Rolling of steel in Hot Strip Mill Dec03

Rolling of steel in Hot Strip Mill...

Rolling of steel in Hot Strip Mill Hot strip mills in these days are either conventional hot strip mills or strip mills for rolling thin slabs. The primary function of the conventional hot strip mill (HSM) is to reheat the semi-finished steel slabs (rolled or continuously cast) to the rolling temperatures and then to roll them thinner and longer through a series of rolling mill stands driven by large motors and finally coiling up the lengthened steel sheet for its easy handling and transport. Coils are produced with an inside diameter of 750 mm on the coilers, with  an outside diameter of up to 2400 mm and with the limitations of coil weight up to 220 kg per cm width. The hot strip mill supplies coils for cold rolling mill, strip shearing and slitting units as well as a finished product for shipment directly to the customers. Most material is transported out of the mill area by an automated coil handling system to the storage aisle. Attributes imparted to the strip by the hot rolled strip mill include surface quality, thickness, width, and flatness control as well as strip profile. Rolling of steel slabs in hot strip mill consists of several sub-processes and at the end of them the final product ‘hot rolled coil’ is produced. The main sub-processes are (i) heating of steel slabs in the reheating furnace, (ii) descaling of the heated slab and its sizing in sizing press, (iii) rolling in the roughing mill and secondary descaling, (iv) rolling in the finishing mill, (v) control cooling of the hot rolled strip and (vi) coiling of the rolled strip. Reheating of the slab Critical to the hot strip mill is the reheating furnace. Modern hot strip mills are equipped with state of...