已阅读5页,还剩23页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
COMPUTER-AIDEDCNCPROGRAMMINGFORTHEMACHININGOFNON-TYPICALPARTSGrzegorzNikielGrzegorzNIKIEL,Ph.D.,Eng.,UniversityofBielsko-Biaa,DepartmentofManufacturingTechnologyandAutomation,43-309Bielsko-Biaa,ul.Willowa2,gnikielath.bielsko.pl1.IntroductionManymanufacturingfirms,especiallymediumandsmall,hastosolveproblemofproductiondevelopmentandsearchofnewcustomers.Inmanycasesthisleadstotheassortmentenlargingofalreadymanufacturedproducts.Oftenthisisjoinedwithimplementationofthenewmanufacturingprocesses.InconditionsofmarketcompetitionitdemandshighflexibilitywhichisoftengotinwayreplacingofconventionalmanufacturingresourcesbythemodernCNCtoolmachines1.Thisisessentialsconditionformoreefficientdevelopment,higherqualityandfasteradoptiontonewrequirements2.FormaintenanceofthelowcostsofmanufacturingforproductionofsmallandmediumbatchesveryoftentheGroupTechnologyisapplied3.Withhelpofgroupingofthemanufacturedcomponentsintofamiliesmoreefficientthemachines,devices,workersareused.IntheprocessesplanningonefrommostimportanttasksistheCNCmachinetoolprogramming4,5.VeryoftentheCAD/CAMsystemsareusedfromreasontheirpossibilityofflexibleprogramming.Inthecaseoftypicalcomponentssuchapproachthepositiveresultsgives,thoughitdemandsanefficientco-operationsbetweenconstructorsandtechnologist.Sometimesfromdifferentreasonsitisimpossible,especiallywhentheGroupTechnologyisapplied.Usuallythepartprogramsformachiningofsinglecomponentsarecreated,butthemodernCNCcontrollersoffersomemethodsofprogramming,whichtomachiningofsomesimilarcomponentscanbeused.Suchmethodsare:1.Cycles6.Thecyclesaredesignformachiningoftypicalsurfaces(theholes,threads,slotsetc.).Usuallyaparametricdescriptionofmachinedsurfacesisappliedwhichenabletheeasyandfastchangesoftheirgeometry.Unfortunatelytheybecharacterizedbysmallflexibilityandsmallinfluenceontostrategyofmachining,dependentonlyfromtheparametersofcycle.InthemoderncontrollersitpermitontoaWorkshopOrientedProgramming(WOP),grammingdirectlybytheoperators,oftenaidedbyadialogprogramming(sometimesaconversationalprogrammingcalled).Thereforethisisrelativesimpleprogrammingmethod,veryoftenusedinindustrialpractice.2.Parametricprogramming5,6.Atypicalpartprogramisexecutedfrombeginningtoendinonerun.Inparametricprogrammingtheexecutionofpartprogramcanrunintodifferentway(e.g.byconditionalinstructionIF.THEN.use).Inaddition,amultiplerepetitionofthepartprogramfragmentisaccessible(REPEATloop,WHILEloopetc.).Furthermore,thearithmeticalfunctionsandotheradvancedfunctionsarepossible.Theaxispositions,feedandspeedfunctions,etc.canbespecifiedbyaparametricexpressions(byR-parametersuse).Intothiswayitwasbeenpossibletocreateownmachiningcyclesalso.Thisapproachdemandshighskillsofprogrammingandisverylabour-consumingalso.Exactverificationoftheprogramisnecessary,inthisitsimmunityinthedangeroussituations(e.g.joinedwithapplicationofincorrectvalueoftheinputparameters).Thereforeinviewofabovementioneddefectsitisinfrequentlyusedinindustrialpractice.3.Programmingbasedonthefreelydefinedcontours.ThetaskdependsondefiningofmachinedcontouranditsautomaticconversiontotheCNCcodes.Iftheautomaticcutterradiuscompensation(theG41andG42functions)isnotusedthenadditionallyaequidistanthastobegenerated.Thissub-taskiseasytorealizationifmentionedcontourisrepresentedinaCADsystemwithhelpoftheOffsetfunction.Secondsub-taskoftenisrealizedinwayofexportofgraphicformofthetoolpathtothetypicalformatsofdataexchange(DXF,HPGLetc.).Innextstepbythesuitablepostprocessorsuse(forexamplethesolutiongivenin7)conversionoftoolpathontotheCNCcodesisperformed.Frompracticalregardsthisapproachingeneralityforthesimpleoperationsisapplied,e.g.alasercutting,awaterjetcuttingetc.Asolutionintegratingbothsub-tasksinoneapplicationprogramareappliedalsotheAutoCUTisthebestexample8.Inpracticethissolutionisnotappliedtoooftenalthoughitpossessesmanyadvantages.IntheconditionsofsmallbatchproductionaprocessplanningtotheCNCprogrammingisoftenrestricted9.InthissituationlargemeaninghasintegrationoftheCAD/CAMsystemswithomissionofCAPPstage.TheFeaturesideaisthenaeffectivemethodofdataexchange10,11,12.WhentheGroupTechnologyisused,aftersupplementbyappropriatedatabasesandknowledgebases,itcanbebestsolutionforproductionoftypicalelements13,14.Incaseofnon-typicalpartssuchapproachgenerallyisineffective.MainlyinviewofthewidelyappliedmethodsofFeaturesrecognizingwhichlimitnumberoftheFeaturetypes10,12.MaybeinfutureasolutionwillbringintegrationofCAD/CAM/CNCsystemsbasedontheSTEP-NCstandards(ISO14649,ISO10303:238)15,16whichwillreplacetraditionallyappliedCNCprogrammingwithG-codesontothingoftheneutralformatofdataexchange.2.AnalysisoftheexamplesPresentedbelowexamplesofthegroupCNCmachiningareafragmentofproductionprogramfromthesmallfirm.Generallythiscomponentshavenon-typicalshapes,theyaremanufacturedfromhardmaterials(e.g.austeniticstainlesssteel),usuallyneededthespecialjigsandfixtures,intheconditionsofsmallbatchproduction.Theplanningprocessesinthiscasedemandaparticipationoftechnologistswithlargeexperience.AspecificcharacterofaccessibletoolmachinesfordefiningofthemethodofCNCprogrammingshouldtoconsideralso.Afterexecutionofdetailedanalysisontosubjectofthediscussedmethodsthefollowingconclusionswereformulated:Themachinedshapesexcludeapplyingofthestandardcycles.Mostoftheprogramsisdesignforthecomplicatedprofilesmachining.Fromheredescriptionoftheseprofilesislargestproblem.Moreover,machiningofthecomponentsisperformedonthedifferenttoolmachines,equippedindifferentcontroller.Formostofmachinedcomponentstheexactdrawingdocumentationisnotmade.Inaproductionorderthegeneraldrawingsareincluded,oftendescribedbyparametricdimensions.Thencurrentvaluesofthisparametersaregivenalso.Shortseriesandlargevarietyofthecomponentsdemandsfastmodifyingofcurrentproductionprogram.FastCNCprogrammingandtheprogramsimplementationisnecessary,bestdirectlyattoolmachine(WOP).Oftentheoperatorsoftoolmachinespossesslargeknowledgeandexperienceintheareaofmanufacturingtechnology,sufficientforpreparationofsimpleprogram(inrangeofthetechnology).Fastpreparationofthetoolpathislimitationonly.Generalconclusionissuch,thatinpresentedcaseuseoftheuniversalCAD/CAMsystemsforCNCprogrammingisverydifficult.Moreover,itjoinswithhighcostsofshoppingandtrainingsfortheworkers.Lowflexibilityofthismethodisexpectedalso,especiallytimeofprogrammingcanbeagreatproblem.Inthissituationaparametricprogrammingasthebestsolutionwasconsidered.But,asitwasshewontheexamples,theparametricprogrammingcanberealizedindifferentway.2.1.ExampleIthegroovedrollersfinishmachiningFinishmachiningofthegroovedrollersfamilywassubjectofresearch(Fig.1).Basicchangingdimensions
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 高考英语复习-Unit-1-Olympic-History-重庆大学版必修市赛课公开课一等奖省名师优
- 2023年病句真题答案
- 2023年成人斯蒂尔病诊断及治疗指南
- 2023年常州工程职业技术学院单招职业技能模拟试题及答案解析
- 2023年浙江省全国建设工程造价员资格考试真题
- 第三节英国的广播电视业
- 电力电气元件项目建议书范文
- 内科学:呼吸系统疾病试题五
- 内科学(医学高级):呼吸系统疾病考试答案(强化练习)
- 2024年04月浙江省嘉兴市秀洲区农业农村和水利局2024年公开招考1名编外人员笔试历年(难与易错考点)高频考题后附答案详解
- 银行英语服务用语实用口语大全范文
- 烤漆房维护保养记录表
- 地铁培训课件:科安达TAZ IIS295型计轴设备
- 健康生活方式系列顺口溜
- 污水厂AB法设计计算书(DOC)76页
- 模具加工制作流程(参考模板)
- 化工厂拆除施工方案作业方案
- 合伙人合作协议书完整
- (word完整版)2021年春季高考学前教育专业理论试题
- 税务局长青年干部座谈会讲话
- PVC膜质量标准及检验操作规程
评论
0/150
提交评论