Adaptive Spindle Damping System with Active Electromagnetic Bearing

Advanced machining operation require ultra-high-precision motor spindles, tool chucks and cutting tools, free from tool deflection and vibrations. Available motor spindles and tool chucks generate uncontrolled process deviations at several eigenfrequencies, leading to geometrical and surface distortions. This paper presents a patented design method of a non-typical Adaptive Spindle System with an additional electromagnetic bearing based on mechatronics and adaptive control methods for advanced cutting technologies. In comparison to known active magnetic bearing systems for rotor orientation, a rotor damping is investigated between roller bearings. The static and dynamic performance determination of the AIS motor spindle have been carried out at a speed of up to 15,000 rpm on a test bench with actuator stimulated forces and displacement sensors. The analysis of time-domain and amplitude-frequency characteristics confirmed the demand in adaptive closed-loop control methods compensating tool deflections and vibrations at eigenfrequencies.