[畢業(yè)設(shè)計(jì)精品]全球電火花活動(dòng)的有關(guān)研究 英語(yǔ)翻譯(電火花)

1、英語(yǔ)篇全球電火花活動(dòng)的有關(guān)研究曾經(jīng)電火花加工被認(rèn)為是非傳統(tǒng)加工過(guò)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(jìn)加工技術(shù)之一。現(xiàn)代電火花加工設(shè)備運(yùn)用先進(jìn)的計(jì)算機(jī)數(shù)字控制，可達(dá)六軸同時(shí)工作和不同的電源技術(shù)。這些能夠作為一面鏡子高精度完成加工。來(lái)自世界頂尖研究所和研究中心主要的電火花建設(shè)者和研究者雇傭的許多專業(yè)工程師通過(guò)共同努力實(shí)現(xiàn)了電火花技術(shù)的巨大先進(jìn)性。這篇報(bào)道為學(xué)者、研究所的發(fā)展、專職社會(huì)和世界范圍內(nèi)對(duì)電火花的先進(jìn)性不斷做出貢獻(xiàn)的其它組織提供了研究綱要。技術(shù)的改革根據(jù)聯(lián)邦實(shí)

2、驗(yàn)協(xié)會(huì)調(diào)查，從政府、私人研究中心到工廠有許多帶來(lái)技術(shù)轉(zhuǎn)變的渠道。以下就是不同加工技術(shù)應(yīng)用的抽樣調(diào)查：1.工業(yè)和實(shí)驗(yàn)室之間合作性研究項(xiàng)目。2.車間、研究會(huì)和簡(jiǎn)報(bào)。3.獨(dú)家的/非獨(dú)家的許可。4.工廠為工作設(shè)備設(shè)立實(shí)驗(yàn)室進(jìn)行贊助性研究。5.咨詢實(shí)驗(yàn)室人員。6.實(shí)驗(yàn)室和工廠貿(mào)易為了相互的利益，職員交換任務(wù)。7.在一家具體的公司里，實(shí)驗(yàn)室設(shè)備使用能力不可獲知。8.實(shí)驗(yàn)室參觀、分享信息并討論技術(shù)上的問題。9.出版社和其他的印刷文獻(xiàn)。10.工業(yè)成員與那些和實(shí)驗(yàn)室相關(guān)的組織聯(lián)合在一起。如項(xiàng)目 9 和 10 所定義的,電火花技術(shù)轉(zhuǎn)變(edmtt)的目的之一是從有關(guān)電火花項(xiàng)目的研究中心提供技術(shù)或信息源，而且使這些

3、可得信息有利于電火花過(guò)程的任何一個(gè)環(huán)節(jié)。由電火花轉(zhuǎn)變技術(shù)出版的一個(gè)參考信息是電火花技術(shù)專欄系列，它包括由大學(xué)、電火花制造業(yè)者和其它世界各地技術(shù)研究中心提供的電火花技術(shù)報(bào)道。不久以前的目標(biāo)·電火花運(yùn)行時(shí)，電極的低溫處理的效果這個(gè)計(jì)劃嘗試研究電火花運(yùn)行時(shí)，工具電極的低溫處理效果。在俄亥俄州的公司，工件材料和電極的低溫處理是由prm碳化物完成的。在低溫處理時(shí)候，材料在77k溫度24小時(shí)冷卻到周圍環(huán)境的溫度。已經(jīng)完成了正確對(duì)待已處理的金屬線和未處理的金屬線的wedm實(shí)驗(yàn)。實(shí)驗(yàn)時(shí)發(fā)現(xiàn)，低溫處理金屬線，使金屬線破壞的危險(xiǎn)性減小了30%。關(guān)于電火花沉淀和wedm的實(shí)驗(yàn)性工作一直在繼續(xù)。·

