Download - Wind Drivetrain Bearing Reliability

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Page 1: Wind Drivetrain Bearing Reliability

Wind Drivetrain Bearing Reliability

Page 2: Wind Drivetrain Bearing Reliability

Before We Start This webinar will be available at

www.windpowerengineering.com & email

Q&A at the end of the presentation

Hashtag for this webinar: #WindWebinar

Page 3: Wind Drivetrain Bearing Reliability

Moderator Presenter

Paul DvorakWindpower

Engineering & Development

Rick BrooksThe Timken Company

Page 4: Wind Drivetrain Bearing Reliability

Wind Drivetrain Bearing Reliability

Presented by The Timken Co.Richard Brooks, Mgr. Wind North America

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WIND TURBINE DRIVETRAIN - COMMON BEARING DAMAGE

Generator Bearings

Gearbox High Speed Bearings

Gearbox Planet Bearings

Main Shaft Bearings

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FINANCIAL IMPACT - WIND DRIVETRAIN BEARING DAMAGE

Low High$0

$500,000TOTAL REPAIR

COST

Frequency of Occurrence

Generator BearingsGearbox High Speed Bearings

Gearbox Planet Bearings

Main Shaft Bearings

$$$

$

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UP TOWER VS. DOWN TOWER REPAIRSUp Tower Down Tower

Crane Costs +++ ---Self Perform ++ -Clean Environment - ++Load Test --- ++Per Event Cost ~$10-$20k ~$250k-$500k

Page 8: Wind Drivetrain Bearing Reliability

Two TS

TDI and CRB Ultrawind

Two SRBs

Single SRB

WIND TURBINE MAIN SHAFT MOUNTS

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Hub Weight

Wind Thrust

Torque

Overturning Moments

Spherical Roller (SRB)

Main Bearing

MAIN SHAFT APPLICATION REVIEW-3 POINT MOUNT SRB

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MAIN SHAFT SRB – OBSERVED DAMAGE MODES:LOW SPEED AND HIGH THRUST COMBINED=• Micropitting

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x

MAIN SHAFT SRB – OBSERVED DAMAGE MODES:LOW SPEED AND HIGH THRUST COMBINED=• Edge Loading

Page 12: Wind Drivetrain Bearing Reliability

MAIN SHAFT SRB – OBSERVED DAMAGE MODES:LOW SPEED AND HIGH THRUST COMBINED=• Single Piece Cage Damage

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MAIN SHAFT SRB – OBSERVED DAMAGE MODES:LOW SPEED AND HIGH THRUST COMBINED=• Debris Damage

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MAIN SHAFT SRB ENHANCEMENTSEnhanced Geometry • Reduce edge loading• Improves roller/race contact• Decreases roller stresses

x

Page 15: Wind Drivetrain Bearing Reliability

MAIN SHAFT SRB ENHANCEMENTSSurface Finish• Reduced asperity contact and stress• Higher surface film, lower torque• Reduce friction and wear

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MAIN SHAFT SRB ENHANCEMENTSTwo Piece Cage:• Lower operating forces/stress

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MAIN SHAFT SRB ENHANCEMENTSWear Resistant “DLC” Coatings• Mitigate surface wear damaged• Increase fatigue life• Increase debris resistance

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TECHNOLOGY DESCRIPTION BENEFITS

Roller Finishing Low Roughness,Isotropic Finish

Reduced Asperity Contact & Stress

Roller Coating WC/aC:H Coating1 µm thick

Increased Wear Resistance,Increased Fatigue Life,Increased Debris Resistance.

Internal Geometry Roller/IR Conformity Decreases Roller Stress,Reduces Potential Roller SkewCreates Favorable Traction

Split Cage Two-Piece Machined Brass Cage

Lowers Possible Operating Forces

TIMKEN WEAR-RESISTANT SRBWear Resistant SRB

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Grease / Debris

Race condition

RESULTS OF TIMKEN WEAR RESISTANT SRBS AFTER 4 YEARS OPERATION

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MAIN SHAFT BEARING HEALTH- OTHER FACTORS• Condition Monitoring

• Statistical analysis and trending of bearing temperatures• Vibration or Shock Pulse analysis

• Lubrication Practices• Variation in manual greasing practices (amount & frequency)• Value of Auto-Lubrication systems

• Grease Selection• Investigate characteristics of current grease and alternatives

• Grease Flush• Designed to extend the life of bearings in early stages of wear

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Page 21: Wind Drivetrain Bearing Reliability

High Speed & Intermediate shafts:• High occurrence Rate •Axial cracks on Inners

Planetary positions:• Medium occurrence Rate• Debris & load damage

WIND GEARBOX BEARINGSPlanet Carrier & Low Speed Positions:•Low occurrence Rate•Thrust damage

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SRB CRB TRB

Integrated CRB Integrated TRB

PLANET BEARING ARRANGEMENTS - DEVELOPMENT

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PLANET BEARING - OBSERVED DAMAGE MODES

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Non-Integrated Integrated

TRB • Debris damage• Creeping Outer

• Debris damage

CRB • Debris damage• Thrust load • Heavy / Uneven loading• Smearing• Creeping outer

• Debris damage• Thrust Loading• Smearing

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PLANET BEARING ENHANCEMENTS• SRB:

