Ultrasonic Standing Wave Levitation And Research On Containerless Processing

This paper designed and manufactured ultrasonic standing wave levitation devicebased on deep analyses of piezoelectric transducer and ultrasonic standing wave field.Several samples are levitated in the levitation device, upon which lead-tin welding wire isheated by a laser beam when it is suspended in standing wave field. Experimentalequipment of combination of standing wave levitation device and electromagnetic levitationsetup is structured, on the basis of which the molten metal melt by electromagneticlevitation without any contact is cooled to solid levitated by ultrasonic standing wave.The development of acoustic levitation is briefly stated and its research status isintroduced. Illustrate the principle and apply of electromagnetic levitation. Then present theproblems of electromagnetic levitation when the molten is cooled. To this question, thispaper puts forward a method that the molten contactlessly processed by electromagneticlevitation is supported by acoustic force and cooled to solid in the ultrasonic standing wavefield.Piezoelectric effect, equation and some performance parameter of piezoelectricceramics are specified, which are groundwork for transducer designing. Then analyse waveequation and it can help us know standing wave field. Moreover, derive standing wavelevitating force formula from which we know the force is changing as sine equation with zdirection. The radiation force, which can predict stable levitated position, is relative toamplitude, acoustic pressure and density of medium.The theories of piezoelectric transducer are discussed and PZT-8is chosen aspiezoelectric material. Also select materials for front and band cover plates respectively.Afterwards, the transducer with two amplitude transformers is designed. In order to increaseradiation areas, enlarge the bottom of the amplitude transformer, for which model analysis isdone. As a result, actual frequency is lower3.35%than design and that it meets requirement.Moreover In model analysis, there get displacement changing chart and displacement vectorchart, from which we can see that the velocity of the radiation part is the max and the vastmajority of energy is radiated out from the radiation part.The model that the surfaces of radiation and reflection are sphere is optimizated withANSYS software. Draw the model and get the acoustic pressure with harmonic analysis.Compared the acoustic pressure of transducer models with different sphere radius, we canget the max acoustic pressure with one sphere radius and this sphere radius is perfect.Relative time-average potential profile presented with ANSYS and Matlab software, fromwhich the stable levitated position and restoring force can be predicted. With the optimization of Chapter Four, standing wave levitation device is structured.Radiation force is tested by electronic precision scale and the relationship of radiation forceand the diatance of radiation and reflection is described. Then particles of different materialsare experimented to levitate in different distance of radiation and reflection, which aresimilar to the prediction of analysis. And disparate node has different levitation ability.Moreover, lead-tin welding wire is heated by laser beam when it is suspended in standingwave field. Also, high frequency heating inductor is manufactured and steel ball of diameter5mm can be levitated steadily in electromagnetic field. Finally, appliance combined byultrasonic standing wave levitation device and electromagnetic levitation setup is built, withwhich steel ball is heated and cooled without any contact. It is feasible that the fusion meltby electromagnetic levitation can be cooled to solid by ultrasonic standing wave levitation.Summarize what we have researched and present conclusions with experiment results.Put forward advices and opinions for the problems of the coupled device, which pave theway for further research.