| 摘要 |
A foundry mould for low pressure moulding of metal parts is constructed of a mould chamber (14) with a bottom surface (17) having an opening (31) through which molten casting metal can ascend. A peripheral pressure chamber (15) surrounds the side walls of the chamber (14) and a suction bell (18, 19) connected to a suction duct (23) covers the top of the mould chamber and pressure chamber. Communicating apertures (20, 21) provide gas flow paths from the mould chamber and pressure chamber to the suction bell. Patterns of gasifiable expanded polystyrene are located in the mould chamber and are supported therein by a masking device, such as a masking shell (28), by means of pattern appendages (26) connected to tubular supporting members (27) of the masking shell. A sleeve (34) is locked to the opening (31) and supports the masking device. Compacted, binderless, sand fills the remaining volume of the mould chamber. Moulded metal parts are produced according to the moulding process of the invention by forcing molten metal under low pressure upwardly through the sleeve, and the masking device to the pattern of gasifiable material, the heat of the molten metal gasifying the pattern material, the molten metal filling the voids left by the gasified patterns. |
