Discussion on Protection Treatment of Rolling Mill Equipment
In practical use, the rolls of rolling mill equipment may crack. Based on the analysis of its cracking phenomenon, the main part of the cracking is basically concentrated at the roll ring, and the cracking section is an irregular inclined plane or a vertical section. So, why does this happen?
The analysis of this problem can actually be explained from many aspects. First of all, it may be due to the quality problems of the roll itself, because the work roll is in direct contact with the high-temperature slab and bears various loads, so it is required to have excellent heat resistance. If the hardness of the roll body decreases greatly with the increase of the roll temperature, it means that the heat resistance of the roll is poor, which will seriously affect the overall performance of the roll.
If the rolling conditions are combined for analysis, the roll must also have good wear resistance and appropriate hardness and strength. In fact, the mechanical fatigue of the outer layer caused by the periodic loading of the roll, and the thermal fatigue caused by the periodic heating of the rolled piece and the periodic cooling of the cooling water on the surface of the roll will cause wear and tear of the roll and thermal cracks.
At the same time, the hardness specification of the roll is also very important. Generally, its hardness is inversely proportional to the thermal crack resistance of the roll body. That is to say, the higher the hardness of the roller body, the better the wear resistance, but the weaker its resistance to heat cracks. Generally speaking, the wear resistance of the roll and the hardness of the roll surface are related to the hardness difference along the diameter direction of the roll body, so it is expected that the hardness difference along the diameter direction of the roll is as small as possible, and the hardness is moderate.
In the actual rolling work, the roll will also bear a lot of load. Professional manufacturers of rolling mills believe that, for example, during the rolling process, the rolls will be subjected to rolling pressure from hydraulic equipment at both ends, and the reaction force generated when the rolled piece is deformed will also bear the alternating heat and cold. load etc.