Grain-Oriented Electrical Steel Sheet Tension Control
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Solution Overview
Problem
Conventional methods for manufacturing grain-oriented electrical steel sheets fail to consistently achieve low transformer noise levels due to variations in magnetostrictive properties, and existing parameters are inadequate for selecting sheets with optimal noise reduction properties.
Innovation Solution
The solution involves controlling the velocity change behavior of magnetostrictive vibration by limiting the number of acceleration/deceleration points to 4 and the magnitude of velocity level change to 3.0×10−4 sec−1 or less, achieved by adjusting the tension of forsterite films and insulating coatings, with a front/rear difference in total tension less than 0.5 MPa and a front/rear difference in forsterite film tension of 0.5 MPa or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for manufacturing grain-oriented electrical steel sheets are used, then production process is simple, but transformer noise levels vary and cannot consistently achieve low noise
Solution Approach 1:
The patent applies parameter changes by precisely controlling magnetostrictive vibration velocity characteristics (limiting acceleration/deceleration points to 4 per period and velocity level change to 3.0×10^-4 sec^-1 or less) and adjusting film tension parameters (front/rear difference in total tension < 0.5 MPa, front/rear difference in forsterite film tension ≥ 0.5 MPa). These parameter controls enable consistent low noise performance while maintaining conventional manufacturing processes.
2Object-generated harmful factors
If magnetic flux density B8 is increased to reduce magnetostriction, then magnetostrictive amplitude decreases, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of increasing magnetic flux density B8 to reduce magnetostriction, the patent changes parameters related to magnetostrictive vibration velocity characteristics and film tension. By controlling acceleration/deceleration points and velocity level change, and by adjusting forsterite film and insulating coating tension, the patent achieves reduced magnetostrictive amplitude without modifying the fundamental magnetic properties or manufacturing complexity.
3Object-generated harmful factors
If conventional magnetostriction reduction techniques are applied, then magnetostrictive amplitude is reduced, but velocity change behavior of magnetostrictive vibration is not controlled, resulting in inadequate noise reduction
Solution Approach 1:
The patent extends conventional magnetostriction reduction by additionally controlling velocity change behavior parameters. Specifically, it limits acceleration/deceleration points to 4 per period and velocity level change to 3.0×10^-4 sec^-1 or less, while also controlling film tension parameters. This comprehensive parameter control ensures both reduced magnetostrictive amplitude and controlled velocity change behavior, achieving reliable noise reduction.
4Measurement precision
If existing parameters are used for selecting electrical steel sheets, then selection process is simple, but noise prediction accuracy is inadequate
Solution Approach 1:
The patent introduces new parameters for noise prediction: magnetostrictive vibration velocity characteristics (number of acceleration/deceleration points, velocity level change magnitude) and film tension parameters (front/rear differences). These parameter changes enable accurate noise prediction while using standard measurement techniques that do not significantly increase measurement complexity.
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 results in a grain-oriented electrical steel sheet with enhanced noise properties and allows for accurate prediction of transformer noise, achieving better noise reduction and iron loss performance compared to conventional techniques.
Implementation Method 1
magnetostrictive properties of the grain-oriented electrical steel sheet satisfy conditions I and II, shown below, I: the number of acceleration/deceleration points that are present in a magnetostriction velocity level dλ/dt in one period of magnetostrictive vibration is 4
Data Source
AI summary
Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.