Adjustment and preloading of rolling bearing clearance

The assembly of rolling bearings is a common operation in the assembly and repair work of the fitter, and the adjustment and preloading of the rolling bearing clearance is an important part of the rolling bearing assembly work. Accurately grasping the process concept of clearance adjustment and pre-tightening, and correctly applying this process in assembly work is the guarantee of the quality of bearing assembly work.

The clearance of the rolling bearing refers to the maximum amount of movement of the other ferrule in the radial or axial direction when one ferrule is fixed, so the clearance is divided into radial clearance and axial clearance.

When the rolling bearing is assembled, its play should not be too large or too small. If the clearance is too large, the number of rolling bodies that can bear the load at the same time is reduced, so that the load of the single rolling body is increased, thereby reducing the rotation precision of the bearing and reducing the service life; if the clearance is too small, the frictional force is increased, resulting in an increase The increased heat, which exacerbates wear and tear, also reduces the service life of the bearing. Therefore, many bearings must be tightly controlled and adjusted during assembly.

The pre-tightening is that when the bearing is assembled, an axial force is applied to the inner ring or the outer ring of the bearing to eliminate the bearing play and cause initial deformation of the rolling element in contact with the inner and outer rings. Preloading can improve the stiffness and rotation accuracy of the bearing under working conditions. For bearings with large load and high rotational accuracy, most of them work without clearance or even a small amount of interference. In this case, the bearings need to be pre-tensioned during assembly.

The adjustment and preloading of the clearance are usually carried out by means of a suitable axial relative displacement of the inner ring of the bearing to the outer ring.

It is not difficult to see from the above concept of the technology that the adjustment of the rolling bearing clearance can improve the bearing capacity and rotation accuracy of the bearing and improve the service life of the bearing. At the same time, the bearing friction will be intensified and the heat generation will increase. Therefore, it is necessary to ensure good lubrication and heat dissipation while adjusting the clearance or pre-tightening. If improperly adjusted or poorly lubricated, it will in turn increase bearing wear and reduce life. Therefore, the following problems must be noted in the correct adjustment and preloading of the rolling bearing clearance.

1. Assembly technical requirements are the fundamental basis for selecting assembly process methods

The adjustment of the rolling bearing clearance can effectively improve the bearing rotation precision, improve the bearing capacity of the bearing, prolong the service life of the bearing, and also effectively reduce the vibration and noise, but not all rolling bearings need to be installed during assembly. Adjustment. The pre-fastening can improve the bearing rigidity and the precision of the rotation, but at the same time, the friction is intensified, the lubricating oil film is destroyed and a large amount of heat is generated. Therefore, the pre-tightened bearing must be forcedly lubricated and cooled. This method is limited to It is a special process for the bearing rigidity and rotation precision requirements. It is only used in the machine tool spindle assembly. The bearing assembly of other transmission mechanisms is almost invisible.

Whether to adjust and pre-tighten the clearance in the rolling bearing assembly is determined according to the assembly technical requirements of the technical documents. Specifically, in the assembly technical requirements, the bearings with high requirements for high speed, heavy load or rotation accuracy are generally required to adjust the bearing clearance or preloading. Otherwise, the bearing clearance is maintained, and only the shaft is used for assembly. Just fix it. From the perspective of the type of bearing, the clearance of the tapered roller bearing, the angular contact bearing and the thrust bearing needs to be adjusted; for the general low-speed, light-load radial ball bearing, in most cases, the clearance is not required. Adjusted and only fixed axially.

For more information and purchase please visit: https://www.supplyforever.com

Thrust ball bearing installation stability maintenance problem solution

When inspecting the thrust ball bearings that have been removed during the regular inspection and operation of TIMKEN bearing equipment and the replacement of peripheral parts, it is necessary to determine in turn whether the secondary bearing parts can be reused and the usage is better. Also carefully investigate and record the removed bearings and appearance. In order to clarify and investigate the remaining amount of lubricant, the bearings should be cleaned well after sampling.

Next, check the raceway surface of the bearing, the condition of the rolling surface and the mating surface, and the wear state of the cage, etc., for damage and abnormality, especially to observe the running track of the raceway surface. To determine whether the bearing can be used again, it is necessary to consider the degree of damage to the thrust ball bearing, machine performance, importance, operating conditions, inspection cycle, etc.

If the bearing is found to be damaged or abnormal, please find out the cause according to the phenomenon of bearing damage and formulate countermeasures. In addition, the inspection results, if there are the following defects, TIMKEN bearings can no longer be used, need to replace the new bearings.

When grease is added to anti-friction bearings, high pressure theory may not be required unless it is used with great care. High pressure can damage bearings and waste grease. Excessive grease can cause high temperatures and create an invisible environment around the bearings. In most applications, ball or roller bearings are fully lubricated if the grease level is between one-third and one-half of the bearing capacity. The excess will usually be wasted by the sealed casing.

1. Are all requirements for the installation surface and installation site?

If there is foreign matter such as iron filings, burrs, dust, etc. in the thrust ball bearing, the bearing will generate noise and vibration during operation, and even damage the raceway and rolling elements. Therefore, before installing the bearings, you must ensure that the mounting surface and the installation environment are clean.

2. Must the bearings be cleaned before installation?

The surface of the bearing is coated with anti-rust oil. You must clean it with clean gasoline or kerosene, and then apply it with clean high-quality or high-speed high-temperature grease.

The effect of cleanliness on TIMKEN bearing life and vibration noise is very large.

But we must remind you that the fully enclosed bearings do not need to be cleaned and refueled.

3. How to choose grease?

Lubrication has a very important influence on the operation and life of the bearing.

Here is a brief overview of the general principles for selecting grease. Grease is made of base oil, thickener and additives. The grease performance of different types and different grades varies greatly. The allowable rotation limit is different. Be careful when selecting.

For more information and purchase please visit: https://www.supplyforever.com