Hot Rolling Mill Target Sensitivity via Independent Offset Control
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Solution Overview
Problem
Existing methods for determining the sensitivity of target sizes in hot rolling trains are prone to systematic errors, leading to inaccurate adjustments in operating values, especially when primary data changes or when trying to achieve different target material properties, resulting in incorrect corrections and increased material scatter.
Innovation Solution
The method involves changing the provisional target values for special target variables by offsets that are independent of primary data and other target variables, allowing for stochastic independence of operating value variations, enabling the determination of sensitivity based on mean operating values and final target values for specific target variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control device adopts the provisional target value unchanged as the final target value for all target variables, then the control system is simple and easy to operate, but systematic errors accumulate leading to inaccurate sensitivity determination and increased material scatter
Solution Approach 1:
The patent segments target variables into two categories: normal target variables (where provisional values are adopted unchanged) and special target variables (where provisional values are changed by offsets). This segmentation allows the system to maintain simplicity for most variables while applying corrective adjustments only where systematic errors are expected, thereby resolving the contradiction between operational simplicity and manufacturing precision.
2Adaptability or versatility
If the control device adjusts operating values based on accumulated systematic errors from previous treatments, then the control adapts to changing conditions, but the sensitivity determination becomes inaccurate due to correlated errors
Solution Approach 1:
The patent introduces an intermediary mechanism (offsets for special target variables) that decouples the adaptation function from the sensitivity determination function. By adding random offsets to special target variables, the system enables accurate sensitivity measurement (by breaking error correlations) while still maintaining adaptability through the overall control loop that processes both normal and special target variables.
3Productivity
If the control device uses model-based determination of operating values to achieve target variables, then the process is efficient and productive, but systematic errors in the model lead to incorrect corrections
Solution Approach 1:
The patent implements a feedback mechanism where the actual achievement of target variables is measured and compared with the desired values. For special target variables, offsets are applied to create variation that allows the system to learn and correct systematic model errors over time, while maintaining high productivity through efficient model-based control for normal operations.
Data Source
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AI summary
A control device (6) for a section of a hot rolling mill is supplied with respective primary data (PD) for a plurality of rolling materials and respective preliminary target values (Z*) for the target variables of the respective rolling material. The respective primary data (PD) describes the respective rolling material before being supplied to the section of the hot rolling mill. The respective preliminary target values (Z*) of the target variables describe a desired target state of the respective rolling material after passing through the section of the hot rolling mill. At least one of the target variables is a particular target variable, whereby the control device (6) determines a respective final target value in such a way that it changes the respective preliminary target value (Z*) by a respective offset. The respective offset is determined independently of the primary data (PD) and the other particular target variables and the normal target variables for the respective rolling material. It is also independent of the operating values of the hot rolling mill determined for handling the respective rolling material. The other target variables are normal target variables, whereby the control device (6) accepts the respective preliminary target value (Z*) unchanged as the respective final target value. In relation to the respective particular target variable, the offsets have multiple different values when all the rolling materials are viewed as a whole. The control device (6) determines operating values (A) for the section of the hot rolling mill in such a way that, after passing through the section of the hot rolling mill, the respective rolling material achieves the final target values of the target variables as far as possible, and operates the section of the hot rolling mill when handling the respective rolling material according to the determined operating values (A).