塑料模具设计中英文翻译006.docx
《塑料模具设计中英文翻译006.docx》由会员分享,可在线阅读,更多相关《塑料模具设计中英文翻译006.docx(26页珍藏版)》请在冰点文库上搜索。
塑料模具设计中英文翻译006
xxxxx大学毕业设计(论文)
外文文献
学院xxxxxxxxxxx
专业班级xxxxxxxxxxxxx
学生姓名xxxxxxxxxxxxxxx
指导教师xxxxxxxxxxxxxxx
A.MoldComponets
Moldsusedininjectionmoldingconsistoftwohalves;onestationaryandonemovable.Thestationaryhalfisfasteneddirectlytothestationaryplatenandisindirectcontactwiththenozzleoftheinjectionunitduringoperation.Themovablehalfofthemoldissecuredtothemovableplatenandusuallycontainstheejectormechanism.Therearemanypossiblemolddesigna,includingmultiplepiecemoldsforcomplicatedparts.Onproductionmoldingequipmentmanyarticlesmaybeshotatthesametimebytheuseofmultiplecavitymolds.Theuseofabalancedrunnersystemcarriestheplasticfromthespruetoeachindividualcavity.Atthispointhematerialpassesthroughagateintothecavity.Thegateisarestriction,smallerthentherunner,toprovideforevenfillingofthemoldcavityandtoallowtheproductstobeeasilyremovedformtherunnersystem.Withmostinjectionmoldingsystem,thearticlescanbesnappedawayfromtherunnerorspruewithoutadditionaltrimming.Prouductsthathavebeeninjectionmoldedcanusuallybeidentifiedbyfindingwherethegatewasbrokenoff.Thegatewillusuallybelocatedattheedgeorpartinglineofanobjectorinthecenterofcylindricalproduct.
Moldsareexpensive,asarethemachines.Yet,oncetheproducthasbeendesigned,moldsmade,andproductionstared,articlescanbeproducedinquantityatlowcost.Virtuallyallthermoplasticscanbeinjectionmoldedthroughvariationsinmoldandmachinedesign.
Mold(anddie)partsthataremass-producedandstandardizedinshapeanddimensionarereferredtoas“standards”(or“standardparts”).Specializedoperatorsofmillingmachines,lathes,lathes,electronicdischargemachining(EDN)equipmentandgrindersproducemoldcomponentsindependentlyofeachother,followingdetaiedmoldpartdrawings.Finally,alltheseitemscometogetherwiththestandardmoldbaseandhardwareandareassembledbythemoldmaker.Today,standardcomponentsforthemoldmakingindustryaremarketedbyanumberofcompanies.Fig.3.1.1illustratethestandardcomponentsforMolds.
Table3.1.1Statusofstandardization(1998)componentsfor
Compression,Injection,andDie-CastMold
Pos.No.
Denomination
Standard
DIN
ISO
1
Plate,plain
16760-1
6753-2
2
Plat,drilled
V16760-2
/
3
Supportpillar
DINISO10073
10073
4
Centringsleeve
16759
9449
5
Locatingguidepillar
16761
8017
6
Locatingguidebusch
16716
8018
7
Ejectorpin,cylindricalhead
1530-A
6751
8
Shoulderedejectorpin,cylindricalhead
1530-C
8694
9
Ejectorpin,conicalhead
1530-D
/
10
Flatejectorpin
1530-F
8693
11
Ejectorsleeve
16756
8405
12
Spruepullerinsert
16757
/
13
Spruebushing
16752-1
10072
14
Anglepin
/
8404
15
Locatingunit,roundandfalt
/
8406
16
Locatingring
16763
10907-1
10907-2
17
Thermalinsulatingsheet
16713
15600
18
Coolingconnectors
16766
/
BMoldConstruction
Theconstructionofthemoldforinjectionmoldingbeginswiththeworkingdrawing.Fromitthetequirementsforthemoldcanbespecified.Thesewouldincludethematerialfromwhichthemoldshouldbemade,theavailabilityofequipmentformachiningthemold,andthemoldcapacityofthediesetonthemachine.
Coldrolledsteelisanidealmaterialforlaboratorymolds,sinceitmachineswell,isfairlyinexpensive,andholdsupwellfornozzlepressureandwear.Itsmajordisadvantageisthatitwillrustquicklyunlessprotectedbymoldteleaseorwaxduringstorage.Complicatedmoldcavitiesneedspecializedmachiningandpolishing,therefore,circularcavitieswhichcanbeturnedandpolishedonthelatherequirelessequipmentandmachiningskill.
Similarmoldsmayalsobemachinedfromaluminum,andtheyhavetheadvantageofnotrusting.Excessiveweardevelopsonthesprueduetothehighnozzlepressureonthesoftaluminum,butthiscanbeovercomebytheuseofasteelcoverplateonthetopofthemold.
Anothermethodofmoldconstructionisbythecastingprocessusinganaluminumfilledepoxyresin.Thistypeofmoldisparticularlysuitedtoproductsofintricatedesignandproductsthataredifficulttomachine.Thecastepoxyisstrongandgivesgoodsurfacedetail,however,itisbrittleandshouldhaveasteeltopplateattachedtoabsorbthewearofthenozzle.Apatternoftheproductmustbesecuredormadeandplacedonamoldplate.Thedragofasmallsteelflaskisplacedaroundthepatternandtheepoxyresinispouredtofillthemoldhalf.Whenthishalfofthemoldhasbeencured,thecopeisplacedoveritandtheremainderofthemoldpoured.Uponcuring,theflaskisremoved,allsurfacesmachinedsmooth,dowelpinholesdrilled,anddowelsinserted.Asteelcapplateshouldbeboltedtothetophalvesandthesprue,runners,andgatesmachined.Instructionsformixing,pouring,andcuringthealuminumfilledepoxyshouldbefollowedaccordingtothemanufacturer’sspecifications.
