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)液(ye)壓(ya)(ya)(ya)設備停止工(gong)作(zuo)一(yi)段時(shi)(shi)(shi)間后(hou),油(you)(you)(you)(you)(you)壓(ya)(ya)(ya)系統(tong)(tong)中的(de)(de)(de)油(you)(you)(you)(you)(you)液(ye)依靠自重返回油(you)(you)(you)(you)(you)箱。同(tong)時(shi)(shi)(shi),因為系統(tong)(tong)密(mi)封裝置(zhi)有(you)間隙,空氣(qi)即由(you)此進入(ru)系統(tong)(tong)。當(dang)鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)再次啟動(dong)(dong)(dong)(dong)時(shi)(shi)(shi),需要(yao)克(ke)服鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)與(yu)導軌(gui)之間較大(da)的(de)(de)(de)靜摩(mo)(mo)(mo)擦阻力(靜摩(mo)(mo)(mo)擦阻力比動(dong)(dong)(dong)(dong)摩(mo)(mo)(mo)擦阻力大(da)得(de)多,有(you)時(shi)(shi)(shi)可能大(da)一(yi)倍)。因而(er),液(ye)壓(ya)(ya)(ya)系統(tong)(tong)油(you)(you)(you)(you)(you)壓(ya)(ya)(ya)達(da)到能克(ke)服鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)阻力的(de)(de)(de)壓(ya)(ya)(ya)力,鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)才(cai)能移(yi)動(dong)(dong)(dong)(dong),但因進油(you)(you)(you)(you)(you)腔中的(de)(de)(de)空氣(qi)在鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)移(yi)動(dong)(dong)(dong)(dong)時(shi)(shi)(shi)被壓(ya)(ya)(ya)縮(suo),鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)開始(shi)移(yi)動(dong)(dong)(dong)(dong)后(hou)由(you)于油(you)(you)(you)(you)(you)壓(ya)(ya)(ya)減低(di)又突然膨脹(油(you)(you)(you)(you)(you)壓(ya)(ya)(ya)降低(di)是因凈摩(mo)(mo)(mo)擦變為動(dong)(dong)(dong)(dong)摩(mo)(mo)(mo)擦)而(er)使鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)產(chan)生沖擊運動(dong)(dong)(dong)(dong),此時(shi)(shi)(shi),排油(you)(you)(you)(you)(you)箱內(nei)(nei)的(de)(de)(de)空氣(qi)被突然壓(ya)(ya)(ya)縮(suo),使反(fan)阻力加大(da),在兩邊壓(ya)(ya)(ya)力平(ping)(ping)(ping)衡(heng)時(shi)(shi)(shi)鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)—突然停頓。當(dang)壓(ya)(ya)(ya)油(you)(you)(you)(you)(you)腔內(nei)(nei)的(de)(de)(de)油(you)(you)(you)(you)(you)壓(ya)(ya)(ya)再恢(hui)復(fu)到能夠(gou)克(ke)服靜摩(mo)(mo)(mo)擦阻力時(shi)(shi)(shi),鑄(zhu)鐵(tie)平(ping)(ping)(ping)板(ban)(ban)工(gong)作(zuo)臺(tai)(tai)作(zuo)如前所述的(de)(de)(de)循環(huan)過程(cheng),也 是—斷續地直線(xian)運動(dong)(dong)(dong)(dong),亦即一(yi)般說的(de)(de)(de)“爬行”。其周期循環(huan)。
