數控技術專業英語教案PAGEPAGE5學習情境1LS1CNCLatheMachining班級學習任務2Task2ProcessAnalysisofCNCLatheMachining日月學時Knowledgeobjects1.ToreadandlearntheknowledgeaboutprocessanalysisofCNClathe.2.Graspthemethodofreadingpartdrawing.3.Graspthemeaningofcuttingdosageandcanselectitcorrectly.4.Masterthegrammaticalstructures.Abilityobjects1.HelpthestudentstolearnsomephrasalverbsandfunctionalitemsabouttheprocessanalysisofCNClatheandtrytousethem.2.Strengthentheirabilitiesofreading.3.Improvetheabilityofgettingspecificinformationfromreadingthetext.4.Improvetheabilityofanalysisandsolvingproblem.5.Haveteamspritandresponsibility.TeachingMethodsSpeaking;Discussing;Pair-work&group-workTeachingaids:Multi-mediacomputer;PPTTeachingcontentRemarksPartATechnicalReading1.ReadingPartDrawing（1）Basicinformationincludedinapartdrawing·Projectedviews;投影視圖·Crosssections;剖視圖·Titleblock;標題欄·Dimensions;尺寸·Technicalrequirements.技術要求（2）Tolerance['t?l?r?ns]n.公差1)Dimensionaltolerance尺寸公差symmetrical[si'metrik?l]adj.對稱的asymmetrical[?e?s??metr?kl]adj.非對稱的2)Geometrictolerance形位公差perpendicular[,p?:p?n'dikjul?]垂直度straightness['streitnis]n.平直度，直線性angulatity[???ɡju?l?riti]n.斜度，傾斜度parallelism[?p?r?leliz?m]n.平行，平行度（3）Surfaceroughness表面粗糙度

Surfaceroughnessisasignificantfactortomeasureitssurfacequality.Ithasgreatinfluenceontheparts’mating,wearresistance,corrosionresistance,leakproofandappearance.（4）HeattreatmentNormalizing正火annealing退火quench淬火temper回火2.Preparingforprocessanalysis（1）CuttingToolsforTurning（2）CuttingtoolmaterialandpropertyPropertity【特性】：highhardness,toughness,abrasionresistanceandtheabilitytowithstandhighpressure.Material【材料】：High-speedsteel(HSS)isakindofalloysteelthatcontainsareasonablepercentageofalloyingelements,suchastungsten(18percent),chromium(4percent),molybdenum,vanadium,andcobalt.ToolsmadeofHSScanretaintheirhardnessatelevatedtemperatureupto600°C.Cementedcarbide【硬質合金】usuallycomposedoftungstencarbide,titaniumcarbideortantalumcarbideandcobaltinvariouscombinations.Coatedcarbidesarecoatedwithwearresistantmaterialsonthesurfaceofcementedcarbideinsert.（3）Cuttingtoolgeometryrakeangle前角thereliefangle后角Positiverakeanglesreducethecuttingforcesresultinginsmallerdeflectionsoftheworkpiece,toolholderandmachine【正的前角能夠減少切削力以減小工件、夾具和機床的變形。】Reliefangleservestoeliminaterubbingbetweentheworkpieceandtheendflank.（4）Three-jawchuckTheadvantagesofthethree-jawchuckarethatitcanautomaticallycenteranditsholdingrangeisbig.Butcenteringprecisionisnothighanditisnotappropriateforsecondaryclampingpartswithhighcoaxialityrequirement.（5）Cuttingdosage切削用量1）CuttingspeedForlatheoperation,thecuttingspeedisdefinedastherateatwhichapointonthecircumferenceoftheworkpiecepassesthecuttingtool.【對于車削加工切削速度并定義為工件圓周方向上刀具經過某一點的速度】Thecuttingspeedisdependentprimarilyuponthematerialbeingmachinedaswellasthematerialofthecuttingtools.Therearealsoothervariablesthataffecttheoptimalvalueofthecuttingspeed.Theseincludethetoolgeometry,thetypeoflubricantandcoolant,thefeedrateandthedepthofcutetc.2）FeedrateThefeedrateisthatthedistancethetooladvancesintotheworkpieceperrevolutionoftheworkpiece.Itisgenerallyrecommendedtousehigherfeedrateforroughingoperationsandfinerfeedrateforfinishingoperations.3）CutdepthDepthofcutisdefinedasthedistancethatthecuttingtoolsisplungedintotheworkpiece.Inthefinishingoperation,itisimportanttoselectasmalldepthofcut.3.AnexampleofprocessanalysisofturningSetup1:·Chucktheworkpiecewiththree-jawchuck【三爪卡盤】;·TurnS1,S2,S3,S4,S6,S7,S8;·Cutthe4×2threadrelief【螺紋退刀槽】;·ThreadS4.Setup2:·ChucktheworkpieceonS8;·TurnS11,S10andS9;·CenterdrillanddrillS12hole.PartBPracticeactivityFastPracticeEXERCISE5Makecalculationusingtheformulainthetext.1.Ifthecuttingspeedis157m/min，thediameteroftheworkpieceis50mm,thenhowmuchisthespindlespeed?提示：應用公式v=πDn/1000計算2.Ifthediameterofthenewsurfaceis50mm,thediameterofthefinishedsurfaceis46mm,howmuchisthedepthofcutforturning?提示：應用ap=（dw-dm）/2公式計算ProfessionalsituationsimulationKeyWords:projectedviews;crosssection;titleblock;dimension;dimensi