1. 基本條件及要求

  ①. 試(shi)件材質(zhi)：15CrMo.

  ②. 試件尺寸及坡口角(jiao)度：如圖4-35所示。

  ③. 焊接材(cai)料(liao)：E5503-B2(R302)或E5515-B2(R307),焊條直徑(jing)Φ2.5mm,焊條使用前(qian)要求(qiu)烘干。

  ④. 焊機：ZX7-400S.

2. 試件清(qing)理及裝配

  ①. 清除坡口(kou)及其兩側外表(biao)面20mm范圍內的(de)油、銹及其他(ta)污物、直至露出(chu)金屬(shu)光澤。

  ②. 裝(zhuang)配：采用(yong)(yong)兩(liang)點(dian)(dian)(dian)定位(wei)焊(han)接(jie)(jie)固定，點(dian)(dian)(dian)固點(dian)(dian)(dian)在時鐘2點(dian)(dian)(dian)與(yu)(yu)10點(dian)(dian)(dian)位(wei)置，所用(yong)(yong)材料與(yu)(yu)焊(han)接(jie)(jie)試件時相(xiang)同(tong)，且(qie)點(dian)(dian)(dian)焊(han)處的裝(zhuang)配間(jian)隙起(qi)焊(han)處為(wei)2.0mm(另一邊間(jian)隙為(wei)3.0mm).焊(han)點(dian)(dian)(dian)長度為(wei)10~15mm,要求焊(han)透(tou)并(bing)不(bu)(bu)得有焊(han)接(jie)(jie)缺陷，焊(han)點(dian)(dian)(dian)兩(liang)端(duan)用(yong)(yong)砂(sha)輪機(ji)打磨出斜(xie)坡，以利于接(jie)(jie)頭。試件的錯邊量應(ying)不(bu)(bu)大于0.5mm,保證管與(yu)(yu)管同(tong)心(xin)。將試件垂直(zhi)固定于焊(han)接(jie)(jie)架上，接(jie)(jie)頭與(yu)(yu)操作者視(shi)線相(xiang)適應(ying)為(wei)宜。

3. 焊(han)接工藝參數

 焊接工藝參(can)數(shu)見表4-14.

4. 操作要點及注意事項

  采用三層四道焊(han)，可(ke)分前后兩個半圈(quan)進行施焊(han)，也可(ke)整圈(quan)進行施焊(han)。

 ①. 斷(duan)弧焊(han)法打底焊(han)

   引弧(hu)(hu)在(zai)時鐘(zhong)6點(dian)前10mm的位置坡(po)(po)(po)口(kou)面(mian)的一(yi)側(ce)上(shang)邊(bian)(bian)(bian)(bian)緣。然后把電(dian)弧(hu)(hu)移至(zhi)鈍(dun)邊(bian)(bian)(bian)(bian)間(jian)隙處，當鈍(dun)邊(bian)(bian)(bian)(bian)熔(rong)(rong)(rong)化(hua)后，焊(han)(han)(han)(han)條(tiao)向下(xia)壓一(yi)下(xia)，當聽到“噗噗”聲后，立即把電(dian)弧(hu)(hu)移至(zhi)坡(po)(po)(po)口(kou)下(xia)邊(bian)(bian)(bian)(bian)緣，形(xing)成(cheng)第一(yi)個熔(rong)(rong)(rong)池后再(zai)采用(yong)短弧(hu)(hu)以兩點(dian)擊穿法，向坡(po)(po)(po)口(kou)上(shang)邊(bian)(bian)(bian)(bian)緣及(ji)(ji)下(xia)邊(bian)(bian)(bian)(bian)緣根部分別給送(song)熔(rong)(rong)(rong)滴，依次循環。在(zai)施(shi)焊(han)(han)(han)(han)過程中(zhong)，要首先擊穿坡(po)(po)(po)口(kou)的下(xia)緣，再(zai)擊穿坡(po)(po)(po)口(kou)的上(shang)邊(bian)(bian)(bian)(bian)緣，并(bing)使下(xia)熔(rong)(rong)(rong)孔在(zai)前、上(shang)熔(rong)(rong)(rong)孔在(zai)后，坡(po)(po)(po)口(kou)的上(shang)、下(xia)邊(bian)(bian)(bian)(bian)緣鈍(dun)邊(bian)(bian)(bian)(bian)處各要熔(rong)(rong)(rong)化(hua)1.5~2mm.弧(hu)(hu)柱長度應透過內壁(bi)1/3左(zuo)右。焊(han)(han)(han)(han)接打底層(ceng)時的焊(han)(han)(han)(han)條(tiao)水平方向角(jiao)度，如圖(tu)4-36所示。焊(han)(han)(han)(han)條(tiao)的下(xia)傾(qing)角(jiao)為(wei)10°~15°,以控制(zhi)熔(rong)(rong)(rong)渣(zha)和形(xing)成(cheng)熔(rong)(rong)(rong)池，并(bing)盡可能將(jiang)熔(rong)(rong)(rong)池形(xing)狀(zhuang)控制(zhi)成(cheng)為(wei)斜橢圓形(xing)，避(bi)免出現凸圓形(xing)焊(han)(han)(han)(han)縫，因(yin)為(wei)凸圓形(xing)焊(han)(han)(han)(han)縫容易形(xing)成(cheng)層(ceng)間(jian)夾渣(zha)及(ji)(ji)熔(rong)(rong)(rong)合不良等缺陷。

