Work Roll Shift and Bender Control for Rapid Edge Drop Changes
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Solution Overview
Problem
Existing edge drop control methods in cold rolling face delays and inefficiencies, particularly when edge drop varies rapidly due to changes in rolling speed or other conditions, leading to inaccurate thickness control and increased yield loss from edge cutting.
Innovation Solution
An edge drop control device comprising low response actuators, a high response actuator, and a processor that calculates and adjusts manipulated amounts to minimize control delays, using a combination of work roll shift and bender devices to independently manage edge drop on both sides, with a control map for regulating high response actuator operations during speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low response actuator is used for edge drop control during rolling, then the device complexity is reduced, but the response speed becomes slow causing control delay when edge drop varies rapidly
Solution Approach 1:
The patent segments the edge drop control function into two distinct actuators: a low response actuator for general control and a high response actuator for rapid adjustments. This segmentation allows each actuator to be optimized for its specific response characteristic, resolving the contradiction between device simplicity and response speed.
Solution Approach 2:
The control system dynamically selects which actuator to use based on the current rolling conditions and edge drop variation rate. When edge drop varies rapidly, the high response actuator is activated; otherwise, the low response actuator is used. This dynamic adaptation resolves the contradiction by matching actuator response capability to actual control needs.
2Speed
If a high response actuator is used for edge drop control, then the response speed improves, but the device complexity and cost increase
Solution Approach 1:
The control system is segmented into multiple actuators with different response characteristics, allowing the high response actuator to be used only when necessary for rapid edge drop changes, thereby limiting the impact on overall device complexity.
Solution Approach 2:
The high response actuator is deployed partially - only when edge drop varies rapidly - rather than being continuously used. This partial action approach provides the needed response speed improvement while avoiding the complexity and cost of having the high response actuator as the primary control mechanism.
3Manufacturing precision
If work roll shift device and work roll bender device are manipulated simultaneously, then the control precision improves, but the control delay increases when the manipulated amount of work roll shift device is large
Solution Approach 1:
The control system dynamically determines the manipulation strategy based on the magnitude of required adjustment. When large adjustments are needed, only the work roll shift device is manipulated to avoid delay. When smaller adjustments are needed, both devices are coordinated for higher precision. This dynamic approach resolves the contradiction between precision and speed.
Solution Approach 2:
The system performs preliminary assessment of the required manipulated amount before executing control actions. This allows the control system to pre-determine the optimal combination of actuators to minimize delay while achieving the required precision, rather than simultaneously manipulating all actuators regardless of necessity.
4Measurement precision
If edge drop control is performed based on delivery side measurement, then the measurement accuracy is sufficient, but the control response is delayed compared to upstream measurement
Solution Approach 1:
The control system performs preliminary calculation of the required manipulated amount based on delivery side edge drop measurements. This allows the control actions to be prepared in advance, reducing the effective response time when the actual manipulation is executed, thereby mitigating the delay inherent in using delivery side measurements.
Data Source
AI summary
An edge drop control device calculates a first calculated manipulated amount of a work roll shift device for bringing a difference between a measured edge drop amount and a target amount close to zero without using a work roll bender device. The edge drop control device calculates a second calculated manipulated amount of the work roll bender device for bringing a difference between a measured edge drop amount and the target amount close to zero without using a work roll shift device. The edge drop control device outputs, when the first calculated manipulated amount is out of an allowable range, the second calculated manipulated amount to the work roll bender device and also outputs a difference between an amount that corresponds to the second calculated manipulated amount and the first calculated manipulated amount, to the work roll shift device.