GB719124A - A new or improved apparatus for finishing surfaces of turbine type blades - Google Patents

Abstract

719,124. Grinding turbine blades. JAMESON, J. L. Dec. 10, 1952, [Dec. 12, 1951.] No. 31303/52. Class 60. A machine for finishing the surface of a turbine blade 3 comprises a blade holder 90, Fig. 2, a die 2, means to move an abrasive band 4 between the blade and the die and fluid-pressure operated mechanism to effect relative member between the latter two members firstly at one rate until they reach a position with their surfaces close to one another and then at a reduced rate which is maintained throughout the finishing operation. In the preferred embodiment, the holder 90 is secured to a movable hydraulic cylinder 91 sliding on a stationary piston 92, Fig. 5. The cycle of operations is initiated by closing a switch 96 to displace a solenoid operated valve 122 which connects a line 95 to a pump 99 through a line 98<SP>1</SP> so that the cylinder 91 moves down quickly. Exhaust from the upper side of the cylinder takes place through a line 94, a valve 109 in a regulating unit 119 and a line 112 which is connected with a discharge line 113 through the valve 122. This action continues until a cam block 107 adjustably mounted on the cylinder 91 closes a micro-switch 108 to displace a solenoid operated valve 104 which permits fluid from the pump 99 to close the valve 109. The cylinder 91 now exhausts through an adjustable needle valve 110 so that its rate of movement is reduced during the abrading operation. The movement of the cylinder 91 is reversed when a second adjustably mounted cam block 114 opens a second micro-switch 115 to operate the valve 122 which connects the line 95 to the discharge line 113 and the line 112 to the pump 99. Fluid from the pump passing through the line 112 opens a valve 117 and hence bypasses the valve 110. A self-recuperating dashpot 126 having a plunger 123 for engagement by a lug 133 on the cylinder 91 cushions the final part of the rapid downward movement of the latter. The abrasive band 4, Fig. 2, passes over guide rollers 4<SP>1</SP> and is trapped between a roller 4<SP>2</SP> and a driven band 4<SP>4</SP> by which it is driven. Convex and concave blade surfaces can be finished and a guide 4<SP>3</SP> is arranged to exert sufficient drag on the abrasive band to provide a slack portion which can be pressed into the concavity of the die block when convex surfaces are being treated. The blade 3, Fig. 7, has one end located in a socket 136 and its other end held by a screw operated releasable swinging clamp 137. A jet 130 delivers oil to the band. Specification 591,890 is referred to.