Rolling Line Pass Change for Faster Gauge Transitions
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Solution Overview
Problem
The traditional 'wedge-on-wedge' rolling method in rolling mills leads to mass flow problems, material loss, and extended transition times when changing the final rolling dimension, especially when coupled with casting machines, due to limited adjusting cylinder travel speeds and insufficient acceleration capacity of work rolls.
Innovation Solution
A two-phase method where the last rolling stand maintains its roll gap unchanged in the first phase, followed by a second phase with dynamic adjustments to achieve the new final rolling dimension, optimizing load redistribution and minimizing wedges and transition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the adjusting cylinder travel speed is increased to reduce transition time, then the transition time decreases, but the mass flow problems and compression of rolled stock increase
Solution Approach 1:
The patent divides the rolling stand adjustment process into two distinct phases: a first phase where the first rolling stand adjusts its roll gap while subsequent stands maintain constant gaps, and a second phase where subsequent stands sequentially adjust their roll gaps. This segmentation prevents simultaneous adjustments that cause mass flow disturbances, allowing faster adjusting cylinder travel speeds without compromising process stability.
Solution Approach 2:
The first rolling stand performs its pass change in advance before the subsequent rolling stands. This preliminary action allows the rolled stock to gradually adapt to the dimension change, and only after the first stand completes its adjustment do the subsequent stands begin their sequential adjustments, preventing compression and maintaining stable mass flow.
2Manufacturing precision
If wedge-on-wedge rolling is used to change final rolling dimension, then the dimension change is achieved, but material loss and extended transition time occur
Solution Approach 1:
The patent segments the wedge formation process across different rolling stands and time phases. Instead of all stands forming wedges simultaneously (which creates long transition zones and material loss), the first stand forms a wedge in the first phase, and subsequent stands form shorter wedges sequentially in the second phase. This results in a shorter overall transition zone and reduced material loss while achieving the desired dimension change.
3Adaptability or versatility
If all rolling stands simultaneously implement pass changes, then load redistribution is achieved, but mass flow problems occur
Solution Approach 1:
The patent segments the load redistribution process into two phases with different stands active in each phase. In the first phase, only the first rolling stand changes its roll gap to begin load redistribution. In the second phase, subsequent stands sequentially change their roll gaps. This temporal segmentation allows load redistribution to occur without all stands adjusting simultaneously, preventing mass flow problems while achieving the desired load distribution.
4Reliability
If the adjusting cylinder travel speed is limited to prevent stock compression, then mass flow stability is maintained, but transition time increases
Solution Approach 1:
The patent implements dynamic control of adjusting cylinder travel speeds across different phases and stands. In the first phase, the first stand uses higher speeds for rapid initial adjustment. In the second phase, subsequent stands use optimized speeds that are higher than traditional limits but lower than maximum capabilities, adapting to the gradual mass flow changes. This dynamic speed control maintains stability while reducing overall transition time.
Data Source
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AI summary
The invention relates to a method and a computer program product for operating a rolling line having a total number of N roll stands for the rolling of rolling material, more particularly metal strip, from a previous final rolling dimension to a changed new final rolling dimension, said roll stands being disposed one behind the other in a rolling direction. According to the method, the rolling is carried out in two temporal phases I and II. In the first temporal phase, the rolling is carried out in accordance with a first load redistribution in accordance with known wedge-on-wedge rolling, the first load redistribution taking into account that the last roll stand maintains its previously set nip unchanged. In order that the desired change in the dimension of the rolling material to the new final rolling dimension can be limited in the manner of a shorter transition time and on a shortest possible portion of the rolling material, in the method according to the invention the roll stands drive pass changes in accordance with a second load redistribution, the second load redistribution taking into account that, differently than in the first temporal phase I, the last roll stand is dynamically driven to the new final rolling dimension.