Laser Resist Removal for Uniform Grooves in Electrical Steel

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Solution Overview

Problem

Existing methods for forming linear grooves on grain-oriented electrical steel sheets using etching struggle to achieve uniform groove shapes and maintain magnetic properties due to variations in resist pattern application and laser irradiation parameters.

Innovation Solution

A method involving the use of two or more laser irradiating devices with controlled beam diameter, incidence angle, and irradiation energy, along with image monitoring and adjustment systems to ensure precise resist removal and prevent melted or oxidized portions, is employed to form uniform linear grooves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser irradiation is used to remove resist, then productivity is improved, but magnetic properties deteriorate due to melted or oxidized portions

Engineering Contradiction:

Improveresist removal efficiencyVSAvoidmagnetic properties

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling laser irradiation conditions including energy density (0.1-10 J/cm²), wavelength selection, pulse duration, and scanning speed to remove resist without causing melting or oxidation of the steel sheet surface, thereby maintaining magnetic properties while achieving efficient resist removal

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses image monitoring systems to capture the resist removal process and creates a digital copy of the actual removal pattern, allowing real-time comparison with the target pattern and automatic adjustment to ensure uniform groove formation without damaging the magnetic properties

Inventive Principle:

Principle #26Copying

2Shape

If laser beam diameter is reduced to form narrow grooves, then magnetic domain refinement is improved, but groove shape uniformity deteriorates

Engineering Contradiction:

Improvemagnetic domain refinementVSAvoidgroove shape uniformity

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent implements feedback control by using image monitoring systems to detect actual groove formation in real-time, comparing it with the target groove shape, and automatically adjusting laser parameters to maintain uniform groove shapes with consistent width and depth, enabling precise magnetic domain refinement

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies dynamics by making the laser beam parameters adjustable and variable during the processing operation, allowing the system to adapt beam diameter, energy distribution, and scanning speed dynamically to maintain optimal groove uniformity across different positions on the steel sheet

Inventive Principle:

Principle #15Dynamics

3Productivity

If multiple laser irradiating devices are used to improve productivity, then resist removal speed is improved, but groove shape uniformity deteriorates due to overlapping irradiation

Engineering Contradiction:

Improveresist removal speedVSAvoidgroove shape uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the steel sheet surface into distinct processing zones, each covered by a separate laser irradiating device, with precisely controlled non-overlapping beam paths that eliminate interference effects while maintaining continuous processing coverage for high productivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces mechanical alignment methods with optical field control by using independent positioning systems for each laser device that precisely control beam placement through optical feedback, eliminating the need for mechanical adjustments and ensuring uniform groove formation across multiple irradiation zones

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 formation of narrow, deep grooves with uniform shapes, maximizing magnetic domain refinement and reducing iron loss in grain-oriented electrical steel sheets while maintaining high productivity.

Implementation Method 1

irradiating laser beams onto the steel sheet surface while repeating a laser scanning to remove a resist in portions irradiated with the laser beams

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

grooves are formed on the steel sheet surface by selectively etching portions on which the resist ink is not coated

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS12195816B2Linear groove formation method and linear groove forming apparatus, and method for manufacturing grain-oriented electrical steel sheet

Publication Date: 2025.01.14 JFE STEEL CORP

AI summary

The linear groove formation method includes a resist forming process of forming a coated resist on a surface of a steel sheet, a laser irradiating process of irradiating laser beams onto the steel sheet while repeating a laser scanning in a direction intersecting a rolling direction of the steel sheet cyclically in the rolling direction of the steel sheet to remove the coated resist in portions irradiated with the laser beams, and an etching process of forming linear grooves by etching portions of the steel sheet from which the coated resist is removed. In the laser irradiating process, the coated resist is removed by using two or more laser irradiating devices, with a certain irradiation energy, a certain beam diameter in a direction perpendicular to a laser scanning direction, and a certain incidence angle with respect to the surface of the steel sheet.