1、液(ye)壓密(mi)封(feng)件之形式選擇

　　在液壓系統中，常見的(de)密(mi)封(feng)形式有(you)擠壓型O形密(mi)封(feng)圈(quan)、Y形圈(quan)、V形圈(quan)、U形圈(quan)唇(chun)形密(mi)封(feng)。唇(chun)形密(mi)封(feng)圈(quan)主要用于往(wang)復動密(mi)封(feng)，與(yu)O形圈(quan)等擠壓密(mi)封(feng)相比(bi)，往(wang)復動密(mi)封(feng)使(shi)用唇(chun)形密(mi)封(feng)圈(quan)具(ju)有(you)更好的(de)綜合(he)性能和更長的(de)使(shi)用壽(shou)命(ming)。

　　唇形密(mi)(mi)(mi)(mi)封(feng)圈(quan)(quan)的(de)密(mi)(mi)(mi)(mi)封(feng)壓緊(jin)(jin)(jin)力(li)(li)(li)是(shi)隨介質壓力(li)(li)(li)的(de)改(gai)變(bian)而(er)變(bian)化的(de)，工(gong)作中(zhong)始終(zhong)應監(jian)控介質壓力(li)(li)(li)的(de)變(bian)化，即能保(bao)證足夠(gou)的(de)密(mi)(mi)(mi)(mi)封(feng)壓緊(jin)(jin)(jin)力(li)(li)(li)，又不至(zhi)于產(chan)生(sheng)過大(da)(da)的(de)摩(mo)擦(ca)力(li)(li)(li)，擠(ji)壓性密(mi)(mi)(mi)(mi)封(feng)主(zhu)要靠預壓緊(jin)(jin)(jin)力(li)(li)(li)產(chan)生(sheng)密(mi)(mi)(mi)(mi)封(feng)力(li)(li)(li)，密(mi)(mi)(mi)(mi)封(feng)圈(quan)(quan)接(jie)(jie)觸壓力(li)(li)(li)預先給定，工(gong)作中(zhong)不能根據介質壓力(li)(li)(li)的(de)改(gai)變(bian)而(er)變(bian)化。大(da)(da)的(de)預壓力(li)(li)(li)會使密(mi)(mi)(mi)(mi)封(feng)圈(quan)(quan)與密(mi)(mi)(mi)(mi)封(feng)面接(jie)(jie)觸面積增大(da)(da)，產(chan)生(sheng)很大(da)(da)的(de)摩(mo)擦(ca)阻力(li)(li)(li)，過大(da)(da)的(de)摩(mo)擦(ca)力(li)(li)(li)會造成密(mi)(mi)(mi)(mi)封(feng)圈(quan)(quan)的(de)破損，在低壓時(shi)造成啟動困難(nan)，或產(chan)生(sheng)爬行現(xian)象，唇形密(mi)(mi)(mi)(mi)封(feng)圈(quan)(quan)可以通過唇部(bu)撐(cheng)開(kai)，變(bian)形補(bu)償小的(de)磨(mo)損量(liang)，保(bao)證密(mi)(mi)(mi)(mi)封(feng)效果和(he)密(mi)(mi)(mi)(mi)封(feng)壽命;而(er)O形圈(quan)(quan)隨著摩(mo)擦(ca)余量(liang)的(de)減少，直接(jie)(jie)影響其(qi)密(mi)(mi)(mi)(mi)封(feng)性。

　　2、液壓密封件(jian)之材料選(xuan)擇

　　密封(feng)(feng)(feng)件形式和(he)結構現在(zai)(zai)一般已經定型(xing)，各密封(feng)(feng)(feng)件質(zhi)(zhi)量(liang)區別主(zhu)要(yao)(yao)在(zai)(zai)于制(zhi)作材料(liao)(liao)上(shang)。密封(feng)(feng)(feng)材料(liao)(liao)主(zhu)要(yao)(yao)使用(yong)(yong)(yong)橡(xiang)膠和(he)合(he)成樹脂。由于各種材料(liao)(liao)性(xing)(xing)能特點(dian)不(bu)同(tong)(tong)(tong)，性(xing)(xing)能特點(dian)不(bu)同(tong)(tong)(tong)，用(yong)(yong)(yong)途也(ye)就(jiu)有(you)所不(bu)同(tong)(tong)(tong)。選用(yong)(yong)(yong)時(shi)需根據不(bu)同(tong)(tong)(tong)的使用(yong)(yong)(yong)條件和(he)不(bu)同(tong)(tong)(tong)的使用(yong)(yong)(yong)條件作出合(he)適的選擇。另(ling)外，某(mou)一材質(zhi)(zhi)的密封(feng)(feng)(feng)對(dui)被密封(feng)(feng)(feng)的某(mou)一工(gong)作介質(zhi)(zhi)(如礦物油(you)等)表現較好的密封(feng)(feng)(feng)性(xing)(xing)能，而對(dui)另(ling)一介質(zhi)(zhi)表現極差(cha)，這(zhe)就(jiu)是密封(feng)(feng)(feng)材料(liao)(liao)與液壓油(you)的相容性(xing)(xing)。還有(you)，各種不(bu)同(tong)(tong)(tong)的密封(feng)(feng)(feng)材料(liao)(liao)對(dui)你(ni)不(bu)同(tong)(tong)(tong)的工(gong)作條件表現出不(bu)同(tong)(tong)(tong)的性(xing)(xing)能。有(you)些(xie)耐(nai)熱，有(you)些(xie)不(bu)耐(nai)熱;有(you)些(xie)耐(nai)酸(suan)，有(you)些(xie)耐(nai)堿，有(you)些(xie)耐(nai)水(shui)，有(you)些(xie)耐(nai)油(you);有(you)些(xie)抗(kang)熱，有(you)些(xie)耐(nai)低溫，有(you)些(xie)耐(nai)高溫，等等。這(zhe)些(xie)因(yin)素(su)在(zai)(zai)考慮密封(feng)(feng)(feng)件材料(liao)(liao)的時(shi)候需注意。