Wire EDM Contact Vibration Control to Prevent Short-Circuits

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Solution Overview

Problem

In wire electrical discharge machining, workpiece distortion can cause parts to enter machining grooves, leading to repeated short-circuits when the wire electrode is moved backward to avoid contact, resulting in longer machining times.

Innovation Solution

A control method that detects contact between the wire electrode and workpiece, stops movement, and vibrates the wire electrode about a stop position, resuming movement only when a contact release state is detected within a predetermined time or after a specified number of vibrations, eliminating the need to move the electrode backward.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wire electrode is moved backward to avoid contact with the workpiece, then contact is avoided, but the wire electrode may enter the machining groove and cause repeated short-circuits

Engineering Contradiction:
Improvecontact avoidance reliabilityVSAvoidmachining efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies mechanical vibration to the wire electrode through a vibration unit that generates vibrational movement in the wire electrode along its length direction. When contact between the wire electrode and workpiece is detected, the vibration unit activates to vibrate the wire electrode, preventing it from entering the machining groove while maintaining forward movement, thereby avoiding repeated short-circuits and improving machining efficiency

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The patent introduces dynamic control by switching between movement state and vibration state based on contact detection. The wire electrode transitions from pure forward movement to vibrational movement when contact is detected, and back to forward movement when contact is released, creating a dynamic response that adapts to real-time machining conditions

Inventive Principle:
Principle #15Dynamics

2Reliability

If the wire electrode is moved backward repeatedly to terminate short-circuit, then short-circuit is terminated, but machining time increases

Engineering Contradiction:
Improveshort-circuit terminationVSAvoidmachining time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The vibration unit generates rapid vibrational movement of the wire electrode along its length direction when contact is detected. This vibration quickly separates the wire electrode from the workpiece contact point, terminating the short-circuit condition much faster than backward movement while maintaining the forward machining direction and overall machining efficiency

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

Instead of moving backward to terminate contact, the system rushes through the contact event by applying vibration that quickly separates the wire from the workpiece surface. This allows the machining process to continue forward without reversing direction, effectively skipping the time-consuming backward movement step

Inventive Principle:
Principle #21Skipping (Rushing through)

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 approach prevents short-circuits without reversing the wire electrode, ensuring smooth and efficient machining even when the workpiece distorts, reducing machining time and preventing re-contact with the groove.

Implementation Method 1

vibrate the wire electrode about a stop position at which the relative movement of the wire electrode has been stopped

Methodology Applied
Scientific EffectVibration: Vibration

Implementation Method 2

generating electrical discharge at an electrode gap between a workpiece and a wire electrode

Methodology Applied
Scientific EffectElectrical discharge: Electric Spark

Data Source

PatentEP3789147B1Wire electrical discharge machine and control method
Publication Date: 2023.06.07 FANUC LTD
  • EP3789147B1 patent drawingFigure 1
  • EP3789147B1 patent drawingFigure 2
  • EP3789147B1 patent drawingFigure 3

AI summary

A wire electrical discharge machine (10) includes: a detection unit (66) configured to detect a contact state in which the wire electrode (12) contacts the workpiece (W), and a contact release state in which the wire electrode (12) that is in the contact state is separated from the workpiece (W); a vibration unit (68) configured to, if the contact state is detected during the machining of the workpiece (W), stop relative movement of the wire electrode (12) and vibrate the wire electrode (12) about a stop position (P) at which the relative movement of the wire electrode (12) has been stopped; and a relative movement control unit (64) configured to resume relative movement of the wire electrode (12) if the contact release state is detected until a predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode (12) is vibrated reaches a predetermined number of times.