Levelling Roll with Segmented Expandable Chambers

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Solution Overview

Problem

Existing tension levelling systems for metal strips with planarity defects in transversal portions fail to provide fine levelling, often leading to breakage in brittle metals and superficial defects like scratches or imprints, and are not effective at varying feeding speeds.

Innovation Solution

A tension levelling system featuring levelling rolls with internally expandable cavities divided into independent chambers by sealing means, allowing for precise external profile modification through pressurized fluid expansion, combined with tension and stretching rolls to maintain stress within the elastic limit and regulate feeding speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single expandable cavity is used in the levelling roll, then the structure is simple, but fine levelling of specific transversal portions cannot be achieved

Engineering Contradiction:
Improvelevelling precisionVSAvoidcavity structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The internal cavity of the levelling roll is divided into multiple independent chambers through sealing elements, allowing each chamber to be pressurized independently. This segmentation enables localized expansion of specific roll portions to address planarity defects in targeted transversal areas of the metal strip, achieving fine levelling without requiring a completely complex external adjustment mechanism.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If high stress is applied to achieve levelling, then levelling effectiveness improves, but brittle metal strips may break

Engineering Contradiction:
Improvelevelling effectivenessVSAvoidmetal strip integrity
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The levelling roll features dynamically adjustable expansion through pressurized fluid insertion into the chambers. The expansion level can be precisely controlled and adjusted in real-time based on the specific requirements of different metal strip types and defect severities. This dynamic control allows the system to apply optimal stress levels that are sufficient for levelling while remaining below the breaking threshold for brittle materials.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of the levelling roll by controlling the pressure and volume of fluid inserted into the chambers. This parameter control enables precise regulation of the roll's expansion degree, allowing the application of controlled stress that achieves effective levelling while preventing excessive stress that would cause breakage in brittle metal strips.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the levelling roll is expanded to level defects, then planarity improves, but superficial defects like scratches or imprints may form

Engineering Contradiction:
ImproveplanarityVSAvoidsuperficial defects
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The sealing elements are positioned at specific locations within the internal cavity to create localized expansion zones. This allows the levelling roll to expand only in the specific transversal portions where planarity defects are detected, rather than uniform expansion across the entire roll surface. The localized quality approach ensures that metal strip areas without defects are not subjected to unnecessary contact pressure, preventing the formation of superficial defects like scratches or imprints while still achieving excellent planarity in the defective regions.

Inventive Principle:
Principle #3Local quality

4Manufacturing precision

If constant levelling pressure is applied, then levelling consistency is good, but the system cannot adapt to varying feeding speeds

Engineering Contradiction:
Improvelevelling consistencyVSAvoidspeed adaptability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The levelling system incorporates dynamic pressure control where the fluid pressure inserted into the chambers can be adjusted in real-time according to the feeding speed of the metal strip. When the feeding speed increases, the system can increase the pressure to maintain adequate contact force and levelling effectiveness. Conversely, when speed decreases, pressure is reduced to prevent over-compression. This dynamic adaptation maintains consistent levelling quality across varying operational speeds.

Inventive Principle:
Principle #15Dynamics

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 system effectively levels transversal defects in metal strips, prevents breakage, and reduces superficial defects, ensuring consistent levelling across varying speeds while maintaining stress near the yield limit for extended periods.

Implementation Method 1

at least one levelling roll (50) of a couple of levelling rolls is provided with an internal cavity (55) which comprises sealing means suitable to divide said internal cavity (55) in a plurality of chambers (60) each of which is expandable in independent way through insertion of a pressurized fluid

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

Each chamber 60 is expandable in independent way from the others through a pressurized fluid and it is able to elastically deform a correspondent external portion 56 of said levelling roll 50

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP1918035B1Tension levelling system for a metal strip
Publication Date: 2019.12.25 SELEMA
  • EP1918035B1 patent drawingFigure 1~2
  • EP1918035B1 patent drawingFigure 3
  • EP1918035B1 patent drawingFigure 4~6

AI summary

Tension levelling system (10) of a metal strip (14) comprising at least a couple of levelling rolls (50) of which at least one having an internal cavity (55) elastically expandable through insertion into the same of a pressurized fluid. The tension levelling system (10) comprises sealing means suitable to divide the internal cavity (55) in a plurality of chambers (60) each of which is expandable in independent way through insertion of a pressurized fluid.