Helical Wound Electrical Machine Core with Adjustable Mandrel
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Solution Overview
Problem
Conventional methods for producing laminated cores for electrical machines result in significant scrap and require substantial energy and force to handle and align the cores, limiting the production of larger diameter cores due to stress and misalignment issues during the winding and sizing processes.
Innovation Solution
A method and apparatus that involve winding a shaped strip onto a mandrel with adjustable diameters to apply tensile strain, secure the coils with weld lines, and then relax the core for easy removal, allowing for the production of larger diameter cores with improved alignment and reduced energy requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mandrel diameter is increased to produce larger diameter cores, then the core size capability is improved, but the force and energy required to handle and align the coils increases significantly
Solution Approach 1:
The mandrel diameter is made dynamically adjustable rather than fixed. The system transitions between a first diameter during winding/alignment and a second larger diameter during removal, allowing the core handling capabilities to adapt to different operational phases without requiring excessive force throughout the entire process.
Solution Approach 2:
The physical parameter of mandrel diameter is changed between operational stages. By increasing the diameter after winding is complete, the core is relaxed from the tensile strain applied during winding, reducing the force needed for removal and handling of large diameter cores.
2Ease of manufacture
If conventional stamping methods are used to produce cores, then manufacturing simplicity is maintained, but significant scrap is generated
Solution Approach 1:
The manufacturing process transitions from stamping discrete parts to winding continuous strip material. This parameter change in the manufacturing approach allows for near 100% material utilization as the strip is formed into the core shape without the cutting and scrap generation inherent in stamping operations.
3Manufacturing precision
If the mandrel diameter is increased during winding to improve alignment, then alignment precision is improved, but the energy required to stretch and hold the coils increases
Solution Approach 1:
The mandrel operates at two distinct diameter states optimized for different functions: a first diameter during winding that provides appropriate tension and alignment, and a second larger diameter during removal that reduces holding forces. This dynamic adjustment optimizes energy efficiency while maintaining alignment precision.
Solution Approach 2:
Alignment is achieved during the winding process itself through the controlled application of tensile strain at the first diameter, rather than requiring subsequent alignment operations. The preliminary winding action at the optimized first diameter ensures proper coil alignment before the diameter is increased for removal.
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
Enables the production of larger diameter laminated cores with enhanced alignment and reduced operational energy, overcoming the limitations of conventional techniques by minimizing scrap and handling challenges.
Implementation Method 1
increasing the diameter of the mandrel by a first predetermined amount, while the mandrel is inside the winding, to impose a tensile strain on the coils of the helical winding
Implementation Method 2
reducing the diameter of the mandrel by a second predetermined amount greater than the first predetermined amount to relax the laminated core
Data Source
AI summary
There is described a method and apparatus for forming a core for an electrical machine, in which a stamped metal strip (4a, 4b) is wound onto a mandrel (22), to form a helical winding. The diameter of the mandrel is then increased to apply tension to the wound strip, while the coils of the wound strip are held between clamps (24, 25). The coils of the wound strip are then fixed relative one to another (50, 51), while the coil is held at the increased diameter. The diameter of the mandrel is then reduced to disengage the laminated core from the mandrel. To produce a rotor or stator for an electrical machine, electrical coils are mounted in slots formed in the inner or outer surface of the core. The rotor or stator may then be incorporated into an electrical machine such as a motor or generator.