半闭环数控车床总体设计开题报告

欢迎下载本文档参考使用，如果有疑问或者需要CAD图纸的请联系q1484406321编号无锡太湖学院毕业设计（论文）相关资料题目： 半闭环数控车床总体设计 信机 系 机械工程及自动化专业学 号： 0923007学生姓名： 陈小康 指导教师： 许菊若 （职称：副教授 ） （职称： ）2013年5月25日目 录一、毕业设计（论文）开题报告二、毕业设计（论文）外文资料翻译及原文三、学生“毕业论文（论文）计划、进度、检查及落实表”四、实习鉴定表无锡太湖学院毕业设计（论文）开题报告题目： 半闭环数控车床总体设计 信机 系 机械工程及自动化 专业学 号： 0923007 学生姓名： 陈小康 指导教师： 许菊若（职称：副教授） （职称： ）2012年11月25日 课题来源校企合作开发课题科学依据（包括课题的科学意义；国内外研究概况、水平和发展趋势；应用前景等） 课题的科学意义在于：随着科学技术的发展，机械产品结构越来越合理，其性能、精度和效率日趋提高更新换代频繁，生产类型由大批大量生产向多品种小批量生产转化。因此，对机械产品的加工相应得提出了高精度、高柔性与高度自动化的要求。数字控制机床就是为了解决单件、小批量、特别是复杂型面零件加工的自动化并保证质量要求而产生的。 国内外研究概况：在国际市场，德国、美国、日本等几个国家基本掌控了中高档数控系统。国外的主要数控系统制造商有西门子、法拉克（FANUC）、三菱电机、海德汉等。随着国际学术及产业界对开放式数控系统研究的日益推进，我国的相关研究也越来越受到重视。经过几十年的发展，我国机床行业也形成了具有一定生产规模和技术水平的产业体系，国产数控系统产业发展迅速，在质与量上都取得了飞跃。国内数控系统基本占领了低端数控系统市场，在中高档数控系统的研发和应用上也取得了一定的成绩。 数控机床的发展趋势： 1 高速化 ：采用高速的32位以上的微处理器，可提高数控系统的分辨率及实现连续小程序段的高速、高精加工。 2 多功能化。 3 智能化：引进了自适应控制技术.自适应控制（Adaptive Control，简称AC）技术是能调节在加工过程中所测得的工作状态特性，且能使切削过程达到并维持最佳状态的技术。 4 高精度化：通过减少数控系统误差和采用补偿技术可提高数控机床的加工精度。 5 高可靠性：通过提高数控系统的硬件质量，采用模块化、标准化和通用化来提高其可靠性。 应用前景：由于产品的多样化和产品更新快是当前机械制造业的明显特点。因而多品种，中小批量生产越来越占优势。由于加工不大的占有很大的比例，这就要求加工设备有很大的灵活性，而新型产品中所需要零件的精度越来越高，形状也相当复杂，这就要求是具有高的效率和加工精度。由于以上几点具体要求结合成一体的分析，用一般的普通机床是无法满足现代社会化发展的需要。 研究内容本次设计主要考虑两大方面：数控部分和机械部件。首先进行数控车床总体方案的比较，然后确定最佳方案。通过计算确定切削用量的选择及各参数的确定。绘制出半闭环数控车床的传动系统图，数控车床总体的尺寸联系图。设计车床的部件：床身的设计，车床底座的设计，排泄装置及其尾架装置的设计。拟采取的研究方法、技术路线、实验方案及可行性分析研究办法： 通过查阅专业文献资料初步掌握数控车床总体设计的相关知识； 积极参加工厂的生产实践,在生产中学习、思考、分析; 解决生产过程中的实际问题,制定新的设计方案。通过实习对数控车床总体进行研究； 结合前期工作及其所掌握的理论知识对数控车床总体进行设计，并完成其应用前景的研究。可行性分析：数控车床主传动总体方案选择。 电动机的选择。研究计划及预期成果研究计划：2012年11月12日-2012年12月2日：按照任务书要求查阅论文相关参考资料，填写毕业设计开题报告书。2012年12月3日-2013年3月1日：填写毕业实习报告。2013年3月2日-2013年3月8日：按照要求修改毕业设计开题报告。2013年3月9日-2013年3月15日：继续整理资料、分析、比较各种方案。2013年3月16日-2013年3月22日：确定最合适的总体方案。2013年3月23日-2013年4月19日：总体设计和零件设计。2013年4月20日-2013年5月21日：毕业论文撰写和修改工作。预期成果：预期成果设计出符合机械厂要求的通用型的，半闭环，斜床身，双轴联动，卧式数控车床，满足生产需要。特色或创新之处 设计过程中要重视设计方法和设计工具的现代化，积极推广应用价值工程。 通过阅读大量的资料，参考一系列数控车床，设计出尽量使数控车床的可靠性，加工精度，变速范围，操作宜人性，工作效率及防护结构适合实际使用。已具备的条件和尚需解决的问题 根据调研情况，半闭式数控车床的总体方案已经确定，车床部件也设计完成。 尚需解决的问题：采用半闭环控制其调式比开环要复杂，设计上也要有其自身的特点，技术难度较大。指导教师意见 指导教师签名：年 月 日教研室（学科组、研究所）意见 教研室主任签名： 年 月 日系意见 主管领导签名： 年 月 日英文原文CNC machine toolsWhilethespecificintentionandapplicationforCNCmachinesvaryfromonemachinetype toanother,allformsofCNChavecommonbenefits.Herearebutafewofthemoreimportant benefitsofferedbyCNCequipment.ThefirstbenefitofferedbyallformsofCNCmachinetoolsisimprovedautomation. The operatorinterventionrelatedtoproducingworkpiecescanbereducedoreliminated.ManyCNCmachinescanrununattendedduringtheirentiremachiningcycle,freeingtheoperatortodoother tasks.ThisgivestheCNCuserseveralsidebenefitsincludingreducedoperatorfatigue,fewer mistakescausedbyhumanerror,andconsistentandpredictablemachiningtimeforeach workpiece.Sincethemachinewillberunningunderprogramcontrol,theskilllevelrequiredof