平面四桿機構的演化Evolutionofplanarfourbarmechanisms主講人：周會娜基本型式一一鉸鏈四桿機構Basictype-hingefourbarmechanism目錄CONTENTS1234曲柄滑塊機構IntroductiontoMechanicalDrawing偏心輪機構Drawingformatofmechanicaldrawings導桿機構FrameofMechanicalDrawing定塊機構Writingfontsformechanicaldrawings5搖塊機構Thesignificanceoflearningmechanicaldrawing1曲柄滑塊機構CrankslidermechanismONE曲柄搖桿機構crank-rockermechanism一、曲柄滑塊機構Crankslidermechanism當AB桿能整周回轉成為曲柄時，該機構稱為曲柄滑塊機構;否則該機構稱為擺桿滑塊機構。WhentheABrodcanrotateallthewaytobecomeacrank,thismechanismiscalledacrankslidermechanism;Otherwise,themechanismiscalledapendulumslidermechanism.曲柄搖桿機構Crankrockermechanism一、曲柄滑塊機構Crankslidermechanism對心曲柄滑塊機構centricslider-crankmechanism偏置曲柄滑塊機構offsetslider-crankmechanism一、曲柄滑塊機構Crankslidermechanism對心曲柄滑塊機構:曲柄回轉中心與滑塊移動導路中心線無偏距。Centeredcrankslidermechanism:Thereisnooffsetbetweenthecrankrotationcenterandthecenterlineoftheslidermovementguide.一、曲柄滑塊機構Crankslidermechanism偏置曲柄滑塊機構:曲柄回轉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Crankslidermechanism偏置曲柄滑塊機構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的行程H。ThedistancebetweenthetwolimitpositionsoftheslideriscalledthetravelHofthemechanism.一、曲柄滑塊機構Crankslidermechanism曲柄滑塊機構的運動特性Kinematiccharacteristicsofcrankslidermechanism1.急回運動和行程速比系數(shù)1.Quickreturnmotionandtravelspeedratiocoefficient偏置曲柄滑塊機構offsetslider-crankmechanism一、曲柄滑塊機構CrankslidermechanismHΦ1>φ2

t1>t2V2>v1工作行程空回行程滑塊行程SlidestrokeHH曲柄轉速Crankspeedωω曲柄轉角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Crankslidermechanism行程速比系數(shù):Travelspeedratiocoefficient：一、曲柄滑塊機構Crankslidermechanism偏心曲柄滑塊機構有極位夾角θ時，就有急回運動特性，而且θ角越大K值就越大，機構的急回特性就越顯著。EccentriccrankslidermechanismwithextremepositionangleθAtthistime,thereisarapidreturnmotioncharacteristic,andθThelargertheangle,thegreatertheKvalue,andthemoresignificantthequickreturncharacteristicofthemechanism.一、曲柄滑塊機構Crankslidermechanism對心曲柄滑塊機構有急回特性嗎?Doesthecentercrankslidermechanismhaveaquickreturncharacteristic?極位夾角θ=0，行程速比系數(shù)K=1。Polarangleθ=0,travelspeedratiocoefficientK=1.Thecenteringcrankslidermechanismhasnoreturncharacteristic對心曲柄滑塊機構無急回特性。一、曲柄滑塊機構Crankslidermechanism曲柄滑塊機構的運動特性Kinematiccharacteristicsofcrankslidermechanism死點位置dead-centerposition2.死點Deadpoint一、曲柄滑塊機構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點不產生力矩，不能使曲柄轉動。Whentheconnectingrodandthecrankarecollinear,theforcepassingthroughthecenterAofthehingedoesnotgeneratetorqueatpointAandcannotcausethecranktorotate.死點位置dead-centerposition一、曲柄滑塊機構Crankslidermechanism曲柄滑塊機構的應用：Theapplicationofcrankslidermechanism內燃機氣缸一一對心曲柄滑塊機構Internalcombustionenginecylinder--centricslider-crankmechanism一、曲柄滑塊機構Crankslidermechanism曲柄滑塊機構的應用Theapplicationofcrankslidermechanism自動送料裝置一一偏心曲柄滑塊機構Automaticfeedingdevice-eccentriccrankslidermechanism一、曲柄滑塊機構Crankslidermechanism2偏心輪機構EccentricwheelmechanismTWO二、偏心輪機構Eccentricwheelmechanism曲柄搖桿機構Crank-rockermechanism工程中常將轉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。曲柄為偏心輪結構的連桿機構稱為偏心輪機構。Inengineering,theradiusoftherotatingpairisoftenexpandedbeyondthelengthofthecranktobecomeadisc,whichiscalledaneccentricwheel.Theconnectingrodmechanismwithaneccentricwheelstructureiscalledaneccentricwheelmechanism二、偏心輪機構Eccentricwheelmechanism二、偏心輪機構Eccentricwheelmechanism曲柄搖桿機構的演化一一偏心輪機構Theevolutionofcrankrockermechanism-eccentricwheelmechanism二、偏心輪機構Eccentricwheelmechanism偏心輪機構的應用Theapplicationofeccentricwheelmechanism剪床shearingmachine機構的演化方法:選擇機構中不同的構件為機架。Mechanismevolutionmethod:Selectdifferentcomponentsinthemechanismasframes.(a)對心曲柄滑塊機構(b)導桿機構(c)搖塊機構(d)定塊機構centricslider-crankmechanismguide-barmechanismShakermechanismBlockfixingmechanism二、偏心輪機構Eccentricwheelmechanism3導桿機構GuiderodmechanismTHREE三、導桿機構Guiderodmechanism取曲柄滑塊機構中原曲柄為機架構成導桿機構。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。Taketheoriginalcrankofthecrankslidermechanismastheframetoformaguiderodmechanism.Theoriginalcrank2isanactivecomponent.IfI3<I2,theguiderod1oscillatesbackandforth,whichiscalledaswingingguiderodmechanism擺動導桿機構oscillatingguide-barmechanism三、導桿機構Guiderodmechanism取曲柄滑塊機構中原曲柄為機架構成導桿機構。Taketheoriginalcrankofthecrankslidermechanismastheframetoformaguiderodmechanism.原連桿3為主動件，若I3≥I2，導桿1作整周運動，稱為轉動導桿機構。Theoriginalconnectingrod3isanactivecomponent.IfI3≥I2,guiderod1movesinafullcircle,whichiscalledarotatingguiderodmechanism.擺動導桿機構oscillatingguide-barmechanism4定塊機構FixedblockmechanismFOUR曲柄滑塊機構中，如取滑塊為機架，則該機構演化成定塊機構。Inthecrankslidermechanism,iftheslideristakenasaframe,themechanismevolvesintoafixedblockmechanism.四、定塊機構Fixedblockmechanism定塊機構Fixedblockmechanism手壓抽水機Handpresswaterpump5搖塊機構Shak