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1、PrecisioninjectionmoldingtechnologyofprogressAuthor:MasakiMikellChenChunAbstract:Introductionaboutprecisioninjectionmoldingtechnologyofthepolymermaterials,anddiscussionaboutfactorswhichimpacttheprecisioninjectionmolding,includingtheprecisionofthemold,thecontrolaccuracyoftheinjectionmoldingmachine,th
2、eprocesscontrolofprecisioninjectionandothercomputercontroltechnology.Discussedtoeachofthesefactors,andgiventherelevantsolutions,finally,introduceanumberofadvancedmoldingtechnology.Keywords:PrecisionInjection,InjectionMachine,PrecisionInjectionMoldInrecentyears,withtherapiddevelopmentoftheelectronics
3、,telecommunications,healthcare,automotive,andotherindustries,thedemandtohigh-precisionandhighperformanceofplasticproductsisincreasingdaybyday,promptedprecisionmoldingtechnologycontinuestoprogress,newtechnologiescontinuetoemerge.Precisioninjectionmoldingproductsnotonlyrequirehighdimensionalaccuracy,l
4、owwarpage,gdtowrite,butalsorequireexcellentopticalproperties,LInjectionmoldingisthemostimportantmethodoftheplasticmolding,includingplasticsplastics,injection,andpacking,severalbasiccoolingprocess,sotherearemanyfactorswhichcanimpactprecisioninjectionmolding.1 PrecisionMoldTbcreatesophisticatedproduct
5、s,precisionmoldisessential.GenerallytheaccuracyoftheMoldcontrolledbythemoldtemperature,theprecisionmanufacturingmoldandtheselectionofplasticshrinkageratewhenmolddesign.1.1 TheControlPrecisionofTheMoldTemperatureGeneralprecisionpartsintheinjectionmolding,temperaturecontrolofmoldistoincreaseproductivi
6、ty.However,theimpactoftemperaturecontrolofmoldforprecisioninjectionmoldingisgreat，itaffectscomponentofcontraction,shape,crystallization,stressandsoon,thereforemolddesigntemperaturelooptemperaturedistributionattherequestreasonable,controlaccuracyisprecise.Wenpreferredmodecontrolandacool-watermachine.
7、Moldtemperaturecontrolandcoolingtimeonproductperformanceandtheimpactisasfollows,31:(I)MeItplasticinjectionandthecycletimeofmoldcavitycanmakefluctuationsofthetemperaturedifference,thereforebetominimizethevolatilityworsepeaks.(2)Heattransferofmoldisthroughtheconcreteandmolddiewithinthemediaaroundthewo
8、rld.Moldisunchangedandthereforecontrolofthemediaisthekey,thegeneralimportandexportofitscoolingwatertemperatureislessthan1C,applicationofthetheorytotheaveragetemperaturecalculated14,thiscanguaranteethestabilityofheattransfer.(3)Stablestateofmoldtomaintainabalancebetweenabsorptionanddistributionofheat
9、,injectionmoldingmachineshouldstrictlymaintainastabletemperature.1.2 TheDesignAndManufactureofPrecisionMoldThepremisetoguarantprecisioncomponentsizeofplasticismolddesigninordertoimprovetheprecisionofprecisioninjectionmold,usingcomputer-aidedanalysisisnecessaryinthedesignprocess,especiallyonthegating
