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Application of locating bearing for cold tandem mill

wallpapers Tech 2020-10-27

The 60/630M deep groove ball bearing on the drive side of the cold rolling mill support roll of the cold rolling mill is used for positioning. It is used as the deep groove ball bearing for positioning on the transmission side. Because it does not bear a large axial load, it is not easy to damage. However, the 60/630M bearings used by the company have abnormally high frequency of damage. The stainless steel rolled by the rolling mill is 201 stainless steel and 304 stainless steel. The rolling speed is 240m/min and the rolling force is 450KN. The abnormal damage of the positioning bearing has seriously affected the normal production, and has also attracted the attention of the steel mill's grinding team and invited us to assist in technical support.

After receiving the request from the steel mill, two rolling mill bearing engineers who are experienced in rolling mill bearing applications were dispatched to the site for technical support. Bearing assembly technicians introduced the use of 60/630M bearings on site;

1) The cage design of the bearing is composed of two half cages combined into an integral cage. After a period of use, the loose gap between the two half cages is too large or cracks directly, causing the bearing to be scrapped before its life cycle.

2) The bearing inspection found that the surface of the steel ball was severely peeled off, and the inner and outer raceways had different degrees of peeling.

Deep groove ball bearings are mainly used for locating bearings on the transmission side of rolling mills. They serve as a floating support when the rolling mill is working and cannot bear radial forces. If the outer diameter of the bearing and the bearing seat are in an interference state, the bearing will be subjected to a radial load force, so that the steel ball and inner and outer raceways of the bearing are very likely to be damaged in advance or the outer ring is broken. It is impossible for the positioning bearing to have no axial force when the rolling mill is working. When the positioning bearing exists at the same time as the axial force and the radial force (the impact load during the rolling mill is unavoidable), the cage is prone to loosening or cracking phenomenon.

Through on-site technical exchanges and visits, in view of the actual working conditions of the steel plant, our suggestions for improvement on the bearing are as follows;

1) The outer diameter of the bearing is 50 wires smaller than the national standard size, which completely avoids the radial force of the positioning bearing.

2) The cage structure maintains the original design structure. The cage is changed from rivet connection to bolt connection. Before the bolts are tightened, fill the threads with anaerobic glue, and weld the bolts on the outside to ensure that the bolts will not loosen.

4) The coefficient of curvature radius of the inner and outer raceway of the bearing is increased accordingly. Increasing the raceway curvature can effectively avoid the damage to the cage by the axial force. Increasing the curvature of the groove can make the rotation of the bearing more flexible.

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