Why are angular contact bearings used in pairs?

Angular bearings are not necessarily used in pairs. Angular bearing, also known as centripetal thrust bearing, is structured as the bearing roller is at a certain angle with the axis, which produces both centripetal force and axial force, which can also play the role of centering and bearing. It is equivalent to installing both a flat bearing and an ordinary cylindrical bearing.

Therefore, angle bearings are used on some rotating shafts that need to carry a certain axial force. But if the axial force is in a single direction, it is not necessarily used in pairs. All it takes is an angular bearing that can compete with the axial force.

Angular bearings are generally used in pairs on shafts with high accuracy and force in both directions. For example, the spindle of the CNC machine tool also has the screw rod of the CNC servo axis. Because the movement of these axes is complex, there are often forward and reverse rotations, and it is required that the axes are reversed correspondingly quickly, and there is no axial movement.

So be sure to use them in pairs. to prevent the shaft from being moved by force in both directions. Achieve the purpose of stabilizing the movement.

Pairwise use is to increase or balance the bearing force, according to the direction of the axial force, you can choose DB back-to-back installation, DF face-to-face installation, DT series installation, for the machine tool spindle, commonly used to triple installation, quadruple installation, and even five installation, normally, the axial load is bidirectional, rarely pure one-way axial load, so the angular contact ball bearings are installed in pairs. On the one hand, the paired installation can increase the radial load capacity, and on the other hand, it can also provide a more targeted bearing load capacity and increase the toughness of the spindle.

Reason: Single row angular contact ball bearings can only withstand axial loads in one direction, and when subjected to radial loads, additional axial forces will be induced. And only the axial displacement of the shaft or housing in one direction can be limited.

If it is installed in pairs, the outer rings of a pair of bearings are opposite, i.e., the wide end faces the wide end face and the narrow end faces the narrow end face. This avoids additional axial forces and limits the shaft or housing to axial clearance in both directions.

Angular contact ball bearings and tapered roller bearings are generally used in pairs, and there are two arrangements according to the different adjustments, installations and use occasions.

1. When the distance between the pressure centers of the two angular contact ball bearings or tapered roller bearings is less than the midpoint span of the two bearings, it is called formal installation. The shafting system of this method is simple in structure, easy to assemble and disassemble, and easy to adjust, but the heating elongation of the shaft will reduce the axial clearance of the bearing, and even get stuck.

2 When the pressure center distance of the two angular contact ball bearings or tapered roller bearings is greater than the span of the midpoint of the two bearings, it is called reverse mounting, and obviously, the thermal expansion of the shaft will increase the axial clearance of the bearing. In addition, the structure of reverse installation is more complex, and it is inconvenient to assemble and disassemble and adjust. Stiffness analysis of positive and reverse installation When the cantilever installation of transmission parts, the stiffness of the shafting system of the reverse installation is higher than that of the shafting system of the positive installation, because the pressure center distance of the bearing of the reverse installation is larger, so that the reaction force, deformation of the bearing and the maximum bending moment and deformation of the shaft are smaller than that of the formal installation.

When the transmission part is between the two bearings.

Formal mounting helps to increase the stiffness of the shaft by reducing the distance between the center of pressure of the bearing, while reverse mounting does the opposite. Therefore, the positive and reverse assembly of two angular contact ball bearings or tapered roller bearings should be considered according to the structure of the transmission parts (gears, worm gears) and shafts. And choose to use.

1. Angular contact ball bearings can bear radial load and axial load at the same time. Able to operate at higher speeds.

2. The larger the contact angle, the higher the axial bearing capacity.

3. The contact angle is the angle between the contact point connection line of the ball and the raceway in the radial plane and the perpendicular line of the bearing axis. High-precision and high-speed bearings typically take a 15-degree contact angle. Brother Chi.

4. Under the action of axial force, the contact angle will increase. There are raceways on the inner and outer rings of angular contact ball bearings, and the inner and outer rings can be moved along the axial direction of the bearing.

5. This kind of bearing is especially suitable for bearing compound filial piety load, that is, the load that acts radially and axial at the same time. The axial load bearing capacity of angular contact ball bearings increases with the increase of contact angle.

6. The contact angle is the angle between the contact line of the ball and the raceway in the radial plane and the vertical line of the bearing axis.

There are three types of angular contact ball bearings: back-to-back, face-to-face and tandem arrangement. The outer ring of an angular contact ball bearing, thick on one side and thin on the other. The thick side is called the "back", and the thin side is called the "surface".

Angular contact ball bearings are mostly installed in pairs and preloaded. If the installation is good, the working accuracy and bearing life of the host can be greatly improved; Otherwise, not only will the accuracy not meet the requirements, but the service life will also be affected.

1. When installed back-to-back (the wide end faces of the two bearings are opposite), the contact angle of the bearing spreads along the direction of the axis of rotation, which can increase the rigidity of its radial and axial support angles, and the maximum anti-deformation ability;

2. When face-to-face (the narrow end faces of the two bearings are opposite) are installed, the contact angle of the bearing converges towards the direction of the axis of rotation, and the rigidity of the bearing angle is small. Because the inner ring of the bearing extends out of the outer ring, when the outer ring of the two bearings is pressed together, the original clearance of the outer ring is eliminated, and the preload of the bearing can be increased;

3. When the series arrangement (the wide end face of the two bearings is in one direction) is installed, the contact angle of the bearing is in the same direction and parallel, so that the two bearings can share the working load in the same direction. However, in order to ensure the axial stability of the installation, two pairs of bearings arranged in series must be mounted opposite each other at both ends of the shaft. The above is precision bearing, Rockwell's hope to help everyone.

It mainly depends on the size of its nominal contact angle.

In the direction of the axis of the axis, the radial perpendicular to it is the direction of the radius along the axis. Therefore, the axial load of the bearing refers to the load generated in the axial direction of the bearing. In layman's terms, it is the force that pushes the inner ring of the bearing out of the outer ring.