4、復(fù)晶體金剛石的電火花線切割(pcd)已經(jīng)實(shí)行的一項(xiàng)實(shí)驗(yàn)性研究決定了wed加工過(guò)程在運(yùn)行時(shí)參數(shù)設(shè)置的效果。wedm 運(yùn)轉(zhuǎn)在切削材料的不同層面時(shí)，在工作件中，像 pcd和wc這樣的材料,是由實(shí)驗(yàn)和理論共同決定的。熱應(yīng)力的數(shù)學(xué)模型一直在繼續(xù)，它理論上解釋了基于stefan數(shù)學(xué)問題的金剛石晶粒機(jī)械切削。·鈹銅合金的wedm這個(gè)計(jì)劃的主要目的是發(fā)展一個(gè)在 wedm 的時(shí)候，為不同硬度的鈹銅合金選擇最佳加工參數(shù)設(shè)置的而設(shè)立的數(shù)據(jù)庫(kù)。這個(gè)計(jì)劃由charmilles robofil 100機(jī)器引導(dǎo)。機(jī)器設(shè)定和切削特點(diǎn)之間的關(guān)系如同加工速度、表面粗糙度、切削余量一樣，都是由實(shí)驗(yàn)決定的。機(jī)器參數(shù)設(shè)定需要

5、知道周期、當(dāng)前狀態(tài)、脈動(dòng)持續(xù)時(shí)間、功率、金屬線速度、金屬線拉力和金屬材料。最佳化參數(shù)設(shè)定有兩個(gè)目的,也就是取機(jī)制速度最大值和取表面光滑最大值。對(duì)于兩者標(biāo)準(zhǔn)的輸入?yún)?shù)數(shù)據(jù)庫(kù)正在發(fā)展。·使用分開電極放電方法排泄分布電火花沉淀的研究這個(gè)計(jì)劃的主要目的是研究加工參數(shù)（峰值電流和瞬時(shí)脈動(dòng)）和火花特征的閃爍方法的影響，如加工間隙之間的閃爍效率和幾何分布。峰值電流和瞬時(shí)脈動(dòng)使加工間隙的環(huán)境改變導(dǎo)致閃爍效率和幾何分布。一種火花探視系統(tǒng)的新方法用于獲得火花數(shù)據(jù)。完整的工具被分為許多小部分去識(shí)別不同間隙不同領(lǐng)域的每一個(gè)電火花?；鸹ㄌ揭暱萍挤椒ㄔ诓煌募庸きh(huán)境下，還能夠有效地用于發(fā)現(xiàn)加工的效率。·

6、;電火花沉淀模的自適應(yīng)控制系統(tǒng)電火花沉淀過(guò)程的電弧損害減少了加工效率、降低了加工表面質(zhì)量和提高了加工成本。這個(gè)項(xiàng)目的主要目的是為電火花提高加工過(guò)程的穩(wěn)定性、避免電弧損害和增加加工效率，開發(fā)自適應(yīng)的控制系統(tǒng)。在這個(gè)項(xiàng)目中，已經(jīng)發(fā)明了數(shù)字化電火花間隙監(jiān)測(cè)，用于精確地探測(cè)間隙所隔時(shí)間效率，包括間隙開始、常態(tài)火花、短暫的電弧、穩(wěn)態(tài)電弧和短路。圖1所示為監(jiān)視器的線路線圖。這個(gè)系統(tǒng)的獨(dú)有特征是高頻率(hf)的監(jiān)測(cè)技術(shù)，它不僅監(jiān)測(cè)當(dāng)前的電弧損害，而且也監(jiān)測(cè)瞬時(shí)電弧視為電弧損害的預(yù)測(cè)信號(hào)。hf探測(cè)是所有edm電弧損害探測(cè)技術(shù)中最容易實(shí)現(xiàn)的方法。一個(gè)自適應(yīng)的控制系統(tǒng)和電火花自動(dòng)調(diào)節(jié)管理的參考模型已經(jīng)建立了。這些

