NURBS及Hermite混合高速加工插补算法

在考虑工件轮廓的几何特点对加工效率与加工平稳性带来的影响的基础上,提出直线、NURBS及Hermite曲线混合高速加工插补算法.该算法在满足插补精度的基础上,对工件轮廓的线段长度、相邻线段夹角等几何参数进行定量分析,筛选出满足条件的部分进行NURBS曲线拟合.对存在尖角的曲线段间采用三次Hermite曲线进行衔接,改善了加工轮廓的光滑性.在满足最大弓高误差及最大加速度的要求下对直线段、NURBS曲线以及Hermite曲线进行混合插补,从而实现任意轮廓高速高质量的数控加工.对比分析和加工实验表明,采用该算法能够提高轮廓的连续性,有利于改善加工效率和加工平稳性.

NURBS-Hermite hybrid interpolation for high-speed machining

A hybrid interpolation algorithm which includes the interpolation of lines, NURBS and Hermite curves was proposed based on the impacts on the machining efficiency and stability exerted by the geometrical features of the machining contours. With full consideration of interpolating accuracy, several machining parameters were quantitatively analyzed, such as the length of machining lines, the angles between adjacent line segments. Tiny line segments which satisfy the fitting conditions were selected to be fitted into NURBS curve for further interpolation. Hermite curve, one of curves which suits high-efficiency manufacturing well, was used for the transition between lines (or line and fitted curve), between which a comparative sharp corner exists. This process can help to improve the continuity of the machining contours. All the interpolating elements, including lines, NURBS and Hermite curves were interpolated to realize high-speed and high-quality machining of any contours based on the maximal chord error limitation and maximal acceleration. Comparing analysis and related experiments show that the proposed algorithm can make the manufacturing process efficient and stable by improving the continuity of machining contours.