课程教案Teaching Plan7.docx
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课程教案TeachingPlan7
TeachingPlan-7:
Sketch
LearningOutcomes
Onthecompletionofthisunityouwillbeabletocorrectlyusethefollowingskillsasfollows:
•Createasketch.
•Identifyconstraintscorrectly.
Assessment
Competencywillbeassessedbyoperationtasksthroughoutthissection.PleaseforwardthePracticalApplicationsManualtoyoursupervisorforassessmentoncompletionofoperationtasks.
Resources
PracticalApplications(Period:
2classesinclassroom)
《PracticalApplicationsofUGNX4.0(StudentGuide)》
Lesson7:
Sketching
Operation(Period:
2classesincomputertrainingroom)
《PracticalApplicationsManual》
Operation4:
Sketching
KeyPoint
Createandeditasketch,constraint
SketchingOverview
Asketchisacollectionoftwo-dimensionalgeometrywithinapart.Eachsketchisanamedcollectionof2Dcurvesandpointsresidingonaplanethatyouspecify.
Sketchertoolsletyoufullycaptureyourdesignintentthroughgeometricanddimensionalrelationshipsthatwerefertocollectivelyasconstraints.Useconstraintstocreateparameter-drivendesignsthatyoucanupdateeasilyandpredictably.
Whenthereisacommonlyusedshapethatvariesinsize,asketchcaneasilyaccommodatetheiterationsofthedesignbyeditingasingleconstraint.
Sketchesshouldbeusedasbasefeaturesofamodeliftheshapelendsitselftoextrudedorrevolvedgeometry.
SketchesandthePartNavigator
SketchescanbecreatedbychoosingtheSketchSectioniconincertainfeaturecreationdialogssuchasExtrudeandRevolve,choosingtheSketchicondirectlyintheFormFeaturetoolbar,orbychoosingInsert→Sketch.
CreatingaNewSketch
DefiningaSketchPlane
Whencreatingasketch,youfirstneedtodefinetheplaneonwhichtoplacethesketchcurves.But,youmustconsiderthestateofthemodel.
Aniconoptionbarshownbelowappearsintheupperleftcornerofthegraphicswindowandcontainsoptionstodefinethesketchplane.
NamingaSketch
Sinceauniquenameisrequiredforeachsketch,adefaultnamewillinitiallybeassignedwithanumericsuffix.Theformatofthedefaultnameis"SKETCH_###"where###isreplacedbythenextsequentialthreedigitnumberbeginningwith000(SKETCH_000,SKETCH_001,etc.).Asketchnamemaybedefinedduringorafterthesketchhasbeencreatedbyclickingonthedefaultsketchname,typinginthenewnameandpressingEnter.
TheActiveSketch
Inanygivenparttheremaybenumeroussketchesofdifferentfeaturesatdifferentorientations.Whenusingthesketcher,onlyonesketchmaybeworkedonatatime.Thissketchiscalledtheactivesketch.Curvescreatedwhileasketchisactivebecomeassociatedwiththeactivesketch.Whenreturningtoasketchtoaddtoormodifyaprofile,thesketchmustbeactivated.Thereareafewwaystoactivateasketch:
•Double-clickingonasketchcurve.
•InthePartNavigatordouble-clickonthesketchfeaturenode.
•ChoosetheSketchiconandselectthedesiredsketchfromtheSketchNamepull-down.
Therearealsoafewwaystodeactivateanactivesketch:
•ChoosetheFinishSketchicon.
•ChooseSketch→FinishSketch.
•Activateadifferentsketch.
•ChooseSketch→Newandcreateanewsketch.
SketchCreationSteps
•Settheworklayerforthesketch.
•ChoosetheSketchicon.
•DefinethesketchplaneonaWCSplane(XC-YC,YC-ZC,orZC-XC)orcreateaDatumCSYSatabsolutecoordinates.
•Namethesketch.
•ChooseOK.
SketchCurves
SketchcurvesarecreatedviatheSketchCurvetoolbar.AscurvesarecreatedgeometricconstraintsareassignedtothecurvesrelativetotheInferConstraintsSettings.
1–Profile
2–Line
3–Arc
4–Circle
InferConstraintSettings
TheInferConstraintsSettingsdialogdetermineswhichconstraintsareautomaticallycreatedduringcurvecreation.ItisaccessedbychoosingtheInferConstraintSettingsiconfromtheConstraintstoolbarorTools→Constraints→InferConstraintSettings.
Asyoucreatethecurvesasymbolwillappearnearthecurvebeingcreatedtorepresenttheconstraintthatwillbeapplied,ifany.
LockingaConstraint
WhenaconstraintsymbolappearsduringcurvecreationyoumaylockinthatconstraintbypressingMB2.Forexample,ifyouarecreatingalineandtheparallelsymbolappears,pressMB2.Asyoumovethecursor,thenewlinethatisrubberbandingisdoingsoparalleltothereferencecurve.
SnapPointToolbar
TheSnapPointtoolbarcanbedisplayedwhencreatingmostofthecurvetypesinthesketchersothatyouhavemorecontrolovertheselectionoflocations.
WhentheSnapPointtoolbarisactive,regardlessofthepointtypesturnedon,cursorlocationisalwaysavailable.
