Rolling Mill Profile Control for Stable Box-Profile Strip
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Solution Overview
Problem
The challenge in rolling metal strips is maintaining a stable thickness profile to prevent concave contours, which can lead to material loss, plant damage, and process instability, especially when producing box profiles with tight tolerances.
Innovation Solution
The method involves determining setpoint values for rolling stands to approximate an ideal contour course primarily within an initial center area, accepting unavoidable edge drops, and using a control device to adjust initial area boundaries based on actual variables and target profiles, ensuring convexity to prevent concave contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the contour course is forced to be very flat to achieve box profiles with tight tolerances, then the thickness uniformity across the width is improved, but the rolling process becomes unstable and may become concave
Solution Approach 1:
The patent applies local quality by differentiating the control approach for the center area versus edge areas of the rolled product. The control device determines setpoint values specifically for the initial center area to achieve a flat contour course (box profile), while accepting that edge areas will have unavoidable thickness drops. This localized control strategy allows tight tolerances in the critical center region without forcing the entire width, thereby maintaining process stability.
Solution Approach 2:
The patent segments the width of the rolled product into different control zones: an initial center area where the contour course is actively controlled to be flat, and edge areas where thickness variations are accepted. By dividing the control domain, the system can achieve box profiles with consistent thickness in the center without requiring the entire width to meet the same stringent criteria, thus preventing process instability.
2Manufacturing precision
If the desired profile value is reduced to produce box profiles, then the thickness consistency is improved, but the risk of concave contours and process disruption increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively preventing concave contours through controlled thickening in the center area. The control device determines setpoint values that create a convex contour course (positive profile value) in the initial center area, which counteracts the natural tendency toward concavity. This preventive measure ensures that even with tight tolerance requirements, the rolling process remains stable and produces the desired box profile without harmful concave defects.
3Manufacturing precision
If the contour course is strictly controlled across the entire width, then the profile precision is improved, but the device complexity and control difficulty increase
Solution Approach 1:
The patent extracts the critical control requirement from the entire width and applies it only to the initial center area. Instead of controlling the contour course across the full width, the control device focuses exclusively on maintaining a flat contour course in the center region where box profile precision is most critical. This extraction of the control function to a specific zone reduces control complexity while maintaining the necessary profile precision.
Data Source
AI summary
A control device that receives actual variables (I) of a flat rolled product before rolling and target variables (Z) of the rolled product after rolling in a rolling mill. The target variables (Z) include at least one profile value (C) of the rolled product, which relates to a predetermined spacing (a) from the edges of the rolled product. The control device determines an ideal contour shape (ci) on the basis of the target variables (Z). On the basis of the actual variables (I) and the ideal contour shape (ci), the device uses a model of the rolling mill to determine target values (COM) for manipulated variables for the roll stands of the rolling mill. The device transfers the target values (COM) to the roll stands, such that the rolled product is rolled in the rolling mill in consideration of the target values (COM).