. a finger 436 secured to the block 422 by a screw 438 and having an inturned lip 440 so that tightening of the screw increases the pressure of the finger on the band. After loosening the screw the band 434 can be turned to present an unworn portion to the workpiece. The work support S comprises means for assisting the operator in placing a workpiece centrally upon the rim 52 and suction means for holding the workpiece in place on the rim. Screwed into the upper end of the sleeve 58 is a hollow bolt 450 with an upstanding portion 452 on which is slidably mounted and keyed a member 456 urged upwardly by a spring 476 and having an annular upper surface 457. On this surface rests a metal annulus 458 with an internal depending skirt 460 whose external diameter is less than the internal diameter of the surface 457. The upper surface of the annulus has a felt covering 462 of greater external diameter than the annulus. The annulus 458 is retained on the member 456 by spring-pressed catches, each pivoted on a pin on the member 456 and having a lip overlapping the lip of the annulus; each catch is urged by a spring- pressed poppet into engagement with the annulus. The arrangement is such that the annulus 458 assumes under its own weight a position substantially coaxial with the sleeve 58; the springs are not strong enough to centralise it if a workpiece is resting on it nor to offer much resistance to displacement. A rubber suction cup 478 is secured to the top of the bolt 450 by a hollow screw; from the bolt 450 a tube 482 descends through the sleeve 58 and is connected to a valve V connected to a suction pump 490 driven through belt 491 by the motor 46. A two-armed le