機械設(shè)計第四章摩擦磨損及潤滑概述

機械設(shè)計第四章摩擦磨損及潤滑概述第1頁，課件共25頁，創(chuàng)作于2023年2月Lubrication（潤滑）——Theconditionofhavingbeenmadesmoothorslipperybytheapplicat-ionofalubricantsuchasoilorgrease(脂)Tribology（摩擦學(xué)）——Thebranchofengineeri-ngthatdealswiththeinteractionofsurfacesinrelativemotion(asinbearingsorgears):theirdesignandfrictionandwearandlubrication第2頁，課件共25頁，創(chuàng)作于2023年2月IIFriction(摩擦)1.Classification①

ClassifiedbywhethertwopartshaverelativemovementStaticalfriction(靜摩擦)——frictionbetweentwoormoresolidobjectsthatarenotmovingrelativetoeachother；Kineticfriction(動摩擦)——occurswhentwoobjec-tsaremovingrelativetoeachotherandrubtogether(likeasled(雪橇)ontheground).第3頁，課件共25頁，創(chuàng)作于2023年2月②

Classifiedbymovementtype（important）Slidingfriction（滑動摩擦）——occurs

whentwoobjectsslideacrossfromoneanother；Rollingfriction(滾動摩擦)——occurswhenabody(suchasaball,tire,orwheel)rollsonasurface.第4頁，課件共25頁，創(chuàng)作于2023年2月③

Classifiedbylubricant（important）Dryfriction

(干摩擦)——resistsrelativelateralmotionoftwosolidsurfacesincontactFluidfriction（流體摩擦）——thefrictionbetweenlayerswithinaviscousfluidthataremovingrelativetoeachother；

第5頁，課件共25頁，創(chuàng)作于2023年2月Boundaryfriction（邊界摩擦）——occurswhenasurfaceisatleastpartiallywet,butnotsolub-ricatedthatthereisnodirectfrictionbetweentwosurfaces;Mixedfriction（混合摩擦）——akindoffrictionincludingbothboundaryfrictionandfluidfric-tion.第6頁，課件共25頁，創(chuàng)作于2023年2月III

Wear(磨損)Threestagesofwear

*run-inwear(磨合磨損)（useful）Stablewear(穩(wěn)定磨損)（work）Severewear(劇烈磨損)（failure）Wearrateε：ε=△q／△t△q——WearmagnitudeDesignoruseamachine,youshoulddoyourbesttoreducerun-intime,increasestableweartimeandpostponethearrivalofseverewear.第7頁，課件共25頁，創(chuàng)作于2023年2月1.Adhesivewear(粘著磨損)3.Fatiguewear(疲勞磨損)Pressure—localtemperatureincreases—adhesion(weld)

Frictionforce—avulsion,shear—materialtransferFluctuatingstresses—crackpropagatio-n—surfacedelamination(表面剝落)—pit（pittingcorrosion,疲勞點蝕）2.Abrasivewear(磨料磨損)Surfacematerialdropsoff,oilcontainsimpurity(雜質(zhì)),rigidgrainsbecomeabrasivegrains(磨料)4.Corrosionwear(腐蝕磨損)5.Erosion(沖蝕磨損)AstateofdeteriorationinmetalscausedbyoxidationorchemicalactionErosioncausedbygasandfluid第8頁，課件共25頁，創(chuàng)作于2023年2月IVLubrication（潤滑）Decreasefriction,reducewear；Preventpartsfromrust；Heatoutputandtemperaturereduction（circulationoil,循環(huán)油）；Cushionandabsorbshock(緩沖吸振)；Seal（Greaselubricant）1.EffectsofLubrication(潤滑的作用)第9頁，課件共25頁，創(chuàng)作于2023年2月2、Lubricantanditsindex（潤滑劑及主要指標(biāo))（1）

Lubricatingoil（潤滑油）

Animaloil,vegetableoil,Mineraloilandchemicalsynthesisoil①

Viscosity（粘度）Resistanceofaliquidtoshearforces(andhencetoflow)第10頁，課件共25頁，創(chuàng)作于2023年2月Newtonianfluidfrictionlaw(牛頓流體摩擦定律)：AmovewithaspeedV，andBisholdstill,sothatfluidclosetoAmovewithaspeedV,andfluidclosetoBplateisstatic.Themovementofthefluidislaminarflow,thereexistrelativeslipbetweenarbitrarytwolayers,shearstressesexistattheinterfaceoflaminarflow,i.e.,第11頁，課件共25頁，創(chuàng)作于2023年2月A.Kineticviscosity（動力粘度）

