Injection Process Multi-objective Optimum And Mold Design Of The Car Skylight Guiding Rail Based On CAE

With the rapid development of the automotive industry,plastics are widely applied in automobiles under the background of vehicle lightweight.Injection molding is a commonly used molding process for plastic products,in actual production,injection products often produce defects such as shrinkage and warpage.With the rapid promotion of CAD/CAE technology in injection mold design and process parameter optimization,the quality and production efficiency of plastic parts are effectively improved.The car skylight guiding rail which produced by a company is chosen as research object in this paper,CAE simulation software and mathematical optimization methods are used to explore how to efficiently and accurately carry out reasonable mold design and forming quality optimization on the car skylight guiding rail.Firstly,the application and advantages of plastic in automobile were introduced.The CAE technology and its theoretical basis were summarized,and the main causes and solutions to the warpage and shrinkage were analyzed.With the three-dimensional design software UG,the mold design of the car skylight guiding rail was carried out,and Moldflow simulation software was used to simulate the forming process of the car skylight guiding rail.The simulation results,rheology design principles and mold design criteria were combined to provide a theoretical basis for mold design which shorten the design and manufacturing cycle of mold.Then,according to the situation that it was easy to produce shrinkage and warpage during the injection molding process,the mold temperature,melt temperature,holding pressure and holding time were selected as the design variables,with ejection volume shrinkage and the minimum warpage as the optimization objective.To optimize the target,the central composite design of four factors and five levels was conducted.Based on the simulation results of Moldflow software,a response surface model between the optimized variables and targets was established,and the effects of the single factor and multi-factor interaction on the volumeshrinkage and warpage were analyzed.Finally,in order to achieve the multi-objective optimization of the process parameters of the car skylight guiding rail,the response surface model of the two optimization objectives were solved by the multi-objective optimization algorithm based on NSGA-II.The combination of process parameters which effectively control the shrinkage and warpage was found.The mold temperature is 64?,melt temperature is 265?,holding pressure is 99.53% of the injection pressure and the holding time is 13 s.At the same time,combined with the Moldflow software,the best combination of process parameters was simulated and verified.The error between the simulation result and the prediction value of the optimization algorithm is small which proves the reliability of the multi-objective genetic algorithm.Meanwhile,through applying the optimal combination of process parameters into actual production,the products produced can meet the quality requirements.The results show that it is extremely important to improve the molding quality of plastic parts and shorten the period of product development by using the numerical simulation technology,the response surface model and the multi-objective optimization algorithm based on genetic algorithm.