Rolling Mill Gauge Change Control for Endless Strip Production
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Solution Overview
Problem
Existing methods for flying gauge change in metal strip production, especially in endless and semi-endless modes, face challenges in reliability, stability, and quality due to synchronization issues between casting and rolling processes, with potential disturbances from heating furnaces and elasticity of slabs, leading to inefficiencies and wear.
Innovation Solution
A system comprising a continuous casting machine, tunnel furnace, roughing mill, rapid heating unit, finishing mill, and loopers, allowing for automatic mode switching between endless, semi-endless, and coil-to-coil production, with a control system that manages rolling speed and temperature to optimize energy use and maintain product quality, and enables flying gauge change by adjusting the gap and rotation speed of rolling stands to achieve precise thickness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flying gauge change is performed by modifying the gap between work rollers of rolling stands, then the final thickness of the metal strip can be changed, but synchronization issues between casting and rolling processes occur, leading to disturbances from heating furnaces and elasticity of slabs
Solution Approach 1:
The control system performs preliminary actions by pre-calculating and pre-positioning the rolling stands and adjusting roller gaps before the actual gauge change occurs. The system prepares the rolling mill by sequentially adjusting stands from downstream to upstream, ensuring that each stand is ready before the material reaches it, thereby avoiding synchronization disturbances and maintaining process stability during thickness changes.
2Manufacturing precision
If the gap between work rollers is modified progressively from upstream toward downstream, then thickness change can be achieved, but coordination of rotation speed and tensioner position requires complex control
Solution Approach 1:
The control system inverts the conventional approach by coordinating adjustments from downstream to upstream rather than upstream to downstream. The roller gap modification starts from the last stand and progresses backward to the first stand, while rotation speeds are adjusted in reverse sequence. This inversion simplifies the control logic by ensuring that each stand is adjusted only after downstream stands are ready, reducing the complexity of coordination between multiple variables.
3Temperature
If rapid heating system is used to restore temperature before last rolling passes, then product temperature is maintained, but energy consumption increases
Solution Approach 1:
The rapid heating system applies partial heating action only to the specific zones and time periods where temperature restoration is critically needed, rather than continuous heating of the entire product. The system activates heating selectively during intermediate positions in the rolling mill where temperature drop affects subsequent rolling passes, optimizing energy usage by applying heat only where and when necessary to maintain product temperature for quality rolling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances the reliability and stability of flying gauge change, reduces wear, and improves the quality of the final metal strip by optimizing energy consumption and production efficiency, allowing for continuous casting without interruptions and minimizing scrap production.
Implementation Method 1
In an intermediate position along the rolling mill it is known, for example from EP 2.569.104, to provide a rapid heating system which, at least in endless mode, determines a restoration of the temperature of the product being rolled
Implementation Method 2
The rolling mill can therefore be represented in its subdivision, for example 2+4, 2+5, 3+5, in relation to the roughing stands which are the first stands of the rolling mill and perform the first thickness reduction of the product at entry
Data Source
AI summary
Method for the production of flat metal products, in particular coils of strip, in endless and/or semi-endless mode, in which a metal product is continuously fed to a rolling mill consisting overall of at least 4 stands. The rolling stands are, in sequence, roughing stands, and finishing stands. It is provided to perform a flying gauge change of the metal product exiting from the rolling mill.