切削シミュレーションによるニッケル基超耐熱合金の被削性評価

Abstract

A finite element modeling of machining of a nickel-base superalloy is presented for aiming at understanding its cutting performances and improving cutting conditions, cutting efficiency and machined surface integrity. A formulation with a dynamic explicit thermo-elastic plastic finite element method, penalty methods dealing with mechanical and thermal boundary conditions on the tool-chip contact area, and mass scaling for efficient calculation gave chip formation and cutting processes of Inconel X750 under a wide range of cutting conditions. Calculated and experimental results agreed well in cutting forces, shear angle, tool-chip contact length and stress distribution on the rake face. It was found that the rake angle had a great influence on the predicted thickness of affected layer for constant undeformed chip thickness while the cutting speed had a little. The instantaneous ratio of heat into the tool to the energy consumption due to friction on the rake face was calculated. At the beginning of cutting the ratio was greater than 100%, then decreased to 100% and less. From the results it was suggested that for better interrupted cutting with good tool cooling, cutting length per tooth may be taken as one at the ratio of 100%.