Pass Schedule Calculation for Stable Metal Strip Rolling
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Solution Overview
Problem
Small working roll diameters in metal strip rolling lead to horizontal deflection and instability, particularly in high-strength materials, due to excessive horizontal forces, which existing methods fail to adequately address by iterative offset adjustments alone.
Innovation Solution
A method and computer program product that calculates a pass schedule by considering individual sections of the metal strip, varying both offset and draw forces, and incorporating load limits to ensure stable rolling conditions, using a pass schedule calculator to predict and maintain target horizontal forces within predefined criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small working roll diameters are used to achieve small final thicknesses and energy efficiency, then manufacturing precision and energy consumption are improved, but horizontal deflection and instability of the rolls increase
Solution Approach 1:
The patent applies dynamics by making the offset variable rather than fixed. The offset is continuously adjusted based on real-time measurement of horizontal roll position and calculation of optimal offset values, allowing the system to adapt to changing rolling conditions and maintain stability throughout the rolling process
Solution Approach 2:
The patent implements feedback by measuring the actual horizontal roll position during rolling, comparing it with the target position, and using this information to calculate and apply corrective offset adjustments. This closed-loop control system ensures the rolls maintain stable positions despite the challenges of small diameters
2Stability of the object's composition
If fixed offset is used to stabilize rolls in hot rolling mills, then roll stability is improved, but the method is insufficient for cold rolling mills with large product ranges and reversing operations
Solution Approach 1:
The patent transforms the static fixed offset into a dynamic variable offset that automatically adapts to different rolling conditions. The system calculates optimal offset values based on current rolling parameters, enabling it to handle diverse product ranges, reversing operations, and various mill types effectively
Solution Approach 2:
The patent changes the offset parameter dynamically during the rolling process based on measured roll positions and rolling conditions. This allows the system to optimize stability for each specific rolling scenario rather than relying on a predetermined fixed offset value
3Stability of the object's composition
If iterative offset adjustment is used to reduce horizontal forces, then roll stability is improved, but the method cannot adequately address excessive horizontal forces in high-strength materials
Solution Approach 1:
The patent applies preliminary action by calculating and setting the optimal offset before rolling begins, based on expected rolling conditions and material properties. This proactive approach prepares the system to handle high horizontal forces from high-strength materials before the rolling process starts
Solution Approach 2:
The patent replaces purely mechanical iterative adjustment with a calculation-based system that uses measured roll positions and mathematical models to determine optimal offset values. This substitution enables more precise and effective control of horizontal forces
Data Source
AI summary
A method and a corresponding computer program product calculate a pass schedule for a stable rolling process when rolling metal strip in a rolling mill. The offset here is varied until the calculated target horizontal force satisfies a predefined limit criterion. The satisfaction of the limit criterion means that the set of rolls and the rolling process are stable. For cases in which a sole iteration of the offset of the working roll does not result in the limit criterion being satisfied, the present invention provides that the draws on the material to be rolled are then changed on the feed side and/or on the outlet side of the rolling stand with constant offset until the calculated target horizontal force satisfies the limit criterion.