Patent GB-1316789-A (GB)
Title: Device in grinding machines
IPC: B24B49/16
Filed: 1970-06-17
Abstract: 1316789 Grinding UVA AB 17 June 1970 [18 June 1969] 29368/70 Heading B3D A grinding machine in which a workpiece 6 and a grinding wheel 3 mounted on a spindle 2 are each rotatable about respective axes, comprises a feed mechanism for effecting relative radial displacement between the workpiece and wheel, and a measuring device operable in response to deflection of the spindle, the feed mechanism being adjustable to a displacement which comprises firstly a given removal of material from the workpiece and secondly a value corresponding to the deflection. The measuring device may be electrical or, as described, pneumatic and consists of a nozzle 10 connected through adjustable valves 15, 17 to a compressed air source 11 and to one 22 of a pair of pressure chambers, the other 24 of which is connected by a pipe 25 to a nozzle 30 co-operating with a surface 31 of a cam 32. A spring 34 urges the cam into engagement with a member 35 on a calibrated disc 36 on a shaft 39 which is coupled to the feed mechanism 4 for the grinding wheel and has a pinion 101 meshing with a rack 100 formed on the rod of a piston 71 in a cylinder 72. A chamber 104 on one side of the piston is connected by a valve 63 to a pump 59, and a chamber 70 on the other side of the piston is connected by selectively operable throttle valves 92 ... 95, which control the speed of the feed, to a sump 60. A lever 40 is mounted on a point 42 and connected to a partition between the pressure chambers 22, 24 and can be coupled by a clamp 43 to an actuator 50 of a switch 55. In operation, the grinding wheel is initially moved to bear against the workpiece 6 and the valve 15 is adjusted so that an indicator 56 registers zero for a predetermined load pressure on the spindle and the position of the cam 32 corresponds to the deflection of the spindle, the pressure in chambers 22, 24 being then equal. The calibrated disc 36 is then turned to the working depth, the movement of the cam altering the pressure in chamber 24 so that lever 40 is moved and one of the valves, say 92, is actuated to control the feed rate when the pump 59 is operated and the grinding wheel and workpiece are rotated, the pump supplying fluid to chamber 104 moving the piston 71 to the left so that the shaft 39 is rotated to actuate the feed device and the disc 36 turned until the member 35 moves cam 32. When the pressure is equalized in chambers 22, 24, the feed taking into account the deflection of the spindle and required feed is completed and the lever 40 moves actuator 50 to operate switch 55 and effect a rapid return of the grinding wheel. During grinding, the grinding wheel is reciprocated axially. A finishing operation may be effected by movement of a piston 78 which can be coupled by a clamp 162 to the rod 141 of a servomotor 133, 134 having an actuating lever 136 connected by a rod 26 to the lever 40. Movement of the lever 136 at the start of the grinding operation causes oil to be sucked into space 76 through a one-way valve by an amount proportional to the deflection of the spindle. When the finish size as set on the calibration disc 36 is reached, the fluid is supplied to space 70 so that grinding is effected at low pressure. A piston 170 is provided in cylinder 72 for moving the grinding wheel to a dressing position.