Turbomachinery Component Machining Using Cast Reference Features
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Solution Overview
Problem
The manufacturing of turbomachinery components for gas turbine engines faces challenges due to large manufacturing tolerances in near-net-shape casting processes, leading to reduced accuracy and engine performance.
Innovation Solution
A method involving an intermediate design with detectable reference features formed during investment casting, allowing for a defined datum system to accurately machine the components, reducing tolerances and achieving ideal surface transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If near-net-shape casting process is used to manufacture turbomachinery components, then manufacturing productivity is improved, but manufacturing precision deteriorates due to large tolerances
Solution Approach 1:
The patent applies preliminary action by forming detectable reference features during the casting process itself, before machining operations. These reference features are created as integral parts of the cast component, allowing subsequent machining to be precisely located and aligned. This preliminary establishment of reference points enables tight tolerances to be achieved in machining without requiring tighter casting tolerances, thus maintaining high productivity while improving precision.
Solution Approach 2:
The patent replaces traditional mechanical datum systems (which rely on physical surfaces and fixtures) with a detection-based system. Optical or sensor-based detection methods are used to locate the reference features and establish datums dynamically. This substitution allows for more precise and flexible datum definition, reducing the impact of casting tolerances on final component accuracy while maintaining efficient manufacturing processes.
2Ease of manufacture
If datum system is defined using cast surfaces, then ease of manufacture is improved, but manufacturing precision deteriorates due to aggregate tolerance
Solution Approach 1:
The patent extracts the datum definition from the cast surfaces themselves and separates it into distinct reference features that are deliberately formed during casting. By taking out the datum function from the general cast surfaces and concentrating it in specific, detectable reference features, the system achieves more precise datum establishment. This allows easy manufacture to be maintained through simple casting operations while precision is improved through the dedicated reference features that minimize aggregate tolerance accumulation.
Solution Approach 2:
The patent introduces detectable reference features as intermediaries between the casting process and the machining process. These reference features serve as a mediator that links the two processes with high precision. The reference features are formed during casting (maintaining ease of manufacture) but provide precise, detectable locations for machining operations (improving manufacturing precision by reducing aggregate tolerance). This intermediary element bridges the gap between the imprecise casting process and the precision machining process.
3Manufacturing precision
If intermediate design with greater platform thickness is used, then manufacturing precision is improved through better datum definition, but loss of substance increases due to additional material removal
Solution Approach 1:
The patent applies preliminary action by forming the detectable reference features during the casting process itself, before any machining occurs. This allows the intermediate design with increased platform thickness to be cast efficiently without requiring additional machining operations to create reference features. The material is added only where necessary to provide stable datum surfaces and reference features, minimizing overall material removal while achieving the precision benefits of the intermediate design.
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
This approach enhances the accuracy of turbomachinery components, improves aerodynamic efficiency, and reduces manufacturing costs by allowing for tighter tolerances and more precise surface formations.
Implementation Method 1
Molten metal is poured into the void, through the same opening that the pattern is removed through. The molten metal adopts the shape of the void, and hence the shape of the component to be formed. Once the metal is solidified, the mould is broken to remove the component.
Implementation Method 2
The pattern is then removed from the mould, by melting or chemical leaching (dissolving) to leave a void in the mould, in the shape of the component to be cast.
Data Source
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AI summary
The present disclosure provides a method of manufacturing a turbomachinery component for a gas turbine engine, comprising: receiving an ideal design of the turbomachinery component, the turbomachinery component comprising: an aerofoil portion comprising an aerofoil surface and having an ideal aerofoil wall thickness; and a platform portion comprising a platform surface coterminous with the aerofoil surface, the platform portion having an ideal radial platform thickness along a radial direction; determining an intermediate design of the turbomachinery component comprising an intermediate platform portion having an intermediate platform surface and an intermediate radial platform thickness which is greater than the ideal radial platform thickness; forming, by an investment casting process, an intermediate turbomachinery component based on the intermediate design, wherein the intermediate turbomachinery component comprises at least one detectable reference feature formed by an internal core element during the investment casting process; defining a datum system for machining the intermediate turbomachinery component comprising detecting the at least one reference feature and defining a radial datum based on the at least one reference feature; and machining the intermediate turbomachinery component using the datum system to remove material from at least the intermediate platform portion of the intermediate turbomachinery component to create a machined turbomachinery component.