GB759600A - Improvements relating to methods and apparatus for surface finishing - Google Patents

Abstract

759,600. Abrasive band machines. ROLLS-ROYCE, Ltd. May 13, 1954 [May 14, 1-953], No. 13591/53. Class 60 Apparatus for surface finishing a curved surface, such as that of a turbine or compressor blade 70, Fig. 12, comprises a work holder, a flexible abrasive carrier 41, Fig. 1, and a pressure-nuid-supply member 105, Fig. 7, disposed on the opposite side of the carrier from the work holder and having a contour 106 shaped to the form of the surface to be finished and provided with fluid delivery channels or apertures 107 to deliver pressure fluid to the back surface of the carrier 41. The carrier, which may be emery cloth, is clamped at 40 to the two ends of a chain 30 tensioned by pneumatically-loaded sprockets 36 and a jockey sprocket 34 and reciprocated by a sprocket 29 connected by a universal coupling 50, Fig. 2, and a chain drive 53 to a wheel 58 which is given an oscillating motion by a link connection and a continuously-rotating disc 56 mounted on the shaft of an electric motor 55. The operative portion of the carrier 41 is renewed for each workpiece by releasing the clamps 40 and operating supply and takeup reels 42, 43. When a concave surface is to be finished, the workpiece is mounted on a vertcally slidable holder 65 loaded by a weight 69 and the member 105 on a dovetail slide 45; for convex surfaces the arrangement is reversed. The member 105 may be made of nickel plated cast iron with a contoured rubber surface bonded thereto or entirely from a rigid material, a silicone grease being applied as lubricant between the member and the carrier 41. Pressure air or liquid is fed to separate chambers 109, 110 and 111, Fig. 8, by ducts 112, 113 and 114 supplied by a changeover valve actuated in accordance with the movement of the carrier 41 relative to the member 105 to avoid undue loss of pressure fluid. For finishing the surfaces of the blade 70 adjacent the platform 71, 72, the carrier 41 travels along lines 73 during part of the finishing operation and then the relative positions of the blade and carrier are adjusted so that the carrier travels along lines 74. To enable this adjustment to be effected, the sprockets for supporting and driving the chain 30 are mounted on a beam 28 which is periodically swung about vertical pivots 24, 25 by an adjustable crank mechanism 86. This mechanism is driven through bevel gearing and a belt 77 by an electric motor controlled by micro-switches and limit switches 98, 99. The micro-switches are actuated alternately by cams rotated by worm and belt drives from the motor 55 to start the motor for the crank mechanism while the limit switches 98, 99 are actuated alternately by the beam 28 to stop this motor when the beam has reached its new angular position. The blade and pressure-nuid-supply member may be adjusted angularly instead of the carrier 41, and an endless abrasive band may be used. Specification 759,642 is referred to.