What is the impact of cage clearance on rolling bearing wear

Rolling bearings are widely used, such as in basic functions, large mechanical equipment, aviation engines, etc. The clearance between the cage directly affects the lubrication, oil film, heat generation, noise, and stability of the cage of the rolling bearing. It plays a key role in the performance of the rolling bearing. If the clearance between the cage is not well controlled, it will not only cause instability of the bearing cage and rolling elements, but also rapidly increase the collision force and friction force of the guide bearing ring, ultimately leading to damage to the cage and even affecting the service life of the bearing.

What are the specific effects of retaining clearance on the wear of rolling bearings?

The factors that affect the normal use of rolling bearings mainly include whether the design of the clearance between the cage pocket and the guide clearance of the cage is reasonable. If the clearance between the guide holes is increased under the given conditions of the cage guide clearance, the stability of the cage will deteriorate, and the inner ring guide is more likely to make the cage unstable than the outer ring guide.

By studying the effect of different cage clearances on the wear of rolling bearings through cage clearances, research experiments were conducted to identify wear marks on cages, steel balls, etc. Comparing the wear of cages and steel balls under different guide clearances and pocket clearances, the following conclusions were drawn:

(1) The guide clearance and pocket clearance both affect the wear of the cage and steel ball, but the influence of the guide clearance on the wear of the cage is more significant than that of the pocket clearance.

(2) When the guide gap is small, the wear on the guide surface of the cage is severe. As the guide gap increases, the wear on the guide surface of the cage gradually decreases. At the same time, the guiding gap affects the wear of the cage pocket, and when the guiding gap design is unreasonable, it exacerbates the wear of the cage pocket.

(3) The wear degree of the guide surface and the pocket hole of the cage gradually decreases with the increase of the pocket hole gap.

What are the factors that affect the stability of the bearing cage?

(1) Axial load

The axial load of a bearing refers to the load formed in the axial direction of the bearing, which is commonly known as the force that pushes the inner ring of the bearing out of the outer ring.

When the bearing is running, the inner ring rotates while the outer ring remains stationary, with axial load as the independent variable. When the bearing speed remains constant, the stability of the cage gradually improves with the increase of axial load. This is because the increase in axial force restricts the sliding of the steel ball, reduces the collision frequency between the steel ball and the cage, and because the frictional force is small when the lubricating oil acts, the vortex acceleration changes little, making the cage relatively stable.

(2) Radial load

Radial load refers to the load acting perpendicular to the axis of the bearing.

Keeping other conditions constant, with radial load as the independent variable, when the inner ring speed and axial load of the bearing are constant, the stability of the bearing cage gradually decreases with the increase of radial load. This is because increasing the frequency of interaction between the radial load retaining frame and the outer sleeve ring will decrease, weakening the effect of the outer sleeve ring on the movement of the retaining frame and reducing its stability.

(3) Bearing speed

When the axial load and radial load of the bearing cage are constant, the stability of the cage gradually increases with the increase of bearing speed. This is because an increase in rotational speed will cause the retainer to be quickly pushed towards the outer sleeve guide surface during movement, resulting in an increase in the frequency of contact between the retainer and the outer sleeve guide surface; At higher rotational speeds, the geometric coupling between the ball and the cage is good, so the cage motion tends to be relatively stable.

(4) Gap ratio

Keeping other conditions constant, with the bearing clearance ratio as the independent variable, when the bearing load and inner ring speed are constant, the stability of the cage gradually decreases as the clearance ratio increases. This is because the increase in clearance ratio increases the collision between the ball and the bearing cage, and this force is asymmetric, resulting in a decrease in the stability of the bearing cage.

(5) External groove curvature coefficient

The curvature coefficient of the outer groove of the bearing is one of the important geometric parameters of the bearing, which has multiple effects on the bearing.

Keeping other conditions constant, with the external groove curvature coefficient as the independent variable, the stability of the retaining frame gradually increases and then decreases as the external groove curvature coefficient increases. This is because, under high-speed rotation of the bearing, the increase in the curvature coefficient of the outer groove will affect the formation of oil film between various components, resulting in significant differences in the instability of the cage.

(6) Inner groove curvature coefficient

The curvature coefficient of the inner groove of the bearing is also one of the important geometric parameters of the bearing.

Keeping other conditions constant, with the curvature coefficient of the inner groove as the independent variable, as the curvature coefficient of the inner groove increases, the stability of the cage first increases and then decreases. The reason is the same as the influence of the external groove curvature coefficient.