Patent GB-561890-A (GB)
Title: Improvements in grinding machines
IPC: B24B47/06
Filed: 1941-08-08
Abstract: 561,890. Controlling grinding machines. BRYANT CHUCKING GRINDER CO. Aug. 8, 1941, No. 16398/43. Convention date, Nov. 9, 1940. Divided out of 560,809. [Class 60] A grinding machine comprises a fluid power system for traversing a'carriage including an axially and angularly movable control valve which is engaged by abutments projecting from the carriage to define the limits of traverse in dependence on the axial setting of the valve, the angular position of which also determines the direction of traverse ; means are also provided for effecting a cross feed. The grinding tool carriage, as shown, is furnished with a cylinder 159 enclosing a fixed piston to the opposite sides of which oil under pressure can be admitted to effect the traverse in opposite directions by pipes 175, 180 connected through the valve system to a reservoir 350. The system includes a control valve 400 which is adjustable axially and co-operates with projections 448, 449, 430, 465 or 467 carried by the carriage and is fitted with a pinion 406 engaging a rack on the end of a pilot valve 355 housed in a casing together with a reversing valve 356. A separate casing 358 encloses a shut-off valve 360 and a manually-operable control valve 359. The parts are shown in the automatic grinding position of the valve 400. Oil is forced by a pump 351 to the casing 3540 for the reverse and pilot valves through a port 365, passes through a port 369, round a neck portion 370 of the pilot valve, through a passage 371 in this valve to a port 372 and passage 373 to the left hand of the reversing valve. It also passes from the port 365 to a pipe 375, round the neck 376 of the shut-off valve 360, through a passage 377, round a neck 378 of the manually-operable control valve 359 and out through a port 379 to the pipe 175, thus forcing the cylinder 159 to the left to produce an inward traversing movement. Discharge from the opposite end of the cylinder 159 takes place through the pipe 180 round a neck 381 of the valve 359, through a port 382, round a neck 383 on the valve 360, a pipe 385, port 386, neck 387 on the reversing valve 356, port 388 and passage 389 to the port 390 of the pilot valve 355, port 392 and pipe 393 to a valve casing 394. The latter contains a rocker valve 395 with a restricted port 396, the degree of opening of which is set by turning the valve 395 to determine the rate of discharge, and with a port 397 always wide open. During grinding, discharge takes place through the port 396 into a pipe 398 leading to the control valve 400.' The latter can be set axially to four positions for " grinding," "dress," "stop" and "fast" by a control handle. In the grinding position the discharge passes from the control valve to pipes 413, 414 leading to a rockable valve 416, thence to the discharge pipe 419. When the cylinder 159 approaches the inward end of its travel, the dog 430 engages a head 431 on the valve 400 to turn it, which movement effects a longitudinal movement of the pilot valve through the rack 405 and pinion 406, the movement being completed by oil pressure behind the shoulder 3551. When the pilot valve 355 moves to the left, the passage 371 is moved out of register with the port 369 and a passage 435 registered with that port, oil passing through the. port 437 and passage 438 to the pipe -439 and to the righthand end of the reversing valve 356. The lefthand end of the reversing valve discharges through a pipe 374, passage 373 and valve port 372, thence round a neck 441 on the pilot valve, through a port 442 and passage 444 to the discharge line 419. With the reversing valve in a left-hand position, oil passes from the pipe 352 through the port 365, round the neck 387 of the'reversing valve, through the port 386 to a pipe 385 leading to the valve casing 358, passage 382 and pipe 180; this drives the carriage in the reverse direction, discharge from the cylinder 159 taking place through the pipe 175 and the movement continuing until a dog 448 engages the head 431 of the valve 400 to rock it, thus repeating the cycle. When the valve is lowered to the "dress" position, the cylinder 159 is permitted an extended traverse, reversal being effected by a dog 449. The port 399 is shut off and discharge is effected through the pipe, 413 permitting'the carriage to retract at normal speed until the wheel approaches the dressing position when a dog 465 engages the ears 466 to turn the valve 416 to shut off the port 417. Discharge then takes place through the throttle valve 421 and pipe 414 at a reduced rate, thus effecting slow traverse during wheel dressing. Automatic reversal of this extended stroke is effected by the engagement of the valve 400 by the dog 449. With the valve 400 in "stop" position the ports 455 and 456 are open and communication is effected between opposite ends of the cylinder to stop the. tool carriage. When the valve 400 is further depressed to " fast " position the unrestricted pipe 426 is opened, permitting rapid discharge from either end of the cylinder 159. The traverse may be manually controlled by means of a hand'lever 475 operating the valve 359. The valve 400 may also effect relative .lateral feed of the tool and work through a ratchet mechanism operated by a plunger 95 at a rate determined by the setting of a throttle 561.