In order to obtain large vibration amplitude in ultrasonic vibration cutting, the transducer demands an additional inductance to match its native capacitance. The objective of this paper is to determine the optimum oscillation frequency of the resonant tank constructed using additional inductance and the transducer's native capacitance. By analyzing the transducer impedance matching on the impedance circle deduced from the transducer equivalent circuit model, the optimum oscillation frequency is found to be not equal to the transducer mechanical resonance frequency, but below it. Frequencies near the optimum oscillation frequency are referred to as the optimum premechanical resonance zone. Consequently, the Theory of Ultrasonic Transducer Impedance Matching at Premechanical Resonance Zone is proposed. Comparative experiments are conducted at different frequency zones. The results reveal that when the transducer is excited at the premechanical resonance zone, the vibration amplitude increases and the excitation voltage signal is the desired sine wave, compared to that when excited at the mechanical resonance frequency and the postmechanical resonance zone. The experimental results confirm the feasibility of this proposed theory.

In this study, to address the low efficiency for conventional ultrasonic-assisted drilling (UAD) of carbon fiber-reinforced plastic and titanium alloy (CFR