Abstract: For improving the flow status of extrusion metal, the boundary condition of transitional surface between flat extrusion container cavity and the inlet of die is established based on the flow function method. With conformal mapping theory, the mapping functions from the profiles of cavity and die to the unit circle are acquired, and the complex 3D model of transitional surface is transformed to a quasi 3D symmetric model. According to the above methods(flow funwtion method and conformal mappirg Theory), flow function of each point in the transitional surface is obtained, and the mathematical representation of transitional surface is established. In order to verify the rationality of new surface, the forming process of a rectangular flat-plate is simulated by finite-element method. Simulation results show that streamline surface can improve the flow of metal, reduce the die pressure and die abrasion, and increase the die life.

Key words: Conformal mapping, Flat extrusion container, Flow function, Transitional surface