摩擦磨损及润滑概述

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1、§4-1Friction§4-2Wear§4-3Lubricant、additiveandlubricationmethods§4-4Introductionoffluidlubricationprinciple§4-0OverviewChapter4Theoverviewoffriction、wearandlubrication中南大学§4-0OverviewTribology----studyfriction、wearandlubricationoftwosurfacesmovingrelatively。Itisanedgeprinciple。▲friction—Twosurf

2、acesmovingrelativelyhindereachother；▲wear--materialofobjectsurfacelosesortransmitbecauseoffriction；▲lubrication—themethodreducingfrictionandwear。About1/3~1/2energyintheworldisconsumedinfriction。Themajorityofmachineelementsarerejectedandreplacedbecauseofexcessivewear。Reducefrictionsaveenergy；Re

3、ducewearlowerthemaintenancecost。中南大学2、typesoffrictionInternalfriction：thephenomenonofhindranceofrelativemovementofmolecule。Externalfriction：thephenomenonofhindranceofrelativemovementofsurface。Staticfriction：frictionhavingrelativemomenttendency。Dynamicfriction：frictionhavingrelativemoment。Slidi

4、ngfriction：Themovementbetweentwosurfacesisrelativesliding。Rollingfriction：Themovementbetweentwosurfacesisrelativerolling。▲“mechanicaltheory”—thefrictionishindranceactionofconvexo-concavesurface；▲“moleculartheory”—thefrictionistheattractiveforceofmoleculeofmaterialsurface；1、principleoffriction▲

5、“mechanical--moleculartheory”—bothaction。§4-1Friction中南大学(1)DryfrictionThesurfacesoftwoelementscontactdirectly，manycold-scoringpointscausedbyhighpressofpartareamaybeshearedwhenmoving。Nodryfriction！(2)Boundaryfriction3、Slidingfriction→consumptionofpower↑wear↑temperature↑→damagethesleeveThereisa

6、sheetofoilfilmbetweenthetwosurfacesofpair.Thethicknessofoilfilmislessthen1μmTheoilfilmcan’tseparatecompletelythetwosurfacesofmetalbody。f≈0.1~0.3vThesurfaceofpairhaveasheetofpressoilfilmthatcanseparatethesurfaceoftwometalbody。Itisanidealcondition。(3)Fluidfrictionf≈0.001~0.01vvv中南大学4.Mixturefric

7、tionvThefrictionconditionoftwosurfacesisbetweenboundaryfrictionandmixturefriction。Thefrictioncoefficientofmixturefrictionismorelessthanthatofboundaryfriction。在一般机器中，处于后三种情况的混合状态。fηn/poBoundaryfrictionMixturefrictionFluidfrictionFriction