| NFAL(near-field-acoustic-levitation) is one kinds of new supporting techniques, It will find widespread application prospect in the precision bearing fields. However, the levitating mechanism of thismethod hasn’t been very clear by now. In this thesis, the characteristis of the squeeze film excited byultrasonic actuaters is studied by the use of lubrication theory and experimental methods. The resultsshow that the squeeze film has considerable carrying capacity which is enogh to support small piecesof objects well.The system consists of piezoceramic actuaters, a slider with elastic hinges, a guide way and otherdevices. The properties of the system involve in four coupled fields including electric, structure, fluidand sound. These four coupled filed worked together to determine the load capacity and filmthickness.The equations of gas film pressure and the electromechanical coupling equation of theactuator are derived firstly, and then proper boundary conditions and initial conditions are selected tosolve the coupled govern equations by numerical methods. The mechanism of the gas squeeze-filmcould be explained by the result of simulation. What’s more, a digital controller is designed on thebasis of STC12C5410AD SCM and an incomplete differential PID control program is developed toset up the experimental system of the gas squeeze-film linear guide.The experimental study consists two major parts. The first part is to set up the linear guide systemand the second part is to test the capacity of the squeeze film and measure the film thickness. Thelinear guide is one kind of little or no friction equipment. Squeeze-film generated by thepiezoceramics and elastic hinges on the surface of the linear guide has considerable load capacity. Theexperiment is aim at the usage of squeeze-film levitation theory. Content of the experiment includesmaking the stacke of piezoceramics, selecting the digital controller, the displacement sensor and theamplifier as well as signal acquisition and processing. In the experiment, the amplitude, bearingcapacities and the height of the guide way are measured to verify the theoretical results. Further more,another new gas squeeze-film linear guide with ultrasonic amplitude actuators is made. By theexperiment, properties of this linear guide are studied and the result got from the theory analysis isproved to be right. And the results of this shows the new kind of guide way has little friction and largecapacity. |
