A hybrid model for turning force based on shear and extrusion deformation considering cutting-edge radius

Turning is a machining process widely used in many industries, such as aviation, aerospace, and optics. The existing turning force model considers the shear deformation and ploughing effect between the tool flank and machined surface of the workpiece while often ignoring the effect of the cutting-edge radius (CER) on the cutting process. Thus, it cannot comprehensively capture the cutting force in the turning process. In this study, the formation mechanism of the turning force is investigated considering the material-deformation mechanism during the turning process, and the effect of CER on the turning force is discussed herein. Further, a method to determine the boundaries of the undeformed chip region is proposed using a three-dimensional geometric model. The extrusion deformation is simulated considering the CER geometry and a three-item cutting-force model for shear–extrusion–ploughing established. Further, an analytical method to calculate the singular position is proposed. The validity of the proposed model is verified experimentally. The proposed model can be used as a guideline to aid further research on the surface integrity of turning-machined parts.