Leachable Casting Core Tie Bar Segmentation

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Solution Overview

Problem

In gas turbine engine manufacturing, the casting process often results in cooling passages collapsing due to shifting core legs, leading to undesirable 'cross talk' or 'kiss out' issues, and existing methods require tie bars that create linking cavities after leaching, causing fluid loss.

Innovation Solution

An additive manufactured leachable casting core with strategically oriented tie bars that form linking cavities with obstructions, such as bends or diameter variations, to restrict fluid communication and equalize pressure, preventing fluid loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If tie bars are used to secure core legs during casting, then structural stability is improved, but linking cavities are created that cause fluid loss

Engineering Contradiction:

Improvecore leg position stabilityVSAvoidcooling fluid loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of substance

Solution Approach 1:

The tie bar is segmented into multiple sections with varying cross-sectional areas, creating a tapered structure that reduces the volume of the linking cavity while maintaining the structural function of securing core legs during casting

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tie bar has non-uniform cross-sectional area along its length, with larger areas at the ends for secure attachment and smaller areas in the middle to minimize linking cavity volume, thereby reducing fluid loss while maintaining stability

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If traditional casting cores are used, then manufacturing simplicity is maintained, but cooling passages collapse due to leg shifting

Engineering Contradiction:

Improvecore manufacturing simplicityVSAvoidcooling passage geometry accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The core legs are pre-positioned and secured with tie bars before the casting process begins, preventing leg shifting during casting and ensuring accurate cooling passage geometry without requiring complex manufacturing procedures

Inventive Principle:

Principle #10Preliminary action

3Strength

If tie bars with large cross-sectional area are used, then structural strength is improved, but linking cavity volume increases causing more fluid loss

Engineering Contradiction:

Improvetie bar structural strengthVSAvoidcooling fluid loss

Core Design Contradiction:

StrengthVSLoss of substance

Solution Approach 1:

The tie bar employs varying cross-sectional area along its length, with larger areas at the ends to provide structural strength for securing core legs, and smaller areas in the middle to minimize linking cavity volume and reduce fluid loss

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11389862B2Leachable casting core and method of manufacture

Publication Date: 2022.07.19 GENERAL ELECTRIC CO

AI summary

A leachable casting core and method of manufacture may include a plurality of legs configured to establish a plurality of internal flow channels of a cast component. Tie bars, with a first tie bar end and a second tie bar end opposite thereof, may couple to at least two of the plurality of legs. At least one of the tie bars may be oriented to form a linking cavity within the cast component between the internal flow channels. The linking cavity may serve as an obstruction to fluid communication through the linking cavity.