Research On Warpage Of Injection Molding Product Based On Hierarchy Structure In Rapid Heat Cycle Molding

Rapid Heat Cycle Molding(RHCM)improves the surface quality of the injection molded product by dynamically controlling the mold temperature,but the dynamic change of the mold temperature can cause the polymer temperature field to become more variable during the molding process,causing more complex warpage.The article is based on the simulation results of mold and product temperature field,the hierarchy structure distribution of the polymer temperature field during the molding process is analyzed.The morphological structure such as hierarchy structure and the crystallinity distribution of the product are analyzed.The RVE model is used to simulate the relationship between crystallization and shrinkage strain.According to the laminated plate model,the warpage simulation method of the injection molded products based on hierarchy structure is proposed,which is used to study the RHCM product warpage.The main research works are as follows:(1)The meso-mechanical model of polypropylene is established to analyze the relationship between crystallization and shrinkage strain of polymer materials.The polypropylene is regarded as a kind of compound material.It is considered that the amorphous phase is the matrix material and the crystalline phase is the inclusion material,so the meso-mechanical model of the composite material for the crystalline polymer is constructed by RVE method.According to the meso-mechanical model,the connection between crystallization and shrinkage strain of polypropylene is analyzed and the relationship between crystallization,shrinkage strain and warpage is discussed.(2)According to the simulation of mold and product temperature field,the hierarchy structure distribution law of product temperature field during the molding process is analyzed.The temperature field of mold and product during injection molding is simulated by Abaqus software.The temperature field distribution of CIM mold and unilateral heating RHCM mold is compared and analyzed.The hierarchy structure distribution of temperature field and its evolutionary law are discussed.(3)The hierarchy structure and the crystallinity of each layer are studied.The influence of crystallization on the shrinkage strain is discussed by RVE model.The morphological structure of different products is studied.The influence of temperature field on the structure and the crystallinity of each layer is analyzed.The relationship between crystallinity and elastic modulus is established by tensile test and crystallinity analysis.The effects of different layers on shrinkage strain are analyzed by RVE model(4)According to the laminated plate model,the warpage simulation method of the injection molded products based on hierarchy structure is proposed to study the warpage of the RHCM products.The warpage of the laminate model is studied by Abaqus software.The differences between RHCM and CIM products warpage are analyzed and discussed.The results are compared with the results of 3D scanning experiment and Moldflow software respectively.The feasibility of the method is analyzed.In summary,the temperature field has an important effect on the product warpage.Different temperature field of the product affects the morphology,resulting in the different strain.Through the simulation of the internal temperature field,establishing the hierarchy temperature field and analyzing the thermal history change,combining with morphology experiments,understanding the law of hierarchy morphological evolution in the molding process.According to the laminated plate model,a simulation method based on hierarchy structure of injection molded parts is proposed.The relationship between the temperature field,morphology and warpage is established.Therefore,the research work of this paper has great important theoretical significance to understand and optimize the product warpage.