Mechanical Performance Analysis And Structural Optimization Design Of Slewing Bearing

The four point contact ball bearing is a kind of slewing bearing,which has large size and low rigidity.The rigidity of the bearing ring has a great influence on the distribution of the internal contact load,and then affects its mechanical performance and fatigue life.At present,the mechanical model of four point contact ball bearing is generally assumed to be a rigid body,neglecting the influence of its structural stiffness on the mechanical properties of the system,and the accuracy of the calculation is insufficient.Considering the elastic deformation of the flexible ring,the mechanical model of the bearing is established.The contact load distribution,the contact angle distribution,the maximum contact load,the maximum contact angle,the maximum contact stress,the bolt load distribution and the fatigue life of the double row four point contact ball bearing are analyzed.The project derives from the National Natural Science Foundation funded project "the basic research on the impact of bolt connection and supporting structure on the life of large turntable bearings(approval number: 51465025)".The main research contents are as follows:First,using the mathematical modeling method,the stiffness matrix of the double row four point contact ball bearing ring is introduced in order to consider the influence of the structural stiffness on the distribution of the internal contact load of the slewing bearing.In the modeling process,the curvature coefficient of the inner and outer ring groove,the ball diameter,the original contact angle,the ball nodal circle diameter,the number of ball,the clearance coefficient,the groove row distance,and so on,are considered.The nonlinear displacement and mechanical equilibrium equations of the four point contact ball bearing are established according to the structural characteristics and stress conditions of the bearing,and the Newton's method is used to solve the problem iteratively.Secondly,taking the yaw variable slurry bearing of wind turbine as an example,the finite element modeling was carried out by ANSYS software,the stiffness matrix was extracted,the contact load and contact angle distribution of the double row four point contact ball bearing were analyzed,and the contact load distribution between the flexible ring model and the finite element model of the two channel ball was found.The distribution trend of contact angle is basically the same.It is proved that the calculation result of flexible ring model is faster than that of finite element model,and it is more accurate than rigid ring model.The bearing capacity of turntable bearing is analyzed and calculated.Under the premise of flexible mechanical model,the influence of structural parameters on the bearing capacity of slewing bearing is analyzed.The analysis and calculation of the bolt connection of the slewing bearing are completed.Then,on the basis of the flexible mechanics model,according to the LundbergPalmgren theory and the calculation method of the fatigue life of the slewing bearing in the international standard,the fatigue life analysis of the rigid ring mechanics model of the double row four point contact ball bearing and the mechanical model of the flexible ring is carried out respectively,and the structural parameters are discussed for the slewing bearing.The influence of fatigue life is analyzed,and the corresponding improvement measures are put forward.Based on the analysis of the mechanical properties of the turntable bearings,the GUI interface of the bearing mechanics analysis software is worked out.Finally,according to the mechanical modeling and the calculation of the bearing capacity,the constraint conditions of the structure parameters of the double row four point contact ball bearing are analyzed.The optimization model of the bearing structure parameters is established by taking the maximum contact stress of the bearing as the objective function,and the genetic algorithm is used to solve it.The performance of the bearing is greatly improved.