Study on Unbalance Magnetic Pull of the motorized spindle under different rotor eccentricities

Abstract

High-speed precision machining is one of the important development directions of modern machining technology, high-speed spindle system is widely used in high-speed machining, and motorized spindle is the main choice of the high-speed machine tool spindle. The electromagnetic force caused by rotor unbalance is one of main vibration sources of motorized spindle. Firstly, the research on the frequency spectrum characteristic of electromagnetic force under different rotor eccentricities is very necessary to suppress electromagnetic vibration. An electromagnetic finite element model was built for a motorized spindle based on Ansoft Maxwell in this paper. The electromagnetic force spectrum variation under the static and dynamic eccentricities is studied. The Unbalance Magnetic Pull(UMP) of the motorized spindle under different rotating speeds and different eccentricities are analysed. The results show that the motorized spindle with the static or dynamic eccentricity both produces new components in the electromagnetic force. Simultaneously, the eccentricity increase positively results in the increase of UMP amplitude. The UMP is constant under the rotor static eccentricity, which has a small impact on rotor vibration, while the frequency of UMP under the rotor dynamic eccentricity is the rotating frequency, which will increase the motorized spindle vibration. Finally, by the experiment the correctness of theoretical analysis and simulation are verified. This work provides a theoretical foundation for the fault diagnosis and dynamic balance of the motorized spindle.