Development of High-Accuracy Control System for Hot Strip Mill

Abstract NKK Keihin Works has developed a high accuracy control system for finishing mill in hot strip mill which include thickness control and crown control. To obtain the high accuracy control, the hydaulic screw down and pair cross &shiftlill is derived, and at the same the new setup model for thickness and crown has been developed. The new setup model consist of both thickness control, which include gauge meter model, deformation resistance estimation and temperature estimation, and crown control. To achieve high precision model, physical phenoena are described as possible as exactly, and also applied to on-line computer system. Consequently, ± 50μ m on-gauge rate has achieved lore than 99% in thickness control and the accuracy in terms of strip crown control also has achieved σ = 11 μ m.