Theoretical And Experimental Research On Transformer With Non-Resonance Structure In Ultrasonic Gear Honing

Gear is the most important component of the mechanical power transmission. It has the advantages of wide range power, high transmission efficiency, accurate drive ratio, long life and safety so as to irreplaceable and extensive use. The gear as the basic components of machinery products is the foundational industry in the national economy development.To raise bearing capacity of gears and reduce the size of transmission devices, hardened-tooth gears are widely used in many countries. However china's precision finishing technology of hardened-tooth gears is significantly behind the developed countries. It is a new attempt to introduce the ultrasonic vibration to traditional gear honing processing, the purpose is to use the advantages of the ultrasonic vibration cutting to overcome the traditional honing disadvantage, give full play to the advantage of gear honing in the precision finishing technology, and achieve the goal of gear machining at high quality, high efficient and low cost.The design of vibration system is one of the key technologies in ultrasonic gear honing, and also is the further study base. Just for this reason, the project proposed by our research team, named "design theory of transformer with non-resonance structure and its application in ultrasonic gear honing and shaving"(No.50975191) was supported by national natural science foundation in2009. The key problem of "design theory of transformer with non-resonance structure" is focused to be solved and innovative research is carried out in this paper, its purpose is to solve the resonance of vibration system composed of gear and horn, and to make vibration mode and frequency and amplitude of gear meet the ultrasonic machining requirements. The following contents are mainly researched in this paper:(1) The design of longitudinal vibration transformerFor small-diameter gear, its vibration mode of gear is one-dimensional longitudinal vibration driven by ultrasonic horn, its radial vibration and bending vibration can be neglected. The small diameter gear is simplified as a cylindrical rod, and then the system formed by the gear and fixing nut and transformer show the same features as compound ultrasonic horn. The longitudinal vibration transformer is designed using the design principle of the composite horn, and a more accurate calculation is obtained. In the last, the amplitude of longitudinal vibration transformer is also analyzed, and a new cascade horn is proposed to increases the amplitude of longitudinal vibration, it is suitable for the application of the large output horn.(2) Axisymmetric flexural vibration of gear and circular plate, annular plateGear axisymmetric flexural vibration is fundamental of design the flexural vibration transformer. Gear is simplified as a circular plate which diameter is equal to gear's pitch circle diameter, and then Mindlin theory of moderately-thick plate vibration is used in the calculation of the gear flexural vibration. The comparison between the calculated results with FEM analysis results show it is more reasonable and accurate to analyze the vibration of gear using Mindin theory than using thin plate theory. Based on Mindlin theory, respectively methods are proposed to calculate the vibration frequency of circular plates with variable thickness along the radial and circular plates with circumferencially distributed holes. Comparisons of calculated results with FEM results prove that this method is reasonably accurate.(3) The design of gear flexural vibration transformerGear flexural vibration transformer is the main vibration form of transformer with non-resonance structure in ultrasonic gear honing. Based on Mindlin theory, through in-depth analysis of vibration characteristics of the gear flexural vibration transformer, multiple computational model is proposed, and then the reasonably practicable design theories and methods of the flexural vibration transformer are identified binding experiments. Furthermore, amplitude distribution characters is analyzed and the measures to increase amplitude is raised. In some extend, the analysis of flexural vibration transformer with FEM is explored.(4) Flexural vibration transformer composed by half-wavelength hornTheories and experiments have shown that the length of nut will have an impact to the frequency of the transformer in flexural vibration amplitude transformer. The longer the fixed nut is, the lower frequency the transformer has, and on the contrary the amplitude transformer will have higher frequency. In addition, the adding of the fixed plate element to flexural vibration amplitude transformer will exert influence over the frequency of the transformer. Based on the results, we put forward a design idea of flexural vibration transformer composed by half-wavelength amplitude transformer. The amplitude transformer is designed as half wavelength and it adjusts the frequency by changing the size of the nut or fixed plate. Theoretically, a preliminary exploration is done on the transformer with this kind of structure.(5) The design of radial vibration transformerRadial vibration amplitude transformer is the third vibration form of the ultrasonic gear honing transformer with non-resonant Structure. The greater the aperture of gears is, the greater the diameter of horns, and the stronger the radial vibration of transformer. The gear's pure radial vibration is also a kind of axisymmetric vibration modes that can be used for compound ultrasonic machining of gears. Based on the longitudinal and radial coupled vibration theory, we present a design theory and mathematical model of radial vibration transformer and verify the accuracy of the design results using finite element analysis method. In addition, an analysis of frequency characteristics and amplitude characteristics of the radial vibration amplitude transformer is also conducted and the improved structure of it is proposed.The above theoretical and experimental studies could help shape a fairly complete design theoretical system of ultrasonic gear honing transformer with non-resonant structure, meets the requirements of the ultrasonic gear honing. These creative researches will have set up a basis for the further theoretical and experimental studies on ultrasonic gear honing in the future.