Patent GB-525743-A (GB)
Title: Improvements in machines for grinding cutter blades particularly gear cutters
IPC: B24B3/02
Filed: 1939-02-27
Abstract: 525,743. Grinding-machines. GLEASON WORKS. Feb. 27, 1939, No. 6476. Convention date, June 29, 1938. [Class 60] In a machine for sharpening gear cutters a conical grinding wheel rotates on its own axis and is swung in a circular path simultaneously about an inclined axis so as to pass the wheel across the surface of the work to be operated upon. Parallel guideways 21, 22 formed in the upper face of a machine bed 20 support a carriage 25 having a head 28 in which a grinding wheel W is mounted. A, motor 35 secured to the bed 20 rotates the grinding wheel continuously through a belt 34, pulley 38 on a telescopic shaft 39 and bevel gears 41, 42, 45, 46 mounted in the carriage 25. Simultaneously, a main motor (not shown) geared to a pinion 77, Fig. 4, rotates that pinion which meshes with a pinion 78 on a shaft 79 having a splined connection with one of a pair of bevel gears, the other gear of the pair being keyed to a vertical shaft carrying a crank 50. An arm 58 journalled on the crank pin of the crank 50 and also arranged to pivot about a horizontal axis connects the crank arm 50 to an arm 65 secured to the head 28, which is itself rotatable, and is thus oscillated to traverse the grinding wheel over the cutter. Work adjustments. The cutter C to be ground is mounted on a shaft rotatably adjustable about its own axis and disposed in a casing 91 carried by trunnions 112 in a head 113, the casing being adjustable about the trunnions by a worm 122. The head 113 may be adjusted along a slide 92 rotatably mounted on a post 97 which may be adjusted vertically in a slide 26 movable across the end of the bed 20 by a handwheel 100. As shown in Fig. 1, the work consists of a face-mill gear cutter but if the slide 92 is turned on the post 97 through 90 degrees a disc-type gear cutter may be sharpened. Wheel feeding mechanism. The head 28 carrying the grinding wheel W is supported by a sleeve 30 slidable in a casing 33 forming part of the carriage 25 and the casing 33 rests upon a head 146 supported through a follower 140 by a double cam 132, 133 carried by a shaft 130 continuously rotated by the pinion 78 through a gear train terminating in a bevel gear 158 secured to a cam 162 on a sleeve 164 splined on the shaft 130. The two surfaces 132, 133 of the double cam provide respectively for rough and fine cutting and are brought into operative position by sliding axially a sleeve 137, in which the shaft 130 is journalled, by a rack and pinion 144, 142 operated by a hand lever 143. At the end of the grinding operation, a lever 170 actuated by the cam 162 withdraws the carriage 25, removing the grinding wheel from the cutter. The lever 170 has an adjustable connection with the carriage 25 to adapt it to cutter blades of different heights. The sleeve 164 also carries another cam, 180, which rocks a lever 182 connected by a link 190 and rod 191 to a piston 192 movement of which rotates the cutter to bring another tooth into position to be operated upon and locks it there. The piston 192, Fig. 17, operates in a cylinder 193 connected at its ends by pipes 211, 212 with the ends of a cylinder 210. Displacement of the piston 192 causes corresponding movement of a piston 214 in the cylinder 210 and a rack 220 which is connected to the piston 214 and engages a toothed segment 223, Fig. 15, on a bush rotatably mounted on the journal of the work spindle 90 to rotate the bush. A lug 228 on the bush carries a spring pressed pawl 229 adapted to engage the segment 223 secured to the work spindle 90. Pivoted about a pin 241 in the housing 242 of the indexing mechanism is a spring-pressed locking dog 240 having pivoted to its underside a trip-dog 250. A trip rail 245 carried by the lug 228 engages an inclined edge on the trip-dog as the disc 223 is rotated by the rack 220 and frees the dog 240 from the disc 223 permitting the pawl 229 to turn the disc until the trip rail 245 clears the trip-dog 250 and the locking dog 240 engages the next notch in the disc 223. When all the teeth have been ground, the carriage 25 is retracted completely, the pivot of the lever 170 being mounted on a slide 172 connected to a piston 260 displaced hydraulically in a cylinder 263 under control of a valve 265 which, during the grinding operations, is held against the pressure of a spring 269 by a detent 275 adapted to be released when a solenoid 277 is energized under control of a stop-mechanism actuated by a cam 259 on a rod 257 secured to the sleeve 164. While the carriage is retracted, a trueing diamond 295 is brought into operative position against the grinding wheel W by the movement of the slide 172. The slide rocks a lever to open a valve 305 in the hydraulic system permitting oil to be pumped past a shut-off valve 328, and a safety valve 334 to a cylinder 301 to raise a piston 300 on the rod 297 of which the diamond is adjustably mounted. The safety valve 328 is located adjacent the valve 265 controlling the slide 172 and can be opened only when the latter has been opened, the opening of the valve 328 then preventing closure of the valve 265. The valve 334 ensures that the diamond is not moved except when the carriage is at the end of its movement. A pin 352 secured to the valve engages a cam track 355 on the cam 180 to keep the valve normally closed. To ensure that the wheel comes to rest at the centre of its traverse, a piston 363, operated by the power fluid flowing to the piston 297 supporting the diamond, displaces a bar 360 into engagement with a flat on the crank plate 50. A screw shaft 398 disposed in a nut 145 non-rotatably held in the head 146 is rotated through bevel gears 397, 396 a shaft 394 and pinion 376 engaged by a ratchet 375 which is actuated by a piston 379 in a cylinder 380 in circuit with the valve 334 and the cylinder 300 for raising the diamond, the movement allowing for wear in the grinding wheel. Manual operation of the valve 265 is required to return the carriage to its operative position after it has been fully retracted therefrom and the main driving motor cannot be energized until a switch 415, Fig. 3, has been closed by movement of the pinion 363 and bar 360 and a second switch 425 by a cam 426 on the carriage 25 itself. To start the machine, the motor driving the hydraulic pump is first switched on, then the motor 35 for driving the grinding wheel and lastly the main driving motor, the last two motors being switched on through relay circuits of which that operating the motor 35 is dependent for the completion of its circuit upon a contact made in starting the pump motor while the relay starting the main motor is in a circuit dependent upon the relay circuit for the grinding wheel motor 35. A pilot light indicates when the carriage 25 is in its fully-retracted position and the main motor at rest.