注塑模具原理(Principle of injection mold)

注塑模具原理(Principleofinjectionmold)注塑模具原理(Principleofinjectionmold)Pouringsystemreferstotheflowofplasticfromthenozzleintothemoldcavity,includingthemainroad,coldmaterialhole,diversionchannelandgate.Formingpartsarepartsoftheshapeoftheproduct,includingmovingdie,fixedmoldandcavity,core,formingrodandexhaustport,etc..Thetypicalmoldstructureasshowninfigure.MainstreamRoadItisapartofthemoldthatconnectstheinjectionnozzletotheshuntorcavity.Thesprueisconcaveatthetoptoconnectwiththenozzle.Mainchannelinletdiametershouldbeslightlylargerthannozzlediameter(O.8mm)toavoidoverflow,andpreventtheconnectionbetweenthetwobecauseoftheinterference.Thediameteroftheinletdependsonthesizeoftheproduct,usually4-8mm.Thespruediametershouldbeenlargedinward3degreesto5degrees,sothatthenewreleasechannel.ColdmaterialholeItisaholeattheendofthemainchanneltocapturethecoldmaterialproducedbetweenthetwoinjectionsattheendofthenozzle,thuspreventingtheblockageoftheshuntorgate.Ifthecoldmaterialismixedwiththemoldcavity,itiseasytoproduceinternalstressintheproducts.Thediameterofthecoldmaterialholeisabout8lOmm,andthedepthis6mm.Foreaseofdemoulding,thebottomisoftentakenupbythereleaselever.Thetopoftheejectorpinsshouldbedesignedintoahookorasunkengroovewinding,smoothlypullthespruetoblockdemoulding.DistributarychannelItisthechannelconnectingthemainchannelandeachcavityinthemultichannelmold.Asthemoltenmaterialtospeedwitheachcavity,arrangedintherunnermoldshouldbesymmetricalanddistancedistributionetc..Theshapeandsizeofthecrossflowchannelaffectboththeflowoftheplasticmelt,thedemouldingoftheproductandthedifficultyinthemanufactureofthedie.Iftheflowisequaltotheamountofmaterial,theflowresistanceofthecircularcrosssectionisminimum.Butbecauseofthecylindricalrunnersurfaceissmall,unfavorabletoshuntblockcooling,andtherunnermustbeopenedinthetwomodes,istime-consumingandeasyalignment.Therefore,itisoftenusedinthetrapezoidalorsemi-circularsectionoftheshunt,andopenedinahalfmoldwithareleaselever.Therunnersurfacemustbepolishedtoreduceflowresistanceandprovidefastermoldfillingspeed.Thesizeoftherunnerdependsonthesizeoftheplastic,thesizeandthicknessoftheproduct.Formostthermoplastics,thecross-sectionalwidthofthebypasssectionisnomorethan8m,andtheextralargecanbeupto1012M,especiallythesmall2-3m.Tomeettheneedsofthepremiseshouldtrytoreducethecross-sectionalarea,toavoidincreasingtheshuntandthusextendthecoolingtime.GateItisthepassagethroughthemainchannel(orshunt)andthecavity.Thecross-sectionalareaofthechannelcanbeequaltothatofthemainchannel(orshunt),butisusuallyreduced.Soitisthesmallestsectioninthewholeflowpassagesystem.Theshapeandsizeofthegategreatlyaffectthequalityoftheproduct.Thegateis:A,controlofthematerialflowrate:B,theinjectionbymoltenmaterialstoredinthispartoftheearlysettingandpreventbackflowC,themoltenmaterialbythestrongshearbyincreasingthetemperature,therebyreducingtheapparentviscositytoimproveliquidity:D,forproductsandrunnersystemseparation.Theshape,sizeandlocationofthegatearedeterminedbythenatureoftheplastic,thesizeandthestructureoftheproduct.Generally,theshapeofthegateisrectangularorround,thesectionalareashouldbesmallandthelengthshouldbeshort,whichisnotonlybasedontheabovefunction,butalsobecausethegateislargerandeasier,whilethebiggateisverydifficulttoreduce.Thepositionofgategeneralshouldnotaffecttheappearanceandthicknessoftheworkplace.Thegatesizeshallbedesignedwithregardtothenatureoftheplasticmelt.B3a6xK"X&Z.rBV"-quality-SPC,six,sigma,TS16949,MSA,FMEA0Q,W,L4g,L(q:k,P,D/,N)CavityItisthemoldingofplasticproductsinthemoldspace.Thecomponentsusedasformingcavitiesarecollectivelyreferredtoasformingparts.Eachformingpartoftenhasaspecialname.Amoldedpartsproductappearancecalleddie(alsocalleddie),constitutetheinternalshapeofproducts(suchasholesandgrooves)calledcoreorpunch(alsocalledmale).Whendesigningamoldingpart,theoverallstructureofthecavitymustbedeterminedaccordingtothepropertiesoftheplastic,thegeometricalshapeoftheproduct,thesizetoleranceandtherequirementoftheuse.Secondly,thelocationofpartingsurface,thelocationofgateandventandthewayofdemouldingaredeterminedaccordingtotheselectedstructure.Finally,accordingtothecontrolsizeofeachpartofthedesignanddeterminethecomponentsofthecombinationbetweentheway.Whentheplasticmeltentersthemoldcavity,ithasahighpressure,sothemoldingpartsshouldberationallyselectedandcheckedforstrengthandrigidity.Inordertoensurethatthesurfaceofplasticproductsissmooth,beautifulandeasytorelease,thesurfacesthatcontacttheplasticsareRa>0.32uminroughnessandresistanttocorrosion.Moldingpartsaregenerallytreatedbyheattreatmenttoincreasehardnessandaremadeofcorrosion-resistantsteel.ExhaustportTheutilitymodelisagrooveshapedairoutletwhichisarrangedinthemould,andisusedfordischargingthegasproducedbytheoriginalandthemeltingmaterial.Themoltenmaterialintothecavity,theoriginalinthecavityandthegasintotheairfromthemeltmustbeinthematerialflowthroughtheexhaustporttotheoutsideofthedieattheendofdischarge,otherwiseitwillmaketheproductswithporosity,badweld,fillingandairaccumulationduetocompressioncausedbyhightemperatureproductswillburn.Ingeneral,theexhaustholecanbelocatedinthecavityflowofmeltendtypeorinthemoldonthesurface.Thelatterisadeepgroovewithadepthof0.03-0.2mmandawidthof1.5-6mmatthesideofthedie.Injection,exhaustholewillnothavealotofmeltexudation,becausethemeltwillinthecoolingandsolidifyingthechannelblocking.Theopeningpositionoftheexhaustportshallnotbedirectedtotheoperatortopreventaccidentalexplosionofthemoltenmaterial.Inaddition,theclearancebetweentheejectorrodandtheejectorholecanalsobeutilizedtoexhausttheclearancebetweenthetopblockandthestripperplateandthecore.StructuralpartsItreferstothestructureofthevariouspartsofthemold,including:guidance,demoulding,corepullingandclassificationofvariousparts.Suchasfrontandrearplywood,frontandrearbuckletemplate,pressureplate,pressurecolumn,guidecolumn,strippingplate,releaserodandreturnrod.HeatingorcoolingdeviceThisisadeviceforsolidifyingandsettingthemeltinthemold.Thethermoplasticisusuallythechannelofcoolingmediuminthedie,andthecoolingmediumiscirculatedtoachievethecoolingpurpose.Thecoolingmediumpassesvariesdependingonthetypeofplasticandthestructureoftheproduct.Thereiscoldwater,hotwater,hotoilandsteam.Thekeyisuniformcoolingwithhighefficiency.Unevencoolingwilldirectlyaffectthequalityandsizeoftheproduct.Theshapeoftheproductshallbebasedonthethermalpropertiesofthemelt(includingcrystallization)Injectionmolddesignprinciplesgenerallyincludethefollowing:InjectionmolddesignprincipleInjectionmolddesignprinciplesgenerallyincludethefollowing:UnidirectionalflowFlowbalanceConstantpressuregradientMaximumshearstressWeldmarkAvoidunsalablestayAvoidsubsurfaceflowControlledfrictionalheatingRunnervalveAcceptablerunner/cavityratioThefollowingarethebasicexplanationsforthesediedesignprinciples;Thebasicinterpretationoftheunidirectionalflowdesignprinciple.Onedirectionflowdesignprincipleistoensurethatinthefillingprocess,theplasticshouldflowinonedirectionandmaintainastraightflowfront.Thisleadstothegenerationofsingledirectionalpositioning.Abalancedflow;allflowpathsshouldbebalanced;thatis,fillinginthesamepressureatthesametime.Themostefficientwayoffillingisthepressuregradient(pressuredecreasestounitlength),whichisfixedalongtheflowpath.Maximumshearstress;maximumshearstressTheshearstressatthetimeoffillingshouldbelessthanthemaximumcriticalshearstressofthematerial,andthenumericalvaluedependsonthematerialandtheapplication.Weld/fuseposition;placeweldlineandfusionlineattheleastsensitivepart.Avoidstagnation;onlymayavoidsettingthegateintothethickandthinflowpathwherethefluidflowpath.Avoidsubsurfaceflow;avoidsubsurfaceflowthroughthegatesettingtoensurethatthefluidmeetsinthefinalfillingarea.Frictionheating;designflowpassageforcontrollingfrictionheating,increasingmelttemperatureofcavity,whichwillobtainlowerstressintheproductwithoutcausingdegradationofplastics,becauseplasticsareinhighertemperatureforalongtime.Hotrunnervalve:theuseofhotvalvedesignrunnersystem,toensurethatinthefreezingofthegate,thecavityisjustfilledandfullypressurized,whichavoidsfillinginthemoldaftertheendofthepressureorreverseflow.Runnerratio:therunnersystemisdesignedforhighpressuredroptominimizeflowchannelmaterialandobtainalowratiorunner/cavitydesign.Intheusualmolddesignprocess,thebasicdesignprincipleshouldbefollowedtoensuretherationalityofthedesigndie,andtheseprinciplesprovidetheanalysisbasisfortheresearchofinverseCAEanalysis.TheimportantfunctionofstandarddiedesignIntherapiddevelopmentofmold,moldmanufacturingindustrytoday,Chineseoutlookisnotoptimistic,mainlyisthemoldmanufacturersunderstandingofmouldmanufacturingisnotenough,theintensityofapplicationofnewtechnologyofmold,themoldinthemoldmanufacturingprocessstandarddesignisnotenoughunderstanding,stillmakingalevelofexperiencethemoldmasterledinoldmanual,theoutlookofdevelopedcountriestomoldmanufacturing,molddesignstandardonthemostimportantposition,followedbytheequipment,management,someJapanesecompaniesdesignpersonnelaccountedfor75%,sothattheprocessingofpeoplecanconcentrateonwhatheshoulddo,fromdothedesignaccordingtothedrawings,specificationforthedesigntoensurethemoldprocessingspeedandquality,toavoidduplicationofwork,theproblemofrepeatedantirevisionism,thissuccessisreallytoomuch,justLookatourdomesticwheneveristhecomparisonoflargeorrelativelywell-knownmoldenterpriseshaveconsiderableimportancetodesignsuchas:Haier,Hisense,ChangzhouHuawei,ShanghaiLongzhou,HPandotherfamousenterprises,dothis,andcontinuetoimprovethedesignstrength,forexample:afriendsaidinZhejiangmolddevelopmentisveryrapid,equipmentismoreandmoreadvanced,isnotonthemoldquality,mainlyinYuyao,Huangyan,Taiwanandotherplaces,manymanufacturershavetodoalltheseplacesd