As an important part of the bearing, the cage plays the role of guiding and separating the rolling elements. The guiding function of the cage actually refers to the correction of the running of the rolling elements. This correction is achieved through collisions between the cage and surrounding components.
Generally, there are three guiding methods for bearing cages: rolling body guiding, inner ring guiding, and outer ring guiding.
Roller guide:
The standard structure of the general design is rolling element guidance, such as short cylindrical roller bearings, which use rolling element guidance, and 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 speed, The rotation is unstable, so rolling element guidance is suitable for medium speed and medium load, such as gearbox bearings, etc.
Roller-element-guided bearing cages are located in the middle of the rolling elements. There is no contact and collision between the cage and the inner and outer rings of the bearing, and the collision between the cage and the rollers corrects the movement of the rollers, and at the same time separates the rollers at a certain equidistant position.
Outer guide:
The outer ring is generally stationary, and the outer ring is guided to facilitate the lubricating oil to enter the guide surface and the raceway. The high-speed gearbox is lubricated by oil mist, and the oil will be squeezed out by the guidance of the rotating inner ring. 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. Taking cylindrical roller bearings as an example, it only bears a fixed value of axial load. When rotating, the speed of each rolling element does not change much. The rotation of the cage Nor is it unbalanced.
Inner Circle Guidance:
The inner ring is generally a rotating ring, which 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 friction of the oil film gives the cage a drag force in the inner ring of the non-load area, thereby increasing the additional driving torque of the cage to the rolling elements, and can be used. prevent slipping.
The bearing cage guided by the inner ring is located near the inner ring of the rolling element. When the bearing is running, the cage may collide with the inner ring of the bearing, thereby correcting the position of the cage.
The three cage guiding methods may appear in different types of bearings, among which there are performance reasons, and there are also reasons for the design and manufacture of the bearing itself. Engineers can choose according to their needs. But sometimes engineers have no choice. However, 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 guided by the three cages is mainly manifested in the speed performance difference under different lubrication conditions.
All three cage types are available for oil and grease lubrication.