Compact Toroidal Electromagnetic Stirrer for Aluminum Casting

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Solution Overview

Problem

Existing electromagnetic stirring devices are not suitable for casting aluminum or aluminum alloys in Hot-Top moulds, as they are too large and incompatible with industrial spaces, and previous solutions fail to effectively homogenize the molten metal bath, leading to surface defects and inadequate stirring.

Innovation Solution

A compact electromagnetic stirrer with a toroidal core and winding configuration, installed near the meniscus and solidification starting zone, generates a rotating magnetic field using phase-shifted currents, eliminating the need for a cooling system and allowing effective stirring of the molten metal bath without direct contact with the mould wall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If traditional electromagnetic stirring devices are used in Hot-Top moulds, then stirring function is provided, but the devices are too large and incompatible with industrial spaces

Engineering Contradiction:
Improvestirrer sizeVSAvoidstirring effectiveness
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The stirrer is segmented into two independent parts: a compact toroidal core and separate winding packs. This segmentation allows the windings to be positioned at optimal distances from the mould wall while keeping the core compact, resolving the contradiction between small size and effective stirring function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from conventional linear coil arrangements to a toroidal (doughnut-shaped) core configuration. This dimensional change enables the windings to be distributed around the core in a compact footprint, achieving effective stirring in a much smaller volume suitable for Hot-Top moulds.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If conventional stirrer designs are used, then electromagnetic stirring is achieved, but they require cooling systems that complicate installation and operation

Engineering Contradiction:
Improvecooling system requirementsVSAvoidelectromagnetic field generation
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The invention extracts and removes the cooling system from the stirrer design. By using a toroidal core with air-core windings positioned at optimal distances, the design eliminates heat generation issues that would require cooling, significantly reducing device complexity while maintaining electromagnetic stirring effectiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If stirrers are positioned close to the mould wall, then effective stirring is achieved, but direct contact causes operational problems

Engineering Contradiction:
Improvestirring effectivenessVSAvoidoperational reliability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention applies local quality by positioning the windings at a specific optimal distance from the mould wall. This localized positioning ensures the electromagnetic field is strong enough for effective stirring while maintaining a gap that prevents direct contact and operational problems, achieving both stirring effectiveness and ease of operation.

Inventive Principle:
Principle #3Local quality

4Manufacturing precision

If existing stirrer designs are used, then some stirring function is provided, but they fail to effectively homogenize the molten metal bath, leading to surface defects

Engineering Contradiction:
Improvehomogenization qualityVSAvoidstirrer configuration
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention creates dynamic stirring action by inducing rotational movement in the molten metal through the toroidal electromagnetic field. This dynamic rotation, rather than simple linear agitation, effectively homogenizes the bath and eliminates surface defects like pinholes and gas bubbles, achieving high manufacturing precision.

Inventive Principle:
Principle #15Dynamics

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 solution achieves improved homogenization of the aluminum or aluminum alloy bath, reducing surface defects and transforming dendritic structures into fine-grained equiaxial/globular structures, resulting in higher-quality products with lower production costs and shorter production times.

Implementation Method 1

generates a rotating magnetic field using phase-shifted currents, eliminating the need for a cooling system and allowing effective stirring of the molten metal bath

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The present invention relates to an electromagnetic stirring device in a mould for casting aluminium or aluminium alloys

Methodology Applied
Scientific EffectElectromagnetic stirring: Electromagnetic Stirring

Data Source

PatentEP3849726B1Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, stirring method in a mould for casting aluminium or aluminium alloys, mould and casting machine for casting aluminium or aluminium alloys
Publication Date: 2023.05.03 ERGOLINES LAB
  • EP3849726B1 patent drawingFigure 1~2
  • EP3849726B1 patent drawingFigure 3~6
  • EP3849726B1 patent drawingFigure 7

AI summary

Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, wherein the electromagnetic stirring device comprises a winding core of conductive coils intended for the circulation of a current generating an electromagnetic field of stirring of the molten metal inside the mould, mould, casting machine and casting plant provided with such an electromagnetic stirring device, stirring method in a mould for casting aluminium or aluminium alloys comprising a phase of supply of phase-shifted currents on an electromagnetic stirring device in a mould.