Endless Hot-Strip Rolling With Mega-Coil Accumulation
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Solution Overview
Problem
Current combined continuous casting and metal strip hot-rolling plants face limitations in producing thin hot-rolled products with high mechanical properties, requiring cold-rolling for low-carbon steels, leading to increased processing time and complexity in handling thin strips, which restricts the replacement of cold-rolled products and limits the production mix of Advanced High Strength Steels.
Innovation Solution
A combined continuous casting and metal strip endless rolling plant with a continuous casting line, three rolling mills, and high-capacity accumulation means for forming mega coils, allowing for continuous hot-rolling of thin strips and reducing thickness, thereby overcoming jamming issues and enabling the production of thinner strips with improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot-rolling is performed immediately after continuous casting to reduce processing time, then productivity improves, but the mechanical properties and surface quality deteriorate for low-carbon steels
Solution Approach 1:
The patent applies parameter changes by controlling the temperature range and cooling rate during hot-rolling to achieve the desired mechanical properties. By optimizing the finishing temperature and subsequent cooling parameters, the process produces thin slabs with improved strength characteristics without requiring cold-rolling, thus maintaining high productivity while improving mechanical properties.
2Productivity
If thin strips are produced by hot-rolling to reduce processing time, then productivity improves, but handling reliability deteriorates due to jamming risks
Solution Approach 1:
The patent changes the temperature parameter during hot-rolling to maintain the strip in an austenitic or ferritic state, which improves ductility and reduces the risk of jamming during handling. By controlling the strip temperature above the transformation point, the material remains more formable and less prone to defects, thereby improving handling reliability for thin strips while maintaining high productivity.
3Strength
If cold-rolling is performed to achieve high mechanical properties, then strength improves, but processing time and device complexity increase
Solution Approach 1:
The patent extracts the cold-rolling step from the traditional processing sequence by achieving the desired mechanical properties through optimized hot-rolling followed by controlled cooling. This removes the unnecessary cold-rolling operation, reducing both processing time and device complexity while maintaining or improving the mechanical properties through precise temperature and rate control during hot-rolling and cooling.
Solution Approach 2:
The patent maintains continuous hot-rolling and cooling operations without interruption, eliminating the need for separate cold-rolling stages. The continuous process flows directly from casting through hot-rolling to coiling, maintaining the strip in a controlled temperature state throughout, which simplifies the overall process and improves productivity while achieving the required mechanical properties.
4Ease of operation
If rolling in austenitic range is performed to improve ductility, then ease of operation improves, but deformation anisotropy increases
Solution Approach 1:
The patent applies parameter changes by controlling the finishing temperature and cooling rate to optimize the microstructure. By adjusting these parameters, the process achieves the desired balance between ductility during rolling and minimal deformation anisotropy in the final product, allowing the strip to be formed more easily while maintaining compositional stability and uniform properties.
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 significantly reduces processing time, enhances production flexibility, and achieves mechanical properties comparable to cold-rolled products, enabling the production of thinner strips and Advanced High Strength Steels, thus replacing cold-rolling processes and expanding the range of steel products.
Implementation Method 1
continuous casting line for casting a slab
Implementation Method 2
casting a slab
Implementation Method 3
first rolling mill for roughing the slab, a second rolling mill for finishing the transfer bar, a third rolling mill, comprising at least two rolling stands, for further reducing the thickness of the strip
Implementation Method 4
accumulation means of the strip comprising at least one first reel dimensioned to wind and unwind a coil
Implementation Method 5
wind and unwind a coil weighing from 80 to 250 metric tons and/or up to 6 meters in diameter
Data Source
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AI summary
A combined continuous casting and endless rolling plant for a metal strip, comprising - a continuous casting line (1) for casting a slab; - a first rolling mill (6) for roughing the slab and for obtaining a transfer bar; - a second rolling mill (11 ) for finishing the transfer bar and for obtaining a strip; - a third rolling mill (18), comprising at least two rolling stands (17), for further reducing the thickness of the strip; - accumulation means (20) of the strip comprising at least one first reel (37, 37') dimensioned to wind and unwind a coil weighing from 80 to 250 metric tons and/or up to 6 meters in diameter, named mega coil; - first cutting means (13), arranged between said third rolling mill (18) and said accumulation means (20), configured to cut the strip after the mega coil has been wound on the at least one first reel (37, 37'); - at least one second reel (48) for winding portions of strip, unwound from said accumulation means (20), up to a predetermined weight limit or coil diameter limit; - second cutting means (47), arranged between said accumulation means (20) and said at least one second reel (48), adapted to cut the strip whenever a portion of strip wound on the at least one second reel (48) reaches said predetermined weight limit or coil diameter limit.