Analysis On Performances Of Thin-walled Four Point-contact Ball Slewing Bearing

Thin-walled four point-contact ball slewing bearings are a type of large rollingbearings applied in the rotation parts of wind power generators, heavy engineeringmachinery and medical devices. Besides, it can bear a complex combine load with itsspecial raceway structure. Under heavy loads and a low speed, there is a big ringdeformation in thin-walled four-point contact ball slewing bearing, and this may havea poor effect on its performances as an increased frictional torque or a reduced servicelife. This systemic research on the performances of thin-walled four point-contact ballslewing bearing may provide a reference for its structural design and obtain a longerservice life. Based on the finite element analysis, the performances of slewing bearingwere analyzed with the combination of domestic and international research results.The influence of negative clearances on the negative four point-contact ballslewing bearing under no loads and also the influence of reducing wall thickness onthe radial ring deformation and the starting friction torque are conducted firstly andthen analyzed with a designed experiment. Under the combined loads, its axial loadcapacity, load distribution, stiffness and ring deformation are analyzed, respectively.And the influencing factors as different structural parameters, ball number, clearanceon the bearing performances are discussed with FEA models. On that basis, theinfluence of reducing wall-thickness and rib height on bearing performance is carriedout for the optimal design parameters of an oversize slewing bearing.Then, the starting friction torque for four point-contact ball slewing bearing isanalyzed in statics. A set of groove curvature radius coefficients is obtained for a closecontact stress between inner ring and out ring through the analysis. Meanwhile, theinfluence of negative clearances on the ring deformation is conducted. The dynamicfrictional characteristics are analyzed in dynamic module of ABAQUS, and the finiteelement model includes separators to separate balls. The relationships between thedynamic torque of certain contact pair and rotating speeds, internal clearances, ball number and groove curvature radius coefficient are obtained in sequence.Finally, the service life for four point-contact ball slewing bearing is analyzed.Through its special fatigue life theory, a static load capacity curve and a dynamic loadcapacity curve are drawn to select slewing bearings. Then the parameters as clearances,ball number, groove curvature radius coefficient and the initial contact angle arediscussed for a structural design. Other influencing factors as the connecting bolts andthe out ring teeth are analyzed then and the stress is checked with the fatigue strengthcriterion.