Laser-Patterned Resist Transfer for Uniform Steel Sheet Grooves

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Solution Overview

Problem

Existing methods for forming grooves on grain-oriented electrical steel sheets struggle to achieve uniformity and accuracy, particularly in the widthwise direction, leading to defects such as edge waves and edge cracks, which can result in incomplete removal of the etching resist coating and degradation of magnetic properties.

Innovation Solution

A method involving the application of an etching resist coating on a roller, followed by laser removal of a portion of the coating while scanning in an axial or inclined direction, transferring the pattern to the metal strip, and then etching the uncoated areas to form uniform grooves, using a low-output laser and specific laser profiles to minimize thermal effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a laser beam is used to locally remove the etching resist coating on the steel sheet surface, then uniform grooves can be formed with high precision, but the laser irradiation causes distortion and melting of the steel substrate which damages the magnetic properties

Engineering Contradiction:

Improvegroove uniformityVSAvoidthermal damage to steel substrate

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary substance (etching resist coating) that absorbs the laser energy and undergoes decomposition or phase change to remove the coating material without directly irradiating the steel substrate. This mediator protects the steel from thermal damage while still achieving the desired coating removal pattern for groove formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical-chemical parameters of the etching resist coating (such as adding laser-absorbing pigments like carbon black, adjusting coating thickness, or modifying composition) to enhance its laser absorptivity. This allows the coating to be selectively removed by laser irradiation at lower energy levels that do not damage the underlying steel substrate, thus resolving the contradiction between removal efficiency and substrate protection.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a high-output laser is used to remove the etching resist coating quickly, then thermal diffusion is suppressed and magnetic properties are maintained, but it becomes difficult to form uniform grooves on metal strip with low flatness or defective shape portions

Engineering Contradiction:

Improvecoating removal speedVSAvoidgroove uniformity on defective portions

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the optical parameters of the etching resist coating by incorporating laser-absorbing pigments (such as carbon black at concentrations of 1-50 wt%) or using coatings with specific absorption coefficients. This enables the coating to absorb laser energy efficiently even at high irradiation speeds, allowing rapid coating removal while maintaining uniform groove formation on defective metal strip surfaces without requiring excessive laser power that would cause substrate damage.

Inventive Principle:

Principle #35Parameter changes

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 uniform grooves even on defective shape portions, resulting in grain-oriented electrical steel sheets with excellent magnetic properties by reducing iron loss and maintaining the integrity of the steel substrate.

Implementation Method 1

irradiating a laser on the roller while scanning the laser in an axial direction of the roller or in a direction inclined to the axial direction to remove a portion of the coating agent for etching resist coating formation irradiated by the laser

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

bringing the roller into contact with at least one side of the metal strip to transfer the coating agent for etching resist coating formation to the at least one side of the metal strip

Methodology Applied

Scientific EffectContact transfer:

Implementation Method 3

etching a portion of the steel sheet surface below the unapplied area corresponding to the removed portion of the coating agent for etching resist coating formation by chemical etching or electrolytic etching

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 4

Methodology Applied

Scientific EffectElectrolytic etching: Electrolysis

Data Source

PatentUS12467104B2Method for forming grooves on metal strip surface and method for manufacturing grain-oriented electrical steel sheet

Publication Date: 2025.11.11 JFE STEEL CORP

AI summary

A method for forming grooves on a surface of a metal strip, having applying a coating agent for etching resist coating formation to a roller; then, irradiating a laser on the roller while scanning the laser in an axial direction of the roller or in a direction inclined to the axial direction to remove a portion of the coating agent for etching resist coating formation irradiated by the laser; then, bringing the roller into contact with at least one side of the metal strip to transfer the coating agent for etching resist coating formation to the at least one side of the metal strip, with an unapplied area corresponding to the removed portion of the coating agent for etching resist coating formation.