Unit：Pa·s（ISO），N·s/m2（C.G.S,厘米-克-秒制單位）B、Kenimaticviscosity(運動粘度)

Unit：m2/s

＝

／

——FluiddensityC、Specificviscosity(條件粘度)

EUnit：Englerdegree(恩氏度,°Et）Oilnumber(Table4-1):AccordingtoGB/T314-1994,oilnumberisthecentralvalueofkenimaticviscosityat40oC第12頁，課件共25頁，創(chuàng)作于2023年2月Influencingfactorofviscosity(影響粘度的因素)Temperature：hightemperaturecauseslowviscosity；Pressure：Viscosityincreaseswithincreasingpress-ure.Whenpressureislowerthan20MPa,itseffectscanbeignored.Whenpressureexceeds20MPa,theymustbeconsidered.

p——Viscosityunderpressurep，Pa·s；

0——Viscosityunderpressure105Pa，Pa·s；

——Pressure–viscositycoefficient(粘壓系數(shù))，

＝（1~3）×10-8m2／N。第13頁，課件共25頁，創(chuàng)作于2023年2月②

Oiliness(油性)Physicalorchemicalabsorptionfilm(吸附膜)→decreasefrictionandwear③Extremepressureproperty(極壓性)Createwear-resisting,highpressureresisti-ngchemicalboundaryfilm④Oxidationresistance(氧化穩(wěn)定性)Theabilitytoresistoxidation⑤

Flashpoint（閃點）andSolidifyingPoint（凝固點）Itisimportanttoworkinhighorlowtemperature

第14頁，課件共25頁，創(chuàng)作于2023年2月（2）Lubricantgrease（潤滑脂）Calciumbase(鈣基)grease,Sodium(鈉基)basegrease，lithiumbase(鋰基)grease,aluminumbase(鋁基)grease①Penetration(針入度)Lowerpenetrationincreasesbearingcapacity②Droppingpoint(滴點)Measurethehighthermalresistanceofthegrease第15頁，課件共25頁，創(chuàng)作于2023年2月（3）Additive（添加劑）EffectsoftheadditiveImproveoiliness,extremepressurepropertyandworkabilityunderextremeoperatingconditions；Deferageingandprolongservicelife；ImprovephysicalpropertyTypicaladditive：detergentdispersant(清凈分散劑),antioxidant(抗氧化劑),oilinessadditive(油性添加劑),extreme-pressureandantiwearadditive(極壓與抗磨添加劑),pourinhibitor(降凝劑),tackifier(增粘劑)第16頁，課件共25頁，創(chuàng)作于2023年2月Lubricatingmethods(oilandgreaselubrication）1.Oillubrication(油潤滑)Forcefillingoilcup(壓注油杯）Oilpotwithturningsleeve（旋套油杯）第17頁，課件共25頁，創(chuàng)作于2023年2月（1）Dripfeedlubrication(滴油潤滑)Oilpotwithneedlevalve(針閥油杯)Wickoiler(油芯注油器)第18頁，課件共25頁，創(chuàng)作于2023年2月（2）Oil-ringlubrication(油環(huán)潤滑)（3）Splashlubrication(飛濺潤滑)（4）Pressurecirculation(壓力循環(huán)潤滑)第19頁，課件共25頁，創(chuàng)作于2023年2月2.Greaselubrication(脂潤滑)Greasecupwithturningsleeve(旋蓋式油脂杯)Greasegun(油脂槍)第20頁，課件共25頁，創(chuàng)作于2023年2月§4—4Hydrodynamicandhydrostaticlubrication(液體動力潤滑和流體靜力潤滑)I.Newtonianlawoffriction(viscosity)牛頓流體摩擦的摩擦定律（粘性定率）Tangentialstressesinanypointoffluidaredirectlypro-portionaltolocalvelocitygradientProportionalitycoefficients(比例系數(shù))η—

KineticviscosityofthefluidShearresistanceperunitare