An Analysis Method of Carrying Capacity Accuracy of Three-Row Roller Slewing Bearing

Three-row roller slewing bearings are the core components of large-scale rotating equipment. It has a large structural size and is subjected to heavy loads, which requires extremely high carrying capacity. The effect of finite element mesh size on the carrying capacity accuracy of three-row roller slewing bearing is investigated. A local finite element model is established to analyze the contact area between the roller and the raceway, which is compared with the Hertz contact theory to verify the reasonable mesh size of the finite element model. The local spring finite element model is established, and the effect of the mesh size on the offset and the declination of the upper and lower raceway is investigated; The overall finite element model of the slewing bearing is established to analyze the effect of the mesh size and the nonlinear spring stiffness on the carrying capacity accuracy. The whole circle deformation of the ring and the load distribution is investigated to determine the reasonable mesh size. This article provides a method and idea for the verification of the three-row roller slewing bearing finite element model, which is beneficial to improve the calculation accuracy of the bearing capacity of the three-row roller slewing bearing.

Influence of finite element mesh size on the carrying capacity analysis of single-row ball slewing bearing

Slewing bearings are widely used in industry to provide rotary support and carry heavy load. The load-carrying capacity is one of the most important features of a slewing bearing, and needs to be calculated cautiously. This paper investigates the effect of mesh size on the finite element (FE) analysis of the carrying capacity of slewing bearings. A local finite element contact model of the slewing bearing is firstly established, and verified using Hertz contact theory. The optimal mesh size of finite element model under specified loads is determined by analyzing the maximum contact stress and the contact area. The overall FE model of the slewing bearing is established and strain tests were performed to verify the FE results. The effect of mesh size on the carrying capacity of the slewing bearing is investigated by analyzing the maximum contact load, deformation, and load distribution. This study of finite element mesh size verification provides an important guidance for the accuracy and efficiency of carrying capacity of slewing bearings.

Mechanical model and contact properties of double row slewing ball bearing for wind turbine

In this paper, the mechanical models of large-scale double row slewing ball bearing considering combined loading conditions were presented based on the rigid rings and flexible rings, respectively. And the contact properties between the ball and raceway were studied. These workflows for the calculation were described and programmed by MATLAB. The load distributions of slewing bearing for 2MW wind turbine were presented. The results indicated that the load distribution with the ideal stiff assumption differs from the load distribution determined by taking into account the flexibility of rings. With flexible rings, the magnitude of contact force is less than that of the rigid rings. The influences of the initial contact angle, the coefficient of groove curvature radius, the clearance on maximum contact force were analyzed and some suggestions have been discussed. These parameters have significant effects on the load distribution. The maximum contact force decreases with coefficient of groove curvature radius decrease. A three dimensional finite element model of the slewing bearing is established and analyzed. The simulated results are compared with that of mechanical models.

Determination of permissible contact stress of case hardened raceway of roller slewing bearing

The permissible contact stress for the rolling bearing made of the through hardened bearing steel has been established based on experience, while there is no definite value or calculating formula of the permissible contact stress for the slewing bearings which are hardened only on the raceway surface yet. To determine the permissible contact stress of the case hardened raceway of roller slewing bearing, finite element analysis for the contact elasto-plastic characteristics between the loaded roller and the case hardened raceway was performed, and the contact plastic deformations corresponding to different roller diameter, roller load, and case depth were obtained. The contact stress produced by the roller load was calculated by using Hertz contact theory. Based on the nonlinear regression analysis between the input parameters and the output plastic deformations of the model, the relation equation between the contact plastic deformation and the roller diameter, contact stress, case depth was established. The formula for calculating the permissible contact stress of the case hardened raceway was obtained according to the regression equation further. The permissible contact stresses calculated by using the obtained formula show that the permissible contact stress of the case hardened raceway depends mainly on the case depth. Loaded compression tests between the roller and the case hardened specimens were conducted to verify the validity of the established calculation method for the permissible contact stress of the case hardened raceway. Permissible contact stress decreases slightly with the increase of the roller diameter and increases with the increase of the case depth significantly. As the case depth reaches 6 mm, the maximum permissible contact stress is 3758 MPa. As the case depth reaches 7 mm, the maximum permissible contact stress of the case hardened raceway is 3889 MPa.