数控技术应用专业英语LS1-2

数控技术专业英语教案PAGEPAGE5学习情境1LS1CNCLatheMachining班级学习任务2Task2ProcessAnalysisofCNCLatheMachining日月学时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;投影视图·Crosssections;剖视图·Titleblock;标题栏·Dimensions;尺寸·Technicalrequirements.技术要求（2）Tolerance['tɔlərəns]n.公差1)Dimensionaltolerance尺寸公差symmetrical[si'metrikəl]adj.对称的asymmetrical[ˌeɪsɪˈmetrɪkl]adj.非对称的2)Geometrictolerance形位公差perpendicular[,pə:pən'dikjulə]垂直度straightness['streitnis]n.平直度，直线性angulatity[ˌæŋɡjuˈlæriti]n.斜度，倾斜度parallelism[ˈpærəlelizəm]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【硬质合金】usuallycomposedoftungstencarbide,titaniumcarbideortantalumcarbideandcobaltinvariouscombinations.Coatedcarbidesarecoatedwithwearresistantmaterialsonthesurfaceofcementedcarbideinsert.（3）Cuttingtoolgeometryrakeangle前角thereliefangle后角Positiverakeanglesreducethecuttingforcesresultinginsmallerdeflectionsoftheworkpiece,toolholderandmachine【正的前角能够减少切削力以减小工件、夹具和机床的变形。】Reliefangleservestoeliminaterubbingbetweentheworkpieceandtheendflank.（4）Three-jawchuckTheadvantagesofthethree-jawchuckarethatitcanautomaticallycenteranditsholdingrangeisbig.Butcenteringprecisionisnothighanditisnotappropriateforsecondaryclampingpartswithhighcoaxialityrequirement.（5）Cuttingdosage切削用量1）CuttingspeedForlatheoperation,thecuttingspeedisdefinedastherateatwhichapointonthecircumferenceoftheworkpiecepassesthecuttingtool.【对于车削加工切削速度并定义为工件圆周方向上刀具经过某一点的速度】Thecuttingspeedisdependentprimarilyuponthematerialbeingmachinedaswellasthematerialofthecuttingtools.Therearealsoothervariablesthataffecttheoptimalvalueofthecuttingspeed.Theseincludethetoolgeometry,thetypeoflubricantandcoolant,thefeedrateandthedepthofcutetc.2）FeedrateThefeedrateisthatthedistancethetooladvancesintotheworkpieceperrevolutionoftheworkpiece.Itisgenerallyrecommendedtousehigherfeedrateforroughingoperationsandfinerfeedrateforfinishingoperations.3）CutdepthDepthofcutisdefinedasthedistancethatthecuttingtoolsisplungedintotheworkpiece.Inthefinishingoperation,itisimportanttoselectasmalldepthofcut.3.AnexampleofprocessanalysisofturningSetup1:·Chucktheworkpiecewiththree-jawchuck【三爪卡盘】;·TurnS1,S2,S3,S4,S6,S7,S8;·Cutthe4×2threadrelief【螺纹退刀槽】;·ThreadS4.Setup2:·ChucktheworkpieceonS8;·TurnS11,S10andS9;·CenterdrillanddrillS12hole.PartBPracticeactivityFastPracticeEXERCISE5Makecalculationusingtheformulainthetext.1.Ifthecuttingspeedis157m/min，thediameteroftheworkpieceis50mm,thenhowmuchisthespindlespeed?提示：应用公式v=πDn/1000计算2.Ifthediameterofthenewsurfaceis50mm,thediameterofthefinishedsurfaceis46mm,howmuchisthedepthofcutforturning?提示：应用ap=（dw-dm）/2公式计算ProfessionalsituationsimulationKeyWords:projectedviews;crosssection;titleblock;dimension;dimensi