Laminated Core Welding Mark Design for Rotary Electric Machines
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Solution Overview
Problem
Poor connection of steel plates in laminated cores due to inadequate welding can lead to stress concentration and crack formation, which affects the stability and performance of rotary electric machines.
Innovation Solution
A laminated core design featuring a line-shaped welding mark with a fluctuating welding depth longer than the steel plate thickness, formed by a pulse-based welding process, which relieves stress concentration and prevents crack occurrence by creating a stable connection between steel plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional welding method is used to connect steel plates, then the welding process is simple and fast, but stress concentration occurs at the welding mark and cracks may form
Solution Approach 1:
The welding mark is designed with non-uniform depth distribution, creating different local qualities within the same welding mark. The deeper portions provide stronger connection while the shallower portions reduce stress concentration, allowing the welding mark to simultaneously achieve strong connection and stress relief across different locations.
Solution Approach 2:
The welding mark employs a curved or wavy depth profile instead of a straight uniform depth. This curvature in the welding mark geometry allows stress to be distributed more evenly through the steel plates, preventing stress concentration at any single point while maintaining overall connection strength.
2Ease of manufacture
If a uniform depth welding mark is used, then the welding process is simple, but stress concentration occurs at the facing portion between steel plates
Solution Approach 1:
The welding parameters are changed to create a non-uniform depth profile in the welding mark. By varying the welding energy input or welding head movement during the welding process, the welding mark depth is dynamically adjusted to optimize both connection strength and stress distribution, moving beyond simple uniform depth welding.
3Strength
If the welding depth is increased to improve connection, then connection strength improves, but stress concentration and crack risk increase
Solution Approach 1:
Different portions of the welding mark have different depths optimized for different functions. Deeper portions maximize connection strength where needed, while shallower portions minimize stress concentration and crack risk, allowing the overall welding mark to achieve strong connection without excessive crack susceptibility.
Solution Approach 2:
The curved depth profile of the welding mark distributes stress more evenly through the material, preventing the formation of stress concentration points that would lead to cracks. The curvature ensures that no single location experiences excessive stress even when overall welding depth is increased for stronger connection.
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
The fluctuating welding depth ensures stable connection of steel plates, suppressing crack formation and enhancing the reliability of laminated cores used in rotary electric machines.
Implementation Method 1
a pulse generating step of generating a plurality of pulses of welding energy by a welding device; a welding step in which the welding energy is applied to a welding position of an end surface where the plurality of steel plates are exposed
Data Source
AI summary
A laminated core has a plurality of steel plates that are laminated in a thickness direction. The laminated core has a line shaped welding mark connecting a plurality of steel plates. The welding mark extends over the plurality of steel plates at the end face where the plurality of steel plates are exposed. The welding mark has a welding depth which fluctuates with a wavelength that is longer than the thickness of the steel sheet. The welding mark has a continuous portion in which the welding depth extends over a plurality of steel plates without fluctuation. Furthermore, the welding mark has a fluctuation portion in which the welding depth periodically fluctuates over a plurality of steel plates. The depth in the continuous portion is substantially equal to the depth in the fluctuation portion.