Composite Ceramic Core for Airfoil Casting
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Solution Overview
Problem
Conventional methods for creating complex ceramic cores for multi-wall airfoil castings face limitations due to tooling design and assembly complexities, leading to dimensional variability, flash formation, and increased handling scrap, which compromise the advanced cooling schemes in gas turbine engines.
Innovation Solution
A method involving the formation of a composite core insert with interlocked fused joints using preformed fugitive core inserts with joint-forming surfaces, eliminating the need for adhesives and reducing mislocation and flash formation by mechanically interlocking the inserts, allowing for more complex airfoil geometries and improved internal feature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple ceramic core pieces are assembled to form complex cooling schemes, then the complexity of cooling features is improved, but dimensional variability and handling scrap increase due to mismatch and fragility
Solution Approach 1:
The core is divided into modular ceramic core pieces that can be assembled together. Each piece is designed with complementary features (protrusions and recesses) that enable precise mating. This segmentation allows complex cooling schemes to be built from standardized modules while maintaining dimensional accuracy through the interlocking joint design.
Solution Approach 2:
Multiple ceramic core pieces are nested together within a core assembly structure. The pieces fit into one another like nested dolls, with each piece containing or being contained by adjacent pieces. This nesting arrangement maximizes the use of space and ensures tight tolerances between assembled components, reducing dimensional variability.
2Adaptability or versatility
If multiple fugitive core inserts are assembled in a core die, then features not operating in common planes are achieved, but flash formation occurs at the union of inserts
Solution Approach 1:
The fugitive core inserts are designed with asymmetric joint-forming surfaces featuring male and female portions that do not mirror each other. This asymmetric design ensures that the inserts mate in a specific orientation, preventing misalignment during assembly. The asymmetric geometry allows features in different planes to be formed while eliminating gaps that would cause flash formation at the unions.
3Ease of manufacture
If conventional tooling is used to form ceramic cores, then manufacturing simplicity is maintained, but core complexity is limited by tooling design capabilities
Solution Approach 1:
The core forming system transitions from static conventional tooling to a dynamic modular assembly approach. Instead of requiring a single complex fixed mold, the system uses multiple simpler modular fugitive core inserts that can be dynamically assembled and reconfigured. This allows the same tooling to produce various core geometries by changing the insert configuration, maintaining manufacturing simplicity while enabling complex multi-plane features.
Data Source
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AI summary
A multi-wall ceramic core for casting an airfoil with one or more internal cooling passages is made by preforming at least one fugitive core insert to have a joint-forming surface with a male and/or female joint feature and then forming at least one fugitive core insert in-situ adjacent and integrally connected and fused to the at least one preformed core insert at the joint-forming surface to form an interlocked, fused joint to form a composite core insert that includes features to form internal passage surfaces in the core when the composite core insert is removed. Another aspect involves preforming first and second fugitive core inserts to have respective joint-forming surfaces with respective snap-fittable joint features and assembling the first and second fugitive core inserts to form a composite core insert by snap fitting the snap-fittable joint features together to form an interlocked joint. The composite core insert is placed in a core molding die cavity, and a fluid ceramic material is introduced into the die cavity to form the ceramic core body incorporating the fugitive composite core insert therein.