一种复杂曲面类增材制造零件分层截面生成算法

A Layered Section Contour Generation Algorithm for Additive Manufacturing Parts with Complex Surfaces

针对传统增材制造分层方法对复杂曲面类零件STL模型分层易造成部分层面轮廓线失真的问题,提出一种基于NURBS曲线的复杂曲面类零件分层截面轮廓生成算法。针对STL模型数据量大和分层速度慢的特点,采用了分组排序的求交算法进行分层,生成截面轮廓点云数据。以切平面与STL模型三角面片的交点作为NURBS曲线的型值点,设定型值点的权值,利用矩阵形式和切失边界条件确定了NURBS曲线的权因子,求解NURBS曲线的控制顶点,采用矩阵形式建立了各切片层的截面轮廓所对应的NURBS曲线方程,绘制了基于NURBS曲线的各层层面轮廓。采用基于NURBS曲线的复杂曲面类零件分层截面生成算法对燃气轮机中压缸动叶片和Ganesha模型进行了分层试验仿真和误差分析。进行了燃气轮机中压缸动叶片的打印试验,通过测量表明:采用本算法打印叶片的轮廓度偏差值符合要求,相比传统算法打印的叶片精度更高,从而验证了所提出的基于NURBS曲线的复杂曲面类零件分层截面生成算法的可行性和准确性。

Aiming at the problem of the traditional additive manufacturing slicing algorithm easily leading to the distortion of the contour lines of the STL models of complex surface parts, a layered section contour generation algorithm for complex surface parts based on the NURBS curve is proposed. Aiming at the characteristics of large quantity of STL model data and slow layering speed, an intersection algorithm based on grouping and ranking is used to layer models, which could generate the point cloud data of the cross-sectional profile. The intersection points of the tangent plane and the STL triangle facet are used as the data points of the NURBS curve, and the weight of the data points is set. The weight factor of the NURBS curve is determined by the matrix form and the cut loss boundary conditions, and the control vertices of the NURBS curve is solved. The NURBS curve equation corresponding to the contour lines of each slicing layer are established in a matrix form, and the layer contours based on the NURBS curve are drawn. The layered section contour generation algorithm for complex surface parts based on NURBS curves is adopted to perform layering simulation and error analysis on the gas turbine medium-pressure cylinder moving blade and Ganesha model. Finally, a printing experiment of the gas turbine medium-pressure cylinder moving blade is performed. The test results show that profile deviation value of the blade printed by the algorithm of this study met the requirements and its accuracy is higher compared with the blade printed by traditional algorithm. It can be seen that layered section contour generation algorithm for complex surface parts based on the NURBS curve proposed here is feasible and accurate.