Impact speed drop compensation procedure for a new layout wire rod mill

This paper presents a new architecture of the final section of the production line of a wire rod mill (WRM). Such final section consists of three stands that are powered by one 5400 kW and two 2400 kW motors, respectively. The motors are supplied by one 9 MVA and two 6 MVA medium voltage NPC inverters, all in the AFE (active front-end) configuration. The authors briefly describe the new mechanical layout and its functional characteristics, highlighting its advantages in terms of product quality and productivity. They also present the main tasks of the automation system, so devised to insure dimensional accuracy of the product both under static and dynamic conditions. Finally, the authors give details of the new algorithm studied and implemented as a special function, added to the standard drive control software and devised to compensate the dynamic speed drop occurring at the impact of the billet entering the stand. By this algorithm the maximum instantaneous impact speed drop is reduced to 0.2% of the maximum rolling speed. Due to the very high rod output speed, the performance of the line production in terms of product quality is directly related to the efficiency of the new algorithm. The paper provides also information about the main results and the performance level attained by the production line.