10、systemandthebehaviorofmoldtemperaturecontrolsystemheatdistributionanalysis.1.3 TheUseofPrecisionMoldDesignShrinkageRatePrecisioninjectionmoldingmachinegenerallyhaslargerinjectionofpower,makedifficultiestomolddesign,sizeandcavitysizeprecisioncontrolproducts.Precisionplasticpartsofthedesignpriortomanu
11、facturesimplemoldtomeasurethemoldingpartoftheactualshrinkage,thiswillgreatlyimprovetheaccuracyofcomponentsize.2 BestPrecision!injectionMoldingProcessParametersSettingsTothebestmoldingprocessparameterstoreduceplasticproducts,theshrinkagerate.Partsofthewallthicknessdifferenceisgenerallyconsideredbythe
12、twofactors:.(1)Melthypertensioncausedbymoldcavityminordeformation;(2)Whenthemoldcavityflexibilityofthematerialafterexpansion.3 PrecisionInjectionMoldingMachineUsedtoReplaceConventionalInjectionMoldingMachinePrecisioninjectionmoldingmachinegenerallylargerinjectionofpower,Besidesmeetinjectionpressurea
13、ndinjectionrateofrequirements,Powerwillbeinjectingitselfontheaccuracyofacertainroleintheimprovement.3.1 TheconsistencyofmoldingcycletimeGeneraltypicalinjectionmoldingmachinewiththreemodes：manual,semi-automaticandfullyautomatic.Duetotheinfluenceofvariousfactors,intheformertwomodelsundereachmoldingcyc
14、letimevary,thiswillaffectthemoldtemperatureandmeltmaterialsintheresidencetime,therebyaffectingtheprecisionofthepartsmade,soinPrecisionmoldingshouldmaximizetheuseoffullyautomaticmodel,41.3.2 TheTemperatureControlofPrecisionInjectionMoldingMachine,AndANewDesignofScrew.Injectionbarrelautomaticthermosta
15、tonthecycleofsexualrelationsandtheopeningofthestovetomeltdensityandviscositychanges.Productsthusaffectingthequalityandaccuracyofthecyclicalfluctuations;injectionmoldingmachinenozzleclosetothemoldcavity.Therefore,thenozzletemperatureofmoldingcomponentwillhaveanimportantimpact.4 PrecisionMoldingTechno
16、logy4.1 ApplicationofTheMoldInjectionCompressionMolding(ICM)TechnologyICMTechnologyisthemeanstoopenacertaindistancefromthemoldundertheconditionsofthebeginninginjection,injectionofacertainamount,closetothebeginningdiecavitymeltimplementationofthecompression,Diecompletelyclosedattheterminationofinject
17、ion,andthenpacking,coolinguntiltheremovalproducts.4.2 TheHigh-speedInjectionMoldingHigh-speedinjectionmoldingmethodoffillingmeltsfasterthantraditionalfast10-100times,sothatmeltinamoldcavitytoproducehighshearflowandviscosity,moldfillingfast,plasticsurfacehardeningslowed,willbeenhancedthin-wallmolding
18、thicknesslimit,inhibitexcessivemoldingpressureandlow-pressuredieasmobile,products,thelowerthestress.4.3 NoGuaranteePressureInjectionMoldingWithoutpackinginjectionmoldingtechnologyisreferredtotheplasticmeltinhigh-speed,highpressurefillingintothemold,thenclosetothenozzleneedle,aplasticmoldcavitymeltau
19、tomaticallycoverallpartsoftheproductcontractionSuchproductscangreatlyreducethewarpage.4.4 OtherIntelligentControlTechnologyPrecisioninjectionmoldingprocessontheprocessingconditionsforcontinuedmonitoringandaccuratecontrolisveryimportant.Withthedevelopmentofcomputertechnology,computerizedinjectionmold
