GB579469A - Method and mould for casting thin-walled flat articles - Google Patents

Abstract

579,469. Processes for casting magnesium. FORD MOTOR CO., Ltd. April 17, 1944, No. 7083. Convention date, Feb. 12, 1943. [Class 83 (i)] Moulds.-In a method of casting from light metals such as magnesium and its alloys, an article having a substantially flat thin section, the molten metal is admitted uniformly at spaced points around the outer portion of the mould cavity defining the flat section so that it flows uniformly through the cavity and the metal initially so flowed concentrates in a reservoir or riser located centrally in the thin section, the succeeding flow of metal serving to fill the thin section and to provide a substantial mass of molten metal in a continuous annular reservoir or riser adjacent the outer portion of the mould cavity. The invention is described with reference to a mould for casting a crank-case blower housing for a radial aircraft engine and in the Figure the actual article is shown instead of the mould cavity. The housing comprises a substantially vertical circumferential wall 14 and a thin flat horizontal wall 15 joined to the wall 14 by a comparatively heavy circumferential flange 19. The wall 15 has a central boss 17, an eccentric boss 18 and vertical strengthening ribs 16. A central riser 27 made in two parts is formed in the mould above the position of the boss 17, a riser 32 over the boss 18 and an annular riser 28 made in four parts over the flange 19. In.operation, metal is poured through a multiple .gate to a settling chamber and then through secondary gates to an annular chambers 25 below the wall cavity 14 to the bottom of which the chamber 25 is connected by a number of small conduits 26. The molten metal first entering fills the cavity 14 and flows radially inwardly through the thin wall cavity 15 and collects in the riser' 27 and also in the riser 32. The succeeding flow fills the cavity 15 and then builds up a mass of molten metal in the outer annular riser 28. As cooling takes place the metal first solidifies in the wall 15 between the risers 27 and 28 from which molten metal may flow as the solidifying mass contracts. The metal in the risers is subsequently cut off along the dotted lines 29, 30 and 33. Either green or baked sand may be used for the mould matrix.