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.

采用淬硬轴承钢的滚动轴承的许用接触应力是根据经验确定的，而仅滚道表面淬火的回转轴承尚无其许用接触应力的确定值或计算公式。为确定滚子转盘轴承表面硬化滚道的许用接触应力，对负载滚子与表面硬化滚道之间的接触弹塑性特性进行有限元分析，得到不同滚子直径、滚子对应的接触塑性变形。获得了载荷和渗层深度。利用赫兹接触理论计算滚子载荷产生的接触应力。通过对模型输入参数与输出塑性变形之间的非线性回归分析，建立了接触塑性变形与滚子直径、接触应力、渗层深度之间的关系方程。进一步根据回归方程得到了表面硬化滚道许用接触应力的计算公式。利用所得公式计算的许用接触应力表明，表面硬化滚道的许用接触应力主要取决于硬化层深度。通过滚子与表面硬化试件之间的加载压缩试验，验证了所建立的表面硬化滚道许用接触应力计算方法的有效性。许用接触应力随滚子直径的增大而略有减小，随渗层深度的增大而显着增大。当渗层深度达到6 mm时，最大允许接触应力为3758 MPa。当渗层深度达到7 mm时，渗层硬化滚道的最大允许接触应力为3889 MPa。