Curved Ceramic Electrode Carrier for Inter-Blade EDM Machining
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Solution Overview
Problem
Existing EDM devices face challenges in accessing confined and tortuously shaped areas within gas turbine engines, such as the inter-blade zone, while maintaining electrical insulation, mechanical strength, and low wear rates, and efficiently supplying dielectric liquid for machining.
Innovation Solution
A one-piece ceramic electrode carrier device with a curved and rectilinear design, featuring a curved conduit for electrode passage and multiple coaxial curved ducts for dielectric liquid supply, optimized through additive manufacturing and abrasive flow machining, ensures precise geometry and efficient dielectric immersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard electrode holder device is used, then electrical insulation and mechanical strength are maintained, but accessibility to confined inter-blade zones is insufficient
Solution Approach 1:
The electrode holder device incorporates a curved portion with a specific curvature radius that enables the device to navigate around turbine blades and access confined inter-blade zones. The curved conduit and dielectric liquid supply ducts are designed with appropriate curvature to follow the geometric constraints of the machining area while maintaining functional performance.
Solution Approach 2:
The device is divided into distinct functional portions: a rectilinear portion for connection to the EDM machine, a curved portion for navigating to the inter-blade zone, and multiple conduits for different functions (electrode passage, dielectric supply). This segmentation allows each portion to be optimized for its specific function while maintaining overall device performance.
2Reliability
If the curved conduit and ducts are made of ceramic material, then electrical insulation and low wear rate are improved, but manufacturing complexity increases
Solution Approach 1:
The internal surfaces of the curved conduit and dielectric liquid supply ducts are finished to a specific arithmetic roughness parameter (Ra) range, optimized for laminar flow of dielectric liquid. This parameter control is achieved through additive manufacturing process optimization and post-processing techniques, balancing manufacturing feasibility with functional performance.
Solution Approach 2:
Traditional mechanical machining methods are replaced with additive manufacturing technology for producing the curved ceramic components. This substitution enables the creation of complex curved geometries that would be difficult or impossible to manufacture using conventional machining, while maintaining the desired ceramic material properties.
3Reliability
If multiple coaxial curved ducts are added for dielectric liquid supply, then laminar flow and machining stability are improved, but device complexity increases
Solution Approach 1:
Multiple dielectric liquid supply ducts are arranged coaxially within the curved portion of the device, with smaller ducts nested within or alongside larger ones. This nested arrangement allows multiple dielectric liquid flow paths to be integrated into a compact curved structure, achieving laminar flow and machining stability without excessive device complexity.
Solution Approach 2:
The curved portion of the device serves multiple functions simultaneously: it provides structural support for navigating to the inter-blade zone, contains conduits for electrode passage, and houses multiple coaxial ducts for dielectric liquid supply. This multi-functionality reduces the need for separate components while achieving the desired machining stability.
4Manufacturing precision
If additive manufacturing is used to produce the ceramic device, then manufacturing flexibility and geometric precision are improved, but production time and cost increase
Solution Approach 1:
The additive manufacturing process parameters, including layer thickness, infill density, and post-processing requirements, are optimized in advance to achieve the desired geometric precision and surface roughness for laminar flow. This preliminary optimization reduces the number of iterations and rework required, improving production efficiency while maintaining precision.
Solution Approach 2:
The device is manufactured from ceramic materials that combine electrical insulation properties with mechanical strength and wear resistance. The use of ceramic additive manufacturing technologies enables the production of complex curved geometries with integrated conduits, achieving functional performance while reducing the need for separate assembly operations.
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
The device provides enhanced accessibility, reduced friction, and stable electric arcs, enabling longer machining times and automation in difficult-to-reach areas with improved machining conditions.
Implementation Method 1
promote a laminar flow of liquid in the machining area
Implementation Method 2
reduced friction
Implementation Method 3
retain the properties of standard guides (electrical insulation...)
Implementation Method 4
the curved extension and the second curved conduit being made of ceramic
Implementation Method 5
stability of the electric arc created between the electrode concerned and the part
Implementation Method 6
The machining area is completely immersed in the dielectric
Implementation Method 7
a post-processing of the interior of the second curved duct, and preferably of the entire interior of said one-piece curved portion, is carried out, by abrasive flow machining (AFM)
Data Source
Figure 1~3
Figure 4~6
Figure 7
AI summary
The invention relates to a device for holding one or more electrodes for electrical discharge machining, comprising a body (41) having a rectilinear portion (43a) in which at least one first duct (45) is provided for the passage of one or more electrodes (21). The body further has an integral curved portion (43b) in which (at least) one second curved dielectric-fluid-supply duct (47) is provided, and in which is provided a curved extension (45b) of the at least one first duct. The curved extension and the second curved duct are made of ceramic, with an inner mean roughness of Ra < 2µm.