SolidWorks Tutorial几何提取.docx

SolidWorks Tutorial几何提取.docx

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SolidWorksTutorial几何提取

SolidWorksTutorial:

ExternalGearPump

AaronHeisler

UniversityofWisconsin

PowertrainControlResearchLaboratory

May23,2008

Goal:

ThepurposeofthisdocumentistoassistPumpLinxusersintransferringaCADfileofanexternalgearpumpmodeledinSolidWorkstotherequiredSTLfileformatforPumpLinx.

1.Tobegin,acompletepumpmodelmustbecreated.AnexampleofsuchamodelisshowninFigures1and2.Atthisstage,themodelmusthaveallthegeometricfeaturestheuserwishestobeincludedinthePumpLinxanalysis.

Figure1:

Tobegin,thepumpmodelmustbecompleteineverydetailrequiredfortheanalysis.

Figure2:

Thegeartimingisimportantatthisstageintheanalysis.

Thereareafewareaswhichneedspecialattentionsothesimulationcanbeproperlyset-up.Theseissuesincludethefollowing:

∙Thesidefaceofthegearmusthavezerogapbetweenitandthebushing.

∙Thegapsbetweentheteethmustbelargeenoughthatthegearsdonotcrossatanypointduringarevolutionoftheinputshaft.ForthepumpshowninFigures1and2,theminimumgapwasapproximately0.0034in.Themagnitudeofthegapwilldependupontheindividualpumpdesign.

∙Theexactcenterlocationofthegearsmustbeknown.Forsimplificationlateron,matetheassemblyorigintothecenterofoneofthebottomgearsandaddparallelmatesbetweentheassemblyplanesandpartplanes.Thepurposeofthisstepistoensurethatthepumpisalignedtoaspecificcoordinatesystemthatcanbeeasilyreferencedatanypointintime.

2.Nowthatthepumpgeometryisfinishedtothelevelofdetaildesiredfortheanalysis,thefluidregionmustbeextracted.Thisisdoneintwodistinctsteps.Thefirststepextractsthefluidencompassedbytheapproximate“figure8”volumethegearspassthroughduringonerevolutionoftheinputshaft.Toextractthisvolume,executethefollowingsteps:

a.Openanewpart.

b.Drawacircleinanyreferenceplane.Dimensionthecirclesoitexactlymatchesthediameterofthehousingwherethegearislocated（seeFigure3）.

c.Drawacircleofequaldiametertocreatea“figure8”shapedsketchthatfillsthevoidinsidethehousingshowninFigure3.ThefinalsketchshouldlooksimilartothatshowninFigure4.

Figure3:

Thenewpartmusthavethesamediameterastheholesboredinthehousingenclosingthegears.

Figure4:

The“figure8”shapedpartbeginsasadrawingcontainingtwoequaldiametercircleswithaknowncenterdistance.

d.Extrudethisshapetotheexactwidthofthegears.ThefinalpartshouldbesimilartothevolumeshowninFigure5.

Figure5:

Extrudethesketchtotheexactwidthofthegears.

e.Thispartistheninsertedintothepumpassemblyandmatedsuchthatitfillstheaforementionedvoidencasingthegears.Thegearoutlinewillstillbevisiblesincebothpartsaretheexactsamethickness.

Figure6:

Thenewpartisinsertedintotheassemblyandmatedsuchthatitencapsulatesthepairofgearsandfillsthehousingbore.

f.Selectthenewpart,andclick“EditComponent”inthemaintoolbar.Thengoto“Insert”–“Mold”–“Cavity”asshowninFigure7.For“DesignComponents”selectthetwogearsthatthispartencapsulatesfromthetreethenclickOK.Keep“ComponentOrigins”,“UniformScaling”,and“0.00%”fortheoptions.

Figure7:

Toextractthefluidregionaroundthegears,the“Cavity”featurewillbeused.Specialcaremustbetakentoensuretheproperregionisextracted.

Figure8:

Selectthetwogearswhichthepartisinplanewithunder“DesignComponents”andensurenoscalingisapplied.

g.Anewwindowwillopentitled“BodiestoKeep”.Clickthe“Selectedbodies”buttonandselectthebodythatisthenewpartminusthegearvolume.ThesmallvolumesatthecenterofthegearsinFigure9shouldnotbesavedasthoseregionsdonotcontainfluidintheactualpump.

