Numerical Investigations on Single Lip Deep Hole Drilling

Abstract

The surface quality and the subsurface properties such as hardness and residual stress of a drill hole are dependent on the cutting parameters of the single lip deep hole drilling process and therefore on the thermo-mechanical as-is state in the cutting zone and in the contact zone between the guide pads and the drill hole surface. In the present work, this highly dynamic and unsteady-state process including large deformation and heat generation FE simulations were carried out to analyze the mechanical as-is state in the drilling contact zone by evaluating the temperature, the feed force as well as the residual stress in the drill hole subsurface. Besides, in-process measurements as well as results from the hole drilling method to determine residual stresses are presented to verify the numerical results. For the simulations, the Johnson-Cook (JC) constitutive law was applied to represent the material behavior of the workpiece to cover strain rate as well as temperature dependent plasticity. The chip formation in the simulations was realized by means of the element elimination technique (EET).This contribution introduces the research project and the performed measurements with respect to the influence of the thermal and mechanical boundary conditions in this machining process focusing on the temperature and the feed force while drilling a 42CrMo4 steel and the residual stress in the drill hole subsurface. With this simulation approach, the chip formation as well as the residual stress distribution in thickness direction were reproduced successfully. The comparison of the process data, such as temperature, feed force or residual stress shows a qualitative agreement of the simulation and the experimental results, too.