Bearing clearance is an important technical parameter of whether the bearing can work normally, and it directly affects the load distribution, friction, temperature rise, and service life of the bearing. As the working conditions of rolling mill bearings are harsh, the rolling load, speed, lubrication, temperature rise, matching interference, and rotation accuracy must be considered. The principle is that when the working conditions permit, the smaller the bearing clearance, the better it is to improve the service life of the rolling mill bearing. The rolling mill adopts four-row cylindrical roller bearings for standard rolling mills. Generally, the clearances are mostly C3 or C4 group standard clearances. For four-row cylindrical roller bearings for high-precision rolling mills, the clearance needs to be determined by the technical engineer and the bearing manufacturer according to the precision requirements of the rolling mill. The machining allowance is reserved for the outer circle of the inner ring of the bearing, and the inner ring of the bearing is assembled to the roll. Later, the outer circle of the inner ring of the bearing will be ground to the specified size together with the roller surface to obtain a high-precision coaxiality tolerance.
During the use of rolling mill bearings, it can be judged whether the bearing clearance is appropriate according to the damage of the bearing.
If the bearing burns, it is not because the inner ring of the bearing slides on the roll diameter, or the friction and poor lubrication of related parts cause the bearing to overheat, it can be considered that the working clearance of the rolling mill bearing is too small.
Bearing rings and rollers are broken. If it is not due to the raw materials, bearing quality, excessive impact load, and poor installation, it can be considered that the working clearance of the rolling mill bearing is too large, which makes the bearing load wrap angle too small (the ideal load angle is 120°～150°), which is caused by the large strain pressure per unit area of the material and the large roller load.
In addition, when using rolling mill bearings of different manufacturers for interchange use, we have to pay attention to whether the matching standards of the rolling mill bearing clearance are the same (that is, whether the inner circle dimensions and tolerances of the outer components of the bearing are consistent, whether the inner ring raceway dimensions and tolerance values is the same, and whether the clearance is the same), otherwise, the bearings cannot be interchanged. This is another reason why the above emphasizes that the bearing must have a fixed assembly relationship.
Reasonable and reliable matching accuracy is also a prerequisite for the correct use of rolling mill bearings. The inner ring of the four-row cylindrical roller bearing in the rolling mill roll system bears the circumferential radial load, so it must be an interference fit with the roll neck; the outer ring supports the concentrated load and needs to be excessively matched with the box hole; the matching bearing only bears axial Load and axial positioning function, and require easy assembly and disassembly, so the inner ring of the bearing and the roll neck have a clearance fit, and the outer ring cannot bear the radial force, and it has a large clearance fit with the box hole.
Please check the Product Guide to select suitable bearings for your machinery.
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