Patent GB-696110-A (GB)
Title: Machine for finishing work pieces such as turbine blades
Inventor: MUELLER PAUL MANNING
IPC: B24B17/08
Filed: 1951-07-17
Abstract: 696,110. Grinding turbine blades. NILESBEMENT-POND CO. July 17, 1951, No. 16953/51. Class 60. A machine for finishing turbine blades and other workpieces comprises a slide 12 movable horizontally on a base 10, a swinging carriage 28 on the slide, means for rotatably mounting a model M and workpiece W on a common horizontal axis on the carriage, a model-following roller 46, an abrasive band 48 passing over a pulley 50 at its point of engagement with the workpiece, and means for oscillating the roller 46 and pulley 50 about axes normal to the axis of rotation of the model and workpiece in timed relation to each other and to the rotation of the model and workpiece. The slide 12 carries a second slide 24 normally locked to the slide 12 by a latch 96 so that both slides are then movable by a screw 14 which engages a nut 16 in the slide 24 and is driven by a reversible motor 18. The carriage 28 swings on horizontal bearings 26 on the slide 12 and carries a shaft 29 on which is centrally mounted a housing 31 for two parallel shafts 30, 32; these two shafts are driven at the same speed by worm gears 34 engaging a worm shaft rotated by a fluid motor 38. The shaft 32 drives both the model M and workpiece W which are mounted at the opposite ends of this shaft between adjustable centers 40, 44. Cams 62, 88 are similarly driven by the shaft 30. The model-following roller 46 is mounted for oscillation about the axis of a vertical shaft 52 which is connected by levers 54, 56 to a bell-crank 58 carrying a roller 60 in contact with the cam 62. The support for the pulley 50 over which the abrasive band 48 passes is similarly mounted for oscillation about the axis of a vertical shaft 68 by being connected by a link 66 with the means for oscillating the roller 46. The band 48 passes over a pulley 70, Fig. 3, at the end of an arm 72 supported by the shaft 68; the pulley 70 is driven by belt-and-pulley mechanism from a motor 82 which is mounted for oscillation with the bell-crank 58. The cam 88 engages a vertically-movable roller 90 actuating a valve 92 which controls the admission of fluid to the motor 38 and thereby the rate of rotation of the model and workpiece. In operation, the slides 12, 24 are connected by the latch 96 and traversed together by screw 14. The carriage 28 then swings under control of the roller 46 and model, and both this roller and the pulley 50 are oscillated by the cam 62; at 'the same time, the cam 88 controls the speed of drive of the motor 38 so that the surface speed of the workpiece in contact with the band is substantially uniform. The grinding path is then in the form of a uniform helix until it reaches the supporting or attaching end of the blade. To finish this portion of the blade, the latch 96 is tripped by a block 98 so as to free the slide 12 from the slide 24, and a spring 100 forces a follower 104 on the latter slide against a face cam 102 on the shaft 30; feed is then made up of a steady traverse provided by the screw 14 and reciprocation of the slide 12 by the cam 102. A limit switch 20 on the frame 10 cooperates with abutments 22 on the slide 12 to reverse the direction of feed at the end of the grinding path, and this feed comprises a first compound stage in which the slide 12 is reciprocated and a second simple feed instituted when the latch 96 again connects the slides 12, 24. Both the roller 46 and pulley 50 may be of crowned form and the surface of the pulley 50 may be resilient.