Ultrasonic linear motor using the L-B mode Langevin transducer with an exponential horn

Abstract

An ultrasonic linear motor is proposed and fabricated by using the longitudinal and bending vibration double mode bolt-clamped Langevin type transducer to meet high power and speed requirements in the aerospace and semiconductor industries. The elliptical trajectory of the driving tip is formed by exciting the longitudinal and bending vibration with phase difference, which generates thrust force and normal force, respectively. An exponential shape horn is adopted to achieve a high linear speed. The classical theory of the transducer horn is used to determine the transducer’s longitudinal resonance frequency and configuration dimensions. FEM analysis is used to degenerate the longitudinal and bending vibration resonant frequencies. The different locations of the driving tip on the horn cause different elliptical-shaped vibration trajectories, and how the trajectory’s shape variation influences motor mechanical output is studied by using the FEM method. Simulation analysis and experiment results show that the motor has better performance when the driving tip is located at the antinode of the bending wave. Typical output of the prototype is no-load velocity of 480 mm/s and maximum driving force of 25 N.