EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

In 2014, SMS group received the order to modernize Severstal’s fifty years old four stand tandem mill (TCM) in Cherepovets. Main aims are to increase the capacity and strip quality as well as to prepare the mill for a later coupling to a new pickling line (PL). Additionally reduced off-gauge length, raised availability and increased automation rate are required to improve the yield. In a follow up to previous papers, this presentation demonstrates the project from the initial situation, the design, the shut-down, the start-up and the achieved benefits from Severstal’s point of view. The main subjects of the revamp project are stronger mill stands #1 - #4 with a new AC drive system at the 1st mill stand, full automatic roll change devices and a reduction of the gap time between two coils. New actuators are implemented in the mill stands (hydraulic adjusting systems, work roll bending, CVC® plus shifting), along with 2 SMS X-Shape® measurements. Furthermore a new field excitation control of the existing DC drives (Ward Leonard drive trains) and the new drive of mill stand #1 improve the mill’s dynamic behavior. Advanced thickness and speed/tension control along with integrated flatness control achieve excellent geometrical product quality. A model-based L2 setup system provides reliable parameters for an extended product range; it also enables the threading assistant function to ensure automatic strip threading with minimum off-gauge length. State-of-the-art automation functions ensure smooth rolling and reliable product quality on the highest level. The paper will demonstrate the most interesting technical aspects of mechanics and automation, the challenges of project execution including shut down, and how they were managed by joint efforts of Severstal and SMS group. The achieved production and quality results as part of Severstal’s prime flat steel production are presented, proving the business impact of Severstal’s investment.