Adaptive Spindle Balancing Using Magnetically Levitated Bearings

摘要

A technological break through for supporting rotating shafts is the active211u001emagnetic bearing (AMB). Active magnetic bearings off some important advantages 211u001eover conventional ball, roller, or journal bearings such as reduced frictional 211u001edrag, no physical contact in the bearing, no need for lubricants, compatibility 211u001ewith high vacuum and ultra-clean environments, and ability to control shaft 211u001eposition within the bearing. The disadvantages of the AMB system are the 211u001eincreased cost and complexity, reduced bearing stiffness and the need for a 211u001econtroller. Still, there are certain applications, such as high speed machining, 211u001ebiomedical devices, and gyroscopes, where the additional cost of an AMB system 211u001ecan be justified. The inherent actuator capabilities of the AMB offer the 211u001epotential for active balancing of spindles and micro-shaping capabilities for 211u001emachine tools. The work presented in this paper concentrates on an AMB test 211u001eprogram that utilizes the actuator capability to dynamically balance a spindle. 211u001eIn this study, an unbalanced AMB spindle system was enhanced with an LMS (Least 211u001eMean Squares) algorithm combined with an existing PID (proportional, integral, 211u001edifferential) control. This enhanced controller significantly improved the 211u001econcentricity of an intentionally unbalance shaft. The study included dynamic 211u001esystem analysis, test validation, control design and simulation, as well as 211u001eexperimental implementation using a digital LMS controller.