| 摘要 |
PROBLEM TO BE SOLVED: To prevent the development of breakage, such as crack, in a mold by plugging holes in a cubic model composed of a resin having an outer shell part provided with plural holes with a material having the metting point (m.p.) lower than that of the cubic model. SOLUTION: The cubic model 31 has the outer shell part 32 almost matched to the outer surface part of a cast product and the inner part thereof is formed as a hollow-state. Support parts 34 are integrally arranged with the outer shell part 32 into the hollow part formed in the inside of the outer shell part 32 to hold the shape of the outer shell part 33. On the outer shell part 32 of this cubic model 31, plural holes 33 are formed. In plural holes 32 in this cubic model 31, plugging materials of thermoplastic resin, such as wax, polyethylene, are filled. A lost foam pattern having the outer surface matched to the outer surface of the cast product as the target is constituted with this cubic model 31 and the plugging materials. As the plugging material, a low m.p. material having the lower m.p. than that of the cubic model 31, is used. This lost foam pattern is set to a prescribed position in a molding flask.
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