An analytical force mode applied to three-dimensional turning based on a predictive machining theory

Abstract

Cutting forces play an important role in the three-dimensional turning processes and are commonly calculated by the mechanistic or empirical models which are considered time-consuming and impractical for various cutting conditions and workpiece-tool pair. Therefore, this paper proposes an analytical force model in three-dimensional turning based on a predictive machining theory, which adopts the non-equidistant shear zone model and regards the workpiece material properties, tool geometry and cutting conditions as the input data. In this model, the real cutting edge of the turning tool is decomposed into a series of infinitesimal cutting elements and the cutting action of which is equivalent to the oblique cutting process with the imposed condition that all chip elements flow in the same direction on account of the interaction between adjacent chip ones. Consequently, the cutting force components applied on each cutting element can be calculated using a modified version of predictive oblique cutting model and the total cutting forces are obtained by summing up the forces contributed by all cutting elements. Finally, the global and local chip flow angles are investigated under various conditions of tool geometry (edge inclination angle, lead angle, nose radius) and cutting parameters (depth of cut, feed, cutting velocity) in this model. Furthermore, a detailed parametric study is provided by the proposed analytical model of cutting forces in order to analyze the influences of cutting parameters and tool geometry on cutting forces, which are verified respectively by the experimental data. Good agreement shows the effectiveness of the proposed analytical model.