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無錫職業(yè)技術學院畢業(yè)設計說明書
外文翻譯
Although?once?considered?a?“nontraditional”?machining?process,?EDM?has?been?replacing?drilling,?milling,?grinding?and?other?traditional?machining?operations?in?many?industries?throughout?the?world.?Since?its?early?days?as?a?“tap?busting”?method?over?50?years?ago,?EDM?has?developed?into?one?of?the?most?advanced?machining?technologies.?Today’s?EDM?equipment?uses?advanced?Computer?Numerical?Control?(CNC)?with?up?to?six-axes?simultaneous?operation?and?state?of-the-art?power?supply?technology,?which?can?produce?a?mirror?surface?finish?and?“split-tenth”?accuracy.
The?tremendous?advancements?in?EDM?technology?have?been?achieved?through?the?collective?efforts?of?many?dedicated?engineers?employed?by?the?major?EDM?builders?and?by?researchers?from?some?of?the?world’s?leading?institutions?and?research?centers.?This?report?provides?an?overview?of?the?research?studies?and?developments?of?these?institutions?and?the?activities?of?professional?societies?and?other?organizations?throughout?the?world?that?are?contributing?to?the?continued?advancements?of?Electrical?Discharge?Machining.
Mechanisms?of?Technology?Transfer
Mechanisms?of?Technology?Transfer?According?to?the?Federal?Laboratories?Consortium,?there?are?several?channels?for?bringing?about?the?transfer?of?technology?from?government?or?private?research?centers?to?industry.?The?following?list?is?a?sample?of?the?various?mechanisms?used
1.?Cooperative?research?projects?between?industry?and?laboratories
2.?Workshops,?seminars,?and?briefings
3.?Exclusive/non-exclusive?licensing
4.?Sponsored?research?where?industry?reimburses?a?lab?for?work?done?at?the?facility.
5.?Consulting?by?lab?personnel.
6.?Employee?exchange?where?researchers?from?the?lab?and?industry?trade?assignments?in?areas?of?mutual?interests.
7.?Use?of?lab?facilities?where?certain?capabilities?are?not?available?at?a?particular?company.
8.?Laboratory?visits?to?share?information?and?discuss?technical?problems.
9.?Publications?and?other?printed?literature.
10.?Membership?in?industrial?affiliate?organizations?that?are?associated?with?research?lab’s.
As?defined?in?items?9?and?10,?one?of?the?objectives?of?EDM?Technology?Transfer?(EDMTT)?has?been?to?provide?a?mechanism?or?source?of?gathering?information?from?research?centers?with?projects?relating?to?EDM,?and?making?this?information?available?to?anyone?interested?in?the?EDM?process.?One?reference?source?published?by?EDMTT?is?the?“EDM?Technology”?volume?series,?which?contain?EDM?technical?reports?by?universities,?EDM?manufacturers,?or?other?technical?research?centers?around?the?world.
International?and?National?EDM?Conferences?and?Discussion?Forums
In?an?effort?to?establish?a?forum?for?the?discussion?of?EDM?research?and?developments,?and?help?provide?a?course?of?instruction?in?basic?and?advanced?EDM?technology,?several?technical?societies?and?other?groups?have?established?international?or?national?conferences?on?EDM.
Japan
??Japan?Society?of?Electrical?Machining?Engineers(JSEME)
Throughout?its?forty?year?history,?the?JSEME?has?been?the?predominant?organization?and?driving?force?behind?the?research?and?development?of?EDM?and?the?dissemination?of?this?information?in?Japan.?All?of?the?major?Japanese?EDM?builders?and?university?EDM?researchers?present?technical?reports?on?the?latest?EDM?research?and?developments?at?their?annual?conferences.?At?the?JSEME?“All?Japan?Conference”?held?in?October?1994,?thirty-five?new?EDM?reports?were?presented,?including?the?latest?research?by?Mitsubishi,?Sodick,?Makino,?Hitachi,?and?the?leading?research?centers?established?at?Japanese?universities.?The?“Journal?of?the?Japan?Society?of?Electrical?Machining?Engineers”?(Japanese?language?only)?is?their?official?publication?which?provides?the?latest?technical?information?on?the?Japanese?EDM?industry.
