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Spherical roller bearing use, installation, and precautions

Features of spherical roller bearings

The spherical roller bearing has a double row of rollers, the outer ring has a common spherical raceway, and the inner ring has two raceways that are inclined at an angle relative to the bearing axis.

This ingenious structure enables it to have self-aligning performance, so it is not easily affected by the angle between the shaft and the bearing box seat on the error or the shaft bending, and is suitable for the occasions where the angle error is caused by the installation error or the shaft deflection.

In addition to radial loads, the bearings can also withstand axial loads acting in both directions.

Spherical roller bearings have two types of inner holes: cylindrical and conical, and the taper of the conical taper hole is 1:30 and 1:12.

This conical inner hole bearing is equipped with an adapter sleeve or a withdrawal sleeve. The tapered inner hole self-aligning ball bearing can be easily and quickly assembled on the optical shaft or the stepped machine shaft.

The models of spherical roller bearings are

  1. spherical roller bearing (type 20000CC)
  2. spherical roller bearing with tapered hole (type 20000CCK)
  3. spherical roller bearing (type 20000CC/W33)
  4. spherical roller bearing with tapered hole (20000CCK/W33 type)
  5. Spherical roller bearing mounted on the adapter sleeve (20000CCK+H type)
  6. Spherical roller bearing mounted on the adapter sleeve (20000CCK/W33+H type)

A total of 6 types.

Spherical roller bearing application

Mainly applicable cage: stamped steel plate reinforced cage (suffix E, very few in China). Stamped steel cage (suffix CC), glass fiber reinforced polyamide 66 cages (suffix TVPB), machined brass two-piece cage (suffix MB).

Machined brass integral cage (suffix CA), a stamped steel cage for vibration applications (suffix JPA). Brass cage (suffix EMA) for vibration applications. For the same structure, the code on the bearing may be different.

Main uses: papermaking machinery, reduction gear, railway vehicle axles, rolling mill gearbox bearing housings, rolling mill rolls, crushers, vibrating screens, printing machinery, woodworking machinery, various industrial reducers, vertical self-aligning bearings with seats.

Spherical roller bearing installation

Spherical roller bearings are equipped with drum-shaped roller bearings between the inner ring with two raceways and the outer ring with spherical raceways.

The center of curvature of the outer ring raceway surface is consistent with the center of the bearing, so it has the same self-aligning function as the self-aligning ball bearing.

When the shaft and housing are deflected, the load can be automatically adjusted and the axial load in two directions. Large radial load capacity, suitable for heavy loads and shock loads.

The inner diameter of the inner ring is a bearing with a tapered bore, which can be directly mounted. Or install it on the cylindrical shaft using an adapter sleeve and a dismantling sleeve.

The cages use steel stamping cages, polyamide forming cages, and copper alloy turning cages.

For self-aligning bearings, the use of an intermediate mounting ring prevents tilting and rotation of the outer ring when installing the bearing with a shaft into the housing shaft hole.

It should be remembered that some sizes of self-aligning ball bearings have balls that protrude out of the sides of the bearing, so the middle mounting ring should be recessed to prevent damage to the balls.

A large number of bearings are generally installed mechanically or hydraulically.

For separable bearings, the inner ring and outer ring can be installed separately, which simplifies the installation process, especially when the inner and outer rings need an interference fit.

When installing the shaft with the inner ring in place into the bearing housing including the outer ring, you must pay attention to check whether the inner and outer rings are correctly aligned to avoid scratching the bearing raceway and rolling parts.

Mounting sleeves are recommended for cylindrical and needle roller bearings with inner rings without flange rib or inner ring with flange on one side.

The outer diameter of the sleeve should be equal to the inner ring raceway diameter F, and the machining tolerance standard should be d10. Drawn cup needle roller bearings are best mounted with mandrels.

Spherical roller bearing clearance

For the installation axial clearance of the spherical roller bearing, the adjustment nut on the journal, the adjustment washer, and the thread in the bearing seat hole can be used, or the preload spring can be used to adjust.

The size of the axial clearance is related to the arrangement of the bearing during installation, the distance between the bearings, and the material of the shaft and the bearing seat, which can be determined according to the working conditions.