(2)磨床導(dao)(dao)軌(gui)(gui)(gui)一般采用(yong)V形和(he)平(ping)面(mian)導(dao)(dao)軌(gui)(gui)(gui)結(jie)合的(de)形式(shi),V形導(dao)(dao)軌(gui)(gui)(gui)保證鑄(zhu)鐵平(ping)板(ban)工(gong)作臺(tai)(tai)在水平(ping)平(ping)面(mian)內的(de)直線度(du),平(ping)面(mian)導(dao)(dao)軌(gui)(gui)(gui)保證其(qi)在垂直平(ping)面(mian)上的(de)直線度(du),兩條導(dao)(dao)軌(gui)(gui)(gui)組(zu)合一起,要求(qiu)相互(hu)平(ping)行度(du)很高(gao),導(dao)(dao)軌(gui)(gui)(gui)扭(niu)曲度(du)也高(gao)。如導(dao)(dao)軌(gui)(gui)(gui)相互(hu)平(ping)行度(du)和(he)扭(niu)曲度(du)太大(da)或在各段變(bian)化較大(da),即使鑄(zhu)鐵平(ping)板(ban)工(gong)作臺(tai)(tai)移動時(shi)(shi)所克服的(de)阻力不斷變(bian)化,而(er)工(gong)作油箱中的(de)油壓不能適應其(qi)變(bian)化,故(gu)鑄(zhu)鐵平(ping)臺(tai)(tai)工(gong)作臺(tai)(tai) 形成時(shi)(shi)快時(shi)(shi)慢的(de)不連(lian)續運動。
(3)如果液壓缸(gang)的圓度(du)(du)在全(quan)長上(shang)各處(chu)變化(hua)(hua)較大,則活(huo)塞(sai)與液壓缸(gang)之(zhi)間隙(xi)大小不均,相應的摩(mo)擦(ca)力亦發生變化(hua)(hua),而使鑄鐵平板(ban)鑄鐵平板(ban)工作臺(tai)運動速度(du)(du)隨著變化(hua)(hua)。另外,活(huo)塞(sai)桿彎曲(qu),在其移動時(shi)與密(mi)封(feng)圈的摩(mo)擦(ca)力經常變化(hua)(hua),也(ye)是產生爬行的原(yuan)因之(zhi)一。
(4)實(shi)際上磨床工(gong)作(zuo)時因為磨削面產生的阻力其微小(xiao),鉗工(gong)平(ping)板工(gong)作(zuo)臺(tai)(tai)運(yun)動是否輕便主要決(jue)定于導(dao)(dao)軌與鑄(zhu)鐵平(ping)板工(gong)作(zuo)臺(tai)(tai)之間摩擦(ca)情況,一般要求兩滑動導(dao)(dao)軌而應生成(cheng)一層(ceng)油膜(mo),并(bing)保持其厚度在0.005~0.008mm為宜(yi),不應太厚,否則,影(ying)響(xiang)加工(gong)度。
磨(mo)床軌道(dao)潤滑油(you)注油(you)方式有(you)兩(liang)種:一(yi)種是(shi)間隙注油(you),即鑄鐵平板工作(zuo)臺(tai)往復一(yi)次(ci)壓入(ru)潤滑油(you)一(yi)次(ci)另一(yi)種是(shi)連續注油(you),即當(dang)鑄鐵平板工作(zuo)臺(tai)開動時,任何時候(hou)都有(you)潤滑油(you)壓入(ru)兩(liang)滑動面間。
后(hou)一種可保(bao)證充(chong)分潤滑,采(cai)用較(jiao)為普(pu)遍。如果潤滑不(bu)好,造(zao)成阻(zu)力不(bu)均勻,同樣也(ye)是產生爬行(xing)的原因之一。
(5)通(tong)(tong)常在液(ye)(ye)壓(ya)泵(beng)進油口(kou)裝有(you)過濾器,應(ying)保證油液(ye)(ye)有(you)足夠的(de)通(tong)(tong)過量(liang)(liang),網(wang)(wang)孔(kong)不能過小(xiao),如(ru)網(wang)(wang)孔(kong)太小(xiao), 易被雜質堵(du)塞。當液(ye)(ye)壓(ya)泵(beng)運轉時(shi)則(ze)在吸油管(guan)中形(xing)成真空(kong),而使部分油蒸發,形(xing)成“油蒸氣(qi)(qi)”,亦可使溶解于(yu)油中的(de)小(xiao)部分空(kong)氣(qi)(qi)分離(li)出來,同時(shi)在液(ye)(ye)壓(ya)泵(beng)密(mi)封處吸入(ru)大量(liang)(liang)空(kong)氣(qi)(qi),當“油蒸氣(qi)(qi)”及空(kong)氣(qi)(qi)進入(ru)液(ye)(ye)壓(ya)缸,即會(hui)(hui)發生(sheng)爬行現(xian)象。同樣道理,進油口(kou)直徑過細,亦應(ying)保證液(ye)(ye)壓(ya)泵(beng)所需油量(liang)(liang)通(tong)(tong)過,吸油管(guan)口(kou)與(yu)過濾網(wang)(wang)底(di)(di)部保持相當距(ju)離(li)(一般在50mm左右)如(ru)油管(guan)直徑小(xiao)或管(guan)口(kou)與(yu)網(wang)(wang)底(di)(di)距(ju)離(li)太近,亦會(hui)(hui)在液(ye)(ye)壓(ya)泵(beng)中造成真空(kong)現(xian)象。
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