Lubrication and sealing of rolling mill bearings（part 2）

The sealing of rolling mill bearing plays an important role not only in hot rolling mill but also in cold rolling mill.This is because the operating conditions of the mill are relatively bad, not only to prevent the hot rolling metal oxide skin on the surface of the rolling material after falling off the immersion and a variety of other foreign matter invasion (see figure 2), but also to prevent the infiltration of cooling media (see figure 3).Otherwise, the working condition of the bearing will deteriorate sharply, and the lubricating oil film will be damaged, so that the surface of the bearing will quickly wear out, and then pitting and peeling will occur rapidly in serious cases, which will greatly reduce the service life of the bearing.Especially when hard foreign bodies (including oxidized iron sheet) are immersed, defects such as indentation and pad injury will appear on the rolling surface of the bearing very quickly, which will lead to stress concentration on the working surface of the bearing in this defect and induce early fatigue failure.

If the external cooling medium invasions will make the bearing rust and other phenomena (as shown in figure 4), will also destroy the oil film on the working surface, make the bearing premature failure.Therefore, the bearing seal of rolling mill plays a very important role in improving the life of the bearing. Usually, the bearing seal of rolling mill is usually installed on the bearing box and the roller neck, but the seal is prone to aging, damage and failure.

Attention should be paid to the sealing of rolling mill bearings during use:

1. Choose appropriate sealing form and structure.

2. For the material of rubber seals, butadiene rubber can be generally used, but when the working temperature is > 200℃, the high temperature resistant fluoro rubber should be used.

3. Do not damage the sealing device during the installation of roller bearings.

4. The use and storage period of rubber seals shall not exceed 2 years, or they will deteriorate and affect the sealing effect.

In recent years, the design of bearing seal has been widely used in the application of rolling mill seal structure, and its application effect is obviously better than the original sealing capacity.