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法向等厚旋转曲面体的模具型腔计算.pdf

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法向等厚旋转曲面体的模具型腔计算.pdf

法向等厚旋转曲面体的模具型腔计算胡满红,马长安,王立军中北大学,山西太原030051摘要在工业领域中,不少产品的零件结构采用法向等厚旋转曲面体。在航天航空领域,为适应飞行需要,一些飞行器如火箭、导弹的外形也大多采用法向等厚的旋转曲面。在制造生产这类零件时,常会碰到这些零件的模具型腔计算问题。为此,本文在理论曲面坐标下,经法向等厚条件,求出了实际模具型腔的坐标值,导出了获得实际模具型腔的精确计算算法和近似计算公式,并给出计算示例,说明对这些公式的具体应用。关键词法向等厚旋转曲面模具型腔近似计算中图分类号TH123.1文献标志码A航空航天工程中的飞行器种类很多,如火箭、导弹等,虽然外形不一,但大致相似,大多采用旋转曲面。其曲面的旋转半径从0开始增大,增长率是非线性的,开始较快,而后渐趋缓慢,成为流线型的外表。而其内腔一般是空的,为的是减轻重量或者是放置必需的物件。而曲面的壁厚常常采用法向等厚结构。这样的外形和壁厚设计,不仅有利于减小飞行阻力和增强飞行器的强度,而且有利于简化飞行器外形、内壁以及制造用工模具的设计计算。1法向等厚旋转曲面及其模具旋转曲面有着良好的机械加工工艺性。在三维空间内,设x轴是旋转轴线,在xoy平面内有一条图1法向等厚旋转曲面体流线型平面曲线,它绕x轴旋转,即得到一旋转曲面,见图1。这条流线型曲线称为理论曲线,它绕x轴旋转而得的曲面称理论曲面。设想在理论曲线旁有一条与它法向等宽的另一条平面曲线,该条曲线也绕x轴旋转,即得到另一个相对于理论曲面的法向等厚旋转曲面,2个曲面的结合,就成为飞行器的外形。加工制造这样的飞行器,常需要进行模具设计。模具型腔由阴模和阳模拼合而成,阴模内腔成型产品之外形,即理论曲面。阳模的外形,即产品的内壁。通常理论曲线由一解析函数式或一系列坐标值给出,而理论曲线的等宽线也称实际曲线或阳模外形曲线不给出相应的坐标值,只是给出等宽值H。在计算机绘图时,可以利用理论曲线和法向等厚条件,绘出实际曲线。但是所绘理论曲线的精度要受到绘图软件插补误差的影响。因此对精度要求较高的零件,需要算出实际曲线的准确坐标值,准确到工程上可以允许的范围。2计算公式如图2所示,理论曲线对称于x轴,相切于y轴,切点就是原点o,以这样的位置关系给出理论曲线的解析函数式Rufx0≤x≤w1图2等宽曲线图示图3实际曲线近似求解图通常它是一条光滑、连续可导、二次或更高次的曲线。为使导出公式具有普遍性,在曲线L1上任取一点MxM,yM,过M点作曲线L1的切线,与x轴夹角为αM,由高等数学知αMarctandydx2再过M点作L1的法线,并在法线上取长度H等宽值,得M点的等宽对应点mxm,ym,由简单几何关系得xmxMHsinαMymyMHcosαM3利用公式3可以计算出理论曲线L1上一系列的点Mi的对应等宽点mi,从而描绘出与理论曲线L1对应的等宽线L2。但在工程上,为加工、测量、检验的方便,希望给定一个自变量xM后,可以在理论曲线L1上直接找到一个因变量yM也可以在实54新技术新工艺数字技术与机械加工工艺装备2008年第8期际曲线L2上直接找到因变量yn见图2。即对应于xxMxn,可以直接求出理论曲线L1上M和实际曲线L2上n两点的y值即yM和yn。M点的y值yM,可以通过解析函数式求出。而n点的y值yn则要通过图3来求解,具体做法是过理论曲线L1上M点作平行于y轴的直线,交实际曲线L2于n点然后再过M点作理论曲线L1的法线,交L2于m点。由m点作Mn的垂线并交Mn于n△,由图3知,n△点位于曲线L2上方,接近于n点,其y轴坐标值为ymynΔyMHcosαM4公式4所得ynΔ可视为yn的近似值。虽然是近似,但随着自变量x的增大,它的近似程度会越来越高,最后近似到工程上需要的精度,这就可以代替准确值计算,这在以下计算示例中可以明显看出。但在自变量x还不大,在同一步长下离散坐标计算中αM变化较大时,ynΔ和yn差值还比较大,因此,不能以ynΔ代替准确的yn。所以,可利用实际曲线上L2上的n点和理论曲线L1上N点的一一对应关系,由L2上n点去找出L1上的N点。再经N点和等宽条件H精确计算出n点的纵坐标yn。但实际曲线L2没有具体函数式,所以反推过去只能采用试算法。待试算满足条件后,再准确地算回来。下面是试算过程在图3上,过n点作nNΔ平行于Mm,交L1于NΔ,可以将xNΔ作为xN的近似值,显然有xNΔxMHsinαM5实际xN70时,误差值还会更小,故可以认为ynΔyn,因此有表2的计算结果。表2x≥70实际曲线yn的计算数值xM7080100120140yM66.1469.9976.6082.0786.60αM22.05°20.03°16.69°13.97°11.65°ynynΔ62.9166.7973.4778.9783.54xM160180200220240yM90.3593.4195.8397.6898.97αM9.62°7.78°6.08°4.48°2.95°ynynΔ87.3190.3892.8194.6795.974结语推导了法向等厚旋转曲面理论曲线的对应等宽点的准确计算公式以及给定自变量,实际曲线L2上对应点y值的准确计算法和近似计算公式。在模具型腔设计计算中,y值的准确计算算法简便易行,便于实现当自变量在一定范围内,近似计算公式计算结果误差值在103mm以内,完全满足一般工程允许范围,适合实际工程应用,有极大的实用价值。参考文献1颜庆津.数值分析M.北京北京航空航天大学出版社,1999.2张国志.材料成型模具设计M.沈阳东北大学出版社,2006.3王俊生.有翼导弹结构设计图册M.北京宇航出版社,1992.作者简介胡满红19712,女,山西运城人,讲师,硕士,研究方向为飞行器制造工程。收稿日期2008年4月8日责任编辑周守清74新技术新工艺实用技术与工艺装备2008年第8期processcontroltechnology,machiningautomationtechnolo2gy,andpresentthatdata,function,processofmodulesabovecanbeintegratedbyproductdatamanagementtechnologyandcorporationscanconstructcontemporaryintegratedhar2nessmanufacturingsystembasedonit.Keywordswiringharnessmanufacturingequipmentcontem2poraryintegratedharnessmanufacturingsystemPDMdataintegrateResearchonGearToothCorrectinginHeavyLoadVehicleTransmissingSystemJIAShuang