7、自適應(yīng)的控制系統(tǒng)經(jīng)過(guò)電火花間隙監(jiān)視器和時(shí)實(shí)控制伺服來(lái)監(jiān)測(cè)間隙參數(shù)。擁有這些系統(tǒng)，在條件差的電火花加工環(huán)境下，生產(chǎn)率都能得到50%的提高。一個(gè)使用了pi自動(dòng)調(diào)節(jié)方法的電火花自動(dòng)調(diào)節(jié)監(jiān)視器已經(jīng)發(fā)展成為三菱 k35 ed 機(jī)器。這個(gè)系統(tǒng)能夠根據(jù)電火花探測(cè)間隙參數(shù)自動(dòng)地調(diào)節(jié)主軸周期縮進(jìn)的周期時(shí)間。電弧損害能夠完全地避免，而且與人工設(shè)置跳躍周期相比，生產(chǎn)率提高50%。·先進(jìn)電火花線切割控制系統(tǒng)在 wedm 加工過(guò)程中，金屬線破壞減少加工效率。這個(gè)問題由沿著金屬線的密度高功率所引起的，這被視為電火花頻率和工件高度決定的電火花分布長(zhǎng)度的比例。在大多數(shù)wedm設(shè)備里，電火花頻率不能時(shí)實(shí)監(jiān)視、控制和最

8、佳脈沖時(shí)間，從而不能根據(jù)制造者提供的數(shù)據(jù)庫(kù)，決定給定高度工件的電火花頻率。這個(gè)計(jì)劃的主要目的是發(fā)展一個(gè)先進(jìn)的wedm監(jiān)測(cè)和控制系統(tǒng)，它能夠時(shí)實(shí)監(jiān)測(cè)工件高度的變化和把電火花頻率控制在一個(gè)最佳水平。最新發(fā)明的控制系統(tǒng)包括數(shù)字式電火花頻率監(jiān)視器和擁有電源和伺服系統(tǒng)控制的pc主控制器。pc時(shí)實(shí)監(jiān)控電壓、電火花頻率和根據(jù)工件高度工作臺(tái)自動(dòng)進(jìn)給。這個(gè)系統(tǒng)將工作臺(tái)進(jìn)給控制在最佳速率，并且根據(jù)工件高度時(shí)實(shí)調(diào)整脈沖將電火花頻率控制在最佳水平。電火花頻率總是根據(jù)安全性和高效率來(lái)進(jìn)行調(diào)整，而且能夠根據(jù)高度變化而變化，從而避免了金屬線損害，維持了最佳切削速度。如圖2所示為切削工件時(shí)，在這個(gè)系統(tǒng)的控制下，根據(jù)高度變化而

9、時(shí)實(shí)記錄的數(shù)據(jù)。高度識(shí)別誤差為1mm，隨高度變化的識(shí)別反應(yīng)誤差為1秒。擁有這個(gè)控制系統(tǒng)使數(shù)控編程的生產(chǎn)者和機(jī)器操作員的工作簡(jiǎn)化，在切削多種高度的工件時(shí)，機(jī)器操作員不需要將工件高度數(shù)據(jù)輸入到機(jī)器中，而且也不必將電源設(shè)置命令輸入數(shù)控程序中。附屬于先進(jìn)材料的電火花磨削的內(nèi)布拉斯加-林肯的大學(xué)的未來(lái)計(jì)劃先進(jìn)材料的機(jī)械磨削，包括可導(dǎo)電的陶器、燒結(jié)碳化物和多晶體金剛石（pcd），由于它們的高硬度和高韌性 ，機(jī)械效率非常低。電火花加工提供了一個(gè)有效的加工先進(jìn)材料的方法。然而，由于電火花加工而造成的表面重鑄層和微裂痕，表面質(zhì)量非常低。這個(gè)計(jì)劃的目的是發(fā)展電火花磨削加工（edg），配有機(jī)械研磨作用的設(shè)備提高放電