20、inghasbeenwidelyused.5 ConclusionThegrowingrequirementofplasticproductsforhighaccuracyandhighperformancerequirementsisthemomentumforsophisticatedinjectionmoldingtechnologyforward.Peopleofprecisioninjectionmoldingunderstandingoftheprincipleisthecontinuousdeepeningofprecisioninjectionmoldingtechnology
21、thebasisforprogress.Withnewmaterials,newtechniquesandnewequipmenthasemerged,particularlyplasticwidelyusedinthecomputerprocessing,tocreategoodconditionsforprecisioninjectiontechnology.Aslongasreasonableouse,wewillbeabletoproducesophisticatedproducts.References1LuoWeiHua.ApplicationEngineeringPlastics
22、,2002,30(8):272 Zhangyougen.Plasticstechnology,1990(1)3 Xiyongsheng.PrecisionInjectionMoldDesign.Beijing:ChinaLightIndustryPress,19974 Wangsongjie.PlasticsProcessing,2002,37(3):405 ChenHong.PrecisionPlasticMolding.Beijing:NationalDefenseIndustryPress,19996 Daiwenli.PolymericMaterialsScienceandEngine
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25、精密注射成型技术的研究进展作者:MasakiMikelI陈占春摘要:介绍聚合物材料的精密注射成型技术，论述影响精密注射成型的因素，包括模具的精度、注塑机的控制精度、精密注射工艺控制和其它一些计算机控制技术。分别对这些因素进行分析讨论，并给出了相关的解决方法，最后介绍了一些先进的模塑成型技术。关键词：精密注射,注塑机,精密注射模具近年来，随着电子、电信、医疗、汽车等行业的迅速发展，对塑料制品的高精度、高性能要求与日俱增，促使精密成型技术不断地进步，新的技术不断地涌现。精密注射成型要求制品不仅具有较高的尺寸精度、较低的翘曲变形、优良的转写性，而且还应有优异的光学性能等。注射成型是最重要的塑料成型方
26、法之一，包括塑料的塑化、注射、保压、冷却等几个基本的过程，因此影响精密注射成型的因素也很多。1精密模具要制造出精密的制品，精密模具是必不可少的。模具的精度一般受模具的温度控制、模具的精密制造和模具设计时对塑料收缩率选用等影响。1.1 模具温度的精密控制在一般精度零件的注射成型中，控制模具温度主要是为了提高生产率。然而模具温度控制对精密注射成型的影响极大2，它影响制件的收缩、形状、结晶、内应力等，因此设计模具冷热回路时要求温度分布合理，控制精度精确，最好采用模温机和冷水机控制。模具温度控制和冷却时间对制品性能的影响及其影响因素如下3：(1)塑料熔体注入和模具开模的循环时间二者会在模具中产生温度差
27、的波动，因此应该尽量减小这种波动差峰。(2)模具内的热量转移模具的热量是通过模具体和模具内的媒体传递出去的，模具是不变的，因此对媒体的控制是关键，一般其冷却水出入口温度差小于1,应用平均温度理论来计算【,I,这样能够保证热量传递的稳定性。(3)模具稳定状态为使模具所吸收和散发的热量保持平衡，注塑机注射出的熔体要严格保持稳定的温度。1.2 精密模具的设计与制造模具设计的好坏是保证塑料制件尺寸精度的前提，为了提高精密注塑模的精度，在设计过程中采用计算机辅助分析是必要的，特别是对浇注系统的流动行为和模具温度调节系统热量分布的分析等。1.3 精密模具设计时物料收缩率的选用热塑性塑料制品成型时收缩率波动
28、较大，给模具设计、确定型腔尺寸和控制制品尺寸精度带来困难。对高精度塑料件可在设计前先制造简易模具，以测出成型时各部位的实际收缩率，这样便可大大提高制件的尺寸精度。2精密注射成型最佳工艺参数的设定选取最佳的成型工艺参数能够减少塑料制品的收缩率。制件壁厚的差异一般认为是由两个方面的因素引起的：(1)高压熔体引起的模具型腔轻微变形；(2)当模具开模后材料的弹性膨胀。3用精密注塑机代替常规注塑机精密注塑机一般都采用较大的注射功率，这样除了可以满足注塑压力和注射速率方面的要求外，注射功率本身还会对制品精度起一定的改进作用。3.1 成型制件循环时间的一致性一般典型的注塑机有三种模式：手动、半自动、全自动。
29、由于各种因素的影响，在前两种模式下每次模塑的循环时间不尽相同，这会影响到模具温度和物料在料筒中的停留时间，进而影响到制件的精度，因此在精密成型中应尽量采用全自动的模式。3.2 精密注塑机的温度控制和新型螺杆的设计注塑机筒上自动调温器的循环性开和关导致了料筒内熔料密度和粘度的变化，从而影响制件质量和尺寸精度的周期性波动;注塑机的喷嘴紧靠模具型腔，所以喷嘴的温度对模塑制件也有重大的影响。4精密成型新技术4.1 在模具中应用注射压缩成型(ICM)技术ICM技术是指模具开启一定距离的条件下开始注射，注射到一定量后，模具开始闭合对型腔内的熔体实施压缩，模具完全闭合时注射终止，然后保压、冷却直到取出制品。
30、4.2 高速注射成型高速注射成型方法的熔体填充速度较传统的快10100倍，使熔体在模腔内产生高剪切的流动，粘度下降，充模速度快，塑料表面硬化减慢，因而可提高薄壁制品的成型厚度极限，抑制过度的成型压力，同时由于模内低压流动，制品的内应力降低。4.3 无保压的注射成型无保压注射成型技术是指将塑料熔体以高速、高压充填入模具，然后关闭设于喷嘴的针阀，以模腔内的塑料熔体自动弥补制品各部分的收缩，这样可以大大降低制品的翘曲变形。4.4 其它的智能控制技术精密注射成型过程中对加工条件实行持续性监测和精确控制非常重要。随着计算机技术的发展，计算机化的注射成型已得到广泛的应用。5结语对塑料制品高精度、高性能要求
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