Hot Finishing Tandem Mill Control for Edge Profile and Strip Crown
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Solution Overview
Problem
Hot finishing tandem rolling mills face challenges in controlling edge-up and edge-drop phenomena, which affect strip profile and passing performance, as existing methods struggle to set both strip crown and edge profile to predetermined values while maintaining strip shape within allowable ranges.
Innovation Solution
A hot finishing tandem rolling mill with reduction devices and strip shape control actuators, a decision control device that adjusts rolling force and flatness control parameters at each stand to control edge profile and strip crown, and a rolling mill control device that implements these adjustments based on a predetermined pass schedule, ensuring the strip shape remains within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rolling force per unit width at the last stand is adjusted to control edge profile, then edge-up or edge drop can be reduced to within allowable range, but strip crown control becomes difficult to achieve at predetermined value
Solution Approach 1:
The patent segments the control of strip profile into two independent control loops: one for edge profile control using rolling force per unit width adjustment, and another for strip crown control using flatness control parameter adjustment. This segmentation allows each parameter to be optimized independently without compromising the other, resolving the contradiction between edge profile and strip crown control precision.
Solution Approach 2:
The patent implements dynamic adjustment of both rolling force per unit width and flatness control parameters based on real-time measurement of edge profile and strip crown. The control system continuously monitors these parameters and dynamically modifies the rolling conditions to maintain both edge profile and strip crown within their respective predetermined ranges, enabling simultaneous precision control of both parameters.
2Manufacturing precision
If flatness control parameter of the last stand is adjusted to control strip crown, then strip crown can be set to predetermined value, but edge profile may exceed allowable range
Solution Approach 1:
The patent separates the control functions into independent segments: flatness control parameters are specifically adjusted for strip crown control, while rolling force per unit width is adjusted for edge profile control. This functional segmentation ensures that adjusting one parameter does not adversely affect the other, allowing both parameters to be maintained within their predetermined ranges simultaneously.
Solution Approach 2:
The patent employs feedback control mechanisms where the actual strip crown and edge profile measurements are fed back to the control system. Based on this feedback, the flatness control parameters and rolling force per unit width are continuously adjusted to maintain both parameters within their respective predetermined ranges, resolving the contradiction between strip crown and edge profile control.
3Manufacturing precision
If only strip crown is controlled to predetermined value using preset control model, then strip crown requirement is met, but edge profile control and strip shape within allowable range cannot be ensured
Solution Approach 1:
The patent extends the control system beyond single-point strip crown measurement to include multi-point measurements of edge profile and strip shape. The control model is segmented into multiple control objectives: strip crown control at the center, edge profile control at the edges, and strip shape control across the width. Each objective is controlled by dedicated parameters (flatness control parameters for crown, rolling force per unit width for edge profile), ensuring all parameters remain within allowable ranges simultaneously.
Solution Approach 2:
The patent transitions from one-dimensional strip crown control to two-dimensional strip profile control by incorporating edge profile and strip shape measurements across the width of the strip. This dimensional expansion allows the control system to monitor and adjust multiple parameters (center crown, edge thickness, flatness) simultaneously, ensuring all remain within their predetermined ranges through coordinated adjustment of flatness control parameters and rolling force per unit width.
Data Source
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AI summary
In a decision control device (60) of a control system (50), a predetermined pass schedule is decided by adjusting the rolling force per unit width at a last stand (100) of a hot finishing tandem rolling mill (1) to cause the edge profile on the outlet side of the last stand (100) to fall within an allowable range based on the relationship between a strip crown and the edge profile on the outlet side of the last stand (100) with respect to the rolling force per unit width and a strip shape control parameter, obtained regarding the last stand (100), and adjusting the strip shape control parameter of the last stand (100) to cause the strip shape on the outlet side of the last stand (100) to fall within an allowable range and cause the strip crown to become a predetermined value or smaller.