The installation of angular contact ball bearing is more complex than that of deep groove ball bearings. They are mostly installed in pairs, and preloading is required. Good installation can greatly improve the working accuracy and bearing life of the host; Otherwise, not only the accuracy can not meet the requirements, but also the service life will be affected.
The installation forms of angular contact ball bearings include back-to-back, face-to-face and series arrangement. Angular Contact Ball Bearing When installing back-to-back (the wide end faces of the two bearings are opposite), the contact angle line of the bearing diffuses along the rotation axis, which can increase its radial and axial support angle rigidity and deformation resistance;
face to face (the narrow end faces of the two bearings are opposite) during installation, the contact angle line of the bearing converges towards the rotation axis, and the ground bearing angle rigidity is small. Because the inner ring of the bearing extends out of the outer ring, Angular Contact Ball Bearing when the outer rings of the two bearings are pressed together, the original clearance of the outer ring is eliminated, which can increase the preload of the bearing;
arranged in series (the wide end faces of the two bearings are in the same direction) during installation, the contact angle lines of the bearings are in the same direction and parallel, so that the two bearings can share the working load in the same direction. However, Angular Contact Ball Bearing when using this installation form, in order to ensure the axial stability of installation, two pairs of bearings arranged in series must be installed opposite at both ends of the shaft.
The preload can be obtained by grinding the end face of a ferrule in the bearing, Angular Contact Ball Bearing or placing two spacer rings with different thickness between the inner and outer rings of a pair of bearings to clamp the bearings together so that the steel ball is in close contact with the raceway.
The preload has a great impact on the service life of the bearing. According to relevant data, when the bearing is equipped with 0.012mm interference, the service life is reduced by 38%, and when there is 0.016mm interference, the service life is reduced by 50%; Angular Contact Ball Bearing When the bearing is equipped with a clearance of 0.004mm, the service life decreases significantly. When there is a clearance of 0.008mm, the service life decreases by 70%.
Therefore, it is very important to select the preload reasonably. Generally, small preload should be selected for high speed and large preload should be selected for low speed. At the same time, the preload shall be slightly greater than or equal to the axial working load.
When preload is selected, the calculation formula of small preload is as follows:
Radial load acting on bearing (n)
Axial load acting on bearing (n)
Included angle between the straight line passing through the contact point of steel ball and raceway and the straight line passing through the central plane of each steel ball (i.e. nominal contact angle):
Each bearing in a pair of bearings is calculated according to this formula. Where “+” is used for the bearing whose axial working load reduces the original pre common surplus value; “It is used for the bearing whose axial working load increases the original pre common surplus value. The small preload of two pairs of bearings is the larger of the two values obtained by the two bearings (according to the assembly experience, the preload of about 50N is generally taken).
Idling test. After the angular contact ball bearing passes the assembly inspection, the no-load operation test shall be conducted at the working speed for not less than 2h, and the temperature rise shall not exceed 15 ℃.