Micro milling has been wildly used in the machining of the miniaturized components with high precision. The cutter used in micro milling usually has small diameter, ranged from 0. 1 to 1. 0mm. Then during the machining, the actually effective rake angle of the cutter is always not equal to nominal rake angle, thus the predicted accuracy of the milling force model will be low. In this paper, the effect of the cutting edge radius on the actually effective rake angle is discussed. Based on the analysis of the milling force on the rake surface, a modeling method for accurate prediction of the three dimensional milling force in micro milling operation is presented. From the angle of the effect of the cutter deflection on the cutting path of the cutter teeth, the prediction model of three dimensional milling force at an arbitrary cutter rotational angle is developed with this method. Meanwhile the computation method for instantaneous uncut chip thickness is proposed. The relationship between instantaneous cutting force coefficients and instantaneous uncut chip thickness is determined in the form of Weibull Function, the relationship between chip flow angle and cutting angular position of cutter is determine too. After compared with the reported research results of references, the predicted value of the cutting force is matched with the measured value, and the errors of the predicted value are between 4% and 9% .%微细铣削加工技术在微小型精密零件加工中有着广泛的应用.微细铣削加工采用的刀具直径范围在0.1～1.0mm之间,加工中刀具实际作用前角不恒等于名义前角,导致现有铣削力模型预测精度低.文章讨论了刀具切削刃刃口圆弧半径对刀具实际作用前角的影响；基于对前刀面的受力分析,提出了一种精确预测微细铣削过程三维铣削力的建模方法；该方法从刀具变形对刀齿切削路径影响的几何关系出发,建立了刀具在任意旋转角所受的三维铣削力预测模型,并构造了瞬时未变形切削厚度的计算方法;提出了以Weibull方程的形式来表示瞬时切削力系数与瞬时未变形切削厚度之间的关系,建立了切屑流动角与刀具切削位置角的关系式.与文献已有切削试验结果对比表明,文章的铣削力预测值与实验值能够较好地吻合,预测的切削力相对误差集中在4％-9％之间.
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