Causes and methods of alleviating variations in the shading of tin plate during temper rolling

The Ispat Karmet metallurgical plant has made a study of the reasons for the formation of “ring-shaped bands” on the backup rolls of its temper-rolling mill and the associated variation in the shading of tin plate rolled on the mill. The plant examined the interactions that take place in the stands of the mill and used the findings to determine the mechanism responsible for the formation of the above-mentioned defects. A method of alleviating these problems was also developed. Improvements that were introduced have led to a fivefold increase in the amount of time that the backup rolls of stand No. 2 remain in service without the formation of the ring-shaped bands. The measures that were adopted have also signficantly reduced the intensity of the variable shading on the tin plate.     

New System for Changing the Work Rolls in the First Stand of Temper-Rolling Mills

ISPAT-Karmet has developed a new roll-changing system for the work rolls of the first stand of temper-rolling mills. In the system, the convex work rolls are interchanged with the cylindrical work rolls every day for the duration of the campaign of the backup rolls. Use of the system has reduced the wear of the backup rolls from 0.82 to 0.16 mm and brought a threefold reduction in the rate of rejection of tin plate for excessive curvature.