Development of a novel noncontact ultrasonic bearing actuated by piezoelectric transducers

Abstract

Many high-end power machines demand greater bearing performance in terms of running speed, precision, reliability, longevity, noise reduction, etc. An ultrasonic bearing based on Near-Field Acoustic Levitation (NFAL) effect is a kind of emerging noncontact gas bearing. Due to its self-aligning capability, the ultrasonic bearing can steadily run at a high speed under high precision. Actuated by piezoelectric transducers, the ultrasonic bearings do not produce much noise pollution. As a potential alternative to conventional bearings, a novel ultrasonic bearing with ability of carrying radical and axial loads simultaneously is first proposed in this study. For purpose of confirming the load-carrying capacity of the designed bearing, a comparison between the load-carrying models' theoretical calculation results and experimental data is conducted. The study of load-carrying capacity will provide a technical reference for the design of ultrasonic bearings. Besides, running performance of the bearing at high speeds is tested to study the bearing's friction torques in starting and high-speed stages. The load-carrying study proves that the ultrasonic bearing can carry at least 12 N radial levitating load and 6 N axial levitating load when excited by a voltage with amplitude 150 V p-p and frequency 16 kHz. The running performance experiments show that the bearing can operate steadily and consistently at a high speed, and the bearing's friction torque at a speed below 20000 r/min is less than 120 μN·m.