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(su)度等速(su)進入焊接區

  工(gong)作(zuo)原理是采用機械方法（更換變(bian)速(su)齒輪(lun)）來(lai)調速(su)。依靠電(dian)(dian)弧的(de)(de)自身調節作(zuo)用來(lai)維持弧長(chang)相對穩定。當焊(han)接(jie)電(dian)(dian)弧受到外(wai)界干擾變(bian)長(chang)增加(jia)時(shi)(shi)，下降外(wai)特性電(dian)(dian)源(yuan)供(gong)給(gei)的(de)(de)焊(han)接(jie)電(dian)(dian)流減小，焊(han)絲熔化速(su)度減緩，電(dian)(dian)弧便(bian)會(hui)由長(chang)變(bian)短，趨向給(gei)定值；反之，電(dian)(dian)弧變(bian)短時(shi)(shi)，焊(han)接(jie)電(dian)(dian)流增大，焊(han)絲熔化加(jia)快，弧長(chang)又由短變(bian)長(chang)，趨向給(gei)定值。按這個(ge)工(gong)作(zuo)原理制造的(de)(de)等速(su)送絲埋弧焊(han)設(she)備有MZ1-1000、MZ2-1500和MZ3-500等型號，焊(han)接(jie)電(dian)(dian)流可采用交(jiao)、直電(dian)(dian)源(yuan)。

2. 焊絲的(de)(de)送進(jin)速度按(an)電弧電壓的(de)(de)高低(di)自動均勻調節

  電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)調(diao)節(jie)原(yuan)理(li)是利(li)用電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)作為(wei)反饋(kui)信(xin)號，經過控(kong)制調(diao)節(jie)系(xi)統改變送絲速度而保持弧(hu)長(chang)(chang)相對(dui)不變。當(dang)電(dian)(dian)(dian)(dian)弧(hu)受外(wai)界干(gan)擾(rao)變長(chang)(chang)，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)升高時(shi)，控(kong)制調(diao)節(jie)系(xi)統接(jie)到電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)反饋(kui)信(xin)號后將(jiang)送絲速度調(diao)快，弧(hu)長(chang)(chang)由長(chang)(chang)變短，趨(qu)向(xiang)穩定值；當(dang)電(dian)(dian)(dian)(dian)弧(hu)長(chang)(chang)度變短，電(dian)(dian)(dian)(dian)弧(hu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)下降時(shi)，將(jiang)送絲速度調(diao)慢(man)，弧(hu)長(chang)(chang)增長(chang)(chang)趨(qu)向(xiang)給定值。這種埋弧(hu)焊(han)機的控(kong)制系(xi)統稍復雜(za)，具體型號有MZ-1000和MZ-1-1000等型號。焊(han)接(jie)電(dian)(dian)(dian)(dian)流(liu)可采用交、直流(liu)電(dian)(dian)(dian)(dian)源。

  按工作需要，埋(mai)弧焊機(ji)常見的構造形式(shi)(shi)有焊車式(shi)(shi)、懸掛式(shi)(shi)、機(ji)床(chuang)式(shi)(shi)、懸臂式(shi)(shi)和門架式(shi)(shi)等，如(ru)圖3-16所示。