The Research On Optimization Of Process Parameters And Enhancement Of Regeneration Rate For Injection Molded Car’s Rear Bumper

Sink mark is the common defect in the injection molding of the car’s rear bumper, which would seriously affect the appearance quality of the products. Sink mark would become more obvious especially after the surface of rear bum-per is painted, which is one of the main reasons scraping the bumper. In addition, the bumper cost could not be reduced all along, because the PP material recycling utilization rate of many bumper manufacturers is generally low. There-fore, it has important realistic and economic significance to reduce the surface sink mark by optimizing process parameters and raising the regeneration rate of the PP material by taking effective measures for the car bumper.In this paper, the car’s rear bumper produced by one carmaker was studied. First, mesh division and repair of this bumper were completed in the injection molding analysis tool Moldflow software, then its runner and cooling systems were created combined with the actual situation of manufacturer. The model was numerically simulated by Moldflow software, which verified the rationality of this built analytic model.Secondly, aimed at minimizing the common surface sink mark on the car’s rear bumper in the actual production, Taguchi was used to arrange the simulation test, then the largest sink mark index of the products was simulated using the created model in the Moldflow. By analyzing the test result, the size order and the significant level that each experimental factor influenced the sink mark index of the rear bumper and the optimal combination of process parameters which made the sink mark smallest were obtained. Based on the obtained optimal combination, the injection molding test was conducted. The results showed that the products had no obvious sink marks and met the quality requirement, which proved the reliability of the simulation results.Finally, the research was conducted to raise the regeneration rate of the car’s rear bumper. The necessity of raising the regeneration rate of the car’s rear bumper was fully proved by analyzing the experimental data. The fish-bone diagram was used to analysis the current situation why PP material regenera- tion of the car’s bumper was low. Then, some specific measures to raise the regeneration rate of the car’s rear bumper were put forward, such as raising the efficiency of the grinder, improving the structure of the mold and eliminating abnormality of metal powder, etc. After these concrete measures and the optim-al combination of process parameters from Taguchi were applied in the prac-tical production, the actual injection molding test was conducted. Compared with before, the products accorded with the quality requirement. At the same time, the regeneration rate was raised and the molding cost was reduced.The research proved that the quality of products would be improved, the production cycle would be shortened, and the cost of products would be reduced when the CAE technology was applied in the practical production. The concrete measures of raising the regeneration rate of bumpers which this research put forward could reduce the molding cost effectively, and had great guiding signify-cance to the product manufacturers.