Composite Casting Core for Turbine Cooling Passageways
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Solution Overview
Problem
Current investment casting techniques for superalloy turbine engine components face challenges in manufacturing fine, precisely located cooling passageways due to the fragility and difficulty in manufacturing ceramic casting cores, which affects the efficiency of air cooling in gas turbine engines.
Innovation Solution
The use of a composite core assembly comprising refractory metal cores and ceramic feedcores, where the refractory metal cores are assembled with ceramic cores and molded over a pattern material to form a shell for investment casting, allowing for precise formation of cooling passageways within the turbine engine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ceramic casting cores are used to form cooling passageways, then the cooling features can be precisely located and formed, but the cores become fragile and difficult to manufacture
Solution Approach 1:
The casting core is divided into two distinct parts: a ceramic feedcore that forms the cooling passageway and a metallic core (refractory metal or tool steel) that provides structural support. This segmentation allows each part to be optimized for its specific function - the ceramic for precision passageway formation and the metallic core for mechanical strength during manufacturing and casting.
Solution Approach 2:
The invention uses a composite core assembly combining ceramic material with metallic material (refractory metal or tool steel). This composite structure leverages the advantages of both materials: ceramic for chemical stability and precision passageway formation, and metal for mechanical strength and ease of handling during the casting process.
2Productivity
If fine cooling features are manufactured, then air cooling efficiency is improved, but the cores become more fragile
Solution Approach 1:
By separating the core into ceramic feedcore and metallic support core, the fine cooling features can be precisely formed in the ceramic portion while the metallic portion provides robust structural support, preventing fragility issues even with fine features.
Solution Approach 2:
Different regions of the core assembly have different properties optimized for their specific functions: the ceramic feedcore region has precise geometric features for cooling passageway formation, while the metallic core region has enhanced mechanical properties for structural support and durability.
3Manufacturing precision
If ceramic cores are used for casting, then cooling passageways can be formed, but cracking risk increases during manufacturing
Solution Approach 1:
The ceramic feedcore is segmented from the metallic core, allowing the ceramic to be optimized for passageway formation while the metallic core absorbs mechanical stresses and prevents cracking propagation throughout the entire core structure.
Solution Approach 2:
The metallic core acts as an intermediary that provides mechanical support to the ceramic feedcore during handling, assembly, and the casting process, reducing the risk of cracking in the more brittle ceramic material.
Data Source
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AI summary
A gas turbine engine component (20) has a leading edge (30) and a trailing edge (32) and a pressure side (36) and a suction side (34). The pressure side (36) and suction side (34) extend between the leading edge (30) and trailing edge (32). One or more cooling passageways extend through the airfoil (22) and comprise a trunk (70) extending from an inlet (50). At the inlet (50), there is an additional passageway (762,74) adjacent the trunk (70) and having at least one edge (134,136) recessed relative to the trunk (70). Also claimed is 1. a pattern (140) for casting a component (20) having an airfoil (22), the pattern (140) comprising: a pattern material (144) having an airfoil portion (146); and a casting core combination (142) at least partially embedded in the pattern material (144) and comprising: a metallic casting core (162,164) having opposite first and second faces; and at least one additional casting core (160), the metallic casting core (162,164) and at least one additional casting core (160) extending spanwise into the airfoil (146) of the pattern material (144), wherein: at least in a portion of the pattern material (144) outside the airfoil (146) of the pattern material (144), an edge portion (184,186) of the metallic casting core (162,164) is recessed relative to the cross-section of an adjacent portion of the at least one additional casting core (160).