From?a?recent?announcement?by?Professor?Yasuo?Kimoto,?current?President?of?JSEME,?the?Society?will?coordinate?a?new?“International?Journal?of?Electrical?Machining”?(IJEM).?The?aims?of?the?IJEM?are:?1)?to?propagate?the?latest?scientific?and?technological?news?in?the?field?of?electrical?machining?methods,?2)?to?exchange?experiences?in?putting?electrical?machining?into?practice,?and?3)?inform?about?the?current?state-ofthe-art?and?suggest?directions?of?further?development.?IJEM?editorial?board?members?include?representatives?from?Mitsubishi,?Sodick,?the?leading?Japanese?research?centers,?and?will?also?include?members?from?outside?Japan.
U.S.A.
??Society?of?Manufacturing?Engineers?(SME)
SME?sponsors?an?annual?EDM?clinic?and?a?fundamentals?course.
??American?Society?of?Mechanical?Engineers?(ASME)
Starting?in?1985,?the?Production?Engineering?Division?of?ASME?began?a?session?on?nontraditional?machining?during?their?Winter?Annual?Meeting?with?EDM?as?the?major?topic?of?discussion.
??Modern?Machine?Shop/Gardner?Management
Beginning?in?1989,?Modern?Machine?Shop?Magazine?and?Gardner?Management?Services?has?sponsored?the?largest?EDM?conference?and?exhibition?in?the?United?States.?EDMTT?has?attended?all?of?these?conferences.
??National?Institute?of?Standards?&?Technology?(NIST)
Organized?under?the?U.S.?Department?of?Commerce?Technology?Administration,?NIST?has?held?conferences?on?the?“Machining?of?Advanced?Materials”?and?presents?technical?information?on?using?EDM.
International
Beginning?in?the?sixties,?the?“International?Institution?for?Production?Engineering?Research”?has?coordinated?an?international?delegation?of?the?world’s?major?EDM?manufacturer’s?and?researchers?for?the?“International?Symposium?for?Electro-Machining”?(ISEM).?The?International?Institution?for?Production?Engineering?Research?is?also?known?officially?as?CIRP,?which?stands?for?“College?International?pour?I’Etude?Scientifique?des?Techniques?de?Production?Mechanique”.?ISEM?has?been?a?forum?of?exchange?for?technical?informationon?EDM,?Laser,?ECM?and?other?high-technology?machining?processes.?ISEMXI?will?be?eld?in?Switzerland?and?cover?topics?on?EDM?Process?and?Physics,?EDM?Machinery,?EDM?Technology,?EDM?Control?and?EDM?Applications.
?EDM?Research?and?Development?Centers
Although?EDM?represents?only?a?small?portion?of?the?total?machine?tool?industry?worldwide,?the?number?of?laboratories?throughout?the?world?performing?EDM?research?and?development?studies?has?been?growing?steadily?for?several?years.?The?more?in-depth?and?well?organized?EDM?research?programs?at?various?technical?centers?are?funded?by?the?major?EDM?builders?or?through?government?research?grants.?Several?EDM?manufacturers?have?also?donated?machines?and?supplies?to?universities?with?limited?funds,?which?has?helped?to?provide?a?program?for?future?engineers?to?obtain?a?hands-on?understanding?of?the?capabilities?of?the?EDM?process.
The?following?institutions?have?established?research?and?development?programs?on?EDM.?They?represent?only?a?partial?list?of?the?laboratories?and?research?projects?throughout?the?world?that?contribute?to?the?advancements?in?EDM?technology.?In?addition?to?the?work?at?advanced?research?laboratories?setup?by?the?major?EDM?manufacturers,?the?work?performed?at?these?institutions?should?have?a?direct?impact?on?future?developments?in?the?EDM?industry.