theCNCoperator(relatedtobasicmachiningpractice)isalsoreducedascomparedtoamachinistproducingworkpieceswithconventionalmachinetools.ThesecondmajorbenefitofCNCtechnologyisconsistentandaccurateworkpieces.TodaysCNCmachinesboastalmostunbelievableaccuracyandrepeatabilityspecifications.Thismeans thatonceaprogramisverified,two,ten,oronethousandidenticalworkpiecescanbeeasily producedwithprecisionandconsistency.AthirdbenefitofferedbymostformsofCNCmachinetoolsisflexibility.Sincethese machinesarerunfromprograms,runningadifferentworkpieceisalmostaseasyasloadinga differentprogram.Onceaprogramhasbeenverifiedandexecutedforoneproductionrun,itcan beeasilyrecalledthenexttimetheworkpieceistoberun.Thisleadstoyetanotherbenefit,fast changeover.Sincethesemachinesareveryeasytosetupandrun,andsinceprogramscanbe easilyloaded,theyallowveryshortsetuptime.Thisisimperativewithtodaysjust-in-time(JIT) product requirements.Motioncontrol-theheartofCNCThemostbasicfunctionofanyCNCmachineisautomatic,precise,andconsistentmotion control.Ratherthanapplyingcompletelymechanicaldevicestocausemotionasisrequiredon mostconventionalmachinetools,CNCmachinesallowmotioncontrolinarevolutionarymanner2.AllformsofCNCequipmenthavetwoormoredirectionsofmotion,calledaxes.Theseaxes canbepreciselyandautomaticallypositionedalongtheirlengthsoftravel.Thetwomostcommonaxistypesarelinear(drivenalongastraightpath)androtary(drivenalongacircularpath).Insteadofcausingmotionbyturningcranksandhandwheelsasisrequiredonconventionalmachinetools,CNCmachinesallowmotionstobecommandedthroughprogrammedcommands.Generallyspeaking,themotiontype(rapid,linear,andcircular),theaxestomove,theamountofmotionandthemotionrate(feedrate)areprogrammablewithalmostallCNCmachinetools.ACNCcommandexecutedwithinthecontroltellsthedrivemotortorotateaprecisenumberoftimes.Therotationofthedrivemotorinturnrotatestheballscrew.Andtheballscrewdrives thelinearaxis(slide).Afeedbackdevice(linearscale)ontheslideallowsthecontroltoconfirm thatthecommandednumberofrotationshastakenplace3. Thougharathercrudeanalogy,thesamebasiclinearmotioncanbefoundonacommontablevise.Asyourotatethevisecrank,yourotatealeadscrewthat,inturn,drivesthemovablejawonthevise.Bycomparison,alinearaxisonaCNCmachinetoolisextremelyprecise.Thenumberofrevolutionsoftheaxisdrivemotorpreciselycontrolstheamountoflinearmotionalongtheaxis.Howaxismotioniscommanded-understandingcoordinatesystems.ItwouldbeinfeasiblefortheCNCusertocauseaxismotionbytryingtotelleachaxisdrivemotorhowmanytimestorotateinordertocommandagivenlinearmotionamount4.(Thiswouldbelikehavingtofigureouthowmanyturnsofthehandleonatablevisewillcausethemovable jawtomoveexactlyoneinch!)Instead,allCNCcontrolsallowaxismotiontobecommandedinamuchsimplerandmorelogicalwaybyutilizingsomeformofcoordinatesystem.Thetwomost popularcoordinatesystemsusedwithCNCmachinesaretherectangularcoordinatesystemand thepolarcoordinatesystem.Byfar,themorepopularofthesetwoistherectangularcoordinate