数控加工中基于自由曲面表面特性的刀具路径安排

目前CNC上的轨迹控制功能仍主要是直线和圆弧插补,因此当加工自由曲面时,大多只能采用直线或圆弧逼近算法来对曲线进行逼近处理。针对数控加工的实际需求,现在数控系统技术人员对数控机床插补器进行研究并开发出了许多曲线和曲面插补功能。基于曲线插补,在保持进给速度尽可能恒定的条件下,对刀位路径和刀位速度进行离线的曲线拟合,以便于得到用于数控加工的刀位文件。这种方法能有效解决进给速度的波动问题,并能有效压缩刀位文件。为此,提出几种算法来拟合刀位路径和刀位速度轮廓曲线。曲线和曲面插补在数控代码数据量和逼近误差方面都有较大的改善。

CNC Tool Path Planning Based on Characteristics of Free-form Surface

At present,computer numerical control(CNC) machines still use linear interpolation and arc interpolation to control their trajectories.Therefore,in machining a free-form surface,most of them use the linear and arc approach algorithm to approach its curves.Accordingly CNC technicians study the interpolator of a CNC machine tool and develop many functions of curve interpolation and free-form surface interpolation.Using the curve interpolation,they perform the off-line curve fitting of cutter location(CL) path and CL feeding velocity under the condition that the latter is kept as constant as possible.Thus they obtain CL files to be used in CNC machining.This method can effectively reduce the fluctuation of feeding velocity and condense CL files.For these reasons,we propose several algorithms for fitting the profile curves of CL path and CL feeding velocity.The algorithm notably improves the curve and freeform surface interpolator in terms of the number of CNC codes and approach errors.