Wire EDM Gap Voltage Control to Prevent Capacitor Charge Buildup
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Solution Overview
Problem
Capacitors in the power circuit of wire electrical discharge machines can build up electric charge, causing gap voltage fluctuations that lead to failures in machining due to incorrect voltage readings and subsequent inappropriate machining operations.
Innovation Solution
A controller is implemented in the wire electrical discharge machine to detect discharges and prevent the supply of machining current by the second power circuit if a discharge occurs during the application of the first voltage, thereby avoiding the accumulation of electric charge on the capacitor and maintaining stable voltage across the electrode gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a capacitor is included in the power circuit to apply spark inducing voltage between the electrodes, then the voltage application capability is improved, but the capacitor builds up electric charge causing gap voltage fluctuation and machining failure
Solution Approach 1:
The controller performs preliminary detection of discharge occurrence before machining current supply. By detecting whether a discharge occurs during the application of the first voltage (spark inducing voltage) before the second voltage (machining voltage) is applied, the system takes preliminary action to prevent charge buildup on the capacitor that would otherwise cause gap voltage fluctuation and machining failure.
2Productivity
If machining current is supplied between the electrodes, then the workpiece machining is achieved, but the capacitor builds up electric charge causing gap voltage fluctuation
Solution Approach 1:
The controller uses feedback from discharge detection to control machining current supply. The detection unit detects whether a discharge occurs during the application of the first voltage, and based on this feedback information, the control unit decides whether to supply the second voltage (machining current). This feedback mechanism prevents capacitor charge buildup that would cause gap voltage fluctuation while maintaining productive machining when conditions are appropriate.
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 solution prevents failures in machining by ensuring that machining current is not supplied when a discharge occurs during the application of the first voltage, thereby maintaining stable gap voltage and preventing undesired machining due to capacitor-induced fluctuations.
Implementation Method 1
a voltage (spark inducing voltage) for inducing electrical discharge is applied across the electrode gap between the wire electrode and the workpiece, and when a discharge is generated, a machining current (discharge current) is supplied between the electrodes to machine the workpiece
Implementation Method 2
when a capacitor is included in the power circuit that applies a spark inducing voltage between the electrodes, the capacitor sometimes may build up electric charge due to the supply of the machining current between the electrodes
Data Source
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AI summary
A wire electrical discharge machine (10) includes: a gap voltage detector (20) for detecting a voltage (V) across an electrode gap (EG); a first voltage control unit (50) for applying a first voltage (VI) to the electrode gap (EG); a discharge determiner (52) for determining whether or not the electrode gap (EG) is in a discharging state during application of the first voltage (VI); and a second voltage control unit (54) for supplying a machining current through the electrode gap (EG) when the electrode gap (EG) is in a discharging state. After a supply of the machining current to the electrode gap (EG), even when a discharge is induced by the next application of the first voltage (V1) to the electrode gap (EG), the second voltage control unit (54) prohibits application of a second voltage (V2) to the electrode gap (EG).