GB769108A - A method of manufacturing articles of irregular cross-section and articles made by said method - Google Patents

Abstract

769,108. Making turbine and compressor blades and rocket fuel chambers; forging. OMNICOIL ENTERPRISES, Inc. Sept. 14, 1954 [Sept. 18, 1953], No. 26597/54. Classes 83 (2) and 83 (4). [Also in Group XXVI] A hollow metal article of irregular crosssection is formed by arranging convolutions or rings of wire side by side on a mandrel or former, securing the adjacent convolutions together by a permanent metallic bond, such as brazing or welding, and pressing the article to the required shape. The wire preferably comprises a helical winding, but may alternatively comprise a series of wire rings arranged side by side. Wire of round, square or ribbon-like cross-section wound in one or more layers on a mandrel or former may be used. The former may be solid, collapsible or destructible and formed of ceramic or low melting material. Complicated shapes are made by winding regular shapes of circular, oval or square cross-section and then expanding them to the required profile in enclosing dies under internal hydrostatic pressure or forging them to shape between dies. Internal reinforcements such as ribs may be used instead of or as part of a mandrel; in the latter case the remainder of the mandrel may be of low melting metal to facilitate its subsequent removal. The ribs may alternatively be enclosed in sheet material to produce a desired surface on which to wind the wire and the whole assembly may subsequently be brazed together to form a unitary structure. In the manufacture of a gas turbine blade, Fig. 1, wire 10 is wound on a mandrel 14 and into a groove 16 in a solid root 12 thereby securing the root to the blade portion to be formed by the wire winding. The adjacent convolutions are then brazed together and to the root; the brazing material may be applied so as to fill the valleys between convolutions, thereby providing a smooth surface 20, Fig. 6 (not shown). The winding is then forged to aerofoil shape between dies B, C, Fig. 3, and the mandrel is subsequently melted out. The open end of the winding may be closed by a plug welded or brazed therein. To facilitate winding on of the wire, the mandrel may be initially fixed to the root by soldering or brazing or it may be cast on to the end of a projection 13 of the root. The surface of the blade may be subsequently ground and/or polished. In another embodiment a compressor guide vane, Fig. 10, has its wire winding 30 enclosed in a sheath E. The wire winding is also arranged to close one end of the blade. In another embodiment, Fig. 7, a rocket chamber is formed by winding wire 25 on to a solid mandrel, the wire convolutions being brazed together and to end flanges 26, 27. The mandrel is subsequently withdrawn.