AGMA-90FTM4-1990.pdf
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1、90 FTM4 DifferentTypes of Wear- How to Classify ? by: LouisFaure,CETIM AmericanGear ManufacturersAssociation TECHNICALPAPER Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 11:19:
2、22 MDTNo reproduction or networking permitted without license from IHS -,-,- DifferentTypesof Wear- Howto Classify? Louis Faure, CETIM The Statementsand opinionscontainedhereinare thoseof the authorand shouldnot be construedas an officialactionor opinionof the AmericanGearManufacturersAssociation. A
3、BSTRACT: In the first part, this documentdescribesall the typesand aspectsof wear which can occuron the gear teethin operation,with causesand explanationsconcerningtheir appearance. For each type of wear, the possibleevolutionand the limits whichshouldnot be overpassedto avoid a failureor severedama
4、geto the teeth,thus reducingthe life of thegear,are clearlyspecified. Aspectsof wear types which can be consideredas normal,mediumor progressiveare also describedand solutionsare presentedas a guidefor wear stabilizing. This documentis illustratedwith numerouspicturesof all typesof wear. Theothertyp
5、esof gearfailuressuchas surfacefatigue,corrosion,plasticflowand breakagearenot includedin this paper which is only dealingwith wear. Copyright 1990 AmericanGearManufacturersAssociation 1500 King Street,Suite201 Alexandria,Virginia,22314 October,1990 ISBN:1-55589-556-5 Copyright American Gear Manufac
6、turers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 11:19:22 MDTNo reproduction or networking permitted without license from IHS -,-,- DIFFERENTTYPESOFWEAR, HOWTOCLASSIFY? L.FAURE HEADOFGEARDEPARTMENT CETIMSENLIS-
7、FRANCE TABLEOF CONTENTS1 INTRODUCTION Section TitleThephenomenaof deteriorationof surfacesare generallyvery complexand depend on numerousconditionswhichinclude: 1.INTRODUCTION1- the operatingconditions 2.CURRENTWEAR(two bodies abrasion)2- the type of load applied - the relative speeds of surfacesin
8、contact 3.SCORING- STREAKS3- the temperature - the lubrication 4.ADHESIVEWEAR3- the surface hardness - the surface roughness 4.1 Polishing3- the compatibilityand nature of materialsin presence 4.2 Adhesionsor adhesures4The wear is a general term covering the local phenomenondescribing the removalof
9、some materialand occuringwhen two surfacesslide 4.3 Hot scuffing5onto one another. 4.4 Cold Scuffing7This term alsoapplies tothe removalof material resultingfrom the presenceof impuritiesin the lubricant. 5.WEARWITHTHREEBODIES8The other types of gear failuressuch as surfacefatigue,corrosion, plastic
10、flow and breakageare not coveredby this paper whichis 5.1 Scratches, Grooves (Scratching)8only dealing with wear. 5.2 Abrasivewear8To separatethe differenttypes of wear,we willuse two distinct classifications: 6.INTERFERENCEWEAR9 One, qualitativewill be basedon the actionmodes of 7.NORMALWEAR10diffe
11、rentwearphenomenaon gear-teethand will allowto characterizethe differentsurfaceaspectswhichwe can 8.MODERATE WEAR12encounter. 9.EXCESSIVEWEAR13The other will take into accountthe intensityof the wear phenomenaandwilldefinethedementsallowingto D10.CONCLUSION15measure theirevolution. Copyright America
12、n Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 11:19:22 MDTNo reproduction or networking permitted without license from IHS -,-,- The qualitativeanalysis of wear phenomenawill bnngus to define s
13、uccessively - abrasivewear with two bodies - streaksand scoring - polishing - scuffing (cold or hot) - abrasivewear with three bodies - scratchesor grooves - interferencewear. During the quantitativeanalysis we will definesuccessively: -normalwear -moderatewear -excessivewear A synthes_s of these tw
14、o classificationshas been made under a chart form whichis placed at the end of this paper. 2 CURRENTWEAR(called two bodies abrasion) The current wear is revealed very early in the life of the gearing and is shown in the removal of micro-particlesof metal on the gear-teeth surface.Thisphenomenonts du
15、eto contactandmetal-to-metal sliding whichoccursthroughthe oil film. The distinctivemachiningmarks of the cuttingprocedureor fmishFigure2Tracesof wear recordedon a gear wheel in operation (for example,the facets resultingfrom hobbing,the streaks left by a gear cutter or by a rack cutter,the surface
16、patternfrom certainWe will note the presenceof a dull zone below the pitch,where the grinding operations)are diminishedor erased by wear.wear is greater,and : Thiswearbringsaboutaprogressivereductionof gear-teeth thickness along with a more or less marked distorsionof the profile- of a lustrousarea
17、on each side of the pitchand slightly in the heavy sliding zones but without noticeabledegradationof thehigher, surfaceroughness.- oftransversalscoringslightlymarkednearthetoothtip, As indicatedon figure1, the wear,which is almost nul in the pitch zone wherethe slidingspeeds are lower or nul, become
18、smore and more importantas we move away from this zone. This zone is- of machining streaks still visible near the pitch. maximumat the tip circle and at the active dedendumcircle whereThe aspect of this wear as well as its developingspeed vary greatly theslidingspeedsarethehighest,accordingto : - th
19、e pressurelevel betweenthe contactsurfaces The aspect of the wear zone is generallygrey coloredand slightly- the hardnessof the materials dull,with sometimeslustrousareasand the presenceof scoring- the roughnessof surfaces (el.figure2)- the thicknessof lubricantfilm. wearon toothtip For example : a)
20、In the easeof slightly loaded gears operating with an oil ._“of relatively high viscosityat medium speeds, we will have ;_i_?anoilfilmsufficientlythicktoavoidmetal-to-metal contact. .f_-_._._This will not generatewear except duringgear startingor _-pitchcirclestopping ._I- -gj,._- t_The originalmach
21、iningtraces will still be intacton the .1_._gear-teethafter long periodsof operation. b)In practice it is not always possibleto have a continuous lubricantfilm betweenthe gear-teethaccordingto the load transmitted.Thereis then contactbetweenthe top of the asperitiesmade during machiningand there is
22、a tendency toothrootwearto polishor score the surfaces in contact (Cf.description hereafterof “polishing,scoringor streaks“). c)In the ease of surfacehardenedgears,dueto the high Figure 1Distinctiveaspect of distorsionof gear-teethprofile underhardness of flanks in contact,we encounteronly slight we
23、ar wearaction,whichisoftendifficulttoappreciate. Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 11:19:22 MDTNo reproduction or networking permitted without license from IHS -,-,
24、- 3SCORING- STREAKS This type of wear presentsunder the form of fine groovesor lines that are in the sliding direction.These steaks or scores are formed progressivelyin the zones characterizedby a high slidingspeed, at the tooth tip and near the root of the gear-teeth. They are often developpedon po
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