Segmented Salt Mold Casting for Complex Electrical Coils

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Solution Overview

Problem

The production of complex geometries in electrical coils by casting is limited due to geometric requirements that prevent demolding, often resulting in surface defects like streaks and grooves, and the need for draft angles in traditional casting methods.

Innovation Solution

A method using a casting mold composed of more than two mold segments, where at least one segment is a lost mold made from salt or a salt mixture, allowing for the production of components with undercuts and high surface quality without draft angles, enabling smooth surfaces and complex geometries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional casting methods with permanent molds are used to produce electrical coils, then the component can be manufactured with defined geometry, but draft angles are required which cause surface defects like streaks and grooves

Engineering Contradiction:
Improvesurface qualityVSAvoiddemolding requirement
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The mold is divided into multiple segments (at least three segments) that can be separated after casting. This segmentation allows the mold to be opened and the cast part to be removed without requiring draft angles, thereby eliminating surface defects while maintaining complex geometry.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a lost mold approach where the mold segments are consumed or destroyed after a single use. This disposable mold approach eliminates the need for draft angles and permanent mold structures, allowing production of high-precision components with complex geometries without surface defects.

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

2Adaptability or versatility

If complex geometries with undercuts are produced by casting, then the component design freedom is increased, but the mold design becomes more complex and demolding is prevented

Engineering Contradiction:
Improvegeometry complexityVSAvoidmold structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The mold is segmented into at least three separate parts that can be arranged to form complex geometries with undercuts. After casting, the segments are removed individually, allowing demolding of complex shapes that would be impossible with a single-piece permanent mold.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of designing a permanent mold that must be opened for demolding, the invention uses a lost mold approach where the mold is intentionally designed to be destroyed or dissolved after casting. This inverts the traditional approach and eliminates demolding constraints entirely.

Inventive Principle:
Principle #13The other way round (Inversion)

3Manufacturing precision

If more than two mold segments are used to define complex geometries, then the component can be produced with high surface quality without draft angles, but the mold assembly complexity increases

Engineering Contradiction:
Improvesurface qualityVSAvoidmold assembly
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The use of at least three mold segments allows the creation of complex geometries with high surface quality by eliminating the need for draft angles. The segmented structure enables the mold to be opened in multiple directions, facilitating demolding while maintaining precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lost mold segments are discarded after a single use, which simplifies the overall process by eliminating the need for complex permanent mold structures. The investment in creating precise lost mold segments is offset by the elimination of expensive permanent mold manufacturing and maintenance.

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

Enables the production of electrical coils with high surface quality and complex geometries without draft angles, reducing post-processing needs and mechanical reworking, while simplifying the production process and scaling of components.

Implementation Method 1

The model is melted out of the hardened investment material

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

at least one molded part is designed as a lost mold, which is produced from a salt or a salt mixture

Methodology Applied
Scientific EffectDissolving:

Data Source

PatentEP3208013B1Method for casting a component, having a complex geometry having a mould with a segmented design
Publication Date: 2023.08.16 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3208013B1 patent drawingFigure 1
  • EP3208013B1 patent drawingFigure 2~3
  • EP3208013B1 patent drawingFigure 4~5

AI summary

The present invention relates to a method for casting a component (10) of complex geometry, in which a mold is used, at least one mold part (1, 5) of which is designed as a expendable mold. The at least one mold part (1, 5) designed as an expendable mold is made from a salt or a salt mixture. In the method, at least one outer or inner part of the mold, which defines the outer or inner geometry of the component, is composed of more than two mold segments (1), which are preferably stacked on top of each other. The method enables the cost-effective casting of components of complex geometry with high surface quality.