Wire EDM Pulse Feedback for Discharge Stability and Breakage Control

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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

VSEngineering Contradiction Analysis

1Productivity

If the number of voltage pulses applied is increased to improve machining efficiency, then productivity increases, but wire electrode breakage risk increases due to accumulated discharge instability

Engineering Contradiction:
Improvemachining efficiencyVSAvoidwire electrode breakage resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control device continuously monitors discharge states by detecting voltage pulses and calculates a degree of instability based on the frequency of abnormal discharges. This feedback mechanism allows real-time adjustment of machining parameters to prevent wire breakage while maintaining productivity. When instability exceeds a threshold, the system automatically reduces the number of voltage pulses or adjusts discharge parameters.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the number of voltage pulses applied to the workpiece based on real-time discharge stability assessment. Rather than using a fixed pulse count, the control device modifies pulse parameters adaptively: reducing pulses when instability is detected and maintaining higher pulses when discharge is stable, thereby optimizing both productivity and wire electrode reliability throughout the machining process.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the voltage application time is shortened to reduce wire electrode stress, then wire breakage risk decreases, but machining efficiency deteriorates due to insufficient material removal

Engineering Contradiction:
Improvewire electrode breakage resistanceVSAvoidmachining efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system changes voltage pulse parameters dynamically based on discharge stability. When discharge is stable, longer voltage application times are used to maintain high machining efficiency. When instability is detected, the system adjusts pulse duration and amplitude to reduce wire stress while still achieving effective material removal. This parameter adaptation resolves the contradiction between wire reliability and machining productivity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the distance between workpiece and wire electrode is reduced to improve machining precision, then manufacturing precision increases, but discharge instability increases leading to wire breakage

Engineering Contradiction:
Improvemachining precisionVSAvoiddischarge stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The control device uses feedback from discharge detection to monitor the stability of electrical discharge at the electrode gap. When the gap distance is reduced to improve precision, the system continuously monitors for signs of discharge instability. If instability is detected, the system adjusts voltage parameters or gap distance to maintain both precision and reliability, preventing wire breakage while preserving machining accuracy.

Inventive Principle:
Principle #23Feedback

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 the stability and reliability of the machining process.

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

Methodology Applied
Scientific EffectElectrical discharge: Electric Spark

Implementation Method 2

generate electrical discharge at an electrode gap... perform electrical discharge machining on the workpiece

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4378611B1Wire electrical discharge machine and wire electrical discharge machining method
Publication Date: 2025.07.23 FANUC LTD
  • EP4378611B1 patent drawingFigure 1
  • EP4378611B1 patent drawingFigure 2
  • EP4378611B1 patent drawingFigure 3

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.