system.TheprogramzeropointestablishesthepointofreferenceformotioncommandsinaCNC program.Thisallowstheprogrammertospecifymovementsfromacommonlocation.Ifprogramzeroischosenwisely,usuallycoordinatesneededfortheprogramcanbetakendirectlyfromtheprint.Withthistechnique,iftheprogrammerwishesthetooltobesenttoapositiononeinchtotherightoftheprogramzeropoint,X1.0iscommanded.Iftheprogrammerwishesthetooltomovetoapositiononeinchabovetheprogramzeropoint,Y1.0iscommanded.Thecontrolwill automaticallydeterminehowmanytimestorotateeachaxisdrivemotorandballscrewtomake theaxisreachthecommandeddestinationpoint.Thisletstheprogrammercommandaxismotioninaverylogicalmanner.Alldiscussionstothispointassumethattheabsolutemodeofprogrammingisused.ThemostcommonCNCwordusedtodesignatetheabsolutemodeisG90.Intheabsolutemode,theendpointsforallmotionswillbespecifiedfromtheprogramzeropoint.Forbeginners,thisisusuallythebestandeasiestmethodofspecifyingendpointsformotioncommands.However,thereisanotherwayofspecifyingendpointsforaxismotion.Intheincrementalmode(commonlyspecifiedbyG91),endpointsformotionsarespecifiedfromthetoolscurrentposition,notfromprogramzero.Withthismethodofcommandingmotion,theprogrammermustalwaysbeaskingHowfarshouldImovethetool?Whiletherearetimeswhentheincrementalmodecanbeveryhelpful,generallyspeaking,thisisthemorecumbersomeanddifficultmethodofspecifyingmotionandbeginnersshouldconcentrateonusingtheabsolutemode.Becarefulwhenmakingmotioncommands.Beginnershavethetendencytothinkincrementally.Ifworkingintheabsolutemode(asbeginnersshould),theprogrammershouldalwaysbeaskingTowhatpositionshouldthetoolbemoved?Thispositionisrelativetoprogramzero,NOTfromthetoolscurrentposition.Asidefrommakingitveryeasytodeterminethecurrentpositionforanycommand,anotherbenefitofworkingintheabsolutemodehastodowithmistakesmadeduringmotioncommands.Intheabsolutemode,ifamotionmistakeismadeinonecommandoftheprogram,onlyonemovementwillbeincorrect.Ontheotherhand,ifamistakeismadeduringincrementalmovements,allmotionsfromthepointofthemistakewillalsobeincorrect.AssigningprogramzeroKeepinmindthattheCNCcontrolmustbetoldthelocationoftheprogramzeropointbyonemeansoranother.HowthisisdonevariesdramaticallyfromoneCNCmachineandcontroltoanother8.One(older)methodistoassignprogramzerointheprogram.Withthismethod,theprogrammertellsthecontrolhowfaritisfromtheprogramzeropointtothestartingpositionofthemachine.ThisiscommonlydonewithaG92(orG50)commandatleastatthebeginningoftheprogramandpossiblyatthebeginningofeachtool.Another,newerandbetterwaytoassignprogramzeroisthroughsomeformofoffset.Refertofig.4.Commonlymachiningcentercontrolmanufacturerscalloffsetsusedtoassignprogramzerofixtureoffsets.Turningcentermanufacturerscommonlycalloffsetsusedtoassignprogramzeroforeachtoolgeometryoffsets.Aflexiblemanufacturingcell(FMC)canbeconsideredasaflexiblemanufacturingsubsystem.ThefollowingdifferencesexistbetweentheFMCandtheFMS:1. AnFMCisnotunderthedirectcontrolofthecentralcomputer.Instead,instructionsfromthecentralcomputerarepassedtothecellcontroller.2. Thecellislimitedinthenumberofpartfamiliesitcanmanufacture.ThefollowingelementsarenormallyfoundinanFMC:CellcontrollerProgrammablelogiccontroller(PLC)MorethanonemachinetoolAmaterialshandlingdevice(robotorpallet)TheFMCexecutesfixedmachiningoperationswithpartsflowingsequentiallybetweenoperations.HighspeedmachiningThetermHighSpeedMachining(HSM)commonlyreferstoendmillingathighrotationalspeedsandhighsurfacefeeds.Forinstance,theroutingofpocketsinaluminumairframesectionswithaveryhighmaterialremovalrate1.Overthepast60years,HSMhasbeenappliedtoawiderangeofmetallicandnon-metallicworkpiecematerials,includingtheproductionofcomponentswithspecificsurfacetopographyrequirementsandmachiningofmaterialswithhardnessof50HRCandabove.Withmoststeelcomponentshardenedtoapproximately32-42HRC,machiningoptionscurrentlyinclude:Roughmachiningandsemi-finishingofthematerialinitssoft(annealed)conditionheattreatmenttoachievethefinalrequiredhardness=63HRCmachiningofelectrodesandElectricalDischargeMachining(EDM)ofspecificpartsofdiesandmoulds(specificallysmallradiianddeepcavitieswithlimitedaccessibilityformetalcuttingtools)finishingandsuper-finishingofcylindrical/flat/cavitysurfaceswithappropriatecementedcarbide,cermet,solidcarbide,mixedceramicorpolycrystallinecubicboronnitride(PCBN)Formanycomponents,theproductionprocessinvolvesacombinationoftheseoptionsandinthecaseofdiesandmouldsitalsoincludestimeconsuminghandfinishing.Consequently,productioncostscanbehighandleadtimesexcessive.Itistypicalinthedieandmouldindustrytoproduceoneorjustafewtoolsofthesamedesign.Theprocessinvolvesconstantchangestothedesign,andbecauseofthesechangesthereisalsoacorrespondingneedformeasuringandreverseengineering.Themaincriteriaisthequalitylevelofthedieormouldregardingdimensional,geometricandsurfaceaccuracy.Ifthequalitylevelaftermachiningispoorandifitcannotmeettherequirements,therewillbeavaryingneedofmanualfinishingwork.Thisworkproducessatisfactorysurfaceaccuracy,butitalwayshasanegativeimpactonthedimensionalandgeometricaccuracy.Oneofthemainaimsforthedieandmouldindustryhasbeen,andstillis,toreduceoreliminatetheneedformanualpolishingandthusimprovethequalityandshortentheproductioncostsandleadtimes.MaineconomicalandtechnicalfactorsforthedevelopmentofHSMSurvivalTheeverincreasingcompetitioninthemarketplaceiscontinuallysettingnewstandards.Thedemandsontimeandcostefficiencyisgettinghigherandhigher.Thishasforcedthedevelopmentofnewprocessesandproductiontechniquestotakeplace.HSM