面向数控机床的等距双NURBS刀具轨迹插补技术

Equidistant Double NURBS Tool Path Interpolation Technology for CNC Machine Tools

五轴数控机床具备两个旋转轴,加工柔性好、加工效率高,但同时其几何误差与空间误差存在复杂耦合关系,导致刀具的运动精度较差。为了保持刀具具有较为精准的运动轨迹,提出面向数控机床的等距双NURBS刀具轨迹插补技术。考虑到待切削工件表面的形状和特性,通过线性微分方程精确地描述待切削工件复杂的三维曲面形状,并利用初始插值点权重改变初始插值点的位置和权重,生成平滑度较高的刀具路径。在此基础上,通过NURBS曲线参数推导,实现五轴数控切削加工刀具轨迹插补。实验结果表明:设计的刀轨控制方法可以将刀轴点轨迹误差控制在-2×10^(-3)mm~2×10^(-3)mm之间,且控制精度高、效果好。可以实现刀具的精确运动和姿态调整。

Five axis CNC machine tools have two rotating axes,which have good machining flexibility and high machining efficiency.However,at the same time,there is a complex coupling relation between geometric errors and spatial errors,resulting in poor tool motion accuracy.In order to maintain the precise motion trajectory of the tool,an equidistant dual NURBS tool trajectory interpolation technology for CNC machine tools is proposed.Considering the shape and characteristics of the surface of the workpiece to be cut,a linear differential equation is used to accurately describe the complex three-dimensional surface shape of the workpiece to be cut,and the position and weight of the initial interpolation point are changed using the weight of the initial interpolation point to generate a tool path with high smoothness.On this basis,through the derivation of NURBS curve parameters,the five axis CNC cutting tool trajectory interpolation is achieved.The experimental results show that the designed tool path control method can control the error of the tool axis point trajectory within-2×10^(-3) mm~2×10^(-3) mm,with high control accuracy and good performance.It can achieve precise motion and posture adjustment of cutting tools.