A novel approach to thermal modeling based on three-dimensional analysis in turning Inconel 718 with round insert

Abstract

The sharp increase of heat generated when processing difficult-to-machine materials is the main reason of short tool life and poor surface integrity. Temperature modeling plays a significant role in the mechanism of metal cutting, which can guide the optimization of cutting parameters. This paper proposes a modified three-dimensional analytical model of temperature prediction for oblique turning Inconel 718 with round carbide insert. The discretization of heat sources is indispensable to analyze the temperature rise due to the complicated geometry of uncut chip area. In this study, primary heat source (shear band) and secondary heat source (tool-chip interface) that divided into many increments through different discretization methods are considered to analyze thermal effects. For each increment of secondary heat source, the local contact length is calculated through a modified function considering global chip flow angle in oblique cutting. The local heat liberation intensities of primary and secondary heat sources are determined through analytical force prediction model. The variation of heat partition fraction with respect to immersion angle is given to study the characteristics of secondary heat source. Finally, a modified three-dimensional expression of temperature rises when turning with round insert considering semi-infinite medium is proposed based on classical thermal theory. The temperature distributions in chip, tool and workpiece can be determined through the proposed model. The results calculated through predictive model show good agreement with that given by finite element method (FEM) and experiments, which validates the correctness of the proposed model.