Rotating Electrical Machine Conductor Segment Welding
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Solution Overview
Problem
The existing manufacturing methods for rotating electrical machines face challenges in reducing blowholes in weld metal due to hydrogen and oxygen in the atmosphere, leading to potential weaknesses in joint strength between conductor segments.
Innovation Solution
The method involves forming conductor segments into a substantially U-shape with plastically deformed and tapered portions, allowing for increased solidification time of the weld metal and reducing blowhole formation by compressing the end portions along the radial and circumferential directions before welding, which enhances bond strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the end portions of conductor segments are reduced in sectional area through plastic deformation, then the heat input during joining is reduced and insulation performance is maintained, but the weld metal cannot achieve sufficient size and joint strength is insufficient
Solution Approach 1:
The conductor segment end portions are designed with non-uniform cross-sectional areas along the welding direction, creating a gradient structure where the area gradually increases from the tip toward the base. This allows the tip region to have low heat input capability while the base region provides sufficient weld metal volume for strong joints.
Solution Approach 2:
The invention transitions from considering only the cross-sectional area at the tip to incorporating the longitudinal dimension (length along welding direction). By extending the welding direction length while maintaining or reducing tip area, the total weld metal volume is increased without compromising insulation performance at the tip.
2Temperature
If the end portions of conductor segments are reduced in sectional area, then heat input during joining is reduced, but it becomes difficult to form weld metal of sufficient size
Solution Approach 1:
The invention compensates for reduced cross-sectional area by increasing the length dimension along the welding direction. The end portions are designed with extended length in the welding direction, creating a tapered geometry that accumulates sufficient weld metal volume despite smaller tip area.
Solution Approach 2:
The cross-sectional area parameter is changed along the welding direction to create a gradient distribution. The area is smaller at the tip (for low heat input) and progressively larger toward the base (for sufficient weld metal volume), optimizing both thermal and structural requirements.
3Object-affected harmful factors
If conventional welding is performed on conductor segments with reduced end portions, then blowing holes are formed in the weld metal due to water vapor from hydrogen and oxygen, but increasing solidification time to reduce blowholes is not addressed in existing methods
Solution Approach 1:
The geometry parameter of the end portions is changed to create a tapered shape with extended length. This geometric modification naturally extends the solidification path and time without requiring process parameter adjustments, allowing water vapor to escape during the prolonged solidification process.
Solution Approach 2:
The end portions are pre-formed with a specific tapered geometry before welding. This preliminary shaping creates the extended solidification path in advance, ensuring that blowholes can form and escape during welding without requiring additional time for process adjustment.
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 effectively reduces blowhole volume and improves the bond strength between conductor segments, ensuring a more robust joint without the need for expensive oxygen-free copper wires, thus enhancing the overall performance and cost-effectiveness of the rotating electrical machine.
Implementation Method 1
the thermal conductivity at the plastically deformed portion is lower than the thermal conductivity at the end portion prior to the forming process. Thus, when the plastically deformed portions are welded together... the weld metal takes longer to set or solidify
Implementation Method 2
the end portions of the conductor segments... are welded together
Data Source
AI summary
A rotating electrical machine includes a stator and a rotor. The stator winding includes a plurality of conductor segments inserted through the slots from one end surface of the stator core with end portions of the conductor segments projecting out beyond another end surface of the stator core. The conductor segments include an undeformed portion, a plastically deformed portion formed at the end portions thereof and a tapered portion. The plastically deformed portion has a dimension of the plastically deformed portion along a circumferential direction that is greater than a dimension of the undeformed portion along the circumferential direction and so that a dimension of the plastically deformed portion along a radial direction is smaller than a dimension of the undeformed portion along the radial direction. The conductor segments are welded together at tops of the plastically deformed portions thereof.