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

Roller is carried by the rotating ring, in the case of strength allows, reduce its weight, to reduce the purpose of inertia resistance. To prevent and reduce sliding becomes very important. It is easy to adopt this measure, which can be achieved only by reducing its number and diameter. In the aero-turbine engine, contact fatigue is not the main damage factor of roller due to the small external load. According to the conventional standard of bearing size surplus is still large, it is generally believed that the number of rollers is reduced by 50%, and the diameter is reduced by 25%, it still does not affect its contact fatigue life. Many engines have adopted this measure, for example, the Spie engine main bearing is of this type, not only the rollers are significantly sparse, but also small size.

2, choose reasonable structure and reduce the weight of the cage

In addition to reducing the weight of the cage as far as the strength allows, its own characteristics should be considered, for example, its resonance, high speed rotation resistance should be avoided.

Cage guide mode is also a very important factor in high speed bearings. If the unbalance of the cage is well controlled, the cage is guided from the outside to the inside, which is very beneficial to reduce skid. Because of the relative motion between the cage and the guide surface of the bearing, the oil film forms a viscous resistance, while the inner guide is on the contrary, the viscous force of the oil film between the cage and the guide surface becomes the drag force. In this way, the viscous resistance becomes the force dragging the cage around. The difference between the two is also not negligible.

3. Oil supply under the ring

The advantage of using underring oil supply is that it takes away the heat of the bearing and minimizes the extra loss caused by mixing. And such as the outer ring belt barrier edge to the inner ring belt barrier edge, is undoubtedly also can reduce the resistance of stirring.

4, the use of hollow roller preload bearing

Hollow roller preload bearing can apply preload to all rollers, so that all areas are free of sliding. Due to the wide operating speed and temperature range of turbine engine rotor bearings, the selection of appropriate preload should be careful. Even at very low external load, too much preload will still make the roller premature failure. A common form of failure is bending fatigue. A typical hollow roller, with a ratio of outside diameter to inside diameter of 2, should have a maximum hole bending stress of less than 25,000 lbs. per inch; The concentricity of the inner and outer diameters should be maintained at 0.005 mm.

5. Elliptical bearings are adopted

The use of elliptical bearings is the most common form of anti-skid, generally have two and three valve structure, as shown in Figure 6. Take the double-lobe elliptical bearing as an example, talk about its structure and anti-skid mechanism. This kind of bearing is generally elliptical outer ring diameter, inner ring diameter (raceway) and bearing seat are round. After assembly, the outer ring raceway becomes ellipse, that is, preload is added to the roller. That is to say, the radial clearance between the short half axis of the elliptical raceway and the raceway is eliminated (the formation of interference), so that the roller is compressed. Therefore, in addition to the bottom of a few roller by the rotor outside the effect of gravity load, on the left, right, 90 ° roller, also the load by a certain amount of additive, so the load of the roller number increased to about 60% of the total number of roller (roller bearing the load of the roller number commonly accounted for about 20% of the total number of roller), as shown in figure 7. Therefore, the added drag power helps prevent the roller and cage from slipping. However, the method of giving ellipticity will reduce the fatigue life of bearings, so it is necessary to consider the selection of the best ellipticity in use.

If you have any questions,pls feel free to contact us.

e-mail:bearing6@hyzcgroup.com