Electrolytic Etching Electrode Design for Grain Oriented Steel

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Solution Overview

Problem

Existing methods for electrolytic etching of grain oriented electrical steel strips face challenges in achieving uniformity of etched groove shapes along the width direction due to variations in current density, often resulting in deepening and widening of grooves at the edges, making it difficult to obtain a widthwise uniform shape.

Innovation Solution

A method and apparatus for continuous electrolytic etching that involves forming an etch mask on the steel strip, centering the strip to maintain alignment with the electrode, and using an electrode with insulating side surfaces to restrict current flow, ensuring uniform current density and preventing excessive etching at the edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the width of the electrode is made large to cover the entire steel strip width, then the current distribution becomes non-uniform with excessive current at the edges, but reducing the electrode width improves current uniformity while leaving edge portions uncovered

Engineering Contradiction:
Improveuniformity of etched groove shapeVSAvoidelectrode structure design
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The electrode is designed with different width characteristics at different locations: the central portion has a width matching the steel strip width to provide uniform current distribution, while the edge portions are reduced in width or made insulating to prevent excessive current concentration. This local differentiation of electrode properties resolves the contradiction between achieving uniform etching and managing current distribution.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The electrode structure is divided into multiple segments with different functional characteristics along the width direction. The central segment provides primary etching current, while edge segments are modified to reduce current flow. This segmentation allows independent optimization of different regions to achieve overall uniformity.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If conventional electrolytic etching is performed without flow restriction, then etching uniformity across the width direction cannot be achieved, but implementing flow restriction structures increases apparatus complexity

Engineering Contradiction:
Improvewidthwise uniformity of groove shapeVSAvoidelectrolyte flow control structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex flow restriction structures from the apparatus design. Instead of using physical barriers or flow control mechanisms, the invention achieves uniform etching through the electrode width design itself, which naturally guides current distribution without requiring additional flow control components.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If the electrode width is increased to ensure full coverage, then current density becomes non-uniform causing edge effects, but decreasing electrode width improves current uniformity while reducing coverage

Engineering Contradiction:
Improvecurrent density uniformityVSAvoidelectrode active area
Core Design Contradiction:
Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The electrode is designed with different width characteristics at different locations: the central portion has a width matching the steel strip width to provide uniform current distribution, while the edge portions are reduced in width or made insulating to prevent excessive current concentration. This local differentiation of electrode properties resolves the contradiction between achieving uniform etching and managing current distribution.

Inventive Principle:
Principle #3Local quality

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 effectively suppresses variations in etched groove shapes along the width direction, improving the uniformity and reducing unnecessary electrolysis, leading to enhanced electrolysis efficiency and reduced production losses.

Implementation Method 1

using an electrode with insulating side surfaces to restrict current flow

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 2

continuous electrolytic etching

Methodology Applied
Scientific EffectElectrolysis: Electrolysis

Data Source

PatentEP3266906B1Method for carrying out continuous electrolytic etching on oriented magnetic steel strip, and apparatus for carrying out continuous electrolytic etching on oriented magnetic steel strip
Publication Date: 2020.04.08 JFE STEEL CORP
  • EP3266906B1 patent drawingFigure 1
  • EP3266906B1 patent drawingFigure 2~3
  • EP3266906B1 patent drawingFigure 4~5

AI summary

A method for continuous electrolytic etching of a grain oriented electrical steel strip includes: a mask formation step of forming an etch mask on a surface of a grain oriented electrical steel strip 1 cold-rolled to final thickness with a linear exposed portion being exposed from the etch mask; a centering step of centering the grain oriented electrical steel strip with a position sensor 9 and a centering apparatus 8, which are placed immediately upstream of an electrolytic etching apparatus 4; and a groove formation step of performing an electrolytic etching process in which electrolytic etching is performed in the electrolytic etching apparatus to form a linear groove on the surface of the grain oriented electrical steel strip by passing electric current between conductor rolls 43a and 43b and an electrode placed in an electrolytic bath while the grain oriented electrical steel strip is brought into contact with the conductor rolls, the grain oriented electrical steel strip is immersed in an electrolytic bath 46, and the grain oriented electrical steel strip is facing the electrode 42.