Rolling Method for Decreasing Cracks on the Roll and Surface Defects on Billet’s Corner by ‘Switch-Over On-Off’ Operation of Water-Cooling

by KOSUKE TSUJIMURA

Publisher - Sumitomo Metal Industries, Ltd.

Category - General Novel

When steel is rolled after the breakdown mill (also known as box rolling), it is difficult for the dia-square rolling method to finish the process without any surface defects (like cracks on the corners of the billets) occurring. Typically, the steel should be free-cutting and silicon-killed. However, because water cooling is necessary for hot working roll, the corners of the billets encounter less hot workability and this is when defects tend to occur. One way of resolving this problem is to adopt a so-called ‘switch-over/on-off operation’ that automatically controls water-cooling. If the roll stops as a result of water-cooling during rolling, or as a result of hot metal and rolling current detection, heat cracks on the roll (as well cracks at the billet’s corner) should decrease.

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