Turbine Blade Platform Cavity Machining with Small Sealed Openings
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Solution Overview
Problem
Existing methods for creating cavities in turbine blade platforms for cooling, such as casting, drilling, and spark erosion, result in large openings that are difficult to seal, especially in nickel-based super alloys, and do not allow for adaptable cooling channel designs.
Innovation Solution
A method involving a spark erosion technique using a rigid electrode to create a first bore and widen it fan-like, generating a small starting opening that can be easily sealed, with additional bores created at angular offsets to form a large cavity, and optionally pivoting the electrode to produce cavities with triangular, diamond, or star-shaped contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If casting cores are used to generate cavities during blade platform casting, then cavities can be formed for cooling fluid passage, but large openings are created that are difficult to seal in nickel-based super alloys
Solution Approach 1:
The cavity formation process is segmented into two distinct phases: first creating a through-bore with a drilling tool, then widening it fan-like with a spark erosion electrode. This segmentation allows the initial opening to be small and easily sealed, while the final cavity achieves the required large volume for effective cooling.
Solution Approach 2:
A through-bore is preliminarily created before the final cavity formation. This preliminary bore provides a controlled small opening that can be sealed easily, while subsequent fan-like widening creates the large cavity volume needed for cooling without requiring the final opening to be large.
2Volume of moving object
If drilling and spark erosion methods are used to introduce cavities subsequently, then cavities can be created in cast blade platforms, but large openings are again created requiring soldering or welding
Solution Approach 1:
The process separates opening creation from cavity widening. The drilling tool creates a precise small-diameter through-bore, while the spark erosion electrode subsequently widens it fan-like. This segmentation enables independent control of opening size and cavity volume, achieving both small sealed openings and large cooling cavities.
Solution Approach 2:
The spark erosion electrode widens the bore in a fan-like pattern, expanding the cavity laterally rather than uniformly. This dimensional approach allows the cavity to achieve large volume while the opening at the surface remains constrained to a small diameter that is easy to seal.
3Adaptability or versatility
If curved electrodes are guided on circular paths to produce cooling channels, then cooling channels can be created, but a complicated tool is required and adaptability to local cooling requirements is limited
Solution Approach 1:
The spark erosion electrode can be dynamically positioned and oriented during the widening process to create fan-like cavities of various shapes and orientations. This dynamic control allows adaptation to local cooling requirements without requiring complex pre-programmed curved electrode paths.
Solution Approach 2:
By changing the orientation and positioning parameters of the spark erosion electrode during the widening process, cavities with different geometries can be created to match local cooling requirements. This parameter control provides versatility without increasing tool complexity.
4Shape
If right-angled guide tubes are used to bend electrodes for undercut erosion, then undercuts can be eroded, but relatively large feed openings result in the workpiece
Solution Approach 1:
The process separates the function of creating access openings from the function of creating undercut geometry. The drilling tool creates small through-bores, while the spark erosion electrode subsequently creates the undercut fan-like cavities. This segmentation allows undercut geometry to be achieved without requiring large feed openings.
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 method allows for the creation of large cavities with minimal initial opening size, which can be easily sealed or left as fluid outlets, effectively addressing the sealing challenges and enabling adaptable cooling designs in turbine blades.
Implementation Method 1
widening the first bore in the manner of a fan by means of a spark erosion method, in particular using a rigid electrode in the form of a wire or rod
Data Source
AI summary
A method for producing a cavity in a blade platform of a blade, in particular of a turbine blade, as part of a blade-platform cooling system, wherein the method has the steps of: producing a first bore from a first platform lateral face in the direction of an opposite second platform lateral face, with a first opening in the first platform lateral face being created, and expanding the first bore in a fan-like manner by an electrical discharge machining method, in particular using a wire- or bar-form electrode, such that the first opening, created in the first step, of the first bore represents the starting point of the fan-like expansion. A blade is produced in particular with such a method.