在埋弧焊焊接過程中，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)送進按預(yu)選定的(de)速度等速進入(ru)焊接區

  工(gong)作(zuo)(zuo)原理是采用機械(xie)方法（更(geng)換變速(su)齒輪）來調(diao)速(su)。依靠電(dian)弧的(de)自身(shen)調(diao)節作(zuo)(zuo)用來維持弧長(chang)(chang)相(xiang)對穩定(ding)。當焊(han)(han)接(jie)電(dian)弧受到外界干擾變長(chang)(chang)增(zeng)加時，下降外特性電(dian)源(yuan)供(gong)給(gei)的(de)焊(han)(han)接(jie)電(dian)流(liu)減小，焊(han)(han)絲熔化速(su)度減緩(huan)，電(dian)弧便會由(you)長(chang)(chang)變短(duan)，趨向(xiang)給(gei)定(ding)值；反之，電(dian)弧變短(duan)時，焊(han)(han)接(jie)電(dian)流(liu)增(zeng)大，焊(han)(han)絲熔化加快，弧長(chang)(chang)又(you)由(you)短(duan)變長(chang)(chang)，趨向(xiang)給(gei)定(ding)值。按(an)這個工(gong)作(zuo)(zuo)原理制造的(de)等(deng)速(su)送絲埋弧焊(han)(han)設備(bei)有MZ1-1000、MZ2-1500和MZ3-500等(deng)型號，焊(han)(han)接(jie)電(dian)流(liu)可采用交、直電(dian)源(yuan)。

2. 焊絲的送進速度按電弧電壓的高低自動(dong)均(jun)勻調節

  電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)電(dian)(dian)(dian)(dian)壓(ya)調節原理是利用電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)電(dian)(dian)(dian)(dian)壓(ya)作為反(fan)饋(kui)信(xin)號(hao)，經過控制(zhi)調節系統改變(bian)送絲(si)速(su)度而保(bao)持弧(hu)(hu)(hu)(hu)長(chang)相對不變(bian)。當電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)受外界干擾變(bian)長(chang)，電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)電(dian)(dian)(dian)(dian)壓(ya)升高(gao)時，控制(zhi)調節系統接到電(dian)(dian)(dian)(dian)壓(ya)反(fan)饋(kui)信(xin)號(hao)后將(jiang)(jiang)送絲(si)速(su)度調快，弧(hu)(hu)(hu)(hu)長(chang)由(you)長(chang)變(bian)短(duan)，趨(qu)向穩定值(zhi)；當電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)長(chang)度變(bian)短(duan)，電(dian)(dian)(dian)(dian)弧(hu)(hu)(hu)(hu)電(dian)(dian)(dian)(dian)壓(ya)下降時，將(jiang)(jiang)送絲(si)速(su)度調慢，弧(hu)(hu)(hu)(hu)長(chang)增長(chang)趨(qu)向給定值(zhi)。這(zhe)種埋弧(hu)(hu)(hu)(hu)焊機(ji)的控制(zhi)系統稍復(fu)雜，具(ju)體型(xing)號(hao)有(you)MZ-1000和(he)MZ-1-1000等型(xing)號(hao)。焊接電(dian)(dian)(dian)(dian)流(liu)(liu)可采用交、直流(liu)(liu)電(dian)(dian)(dian)(dian)源(yuan)。

  按工作需要，埋弧焊機(ji)常見的(de)構造形式(shi)(shi)有焊車式(shi)(shi)、懸(xuan)(xuan)掛式(shi)(shi)、機(ji)床(chuang)式(shi)(shi)、懸(xuan)(xuan)臂式(shi)(shi)和門架式(shi)(shi)等，如圖3-16所示。