| 摘要 |
PROBLEM TO BE SOLVED: To provide a mold for a cylindrical lost foam pattern in order to cast a cylindrical component having many holes on a peripheral wall of an oilless bushing or the like by a lost foam pattern casing method. SOLUTION: For a mold 1 for injection molding a foamed resin-made cylindrical lost foam pattern 20, the mold has a cylindrical recessed mold 3 for molding an outer peripheral surface of the pattern, the recessed mold has many opening parts piercing radially the peripheral wall, and a hole opening means capable of going in or coming out is arranged in a cavity. For example, the opening means comprises a cylindrer actuator, a rode of the cylinder actuator is advanced into the cavity before a resin is injected into the cavity, or while the resin injected into the cavity has fluidity, and a hole is formed on the pattern in the cavity by retreating the rod after curing the resin. Or, the hole opening means is a drill or a reamer, and the hole is formed by machining the pattern in the cavity after curing the resin injected in the cavity. Or, the hole opening means is a rodlike heater, and the hole is formed by heating the pattern in the cavity after curing the resin injected into the cavity.
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