Abstract: A certain CVC-6h cold mill installed with many actuators of flatness control, such as work-roll bending, intermediate-roll bending and intermediate-roll shifting could not eliminate the coupled edge and centre wave on the narrow strip. To find the solution, an analysis method based on the efficiency function is established. It describes the mill flatness adjustment characteristic in a set of orthogonal vectors defined as eigenvectors, and judges whether a certain flatness error can be eliminated by the sum of the similarity between these vectors and the error. It is found that the mill is impossible to weaken the flatness error effectively. Considering the actual situation, we make a single-side chamfer on the work-rolls in final stand. This method is applied in industrial production, and the result agrees with our anticipation.

Key words: Cold rolling, Flatness, Roll contour, Similarity