滚珠丝杠循环机构的冲击失效分析.doc

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1、Impactfailureanalysisofre-circulatingmechanisminballscrew滚珠丝杠循坏机构的冲击失效分析AbstractAballscrewdrivenmechanismisamajorcomponentinhigh-speed/high-precisiontransmittingsystems.Insuchamechanism,thereturntubehasbeendesignedtoprovidethepathforasteelballrollinginscrewgrooves.Asthedrivenshaftintheme

2、chanismoperatesathighrotatingspeed,forcescausedbytheimpactactivitybetweenthesteelballandreturntubemaygeneratehighstressesandcausedamagetothereturntubeaftersomesignificantservicetimes.Inordertounderstandthefractureconditionsinthereturntube,animpact・contactformulaisdevelopedandthetransient

3、behaviorisinvestigatedbasedonthefiniteelementmethodinthispaper.Fromresultsobtainedhere,itisshownthattherotationalspeedoftheballscrewmayaffecttheservicelifeofthereturntubesignificantly.Factorsthataffecttheservicelifeofthere-circulatingmechanismarethendescribedindetail.Furthersuggestionsfo

4、rtheimprovementofthereturntubeinthedesign/fabricationprocessesarealsoproposedinthefinalpartofthispaper.一•个滚珠丝杠驱动机构是在高速/高楷度传递系统…个主要的组件。在这样的一个机构，反向器被设计用來为钢球在丝杠螺纹屮滚动提供路径。作为机构运作的驱动轴在高转速下、钢球和反向器Z间山冲击活动产生的高应力和反向器后一些长时间的运行可能進成损坏。为了理解反向器中断裂情况，本文发展了一个冲击-接触公式，研究了呈于冇限兀方法的瞬态过程。从这甲获得的结果，表明了滚珠丝杠转速的可能显

5、苦冲击反向器的寿命。循环机构使川寿命的冲击因索将详细讨论。反向器在设计/制造过程的进一步改进意见和建议也在本文的最后一部分提出。1.IntroductionAballscrewdrivenmechanismisamajorcomponentinthedevelopmentofhigh-speed/high-precisionsmittingsystems・Undertherequirementforhigh-speedtransmittingsystemssuchastherecentapplicationsinsemiconductorfields,thefeedra

6、teoftheballscrewisfasterthan80mmin,whichismuchhigherthantheconventionalrate,30mmin「1orlower.Generallyspeaking,therequirementofhighfeedratecanbereachedbyincreasingtherotationalspeedoftheballscrew.However,themaximumrotationalspeedisrestrictedbytheallowableclmNvalue(productofballpitchcircle

7、diameterdminmmandrotationalspeedNinrpm)oftheballscrewinthedesignprocess.CutrentstandarddmNvaluesforballscrewsdesignedundercertainspecificationsaredefinedwithintherangefrom70,000to80,000[1].Foraballscrewwithdiameter5()mmandleadingpitch20—3()mmoperatingatrotationalspeedsof2