10、環(huán)境和切除加工先進(jìn)材料時(shí)的損毀層。如圖3所示的加工過(guò)程。這個(gè)加工方法是使用焊有金剛石的金屬磨輪作為電極。在加工時(shí)，磨輪電極高速旋轉(zhuǎn)，電火花在工件與電極之間間隙釋放，加工間隙由電火花伺服系統(tǒng)控制。初步的實(shí)驗(yàn)研究表明研磨作用不僅能夠提高電火花的表面質(zhì)量，而且能夠通過(guò)有效地切除腐蝕層和微粒子和提供高速的常態(tài)放電比例與更好的加工穩(wěn)定性來(lái)提高放電間隙的條件。·先進(jìn)的時(shí)實(shí)電火花沉淀的監(jiān)測(cè)和控制系統(tǒng)因?yàn)槭姌O具有比較高的機(jī)械效率和容易制造，所以它在美國(guó)的電火花沉淀操作中應(yīng)用比較廣泛。在有石墨電極的電火花中，電弧損害經(jīng)常發(fā)生，而且很難避免。這個(gè)計(jì)劃的主要目的是電火花沉淀在使用石墨電極時(shí)，發(fā)展一個(gè)先

11、進(jìn)的監(jiān)測(cè)和控制系統(tǒng)。在這個(gè)計(jì)劃中,可獲得先進(jìn)的和商業(yè)化的數(shù)字式電火花監(jiān)視器，它將被發(fā)展成為監(jiān)測(cè)間隙狀態(tài)間的時(shí)間比。神經(jīng)網(wǎng)絡(luò)技術(shù)將會(huì)用來(lái)分析由電火花監(jiān)測(cè)系統(tǒng)得來(lái)的間隙電壓、當(dāng)前信號(hào)和間隙狀態(tài)的數(shù)據(jù)。神經(jīng)網(wǎng)絡(luò)和模糊邏輯的識(shí)別系統(tǒng)在石墨電極的電火花加工過(guò)程中，將會(huì)發(fā)展成能夠預(yù)測(cè)電弧損害的系統(tǒng)。先進(jìn)的控制系統(tǒng)將會(huì)發(fā)展為時(shí)實(shí)控制放電電源、電極工具的自動(dòng)轉(zhuǎn)換和伺服系統(tǒng)。·先進(jìn)材料的電火花電源當(dāng)使用電火花加工耐高溫材料時(shí)，包括鎢碳化物、導(dǎo)電陶器、pcd和pcb等材料，放電波形很大程度地影響加工運(yùn)轉(zhuǎn)過(guò)程。大多數(shù)通過(guò)商業(yè)可獲得的電火花電源僅僅提供方形放電電流脈沖。但是，使用方形放電脈沖，高溫能量不能夠

12、高度集中，因此，許多先進(jìn)材料包括鎢碳化物和導(dǎo)電陶器的材料切除率非常低。這個(gè)計(jì)劃被建議發(fā)展成為一個(gè)電火花脈沖觸發(fā)器，提供特殊的放電波形以適合先進(jìn)材料的加工。所建議的脈沖電源標(biāo)準(zhǔn)將會(huì)發(fā)展成為比商業(yè)上的電火花電源擁有更廣的峰值電流和電壓變化范圍，提供 rc脈沖控制的晶體管和多水平波形。計(jì)算機(jī)能夠?qū)Ψ烹姴ㄐ尉幊毯瓦x擇不同的脈沖參數(shù)。不同材料和加工設(shè)備有最佳的波形，將通過(guò)熱模型的理論研究和對(duì)先進(jìn)材料電火花過(guò)程的分析決定波形。·加州/戴維斯大學(xué)一些電火花研究領(lǐng)域中,包括(但是不僅僅是)先進(jìn)的電火花控制系統(tǒng)，目的在于增加生產(chǎn)，減少操作注意事項(xiàng)和wedm上的金屬線破壞的研究。·德克薩斯a&

13、amp;m大學(xué)電火花的難點(diǎn)在于對(duì)加工材料的研究，如鎢碳化物/鈷合成、鈦合金和其它陶器合成材料。 ·田納西州科技大學(xué)電火花加工的陶瓷材料。日本·工業(yè)科學(xué)研究所,東京大學(xué)在教授t. masuzawa的指導(dǎo)下，這個(gè)研究所被譽(yù)為日本領(lǐng)導(dǎo)級(jí)電火花研究所。它們的研究涵蓋了所有的電火花領(lǐng)域，包括：高的表面質(zhì)量、微加工的金屬線電極放電磨削（wedg）、摩爾電火花、電火花閃爍的研究、微孔電火花和其它范圍的電火花研究。工業(yè)科學(xué)研究所、日本科技研究所和toyama大學(xué)聯(lián)合在一起研究和發(fā)展直接的或粘有金剛石的金屬磨的電火花加工。這種方法生產(chǎn)與普通的磨輪方法相比，有較高效率的磨削和較低的磨削力。最近

