Patent GB-1435070-A (GB)
Title: Plural station grinding machine systems
IPC: B24B49/16
Filed: 1974-10-26
Abstract: 1435070 Grinding SUNDSTRAND SYRACUSE 26 Oct 1974 46408/74 Heading B3D [Also in Division G1] A plural station grinding machine comprises a grinding wheel 10, Fig. 1, at each station A, B arranged for simultaneous operation on a workpiece W, means 24, 25, 24<SP>1</SP>, 25<SP>1</SP> associated with each grinding wheel for driving the associated wheel at a variable rate of speed, means for determining the actual surface speed of each wheel, and means for controlling the driving means to have each grinding wheel operate with the same surface speed. As described, the machine is of the centreless grinding type and the effect of the same surface speed of the grinding wheels avoids torque being applied to the workpiece. The control may also be applied to the regulating wheels 11, 11 of the machine. The surface speed of the grinding wheels is set by a control 20 which supplies an analog output signal to summing units 21, 211 associated with each station, each unit also receiving a surface velocity analog for its wheel from a respective multiplier 22, 22<SP>1</SP> provided with signals from sensing mechanisms 32, 32<SP>1</SP>, which detect the size of the grinding wheels, and rotary pulse generators 30. Any error signals at the summing units 21, 21<SP>1</SP> is amplified and passed to respective actuators 28, 28<SP>1</SP> controlling pumps 24, 24<SP>1</SP> connected to motors 25, 25<SP>1</SP> driving the grinding  wheels. Each mechanism 32, 32<SP>1</SP> for detecting the size of its grinding wheel, and hence the wear thereof, uses filtered coolant and consists of a housing 40 Fig. 6, which is supplied with the coolant through a pipe 41 and has a pair of orifices 42, 43, orifice 42 leading to a chamber 44 and tube 45, and orifice 43 communicating with a chamber 46 of the same volume as chamber 44 and tube 45. Tube 47 has a sensing orifice 47 adjacent its grinding wheel 10, and chamber 46 has a sensing orifice 49 adjacent an adjustable restrictor 50 having a contour corresponding to the grinding wheel. The chambers 44, 46 are connected by respective pipes 57, 58 to opposite sides of a diaphragm 56 connected to a switch 60 which is thereby operated when a pressure differential exists in the chambers 44, 46. Each grinding station consists of a head 67 movable along ways 66 by an hydraulic cylinder 68 and having a column 69 which supports the grinding wheel 10 and its motor 25. A way 70 on the head supports a dresser structure 71 movable by a cylinder motor 71a. A sensor ram housing 75 is movable along ways 72, 73 on the structure 71 and has a ram 76 carrying the sensor orifice 47. The ram is a telescopic fit with a block 95 carrying the housing 40. The ram housing 75 is urged towards the grinding wheel by springs 80 to a position determined by a stylus 85 engaging a cam bar 83 whereby the profile of the grinding wheel is determined as the housing moves along the ways 70. The ram 76 is movable relative to the housing 75 by a wheel 101 engaging a screw 103 on the ram and rotated by a worm 100 which is axially movable for coarse adjustment by a reversible air motor 125 and is rotatable in steps by a pawl- and-ratchet mechanism operated by a fluid motor, the stroke of which is controlled by an adjustable limit switch. When the sensor detects that wear of the wheel has occurred, the switch 60 (Fig. 6) operates the fluid motor to feed the ram 76 towards the wheel. Simultaneously, this motor 68 is operated to advance the head 67 the same amount. The position of the ram 76 in the housing 75 is detected by a transducer unit 130, and the position of the ram longitudinally of the wheel is detected by a transducer 135, the outputs of the transducers being fed to a computer which determines when dressing by a diamond 150 carried by the ram is necessary. The contour of the grinding wheel is monitored by the cam bar 83 and transducer 130 and is sensed as the base 71 move axially of the wheel. The profile is compared with a set profile to determine whether dressing is required.