Non-Oriented Electrical Steel Sheet for Low-Loss Punching Accuracy
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Solution Overview
Problem
Non oriented electrical steel sheets for integrally punched iron cores in motors, particularly for electric and hybrid vehicles, face challenges in achieving both excellent magnetic characteristics and small mechanical anisotropy, which affects shape accuracy and efficiency.
Innovation Solution
A non oriented electrical steel sheet with a specific chemical composition, including controlled levels of elements like Si, Al, Mn, P, S, N, and others, and a defined grain size and thickness, optimized through cold rolling and stress-relief annealing processes to achieve low iron loss and high magnetic flux density with reduced mechanical anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non oriented electrical steel sheet is used for integrally punched iron cores, then magnetic characteristics in rolling direction and transverse direction can be improved, but mechanical anisotropy increases causing deterioration of shape accuracy after punching
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (C: 0.005% or less, Si: 1.0-5.0%, Mn: 3.0% or less, P: 0.3% or less, S: 0.01% or less, N: 0.01% or less, B: 0.10% or less) and physical parameters (average grain size: 30-200 μm, sheet thickness: 0.10-0.35 mm) to achieve a balance between magnetic characteristics and mechanical anisotropy. The specific parameter ranges are optimized to reduce mechanical anisotropy while maintaining excellent magnetic properties in both rolling and transverse directions.
2Productivity
If the gap between stator and rotor is reduced to improve motor performance, then efficiency increases, but the requirement for high shape accuracy of iron core components becomes more critical
Solution Approach 1:
The patent controls mechanical anisotropy through parameter optimization of the steel sheet, achieving uniform mechanical properties in different directions. This reduces differential shrinkage and deformation during punching, ensuring high shape accuracy of the iron core even when the gap between stator and rotor is reduced for improved motor efficiency.
3Device complexity
If steel sheet blank is punched to hollow disc shape for integrally punched iron core, then manufacturing complexity is reduced, but mechanical anisotropy causes deterioration of shape accuracy
Solution Approach 1:
The patent optimizes the chemical composition parameters and microstructure parameters of the steel sheet to minimize mechanical anisotropy. This enables the steel sheet to maintain high shape accuracy during the punching process to create hollow disc-shaped iron cores, simplifying the iron core structure while ensuring manufacturing precision.
Solution Approach 2:
The patent performs preliminary optimization of the steel sheet's chemical composition and microstructure before the punching process. By pre-controlling the grain size (30-200 μm) and chemical composition, the material is prepared in advance to resist deformation and maintain shape accuracy during subsequent punching operations.
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 solution provides a steel sheet with excellent magnetic characteristics and small mechanical anisotropy, enhancing the performance and shape accuracy of integrally punched iron cores and motors, thereby improving the efficiency and reliability of electric and hybrid vehicles.
Implementation Method 1
optimized through cold rolling and stress-relief annealing processes
Implementation Method 2
optimized through cold rolling and stress-relief annealing processes
Data Source
AI summary
A non oriented electrical steel sheet includes, as a chemical composition, by mass %, 1.0% or more and 5.0% or less of Si, wherein a sheet thickness is 0.10 mm or more and 0.35 mm or less, an average grain size is 30 μm or more and 200 μm or less, an X1 value defined by X1=(2×B50L+B50C)/(3×IS) is less than 0.845, an E1 value defined by E1=EL/EC is 0.930 or more, and an iron loss W10/1k is 80 W/kg or less.