點焊機的工作原理

點焊(han)的工(gong)藝(yi)過程為開通冷(leng)卻水(shui)；將焊(han)件表面(mian)清理(li)干凈(jing)，裝配準(zhun)確后，送入上、下電極之間，施加壓(ya)力，使其(qi)接觸良好;通電使兩(liang)工件接觸表面受熱，局(ju)部熔化，形成熔核(he);斷電后保(bao)持壓力(li)，使熔核(he)在壓力(li)下冷(leng)卻(que)凝固形成焊點;去(qu)除(chu)壓力，取出工(gong)件。焊接電(dian)流、電(dian)極壓力、通(tong)電(dian)時間及電(dian)極工(gong)作(zuo)表面尺(chi)寸等點焊工(gong)藝參(can)數對焊接質量有重大影響。

點焊(han)機(ji)(ji)利(li)用正負(fu)兩(liang)極在瞬間短(duan)路時產生的(de)高溫電弧(hu)來熔化電焊(han)條上的(de)焊(han)料和(he)被焊(han)材料，來達到(dao)使它們結(jie)合的(de)目的(de)。電焊(han)機(ji)(ji)的(de)結(jie)構十分(fen)簡單，說白了就(jiu)是一個大功(gong)率的(de)變壓器，將220V交流電(dian)(dian)(dian)變為(wei)低電(dian)(dian)(dian)壓，大電(dian)(dian)(dian)流的電(dian)(dian)(dian)源，可(ke)(ke)以(yi)是直流的也可(ke)(ke)以(yi)是交流的。電(dian)(dian)(dian)焊變壓器有自身的特點，就(jiu)是具有電(dian)(dian)(dian)壓急劇(ju)下降(jiang)的特性(xing)。

在(zai)焊(han)(han)條引(yin)燃后電(dian)壓下降(jiang)，電(dian)焊(han)(han)機的(de)工作電(dian)壓的(de)調節，除(chu)了一次的(de)220/380電(dian)(dian)(dian)(dian)壓變(bian)換，二(er)次(ci)線(xian)圈也有抽頭變(bian)換電(dian)(dian)(dian)(dian)壓，同(tong)時(shi)(shi)還有用(yong)(yong)鐵芯來調節的(de)，可調鐵芯。電(dian)(dian)(dian)(dian)焊機(ji)一(yi)(yi)般是一(yi)(yi)個大(da)功率(lv)的(de)變(bian)壓器，系(xi)利用(yong)(yong)電(dian)(dian)(dian)(dian)感(gan)的(de)原理(li)做(zuo)成的(de)。電(dian)(dian)(dian)(dian)感(gan)量在接通和斷開時(shi)(shi)會產(chan)生巨大(da)的(de)電(dian)(dian)(dian)(dian)壓變(bian)化，利用(yong)(yong)正負(fu)兩(liang)極在瞬間短(duan)路時(shi)(shi)產(chan)生的(de)高(gao)壓電(dian)(dian)(dian)(dian)弧(hu)來熔(rong)化電(dian)(dian)(dian)(dian)焊條上的(de)焊料。來達到使它們結合的(de)目的(de)。

點(dian)焊(han)(han)(han)(han)是焊(han)(han)(han)(han)件裝配接(jie)(jie)接(jie)(jie)頭，并壓緊在(zai)兩(liang)電(dian)(dian)(dian)極之間(jian)，利用(yong)電(dian)(dian)(dian)阻熱熔化母材(cai)金(jin)屬，形成焊(han)(han)(han)(han)點(dian)的(de)(de)電(dian)(dian)(dian)阻焊(han)(han)(han)(han)方(fang)法。點(dian)焊(han)(han)(han)(han)多用(yong)于(yu)薄板的(de)(de)連接(jie)(jie)，如飛機蒙皮(pi)、航空(kong)發動機的(de)(de)火煙筒、汽車駕駛室外殼等(deng)。點(dian)焊(han)(han)(han)(han)機焊(han)(han)(han)(han)接(jie)(jie)變壓器(qi)(qi)是點(dian)焊(han)(han)(han)(han)電(dian)(dian)(dian)器(qi)(qi)，它的(de)(de)次級只(zhi)有一(yi)圈回路(lu)。上(shang)、下電(dian)(dian)(dian)極與電(dian)(dian)(dian)極臂(bei)既(ji)用(yong)于(yu)傳導焊(han)(han)(han)(han)接(jie)(jie)電(dian)(dian)(dian)流，又用(yong)于(yu)傳遞動力。冷(leng)卻水路(lu)通過變壓器(qi)(qi)、電(dian)(dian)(dian)極等(deng)部分，以免發熱焊(han)(han)(han)(han)接(jie)(jie)時，應(ying)先通冷(leng)卻水，然后接(jie)(jie)通電(dian)(dian)(dian)源開關(guan)。電(dian)(dian)(dian)極的(de)(de)質(zhi)量直接(jie)(jie)影響(xiang)焊(han)(han)(han)(han)接(jie)(jie)過程、焊(han)(han)(han)(han)接(jie)(jie)質(zhi)量和生產(chan)率。電(dian)(dian)(dian)極材(cai)料常用(yong)紫(zi)銅(tong)(tong)、鎘青銅(tong)(tong)、鉻青銅(tong)(tong)等(deng)制成;電(dian)(dian)(dian)極(ji)的(de)形(xing)狀多(duo)種多(duo)樣(yang)，主要(yao)根據焊(han)件形(xing)狀確定。安裝電(dian)(dian)(dian)極(ji)時，要(yao)注意上(shang)、下電(dian)(dian)(dian)極(ji)表面(mian)保持平行;電極平面要保持(chi)清潔，常用砂布或銼刀修整。焊接循(xun)環(huan)點焊和凸(tu)焊的焊接循(xun)環(huan)由四個基本階(jie)段(點焊過程(cheng))：

(1)預壓階段——電(dian)極下降到(dao)電(dian)流接通階段，確保電(dian)極壓緊工(gong)件，使工(gong)件間有適當壓力。

(2)焊接(jie)時間(jian)——焊接(jie)電流(liu)通過工(gong)件，產熱(re)形成熔核。

(3)維(wei)持時(shi)間——切斷焊接電流，電極壓(ya)力繼(ji)續維(wei)持至熔核凝固到足(zu)夠(gou)強度。

(4)休止時(shi)間——電極開始(shi)提起到電極再次開始(shi)下(xia)降，開始(shi)下(xia)一個焊接循環。

為(wei)了改善焊接接頭的性能，有時需要將(jiang)下列各項中的一個或多(duo)個加于(yu)基本循環：

(1)加大預壓力以消除厚工(gong)件(jian)之間的間隙，使之緊密貼合。

(2)用預熱脈沖提高金屬的塑性，使工件(jian)易于(yu)緊密貼(tie)合、防止(zhi)飛濺；凸焊時(shi)這(zhe)樣做可(ke)以(yi)使多個凸點在通電焊接前與平板均(jun)勻接觸，以(yi)保證各點加(jia)熱的(de)一致。