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)送進(jin)按預選(xuan)定的(de)速度等速進(jin)入焊接區

  工(gong)作(zuo)原理是采(cai)用(yong)(yong)機械方法（更換(huan)變(bian)(bian)速齒(chi)輪）來(lai)調(diao)速。依靠(kao)電(dian)(dian)(dian)弧(hu)(hu)的(de)自身(shen)調(diao)節(jie)作(zuo)用(yong)(yong)來(lai)維持(chi)弧(hu)(hu)長(chang)相對(dui)穩定(ding)。當焊(han)接電(dian)(dian)(dian)弧(hu)(hu)受到外界干擾變(bian)(bian)長(chang)增(zeng)加(jia)時，下降外特(te)性電(dian)(dian)(dian)源供給的(de)焊(han)接電(dian)(dian)(dian)流減小，焊(han)絲熔化速度(du)減緩，電(dian)(dian)(dian)弧(hu)(hu)便會由(you)長(chang)變(bian)(bian)短，趨(qu)向(xiang)給定(ding)值(zhi)；反之(zhi)，電(dian)(dian)(dian)弧(hu)(hu)變(bian)(bian)短時，焊(han)接電(dian)(dian)(dian)流增(zeng)大，焊(han)絲熔化加(jia)快(kuai)，弧(hu)(hu)長(chang)又(you)由(you)短變(bian)(bian)長(chang)，趨(qu)向(xiang)給定(ding)值(zhi)。按這個(ge)工(gong)作(zuo)原理制造的(de)等(deng)速送絲埋弧(hu)(hu)焊(han)設備有MZ1-1000、MZ2-1500和MZ3-500等(deng)型號，焊(han)接電(dian)(dian)(dian)流可采(cai)用(yong)(yong)交、直電(dian)(dian)(dian)源。

2. 焊絲的(de)送進(jin)速度按電弧電壓的(de)高(gao)低自動(dong)均勻(yun)調(diao)節

  電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)壓(ya)(ya)調節原理(li)是利用電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)壓(ya)(ya)作為反(fan)饋(kui)信號，經過(guo)控(kong)(kong)(kong)制調節系(xi)統(tong)改變(bian)送絲(si)(si)(si)速(su)度(du)(du)而(er)保持弧長(chang)(chang)相對不變(bian)。當電(dian)(dian)(dian)(dian)弧受外界干擾(rao)變(bian)長(chang)(chang)，電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)壓(ya)(ya)升高時(shi)，控(kong)(kong)(kong)制調節系(xi)統(tong)接到電(dian)(dian)(dian)(dian)壓(ya)(ya)反(fan)饋(kui)信號后將送絲(si)(si)(si)速(su)度(du)(du)調快，弧長(chang)(chang)由(you)長(chang)(chang)變(bian)短(duan)，趨(qu)向(xiang)穩(wen)定值；當電(dian)(dian)(dian)(dian)弧長(chang)(chang)度(du)(du)變(bian)短(duan)，電(dian)(dian)(dian)(dian)弧電(dian)(dian)(dian)(dian)壓(ya)(ya)下降時(shi)，將送絲(si)(si)(si)速(su)度(du)(du)調慢，弧長(chang)(chang)增長(chang)(chang)趨(qu)向(xiang)給定值。這種埋弧焊機的控(kong)(kong)(kong)制系(xi)統(tong)稍復雜，具體型(xing)號有MZ-1000和MZ-1-1000等型(xing)號。焊接電(dian)(dian)(dian)(dian)流(liu)可采用交、直流(liu)電(dian)(dian)(dian)(dian)源。

  按(an)工作需要，埋(mai)弧(hu)焊(han)(han)機常見的(de)構造形(xing)式(shi)有焊(han)(han)車(che)式(shi)、懸掛式(shi)、機床式(shi)、懸臂式(shi)和門架式(shi)等，如圖3-16所示。