箱體零件加工概述1箱體零件的功用與結(jié)構(gòu)特點箱體是機器的基礎(chǔ)零件，它將機器中有關(guān)部件的軸、套、齒輪等相關(guān)零件連接成一個整體，并使之保持正確的相互位置，以傳遞轉(zhuǎn)矩或改變轉(zhuǎn)速來完成規(guī)定的運動。故箱體的加工質(zhì)量，直接影響到機器的性能、精度和壽命。箱體類零件的結(jié)構(gòu)復雜，壁薄且不均勻，加工部位多，加工難度大。據(jù)統(tǒng)計資料表明，一般中型機床制造廠花在箱體類零件的機械加工工時約占整個產(chǎn)品加工工時的l520。2箱體零件的主要技術(shù)要求箱體類零件中，機床主軸箱的精度要求較高，可歸納為以下五項精度要求：孔徑精度：孔徑的尺寸誤差和幾何形狀誤差會造成軸承與孔的配合不良?？讖竭^大，配合過松，使主軸回轉(zhuǎn)軸線不穩(wěn)定，并降低了支承剛度，易產(chǎn)生振動和噪聲；孔徑太小，會使配合偏緊，軸承將因外環(huán)變形，不能正常運轉(zhuǎn)而縮短壽命。裝軸承的孔不圓，也會使軸承外環(huán)變形而引起主軸徑向圓跳動。從上面分析可知，對孔的精度要求是較高的。主軸孔的尺寸公差等級為IT6，其余孔為IT8IT7?？椎膸缀涡螤罹任醋饕?guī)定的，一般控制在尺寸公差的12范圍內(nèi)即可?？着c孔的位置精度：同一軸線上各孔的同軸度誤差和孔端面對軸線的垂直度誤差，會使軸和軸承裝配到箱體內(nèi)出現(xiàn)歪斜，從而造成主軸徑向圓跳動和軸向竄動，也加劇了軸承磨損。孔系之間的平行度誤差，會影響齒輪的嚙合質(zhì)量。一般孔距允差為土0.025土0.060mm，而同一中心線上的支承孔的同軸度約為最小孔尺寸公差之半?？缀推矫娴奈恢镁龋褐饕讓χ鬏S箱安裝基面的平行度，決定了主軸與床身導軌的相互位置關(guān)系。這項精度是在總裝時通過刮研來達到的。為了減少刮研工作量，一般規(guī)定在垂直和水平兩個方向上，只允許主軸前端向上和向前偏。主要平面的精度：裝配基面的平面度影響主軸箱與床身連接時的接觸剛度，加工過程中作為定位基面則會影響主要孔的加工精度。因此規(guī)定了底面和導向面必須平直，為了保證箱蓋的密封性，防止工作時潤滑油泄出，還規(guī)定了頂面的平面度要求，當大批量生產(chǎn)將其頂面用作定位基面時，對它的平面度要求還要提高。表面粗糙度：一般主軸孔的表面粗糙度為Ra0.4m，其它各縱向孔的表面粗糙度為Ra1.6m；孔的內(nèi)端面的表面粗糙度為Ra3.2m，裝配基準面和定位基準面的表面粗糙度為Ra2.50.63m，其它平面的表面粗糙度為Ra102.5m。3箱體零件的材料及毛坯箱體零件材料常選用各種牌號的灰鑄鐵，因為灰鑄鐵具有較好的耐磨性、鑄造性和可切削性，而且吸振性好,成本又低。某些負荷較大的箱體采用鑄鋼件。也有某些簡易箱體為了縮短毛坯制造的周期而采用鋼板焊接結(jié)構(gòu)的。Processingoutlinedinbodyparts1boxofthefunctionofpartsandstructuralfeaturesBoxisthebasisofmachineparts,itwillmachinetheaxisofthecomponents,kits,gearandotherrelatedpartsintoawhole,andeachothertomaintainthecorrectpositiontotransmittorqueortochangethespeedtocompletethemovement.Therefore,thequalityoftheprocessingtank,adirectimpactonmachineperformance,accuracyandlifeexpectancy.Box-typepartsofthestructureofcomplexthin-walledandnon-uniform,multi-siteprocessing,processingisdifficult.Accordingtostatistics,thegeneralmedium-sizedbox-typemachinetoolfactorypartsonmachiningtimeprocessingthewholetimeaboutthel5%20%.2BoxofthemaintechnicalrequirementsofpartsBox-typeparts,themachinetoolspindleboxhigheraccuracycanbesummedupintheaccuracyofthefollowingfiverequirements:precisionaperture:aperturesizeandgeometryoferrorswillcauseerrorswiththebearingandtheholebad.Apertureistoolarge,withtooloose,sothattheaxisspindleinstability,andreducethebearingstiffnessandeasytoproducevibrationandnoise；apertureistoosmall,willtieinwiththetight,thebearingsouterringwillbedeformedandcannotshortenthelifeofthenormaloperationof.Notloadedbearingaroundhole,therewillbeouterbearingspindleradialdeformationcausedbyaroundbeating.Fromtheaboveanalysiswecanseethattheprecisionoftheholeishigher.SpindleholesizetolerancelevelforIT6,theremainingholesfortheIT8IT7.Holegeometryaccuracynotprovidedforthegeneralcontrolofthedimensionaltolerancesof1/2canbewithinthescope.holewiththeholelocationaccuracy:thesameaxisoftheholecoaxialitythefaceoferrorandthemicropylarendoftheverticalaxiserror,shaftandbearingassemblywillappeartoskew,resultinginbeatingroundthemainaxisofradialandaxialrockyledge,butalsoexacerbatedthebearingwear.Holesinparallelbetweenthedegreeoferrorwillaffectthequalityofthemeshinggears.DistanceToleranceforthegeneralsoilsoil0.0250.060mm,andthesameonlinesupportcentercoaxialityholeaboutthesizetoleranceofthesemi-holes.holeandtwo-dimensionalpositionalaccuracy:themainholeofthespindleboxisinstalledparalleltothebasesurface,thedecisionofthemainrailandbedpositionofmutualrelations.TheaccuracyadoptedintheassemblytoachievetheInstitutescratch.Scratchinordertoreducetheworkloadstudy,thegeneralprovisionsintheverticalandhorizontaldirections,allowingonlythefrontspindleupwardandforwardbias.Theaccuracyofthemainplane:Assembly-basedsurfaceflatnessoftheimpactofbedspindleboxandconnectthecontactstiffness,asaprocessingbaselocationwillaffectthemachiningaccuracyofthemainhole.Thereforetheprovisionsofthebottomsurfacemustbeflatandoriented,inordertoensurethesealingcovertopreventoilleakwork,butalsoprovidesthetopoftheflatnessrequirement,whenthehigh-volumeproductionofitstopsurfaceforpositioningthebasesurfacewhenitalsotoimprovetheflatnessrequirements.surfaceroughness:generalspindleholeforthesurfaceroughnessRa0.4m,otherverticalholeforthesurfaceroughnessRa1.6m；holeinthesurfaceroughnessforendRa3.2m,assemblyandpositioningofbase-leveldatumThesurfaceroughnessforRa2.50.63m,theotherfortwo-dimensionalsurfaceroughnessRa102.5m.3boxofmaterialsandroughpartsBodypartsoftenchooseavarietyofmaterialgradesofgraycastiron,asgra