Six-High Rolling Mill Stand for Ultra-Thin Strip Geometry Control
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Solution Overview
Problem
Existing six-high rolling mill stands are either not suitable for hot rolling long uninterrupted sequences of ultra-thin steel strips with a thickness <0.8 mm or they are not optimally suited for producing ultra-thin strips with good geometry and low production costs.
Innovation Solution
A six-high rolling mill stand with work roll bending blocks and intermediate roll bending blocks, featuring intermediate rolls with a specific tapered shape and a roll crown that follows an even function, allowing for effective adjustment of the strip's profile and flatness. This configuration reduces Hertz' stresses and work roll wear, enabling longer uninterrupted rolling sequences and improved strip geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a four-high rolling mill stand is used for hot rolling ultra-thin strip, then the rolling forces become very high when producing ultra-thin strip with thickness ≤0.8 mm, but the mill stand cannot maintain long uninterrupted rolling sequences
Solution Approach 1:
The patent implements a six-high rolling mill configuration where intermediate rolls are nested between the work rolls and backup rolls. The intermediate rolls have a crowned surface that contacts the work rolls, while the backup rolls support the intermediate rolls. This nested arrangement distributes the rolling forces across multiple roll interfaces, reducing the force concentration on individual work rolls and enabling sustained production of ultra-thin strip with thickness ≤0.8 mm
2Manufacturing precision
If conventional six-high rolling mill stands are used, then they are not optimally suited for producing ultra-thin strips with good geometry, but adding intermediate roll bending blocks increases device complexity
Solution Approach 1:
The intermediate rolls are pre-crowned with a specific profile during manufacturing. This preliminary shaping of the intermediate roll surfaces allows them to automatically compensate for flatness defects in the strip during rolling. The crowned intermediate rolls transfer their pre-formed geometry to the work rolls through contact, enabling good strip geometry without requiring complex real-time adjustment mechanisms
Solution Approach 2:
The patent incorporates bending blocks for both the work rolls and intermediate rolls, allowing dynamic adjustment of roll curvature during operation. The intermediate roll bending blocks enable modification of the intermediate roll crown profile to match varying strip requirements. This dynamic adaptability optimizes strip geometry control while maintaining a relatively simple structural configuration
3Manufacturing precision
If intermediate rolls with S-shaped roll crown are used, then the roll crown follows an odd function with respect to the centre, but this creates asymmetric deformation and affects strip profile control
Solution Approach 1:
The patent deliberately employs asymmetric work rolls with tapered portions that are not symmetric with respect to the roll center. The upper and lower work rolls have opposite asymmetric configurations, creating a controlled asymmetric rolling gap. This asymmetric design compensates for material flow variations and enables precise profile control of the rolled strip, transforming the potential disadvantage of asymmetric deformation into a beneficial control mechanism
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 proposed solution allows for hot rolling of ultra-thin steel strips with a thickness <0.8 mm in long uninterrupted sequences, achieving good geometry and low production costs, while minimizing work roll wear and maintaining control over the strip's profile and flatness.
Implementation Method 1
work roll bending blocks for bending the work rolls in vertical direction
Implementation Method 2
intermediate roll bending blocks for bending the intermediate rolls in vertical direction
Implementation Method 3
two axial shifting devices for axially shifting the work rolls
Implementation Method 4
two intermediate rolls for supporting the work rolls in vertical direction
Implementation Method 5
two backup rolls for supporting the intermediate rolls in vertical direction
Implementation Method 6
This configuration reduces Hertz' stresses and work roll wear
Data Source
AI summary
A six-high rolling (also known as sexto) mill stand that is suited for hot rolling an intermediate strip into a thin strip that is less than 0.8 mm thick. A combined casting and rolling installation that includes the six-high rolling mill stand allowing for hot rolling in long uninterrupted sequences, without any change of the work rolls to obtain a strip with good geometry due to moderate rolling forces.