在埋(mai)弧焊焊接過程中，維持電弧穩定燃燒，以及保持焊接參數基本不變是保證焊接接頭質量的基本要求。對此可通過以下兩種方法來實現。

1. 焊絲的(de)送(song)進按預選(xuan)定的(de)速度等速進入焊接(jie)區

  工(gong)(gong)作原理(li)是采(cai)用機械方法(fa)（更換變(bian)速齒輪）來(lai)調(diao)速。依靠電(dian)(dian)弧(hu)(hu)的自(zi)身(shen)調(diao)節作用來(lai)維持弧(hu)(hu)長(chang)相對(dui)穩定(ding)(ding)。當焊(han)接(jie)電(dian)(dian)弧(hu)(hu)受(shou)到外(wai)界(jie)干擾變(bian)長(chang)增加(jia)時，下降(jiang)外(wai)特性(xing)電(dian)(dian)源供給(gei)的焊(han)接(jie)電(dian)(dian)流減(jian)小，焊(han)絲(si)熔(rong)(rong)化(hua)速度減(jian)緩，電(dian)(dian)弧(hu)(hu)便會由長(chang)變(bian)短(duan)，趨(qu)向(xiang)給(gei)定(ding)(ding)值(zhi)(zhi)；反之，電(dian)(dian)弧(hu)(hu)變(bian)短(duan)時，焊(han)接(jie)電(dian)(dian)流增大，焊(han)絲(si)熔(rong)(rong)化(hua)加(jia)快，弧(hu)(hu)長(chang)又由短(duan)變(bian)長(chang)，趨(qu)向(xiang)給(gei)定(ding)(ding)值(zhi)(zhi)。按(an)這個工(gong)(gong)作原理(li)制造的等速送(song)絲(si)埋弧(hu)(hu)焊(han)設備有(you)MZ1-1000、MZ2-1500和MZ3-500等型號，焊(han)接(jie)電(dian)(dian)流可(ke)采(cai)用交(jiao)、直電(dian)(dian)源。

2. 焊絲(si)的送進速(su)度按電弧電壓的高低自動均勻(yun)調(diao)節

  電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)調(diao)節原理是利用電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)作為反饋信號，經過(guo)控(kong)制調(diao)節系統(tong)改變(bian)(bian)送(song)絲速(su)(su)度而保持弧(hu)長(chang)相對不(bu)變(bian)(bian)。當(dang)電(dian)(dian)(dian)(dian)弧(hu)受外界干擾變(bian)(bian)長(chang)，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)升高時，控(kong)制調(diao)節系統(tong)接到電(dian)(dian)(dian)(dian)壓(ya)(ya)反饋信號后將送(song)絲速(su)(su)度調(diao)快，弧(hu)長(chang)由長(chang)變(bian)(bian)短，趨向穩定值(zhi)；當(dang)電(dian)(dian)(dian)(dian)弧(hu)長(chang)度變(bian)(bian)短，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)下降時，將送(song)絲速(su)(su)度調(diao)慢，弧(hu)長(chang)增(zeng)長(chang)趨向給定值(zhi)。這種埋弧(hu)焊(han)機的控(kong)制系統(tong)稍復(fu)雜，具體(ti)型號有MZ-1000和MZ-1-1000等型號。焊(han)接電(dian)(dian)(dian)(dian)流(liu)可采(cai)用交、直流(liu)電(dian)(dian)(dian)(dian)源。

  按(an)工作需(xu)要，埋弧焊(han)機常見的構造形式(shi)有焊(han)車式(shi)、懸掛(gua)式(shi)、機床(chuang)式(shi)、懸臂(bei)式(shi)和(he)門架式(shi)等(deng)，如圖3-16所示。