GB683127A - Improved method and means for machining parts mounted in circumferential assembly for use - Google Patents

Abstract

683,127. Making turbines; casting composite articles; moulds. ROLLS-ROYCE, Ltd. Sept. 18, 1950 [June 30, 1949], No. 17384/49. Classes 83 (i) and 83 (ii). To facilitate the machining of turbine, compressor or other parts which, when assembled for use, have circumferentially extending abutting portions, the parts are provided with surfaces or points or both by which they are located in a jig in the same relative positions as when in use, said jig having surfaces which define a wall or walls of a mould in which the located parts are partly contained, the other wall or walls being formed by said abutting portions. Low melting point material is then poured into said mould, the composite casting is removed and machined, and finally the cast material is melted away. This material should melt at a temperature which is not damaging to the parts in question, e.g. aluminium alloy for nickel-chromium turbine blades. Wood's metal, lead and soft solder may also be used. Blanks may be cast or machined to have a finished blade profile 30 and end parts 31, 32 of which the front and back faces are machined at the required inclination to abut circumferentially. For nozzle guide-vane parts 30 of turbines with inner and outer platforms 31, 32 which abut circumferentially, these platforms define inner and outer vertical mould walls. The blanks are formed with perforated lugs 37 to engage pins 36 of the jig 35 which forms the bottom mould wall and has clamping rings 38 and screws 43 to engage a supporting ring 40. An upper supporting ring 41 with pouring holes 42 is also cast in. The composite casting is removed from the jig, using the screw 43 as an ejector if required, and the projecting parts p are then turned &c., e.g. as shown in the chain lines 33, 34.