Copper Hairpin Laser Welding With Sub-1000 Nm Beams
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Solution Overview
Problem
The existing methods for joining copper hairpins in stator windings of electric motors result in irregular and unstable joining due to varying energy absorption caused by different surface properties, leading to fluctuations in the welding process and potential formation of spatter and process pores.
Innovation Solution
A method using a machining beam with a wavelength of less than 1000 nm, preferably in the green or blue spectrum, for laser beam welding of copper hairpins, which increases energy absorption and stability, allowing for heat conduction welding without the formation of vapor capillaries, thereby achieving a uniform and controlled joining process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser beam welding is performed at wavelength of 1030 nm (near infrared), then deep welding with vapor capillary formation occurs, but energy absorption varies due to surface properties causing irregular and unstable joining
Solution Approach 1:
The patent changes the laser wavelength parameter from 1030 nm (near infrared) to wavelengths below 1000 nm (green or blue spectrum). This parameter change increases the energy absorption of copper material consistently, eliminating the variability caused by surface properties and achieving stable, uniform joining results.
2Strength
If deep welding with vapor capillary formation is used, then joining of copper hairpins is achieved, but spatter and process pores are formed
Solution Approach 1:
By changing the laser wavelength to below 1000 nm, the welding process transitions from deep welding with vapor capillary formation to a more controlled heat conduction welding process. This eliminates the harmful effects of spatter and process pores while maintaining adequate joining strength.
3Quantity of substance
If copper hairpins with larger cross-sectional area are used, then current flow and motor performance are improved, but conventional winding formation is not possible due to stresses from dimensioning and geometry
Solution Approach 1:
The patent replaces the conventional mechanical winding process with a direct insertion method where pre-formed copper hairpins are inserted into the stator cage. The laser welding process then joins these hairpins, eliminating the need for complex mechanical winding operations while accommodating larger cross-sectional areas.
4Ease of operation
If hairpins are inserted linearly into stator cage, then assembly is simplified and multiple hairpins can be introduced simultaneously, but mechanical and electrical connection between hairpins must be established separately
Solution Approach 1:
The patent uses laser beam welding to automatically join the inserted hairpins, replacing complex mechanical joining operations. The laser process can precisely join multiple hairpins in sequence or parallel, maintaining assembly simplicity while establishing reliable electrical connections.
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 results in a more uniform and stable joining of copper hairpins, reducing fluctuations in energy input and minimizing the formation of spatter and process pores, leading to a consistent welding result and improved stator winding efficiency.
Implementation Method 1
the absorption of the energy of the machining beam in the material of the hairpin may vary from hairpin to hairpin due to changing surface properties
Implementation Method 2
the respective ends to be joined to one another of the hairpins are then actually joined to one another, for example by laser beam welding with a machining beam in the near infrared (NIR), for example at a wavelength of 1030 nm
Implementation Method 3
This enables an increased flow of current compared with a wire. The increase in the performance of electric motors
Data Source
AI summary
A method for joining copper hairpins includes providing at least two ends to be joined to one another of the copper hairpins, and joining the copper hairpins. The copper hairpins are joined by laser beam welding with a machining beam having a wavelength of less than 1000 nm.