cornell wind workshop

Cornell Wind Workshop – 6-13-2009

Challenges of Large MMW Challenges of Large MMW Gearboxes in Wind Turbine Gearboxes in Wind Turbine ApplicationsApplications

Michael Sirak, PE, GE Transportation Michael Sirak, PE, GE Transportation Tony Giammarise, GE TransportationTony Giammarise, GE Transportation

Cornell UniversityCornell University 12-13 June 200912-13 June 2009

GE Transportation

Industry Trends

DriveTrain Description

Challenges Moving Forward

Design

Manufacturing

Validation


GE … a tradition of innovation

Founded in 1878 as theEdison Electric Co.

130 years of successful operation

320,000 employees worldwide

Strong technology focus … Research centers in Germany, India, China and the U.S.


Four segments … aligned for growth

• Aviation• Enterprise Solutions• Healthcare• Transportation

• Aviation Financial Services

• Commercial Finance• Energy Financial

Services• GE Money• Treasury

• Cable• Film• International• Network• Sports & Olympics

• Energy• Oil & Gas• Water

Energy Infrastructure

Technology Infrastructure

NBC UniversalCapital

• Aviation• Enterprise Solutions• Healthcare• Transportation

• Aviation Financial Services

• Commercial Finance• Energy Financial

Services• GE Money• Treasury

• Cable• Film• International• Network• Sports & Olympics

• Energy• Oil & Gas• Water

Energy Infrastructure

Technology Infrastructure

NBC UniversalCapital


GE Transportation

•Global Headquarters

•Commercial Operations

•Engineering– Analysis and Diagnostics

Laboratories– Test Development

Laboratories

•Manufacturing– AC Inverters– Heavy & Light

Fabrications– Generators– Traction Motors– Locomotive Assemblies– OHV Wheels– Wind Gearboxes

