Shape Measurement of Steel Strips Using a Laser-Based Three-Dimensional Reconstruction Technique

Quality control is of utmost importance in the metal industry. It requires online measurement and inspection systems which provide precise feedback to closed-loop controllers in industrial facilities. In rolled products, shape is one of the main quality criteria. In this work a low-cost, real-time 3D shape measurement system for long, flat-rolled products based on laser triangulation is proposed. The system provides online measurements of two geometrical features of the shape of rolled products: flatness and width. The proposed system is based on 3D surface reconstruction of rolled products with which flatness can be measured accurately and continuously across the whole width of the strip. Three-dimensional surface reconstruction provides highly width accurate measurements not only of flat products, as do most other systems, but of non-flat products. The accuracy of the laser extraction method used to reconstruct the surface of the rolled products is evaluated, as well as the online performance of the system.