机械外文翻译--箱体零件加工概述.doc

箱体零件加工概述1箱体零件的功用与结构特点箱体是机器的基础零件，它将机器中有关部件的轴、套、齿轮等相关零件连接成一个整体，并使之保持正确的相互位置，以传递转矩或改变转速来完成规定的运动。故箱体的加工质量，直接影响到机器的性能、精度和寿命。箱体类零件的结构复杂，壁薄且不均匀，加工部位多，加工难度大。据统计资料表明，一般中型机床制造厂花在箱体类零件的机械加工工时约占整个产品加工工时的l520。2箱体零件的主要技术要求箱体类零件中，机床主轴箱的精度要求较高，可归纳为以下五项精度要求：孔径精度：孔径的尺寸误差和几何形状误差会造成轴承与孔的配合不良。孔径过大，配合过松，使主轴回转轴线不稳定，并降低了支承刚度，易产生振动和噪声；孔径太小，会使配合偏紧，轴承将因外环变形，不能正常运转而缩短寿命。装轴承的孔不圆，也会使轴承外环变形而引起主轴径向圆跳动。从上面分析可知，对孔的精度要求是较高的。主轴孔的尺寸公差等级为IT6，其余孔为IT8IT7。孔的几何形状精度未作规定的，一般控制在尺寸公差的12范围内即可。孔与孔的位置精度：同一轴线上各孔的同轴度误差和孔端面对轴线的垂直度误差，会使轴和轴承装配到箱体内出现歪斜，从而造成主轴径向圆跳动和轴向窜动，也加剧了轴承磨损。孔系之间的平行度误差，会影响齿轮的啮合质量。一般孔距允差为土0.025土0.060mm，而同一中心线上的支承孔的同轴度约为最小孔尺寸公差之半。孔和平面的位置精度：主要孔对主轴箱安装基面的平行度，决定了主轴与床身导轨的相互位置关系。这项精度是在总装时通过刮研来达到的。为了减少刮研工作量，一般规定在垂直和水平两个方向上，只允许主轴前端向上和向前偏。主要平面的精度：装配基面的平面度影响主轴箱与床身连接时的接触刚度，加工过程中作为定位基面则会影响主要孔的加工精度。因此规定了底面和导向面必须平直，为了保证箱盖的密封性，防止工作时润滑油泄出，还规定了顶面的平面度要求，当大批量生产将其顶面用作定位基面时，对它的平面度要求还要提高。表面粗糙度：一般主轴孔的表面粗糙度为Ra0.4m，其它各纵向孔的表面粗糙度为Ra1.6m；孔的内端面的表面粗糙度为Ra3.2m，装配基准面和定位基准面的表面粗糙度为Ra2.50.63m，其它平面的表面粗糙度为Ra102.5m。3箱体零件的材料及毛坯箱体零件材料常选用各种牌号的灰铸铁，因为灰铸铁具有较好的耐磨性、铸造性和可切削性，而且吸振性好,成本又低。某些负荷较大的箱体采用铸钢件。也有某些简易箱体为了缩短毛坯制造的周期而采用钢板焊接结构的。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