机械制造技术基础课件-CHAPTER3-section1-2012

Chapter3Basicconceptsandknowledgeinmachiningprocess3.1Thetaskandcontentofpartsmachining3.2Basicconcepts3.3Thelocationprincipleofworkpiece3.4Choiceoflocationdatumandcalculationoflocationerror3.5Workpiececlamping3.6Relationshipbetweenclampingandmachiningaccuracy3.7Themotionanalysisofmachinetool3.8Theprincipleandproceduresofprocessplanning3.9metalremoval,processdimensionalchainandeconomicalmachiningaccuracyQuestionspreview•Questionsrelatedwith“process”(1)Haveyoueverheardabouttheword“process(工艺）”before?Canyougivesomeexamples?(2)Whatwordswilloccurinyourmindwhenpeopletalkabout“process”?Givethekeywords.(3)Doyouthinkaprocessisuniqueorvariational?Why?(4)Accordingtoyourunderstanding,whatwillbeinvolvedinamachiningprocess?CardofprocessroutineOperationcardTheprocessofaproductfromrawmaterialtofinishedmachineformingoftheroughcastorpart——casting、forging、punching,welding、pressing、agglomeration（烧结）、infusing(注塑)、moulding…Machining—cutting、grinding,specialmachining(non-conventionalmachining)Material’spropertiesadaptationandtreatment——heattreatment,electroplate、coating,filming…Machineassemble—connectthepartsaccordingtothedefiniterelationshipandspecification,includingpartfixing,connection,adjustment,balance,inspectionandtestφ20±0.072×10.8Engineeringdrawingofaladderedshaftφ32φ40φ25±0.07φ350-0.0170.80.8354030550150其余倒角1×45°3.22×1Question:Canyoutellthefunctionsandspecifications（技术条件）fortheseparts?Ascrewtobemachined3.1ThetaskandcontentofpartsmachiningManufacturingistoutilizeandmanagematerials,people,equipment,andmoneytoproduceproducts.Toachieveasuccessfulandeconomicalmanufacturing,theplanningmustbemadefromthebeginningofthedesignstageandgothroughtheselectionofmaterials,processes,equipment,andtheschedulingofproduction.Theessentialofmanufacturingistoturnrawmaterial(orsemi-product)intofinishedproductwhichsatisfiestherequirement.Thetaskofmachiningistoturntherawmaterial(roughcast)intothefinishedpartswhichsatisfiedtherequirementofproduct.Machininginvolvesthemethod(means)andprocess.3.2.1manufacturingprocess(生产过程）Theprocessofaproductinvolves：Productdesignandprepare、transportoftherawandprocessedmaterials、roughcastforming、machining、heattreatment、assembly、deburring、test、paintingandpacking.Theserelatedprocessesconstitutetheso-called“productionprocess”.Itisusuallycompletedbythecoordinatedworkofdifferentfactoriesorworkshops.3.2Thebasicconceptsinmachining3.2.2Processofapart（工艺过程）Processofapart:Theprocessbywhichtheshape,dimensionsandperformanceofrawmaterialorroughcastingarechangedandturnedintothedesiredpartsdirectlybymachiningiscalledtheprocessofapart,orpartprocessingroute.Whenpartsareassembledintoaproduct,itiscalledtheassemblyprocess.4.1.2.1Whatconstitutesapartprocess?Partprocessconsistsofoneorseveraloperationsinsequence.Aroughcastingcanbeturnedintoafinishedorsemi-finishedproductbytheoperations.(1)Operationsorjobs（工序）Thejobfinishedbyoneoperator(oragroupofoperators)whoworksinafixedworkposition(onemachinetoolorclippingtable)toachievethecontinuousmanufacturingforoneorseveralpartsiscalledtheoperation.Anoperationisthebasicelementofapartprocess,andaswellastheelementfortheproductionschedulecostassessment.Ifthenumberofthepartsinabatchissmall,themanufacturingprocesscanbecompletedthrough5operations,whichareshownintable4-1.Fig4-1istheengineeringdrawingofashaftmovieTable4-1theprocessofshaftmanufacturingOperationNo.OperationnameWorkplace1facingandcenterdrillingthetwoends,Enginelathe2CylindricalTurningEnginelathe3KeywaymillingUprightmillingmachine4CylindricalgrindingGrindingmachine5deburringClippingtableToproducethesamepartasFig4-1,ifthenumberofpartsislarge,theoperation1intable4-1canbedividedintothefollowing2operations:a）facingandcenteringoneendinanenginelathebyoneoperatorb）transferringtheparttoanotherenginelatheforfacingandcenteringanotherendbyanotheroperator（2）OperationSteporsub-jobs（工步）Anoperationstepisthebasicelementofanoperation.Anoperationstepisdefinedasanoperationthatiscompletedundertheconditionwhenthesurfacetobemachined,thecuttingparameters(includingcuttingspeed,feedandbackengagement)andcuttingtoolremainthesame.Ifanyoftheconditionischanged,itwillbecomeanotheroperationstep.Whenseveralsurfacesofapartaremachinedsimultaneously,itiscalledacompositeoperationstep.Thepurposeofclassifyinganoperationintostepsistomakeacomplexoperationmoreconvenientandeasiertoanalyzeanddescribe,tomakethemanufacturingmoreefficienttoorganize,andtomaketheoperationtimeeasiertocalculate.Question:Canyoumaketheoperationstepsfortheshaftprocess?（3）cuttingpass（走刀）Whentheamountofmetalremovalislarge,severalcuttingpassesmayneed.Acuttingpassisakindofoperationstepthatiscompletedbythesamecuttingtooltocutthesamesurfaceunderthesamecuttingparameters.（4）Setup（安装）Beforeitcanbemachined,thepartmusthaveaproperpositionrelativetothecuttingtool,andbeclampedbyafixtureinthemachinetool.Thisprocedureiscalledtheclamping.Thejobfinishedbyoneclampingiscalledthesetup.EachoperationmayhaveeithersinglesetuporseveralsetupsInthesameoperation,thenumberofsetupsshouldbearrangedtobeasfewaspossible.Itcannotonlyraisetheprodu