| 摘要 |
PROBLEM TO BE SOLVED: To realize the efficient liquation of a low melting point metal core in the hollow part of a plastic molding, and completely eliminate remnant of a metal, from which the low melting point metal core is made, onto the inner wall surface of the hollow part of the plastic molding. SOLUTION: A plastic molding having hollow parts, each of which has a non-releasable shape and is filled with a low melting point metal core such as an intake manifold 2, is immersed in an ethylene glycol liquid 5 so as to melt the low melting point metal core in the ethylene glycol liquid 5 through high frequency induction heating in order to flow the low melting point metal under molten state out of the opening part of the plastic molding 2. In this case, during the period ranging from the time point of the starting of the melting of the low melting point metal core to that of the completion of liquation, a mechanical vibration is given to the plastic molding 2 in order to flow the low melting point metal under molten state out of the opening part of the plastic molding 2.
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