一、火花機的主要組成部件
火花機也稱為電火花加工(gong)機床(chuang)或EDM機床(chuang),主要(yao)組成(cheng)部(bu)件(jian)包(bao)括以下幾個部(bu)分:
1、機床主體
機床主(zhu)體(ti)是火花(hua)機的(de)基礎結構,它承(cheng)載著所有的(de)工作(zuo)部件和(he)控制系統。主(zhu)體(ti)通(tong)常由鑄鐵或鋼材制成,以確(que)保穩定性和(he)剛性。
2、主軸和電極夾持裝置
主軸是安裝和移動電極的部分,用于將電極精確定位在工件上方。電極(ji)夾持裝置(zhi)用于固定電極(ji),并確保電極(ji)在加(jia)工過程中保持穩定的位置(zhi)和角(jiao)度。
3、工作臺和工件夾持裝置
工作臺用于支撐和移動工件,以便在加工過程中精確定位工件。工(gong)(gong)件(jian)夾持裝(zhuang)置用于固定工(gong)(gong)件(jian),防止在加工(gong)(gong)過程中(zhong)發(fa)生移動或振(zhen)動。
4、電源和控制系統
電源系統為火花機提供所需的電壓和電流,用于產生電火花。控(kong)制系(xi)統(tong)是火花機的(de)核心(xin)部分,它控(kong)制電(dian)極(ji)和(he)工作臺的(de)運動(dong),以及(ji)電(dian)源的(de)通斷(duan),確(que)(que)保加(jia)工過程的(de)精確(que)(que)性和(he)穩定性。控(kong)制系(xi)統(tong)通常包括計(ji)算機數控(kong)(CNC)系(xi)統(tong),用于編程和(he)自動(dong)化(hua)加(jia)工過程。
5、工作液循環系統
工(gong)作(zuo)液(ye)在火花加(jia)工(gong)過程中起到冷卻、潤滑和清除加(jia)工(gong)廢屑(xie)的(de)(de)作(zuo)用。工(gong)作(zuo)液(ye)循環系(xi)統負責(ze)將工(gong)作(zuo)液(ye)輸送到加(jia)工(gong)區域(yu),并回收和過濾使用過的(de)(de)工(gong)作(zuo)液(ye)。
6、電氣系統和傳感器
電氣系統為火花機提供電力和信號傳輸,確保各個部件的正常運行。傳(chuan)感器用于(yu)監(jian)測(ce)加(jia)工(gong)過(guo)程中的(de)各種參數(shu),如電(dian)極(ji)和工(gong)作臺的(de)位置、電(dian)流(liu)和電(dian)壓等,以便及時調整和控制加(jia)工(gong)過(guo)程。
7、安全防護裝置
火(huo)花機(ji)在工作過程(cheng)中可能會產生火(huo)花和飛濺物,因此需要配備安全防(fang)護(hu)裝(zhuang)置,如防(fang)護(hu)罩、防(fang)護(hu)門和緊(jin)急停機(ji)按鈕等,以保護(hu)操(cao)作人員的(de)安全。
二、火花機的工作原理
進行電火花機加工(gong)時(shi),工(gong)具(ju)電(dian)極(ji)和工(gong)件(jian)分(fen)別(bie)接脈(mo)沖電(dian)源的兩極(ji),并浸入工(gong)作(zuo)液中,或(huo)將工(gong)作(zuo)液充入放電(dian)間隙(xi)。通(tong)過(guo)間隙(xi)自(zi)動控制系(xi)統控制工(gong)具(ju)電(dian)極(ji)向工(gong)件(jian)進給,當兩電(dian)極(ji)間的間隙(xi)達到一定距離時(shi),兩電(dian)極(ji)上(shang)施(shi)加的脈(mo)沖電(dian)壓將工(gong)作(zuo)液擊穿(chuan),產生(sheng)火花放電(dian)。
在放(fang)電的微(wei)細通道(dao)中瞬時(shi)集中大量(liang)的熱能,溫(wen)度(du)(du)可(ke)高達(da)一萬攝氏度(du)(du)以上(shang),壓力也(ye)有急劇變化,從(cong)而使這一點工(gong)作(zuo)(zuo)表面(mian)局(ju)部(bu)微(wei)量(liang)的金屬(shu)材料立刻(ke)熔化、氣(qi)化,并(bing)爆炸式地飛濺到(dao)工(gong)作(zuo)(zuo)液中,迅速冷凝,形成固體(ti)的金屬(shu)微(wei)粒,被工(gong)作(zuo)(zuo)液帶走。這時(shi)在工(gong)件表面(mian)上(shang)便留下(xia)一個微(wei)小的凹坑痕跡(ji),放(fang)電短暫(zan)停歇,兩電極間工(gong)作(zuo)(zuo)液恢復絕緣(yuan)狀態(tai)。
緊接(jie)著(zhu),下一個脈沖電壓又在兩電極相對接(jie)近(jin)的(de)(de)另(ling)一點處擊穿,產(chan)(chan)生火花放(fang)電,重復(fu)上(shang)述過(guo)程。這樣,雖然(ran)每個脈沖放(fang)電蝕除(chu)(chu)的(de)(de)金(jin)屬(shu)量極少,但(dan)因每秒有成千上(shang)萬次(ci)脈沖放(fang)電作用,就能蝕除(chu)(chu)較多(duo)的(de)(de)金(jin)屬(shu),具有一定的(de)(de)生產(chan)(chan)率。
