便携药盒模具设计与加工工艺文档格式.docx

便携药盒模具设计与加工工艺文档格式.docx

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AnintegratedCAD/CAE/CAMsystem,HSC-1.1,isdescribedinthisarticle.AttheCAD/CAEstagethedrawingsofinjectionmouldedpartscanbetransformedintothedrawingsofthemouldpartsinteractivelyand,accordingtotheuser'

sneeds,themechanicalcheck,runnerbalanceanalysis,flowsimulationandcoolingsimulationcanbecarriedout.NCtapesforwirecuttingormillingmachinetoolscanbegeneratedattheCAMstage.Thepracticeshowsthatthesystemisausefultoolformoulddesignersandmanufacturers.

Introduction

Injectionmouldingisoneofthemostimportantpolymerprocessingoperationsinindustrytoday.Itissuperiorformassproductionofcomplexpartstohighprecisionatlowcost.Foralongtime,experience,intuitionandtrialanderrorhavebeenkeyfactorsinmoulddesigning,mouldmanufacturingandmouldingoperation.Theseapproacheshavebecomeincreasinglyinefficientandcostly,especiallywhenappliedtothemouldingoflargepartsandpartsofhighprecisionortotheprocessingofnewkindsofpolymers.NowsomeoftheseproblemsarebeingsolvedsuccessfullybycombiningrecentadvancesinCAD,CAEandCAMtechnology.

InrecentyearsmoreandmoreCAD/CAE/CAMsystemsforinjectionmouldinghavebeendevelopedanddeliveredinWesternindustrializedcountries,suchasC-MOULD3.1ofACTechnologyInc.intheUSA,CAD-MOULDofIKVinGermany,McKAM-llofMcCillUniversityinCanada,andMoldFlowinAustralia.Withthehelpofthesesoftwarepackagestheproductivityandqualityofinjectionmouldedpartscanbeimprovedandthestart-uptimecanbeshortened.

CAD/CAE/CAMtechnologyforinjectionmouldinghasbeendevelopedquicklyinChinasince

1980.Asapioneerinthisfieldinourcountry,wehavestudiedanddevelopedCAD/CAE/CAMtechnologyofinjectionmouldingformanyyears.Throughfiveyears'

developmentandpracticalverification,anintegratedCAD/CAE/CAMsystemforinjectionmoulding,HSC-1.1,hasbeendevelopedandputintousesuccessfullyinmanyfactories.

Systemdescription

HSC-1.1isdevelopedonpersonalcomputerssuchasthePC386andPC486.Thedesirableinternalstorageis4MBormore,andtheexternalstorageismorethan100MB.

Fig.1showsthesoftwarerequirementsofHSC-1.1.Thesystemisdevelopedandrununderthe

environmentofOperatingSystemII（OS/2）orMS-DOS.InthesystemAutoCAD-10.0isusedonlyasagraphiceditoranddrawingsoftware.StandardFortran77andAutoLispareusedforprogramming.Exceptforafewofprogramsforgraphicdriver,allthesoftwareinthesystemisindependentofcomputers,whichensuresgoodportabilityofthesystem..

AsshowninFig.2,HSC-1.1integratesninemoduleswiththeirfunctiondesignbasedontherequirementsofusers.Allmodulesinthesystemaresupervisedbyamaincontrolprogramnamedcontrolpanel'

or'

controlmenu'

.Userscaninvokeanymodulebyorderingthemenudisplayedonthescreenbythecontrolpanel.Thedataexchangefromonemoduletoanotherisimplementedautomaticallyintheformofdatafiles.Fig.3showsthedataflowchartofHSC-1.1.

FunctionofCADmodules

ThetaskofCADmodulesistotransformthedrawingsofinjectionmouldedpartsintothedrawingsofmouldpartsefficientlyandprovidenecessarydataforsimulationandNCmodules.Duetocomplexcavities,asurfacemodellingprogramhasbeenevelopedforgraphicinput.Planes,regularsurfacesandbi-cubicsurfacescanbecreatedeasily.Theco-ordinatesofpointsonsurfaces

canbecalculatedbytheprogramusingdimensionsofthepartdrawingandtheco-ordinatesofthepointsinputbefore.Whilethepartdrawingisbeinginputonesurfaceafteranother,thedimensionsofthepartwillbetransformedintothedimensionsofthecavityandcorethroughinteraction.Thedataforthecavityandcorearerecordedforbothmoulddesignandsimulation.

AdatabaseforstandardmouldsetshasbeensetupwhichcontainstenkindsofstandardmouldsetsissuedbytheElectricalMinistryofthePeople'

sRepublicofChina.Eachkindofmouldsetcontains13series.Hencethereare31150combinationsofmouldsetsaltogetherinthedatabase.Oncethecavitylayoutisdetermined,allthestandardmouldpartscanbeselectedautomaticallyanddimensionedthroughinteraction.

Thesystemprovidesagroupoffunctionsforuserstodesigntherunnersystem,editconstructionofcavityandcoreandarrangeejectionpinsandcoolinglines.Finallyallthemouldpartdrawingsincludingmovingmouldassembly,stationarymouldassemblyandgeneralmouldassemblydrawingcanbeproduced.Fig.4showsamouldassemblydrawingofaswitchsocketmadeintheShanghaiNo.9RadioFactoryforcolourTVsets.

