注塑模具设计与制造外文文献翻译.docx

注塑模具设计与制造外文文献翻译.docx

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注塑模具设计与制造外文文献翻译

2Injectionmoldingmachine

FromPlasticsWiki,freeencyclopedia

Injectionmoldingmachinesconsistoftwobasicparts,aninjectionunitandaclampingunit.Injectionmoldingmachinesdifferinbothinjectionunitandclampingunit.Thenameoftheinjectionmoldingmachineisgenerallybasedonthetypeofinjectionunitused.

2.1Typesofinjectionmoldingmachines

Machinesareclassifiedprimarilybythetypeofdrivingsystemstheyuse:

hydraulic,electric,orhybrid.

2.1.1Hydraulic

HydraulicpresseshavehistoricallybeentheonlyoptionavailabletomoldersuntilNisseiPlasticIndustrialCo.,LTDintroducedthefirstall-electricinjectionmoldingmachinein1983.Theelectricpress,alsoknownasElectricMachineTechnology（EMT）,reducesoperationcostsbycuttingenergyconsumptionandalsoaddressessomeoftheenvironmentalconcernssurroundingthehydraulicpress.

2.1.2Electric

Electricpresseshavebeenshowntobequieter,faster,andhaveahigheraccuracy,howeverthemachinesaremoreexpensive.

2.1.3Hybrid

Hybridinjectionmoldingmachinestakeadvantageofthebestfeaturesofbothhydraulicandelectricsystems.Hydraulicmachinesarethepredominanttypeinmostoftheworld,withtheexceptionofJapan.

2.2Injectionunit

Theinjectionunitmeltsthepolymerresinandinjectsthepolymermeltintothemold.Theunitmaybe:

ramfedorscrewfed.

Theramfedinjectionmoldingmachineusesahydraulicallyoperatedplungertopushtheplasticthroughaheatedregion.Thehighviscositymeltisthenspreadintoathinlayerbya"torpedo"toallowforbettercontactwiththeheatedsurfaces.Themeltconvergesatanozzleandisinjectedintothemold.

ReciprocatingscrewAcombinationmelting,softening,andinjectionunitinaninjectionmoldingmachine.Anothertermfortheinjectionscrew.Reciprocatingscrewsarecapableofturningastheymovebackandforth.

Thereciprocatingscrewisusedtocompress,melt,andconveythematerial.Thereciprocatingscrewconsistsofthreezones（illustratedbelow）:

·feedingzone

·compressingzone

·meteringzone

Whiletheoutsidediameterofthescrewremainsconstant,thedepthoftheflightsonthereciprocatingscrewdecreasesfromthefeedzonetothebeginningofthemeteringzone.Theseflightscompressthematerialagainsttheinsidediameterofthebarrel,whichcreatesviscous（shear）heat.Thisshearheatismainlyresponsibleformeltingthematerial.Theheaterbandsoutsidethebarrelhelpmaintainthematerialinthemoltenstate.Typically,amoldingmachinecanhavethreeormoreheaterbandsorzoneswithdifferenttemperaturesettings.

InjectionmoldingreciprocatingscrewAnextruder-typescrewrotateswithinacylinder,whichistypicallydrivenbyahydraulicdrivemechanism.Plasticmaterialismovedthroughtheheatedcylinderviathescrewflightsandthematerialbecomesfluid.Theinjectionnozzleisblockedbythepreviousshot,andthisactioncausesthescrewtopumpitselfbackwardthroughthecylinder.（Duringthisstep,materialisplasticatedandaccumulatedforthenextshot.）Whenthemoldclamphaslocked,theinjectionphasetakesplace.Atthistime,thescrewadvances,actingasaram.Simultaneously,thenon-returnvalveclosesofftheescapepassagesinthescrewandthescrewservesasasolidplunger,movingtheplasticaheadintothemold.Whentheinjectionstrokeandholdingcycleiscompleted,thescrewisenergizedtoreturnandthenon-returnvalveopens,allowingplastictoflowforwardfromthecylinderagain,thusrepeatingthecycle.

2.2.1Feedhopper

Thecontainerholdingasupplymoldingmaterialtobefedtothescrew.Thehopperlocatedoverthebarrelandthefeedthroatconnectsthem.

2.2.2Injectionram

Theramorscrewthatappliespressureonthemoltenplasticmaterialtoforceitintothemoldcavities.

2.2.3Injectionscrew

Thereciprocating-screwmachineisthemostcommon.Thisdesignusesthesamebarrelformeltingandinjectionofplastic.

Thealternativeunitinvolvestheuseofseparatebarrelsforplasticizingandinjectingthepolymer.Thistypeiscalledascrew-preplasticizermachineortwo-stagemachine.Plasticpelletsarefedfromahopperintothefirststage,whichusesascrewtodrivethepolymerforwardandmeltit.Thisbarrelfeedsasecondbarrel,whichusesaplungertoinjectthemeltintothemold.Oldermachinesusedoneplunger-drivenbarreltomeltandinjecttheplastic.Thesemachinesarereferredtoasplunger-typeinjectionmoldingmachines.

2.2.4Barrel

Barrelisamajorpartthatmeltsresinstransmittedfromhopperthroughscrewsandstructuredinawaythatcanheatupresinstothepropertemperature.Abandheater,whichcancontroltemperaturesinfivesections,isattachedoutsidethebarrel.Meltedresinsaresuppliedtothemoldpassingthroughbarrelhead,shot-offnozzle,andone-touchnozzl