Modeling the dependence of the curvature of the front end of a thin slab on rolling conditions of steel

The desire to increase the rolling speed and productivity of rolling mills, as well as to improve the quality of products and reduce their cost requires solving the problem of the stability of the movement of sheet metal between the stands of a continuous group. In the first passes, it sis strived to increase single reductions, but an increase in the elongation ratios and grip angles raises the risk of curvature of the front end of the strip, complicating the grip of the strip by the rolls of the next stand. The risks of emergency braking and stopping the strip between the stands of a continuous group limit the single reductions, rolling speed, productivity of the mill or casting and rolling complex (CRC). Using the example of the operating conditions of the 1950 mill, the first CRC in Russia of the OMK company (Vyksa), the first rolling operations of carbon steel in the zone of twin roughing stands are simulated. The study is based on finite element 3D modeling in the QForm software package. The output characteristic is the value of strip curvature 1/R (R is the radius of curvature of the strip) after the slab is reduced by edger rolls and exits the horizontal rolls of the first stand. The wear process of the rolls is taken into account. Of the possible causes of curvature during hot rolling, special attention is paid to the following factors: difference in “friction factors” (QForm term) of rolls of one pair; difference in roll diameters; difference in horizontal roll speeds (there is no such function on the 1950 mill, the roll drive is common). Examples of technical means for monitoring strip curvature during rolling under production conditions are shown, the capabilities and practical significance of which increase in the context of digitalization of production. Safe increase in single reductions and rolling speed in continuous groups of rolling mills will reduce the temperature wedge, make it possible to obtain thinner hot-rolled sheet and improve the quality of rolled products. The use of curvature models based on the accumulated data base will allow predicting the moment of emergency strip locking, choosing the optimal moment for changing rolls, identifying methods for process control and increasing production stability.