Helical Metal Coil Casting with Axial Compression for High Fill Factor

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Solution Overview

Problem

Current methods for manufacturing cast aluminum and copper coils or coils made of aluminum and copper alloys in permanent molds are lacking, leading to low power and torque density in electrical machines due to inefficient fill factors, heat dissipation issues, and high tooling complexity, which results in high reject rates and limited design flexibility.

Innovation Solution

A method involving the production of a pre-formed helical metal body in a mold followed by plastic deformation along its longitudinal axis to achieve the target shape, allowing for the use of simple two-part tooling and enabling mass production of coils with improved fill factors and reduced gaps between turns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional winding methods are used to manufacture coils, then mass production is achieved, but the fill factor is low and power density is reduced

Engineering Contradiction:
Improvemass production capabilityVSAvoidfill factor
Core Design Contradiction:
ProductivityVSVolume of moving object

Solution Approach 1:

The invention changes the manufacturing method from conventional winding to casting process, transforming the production parameters to achieve both mass production capability and improved fill factor. The casting process allows complete filling of the mold cavity, maximizing the fill factor while maintaining high productivity through automated casting cycles.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the mechanical winding system with a casting system. Instead of mechanically winding wire around a former, the liquid metal is poured into a mold and solidifies to form the coil geometry directly, eliminating the winding mechanism while achieving superior fill factor and production efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Volume of moving object

If complex manually manufactured coils are wound to improve fill factor, then power density increases, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvefill factorVSAvoidmanufacturing complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The invention uses a mold as a copy or replica of the desired coil geometry. The mold cavity is designed to match the final coil shape, and the casting process creates an exact copy of this geometry in metal, achieving complex shapes without complex manufacturing operations.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The mold is prepared in advance with the exact geometry of the desired coil. All complex features, internal passages, and geometric details are pre-formed in the mold cavity, so that the casting process simply fills this pre-prepared space, eliminating the need for post-casting forming operations.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If cast coils are produced in lost molds, then geometric flexibility is achieved, but tooling life is limited and production cost increases

Engineering Contradiction:
Improvegeometric flexibilityVSAvoidtooling life
Core Design Contradiction:
Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The invention replaces expensive, short-lived lost molds with durable, reusable permanent molds. The permanent mold can be used repeatedly for hundreds or thousands of casting cycles, eliminating the need to create new molds for each production run while maintaining full geometric flexibility through proper mold design.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Quantity of substance

If high casting temperature is used for copper components, then complete filling of mold is achieved, but thermal stress reduces tool life

Engineering Contradiction:
Improvemold filling completenessVSAvoidtool life
Core Design Contradiction:
Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The invention optimizes the casting temperature parameters to use the minimum necessary temperature to achieve complete mold filling. By carefully controlling the pouring temperature and casting speed, the process achieves full mold filling at lower temperatures, reducing thermal stress on the permanent mold while maintaining production efficiency.

Inventive Principle:
Principle #35Parameter changes

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 mass production of cast coils with increased power density, reduced manufacturing complexity, and improved design flexibility, facilitating automated processes and cost-effective production of coils for electrical machines.

Implementation Method 1

a pre-formed, helical metal body (1') is produced in a mold (20) by a casting process

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

compressed by deformation along its longitudinal axis (6)

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP3852948B1Method for producing a helical metal body
Publication Date: 2025.11.12 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3852948B1 patent drawingFigure 1~3
  • EP3852948B1 patent drawingFigure 4~5

AI summary

The invention relates to a method for producing a helical metal body (Γ), in which initially a preformed, helical metal body is produced in a mould by a casting method and is subsequently compressed along its longitudinal axis by deformation.