Roll Gap Control for Tension-Induced Thickness Variation
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Solution Overview
Problem
The existing rolling processes face challenges in maintaining precise thickness control of flat metal rolling stock due to tension-related changes, which are not adequately addressed by current automatic gauge control (AGC) systems, leading to delays and inaccuracies in thickness correction, especially during the tapping phase when inlet-side or outlet-side tensions change.
Innovation Solution
An operating method that determines an additional setpoint using actual and target tension values from inlet-side and outlet-side train controls, combined with sensitivity factors, to adjust the roll gap and compensate for changes in rolling force and springiness, ensuring better thickness compliance by actively managing tension-related changes during rolling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AGC (automatic gauge control) is used to correct thickness variations, then thickness control is improved, but response time is delayed and inaccuracies occur during tension changes
Solution Approach 1:
The patent applies preliminary action by calculating and applying a preliminary thickness correction based on predicted rolling force changes before the actual thickness deviation occurs. The system predicts the rolling force change based on tension changes and applies a preliminary correction to the actuator position setpoint, thereby compensating for thickness variations proactively rather than reactively, reducing both delay and inaccuracy.
2Manufacturing precision
If roll gap is adjusted to maintain target thickness, then thickness precision is improved, but tension-induced springback variations cause inaccuracies
Solution Approach 1:
The patent implements feedback by continuously monitoring actual rolling force and comparing it with predicted rolling force. Based on the difference between actual and predicted values, the system calculates a correction value that is applied to the actuator position setpoint. This closed-loop feedback mechanism compensates for springback variations caused by tension changes, improving both precision and reliability of thickness control.
3Stability of the object's composition
If tension control is applied to maintain inlet-side or outlet-side tension, then rolling process stability is improved, but thickness control accuracy deteriorates due to unaccounted rolling force changes
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the actuator position setpoint based on changes in rolling force parameters. The system calculates the difference between predicted and actual rolling force and translates this parameter change into a corrective position adjustment. This allows the system to maintain thickness control accuracy even when tension control causes rolling force variations, effectively decoupling the two control objectives.
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 enhances the dynamic control of the rolling process, allowing for precise thickness maintenance even when AGC is not active, reducing errors and improving stability by compensating for tension-induced thickness variations, thus shortening the initial and end sections of the rolling stock to meet target thickness within tighter tolerances.
Implementation Method 1
the springback of the roll stand must also be taken into account. Springback results from the rolling force and other forces acting on the roll stand
Implementation Method 2
the stock to be subjected to an inlet-side tension in front of the roll stand or an outlet-side tension behind the roll stand
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A flat metal material (2) to be rolled is rolled in a roll stand (1). A position controller (6) for controlling the placement of an actuator (5) by means of which a roll gap of the roll stand (1) is set determines an actuating variable (q) for the actuator (5) as a function of a resulting position target value (s*) and a position actual value (s) of the actuator (5) and drives the actuator (5) accordingly. The resulting position target value (s*) is determined with utilization of a resulting base target value (s1*). The resulting base target value (s1*) is determined as the sum of an initial base target value (s0*) and an additional target value (δs1*). The additional target value (δs1*) is determined by a determination element (13) with utilization of an inlet-end actual tension (ZE) and an inlet-end reference tension (ZER) and/or with utilization of an outlet-end actual tension (ZA) and an outlet-end reference tension (ZAR). Instead of the actual tensions (ZE, ZA), the corresponding target tensions (ZE*, ZA*) of corresponding tension control operations can also be used. However, in both cases, the reference tensions (ZER, ZAR) are variables that differ from the target tensions (ZE*, ZA*).