Nonlinear Modeling of a Magnetically Guided Machine Tool Axis

Contactless linear magnetic guides qualify as an alternative guiding principle for high speed cutting (HSC) machines, as they avoid frictional forces and wear. Tests on a prototype guide showed, that an adequate dynamic stiffness for a machine tool axis can be achieved with a magnetic guide. For the application to a prototype machine the concept has to be modified to fulfil the demands of machine design. This requires a new type of magnet arrangement as well as new models for the active parts. A new structure of magnetic guides is proposed basing on nonlinear models of the guiding magnets. Further, influences of eddy current effects and appropriate countermeasures will be discussed. The resulting machine axis will allow a dynamical stiffness of the guide of up to 150N/µm in the whole frequency range at a damping ratio near D=1.