机械专业英语文章中英文对照.docx

机械专业英语文章中英文对照中英文对照机械专业英语文章品析公差系统Asystemoftolerancesisnecessarytoallowforthevariationsinaccuracythatareboundtooccurduringmanufacture,andstillprovideforinterchangeabilityandcorrectfunctionofthepart.为了允许在制造过程中必然会发生的精度变化并提供零件的互换性和正确功能一个公差系统是必需的。Atoleranceisthedifferenceinadimensioninordertoallowforunavoidableimperfectionsinworkmanship.Thetolerancerangewilldependontheaccuracyofthemanufacturingorganisation,themachiningprocessandthemagnitudeofthedimension.公差是为了允许工艺上不可避免缺陷而存在的尺寸上的不同。公差范围取决于制造机构的精度、机加工过程和尺寸的量值。Thegreaterthetolerancerange,thecheaperthemanufacturingprocess.Abilateraltoleranceisonewherethetolerancerangeisdisposedonbothsidesofthenominaldimension.Aunilateraltoleranceisonewherethetolerancezoneisononesideonlyofthenominaldimension,inwhichcasethenominaldimensionmayformoneofthelimits.公差范围越大则制造过程的成本就越低。双向公差是在公称尺寸两侧都有公差带的公差。单向公差是仅在公称尺寸一侧有公差带的公差在这种情况下公称尺寸成了两个极限中的一个。Limitsaretheextremedimensionsofthetolerancezone.Forexample,nominaldimension30mm极限是公差带的极限尺寸。例如公称尺寸30毫米Fitsdependontherelationshipbetweenthetolerancezonesoftwomatingparts,andmaybebroadlyclassifiedintoaclearancefitwithpositiveallowance,atransitionfitwheretheallowancemaybeeitherpositiveornegative(clearanceorinterference),aninterferencefitwheretheallowanceisalwaysnegative.配合取决于两配合零件公差带之间的关系并且可以概括地分为具有正允差的间隙配合允差可以是正或负的过渡配合和总是负允差的过盈配合。经典中英文对照机械专业英语文章TypeofLimitsandFits极限和配合的类型TheISOSystemofLimitsandFits,widelyusedinanumberofleadingmetriccountries,isconsiderablymorecomplexthantheANSIsystem.在一些最主要采用公制的国家中广泛使用的ISO的极限和配合系统，比ANSI的极限和配合系统要复杂得多。Inthissystem,eachparthasabasicsize.Eachlimitofsizeofapart,highandlow,isdefinedbyitsdeviationfromthebasicsize,themagnitudeandsignbeingobtainedbysubtractingthebasicsizefromthelimitinquestion.Thedifferencebetweenthetwolimitsofsizeofapartiscalledthetolerance,anabsoluteamountwithoutsign.在这个系统中，每个零件都有基本尺寸。零件尺寸的每一极限，不管大小，都通过对基本尺寸的偏差来定义，其量值和符号由正被讨论的极限减去基本尺寸得到。零件尺寸的两个极限之差称为公差，这是一个没有符号的绝对量值。Therearethreeclassesoffits:1)clearancefits,2)transitionfits(theassemblymayhaveeitherclearanceorinterfere