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. 焊絲的送進按預選定(ding)的速(su)度等速(su)進入焊接區

  工作(zuo)原理(li)(li)是(shi)采(cai)用(yong)機械方法(fa)（更換變速齒輪）來調速。依靠電(dian)(dian)(dian)弧(hu)(hu)(hu)的(de)自身(shen)調節作(zuo)用(yong)來維持弧(hu)(hu)(hu)長相對穩定(ding)。當焊(han)接電(dian)(dian)(dian)弧(hu)(hu)(hu)受到外界干(gan)擾變長增加時，下降外特(te)性電(dian)(dian)(dian)源(yuan)供給(gei)(gei)的(de)焊(han)接電(dian)(dian)(dian)流減小(xiao)，焊(han)絲熔(rong)化速度減緩，電(dian)(dian)(dian)弧(hu)(hu)(hu)便會由(you)長變短(duan)(duan)，趨(qu)向給(gei)(gei)定(ding)值；反之，電(dian)(dian)(dian)弧(hu)(hu)(hu)變短(duan)(duan)時，焊(han)接電(dian)(dian)(dian)流增大(da)，焊(han)絲熔(rong)化加快(kuai)，弧(hu)(hu)(hu)長又由(you)短(duan)(duan)變長，趨(qu)向給(gei)(gei)定(ding)值。按這個工作(zuo)原理(li)(li)制造的(de)等速送絲埋弧(hu)(hu)(hu)焊(han)設(she)備有MZ1-1000、MZ2-1500和MZ3-500等型號(hao)，焊(han)接電(dian)(dian)(dian)流可采(cai)用(yong)交、直(zhi)電(dian)(dian)(dian)源(yuan)。

2. 焊(han)絲的送進速度按電(dian)弧電(dian)壓的高低自動均(jun)勻(yun)調(diao)節

  電(dian)(dian)弧(hu)電(dian)(dian)壓調(diao)(diao)節原理是(shi)利用電(dian)(dian)弧(hu)電(dian)(dian)壓作為反(fan)饋信(xin)號(hao)，經(jing)過控制調(diao)(diao)節系統(tong)改變(bian)送(song)(song)絲速(su)度(du)而保持弧(hu)長(chang)相對不變(bian)。當電(dian)(dian)弧(hu)受外界干擾(rao)變(bian)長(chang)，電(dian)(dian)弧(hu)電(dian)(dian)壓升高時，控制調(diao)(diao)節系統(tong)接到電(dian)(dian)壓反(fan)饋信(xin)號(hao)后(hou)將送(song)(song)絲速(su)度(du)調(diao)(diao)快，弧(hu)長(chang)由長(chang)變(bian)短，趨(qu)向(xiang)穩定值(zhi)；當電(dian)(dian)弧(hu)長(chang)度(du)變(bian)短，電(dian)(dian)弧(hu)電(dian)(dian)壓下(xia)降時，將送(song)(song)絲速(su)度(du)調(diao)(diao)慢，弧(hu)長(chang)增長(chang)趨(qu)向(xiang)給定值(zhi)。這種埋弧(hu)焊機的控制系統(tong)稍復(fu)雜，具體型號(hao)有(you)MZ-1000和MZ-1-1000等型號(hao)。焊接電(dian)(dian)流可采用交(jiao)、直流電(dian)(dian)源。

  按(an)工作(zuo)需(xu)要，埋弧焊機(ji)常見的構造形式(shi)有焊車(che)式(shi)、懸(xuan)掛(gua)式(shi)、機(ji)床式(shi)、懸(xuan)臂式(shi)和門架式(shi)等，如圖3-16所示(shi)。