U.S.A.
Nontraditional?Manufacturing?Research?Center,?University?of?Nebraska-Lincoln
Under?the?direction?of?Professor?K.?P.?Rajurkar,?this?institution?has?established?one?of?the?world’s?leading?centers?for?academic?studies?and?experimental?research?in?EDM?and?other?high?technology?machining?processes.?Courses?taught?in?advanced?manufacturing?processes?cover?a?broad?range?of?topics?and?provide?the?student?with?an?in?depth?study?of?EDM?technology.?Besides?EDM,?about?30?other?advanced?manufacturing?processes?are?covered.?The?following?graduate?level?course?description?provides?a?summary?of?these?studies:
?Course?Title:?Advanced?Manufacturing?Processes?(IE?970)?Description:?
Advanced?manufacturing?processes?provide?an?alternative?(or?sometimes?the?only?alternative)?for?manufacturing?complex?shapes?in?a?wide?variety?of?materials.?This?course?deals?with?topics?ranging?from?the?principles?of?operation,?to?the?integration?of?these?advanced?processes?into?future?flexible?manufacturing?systems.?About?thirty-one?nontraditional?manufacturing?processes?including?Electrical?Discharge?Machining?(EDM),
Electro-Chemical?Machining?(ECM),?Laser?Beam?Machining?(LBM),?Abrasive?Jet?Machining?(AJM),?Electrochemical?Arc?Machining?(ECAM),?Electron?Beam?Welding,?etc.?are?covered?in?this?course.?In?the?context?of?these?advanced?manufacturing?processes,?the?following?topics?are?covered.
1.?Process?Mechanism,?Modeling?and?Simulation
2.?Surface?Integrity
3.?Tool?Design,?CAD
4.?Design?of?Related?Machine?Tools
5.?Adaptive?Control
6.?Expert?Systems,?Neural?Networks,?Fuzzy?Logic?Applications
7.?Integration?within?CIM?Environment
8.?Applications
9.?Environmental?and?Safety?Issues
In?addition?to?the?class?lectures,?experimental?projects?on?Die-Sinking?EDM?and?Wire?EDM?are?also?required.
The?following?list?of?projects?provide?an?overview?of?past?and?future?EDM?research?work?conducted?at?the?University?of?Nebraska’s?Nontraditional?Manufacturing?Research?Center.
?Projects?Conducted?Over?Past?Two?Years
Effect?of?cryogenic?treatment?of?electrode?on?EDM?performance
This?project?attempts?to?study?the?effect?of?cryogenic?treatment?of?work?and?tool?electrodes?on?EDM?process?performance.?Cryogenic?treatment?of?the?work?piece?material?and?electrodes?(for?EDM?and?WEDM)?was?done?by?RPM?Carbide,?Inc.?of?Ohio.?During?cryogenic?treatment,?the?material?is?cooled?at?77?K?for?24?hours?and?brought?back?to?ambient?temperature.?Experiments?on?WEDM?have?been?carried?out?using?treated?wire?and?untreated?wire.?It?was?experimentally?found?that?the?risk?of?wire?rupture?was?reduced?by?30%?when?using?cryogenically?treated?wire.?Experimental?work?on?Die-sinking?EDM?and?WEDM?is?continuing.
??Wire?EDMing?of?Polycrystalline?Diamond?(PCD)
An?experimental?study?has?been?carried?out?to?determine?the?effects?of?parameter?settings?in?a?state?of?the?art?WED?machine?on?the?machining?performance.?The?WEDM?performance?in?cutting?different?layers?of?materials,?such?as?PCD?and?WC,?in?the?workpiece?have?been?experimentally?and?theoretically?determined.?The?mathematical?model(s)?of?thermal?stress?for?a?theoretical?explanation?of?the?removal?mechanism?of?diamond?grain?based?on?the?numerical?solution?of?Stefan?problem?is?continuing.
