Finishing Train Width Control Using Tension and Temperature Tracking
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Solution Overview
Problem
Existing methods for controlling the width of metal strips in hot rolling trains often fail to maintain precise width tolerances, especially due to uneven temperature distributions, leading to inadequate width regulation and widening issues during the finishing process.
Innovation Solution
A method that detects the actual width and temperature of metal strip sections before entering the finishing train, associates these with target values, and uses a width control unit at each rolling stand to adjust tension and temperature to accurately track and correct the width, ensuring the metal strip approximates the target width by calculating downstream additional target values and supplying them to a tension regulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If width measurement is performed after multiple rolling stands and compensation is done by switching on additional strip tension, then width deviations can be compensated, but the control system becomes complex and requires multiple measurement points
Solution Approach 1:
The patent performs width measurement before the finishing train (at the roughing train outlet) in advance, before the metal strip enters the finishing train. This preliminary measurement allows the control system to predict and prepare for width deviations that will occur during finishing rolling, rather than reacting to them after they happen. The control system uses this early measurement data to calculate target widths for each finishing stand and adjust tensions proactively.
Solution Approach 2:
The patent divides the finishing train into multiple rolling stands (first, second, third stands) and assigns specific control functions to each. The control system segments the width control task by determining target widths for each individual stand based on the initial measurement and predicted widening behavior. This segmentation allows distributed control without requiring multiple physical measurement points throughout the finishing train.
2Manufacturing precision
If width is controlled by adjusting tension at each rolling stand, then width precision improves, but the control interventions increase in frequency and complexity
Solution Approach 1:
The control system performs width measurement and control calculations at specific periodic intervals - specifically at the outlet of the roughing train before the finishing train. This periodic control approach, rather than continuous adjustment at each stand, reduces the frequency of control interventions while maintaining effectiveness. The system recalculates target widths periodically based on the initial measurement and predicted widening.
Solution Approach 2:
The control system calculates and sets target widths for all finishing stands in advance, before the metal strip actually passes through them. This preliminary calculation of target widths for each stand, based on the initial width measurement and predicted widening behavior, allows the system to prepare control actions ahead of time, reducing the need for frequent reactive adjustments during the actual finishing process.
3Measurement precision
If multiple width measurements are performed throughout the finishing train, then width deviations can be detected accurately, but the hardware requirements and system complexity increase
Solution Approach 1:
The patent performs the width measurement in advance at the roughing train outlet, before the metal strip enters the finishing train. This single preliminary measurement is sufficient because the control system uses it to predict width deviations and calculate target widths for each finishing stand. This eliminates the need for multiple measurement points throughout the finishing train while maintaining effective width control.
Solution Approach 2:
The control system uses the initial width measurement as feedback to calculate predicted widening behavior and determine appropriate target widths for each finishing stand. This feedback mechanism allows the system to compensate for expected width deviations without needing to physically measure the width at each subsequent stand. The feedback loop is closed through tension adjustment based on the initial measurement data.
Data Source
AI summary
Before the rolling of a metal strip on a finishing train, the actual width and actual temperature of portions of the metal strip are respectively detected. The portions of the metal strip are tracked while they run through the finishing train. The rolling stands are respectively assigned width controlling devices which determine the setpoint width and the actual width after the rolling in the assigned rolling stand, and a downstream additional setpoint value, by which the desired tension downstream of the assigned rolling stand is corrected in order to bring the actual width closer to the setpoint width. The downstream additional setpoint value is both taken into account in the determination of the actual width and fed to a tension controller, which sets an actual tension, in the metal strip downstream of the assigned rolling stand, in accordance with the corrected setpoint tension. Determining the downstream additional setpoint value by the difference between the setpoint width and the actual width of a portion of the metal strip.