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分析金牛機械密封泄漏原因,要根據實踐經驗、現場觀察并借助儀器測量,弄清楚密封元件與密封性能之間的內在聯系,全方位檢查密封環、傳動件、加載彈性元件、輔助密封圈、防轉機構、緊固螺釘、底座、軸套、密封腔體以及密封系統等部位,綜合分析,找出金牛機械密封泄漏原因,以此為依據,選擇正確的金牛機械密封。下面是金牛機械密封常見(jian)的泄漏現(xian)象及原因分析
1. 機械(xie)磨損(sun)
金牛機械密封泄漏中較為常見的就是機械磨損,機械磨損導致密封副端面產生分離,造成密封泄漏。機械磨損還會破壞密封副的正常配合關系,使傳動軸轉動時引起密封元件發生軸向位移和擺動,導致金牛機械密封泄漏。這種金牛機械密封泄漏可根據金牛機械密封副磨損痕跡的具體情況進行準確判斷。如果密封磨損痕跡均勻而產生泄漏,說明金牛機械密封泄漏的出現是由其他部位引起的。此時需要檢測其他部位而非密封本身。如果密封副沒有磨損痕跡而出現泄漏,說明可能是動環相對于靜環不旋轉或者出現打滑,可以對防轉銷或底座進行檢測,確定是否是防轉銷脫落了或者底座的孔徑與密封件的外徑不相匹配所致。如果金牛機械密封副(fu)磨損痕跡很深,則有(you)可能是傳動軸轉動時(shi)密封(feng)副(fu)出現分離,有(you)大顆粒物質嵌入(ru)軟質碳(tan)端面,此時(shi)可用硬質材(cai)料作為密封(feng)副(fu)材(cai)料。
2. 由熱損傷引(yin)起的密(mi)封泄(xie)漏
機械產生(sheng)過(guo)大的(de)熱量(liang)往往造成機械密封(feng)副變形、熱裂(lie)或(huo)皰疤,引(yin)起(qi)泄漏。
熱(re)(re)裂主要(yao)是(shi)機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)在(zai)(zai)(zai)干摩擦或(huo)冷(leng)卻系統(tong)發生中(zhong)斷等情況下,造成(cheng)機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)在(zai)(zai)(zai)短時間內承受超負荷(he)熱(re)(re)量(liang)而出(chu)現(xian)密(mi)(mi)封(feng)(feng)(feng)(feng)環(huan)表面徑向裂紋(wen)。由于熱(re)(re)裂往往引(yin)起密(mi)(mi)封(feng)(feng)(feng)(feng)環(huan)磨(mo)損加劇,造成(cheng)大量(liang)的泄漏,所以在(zai)(zai)(zai)設(she)(she)計機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)時要(yao)充分考(kao)慮機(ji)械材(cai)料(liao)的物理(li)性質,并要(yao)根(gen)據(ju)機(ji)械材(cai)質設(she)(she)定特定的運轉條件。皰疤主要(yao)是(shi)由于碳石(shi)墨導致粘結劑被擠出(chu),出(chu)現(xian)密(mi)(mi)封(feng)(feng)(feng)(feng)泄漏。由于介質的潤滑性、操作溫度(du)(du)、線速度(du)(du)、配對材(cai)料(liao)組合等因素的影響都(dou)會(hui)使機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)產(chan)生大量(liang)熱(re)(re)能(neng),所以為(wei)了(le)使機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)摩擦熱(re)(re)能(neng)及時散發,改(gai)變端面面積(ji)比、減少載(zai)荷(he)、靜止型(xing)密(mi)(mi)封(feng)(feng)(feng)(feng)并加導流套都(dou)能(neng)較好地改(gai)善密(mi)(mi)封(feng)(feng)(feng)(feng)的散熱(re)(re)條件,保證機(ji)械密(mi)(mi)封(feng)(feng)(feng)(feng)的正常(chang)運行。
3. 由腐蝕引起的密封泄漏
機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)的(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)是(shi)引(yin)起機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)泄漏(lou)最主(zhu)要(yao)(yao)原因之一,一般有(you)化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)和電化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)。化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)主(zhu)要(yao)(yao)是(shi)由于機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)長(chang)時(shi)間與腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性介(jie)質接(jie)(jie)觸引(yin)起的(de)(de)(de)。這(zhe)種(zhong)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)對機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)影響(xiang)較大,甚至會(hui)導致機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)金(jin)屬(shu)晶界的(de)(de)(de)破壞(huai)或斷裂。電化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)主(zhu)要(yao)(yao)是(shi)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)環(huan)兩種(zhong)金(jin)屬(shu)在(zai)電介(jie)質溶液中(zhong)產生電位差(cha),導致機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)產生電池(chi)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)。