Wire EDM Filter Heating to Prevent Magnesium Swarf Ignition

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Solution Overview

Problem

Wire electrical discharge machines face safety issues due to the oxidation of magnesium swarf, which can lead to intense heat reactions and potential ignition when machining magnesium-containing workpieces, as the existing methods to manage magnesium oxidation, such as acid or alkaline solutions, cause corrosion and conductivity issues.

Innovation Solution

A wire electrical discharge machine configuration that heats the working fluid in the filter and storage tanks to prevent magnesium swarf oxidation, using a heating device to maintain the fluid at a temperature that converts magnesium swarf into magnesium hydroxide, reducing reactivity and preventing filter ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If acid or alkaline solutions are used to dissolve magnesium particles, then magnesium swarf can be removed from the working fluid, but the working fluid causes corrosion of the wire electrical discharge machine and workpiece and electric conductivity becomes too high

Engineering Contradiction:
Improvemagnesium swarf removalVSAvoidcorrosion and high electric conductivity
Core Design Contradiction:
Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter of the working fluid from ambient to elevated temperatures (60-100°C). This temperature change causes magnesium to react with the working fluid and form magnesium hydroxide, which has different properties than metallic magnesium. The temperature parameter change transforms the chemical state of magnesium, allowing it to be removed as hydroxide rather than requiring acid or alkaline solutions that cause corrosion and conductivity issues.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful oxidation reaction of magnesium into a beneficial process. By heating the working fluid, magnesium reacts to form magnesium hydroxide, which then precipitates and can be easily removed. The reaction that would normally be considered harmful (oxidation of magnesium) is controlled and converted into a useful precipitation process that removes magnesium swarf without the need for corrosive chemicals.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If magnesium swarf is allowed to oxidize in air, then the oxidation reaction can proceed naturally, but intense heat is generated which may lead to ignition of the filter

Engineering Contradiction:
Improvenatural oxidation processVSAvoidintense heat and ignition risk
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by heating the working fluid before magnesium swarf is collected in the filter. This pre-heating causes magnesium to react and form magnesium hydroxide in advance, converting the highly reactive metallic magnesium into a stable hydroxide form. This preliminary chemical transformation prevents the subsequent dangerous oxidation that would occur if metallic magnesium were to contact air in the filter, thereby eliminating the ignition risk while maintaining the natural oxidation pathway.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies preliminary anti-action by preventing the harmful oxidation of magnesium before it can occur. By heating the working fluid in advance, magnesium is converted to magnesium hydroxide, which is much less reactive with oxygen than metallic magnesium. This preliminary counter-action neutralizes the reactivity of magnesium, preventing the intense heat generation and ignition risk that would result from natural oxidation in the filter.

Inventive Principle:
Principle #9Preliminary anti-action

3Object-affected harmful factors

If the working fluid is heated to convert magnesium swarf into magnesium hydroxide, then magnesium oxidation is prevented and filter ignition is avoided, but additional energy is required for heating

Engineering Contradiction:
Improvemagnesium oxidation and filter ignition preventionVSAvoidheating energy consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent applies self-service by utilizing the existing working fluid circulation system to distribute heat throughout the system. The working fluid itself serves as the heat transfer medium, and the heating is integrated into the existing fluid circulation infrastructure. This eliminates the need for separate heating systems and allows the working fluid to serve dual purposes: machining operations and thermal processing for magnesium conversion.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the temperature parameter of the working fluid to achieve magnesium conversion. By elevating the temperature to 60-100°C, magnesium reacts to form magnesium hydroxide, which precipitates and can be removed. This parameter change is achieved using the existing working fluid system, minimizing additional energy infrastructure requirements while effectively preventing magnesium oxidation and filter ignition.

Inventive Principle:
Principle #35Parameter changes

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 effectively prevents magnesium swarf oxidation and filter ignition, ensuring safe operation and maintaining machining accuracy while avoiding corrosion and conductivity problems associated with acidic or alkaline solutions.

Implementation Method 1

heats the working fluid contained in the filter

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

cause reaction between the machined swarf adhered to the filter and the heated working fluid. This machined swarf which has reacted with the heated working fluid becomes unlikely to oxidize

Methodology Applied
Scientific EffectChemical reaction (magnesium to magnesium hydroxide conversion): Chemical Bonding

Data Source

PatentEP3281734B1Wire electrical discharge machine
Publication Date: 2023.04.19 FANUC LTD
  • EP3281734B1 patent drawingFigure 1
  • EP3281734B1 patent drawingFigure 2
  • EP3281734B1 patent drawingFigure 3

AI summary

A wire electrical discharge machine (10) includes a filter (52) for removing machined swarf produced by electrical discharge machining from a working fluid, and a heating device (66) for heating the working fluid stored inside the filter (52).