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發布時間:2021-12-10 15:52:26 人氣:127985 來源:
填(tian)(tian)(tian)(tian)料改集(ji)式密(mi)(mi)(mi)封是指(zhi)通過預(yu)(yu)緊(jin)(jin)或介質(zhi)壓力的(de)自(zi)緊(jin)(jin)作(zuo)用(yong)(yong)使(shi)填(tian)(tian)(tian)(tian)料與轉(zhuan)動(dong)件(jian)及固定(ding)件(jian)之(zhi)間產(chan)生(sheng)壓緊(jin)(jin)力的(de)動(dong)密(mi)(mi)(mi)封裝置(zhi)。又(you)稱(cheng)“填(tian)(tian)(tian)(tian)料函(han)密(mi)(mi)(mi)封”。結(jie)構(gou)形(xing)式較多,主(zhu)要(yao)由(you)填(tian)(tian)(tian)(tian)料、填(tian)(tian)(tian)(tian)料箱(xiang)和填(tian)(tian)(tian)(tian)料固定(ding)件(jian)組成。常(chang)用(yong)(yong)的(de)填(tian)(tian)(tian)(tian)料材料有(you)石棉織物、碳纖(xian)維、橡(xiang)膠、柔性石墨和工程塑料等,預(yu)(yu)制成環狀或條狀(有(you)的(de)需預(yu)(yu)先浸漬潤(run)滑(hua)性好的(de)填(tian)(tian)(tian)(tian)充物),并采用(yong)(yong)多環或螺(luo)旋狀多層(ceng)結(jie)構(gou)。填(tian)(tian)(tian)(tian)料箱(xiang)用(yong)(yong)以(yi)安置(zhi)填(tian)(tian)(tian)(tian)料。填(tian)(tian)(tian)(tian)料固定(ding)件(jian)包括壓蓋、螺(luo)栓和彈簧(huang)等,用(yong)(yong)以(yi)使(shi)填(tian)(tian)(tian)(tian)料預(yu)(yu)緊(jin)(jin),工作(zuo)時(shi)阻止介質(zhi)外漏,彈簧(huang)可(ke)起(qi)補(bu)償作(zuo)用(yong)(yong)。
填(tian)(tian)(tian)料(liao)裝入填(tian)(tian)(tian)料(liao)腔(qiang)以后,經壓(ya)蓋螺絲對它作軸向(xiang)壓(ya)縮,當軸與填(tian)(tian)(tian)料(liao)有(you)相對運動時,由于(yu)(yu)填(tian)(tian)(tian)料(liao)的(de)塑(su)性,使它產生徑向(xiang)力,并與軸緊(jin)密(mi)接(jie)(jie)觸(chu)(chu)。與此同(tong)時,填(tian)(tian)(tian)料(liao)中(zhong)浸漬的(de)潤(run)滑(hua)劑被擠出(chu)(chu),在(zai)接(jie)(jie)觸(chu)(chu)面之(zhi)間形成(cheng)油膜。由于(yu)(yu)接(jie)(jie)觸(chu)(chu)狀態(tai)(tai)并不(bu)是(shi)特(te)別均勻(yun)的(de),接(jie)(jie)觸(chu)(chu)部(bu)位(wei)(wei)便出(chu)(chu)現“邊界潤(run)滑(hua)”狀態(tai)(tai),稱為“軸承效(xiao)(xiao)(xiao)應(ying)(ying)”;而(er)未(wei)接(jie)(jie)觸(chu)(chu)的(de)凹部(bu)形成(cheng)小(xiao)油槽,有(you)較厚的(de)油膜,接(jie)(jie)觸(chu)(chu)部(bu)位(wei)(wei)與非接(jie)(jie)觸(chu)(chu)部(bu)位(wei)(wei)組成(cheng)一道不(bu)規(gui)則的(de)迷宮(gong),起(qi)阻(zu)止液流(liu)泄(xie)漏的(de)作用,此稱“迷宮(gong)效(xiao)(xiao)(xiao)應(ying)(ying)”。這(zhe)就是(shi)填(tian)(tian)(tian)料(liao)密(mi)封(feng)的(de)機理(li)。顯然(ran),良(liang)好的(de)密(mi)封(feng)在(zai)于(yu)(yu)維持(chi)“軸承效(xiao)(xiao)(xiao)應(ying)(ying)”和“迷宮(gong)效(xiao)(xiao)(xiao)應(ying)(ying)”。也就是(shi)說(shuo),要保(bao)持(chi)良(liang)好的(de)潤(run)滑(hua)和適當的(de)壓(ya)緊(jin)。若潤(run)滑(hua)不(bu)良(liang),或壓(ya)得過緊(jin)都會使油膜中(zhong)斷,造成(cheng)填(tian)(tian)(tian)料(liao)與軸之(zhi)間出(chu)(chu)現干摩擦,最后導(dao)致燒軸和出(chu)(chu)現嚴重磨損(sun)。
為(wei)此,需要(yao)經常(chang)對(dui)填料(liao)(liao)的(de)(de)壓緊程(cheng)度進行調整,以便填料(liao)(liao)中的(de)(de)潤滑劑在運(yun)行一段時間流(liu)失(shi)之后(hou),再擠(ji)出一些(xie)潤滑劑,同時補償填料(liao)(liao)因體(ti)積變化所造成的(de)(de)壓緊力(li)松弛。顯然,這樣經常(chang)擠(ji)壓填料(liao)(liao),最終將使浸漬劑枯竭,所以定期(qi)更換填料(liao)(liao)是(shi)必(bi)要(yao)的(de)(de)。此外,為(wei)了(le)維持液膜和(he)帶走摩擦熱,有意讓填料(liao)(liao)處(chu)有少量泄漏也(ye)是(shi)必(bi)要(yao)的(de)(de)。