【作者】 贾平；

【导师】 陈观慈；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2012， 硕士

【摘要】 偏航、变桨轴承广泛使用大型四点接触球轴承,工作时承受轴向载荷、径向载荷及倾覆力矩的联合作用,具有工况载荷复杂、结构尺寸大、整体刚度低及工作转速低的特点,因此不能采用普通轴承的分析方法,而有必要针对其展开专门的研究与分析。本文采用数值分析法和有限元仿真法,研究偏航、变桨轴承的力学特性和结构参数的优化设计。首先,简要分析了偏航、变桨轴承的工作环境、载荷特征、结构形式等特点,详细阐述了以Hertz弹性接触理论为条件的偏航、变桨轴承接触变形和接触应力的非线性关系,推导了偏航、变桨轴承接触载荷和接触刚度的计算方法,并介绍了其静强度和疲劳强度的计算理论。其次,根据偏航、变桨轴承的使用工况条件、几何结构特点和变形协调关系,建立了考虑实际接触角、游隙、滚道沟曲率半径系数等因素的偏航、变桨轴承力学模型,并给出了采用牛顿—拉夫森迭代法求解力学模型的详细过程,并以某一型号偏航、变桨轴承为例,研究了不同工况条件下轴承的载荷分布规律及实际接触角的变化情况。接着,采用力学模型与经验公式两种方法计算偏航、变桨轴承的最大接触载荷并进行对比分析,初步验证了偏航、变桨轴承力学模型求解最大接触载荷及计算静强度的正确性。基于力学模型计算接触载荷的方法,实现了偏航、变桨轴承承载曲面和承载曲线的精确绘制。然后,分析了滚道排距、游隙、接触角、沟曲率半径等结构参数对轴承接触载荷、接触应力、实际接触角、承载滚动体个数等力学性能的影响规律,完成了以最小接触应力为目标函数的偏航、变桨轴承优化模型建立,并采用遗传算法进行求解,从而实现了偏航、变桨轴承结构参数的优化设计。最后,采用有限元分析法对比分析了无支撑结构和含支撑结构的偏航、变桨轴承两种模型的载荷分布及实际接触角变化规律,并通过与力学模型计算结果进行对比分析,进一步验证了偏航、变桨轴承力学模型求解载荷分布方法的正确性。更多还原

【Abstract】 The large-scale four-point contact ball bearing is usually used as the yaw and pitch bearing, which are mainly loaded with axial force, radial force and turnover moment, in a wind turbine. The traditional analysis method of rolling element bearing is not useful for the four-point contact ball bearing any more because the bearing is with different structure and low stiffness. So it is necessary to develop a new method for analyzing the mechanical performances of a four-point contact ball bearing. In this study, the mechanical performances analysis and structural optimization design of a yaw and pitch bearing are accomplished based on the new mathematical model developed in this paper. Then, the model and results are verified by the finite element method.First, the characteristics of yaw and pitch bearing, such as the working environment, load, structure, are analyzed. The nonlinear relationship between the Hertz contact stress and deformation of a rolling bearing is introduced. The calculation method for the contact load and contact stiffness of the yaw and pitch bearing is given. And calculation theories of the static and fatigue strengths are introduced.Second, according to the working conditions, geometry structure characteristics and deformation compatibility relation of yaw and pitch bearing, a mathematical model considering all kinds of factors, such as the actual contact angle, play and groove curvature coefficients, is developed. And the detail process to solve the mathematical model using the Newton-Raphson iterative method is given. Taking one kind of four-point contact ball bearing as an example, the load distribution and the actual contact angle are researched under the different working conditions.Then, the maximal contact forces calculated by the mathematical model are compared with those gotten by the empirical formula. The validity of the mathematical model for calculating the maximal contact force and static strength is verified. The load curve and surface are drawn exactly based on the mathematical model of four-point contact ball bearing.After that, the influence of the structure parameters (groove row distances, play, contact angle, groove curvature coefficients, diameter and number of roller, etc) on the mechanical performances (contact load, contact stress, actual contact angle, number of loaded rollers, etc) is analyzed. The optimization model of four-point contact ball bearing is established taking the minimum contact stress as an objective. The optimized values of key structural parameters are obtained by the optimization model adopting genetic algorithm.Finally, using the finite element method, load and actual contact angle distributions when the finite model is with support structure or no support structure are analyzed, respectively. The results gotten by the finite element method are compared with those calculated by the mathematical model developed in this paper. The validity of the mathematical model for analyzing the mechanical performances of a four-contact ball bearing is further verified.更多还原