平面四桿機構(gòu)的演化Evolutionofplanarfou

平面四桿機構(gòu)的演化Evolutionofplanarfourbarmechanisms主講人：周會娜基本型式一一鉸鏈四桿機構(gòu)Basictype-hingefourbarmechanism目錄CONTENTS1234曲柄滑塊機構(gòu)IntroductiontoMechanicalDrawing偏心輪機構(gòu)Drawingformatofmechanicaldrawings導桿機構(gòu)FrameofMechanicalDrawing定塊機構(gòu)Writingfontsformechanicaldrawings5搖塊機構(gòu)Thesignificanceoflearningmechanicaldrawing1曲柄滑塊機構(gòu)CrankslidermechanismONE曲柄搖桿機構(gòu)crank-rockermechanism一、曲柄滑塊機構(gòu)Crankslidermechanism當AB桿能整周回轉(zhuǎn)成為曲柄時，該機構(gòu)稱為曲柄滑塊機構(gòu);否則該機構(gòu)稱為擺桿滑塊機構(gòu)。WhentheABrodcanrotateallthewaytobecomeacrank,thismechanismiscalledacrankslidermechanism;Otherwise,themechanismiscalledapendulumslidermechanism.曲柄搖桿機構(gòu)Crankrockermechanism一、曲柄滑塊機構(gòu)Crankslidermechanism對心曲柄滑塊機構(gòu)centricslider-crankmechanism偏置曲柄滑塊機構(gòu)offsetslider-crankmechanism一、曲柄滑塊機構(gòu)Crankslidermechanism對心曲柄滑塊機構(gòu):曲柄回轉(zhuǎn)中心與滑塊移動導路中心線無偏距。Centeredcrankslidermechanism:Thereisnooffsetbetweenthecrankrotationcenterandthecenterlineoftheslidermovementguide.一、曲柄滑塊機構(gòu)Crankslidermechanism偏置曲柄滑塊機構(gòu):曲柄回轉(zhuǎn)中心至滑塊移動導路中心線存在垂直距離e(即有偏距)Biascrankslidermechanism:Thereisaverticaldistancee(i.e.offset)betweenthecrankrotationcenterandthecenterlineoftheslidermovementpath一、曲柄滑塊機構(gòu)Crankslidermechanism偏置曲柄滑塊機構(gòu)offsetslider-crankmechanism偏心的距離e稱作偏心距。Thedistanceeofeccentricityiscalledeccentricity.滑塊的兩個極限位置之間的距離稱為機構(gòu)的行程H。ThedistancebetweenthetwolimitpositionsoftheslideriscalledthetravelHofthemechanism.一、曲柄滑塊機構(gòu)Crankslidermechanism曲柄滑塊機構(gòu)的運動特性Kinematiccharacteristicsofcrankslidermechanism1.急回運動和行程速比系數(shù)1.Quickreturnmotionandtravelspeedratiocoefficient偏置曲柄滑塊機構(gòu)offsetslider-crankmechanism一、曲柄滑塊機構(gòu)CrankslidermechanismHΦ1>φ2

t1>t2V2>v1工作行程空回行程滑塊行程SlidestrokeHH曲柄轉(zhuǎn)速Crankspeedωω曲柄轉(zhuǎn)角crankangleφ1=180°+θφ2=180°-θ運動時間Exercisetimet1t2滑塊的平均速度TheaveragespeedofthesliderV1V2一、曲柄滑塊機構(gòu)Crankslidermechanism行程速比系數(shù):Travelspeedratiocoefficient：一、曲柄滑塊機構(gòu)Crankslidermechanism偏心曲柄滑塊機構(gòu)有極位夾角θ時，就有急回運動特性，而且θ角越大K值就越大，機構(gòu)的急回特性就越顯著。EccentriccrankslidermechanismwithextremepositionangleθAtthistime,thereisarapidreturnmotioncharacteristic,andθThelargertheangle,thegreatertheKvalue,andthemoresignificantthequickreturncharacteristicofthemechanism.一、曲柄滑塊機構(gòu)Crankslidermechanism對心曲柄滑塊機構(gòu)有急回特性嗎?Doesthecentercrankslidermechanismhaveaquickreturncharacteristic?極位夾角θ=0，行程速比系數(shù)K=1。Polarangleθ=0,travelspeedratiocoefficientK=1.Thecenteringcrankslidermechanismhasnoreturncharacteristic對心曲柄滑塊機構(gòu)無急回特性。一、曲柄滑塊機構(gòu)Crankslidermechanism曲柄滑塊機構(gòu)的運動特性Kinematiccharacteristicsofcrankslidermechanism死點位置dead-centerposition2.