Eight-High Rolling Mill Shoulder Shifting for Edge Drop Control
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Solution Overview
Problem
The existing eight-high rolling mills suffer from detrimental contact portions between rolls, leading to decreased shape control performance and increased shape change due to rolling load variations.
Innovation Solution
The implementation of a work roll support roll group with tapered shoulders and shift devices to align these shoulders with the strip width ends, eliminating detrimental contact portions and enhancing roll support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If second intermediate rolls are provided without tapered shoulders, then the structure is simpler, but detrimental contact portions occur outside strip width leading to decreased shape control performance
Solution Approach 1:
The patent applies asymmetry by providing tapered shoulders only on specific rolls (work rolls and first intermediate rolls) while leaving other rolls (second intermediate rolls and back-up rolls) without tapered shoulders. This asymmetric configuration eliminates detrimental contact portions at critical locations where shape control is most needed, while maintaining structural simplicity elsewhere in the rolling mill system.
Solution Approach 2:
The patent implements local quality by selectively applying tapered shoulders only to specific rolls that require precise shape control (work rolls and first intermediate rolls), rather than uniformly equipping all rolls with tapered shoulders. This localized approach optimizes shape control performance at critical contact points while avoiding unnecessary complexity in other areas.
2Area of stationary object
If rolls have contact portions outside strip width, then the support coverage is increased, but shape stabilization performance decreases due to large shape change with rolling load variations
Solution Approach 1:
The asymmetric distribution of tapered shoulders ensures that contact portions outside strip width are eliminated only where they cause harmful effects (at work rolls and first intermediate rolls), while maintaining adequate support coverage through properly positioned tapered shoulders within or near the strip width boundaries.
Solution Approach 2:
The patent applies different contact characteristics to different rolls based on their specific functions. Work rolls and first intermediate rolls have tapered shoulders positioned to prevent detrimental external contact, while other rolls maintain configurations optimized for their respective support roles, achieving local optimization of both coverage and stability.
3Productivity
If small-diameter work rolls are used for rolling hard metal strip, then the rolling efficiency is improved, but edge drop increases due to decreased shape control performance
Solution Approach 1:
The asymmetric configuration of tapered shoulders on small-diameter work rolls and first intermediate rolls eliminates detrimental contact portions that would otherwise compromise shape control. This enables small-diameter rolls to maintain both high rolling efficiency and precise edge control when processing hard metal strips.
Solution Approach 2:
By optimizing the local contact characteristics at the work roll and first intermediate roll interfaces through selective tapered shoulder positioning, the patent enables small-diameter rolls to achieve both high productivity and precise shape control, preventing edge drop while maintaining rolling efficiency.
Data Source
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AI summary
Provided are one pair of first intermediate rolls 3a and 3b that have tapered roll shoulders 3c and 3d at point-symmetrical positions in an up-down axis direction and support one pair of work rolls 2a and 2b that roll a metal strip 1, one pair of second intermediate rolls 5a and 5b that have tapered roll shoulders 5c and 5d at point-symmetrical positions in the up-down axis direction opposite to those of the first intermediate rolls 3a and 3b and support the first intermediate rolls 3a and 3b, one pair of back-up rolls 7 that support the second intermediate rolls 5a and 5b, support roll groups 12 or support bearings 13 that are provided on an entry side and/or an exit side of the work rolls 2a and 2b, shift cylinders 50 that shift positions of the roll shoulders 3c and 3d in an axis direction such that the positions align with strip width ends of the metal strip 1, and shift cylinders 51 that shift positions of the roll shoulders 5c and 5d in an axis direction such that the positions align with strip width ends of the metal strip 1. As a result, a hard metal strip can more efficiently be rolled as compared with the prior art, and hence a metal strip small in edge drop and high in product quality is obtained.