清华大学机械原理英文 (7).ppt

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1、Chap.6intermittentmechanismsChap.6.1RatchetmechanismsChap.6.2GenevamechanismsChap.6.3Cam-typeindexmechanismsChap.6.4IntermittentgearsetChap.6.1RatchetmechanismsWorkingprinciple:DrivingpawlHoldingpawlDrivenratchetFrameTypeoftheratchetmechanismsSilentratchetmechanismsExternallymeshedIn

2、ternallymeshedRatchetrackFixeddirectionChangeabledirection1,2SinglefunctionDoublefunctionExternalInternalToothratchetmechanismsInternallymeshedRatchetrackExternallymeshedDoublefunctionSilentratchetmechanismsApplication1．Intermittentmotion（牛头刨床的间歇送进机构）2．Safetyliftingmecjanism（卷扬机制动机构）

3、3．转位、分度（手枪盘分度机构）4．Clutch超越离合（钻床的自动进给机构）Chap.6.2GenevamechanismsDrivingplateDrivengenevawheelWorkingprinciple:TypeofthegevevamechanismsPlanargenevamechanismsSphericalgenevamechanismsexternalgenevamechanismsinternalgenevamechanismsComparedtotheratchetmechanismTheangularvelocityofagenev

4、amechanismshouldnotbetoohigh.Therotationangleofagenevawheelforeachcyclecannotbeadjusted.TheGenevamechanismhasnorigidimpulseandmotionissmoother.Genevamechanismscanbeusedtodriverotatingtableswithlargemomentsofinertia.ApplicationWidelyusedintheAutomaticmachineandinstruments.ProjectionMa

5、chineChap.6.3Cam-typeindexmechanismsItisusedinmachineswhichneedtotransmitindexingmotionorintermittentmotionbetweentwocrossedshafts.Twotypes:Cylindrical-camindexmechanismsHourglass–camindexmechanismsAdvantages,DisadvantagesandApplicationItcantransmitmotionsmoothlyandtheirdynamicalchar

6、acteristicsareverygood.Noiseandvibrationisverylow.Anyratiobetweenmotiontimeanddwelltimecanbedesigned,andpositionalaccuracyishighandreliable.Usedinhigh-speed,high-accuracyindexmechanisms.Thehourglass-camindexmechanismhashigherindexaccuracy.Chap.6.4IntermittentgearsetTypeExternalIntern

7、alApplicationRackgearset