Reasons why high-speed steel sink rolls are cooled in use
High-speed steel material has a large amount of thermal expansion, and poor roll temperature distribution is prone to uneven thermal expansion and abnormal shedding of the oxide film, which affects the thermal crown and roll gap accuracy of sink rolls. The key factor affecting the oxide film and thermal crown of high-speed steel sink rolls is the surface temperature of sink rolls.
Therefore, the ideal cooling method of sink rolls and shortening the time that the sink roll surface is in a high temperature state are important means to control the thickness of the oxide film on the sink roll surface, control the thermal crown, and reduce thermal cracks. During the hot rolling process, the instantaneous contact temperature of sink rolls is 600℃~750℃, and the temperature of sink rolls exceeds 50℃. prevent further oxidation.
After the sink rolls pass through the instantaneous high temperature contact zone, the rapid operation in a 100% water-cooled environment is conducive to the formation of Fe3O4 oxide films with the best protective properties. Increasing the cooling water volume on the outlet side, reducing the water volume on the inlet side, and reducing the height of the water cutting plate can enhance the cooling effect of sink rolls, but there are still problems of high roll surface temperature and uneven distribution.
The above is the reason why the high-speed steel sink rolls adopt the cooling method in use. By optimizing the cooling water distribution of the sink rolls and increasing the amount of cooling water in the middle of the sink rolls, the roll surface temperature can be significantly reduced and the temperature distribution uniformity can be improved.
The above is the reason why the high-speed steel submerged roller adopts the cooling method in use. By optimizing the cooling water distribution of the submerged roller and increasing the amount of cooling water in the middle of the submerged roller, the temperature of the roller surface can be significantly reduced and the uniformity of the temperature distribution can be improved.
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