Patent GB-813820-A (GB)
Abstract: 813,820. Copy-grinding. LANDIS TOOL CO. Feb. 8, 1957, No. 4340/57. Class 60. [Also in Group XXIX] A machine tool for cutting a non-cylindrical workpiece, such as a turbine blade 80, Figs. 1 and 2, to conform with a pattern 62, has the workpiece and pattern rotatably mounted in axial alignment on supporting means slidably mounted relative to a cutting- tool 13, and a resiliently-mounted follower, which has a follower shoe 60 with a profile 61, Fig. 2, approximating to the profile of the grinding wheel, adapted such that in following the pattern contours its displacement is transmitted by way of a hydraulic system including a cylinder-and-piston arrangement 20, 21 to produce a relative corresponding displacement of the grinding wheel. The workpiece 80 and pattern 62 are co-axially mounted between a headstock 82, Fig. 1, and a tailstock 81 on a table 11 which is longitudinally movable on a machine bed 10. A wheelhead 12, which carries a grinding wheel 13, is slidable to-and-from the workpiece by means of an arm 23, Fig. 2, secured to the wheel head and connected to the piston 21 by a rod 22. The piston is reciprocated in the cylinder 20, which is secured to the machine bed, by fluid pressure supplied through conduits 34, 43, 45 and valves 33, 42 from pumps 30, 40. Fluid from the valves is also supplied through conduits 35, 46 to oppositely-disposed nozzles 36, 47 disposed on a member 50 which is slidably mounted on a bracket 51 secured to the wheel-head. Attached to a portion 58 of the member 50 is a pair of leaf springs 73 arranged to carry a block 56 to which is secured a verticallyadjustable follower shoe 60 and a valve member is disposed between the two nozzles. The member 50 is adjustable relative to the wheelhead means of a screw 70, a spring 74 being provided to eliminate backlash. Movement between the wheel-head 12 and member 50 isshown on an indicator 75 and between the follower 60 and wheel-head 12 on an indicator 65. Upon operation of the pump 30, fluid is supplied to the valve 33 which automatically divides the flow into predetermined proportions and equal pressures into the conduits 34, 35. The pump 40 is also energised when the fluid reaches a predetermined pressure in the conduit 34 by the operation of a plunger 150 and fluid is then supplied through conduit 41 to the valve 42 and through conduit 45 to the cylinder 20 ; valve 42 operates in a similar manner to valve 33 to supply conduits 43, 46. The pressure in conduit 35, and hence conduit 34, is adjusted to be above and below the pressure in conduit 45 when the valve member 55 is moved to and from respectively, the nozzle 36. Rotation of the pattern 62 displaces the follower shoe 60 and moves the valve member 55, say, to the right towards the nozzle 36, increasing the pressure in the conduits 35, 34 and thus moving the piston and wheel-head to the right until the nozzle 36 has moved sufficiently far from the valve member 55 to bring the pressure in conduits 34, 35 again equal to the pressure in conduit 45 ; movement of the valve member to the left results in a decrease in the pressure in conduits 34, 35 and movement of the wheelhead to the left. When the piston is not moving the flow of fluid from valve 33 is diverted from conduit 34 to discharge through conduit 32. Movement of the valve member 55 to and from nozzle 47 varies the pressure supplied from valve 42 through conduit 43 to the right hand end of cylinder 20. At each rotation of the workpiece and pattern, a dog 120, Fig. 1, operates a micro-switch 122 to momentarily actuate a solenoid-operated valve to supply fluid pressure through a reversing valve to one end of a piston-and-cylinder device to move the table 11 in steps to present successive increments of the work-piece to the grinding wheel 13. A lever operates the reversing valve to supply fluid to the opposite end of the piston- and-cylinder device and reverse the direction of the table movement.