  后半圈操作方法與前半圈相同(tong)。

 ②. 連弧焊(han)法打底焊(han)

   在(zai)時(shi)(shi)鐘6點(dian)前10mm的位置，在(zai)坡口一側下(xia)邊緣引弧(hu)，向上(shang)做斜橢圓(yuan)形(xing)運(yun)條，向后的動作要(yao)小，向上(shang)的動作要(yao)大，并(bing)(bing)同時(shi)(shi)壓住電(dian)(dian)弧(hu)，擊(ji)(ji)穿(chuan)坡口根(gen)部。當發出“噗噗”聲，形(xing)成(cheng)熔(rong)(rong)孔后，并(bing)(bing)觀察當坡口上(shang)鈍(dun)邊被熔(rong)(rong)化(hua)1.5~2mm時(shi)(shi)，再(zai)向下(xia)方(fang)做斜橢圓(yuan)形(xing)運(yun)條。坡口下(xia)鈍(dun)邊也(ye)要(yao)熔(rong)(rong)化(hua)1.5~2mm,弧(hu)柱長度要(yao)透過內(nei)壁1/2,收弧(hu)時(shi)(shi)應將電(dian)(dian)弧(hu)帶到坡口上(shang)邊緣，向后方(fang)提(ti)起再(zai)熄(xi)弧(hu)。接頭時(shi)(shi)，應在(zai)距(ju)焊道末端(duan)10~15mm處引弧(hu)，并(bing)(bing)做斜橢圓(yuan)運(yun)條，當運(yun)到原熔(rong)(rong)池的1/2處時(shi)(shi)，將電(dian)(dian)弧(hu)向管內(nei)壓、擊(ji)(ji)穿(chuan)，然(ran)后再(zai)以(yi)斜橢圓(yuan)形(xing)運(yun)條法施焊。

 ③. 填充及蓋(gai)面焊

   首(shou)先清(qing)理打底(di)焊(han)的(de)熔(rong)渣(zha)，修(xiu)平焊(han)縫的(de)凸處，焊(han)接(jie)第二層及蓋面焊(han)時(shi)，要由下向上(shang)排列(lie)焊(han)接(jie)的(de)多(duo)道焊(han)，采(cai)用直線(xian)運條法，焊(han)接(jie)時(shi)電流(liu)應略大一些，熔(rong)池(chi)形狀應盡可能控制為斜橢(tuo)圓形。如果運條時(shi)熔(rong)渣(zha)和(he)液態(tai)金(jin)屬混合在一起，可將電弧略為拉長并向后（與焊(han)接(jie)方(fang)向相反）帶(dai)一下，熔(rong)渣(zha)就會被(bei)吹(chui)向后方(fang)，與液態(tai)金(jin)屬分離，使熔(rong)池(chi)保(bao)持清(qing)晰，焊(han)縫平整。

   施(shi)焊(han)(han)時焊(han)(han)條(tiao)(tiao)的(de)角(jiao)(jiao)度，填充時，焊(han)(han)條(tiao)(tiao)要基本保(bao)持水(shui)(shui)平位置，焊(han)(han)條(tiao)(tiao)與水(shui)(shui)平軸線成90°夾角(jiao)(jiao)。蓋面層(ceng)時，焊(han)(han)條(tiao)(tiao)應與水(shui)(shui)平軸成15°傾(qing)角(jiao)(jiao)。下(xia)面的(de)焊(han)(han)縫(feng)焊(han)(han)條(tiao)(tiao)向下(xia)傾(qing)，上(shang)面的(de)焊(han)(han)縫(feng)焊(han)(han)條(tiao)(tiao)向上(shang)傾(qing)，如圖4-37所示。這(zhe)樣可防(fang)止產生咬邊，并有利于焊(han)(han)道與母(mu)材金屬的(de)圓(yuan)滑過渡。