| 摘要 |
PURPOSE:To improve a casting quality around the first casting through hole and also to improve the continuous productivity by setting a cooling time of the first core for the first casting through hole forming near the sand core for water jacket larger than a cooling time of the second core for the second casting through hole forming near a metallic mold, after casting. CONSTITUTION:At the time of filling up molten metal into a cavity C1, cooling water is flowed through the cooling water introducing passages 191, 192 and the cooling water exhausters 201, 202 by opening each opening valve 221, 222 through each timer, and exhausted from drainage pipe 241, 242. By these flows, the first and the second cores 171, 172 are cooled. The molten metal at the metallic mold M side is cooled by the metallic mold M to solidify rapidly, and so even if the cooling time at each the second core 172 side is short, it is no problem. In the other side, the molten metal at the sand core 16 side is slowly solidified by receiving the heat insulating effect of the sand core 16, but the water passing time of each the first core 171, that is, the cooling time is set as longer than it of the second core 172. Therefore, the heat reserve of each the first core 171 is evaded and the casting quality around each the first casting through hole becomes to good.
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