Research On Ultrasonic Vibration Reducing Friction In Supporting Shafts

Bearing is the key component in the mechanical equipment. The function of bearing is to support the shaft and parts on the shaft and transfer movement and power. The rotating precision of shafting and performance of whole machine are affected by the bearing. With the development of modern manufacturing technology, the non-contacted and high rotating bearing is becoming a new study field. Piezoelectric ultrasonic technology with the characteristic of making use of ultrasonic vibration is developing rapidly in recent years. We have done a lot of research in ultrasonic vibration antifriction and bring forward the conception of ultrasonic vibration bearing for the first time on the basis of ultrasonic technology, machine vibrations and the science of friction. This broadens the application domain of ultrasonic vibration. The dissertation consists of five parts, the details as follows: (1) Introduction Along with the development of piezoelectricity material, ultrasonic technologies get more attention and develop to a new subject-ultrasonics. Generally, the ultrasonic vibration frequency is above 20KHz, the application of few sound wave which frequency under 20KHz is also including the research of ultrasonics. In this part, the antifriction and suspension technology in the case of ultrasonic vibration is expatiated. By analysis relative merits of the common bearing ,merits of ultrasonic vibration reducing friction in supporting shafts is given.And bolt fixing piezoelectric transducer is constructed as the basal body, the feasibility of bearing construction using ultrasonic vibration is analyzed, in the last of this part, on the base of former research ,the main contents studied in the paper is given. (2) Physics of ultrasonic vibration This part introduces the basic theories of piezoelectricity as well as piezoelectric phenomena,ceramic, equations and piezoelectric vibrator. (3) Design , make and test performance of piezoelectric transducer Based on the study of domestic and oversea scholars, the necessary condition of producing acoustic levitation is analyzed further and the relative theories of piezoelectricity,the ultrasonic and vibration are studied. It describes the mechanism of ultrasonic vibration for reducing friction and acoustic levitation and the feasibility of constructing acoustic levitation support of bearing by ultrasonic vibration. The performance of key components forming ultrasonic reducing friction acoustic Levitation, piezoelectric ceramic actuator, is analyzed largely in theory and test. Build the vibration equation of piezoelectric ceramic actuator and determine the size of piezoelectric ceramic actuator by boundary conditions. Design and fabricate the piezoelectric ceramic actuator and test the basic vibration parameters, such as the impedances of the actuator and resonance frequency. The value of prestressing force impacts on resonance frequency. Establish the matching method for the ultrasonic actuator that has the capability of acoustic levitation and reducing friction and testing research, including impedance matching method, circuit selection and relative test. The coupling between signal actuator and the piezoelectric ceramic actuator is improved and power losing is also reduced largely. (4) Analyze the vibration mode and resonance of the piezoelectric transducer Analyze three kinds of piezoelectric transducers to make the actuator vibration parameter for producing the optimal ultrasonic vibration for reducing friction and levitation. The piezoelectric transducer designed in the chapter two is predigested to two modes, one with prestressing force bolt and other without. Then frequency of design mode in chapter two is smaller than piezoelectric transducers of fact. It can be concluded that length of piezoelectric transducer front cover board bears on resonance frequency. Basing on mode analyse, I make harmonic analysis and take breadth-frequency curve of fan-out nodal to back cover board nodal. On resonance frequency, the displacement of fan-out nodal and back cover board nodal reach their peak. (5) The experimental research of ultrasonic vibration reducing friction in supporting shafts Design and facture ultrasonic vibration supporting shafts and conduct performance test analysis, This part consists of the levitation mechanism of ultrasonic bearing , comparing the reducing friction performance between ultrasonic bearing and others and the measurement for dynamic friction moment in the support section of ultrasonic radial bearing. I construe the reason of ultrasonic reducing friction. The strongpoint of ultrasonic vibration supporting shafts is...