1、液壓(ya)密封(feng)件之形式選擇

　　在液壓(ya)系統中(zhong)，常見的(de)密(mi)(mi)封(feng)形(xing)(xing)式有擠壓(ya)型O形(xing)(xing)密(mi)(mi)封(feng)圈(quan)、Y形(xing)(xing)圈(quan)、V形(xing)(xing)圈(quan)、U形(xing)(xing)圈(quan)唇形(xing)(xing)密(mi)(mi)封(feng)。唇形(xing)(xing)密(mi)(mi)封(feng)圈(quan)主要用(yong)于(yu)往復(fu)動(dong)密(mi)(mi)封(feng)，與O形(xing)(xing)圈(quan)等擠壓(ya)密(mi)(mi)封(feng)相比，往復(fu)動(dong)密(mi)(mi)封(feng)使(shi)用(yong)唇形(xing)(xing)密(mi)(mi)封(feng)圈(quan)具有更好的(de)綜合(he)性能和更長的(de)使(shi)用(yong)壽命。

　　唇(chun)形(xing)(xing)密(mi)(mi)封(feng)(feng)(feng)(feng)圈(quan)(quan)(quan)(quan)的(de)(de)密(mi)(mi)封(feng)(feng)(feng)(feng)壓(ya)(ya)(ya)緊力(li)(li)是隨介(jie)質壓(ya)(ya)(ya)力(li)(li)的(de)(de)改變而(er)變化的(de)(de)，工作中始終應監控介(jie)質壓(ya)(ya)(ya)力(li)(li)的(de)(de)變化，即能保證(zheng)足夠的(de)(de)密(mi)(mi)封(feng)(feng)(feng)(feng)壓(ya)(ya)(ya)緊力(li)(li)，又不至于產生過大(da)的(de)(de)摩擦力(li)(li)，擠壓(ya)(ya)(ya)性密(mi)(mi)封(feng)(feng)(feng)(feng)主要靠(kao)預壓(ya)(ya)(ya)緊力(li)(li)產生密(mi)(mi)封(feng)(feng)(feng)(feng)力(li)(li)，密(mi)(mi)封(feng)(feng)(feng)(feng)圈(quan)(quan)(quan)(quan)接觸壓(ya)(ya)(ya)力(li)(li)預先給定(ding)，工作中不能根據(ju)介(jie)質壓(ya)(ya)(ya)力(li)(li)的(de)(de)改變而(er)變化。大(da)的(de)(de)預壓(ya)(ya)(ya)力(li)(li)會使(shi)密(mi)(mi)封(feng)(feng)(feng)(feng)圈(quan)(quan)(quan)(quan)與密(mi)(mi)封(feng)(feng)(feng)(feng)面接觸面積增大(da)，產生很大(da)的(de)(de)摩擦阻力(li)(li)，過大(da)的(de)(de)摩擦力(li)(li)會造成密(mi)(mi)封(feng)(feng)(feng)(feng)圈(quan)(quan)(quan)(quan)的(de)(de)破(po)損(sun)，在低壓(ya)(ya)(ya)時造成啟動困難，或產生爬行現象，唇(chun)形(xing)(xing)密(mi)(mi)封(feng)(feng)(feng)(feng)圈(quan)(quan)(quan)(quan)可以通過唇(chun)部撐開(kai)，變形(xing)(xing)補償(chang)小(xiao)的(de)(de)磨損(sun)量(liang)(liang)，保證(zheng)密(mi)(mi)封(feng)(feng)(feng)(feng)效果和密(mi)(mi)封(feng)(feng)(feng)(feng)壽(shou)命(ming);而(er)O形(xing)(xing)圈(quan)(quan)(quan)(quan)隨著摩擦余量(liang)(liang)的(de)(de)減少(shao)，直(zhi)接影響(xiang)其密(mi)(mi)封(feng)(feng)(feng)(feng)性。

　　2、液(ye)壓(ya)密封(feng)件之材料選擇

　　密(mi)封(feng)(feng)件(jian)(jian)形式和結構現在一般已經定(ding)型，各(ge)密(mi)封(feng)(feng)件(jian)(jian)質(zhi)量區別主(zhu)要在于制(zhi)作材(cai)(cai)料(liao)上(shang)。密(mi)封(feng)(feng)材(cai)(cai)料(liao)主(zhu)要使用(yong)(yong)橡膠和合成(cheng)樹脂(zhi)。由于各(ge)種(zhong)材(cai)(cai)料(liao)性(xing)能特(te)點(dian)不同(tong)(tong)(tong)，性(xing)能特(te)點(dian)不同(tong)(tong)(tong)，用(yong)(yong)途也就有(you)所不同(tong)(tong)(tong)。選(xuan)用(yong)(yong)時(shi)需(xu)根據不同(tong)(tong)(tong)的(de)(de)使用(yong)(yong)條(tiao)件(jian)(jian)和不同(tong)(tong)(tong)的(de)(de)使用(yong)(yong)條(tiao)件(jian)(jian)作出(chu)合適的(de)(de)選(xuan)擇。另外，某一材(cai)(cai)質(zhi)的(de)(de)密(mi)封(feng)(feng)對(dui)被(bei)密(mi)封(feng)(feng)的(de)(de)某一工(gong)作介(jie)質(zhi)(如礦物油(you)(you)等(deng)(deng))表(biao)現較(jiao)好的(de)(de)密(mi)封(feng)(feng)性(xing)能，而對(dui)另一介(jie)質(zhi)表(biao)現極差，這就是密(mi)封(feng)(feng)材(cai)(cai)料(liao)與(yu)液壓(ya)油(you)(you)的(de)(de)相容性(xing)。還有(you)，各(ge)種(zhong)不同(tong)(tong)(tong)的(de)(de)密(mi)封(feng)(feng)材(cai)(cai)料(liao)對(dui)你(ni)不同(tong)(tong)(tong)的(de)(de)工(gong)作條(tiao)件(jian)(jian)表(biao)現出(chu)不同(tong)(tong)(tong)的(de)(de)性(xing)能。有(you)些(xie)(xie)耐(nai)熱(re)(re)，有(you)些(xie)(xie)不耐(nai)熱(re)(re);有(you)些(xie)(xie)耐(nai)酸，有(you)些(xie)(xie)耐(nai)堿，有(you)些(xie)(xie)耐(nai)水，有(you)些(xie)(xie)耐(nai)油(you)(you);有(you)些(xie)(xie)抗熱(re)(re)，有(you)些(xie)(xie)耐(nai)低(di)溫，有(you)些(xie)(xie)耐(nai)高(gao)溫，等(deng)(deng)等(deng)(deng)。這些(xie)(xie)因素(su)在考慮密(mi)封(feng)(feng)件(jian)(jian)材(cai)(cai)料(liao)的(de)(de)時(shi)候需(xu)注意(yi)。