With the new four-high stand, VDM will now be able to produce sheet with even tighter geometric tolerances and process higher piece weights.

"The term 'four-high stand' refers to a rolling stand with a typical basic structure, consisting of two driven work rolls and two back-up rolls. During the investment project, our rolling mill has been brought into line with the state of technology. With our new rolling mill, we shall be able to respond even better to our customers' needs in terms of product design and quality," explains Dr. Franz-Josef Wahlers, Chief Technical Officer of Outokumpu VDM.

Outokumpu VDM has invested almost EUR 35 million in Siegen. Two new rolling stands with a modern hydraulic screw-down mechanism and a roll bending system have been installed. The new unit is designed for an accumulated rolling force of 6,000 tons. The thickness range has been extended upward. In addition, it will now be possible to process up to 60 percent larger slabs. The new hydraulics and control ensure even tighter sheet thickness tolerances, both length- and crosswise. To optimize the metal surface, a height-adjustable scale scrubber has been integrated.

Standstill in the summer

"Production was brought to a standstill for five weeks this summer. The new hot rolling stand went into operation in mid-August. For the first ten rolled pieces, stainless steels were used to test all the processes and movements in the stand. We have been processing customer orders again since the second week of commissioning," explains Hanno Gerich, Plant Manager at the Siegen and Altena locations. The shutdown was accomplished in this short period because it was possible to largely use the existing foundation beds, so no time had to be allowed for drying.

The mill in Siegen mainly rolls sheet of particularly hard and difficult-to-process metals, including high-temperature and extremely corrosion-resistant nickel and titanium alloys. These are employed in the production of highly stressed components in mechanical and plant engineering, aerospace and the chemical process industry. The mill rolls sheet to a thickness of 3.0 millimeters – which makes it  very unique.

Simulation of the production process

Before installation, the rolling stand was fully preassembled at the SMS Siemag production shop in Hilchenbach. This is where key components were scrutinized and the stand function-tested. The entire automation gear was set up in the SMS Siemag test bay in order to simulate the production process and optimize the automation functions prior to installation at the mill.

A major challenge during the overhaul was the limited space. The new stand was to be installed with as little change to the surroundings as possible and by re-using a large number of parts in their original positions. Thanks to the preassembly of the entire stand inclusive of the stand platform, it was possible to ensure that final assembly took place without time-consuming downstream modifications. "We're proud of being able to successfully complete the modernization project with only five weeks for the turnaround – a big thank-you to everyone involved! And special thanks are owed to the supervisory authorities that cooperatively supported us throughout planning and implementation," stresses Dr. Jan Jürging, Plant Manager at the Siegen location.

More information:
Philipp Verbnik
Marketing & Regional Management,
Outokumpu VDM GmbH
Telefon: +49 2392 55 2274
E-Mail: Philipp.Verbnik@outokumpu.com