Rolling Mill Control Method for Strip Gauge and Profile
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Solution Overview
Problem
Current control methods for rolling mill trains fail to effectively account for temperature variations across the width and length of strips during rolling, leading to malfunctions such as roll stand reactions, gauge, profile, and flatness defects, as they cannot utilize selective roll cooling or adapt to asymmetries in material strength.
Innovation Solution
A control method that predicts strip section temperatures using a prediction horizon and adjusts the roll gap profile by influencing roll bending, shifting, and cooling, incorporating a roll stand model and rolling force model to optimize the roll gap profile and account for material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If automatic gauge control (AGC) is used to compensate for roll stand reaction, then gauge deviations are corrected, but temperature variations across the strip width cannot be detected or compensated
Solution Approach 1:
The system performs preliminary action by predicting the temperature distribution across the strip width and longitudinal direction before rolling occurs. This prediction is used to pre-calculate compensatory measures for roll stand reactions, enabling proactive compensation rather than reactive correction after defects occur.
Solution Approach 2:
A mathematical model acts as an intermediary between measured temperatures and roll stand reactions. The model calculates the relationship between temperature distribution and rolling forces, enabling indirect measurement and compensation of temperature effects that cannot be directly sensed by conventional gauges.
2Productivity
If feed-forward control using rolling force measurement in the first roll stand is implemented, then remaining stands can be controlled proactively, but single-stand trains cannot utilize this method
Solution Approach 1:
The mathematical model serves as a universal intermediary that can process temperature data and predict roll stand reactions for any mill configuration. This allows the system to adapt to both multi-stand and single-stand trains, as well as continuous casting and rolling plants, without requiring fundamental changes to the control methodology.
3Manufacturing precision
If selective roll cooling is not utilized, then roll crown adaptation is limited, but when actuating elements for roll gap shape are at their limits, temperature variations cannot be compensated
Solution Approach 1:
The system performs preliminary action by predicting temperature distribution and calculating required selective roll cooling patterns before the rolling process. This allows the roll cooling system to be proactively adjusted to compensate for anticipated temperature variations, even when other actuating elements are at their adjustment limits.
4Reliability
If temperature variations in the strip are not compensated, then rolling force variations occur, but compensation systems increase device complexity
Solution Approach 1:
A mathematical model acts as a software-based intermediary that calculates temperature-compensation relationships without requiring additional physical sensors or complex hardware. The model processes existing temperature measurement data and generates control signals, achieving compensation through information processing rather than physical system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise control of the roll gap profile, reducing defects by anticipating and adapting to temperature and material property changes, enabling better load redistribution between roll stands and improving rolling mill efficiency.
Implementation Method 1
adjusting a profile of a roll gap formed by work rolls of a first roll stand by influencing roll bending
Implementation Method 2
adjusting a profile of a roll gap formed by work rolls of a first roll stand by influencing roll shifting
Implementation Method 3
selective roll cooling in order to adapt the roll crown
Implementation Method 4
selective roll cooling in order to adapt the roll crown
Data Source
AI summary
A current temperature is ascertained for sections of a strip ahead of a first mill stand. The temperatures of the strip sections are predicted with a prediction horizon corresponding to multiple strip sections, including when each strip section is milled in the first mill stand for which time a nip profile formed by the working rolls is predicted. A control parameter for milling a specific strip section in the first mill stand is ascertained for controlling a control device of the first mill stand. A manipulated variable curve for the control device, influencing the nip profile of a nip formed by working rolls of the first mill stand, is set for the prediction horizon and optimized for the predicted nip profile and a desired profile. The current value of the optimized manipulated variable curve corresponds to the control parameter which is fed to the control device as the manipulated variable.