Modeling and prediction of cutting forces in end milling of curved surfaces

A novel mechanistic cutting force model is presented for end milling of curved surfaces, including the effect of instantaneous feed direction. In machining of curved geometries where the curvature varies continuously along tool path, the cutting parameters, such as feed per tooth, entry/exit angle, and instantaneous undeformed chip thickness, vary along tool path. The cutting process of curved surface is discretized into a series of steady-state cutting processes at intervals of feed per tooth, and a vector model for these parameters of each segmented cutting process is presented. The Fourier series expansion is used for deriving the cutting force model. Combined with the milling force coefficients fitted by a series of slot milling tests, the predicted cutting forces in machining PCrNi3MoVA workpiece with circular and Bezier curve geometries are achieved, respectively. The prediction accuracy of the model is validated experimentally and the predicted and measured results correspond well with each other.