| 摘要 |
PROBLEM TO BE SOLVED: To provide a molding method of a throttle body enhanced in roundness and excellent in mechanical strength by the injection molding of a thermoplastic resin, a mold for the throttle body and the throttle body. SOLUTION: In a mold cavity 10 for molding the throttle body 1 having an attaching flange 5 formed to one end of its cylindrical bore part 2, a pressure fluid injection port 6 is provided to the outside of the bore part 2 in which a throttle valve is incorporated and, after the cavity 10 is filled with a resin, a pressure fluid such as an inert gas or the like is injected from the pressure fluid injection port 6 at pressure drop timing in the cavity to apply pressure to the outside region of the bore part 2 in which the throttle valve is positioned. Next, dwelling pressure is applied to a resin, the resin is cooled while applying the pressurizing hydraulic pressure even after the stop of dwelling pressure and a mold is opened after the resin is solidified to eject a molded product. As a result, the roundness of the throttle body can be enhanced to the utmost in the inner diameter part 3 of the bore part 2. COPYRIGHT: (C)2009,JPO&INPIT |
