复杂自由曲面曲率分布特征对数控铣削性能的影响

针对复杂自由曲面的数控铣削性能难预测的问题，提出曲面曲率分布特征值，用于评价数控加工效率和加工精度。在构建的刀位面上策划等间距行走的刀位轨迹，建立刀位轨迹长度和刀具间的最大残余高度作为加工效率和加工精度的评价指标，分析曲面曲率分布特征值对加工效率和加工精度的影响。试验结果证明该自由曲面数控加工模式的有效性。分析发现，随着曲面曲率分布特征值增大，刀位轨迹长度和最大残余高度同时增加，导致加工效率和加工精度同时下降。此外，在曲面曲率分布特征值小于0.5 mm–1时，加工效率降低幅度不超过7 %，但加工精度却下降6～7倍。因此，曲面曲率分布特征值可用于评价和预测复杂自由曲面的数控铣削性能。

Effect of Curvature Distribution Feature of Complex Free-form Surface on CNC Milling Performance

In view of the difficulty of prediction of CNC milling performance of the complex free-form surface, the curvature distribution value is proposed to evaluate CNC machining efficiency and machining accuracy. Equal-interval tool paths are planned on the constructed cutter location surface. Tool path length and maximum scallop-height are regarded as the evaluation index of achining efficiency and machining accuracy respectively. The influence of curvature distribution value on the tool path length and maximum scallop-height is investigated. Experimental results show that it is valid for this tool path mode to conduct CNC milling of free-form surface. Analytical results show that along with the increase of curvature distribution value, both tool path length and maximum scallop-height increase, thus reducing machining efficiency and machining accuracy. In addition, when the curvature distribution value is less than 0.5 mm–1, the machining efficiency decreases by only 7 %, but the machining accuracy decreases by 6-7 times. Therefore, the curvature distribution value can be used to evaluate and predict the CNC machining performance of complex free-form surface.