An ultrasonically levitated non-contact sliding table with the traveling vibrations on fine-ceramic beams

Abstract

This report presents a new design and its performance test for a non-contact sliding table by ultrasonic levitation. A slider is levitated by an acoustic radiation force emitted from two vibrating guide rails, and a flexural traveling wave propagated along the guide rails allows a non-contact transportation of the slider. The reduction of the abrasion and dust generation, high cost performance and simple structure are expected. The profile of the sliding table was designed using the finite element method (FEM) for high levitation and transportation efficiency. The prototype sliding table made of alumina ceramics for obtaining higher machining accuracy and rigidity. A structure consists of a pair of 152-mm-long beams with a triangle cross-section, two bolt-clamped Langevin transducers (BLT) with the diameter of 11 mm and cross-shaped vibration direction converters to permit low height of 11 mm. A slider with the length of 40 mm was designed to fit the two rail guides. The flexural mode standing wave was observed along the guide rail at the resonance frequencies of 89.4 kHz, and the levitation of the slider could be confirmed even if the levitation distance is less than 10 µm. The levitation distance of the slider was measured with increasing the slider's weight, and the levitation force, the levitation rigidity and the displacement amplitude of the levitating slider in the vertical direction were measured to be 4.8 kN/m 2 , 2.5 kN/µm/m 2 and under ±1 µm, respectively, in the case of the levitation distance of 2.2 µm. The non-contact transporting of the slider was achieved with the phased drive of two transducers. By controlling the phase difference, the slider transportation direction could be switched. The maximum thrust and the transportation speed were 1.3 mN and 34.6 mm/s, respectively, in the case of the slider's weight of 107 g.