在埋弧(hu)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(jin)按預選定的(de)速(su)度等速(su)進(jin)入焊接(jie)區

  工作(zuo)原(yuan)理(li)是采用機械方法（更換變速(su)齒(chi)輪）來調(diao)速(su)。依靠(kao)電(dian)(dian)弧(hu)的自身(shen)調(diao)節作(zuo)用來維持弧(hu)長相對穩定。當(dang)焊(han)(han)接電(dian)(dian)弧(hu)受(shou)到外界干擾變長增加時，下降外特性電(dian)(dian)源(yuan)供給(gei)的焊(han)(han)接電(dian)(dian)流(liu)減小，焊(han)(han)絲(si)熔化(hua)速(su)度減緩，電(dian)(dian)弧(hu)便會由(you)長變短(duan)(duan)，趨向給(gei)定值(zhi)；反之，電(dian)(dian)弧(hu)變短(duan)(duan)時，焊(han)(han)接電(dian)(dian)流(liu)增大，焊(han)(han)絲(si)熔化(hua)加快，弧(hu)長又由(you)短(duan)(duan)變長，趨向給(gei)定值(zhi)。按這個工作(zuo)原(yuan)理(li)制造的等速(su)送(song)絲(si)埋弧(hu)焊(han)(han)設備有MZ1-1000、MZ2-1500和(he)MZ3-500等型號，焊(han)(han)接電(dian)(dian)流(liu)可(ke)采用交、直(zhi)電(dian)(dian)源(yuan)。

2. 焊絲(si)的(de)送進速度按(an)電弧(hu)電壓的(de)高低自動(dong)均勻調節(jie)

  電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)電(dian)(dian)(dian)(dian)(dian)壓調節(jie)原理是利用(yong)電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)電(dian)(dian)(dian)(dian)(dian)壓作(zuo)為反饋信號(hao)，經過(guo)控(kong)制調節(jie)系(xi)統改變(bian)(bian)送(song)絲(si)速度(du)(du)而(er)保持弧(hu)(hu)長(chang)相對不變(bian)(bian)。當(dang)(dang)電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)受外界干(gan)擾變(bian)(bian)長(chang)，電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)電(dian)(dian)(dian)(dian)(dian)壓升高(gao)時，控(kong)制調節(jie)系(xi)統接到電(dian)(dian)(dian)(dian)(dian)壓反饋信號(hao)后將送(song)絲(si)速度(du)(du)調快，弧(hu)(hu)長(chang)由長(chang)變(bian)(bian)短，趨向穩定值；當(dang)(dang)電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)長(chang)度(du)(du)變(bian)(bian)短，電(dian)(dian)(dian)(dian)(dian)弧(hu)(hu)電(dian)(dian)(dian)(dian)(dian)壓下降時，將送(song)絲(si)速度(du)(du)調慢，弧(hu)(hu)長(chang)增長(chang)趨向給定值。這種埋(mai)弧(hu)(hu)焊機(ji)的控(kong)制系(xi)統稍復雜，具體(ti)型(xing)號(hao)有MZ-1000和MZ-1-1000等(deng)型(xing)號(hao)。焊接電(dian)(dian)(dian)(dian)(dian)流可(ke)采用(yong)交、直流電(dian)(dian)(dian)(dian)(dian)源。

  按工作需(xu)要，埋弧焊機常見的構造形式(shi)有焊車(che)式(shi)、懸(xuan)掛式(shi)、機床式(shi)、懸(xuan)臂(bei)式(shi)和門架式(shi)等，如圖3-16所示。