Numerical Analysis And Simulation Method For Extrution Process

Extrusion is one the most important method of metal plastic forming process. The theory research and technology development of it are faced with an important new stage of development. The combination of basic theory research and technological innovation will promote the further development of metal extrusion. There are many technological factors are closely related to the material flow in extrusion, such as the product structure, properties, surface quality, dimension and shape accuracy, finished product rate, the optimization of extrusion die design and extrusion efficiency etc. It is of an extremely important theoretical significance to establish a reliable mathematical-mechanical model to control the material flow behavior in the extrusion process. On this basis, the rational and effective optimum design methods of extrusion process are the key sally port for the development of extrusion technology and improvement the quality of extruded products.There are two kinds of main research methods about the rule of material flow in extrusion process, one is the numerical analysis method, the other is the experimental method. Those methods have its independent characteristic and can be used in specific research object. However, all of those methods have not been used widely in engineer practice for its obvious limitation. For a long time, the processing parameters in technological design calculated with empirical formula. One of reason is lack of mathematical-mechanical models with plastic theoretical basis, which can connect the physical parameters and geometrical parameters in extrusion process, the other is numerical simulation technology can not be used correctly in metal bulk forming and can not effectively guide the productive practice. In this paper, backward extrusion with cup-shaped mold, forward extrusion with cone-shaped mold and upsetting-extruding composite deformation process are researched with numerical analysis method and numerical simulation. In this way, the elemental regularity between physical parameters and geometrical parameters can be researched with numerical formula in place of empirical formula.The analytic relationship between physical parameters and geometrical parameters was researched with numerical analysis method based on classical plastic theory. The numerical analysis model with plastic theory background was established. At first, with precise graphing method, the slip line field was researched for varying degrees deformation of backward extrusion with cup-shaped mold and forward extrusion with cone-shaped mold in different friction boundary conditions. Then, the function equation about physical parameters (deforming force, stress etc) and slip line field parameters was researched. The analytical relations about slip-line field parameters and key geometric parameters, such as die size, extrusion ratio etc, were established with curve fitting, differential equation, iterated interpolation method and extremum method. Based on slip-line solution, the numerical analysis model between physical parameters and geometrical parameters (die dimension, extrusion ratio etc) was researched. Based on modular theory, analytic model of upsetting-extruding composite deformation with complex boundary conditions were researched with superimposed slip-line field method. The numerical analysis model of backward extrusion with cup-shaped mold process was verified with experiment finaly. The influence regularity of die cone angle for the process of deformation in forward extrusion with cone-shaped mold process was investigated.The application of the Lagrange mesh in solid behavior and Euler mesh in fluid behavior was discussed respectively. Limitations and advantages of the finite element method and finite volume method for numerical simulation of large metal deformation were investigated. Comparative simulation for backward extrusion process with cup-shaped and forward extrusion process with cone-shaped mold was studied with FEM and FVM. The influence of physical quantity for the deformation was studied at the same time. The application method of FEM with DEFORM and FVM with MSC.SUPERFORGE was also researched. Upsetting-extruding composite deformation process was simulated with MSC.SUPERFORGE and the technological parameters were adjusted based on the result of simulation. In this way, the optimum design can be realized.Blindness of empirical formula in the technological design can be avoided with numerical analysis model. As object function, it can be used for Optimum design of extrusion. Realistic numerical simulation of deformation can be used to research the influence law between the physical parameters and geometric parameters and the realization of computer-aided optimal design.