Dynamic loads reduction of mechanical and electrical equipment of the hot rolling mill roughing train

Abstract

The authors carried out the analysis of electric drives dynamic loads of horizontal and vertical rolling stands of the continuous roughing train of “Magnitogorsk Iron and Steel Plant” OJSC 2000 rolling mill. The analysis confirmed that considerable dynamic loads act on the electric drives of horizontal and vertical stands during strip take-in and proved that it is necessary to develop new control methods and algorithms reducing dynamic loads on the stand electrical and mechanical equipment. As a part of the study the authors found out the main reasons causing dynamic loads increase during strip take-in in the rolls of the 4^th – 6^th stands of the continuous train: the error of rolls linear speeds of adjacent horizontal and vertical stands; the presence of the uncontrolled steady-state error in the single-integrating speed control system after the strip take-in and the instantaneous dam formed in the strip during take-in in the subsequent stand. To eliminate the speed error of horizontal and vertical rolls the research group offered the principle of automatic corrective adjustment of strip reduction in horizontal and vertical rolls and on the basis of this principle a new method of rolling control in the rolling mill continuous train was developed. In order to eliminate the steady-state error in the speed and strip dam the authors offered a method of speed control compensating the steady-state speed error. The implementation of this method will make it possible to set up a more accurate relationship between rolls speed in the vertical and horizontal stands before the strip take-in thus eliminating shocks and reducing dynamic loads on the mechanical and electrical equipment.