Pickling lines remove any rust and scale from hot-rolled strips. The process is based on passing the strip through hydrochloric acid baths to dissolve the surface oxides. The coils passed through pickling line have a typical weight of 25MT with thickness varying from 1.6mm to 3.2mm and width 700-1300mm. The coil moves at a speed between 80 metre per minute (mpm) to 90mpm.
The quality of the pickled coil is very important for further processing. There are various types of edge defects, some being part of the incoming coil and rest developed during the pickling process. These defects need to be detected at the pickling line and an appropriate decision needs to be initiated by the quality inspectors. At present, inspector is posted at the exit (near re-coiler) 24X7, who observes the pickled Coil and takes decision for rework, reject or pass as shown in figure 1. Since we are dependent only on manual visual inspection, there is chance that some defect can go unnoticed. Thus, an alternative to manual inspection is being sought to inspect both the edges of the complete coil for defects such as edge crack, busted edge, chipped edge etc as shown in figure 2.
The solution must meet the following requirements