Friction Stir Welding Rotor Coils Without Filler Material
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Solution Overview
Problem
Traditional brazing processes for joining rotor coils are manual, unreliable, and limited in joint location, requiring destructive testing and excessive copper material, with quality dependent on operator skill and resulting in weld defects.
Innovation Solution
Friction Stir Welding (FSW) process using a machine with a welding tool to form a continuous welding path between rotor coils, eliminating the need for filler material and allowing automatic control of the welding process, including a milling tool for separating the coils, which improves mechanical and electrical conductivity and reduces material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brazing processes are used to join rotor coils, then joints can be formed, but the process is manual and unreliable with quality dependent on operator skill
Solution Approach 1:
The patent replaces the manual brazing process with an automated friction stir welding process. The welding tool performs the joining operation automatically through programmed motion along a defined welding path, eliminating dependence on operator skill and ensuring consistent joint quality across all rotor coils.
Solution Approach 2:
The invention changes the fundamental parameters of the joining process by transitioning from brazing (thermal diffusion bonding with filler material) to friction stir welding (mechanical mixing and forging). This parameter change enables automated control through programmed welding speed, tool rotation speed, and axial force, thereby improving reliability.
2Adaptability or versatility
If brazing processes are used, then joints can be formed, but joint locations are limited within the rotor coils
Solution Approach 1:
The welding process is segmented into discrete positional segments along the welding path, allowing the tool to access and weld at any location along the rotor coil assembly. This segmentation enables flexible joint placement without the geometric constraints that limit brazing access.
3Loss of substance
If brazing is performed, then rotor coils can be joined, but excessive copper material is used and destructive testing is required
Solution Approach 1:
The invention extracts and eliminates the filler material requirement from the joining process. Friction stir welding creates a metallurgical bond through direct material mixing and forging without requiring additional copper or filler materials, thereby reducing material usage while maintaining joint integrity.
Solution Approach 2:
The friction stir welding process is self-verifying through the formation of a distinct stirred zone and tool exit profile that inherently indicate successful welding. This self-service characteristic eliminates the need for separate destructive testing to verify joint quality, as the process parameters and resulting microstructure provide built-in quality assurance.
4Productivity
If manual brazing is performed, then joints can be formed, but the process is time-consuming and labor-intensive
Solution Approach 1:
The invention merges multiple operations into a single automated friction stir welding process that simultaneously achieves material joining, surface preparation, and quality verification. This consolidation increases productivity by eliminating the sequential steps required in manual brazing while the automated system manages the complexity through integrated control.
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 FSW process produces high-quality, defect-free joints with improved mechanical properties and electrical conductivity, reduces copper usage, and eliminates the need for destructive testing, offering labor and time savings while allowing for precise control and repeatability.
Implementation Method 1
Friction Stir Welding (FSW) process
Implementation Method 2
welding the straight section to the one end of the end arc section of the each rotor coil at a joint using a welding tool
Data Source
AI summary
A process and a system for welding rotor coils are presented. A plurality of rotor coils are arranged on a table of a machine. A welding tool welds the rotor coils on one end using a Friction Stir Welding process. Transition pieces are each arranged between the rotor coils to create a continuous welding path. A run-off tab is placed at an end of the welding path. The welding tool is changed to a milling tool after completion of the welding. The milling tool traces back along the welding path to separate the rotor coils. The milling tool may be changed to the welding tool to repeat the process for another end of the rotor coils. The process is completely automatic and controlled by a control unit.