The Mechanical-thermal Behavior In The Deformation Zone Of Closed Extruding Fine Blanking And The Influence On Forming

Closed extruding fine blanking is a new fine blanking process which can make up for the shortcomings of the existing fine blanking process,and it is suitable for processing material with low plasticity and large thickness,as the time of invention is not long,the basic problems involved in the closed extruding fine blanking process need to be studied.This paper mainly focuses on force and heat behavior and the effect of the force and heat behavior on the forming of the closed extruding fine punching deformation zone.These problems are: The relationship between the force-heat behavior and the formability in the deformation zone;The friction problem in the deformation zone;Temperature distribution and thermo mechanical coupling in the deformation zone.The above research will lay the foundation for the development of the closed extruding fine blanking process.First,the relationship between the plasticity of the deformation zone and the quality of the fine blanking parts and the factors that affect the plasticity of the material were analyzed.The relationship between the stress state of the material,the plastic deformation heat of the material,friction between material and mould,and the plasticity of the deformation zone in the plastic processing was analyzed.The relationship between the mechanical-thermal behavior in the deformation zone and the quality of the fine blanking was also clarified.Secondly,the basic mechanics of the deformation zone was analyzed by the principal stress method,The real stress-strain of the material was obtained by tensile test,a flow stress model was chosen to conform to the closed extruding process,the distribution of stress and strain in the deformation zone of the material in the closing stage of the main and secondary die and in the punching stage of punch was obtained.The effect of the plasticity of the material on the surface quality of the formed surface was studied through physical experiments.The materials of different outer ring filling rates was selected for numerical simulation and physical experiment of closed extruding fine blanking process,and the relationship between outer ring filling rate and hydrostatic pressure and deformation quality of deformation zone was obtained,and verified by physical experiments.Thirdly,the deformation friction model was established,the friction force between the die and the blank in the closed extruding fine blanking process was analyzed.finite element simulation was carried out under the different friction coefficient conditions of the contact surface of the material-die,the material-main concave die,and the contact surface friction coefficient conditions were obtained when the proportion of the bright band of the forming parts is the highestFinally,the finite element software was used to simulate the temperature distribution in the deformation zone,The temperature distribution,the law of temperature change and the law of stress change of the deformation zone at different stages were obtained.The different counter force,blanking speed and outer ring filling rate are selected respectively,and the forming process under different conditions was simulated,the influence of different forming process parameters on the temperature distribution and size in the forming process was obtained.In this paper,the results of research on the forcr-thermal behavior such as material plasticity,stress state in the deformation zone,friction and temperature,and the effect on the forming quality in closed extruding fine blanking are laid for the industrial application of the new technology of closed extruding fine blanking.