Optimised rolling process at Outokumpu thanks to LAP Laser

The Finnish steel giant, Outokumpu, installed an innovative laser measuring system from LAP in a research project to improve the production process for slabs. With the system specially adapted to the demands, the warpage can already be taken into account during the production process. That enables near-net-shape production and reduces costly refinishing.The Finnish steel giant, Outokumpu, installed an innovative laser measuring system from LAP in a research project to improve the production process for slabs. With the system specially adapted to the demands, the warpage can already be taken into account during the production process. That enables near-net-shape production and reduces costly refinishing.

The basis for the success of the Outokumpu steel company is its market and customer orientation, with the focus on the needs, demands and challenges of the customers and markets. The group’s whole corporate policy is oriented to strengthening and expanding its position as one of the world’s leading producers of special steels. Outokumpu safeguards its competitiveness through research and development in applications and technology. Outokumpu continuously improves the production processes.

In a current research project, the Finnish company is investigating the possibilities of near-net-shape production. The steel company was therefore looking for a measuring system that provides reliable data despite the typical ambient conditions in a melting shop of near-net-shape production for semi finished products (slabs) before using them in next production step at hot rolling.

Outokumpu now works even more precisely
 One thing is clear already: The use of the LAP measuring system has significantly improved compliance with the dimensional tolerances. This improvement is not yet quantifiable, however, as further data have to be collected and evaluated before a final evaluation can take place. It has already been discovered, however, that the measuring system is suitable for operation in a melting shop without reservation, since despite the rough environment, it operates dependably and provides reliable values with high precision.

"With the findings from the current research project, we can already manufacture to closer tolerances. As soon as we have evaluated all the data and can detect warpage trends at a very early stage, we can optimise the production process still further," says Marko Petäjäjärvi, Project Manager at Outokumpu.

The investment in the optical measuring system from LAP has already proved to be successful beyond a doubt. The close cooperation between Outokumpu and LAP led to a short installation period and a sturdy system. Just four months passed between the decision in favour of the measuring system in October 2009 and the commissioning.

 Challenging research goal, including precise determination of temperature distribution, right cut to length, width and shape of edge profile.
The laser measuring system is installed immediately downline of the continuous caster where it has to not only withstand but also accurately measure temperatures up to 900°C. Furthermore, it has to measure the width of the slabs of between 800 and 1,700 millimetres as well as the length of the between 2 and 15 metre long semi-finished products and the thickness that is set to 170 millimetres. At a roller conveyor line speed of 30 metres per minute, however, the measuring system has to do even more. Outokumpu requires reliable measurement of the whole shape (thickness, width, length, edge profile, camber) of every slab. With these exact dimensions and the specific density of the respective alloy, the exact weight can be calculated in the next step without the semi-finished products having to be weighed. 

For the research project the company needed a measuring system that also determines the precise distribution of the temperature at the flanks of the slabs. The Finnish engineers planned to compare the temperature distribution of the slabs downstream of the continuous caster with the warpage and change in shape of the cold slabs. From this comparison they hoped to learn more about the relationship between warpage and temperature distribution.

The concrete goal of the research project was ultimately to optimise the downline rolling process on the basis of these data. The engineers can control the rolling process very precisely on the ultra-modern rolling lines. With the data from the project, they wish to influence the rolling process in such a way that the warpage due to temperature is more or less eliminated. That allows near-net-shape slabs, which are a basic requirement for as well near-net-shape production of finished products like coils and strips. Beneficially the steel company can do away with costly refinishing.

Scanning laser sensors provide exact measurement data
 Outokumpu relied on the vast experience of LAP from Lüneburg and invested in an innovative LAP system that provides reliable values for the whole profile inline. LAP has been producing laser-based systems for contact-free measurement of distance, width, thickness, length, diameter, contour and flatness for 25 years. The LAP engineers know the conditions under which the measuring systems have to operate very well. They know that mechanical stability, resistance to vibrations and soiling, thermal insulation, independent cooling systems and easy maintenance contribute just as much to the performance of a measuring system as the individual sensor.

The scanning laser sensors from the LAP ANTARIS Series provide precise measurement data even with large measurement distances, and are particularly suitable for measuring hot or glowing materials. This allows them to be installed at a safe distance where the thermal load is reduced and the risk of collisions is ruled out. The lens system is continuously flushed with filtered air, thus preventing soiling and at the same time cooling the protective housing of the lens system.

Tailor-made laser triangulation method
The ANTARIS sensors employed at Outokumpu operate using the triangulation method: A laser beam is reflected at the surface of the measured object and projected via a lens and passive reflector onto a light-sensitive line camera. Depending on the distance of the measured object, the position of the light spot changes. From this the signal processor calculates the distance between the sensor and the surface of the slabs.

 In order to meet the specific demands of the Finnish steel producer and also determine the exact edge profile, LAP extended the regular width measurement with ANTARIS SCAN sensors to provide a two-dimensional measurement. Two additional sensors were installed alongside the sensor for the width measurement. This 3 + 1 arrangement allows convexities and concavities to be detected even when the slabs roll through the measuring device tilted or at an angle

LAP has oriented the vertical scanning range and the scanning frequency to the nominal thickness and the position of the slabs on the roller table. The measuring specialist has installed an automatic system for this which detects the thickness and position of the material independently. The system adjusts automatically so that the glowing slabs can be best scanned. In this way the scanning range follows the material even in the event of vertical movement or with extreme curvature.

The sensors pass on the collected measurement data to a PC which filters the data and calculates the dimensions in real-time. A further PC visualises the width as a line diagram and the edge profile with three coloured lines over the length of the slab on a monitor. The length of the slabs is determined using light barriers and a further ANTARIS SCAN sensor and output as a numerical value.

Your Press Contact

    Thomas Armbruster

    Tel.: +49 (0)4131 951195
    Fax: +49 (0)4131 951196

    LAP GmbH
    Laser Applikationen
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    21337 Lüneburg

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