GB810294A - Improvements in or relating to upward flow casting - Google Patents

Abstract

810,294. Casting-machines; making aircraft; brazing. BRENNAN, J. B. June 2, 1955, No. 15822/55. Classes 83 (1), 83 (2) and 83 (4). A mould is moved with respect to a moltenmetal supply source and is charged at successively higher levels of the mould cavity, each charge flowing upwardly in that cavity. A permanent, two-part mould 4, Figs. 1 and 2, defining a cavity 8 for an air-foil section, has gates 12 at different levels, and risers 11. The mould is surrounded by a crucible 15 which has valve-plates 16, movable by handles 19, for opening and closing discharge-ports 17, and which plates may be pressed against the mould to form a fluid-tight seal by hydraulic cylinders 18. A heating-coil 14 surrounds the crucible, and a cooling-device 20 is secured to the bottom of the crucible. In operation, a mould on the base-plate 2 is preheated by the coil 14, the plates 16 are raised to allow molten metal to enter the mould through the lowermost gates 12, and the crucible is then progressively raised to cause the metal to flow through the other gates 12 in succession. The cooling-device 20 being raised with the crucible, the solidification of the metal in the mould progresses from the bottom upwardly. Alternatively the crucible or cooling-device may be stationary, and the mould moved. In a modification, Figs. 4, 4a, the molten metal is contained in the hollow walls of a structure having a stepped base 30a. The mould 4 has gates 12 at different levels which correspond with gates 16 in said hollow walls, so that metal flows through the gates 12 in succession as the mould is moved from one step to the next. Stepped cooling walls 31 cause a progressive cooling of the mould. Alternatively the crucible and cooling-walls may be moved past a static-mould. Making aircraft; brazing.-Two cast portions 35, 36, Fig. 5, of an airfoil section, e.g. of aluminium alloy, are joined by placing aluminium brazing compound between the abutting machined faces, and heating in a brazing furnace or by high-frequency heating. Alternatively, the portions with the brazing compound between are squeezed together in a close-fitting die heated to approximately 400-500‹ F.