Dynamic Modelling of High-Speed Spindle Supported by Active Magnetic Bearings in Presence of Defects

Abstract

During the machining process, the instantaneous cutting forces generate vibrations which reduce the effects of the machine’s performances. In general, the majorities of cutting force models assume that the cutting tool is geometrically perfect and focus only on the impact of different cutting parameters. Thus, several sources of errors in machining should not be ignored as they can generate vibrations and therefore affect surface quality. Accordingly, this paper will examine the surface topography resulting from the integration of machining errors, such as tool run out, tool tilting and workpiece displacement. The global studied system includes: the milling machine structure that is modeled using the Finite Element Method (FEM), two Active Magnetic Bearings (AMB), supporting the spindle, are modeled by dynamic stiffness and damping coefficients, and finally a predictive cutting force model was also incorporated. Based on this model, a modal analysis of the machine tool is established using the dynamic substructure method. The machined surface profile as well as time and frequency tooltip responses under the influence of the presented errors are also investigated.