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Fracture Failure Analysis of Backing Rolling Bearing Jacket

wallpapers News 2020-12-15
The failure mode of the bearing is mainly the early fatigue failure of the bearing, that is, the raceway and the outer diameter surface will peel off under repeated stress. For supporting rolling bearings, the shell is particularly ruptured in a short time, which is unique. Therefore, a fracture analysis is performed.
 
The light yellow burning colour on the outer surface of the ferrule indicates that the ferrule has been damaged by mechanical heat. Under the action of heat, the hardness of this area drops sharply from HRC60.5 to HRC50, and the strength is greatly reduced. It is easy to produce extrusion cracks under the action of mechanical force. . The existence of cracks significantly reduces the fracture strength and causes stress to be concentrated at the crack tip. In the next stress cycle, when the stress reaches or exceeds the material strength limit, the gasket will fracture early.
 
Thermal burns on the surface of the ferrule are caused by excessive installation interference. Most of the reasons for the fracture of the inner and outer rings of rolling bearings are caused by excessive installation interference. The rounded corners of the shaft or housing are too large; severe burns or excessive shock loads. Whether the rolling force of the backing bearing even depends on the dimensional accuracy of the backing bearing. The original dimensional accuracy of the support bearing is very high.
 
Secondly, although the internal organization of the ferrule is normal, and the surface hardness of the outer diameter meets the technical requirements, there is a certain degree of tissue separation. Although there is no direct relationship between organizational isolation and component failure, it does affect the life of the material. It is easy to cause cracks in the weak areas of tissue isolation, which is an organizational factor that cannot be ignored.
 
Conclusion and Suggestion
 
Through the above inspection, analysis and discussion, the following conclusions and suggestions can be drawn:
 
(1) The internal structure of the ferrule is normal, and the surface hardness of the outer diameter meets the technical requirements. Except for a certain degree of structural segregation, no metallurgical defects that may cause cracks were found.
 
(2) Mechanical thermal damage to the outer surface of the ferrule due to friction, causing the ferrule to appear to be crushed. The existence of cracks will significantly reduce the fracture strength and cause stress concentration at the crack tip. When the stress reaches or exceeds the material strength limit, the ferrule will break early.
 
(3) Due to excessive installation interference, local thermal damage is caused on the outer surface of the sealing gasket. It is recommended to strengthen assembly quality inspection and management. For multi-roll cold rolling mill backing bearings, not only the material selection and manufacturing process should be paid attention to, but also the subsequent installation, adjustment and maintenance should be strictly managed.

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