Angled Tip Rods for Swept Turbine Blade Core Casting
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Solution Overview
Problem
In gas turbine engines, radially oriented tip rods 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 extending at an angle of 5-12 degrees relative to the normal angle of the wall, along with channel sections and bumpers, to form through-holes that meet the required sizing criteria and provide core stability during the casting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If radially oriented tip rods are used in turbine blades with airfoil sweep configurations, then the blade core can be cast with internal channels, but the tip rods fail to meet producible sizing criteria (embedded length and core thickness requirements) due to curvature at the tip, causing breakage during casting
Solution Approach 1:
The tip rods are oriented at an angle (e.g., 10-20 degrees) relative to the radial direction, creating an asymmetric configuration that accommodates the curved geometry of the blade tip while maintaining sufficient embedded length and core thickness. This angular orientation allows the rods to extend from the internal channels through the curved tip surface without violating manufacturing sizing criteria.
Solution Approach 2:
Instead of orienting tip rods purely radially (one dimension), the solution introduces an angular component, orienting them in a different dimensional direction relative to the blade core. This dimensional change allows the rods to navigate the curved tip geometry while meeting embedded length and core thickness requirements.
2Productivity
If tip rods are oriented at an angle to meet sizing criteria, then producibility improves, but the complexity of positioning and orienting the rods during core assembly increases
Solution Approach 1:
The tip rods are pre-positioned and pre-oriented at the correct angles during core assembly before casting. The core design includes features such as angled bore holes or positioning structures that guide the rods into the correct angular orientation, eliminating the need for complex post-assembly adjustments and reducing positioning errors.
Solution Approach 2:
The solution changes the orientation parameter of the tip rods from radial (0 degrees) to an angled configuration (e.g., 10-20 degrees). This parameter change optimizes the rods to meet sizing criteria while the core design incorporates corresponding angular features that simplify positioning, thereby reducing overall assembly complexity despite the angular orientation.
3Stability of the object's composition
If multiple tip rods are used to control core shift in all directions, then core stability improves, but the number of rods increases the likelihood of breakage and manufacturing complexity
Solution Approach 1:
Each angled tip rod is designed to perform multiple functions: controlling radial core shift, controlling tangential core shift, and providing structural support. By making each rod multi-functional, the total number of rods required for stable core positioning is reduced, thereby decreasing the overall probability of breakage and simplifying manufacturing while maintaining comprehensive core position control.
Data Source
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AI summary
A core (401) is provided for fabricating a blade to include an airfoil. The airfoil includes pressure and suction surfaces, leading and trailing edges extending along the pressure and suction surfaces and a tip shelf with a first sweep configuration and a wall. The core includes channel sections (410) configured to form internal channels within the airfoil by casting processes and tip rods (420) extending from respective portions of the channel sections proximate to a tip shelf location. The respective portions of the channel sections have a second sweep configuration corresponding to the first sweep configuration. The tip rods are configured to extend through the wall at an angle of about 5-12 degrees inclusive relative to a normal angle of the wall during the casting processes to form through-holes angled at about 5-12 degrees inclusive in the wall.