Study On Ultrasonic Focusing Internal Processing Method Of Metal Droplets Based On Acoustic Levitation

The 21 st century is an era of rapid development of new materials and micromachining technology,and a variety of new material processing methods have emerged.Among them,the processing of a new batch of intelligent materials based on internal processing has become the focus and difficulty of current research.Moreover,internal processing has been well applied and extensively studied in the processing of transparent materials in femtosecond lasers.However,modern micro-electromechanical systems(MEMS)and ferrous metal non-transparent materials are still processed using traditional micro-structured layer bonding or multiple material stacking manufacturing methods to achieve the internal structure of the material;In terms of internal processing,transparent materials are often used as the base material for processing,which is subject to greater limitations.In addition,in the medical field,high-intensity focused ultrasound processing(HIFU)processing has been applied to biological tissue materials,and its working principle is to use ultrasound focus positioning technology to directly penetrate the ultrasonic "knife" into the biological tissue,and accurately cut the lesions at a fixed point.organization.Due to the huge potential application value of MEMS and intelligent material processing technology,the core problem of this paper is derived.The acoustic suspension phase-controlled in-focus processing proposed in this paper is based on the direct processing of microstructures in non-transparent materials such as metals.Research methods.The full text of the research is as follows:The first chapter is the background meaning and the research status at home and abroad.Firstly,the background and significance of internal processing and the application value of internal processing are introduced.Then,the internal processing method in non-transparent material,that is,the process of processing transparent dielectric material in the femtosecond laser to produce continuous hollow microchannels is introduced.The field and value of processing technology application,explore the domestic and international research progress of practical application scenarios of metal processing.The second chapter is the theory of ultrasonic focusing and phased array ultrasonic focusing.In this chapter,we first introduce the theory of acoustic radiation force from the theory of ultrasonic standing wave field.According to the theory of ultrasonic phased array focusing,we analyze the size and size accuracy of focus point from phase-controlled delay precision and geometric dimensional accuracy.Simulated by COMSOL Multiphysics Analyze the model,explore the influence of the size of the focal spot on the processing performance,and establish a simulation experiment on the change of sound pressure at the focal point.The third chapter is the research on the acoustic cavity cavitation forming method of metal melt.Study and analyze the theory of acoustic focal point acoustic cavitation,establish the theoretical analysis of the acoustic cavitation threshold of different metal materials;study and analyze the relationship between the surface tension,viscosity and temperature of metal droplets on the formation of cavitation nucleus inside the droplet;The influence of the size of the cavitation nucleus on the cavitation threshold is derived.According to the internal cavitation nucleus theory of the droplet,the size variation model of the cavitation bubble inside the droplet is deduced;and the numerical simulation analysis of the cavitation bubble formation by ultrasonic focusing point is obtained.Simulation of the process of cavitation bubble growth and stable molding.The fourth chapter is the experimental study on the suspension processing of metal droplets.The experimental platform of ultrasonic standing wave suspension field and phase-controlled ultrasonic focusing integrated system is established.The ultrasonic needle focusing cavitation forming method and size control analysis are studied.The spherical state changes in the ultrasonic standing wave microgravity field are adopted.The high-speed camera(CCD)is adopted.The pattern of the change of the size of the cavitation bubble in the droplet was made;the study of the formation of cavitation bubble by ultrasonic needle was carried out with different materials.