| 摘要 |
<p>1281798 Casting apparatus UNITED AIRCRAFT CORP 19 April 1971 [28 April 1970] 26002/71 Heading B3F A casting mould assembly comprises a shell mould 2 a susceptor 16, a chill plate 26 and a sleeve 22 around the susceptor 16, the sleeve 22 being provided with induction coils 24. The susceptor 16 has a cavity (18) shaped to conform with the outer surface of the shell mould and is split vertically to allow insertion of the shell mould 2. A ledge in the susceptor supports the shell mould 2 so that its lower portion 8 does not touch the chill plate 26. As shown in Fig. 1, the shell mould is for casting single crystal turbine blades and comprises a sprue 4, a turbine-blade forming cavity 10, 12, 14 and a single-crystalselecting helical bottom part 8. The mould is preheated, alloy poured and upward solidification from the chill plate effected. In a modification, a columnar crystalline turbine-blade can be formed by omitting the single crystal selecting helix 8 and replacing it with a solidification starting cavity opening on to the chill plate. In order to provide a thermal gradient in the mould the wall thickness of the susceptor may be varied e.g. to induce upward solidification the susceptor is tapered downwardly.</p> |
