模具专业毕业设计外文翻译

本科毕业设计（论文）外文资料翻译MATERIALSELECTIONDURINGRECANTYEARSTHESELECTIONOFENGINEERINGMATERIALSHASASSUMEDGREATIMPORTANCEMOREOVER,THEPROCESSSHOULDBEONEOFCONTINUALREEVALUATIONNEWMATERIALSOFTENBECOMEAVAILABLEANDTHEREMAYBEADECREASINGAVAILABILITYOFOTHERSCONCERNSREGARDINGENVIRONMENTALPOLLUTION,RECYCLINGANDWORKERHEALTHANDSAFETYOFTENIMPOSENEWCONSTRAINTSTHEDESIREFORWEIGHTREDUCTIONORENERGYSAVINGSMAYDICTATETHEUSEOFDIFFERENTMATERIALSPRESSURESFROMDOMESTICANDFOREIGNCOMPETITION,INCREASEDSERVICEABILITYREQUIREMENTS,ANDCUSTOMERFEEDBACKMAYALLPROMOTEMATERIALSREEVALUATIONTHEEXTENTOFPRODUCTLIABILITYACTIONS,OFTENTHERESULTOFIMPROPERMATERIALUSE,HASHADAMARKEDIMPACTINADDITION,THEINTERDEPENDENCEBETWEENMATERIALSANDTHEIRPROCESSINGHASBECOMEBETTERRECOGNIZEDTHEDEVELOPMENTOFNEWPROCESSESOFTENFORCESREEVALUATIONOFTHEMATERIALSBEINGPROCESSEDTHEREFORE,ITISIMPERATIVETHATDESIGNANDMANUFACTURINGENGINEERSEXERCISECONSIDERABLECAREINSELECTING,SPECIFYING,ANDUTILIZINGMATERIALSIFTHEYARETOACHIEVESATISFACTORYRESULTSATREASONABLECOSTANDSTILLASSUREQUALITYTHEFIRSTSTEPINTHEMANUFACTUREOFANYPRODUCTISDESIGN,WHICHUSUALLYTAKESPLACEINSEVERALDISTINCTSTAGESACONCEPTUALBFUNCTIONALCPRODUCTIONDESIGNDURINGTHECONCEPTUALDESIGNSTAGE,THEDESIGNERISCONCERNEDPRIMARILYWITHTHEFUNCTIONSTHEPRODUCTISTOFULFILLUSUALLYSEVERALCONCEPTSAREVISUALIZEDANDCONSIDERED,ANDADECISIONISMADEEITHERTHATTHEIDEAISNOTPRACTICALORTHATTHEIDEAISSOUNDANDONEORMOREOFTHECONCEPTUALDESIGNSSHOULDBEDEVELOPEDFURTHERHERE,THEONLYCONCERNFORMATERIALSISTHATMATERIALSEXISTTHATCANPROVIDETHEDESIREDPROPERTYIFNOSUCHMATERIALSAREAVAILABLE,CONSIDERATIONISGIVENASTOWHETHERTHEREISAREASONABLEPROSPECTTHATNEWONECOULDBEDEVELOPEDWITHINCOSTANDTIMELIMITATIONSATTHEFUNCTIONALORENGINEERINGDESIGNSTAGE,APRACTICAL,WORKABLEDESIGNISDEVELOPEDFAIRLYCOMPLETEDRAWINGSAREMADE,ANDMATERIALSARESELECTEDANDSPECIFIEDFORTHEVARIOUSCOMPONENTSOFTENAPROTOTYPEORWORKINGMODALISMADETHATCANBETESTEDTOPERMITEVALUATIONOFTHEPRODUCTASTOFUNCTION,RELIABILITY,APPEARANCE,SERVICEABILITY,ANDSOONALTHOUGHITISEXPECTEDTHATSUCHTESTINGMIGHTSHOWTHATSOMECHANGESMAYHAVETOBEMADEINMATERIALSBEFORETHEPRODUCTISADVANCEDTOTHEPRODUCTIONDESIGNSTAGE,THISSHOULDNOTBETAKENASANEXCUSEFORNOTDOINGATHOROUGHJOBOFMATERIALSELECTIONAPPEARANCE,COST,ANDRELIABILITYFACTORSSHOULDBECONSIDEREDINDETAIL,TOGETHERWITHTHEFUNCTIONALFACTORSTHEREISMUCHMERITTOTHEPRACTICEOFONEVERYSUCCESSFULCOMPANYWHICHREQUIRESTHATALLPROTOTYPESBEBUILTWITHTHESAMEMATERIALSTHATWILLBEUSEDINPRODUCTIONAND,INSOFARASPOSSIBLE,WITHTHESAMEMANUFACTURINGTECHNIQUESITISOFLITTLEVALUETOHAVEAPERFECTLYFUNCTIONINGPROTOTYPETHATCANNOTBEMANUFACTUREDECONOMICALLYINTHEEXPECTEDSALESVOLUME,ORONETHATISSUBSTANTIALLYDIFFERENTFROMWHATTHEPRODUCTIONUNITSWILLBEINREGARDTOQUALITYANDRELIABILITYALSO,ITISMUCHBETTERFORDESIGNENGINEERSTODOACOMPLETEJOBOFMATERIALANALYSIS,SELECTION,ANDSPECIFICATIONATTHEDEVELOPMENTSTAGEOFDESIGNRATHERTHANTOLEAVEITTOTHEPRODUCTIONDESIGNSTAGE,WHERECHANGESMAYBEMADEBYOTHERS,POSSIBLYLESSKNOWLEDGEABLEABOUTALLOFTHEFUNCTIONALASPECTSOFTHEPRODUCTATTHEPRODUCTIONDESIGNSTAGE,THEPRIMARYCONCERNRELATIVETOMATERIALSSHOULDBETHATTHEYARESPECIFIEDFULLY,THATTHEYARECOMPATIBLEWITH,ANDCANBEPROCESSEDECONOMICALLYBY,EXISTINGEQUIPMENT,ANDTHATTHEYAREREADILYAVAILABLEINTHENEEDEDQUANTITIESASMANUFACTURINGPROGRESSES,ITISINEVITABLETHATSITUATIONSWILLARISETHATMAYREQUIREMODIFICATIONSOFTHEMATERIALSBEINGUSEDEXPERIENCEMAYREVEALTHATSUBSTITUTIONOFCHEAPERMATERIALSCANBEMADEINMOSTCASES,HOWEVER,CHANGESAREMUCHMORECOSTLYTOMAKEAFTERMANUFACTURINGISINPROGRESSTHANBEFOREITSTARTSGOODSELECTIONDURINGTHEPRODUCTIONDESIGNPHASEWILLELIMINATETHENECESSITYFORMOSTOFTHISTYPEOFCHANGETHEMORECOMMONTYPEOFCHANGETHATOCCURSAFTERMANUFACTURINGSTARTSISTHERESULTOFTHEAVAILABILITYOFNEWMATERIALSTHESE,OFCOURSE,PRESENTPOSSIBILITIESFORCOSTREDUCTIONANDIMPROVEDPERFORMANCEHOWEVER,NEWMATERIALSMUSTBEEVALUATEDVERYCAREFULLYTOMAKESURETHATALLTHEIRCHARACTERISTICSAREWELLESTABLISHEDONESHOULDALWAYSREMEMBERTHATITISINDEEDRARETHATASMUCHISKNOWNABOUTTHEPROPERTIESANDRELIABILITYOFANEWMATERIALASABOUTTHOSEOFANEXISTINGONEALARGEPROPORTIONOFPRODUCTFAILUREANDPRODUCTLIABILITYCASESHAVERESULTEDFROMNEWMATERIALSBEINGSUBSTITUTEDBEFORETHEIRLONGTERMPROPERTIESWEREREALLYKNOWNPRODUCTLIABILITYACTIONSHAVEMADEITIMPERATIVETHATDESIGNERSANDCOMPANIESEMPLOYTHEVERYBESTPROCEDURESINSELECTINGMATERIALSTHEFIVEMOSTCOMMONFAULTSINMATERIALSELECTIONHAVEBEENAFAILURETOKNOWANDUSETHELATESTANDBESTINFORMATIONAVAILABLEABOUTTHEMATERIALSUTILIZEDBFAILARETOFORE,ANDTAKEINTOACCOUNTTHEREASONABLEUSESFORTHEPRODUCTWHEREPOSSIBLE,THEDESIGNERISFURTHERADVISEDTOFORESEEANDACCOUNTFORMISUSEOFTHEPRODUCT,ASTHEREHAVEBEENMANYPRODUCTLIABILITYCASESINRECENTYEARSWHERETHECLAIMANT,INJUREDDURINGMISUSEOFTHEPRODUCT,HASSUEDTHEMANUFACTURERANDWONCTHEUSEOFMATERIALSABOUTWHICHTHEREWASINSUFFICIENTORUNCERTAINDATA,PARTICULARLYASTOITSKINGTERMPROPERTIESDINADEQUATE,ANDUNVERIFIED,QUALITYCONTROLPROCEDURESANDEMATERIALSELECTIONMADEBYPEOPLEWHOARECOMPLETEUNQUALIFIEDTODOSOTHECOMPUTERINDESIGNANDGRAPHICSCOMPUTERSAREWIDELYUSEDINENGINEERINGANDRELATEDFIELDSANDTHEIRUSEISEXPECTEDTOGROWEVENMORERAPIDLYTHANINTHEPASTENGINEERINGANDTECHNOLOGYSTUDENTSMUSTBECAMECOMPUTERLITERATE,TOUNDERSTANDTHEAPPLICATIONSOFCOMPUTERANDTHEIRADVANTAGESNOTTODOSOWELLPLACESTUDENTSATASERIOUSDISADVANTAGEINPURSUINGTHEIRCAREERSCOMPUTERAIDEDDESIGNCADINVOLVESSOLVINGDESIGNPROBLEMSWITHTHEHELPOFCOMPUTERTOMAKEGRAPHICIMAGESONPAPERWITHAPLOTTERORPRINTER,ANALYZEDESIGNDATA,ANDSTOREDESIGNINFORMATIONFOREASYRETRIEVALMANYCADSYSTEMSPERFORMTHESEFUNCTIONSINALLINTEGRATEDMANNER,GREATLYINCREASINGTHEDESIGNERSPRODUCTIVITYCOMPUTERAIDEDDESIGNDRAFTINGCADD,ANOFFSHOOTOFCAD,ISTHEPROCESSOFGENERATINGENGINEERINGDRAWINGSANDOTHERTECHNICALDOCUMENTSBYCOMPUTERANDISMOREDIRECTLYRELATEDTODRAFTINGTHANISCADTHECADDUSERINPUTSDATABYKEYBOARDAND/ORMOUSETOPRODUCEILLUSTRATIONSONTHEMONITORSCREENTHATCANBEREPRODUCEDASPAPERCOPIESWITHAPLOTTERORPRINTERENGINEERSGENERALLYAGREETHATTHECOMPUTERDOESNOTCHANGETHENATUREOFTHEDESIGNPROCESSBUTISASIGNIFICANTTOOLTHATIMPROVESEFFICIENCYANDPRODUCTIVITYTHEDESIGNERANDTHECADSYSTEMMAYBEDESCRIBEDASADESIGNTEAMTHEDESIGNERPROVIDESKNOWLEDGE,CREATIVITY,ANDCONTROLTHECOMPUTERGENERATESACCURATE,EASILYMODIFIABLEGRAPHICS,PERFORMSCOMPLEXDESIGNANALYSISATGREATSPEED,ANDSTORESANDRECALLSDESIGNINFORMATIONOCCASIONALLY,THECOMPUTERMAYAUGMENTORREPLACEMANYOFTHEENGINEERSOTHERTOOLS,BUTITCANNOTREPLACETHEDESIGNPROCESS,WHICHISCONTROLLEDBYTHEDESIGNERDEPENDINGONTHENATUREOFTHEPROBLEMANDTHESOPHISTICATIONOFTHECOMPUTERSYSTEM,COMPUTERSOFFERTHEDESIGNERORDRAFTERSOMEORALLOFTHEFOLLOWINGADVANTAGES1EASIERCREATIONANDCORRECTIONOFDRAWINGSWORKINGDRAWINGSMAYBECREATEDMOREQUICKLYTHANBYHANDANDMAKINGCHANGESANDMODIFICATIONSISMOREEFFICIENTTHANCORRECTINGDRAWINGSMADEBYHAND2BETTERVISUALIZATIONOFDRAWINGSMANYSYSTEMSALLOWDIFFERENTVIEWSOFTHESAMEOBJECTTOBEDISPLAYEDAND3DPICTORIALSTOBEROTATEDONTHECRTSCREEN3DATABASEOFDRAWINGAIDSCREATIONANDMAINTENANCEOFDESIGNDATABASESLIBRARIESOFDESIGNSPERMITSSTORINGDESIGNSANDSYMBOLSFOREASYRECALLANDAPPLICATIONTOTHESOLUTIONOFNEWPROBLEMS4QUICKANDCONVENIENTDESIGNANALYSISTHEDESIGNERCANEVALUATEALTERNATIVEDESIGNTHEREBYCONSIDERINGMOREPOSSIBILITYWHILESPEEDINGUPTHEPROCESSATTHESAMETIME5SIMULATIONANDTESTINGOFDESIGNSSOMECOMPUTERSYSTEMSMAKEPOSSIBLETHESIMULATIONOFAPRODUCTSOPERATION,TESTINGTHEDESIGNUNDERAVARIETYOFCONDITIONSANDSTRESSESCOMPUTERTESTINGMAYIMPROVEONORREPLACECONSTRUCTIONOFMODELSANDPROTOTYPES6INCREASEDACCURACYTHECOMPUTERISCAPABLEOFPRODUCINGDRAWINGSWITHMOREACCURACYTHANISPOSSIBLEBYHANDMANYCADSYSTEMSAREEVENCAPABLEOFDETECTINGERRORSANDINFORMINGTHEUSEROFTHEM7IMPROVEDFILINGDRAWINGSCANBEMORECONVENIENTLYFILED,RETRIEVED,ANDTRANSMITTEDONDISKSANDTAPESCOMPUTERGRAPHICSHASANALMOSTLIMITLESSNUMBEROFAPPLICATIONSINENGINEERINGANDOTHERTECHNICALFIELDSMOSTGRAPHICALSOLUTIONSTHATAREPOSSIBLEWITHAPENCILCANDONEONACOMPUTERANDUSUALLYMOREPRODUCTIVELYAPPLICATIONSVARYFROM3DMODELINGANDFINITEELEMENTANALYSISI4TO2DDRAWINGSANDMATHEMATICALCALCULATIONSONCETHEDOMAINOFLARGECOMPUTERSYSTEMSADVANCEDAPPLICATIONSCANNOWBEDONEONMICROCOMPUTERANIMPORTANTEXTENSIONOFCADISITSAPPLICATIONTOMANUFACTURINGCOMPUTERAIDEDDESIGN/COMPUTERAIDEDMANUFACTURINGCAD/CAMSYSTEMSMAYBEUSEDTODESIGNAPARTORPRODUCT,DEVISETHEESSENTIALPRODUCTIONSTEPS,ANDELECTRONICALLYCOMMUNICATETHISINFORMATIONTOANDCONTROLTHEOPERATIONOFMANUFACTURINGEQUIPMENT,INCLUDINGROBOTSTHESESYSTEMSOFFERMANYADVANTAGESOVERTRADITIONALDESIGNANDMANUFACTURINGSYSTEMS,INCLUDINGLESSDESIGNEFFORT,MOREEFFICIENTMATERIALUSE,REDUCEDLEADTIMES,GREATERACCURACY,ANDIMPROVEDINVENTORYCONTROL材料选择近些年来，工程材料的选择已经显得非常重要。