1,WANGYanzhong21.StateKeyLabofVehi2cleTransmissionofChinaNorthVehicleResearchInstitute,Beijing100072,China2.BeijingUniversityofAeronauticsandAstronautics,Beijing100083,ChinaAbstractThepaperdiscussestheobjectiveandsignificanceofgeartoothcorrectingandintroducescommoncorrectingmethods.32Dcorrectingiselaboratedinanexampleofgearinheavyloadvehicletransmissionsystem.Basingonthea2nalysisofdeformationandstiffnessofthetransmissionsys2tem,32Dcorrectingquantityisaccountedaccordingtothe32Dcorrectingsurfaceandminimumprincipiaofloaddensity.Theexperimentsbeforeandafterthecorrectingindicatetheadvantagedeffectsofgeartoothcorrecting,andthedeflectedloadofthegearintransmissionsystemisremoved.Keywordsgeartoothcorrectingelasticdeformationdeflec2tedloadmeshstiffness32DcorrectingFatigueLifePredictionMethodsofNotchedSpeci2menBAIHe,WANGBojianDepartmentofMetallurgyEngineer2ing,XianUniversityofArchitectureandTechnology,Xian710055,ChinaAbstractThelifepredictionmethodsofnotchedspecimenarereviewed,especiallyonnominalstressapproach,localstress2strainmethodandstressfieldintensityapproach.Itintro2ducestheprinciples、applicationmethods、rangeofapplica2tion、advantagesanddisadvantagesofthefatiguelifepredic2tionmethodofnotchedspecimen.Andpresentresearchsta2tusanddevelopmentareintroduced.Keywordsnotchedspecimennominalstressapproachlocalstress2strainmethodstressfieldintensityapproachNormalUniformThicknessRevolvingCurvedSur2faceBodyMoldCavityComputationHUManhong,MAChang2an,WANGLijunNorthUniversi2tyofChina,Taiyuan030051,ChinaAbstractIntheindustrialfield,anumberofproductpartsstructurehadusednormaluniformthicknessrevolvingcurvedsurfacebody.Intheaerospace,tomeetoperationalneeds,normaluniformthicknessrevolvingsurfaceismoreof2tenbeadoptedinsuchaircraftasrocketsandmissiles.Intheproductionofsuchparts,oftenencountertheproblemsofmoldcavitycalculationfortheseparts.Therefore,basedonthetheoryofsurfacecoordinates,thispapercalculatedthecoordinateoftherealmoldcavityontheconditionofnormalequal2thickness,obtainedtheaccesstotheactualmoldcavityoftheprecisecalculationofalgorithmsandapproximatecal2culationformula.Intheendofthispaper,anexampleispro2videdtoillustratetheapplicationofthesespecificequations.Keywordsnormaluniformthicknessrevolvingcurvedsur2facemoldcavityapproximatecalculationProcessOptimizationExperimentResearchontheNewLappingModeoftheHardnessMaterialSphereXUQin1,YUANJulong1,ZHOUZhaozhong2,LVBinghai31.PERCZhejiangUniversityofTechnology,Hangzhou310014,China2.WestBranchofZhejiangUniversityoftechnology,Quzhou324000,China3.HunanUniversity,Changsha410000,ChinaAbstractSiliconnitrideceramics,oneofthemosttypicalhardnessmaterialsphere,haveexcellentpropertieslikesmalldensity,highrigidity,highYoungsmodulus,highwearabili2ty,goodthermalstabilityandchemicalstability,whichmakeitbecomeoneofthemostappropriatematerialsforrollersofhighprecisionbearing.ButthetraditionalV2grooveabrasivelappingprocessmakesithardtohavethefurtherapplica2tions.TofigureoutabetterprocessonnewRDPlappingmode,taguchimethodisappliedtooptimizelappingparame