Grain-Oriented Electrical Steel Sheet Groove Formation via Electrolytic Etching
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Solution Overview
Problem
Existing methods for magnetic domain refining in grain-oriented electrical steel sheets face challenges such as increased iron loss during stress relief annealing and difficulties in achieving both low iron loss and high productivity, particularly due to issues with resist film application and electrolytic etching.
Innovation Solution
The method involves applying a photosensitive resin resist film to a steel sheet, patterning it through photoexposure, and using electrolytic etching with a high current density to form grooves without residual resist, preventing unintended etching and maintaining low iron loss and high productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical etching is used to form grooves for magnetic domain refining, then heat-resistant magnetic domain refining is achieved, but the etching rate is limited requiring excessively large equipment and the uniformity of groove shape deteriorates
Solution Approach 1:
The patent replaces chemical etching with electrolytic etching. Instead of using chemical reactions between acid and the steel sheet surface, the invention uses electrical current to selectively remove material at the groove positions. This substitution enables much higher etching rates while maintaining precise control over groove shape and dimensions, directly resolving the contradiction between heat-resistant magnetic domain refining and productivity.
2Ease of manufacture
If gravure offset printing is used to apply resist film, then continuous or discontinuous linear grooves can be formed, but the doctor blade wears leading to residual ink in non-application regions causing unintended etching
Solution Approach 1:
The patent replaces gravure offset printing with a combination of screen printing and photolithography. Instead of using a mechanical gravure roller that is subject to wear, the invention uses a screen print to apply resist followed by UV photoexposure through a mask. This eliminates the wear problem of the doctor blade and ensures precise groove positioning without residual ink contamination, resolving the contradiction between ease of manufacture and manufacturing precision.
3Productivity
If high electrolytic etching current density is used to increase productivity, then etching speed increases, but dielectric breakdown of resist occurs in non-application regions causing poor magnetic domain refining
Solution Approach 1:
The patent applies a protective coating to the entire steel sheet surface before electrolytic etching. This preliminary protective layer prevents dielectric breakdown of the resist in non-application regions even when high current density is used. By preparing this protective barrier in advance, the invention enables high-speed etching while maintaining reliable magnetic domain refining quality, resolving the contradiction between productivity and reliability.
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 grain-oriented electrical steel sheets with improved heat-resistant magnetic domain refining, maintaining low iron loss and high productivity even after stress relief annealing.
Implementation Method 1
applying a photosensitive resin resist film to a steel sheet, patterning it through photoexposure
Implementation Method 2
using electrolytic etching with a high current density to form grooves
Data Source
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AI summary
Provided is a manufacturing method for a grain-oriented electrical steel sheet with which it is possible to achieve both good iron loss and high productivity. In groove formation for magnetic domain refinement, a resist containing a photosensitive resin is applied, photoexposed, and developed to form an exposed steel substrate portion having a linear shape. Subsequently, electrolytic etching is performed at current density ρ = I/S of 7.5 A/cm2 or more with respect to the exposed steel substrate portion, where I represents current supplied to an electrode and S represents surface area of the exposed steel substrate portion in a steel sheet surface of equal surface area to the electrode.