| With the wide application of plastic products in various fields,the quality requirements on products have been increasing continuously.The traditional methods on experience in injection mold design and process debugging can no longer meet the complex structure and high quality requirements,Therefore,the application of CAE technology has brought new ideas in injection mold and process development,which can save cost,reduce product development cycle and improve production efficiency.In this paper,automobile latch(POM)is taken as the research object.The CAD software and finite element simulation are applied to guide the reasonable design of injection molds,and then the mathematical optimization method is used to optimize the parameters of automobile latch injection molding process.The main contents of this paper are as follows:Firstly,the classification and performance of automotive plastics as well as the injection molding technology were introduced,Besides,the common defects of plastic parts during injection molding and improvement measures were analyzed.The automobile latch model was designed by UG software,the pre-injection analysis of product was performed by the Moldflow software to predict the potential problems during the mold design,and then the reasonable injection mold structure was designed.Five process parameters of mold temperature,melt temperature,cooling time,packing pressure and packing time were selected as design variables to design the orthogonal test by using Moldflow numerical simulation with the minimum warpage and volume shrinkage as optimization targets.The influence of the variables on the target and the significant order were predicted by using range and variance analysis,and the mininal process parameter combination of the warpage and the shrinkage volume was obtained respectively.Secondly,based on the results of orthogonal test,the gray relational model was established to obtain the optimal combination of process parameters through combining warpage and volume shrinkage into single target as the comprehensive quality index.The optimal combination of process parameters was obtained by simulation verification and the result of simulation on this parameter combination indicates that the comprehensive molding quality is improved simultaneously to achieve a balanced optimal effect under the premise of effective control of warpage and shrinkage of this plastic part which is better than analysis of variance.Finally,the pressure and melt temperature were selected as the optimization variables for their great impact on the warpage and volume shrinkage,and warpage and ejection volume shrinkage were still selected as optimization targets,the second-order response surface was used to establish the nonlinear mapping relation between the variable and the target,and the response surfaces of the two targets were superimposed to find the optimal region,Subsequently,the precise combination of the optimum process parameters was obtained(mold temperature is 60℃,melt temperature is 180.5℃,cooling time is 16 s,packing pressure is 98.75% of injection pressure,packing time is 20s).The molding results of the process parameters are better than those obtained by gray correlation.According to the combination of this process parameters for mold debugging,automobile latch plastic part with better comprehensive quality can be obtained,which validates the accuracy and efficiency of response surface optimization method and provides the innovate way for developing injection mold as well as improving the quality of plastic. |
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