| With the rapid development of domestic plastic industry, plastic products are more and more widely used in the fields, such as automotive, home appliances, electronic communication, aerospace and other industries, and the quality requirements of injection mould becomes increasingly higher. Thus, the traditional design methods are unable to meet the requirements of high quality, high precision, long life and high performance. Recently, the introduction of CAE technology in injection mould has broken the shackles of the traditional design methods. The potential defects of the products can be predicted through the simulation of plastic products in the molding process, then reasonable injection molding process parameters and mould structure can be determined. Whereas, the numerical simulation of injection mould is mainly concentrated on the molding process of the products, while the stress and deformation in the molding process of the mould is less considered. The transient temperature field, thermal stress field, thermal structure coupling and assembly tolerance of typical injection mould was analyzed by the finite element method in the mould design stage, and the influence of the temperature field on mould structure stress and the thermal deformation on the assembly tolerances was studied in this paper, which provided the theoretical instruction for the optimization design of injection mould.Firstly, the temperature field in the molding process of injection mould was researched theoretically based on heat transfer theory and the finite element method, and the mathematical model and numerical model of temperature field in different injection stage was established, which provided the theoretical foundation for the simulation of the transient temperature field.Secondly, the transient temperature field in the injection mould filling, packing and cooling stage was analyzed using the ANSYS to obtain the temperature field distribution of inside key parts in different injection time. The results showed that the distribution of temperature field in the packing stage was uneven and the molding parts produced large thermal stress and thermal deformation. Then, through the comparative analysis on temperature stress of the mould and the core thermal deformation in height direction in different packing time, the most dangerous working condition in the forming process was determined.Thirdly, the numerical simulation of mould assembly on mechanical and thermal structure coupling field were carried out to study the impact of temperature on the performance of internal key parts and evaluate the strength and stiffness of the mould in molding process. At the same time, the effects of the mould clamping force on the thermal stress were studied using the CAE technology to provide a reference for the selection of injection molding machines and settings of clamping forces during production.Finally, the two-dimensional tolerance analysis of mould assembly model was studied from aspects of the ideal situation and actual working condition based on the direct linearization method. And the influence of components deformation on the variable assembly tolerance was researched in this paper. The study above provided a more reasonable analysis method for the traditional tolerance analysis of injection mould. |
