在埋弧(hu)焊(han)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(han)絲的(de)送進(jin)按預選(xuan)定的(de)速度等速進(jin)入(ru)焊(han)接區

  工作(zuo)原理是采用(yong)機械方法(fa)（更換變(bian)速齒(chi)輪）來調速。依靠電(dian)(dian)弧的自身(shen)調節作(zuo)用(yong)來維持弧長相對穩定。當焊(han)接電(dian)(dian)弧受到外界干擾變(bian)長增加(jia)時，下(xia)降(jiang)外特性電(dian)(dian)源供給的焊(han)接電(dian)(dian)流減小，焊(han)絲熔化(hua)(hua)速度減緩，電(dian)(dian)弧便(bian)會由(you)長變(bian)短(duan)，趨向(xiang)給定值；反之，電(dian)(dian)弧變(bian)短(duan)時，焊(han)接電(dian)(dian)流增大，焊(han)絲熔化(hua)(hua)加(jia)快(kuai)，弧長又(you)由(you)短(duan)變(bian)長，趨向(xiang)給定值。按(an)這個工作(zuo)原理制造的等速送絲埋弧焊(han)設備(bei)有MZ1-1000、MZ2-1500和(he)MZ3-500等型號，焊(han)接電(dian)(dian)流可(ke)采用(yong)交、直電(dian)(dian)源。

2. 焊絲的送進速度按電弧(hu)電壓的高低(di)自(zi)動均勻調節

  電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)調(diao)節原理是利用(yong)(yong)電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)作為反饋(kui)信號，經(jing)過控制(zhi)調(diao)節系(xi)統改變(bian)送絲速度(du)而保持弧(hu)長(chang)(chang)相(xiang)對(dui)不變(bian)。當(dang)電(dian)(dian)(dian)(dian)弧(hu)受外(wai)界干(gan)擾(rao)變(bian)長(chang)(chang)，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)升高(gao)時，控制(zhi)調(diao)節系(xi)統接到電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)反饋(kui)信號后將(jiang)送絲速度(du)調(diao)快，弧(hu)長(chang)(chang)由(you)長(chang)(chang)變(bian)短，趨(qu)向穩(wen)定值；當(dang)電(dian)(dian)(dian)(dian)弧(hu)長(chang)(chang)度(du)變(bian)短，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)下降時，將(jiang)送絲速度(du)調(diao)慢(man)，弧(hu)長(chang)(chang)增長(chang)(chang)趨(qu)向給定值。這種埋弧(hu)焊(han)機的控制(zhi)系(xi)統稍復雜，具(ju)體型號有(you)MZ-1000和MZ-1-1000等(deng)型號。焊(han)接電(dian)(dian)(dian)(dian)流(liu)可(ke)采用(yong)(yong)交、直流(liu)電(dian)(dian)(dian)(dian)源。

  按(an)工作需要，埋(mai)弧焊機常見的構造形(xing)式有焊車式、懸掛式、機床式、懸臂式和門架式等，如(ru)圖3-16所示(shi)。