As an important part of the bearing, the cage plays a role in guiding and separating the rolling elements. The guiding effect of the cage actually refers to the correction of the rolling element operation. This correction is achieved by the collision between the cage and the surrounding parts.
There are three general guidance methods for bearing cages: rolling element guidance, inner ring guidance, and outer ring guidance
1.Rolling element guidance
The standard structure of general design is rolling element guidance, such as short cylindrical roller bearings, which adopt rolling element guidance. The cage does not contact the rib surfaces of the inner and outer rings. The cage can be used in general, but when the rolling element speed increases at high speeds, The rotation is unstable, so the rolling element guidance is suitable for medium speed and medium load, such as gearbox bearings.
The bearing cage guided by the rolling elements is located in the middle of the rolling elements. The cage and the inner and outer rings of the bearing do not contact or collide. The collision between the cage and the rollers corrects the roller movement, and at the same time separates the rollers at a certain equidistant position.
2.Outer ring guidance
The outer ring is generally stationary, and the outer ring guide facilitates the lubricating oil to enter the guide surface and raceway. The high-speed gearbox is lubricated by oil mist, and the rotating inner ring guides the oil out. The bearing cage guided by the outer ring is located on the side of the rolling element close to the outer ring. When the bearing is running, the bearing cage may collide with the outer ring of the bearing to correct the position of the cage.
The outer ring guide is generally used in the case of high speed and stable load. Take cylindrical roller bearing as an example. It only bears a fixed value of axial load. When rotating, the speed of each rolling element does not change much, and the rotation of the cage Not unbalanced.
3.Inner ring guidance
The inner ring is generally a rotating ferrule, and provides rolling elements to drag torque when rotating. If the bearing load is unstable or the load is light, slippage will occur.
While the cage adopts internal guidance, an oil film is formed on the guide surface of the cage. Due to the friction of the oil film, the drag force is applied to the cage in the non-load zone, thereby increasing the additional driving torque of the cage to the rolling elements. Prevent slippage.
The bearing cage guided by the inner ring is located where the rolling elements are close to the inner ring. When the bearing is running, the cage may collide with the inner ring of the bearing to correct the position of the cage.
The three cage guidance methods may appear in different types of bearings. Among them, there are performance reasons, as well as the design and manufacturing of the bearing itself. Engineers can choose according to their needs. But sometimes engineers have no choice. In any case, the different performance of different cage guidance methods should be noted.
The difference between the three cages is mainly manifested in: the performance difference of the bearings of the three cage guidance methods is mainly manifested in the difference in speed performance under different lubrication conditions.
Bearings of the three cage types can be used for oil lubrication and grease lubrication.
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