Modeling And Simulation For Stability Analysis Of Milling Process Including The Effect Of Process Damping

Process damping can be a significant source to enhance the critical axial depth of cut especially at low cutting speeds. To establish the stability model of milling process including the effect of process damping,and get the stability lobes diagram(SLDs) accurately is particularly important for high efficient machining of hard-to-machine materials, such as titanium, nickel-based alloys, which can not be machined at high cutting speeds.The paper is focused on the research of process damping which is generated during cutting process. Firstly, the process damping is modeled,the corresponding coefficients are identified, and the effect of tool geometry and cutting conditions on process damping is investigated.Then the stability model that considering the effect of process damping is established, and the model is solved using the analytical method and the full discretization method. Lastly, the model and the corresponding solution approaches are validated by chatter verificaiton tests.As the modeling of process damping is inverstigated, the mechnism of process damping is firstly described and the indentation of tool flank into the undulaton surface of workpiece is regarded as the main source of process damping. On the basis, the indentation area is calculated using analytical and numerical approaches. Secondly, the coeffcients of process damping and indentation force are identified using energy equivalent method by equating the energy dissipated by indentation force with that dissipated by viscous damper. Lastly, the effect of tool geometry and cutting conditions on process damping is investigated through numerical simulation.As for the modeling of chatter stability for milling process in which the effect of process damping is considered, the milling system is firstly simplifed as a 2-DOF vibration system, and the dynamical differential equations are established based on the proces damping model and regenerating cutting force model. Secondly, the dynamic cutting forces are expressed as Fourier expansion with only the zero order and the firstharmonics, the critical axial depth of cut is achieved with the obtained eigenvalues which results in the stability lobes diagram. Lastly, the stability model of milling process and its analytical solution method is validated through chatter verification tests, and the effect of cutting conditions on the stability lobes diagram is investigated through numerical simulations.As the classical analytical method is unable to predict the additional stability lobes in low radial immersion milling, the stability model considering the effect of process damping is solved using the full discretization method, which is formerly used in solving the chatter stability model of milling proess in which the effect of process damping is not taken into consideration, and the rate of conergence of the method is investigated. At last, the method is also validated by chatter verification tests.