在保持工(gong)(gong)(gong)具(ju)電(dian)極(ji)與(yu)工(gong)(gong)(gong)件之間(jian)恒定(ding)放電(dian)間(jian)隙的(de)(de)條件下,一邊(bian)蝕(shi)除(chu)工(gong)(gong)(gong)件金屬,一邊(bian)使工(gong)(gong)(gong)具(ju)電(dian)極(ji)不斷地向工(gong)(gong)(gong)件進給,最后便加工(gong)(gong)(gong)出與(yu)工(gong)(gong)(gong)具(ju)電(dian)極(ji)形狀相(xiang)對(dui)應的(de)(de)形狀來。因此(ci),只要改變工(gong)(gong)(gong)具(ju)電(dian)極(ji)的(de)(de)形狀和工(gong)(gong)(gong)具(ju)電(dian)極(ji)與(yu)工(gong)(gong)(gong)件之間(jian)的(de)(de)相(xiang)對(dui)運(yun)動方式,就能(neng)加工(gong)(gong)(gong)出各種復(fu)雜的(de)(de)型面。工(gong)(gong)(gong)具(ju)電(dian)極(ji)常用導(dao)電(dian)性(xing)良好、熔點(dian)較高、易加工(gong)(gong)(gong)的(de)(de)耐電(dian)蝕(shi)材料,如銅、石墨(mo)、銅鎢合金和鉬等。在加工(gong)(gong)(gong)過(guo)程中,工(gong)(gong)(gong)具(ju)電(dian)極(ji)也有損(sun)耗,但(dan)小于(yu)工(gong)(gong)(gong)件金屬的(de)(de)蝕(shi)除(chu)量,甚至接(jie)近于(yu)無損(sun)耗。
工(gong)作(zuo)液作(zuo)為放(fang)(fang)(fang)電(dian)(dian)(dian)介(jie)質,在加工(gong)過程中還起著冷(leng)(leng)卻、排屑等作(zuo)用。常(chang)用的(de)(de)(de)(de)工(gong)作(zuo)液是粘度較低(di)、閃點(dian)較高、性(xing)能(neng)穩(wen)定的(de)(de)(de)(de)介(jie)質,如(ru)煤油、去離子水和乳化液等。電(dian)(dian)(dian)火(huo)(huo)花(hua)(hua)機是一種(zhong)自(zi)激放(fang)(fang)(fang)電(dian)(dian)(dian),其(qi)特點(dian)如(ru)下(xia):火(huo)(huo)花(hua)(hua)放(fang)(fang)(fang)電(dian)(dian)(dian)的(de)(de)(de)(de)兩個電(dian)(dian)(dian)極(ji)間在放(fang)(fang)(fang)電(dian)(dian)(dian)前具較高的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya),當兩電(dian)(dian)(dian)極(ji)接近時(shi),其(qi)間介(jie)質被擊穿后,隨即(ji)發生火(huo)(huo)花(hua)(hua)放(fang)(fang)(fang)電(dian)(dian)(dian)。伴(ban)隨擊穿過程,兩電(dian)(dian)(dian)極(ji)間的(de)(de)(de)(de)電(dian)(dian)(dian)阻急(ji)劇變小,兩極(ji)之間的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)也隨之急(ji)劇變低(di)。火(huo)(huo)花(hua)(hua)通(tong)道必須在維持暫短的(de)(de)(de)(de)時(shi)間(通(tong)常(chang)為10-7-10-3s)后及時(shi)熄滅(mie),才可保持火(huo)(huo)花(hua)(hua)放(fang)(fang)(fang)電(dian)(dian)(dian)的(de)(de)(de)(de)“冷(leng)(leng)極(ji)”特性(xing)(即(ji)通(tong)道能(neng)量轉(zhuan)換(huan)的(de)(de)(de)(de)熱能(neng)來不及傳至電(dian)(dian)(dian)極(ji)縱深(shen)),使通(tong)道能(neng)量作(zuo)用于極(ji)小范圍。通(tong)道能(neng)量的(de)(de)(de)(de)作(zuo)用,可使電(dian)(dian)(dian)極(ji)局部被腐蝕(shi)。利(li)用火(huo)(huo)花(hua)(hua)放(fang)(fang)(fang)電(dian)(dian)(dian)時(shi)產生的(de)(de)(de)(de)腐蝕(shi)現(xian)象(xiang)對材料(liao)進(jin)行尺寸加工(gong)的(de)(de)(de)(de)方法(fa),叫電(dian)(dian)(dian)火(huo)(huo)花(hua)(hua)機加工(gong)。