Study on the Capacity Analysis Method of Slewing Bearing
With the rapid development of the national economy, lifting, digging and other equipments are becoming lighter, the host structural become more and more compact, but their load capacity are increasing. As the important component in these equipments, slewing bearing has been paid more attention and its design becomes more and more strict. Recently, there contact stress meet the requirement, but some slewing bearings produce stuck, raceway fracturing, depression and other non-normal failure phenomenon. Partly due to the manufacturing quality, and there are another two important reasons:the lack of the stiffness of slewing bearing and the failure of high-duty bolted joints.Currently, the stiffness analysis of slewing bearing only focuses on the contact deformation between roller and raceway but ignores the deformation of ring, resulting in the calculation of total deformation is not as accurate. There are various non-linearities on the high-duty bolted joints of slewing bearing, such as geometrical non-linearity, boundary non-linearity and material non-linearity. Because of the above difficulties, the designers usually calculate it based on a certain simplification and idealize the bolted joint.In response to above problems, this paper fully research the structural features and the load situation of slewing bearing, by exploring of the stiffness analysis method and the high-duty bolted joints analysis method to make up deficiencies on the current capacity analysis method of slewing bearing. The main research and study of this paper are as follows:(1) Through analyzing the working principle of slewing bearing, structural features and the load situation, we study the current problems in the capacity analysis method, determining the necessity and feasibility of stiffness calculation method and high-duty bolted joint calculation method analysis of slewing bearing.(2) Taking crossed-roller slewing bearing as the study object, we analyze its working principle. Calculating the raceway pressure by using pressure superposition method and analyze the unit pressure on the rolling raceway subjected to the vertical load as well as subjected to the overturning moment.(3) Based on the Hertz contact theory and ANSYS software, we establish the FEA model which can calculate the relative displacement between the outer ring and the inner ring as well as consider the ring deformation. Analyze the relationship between the vertical load and deformation, the relationship between the overturning moment and deformation as well as displacement distribution on the raceway under overturning moment; and then we contrast the calculation and existing result, explaining the accuracy of the finite element method.(4) By reasonable assumption and considering the friction, contact, preload intensity, load eccentricity, bolt bending, and other nonlinearities, we establish three-dimensional FEA model which can reflect the high duty bolted joint and then get the bolt behavior and develop the finite element method for static strength, fatigue strength and related stresses of bolt. Through the analysis of the practical examples, we contrast the finite method and the results of analytical method and explain the accuracy of the finite element method.(5) By the finite element method, we do numerous numerical simulation experiments to study the effects and its degree of preload intensity, support plate thickness, tube height on the bolt behavior. These results will guide designer to complete the slewing bearing design effectively and accurately, and the idea of these research ideas can be well applied to bolted joints study in other devices.
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