Through its unique structural design, the self-aligning roller bearing for wind turbines has the ability to automatically align, withstand multi-directional loads, and adapt to complex working conditions. The following is a detailed introduction to its working principle:
1. Structural Design
The self-aligning roller bearing consists of a double raceway inner ring, double row symmetrical spherical rollers, a cage, and a large spherical outer ring. The outer ring has a common spherical raceway, while the inner ring has two raceways that are inclined at a certain angle to the bearing axis. This design allows the contact between the rollers and the inner and outer rings of the bearing to be linear contact rather than point contact when subjected to load, thereby improving the bearing's load-bearing capacity.
2. Principle of Automatic Alignment
Alignment Mechanism: When the shaft is bent or tilted under external load, causing relative rotation between the centerline of the inner ring and the centerline of the outer ring of the bearing, the special structure of the aligning roller bearing enables it to automatically adjust.
. Due to the spherical shape of the outer raceway and the alignment of the curvature center with the bearing center, the rollers can be aligned within the outer raceway to compensate for shaft deflection and concentricity errors.Alignment angle: The alignment angle allowed for aligning roller bearings is generally 1 ° to 2.5 °, and the specific value varies depending on the bearing size series.
. Within this range, even if the shaft and housing deform, the bearings can be adjusted accordingly, so as not to increase the additional burden on the bearings and ensure that they continue to work normally.III. Load bearing capacity
Radial load: Spherical roller bearings have high radial load capacity and are particularly suitable for working under heavy loads or vibration loads.
. Its two column roller design enables the bearing to evenly distribute radial forces and improve load-bearing stability. Axial load: In addition to bearing radial loads, self-aligning roller bearings can also withstand axial loads in any direction. Due to the angle between the roller axis and the bearing axis, the bearing can bear both radial and axial loads. The larger the angle, the stronger the axial bearing capacity. However, it should be noted that self-aligning roller bearings cannot withstand pure axial loads.Overturning moment: In applications such as wind turbines, the main shaft bearings need to bear the weight of the wind blades and hub, as well as the force exerted by the wind on the main shaft through the wind turbine, which can generate overturning moment.
. The multi-directional load-bearing capacity of self-aligning roller bearings enables them to adapt well to this working condition.IV. Motion Characteristics
Roller Motion: During the motion of the bearing, the roller generates centrifugal force and gyroscopic moment.
. Due to the fact that the load on the roller inside the bearing is not constant and only acts on the lower half of the bearing, the movement of the roller also varies with its position. Bearings are divided into two parts during normal operation: the load-bearing area and the non load-bearing area. The roller movement in the bearing area is synchronized with the inner ring, and the inner ring raceway controls its movement; Instead of the load-bearing area, the roller motion will slightly lag behind the cage due to the presence of damping.Cage movement: In addition to evenly separating the rolling elements, the cage can also guide the rotation of the rolling elements and improve the internal lubrication performance of the bearing.
. In self-aligning roller bearings, the movement of the cage also becomes extremely complex, as it needs to adapt to the discontinuous micro impact of the rollers and the relative sliding inside the bearing.