Permanent Mold Coil Casting With Accessible Burr Removal

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Solution Overview

Problem

Existing coil manufacturing processes using casting techniques face inefficiencies due to the use of cores and slides, which increase production costs and complexity, and molds are prone to erosion and cracking, leading to burrs that require costly post-processing and reduce the service life of molds.

Innovation Solution

A method using a permanent mold with two mold halves that form a cavity for a bent helix with a flattened spiral cross-sectional profile, allowing burrs to be easily accessible and removable, and eliminating the need for additional cores or slides, with the mold design facilitating easy bending of the casting into a helix shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If cores and slides are used in casting molds for complex geometries, then the coil shape can be formed, but production costs increase and manufacturing complexity increases

Engineering Contradiction:
Improvecoil geometryVSAvoidmold structure
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The mold is divided into exactly two mold halves that can be separated, eliminating the need for internal cores and slides. Each mold half forms a portion of the coil geometry, and the segmented design allows for easy removal after casting without requiring complex internal mold components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using internal cores and slides to form the coil shape from the inside out, the invention uses external mold halves that form the coil shape from the outside in. The mold halves are designed with the negative geometry of the desired coil, inverting the traditional approach to achieving complex shapes.

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

2Temperature

If high casting temperatures are used, then the coil material can be properly cast, but mold erosion and cracking increase, reducing mold service life

Engineering Contradiction:
Improvecasting temperatureVSAvoidmold service life
Core Design Contradiction:
TemperatureVSDuration of action of stationary object

Solution Approach 1:

The mold halves are designed with robust construction and appropriate material selection to withstand high casting temperatures before the casting process begins. The simple two-half design without internal cores or slides eliminates potential weak points where erosion and cracking would initiate, providing inherent protection against thermal damage.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The invention removes internal cores and slides from the mold structure, extracting the elements that would be most susceptible to erosion and cracking from high-temperature exposure. This leaves only the essential mold halves that can be more easily protected and maintained.

Inventive Principle:
Principle #2Taking out (Extraction)

3Shape

If traditional casting molds with multiple parts are used, then complex coil geometries can be formed, but burrs are formed on the coil surface requiring costly post-processing

Engineering Contradiction:
Improvecoil geometryVSAvoidsurface quality
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The mold is segmented into exactly two halves with a single parting line, minimizing the number of interfaces where burrs can form. This simple segmentation maintains the ability to form complex coil geometries while reducing surface defects compared to multi-part molds with multiple parting lines.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mold halves are designed with optimized parting line locations and surface finishes at critical areas to prevent burr formation. The local quality of the mold surfaces and parting line design is enhanced in specific regions to ensure high surface quality on the final coil product.

Inventive Principle:
Principle #3Local quality

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 enables efficient production of high-quality helices with minimal burrs, reducing production costs and extending mold life by simplifying the manufacturing process and minimizing post-processing requirements.

Implementation Method 1

a permanent mold (1) is provided which has exactly two mold halves (1.1, 1.2) that can be joined in one mold parting plane (1.5); The two halves of the permanent mold are joined together in such a way that the permanent mold, when joined, has a cavity which forms the shape of a bent helix

Methodology Applied
Scientific EffectMold cavity forming:

Implementation Method 2

wherein this coil material is solidified and/or this coil material is allowed to solidify under controlled conditions

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP3853983B1Production of a coil, permanent mold for a coil, and coil
Publication Date: 2025.12.17 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3853983B1 patent drawingFigure 1a~1c
  • EP3853983B1 patent drawingFigure 1d
  • EP3853983B1 patent drawingFigure 2a~2c

AI summary

The invention relates to a method for producing a coil (2), having a step of providing a permanent mold (1) with mold halves (1.1, 1.2) which can be joined together on a mold separation plane (1.5). The method additionally has a step of joining together the mold halves (1.1, 1.2) of the permanent mold (1) such that the permanent mold (1) has a cavity (1.3), which defines the shape of the coil (2) or the shape of a bent open coil (2'), when the permanent mold is joined together, wherein the specified coil (2) or the bent open coil (2') has a flattened profiled winding cross-section which has two opposite flat faces (2.1, 2.1'), an outer face (2.2) and an inner face (2.3) opposite the outer face (2.2), and the mold separation plane (1.5) runs at least partly along the outer face (2.2) and/or the inner face (2.1) and/or edges of the profiled winding cross-section. The method additionally has a step of removing burrs (3) extending on the outer face (2.2) and/or the inner face (2.3) and/or the edges of the cast body on the mold separation plane (1.5). The invention further relates to a permanent mold for carrying out the method and to a coil which has been produced using the method or using the permanent mold.