| 摘要 |
Method of casting such melts of materials, the course of solidification of which comprises an expansion followed by a contraction, for example grey iron alloys, nodular iron, etc. The molten material is supplied to the mould cavity (2) in a mould (1) via one or more sprues (5) with following inlets (7) in direct communication with the mould cavity (2), after which the connection of the mould cavity (2) to the environment is blocked at a moment selected so that at least some of said expansion and following contraction takes place in the space closed by said blocking. What is characteristic of the invention is that the blocking is brought about by cooling a portion of the sprue (5) so that a solidified plug of material (10) is formed in the sprue (5) before the material present in the inlet (7) solidifies. According to a preferred form of embodiment, the cooling is brought about by inserting a plug, for example of sand, in the mouth of the sprue (5), preferably a plug with a cross-section decreasing in the direction of insertion. The invention renders it possible to utilize the expansion of the melt during the course of solification to prevent the development of cavities in the casting caused by following contraction while at the same time complete freedom is afforded with regard to the dimensioning of the casting system. |
