One, cooperate the choice
The inner and outer diameters of the rolling NSK bearing are manufactured according to standard tolerances. The tightness of the inner ring and shaft, outer ring and seat hole of the bearing imported by NSK can only be achieved by controlling the tolerance of the journal and seat hole.NSK imported bearing inner ring and shaft matching with base hole system, NSK imported bearing outer ring and seat hole matching with machine shaft system.Rolling NSK imported bearings commonly used.The correct choice of fit, must know the actual load conditions, operating temperature and other requirements of NSK imported bearings, and in fact is very difficult.Accordingly, most circumstance is to use elaborate choice to cooperate.
Ii. Load properties
The rotation of load vector relative to ring should be considered first.According to the rotation of the synthetic radial load vector relative to the ring, the compound load borne by the ring can be divided into fixed load, rotating load and swinging load.
A. Fixed load
The resultant radial load acting on the ring is borne by the local area of the ring raceway and transmitted to the corresponding local area of the shaft or NSK inlet bearing block. Such load is called fixed load.Its characteristic is that the synthetic radial load vector is relatively static with the ring.Loose fit can be selected for the ring bearing directional load.
B. Rotating load
The synthetic radial load acting on the raceway rotates along the circumference of the raceway and is successively borne by various parts. Such load is called rotary load, and its characteristic is that the synthetic radial load vector rotates relative to the raceway.The ring bearing rotating load should be fitted tightly. Under special circumstances, such as very light load, or under the action of heavy load, the ring only occasionally rotates at low speed. When NSK inlet bearing is made of harder material and with a rougher surface, the ring bearing bearing rotating load can also be fitted loosely.
C. Swing load
Applied to ring in the synthesis of radial direction load, the load case, called oscillating load or directional load, its characteristic is the synthesis of radial load vector acting ring in the ring groove in a certain area of swing, on certain areas for the raceway, or apply to import NSK bearing load is impact load, vibration load, its direction, load values change often.The inner and outer rings of NSK inlet bearing bearing under swinging load shall be closely matched with the holes of bearing housing at state and NSK inlet.
Three, the load size
The excess between the ring and the shaft or housing depends on the size of the load, with a larger excess for heavier loads and a smaller excess for lighter loads.The equivalent radial load is usually divided into "light", "normal" and "heavy" loads.
Selection of tolerance zones for shafts and housing holes
Fifth, the surface roughness and shape and position tolerance
The roughness and shape and position tolerance of the matching surface directly affect the performance of the product, such as wear resistance, corrosion resistance and matching properties.For this reason, it is very important to rationally specify the shape and position tolerance of shaft and shell hole and put forward the roughness requirement of mating surface for stabilizing mating property and improving the joint strength of overwinning mating.