Injection Process Optimum And Mold Design Of The Car Door Inner Panel

With the increasing auto production and sales in China, plasticization of automobile has become an important evaluation of the development level in automobile industry which boosting the application of plastic parts in automotive. The thin shell is the most common type of plastic injection parts. Warpage is the main quality defect which causes the dimensional deviation of product assembly. CAD/CAE technology is rapidly developing and applied to the injection molding industry, which efficiently improve the quality of products as well as cut the cost of product development cycle.The car door inner panel is chosen as research object in this paper, applying the CAD/CAE technology during the design phase to guiding tooling design. Taking the orthogonal design, grey relation theory and response surface method into comprehensive consideration is for the process parameter optimization of car door inner panel.Firstly, the paper introduces the category of automotive plastic parts and the common technologies of plastic processing, analyzing the common quality defects of injection plastic parts and solutions. Then, three-dimensional model of the car door inner panel was designed in CATIA. At the same time, the numerical simulation modal of injection molding process was established in software Moldflow. The appropriate mold structure had been designed by combining the simulation result and tooling design principles which shorten the manufacturing cycle of moldThen, five factors are taken into account which based on simulation process and orthogonal method. They are mold temperature, polymer-melt temperature, cooling time, packing time and packing pressure. Afterwards, through range analysis and variance analysis, assessing the impacts of different multi-parametric combinations on warpage and volume shrinkage.Subsequently, integrating orthogonal design with grey relational model is order to estimate the influence factors on injection process. Then, the warpage and volume shrinkage of car door inner panel were selected as the quality targets. Grey correlation is taken as evaluation factors to calculate the average gray correlation degree of different parameters under different values. The higher value of grey correlation is, the better comprehensive quality of this lever of this parameter can be obtained. Through the Moldflow simulation the value of warpage obtained increased by 0.053 mm compared to the minimum value of the orthogonal experiment, the volumetric shrinkage is only 0.02% under the optimized parameters compared to the orthogonal experiment, therefore improving the comprehensive quality of the car door inner panel.Finally, basing on the packing time and mold temperature the response surface model is set up to further optimize the injection process of car door inner panel. Meanwhile, the variance analysis and inspection of models are carried out to verify the significant of response surface models. The optimal process parameters of the car door inner panel, which can satisfy the quality of plastic parts is determined by superposing the two response surface models. The mold temperature is 50.5?,packing time is 9.1s, polymer-melt temperature is 230?, cooling time is 12 s, packing pressure is 40 MPa. Next the simulation result of the response surface models is much better than the theory grey one, which proves the reliability of the response surface model. Importantly, setting the parameters in injection machine and then get good quality of the car door inner panel, which show that the second-order response surface method has great significant guidance to optimize the injection molding process parameters and provide practical experience in production.