Energy Saving in Rolling Process of the Three Quarters Continuous Type Hot Strip Mill

The total length of the rolling mill line and the state of slab temperature change are analytically discussed by means of a mathematical model for two different types o f hot strip mill: the quasi continuous type, which is usually called the three quarters continuous type, and the quasi continuous tandem type in which the last rougher and the finishing train are connected in tandem for shortening the rolling mill line.In the quasi continuous tandem type, the total length in the roughing process can be shortened to 56% compared with the case of the normal quasi continuous type. For a given reheating temperature, the slab temperature at the entrance of the first finisher remains much higher in the quasi continuous tandem type so that the reheating temperature can be lowered. Consequently, the quasi continuous tandem type is considered to be effective not only for the shortening of the length in a rolling mill line, but also for the energy saving in the rolling process.Finally, it is suggested on the basis of mill layout that the semi continuous type hot strip mill, which is insufficient in the rolling capacity and consumes a relatively large quantity of energy, can be remolded into the quasi continuous tandem type with comparative ease.