流线型挤出模曲面构造

根据塑料挤出的特点，在编程实现对型材截面轮廓凸凹性自动判断的基础上，采用射线法与比例间隔法相结合的方法，确定流道入口圆周上型值点的位置．以三次多项式作为流道模腔型曲线的数学模型，依据流线型要求给出的初始、边界条件，得出型曲线的数学方程．构建了挤出模流道的三维参数化曲面模型．有限元分析结果显示，该方法创建的流线型流道模型，其流动稳定性和平顺性都优于直线型流道．

Surface Construction for the Streamlined Extrusion Die

Based on the characteristic of plastic extrusion, the convexity-concavity of sectional profile of section bar is automatically estimated by programming. By adopting method of ray tracing in combination with method of proportional spacing, the offset points on the circumference of channel inlet are located. Taking cubic polynomial as mathematical model of the skeleton curve of channel modular cavity and according to initial condition and boundary condition given to meet the requirement of streamline, the mathematic equations of skeleton curve are obtained. And then, a three-dimensional parameterized surface model is constructed for the channel of extruszon die. As shown by the result of finite element analysis, the streamlined channel model establishing by this method is better than linear type channel in stability and smoothness of its flow.