The vibration analysis of a high-speed motorized spindle system considering nonsmooth bearing restoring force and unbalanced magnetic pulling force

As an important equipment in the field of modern machining, high-speed motorized spindle has a broad application prospect and important research significance. This paper focuses on the dynamic behaviour of high-speed motorized spindle systems. By using the lumped mass method to simplify the motorized spindle system, nonlinear factors such as Hertz contact and bearing time-varying stiffness are considered in the model. In addition, the effects of unbalanced magnetic force and unbalanced mass on the whole system are considered.On this basis, a system of 18-degree-of-freedom differential equations is established to describe the motion of the system. The effects of spindle speed, rotor eccentricity, air gap eccentricity and bearing parameters on the vibration behaviour and stability of the spindle are investigated using analytical methods such as bifurcation diagrams, time-domain waveforms, spectra, trajectories and Poincaré sections. The results show that the variation of spindle speed and bearing parameters has a significant effect on the vibration behaviour and stability of the spindle. The study provides a valuable reference for the design and optimisation of motorized spindle systems and bearing selection.