Laser measurement systems for plate mills - flatness, plate geometry, thickness and length measurement at Baoshan Iron & Steel Group, Co. Ltd., China

Thickness and length measurement at cut-to-length line.

As a final step in the production process, thickness and length of the finished plates are assessed for documentation and archiving. This allows the capability to prove compliance of the specifications at any time.

The thickness of the finished plates is measured optically by laser triangulation sensors located above and below the plate.
Each sensor measures the distance to the respective plate surface, and the thickness is calculated as the difference of the fixed sensor-to-sensor distance and the measured distances to the plate surfaces. Plate thickness is measured in 3 tracks. Transversal positioning of all sensors allows optimal location of the measurement tracks for any given material width. Having this capability, even slitted plates can be measured.
The thickness profiles of the plates are displayed on a monitor, with color-coded highlighting of tolerance violations.

A Laser Doppler gauge is used to monitor the length of the plates. Additional laser photocells are used to trigger the length measurement, further enhancing measurement accuracy.