Roll Stand Tilt Control to Prevent Metal Strip Edge Undulations
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Solution Overview
Problem
Existing roll stand control methods fail to effectively prevent waves in rolled metal strips, leading to faults and cobbles, as they cannot anticipate and adjust for unmeasurable factors like thickness wedges and temperature gradients, despite attempts to align the strip's lateral position.
Innovation Solution
A control method that assesses the formation of waves in metal strips by varying parameters of the stand controller, using image data to detect wave formation and adjust pivot values, and stores these parameters for future rolls with similar characteristics to prevent wave occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lateral position of the metal strip is adjusted by pivoting the rolls to align with the desired position, then the strip alignment is improved, but wave formation occurs in the metal strip
Solution Approach 1:
The control device applies preliminary counteracting actions by detecting wave formation tendencies and adjusting roll parameters before complete wave development occurs. The system proactively modifies pivot values and roll positions to prevent wave formation while maintaining strip alignment, rather than reacting after waves have fully developed
Solution Approach 2:
The control device dynamically changes operating parameters including pivot values, roll positions, and rolling forces based on real-time detection of strip conditions. By adjusting these parameters in response to detected wave tendencies, the system maintains both alignment precision and strip stability without fixed parameter settings
2Stability of the object's composition
If the roll stand is asymmetrically adjusted to compensate for unmeasurable factors like thickness wedges and temperature gradients, then wave formation is reduced, but the control system cannot anticipate these factors in advance
Solution Approach 1:
The control device implements feedback control by continuously detecting strip conditions including wave formation indicators and using this information to adjust roll parameters. The system measures actual strip behavior and feeds this information back to modify pivot values and rolling forces, compensating for unmeasurable factors like thickness variations and temperature gradients through their observable effects
Solution Approach 2:
The control device takes preliminary actions by detecting early signs of wave formation and adjusting roll parameters before complete wave development occurs. The system proactively modifies operating conditions based on detected tendencies, preparing the rolling process in advance to prevent wave formation rather than reacting after waves have fully developed
Data Source
AI summary
A control device (3b) for a roll stand (1). During rolling of a metal strip (2) in the roll stand (1), the device receives measurement data (M) for a lateral position (y) of the metal strip (2) on the inlet side and/or outlet side of the roll stand (1). Taking into account parameters (P) of the stand regulator (3a) on the basis of the deviation in the lateral position (y) from a target position (y*), a stand regulator (3a) of the control device (3b) determines a tilt value (δs) for the roll stand (1) and controls the roll stand (1) accordingly. The control device (3b) determines at least one variable (V1, V2, Q1, Q2) from which it is derived, for both strip edges (7, 8) of the metal strip (2), whether the metal strip (2) forms an undulation (9) in the region of the particular strip edge (7, 8). As soon as the metal strip (2) forms an undulation (9) in the region of one of the strip edges (7, 8), the control device (3b) varies at least one of the parameters (P) of the stand regulator (3a), such that the stand regulator (3a) determines the tilt value (δs), starting from the variation in the at least one parameter (P), and taking into account the changed parameter (P).