Knowledge of the use and maintenance of rolling mill bearings

wallpapers Environment 2020-10-27

Rolling mill rolls and ball bearing are important components of the rolling mill. In rolling production, the roll has to be in direct contact with the rolled metal, and plastic deformation of the metal occurs. Therefore, the roll is the primary deforming part of the rolling mill, and the roll is supported by various types of bearings. The quality of the roll and the roll bearing is as well as The service life is directly related to the quality, output profit and output cost of rolling mill products. Therefore, the use and maintenance of roll bearings, as well as damage treatment are particularly important.

Operating environment of roll bearings

Roll bearings are used to support rolls. Compared with general-purpose bearings, roll bearings have the following characteristics:

01Withstand high unit pressure

Because the outer dimension of the bearing seat is limited, it cannot be larger than the minimum diameter of the roll body, and the length of the roll neck is short, so the unit load on the bearing is large. The unit pressure of general roll bearings can be as high as 2000-4800Mpa, which is 2-5 times that of general bearings, and the pv value (the product of unit pressure and linear velocity) is 3-20 times that of general bearings.

02 Big difference in operating speed

Different rolling mills have different operating speed requirements, and their speeds are still very different. For example, the export speed of the modern six-stand cold casting and continuous rolling mill has reached 42m/s, and the export speed of the high-speed wire rod mill has reached 100m/s. The speed of the low-speed rolling mill is only 0.2m/s. Obviously, rolling mills of different speeds should use different types of bearings.

03 Poor operating conditions

During hot rolling, the rolls must be cooled by water, and some dirty water, iron oxide scraps, etc. are easily immersed in the bearing. The cold rolling mill selects the process smoothing agent (emulsion, etc.) to smooth the material of the cooling roll and the rolled piece. The smoothing agent cannot be mixed with the bearing emulsified liquid. This puts higher requirements on the sealing of the bearing.

Therefore, the requirements for roll bearings are large load-bearing capacity, small impact coefficient, impact resistance, and work at different speeds; in terms of structure, the radial dimension should be as small as possible (in order to select a larger roll neck diameter ), with excellent smoothing and cooling conditions. When necessary, the roll bearings need to be removed from the rolling mill for testing and maintenance, so as to maximize the service life of the roll bearings. The frequency of bearing maintenance and maintenance should be adjusted according to the working conditions of the rolling mill, mainly according to the operating conditions. The general maintenance frequency is that full-load bearing work is inspected every three months, most rolling mills are maintained every six months, and light-load working rolling mills are maintained every twelve months.

Roll bearings should be checked separately after the initial work for 1000h. During the maintenance process, the bearings should be cleaned completely and the oil seal should be checked at the same time. If it fails, the oil seal should be replaced completely. If no abnormality is found, the second inspection time can be extended, for example, after every 2000 hours or more, from the rolling mill Remove the bearing and bearing seat and other components, check the working condition, and record the bearing position and bearing area of ??the rolling mill each time.