Cutting force modeling in end milling of curved geometries based on oblique cutting process

Cutting force prediction is the key issue for planning and optimizing the machining process. Based on an oblique cutting process, a novel method for modeling cutting force is proposed in end milling of curved geometries. Differentiating cutter along the axil, the working reference plane for an infinitesimal cutter element is calculated by utilizing differential geometry of curves. In the reference system of working normal plane, the connection between cutting parameters, e.g., force vectors, velocity vectors, chip flow angle, normal friction angle, normal shear angle and shear stress, is established by the minimum energy principle. Single-tooth straight milling tests are utilized for calibrating the cutting force coefficients, in which normal friction angle, normal shear angle and shear stress can be characterized by the dual-exponential function of instantaneous unreformed chip thickness. Two PCrNi3MoVA components with circular and Bézier curved geometries are machined. The experimental results show that variation of cutting force is influenced with the instantaneous feed direction and the curvature of the curve. Validity of the cutting force model is demonstrated by comparing predicted cutting forces with the experimental results.