The protection and maintenance of SKF rolling mill bearing

Writer: Eric Bearing Limited

Mill roll and roll bearing are important components of rolling mill. the roll is directly contacted with the rolled metal in rolling production, and suffers metal plastic deformation, thus, the roll is the primary deformation part of the mill, and is supported by various bearings, roll and roll bearing and service life are directly related to the product quality of mills, output profit and production cost. Therefore, the use and maintenance of rolling bearing, as well as damage removal are particularly important.   Eric Bearing have rich stock for ball bearings SKF 6310-2Z ,more details , pls click here :

Operating environment of SKF roll bearings

Roll bearings are used to support the roll, compared with general purpose bearings; roll bearings have the following characteristics:

1. High pressure per unit

Because dimensions of the bearing housing is limited, cannot be greater than the minimum diameter of the roll body, and the length of the roll neck is short, so  it's unit load on the bearing is large. The unit pressure of general roll bearing can be up to 2000-4800 mpa, which is 2-5 times that of general bearings, and pv values (unit pressure and linear velocity product) is 3-20 times than that of general bearings.

2.The operation speed of roll mill is greatly varied 

Different rolling mills have different requirements for operation speed, they are much different, for example, the modern six stand cold casting mill outlet velocity has reached 42 m/s, the high speed of wire-rod mill is up to100 m/s, and the low speed of rolling mill is only 0.2 m/s. Obviously, different speed of rolling mill should use different types of bearings.

3. Poor operating conditions

As the hot rolling roll is cooled by water, some dirty sewage and iron oxide scrap easy immerse bearing. The cold-rolling mill is often selected smoothing agent (emulsion, etc) to smooth the cooling roll and rolled piece l, the smooth agent cannot be mixed with bearing emulsion. This put forward higher requirements for the bearing seal.

Therefore, the demands for roll bearing are large loading capacity ,small impact coefficient, resistance to impact, and working at different speed; the requirements for the roll structure, the radial dimensions should be as small as possible (in order to choose a larger roll neck diameter), with excellent smooth and cooling conditions. 

If necessary, roll bearings should be removed from the mill for testing and maintenance, so as to maximize the service life of rolling bearings. The frequency of bearing maintenance should be adjusted according to the rolling condition; the primary maintenance can be according to operation load, the general maintenance frequency is that the full load bearing should be respected once every three months. Most of the rolling mills are maintained every six months; the light load work mill is maintained every twelve months. Eric Bearing have rich stock for ball bearings SKF 6209-2Z/C3 , more details , pls click here

（2）Before and after use of treatment for roll bearings. When a new roll is transported into the factory, don’t let it in bump damage, After inspected and approved by relevant departments, the new roll should be coded and installed in the correct order, then inner sleeve and seal end cover and other auxiliary parts are installed onto the top of the roll. 

The general installation method: the bearing inner ring is usually heated to 150% ~ 200% by oil or electric heater, while the inner sleeve expansion the bearing can be hot installed on the roll neck. In order to delay fatigue failure, all kinds of fault disturbance should be avoided, a timely check up and proper maintenance will keep bearing in a good operation service period.