The Analytical Prediction of the Characteristics within Machined Surface Layer (Part 3)

The Thermal and Mechanical Effects on Machined Surface Characteristics

Abstract

The analytical method for the prediction of the mechanical state of machined surface layer was proposed. The residual stress and strain are caused by both the mechanical and the thermal state of cutting processes. Thus elastic-plastic deformation analysis and thermal analysis of cutting processes were simultaneously carried out using a finite element method. The tensile residual stress in the cutting direction was generated within the numerically machined top surface. At high speed cutting the flow stress of the primary shear zone ahead of the cutting edge increased because of increasing of strain rate. Furthermore the tensile stress parallel to cutting direction generated just behind the cutting tool was further increased by shrinkage of workpiece surface in cooling process. Thus the residual stress at high cutting speed became larger than that at low cutting speed. The curvature of the machined workpiece after unchucked increased with cutting speed, too. The residual stress and the temperature of the finished surface calculated were in good agreement with experimental data.