| 摘要 |
PURPOSE:To obtain a hollow casting product with a desired accuracy and beauti ful surface condition by forming a core body with almost the same shape as the inner surface of the product, covering a foaming synthetic resin with the equivalent thickness as the product's on the core to form a casting part and burning down said resin by poured molten metal after enclosing it in sands. CONSTITUTION:A projection part of the core 1b connected successively with the core body 1a, which is formed as almost the same shape as the inner surface of the product, is formed as projecting toward outside from the end of product's opening part. Further, this core 1 is fixed the settled position, to be the desired thickness in each part of the product in the cavity 4, which is formed as almost the same shape as the outer shape of the product, at contacting surfaces of both metal molds B, and is supported for its projection parts 1b. After filling up the foaming synthetic resin beads in the cavity 4 under contact condition of the metal molds B, it is heated and cooled, and then it is formed as the casting part 6 covered on the core body 1b. Next, after enclosing the core 1 in the sands 7, the molten metal is poured into the casting part 6 through a runner 8 formed toward the casting part, burns down the foamed synthetic resin therein and solidifies, and then the hollow casting product is obtained.
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