Roll is a kind of production tool that can make metal produce plastic deformation. It is subject to complex stress state in production, which is easy to roll failure, peeling, fracture, roll surface damage, etc. Among the roll failure forms, there are many types of roll surface damage, which is also a common failure form, including roll surface cracks, indentation, oxide film falling off, slag inclusion, sticking steel, abnormal wear, etc.
1. Roll surface crack
The cracks can be divided into normal cracks and abnormal cracks. The normal cracks are also called hot cracks. They are gradual cracks on the roll surface caused by the thermal stress generated by multiple temperature cycles, which is a micro surface layer phenomenon on the roll surface; Abnormal cracks are thermal impact cracks caused by accidents such as slipping, sticking, sticking, stacking and tail flapping during rolling, and cracks with certain depth and ductility are formed locally on the surface of the roll surface.
2. Roll surface indentation
It mainly refers to the pressing of iron oxide scale and other foreign matters due to cleaning in the production process, and the continuous or discontinuous distribution of irregular shaped pits on the roll surface.
3. Falling off of oxide film
At the beginning of rolling, after a period of hot rolling, a thin layer of silver gray or light blue oxide film is formed on the surface of the roll, which is very important to protect the roll surface and improve the surface quality of the rolled piece. Because of the repeated effect of rolling force, the oxide film produces microcracks around the carbide; When the cooling capacity of the roll is insufficient, it is difficult to form a dense oxide film on the roll surface, and even if the oxide film is formed, it will deteriorate quickly. If the rolling is not reasonable, the oxide film is quickly destroyed during the formation process, which will cause the oxide film to fall off, leaving meteor spots and other defects on the roll surface, resulting in increased roughness and wear of the roll surface.
4. Sticking steel, abnormal wear, etc
The adhesion between the roll surface and the rolled piece due to abnormal rolling results in steel adhesion; Unreasonable process parameters during rolling cause excessive consumption of rolls with the same width and uneven wear of roll surface.
In production, standardized operation and equipment maintenance shall be carried out to avoid roll surface damage in the above aspects.
