Structure Design And Experimental Study On Ultrasonic Levitation Bearing Which Support With Concave Cylindrical Surface

This paper is based on the project of"the National Natural Science Foundation research of ultrasonic technology for shaft levitation in high-speed flywheel energy storage system", The project propose using ultrasonic vibration bearing technology for shaft levitation in the flywheel energy storage system, to levitate the flywheel and shaft through High-frequency vibration, to reduce friction, achieve greater speed, lower energy consumption, improve the flywheel energy storage efficiency. Based on the deeply analysis on the theory of ultrasonic levitation and ultrasonic antifriction, this paper designed and built the testing system of ultrasonic vibration bearing, which support the shaft used the ultrasonic vibration of the concave cylindrical face. The test of this system showed that the high-speed shaft can be frictionless levitated and by the ultrasonic bearing with the ultrasonic vibration concave cylindrical face.The paper is composed of five chapters; the following is the main contentChapter one: IntroductionThe development of bearing was introduced in briefly, cited the types of bearings which emerge recently; Introduced of the characters and the applications of the ultrasound wave, based on that, put an emphasis on the ultrasonic levitation and antifriction technology, summarized the domestic and international research of ultrasonic levitation and antifriction technology, then raised the issue of this paper: research on levitation and antifriction technology of the concave cylindrical face supported ultrasonic bearing and pointed out the main work which this paper will finish.Chapter two: Piezoelectric transducer design and experimental which was used to ultrasonic levitation bearing with concave cylindrical faceFollowing the basic theory of piezoelectricity, introduced the piezoelectric material, principle, types and performance of the piezoelectric transducer. On that basics, selection and design the materials, structure and vibration mode In this chapter. Basing on the simplified model of the piezoelectric transducer and according to the knowledge of Mechanical vibrations and Acoustic designed the key size of the transducer. Analysis the mode of the transducer in HYPERWORKS, and modified the key size of the piezoelectric transducers according the analysis result. The vibration performance on the points of the concave cylindrical surface of the transducer has been analyses by the harmonic response analysis of the radial support transducer in HYPERWORKS. Produced the transducer with key size in amendment. The resonant frequency and the amplitude of the transducers has been tested, and the vibration performance on the point of the concave cylindrical surface of the transducer has been tested, the result of the test suggested that the amplitude of each point on the concave cylindrical surface are equal.Chapter three: Theoretical and experimental study on ultrasonic levitation and antifriction characteristics of the concave cylindrical surfaceStarting with analyzing the effect of the ultrasonic vibration surface to the object, this chapter used computational acoustics analyzed the levitation force produced by the ultrasonic vibrate of the concave cylindrical surface, and processed some relative experiments. The result of the theoretical and experimental analysis suggested that the vibrating concave cylindrical surface can realize the levitation of the shaft, and the value of the levitation force is related to the vibration parameters and geometric parameters of the surface. In the same field stimulation conditions, the levitation gaps will be reduced as the increase of the shaft weight, and the reduction of the levitation gap is nonlinear. From the result of the experiment also can draw the conclusion that the with the levitation gap is very stable which is beneficial to levitation of the high-speed shaft. . Using hertz theory of Tribology built up the contact model of the concave cylindrical surface and the shaft and analyzed antifriction characteristics. Lastly, draw the conclusion that the bigger the amplitude, the bigger stiffness the contact pair, the more obvious the friction reducing effect.Chapter four: Design and experiment on the ultrasonic bearing with concave cylindrical surface.According to the actual working status of general bearing, in this chapter realized the high-speed shaft levitated by a special ultrasonic bearing structure, which using ultrasonic vibration concave cylindrical surface to support the shaft in the radial direction and using ultrasonic vibration plane surface to locate the shaft in the axial direction. Analyzed the force of the concave cylindrical surface act to the shaft on the basis of the finite element analysis results. After finished the design and manufacture of the ultrasonic bearing processed some tests. The tests showed that the ultrasonic bearing with concave cylindrical surface have ability to levitated high-speed shaft, which can reach up to 9500rpm. Compare with general bearing, the ultrasonic bearing demonstrate more obvious antifriction performance, the friction coefficient can be reduced to 0.0002~0.0003, witch equivalent to 1/5~1/10 of the friction coefficient of the general ball bearing.Chapter five: Conclusions and OutlookSummarized the research work of this paper, combining experimental results, presented the conclusion of the study of this paper. Lastly, aiming at the existing problems of this paper gave several opinions, which build up a base for future study no ultrasonic levitation bearing...