中英文翻译(Engineering Tolerance)

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1、英文：EngineeringToleranceIntroductionAsolidisdefinedbyitssurfaceboundaries.Designerstypicallyspecifyacomponent’snominaldimensionssuchthatitfulfilsitsrequirements.Inreality,componentscannotbemaderepeatedlytonominaldimensions,duetosurfaceirregularitiesandtheintrinsicsurfaceroughness.Somevariabilityind

2、imensionsmustbeallowedtoensuremanufactureispossible.However,thevariabilitypermittedmustnotbesogreatthattheperformanceoftheassembledpartsisimpaired.Theallowedvariabilityontheindividualcomponentdimensionsiscalledthetolerance.Thetermtoleranceappliesnotonlytotheacceptablerangeofcomponentdimensionsprod

3、ucedbymanufacturingtechniques,butalsototheoutputofmachinesorprocesses.Forexample,thepowerproducedbyagiventypeofinternalcombustionenginevariesfromoneenginetoanother.Inpractice,thevariabilityisusuallyfoundtobemodeledbyafrequencydistributioncurve,forexamplethenormaldistribution(alsocalledtheGaussiand

4、istribution).Oneofthetasksofthedesigneristospecifyadimensiononacomponentandtheallowablevariabilityonthisvaluethatwillgiveacceptableperformance.ComponentTolerancesControlofdimensionsisnecessaryinordertoensureassemblyandinterchangeabilityofcomponents.Tolerancesarespecifiedoncriticaldimensionsthataff

5、ectclearancesandinterferencesfits.Onemethodofspecifyingtolerancesistostatethenominaldimensionfollowedbythepermissiblevariation,soadimensioncouldbestatedas40.000mm±0.003mm.Thismeansthatthedimensionshouldbemachinedsothatitisbetween39.997mmand40.003mm.Wherethe-22-variationcanvaryeithersideofthenomina

6、ldimension,thetoleranceiscalledabilateraltolerance.Foraunilateraltolerance,onetoleranceiszero,e.g.40+0.006.0.000Mostorganizationshavegeneraltolerancesthatapplytodimensionswhenanexplicitdimensionisnotspecifiedonadrawing.Formachineddimensionsageneraltolerancemaybe±0.5mm.Soadimensionspecifiedas15.0mm

7、mayrangebetween14.5mmand15.5mm.Othergeneraltolerancescanbeappliedtofeaturessuchasangles,drilledandpunchedholes,castings，forgings,weldbeadsandfillets.Whenspecifyingatoleranceforacomponent,referencecanbemadetoprevi