扁挤压筒过渡曲面建模

为改善铝型材挤压过程中金属流动状况，通过引入流函数法建立基于流曲线的扁挤压筒型腔到模口之间过渡曲面的边界条件；同时采用保角映射方法，描述扁挤压筒型腔及模口处轮廓分别向单位圆的映射关系，构造过渡曲面入口和出口复杂图形的解析函数，解决了复杂三维模型向准三维对称模型的转换问题。两者结合得到过渡曲面上各点的流线方程，完成对过渡曲面的数学描述。为验证新构建曲面的合理性，对一矩形壁板成形过程进行模拟。结果表明：流线型过渡曲面有利于金属流动，并且有利于降低型腔面上的法向压力，可减少磨损、提高模具寿命。

TRANSITIONAL SURFACE MODELING OF FLAT EXTRUSION CONTAINER

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.