• Replace with new design• CRB:

• Case carburized• DLC coating• Modified controlled clearances• Redesign as TRB or integrated

• TRB:• Case carburized• Redesign as integrated

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HIGH SPEED & INTERMEDIATE BEARINGS – OBSERVED DAMAGE MODES

I

R

r

Rr

F

1. Smearing 3. White Etch AreaAxial Cracking / Flaking

2. Inclusion Related:Axial Cracking / Spalling

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ROLLER SLIDING / SMEARING IN CRB

IR

r

RIRR

r

Outer Race

Inner Race

Cage

Roller

D - roller sliding increases outside the load zone

C – load zone exit – most of the traction forces are lost beyond this point

F

B - traction forces restore roller velocity to pure rolling motion in load zone

A– smearing as roller accelerates entering the load zone

Load distribution in load zone

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INCLUSION RELATED AXIAL CRACKING• Caused by non-ferrous contaminants in the steel• Commonly manifests as White Etch Butterflies• Material transforms in the area of the inclusion• Crack forms and prorogates to the surface or spalls

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WHITE ETCH AREAS CRACKS1. Hoop Stress from original Press Fit on shaft2. Tensile stresses from roller sliding & skewing3. Dynamic conditions begin the subsurface

transformation4. Crack forms in the hard & brittle transformed area5. Crack propagates to the surface

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WHITE ETCH AREAS CRACKS2. Tensile stresses from roller sliding & skewing

IR

r

Rr

F

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WHITE ETCH AREAS CRACKS

3.

3. Dynamic conditions begin the subsurface transformation

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WHITE ETCH AREAS CRACKS

Dynamic Event

Dynamic Event

NormalLoad

NormalLoad

Plastic Deformation Transformation

Plastic Deformation Transformation

4.

4. Crack forms in the hard & brittle transformed area

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WHITE ETCH AREAS CRACKS

5.

5. Crack propagates to the surface

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BEARING ENHANCEMENTS - HIGH SPEED & INTERMEDIATEEnhancement White Etch Inclusions Smearing

Steel Cleanliness + +++

Black Oxide +(early stages)

++(early stages)

‘DLC’ Coatings + +++

Case Carburized +++ ++

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0

1

2

3

4

Com

plet

ed Sm

earin

g Tes

t Cyc

les

Smeared during first cycle

ENGINEERED SURFACE: PERFORMANCE COMPARISON

Ground Honed/ES20 Honed/ES20/Black Oxide Wear-Resistant

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ENGINEERED SURFACES (COATINGS & TREATMENTS) Black Oxide Surfaces• Black oxide is a conversion treatment:

• Metallic parts are put into a hot bath containing oxidizing salts• Steel reacts with the oxidizing salts to form a

thin layer of magnetite on the surface (Fe3O4).

• Black oxide is a sacrificial surface• Benefits:

• Aesthetics• Corrosion prevention• Run-in and/or performance improvement• Prevents mild adhesive wear damage• Improve rolling contact fatigue life

DLC Coated Surfaces• DLC is a hard coating:

• Tungsten carbide incorporating an amorphous hydrocarbon composite. • Applied with a Physical Vapor Deposition

process in a vacuum chamber.

• Benefits:• Improve rolling contact fatigue life.• Mitigate life limiting wear damaged caused by

metal adhesion.• Increased fatigue Life• Increased debris resistance• Prevent scuffing or smearing damage

(Timken Wear Resistant coating)

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Inner Race Subsurface Condition

Roller coating intact

RESULTS OF TIMKEN CRB (CASE CARBURIZED AND WEAR RESISTANT) AFTER 18 MONTHS

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GEARBOX BEARING HEALTH – OTHER FACTORS• Condition Monitoring• Oil analysis programs and Online oil monitoring systems• Vibration or Shock Pulse analysis

• Oil Selection • Anti-Foaming• Additives / Properties

• Oil System Accessories• Moisture removal systems• Oil filtration systems

• Quality Oil Changes• Frequency based on oil monitoring condition• Vendor oil change features

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Page 39: Wind Drivetrain Bearing Reliability

GENERATOR BEARING OBSERVED DAMAGE MODES•Electrical Fluting •Inadequate Lubrication

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GENERATOR BEARING ENHANCEMENTS• Add on shaft grounding ring • Upgrade the ground brushes from carbon to metal fiber• Upgrade bearings from metal/ceramic coated to ceramic balls    

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Generator Bearings

Gearbox High Speed Bearings

Gearbox Planet Bearings

Main Shaft Bearings

WIND TURBINE DRIVETRAIN - SUMMARY BEARING DAMAGE AND UPGRADES•Wear Resistant coating

•Case Carburized•Controlled clearance

•Grounding improvements•Ceramic balls

•Case Carburized•Wear Resistant coating

•Wear Resistant coating•Two piece cage•Geometry enhancements

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Questions?Paul Dvorak Windpower Engineering & [email protected]: @Windpower_Eng

Rick BrooksThe Timken [email protected] Phone: 330-471-7812

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Thank You This webinar will be available at

www.windpowerengineering.com & email Tweet with hashtag #WindWebinar Connect with Windpower Engineering &

Development

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