Investment Casting Core Ball-Chute Support Fillet Radius
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Solution Overview
Problem
The existing investment casting process for turbine blade assemblies often results in high stress points due to small fillet radii, which can lead to breakage during processing and operational mechanical and thermal stresses in the finished blades.
Innovation Solution
The use of an investment casting core with a ball-chute support feature and shelf support feature, where the ball-chute support extends from the shelf to the serpentine feature with a chute length less than four times the smallest diameter, and a local fillet radius greater than half the diameter, providing increased strength and reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional investment casting core design is used with small fillet radii, then the core can be manufactured with standard processes, but high stress points are created that increase breakage risk during casting and operation
Solution Approach 1:
The patent applies parameter changes by modifying the fillet radius dimension from small (traditional) to large (at least 0.02 inches or greater than half the ball-chute diameter). This parameter change directly reduces stress concentrations and eliminates high stress points that cause breakage during casting and operation, while maintaining manufacturability through the standardized core design
2Strength
If ball-chute support features with longer chute lengths are used, then support to serpentine features is improved, but stress concentrations increase and durability decreases
Solution Approach 1:
The patent optimizes the chute length parameter by specifying it be less than four times the smallest diameter of the ball-chute support feature. This parameter optimization provides adequate support to serpentine features while preventing excessive stress concentrations, thereby improving durability and reducing breakage risk during casting and operation
3Strength
If more metal is used in ball-chute support features, then strength and stress resistance are improved, but the weight of the turbine blade assembly increases
Solution Approach 1:
The patent optimizes the dimensions of ball-chute support features by specifying the chute length be less than four times the smallest diameter and the local fillet radius be at least 0.02 inches or greater than half the diameter. These parameter specifications provide adequate stress resistance and structural integrity while minimizing the amount of metal required, thereby reducing the overall weight of the turbine blade assembly
Data Source
AI summary
An apparatus relating to engineering the geometry for a ball-chute support feature in an investment casting core. The investment casting core is for an airfoil region having at least one serpentine feature and at least one inlet feature coupled to the at least one serpentine feature by a ball-chute support feature. The investment casting core is leached out to form cooling passages in the airfoil.