今天我給大家講講便(bian)攜式探傷儀靈敏度低的原因：
主要原因：
1.發射(she)電(dian)(dian)(dian)(dian)(dian)路(lu)部分 1).電(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)壓(ya)E過低 2).閘流管(guan)或可(ke)控硅導(dao)電(dian)(dian)(dian)(dian)(dian)時，內(nei)阻太(tai)(tai)大。 3).觸發波重復頻(pin)(pin)(pin)率(lv)(lv)(lv)太(tai)(tai)高或閘流管(guan)的負(fu)載(zai)電(dian)(dian)(dian)(dian)(dian)阻R太(tai)(tai)大，使發射(she)電(dian)(dian)(dian)(dian)(dian)路(lu)中電(dian)(dian)(dian)(dian)(dian)容(rong)C不能充電(dian)(dian)(dian)(dian)(dian)至電(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)壓(ya)E。 4).電(dian)(dian)(dian)(dian)(dian)容(rong)C漏電(dian)(dian)(dian)(dian)(dian) 5).諧(xie)振式發射(she)電(dian)(dian)(dian)(dian)(dian)路(lu)中，諧(xie)振頻(pin)(pin)(pin)率(lv)(lv)(lv)與(yu)探(tan)頭(tou)的自然頻(pin)(pin)(pin)率(lv)(lv)(lv)偏離太(tai)(tai)大。
2.接收電(dian)(dian)路部分 1).電(dian)(dian)子管或晶體(ti)管衰老。2).電(dian)(dian)子管或晶體(ti)管工作點(偏(pian)流或偏(pian)壓)不(bu)在*佳點。 3).電(dian)(dian)源(yuan)電(dian)(dian)壓低(濾(lv)波電(dian)(dian)容(rong)漏電(dian)(dian)) 4).調諧回路調亂，放(fang)大(da)頻率(lv)與發射頻率(lv)不(bu)一(yi)致(zhi)。
3.便攜式探(tan)(tan)傷儀探(tan)(tan)頭(tou)(tou)(tou)部分(fen) 1).晶片(pian)(pian)(pian)(pian)的靈敏度(du)低(發射及接(jie)收的靈敏度(du)的乘積低)。 2).晶片(pian)(pian)(pian)(pian)的自然頻率(lv)與發射頻率(lv)或放大頻率(lv)不(bu)一(yi)致。3).晶片(pian)(pian)(pian)(pian)的銀層(ceng)脫落 4).保護膜(mo)片(pian)(pian)(pian)(pian)磨損。 5).保護膜(mo)片(pian)(pian)(pian)(pian)與晶片(pian)(pian)(pian)(pian)之間的油層(ceng)流(liu)失(有(you)的探(tan)(tan)頭(tou)(tou)(tou)保護膜(mo)與晶片(pian)(pian)(pian)(pian)直接(jie)粘合)。 6).吸收塊阻(zu)尼(ni)太大。 7).晶片(pian)(pian)(pian)(pian)的阻(zu)抗(kang)與探(tan)(tan)頭(tou)(tou)(tou)引線的阻(zu)抗(kang)不(bu)匹(pi)配(如用低阻(zu)抗(kang)的電纜線連(lian)接(jie)高(gao)阻(zu)抗(kang)的石英(ying)晶片(pian)(pian)(pian)(pian))。 8).探(tan)(tan)頭(tou)(tou)(tou)在超過其居里溫(wen)度(du)的高(gao)溫(wen)工作(zuo)物上(shang)探(tan)(tan)測(ce)效率(lv)低。 9).探(tan)(tan)頭(tou)(tou)(tou)線及插座頭(tou)(tou)(tou)接(jie)觸不(bu)佳。
4.示(shi)波管(guan)部分 1).偏轉靈敏度低。 2).加速極電壓過高。
檢查方法：
1.檢查發射(she)電(dian)(dian)路 1).用萬(wan)用表測量(liang)超聲波(bo)(bo)(bo)測厚(hou)儀電(dian)(dian)源電(dian)(dian)壓(ya)是(shi)否過(guo)低 2).用萬(wan)用表測量(liang)閘流(liu)管(可控硅)的(de)屏(陽)極電(dian)(dian)壓(ya)的(de)平(ping)均值是(shi)否偏高或偏低 3).檢查電(dian)(dian)容(rong)C是(shi)否漏(lou)電(dian)(dian) 4).用脈沖示波(bo)(bo)(bo)器(qi)(或用外差式波(bo)(bo)(bo)長計(ji))測量(liang)發射(she)波(bo)(bo)(bo)的(de)頻率是(shi)否符合。用試(shi)塊檢查時，將探頭放在試(shi)塊上，是(shi)熒光屏上有反射(she)波(bo)(bo)(bo)，調(diao)整發射(she)電(dian)(dian)路中線圈(quan)L的(de)鐵心，是(shi)反射(she)波(bo)(bo)(bo)*高
