Flat Rolled Strip Crown Profiling for Symmetric Slit Widths
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Solution Overview
Problem
Existing rolling processes struggle to maintain productivity and achieve precise control over the crown and planarity of hot-rolled strips when dividing them into narrower widths, leading to asymmetrical profiles and instability in downstream processing.
Innovation Solution
The use of work rolls with shaped profiles, such as double, triple, or quadruple crowns, in the finishing mill stands to impart corresponding profiles to the strip, combined with a controlled cooling system to modulate thermal crowns, allowing for precise control of the mechanical and thermal profiles to achieve symmetrical crowns in divided strip portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rolling mill produces strip with maximum width to maintain productivity, then productivity is improved, but the strip cannot meet market requirements for narrower widths
Solution Approach 1:
The invention segments the rolling process into two distinct phases: a first rolling phase that produces a wide strip at maximum productivity, and a second rolling phase that divides and re-rolls the wide strip into multiple narrower strips of desired width. This segmentation allows the plant to maintain high productivity while delivering various narrower widths to meet diverse market requirements.
Solution Approach 2:
The invention performs preliminary action by first producing a wide strip with optimal crown profile in the first rolling phase, before dividing it into narrower portions. This preliminary wide-strip production with controlled crown ensures that subsequent division and re-rolling can achieve the desired narrow widths while maintaining quality, rather than directly rolling narrow strips which would reduce productivity.
2Adaptability or versatility
If the strip is divided longitudinally into half-strips to meet narrower width requirements, then width adaptability is improved, but the crown becomes asymmetrical and profile quality deteriorates
Solution Approach 1:
The invention applies preliminary action by imparting a predetermined crown profile to the wide strip in the first rolling phase, specifically designing this preliminary crown to compensate for the asymmetry that will occur during subsequent longitudinal division. This preliminary crown configuration ensures that after division and re-rolling, each narrow strip achieves the desired symmetrical crown profile.
Solution Approach 2:
The invention applies local quality by creating different crown profiles in different zones of the wide strip during the first rolling phase. The crown distribution is specifically tailored for each width zone that will subsequently be divided, ensuring that each future narrow strip portion receives the appropriate local crown characteristics needed for its final profile.
3Ease of manufacture
If conventional rolling processes are used for divided strips, then processing simplicity is maintained, but crown control precision and planarity are insufficient
Solution Approach 1:
The invention uses preliminary action to pre-establish the crown profile in the first rolling phase, which then serves as the foundation for the second rolling phase. This preliminary crown configuration reduces the adjustment burden in the second phase and enables more precise final crown control, achieving better manufacturing precision without substantially complicating the overall process.
Solution Approach 2:
The invention replaces conventional mechanical crown control methods with a more advanced system that combines mechanical rolling with thermal field control. By using controlled cooling systems to create thermal crowns that complement the mechanical crowns, the process achieves superior crown control precision and planarity compared to traditional purely mechanical approaches.
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
This approach enables the production of strips with optimal geometric and dimensional characteristics, maintaining productivity while ensuring each portion has the correct crown for desired thickness, profile, and flatness, enhancing downstream processing reliability and quality.
Implementation Method 1
a controlled cooling system to modulate thermal crowns
Implementation Method 2
work rolls with shaped profiles... to impart corresponding profiles to the strip
Data Source
AI summary
The invention concerns a method and a plant for producing flat rolled products, in order to obtain strips having a multiple crown transverse profile that subsequently have to be divided in a longitudinal direction into strips of a smaller width; the method provides a rolling step carried out in a rolling mill comprising roughing stands and finishing stands equipped with respective work rolls, in order to supply a strip of a determinate width.