| 摘要 |
PURPOSE:To constitute the title method so that it does not happen that crush of the inside diameter and an uneven thickness are generated at the time of blow molding of a molded product having a contracted diameter part, by a method wherein the diameter of a parison is made somewhat large by adjusting it to the maximum diameter part of the molded product which is to be molded, and blow molding of an expanded diameter part is performed with air through an air feed nozzle. CONSTITUTION:A parison 27 is supplied between molds 23, 25 through an extrusion die 26. The parison which is on a position corresponding to a small diameter cavity part 22C is pressurized and molded from the inside and outside with a male screw part 32 of an insert member 30 and female screw part 22D formed on the small diameter cavity part 22C of the mold. When air is fed within the parison 27 through an air feed nozzle 28, the air is fed within the parison positioned on large diameter cavity parts 22A, 22B through a small hole 34 of the insert member 30, and molding is performed with this air pressure. With this construction, a thickness at expanded parts 10A, 10B is secured sufficiently and a molded product free of uneven thickness as a whole without having pile up inwardly in a contracted diameter bellows part 10C. |
