On-Line Real Time Surface Inspection System for a Tin Coating Line

Abstract

At Hoogovens Steelworks in IJmuiden, an on-line real time surface inspection system has been installed.The inspection system has been based on a 2048 elements line scan camera, a 20 MHzimage processor, a colour monitor, an operators panel, a video display unit (VDU) and a printer. The system can present real time monitor images of the material that has to be inspected, in a strobe mode. This strobe mode can be stopped manually, whenever a certain pushbutton on the operators panel is pressed or automatically, as soonas a defect matches certain selectable limit characteristics.The monitor image can show a part of the strip with a length of 435 mm using the highest resolution. Each pixel on the monitor will then represent a surface on the steel strip of 0.85 * 0.6 mm2.The system is capable of detecting much smaller defects, depending on the intensity change due to the defect.The final aim of this project is to obtain an on-line real time classification system able to classify at least 50 different defects.The benefits of this system over the inspection without additional equipment is:.-speed independent detection-objective on-line real time detection and at a later stage classification-possibility to detect and get rid of defects made in the tinning line at an early stage.