变曲率曲面周铣铣削力建模与分析

Modeling and analysis of milling force in peripheral milling of curved surface with variable curvature

为实现变曲率曲面周铣铣削力预测,阐述了铣削力基本模型,基于直线插补给出了刀具位置角、进给方向角及加工时间的确定方法。采用坐标变换法推导出包含刀具偏心跳动的未变形切屑厚度新算式,提出包含工件边界的切入角与切出角计算方法。利用提出的方法对铣削力进行预测,预测值与实测值在变化趋势和大小方面均具有良好的一致性,证实了铣削力模型的有效性。在此基础上分析了曲率对工艺几何参数和铣削力的影响,结果表明:曲率对凹曲面铣削的影响较凸曲面更加显著,铣削凹曲面时切角区间、未变形切屑厚度、进给方向和法向铣削力峰值均随曲率增大而增大,铣削凸曲面时则减小。进给方向和法向铣削力谷值是否受曲率影响与径向切深有关。

To predict the milling force for peripheral milling of curved surface with variable curvature,the basic model of milling force is described. A method is proposed to determine the angular position,feed direction and machining time based on linear interpolation. With coordinate transformation,a new analytical formula is presented to calculate instantaneous uncut chip thickness in presence of cutter runout. In addition,the entry angle and exit angle are described considering the workpiece boundary.With the proposed method,the milling forces are simulated. The predicted values and measured values have good agreements both in variation tendency and magnitude,which shows that the presented milling force model is efficient. Further,effects of curvature on process parameters and milling forces are simulated. And the results show that effects of curvature on milling of concave surface are more significant than convex surface. In milling of concave surface,the engagement angle,uncut chip thickness,force peaks in feed direction and normal direction increase with the increase of curvature. In milling of convex surface,the result is opposite. The effects of curvature on force troughs relate to the radial cut depth.