Multi-modal defect detection of residual oxide scale on cold stainless steel strip

This work presents two initial approaches and a novel technique for the industrial inspection of residual oxide scale on a cold stainless steel strip. The research aims to develop real-time systems to detect 50-mum defects. Initially, a spectrophotometric analysis provides the wavelength regions where differences between stainless steel and residual oxide scale reflectance are highlighted. The multi-modal approach is based on laser techniques that comprise three different strategies to gradually achieve a robust stainless steel industrial inspection through the evaluation of their performance. First, an inspection system based on a single commercial laser has been designed with a dynamic threshold module. In the second approach, the inspection task is accomplished by volatilizing a reduced area of the stainless steel surface with short pulses of a high-power ultraviolet laser and then analyzing the generated plasma with an intensifier camera. The third technique consists of an innovative smart vision system for surface visual inspection based on laser diode diffuse illumination. This vision system can be configured to work with two laser illumination modes: the diffuse coaxial lighting and the diffuse bright-field lighting. These techniques aim to gradually improve surface defect detection of a cold stainless steel strip. Furthermore, some of the results of the defect detection level obtained with each approach are displayed and discussed.

inspección de superficies; óxido residual; lámina fría de acero inoxidable; visión por computador; iluminación coaxial difusa; iluminación difusa de campo luminoso; aplicaciones industriales de visión; surface inspection; residual oxide scale; cold stainless steel strip; machine vision; diffuse coaxial lighting; diffuse bright-field lighting; vision industrial applications

Multi-modal defect detection of residual oxide scale on cold stainless steel strip Articles