Experimental And Simulation Investigation On Fatigue Failure Of High Speed Intermittent Cutting Tools

High-speed machining (HSM) technology has become the mainstream machining technology. However, in high-speed intermittent cutting, Tool failure is very easy to happen due to the mechanical impact with the tool going into or out from workpiece and the thermal shock during the cutting stage and void cutting stage. Research on tool breakage failure mechanisms will be of great significance for prolonging service life of tools. In this paper, the temperature field and stress field of the cutting tool in the high-speed intermittent cutting were studied by the combination of experiments and FEM simulation. In addition, the fatigue crack growth of the tool was simulated and analyzed, which was used to study the mechanism of fatigue damage failure of the cutting tool in high-speed intermittent cutting.First, The experiment of high-speed intermittent turning hardened steel 20CrMnTi was conducted and the change of cutting force with tool breakage was studied, which provides experimental evidence for the modeling of machining simulation. The optimum of cutting parameters was obtained for each cutting stages. The cutting temperature and chip morphology in the high-speed intermittent turning as well as the fracture surface were analyzed revealing the failure mechanism of tool in high-speed intermittent turning hardened steel.A simplified two-dimensional cutting model of the high-speed intermittent turning was simulated using the finite element software Abaqus. The stress field on the rake and flank was analyzed at cut-in and cut-out in the high-speed intermittent cutting. Besides, the evolution of stress field on the rake and flank in the cutting stage of the high-speed intermittent cutting was studied to obtain the stress distribution law. Moreover, the comparison analysis of stress and cutting temperature under thermo-mechanical coupling and thermol mechanical uncoupling was used to reveal the stress distribution in the high-speed intermittent cutting.The technology of zero-thickness cohesive force finite element (CZM) and XFEM was used to simulate the growth of fatigue crack of tools in high-speed intermittent cutting on the Abaqus platform. The fatigue crack growth path of tools under different cutting parameters and tool angels was simulated and analyzed and the orientation of tool fatigue crack growth under high-speed intermittent cutting was studied to verify the failure mechanism of tool breakage in high-speed intermittent cutting.