1、液壓密(mi)封件(jian)之形式選擇

　　在液壓(ya)(ya)系統中，常(chang)見的(de)密(mi)(mi)(mi)封(feng)形(xing)式有(you)擠壓(ya)(ya)型O形(xing)密(mi)(mi)(mi)封(feng)圈(quan)(quan)(quan)(quan)、Y形(xing)圈(quan)(quan)(quan)(quan)、V形(xing)圈(quan)(quan)(quan)(quan)、U形(xing)圈(quan)(quan)(quan)(quan)唇(chun)(chun)形(xing)密(mi)(mi)(mi)封(feng)。唇(chun)(chun)形(xing)密(mi)(mi)(mi)封(feng)圈(quan)(quan)(quan)(quan)主要(yao)用(yong)(yong)于往復動(dong)密(mi)(mi)(mi)封(feng)，與O形(xing)圈(quan)(quan)(quan)(quan)等擠壓(ya)(ya)密(mi)(mi)(mi)封(feng)相比，往復動(dong)密(mi)(mi)(mi)封(feng)使用(yong)(yong)唇(chun)(chun)形(xing)密(mi)(mi)(mi)封(feng)圈(quan)(quan)(quan)(quan)具有(you)更好的(de)綜合(he)性能和(he)更長的(de)使用(yong)(yong)壽命。

　　唇(chun)形(xing)(xing)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)圈(quan)的(de)(de)(de)(de)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)壓(ya)(ya)緊力(li)(li)(li)是隨(sui)介質壓(ya)(ya)力(li)(li)(li)的(de)(de)(de)(de)改變(bian)而(er)(er)變(bian)化的(de)(de)(de)(de)，工作(zuo)中始終(zhong)應監控(kong)介質壓(ya)(ya)力(li)(li)(li)的(de)(de)(de)(de)變(bian)化，即能(neng)保證足夠的(de)(de)(de)(de)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)壓(ya)(ya)緊力(li)(li)(li)，又不至于產生(sheng)過大的(de)(de)(de)(de)摩(mo)擦(ca)(ca)力(li)(li)(li)，擠壓(ya)(ya)性密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)主要靠預(yu)壓(ya)(ya)緊力(li)(li)(li)產生(sheng)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)力(li)(li)(li)，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)圈(quan)接(jie)觸壓(ya)(ya)力(li)(li)(li)預(yu)先給定，工作(zuo)中不能(neng)根據介質壓(ya)(ya)力(li)(li)(li)的(de)(de)(de)(de)改變(bian)而(er)(er)變(bian)化。大的(de)(de)(de)(de)預(yu)壓(ya)(ya)力(li)(li)(li)會使(shi)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)圈(quan)與密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面(mian)接(jie)觸面(mian)積增大，產生(sheng)很大的(de)(de)(de)(de)摩(mo)擦(ca)(ca)阻力(li)(li)(li)，過大的(de)(de)(de)(de)摩(mo)擦(ca)(ca)力(li)(li)(li)會造成(cheng)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)圈(quan)的(de)(de)(de)(de)破損，在低壓(ya)(ya)時造成(cheng)啟動(dong)困難(nan)，或產生(sheng)爬行現象(xiang)，唇(chun)形(xing)(xing)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)圈(quan)可(ke)以通過唇(chun)部撐開，變(bian)形(xing)(xing)補償小(xiao)的(de)(de)(de)(de)磨損量，保證密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)效果(guo)和密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)壽(shou)命;而(er)(er)O形(xing)(xing)圈(quan)隨(sui)著摩(mo)擦(ca)(ca)余量的(de)(de)(de)(de)減少，直(zhi)接(jie)影響其密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)性。

　　2、液(ye)壓密(mi)封件之材料選擇(ze)

　　密封(feng)(feng)(feng)件(jian)形式(shi)和(he)結構現(xian)(xian)(xian)在(zai)一般已(yi)經(jing)定型，各(ge)密封(feng)(feng)(feng)件(jian)質(zhi)量區(qu)別(bie)主要在(zai)于(yu)制(zhi)作材(cai)(cai)料上。密封(feng)(feng)(feng)材(cai)(cai)料主要使(shi)用(yong)(yong)橡(xiang)膠和(he)合(he)成樹脂。由于(yu)各(ge)種(zhong)材(cai)(cai)料性能特點(dian)不(bu)(bu)同(tong)，性能特點(dian)不(bu)(bu)同(tong)，用(yong)(yong)途也就有(you)(you)所不(bu)(bu)同(tong)。選用(yong)(yong)時(shi)需根據不(bu)(bu)同(tong)的使(shi)用(yong)(yong)條件(jian)和(he)不(bu)(bu)同(tong)的使(shi)用(yong)(yong)條件(jian)作出合(he)適的選擇。另外，某一材(cai)(cai)質(zhi)的密封(feng)(feng)(feng)對(dui)被密封(feng)(feng)(feng)的某一工作介質(zhi)(如礦物油等)表(biao)現(xian)(xian)(xian)較(jiao)好的密封(feng)(feng)(feng)性能，而對(dui)另一介質(zhi)表(biao)現(xian)(xian)(xian)極(ji)差(cha)，這就是密封(feng)(feng)(feng)材(cai)(cai)料與液壓油的相容(rong)性。還有(you)(you)，各(ge)種(zhong)不(bu)(bu)同(tong)的密封(feng)(feng)(feng)材(cai)(cai)料對(dui)你不(bu)(bu)同(tong)的工作條件(jian)表(biao)現(xian)(xian)(xian)出不(bu)(bu)同(tong)的性能。有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)熱，有(you)(you)些(xie)(xie)(xie)不(bu)(bu)耐(nai)(nai)(nai)熱;有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)酸(suan)，有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)堿，有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)水，有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)油;有(you)(you)些(xie)(xie)(xie)抗熱，有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)低溫(wen)，有(you)(you)些(xie)(xie)(xie)耐(nai)(nai)(nai)高(gao)溫(wen)，等等。這些(xie)(xie)(xie)因素(su)在(zai)考慮密封(feng)(feng)(feng)件(jian)材(cai)(cai)料的時(shi)候需注意(yi)。