2.檢查(cha)(cha)接(jie)(jie)收(shou)電(dian)(dian)(dian)(dian)路 1).測量各(ge)級(ji)電(dian)(dian)(dian)(dian)壓(ya)是否(fou)正常。 2).檢查(cha)(cha)調(diao)諧頻(pin)(pin)率(lv)(lv)(lv)及放大(da)(da)(da)(da)倍(bei)數(shu)，有(you)以下(xia)幾種方法(fa)：(1)將高(gao)(gao)頻(pin)(pin)信號(hao)(hao)發生器的(de)(de)(de)(de)輸(shu)出端接(jie)(jie)在(zai)接(jie)(jie)收(shou)電(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)輸(shu)入端，將電(dian)(dian)(dian)(dian)壓(ya)表(biao)接(jie)(jie)在(zai)檢波(bo)(bo)電(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)輸(shu)出端，改變高(gao)(gao)頻(pin)(pin)信號(hao)(hao)發生器的(de)(de)(de)(de)頻(pin)(pin)率(lv)(lv)(lv)(輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)不變)，記下(xia)電(dian)(dian)(dian)(dian)壓(ya)表(biao)的(de)(de)(de)(de)數(shu)值。電(dian)(dian)(dian)(dian)壓(ya)*大(da)(da)(da)(da)時(shi)的(de)(de)(de)(de)頻(pin)(pin)率(lv)(lv)(lv)應(ying)與發射(she)頻(pin)(pin)率(lv)(lv)(lv)符合，并(bing)記下(xia)放大(da)(da)(da)(da)倍(bei)數(shu)。如(ru)頻(pin)(pin)率(lv)(lv)(lv)偏離過大(da)(da)(da)(da)，則需調(diao)整探(tan)傷儀各(ge)級(ji)線(xian)(xian)圈(quan)。 (2)將探(tan)頭放在(zai)試塊上(shang)(shang)，使(shi)熒光(guang)屏上(shang)(shang)有(you)反(fan)(fan)射(she)波(bo)(bo)，用(yong)示波(bo)(bo)器觀察各(ge)級(ji)屏極(或集(ji)電(dian)(dian)(dian)(dian)極)的(de)(de)(de)(de)波(bo)(bo)形是否(fou)上(shang)(shang)等(deng)比(bi)上(shang)(shang)等(deng)大(da)(da)(da)(da)(從前級(ji)往后級(ji))，如(ru)有(you)上(shang)(shang)等(deng)波(bo)(bo)形不夠大(da)(da)(da)(da)，說(shuo)明該級(ji)有(you)問(wen)題。 (3)放大(da)(da)(da)(da)電(dian)(dian)(dian)(dian)路如(ru)系(xi)單調(diao)諧，將探(tan)頭放在(zai)試塊上(shang)(shang)，調(diao)各(ge)級(ji)線(xian)(xian)圈(quan)的(de)(de)(de)(de)鐵(tie)心，使(shi)反(fan)(fan)射(she)波(bo)(bo)*高(gao)(gao)。 3).檢查(cha)(cha)電(dian)(dian)(dian)(dian)子或晶體管是否(fou)衰老。 4).調(diao)整工作(zuo)點(dian)(電(dian)(dian)(dian)(dian)子管的(de)(de)(de)(de)陰極電(dian)(dian)(dian)(dian)阻(zu)、晶體管的(de)(de)(de)(de)射(she)極電(dian)(dian)(dian)(dian)阻(zu)及基極分壓(ya)電(dian)(dian)(dian)(dian)阻(zu))。5.檢查(cha)(cha)調(diao)諧線(xian)(xian)圈(quan)是否(fou)霉斷。
