GB721478A - Improvements relating to the shaping of metal articles - Google Patents

Abstract

721,478. Making turbine blades. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. March 5, 1953,[April 1, 1952], No. 8294/62. Classes 83 (2) and 83 (4). Stamping.-A method of forging a turbine or compressor blade casting to produce accurate shaping of a face thereof to a predetermined form consists in forcing said face against a die surface by the application of pressure at the opposite face of said blade casting through the intermediary of a loose pad of material deformable under pressure and without application of heat so as to ensure uniform pressure distribution on the blade casting to transfer errors from said face in contact with the die surface to the opposite face. The press tool comprises dies 1 and 2 mounted on plates 11 and 21 respectively located by pillars 3 over which slide bushes 3<SP>1</SP> in the plate 2<SP>1</SP> when the plate 21 is depressed. Springs 4 keep the dies apart when no pressure is being exerted. The bottom die 1 has an accurate convex face 5 corresponding to the accurate shape desired for the concave face 6 of the cast turbine or compressor blade 7 which is accurately located in the die by means of pins 14 and a spring-loaded plunger 10 located in semi-cylindrical grooves on each die. In operation, a turbine or compressor blade of high tensile steel is heated to say 650‹ C. and positioned in the bottom die of the press tool. A pad of asbestos covered by graphite and white spirit as lubricant is placed over the blade and the press operated at a pressure of 50 tons per square inch, whereby the under face of the blade is caused accurately to conform to the shape of the bottom die. All errors are now contained in the upper face of the blade and these are later removed by polishing or grinding. Turbine blades of austentic steel can be pressed to accurate shape when cold, using rubber as the deformable material for the pad.