Roll Stand Gap Calibration Using In-Line Strip Thickness Feedback
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Solution Overview
Problem
In continuous casting and rolling installations, replacing worn work rolls during operation disrupts productivity due to the need to deactivate the entire roll train, as existing methods cannot calibrate roll stands with metal strips present, leading to frequent downtimes and reduced productivity.
Innovation Solution
An operating method where the thickness and state parameters of the metal strip are used to establish the calibration value of a roll stand, allowing for calibration during normal operation without interrupting the process, using a model that adjusts the control element position based on these parameters, and employing drivers and loop lifters to manage strip tension and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire roll train is deactivated to replace worn work rolls, then the roll replacement can be performed safely, but the overall productivity of the installation is significantly reduced
Solution Approach 1:
The invention divides the roll train into independent segments, allowing individual roll stands to be deactivated for roll replacement while other stands continue operating. The control element positions are segmented and can be independently adjusted for each stand, enabling partial shutdown without affecting the entire installation.
Solution Approach 2:
The invention implements dynamic control where the model continuously adapts control element positions based on real-time strip thickness measurements and state parameters. During roll replacement, the system dynamically adjusts which stands are active and modifies control parameters to maintain productivity while ensuring safe replacement conditions.
2Ease of repair
If the roll train is stopped for roll replacement in continuous casting and rolling installations, then the worn rolls can be replaced, but the continuous operation is interrupted and productivity is reduced
Solution Approach 1:
The invention performs preliminary calibration of control element positions using a mathematical model before actual roll replacement. Thickness measurements and state parameters are collected in advance, and the model predicts optimal control positions that will maintain strip quality after replacement, reducing the time needed for post-replacement adjustments.
Solution Approach 2:
The invention implements a feedback mechanism where strip thickness measurements from thickness gauges are continuously fed back to the control system. During and after roll replacement, the model uses this feedback to automatically adjust control element positions, ensuring that strip thickness specifications are maintained without requiring manual intervention or production stoppage.
3Measurement precision
If a thickness measuring device is used to capture strip thickness during calibration, then the calibration value can be established, but the calibration process becomes more complex
Solution Approach 1:
The invention makes the thickness measuring device serve multiple functions: it is used for both quality control during normal production and for calibration during roll replacement. The same sensor provides data for both operational monitoring and system recalibration, eliminating the need for separate calibration equipment and reducing overall system complexity.
Solution Approach 2:
The invention enables the calibration system to self-calibrate using existing production equipment and measurements. The mathematical model automatically processes thickness measurement data and state parameters to determine optimal control element positions without requiring external calibration tools or manual intervention, making the system self-sufficient.
Data Source
AI summary
In a normal operation of a roll stand (e.g. 4) of a roll train, working rolls (10) of the roll stand (4) are adjusted to a roll gap (s4) by adjusting a control element position (p4) of a control element (14) of the roll stand (4), such that the working rolls (10) roll the metal band (5). To determine the control element position (p4) to be adjusted, a calibration value (sC4) of the respective roll stand (4), further status parameters (P4) of the roll stand (4) and a target roll gap (s4*) are specified to a model (15) of the roll stand (4). The model (15) determines the control element position (p4) to be adjusted therefrom. In the calibration operation, a control element position (p4) is initially adjusted such that the metal band (5) passes through the roll stand (4) without being rolled. The control element position (p4) is varied such that the working rolls (10) roll the metal band (5). A thickness (d) of the metal band (5) is detected by a downstream thickness-measuring device (9). The thickness (d), further status parameters (P4) and the control element position (p4) are supplied to the model (15), which determines the calibration value (sC4) of the respective roll stand (4) therefrom. Subsequently, normal operation is resumed and the previously determined calibration value (sC4) is used to determine control element positions (p4) to be adjusted as the calibration value (sC4) of the respective roll stand (4).