??WEDM?of?Beryllium?Copper?Alloys
The?main?objective?of?this?project?is?to?develop?a?database?of?optimal?machine?parameter?settings?for?machining?of?Beryllium?copper?alloys?of?different?heights?during?WEDM.?This?project?is?conducted?with?a?Charmilles?Robofil?100?WED?machine.?The?relationships?between?the?machine?settings?and?machining?characteristics?such?as?machining?speed,?surface?roughness,?and?overcut?are?determined?experimentally.?The?machine?setting?parameters?are?charge?frequency,?charge?current,?pulse?duration,?capacitance,?wire?speed,?wire?tension?and?wire?material.?The?optimization?of?parameter?settings?consists?of?two?objectives,?i.e.?to?maximize?the?machining?speed?and?to?maximize?surface?finish.?A?database?of?input?parameters?for?both?criteria?is?being?developed.
Study?of?discharge?distributions?in?die-sinking?EDM?using?divided?electrode?spark?detection?method
The?principal?objective?of?this?project?is?to?study?the?influence?of?machining?parameters?(peak?current?and?pulse?on-time)?and?flushing?methods?on?spark?characteristics?such?as?sparking?efficiency?and?geometrical?distribution?of?sparks?in?the?machining?gap.?Peak?current?and?pulse?on-time?change?the?machining?conditions?in?the?gap?leading?to?changes?in?the?sparking?efficiency?and?spark?distribution.?A?new?method?of?spark?detection?system?is?employed?to?obtain?the?spark?data.?The?solid?tool?is?divided?into?number?of?smaller?sections?to?identify?each?spark?in?different?areas?in?the?gap?at?different?instants.?This?spark?detection?methodology?can?also?be?effectively?used?to?find?the?efficiency?of?machining?when?subjected?to?different?machining?conditions.
Adaptive?control?systems?for?die-sinking?EDM
The?arc?damage?in?the?die-sinking?EDM?process?reduces?the?machining?productivity,?decreases?the?machined?surface?quality,?and?increases?the?machining?cost.?The?main?objective?of?this?project?is?to?develop?adaptive?control?systems?for?EDM?to?improve?the?process?stability,?avoid?arc?damage,?and?increase?the?machining?rate.?In?this?project,?a?digital?EDM?gap?monitor?was?developed?to?precisely?detect?the?time?ratios?of?gap?states?including?gap?open,?normal?spark,?transient?arc,?stable?arc?and?short?circuit.?The?unique?feature?of?this?system?is?the?high?frequency?(HF)?detecting?technology?that?detects?not?only?the?occurrence?of?arc?damage,?but?also?the?transient?arc?regarded?as?the?forecasting?signal?of?arc?damage.?The?HF?detection?is?the?most?reliable?method?in?all?EDM?arc?damage?detecting?technologies.?A?model?reference?adaptive?control?system?and?a?self-tuning?regulating?system?for?EDM?have?been?developed.?These?adaptive?control?systems?detect?gap?state?parameters?through?the?EDM?gap?monitor?and?control?the?servo?feed?in?real-time.?The?productivity?with?these?control?systems?has?been?shown?to?be?improved?by?50%?when?machining?under?poor?flush?conditions.?An?EDM?auto?jumping?controller?using?the?PI?self-tuning?approach?has?also?been?developed?on?a?state-of-the-art?Mitsubishi?K35?ED?machine.?This?system?adaptively?adjusts?the?cycle?time?of?the?periodical?retraction?of?the?main?spindle?according?to?the?detected?EDM?gap?parameters.?The?arcing?damage?can?be?completely?avoided,?and?the?productivity?is?improved?by?50%?as?compared?to?the?manually?set?jumping?cycle?time.
