| As elementary mechanical components, spiral bevel gears have been used to transmit torque and movement of intersected or crossed axes. Because of their advantages of large overlap coefficient, steady transmission, low noise, good bearing capacity, high transmitting ratio, etc., they have been extensively employed in vehicles, ships, aircrafts, spacecrafts, machine tools, construction machines, etc.The tooth contact pattern, transmission error curve, and load sharing between teeth are affecting transmission characteristics of spiral bevel gears, such as stability in driving, vibration, noise, dynamic stifness, and dynamic strength.Mesh characteristics of spiral bevel gears has always been an important research direction for domestic and foreign scholars, however, there are some inadequate aspects of existing research, such as optimization method, model of gears, position deviation analysis, load analysis, experiment verification, etc.Therefore, this thesis research, with the basis of space meshing theory, is aimed to develop a global optimization designed method of tooth contact pattern and transmission’error curve. Besides, the research considers the effect of the relative position deviation of gear drive, as well as establishes a theoretical and experimental investigation of loaded tooth contact characteristics of spiral bevel gears transmission system. The main parts in my thesis are discussed below.Firstly, anew set of fundamental equations for geometric relationships of hypo id gear’s pitch parameters are established. Based on these formulas, the novel calculation methods are established for pitch parameters of generating gears of the gear and the pinion.Secondly, the exact mathematics models of gear tooth surface, pinion tooth surface, and their assembly are set up, and then the three-dimensional and two-dimensional tooth contact regions and transmission error curve are obtained by the tooth contact analysis. Taking the semi-major axis l1, the orientation angle y, and the intersection point ordinate 8 as the optimization objectives, and the normal curvature Af1, the normal curvature Bf1, and the geodesic torsion Cf1 as the control parameters, and complex-constrain genetic algorithm as the solving method, a global optimization designed method of tooth contact characteristics is established.Thirdly, a mesh equation is acquired due to the effects of the mounting errors. By analyzing the influences of each kind of erros on contact characteristics, the pinion axial position error AH and the offset error ΔV are assessed as having higher sensitivity degree. A mathematical definition and description of the coaxiality deviations of the gear drive is presented. Then, a multi-tooth mesh equation is established due to the effects of the coaxiality deviations, and the influences of the coaxiality deviations based on muliti-tooth contact analysis (MTCA), and the correlation between the mounting errors and the coaxiality deviations is obtained, And then, the optimization of the gear axial deviation angle ψ20 and the pinion axial deviation angle ψ10 is discussed.Fourthly, the exact mathematics models of gear root fillet surface and pinion root fillet surface are set up. Then, a finite element analysis model of spiral bevel gears transmission system is acquired which is appropriate for loaded tooth contact characteristics analysis under quasi-static condition. And then, the variation of contact stresses, bending stresses, and transmission error with loading levels are investigated.Finally, a spiral bevel gears transmission performance test system for wide range-working condition is developed. The experimental principles of tooth contact pattern test and bending stress test are presented. By comparing the test and simulation results, a good identity of results has been reached. |
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