3.檢(jian)(jian)(jian)查(cha)探(tan)(tan)頭(tou)部分(fen) 1).首(shou)先用(yong)(yong)良好的(de)(de)(de)探(tan)(tan)頭(tou)探(tan)(tan)測，如(ru)探(tan)(tan)傷(shang)儀(yi)靈(ling)敏度(du)(du)提高(gao)了，說明(ming)原探(tan)(tan)頭(tou)有(you)問題，需換新。 2).如(ru)晶片(pian)(pian)退化(hua)，可(ke)重新電極(ji)(ji)化(hua)，有(you)的(de)(de)(de)儀(yi)器(qi)有(you)極(ji)(ji)化(hua)插座，將探(tan)(tan)頭(tou)插在(zai)(zai)插座上(shang)，開機(ji)通電十分(fen)鐘即可(ke)。如(ru)無極(ji)(ji)化(hua)插座，在(zai)(zai)探(tan)(tan)傷(shang)儀(yi)內部示波管的(de)(de)(de)高(gao)壓(ya)(ya)(ya)(ya)回路(lu)中(zhong)，引出適當(dang)電壓(ya)(ya)(ya)(ya)即可(ke)。鈦(tai)酸(suan)鋇(bei)的(de)(de)(de)極(ji)(ji)化(hua)電壓(ya)(ya)(ya)(ya)為(wei)每毫(hao)米2000伏，鋯(gao)鈦(tai)酸(suan)鉛(qian)為(wei)每毫(hao)米4000伏。晶片(pian)(pian)初次極(ji)(ji)化(hua)時，將晶片(pian)(pian)夾(jia)在(zai)(zai)夾(jia)具中(zhong)，并侵入盛有(you)變(bian)(bian)壓(ya)(ya)(ya)(ya)器(qi)油(you)的(de)(de)(de)容器(qi)中(zhong)，并將容器(qi)放(fang)在(zai)(zai)電爐(lu)上(shang)，加溫(wen)至(zhi)居里溫(wen)度(du)(du)(鈦(tai)酸(suan)鋇(bei)120℃，鋯(gao)鈦(tai)酸(suan)鉛(qian)300℃)后接(jie)通電壓(ya)(ya)(ya)(ya)，20分(fen)鐘后切(qie)斷電爐(lu)電源，使變(bian)(bian)壓(ya)(ya)(ya)(ya)器(qi)油(you)自然冷卻(que)至(zhi)室溫(wen)時，將高(gao)壓(ya)(ya)(ya)(ya)關掉即可(ke)。 3).晶片(pian)(pian)的(de)(de)(de)壓(ya)(ya)(ya)(ya)電性(xing)能可(ke)用(yong)(yong)簡單的(de)(de)(de)方(fang)法檢(jian)(jian)(jian)查(cha)，即用(yong)(yong)高(gao)靈(ling)敏度(du)(du)的(de)(de)(de)電子(zi)管電壓(ya)(ya)(ya)(ya)表(biao)檢(jian)(jian)(jian)查(cha)，將地(di)線一端壓(ya)(ya)(ya)(ya)在(zai)(zai)晶片(pian)(pian)的(de)(de)(de)一端，將表(biao)棒稍用(yong)(yong)力壓(ya)(ya)(ya)(ya)晶片(pian)(pian)的(de)(de)(de)另(ling)一端，看電壓(ya)(ya)(ya)(ya)表(biao)指(zhi)針的(de)(de)(de)偏轉是否(fou)大，如(ru)不偏轉或偏轉甚小，則壓(ya)(ya)(ya)(ya)電性(xing)能不好。
4.檢查示波(bo)(bo)管(guan)部分 1).檢查示波(bo)(bo)管(guan)的(de)偏(pian)轉(zhuan)(zhuan)靈(ling)敏(min)度 將電(dian)壓(ya)表跨接(jie)于垂直(zhi)偏(pian)轉(zhuan)(zhuan)板(ban)，正表棒(bang)接(jie)示波(bo)(bo)管(guan)的(de)第(di)7腳(jiao)，負表棒(bang)接(jie)第(di)8腳(jiao)，開機(ji)后記下掃描線在熒光(guang)屏上的(de)位(wei)置(zhi)，并記下電(dian)壓(ya)表的(de)數值(zhi)(zhi)，然后調節儀器面板(ban)上的(de)垂直(zhi)位(wei)移(yi)電(dian)位(wei)器W，使掃描線向(xiang)上，移(yi)動A毫(hao)(hao)米(mi)，若此時電(dian)壓(ya)表指(zhi)示電(dian)壓(ya)的(de)變化為(wei)(wei)B伏特，則偏(pian)轉(zhuan)(zhuan)靈(ling)敏(min)度=A/B 毫(hao)(hao)米(mi)/伏 正常偏(pian)轉(zhuan)(zhuan)靈(ling)敏(min)度為(wei)(wei)0.35~0.54毫(hao)(hao)米(mi)/伏，若所(suo)得(de)之值(zhi)(zhi)比正常值(zhi)(zhi)小的(de)多，則應換新管(guan)。 2).檢查加速(su)極(ji)電(dian)壓(ya) 示波(bo)(bo)管(guan)的(de)偏(pian)轉(zhuan)(zhuan)靈(ling)敏(min)度與加速(su)極(ji)電(dian)壓(ya)成反比，若加速(su)極(ji)電(dian)壓(ya)過(guo)高，應減低(di)之。
上一篇 便攜式探傷儀操作前的準備工作都有哪些? 下一篇 便攜式探傷儀為什么會不顯示掃描線呢?