Patent GB-1313823-A (GB)
Title: Workpiece surface finishing apparatus
IPC: B24B49/16
Filed: 1971-10-13
Abstract: 1313823 Abrading CLAIR MFG CO Inc 13 Dct 1971 [20 Nov 1970] 47633/71 Heading B3D A method of lowering a finishing roll 35 into contact with a workpiece 45 and thereafter maintaining a substantially uniform pressure relationship between the roll and workpiece comprises coupling a cylinder-piston unit 112 to the roll such that movement of the piston in one direction raises the roll into a first position and movement in the other direction permits the weight of the roll to move the roll to a work-  piece engaging position, continuously biasing the unit to move the piston to raise the roll to the first position, momentarily introducing air at high pressure into the cylinder to substantially counterbalance the bias and permit the full weight of the roll to initiate movement towards the second position, and reducing the high pressure to a relatively low pressure during the period of movement of the roll toward and into the second position, the difference between the bias and low pressure determining the working pressure between the roll and work, piece. In apparatus for carrying the method, the workpiece, which may be flat or contoured, is mounted on a table 60 carried by supports 58 on a carriage 50 reciprocated by an hydraulic piston-and-cylinder device 55, 56 along slideways on a base-plate 21. The carriage moves between uprights 22 bridged by a non-rotatable shaft 26 carrying stirrups 27 for a rotatable shaft 28 supporting arms 30, 32, 33 rotatably carrying a shaft 34 of the grinding, brushing, polishing or buffing roll 35. Shaft 34 is connected by belt drives 39, 36 to an electric motor, an ammeter being provided to indicate the load on the motor. A crank arm 106 is keyed to shaft 28 and at its outer end has a nut 104 engaged by a screw 102 rotatable by a hand wheel 108 and connected to the piston 110 in the cylinder 112 secured to the base of the machine. Rails 122 are secured to the carriage 50 and adjustably carry blocks 124 having fingers 126 for actuating sensors LS4, LS5, the blocks being adjustable to positions coincident with changes in the contour of the workpiece. The machine is controlled by a system having a counterbalance circuit 130, work pressure circuit 140, reduce force circuit 150 and roll lowering circuit 160. Counterbalance circuit 130 has a source connected by a regulator 162, surge tank and conduit 168 to the upper end of cylinder 112 to raise roll 35 to first (dotted) position. Pressure circuit 140 has a regulator 172, surge tank 174, conduit 176, shuttle valve 178, conduit 180, valve 182 and conduit 184 leading to the lower end of the cylinder. The reduce force circuit 150 has a conduit 192 connecting the lower end of the cylinder to a valve 194 and adjustable throttle valve 198 leading to exhaust. Roll lowering circuit 160 has a conduit 202 from conduit 166 to a valve 204 actuated by a time controlled relay 208, the valve being connected by a conduit 206 to the shuttle valve 178. In operation, regulator 162 is adjusted so that the pressure in the upper end of cylinder 112 raises the roll, valves 182, 194 and 204 being closed, and regulator 172 adjusted to the desired work pressure. When the machine is started and valves 182 and 204 open so that high pressure is also passed through the shuttle valve to the lower end of the cylinder so that the full weight of the roll initiates downward movement of the roll into engagement with the workpiece, line 172 being closed by the pressure in line 206 acting on the diaphragm 212 of the shuttle valve. Immediately, after about a second, relay 208 closes valve 204 and only low pressure is supplied through shuttle valve 178 from line 176 to line 180. The activation of shuttle valve 178 is such that the high pressure is only supplied momentarily to the lower end of the cylinder during initial movement of the roll. During movement of the carriage, the fingers 126 actuate the sensors LS4, LS5 to actuate valve 194 between closed and open positions whereby the pressure at the lower end of cylinder is altered when the roll is working on an upwardly inclined surface to a downwardly inclined surface so that the roll has the same abrading effect.