Installation Of Angular Contact Ball Bearings

The installation of angular contact ball bearings is more complicated than that of deep groove ball bearings. They are mostly installed in pairs and require preloading. Proper installation can greatly improve the working accuracy and bearing life of the host; otherwise, not only the accuracy will not meet the requirements, but the lifespan will also be affected.
Installation form
There are three installation forms of angular contact ball bearings: back-to-back, face-to-face and series arrangement. When installed back-to-back (the wide end faces of the two bearings face each other), the contact angle of the bearings spreads along the direction of the rotation axis, which can increase its radial and axial support angle rigidity and maximize its resistance to deformation; face-to-face (the narrow end faces of the two bearings face each other) When installed, the contact angle line of the bearing converges toward the direction of the rotation axis, and its ground bearing angle rigidity is small. Since the inner ring of the bearing extends out of the outer ring, when the outer rings of the two bearings are pressed together, the original gap of the outer rings is eliminated, which can increase the preload of the bearing; when installed in series (the wide end surfaces of the two bearings are in one direction) , the contact angle lines of the bearings are in the same direction and parallel, allowing the two bearings to share the working load in the same direction. However, when using this installation form, in order to ensure the axial stability of the installation, two pairs of bearings arranged in series must be installed opposite each other at both ends of the shaft.
Obtaining preload
The preload can be preloaded by grinding the end face of a ring in the bearing, or by placing two spacers of different thicknesses between the inner and outer rings of a pair of bearings to clamp the bearings together so that the steel balls are in contact with the raceway. Obtained from close contact.
The size of the preload has a great influence on the service life of the bearing. According to relevant information, when the bearing is assembled with an interference of 0.012mm, the service life is reduced by 38%; when the interference is 0.016mm, the service life is reduced by 50%; When the bearing is assembled with a 0.004mm gap, the service life is significantly reduced, and when there is a 0.008mm gap, the service life is reduced by 70%. Therefore, it is very important to make a reasonable selection of the size of the preload. Generally, a small preload should be used for high speeds, and a large preload should be used for low speeds. At the same time, the preload should be slightly greater than or equal to the axial working load.
Calculation of preload
When selecting preload, the minimum preload calculation formula is as follows:
Aomin=1.58tgaR±0.5A (N)
Radial load acting on the bearing (N)
Axial load acting on the bearing (N)
The angle between the straight line passing through the contact point of the steel ball and the raceway and the straight line passing through the center plane of each steel ball (ie, the nominal contact angle):
7000C a=15°
7000AC a=25°
7000B a=40°
Each bearing in a pair of bearings is calculated according to this formula. The “+” sign in the formula is used for the bearing where the axial working load reduces the original pre-compensation value; the “+” sign is used for the bearing where the axial working load increases the original pre-compensation value. Two in pairs The minimum preload of the bearing is selected from the maximum of the two values obtained for the two bearings (according to assembly experience, a preload of about 50N is generally taken).
Adjustment of preload
Dry running test. After the angular contact ball bearing passes the assembly inspection, it must be subjected to a dry running test at the working speed for not less than 2 hours, and the temperature rise should not exceed 15°C.