0 引言
熱電偶是一種主要測溫元件, 是由不同的兩種金屬組成。其測量端通常是采用焊接形成的, 焊接質量的好壞直接影響熱電偶測量溫度的可靠性圖1 熱電偶點焊機基本原理圖
圖2 儲能式熱電偶點焊機電路拓撲圖
圖3 儲能式熱電偶點焊接電路原理圖 下載原圖
2.3 可控硅觸發控制電路
本項目采用可(ke)控硅(gui)直流(liu)開關構成的關斷(duan)電路, 當可(ke)控硅(gui)導通時, 儲(chu)能電容(rong)向工(gong)件(jian)放(fang)(fang)電, 當可(ke)控硅(gui)截止(zhi)時, 電容(rong)停(ting)止(zhi)放(fang)(fang)電。可(ke)控硅(gui)又叫晶閘(zha)管, 是一種非常重要(yao)的功率(lv)器(qi)件(jian), 具(ju)有反應快、效(xiao)率(lv)高(gao)的特點, 被廣(guang)泛應用于高(gao)電壓(ya)和高(gao)電流(liu)的控制。
可(ke)控(kong)硅觸發(fa)控(kong)制電(dian)路由(you)開關(guan)三(san)極(ji)管Q3及電(dian)壓比較器(qi)B3組成, 開關(guan)三(san)極(ji)管選用NPN型三(san)極(ji)管BU406, 通過二極(ji)管D9連接到可(ke)控(kong)硅Q2的(de)控(kong)制極(ji)。電(dian)壓比較器(qi)選用LM339。LM339是(shi)一種常用的(de)集成電(dian)路, 其內(nei)部集成有四個獨立(li)的(de)電(dian)壓比較器(qi)。
當(dang)未(wei)進行焊(han)接(jie)時(shi), 可(ke)控(kong)硅(gui)陰極(ji)懸空, 電(dian)(dian)(dian)壓比較器LM339反相(xiang)輸入端 (4) 高于(yu)門限電(dian)(dian)(dian)壓, 致使電(dian)(dian)(dian)壓比較器LM339輸出(chu)為低電(dian)(dian)(dian)平, 開(kai)(kai)關三極(ji)管(guan)Q3未(wei)導通(tong)(tong), 可(ke)控(kong)硅(gui)截止, 放(fang)(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)容(rong)不(bu)能放(fang)(fang)電(dian)(dian)(dian)。當(dang)焊(han)接(jie)時(shi), 可(ke)控(kong)硅(gui)陰極(ji)通(tong)(tong)過熱(re)電(dian)(dian)(dian)偶絲(si)連接(jie)到地, LM339反相(xiang)輸入端 (4) 電(dian)(dian)(dian)壓被拉(la)低, 低于(yu)門限電(dian)(dian)(dian)壓。此(ci)時(shi)放(fang)(fang)電(dian)(dian)(dian)指示燈CN6發光, LM339輸出(chu)端翻轉(zhuan), 為高電(dian)(dian)(dian)平。此(ci)時(shi), SG3525輸出(chu)關斷, 開(kai)(kai)關三極(ji)管(guan)Q3導通(tong)(tong), 觸發可(ke)控(kong)硅(gui)導通(tong)(tong), 放(fang)(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)容(rong)瞬時(shi)放(fang)(fang)電(dian)(dian)(dian), 瞬時(shi)大電(dian)(dian)(dian)流(liu)通(tong)(tong)過電(dian)(dian)(dian)偶絲(si), 完成焊(han)接(jie)。
3 結論
設計(ji)了基于鎳氫可(ke)充電(dian)(dian)電(dian)(dian)池儲能的(de)熱電(dian)(dian)偶(ou)點焊(han)(han)(han)機(ji), 并通過(guo)可(ke)調(diao)節電(dian)(dian)壓(ya)的(de)Boost升(sheng)壓(ya)電(dian)(dian)路實現點焊(han)(han)(han)機(ji)焊(han)(han)(han)接(jie)能量(liang)可(ke)調(diao)節功能。經過(guo)一(yi)段時間(jian)的(de)使用(yong)證(zheng)明, 儲能式熱電(dian)(dian)偶(ou)點焊(han)(han)(han)機(ji)較之普通點焊(han)(han)(han)機(ji)在使用(yong)范圍(wei)、控制、焊(han)(han)(han)接(jie)質量(liang)等(deng)諸多(duo)方(fang)面的(de)性能有明顯的(de)提升(sheng)。