Bearing pre-tightening methods, and the influence of speed - bearing knowledge

Bearing axial pre-tightening force method has two kind of prestressing force is a kind of constant pressure, the other is a positioning pre-tightening force. Under the constant pressure preload, bearing radial stiffness increased slightly, the increase of rotational speed and the axial stiffness and Angle quickly down. Positioning under the preloaded, bearing the radial, axial and Angle stiffness with the increase of the rotational speed and increased rapidly, but the increase of the axial stiffness and Angle is more gentle. 1, the influence of the pre-tightening load with the increase of pre-tightening load, radial, bearing. Axial stiffness and Angle increases slightly, but the impact is very small. Compared with positioning preloaded, the effect is significant for constant pressure preload. This is the mountain in the pre-tightening load increase make inside and outside the circle contact Angle increases, but also make contact load increases, so that the radial, axial and Angle stiffness is increased. But the pre-tightening load caused by the contact load and contact Angle change, compared with the displacement caused by the change speed and parts is small, therefore, the influence on bearing stiffness is limited. This is Orient the change of the preload is less than the cause of the constant pressure preload. 2, the influence of channel curvature radius, with the increase of channel curvature radius on inner and outer radial, axial stiffness and Angle is less, but the effect is very small, only positioning under the preloaded stiffness changes a little some obviously, this is because the channel curvature radius increases make contact deformation increases. Therefore, generally choose the channel when the radius of curvature can not consider its effect on stiffness. 3, count, under the influence of the positioning preloaded ball increase in the number of radial, axial and Angle stiffness increased slightly. Count increase increase stiffness, but the same pre-tightening load, increase the count will reduce the contact load, although they are the result of interaction of can increase the stiffness of bearing, but less. Under constant pressure preload, count increased the radial stiffness were increased significantly, and when the speed increased to a certain value of axial and Angle stiffness decreases, but the change is very small. , this is due to the constant pressure preload count increases while the inner ring contact load is reduced, but at the same time make the inner ring of contact Angle decreases, and they work together to make bearing radial stiffness significantly increased, and the axial stiffness and Angle decreases slightly. Therefore, the ball when the increase in the number, should increase pre-tightening load, only when the contact load at the same time, increase the count can increase the bearing stiffness. 4, ball diameter of absence made positioning preloaded, ball diameter, radial, axial and angular rigidity increases slightly. Increases the size of the ball the ball size for the centrifugal force increases, outer contact Angle decreases, and inner ring contact Angle increases, but at the same time make contact on inner and outer load increases, they are the result of joint action make bearing stiffness increases. By a change in positioning preloaded under centrifugal force have less effect on the contact load, so the ball diameter changes on the influence of the stiffness is very small. Under constant pressure preload, the ball diameter radial stiffness increases, the axial Angle stiffness and reduce, but less affected. This is due to increase the ball the ball size for the increase of the centrifugal force, both inside and outside circle contact Angle decreased, the outer contact load increase, while the inner ring contact load basically remain unchanged, so the radial stiffness increase, and the axial stiffness and Angle slightly reduced. Therefore, reducing not only improve the speed performance, the ball size and will not reduce the stiffness performance. This also ball from theory of divination proves that the path is currently one of the development trend of the main shaft bearing. 5, the initial contact Angle of absence made positioning preloaded, the initial contact Angle increases significantly reduce radial stiffness, axial stiffness and Angle increased significantly. This is because the initial contact Angle increases, the radial component of the contact stiffness is reduced, the axial component increases, at the same time, same pre-tightening load under contact load. Under the constant pressure preload, the initial contact Angle increases the radial stiffness significantly decreased; Low speed, axial stiffness and Angle increases, high speed, the basic no change. This is due to the constant pressure preload, the inner and outer ring allows the axial displacement, in order to maintain the balance of the force, outer contact Angle almost close to zero, the initial contact Angle size had little influence upon foreign circle contact Angle. Also, the initial contact Angle increases, the same pre-tightening load under contact load. Therefore, positioning under the preloaded increase initial contact Angle can improve the bearing axial stiffness and Angle, and increase the initial contact Angle under constant pressure preload not only failed to improve the axial stiffness and Angle, reduce the radial stiffness.