Handheld EDM Fastener Removal in Limited-Access Assemblies
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Solution Overview
Problem
Conventional EDM devices are limited in accessibility and accuracy due to the need for direct line of sight and manual operation, making them unsuitable for machining fasteners in complex assemblies with limited access or mechanical constraints.
Innovation Solution
A hand-held EDM device with a housing that can be positioned proximal to a fastener using alignment features, a movable erosion electrode, and a dielectric fluid management system, allowing for remote operation and precise control of the machining process, including the use of a dielectric outlet for fluid evacuation and pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional EDM devices are used with manual operation, then the operator can control the machining process, but the device is limited to easily accessible regions requiring direct line of sight
Solution Approach 1:
The patent replaces manual mechanical positioning with an automated positioning system that uses alignment features (alignment portions on the housing locating against alignment features on the workpiece) to automatically position the erosion electrode relative to the fastener, eliminating the need for manual positioning while expanding accessibility to hard-to-reach locations
Solution Approach 2:
The patent introduces alignment features as intermediaries between the housing and workpiece that facilitate automatic positioning and sealing. These alignment features act as mediators that enable the device to locate and seal against workpiece surfaces in inaccessible regions without requiring direct operator intervention or line of sight
2Measurement precision
If manual positioning is used to maintain electrode position, then positioning accuracy can be achieved in accessible regions, but the operator must apply hand pressure which limits reach
Solution Approach 1:
The patent replaces manual positioning with an automated positioning mechanism where the erosion electrode is movable relative to the housing along a controlled axis. The housing itself is positioned by alignment features rather than hand pressure, enabling precise electrode positioning in locations beyond operator reach
3Adaptability or versatility
If the housing is positioned proximal to the fastener for remote operation, then accessibility to inaccessible locations is improved, but sealing against the workpiece surface becomes challenging
Solution Approach 1:
The patent uses alignment features as intermediaries that serve dual functions: positioning the housing relative to the workpiece and creating reliable seals. The alignment portions on the housing locate against corresponding alignment features on the workpiece, providing both mechanical positioning and sealing contact surfaces that work effectively in inaccessible regions
Solution Approach 2:
The patent creates equipotential sealing surfaces through the alignment features where the housing and workpiece make contact. This ensures uniform pressure distribution and reliable sealing across the interface, maintaining sealing effectiveness regardless of the device's position or orientation in inaccessible locations
4Productivity
If conventional machining techniques are used on seized bolted joints, then material removal can be achieved, but the work hardening nature of materials prevents effective machining
Solution Approach 1:
The patent applies electro-discharge machining parameters (electrical discharge, pulsed waveform, dielectric fluid) instead of conventional mechanical machining parameters. This fundamental parameter change allows effective material removal from work-hardened, seized fasteners by using electrical erosion rather than mechanical cutting, overcoming the limitations of conventional techniques on hardened materials
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
Enables the machining of fasteners in inaccessible locations without manual intervention, reducing the risk of incorrect erosion and improving operational convenience and efficiency by maintaining a secure seal and precise control over the machining process.
Implementation Method 1
Electric Discharge Machining (EDM) is a well-known technique that is used for the machining of metal materials. EDM as the title suggests creates an electrical discharge by the removal of material from a workpiece.
Implementation Method 2
a dielectric inlet being configured to deliver a dielectric fluid to a region between the erosion electrode and the fastener
Data Source
AI summary
An electro-discharge machining (EDM) device that includes a housing, an erosion electrode, a ground electrode, and a dielectric inlet. The housing is configured to be positioned on a surface of a workpiece and proximal to a fastener to be eroded. The planar erosion electrode is positioned at least partially within the housing, with the erosion electrode being movable relative to the housing in a first axis. The first axis is substantially normal to a longitudinal axis of the fastener. The ground electrode is conductively connected to the fastener. The dielectric inlet is configured to deliver a dielectric fluid to a region between the erosion electrode and the fastener.