死點Deadpoint一、曲柄滑塊機構(gòu)Crankslidermechanism當滑塊為主動件，存在兩個死點位置。Whenthesliderisanactivecomponent,therearetwodeadcenterpositions.連桿和曲柄共線時，過鉸鏈中心A的力，對A點不產(chǎn)生力矩，不能使曲柄轉(zhuǎn)動。Whentheconnectingrodandthecrankarecollinear,theforcepassingthroughthecenterAofthehingedoesnotgeneratetorqueatpointAandcannotcausethecranktorotate.死點位置dead-centerposition一、曲柄滑塊機構(gòu)Crankslidermechanism曲柄滑塊機構(gòu)的應用：Theapplicationofcrankslidermechanism內(nèi)燃機氣缸一一對心曲柄滑塊機構(gòu)Internalcombustionenginecylinder--centricslider-crankmechanism一、曲柄滑塊機構(gòu)Crankslidermechanism曲柄滑塊機構(gòu)的應用Theapplicationofcrankslidermechanism自動送料裝置一一偏心曲柄滑塊機構(gòu)Automaticfeedingdevice-eccentriccrankslidermechanism一、曲柄滑塊機構(gòu)Crankslidermechanism2偏心輪機構(gòu)EccentricwheelmechanismTWO二、偏心輪機構(gòu)Eccentricwheelmechanism曲柄搖桿機構(gòu)Crank-rockermechanism工程中常將轉(zhuǎn)動副的半徑擴大至超過曲柄長度變成圓盤，此偏心圓盤稱為偏心輪。曲柄為偏心輪結(jié)構(gòu)的連桿機構(gòu)稱為偏心輪機構(gòu)。Inengineering,theradiusoftherotatingpairisoftenexpandedbeyondthelengthofthecranktobecomeadisc,whichiscalledaneccentricwheel.Theconnectingrodmechanismwithaneccentricwheelstructureiscalledaneccentricwheelmechanism二、偏心輪機構(gòu)Eccentricwheelmechanism二、偏心輪機構(gòu)Eccentricwheelmechanism曲柄搖桿機構(gòu)的演化一一偏心輪機構(gòu)Theevolutionofcrankrockermechanism-eccentricwheelmechanism二、偏心輪機構(gòu)Eccentricwheelmechanism偏心輪機構(gòu)的應用Theapplicationofeccentricwheelmechanism剪床shearingmachine機構(gòu)的演化方法:選擇機構(gòu)中不同的構(gòu)件為機架。Mechanismevolutionmethod:Selectdifferentcomponentsinthemechanismasframes.(a)對心曲柄滑塊機構(gòu)(b)導桿機構(gòu)(c)搖塊機構(gòu)(d)定塊機構(gòu)centricslider-crankmechanismguide-barmechanismShakermechanismBlockfixingmechanism二、偏心輪機構(gòu)Eccentricwheelmechanism3導桿機構(gòu)GuiderodmechanismTHREE三、導桿機構(gòu)Guiderodmechanism取曲柄滑塊機構(gòu)中原曲柄為機架構(gòu)成導桿機構(gòu)。原曲柄2為主動件，若I3<I2，導桿1作往復擺動，稱為擺動導桿機構(gòu)。Taketheoriginalcrankofthecrankslidermechanismastheframetoformaguiderodmechanism.Theoriginalcrank2isanactivecomponent.IfI3<I2,theguiderod1oscillatesbackandforth,whichiscalledaswingingguiderodmechanism擺動導桿機構(gòu)oscillatingguide-barmechanism三、導桿機構(gòu)Guiderodmechanism取曲柄滑塊機構(gòu)中原曲柄為機架構(gòu)成導桿機構(gòu)。Taketheoriginalcrankofthecrankslidermechanismastheframetoformaguiderodmechanism.原連桿3為主動件，若I3≥I2，導桿1作整周運動，稱為轉(zhuǎn)動導桿機構(gòu)。Theoriginalconnectingrod3isanactivecomponent.IfI3≥I2,guiderod1movesinafullcircle,whichiscalledarotatingguiderodmechanism.擺動導桿機構(gòu)oscillatingguide-barmechanism4定塊機構(gòu)FixedblockmechanismFOUR曲柄滑塊機構(gòu)中，如取滑塊為機架，則該機構(gòu)演化成定塊機構(gòu)。Inthecrankslidermechanism,iftheslideristakenasaframe,themechanismevolvesintoafixedblockmechanism.四、定塊機構(gòu)Fixedblockmechanism定塊機構(gòu)Fixedblockmechanism手壓抽水機Handpresswaterpump5搖塊機構(gòu)Shak