Roll Gap Tension Compensation for Stable Thickness Control
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Solution Overview
Problem
Existing roll stand systems face challenges in maintaining accurate thickness of rolled metal stock due to delays and inefficiencies in correcting deflection caused by inlet-side and outlet-side tensions, particularly during initial and final passes, leading to thickness deviations and potential oscillations.
Innovation Solution
An operating method that determines an additional target value based on actual and reference tensions using sensitivity factors, allowing for real-time adjustment of the roll gap to compensate for tension-induced deflections, even when the Automatic Gauge Control (AGC) is not active, thereby improving thickness control and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the roll gap is set based on actuator position alone, then the positioning is simple, but the thickness control accuracy deteriorates due to deflection from rolling force and tension
Solution Approach 1:
The system uses feedback from tension sensors to detect actual inlet-side and outlet-side tensions, then feeds this information back to the position regulator which adjusts the actuator position accordingly. This closed-loop feedback mechanism compensates for deflection caused by tension forces, maintaining thickness control accuracy while building upon the simple actuator-position-based positioning approach.
Solution Approach 2:
The invention introduces a position regulator as an intermediary component between the actuator position control and the roll gap setting. This regulator calculates the actual roll gap by considering both the actuator position and the deflection caused by rolling force and tension, thereby mediating between the simple actuator positioning and the accurate thickness control requirements.
2Manufacturing precision
If AGC is used to correct deflection, then thickness control improves, but response time increases due to delay in correcting tension-induced deflection
Solution Approach 1:
The system performs preliminary action by proactively compensating for expected tension-induced deflection before it causes thickness deviation. The position regulator uses the detected actual tensions to calculate and apply compensation to the actuator position in advance, preventing deflection-related thickness errors rather than correcting them after they occur, thus reducing response time delays.
Solution Approach 2:
The invention implements dynamic adjustment of the roll gap by continuously updating the actuator position based on real-time tension measurements. Unlike static AGC correction, the system dynamically adapts to changing tension conditions during rolling, allowing immediate response to tension variations and reducing the time delay in correcting deflection.
3Stability of the object's composition
If inlet-side and outlet-side tensions are regulated, then tension maintenance improves, but thickness control deteriorates due to uncorrected deflection during initial and final passes
Solution Approach 1:
The invention merges the tension regulation function with the roll gap control function in a unified system. The position regulator simultaneously processes information from both tension regulators and actuator position sensors, combining these inputs to determine the optimal actuator position that maintains both tension stability and thickness accuracy. This integrated approach ensures that tension regulation and thickness control work together rather than conflict, particularly during initial and final passes.
Data Source
AI summary
A position controller that controls an actuator that sets a roll gap of a roll stand by determining an actuating variable (q) for the actuator as a function of a resulting position target value (s*) and a position actual value(s) of the actuator. The (s*) is determined with a resulting base target value (s1*), which is determined as the sum of an initial base target value (s0*) and an additional target value (δs1*), which is determined by a determination element with an inlet-end actual tension (ZE) and an inlet-end reference tension (ZER) and/or with an outlet-end actual tension (ZA) and an outlet-end reference tension (ZAR). Instead of (ZE) and (ZA), the corresponding target tensions (ZE*, ZA*) of corresponding tension control operations can also be used. However, in both cases, (ZER) and (ZAR) are variables that differ from (ZE*) and (ZA*).