Research On Injection Molding Process Of Automobile OBD Cover Based On CAE Technology

OBD(On-Board Diagnostic-OBD),an integral part of the on-board diagnostic systems,is mainly applied to the protection for OBD box.The assembly accuracy of OBD is strict.Excessive curly and deformation would have great effect on the combination between cover and box,resulting in increasing noise during driving and driving safety.Therefore,it is important to improve the product quality by analyzing the warping deformation of the thin-walled OBD cover and optimize the injection mold structure and molding process parameters.In this work,The effects of injection time,melt temperature,mold temperature,holding time and packing pressure on the deformation of OBD cover box is investigated by Autodesk Moldflow Insight simulation analysis software and orthogonal test optimization method.Optimal process parameters was obtained to improve the deformation of OBD box by the mean value analysis and variance analysis method.The main conclusions of this work are as following:(1)Based on the analysis by Moldflow software,theoretical basis and data support for the design offing of injection mold were obtained.Processing for OBD cover products including injection mold casting system,exhaust system,cooling system were investigated to obtain optimal processing parameters.The mold adopted a whole structure with one module and two cavities,and the pouring system adopted the complex runner system with hot and cold runner.In optimal gate position beyond the edge of the assembly,gel could be injected by a fan side gate with large size.The mold exhaust system is optimized by using the partial surface exhaust and the exhaust groove.The cooling efficiency of the mold is optimized by proper design for the cooling pipe.(2)Discussion and analysis were applied about the results of flowing,cooling,warping deformation.The influences of the velocity field,the temperature field and the pressure field on the warpage of product during the flowing process of polymer melt were investigated.The results showed that the product shrinkage unevenness was the most important factor affecting the warping deformation of the OBD product.(3)OBD cover warpage as the optimization target,orthogonal test with 5 factor 4 horizontal was used to study the effect of injection temperature,mold temperature,holding time and packing pressure on the warping deformation of the law.By the mean and variance analysis,it was found that the packing process setting(packing pressure and packing time)was the most important process parameter which affected the overall warping deformation of the product.The optimal process parameters was obtained:the injection time 3.5s,the melt temperature 230?,the mold temperature 50 ?,the packing time 9s and the packing pressure 95%.About the actual length,width and height of the injection molded products,maximum relative error between numerical simulation and experinment was around 9.7%,suggesting the validity and accuracy of CAE method in this wor.