First, the basic concept of bearing life

According to the latest fatigue life theory of rolling bearings, a bearing with excellent design, excellent material, well-made and correct installation, as long as the load it bears is easy enough (not greater than a certain permanent limit load value corresponding to the bearing), the material of this bearing will never cause fatigue damage. Therefore, as long as the working environment temperature of the bearing is suitable and the change is not large, absolutely no solid dust, harmful gas and moisture intrude into the bearing, the lubrication of the bearing is sufficient and just right, the lubricant is absolutely pure and free of impurities, and will not age and deteriorate... , the bearing will run indefinitely.

The significance of this theory is not only that it provides a more reliable tool for predicting bearing life than the ISO life equation, but also that it shows that the fatigue life of all rolling bearings has considerable development potential. And show the way to develop this potential, and thus have a profound impact on the development, quality management and application technology of bearing products.

However, the infinity of bearings can only be realized under laboratory conditions

For bearings used in the field, their working load is often greater than their corresponding fatigue endurance limit load. After a certain period of work, sooner or later, due to the fact that the material itself reaches the electrical fatigue limit, fatigue spalling will occur. And can not continue to use. Even if the working load of some bearings is lower than its corresponding permanent limit load, wear failure will occur due to the problem of bearing contamination that is difficult to eradicate. In short, the bearings in field use are more or less always insufficient. Having those conditions in the above-mentioned laboratory, and any one of them is slightly insufficient, will shorten the usable period of the bearing, which will cause the life of the bearing.

Generally speaking, the life of the rolling bearing is It refers to the long service period in which the rolling bearing can continuously maintain the working performance and working accuracy that meet the active requirements under the actual service conditions (including working conditions, environmental conditions and maintenance and maintenance conditions, etc.).

II. Calculated bearing life categories

The failure modes of rolling bearings are various, but there is no available life calculation method for most of them. Only fatigue life, wear life, lubrication life and fretting life can be calculated by calculating It can be quantitatively evaluated by the method.

1. When the fatigue life is adequately lubricated and other operating conditions are normal, rolling bearings often fail due to fatigue spalling. The specified formula and calculation program are calculated with certain reliability.

2. Wear life The main bearing of the machine tool takes a large diameter to ensure that the size of the bearing is correspondingly large. Before reaching the fatigue limit, the accuracy is often lost due to wear and can not continue to be used. For this type of bearing, the wear life must be used to measure its possible service period. In fact, most of the bearings used in the field fail due to excessive wear, so The wear life must also be considered.

3. The lubrication life is mainly for grease lubricated bearings with double-sided seals. After one-time grease filling, no additional grease will be added. At this time, the life of the bearing depends on the amount of rolling grease. Service life.

4. Fretting abrasion service life The bearings in winches, cantilever cranes, gear boxes, and automobile clutches are subject to vibration loads when they are not in operation. The fretting wear damage is often developed into the leading cause of bearing failure. For bearings in this type of mechanism, the fretting wear life sometimes needs to be calculated.

Now the four life categories and their calculation methods are respectively be introduced.

1. Fatigue life of rolling bearings

1. Basic concept of bearing fatigue life

The general bearing fatigue life refers to a certain technical state (structure, process state, fit, installation, clearance and lubrication state, etc.) rolling bearings run under the actual use state of the host until the rolling table