Study On Driving Characteristics Optimization And Temperature Adaptability Of An Ultrasonic Drill

Asteroids are small objects born in the early stage of the formation of the solar system.They retain the historical information of the formation of the solar system,and they have considerable potential mineral value.The study of asteroids is of great significance to scientific research,disaster prevention and development.Asteroid surface anchoring is the basis of in-situ scientific exploration and resource developmen.The impact ultrasonic drill has the advantages of small volume,light weight and low drilling pressure,which is very suitable for asteroid surface anchoring drilling.In this paper,the structure design,driving characteristics and high/low temperature adaptability of the impact ultrasonic drill are studied.In order to design the ultrasonic drill with reliable performance and excellent drilling speed,the transducer size is preliminarily confirmed according to the stress wavelength and standing wave distribution.The finite element analysis method is used for modal simulation to analyze the influence of configuration size on the amplitude distribution and vibration velocity ratio of the transducer.The high output performance transducer is designed based ion the result of modal simulation.According to the motion characteristics of ultrasonic drill,the components of free mass,drilling tool and drill shell are developed.Based on the analysis of BVD equivalent circuit model,the evaluation criteria and detection methods of transducer driving performance are studied.Due to the dramatically changing drilling load and unstable resonant frequency,it is necessary to study a driving circuit with the function of frequency positioning.The ultrasonic driving circuit with chopper power regulation and current signal closed-loop control function is studied based on STM32F103 MCU.The inductive compensation between the resonant network of the transducer and the driving circuit improves the active power of the ultrasonic driving circuit.According to the frequency impedance characteristics of the transducer,the working frequency is located by looking for the current peak point within certain range,and the working frequency is tracked and locked according to the current signal phase angle.The driving characteristics and temperature adaptability of ultrasonic drill are studied by experiments.In order to avoid the transducer aging in the test which can interfere with the results,the transducer was artificially aged by high temperature treatment and continuous operation before the test.The influence of preload on driving performance of ceramic stack was studied.An automatic preload loading platform based on x PC Target Real-time operating environment was built to control the tightening force.The positive pressure was detected by CLP piezoelectric washer of HBM.The relationship between impedance,driving characteristics and preload was obtained by impedance analyzer.The high/low temperature performance of the transducer and the ultrasonic drill is studied.The transducer and the ultrasonic drill are tested in the high/low temperature test chamber,and the relationship between driving characteristics,drilling speed and temperature is obtained.