數(shù)控技術(shù)專業(yè)英語教案PAGEPAGE5學(xué)習(xí)情境1LS1CNCLatheMachining班級學(xué)習(xí)任務(wù)2Task2ProcessAnalysisofCNCLatheMachining日月學(xué)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(biāo)題欄·Dimensions;尺寸·Technicalrequirements.技術(shù)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(zhì)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(jī)床的變形?！縍eliefangleservestoeliminaterubbingbetweentheworkpieceandtheendflank.（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(jīng)過某一點(diǎn)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(yīng)用公式v=πDn/1000計算2.Ifthediameterofthenewsurfaceis50mm,thediameterofthefinishedsurfaceis46mm,howmuchisthedepthofcutforturning?提示：應(yīng)用ap=（dw-dm）/2公式計算ProfessionalsituationsimulationKeyWords:projectedviews;crosssection;titleblock;dimension;dimensi