Research On Warpage Optimization Of The Large-Scale Plate Part Based On Local Temperature Compensation

The application of large-scale plate plastic parts in automobiles,household appliances,medical equipment and other fields is becoming more and more popular.Due to the flow length ration of large-scale plastic parts,it is difficult to meet the molding requirements in traditional injection molding.Rapid Heat Cycle Molding(RHCM)is widely used in the production of large-scale plastic parts with appearance requirements.Due to the simple structure and low rigidity,warpage is the main defect of the parts in molding process.The warpage has an important impact on the assembly process,which seriously restricts the performance of the product.Therefore,the warpage control strategy have practical significance for the production and application of the large-scale plate plastic part.In order to reduce the warpage of large-scale plastic parts,this paper proposed a warpage optimization strategy based on local temperature compensation.The warpage optimization of large-scale plate part was studied from the aspects of mold temperature response,molding process parameters optimization,and mold heating channels layout optimization basing on temperature compensation.Firstly,the process parameters for warpage of large-scale plastic parts was optimized.The mold temperature,melt temperature,packing pressure,packing time and cooling time have an effect on the warpage of the plastic part.The orthogonal experiment was exploited to design experiments.Moldflow was utilized to simulate the injection molding process of the plastic part.The influences of various process parameters on warpage were analyzed by range analysis and variance analysis.It turned out that the mold temperature is the most significant factor.Then,the optimization combination were verified by simulation.The simulation results of optimization combination was found that the uneven temperature distribution of the part after the injection molding is a main factor causing the warpage deformation.Therefore,locally temperature compensate of the mold during the heating process was proposed.Secondly,the mold temperature response model of the large-scale plastic part and influence law were explored.The heat transfer mechanism during the heating process of the mold was analyzed,and the heat exchange coefficients of the heat transfer boundary were calculated.ABAQUS was employed to construct the FEM model of the heating process of large-scale plastic parts molds.The influence of mold factors and medium factors on the mold temperature response were analyzes.Those provided a theoretical basis for preliminary mold channel layout.Finally,the channel layout was optimized based on the local mold temperature compensation.Optimizing the mold temperature distribution and improving the heating efficiency were considered as the optimization objective.The distances between the channel and the cavity were taken as the optimization parameter.Different channel layout were obtained by Latin Hypercube Sampling(LHS).The simulation of the mold heating process was completed by ABAQUS.The mathematical models between optimization parameters and multi-objectives were established based on the Response Surface Model(RSM).Multi-objective genetic algorithm and multi-attribute decision making were utilized to get the optimal solution set for the RSM.The optimized channel layout was finally determined,and the effectiveness of the optimization was verified by simulation experiment.