Bearing is an important component in contemporary machinery and equipment. Its main function is to support the mechanical rotating body, reduce the friction coefficient during its movement, and ensure its turning accuracy.
The inner and outer diameters of roller bearings of roller bearing manufacturers are manufactured according to standard tolerances. The tightness of the inner ring and shaft, outer ring and seat hole of the bearing can only be adjusted by controlling the tolerance of the journal and the tolerance of the seat hole. achieve. The cooperation between the bearing inner ring and the shaft adopts the base hole system, and the cooperation between the bearing outer ring and the seat hole adopts the base shaft system. To correctly select the fit, you must know the actual load conditions, operating temperature and other requirements of the bearing, but it is actually very difficult. Therefore, most cases are based on the use of lapping selection.
A transition fit is a fit that may have a gap or interference. At this time, the tolerance zone of the hole and the tolerance zone of the shaft overlap each other. Transition fit is mainly used for centering connection between hole and shaft. The larger limit size of the hole minus the smaller limit size of the shaft is the larger gap Xmax, which is the looser state of the hole and shaft fit; the smaller limit size of the hole is subtracted from the larger limit size of the shaft For a larger interference Ymax, it is a tighter state of hole and shaft fit.
According to the rotation of the load acting on the bearing relative to the ferrule, there are three types of loads on the bearing ferrule: local load, cyclic load, and swing load. Normally, cyclic load (rotary load) and swing load adopt tight fit. Except for special requirements on local load, tight fit is generally not suitable. When the bearing ring is subjected to a dynamic load and the load is heavy, the inner and outer rings should adopt an interference fit, but sometimes the outer ring can be loosened slightly, and it should be able to move axially in the bearing housing shell hole; when When the bearing ring bears the oscillating load and the load is light, a looser fit than a tight fit can be used.