EDM Hole Drilling with Pressure Feedback Control
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Solution Overview
Problem
The existing electric discharge machining (EDM) process for creating cooling holes in gas turbine engine components lacks real-time feedback and control, leading to variations in airflow and potential non-conforming hardware due to lack of instant feedback on airflow and hole breakthrough, and inability to prevent wall strikes during machining.
Innovation Solution
An apparatus and method utilizing a pressure transducer connected to the workpiece to sense pressure within the cavity and provide feedback to control the EDM process, allowing for real-time monitoring and adjustment of machining parameters, including using a dielectric fluid tank and fixture to secure the workpiece and control the electric discharge machine based on sensed pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional EDM process is used without real-time monitoring, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to lack of control over hole breakthrough and wall strikes
Solution Approach 1:
The patent implements real-time feedback by monitoring voltage and current signals during EDM drilling. When breakthrough is detected through signal analysis, the system automatically adjusts drilling parameters or stops the process to prevent wall strikes, thereby improving hole dimension accuracy without requiring complex external monitoring equipment
Solution Approach 2:
The patent replaces complex mechanical monitoring systems with electrical signal analysis. By analyzing voltage and current characteristics during the EDM process, the system detects breakthrough and controls drilling depth, substituting mechanical measurement methods with simpler electrical sensing
2Reliability
If EDM drilling continues without real-time breakthrough detection, then productivity is maintained, but reliability deteriorates due to wall strikes and non-conforming parts
Solution Approach 1:
The system continuously monitors drilling parameters and provides real-time feedback to detect breakthrough. This allows the process to maintain high productivity by avoiding unnecessary drilling while ensuring reliability through automatic detection of breakthrough conditions and prevention of wall strikes
Solution Approach 2:
The system performs preliminary detection of breakthrough conditions by analyzing voltage and current signals before actual breakthrough occurs. This preliminary action allows the system to prepare for breakthrough, adjust parameters in advance, and prevent wall strikes while maintaining optimal drilling speed
3Manufacturing precision
If no real-time airflow monitoring is implemented, then device complexity is reduced, but manufacturing precision deteriorates due to inability to control in-process airflow
Solution Approach 1:
The system uses voltage and current signal feedback during EDM drilling to indirectly monitor and control airflow conditions. By analyzing changes in electrical parameters that correlate with airflow variations, the system achieves airflow control without requiring separate airflow sensing equipment
Solution Approach 2:
The voltage and current monitoring system serves multiple functions: it controls the EDM process, detects breakthrough, and simultaneously provides information about airflow conditions. This multi-functionality achieves airflow control without adding dedicated monitoring devices
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 real-time monitoring and control of the EDM process, reducing rework and non-conforming parts by providing instant feedback on airflow and preventing wall strikes, thus improving the accuracy and efficiency of hole drilling.
Implementation Method 1
a pressure transducer connected to the pressure port of the fixture for sensing pressure within the cavity of the workpiece
Implementation Method 2
an electric potential difference exists between the electrode and the workpiece and a spark discharge will arc the gap therebetween, thereby eroding a small amount of material from the workpiece adjacent the electrode
Implementation Method 3
a spark discharge will arc the gap therebetween, thereby eroding a small amount of material from the workpiece
Implementation Method 4
The dielectric fluid assists in the formation of the spark discharges, cools the workpiece during repeated spark discharges and carries away material eroded from the workpiece
Data Source
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AI summary
An apparatus and method for machining apertures into a conductive workpiece (10) is disclosed. The apparatus has a tank (34) capable of holding a dielectric fluid, and a fixture (24) for holding the workpiece in the tank. An electric discharge machine with an electrode (36), a power supply connected to the electrode that produces machining pulses for electric discharge machining through the workpiece, and a controller (39) for regulating the power supply and electrode position is also part of the apparatus. Finally, the apparatus has a pressure transducer (33) connected to the fixture, and a process controller (38) in communication with the electric discharge machine controller and pressure transducer.