精密點焊機焊點是如何形成的

發布時間：2021-07-20 14:51瀏覽次數：次

點焊(han)過程可(ke)分為彼此相聯的三個階段：預加(jia)壓(ya)力、通電加(jia)熱和鍛壓(ya)。
預加壓力

施加預焊(han)極壓(ya)力以(yi)保(bao)持(chi)焊(han)縫在焊(han)縫處緊(jin)密(mi)接觸(chu)(chu)。如果(guo)壓(ya)力不足，接觸(chu)(chu)電(dian)阻(zu)過大，會導致(zhi)焊(han)件(jian)(jian)燒穿或(huo)電(dian)極工作面燒壞。因此，通電(dian)前應使電(dian)壓(ya)力達到預定值，以(yi)保(bao)證電(dian)極與焊(han)件(jian)(jian)、焊(han)件(jian)(jian)之間(jian)的接觸(chu)(chu)電(dian)阻(zu)保(bao)持(chi)穩定。

通電加熱

提供電(dian)(dian)(dian)(dian)加熱以提供焊(han)(han)(han)接(jie)(jie)(jie)件(jian)之(zhi)(zhi)間形成所需的(de)(de)(de)熔(rong)核。大(da)電(dian)(dian)(dian)(dian)流密度(du)出(chu)現在兩(liang)電(dian)(dian)(dian)(dian)極(ji)接(jie)(jie)(jie)觸(chu)(chu)(chu)面(mian)之(zhi)(zhi)間的(de)(de)(de)金屬(shu)圓(yuan)筒中，焊(han)(han)(han)接(jie)(jie)(jie)件(jian)之(zhi)(zhi)間的(de)(de)(de)接(jie)(jie)(jie)觸(chu)(chu)(chu)電(dian)(dian)(dian)(dian)阻(zu)和(he)焊(han)(han)(han)接(jie)(jie)(jie)件(jian)本身的(de)(de)(de)電(dian)(dian)(dian)(dian)阻(zu)產(chan)(chan)生(sheng)了大(da)量(liang)的(de)(de)(de)熱量(liang)和(he)高(gao)(gao)溫(wen)。特別(bie)是(shi)在焊(han)(han)(han)縫之(zhi)(zhi)間的(de)(de)(de)接(jie)(jie)(jie)觸(chu)(chu)(chu)面(mian)上，熔(rong)核是(shi)先熔(rong)化(hua)形成的(de)(de)(de)。電(dian)(dian)(dian)(dian)極(ji)與焊(han)(han)(han)件(jian)之(zhi)(zhi)間的(de)(de)(de)接(jie)(jie)(jie)觸(chu)(chu)(chu)電(dian)(dian)(dian)(dian)阻(zu)也會產(chan)(chan)生(sheng)熱量(liang)，但大(da)部分熱量(liang)被水冷銅合金電(dian)(dian)(dian)(dian)極(ji)帶走。因此，焊(han)(han)(han)條與焊(han)(han)(han)件(jian)之(zhi)(zhi)間的(de)(de)(de)接(jie)(jie)(jie)觸(chu)(chu)(chu)溫(wen)度(du)遠低(di)于焊(han)(han)(han)件(jian)之(zhi)(zhi)間的(de)(de)(de)接(jie)(jie)(jie)觸(chu)(chu)(chu)點(dian)，在正常(chang)情況下(xia)達不到熔(rong)化(hua)溫(wen)度(du)。由于電(dian)(dian)(dian)(dian)流密度(du)低(di)，氣缸周圍的(de)(de)(de)金屬(shu)溫(wen)度(du)不高(gao)(gao)。靠近(jin)熔(rong)核的(de)(de)(de)金屬(shu)溫(wen)度(du)高(gao)(gao)，達到塑性狀(zhuang)態(tai)。在壓力的(de)(de)(de)作用(yong)下(xia)，焊(han)(han)(han)接(jie)(jie)(jie)形成一個(ge)塑料金屬(shu)環(huan)，緊(jin)緊(jin)地包圍熔(rong)化(hua)的(de)(de)(de)核心，防止(zhi)熔(rong)化(hua)的(de)(de)(de)金屬(shu)溢出(chu)。

鍛壓

鍛壓(ya)是電(dian)(dian)極(ji)切(qie)斷(duan)焊(han)(han)接(jie)電(dian)(dian)流后(hou)繼(ji)續擠(ji)壓(ya)焊(han)(han)點(dian)(dian)，對焊(han)(han)點(dian)(dian)起壓(ya)緊作用的(de)(de)過程。斷(duan)電(dian)(dian)后(hou)，熔(rong)化的(de)(de)核心開始(shi)冷(leng)卻并(bing)在(zai)封閉的(de)(de)金屬“殼”中(zhong)結晶，不(bu)能(neng)自由收縮。如果(guo)此時沒有(you)壓(ya)力，焊(han)(han)點(dian)(dian)容易(yi)收縮開裂，影響焊(han)(han)點(dian)(dian)的(de)(de)強度。如果(guo)存在(zai)電(dian)(dian)極(ji)擠(ji)壓(ya)，由此產生的(de)(de)擠(ji)壓(ya)變(bian)形允許熔(rong)核自由收縮并(bing)變(bian)得(de)致密。因此，斷(duan)電(dian)(dian)后(hou)必須保持電(dian)(dian)極(ji)壓(ya)力，直到熔(rong)核金屬完全凝固后(hou)才能(neng)釋(shi)放(fang)。鍛壓(ya)持續時間取決于(yu)焊(han)(han)接(jie)件的(de)(de)厚度。