| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a thin and high strength inner duct the cross sectional area of which are of approximately the same at the body and the end or greater with the body. SOLUTION: The inner duct is produced from a thermoplastic resin such as PET or PEN by stretch blow molding. More specifically, the manufacturing method comprises molding the resin into a cylindrical preform 20 in which the larger diameter parts 20a at the ends are narrowed down to the middle part 20b in the cross sectional area, heating the preform 20 and blowing high pressure gas into the inside of the preform 20. In the stretch blow process, the cross sectional area of the middle part 20b narrowed in the molded preform 20 is stretch blow-molded in the radial direction until it becomes approximately the same as that of the larger diameter parts 20a. The manufacturing method can be suitably used for producing an inner duct with a thin wall and yet a high strength. Since the resultant molding does not have a bottom, no additional step to cut off the bottom is required and no waste is produced. COPYRIGHT: (C)2009,JPO&INPIT |
