Wire EDM Electrode Pin Contact Detection

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Solution Overview

Problem

Existing wire electric discharge machines face challenges in reliably switching between rough machining and finish machining power sources, leading to inconsistencies in machining speed and surface roughness due to uncertainties in the contact state between the wire electrode and the electrode pin, which can result in reduced precision and potential damage to the workpiece.

Innovation Solution

A wire electric discharge machine equipped with a short-circuit detection mechanism and a controller to determine the contact or non-contact state between the electrode pin and the wire electrode, using a switch to ensure the same electric potential and a cleaning fluid jetting device to maintain attachment/detachment conformity, thereby ensuring accurate switching between machining conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a movable electrode pin or driving mechanism is used to switch between rough machining and finish machining power sources, then the machining speed and surface roughness can be improved, but the reliability of power source switching deteriorates due to uncertain contact state detection

Engineering Contradiction:
Improvemachining speedVSAvoidpower source switching reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent replaces the mechanical contact detection method with an electrical detection method. Instead of relying on mechanical switches or position sensors to detect whether the electrode pin contacts the wire electrode, the invention uses electrical continuity detection through the power supply line to determine the contact state, thereby improving switching reliability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback mechanism where the contact state between the electrode pin and wire electrode is continuously monitored through electrical detection. The detection result is fed back to the control system, which automatically adjusts the power source selection based on the actual contact state, ensuring reliable switching between rough and finish machining modes

Inventive Principle:
Principle #23Feedback

2Device complexity

If the contact state between electrode pin and wire electrode is not accurately detected, then the device complexity is reduced, but the manufacturing precision deteriorates due to incorrect power source selection

Engineering Contradiction:
Improvedetection system complexityVSAvoidmachining precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent makes the power supply line serve multiple functions: it not only supplies power for machining but also acts as a detection circuit for contact state monitoring. This multi-functional design eliminates the need for separate detection circuits, maintaining simple device structure while ensuring accurate machining precision through reliable power source selection

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If cleaning fluid jetting is added to maintain electrode pin attachment, then the reliability of contact state is improved, but the device complexity increases

Engineering Contradiction:
Improveelectrode pin attachment reliabilityVSAvoidcleaning system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces cleaning fluid as an intermediary substance to maintain the contact reliability between the electrode pin and wire electrode. The cleaning fluid removes contaminants that could interfere with electrical contact, thereby improving attachment reliability without requiring complex mechanical cleaning mechanisms

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses hydraulic or pneumatic systems to deliver cleaning fluid to the electrode pin contact area. This allows efficient cleaning of the contact surface through fluid pressure, improving contact reliability while keeping the cleaning mechanism relatively simple compared to mechanical scraping or brushing systems

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 solution enables reliable detection and management of the contact state between the wire electrode and the electrode pin, ensuring consistent machining performance, improving machining speed and surface roughness by preventing errors during power source switching, thus protecting the workpiece from damage.

Implementation Method 1

short-circuit detection means for detecting a short circuit between the wire electrode and the workpiece

Methodology Applied
Scientific EffectElectrical conductivity detection: Conduction (electrical)

Implementation Method 2

a switch to make the wire electrode and the workpiece have the same electric potential

Methodology Applied
Scientific EffectElectric potential equalization: Electrical Resistance

Implementation Method 3

a cleaning fluid jetting device to jet cleaning fluid to the attaching/detaching mechanism

Methodology Applied
Scientific EffectFluid spray cleaning: Fluid Spray

Data Source

PatentEP2158993B1Wire electric discharge machine having function of detecting detachment/attachment of an electrode pin
Publication Date: 2013.11.20 FANUC LTD
  • EP2158993B1 patent drawingFigure 1
  • EP2158993B1 patent drawingFigure 2a~2f
  • EP2158993B1 patent drawingFigure 3

AI summary

A wire electric discharge machine capable of detecting a contact and non-contact of an electrode pin to a wire electrode. The wire electric discharge machine has a plurality of machining power sources with respective power supply lines to be selected according to machining conditions, one polarity of each set of the power supply lines is electrically connected to a wire electrode through an electrode pin, and the other polarity of each set of the power supply lines is electrically connected to a workpiece. The wire electric discharge machine comprises an air cylinder for attachment/detachment of the electrode pin to/from the wire electrode, a short-circuit detection circuit for detecting a short circuit between the wire electrode and the workpiece, with one polarity electrically connected to the electrode pin, and the other polarity electrically connected to the workpiece, and a first relay for making the wire electrode and the workpiece have the same potential, and a controller for determining a contact/non-contact between the wire electrode and the electrode pin using the short-circuit detection circuit and the first relay.