我們(men)時常看到(dao)精密機械零(ling)件上有- -些(xie)非常小的(de)(de)(de)孔，相信大(da)家-定很好奇,這(zhe)些(xie)小而(er)深(shen)的(de)(de)(de)孔是(shi)如何加(jia)工(gong)(gong)(gong)出來的(de)(de)(de)。這(zhe)就需要(yao)依靠電(dian)火(huo)花(hua)機床來操作了(le)，微(wei)細電(dian)火(huo)花(hua)加(jia)工(gong)(gong)(gong)是(shi)利(li)用高頻微(wei)能脈沖(chong)電(dian)源,將(jiang)高頻放(fang)(fang)電(dian)能量輸(shu)向放(fang)(fang)電(dian)間隙，靠產生(sheng)的(de)(de)(de)高溫(wen)熱效(xiao)應(ying)等綜合效(xiao)應(ying)實(shi)現對被(bei)加(jia)工(gong)(gong)(gong)的(de)(de)(de)精密零(ling)部件上材料(liao)的(de)(de)(de)去除,進而(er)達到(dao)對其(qi)尺寸加(jia)工(gong)(gong)(gong)的(de)(de)(de)目的(de)(de)(de)。由于被(bei)加(jia)工(gong)(gong)(gong)的(de)(de)(de)孔徑細微(wei), -般要(yao)想達到(dao)精密機械加(jia)工(gong)(gong)(gong)的(de)(de)(de)尺寸精度和表面(mian)質量要(yao)求(qiu)，還需要(yao)有一些(xie)別的(de)(de)(de)方面(mian)的(de)(de)(de)要(yao)求(qiu)。

小(xiao)孔(kong)電(dian)火花精密機(ji)械(xie)加I現(xian)在(zai)常常采用空心(xin)電(dian)極(ji)的(de)加工(gong)方法,電(dian)極(ji)的(de)最小(xiao)直徑約為0.2mm-0.3mm ,采用水作(zuo)為加工(gong)液(ye)(ye),再向做(zuo)回轉運動的(de)空心(xin)電(dian)極(ji)中通(tong)入高(gao)壓(ya)工(gong)作(zuo)液(ye)(ye),沖(chong)走(zou)加工(gong)屑,并(bing)保持高(gao)電(dian)流密度(du)(du)連續正常放(fang)電(dian)，因(yin)此這種精密機(ji)械(xie)加工(gong)方法速度(du)(du)高(gao)。但(dan)同時也會存(cun)在(zai)-些問題 ,如工(gong)具(ju)電(dian)極(ji)截(jie)面積小(xiao),容易變(bian)形;精密機(ji)械(xie)零件加工(gong)孔(kong)徑小(xiao)，放(fang)電(dian)間隙微(wei)小(xiao);微(wei)小(xiao)孔(kong)加工(gong)深徑比(bi)大,散熱以及排屑困難。

基于以(yi)_上原因,電(dian)(dian)火花微(wei)小孔加工(gong)中(zhong)往往電(dian)(dian)極損耗較大。所(suo)以(yi)工(gong)具電(dian)(dian)極應(ying)選(xuan)擇剛(gang)性好(hao)、容易矯(jiao)直(zhi),加工(gong)穩(wen)定性好(hao)和損耗小的材料,如銅鎢合金絲、鎢絲等。精密機械加工(gong)時為了避(bi)免電(dian)(dian)極傾斜或彎曲(qu),還需要設置工(gong)具電(dian)(dian)極的導向裝置。

為了改善微小孔加(jia)(jia)工(gong)(gong)時的排屑條件,使(shi)(shi)精(jing)密(mi)機械零件加(jia)(jia)工(gong)(gong)過程穩定(ding),常采(cai)用電磁振動頭,使(shi)(shi)I具電極(ji)(ji)絲沿軸(zhou)向振動,或(huo)(huo)采(cai)用超聲波(bo)振動頭，使(shi)(shi)工(gong)(gong)具電極(ji)(ji)端(duan)面作軸(zhou)向高頻(pin)振動，進行電火花超聲波(bo)復合(he)加(jia)(jia)工(gong)(gong)，可以大(da)大(da)提高生產(chan)率。如果(guo)所加(jia)(jia)工(gong)(gong)的小孔直徑較(jiao)大(da),允許采(cai)用空心(xin)電極(ji)(ji)(如空心(xin)紫銅(tong)管(guan)或(huo)(huo)黃銅(tong)管(guan)) , 則可以用較(jiao)高的壓力(li)強迫沖(chong)沒擊,加(jia)(jia)工(gong)(gong)速度將顯著提高。如果(guo)機床主(zhu)軸(zhou)有旋轉(zhuan)(zhuan)功(gong)能(neng),或(huo)(huo)采(cai)用旋轉(zhuan)(zhuan)頭附件使(shi)(shi)I具電極(ji)(ji)轉(zhuan)(zhuan)動，或(huo)(huo)使(shi)(shi)電極(ji)(ji)轉(zhuan)(zhuan)動，或(huo)(huo)使(shi)(shi)工(gong)(gong)件轉(zhuan)(zhuan)動,則除(chu)可提高加(jia)(jia)工(gong)(gong)速度外,還可提高加(jia)(jia)工(gong)(gong)小孔的圓(yuan)度。

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