磨床使用鑄鐵平板工作臺時導致運動不均勻的原因是哪些?
2017年09月11日
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在現代機械制造工業企業的生產中,由于產品品種的增加,質量的提高,作為jingmi加工工藝裝備的磨床所占比重也較大。因而,磨削設備的正常運行,對保證完成生產任務有著其重要的作用,液壓傳動磨床鑄鐵平板/鑄鐵平臺工作臺運動( 別是在低速運轉時)不均勻現象產生的原因如下。
(1)當(dang)(dang)液(ye)壓(ya)(ya)(ya)(ya)設備停止(zhi)工(gong)(gong)作(zuo)一(yi)(yi)段時間(jian)(jian)后,油(you)壓(ya)(ya)(ya)(ya)系(xi)(xi)(xi)統中的(de)油(you)液(ye)依(yi)靠自重(zhong)返回油(you)箱(xiang)。同時,因(yin)為系(xi)(xi)(xi)統密封裝置有間(jian)(jian)隙,空(kong)氣(qi)即由(you)(you)此進入系(xi)(xi)(xi)統。當(dang)(dang)鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺再次啟(qi)動(dong)(dong)(dong)時,需要克(ke)(ke)服鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺與導(dao)軌之間(jian)(jian)較大(da)的(de)靜(jing)摩(mo)擦阻力(li)(靜(jing)摩(mo)擦阻力(li)比(bi)動(dong)(dong)(dong)摩(mo)擦阻力(li)大(da)得(de)多,有時可能(neng)大(da)一(yi)(yi)倍)。因(yin)而(er),液(ye)壓(ya)(ya)(ya)(ya)系(xi)(xi)(xi)統油(you)壓(ya)(ya)(ya)(ya)達到能(neng)克(ke)(ke)服鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺阻力(li)的(de)壓(ya)(ya)(ya)(ya)力(li),鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺才能(neng)移動(dong)(dong)(dong),但因(yin)進油(you)腔(qiang)(qiang)中的(de)空(kong)氣(qi)在鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺移動(dong)(dong)(dong)時被(bei)壓(ya)(ya)(ya)(ya)縮(suo),鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺開始(shi)移動(dong)(dong)(dong)后由(you)(you)于油(you)壓(ya)(ya)(ya)(ya)減低(di)又突然膨脹(油(you)壓(ya)(ya)(ya)(ya)降(jiang)低(di)是因(yin)凈摩(mo)擦變為動(dong)(dong)(dong)摩(mo)擦)而(er)使鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺產生沖擊運(yun)動(dong)(dong)(dong),此時,排油(you)箱(xiang)內的(de)空(kong)氣(qi)被(bei)突然壓(ya)(ya)(ya)(ya)縮(suo),使反阻力(li)加大(da),在兩邊壓(ya)(ya)(ya)(ya)力(li)平(ping)衡(heng)時鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺—突然停頓。當(dang)(dang)壓(ya)(ya)(ya)(ya)油(you)腔(qiang)(qiang)內的(de)油(you)壓(ya)(ya)(ya)(ya)再恢復到能(neng)夠克(ke)(ke)服靜(jing)摩(mo)擦阻力(li)時,鑄(zhu)(zhu)鐵(tie)(tie)(tie)(tie)平(ping)板(ban)工(gong)(gong)作(zuo)臺作(zuo)如前所述的(de)循(xun)環過程,也 是—斷(duan)續地直線運(yun)動(dong)(dong)(dong),亦(yi)即一(yi)(yi)般說的(de)“爬(pa)行”。其周期循(xun)環。
(2)磨床導(dao)軌(gui)一般采用V形和平(ping)(ping)面導(dao)軌(gui)結(jie)合的(de)形式,V形導(dao)軌(gui)保(bao)(bao)證鑄鐵平(ping)(ping)板工作(zuo)臺(tai)在(zai)水平(ping)(ping)平(ping)(ping)面內(nei)的(de)直(zhi)線(xian)(xian)度(du),平(ping)(ping)面導(dao)軌(gui)保(bao)(bao)證其在(zai)垂(chui)直(zhi)平(ping)(ping)面上的(de)直(zhi)線(xian)(xian)度(du),兩(liang)條導(dao)軌(gui)組合一起,要求相互(hu)平(ping)(ping)行度(du)很高,導(dao)軌(gui)扭(niu)曲(qu)(qu)度(du)也(ye)高。如導(dao)軌(gui)相互(hu)平(ping)(ping)行度(du)和扭(niu)曲(qu)(qu)度(du)太大或在(zai)各段變化較大,即使(shi)鑄鐵平(ping)(ping)板工作(zuo)臺(tai)移動時(shi)所克服的(de)阻力(li)不斷變化,而工作(zuo)油箱中的(de)油壓不能適(shi)應其變化,故鑄鐵平(ping)(ping)臺(tai)工作(zuo)臺(tai) 形成時(shi)快時(shi)慢(man)的(de)不連(lian)續運動。
