What should I do if the roller bearing is misaligned? Bearing manufacturers teach you these common tricks

When the roller bearing is working, the wooden sticks do a pure flipping fitness movement on the inner and outer ring raceways, so the support frame that pushes the rollers must have sufficient drag force to get rid of frictional resistance. If the drag force is not enough to get rid of the frictional resistance, the rollers will roll on the dovetail guide, resulting in a difference in speed, that is, deviation. So what should I do if the roller bearing is misaligned?

1. Reduce the number of rollers and reduce the diameter of the rollers

The roller is moved by the rotating ring. Under the condition of compressive strength, its net weight is reduced to achieve the purpose of reducing the frictional resistance of inertial force. It is increasingly critical to avoid and reduce scrolling. The choice of this strategy is relatively simple, and it can be done only by reducing its total number and diameter. In airline turbines, contact fatigue is not a critical failure factor for rollers due to the small external load. According to the basic specification of the bearing specification or large, it is generally felt that the total number of rollers is reduced by 50%, and the diameter is reduced by 25%, it still does not endanger its contact fatigue life. Many automotive engines have chosen this strategy, for example, the Spey engine main bearing is this type, not only the rollers are significantly rare, but also the size is exquisite.

2. Select the effective structure and relieve the net weight of the cage

In addition to avoiding its net weight as much as possible when the compressive strength allows the cage, its own characteristics should also be considered, for example, it should be prevented from resonance, high-speed running friction resistance, etc.

The correct guiding method of the cage is also a very critical element in the fast bearing. If the unevenness of the cage is properly controlled, it is also very beneficial to change the cage from the outer correct guidance to the inner correct guidance to reduce the deviation. Due to the relative speed between the correct guide surface of the cage and the bearing, the sliding oil produces a viscous frictional resistance, while the inner correct guidance is reversed, and the sliding oil between the cage and the correct guide surface is viscous. The force becomes the drag force. In this way, the viscous frictional resistance becomes the force that drags the cage to rotate. The difference between the two cannot be ignored.

3. Oil provided under the ring

The advantage of choosing the oil provided under the ring is that it brings the hotness of the bearing while minimizing the additional damage caused by mixing. Another example is to change the outer ring belt rib to the inner ring belt rib, which can undoubtedly reduce the frictional resistance of mixing, as shown in Figure 4.

4. Use hollow roller preload bearing

The hollow roller preload bearing can increase the preload on all the rollers, so that there is no rolling in all areas. Because the speed ratio and temperature range of the rotor bearing of the turbine motor are relatively wide, the selection of the appropriate preload should be cautious. Even at very low additional loads, excessive preload can cause premature failure of the rollers. A common form of destruction is bending fatigue. For a typical hollow roller, the ratio of diameter to inner diameter is 2, and the hole stress should be less than 25,000 lbs/ft; the concentricity of the inner and outer diameters should be maintained at 0.005mm.

5. Use elliptical bearings

The use of elliptical bearings is the most common ground anti-skid method, and there are generally two types of structures: double-lobed and three-lobed. Taking the double-lobed elliptical bearing as an example, talk about its structure and ground anti-skid principle. This type of bearing generally has an oval diameter of the outer ring, and the inner diameter (raceway) of the outer ring and the bearing seat are annular. After installation, the outer ring raceway becomes an ellipse, that is, the rollers are preloaded. In other words, the axial backlash between the roller and the dovetail guide at the short drive shaft of the elliptical dovetail guide is cleared (a clearance fit is generated), which reduces the rollers. Therefore, in addition to the effect that the lowermost rollers are subjected to the force load of the motor rotor, the rollers at 90° to the left and right are also subjected to a certain amount of preload, thereby increasing the number of rollers bearing the load. Raised to about 60% of the number of rollers (roller bearings generally bear the load of about 20% of the number of rollers). Thus, the increased drag force is beneficial to avoid misalignment of the rollers and cages. However, the way in which the ovality is derived will reduce the fatigue life of the bearing, so the selection of ovality must be considered in the application.