Features of technological schemes and equipment for the production of thin strips on hot strip mill

The purpose of the work is to determine rational schemes for their production by analyzing the technological and design parameters of a number of broadband mills that roll hot-rolled strips less than 2,0 mm thick. It is shown that at present there is a constant increase in the production of extremely thin hot-rolled strips (0,8-1,5 mm thick), which can be used instead of more expensive (by $ 20-30 per ton) cold-rolled strips. The development of the production of hot-rolled strips of such a thickness is limited by a number of problems, in particular, the low temperature of the end of rolling (760-820 °C), which leads to a significant decrease in the ductility of the rolled stock; limiting the rolling filling speed, which does not allow increasing the temperature of the end of rolling the complexity of controlling the cross-sectional profile and flatness of the strips. Using mathematical modeling, it was found that the strip thickness and rolling speed have the greatest influence on the temperature of the end of rolling. The thickness and temperature of the rolls at the entrance to the finishing group of stands have a lesser effect. A decrease in the number of stands in the finishing group increases the temperature of the end of rolling at a constant thickness of the rolls, but when the thickness of the rolls changes in accordance with the number of stands, the effect is significantly reduced. The most favorable technological parameters for the production of extra-thin hot-rolled strips are provided by casting and rolling units, which are characterized, in comparison with broad-strip mills, as a rule, by a greater thickness and temperature of the rolls (or continuously cast slabs) and a smaller number of stands. An increase in the thickness of billets (slabs) requires an increase in the permissible values of the energy-power parameters of rolling, as well as the use of special solutions that will ensure minimal heat loss by the rolls before entering the finishing group of stands. Calculations show that, based on the reliable maximum refueling speed of hotrolled strips (10-11.5 m / s) achieved in the industry, the minimum thickness of strips with high plastic characteristics is: for broad-strip mills - 1.9-2.0 mm; for casting and rolling units, depending on their type - 1.3-1.6 mm.