ProfileTool
TheProfiletoolallowscreationofastringoflinesandarcswithouthavingtospecifyastartforeachcurveafterthefirstcurveiscreated.TheProfiletoolisturnedonbydefaultwhenyoufirstcreateasketchandcanbeaccessedbychoosingtheProfileiconontheSketchCurvetoolbar.
CreatingLines
LinecreationisaccessedbychoosingtheLineiconontheSketchCurvetoolbar.
Onceinlinecreation,theiconsintheupperleftcornerofthegraphicswindowprovidetwooptions:
CoordinateMode(bycursorlocationorkeyinginanXCandYCcoordinates)andParameterMode.
CreatingArcs
ArccreationisaccessedbychoosingtheArciconontheSketchCurvetoolbar.
Onceinarccreation,theiconsintheupperleftcornerofthegraphicswindowgiveyoutwosetsofoptions.Thefirstiscreationmethod,andthesecondisfortheCoordinate/ParameterMode.
Therearetwodifferentarccreationmethods:
Arcby3Points
•Locatethestart,locatetheend,andthenlocateapointonthearc.
•Locatethestart,enteraradiusvalueandpressEnter,locatetheendpoint,andthenmovethecursortopreviewandchoosewhichofthefourpossiblesolutionstocreate.
•Thesameastheprevious,butentertheradiusvalueafterlocatingtheendpoint,butbeforethepointonarc.
ArcbyCenterandEndPoints
•Locatethecenter,locatethestartpoint,andlocatetheendpoint.(Thestartpointlocationdeterminestheradius.)
•Locatethecenter,locatethestartpoint,enteraradiusvalueandpressEnter,locatetheendpoint.
•Locatethecenter,enterradiusandsweepanglevaluesandpressEnter,locatethestartofthesweep,andspecifythedirectionforthesweep.
CreatingCircles
CirclecreationisaccessedbychoosingtheCircleiconontheSketchCurvetoolbar.
Onceincirclecreation,theiconsintheupperleftcornerofthegraphicswindowprovidetwosetsofoptions.Thefirstiscreationmethod,andthesecondisfortheCoordinate/ParameterMode.
Therearetwodifferentcirclecreationoptions:
CirclebyCenterandDiameter
•Locatethecenter,andthenlocateapointonthecircumferenceofthecircle.
•Locatethecenter,enteraDiameter,andpressEnter.Thecircleiscreated.Youaretheninmultiplecirclecreationmode-justindicateanotherlocationforacirclecenter.
•Locatethecenter,dragtheradiusuntilyougetthesizeyouwant.PressEnter.Thecircleiscreated,andyouareinmultiplecirclecreationmode.Indicateanothercenter.
Circleby3Points
•Locatethreepointsonthecircumferenceofthecircle.
•Locatetwopointsonthecircumferenceofthecircle,enteraradiusvalueandpressEnter,thenchoosewhichofthetwooptionsyouwantbycursorlocation.
CreatingFillets
FilletcreationisaccessedbychoosingtheFilleticonontheSketchCurvetoolbar.
Onceinfilletcreation,iconoptionsappearintheupperleftcornerofthegraphicswindow.TheTrimInputsoption
(1)determineswhetherornottheoriginalcurvesaretrimmed.TheDeleteThirdCurveoption
(2)determineswhetherthemiddlecurveisdeletedinathree-curvefillet.TheCreateAlternateFilletoption(3)willproduceacomplementarysolutionforthefillet(e.g.a270degreearcinsteadofthedefault90degreearc).
Youcancreatefilletsbetweenlines,arcsorconics.Youcanalsocreateafilletbetweentwoparallellines.
ThereareseveralwaystocreateFillets:
•Selecttwocurveswithasingleselection(attheirintersection),andthendragthesizeandquadrant.
•Selecttwocurvesindividually,anddragthesizeandquadrant.
•Selectonecurve,enteraradiusvalue,andselectthesecondcurve.
•Selecttwocurvesindividually,enteraradiusvalue,andtheindicatethedesiredquadrant.
•Drag(withMB1)acrossthetwocurvesyouwanttofillet.Thesizeofthefilletisdeterminedbywherethecurvesareselected.
TrimmingandExtendingCurves
QuickTrim
Thisoptionwillallowyoutotrimanycurvetotheclosestcurveinthesketchandpreviewtheresultsinpreselectioncolor.
Youcantrimmultiplecurvesatonetime,byusingthe"crayon"selectmethod.
HolddownMB1anddragacrosstheportionofcurvesyouwanttotrimaway.
Youcanselectaspecificcurvetotrimto,byusingCtrl-selecttoselectthedesiredboundarycurve.Morethanoneboundingcurvecanbeselectedusingthismethod.
Whenacurveistrimmed,appropriateconstraintsareautomaticallycreated.Inthepreviousexample,twoPointonCurveconstraintsandoneCollinearconstraintareadded.Ifoneoftheboundarycurvesislatertrimmedtotheline,thePointonCurveconstraintwouldchangetoCoincident.
Ifyoutrimanarctoalinethatistangent,thetangencyconstraintisretained.
QuickExtend
Thisoptionwillextendlines,arcsandconicstotheclosestcurveinthesketch.Thesystemwillpreviewtheresultsinthepreselectioncolor.
Thecurvebeingextendedmustextendtoanactualintersectionwiththeboundarycurve.
Youcanextendmultiplecurvesat