Molding Tool Alignment for Ceramic Core Cooling Features
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Solution Overview
Problem
Conventional ceramic core manufacturing in gas turbine engines faces challenges with low green body strength, distortion, and breakage due to the unsupported interior surface during firing, and maintaining alignment of impingement cooling jets is difficult in investment casting processes, leading to inefficient cooling performance.
Innovation Solution
A molding tool with a first and second mold portion and a sacrificial alignment member is used to form crossover holes and impingement jet receiving features, ensuring precise alignment and focused cooling fluid jets for improved cooling performance in ceramic cores during casting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ceramic core manufacturing is used, then the core can be produced, but the green body strength is low and the core is subject to distortion and breakage during firing
Solution Approach 1:
The patent applies preliminary action by pre-forming a support structure within the green body before firing. The support structure is created by placing a sacrificial material (such as a wire or rod) into the green body that will later be removed, leaving a void space that prevents distortion during firing. This preliminary structural reinforcement allows the weak green body to maintain its shape through the firing process.
Solution Approach 2:
The patent uses an intermediary support structure made of sacrificial material that temporarily reinforces the green body during handling and firing. This intermediary element acts as a mediator between the weak green body and the requirements for structural stability, allowing the core to be fired successfully and then having the sacrificial material removed to create the desired internal geometry.
2Reliability
If impingement cooling jets are formed in ceramic cores, then cooling efficiency is improved, but maintaining alignment of the jets is difficult during investment casting
Solution Approach 1:
The patent employs an intermediary alignment tool or fixture that maintains the precise spatial relationship between the crossover hole and the impingement jet receiving feature during the investment casting process. This alignment tool acts as a mediator that ensures the jet will be properly positioned relative to the target surface, transferring the alignment information from the mold-making stage through to the final casting.
Solution Approach 2:
The patent applies preliminary action by pre-establishing the alignment geometry in the mold-making stage. The mold is constructed with built-in alignment features or registration marks that ensure the crossover hole and impingement jet receiving feature are positioned correctly before the casting process begins. This preliminary alignment prevents misalignment issues during subsequent casting operations.
3Ease of manufacture
If the green body is dried and removed from the mold, then the ceramic core can be fired, but the interior surface remains unsupported and is subject to breakage
Solution Approach 1:
The patent applies preliminary action by inserting a sacrificial support structure into the green body before removal from the mold. This support structure remains in place during drying and provides internal reinforcement to the hollow green body, preventing collapse or breakage of the interior surface. The sacrificial material is later removed after firing to create the desired internal geometry.
Solution Approach 2:
The patent uses beforehand cushioning by providing a sacrificial support structure that cushions and protects the weak green body walls during handling and drying. This temporary support acts as a protective element that prevents damage to the interior surface, allowing the green body to be successfully removed from the mold and fired without breakage.
Data Source
AI summary
A molding tool (10) for manufacturing cooling features in a ceramic core for a casting process includes a first mold portion (12) comprising a crossover hole forming feature (18); a second mold portion (24) comprising an impingement jet receiving forming feature (30) for forming an impingement jet receiving feature having a desired aiming point (32); and a sacrificial alignment member (34) for extending at least partially into the crossover hole forming feature (18) at least partially into the aiming point (32) of the impingement jet receiving forming feature (30) for substantially aligning a central axis (38) of the crossover hole forming feature (18) with the aiming point (32) to maintain a crossover hole and aiming point alignment during casting to ensure that the jet is directed at the aiming point (32) in a resultant cast part.