Centre-line deviation as a measure of camber in steel slabs during unrestricted horizontal rolling

A theoretical analysis of slab motion during camber evolution in unrestricted horizontal rolling is presented. The analysis shows that a linear relationship exists between centre-line deviation (CLD) curvature and outgoing camber, which is a function of ingoing and outgoing slab thickness and ingoing slab camber. An experimental study, undertaken during commercial rolling at the hot stripmill in Port Talbot, is described. CLD data from a stereoscopic width gauge (SWG) and a line scanning pyrometer (LSP) at the exit of the horizontal scale breaker were compared with the measurements of actual outgoing slab camber. The results confirmed the findings of the theoretical analysis and showed that CLD data, once suitably processed, can be used as a measure of camber. The SWG appeared to offer better measurements than the LSP. Incorporating ingoing camber into the model improved the accuracy achieved. Finally, a practical on-line camber measurement technique using SWG CLD data is proposed on the basis of the findings of this study.