Advanced?Wire-EDM?control?system
In?the?WEDM?process,?wire?rupture?reduces?the?machining?rate.?This?problem?is?caused?by?high?power?density?along?the?wire,?which?is?regarded?as?the?ratio?of?sparking?frequency?to?spark?distribution?length?determined?by?the?workpiece?height.?With?most?of?the?state-of-the-art?WEDM?equipment,?the?sparking?frequency?can?not?be?on-line?monitored?and?controlled,?and?an?optimal?pulse?off-time?to?determine?the?sparking?frequency?for?a?given?workpiece?height?is?selected?in?accordance?with?manufacturer?supplied?database.?The?main?objective?of?this?project?is?to?develop?an?advanced?WEDM?monitoring?and?control?system?that?monitors?on-line?the?change?of?workpiece?height?and?control?the?spark?frequency?at?optimal?levels.?A?recently?developed?control?system?consists?of?a?digital?spark?frequency?monitor?and?a?PC?used?as?the?main?controller?with?an?interface?for?power?generator?and?servo?system?control.?The?PC?monitors?on-line?the?gap?voltage,?spark?frequency,?and?the?table?feed?rate?to?identify?the?workpiece?height.?This?system?regulates?the?table?feed?at?optimal?rates?and?adjusts?the?pulse?off-time?in?real-time?to?control?the?spark?frequency?at?optimal?levels?determined?by?the?identified?workpiece?height.?The?spark?frequency?is?always?adjusted?at?a?safe?and?highly?productive?level,?and?is?able?to?follow?the?change?in?workpiece?height?to?avoid?wire?rupture?and?to?maintain?an?optimal?cutting?speed.?The?error?of?the?workpiece?height?identification?is?1?mm?and?the?response?of?the?identification?to?changes?in?workpiece?height?is?1?second.?With?this?control?system,?procedures?of?NC?programming?and?machine?operations?are?simplified,?and?the?machine?operator?does?not?need?to?input?the?workpiece?height?data?into?the?machine?and?insert?the?power?generator?setting?commands?into?the?CNC?program?when?cutting?a?multiple?height?workpiece.
?Future?Projects?at?the?University?of?Nebraska
??Abrasive?assisted?Electrical?Discharge?Grinding?for?machining?advanced?materials
The?machining?rate?with?mechanical?grinding?of?advanced?materials,?including?electrically?conductive?ceramics,?sintered?carbides,?and?polycrystalline?diamonds?(PCD),?is?very?low?due?to?their?high?hardness?and?toughness.?The?EDM?process?provides?an?effective?alternative?to?machine?advanced?materials.?However,?the?surface?quality?generated?by?EDM?is?poor?due?to?the?recast?layer?and?micro-cracks?on?the?machined?surface.?The?objective?of?this?project?is?to?develop?an?Electrical?Discharge?Grinding?(EDG)?process?with?an?assistance?of?mechanical?abrasive?effects?for?improving?the?flushing?condition?and?removing?the?damaged?layer?when?machining?advanced?materials.?During?machining,?the?grinding?electrode?rotates?in?high?speed,?the?spark?discharges?take?place?in?the?gap?between?the?electrode?and?workpiece,?and?the?machining?gap?is?controlled?by?an?EDM?servo?system.?The?preliminary?experimental?study?indicates?that?the?abrasive?effect?not?only?improves?the?surface?quality?of?EDG,?but?also?improve?the?gap?flushing?condition?by?effectively?removing?the?eroded?chips?and?particles,?and?providing?higher?normal?spark?ratio?and?better?machining?stability.
