| With the rapid development of electronic connector,the market has higher requirements on the surface quality,dimensional accuracy and assembly performance of the connector.The dimensional accuracy error caused by shrinkage deformation is a common and difficult engineering problems.Engineers design product based on product structure and molding process in the development and design of new product,but the result is often difficult to predict,the material shrinkage have different results due to the differences of material and forming process.In addition,the greater the shrinkage of the injection molded parts,the greater the likelihood of defects such as warping deformation,surface shrinkage marks,etc.How to use CAE to carry out quality defects prediction to improve the quality and performance of electronic connectors has become an important subject of research in this field.The paper took a connector plug produced by Kunshan Cocentra Electronics Co.,Ltd as the research object,studied the influence of process parameters on the forming quality under the determined conditions of injection molding machine,plastic material and mold structure and optimized the forming parameters to improve the size precision caused by shrinkage leads to poor assembly.Finally,the feasibility of assembly was verified by the test mode.The main results and research contents of this paper were listed as follows:Firstly,the gate position optimization,finite element model creation and simulation test analysis were studied based on Moldflow software.Importing 3D model of the connector into software for grid partition and repair.Using the "gate position" analysis sequence option in Moldflow to find the best gate position,the results showed that there were many short shots and can not be used as the best gate position.According to the structure of the connector with the gate design principle,three schemes of the gate location were designed,each indicator was simulated and compared under the same conditions,which concluded that the side gate was the best,and consistent with actual production gate.The pouring and cooling system were designed and meshed with the actual connector production,and flow and cooling function of software were analyzed,the results showed that the finite element model was reasonable.Analysis of warping deformation showed that the main factors causing deformation were the uneven shrinkage,which accounted for 98.01% of warping deformation caused by all the factors,the influence of the uneven cooling and the orientation factor were small,and the Y direction shrinkage was the biggest,which has important influence on the assembly of the connector.Secondly,the Analysis of influence of different process parameters on the molding quality,optimization of the process parameters were studied based on the orthogonal test;by using the weighted comprehensive score method,the process parameters of optimum integrated quality was obtained.Taking the mold temperature,melt temperature,packing pressure,packing time,injection time and cooling time as the main factors,the indexes were volume shrinkage at ejection time,warping deformation and indentation depth,and orthogonal experiment of six factors and five levels of 25 groups was established.Software was used to simulate the index values under different process parameters combinations and signal-to-noise ratio function was calculated for the test results.The process parameters combinations of optimal single quality and the influence of process parameters were analyzed through the mean and range analysis of signal-to-noise ratio.Through the variance analysis of signal-to-noise ratio,the influence degree and size of the process parameters on the quality indexes were analyzed,the results showed that the significant influence factors of the volume shrinkage,warpage and indentation depth were namely the packing pressure and melt temperature,the mold temperature,the packing time,the injection time and the cooling time were relatively small,but also need the appropriate technological level.Based on the weighted comprehensive score method,the comprehensive evaluation of volume shrinkage at ejection time,warpage deformation and shrinkage depth was carried out.Through the mean and range analysis,the process parameters of optimal integrated quality and the influence of process parameters on the comprehensive score was obtained.After that,the method of the coefficient of variation was combined with the method of approximating the ideal solution to optimize multi-objective quality of process parameters,the process parameters was further refined and optimized,and prediction model of BP Neural Network between process parameters and multi-objective quality was established.Based on orthogonal test data as sample,the weight of each quality indicators was determined by using variation coefficient method,approximating ideal solution is used to calculate the relative closeness of each quality index with different process parameters combinations.The influence of different process parameters on relative proximity was analyzed by mean and range analysis,and the combination of process parameters of optimal integrated quality was obtained initially.On the basis of the best quality technology,process parameter level was refined,and the combination of process parameters of optimal comprehensive quality was obtained through the optimization analysis.The experimental results showed that further optimization was achieved compared to the process was not refined.Due to the complex nonlinear relationship between the process parameters and the forming quality,it is difficult to express with the concrete mathematical function,and the BP neural network prediction model was established.Taking results of orthogonal test as the training samples,and the influence of different hidden layer nodes on the neural network was trained,and the number of hidden nodes with the least error was obtained.Through training and prediction of the test results of process refinement,the prediction values closed to the simulation,which showed that BP neural network model had better predictive function,can substitute software simulation for a long time in the range of allowable error,and provide theoretical guidance for quick and easy optimization of process parameters.Finally,the test mode of injection molding process was verified for connector.The best combination of process parameters based on the study was tested through injection molding machine,the dimensions measured by the test mode complied with design specifications of plastic parts drawings,the molded parts and terminals were assembled well,which showed that the optimized process parameters can improve the size precision caused by shrinkage.In order to meet the requirements of the plug and contact characteristics,the plug and pull force test were carried out,the plug force curve met the requirements,and the reliability of the optimized process parameters was verified indirectly.The above research results indicate that CAE analysis with research methods of optimization method and process test validation has important practical significance for improving the molding quality defects,optimizing the process parameters,reducing the number of molds and modifications after product testing. |
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