机械外文翻译--机械加工.doc
本科毕业论文(设计)相关中英文翻译资料资料题目:机械加工学生姓名:所在院系:机电学院所学专业:机电技术教育完成时间:MachiningTurningTheenginelathe,oneoftheoldestmetalremovalmachines,hasanumberofusefulandhighlydesirableattributes.Todaytheselathesareusedprimarilyinsmallshopswheresmallerquantitiesratherthanlargeproductionrunsareencountered.Theenginelathehasbeenreplacedintodaysproductionshopsbyawidevarietyofautomaticlathessuchasautomatictracerlathes,turretlathes,andautomaticscrewmachines.Alltheadvantagesofsingle-pointtoolingformaximummetalremoval,andtheuseofformtoolsforfinishedonaparwiththefastestprocessingequipmentonthescenetoday.Tolerancesfortheenginelathedependprimarilyontheskilloftheoperator.Thedesignengineermustbecarefulinusingtolerancesofanexperimentalpartthathasbeenproducedontheenginelathebyaskilledoperator.Inredesigninganexperimentalpartforproduction,economicaltolerancesshouldbeused.TurretLathesProductionmachiningequipmentmustbeevaluatednow,morethaneverbefore,intermsofabilitytorepeataccuratelyandrapidly.Applyingthiscriterionforestablishingtheproductionqualificationofaspecificmethod,theturretlathemeritsahighrating.Indesigningforlowquantitiessuchas100or200parts,itismosteconomicaltousetheturretlathe.Inachievingtheoptimumtolerancespossibleontheturretlathe,thedesignershouldstriveforaminimumofoperations.AutomaticScrewMachinesGenerally,automaticscrewmachinesfallintoseveralcategories;single-spindleautomatics,multiple-spindlerapid,automaticchuckingmachines.Originallydesignedforrapid,automaticproductionofscrewsandsimilarthreadedparts,thenarrowfield,andtodayplaysavitalroleinthemassproductionofavarietyofprecisionparts.Quantitiesplayanimportantpartintheeconomyofthepartsmachinedontheautomaticscrewmachine.Thecostofthepartsmachinedcanbereducediftheminimumeconomicallotsizeiscalculatedandthepropermachineisselectedforthesequantities.AutomaticTracerLathesSincesurfaceroughnessdependsgreatlyuponmaterialturned,tooling,andfeedsandspeedsemployed,minimumtolerancesthatcanbeheldonautomatictracerlathesarenotnecessarilythemosteconomicaltolerances.Insomecases,tolerancesof±0.05mmareheldincontinuousproductionusingbutonecut.Groovewidthcanbeheldto±0.0125mmonsomeparts.Boresandsingle-pointfinishescanbeheldto±0.0125mm.Onhigh-productionrunswheremaximumoutputisdesirable,aminimumtoleranceof±0.125mmiseconomicalonbothdiameterandlengthofturn.MillingWiththeexceptionsofturninganddrilling,millingisundoubtedlythemostwidelyusedmethodofremovingmetal.Wellsuitedandreadilyadaptedtotheeconomicalproductionofanyquantityofparts,thealmostunlimitedversatilityofmillingprocessmeritstheattentionandconsiderationofdesignersseriouslywiththemanufactureoftheirproduct.Asinanyotherprocess,partsthathavetobemilledshouldbedesignedwitheconomicaltolerancesthatcanbeachievedinproductionmill.Ifthepartisdesignedwithtolerancesfinerthannecessary,additionaloperationswillhavetobeaddedtoachievethesetolerances-andthiswillincreasethecostofthepart.GrindingGrindingisoneofthemostwidelyusedmethodsoffinishingpartstoextremelyclosetolerancesandfinesurfacefinishes.Currently,therearegrindersforalmosteverytypeofgrindingmachinerequired.Whereprocessingcostsareexcessive,partsredesignedtoworthwhile.Forexample,whereverpossibletheproductioneconomyofcenterlessgrindingshouldbetakenadvantageofbyproperdesignconsideration.Althoughgrindingisusuallyconsideredafinishingoperation,itisoftenemployedasacompletemachiningprocessonworkwhichcanbegrounddownfromroughconditionwithoutbeingturnedorotherwisemachined.Thusmanytypesofforgingsandotherpartsarefinishedcompletelywiththegrindingwheelatappreciablesavingsoftimeandexpense.Classesofgrindingmachinesincludethefollowing:cylindricalgrinders,centerlessgrinders,internalgrinders,surfacegrinders,andtoolexpense.Thecylindricalandcenterlessgrindersortaperwork;thussplines,shafts,andsimilarpartsaregroundoncylindricalmachineseitherofthecommon-centertypeorthecenterlessmachine.Threadgrindersareusedforgrindingprecisionthreadsforthreadgages,andthreadsonprecisionpartswheretheconcentricitybetweenthediameteroftheshaftandpitchdiameterofthreadmustbeheldtoclosetolerances.Theinternalgrindersareusedforgrindingofprecisionholes,cylinderbores,andsimilaroperationswhereboresofallkindsaretobefinished.Thesurfacegrindersareforfinishingallkindsofflatwork,orworkwithplainsurfaceswhichmaybeoperateduponeitherbytheedgeofawheelorbythefaceofagrindingwheel.Thesemachinesmayhavereciprocatingorrotatingtables.