不(bu)管是(shi)化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)還是(shi)電化(hua)(hua)學(xue)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)對機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)都有(you)很大的(de)(de)(de)影響(xiang),所以在(zai)機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)材(cai)(cai)(cai)料(liao)選取上(shang)要(yao)(yao)考(kao)慮密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)元(yuan)件(jian)(jian)(jian)的(de)(de)(de)精(jing)密(mi)(mi)(mi)(mi)(mi)性,選擇比主(zhu)機(ji)更耐腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)材(cai)(cai)(cai)料(liao)。機(ji)械(xie)(xie)(xie)(xie)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速度(du)(du)(du)的(de)(de)(de)快慢與壓(ya)力、溫度(du)(du)(du)和滑動(dong)速度(du)(du)(du)都有(you)密(mi)(mi)(mi)(mi)(mi)切的(de)(de)(de)關系(xi)。當密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)元(yuan)件(jian)(jian)(jian)所承受的(de)(de)(de)壓(ya)力增大、溫度(du)(du)(du)升高、滑動(dong)速度(du)(du)(du)加快時(shi),密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)元(yuan)件(jian)(jian)(jian)的(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速度(du)(du)(du)也(ye)會(hui)加快。針對這(zhe)些因素,采取雙端面(mian)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)可以減少(shao)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)元(yuan)件(jian)(jian)(jian)的(de)(de)(de)零(ling)件(jian)(jian)(jian)與腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性介(jie)質的(de)(de)(de)接(jie)(jie)觸,從而減輕腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性介(jie)質對密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)元(yuan)件(jian)(jian)(jian)的(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)。密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)環(huan)材(cai)(cai)(cai)料(liao)的(de)(de)(de)選取可以采用奧(ao)氏體不(bu)銹鋼,并(bing)在(zai)1 050℃下進行熱處理,防止(zhi)晶間腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)。
4. 由(you)密(mi)封零件失效引起的密(mi)封泄漏
機械(xie)的輔助密(mi)封(feng)(feng)(feng)圈(quan)(quan)對機械(xie)密(mi)封(feng)(feng)(feng)有著至(zhi)關重要(yao)的作用(yong)(yong),輔助密(mi)封(feng)(feng)(feng)圈(quan)(quan)一般選用(yong)(yong)合成(cheng)(cheng)橡(xiang)膠(jiao)O形(xing)圈(quan)(quan)。合成(cheng)(cheng)橡(xiang)膠(jiao)O形(xing)圈(quan)(quan)一旦出(chu)現(xian)老(lao)化、永久性變形(xing)、扭曲及(ji)擠出(chu)損傷等(deng)情況時,會(hui)使(shi)(shi)機械(xie)密(mi)封(feng)(feng)(feng)出(chu)現(xian)泄(xie)漏(lou)。因此合成(cheng)(cheng)橡(xiang)膠(jiao)O形(xing)圈(quan)(quan)的材質選取要(yao)充分考(kao)慮其安(an)(an)全使(shi)(shi)用(yong)(yong)溫度,增加合成(cheng)(cheng)橡(xiang)膠(jiao)O形(xing)圈(quan)(quan)的截面,用(yong)(yong)橡(xiang)膠(jiao)包(bao)覆聚四氟乙烯等(deng)復合材料作為密(mi)封(feng)(feng)(feng)圈(quan)(quan)的材料,提高材料的硬(ying)度。在(zai)密(mi)封(feng)(feng)(feng)圈(quan)(quan)安(an)(an)裝時,要(yao)在(zai)密(mi)封(feng)(feng)(feng)槽內涂上潤滑(hua)脂。除了密(mi)封(feng)(feng)(feng)圈(quan)(quan)外(wai),彈簧(huang)、傳動銷(xiao)等(deng)零部(bu)件如發生變形(xing)、斷(duan)裂(lie)、腐蝕等(deng)也會(hui)導致密(mi)封(feng)(feng)(feng)泄(xie)漏(lou)。在(zai)機械(xie)密(mi)封(feng)(feng)(feng)運行(xing)(xing)時,也要(yao)考(kao)慮彈簧(huang)、傳動銷(xiao)等(deng)零部(bu)件的狀(zhuang)態,確保彈簧(huang)、傳動銷(xiao)等(deng)零部(bu)件沒有磨損或(huo)者變形(xing),使(shi)(shi)機械(xie)密(mi)封(feng)(feng)(feng)正常運行(xing)(xing)。