| With the development of the automobile industry,the headlight technology is also driven by this to show the vigorous vitality.On the basis of the pursuit of higher performance and quality,the appearance of the car headlight has produced more aesthetic pursuit to cater to the market,and the multi-color injection molding has become the first choice because of its colorful appearance.In this paper,the injection parts of two-color through lamp were taken as the research object,combined with CAE analysis technology,the product structure,mold system and molding process parameters were analyzed,in order to obtain high-quality plastic parts,the product structure,mold system and molding process parameters were analyzed,designed and optimized.(1)According to the molding structure and service conditions of the product,the injection sequence of two shots and the selection of materials were determined,and the pouring system of two shots was designed by CAE analysis technology.The cooling system of plastic parts was optimized by using experimental design and variance analysis.The optimal cooling effect was determined when the diameter of the designed waterway was9.5mm,the distance between the waterway and the plastic part was 38 mm,the distance between the waterway and the plastic part was 10 mm,the inlet temperature was 70℃ and the flow Reynolds number was 25000.Finally combined with the analysis results of plastic parts and the theory of mold design to design the mold forming mechanism.(2)With the first and second volume shrinkage and total warping deformation of plastic parts as quality objectives,mold temperature,first melt temperature and dwell pressure,second melt temperature and pressure holding,and pressure holding time were selected as process variables.Based on Opt LHD(optimal Latin Hypercube)experiment design and the corresponding mode flow analysis data obtained by Moldflow,BP neural network model was constructed by MATLAB,and the experimental data were trained and tested to ensure the high precision of the model.Finally,the influence law of each process parameter on the volume shrinkage and total warp deformation of the two shot was analyzed.(3)On the basis of the established BP neural network model,NSGA-Ⅱ(nondominated sorting genetic algorithm)optimization algorithm was written with MATLAB.Taking the first and second volume shrinkage and total warpage deformation of plastic parts as quality objectives,multi-objective process parameters were optimized in the established interval,and Pareto optimal solution set composed of domination level 1 was obtained.(4)The optimal solution is found in Pareto frontier: the volume shrinkage rate of the first shot is 3.581%,the volume shrinkage rate of the second shot is 4.574%,and the total warpage deformation value is 3.275 mm.The corresponding process parameter combination is as follows: Mold temperature 80℃,the first injection melt temperature 282℃,the first injection pressure 13 MPa,the second injection melt temperature 280℃,the second injection pressure 96 MPa,the pressure holding time 13.5s.Moldflow was used to simulate and verify the data.The errors between the simulation results and the optimal results of each index were 1.07%,1.27% and 0.95%,respectively.Compared with the optimal results before optimization,the optimized results were improved by 3.87%,13.52% and 1.62%,respectively.(5)The obtained process parameters were used for actual production verification and detection.The surface of the plastic parts obtained was smooth without weld marks,no cross-color appeared on the two-color bonding surface,and the light was uniform after the first transparent light guide was lit.The average error between the actual warpage value and the optimized warpage value was found to be 2.429%.The optimization results are close to the actual production data. |
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