Helical Core Manufacturing: Notch-Based Bending for Rotating Electrical Machines
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Solution Overview
Problem
The existing methods for manufacturing helical cores for rotating electrical machines face challenges in reducing material costs and improving yield due to issues like unnecessary metal waste, complex shapes, and potential deformation during processing, which affect magnetic characteristics and strength.
Innovation Solution
A manufacturing method involving forming a yoke portion and tooth portions on a belt-shaped metal plate, followed by notching between the tooth portions, and then bending the plate into a helical shape within a predetermined dimension, with optional heating and stress relief annealing to prevent deformation and optimize thickness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the belt-shaped metal plate is bent into a helical shape by bending in the plate surface, then the outer circumferential side of the yoke extends more largely than the inner circumferential side, but the thickness of the outer circumferential side becomes thinner than the inner circumferential side
Solution Approach 1:
A notch is formed at a predetermined position on the belt-shaped metal plate before the helical bending process. This preliminary action creates a stress relief zone that prevents excessive thinning of the outer circumferential side during bending, thereby maintaining thickness uniformity while achieving the helical shape.
2Productivity
If many unused portions occur in the metal plate used for punching, then the yield of the metal plate decreases, but the material costs increase
Solution Approach 1:
The metal plate is utilized more efficiently by forming the helical core directly from a belt-shaped plate with optimized dimensions, reducing the need for excessive material and minimizing unused portions after punching, thereby increasing yield and reducing material waste.
3Reliability
If magnetic powder is filled in the gap at the outer circumferential side, then magnetic characteristics and stiffness are recovered, but the manufacturing process becomes more complex
Solution Approach 1:
The notch is formed in advance on the metal plate before bending, which prevents gap formation at the outer circumferential side during the helical bending process. This preliminary preventive measure eliminates the need for subsequent magnetic powder filling, thereby recovering magnetic characteristics while simplifying the manufacturing process.
4Ease of manufacture
If the distance between the bending start position and the notch position is large, then the bending process is more flexible, but the effectiveness of the notch in preventing thinning is reduced
Solution Approach 1:
The distance between the bending start position and the notch position is optimized within a specific range. This parameter optimization ensures that the notch effectively prevents thinning of the outer circumferential side while maintaining sufficient bending flexibility for practical manufacturing.
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 reduces material waste, maintains magnetic characteristics, and decreases production costs by ensuring even thickness and preventing deformation, thus enhancing the yield and flexibility of helical core production.
Implementation Method 1
optional heating and stress relief annealing to prevent deformation and optimize thickness distribution
Implementation Method 2
optional heating and stress relief annealing to prevent deformation and optimize thickness distribution
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A manufacturing method of a helical core for a rotating electrical machine includes: first step forming a yoke portion extending along one direction and tooth portions protruding toward a width direction of the yoke portion from a first side edge of the width direction, with respect to a belt-shaped metal plate extending along the one direction; second step forming a notch at a position between tooth portions of the yoke portion after the first step; and third step processing the belt-shaped metal plate into a helical shape by applying bending to the metal plate so that the belt-shaped metal plate is curved toward the width direction sequentially from a portion where the notch is formed after the second step, and in the third step, a distance between a position where the application of bending starts and the position where the notch is formed is limited to within a predetermined dimension.