Patent ID: 7303719

Claim:
An injection molding process for producing a disk-shape resin molded article that includes a rim forming peripheral area, a boss forming a concentric inner area, and a web having a disk configuration for connecting the rim and the boss, the injection molding process comprising: injecting a molten resin into a cavity of a metal mold, the metal mold comprising a fixed mold member, a movable mold member disposed movably relative to the fixed mold member, a pressing core movably disposed or faced to at least one lateral side of the web, and a center pin disposed movably to insert into the bore of the boss and to contact with the lateral surface of the boss; and pressing, in the molding process, a web site and at least one site selected from the group consisting of a boss site and a rim site in a thickness direction, said metal mold members, said pressing core and said center pin form the closed cavity by forward movement in a thickness direction, and said cavity has a capacity larger than a volume of the final molded article by a contraction volume of the injected resin, wherein the pressing core is advanced to an original position separated from the fixed mold member with a distance corresponding to the volume of the injected molten resin, the molten resin is injected into said cavity in response to the completion of the advanced movement of the pressing core to the original position, and the pressing core is further advanced to a predetermined position which corresponds to the contraction volume or shrinking amount of the injected molten resin in response to the injection of the molten resin, and wherein in the molding process, the web site is pressed in a thickness direction, and at least one site selected from the group consisting of a lateral outer region or a lateral outer side edge of the boss and a lateral inner side edge of the rim is pressed partially in a thickness direction, wherein the whole lateral side of the boss and/or the whole lateral side of the rim is not essentially pressed.