Abstract: Ultrasonic transducer is an energy transducing system, which can transduce electricity from ultrasonic power to machine vibration in ultrasonic vibration machining. Because ultrasonic transducer is a capacitive load, in order to transduce the electricity energy from ultrasonic power to ultrasonice transducer’s machine vibration, it’s necessary to add an appropriate inductor between them. On the other hand, ultrasonic transducer is a powerful nonlinear time-varying system, and it’s characteristics of impedance and machine vibration differ distinguishingly at different frequency. So, the key of enhancing vibration machining quality is how to match ultrasonic transducer at an appropriate frequency point. By means of rightly selecting ultrasonic transducer’s equivalent circuit model and deeply analyzing and researching on the impedance circle induced by it’s model, it can be concluded that ultrasonic transducer’s vibration amplitude is maximal and it’s vibration wave quality is the best when it is matched at it’s passed inherent resonance zone. So, the passed inherent resonance zone is the optimal working frequency zone. Consequently, the theory on ultrasonic transducer’s matching at it’s passed inherent resonance zone is provided. The experiment results show that this theory is true.

Key words: Matching, Passed inherent resonance zone, Ultrasonic transducer