GE TransportationErie, PA

Founded 19075,500 employees

GE TransportationErie, PA

Founded 19075,500 employees

Gear & Gearbox Manufacturing

Wire & Motor Manufacturing

Fabrication & Machining

Rotating Lab


Locomotives

Parts & Service

Propulsion & Specialty Services

Signaling &Comm

FinancialSolutions

Traffic Mgmt

Systems

Transportation2008 Revenue of $5.2 B


P&SS … a derivatives business Mining / OHVDrive Systems

for Mining Trucks

Drivetrain Technologies

Wind Turbine Gearboxes

Marine & StationaryEngines for Boats

& Power Generators

TransitPropulsion for Transit Cars

DrillDC/AC Motors for Drill Rigs

15,000 Engines Operational in 20 countries 18000 drives shipped

Land Based Technology Status

Today’s Land Base Utility Class Turbines

• 1.5 – 3.0 MW Upwind Configuration

• 80 – 100 Meter Tower Height

• Conventional 3 stage gearbox

• Distributed component drivetrain

• Full Span Pitch Control

• Tapered Cylinder Steel Towers

• ~65 kWhr/kg tower top mass

• 200 MW + Windfarms

Performance

• 98% Availability

• 40+% Capacity Factor at IEC-II 8.5 m/s

• CF% +10 pts in last 5 yrs

Clipper 2.5-93

Performance• Average 45+% Capacity Factor

• Availability & Cost Not Well Established

• 11 c/kwhr UK Thames Estuary site

Offshore Technology Status Offshore Technology

• Development and demo stage

• 19 Projects, 900 MW Installed, shallow water

• 3 – 4 MW Upwind Configuration

• 80 m towers

• Monopile & gravity foundations < 15m

• Steel Tapered Towers

• Infrastructure not yet available in US

GE 3.6 MW – Arklow Banks


US 20% Wind OutlookWind ResourceUS has outstanding wind resource

Broadly distributed thru mid-west & west

Offshore in NE

Technology IssuesNeed for technology improvements to compete with cheap coal

Offshore wind not mature

Turbines 5-10 MW req’d

US Has the Wind Resource

20% Wind Distributes per Demand & Resource

TransmissionCorridors an Essential Part of the Solution

Grid IntegrationIntegration of wind forecasting tools

Consolidation of load balance zones

System Balkanization a barrier

WinDS Analysis to Achieve 20%

Land Technology Improvements

• Turbine size increasing from 1.5 to 5 MW

• 20% Reduction In Capital Cost per kW

• 15% Increase In Capacity Factor

• 30% Reduction in O&M Costs

• GW Scale Windfarms

Offshore Technology Improvements

• Turbine size increasing from 3 to 10 MW

• 20% Reduction In Capital Cost

• 15% Increase in Capacity Factor

• 50% Reduction in O&M Costs

Analysis Summary • Existing Technology Achieves 6-

8% Penetration by 2030

• 20% Requires Technology Improvement

• Improvements In Cost, Capacity Factor, and O&M needed

• One cent reduction in COE - 12 billion dollar economic savings per year

Onshore

Shallow Offshore

Deep Offshore

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

2000 2005 2010 2015 2020 2025 2030 2035 2040 2045

Cap

ital

Co

st $

/kW


7GA87 Gearbox


7GA87E – 1.5MW 1:78 ratio Compound Planetary

• 3 stage CP design with helical gearing

• Straddle mounted planet bearings

• Flexible, splined ring gear

• No reversed bending loads on planet teeth

• One high speed stage

• Over 1300 produced

• Oldest fleet at 36 months


Current GET Gearboxes Differential Planetary +

Parallel Shaft2.0 – 2.7 MW @ 14.4 – 18 RPM 1400 – 1900 KNm Input Torque60:1 – 97:1 Ratio PossibilitiesApproximate Weight: 39,000 LbsHorizontal and vertical output shaft locations @ 550mm CD2350 / 2150mm Overall Length2 Simple Planetaries + Parallel

Shaft2.3 – 2.9 MW @ 14 – 16 RPM Input Speed1500 – 1920 KNm Input Torque78:1 – 136:1Approximate Weight: 46,500 LbsHorizontal Output Shaft @ 550mm CD2550mm Overall LengthCompound Planetary + Parallel Shaft1.4 – 1.8 MW @ 16 – 20 RPM 700 – 970 KNm Input Torque59:1 – 86:1 Ratio PossibilitiesApprox Weight: 33,000 LbsHorizontal Output Shaft @ 550mm CD.Working on Vertical Output Shaft for 2009.2200mm Overall Length


Common Gearbox Components2 Simple Planetary + Parallel Shaft Arrangement

Input Carrier – Connects Gearbox to Blades

Input Carrier Bearings – Supports blade loads

Low Speed Sun Gear – Output of first speed increasing Stage. Inputs power to High Speed Planetary Stage

Low Speed Planet Gears – Typically 3, 4, or 5 gears. Meshes with Annulus and Sun Gear.

Input Housing – Supports gearbox torque and blade loads.

Torque Arms – Transfers torque and wind load to turbine structure

Low Speed Annulus Gear – Non-Rotating, fixed to Input Housing.

High Speed Annulus Gear – Non-Rotating, fixed to Input Housing.

High Speed Sun Gear – Output of second speed increasing Stage. Inputs power to High Speed Parallel Shaft StageHigh Speed Carrier Bearings

– Supports Gear loads

High Speed Gear Bearings – Supports Sun Gear & High Speed Gar loads.

Pitch Tube – Conduit for electric or hydraulic supply to blade control system – rotates at rotor speed.

High Speed Gear – fixed to sun gear, drives high speed pinion.

High Speed Pinion – driven by high speed gear. Drives the generator.

High Speed Pinion Bearings– supports gear and braking loads.

High Speed Planet Gears – Typically 3.


Constraints – Design PerspectiveDesign Complexity & challenges

• Dynamic Loads – Extreme coherent gust winds, Turbulent shear winds

• Low “Lamda” – Design challenge to maintain Lamda ratios >1

• High Torque Density

• Loads prediction & understanding

• Torque Arm Design – Currently used for a 1.5-2.0MW turbine Gearbox, but as the MW rating increases, this design becomes complex

• Adequate Cooling & heating – Challenge due to extreme environmental conditions

• Noise control – Huge factor due to noise regulations

• Vibrations

• Seal designs – Current Gearbox industry is challenged is oil leaks either on input side / output side

• Reliability – Design life 20 years

• Weight – Shipping and uptower

Flap Flap deflectiondeflection

Edge Edge deflectiondeflection

Tower Tower loadsloads

Main Shaft Main Shaft MomentMoment

NacelleNacelleYawYaw

Flap Flap deflectiondeflection

Edge Edge deflectiondeflection

Tower Tower loadsloads

Main Shaft Main Shaft MomentMoment

NacelleNacelleYawYaw


Growing wind turbine scale necessitates development of new drive train technology

Roller Speed: 92 ft/s

Roller Speed: 65 ft/s

RotationRotation1,500 RPM

3.6 MW HS Pinion Bearing

Rotation1,500 RPM

1.5 MW HS Pinion Bearing

Problem

•Conventional 3-stage gearbox-based drive trains are sub-optimal as wind turbine rated power grows from 1 MW to 5 MW

•Cause is increasing size of problematic HS Pinion Bearings which require decreasing oil viscosities

•Forces a dangerous compromise … select low viscosity oil to support higher speed bearings OR higher viscosity oil to protect the low speed gear stages

Solution

•Develop technology that eliminates the need for the 3rd (high speed) stage of the gearbox

