Flatness inspection is a fundamental issue in the quality control performed during the manufacturing of steel strips. The quality requirements for such products have been increasing for the last years, and nowadays new flatness measurement techniques are needed to fullfill this requirements. This paper introduces the concept of flatness and the most common flatness metrics used in the industry. Our work focuses on the application of the well-known laser ranging techniques in the design, construction and test of a flatness measurement and inspection system capable of aquiring the true shape of a steel strip in real time and calculating its flatness indexes so they can be used in the quality inspection of the steel products.
For testing the system, a steel strip simulator has been constructed that allows us to generate any possible flatness defect with a known magnitude and measure it with our flatness measurement system. The agreement between the real magnitude of the defects and the measured ones is better than 4.5 I-Units in the range of 0 to 100 I-Units. The system prototype has been installed in the conditioning line of Aceralia (steel manufacturer) to test the proposed solution under real industrial conditions.