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塑料内应力控制.doc

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塑料内应力控制.doc塑料内应力控制InternalstresscontrolofplasticsTime:2007-04-2410:03source:Alibabaforumtextselection:largeandsmallplasticplasticstressisakindofinternalstressintheplasticmeltintheprocessbecauseoftheorientationandthecoolingshrinkagefactorofthemolecularchainandthering・Theessenceofinternalstressisnotbalaneedconformationofmolecularchainformedinthemeltingprocess,theimbalanceintheconformationofcuringnotimmediatelycoolingreturntotheequilibriumconformationandadapttoenvironmentalconditions,theimbalanceofhighelasticdeformationoftheconformationisakindofreversible,highelasticdeformationandtheusualtofreezeenergystoredinplasticproducts,undersuitableconditions,icenergyrelease・icenergy,theinternalstressbalaneeisdestroyed,andtheplasticproductswillcausestresscrackingandwarpage・Almostallplasticproductswillhavevaryingdegreesofinternalstress,especiallyplasticinjectionproductsaremoreobviousstress・Theexistenceofinternalstressnotonlycauseswarpageandcrackingofplasticproductsduringstorageanduse,butalsoaffectsthemechanicalproperties,opticalproperties,electricalpropertiesandappearancequalityofplasticproducts・Forthisreason,wemustfindouttheinternalstressesandtoeliminateinternalstressandreducethestressinsidetheplasticproducts,andtheresidualstressintheplasticproductsaredistributedasevenlyaspossible,toavoidthephenomenonofstressconcentration,,suchasplasticmeltbystrongershearinthemachiningprocess,orientationandcrystallizationprocessinthepresenceofmelt,allpartsofthecoolingspeedisextremelydifficulttoachieveuniformandnonuniformplasticization,demolding,whichwillleadtointernalstress・Accordingtothecausesofinternalstress,stresscanbedividedintothefollowingcategories・orientationinternalstress:Theorientationinternalstressisakindofinternalstressproducedbytheplasticmeltintheprocessofflowfillingandholdingandfeeding,andthemacromolecularchainsarearrangedalongtheflowdirectionandthedirectionalconformatio

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