基于数控代码的构造曲面法向矢量的求解方法

NC Code Based Normal Vector of Constructed Free-form Surface

采用区别与传统全局建模的方法,基于三坐标数控代码直接提取出曲面的表面数据点,然后用散乱点三角网格模型,先求出空间坐标点两个方向的切向矢量,进而求出曲面的法向矢量.最后用算例说明了该计算方法较传统的全局建模方法有计算量较小而精度较高的优势.

Five axis NC （numerical control） machining of mold surfaces needs the normal vector of machining points to determine the position of the cutter, and the main method of generating mold surfaces now is using the constructed free-form surface. The problems arise when it is difficult to describe the constructed free-form surface using mathematical formula, or there is no such a mathematical formula at all. To tackle this problem, different from the traditional global modeling method, in this paper we use the three coordinates NC code to extract the surface point directly by adopting the triangular mesh model, calculating two directions of the tangential vector then calculating the surface normal vector. The proposed method proves to be time-saving in calculation with higher accuracy.