Factors Affecting Service Life of Rolling Mill

In the operation and use of rolling mill equipment, the higher the working temperature of the mechanical equipment, the lower the value of load capacity, the shorter the service life of bearing. The relationship between the hardness of bearing material and the service life of bearing, the influence of the hardness of bearing working surface material on the service life of bearing, mainly reflected in the reduction of the rated dynamic load value of bearing. The hardness of the surface of the bearing parts is generally in accordance with the standard. If the hardness of the material surface of the bearing parts is lower than the previous range, the nominal dynamic load number has a downward tendency.

The service life of the rolling mill operation is affected by the non-metallic inclusions in the steel strip on the contact fatigue. The oxide inclusions and the material matrix under the metal surface layer are easy to appear fatigue cracks because of the action of the external AC voltage. The more the number of non-metallic inclusions in the steel, the lower the fatigue life of the bearing. In order to reduce the non-metallic inclusions in the steel, the effective casting method must be used. Although the fatigue life of the bearing is improved, the cost of steel is too high.

Therefore, for important bearing materials, generally vacuum removal or vacuum degassing and steel refining are used, and the bearing life is enough to meet the performance requirements of users. The residual tension of the bearing material surface can affect the service life of the bearing. In the process of heat treatment, if the bearing parts are not treated properly, large thermal stress will be generated. If the cooling process is not sufficient or the rolling amount is too large, rolling accidents will also occur. When the bearing and the shaft shell match, the tension will be cut off and the interference will be too large.

In the use of the rolling mills, internal stress may also occur, including the destructive defects in the working surface of the bearing, which may also lead to the change of residual stress on the material surface. Generally, these additional residual stresses on the material surface caused by external factors are normal stresses, which are subject to normal cold and heating treatment.