For spherical roller bearings with high load and high speed, when adjusting the clearance, the influence of temperature rise on the axial clearance must be considered, and the clearance reduction caused by temperature rise must be estimated, that is, the axial clearance.

The gap should be appropriately adjusted to be larger.

For bearings with low speed and vibration, they should be installed without clearance, or installed with preload.

The purpose is to make the rollers and raceways of spherical roller bearings have good contact, distribute the load evenly, and prevent the rollers and raceways from being damaged by vibration and impact.

After adjustment, check the axial clearance with a dial gauge. The method is to fix the dial indicator on the fuselage or bearing seat first, so that the dial indicator contact can withstand the smooth surface of the shaft, and push the shaft left and right along the axial direction.

The maximum swing of the dial is the axial clearance value.

Spherical roller bearing attention problems

The preloading force of the spherical roller bearing is carried out at room temperature, but in the working state, the drive shaft caused by the micro-stretching temperature of the system will change the bearing preloading force.

Therefore, the set preloading force should be considered for this factor.

It requires the ability of size, speed, and other conditions to set the reasonable use of spherical roller bearing preload to ensure the life of the transmission. If the preload is too large, the power consumption may even lead to overheating.

If the preload is too small, under the action of the body load, the shaft rolling, and the gap between the outer rings, there will be beating, running, and the transmission accuracy will increase to reduce noise, affect the gear meshing, and severely damage the teeth and bearings.

According to different spherical roller bearing assemblies, such as: directly by the axial compression of the inner bearing inner ring, the bearing preload nut is rotated, and the inner and outer rings are rotated to eliminate the gap and achieve the purpose of bearing preload.

Achieving common use: first, well over the preloaded bearing, last of the nut, then back 1/4 turn. Assembly method, the advantages of this method are less investment, simplicity, practicality, and consistency with the premise of good quality tapered roller bearings, it can be used.

Electric heating plate heating method: Put the bearing on the electric heating plate at a temperature of 100 ℃ for a few minutes. This method is the most simple. If it is turned several times, the bearing can be heated evenly, and the efficiency is also high.

This method can be used.

Electric furnace heating method: Put the bearing in a closed automatic temperature-controlled electric furnace for heating, the heating is uniform, the temperature control is accurate, the heating is fast, and it is suitable for heating many bearings in a batch.

Induction heating method: The use of induction heaters can quickly, reliably, and cleanly heat the spherical roller bearing to the required temperature, which is especially suitable for occasions where the inner ring is tightly fitted, because only the inner ring is heated, and the outer ring is heated.

The ring is less heated, which makes it easier to install on the shaft and into the seat hole.

The light bulb heating method uses a 50W light bulb to heat the spherical roller bearing, which can ensure that the heating temperature is about 100 ° C. The smaller bearing can be placed directly on the bulb, and the larger bearing can be placed in the cone of the bulb.

The cover can prevent the heat loss of the bulb, and make the heating uniform. The conical cover can be adjusted up and down and can be adapted to heat bearings of different sizes within a certain range.

If far-infrared light bulbs are used, pay attention to the direction of the light bulbs, so as to avoid infrared rays being harmful to people.

This kind of light bulb can be used for energy-saving light bulb heating method, which is suitable for a small number and is not often needed; where the bearing needs to be heated, the light bulb can also be used for lighting at ordinary times, and no other equipment is required.

Oil tank heating method: This is a widely used traditional heating method. A metal mesh is installed at a distance of 50~70mm from the bottom of the oil tank, and the bearing is placed on the mesh.

The large bearing should be lifted by hooks and should not be placed directly at the bottom of the tank to prevent contact with the tank. The bearing parts at the bottom are locally heated too high, or the dirt deposited at the bottom of the tank enters the bearing oil tank.

The points to note in the heating method are as follows. Non-corrosive mineral oil with good thermal stability should be used, preferably transformer oil. Both the oil and the container should be used.

The capacity of the oil tank to keep clean should be determined by the size and oil volume of the heated spherical roller bearing. If the container is too small, during continuous operation, the oil temperature will drop quickly once the bearing is put in, and the effect will not be good.