Figure9:

Multiplevolumesarecreatedwhenthe“Cavity”functionisused.Picktheappropriatebodywhichequatestothevolumeoffluidtrappedaroundthegears.

h.Thispartisnowfinished.Repeatthisprocessforeachpairofgearspresentinthepump.

Figure10:

Thefinishedpartistheoriginal“figure8”shapewiththegearvolumesubtracted.Thisisthefirstofthetwofluidregionsrequiredandneedstobedoneforeachpairofgears.

3.Thesecondfluidvolumecannowbeextractedfromthegearpumpassembly.Executethefollowingsteps:

a.Openanewpart.

b.Createanarbitraryshapethatfillstheentirevolumeofthepump.Theshapeofthispartisnotimportantandcanbeofnearlyanydesign.Theonlyimportantnoteisthatthispartshouldhavethesamewidthasthedistancebetweentheinletandoutletportfaces.MatetheinletandoutletfacessotheyarecoincidentasshowninFigure12.

Figure11:

Toextractthefluidtrappedintheinletandoutletports,createalargepartthatcapturesalltheregionsinsidethepumpthatmaycontainfluidwhichmustbeanalyzed.

Figure12:

Thenewpartismatedtotheinletandoutletportsandislargeenoughtoincludeanyinternalvolumesthatcouldcontainfluidinsidethepumphousing.

c.Thesameprocessaswasusedforthe“figure8”partwillbeusedagaintosubtractthepumpvolumefromthenewpart.Selectthenewpartfromthetreeandclick“EditComponent”.Click“Insert”–“Mold”–“Cavity”.Payspecialattentiontothepartsselectedunder“DesignComponents”.Selecteachhousingsectionaswellasthe“figure8”partscreatedinStep2andthegears.Again,selectComponentOriginsfrom“Scaleabout”,“Uniformscaling:

0.00%”.ClickOK.

Figure13:

Whenusingthe“Cavity”functiontofindtheinternalvolumesofthepump,besurethatallthepartsincludingthepumphousing,“figure8”parts,andgearsareselectedunder“DesignComponents”.

d.Whenthe“BodiestoKeep”windowpopsup,clickthe“SelectedBodies”buttonandselectthebodiesthatarethefluidvolumefromtheinletandoutletfacestothegears.Typically,“Body1”and“Body2”aretherequiredvolumesalthoughthisisdependentupontheinternalpumpdesign.ClickOK.

e.ThefinalpartshouldlooksimilartothevolumeshowninFigure14.

Figure14:

Thefinalpartshouldlooksimilartothis.

4.Thefinalstepistosavethenewpartsinthecorrectformat（.stlfileextension）.Todothisfromtheassembly,click“File”–“SaveAs”.Under“Saveastype”clickthedropdownmenuandselect“STL”.

Figure15:

SelectSTLfromthe“Saveastype”format.ThisisthefileformatPumpLinxrequireswhenimportingathree-dimensionalsurface.

Clickthe“Options…”buttonatthebottomofthewindow.Atthispoint,selecttheresolutionthatisappropriatefortheapplication.Forafinermesh,selectanAngleToleranceof1.0°andtheminimumDeviationTolerance.Clickthecheckboxinfrontof“DonottranslateSTLoutputdatatopositivespace”!

NeglectingthisstepwillmovetherelativepositionofthepartswhentheyareimportedintoPumpLinx.Thenclick“OK”and“Save”.

Figure16:

Intheoptionsmenu,besuretoclickthebutton“DonottranslateSTLoutputdatatopositivespace”.Ifthisboxisnotchecked,theoriginsofthepartwillberelocatedrandomlywhenthepartsareimportedtoPumpLinx.

Dependingonthepump’sdesign,morethanadozenSTLfileswillbecreated.OnlythefluidregionfilesarenecessaryforthePumpLinxanalysis.Inthisexample,therequiredfilesarethetwo“figure8”shapedpartsaswellastheinletandoutletportparts.