Research On Experimental And Numerical Simulation Of Warpage For Precision Injection Molded Parts

This paper studied the precision injection-molded parts with different materials such asamorphous polymers, crystalline polymers and carbon fiber-filled polymers. Calculation andsimulation analysis layers residual stress of injection-molded parts on different processparameters. Calculation method on the residual stress had been discussed by viscous fluidequations combined with shell theory, and writed the computer calculation programm, andthen calculated the layers residual stress according to the experimental data. Moldflowanalysis software had been used to simulate the residual stress distribution in the thicknessdirection of the injection-molded parts under different process conditions. The residual stressof thickness direction had been transformed into layered residual stress, and then two resultshad been compared. For the crystalline polymers, the impact factors of the crystallinity degreeon residual stress had been introduced, the calculated results had been compared to thesimulation results. The ovality of carbon fiber cross section was observed through amicroscope,and then calculated the orientation degree of the carbon fibers in the matrix,andprovided the basis for the calculation of residual stress to determine its impact on themechanical behavior of materials.The main works are as follows:1. Injection molding experiment had been accomplished with PC and PP, the former wasselected as amorphous polymer and the latter was selected as crystalline polymer. First of all,the sapmle had been prepared by injection molding parts, and then the sapmle had beenfabricated by using delamination method. The warpage deformation data had been measuredby quadratic elements measuring instrument. The warpage deformation value was convertedinto a curvature radius. The curvature radius had been substituted into the residual stresscalculation formula. The layer residual stress had been calculated. Analysis had been workingby using Moldflow under different process conditions, and the layers residual stress in thethickness direction obtained from the simulation results.Finally, the simulation results hadbeen compared with the calculated results.2. The crystallization behavior of crystalline polymers has great complexity. Thedelamination and degree of crystallinity experiments had been carried out with polypropyleneparticles respectively. The degree of crystallization experiments had been worked usingDSC.The temperature field was modified by introducing the crystallizing latent heat into theenergy equation at first.Then layers residual stress had been calculated by the corrected formula and then compared with the simulation results.3. The carbon fibers had greater effective on mechanical properties of the carbon fiberfilled polypropylene parts. The injection-molded parts manufactured by experiment,and themicroscopic observation sample had been prepared.The Sample cross-section observed usingan optical microscope, and the carbon fiber-sectional dimension had been obtained,then theorientation degree of the carbon fibers had been calculated in the matrix. The residual stresscalculation formula was amended by the results.4. Abaqus, non-linear finite element software, had been used to anlyze the warpage ofparts. Moldflow analysis result was imported to the software.The effective of ejection force ofmold thimble to parts warpage had been considered. The anlysis results had been comparedwith the warpage results，the variation followed injection conditions were consistent.5.The influences of injection pressure,packing pressure and mold temperature on theresidual stressed and the warpage in injection molded parts had been explored. Theoptimization process conditions of injection molding had been obtained, and the resultsprovided the basis for theoretical research.