Angled Pressure Finger Seating for Helical Lamination Stacks
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Solution Overview
Problem
The seating of pressure fingers in laminated cores of electric machines is imprecise due to manufacturing deviations and angular misalignments, leading to plastic deformation and potential loosening during operation.
Innovation Solution
The pressure fingers are angled relative to the radial section and plug pin, compensating for the helical angle deviation from 90°, allowing precise alignment and full contact with the sheet metal surface, reducing plastic deformation and loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure fingers are inserted with conventional perpendicular alignment to the lamination surface, then assembly is simple, but misalignment and plastic deformation occur due to helical angle deviation
Solution Approach 1:
The plug pin is designed with an asymmetric angular deviation relative to the radial section, specifically angled by the helix angle (e.g., 15 degrees) to match the helical arrangement of laminations. This asymmetric configuration enables the pressure finger to align precisely with the non-perpendicular slot axis formed by circumferential offsets, eliminating misalignment and plastic deformation while maintaining structural integrity.
2Manufacturing precision
If tight tolerances are used for pressure finger engagement in slots, then alignment precision improves, but pressure fingers become prone to loosening due to high surface pressure
Solution Approach 1:
The plug pin is angled at the helix angle (e.g., 15 degrees) relative to the radial section, changing the geometric parameter of the pressure finger configuration. This angular parameter change allows the pressure finger to engage the slot with optimized contact mechanics, distributing surface pressure more evenly and preventing both misalignment and loosening during operation.
3Ease of manufacture
If pressure fingers are allowed to move angularly during stamping, then manufacturing flexibility increases, but misalignment and deformation occur during pressing
Solution Approach 1:
The plug pin is pre-angled at the helix angle (e.g., 15 degrees) relative to the radial section during manufacturing. This preliminary angular configuration ensures that when the pressure finger is inserted into the slot, it automatically aligns with the correct orientation, preventing misalignment and deformation during the pressing operation while maintaining ease of assembly.
Data Source
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AI summary
A laminated core 10 for a stator 12 arranged about a central axis AM or a rotor of an electric machine rotatable about the central axis AM, wherein several individual laminations 14, assembled into sub-cores 16, are provided, and each individual lamination 14 has a circumferential offset to form a helix angle αS of the laminated core 10 relative to the individual lamination 14 adjacent in an axial direction to the central axis AM, and the sub-cores 16 are aligned with each other forming an axially extending axial gap 18, and wherein several pressure fingers 20 are inserted circumferentially between sub-cores 16. The pressure finger has a radial section 22 and a plug pin 24, wherein the radial section 22 and the plug pin 24 are angled to each other at a rate on the order of the helix angle αS. A clean, flat bearing surface of the pressure finger 20 on the respective laminated core 10 or sub-core 20 is ensured.