Stator Lamination Interlocks for Consistent Holding Force
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Solution Overview
Problem
Existing stator production methods for electrical machines face significant fluctuations in separating forces due to material variations and tool wear, leading to inconsistent holding forces and increased magnetic flux losses.
Innovation Solution
The method involves simultaneously punching and axially reassembling T-shaped sheet metal laminations with undercuts, creating a defined interlocking connection that minimizes material cohesion and eliminates the influence of tool wear, allowing for precise separation and reassembly of stator segments with minimal magnetic flux losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If incomplete punching is used to create predetermined breaking points, then the T-segments remain connected as a stator base body, but significant fluctuations in separating forces occur due to material fluctuations and tool wear
Solution Approach 1:
The punching tool is segmented into multiple independent punching elements arranged in a matrix, where each element can be independently adjusted. This allows precise control over the punching depth for each element, enabling consistent creation of undercuts without the fluctuations caused by tool wear or material variations in incomplete punching methods.
Solution Approach 2:
The undercut is created as a preliminary feature during the punching process itself, before the segments need to be separated. By pre-forming the undercut geometry with defined dimensions, the separation force becomes predictable and consistent, eliminating the need for subsequent breaking or fracturing operations.
2Stability of the object's composition
If incomplete punching creates predetermined breaking points, then segments remain connected, but plastic deformation reduces holding forces after joining
Solution Approach 1:
The punching elements are segmented and independently controllable, allowing the undercut to be created with precise geometry that avoids excessive plastic deformation. The undercut acts as a mechanical interlock feature rather than relying on deformed material, preserving the holding force.
Solution Approach 2:
The punching depth parameter is precisely controlled to create the undercut geometry without causing significant plastic deformation. By adjusting the punching depth to just sufficient for undercut creation, the material remains largely elastic and maintains its original strength properties after joining.
3Manufacturing precision
If complete punching is used to separate segments, then material cohesion is eliminated, but the segments cannot remain connected as a stator base body
Solution Approach 1:
The punching tool uses multiple segmented elements where only specific elements create the undercut while others maintain connection. This selective segmentation allows the stator base body to remain intact while providing defined separation forces at the undercut locations.
Solution Approach 2:
The undercut feature is applied locally at specific positions where separation is desired, while the rest of the stator base body maintains its integrity. This localized modification allows complete punching benefits at critical points without compromising overall structural connection.
4Manufacturing precision
If undercuts are punched out in the tangential direction, then holding forces become consistent and tool wear influence is eliminated, but the manufacturing process becomes more complex
Solution Approach 1:
The punching tool is divided into multiple independent elements arranged in a matrix, with each element controllable individually. This segmentation allows the complexity to be distributed across simple, identical modular elements rather than requiring a single complex tool, making the system more manageable and precise.
Solution Approach 2:
The segmented punching elements are universal and identical in design, each capable of creating the same undercut geometry. This multi-functionality allows the same simple element to be reused multiple times in different positions, reducing overall system complexity while achieving precise, consistent results.
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 ensures consistent holding forces and reduced magnetic flux losses by using a defined undercut geometry, allowing for efficient winding and assembly with minimal deformation, thus improving the reliability and performance of the stator.
Implementation Method 1
In a first step, all T-shaped sheet metal laminations of a lamination layer are in this case simultaneously separated from a single sheet metal layer during punching
Implementation Method 2
in a second step they are pressed axially back into their original position
Implementation Method 3
an undercut is punched out in the tangential direction, as a result of which the individual T-segments remain connected to each other over the entire circumference as the stator base body
Implementation Method 4
the frictional connection (material cohesion) is eliminated by means of complete punching
Data Source
AI summary
A method for producing a stator (14), in particular for an EC motor (13), as well as a stator (14) produced using said method and an electrical machine (12) produced using said method, which comprises the following method steps: —T-shaped lamination segments (20) of a lamination layer (21) are first completely punched out of a sheet metal region in the axial direction (8) —the lamination segments (20) are then pressed back against the axial direction (8) into the original axial position of the sheet metal region (18), wherein a yoke region (24) is punched out on the lamination segments (20), from which region a respective tooth (26) extends in a radially inward direction —wherein connecting lugs (30) of a first lamination segment (20) and a corresponding recess (31) of a second adjacent lamination segment (20) are designed such that these form an undercut (32) with respect to the tangential direction (9), which undercut keeps the adjacent lamination segments (20) connected to one another in the tangential direction (9) as an annular lamination layer (21) —axial stacking of the individual lamination layers (21) on top of one another to form a stator base body (17) comprising stator segments (22).