2terstoobtainthebetterMRR,sphericityandsurfacefinish.Influenceofparametersinvolving,includingload,speed,andslurryconcentrationisdiscussedandtheoptimumlappingconditionsarefiguredout.KeywordshardnessmaterialspheretaguchimethodprocessoptimizationStudyonDigitalRemanufacturingTechnologyforVehicleEnginesHUANGYanbin,SONGGaowei,ZHANGQiyong,BAGuozhaoDepartmentofEquipmentRemanufacturing,Acad2emyofArmoredForcesEngineering,Beijing100072,ChinaAbstractAtpresent,thedigitalremanufacturingofvehicleengineshasdeveloped,butitisstillatthepreliminarylevel,mostofremanufactureprocesseskeeptraditionaltechniquesandlowproductionefficiency,especiallylowinformationtechnical.Therefore,inthispaper,thearchitecture,techno2logicalprocessandprocessplanningareestablishedwhichisbasedondigitalfactory,andlaythefoundationforresearchandapplicationofthedigitalremanufacturingofvehicleen2gines.KeywordsdigitalfactoryremanufacturingarchitecturetechnologicalprocessprocessplanningMathematicalModelofMicrostructureandMechan2icalPropertiesPearliteNodularCastIronXUZhixing,ZHUXianyongInstituteofMechanicalScienceandEngineering,JilinUniversity,Changchun130025,ChinaAbstractThecompositions,volumefractionofpearlite,ratioofshpericityandmechanicalpropertiesofthepearlitenodulecastironaremeasured.Basedonthemethodoflinearre2gressionmulti2analysis,themodelsabouttheeffectsofthealloycompositionsonmicrostructureandmechanicalproper2tiesofthepearlitenodulecastiron,andthedependenceofthecontentsofpearliteandferriteontheratioofshpericity,in2tension,hardnessandelongationareestablished.Therela2tionsofalloyingelementsandmicrostructureandpropertiesarestudied.33groupsand9groupssamplesareelectedfrom42groupstestdataasstudydataandvaliditydatarespective2ly,theunknowndatacanbepredictedusingthismathemati2calmodel.Theresultsindicatthatthemethodcanaccuratelypredicatethecontentsofpearliteandmechanicalpropertiesofthenodulecastiron,composition,microstructureandme2chanicalproperties.KeywordsnoduleironcastpearlitemechanicalpropertiesmathematicalmodelSelectionofSpecificParametersofGrindingWheelforHigh2TemperatureAlloyBasedonFuzzyTheoryWENYifang1,RUIYannian2,ZHOUHongying11.SuzhouIndustrialVocationalandTechnicalCollege,Suzhou215104,China2.SuzhouUniversity,Suzhou215021,ChinaAbstractGrindingresearchersarestudyinghowtoselectthespecificparametersofgrindingwheelforhigh2temperaturealloyinarightway.AMathematicalModelofselectionofspecificparametersofgrindingwheelforhigh2temperaturealloybasedonfuzzytheoryisproposedinthispaper,whichusesTitaniumAlloyasmainresearchingobject,issyntheticallyevaluatedbyfuzzytheoryandentitledwiththeexperienceofexpertsandex2perimentalresearch.Theconclusionshowstheadvance,reliabili2tyandpracticabilityofthismethod.Keywordsfuzzytheoryhigh2temperaturealloyselectionofspecificparametersReliabilityDiscussofLead2freeWeldingUsedintheRailwaySignalProductsFENGGuofangBeijingRailwaySignalFactory,Beijing102613,ChinaAbstractThispaperdiscussesthereliabilityoflead2free2新技术新工艺英文摘要2008年第8期

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