Optimization Of Injection Molding Process For Dashboard Structure Reaction

With the continuous improvement of living conditions, people have ever greater demands for the safety and comfort in their vehicles, so that the qualities of interior parts which are direct contact with human body have been increasingly concerned. In this thesis, the structural reaction injection molding (SRIM) process of instrument panel is optimized by theoretical analysis, numerical simulation and production test, in order to solve the drawbacks that exist in the actual products.The possible causes of the short shot, blister and warpage deformation in instrument panels were systematically analyzed, then the impacts of the process flow and parameters of SRIM on product qualities were discussed to identify the six key process parameters. Further, the polymerization reaction kinetics of polyurethane were investigated to determine the scopes of material temperature, mold temperature and hold time.In order to conduct the filling process analysis of instrument panel, the Moldflow microcellular foaming module was selected according to the characteristics of SRIM, then the cavitation formation processes and distributions under different pouring trajectories were calculated to get the best pouring trajectory. Later, by comparing the distributions of cell radiuses using optimum pouring trajectory, it was found that 50℃ was the best mold temperature.The effects of process parameters on warpage of instrument panel cooling in mould were analyzed using Moldflow cooling module, the results showed that the water temperature had little influence on the deformation, and the hold time in mould could be set as 652s. The deformation of instrument panel cooling in air was simulated by the thermal-structure coupling module of ANSYS Workbench, it was found that the deformation was smaller when the instrument panel was bottom-supported or internal surface-supported.Finally, a production test was carried out based on the optimal process parameters of SRIM, the temperature distributions of materials, mold and product were monitored during the production process. By comparing the manufactured instrument panel and existing products, it was suggested that the optimization for the process parameters of SRIM could significantly improve the qualities of instrument panels.