Because the spherical sliding contact area of the joint bearing is large and the inclination angle is large, and because most of the joint bearings adopt special machining methods, The rolling bearing is mainly composed of an inner ring with an outer spherical surface and an outer ring with an inner spherical surface. Spherical bearings are usually used for low speed swing motion, that is, angular motion.Because the sliding surface is spherical, it can also perform oblique motion in a certain angle, that is, self alignment motion. It still works. Calculation method: The spherical sliding bearing has two mating spheres.This connection is called coordination.The calculation method of the mechanical properties of spherical plain bearings plays an important role in the structural design and wear analysis of spherical sliding bearings.The calculation of the contact pressure on the surface is a very complicated problem.The existing Hertz model can not be used to calculate the contact pressure distribution of spherical coordinates, because it is limited to elastic half space body. At present, there is a unified spherical contact model, that is, the Fang model, which can solve the problem of small spherical contact pressure distribution.This model is suitable for incompatible contact and coordinated contact. However, the contact area of the joint bearing is not a complete sphere, so the calculated value of the contact pressure distribution should be further calculated on the basis of the complete spherical contact model. In addition, the free boundary effect will also occur during the use of the joint bearing, which will have a certain impact on the application of the joint bearing.The free boundary effect produces concentrated contact pressure and large pressure gradient at the outer ring of the joint bearing.