Rolling Mill Control for Decoupled Strip Contour and Flatness
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Solution Overview
Problem
Existing roll train systems struggle to independently adjust metal strip contour and flatness, leading to low-frequency vibrations and slow contour correction, as both parameters are intertwined and controlled sequentially, with flatness control affecting contour measurements.
Innovation Solution
An operating method for a roll train where the control device decouples contour and flatness adjustments by considering downstream and upstream changes, using delayed control variables and separate controllers for each roll stand to independently control actuators, allowing for real-time adjustments and reduced flatness changes upstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If both contour control and flatness control act on the same roll stand, then both parameters can be controlled at the same location, but contour and flatness cannot be adjusted independently due to their interdependence through the rolling gap shape
Solution Approach 1:
The control system is segmented into separate controllers: one dedicated to contour control and another to flatness control. Each controller independently manages its respective parameter by actuating specific actuators on appropriate roll stands, eliminating the interference that occurs when both controls act on the same roll stand.
Solution Approach 2:
The patent introduces an intermediary control architecture where the contour controller and flatness controller communicate through a coordinated control system. This intermediary layer enables independent adjustment of both parameters by distributing control commands to different roll stands while maintaining overall system coordination.
2Manufacturing precision
If contour control acts on upstream roll stands to enable material cross flow, then contour can be adjusted, but correction speed is slow due to the distance between the controlled roll stand and measurement location
Solution Approach 1:
The control system performs preliminary adjustments on upstream roll stands to prepare the metal strip for final contour correction. By anticipating the required contour changes and applying corrections progressively through multiple roll stands, the system achieves both accurate contour adjustment and faster overall correction speed.
Solution Approach 2:
The patent implements continuous contour correction across multiple roll stands rather than relying on a single distant control point. This continuous action along the rolling path maintains constant correction capability, significantly improving response speed while preserving the material cross-flow effect needed for effective contour control.
3Manufacturing precision
If flatness control operates with short dead time, then flatness can be controlled effectively, but the measurement signal for contour control is repeatedly falsified
Solution Approach 1:
The measurement and control system is segmented into independent channels: flatness measurement and contour measurement each have dedicated sensors and processing paths. This segmentation allows flatness control to operate with short dead time using its own measurement channel without interfering with contour measurement accuracy.
Solution Approach 2:
The patent separates the control dimensions by assigning different roll stands to different control functions. Contour control acts on upstream roll stands while flatness control acts on downstream roll stands, creating spatial separation that eliminates signal interference while maintaining effective control in both dimensions.
Data Source
AI summary
A control device of the rolling mill line controls actuators of a downstream and an upstream roll stand. The control device determines control variables for the actuators of the upstream roll stand while taking into consideration a flatness change to be carried out and additionally taking into consideration a contour change to be carried out and controls the actuators of the upstream roll stand accordingly. The control device determines control variables for the actuators of the downstream roll stand while taking into consideration the contour change to be performed but without taking into consideration the flatness change to be performed and controls the actuators of the downstream roll stand accordingly. The control device outputs the control variables to the actuators of the downstream roll stand with a delay of a transport time, relative to the corresponding control variables for the actuators of the upstream roll stand.