箱體零件加工概述1箱體零件的功用與結構特點箱體是機器的基礎零件，它將機器中有關部件的軸、套、齒輪等相關零件連接成一個整體，并使之保持正確的相互位置，以傳遞轉矩或改變轉速來完成規定的運動。故箱體的加工質量，直接影響到機器的性能、精度和壽命。箱體類零件的結構復雜，壁薄且不均勻，加工部位多，加工難度大。據統計資料表明，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品加工工時的l520。2箱體零件的主要技術要求箱體類零件中，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。孔徑過大，配合過松，使主軸回轉軸線不穩定，并降低了支承剛度，易產生振動和噪聲；孔徑太小，會使配合偏緊，軸承將因外環變形，不能正常運轉而縮短壽命。裝軸承的孔不圓，也會使軸承外環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。孔的幾何形狀精度未作規定的，一般控制在尺寸公差的12范圍內即可。孔與孔的位置精度：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出現歪斜，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。孔和平面的位置精度：主要孔對主軸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，還規定了頂面的平面度要求，當大批量生產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構的。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