14、工業(yè)科學(xué)研究所出版的研究有一篇報(bào)導(dǎo)，是關(guān)于微孔電火花電極使用壓電平移裝置的發(fā)展。他們也發(fā)展了3軸數(shù)控微電火花，它能夠生產(chǎn)出表面精度高達(dá)0.1毫秒。另外的最近報(bào)告報(bào)道了在加工不同種類型的碳鋼時(shí)，銅電極金屬線的比例研究。據(jù)了解電極金屬線比例很大程度上不僅受結(jié)構(gòu)的影響，而且也受包圍電極的碳層質(zhì)量的影響。如果有電極表面產(chǎn)生足夠厚度的碳層，較低金屬線比例就能很容易實(shí)現(xiàn)。 ·科技大學(xué)nagaoka最近一些研究工作(也和豐田技術(shù)學(xué)院連同日立生產(chǎn)公司一起研究)有一項(xiàng)關(guān)于絕緣體陶瓷的電火花模型的有趣報(bào)道。除了有限的電火花方法外，通常只有具有導(dǎo)電性能的陶瓷材料才能用電火花加工。因此，研究者正在研究最近已

15、經(jīng)發(fā)明的使用標(biāo)準(zhǔn)電火花加工的深孔加工和絕緣陶瓷的切削加工方法。·日本技術(shù)研究所加工中心調(diào)查電火花沉淀運(yùn)行的可能性以減少制造壓鑄模所需的加工時(shí)間。·大阪縣工業(yè)科技研究所  最近大部分工作包括表面整體性研究，它幫助電火花表面實(shí)現(xiàn)高性能、抗腐蝕和抗磨損。早期的工作包括變壓器聯(lián)結(jié)線路的發(fā)展，用來(lái)穩(wěn)住wedm的電解效果。·應(yīng)用力學(xué)的研究所,kyushu 大學(xué)陶瓷材料的加工和陶瓷金屬合金的發(fā)展，使用電火花增加黏結(jié)強(qiáng)度，減少殘留應(yīng)力。·豐田技術(shù)學(xué)院通過(guò)日本電火花制造業(yè)者的聯(lián)合努力，他們過(guò)去的研究在電火花的電介流體中使用硅粉、鋁粉和石墨粉，增強(qiáng)電火花表面光滑度

16、，使其像一面鏡子一樣光潔，這是最早的徹底研究。通過(guò)懸浮粉末釋放電流的分散，他們?cè)缙诘难芯渴辜庸け砻婢冗_(dá)到0.8微米甚至更高，但加工時(shí)間明顯下降?，F(xiàn)在一些電火花制造業(yè)者在電火花沉淀和線切割中提供一個(gè)粉狀混合物電介體系統(tǒng)。最近豐田技術(shù)學(xué)院的大部分工作包括微孔電火花、碳在電火花電極上沉淀的研究、絕緣陶瓷的電火花加工和電極磨損研究。·toyama縣大學(xué)最近出版的研究中含一個(gè)報(bào)告，它是關(guān)于wedm的金屬線彎曲和它如何影響加工精度的研究。金屬線變化是用光學(xué)纖維來(lái)測(cè)量，正在研究一項(xiàng)電火花脈沖對(duì)金屬線的力學(xué)作用的調(diào)查。toyama大學(xué)通過(guò)和三菱電力的聯(lián)合努力,最近完成了另一項(xiàng)計(jì)劃，它嘗試對(duì)電火花線

