| Wind turbine pitch bearing is one of the key components of wind power equipment, whose design and manufacturing is a bottleneck restricting to enhance the overall strength of major equipment industry in China. This paper selected a typical MW wind turbine pitch bearings-double row four point contact ball slewing bearing for the study. A pitch bearing mechanical model was established according to the Hertz elastic contact theory that consider radial force, axial force and overturning moment, and use Newton-Raphson method for numerical simulation of the model. The model is not only consider the three directions of the load, but also take into account a number of important design parameters, including radial clearance, groove radius of curvature coefficient, contact angle and double roller bearings spacing, etc. Based on the theory of elasticity, the equations about the bearing internal and outer ring bending deformation under the rolling contact load and the bearing load were detailed induced, and multiple non-linear transcendental equation group were solved to analyze four-point contact ball bearing related mechanical problems. The rigid ring model based on the theory of Hertz elastic contact and the flexible ring model based on the theory of elasticity were taken to numerical simulation, researching on the load distribution and distribution span of the four bearing contact diagonal, rolling element contact stress distribution, ring bending and torque distribution problems, etc.. Focusing on the research of some important design parameters impacting the carrying capacity of the bearing, including radial clearance, contact angle and groove radius of curvature coefficient, a detailed analysis was given, and the corresponding bearing design recommendations were presented. Work done by this paper provides an important theoretical basis for four-point contact ball slewing bearing, and even slewing bearing, and has some practical application value of engineering. |
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