Flat Wire Coil Forming With Layered Cross-Section Control

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Solution Overview

Problem

The large-scale production of coils with flat wire is complex, cost-intensive, and technically challenging due to issues with winding sticking together and uneven cross-sectional distribution, making it difficult to control the resulting shape and force distribution during pressure forming.

Innovation Solution

A method involving a rotatable lower tool that shapes a round feed wire into a coil turn, which is then formed into a flat wire coil using an upper tool, allowing for precise adjustment of the final cross-section without joining processes, enabling a continuous and cost-effective production of flat wire coils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If pressure forming is used to produce flat wire coils from round wire, then coil shape can be obtained, but the process becomes complex and costly due to winding sticking together and uneven cross-sectional distribution

Engineering Contradiction:
Improvecoil shapeVSAvoidprocess complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The coil winding process is segmented into discrete layers, with each layer being formed independently in the circumferential cavity before the next layer is added. This prevents windings from sticking together and allows individual control of each layer's cross-sectional shape, resolving the complexity issue while maintaining precise shape control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The circumferential cavity in the lower tool is pre-configured with the exact cross-sectional geometry desired for each layer. This preliminary shaping action eliminates the need for complex post-forming operations and ensures uniform cross-sectional distribution from the start, simplifying the overall process.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If multiple coil windings are pressed simultaneously to produce flat wire coils, then production speed increases, but controlling the resulting cross-sections becomes impossible due to uneven force distribution

Engineering Contradiction:
Improveproduction speedVSAvoidcross-sectional control
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Instead of pressing multiple windings simultaneously, the method segments the process so that each layer is formed sequentially in the circumferential cavity with controlled pressure application. This allows precise control of each layer's cross-section while maintaining high productivity through continuous layer-by-layer formation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The circumferential cavity provides localized shaping action on each layer at its specific position, ensuring that each layer receives precisely controlled pressure and shaping forces. This local quality control enables accurate cross-sectional geometry for each layer without the uneven force distribution that occurs in simultaneous pressing.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If round wire is used for coil winding, then feed wire is easier to handle, but the slot fill factor and efficiency are reduced compared to flat wire

Engineering Contradiction:
Improvefeed wire handlingVSAvoidslot fill factor
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The cross-sectional parameters of the wire are changed layer by layer as it is wound into the circumferential cavity. Each layer is progressively shaped from round to the desired flat or non-circular cross-section, maintaining ease of handling during feeding while achieving high slot fill factor in the final product.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The circumferential cavity is pre-configured with the target cross-sectional geometry, and each layer is shaped to match this preliminary form. This allows the wire to be fed in its easy-to-handle round form and then transformed into the space-efficient flat form, combining the advantages of both approaches.

Inventive Principle:
Principle #10Preliminary action

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 method allows for the precise and robust production of flat wire coils with adjustable cross-sections, eliminating the need for complex joining processes and ensuring technical safety and efficiency in coil manufacturing.

Implementation Method 1

The lower tool is preferably designed to be rotatable, so that a feed wire inserted or positioned in the lower tool can be wound up in the shape of the lower tool or unwound from a feed roll of the feed wire by a rotational movement of the lower tool

Methodology Applied
Scientific EffectRotational movement:

Implementation Method 2

the half coil turn formed by the feed wire is formed by the upper tool into a winding section transverse to the feed direction of the feed wire. This forming can be carried out essentially parallel to the rotational axis of the lower tool, thus imparting a final cross-section to the unwound feed wire positioned in the mold

Methodology Applied
Scientific EffectPressure forming: Compression

Data Source

PatentEP4307543B1Simplified production of flat wire coils
Publication Date: 2025.01.22 VOLKSWAGEN AG
  • EP4307543B1 patent drawingFigure 1A~1B
  • EP4307543B1 patent drawingFigure 2A~2B
  • EP4307543B1 patent drawingFigure 3A~3E

AI summary

In order to create a method for producing a coil turn (101), in particular in the form of flat wire, which is precise and technically easy to implement, it is proposed to arrange a feed wire (30) in a circumferential cavity (13) of a lower tool (11) to form half a coil turn, to form the half coil turn formed by the feed wire (30) by an upper tool (12) into a winding section transverse to the feed direction (Z) of the feed wire (30), and after pressing to space the upper tool (12) away from the lower tool (11) and to arrange the feed wire (30) in the circumferential cavity (13) of the lower tool (11) to form another half coil turn.