Casting Mold Insert Sealing for Thread Strength

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Solution Overview

Problem

Existing metal and plastic casting methods face challenges in preventing molten materials from infiltrating threaded inserts during the casting process, leading to weakened threads and defective components due to material shrinkage and high-pressure injection, which complicates the integration of reliable and strong thread inserts.

Innovation Solution

A metal or plastic casting mold with a flexible sealing element positioned between the insert and the mold wall to prevent molten material from entering the insert, combined with a holding core that can be removed to accommodate material shrinkage and maintain insert stability during cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If threaded inserts are molded into molten metal or plastic, then the insert integration is achieved, but molten material infiltrates the insert threads causing weakened threads and defective components

Engineering Contradiction:

Improvethread strengthVSAvoidmolten material infiltration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A sealing element is introduced as an intermediary component between the insert and the mold cavity wall. This sealing element prevents direct contact between the molten material and the insert threads, thereby blocking the infiltration path while allowing the insert to remain integrated in the cast component.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing element is positioned in advance before the molten material is injected, creating a preventive barrier that stops the harmful infiltration from occurring in the first place. This preliminary protective measure ensures that the insert threads remain clean and structurally sound throughout the casting process.

Inventive Principle:

Principle #9Preliminary anti-action

2Manufacturing precision

If rigid positioning is used to hold the insert, then position accuracy is maintained, but mechanical tensions arise during material shrinkage

Engineering Contradiction:

Improveinsert position accuracyVSAvoidinsert stability

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The positioning device is designed with dynamic characteristics, allowing it to adapt its positioning force during the casting process. During material shrinkage, the positioning device can accommodate dimensional changes while maintaining adequate positioning, thereby reducing mechanical tensions and preventing insert damage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The positioning device utilizes material parameter changes, specifically the thermal expansion and contraction properties of the mold material. As the mold and insert undergo thermal changes during casting, the positioning device adjusts accordingly, maintaining position accuracy while accommodating shrinkage-induced dimensional variations.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If high pressure is applied during casting, then complete mold filling is achieved, but molten material forces its way into the insert

Engineering Contradiction:

Improvemold filling completenessVSAvoidmaterial infiltration under pressure

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The sealing element serves as a pressure-resistant intermediary barrier between the high-pressure molten material and the insert. It withstands the casting pressure while blocking the material from penetrating into the insert threads, allowing complete mold filling without compromising insert integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 molten material infiltration into threaded inserts, enhances thread strength, and reduces mechanical tensions caused by material shrinkage, resulting in more reliable and cost-effective cast components with reduced post-processing requirements.

Implementation Method 1

a preferably flexible sealing element is arranged by means of which the insert is at least partly sealable against the entering of molten metal

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a holding core that can be removed to accommodate material shrinkage and maintain insert stability during cooling

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS10441997B2Casting mold, insert for a casting mold, a cast part and a casting method therefor

Publication Date: 2019.10.15 BOLLHOFF VERBINDUNGSTECHNIK GMBH

AI summary

A metal casting method and a plastic injection molding method in which an insert is molded in molten material such that no molten material enters the interior of the insert. The usage of a wire thread insert as insert has the advantage that for example in an aluminum cast part thread holes can be produced already as part of the casting process. For this purpose, the casting mold, the insert, as well as the casting method are described.