Influence Of Insert Thermoforming-film To Molding Film On Performance Of Injection Molded Parts

Insert Thermoforming-film to Molding(INS)is a new surface decoration process for automotive interior parts.Because it can complete the injection molding and decoration simultaneously,It has the advantages of environmental protection and high efficiency in the production process,so INS is widely used in automotive interior parts.However,at present,INS technology faces the problems of shallow depth of sheet forming,the film easy to breakage and peeling off from injection molded part and the injection molding product is easy to warp,whice makes the performance control of the INS product difficult.In view of the thermoforming process and in-mold injection process of the sheet materials in INS technology are the most important factors affecting the quality of interior parts,therefore this thesis mainly does the following work:(1)Test analysis of basic mechanics of INS film.The INS film were subjected to uniaxial tension and biaxial tensile tests at different temperatures,tensile rates and loading displacements.The stress-strain behavior of the film was studied.The two stretching methods were compared and analyzed.The change of mechanical properties of the diaphragm under temperature and loading ratio.(2)Analysis of thermoformability properties of INS film.The constitutive model conforming to the deformation behavior of the film was constructed by using the experimental data.Then the user subroutine was written in Fortran language and embedded in ABAQUS software.The accuracy of the model was verified by simulation results and experimental comparison methods.Finally,the influence of process parameters on the thermoforming properties of the film was simulated.(3)Study on the influence of film deformation behavior on the in-mold film injection molding process.Since the formed film is fixed in the mold cavity,the film will inevitably affect the melt flow and heat transfer process during the injection molding process,thereby affecting the performance of the INS injection molded part.In this thesis,the film with variable thickness after forming is used as the boundary condition of the mold flow analysis,and the thermal conductivity coefficient of the composite film is tested with the temperature curve,so as to establish the in-mold film injection molding model,and then use the moldflow software to simulate the injection molding.The influence of the film on the melt temperature field and the mold temperature field after forming.(4)Analysis of the influence of the film on the performance of the injection molded parts.Firstly,the influence of the deformation behavior of the film on the warpage and shrinkage of the INS injection molded parts was studied by using the variable thickness diaphragm after forming.Secondly,the orthogonal test and the control experiment were used to study the injection molding process and the film to the INS injection molding mechanics.The influence of performance and optimization of the in-mold film injection molding process were carried out.Finally,the cross-sections of the two injection molded parts were observed by scanning electron microscope,and the influence mechanism of the injection molding process on the bonding performance of the film and the substrate was analyzed.The research in this thesis can not only technical reference for INS sheet forming,but also has important reference value for INS injection molding process and improvement of INS product qualification rate.