provideshopeandsolutions.MaterialsThedevelopmentofnew,moredifficulttomachinematerialshasunderlinedthenecessitytofindnewmachiningsolutions.Theaerospaceindustryhasitsheatresistantandstainlesssteelalloys.Theautomotiveindustryhasdifferentbimetalcompositions,CompactGraphiteIronandaneverincreasingvolumeofaluminum3.Thedieandmouldindustrymainlyhastofacetheproblemofmachininghighhardenedtoolsteels,fromroughingtofinishing.QualityThedemandforhighercomponentorproductqualityistheresultofeverincreasingcompetition.HSM,ifappliedcorrectly,offersanumberofsolutionsinthisarea.Substitutionofmanualfinishingisoneexample,whichisespeciallyimportantondiesandmouldsorcomponentswithacomplex3Dgeometry.ProcessesThedemandsonshorterthroughputtimesviafewersetupsandsimplifiedflows(logistics)caninmostcases,besolvedbyHSM.Atypicaltargetwithinthedieandmouldindustryistocompletelymachinefullyhardenedsmallsizedtoolsinonesetup.CostlyandtimeconsumingEDMprocessescanalsobereducedoreliminatedwithHSM.Design&developmentOneofthemaintoolsintodayscompetitionistosellproductsonthevalueofnovelty.Theaverageproductlifecycleoncarstodayis4years,computersandaccessories1.5years,handphones3months.OneoftheprerequisitesofthisdevelopmentoffastdesignchangesandrapidproductdevelopmenttimeistheHSMtechnique.ComplexproductsThereisanincreaseofmulti-functionalsurfacesoncomponents,suchasnewdesignofturbinebladesgivingnewandoptimizedfunctionsandfeatures.Earlierdesignsallowedpolishingbyhandorwithrobots(manipulators).Turbinebladeswithnew,moresophisticateddesignshavetobefinishedviamachiningandpreferablybyHSM.Therearealsomoreandmoreexamplesofthinwalledworkpiecesthathavetobemachined(medicalequipment,electronics,productsfordefence,computerparts)ProductionequipmentThestrongdevelopmentofcuttingmaterials,holdingtools,machinetools,control sandespeciallyCAD/CAMfeaturesandequipment,hasopenedpossibilitiesthatmustbemetwithnewproductionmethodsandtechniques5.DefinitionofHSMSalomonstheory,Machiningwithhighcuttingspeeds.onwhich,in1931,tookoutaGermanpatent,assumesthatatacertaincuttingspeed(5-10timeshigherthaninconventionalmachining),thechipremovaltemperatureatthecuttingedgewillstarttodecrease.Giventheconclusion:.seemstogiveachancetoimproveproductivityinmachiningwithconventionaltoolsathighcuttingspeeds.Modernresearch,unfortunately,hasnotbeenabletoverifythistheorytotally.Thereisarelativedecreaseofthetemperatureatthecuttingedgethatstartsatcertaincuttingspeedsfordifferentmaterials.Thedecreaseissmallforsteelandcastiron.Butlargerforaluminumandothernon-ferrousmetals.ThedefinitionofHSMmustbebasedonotherfactors.Giventodaystechnology,highspeedisgenerallyacceptedtomeansurfacespeedsbetween1and10kilometersperminuteorroughly3300to33000feetperminute.Speedsabove10km/minareintheultra-highspeedcategory,andarelargelytherealmofexperimentalmetalcutting.Obviously,thespindlerotationsrequiredtoachievethesesurfacecuttingspeedsaredirectlyrelatedtothediameterofthetoolsbeingused.Onetrendwhichisveryevidenttodayistheuseofverylargecutterdiametersfortheseapplications-andthishasimportantimplicationsfortooldesign.Therearemanyopinions,manymythsandmanydifferentwaystodefineHSM.MaintenanceandtroubleshootingMaintenanceforahorizontalMCThefollowingisalistofrequiredregularmaintenanceforaHorizontalMachiningC