17、切割溫度分布的測(cè)量。盡管wedm由于加工過(guò)程中的金屬線破壞，最大切削速度受到限制，然而知道金屬線的真實(shí)溫度對(duì)于wedm加工速度的發(fā)展是很重要的。金屬線溫度分布是通過(guò)wedm釋放的電流和電壓測(cè)量的。資訊科技發(fā)現(xiàn)釋放濃度僅僅發(fā)生在金屬線被破壞之前，因此釋放濃度可以作為金屬線破裂的主要原因。結(jié)果也表明平均的金屬線溫度在100左右。·岡山大學(xué)最近的旋轉(zhuǎn)圓板電極研究為mrr提高深槽加工能力。鈦、英高鎳和銅合金材料等的其它研究。·yamagata 大學(xué)有關(guān)氧化物-超導(dǎo)體的陶瓷的電火花研究。歐洲·技術(shù)轉(zhuǎn)變公司(英國(guó)伯明罕)transtec把車輛作為大學(xué)和其它工業(yè)制造業(yè)研究所來(lái)研

18、究、發(fā)展和銷售先進(jìn)技術(shù)?？茖W(xué)和商業(yè)計(jì)劃已經(jīng)在transtec與伯明罕、愛丁堡和諾丁漢之間建立。transtec的研究和發(fā)展集中在下列三個(gè)有名的產(chǎn)品種類和控制技術(shù)領(lǐng)域內(nèi)：1.電火花加工2.電化學(xué)加工3.電火花質(zhì)地產(chǎn)品含:柔性加工單元擁有多軸電火花、電火花質(zhì)地加工、電火花無(wú)線電電波頻率自適應(yīng)控制、電火花數(shù)控自適應(yīng)控制、ram-type電火花和自適應(yīng)控制系統(tǒng)的數(shù)控電火花鉆孔加工。cul最近的大多數(shù)電火花研究工作包括:·電火花的計(jì)算機(jī)輔助加工計(jì)劃和制造研究計(jì)劃的目的是使cad/cam和電火花加工成為一個(gè)整體。整體包括特征模型單元的發(fā)展、capp（計(jì)算機(jī)輔助過(guò)程規(guī)劃）單元的發(fā)展、cam-edm

19、單元（計(jì)算機(jī)輔助制造業(yè)）和數(shù)控傳遞過(guò)程。在這項(xiàng)研究工作中，已經(jīng)定義了新的特點(diǎn)去完全或部分地描述電火花加工工件。·電火花加工熱效應(yīng)的金屬結(jié)構(gòu)學(xué)調(diào)查此研究是為了更好地理解haz的金屬結(jié)構(gòu)和微結(jié)構(gòu)特征，從而提高加工表面質(zhì)量。這個(gè)研究有兩個(gè)主要的應(yīng)用領(lǐng)域：1.暴露在外的工具的沖擊、彎曲和拉力。當(dāng)前的研究嘗試發(fā)展新的電火花電源，并定義最佳加工和觸發(fā)設(shè)置，以便于完全去除電火花加工過(guò)程中的白色層。在 edm 程序的時(shí)候。2.暴露在外的工具的磨料磨損和化學(xué)磨損。當(dāng)前的研究嘗試?yán)冒讓拥膬?yōu)點(diǎn)（硬度、耐化學(xué)腐蝕）當(dāng)作一層保護(hù)膜。這個(gè)研究需要agie 和 charmilles 技術(shù)的合作。·加工

20、刀具和生產(chǎn)工程學(xué)研究所與生產(chǎn)技術(shù)fraunhofer研究所（德國(guó)）·電火花加工的電拋光鑄模和壓鑄模。·水庫(kù)電介質(zhì)鍛造模的研究。·電火花加工后的陶瓷性能。·半導(dǎo)體材料的電火花加工。·超級(jí)先進(jìn)的電火花加工和提高工具生產(chǎn)的涂料科技。·電火花線切割拋光。·linkoping大學(xué)(瑞典)為了監(jiān)視電火花加工過(guò)程中的放電位置，發(fā)明了一個(gè)系統(tǒng)廣泛地分析電火花加工過(guò)程。這個(gè)方法的使用是基于火花釋放的能量轉(zhuǎn)化為工件中的超聲波脈沖這樣一個(gè)猜想。·dundee大學(xué)(dundee,蘇格蘭)早期在高頻率ac源的使用上，和三菱電力公司的共同合作

