Laser-Etched Groove Formation on Electrical Steel With Low Thermal Impact
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Solution Overview
Problem
Existing methods for forming narrow grooves on grain-oriented electrical steel sheets using etching resist coating and laser irradiation face challenges in achieving high accuracy and uniformity, particularly in reducing groove width to 200 μm or less, while minimizing thermal effects that degrade magnetic properties.
Innovation Solution
A method involving forming an etching resist coating with a lightness L* of 0 to 70 in the CIELAB color space, irradiating a low-output laser (<1.5 kW) intersecting the rolling direction to remove the coating, and etching the metal strip to create grooves with a removal width of 200 μm or less and scanning rate of 111 m/s or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-output laser (1.5 kW or more) is used to remove the etching resist coating in a short time, then productivity is improved, but thermal diffusion in the steel substrate occurs which degrades magnetic properties
Solution Approach 1:
The patent changes the lightness parameter L* of the etching resist coating from conventional high values (79 or more) to a specific range (40 or more and less than 79). This parameter change allows the coating to absorb laser energy more effectively, enabling complete removal using low-output lasers (less than 1.5 kW) without causing thermal diffusion in the steel substrate, thus resolving the contradiction between productivity and magnetic property degradation.
2Manufacturing precision
If the beam diameter is reduced to form narrow grooves (200 μm or less), then manufacturing precision is improved, but it becomes difficult to remove the etching resist coating completely with low-output lasers
Solution Approach 1:
The patent modifies the lightness parameter L* of the etching resist coating to a specific range (40 or more and less than 79), which optimizes laser absorption characteristics. This enables complete removal of the coating even when using narrow beam diameters (200 μm or less) with low-output lasers, simultaneously achieving narrow groove formation and complete coating removal without requiring high laser power.
3Manufacturing precision
If multiple low-output lasers are installed and scanning speed is reduced to form narrow grooves, then manufacturing precision is improved, but device complexity and maintenance costs increase
Solution Approach 1:
The patent changes the lightness parameter L* of the etching resist coating to optimize laser absorption. This single parameter modification enables the use of a single low-output laser with a narrow beam to completely remove the coating and form narrow grooves (200 μm or less), eliminating the need for multiple lasers or complex scanning systems, thus reducing device complexity while maintaining manufacturing precision.
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 forms narrow grooves with reduced thermal effects, enhancing the magnetic properties of grain-oriented electrical steel sheets by allowing the etching resist coating to be removed well with low-output lasers, resulting in excellent magnetic properties.
Implementation Method 1
irradiating a laser with an output of less than 1.5 kW on the etching resist coating while scanning the laser to remove a portion of the etching resist coating
Implementation Method 2
etching a portion of the metal strip below the removed portion of the etching resist coating by chemical etching
Implementation Method 3
etching a portion of the metal strip below the removed portion of the etching resist coating by electrolytic etching
Data Source
AI summary
A grain-oriented electrical steel sheet with extremely excellent magnetic properties by removing an etching resist coating well to form narrow grooves on a metal strip surface even with low-output laser, while reducing thermal effects on the metal strip caused by laser irradiation, and a method for forming grooves on a metal strip surface, having forming an etching resist coating with 0 to 70 lightness L* on at least one side of the metal strip, irradiating laser with less than 1.5 kW output on the etching resist coating while scanning the laser in a direction that intersects a rolling direction of the metal strip to remove a portion of the etching resist coating irradiated by the laser, and etching a portion of the metal strip below the removed portion of the etching resist coating to form grooves, the lightness L* being a L* value in a CIELAB color space (CIE1976L*a*b* color space).