Research And Design Of Miniature Piezoelectric Ultrasonic Transducer

Ultrasound has important applications in national defence industries, mechanical andelectronic engineering, manufacturing and medical treatment. As its application areas develop,ultrasound technology is becoming increasingly significant in national economy. Comparedwith traditional method in medical treatment, ultrasound has great advantages in diagnosisand treatment. At present, many research targets in medicine are in small scale, and even in acellular or molecular level. Therefore, in order to reduce harm and improve the purity oftarget subjects, the miniaturization of ultrasonic system becomes necessary. And the centralproblem of miniaturization is ultrasonic transducer and tool miniaturization. In this research, anew miniature piezoelectric ultrasonic transducer was designed, manufactured and optimizedand it can be used for micro cutting. The influences of micro defects and loads of transducerwere also studied. The research results are as follows:(1) After the selection of component materials, mechanical structures were calculatedaccording to the four-terminal network method. The finite element model of transducer withtwo ends free was established. Through modal and harmonic analysis, resonance frequency,nodes amplitudes and modes of vibration were gained.(2) Component and assembly drawings were given, on the basis of which eachcomponent was manufactured, and ultrasonic tool was fabricate by electrochemical corrosion.The miniature piezoelectric ultrasonic transducer was64mm long and maximum diameter was6mm.(3) In allusion to the phenomenon abnormal heat, finite element model of micro-crack onultrasonic tool during operation was established. Experiments and simulation analysis wereemployed to study the dynamical contact behavior together with heat generation ofmicro-crack in working condition. The results showed that vibration of crack surfaces did notsynchronize. The temperature of middle part were higher than other parts obviously, and ittended to increase quickly and decrease to stable state.(4) Each key parameters of transducer were measured with system admittance measurement platform and longitudinal amplitude measurement platform. Theadmittance-frequency relation and amplitude-volt relation of ultrasonic transducer wereestablished, modes of vibration and resonance frequency were calculated with measurements.Compared with design and simulation results, the reasons for differences were analyzed, andtransducer structure were optimized.(5) Matching inductor of experiment loads was calculated through the admittance andfrequency variations of different loads, which offered data reference for efficiencyimprovement. Miniature ultrasonic piezoelectric transducer cutting system was established formicro-tissue cutting. Compared with static cutting, ultrasonic cutting showed the advantagesof minor harm, sharp cut and simple operation.