FunctionofCAEmodules

CAEmodulesincludetheinterfacebetweenCADandCAEmodules,mechanicalcheckformouldplates,runnerbalanceanalysis,flowsimulationandcoolingsimulation.WiththehelpoftheseCAEmodulesthemouldconstructiondesigncanbeimprovedandpossibledefectsininjectionmouldedpartssuchasdegradation,shortshots,andimproperlocationofweldlinescanbeaddressedbeforemouldmaking.

TheinterfacebetweenCADandCAEmodulesreadsthegeometricmodelofcavityanddeliverysystemwhichisproducedatthepreviousCADstageandgeneratesFEMmeshautomatically.Usingtheinterface,userscanalsoselectpolymer,coolant,mouldmaterialandsetprocessconditionssuchasinjectiontemperature,injectiontime,coolanttemperatureetc.Theinterfacereadsthepropertydataofthematerialsfromthedatabankandwritesthemeshconfiguration,materialpropertiesandprocessconditionsintodatafileswhicharetheinputsfortheCAEmodulesdescribedbelow.

Currentlythesystemusesa2Dfinite-elementmethod（FEM）toanalysethemouldplate'

sstrengthandrigidityforatypicalmouldcross-section.Ananalysisprogrambasedona3DFEMisunderdevelopment.

Inordertoguaranteethesamequalitiesoftheinjectionmouldedpartsproducedinmulti-cavities,eachcavitymustbefilledsimultaneouslyatthesamepressureandtemperature.Thisrequirestherunnersystemtobebalanced.InHSC-1.1thebalancecanbereachedbycorrectingthedimensionsofrunnersandgatesdesignedbyusersatthepreliminarydesignstagewhicharemostprobablynotbalanced.

Theflowsimulationprogramisoneofthemostbasicandusefulanalysesinthesystem.The

governingequationsforflowincavitycanbeobtainedbyextendingtheclassicalHele-Shawflowtoaninelastic,non-Newtonianfluidundernon-isothermalconditions:

i-（rti）+J-（bv）=0

dXdf/

+u+v

dtdxBy

Bz2

whereP,Farethepressureandtemperatureofmelt,respectively;

r|,yrepresentviscosityandshearrate;

'

—'

denotesanaverageoverz,thegapwiseco-ordinate;

p,CpandKaredensity,specificheatandheatconductivityofthemelt,respectively;

andbisthehalfgapthickness.Becausethethicknessdimensionofaninjectionmouldedpartisoftenmuchsmallerthantheothertwodimensions,apowerfulnumericalscheme,whichisthehybridofthefiniteelementandfinitedifferencemethods（FEM/FDM）,isadoptedinthesolution.Intheimplementationofthescheme,theplanarco-ordinatesaredescribedintermsoffiniteelementsandthegapwiseandtimederivativesareexpressedintermsoffinitedifferences.Acontrolvolumeapproachisadoptedtoderivethefinite-elementformulationandtrackthemeltfrontmovement.Byuseofflowsimulation,userscanacquireinformationsuchaspressure,velocityandtemperaturedistributions,totalpressuredrop,clampforceetc.,whichisveryhelpfulindesigningthedeliverhelpfulindesigningthedeliverysystemandoptimisingtheprocessconditions.Userscanalsoanimatethefillingofthecavityandobtainanoptimumflowpatternbychangingthenumberandlocationsofgates.

Coolingsimulationincludes3Dsteadyandtransientcoolinganalyses.The3Dsteadycoolinganalysisusestheboundaryelementmethod（BEM）.Formulasformodellingthecavitysurfaces,coolinglinesandexteriorsurfaceshavebeenestablishedandproventobereliableandeffective.Basedonthesteadycoolingsimulation,3Dtransientcoolingsimulationhasbeendeveloped.AnovelBEMhasbeenadoptedinthismoduletoeliminatenumericalbodyintegration.Withthehelpofthismoduleuserscancalculateheattransferbetweencavityandcoolingchannels,reducecoolingtimeandpredicttemperaturealongmouldandinjectionmouldedpartsurfaces.

AllresultsofCAEmodulescanbedisplayeddynamicallywithcontourplots,shadedcolourimagesandvariouscurveplotstoaidusersinimprovingtheirdesign.

FunctionofCAMmodule

ThecutterlocationfilescanbecreatedbasedonthegeometryofcavityandcorewhichismodelledatthepreviousCADstage.NCtapescanthenbegeneratedbyuseofpostprocessorsforbothNCwirecuttingmachinetoolsandNCmillingmachinetools.CurrentlyonlythefunctionofNCwirecuttingisusedinpractice.AlotofinjectionmouldshavebeendesignedandmanufacturedbyusingthesystemHSC-1.1infactoriesinourcountry.

Conclusions

HSC-1.1isanintegratedCAD/CAE/CAMsystemforinjectionmoulding.Allprogramsinthesystemareindependentofcomputersexceptafewprogramsforthegraphicdriver.Itensuresthesystem'

sgoodportability.Themodularstructureofthesystemguaranteesthateachmoduleofthesystemhasgoodexpandabilityandmaintainability.ThepracticeshowsthatHSC-1.1isapowerfultoolformoulddesigningandmanufacturing.Itcanassistengineersincuttingmouldcostandimprovingmouldquality.HSC-1.1willfindmoreand