Four row cylindrical roller bearings can be selected as rolling mill roller bearings, relative to other bearings of the same size series mainly have the following characteristics:

Standard shape, easy to process high precision

Separable, easy to disassemble and clean

Linear contact of rolling element, strong bearing capacity

Locally interchangeable, easy to disassemble and change rolls

The main industry standard JB/T5389.1-2005 for four-row cylindrical roller bearings used in rolling mills in China is to standardize the outline dimension of four-row cylindrical roller bearings used in rolling mills, and the tolerance of the inner raceway diameter is prescribed in the standard as minus tolerance (see Table 1). The size tolerance of the inner raceway is fixed to determine the radial clearance of different groups, and the size of the outer raceway is processed to determine the size tolerance of the inner compound circle of the roller.

However, in the actual production due to competition, size non-standard and other factors, resulting in relatively chaotic size. The FW value is changed by itself, causing problems such as interchange deviation and clearance change, which cause great difficulty in the daily work of steel mill assembly. See Figure 1;

In China's current national standard, the inner raceway size of the four-row cylindrical roller bearing is the interchangeable standard size of the rolling mill bearing, that is to say, the four-row cylindrical roller bearing used in the rolling mill is the base shaft system. In order to ensure the accuracy of rolling materials, the rolling mill needs to change rolls frequently, and there are many spare rolls. Often, the spare rolls of the steel or long rolling mill reach 1 to 4 or even more, which requires the inner rings of the four columns of cylindrical roller bearings to be separated and interchangeable. Therefore, special attention needs to be paid to the accuracy of Fw dimensions in the pre-sale communication and dimension measurement stage.

When the inner diameter exceeds 450mm, the size is often matched with FW as a fixed value, which is unified with foreign brands such as FAG and SKF. That is, the value of FW is used as the first element of the exchange of four rows of cylindrical roller bearings to determine the radial clearance and then determine the machining tolerance of the inner raceway, that is, the base hole design. See Figure 2 and table △FW tolerances;

The tolerance of FW value of the roller compound inner diameter is used as an interchangeable matching size, in the form of base hole system, and the positive tolerance requirements, △FW tolerance can be selected by referring to the following table;