21、(日本名古屋)實(shí)現(xiàn)wedm的亞微米表面光潔度。·布加勒斯特工藝學(xué)院(羅馬尼亞)為了實(shí)現(xiàn)較高性能的電火花加工，研究通過(guò)冷卻含氟利昂和氮的電極來(lái)改變電極材料的性能。·技術(shù)學(xué)會(huì) (布達(dá)佩斯,匈牙利)電火花加工沉淀的計(jì)算機(jī)輔助規(guī)劃。·中央機(jī)械工程學(xué)會(huì)(保加利亞)  wedm自適應(yīng)控制系統(tǒng)的研究。結(jié)論這些所列舉大學(xué)的研究計(jì)劃只是全世界電火花加工技術(shù)研究結(jié)果的一小部分。美國(guó)正在進(jìn)行的電火花研究工作的數(shù)量被認(rèn)為在其它國(guó)家之后，如果工業(yè)和政府為研究和其它計(jì)劃提供資金加入更多先進(jìn)技術(shù)的積極興趣，那么美國(guó)將會(huì)擴(kuò)張研究數(shù)量。通過(guò)全世界的大學(xué)和研究所的電火花制造業(yè)者和研究者先進(jìn)

22、的研究和發(fā)展集體的共同努力，電火花加工將會(huì)朝更高水平的機(jī)器運(yùn)轉(zhuǎn)和能力方面繼續(xù)發(fā)展。這些一直持續(xù)的計(jì)劃將會(huì)產(chǎn)生更高機(jī)械性能、更高精密度和更高表面光潔度的電火花加工技術(shù)，為全世界加工刀具工業(yè)提供與其它加工方法無(wú)法相比的獨(dú)一無(wú)二的加工。worldwide research and activities in edm although once considered a “nontraditional” machining process, edm has been replacing drilling, milling, grinding and other traditional mac

23、hining 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. todays edm equipment uses advanced computer numerical control (cnc) with up to six-axes simultaneous op

24、eration 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

25、 from some of the worlds 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 advance

26、ments of electrical discharge machining.  projects conducted over past two yearseffect of cryogenic treatment of electrode on edm performancethis project attempts to study the effect of cryogenic treatment of work and tool electrodes on edm process performance. cryogenic treatment of the w

27、ork 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 experim

28、entally 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 settin

29、gs 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 t

30、he removal mechanism of diamond grain based on the numerical solution of stefan problem is continuing.  wedm of beryllium copper alloysthe main objective of this project is to develop a database of optimal machine parameter settings for machining of beryllium copper alloys of different heights

31、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, c

32、harge 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. st

33、udy of discharge distributions in die-sinking edm using divided electrode spark detection methodthe 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 geo

34、metrical 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

35、 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-sinki

36、ng edmthe 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

37、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 tha

38、t 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 e

39、dm 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 con

40、troller 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,

41、 and the productivity is improved by 50% as compared to the manually set jumping cycle time.   advanced wire-edm control systemin 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 s

42、parking 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 s

43、elected 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 consi

44、sts 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 op

45、timal 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 rup

46、ture 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 ope

47、rator 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 adva

48、nced materialsthe 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 advan

49、ced 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 flushi

50、ng 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 e

51、xperimental 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 monito

52、ring and control system for die-sinking edmgraphite 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

53、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

54、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

55、 developed to control on-line the discharge power, auto-jumping of tool electrode, and the servo system.  edm power generator for advanced materialswhen using edm to machine the high thermal resistant materials including tungsten carbide, conductive ceramics, pcd and pcb, the discharge waveform

56、s 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 inc

57、luding 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

58、 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 requirement

59、s will be determined by the theoretical study of thermal modeling and analysis of the edm process for advanced materials.  university of california/davisresearch 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 universityedm studies on difficult to machine materials such as tungsten carbide/cobalt composites, titanium diboride or other ceramic composite materials. tennessee technological universitymachin