Image Number 102 for United States Patent #5942169.
A method of over-molding used to produce a three-dimensional hollow molded article employs a core made of resin having a hollow portion. The core is placed in a cavity of a mold. Molten resin is injected into a space formed by the core and a cavity wall of the mold through a resin injection portion. In this way at least part of the outer surface of the core is covered with resin. Deformation of the core due to the pressure of the resin during injection is prevented in one of a number of different ways. The over-molding method is optimized by calculating a temperature distribution and a pressure distribution of the molten resin in the step of injecting the molten resin into the space by numerical analysis. The displacement distribution and for the stress distribution of the core caused by pressure applied to the core by flow of the molten resin is calculated by a numerical analysis on the basis of the calculated temperature distribution and pressure distribution. The form of the hollow molded article, the form of the core, the form of the mold, and the molding conditions can thereby be optimized on the basis of at least one of the calculated displacement distribution and the stress distribution so as to minimize deformation of the core.