Wire EDM Pulse Instability Control to Prevent Wire Breakage
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Solution Overview
Problem
Existing wire electrical discharge machines face issues with wire electrode breakage due to unclear definitions of normal and abnormal discharge states, leading to inefficiencies in machining processes.
Innovation Solution
A wire electrical discharge machine that calculates the degree of instability based on the number of non-discharge pulses and adjusts machining conditions, such as off time, to reduce wire electrode breakage by stabilizing the discharge state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If weight coefficients are pre-defined for normal and abnormal discharge pulses to calculate energy evaluation data, then wire breakage can be reduced by adjusting off time, but the definitions of normal and abnormal discharge states remain unclear leading to inefficiencies
Solution Approach 1:
The patent changes the parameter used for discharge state evaluation from pre-defined weight coefficients of normal and abnormal pulses to the actual discharge delay time measured for each pulse. This allows clear differentiation between stable and unstable discharge states based on measurable physical parameters, enabling more precise control of the off time to prevent wire breakage while maintaining machining efficiency.
Solution Approach 2:
The patent replaces the mechanical classification system (pre-defined categories of normal and abnormal pulses with fixed weight coefficients) with a direct measurement approach using discharge delay time. This substitution eliminates the ambiguity of categorical definitions and provides a continuous, precise metric for evaluating discharge stability and controlling machining parameters.
2Reliability
If the off time is increased to reduce wire breakage, then wire electrode stability improves, but machining productivity decreases
Solution Approach 1:
The patent implements dynamic adjustment of the off time parameter based on real-time monitoring of discharge delay time. Instead of using a fixed or pre-determined off time, the system continuously adapts the off time duration according to the actual discharge stability conditions, allowing optimal balance between wire protection and machining speed under varying operational conditions.
Solution Approach 2:
The patent introduces a feedback mechanism where the discharge delay time is measured for each voltage pulse and used to adjust subsequent machining parameters including the off time. This closed-loop control ensures that the off time is extended only when discharge instability is detected, rather than maintaining a consistently conservative setting that would reduce overall productivity.
3Productivity
If voltage pulses are applied with short intervals to maintain high machining speed, then productivity increases, but wire breakage risk increases due to insufficient cooling and charge accumulation
Solution Approach 1:
The patent applies preliminary action by measuring the discharge delay time before each voltage pulse and using this information to determine the appropriate off time for the next pulse. This anticipatory adjustment ensures that sufficient cooling and charge dissipation time is provided before the next discharge event, preventing wire breakage while maintaining high overall machining speed through optimized pulse timing.
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 machine effectively reduces wire electrode breakage by dynamically adjusting machining conditions in response to discharge instability, enhancing machining stability and efficiency.
Implementation Method 1
applies a voltage between a workpiece to be machined and a wire electrode to generate electrical discharge at an electrode gap formed between the workpiece and the wire electrode
Implementation Method 2
measuring, for each of the voltage pulses, a discharge delay time which is a time from a start of application of the voltage pulse until a voltage drop due to occurrence of discharge
Data Source
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AI summary
A wire electrical discharge machine (10) includes: a pulse detection unit (60) configured to detect voltage pulses repeatedly applied between a workpiece (W) and a wire electrode (12); an instability calculation unit (66) configured to calculate the degree of instability indicating how unstable the discharge state is, by using the number of non-discharge pulses that present no voltage drop due to electrical discharge, among the pulses detected per unit time by a pulse detection unit (60); and a machining condition changing unit (68) configured to change a machining condition for the workpiece (W), based on the calculated degree of instability.