Angled Tip Rods for Swept Airfoil Casting
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Solution Overview
Problem
In gas turbine engines, radially oriented tip rods often fail to meet producible tip rod sizing criteria due to the curvature of blade cores at the tip, leading to breakage during casting and increased scrap rates in turbine blades with airfoil sweep configurations.
Innovation Solution
The use of alumina or quartz tip rods positioned at an angle to meet sizing criteria, with additional core support features like bumpers to ensure stability and producibility, and obliquely-angled through-holes to facilitate core stability and dirt purge in turbine blades with airfoil sweep.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radially oriented tip rods are used in turbine blades with airfoil sweep, then the blade core positioning function is provided, but the rods fail to meet sizing criteria due to curvature and break during casting
Solution Approach 1:
The patent applies asymmetry by transitioning from radially oriented rods to angled tip rods that are positioned at specific angles (e.g., 45 degrees) relative to the radial direction. This asymmetric positioning allows the rods to meet minimum embedding length and core thickness requirements while accommodating the curved geometry of swept airfoil blades, thereby preventing breakage during casting.
Solution Approach 2:
The patent applies local quality by positioning tip rods at specific locations and angles where they can effectively meet sizing criteria. The rods are strategically placed to provide core positioning functionality while locally adapting to the curved blade geometry, ensuring they meet minimum embedding length and core thickness requirements without breaking during casting.
2Stability of the object's composition
If tip rods are made longer to meet embedding requirements, then core positioning stability is improved, but the unsupported length increases causing breakage
Solution Approach 1:
The patent uses asymmetric angular positioning of tip rods to optimize both embedding length and unsupported length. By positioning rods at specific angles (e.g., 45 degrees) rather than radially, the design achieves adequate embedding depth for stability while reducing the exposed unsupported portion, thereby preventing breakage during casting.
Solution Approach 2:
The patent changes the geometric parameters of tip rod positioning by introducing specific angular orientations (e.g., 45 degrees relative to radial direction). This parameter change allows simultaneous optimization of embedding length for stability and reduction of unsupported length to prevent breakage during the casting process.
3Stability of the object's composition
If multiple tip rods are connected by tip plenum, then core stability is improved, but the complexity of the casting process increases
Solution Approach 1:
The patent extracts or removes the tip plenum component from the design. Instead of connecting multiple tip rods through a tip plenum, the invention uses individually positioned angled tip rods that provide sufficient core stability on their own, thereby simplifying the casting process and reducing manufacturing complexity.
Data Source
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AI summary
A core is provided for fabricating a blade to include an airfoil (220). The airfoil (220) includes pressure and suction surfaces (221, 222), leading and trailing edges (223, 224) extending along the pressure and suction surfaces (221, 222) and a tip shelf (225) with a first sweep configuration (701) and a wall (226, 310). The core includes channel sections configured to form internal channels (702) within the airfoil (220) by casting processes and tip rods extending from respective portions of the channel sections proximate to a tip shelf (225) location. The respective portions of the channel sections have a second sweep configuration (430) corresponding to the first sweep configuration (701). The tip rods are configured to extend through the wall (226, 310) at an angle of about 5-12 degrees inclusive relative to a normal angle of the wall (226, 310) during the casting processes to form through-holes angled at about 5-12 degrees inclusive in the wall (226, 310).