Patent GB-829063-A (GB)
Title: Improvements in or relating to devices for use with grinding machines for compensating reduction of material in the grinding disc
IPC: B24B49/18
Filed: 1958-03-21
Abstract: 829,063. Grinding. LINDNER G.m.b.H., H. March 21, 1958 [April 17, 1957], No. 9212/58. Class 60. A device for adjusting the amount of movement of a feed carriage 6 of a grinding wheel 1, particularly on a thread grinding machine, to compensate for the reduction in size of the wheel resulting from the extent of trueing as adjusted by a trueing device 3 comprises a dog 23 which is drivable by a compensating mechanism 22, 31, 34, 35 and capable of being connected by a clutch 19 to a feed adjustment spindle 7, impingement of the dog in one direction of movement against a stop 25, infinitely variably adjustable to correspond to the reduction in size of the grinding wheel resulting from trueing, actuating means to disengage the clutch and reverse the direction of movement of the driving mechanism until the dog impinges against a fixed stop 24. The grinding wheel, which has a screw thread profile, is fed towards or away from the workpiece 2 by connection of a handwheel 17 to the spindle 7 by means of a clutch 14, which is preferably electro-magnetic, and gears 10, 11, 12, 13 ; an automatic feed may replace the manual adjustment. The reduction in size of the grinding wheel effected by the trueing device 3, which may comprise a diamond 4 or profiled roller, is compensated for by disengaging the clutch 14 and engaging a similar clutch 19 so that movement of the piston 34 and rack and pinion 22, 31 can be transmitted to the spindle 7 and carriage 6 by an amount determined by the dog 23, which is secured to the same shaft as the pinion, impinging against the stop 25 mounted on a wheel 26 which can be rotated to a predetermined position corresponding to the depth of trueing by a worm 27 on a shaft 28 having a graduated scale 30 and knob 29 at its other end. The direction of movement of the piston is controlled by valves 40, 43 which are operated respectively by solenoids 48, 50 actuated by switches 45, 46, 52 and relays 53, 54. In operation, .the stop 25 is adjusted by means of the knob 29 and scale 30 to correspond to the required compensation movement, which is determined by measurement of the error of a piece of work following a preliminary trueing of the wheel, such error being taken into account in adjusting the stop to compensate for the final trueing, and the switch 52 operated manually or automatically to actuate the relays 53, 54. The contacts of the relays disengage clutch 14, engage clutch 19, and energise the solenoid to position the valves 40, 43 so that a pump 39 supplies fluid to urge the piston 34 upwards and, by means of the clutch 19 and gears, feed the carriage 6 towards the workpiece until the dog 23 impinges against the stop 25. The movement of the piston is thus stopped and the pressure in the line 36 increases to operate the switch 45 which de-energises the relay 54 to re-engage clutch 14 and disengage clutch 19, and actuates the solenoid 48 to reverse the valve 43 and supply fluid through line 37 to the upper end of the cylinder 35. The downward movement of the cylinder is thus stopped by the dog 23 impinging against the fixed stop 24, the consequent rise in pressure of the fluid in the line 37 operating switch 46 to de-energise the relay 53 and return the valve 40 to its initial, inoperative position. The trueing device may be set in operation by an additional contact on the switch 52 or by a control switch operated independently of the instruction to effect compensation.