26/07/2011

Siemens VAI modernizes hot-rolling mill at Hoesch Hohenlimburg, Germany

In the course of the project, five rolling stands will be completely replaced and two additional stands will be revamped in the finishing mill. The goals of the modernization are to expand the product portfolio and increase the mill yield with a simultaneous further improvement in quality. The project is scheduled for completion by mid-January 2013. The order volume exceeds 20 million euros.

The finishing mill in the medium-wide-strip hot-rolling mill of Hoesch Hohenlimburg is comprised of nine rolling stands, seven of which are 4-high stands. In the course of the modernization project, five of these stands will be exchanged and two additional stands will be revamped with state-of-the-art technologies. All of the stands are being equipped with work-roll shifting devices for the installation of SmartCrown rolls and L-type bending blocks. This allows improved control of strip profile and flatness parameters. Long-stroke cylinders for automatic thickness regulation (hydraulic automatic gauge control/HAGC), cooling systems and position transducers are also being installed in the bending blocks. Backup roll exchanges, which up until now have been executed with the use of an overhead crane, will be carried out after the revamp by means of hydraulic extraction of the backup rolls. The design and engineering took into consideration possible future technological advances. The automation system, currently also being modernized by Siemens, will also be adapted during the course of project to the new rolling mill configuration.

Once the entire project has been completed, the rolling mill will have an annual capacity of 1.35 million tons of medium-wide strip with thicknesses ranging between 150 mm and 720 mm. The achievable strip thicknesses range between 1.3 mm and 16 mm with coil weights of up to 15 tons. The modernized mill will empower Hoesch Hohenlimburg to expand its product spectrum to include new high-strength steel grades. Narrower strip thickness and width tolerances combined with improved flatness and profile will contribute to improved product quality. Because the achievable minimum thickness of high-strength strip can be reduced, the hot-rolled strip product can replace cold-rolled products for a number of applications. Strip steering is also being improved, thus increasing operational safety. The integrated plant concept that is based on carefully matched mechanical, electrical and automation components and systems additionally allows a more flexible setup of rolling schedules and longer rolling sequences. This leads to higher system availability and increased mill yield.

The rolling mill modernization will be carried out in two phases during scheduled mill downtimes. Modernization of two of the operating rolling stands and installation of two new stands is scheduled for the summer of 2012. Installation of the remaining three new rolling stands is foreseen for December 2012. The automation systems in the roughing and finishing lines will be completely modernized on the basis of the Siroll HM platform specially developed for hot-rolling mills. Siemens previously modernized a downcoiler and the cooling line in the medium-strip rolling mill.

Source: Siemens