2.HotRunnerSystems
Hotrunnersareclassifiedaccordingastheyareheated:
insulated-runnersystems(itisnotdescribedinthisarticle)andgenuinehot-runnersystems.
Thelattercanbefurthersub-classifiedaccordingtothetypeofheating:
internalheating,andexternalheating.
Heatingisbasicallyperformedelectricallybycartridgeheaters,heatingrods,bandheaters,heatingpipesandcoils,etc.Toensureuniformflowanddistributionofthemelt,usuallyarelativelyelaborateaontrolsystemcomprisingseveralheatingcircuitsandanappropriatenumberofsensorsisneeded.Theoperatingvoltageisusually220Vto240V,butsmallnozzlesfrequentlyhavealowvoltageof5V,andalso15Vand24Voperatingvoltage.
Runnersystemsinconventionalmoldshavethesametemperaturelevelastherestofthemoldbecausetheyareinthesamemoldblock.If,however,therunnersystemislocatedinaspecialmanifoldthatisheatedtothetemperatureofthemelt,alltheadvantageslistedbelowaccrue.Runnermanifoldsheatedtomelttemperaturehavethetaskofdistributingthemaltasfarasthegateswithoutdamage.Theyareusedforallinjectionmoldedthermoplasticsaswellasforcrosslinkingplastics,suchaselastomersandthermosets.
Inthecaseofthermoplastics,thesemanifoldsareusuallyreferredtoasthehot-runnersystem,thehotmanifold,orsimplyashotrunners.Forcrosslinkingplastics,theyareknownascoldrunners.
A.Hot-RunnerSystems
Hot-runnersystemshavemoreorlessbecomeestablishedforhighly-automatedproductionofmoldedthermoplaticpartsthatareproducedinlargenumbers.Thedecisiontousethemisalmostalwaysbasedoneconomics,i.e.productionsize.Qualityconsiderations,whichplayedamajorroleinthepast,areveryrarenowbecausethermoplasticsemployedtodayarealmostallsothattheycanbeprocessedwithoutdifficultywithhot-tunnersystemsthathavebeenadaptedaccordingly.
Hot-tunnersystemsareavailableasstandardunitsanditishardlyworthwhilehavingthemmade.Therelevantsuppliersoffernotonlyprovenpartsbutalsocompletesystemstailoredtospecificneeds.Thechoiceofindividualpartsislarge.
B.EconomicAdvantagesandDisadvantagesofHot-RunnerSystems
1.EconomicAdvantages
Savingsinmaterialsandcostsforregrind.
Shortercycles;coolingtimenolongerdeterminedbytheslowlysolidifyingrunners;nonozzleretractionrequired.
Machinescanbesmallerbecausetheshotvolume-aroundtherunners-isreduced,andtheclampingforcesaresmallerbecausetherunnersdonotgeneratereactiveforcessincetheblocksandthemanifoldblockareclosed.
2.EconomicDisadvantages
Muchmorecomplicatedandconsiderablymoreexpensive.
Moreworkinvolvedinrunningthemoldforthefirsttime.
Moresusceptibletobreakdowns,highermaintenancecosts(leakage,failureofheatingelements,andwearcausedbyfilledmaterials).
3.TechnologicalAdvantages
Processcanbeautomated(demolding)becausedonotneedtobedemolded.
Gatesatthebestposition;thankstouniform,preciselycontrolledcoolingofthegatesystem,longtlowpathsarepossible.
Pressurelossesminimized,sincethediameteroftherunnersisnotrestricted.
Artificialbalancingofthegatesystem;balancingcanbeperformedduringrunningproductionbymeansoftemperaturecontrolorspecialmechanicalsystem(e.g.adjustmentofthegapinaring-shapeddieoruseofplatesinflowchannel.Naturalbalancingisbetter).
Selectiveinfluencingofmoldfilling;needlevalvenozzlesandselectiveactuationofthempavethewayfornewtechnology(cascadegatesystem:
avoidanceofflowlines,in-molddecoration).
Shorteropeningstrokeneededcomparedwithcompeting,conventionalthree-platenmolds.
Longerholdingpressure,whichleadstolessshrinkage.
4.TechnologicalDisadvantages
Riskofthermaldamagetosensitivematerialsbecauseoflongflowpathsanddwelltimes,especiallyonlongcycles.
Elaboratetemperaturecontrolrequiredbecausenon-uniformtemperaturecontrolwouldcausedifferentmelttemperaturesandthusnon-uniformfilling.
C.DesignofaHot-RunnerSystemanditsComponents
Hot-runnermoldsareambitioussystemsinatechnologicalsensethatinvolvehightechnicalandfinancialoutlayformeetingtheirmainfunctionofconveyingmelttothegatewithoutdamagetothematerial.
D.Externally/InternallyHeatedSystems
Themajoradvantagesanddisadvantagesofthetwotypes.
E.ExternallyHeatedSystem
1.Advantage
Largeflowchannelcauselowflowrareanduniformtemperaturedistribution.
2.Disadvantage
Thetemperaturesrequiredforexternalheatinghavetobeverymu