Twisting Fixture for Bar Conductor End Portions
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Solution Overview
Problem
Existing methods for twisting free end portions of bar conductors in electric machine windings face challenges in precision and accessibility due to the intrinsic elasticity of conductors and limited access to the small protrusions, making it difficult to achieve correct bending for adequate electrical connections.
Innovation Solution
A twisting method and fixture that utilizes a pocket member with a main structure and axially slidably mounted secondary structures, allowing for relative rotational-translational motion to align and bend the conductors' end portions uniformly and non-uniformly, facilitating precise shaping and connection formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional twisting methods are used on small protruding end portions, then the conductors can be accessed and bent, but the precision of bending is insufficient due to limited access and intrinsic elasticity
Solution Approach 1:
The twisting device is divided into multiple pockets, each capable of independently receiving and twisting conductor end portions. This segmentation allows precise control over each conductor's bending while maintaining accessibility through the organized pocket structure.
Solution Approach 2:
The pockets act as intermediary structures between the operator and the conductor end portions. Each pocket provides a confined space that facilitates precise bending operations while the overall device structure ensures accessibility to all protruding ends.
2Manufacturing precision
If the conductor end portions are allowed to elastic recovery after bending, then the intrinsic elasticity is maintained, but the bending precision is compromised as conductors return partially to starting configuration
Solution Approach 1:
The pockets are designed to hold the conductor end portions in the desired bent configuration before final positioning. This preliminary action maintains the bent shape against elastic recovery forces, ensuring precision is achieved and maintained.
Solution Approach 2:
The pockets provide mechanical constraint that changes the effective stiffness parameter of the conductor during bending. By confining the conductor within the pocket structure, the system overcomes intrinsic elasticity and maintains the desired configuration.
3Productivity
If multiple conductor end portions are twisted simultaneously, then productivity is improved, but the device complexity increases
Solution Approach 1:
The twisting device employs multiple identical pockets that can simultaneously process multiple conductor end portions. This universal design allows the same pocket structure to be replicated and used in parallel, increasing productivity without requiring fundamentally different mechanisms for each conductor.
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 method and fixture enable efficient and precise twisting of bar conductors' end portions, ensuring reliable electrical connections and overcoming the limitations of previous techniques by providing a robust and efficient twisting process.
Implementation Method 1
for various reasons, it may be difficult to correctly and precisely bend the free end portions of conductors, as required. For example, since the protrusion of the majority of these end portions on the welding side is relatively small, it may be difficult to access the end portions of conductors and carry out the operations required to ensure a correct bending both in the circumferential and in the axial direction with respect to the stator core axis. Moreover, as an example, a precise shaping of conductors is complicated by the fact that these are provided with an intrinsic elasticity, which, after bending, tries to drive them partially back to their starting configuration.
Data Source
AI summary
A twisting method is described, for twisting free end portions of bar conductors for the stator or rotor bar winding of an electrical machine. The twisting method allows achieving a non uniform twisting of the bar conductors from the welding side of the stator or rotor core by means of a twisting fixture. The twisting fixture comprises a pocket member including a main structure provided with an arc of adjacent pockets and a secondary structure, provided with at least one further pocket, which can axially translate with respect to the main structure.