| 摘要 |
PURPOSE:To provide both end opening sections of accurate inner diameter dimension, eliminate cutting of one side opening section of a molded product and prevent the generation of mold split line trace such as in a blow molded product by bonding a cylindrical body to a core bar, molding, and then melting the metal core bar. CONSTITUTION:A core bar 2 having an outer peripheral section of a bellows type shape corresponding with a bellows shape inner diameter section of a product by being formed with a low melting metal is installed around a core bar supporting shaft 1, and a cylindrical body 3 formed with heat-shrinkable resin is heated and bonded in a manner of coating the outer peripheral-section of the core bar 2. After that, the core bar 2 and the cylindrical body 3 are cooled simultaneously to solidify and mold the cylindrical body 3 in conformity with the outer peripheral shape of the core bar 2. Then, the core bar 2 and the cylindrical body 3 are disposed in an induction heating coil and heated, and the core bar 2 is melted at the low temperature leaving the resin cylindrical body 3 only. |
