Die-Casting Tool With Rear Rim Compaction for Void-Free Wheels

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Solution Overview

Problem

Existing die-casting processes for manufacturing vehicle wheels result in solidification cavities in the thick-walled rear rim area due to the flow front moving from thin-walled to thick-walled sections, making it impossible to produce a porosity-free wheel in this area.

Innovation Solution

A die-casting tool with secondary compressors, including radial and axial pistons, is used to locally compress and displace unsolidified material in the rear rim during the casting process, ensuring even distribution and avoiding cavities by acting on the rear rim cavity in a circumferential direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the mold is filled via a central sprue with flow direction from thin-walled rim bed to thick-walled rear rim, then the mold filling process is simple and efficient, but solidification cavities form in the rear rim area

Engineering Contradiction:
Improvemold filling efficiencyVSAvoidabsence of solidification cavities
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Secondary compactors are activated during the holding pressure phase to preliminarily compact the casting material in the rear rim area before solidification completes, preventing cavity formation in advance

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Secondary compactors are positioned specifically in the rear rim area where cavities form, applying localized compaction force only where needed rather than uniformly across the entire casting

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If holding pressure is applied during casting, then material compaction is improved, but it cannot affect the thick-walled rear rim because thin-walled rim bed solidifies first

Engineering Contradiction:
Improvematerial compaction qualityVSAvoideffectiveness in rear rim area
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The compaction function is segmented into primary compaction (general holding pressure) and secondary compaction (localized rear rim compaction), allowing each to operate independently in its optimal timing window

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Secondary compactors are dynamically activated during the holding pressure phase with adjustable timing and force, adapting to the local solidification state of the rear rim area

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 effectively prevents solidification cavities in the rear rim, ensuring a void-free material condition by distributing the casting material evenly, thus producing a high-quality vehicle wheel.

Implementation Method 1

These compactors can locally compress the casting material in the area of the rear rim during the casting process

Methodology Applied
Scientific EffectLocal compression: Compression

Implementation Method 2

the still unsolidified casting material in the rear rim cavity is displaced along a flow path in the circumferential direction of the wheel

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 3

the mold is filled via a central sprue, with the molten metal flowing radially outwards from the wheel hub

Methodology Applied
Scientific EffectRadial flow:

Data Source

PatentEP4549050B1Die-casting tool and die-casting method for producing a raw cast wheel
Publication Date: 2026.05.13 AUDI AG
  • EP4549050B1 patent drawingFigure 1~2
  • EP4549050B1 patent drawingFigure 3
  • EP4549050B1 patent drawingFigure 4~5

AI summary

The invention relates to a die-casting tool for manufacturing a raw cast wheel (1), in which the mold is filled by means of a central sprue in a filling direction from a wheel hub (3) via spokes (7) radially outwards to a front horn (9) and from there axially via a rim bed (11) to a rear horn (13). According to the invention, the die-casting tool has at least one, and in particular a number, of secondary compactors (37, 39) distributed in the circumferential direction of the wheel in the region of the rear horn (13), which compact the casting material (42) in the region of the rear horn (13) during the casting process.