Effect of helical tool orientation on the stress-strain state of hardened carbon steel parts

The objective of this study is to determine the optimal orientation of a helical tool to maximize stress within the deformation zone and residual compressive stresses in hardened components. The stress-strain state of a cylindrical workpiece under helical tool action was assessed based on the magnitude of temporary stresses occurring within the deformation zone and residual stresses after unloading the hardened workpiece. Finite element modeling and numerical calculations revealed that with increasing tool axis rotation angle, tool contact with the workpiece deteriorates, leading to uneven deformation and, consequently, an uneven distribution of residual stresses. It was established that, for helical SPD, the optimal tool axis rotation angle is 0˚, meaning that rotating the tool in the vertical plane is impractical. As the number of tool turns increases from 1 to 3, the intensity of temporary and residual stresses increases monotonically by 26% and 30%, respectively. Effective hardening is ensured by a working tool with two profile threads.