| 摘要 |
PURPOSE:To easily manufacture a low m.p. core having smooth surface by packing sand, using a wooden pattern covered with a film composed of heat resistant resin and removing the film after pouring molten Bi-Sn alloy and solidifying at the time of producing the low m.p. core with the Bi-Sn alloy. CONSTITUTION:At the time of manufacturing the core for casting with the low m.p. alloy of Bi-Sn alloy, on the surface of wooden pattern 2 giving shape of the core 1, the film 3 composed of the heat resistant resin of polyimide, etc., without being molten even at temp. of the molten Bi-Sn and without developing abnormality on surface condition, is closely stuck with evacuation in the wooden pattern 2. A molding flask 4 is fitted to the wooden pattern 2 and after packing the sand 5 therein and applying the film 6 as the same as the above on the surface, inner part of the molding flask 4 is evacuated and the sand 5 is solidified and the wooden pattern 2 is taken off. An upper sand mold 7 and a lower sand mold 8 formed with this method are mated and after preheating, the molten Bi-Sn alloy 10 is poured into cavity 9 and solidified. Successively, the sand molds 7, 8 are broken, and by removing the film, the low m.p. core 1 having smooth surface is manufactured. |
