Multi-Mode Thin Slab Rolling Layout for Flexible Steel Production
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Solution Overview
Problem
Existing rolling plants face limitations in producing a wide range of steel qualities and thicknesses due to the rigidity of the endless process, which results in low use factor, yield, and flexibility, making it impractical for certain steel types and preventing the addition of a second casting line to increase productivity.
Innovation Solution
A rolling plant that integrates three operating modes: endless, semi-endless, and coil-to-coil, allowing for the production of all steel qualities with thicknesses between 30 and 140 mm, incorporating a tunnel furnace as a buffer and rapid heating unit to manage production flexibility and maintain continuous casting without interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rolling train is directly attached at the exit of the continuous casting machine in the endless process, then temperature loss is minimized and energy saving in rolling is achieved, but the process becomes rigid and cannot accommodate certain steel types requiring lower casting speeds
Solution Approach 1:
The patent segments the continuous casting-rolling process into distinct modules: continuous casting machine, tunnel furnace, roughing rolling train, rapid heating unit, and finishing rolling train. This segmentation allows independent optimization of each module and enables flexible configuration for different steel types while maintaining the benefits of direct attachment for ultra-thin strip production.
Solution Approach 2:
The patent introduces dynamic control of the tunnel furnace and rapid heating unit to adjust the process in real-time. The tunnel furnace can operate in different modes (heating, maintenance, accumulation) and the rapid heating unit provides dynamic temperature adjustment, enabling the system to adapt to different steel qualities and casting speeds while maintaining process continuity.
2Productivity
If the rolling train is located immediately at the exit of the continuous casting machine, then continuous rolling is achieved, but any stoppage requires stopping the casting process causing production loss
Solution Approach 1:
The patent incorporates a tunnel furnace between the continuous casting machine and the roughing rolling train that can accumulate slabs beforehand. This creates a buffer stock that allows the rolling train to be stopped for maintenance or roll changes without immediately stopping the continuous casting process, thus cushioning against production interruptions and maintaining overall productivity.
Solution Approach 2:
The tunnel furnace acts as an intermediary element between the continuous casting machine and the rolling train. It decouples the two processes, allowing independent operation and enabling the rolling train to be stopped without affecting the casting process, thereby improving system reliability while maintaining productivity.
3Length of moving object
If the endless process is used for ultra-thin strip production, then thickness reduction from 1.5-3.0 mm to 0.7-0.9 mm is achieved, but the process cannot accommodate steel types requiring lower casting speeds
Solution Approach 1:
The patent applies preliminary heating in the tunnel furnace before the slab enters the rolling train. This allows the casting speed to be reduced for certain steel types without compromising the final rolling temperature, enabling the production of various steel qualities including peritectic steel, high carbon steel, and silicon steel while still achieving ultra-thin strip thicknesses.
Solution Approach 2:
The patent changes the temperature parameter through the tunnel furnace and rapid heating unit to accommodate different steel types. By adjusting the heating parameters and maintaining appropriate temperatures throughout the process, the system can handle steel types requiring lower casting speeds while still achieving the target ultra-thin thicknesses of 0.7-0.9 mm.
4Productivity
If a second casting line is added to increase productivity, then production capacity increases, but the rigid endless process layout prevents such expansion
Solution Approach 1:
The patent designs the tunnel furnace and rolling train as universal components that can serve multiple functions and multiple casting lines. The tunnel furnace can accommodate slabs from different casting lines and the rolling train can process slabs from either line, enabling the addition of a second casting line to increase productivity without significantly increasing overall plant complexity.
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 plant achieves high productivity and quality by enabling the production of all steel qualities with reduced production costs, optimized energy use, and increased yield by automatically switching between operating modes based on steel quality and thickness, allowing for continuous casting without interruptions.
Implementation Method 1
a tunnel furnace (15) for possible heating and/or maintenance, located between the continuous casting device (11) and the roughing train (18a, 18b, 18c)
Implementation Method 2
tunnel furnace (15) for possible heating and/or maintenance
Implementation Method 3
a rapid heating unit (20), in this case using induction, at exit from the roughing stands (18a, 18b, 18c) and upstream of the finishing rolling stands (21a, 21b, 21c, 21d, 21e)
Data Source
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AI summary
Rolling plant and method to produce strip with a thickness varying from 0.7 mm to 20 mm, for all qualities of steel which can be cast in the form of thin slabs with a thickness comprised from 30 mm to 140 mm. The plant comprises at least a continuous casting device (11), a tunnel furnace (15) for heating and maintenance/equalization disposed downstream of the continuous casting device (11), a rolling train, disposed downstream of the tunnel furnace (15), consisting of a roughing train comprising from 1 to 4 rolling stands (18a, 18b, 18c) and a finishing train comprising from 3 to 7 stands (21a-21e), a rapid heating unit (20) with elements able to be selectively activated, interposed between said roughing train and said finishing train. The plant is made to work either in coil-to-coil mode, or in semi-endless mode or in endless mode.