Study On The Radial-Torsional Vibration Mode Of Pattern Conversion Type Piezoelectric Ultrasonic Transducer

With the development of industry and progress of technology, the requirement of ultrasonic transducer vibration modes is more and more, especially in rotary maching,cutting,ultrasonic motor etal. Composite vibration modes are mainly longitudinal-torsional, longitudinal-bending, bending- torsional, these modes are been swithed from single mode.The stator of ultrasonic motor is a composite vibration mode transducer and become hotspot in recent years because its high torque and low noise. Ultrasonic motor replace traditional electromagnetic motors in anti-electromagnetic interference and low noise instruments. The types of ultrasonic motor also be continued innovation and optimization along with the increasing demands in some areas.This paper proposes a radial-torsional composite vibration mode of piezoelectric ultrasonic transducer. By deriving the theory, seting up the model and conducting the experiment to analysis the vibration characteristics of piezoelectric ultrasonic transducer. The main research contents are as follows:1.The longitudinal-radial coupling type of power synthesis ultrasonic vibration system constituted by longitudinal vibration ultrasonic transducer and the radial vibration of slit type concentrator is studied through harmonic superposition method. Through the electromechanical analogy principle derived equivalent circuit and resonance frequency equation, the amplitude magnification coefficient, the curve of the first and the second order resonance frequency with radius ratio. The results show that the amplitude magnification coefficient is larger at the second order, the second mode concentrator and transducer can synthesize large ultrasonic power. The theory, the simulation and the experimental results are in a good agreement.2. The vibration characteristics of equivalent thickness inclined slit type piezoelectric ultrasonic transducer were studied. Discussing the radial and torsional vibration of metallic annular plate respectively, with the introduction of radial-radial and radial-torsional coupling coefficient, the radial vibration and torsional vibration equivalent impedance coupled to the mechanical side of the piezoelectric ceramic disk radial vibration circuit, then the equivalent circuit and the resonance frequency equation are obtained. Theory, simulation and experimental methods were used to analyze the relationship of bevel and radius ratio with resonant frequency.3. The vibration characteristics of linear variable thickness inclined slit type piezoelectric ultrasonic transducer were analyzed. Using ANSYS finite element simulation to finish modal analysis, harmonic response analysis and transient analysis research. Getting the resonance frequencies of the transducer, the antiresonance frequency and admittance frequency curve, simulating the same location node’ elliptical motion trajectory at the resonant frequency of bevel 30 degree,45 degree,60 degree transducer, compared the same location node’elliptical motion trajectory with equivalent thickness inclined slit type transducer.4. Testing the resonance frequency of several groups of samples with different bevel transducer, by giving piezoelectric plate Z direction of polarization, the inclined slit type transducer produce radial-torsional composite mode vibration, the resonance frequency of experimental measured by impedance analyzer are in a good agreement with the simulation results.