Ceramic Permanent Mold for Series Casting of Helical Copper Coils

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Solution Overview

Problem

Existing technologies lack a series-production process for producing cast copper coils or copper alloy coils in permanent molds with sufficient service life, leading to lower power or torque density in electrical machines due to inefficient space utilization and heat dissipation issues.

Innovation Solution

A casting mold is used to produce cast coils in permanent molds, featuring a die with conical or truncated pyramid-shaped inner contours and ceramic core pullers with variable web geometry to define the helix, allowing for efficient production of copper or copper alloy coils, which are cast using low-pressure or die casting processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If wound coils are used to improve fill ratio, then power density increases, but manufacturing complexity and cost increase due to manual manufacturing requirements

Engineering Contradiction:

Improvepower densityVSAvoidmanufacturing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical winding process with a casting process. Instead of manually winding wire to create coils, the invention uses mold casting to directly form the coil structure from molten copper or copper alloy, eliminating the complex manual winding operations while achieving comparable or superior fill ratios and power density

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental manufacturing parameter from wire winding to molten metal casting. This parameter change enables automated production of coils with optimized geometry, including variable cross-sections and improved fill ratios, while significantly reducing manufacturing complexity and enabling series production

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional coil winding is used, then manufacturing is simpler, but heat dissipation is impaired due to coil turns arrangement

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidheat dissipation

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent changes the manufacturing process from winding to casting, which fundamentally alters the coil structure. The casting process enables optimized cross-sectional geometries and internal configurations that improve heat dissipation pathways while maintaining manufacturing simplicity through automated mold-based production

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs copper or copper alloys with specific material properties optimized for both electrical conductivity and thermal management. The casting process allows incorporation of material compositions and structural features that enhance heat dissipation while maintaining ease of manufacture through mold-based production

Inventive Principle:

Principle #40Composite materials

3Productivity

If lost form casting is used for cast coils, then production is possible, but service life is insufficient due to non-reusable molds

Engineering Contradiction:

Improveproduction capabilityVSAvoidmold service life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent divides the mold into multiple reusable segments or components that can be disassembled and reassembled. This segmentation allows the mold to be used repeatedly for series production while maintaining the ability to produce complex coil geometries, thereby extending service life compared to traditional lost-form casting

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from a disposable lost-form approach to a recoverable and reusable mold system. The mold components are designed to withstand repeated use, and the process recovers and reuses the mold rather than discarding it after each casting, significantly extending service life while maintaining production capability

Inventive Principle:

Principle #34Discarding and recovering

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 significantly increases productivity and reduces manufacturing costs while enhancing power or torque density in electrical machines by optimizing coil fill ratio and heat dissipation.

Implementation Method 1

cast coils made of copper or copper alloys in permanent molds, which are cast using low-pressure or die casting processes

Methodology Applied

Scientific EffectLow-pressure casting:

Implementation Method 2

cast coils made of copper or copper alloys in permanent molds, which are cast using low-pressure or die casting processes

Methodology Applied

Scientific EffectDie casting:

Data Source

PatentEP3853974B1Casting mould for producing helical cast bodies

Publication Date: 2025.10.22 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

Figure 1~2
Figure 3~5

AI summary

The invention relates to a casting mould for producing helical cast bodies (1), in particular coils, springs or spirals, having: a mould (10) in the form of a permanent mould which determines the outer contour of the helical body and consists of a ceramic material or is coated by a ceramic material; a supporting tool (8), which supports the mould (10) from outside; and a mould core (12), which defines the continuous opening within the helical body (1) and consists of a ceramic material or is coated by a ceramic material, the mould core being formed in particular as a core puller.