此外，选择过程应该足一个对材料的连续不断的重新评价过程。新材料不断出现，而一些原有的材料的可以被利用的数量可能会减少。环境污染、材料的吸收利用、工人的健康及安全等方面经常会对材料选择附加新的限制条件。为减轻重量或者和约能源，可能要求使用不同的材料、来自国内和国际的竞争、对产品维修保养方便性要求的提高和顾客的反馈等方面的压力，都会促使人们对材料进行重新评价。由于材料选用不当造成的产品责任诉讼，已经产生深刻的影响此外，材料与材料加工之间的相互依赖关系已经被人们认识得更清楚。新的加工方法的出现，通常会促使人们对被加工材料进行重新评价。因此，为了能在合理的成本和确保质量的前提下，获得满意的结果，设计工程师和制造工程师都必须认真仔细地选择、确定和使用材料。制造任何产品的第一步工作都是设汁。设计通常可以分为几个明确的阶段A概念设计B功能设计；C生产设计。在概念设计阶段，设计者着重考虑产品应该具有的功能。通常要设想和考虑几个方案，然后决定这种想法是否可行；如果可行，则应该对其中一个或几个方案做进一步的改进。在此阶段，关于材料选择惟一需要考虑的问题是是否有性能符合要求的材料可供选用；如果没有的话，是否有较大的把握在成本和时间都允许的限度内研制出一种新材料。在功能设计或工程设计阶段，要做出一个切实可行的设计。在这个阶段需要绘制相当完整的图纸，选择并确定各种零件的材料。通常要制造出样机或者实物模型，并对其进行试验，评价产品的功能、可靠性、外观和维修保养性等。虽然这种试验可能表明，在产品进入生产阶段之前，应该更换某些材料，但是，绝对不能将这一点作为不认真选择材料的借口。应该结合产品的功能，认真仔细地考虑产品的外观、成本和可靠性。一个很有成就的公司在制造所自样机时，所选用的材料应该和其在生产使用的材料相同并尽可能使用同样的制造技术。这样做，对公司是很有好处的。功能完备的样机如果不能根据预期的销售量经济地制造出来，或者样机与正式生产的装置在质量和可靠性方面有很大不同，则这种样机就没有多大的价值。设计工程师最好能在这一阶段全部完成材料的分析、选择和确定工作，而不是将其留到生产设计阶段去做。因为，在生产设计阶段材料的更换是由其他人进行的，这些人对产品的所有功能的了解可能不如设计工程师在生产设计阶段中，与材料有关的主要问题是应该把材料完全确定下来，使它们与现有的设备相适应，能够利用现有设备经济地进行加工，而且材料的数量能够比较容易地保证供应。在制造过程中，不可避免地会出现使用中的材料做一些更改的情况。经验表明，可以采用某些便宜材料作为替代品。然而，在大多数情况下，在进行生产以后改换材料比在开始生产前改换材料所花费的代价要高。在生产设计阶段做好材料选择工作，可以避免大多数的这种材料更换情况，在生产制造开始后出现了可供使用的新材料是更换材料的最常见的原因。当然，这些新材料可能降低成本、改进产品性能。但是，必须对新材料进行认真的评价，以确保其所有性能都被人们所了解。应当时刻牢记，新材料的性能和可靠性很少能像现有的材料那样为人们所了解。大部分的产品失效和产品责任事故案件是由于在选用新材料作为替代材料之前，没有真正了解它们的长期使用性能而引起的。产品的责任诉讼迫使设计人员和公司在选择材料时，采用最好的程序。在材料选择过程中，五个最常见的问题为A不了解或者未能利用关于材料应用的最新和最好的信息资料；B未能预见和考虑产品可能的合理用途若有可能，设计人员还应进一步预测和考虑由于产品使用方法不当造成的后果。在近年来的许多产品责任诉讼案件中，由于错误地使用产品而受到伤害的原告控告生产厂家，并且赢得判决；C所使用的材料的数据不全或者有些数据不确定，尤其当其长期性能数据是如此的时候；D质量控制方法不适当和未经验证；E由一些完全不称职的人员选择材料。通过对上述五个问题的分析，可以得出这些问题是没有充分理由存在的结论对这些问题的分析和研究可以给避免这些问题的出现指明方向。尽管采用最好的材料选择办法也不能避免发生产品责任诉讼，设计人员和工业界按照适当的程序进行材料选择，可以大大减少诉讼的数量。从上面的讨论可以看出，选择材料的人们应该对材料的性质、特点和加工方法有一个全面而基本的了解。计算机在设计和制图中的应用计算机在工程和相关领域内得到广泛的应用而这种应用预计会得到越来越快的发展。工程技术专业的学生们应该通晓计算机了解计算机的用途干和它们的优点。不这样做，就会使学生们在将来的职业生涯中处于非常不利的地位。计算机辅助设计CAD是应用计算机来帮助解决设计问题这包括在视