(3)如果液壓缸(gang)的(de)圓(yuan)度在全長(chang)上各處(chu)變化較大,則活塞與液壓缸(gang)之(zhi)(zhi)間隙(xi)大小不(bu)均,相應的(de)摩(mo)擦(ca)力亦(yi)發生(sheng)變化,而(er)使鑄鐵平板鑄鐵平板工作(zuo)臺運動(dong)(dong)速度隨著變化。另外,活塞桿彎(wan)曲,在其移動(dong)(dong)時與密封(feng)圈的(de)摩(mo)擦(ca)力經(jing)常變化,也是(shi)產生(sheng)爬行的(de)原因之(zhi)(zhi)一。
(4)實際(ji)上磨床工(gong)(gong)作(zuo)時(shi)因(yin)為(wei)磨削面產(chan)生(sheng)的阻(zu)力其(qi)微(wei)小,鉗工(gong)(gong)平板工(gong)(gong)作(zuo)臺運(yun)動是否輕便主要決定于(yu)導(dao)軌與鑄鐵平板工(gong)(gong)作(zuo)臺之間摩擦情(qing)況,一(yi)般要求兩(liang)滑動導(dao)軌而(er)應(ying)生(sheng)成一(yi)層油膜,并保(bao)持其(qi)厚(hou)度(du)在(zai)0.005~0.008mm為(wei)宜(yi),不應(ying)太厚(hou),否則,影響加工(gong)(gong)度(du)。
磨(mo)床軌道潤(run)滑(hua)(hua)油注油方式(shi)有兩種(zhong):一(yi)種(zhong)是間(jian)隙注油,即鑄(zhu)鐵平(ping)板工作(zuo)臺往復(fu)一(yi)次壓入潤(run)滑(hua)(hua)油一(yi)次另(ling)一(yi)種(zhong)是連續注油,即當鑄(zhu)鐵平(ping)板工作(zuo)臺開動時(shi),任(ren)何時(shi)候都有潤(run)滑(hua)(hua)油壓入兩滑(hua)(hua)動面間(jian)。
后一種(zhong)可保(bao)證充分潤滑,采用較為普遍。如果(guo)潤滑不好,造成(cheng)阻力不均勻,同樣也是產(chan)生(sheng)爬行(xing)的原因之一。
(5)通常(chang)在(zai)液(ye)壓(ya)(ya)泵(beng)(beng)(beng)進(jin)油(you)(you)口裝有(you)過(guo)(guo)(guo)濾(lv)器,應(ying)保(bao)證(zheng)油(you)(you)液(ye)有(you)足夠的(de)通過(guo)(guo)(guo)量,網(wang)孔不能(neng)過(guo)(guo)(guo)小(xiao)(xiao),如網(wang)孔太(tai)小(xiao)(xiao), 易被雜質堵塞。當(dang)液(ye)壓(ya)(ya)泵(beng)(beng)(beng)運轉時(shi)則在(zai)吸(xi)油(you)(you)管中形(xing)成真空(kong)(kong),而(er)使部(bu)(bu)分(fen)油(you)(you)蒸發,形(xing)成“油(you)(you)蒸氣(qi)”,亦可使溶(rong)解于油(you)(you)中的(de)小(xiao)(xiao)部(bu)(bu)分(fen)空(kong)(kong)氣(qi)分(fen)離(li)出來,同時(shi)在(zai)液(ye)壓(ya)(ya)泵(beng)(beng)(beng)密封處吸(xi)入(ru)大量空(kong)(kong)氣(qi),當(dang)“油(you)(you)蒸氣(qi)”及空(kong)(kong)氣(qi)進(jin)入(ru)液(ye)壓(ya)(ya)缸,即會(hui)(hui)發生爬行現象(xiang)。同樣道理,進(jin)油(you)(you)口直徑過(guo)(guo)(guo)細,亦應(ying)保(bao)證(zheng)液(ye)壓(ya)(ya)泵(beng)(beng)(beng)所需油(you)(you)量通過(guo)(guo)(guo),吸(xi)油(you)(you)管口與過(guo)(guo)(guo)濾(lv)網(wang)底部(bu)(bu)保(bao)持相當(dang)距離(li)(一般在(zai)50mm左右)如油(you)(you)管直徑小(xiao)(xiao)或(huo)管口與網(wang)底距離(li)太(tai)近(jin),亦會(hui)(hui)在(zai)液(ye)壓(ya)(ya)泵(beng)(beng)(beng)中造成真空(kong)(kong)現象(xiang)。
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