Molded resin body and method for producing the same

摘要

A method of molding a hollow body to make the body nearly uniform in thickness around an internal opening thereof. A weir is provided in a central part of an opening portion of the mold cavity near an upstream side of the opening portion with respect to the direction of flow of a resin. Molten resin is injected into the cavity, and pressurized gas is thereafter injected into the molten resin in the cavity to make the internal opening in the resin. Since the weir is provided, the resin comes into uniform contact with the inner mold surface of the die at the opening portion as the resin flows into opening portion. The resin is uniformly cooled and solidified, starting with the inner surface and working inwardly, so that the hollow body is made nearly uniform in thickness around the internal opening.