Grain-Oriented Steel Sheet Curved Grooves Suppress Warpage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser beam machining of grooves in grain-oriented magnetic steel sheets leads to deformation, such as warpage, which reduces the performance of transformers by decreasing the space factor and increasing iron loss due to local stress concentration during lamination and compression.
Innovation Solution
Forming curved grooves with a specific standard deviation value (D/PL ≥ 0.02) and angle (≤ ±30°) on the surface of the steel sheet using laser beam machining, which reduces warpage and maintains low iron loss, and optionally forming grooves on both surfaces to further minimize deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If grooves are formed by laser beam machining on the surface of grain-oriented magnetic steel sheet, then iron loss is reduced, but warpage and deformation occur
Solution Approach 1:
The patent applies curvature principle by forming grooves with a specific curved profile instead of straight lines. The groove cross-section is designed with a curvature radius R satisfying 0.05mm < R ≤ 0.5mm, and the groove center line forms an angle θ of 0° < |θ| ≤ 30° with the sheet surface normal. This curved geometry distributes stress more evenly and prevents the warpage that occurs with sharp or linear grooves, while still achieving the iron loss reduction benefit.
Solution Approach 2:
The patent utilizes parameter changes by optimizing multiple groove parameters simultaneously: depth (5-50μm), width (10-300μm), curvature radius (0.05-0.5mm), and angle (0°-30°). By carefully controlling these parameters within specific ranges, the patent achieves a balance between reducing iron loss through groove formation and minimizing warpage by avoiding excessive stress concentration that would cause deformation.
2Loss of energy
If grooves are formed to reduce iron loss, then magnetic domain wall interval is narrowed, but local stress concentration increases during lamination and compression
Solution Approach 1:
The curved groove profile with radius R > 0.05mm eliminates sharp corners and concentrated stress points. The gradual curvature distributes mechanical stress evenly during lamination and compression processes, preventing local stress concentration while maintaining the groove's ability to narrow magnetic domain wall intervals and reduce iron loss.
Solution Approach 2:
By optimizing groove depth (5-50μm) and curvature radius (0.05-0.5mm) parameters, the patent achieves sufficient magnetic domain wall narrowing for iron loss reduction without creating excessive stress concentrations. The controlled angle θ (0° < |θ| ≤ 30°) ensures the grooves are neither too shallow to be effective nor too deep to cause stress problems.
3Loss of energy
If grooves are formed on steel sheet surface, then iron loss is reduced, but space factor of transformer decreases due to deformation
Solution Approach 1:
The curved groove design minimizes warpage and deformation that would otherwise reduce the transformer's space factor. By distributing stress evenly through the curved profile, the patent maintains better dimensional stability of the steel sheet, ensuring higher space factor in the final transformer while still achieving iron loss reduction through the groove structure.
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
The method effectively suppresses warpage and maintains low iron loss, enhancing the transformer's performance by increasing the space factor and reducing stress concentration, thus achieving improved iron loss characteristics.
Implementation Method 1
a groove (a laser-irradiated portion) in which a steel sheet (a steel sheet 1 to be laser-irradiated) is melted and evaporated by laser irradiation
Implementation Method 2
a groove (a laser-irradiated portion) in which a steel sheet (a steel sheet 1 to be laser-irradiated) is melted and evaporated by laser irradiation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A grain-oriented magnetic steel sheet includes grooves each of which extends in a direction intersecting a transportation direction, the grooves being formed at predetermined pitches PL in the transportation direction by laser beam irradiation, in which a relationship between a standard deviation value D and the pitch PL satisfies the following expression (1), the standard deviation value D being a standard deviation of distances between a linear approximation line, which is obtained from a center line of each of the grooves in a groove width direction by a least-squares method, and respective positions on the center line, and an average angle formed between tangent lines of the respective positions on the center line and a direction perpendicular to the transportation direction is more than 0° to 30°. [Expression 1] 0.02≤D/PL