???Advanced?on-line?monitoring?and?control?system?for?die-sinking?EDM
Graphite?electrodes?are?popular?for?die-sinking?EDM?operations?in?U.S.?industries?because?of?higher?machining?rates?and?easy?of?fabrication.?During?EDM?with?graphite?electrodes,?the?arc?damage?occurs?frequently?and?is?difficult?to?avoid.?The?main?objective?of?this?project?is?to?develop?an?advanced?monitoring?and?control?system?for?die-sinking?EDM?when?using?graphite?electrodes.?In?this?project,?an?advanced?and?commercial?available?digital?EDM?monitor?will?be?developed?to?detect?the?time?ratios?of?gap?states.?The?neural?network?technology?will?be?used?to?analyze?the?gap?voltage?and?current?signals?and?the?data?of?gap?states?collected?from?the?EDM?monitoring?system.?A?neural?network?and?fuzzy?logical?identification?system?will?be?developed?to?predict?the?arc?damage?during?the?EDM?process?with?graphite?electrodes.?An?advanced?control?system?will?be?developed?to?control?on-line?the?discharge?power,?auto-jumping?of?tool?electrode,?and?the?servo?system.
???EDM?power?generator?for?advanced?materials
When?using?EDM?to?machine?the?high?thermal?resistant?materials?including?tungsten?carbide,?conductive?ceramics,?PCD?and?PCB,?the?discharge?waveforms?strongly?influence?the?process?performance.?Most?commercially?available?EDM?power?generators?provide?only?square?discharge?current?pulses.?However,?with?square?discharge?pulses,?the?thermal?energy?can?not?be?highly?concentrated,?therefore,?the?material?removal?rates?for?many?advanced?materials?including?tungsten?carbide?and?conductive?ceramics?are?very?low.?This?project?is?proposed?to?developed?an?EDM?pulse?generator?to?provide?particular?discharge?waveforms?suitable?to?machine?advanced?materials.?The?prototype?of?the?proposed?pulse?power?generator?will?be?developed?to?provide?the?transistor?controlled?RC?pulse,?multi-level?waveforms?with?wider?peak?current?and?voltage?ranges?than?current?commercially?available?EDM?power?generators.?A?computer?can?program?the?discharge?waveform?and?select?different?pulse?parameters.?The?optimal?waveforms?for?different?material?and?machining?requirements?will?be?determined?by?the?theoretical?study?of?thermal?modeling?and?analysis?of?the?EDM?process?for?advanced?materials.
?University?of?California/Davis
Research?in?several?EDM?fields,?including?(but?not?limited?to)?advanced?EDM?control?systems?aimed?at?increasing?production?and?reducing?operator?attention?and?studies?in?wire?breakage?on?WEDM.
Texas?A&M?University
EDM?studies?on?difficult?to?machine?materials?such?as?tungsten?carbide/cobalt?composites,?titanium?diboride?or?other?ceramic?composite?materials.
中文原文
一種新技術電火花的加工，盡管電火花加工曾經(jīng)被認為是非傳統(tǒng)加工過程，但是電火花在世界范圍內(nèi)許多工業(yè)方面已經(jīng)取代了鉆孔、銑削、磨削和其它傳統(tǒng)加工方法。盡管50年以前的早期它是“tapbusting”的方式，但是電火花已經(jīng)發(fā)展成為最先進加工技術之一。現(xiàn)代電火花加工設備運用先進的計算機數(shù)字控制，可達六軸同時工作和不同的電源技術。這些能夠作為一面鏡子高精度完成加工。
來自世界頂尖研究所和研究中心主要的電火花建設者和研究者雇傭的許多專業(yè)工程師通過共同努力實現(xiàn)了電火花技術的巨大先進性。這篇報道為學者、研究所的發(fā)展、專職社會和世界范圍內(nèi)對電火花的先進性不斷做出貢獻的其它組織提供了研究綱要。
加工技術的轉變
根據(jù)聯(lián)邦實驗協(xié)會調(diào)查，從政府、私人研究中心到工廠有許多帶來技術轉變的渠道。以下就是不同加工技術應用的抽樣調(diào)查：
1.工業(yè)和實驗室之間合作性研究項目。
2.車間、研究會和簡報。
3.獨家的/非獨家的許可。
4.工廠為工作設備設立實驗室進行贊助性研究。