Rolling Mill Control System for Exit Thickness Stability
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Solution Overview
Problem
In rolling mills, fluctuations in entry or exit tension lead to unstable exit thickness control, causing issues like snaking of rolled materials and plate breaks due to the inability to effectively manage tension deviations within predetermined ranges, especially during changes in rolling speed.
Innovation Solution
The implementation of a control method that uses entry and exit tension-reel speeds to control tension fluctuations, incorporating a control system that switches between different control modes (constant torque, constant speed, and speed thickness control) based on rolling conditions to maintain stable exit thickness and tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the tension reel is operated under constant torque control to maintain stable rolling operation, then the rolling operation is stabilized, but the tension reel speed fluctuates causing exit thickness fluctuation
Solution Approach 1:
The control system dynamically switches between constant torque control and constant speed control modes based on rolling conditions. When the influence coefficient changes significantly, the system transitions to constant speed control to maintain entry speed stability and prevent exit thickness fluctuation, while still allowing tension fluctuations within acceptable ranges.
Solution Approach 2:
The system changes the control parameter from torque to speed when the influence coefficient changes greatly. By monitoring the influence coefficient and switching control modes accordingly, the system maintains both rolling operation stability and exit thickness accuracy under varying conditions.
2Manufacturing precision
If the tension reel speed is made constant to suppress exit thickness fluctuation, then the exit thickness accuracy is improved, but the tension fluctuation increases beyond acceptable ranges
Solution Approach 1:
The control system dynamically adjusts the control mode based on rolling conditions. When constant speed control is active, the system allows tension to fluctuate within a predetermined range, switching to constant torque control when tension stability becomes critical, thus balancing thickness accuracy and tension stability requirements.
Solution Approach 2:
The system applies constant speed control only partially - allowing tension fluctuations within acceptable ranges rather than completely suppressing them. This partial action maintains exit thickness accuracy while accepting some tension variation that does not compromise rolling operation stability.
3Adaptability or versatility
If the influence coefficient of the rolling mill changes greatly due to operational state, then the rolling conditions vary, but the existing control methods become unstable
Solution Approach 1:
The system continuously monitors the influence coefficient and uses this feedback to determine when to switch between control modes. When the influence coefficient changes exceed a threshold, the system transitions from constant torque to constant speed control, ensuring stable operation under varying rolling conditions.
Solution Approach 2:
The control system is designed to be dynamic, automatically adapting its control strategy based on real-time rolling conditions. The switching mechanism ensures that the appropriate control mode (constant torque or constant speed) is applied according to the current operational state, maintaining control stability across different scenarios.
Data Source
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AI summary
To suppress an influence on an exit thickness of a rolled material when fluctuation of entry or/and exit tension of the rolled material is controlled using entry or/and exit tensionreel speed of the rolled material. In a rolling mill (1) with roll pairs to roll a rolled material, means is provided for switching, according to rolling conditions, between a control element for controlling a tension of the rolled material and a control element (61) for controlling a thickness of the rolled material. A running speed of the rolled material entering the rolling mill to be rolled is controlled based on a thickness of the rolled material. A running speed of the rolled material exiting the rolling mill is controlled based on a tension of the rolled material exiting the rolling mill (1). To control the running speed of the rolled material exiting the rolling mill (1), a non-interference control variable is generated and output for controlling the running speed of the rolled material entering the rolling mill. A control value for control based on tension fluctuation of the rolled material is suppressed to be smaller at the switching between the control elements.