Hot rolling

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Flatness measurement sensors for hot strip mills have been used for a long time and most mills have some kind of flatness/shape measurement today. However, accurate flatness measurement under hot conditions often leads to inaccurate and unreliable results. Strip speed, heat shimmering, cumbersome calibration, water and moist are factors that complicates the measurement.

To overcome this, Shapeline has, in cooperation with SSAB and Sweden´s innovation agency, Vinnova, developed a system for hot band measurement based on laser lines instead of laser points or white light. This has been possible thanks to ShapeCAT, a novel approach based on smart-camera technology developed by Shapeline specifically for flatness measurement. ShapeCAT enables high-speed and high-resolution laser line triangulation and still maintaining excellent accuracy. In addition, the resolution provided enables strip edge-detection which is used to compute strip shape, camber, off-center and width. All in the same sensor.

The heat-shimmering effect is reduced by moving cold air into the measurement field, which drastically improves the accuracy.

The approach is now demonstrated by a full scale installation in a measurement house after the exit of the last roll-stand at SSAB hot strip mill in Borlänge, Sweden. A novel approach for calibration has also been developed and integrated in the measurement house that enables precision calibration under production conditions. This simplifies and shortens installation as well as calibration times drastically.

The concept was presented for the first time by Dr. Pär Kierkegaard, company founder and vice president, on the Rolling 2016 conference in Graz, Austria, in June, 2016.

The paper can be found here.

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Result from measurements.