6

8

1 0

1 2

1 4

1 6

1 8

2 0

2 2

2 4

2 6

2 8

0 5 0 0 0 0 0 1 0 0 0 0 0 0 1 5 0 0 0 0 0 2 0 0 0 0 0 0

(µ-in

)

T o r q u e ( lb f - in )

0 . 1 5

0 . 2 0

0 . 2 5

0 . 3 0

0 . 3 6

0 . 4 1

0 . 4 6

0 . 5 1

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0 . 6 1

0 . 6 6

(µ-m

)

F ilm T h ic k n e s s ( m in )

I S O 3 2 0 - 7 0 C L o w S p e e d S t a g eI S O 4 6 0 - 6 0 C L o w S p e e d S t a g e

+ + + + + + + + +0 . 0 0 5 6 4 9 2 1 1 2 9 8 5 1 6 9 4 7 7 2 2 5 9 7 0

T o r q u e ( N - m )

3 0 0 % T o r q u e

6

8

1 0

1 2

1 4

1 6

1 8

2 0

2 2

2 4

2 6

2 8

0 5 0 0 0 0 0 1 0 0 0 0 0 0 1 5 0 0 0 0 0 2 0 0 0 0 0 0

(µ-in

)

T o r q u e ( lb f - in )

0 . 1 5

0 . 2 0

0 . 2 5

0 . 3 0

0 . 3 6

0 . 4 1

0 . 4 6

0 . 5 1

0 . 5 6

0 . 6 1

0 . 6 6

(µ-m

)

F ilm T h ic k n e s s ( m in )

I S O 3 2 0 - 7 0 C L o w S p e e d S t a g eI S O 4 6 0 - 6 0 C L o w S p e e d S t a g e

+ + + + + + + + +0 . 0 0 5 6 4 9 2 1 1 2 9 8 5 1 6 9 4 7 7 2 2 5 9 7 0

T o r q u e ( N - m )

3 0 0 % T o r q u e

Impact of change from ISO VG 320 to ISO VG 460 oil on Low

Speed Planetary gear film thickness

Film Thickness (mm)

Above Line:Film Thickness > Gear Surface Finish


Relative Sizes & Conversion of mils & microns

~ Diameter of human hair, thickness of copy paper~ 0.1mm = 100 microns = .004 inch

1 mil = .001 inch = 25.4 microns

1 micron = 1 m = 1e-6 meters = .001 mm

Film thickness on low speed wind bearings ~ 0.15 microns!


Gear Design ProcessIdentify DesignInputs

-Loads-Speed-Size, etc

Preliminary GearSizing

-Ratios-Face width-Diameter, etc

Housing Design-Preliminary sizing-Detailed design

Optimize GearMacro Geometry

-Utilize RMC program-Kissoft program

Bearing Selection-Life-Stiffness-Size-Clearance

Detailed FEA-Housing deflection-Carrier deflection-Shaft deflections-Bearing deflections

3-D Mesh - MicroGeometry

-LVR/LDP-Gear stresses-Load Distribution

AGMA/DINRatings

-Predictor for Gear Life

Validation Testing-Strain gaging-Load Distribution

Profiles-HALT testing

Design Complete

Shaft Design-Diameter-Stiffness

Iteration

Iteration


Constraints – Manufacturing Perspective

• Size of Gearing

Size of gears used causes a challenge in manufacturing a quality gear, current industry supported by few suppliers in market

• Heat Treatment Process

Several heat treatment process available but process is generally difficult to monitor and maintain long term process capability

• Steel Quality

• Casting & Machining

• Cleanliness

Plays a major role in the overall reliability of the gear box from performance & life stand point

• Grinding

• Process Quality

Very critical to this business as cost of producing a non-quality part accumulates into a higher maintenance costs

IH process

Gear Mfg defect- not acceptable


Paint

Test StandTrim

& Flush A

ssem

bly

2Po

siti

oner

Ass

embl

y 1

Pit

Ship

Sub Assembly

Pump & Cooler

Subs

Prep-to-Ship

1

2

3

4

5

6

7

8

Gearbox production• Process Capability

– Supplier … component characteristic data– Assembly … validated measurement systems– Test … temp, vibration, particulate count, w ear

• Documentation & Systems– M anufacturing instructions– e-Traveler– Quality system audits– Test documentation

• Cleanliness– Pre and post- test gearbox oil flush to ISO 4406– Component cleaning– Lean supermarket


Constraints – Validation Perspective• Comprehensive commercial testing

• Component testing

• Sub-system testing

• HALT - Every new production or significant change

• Field testing - ~ typically 6 months field test

• Cost – testing costs are expensive but critical

• Larger gearboxes = larger test stands


Reaction at simulated planet pinions

Two synchronous hydraulic jacks used to simulate 1137.6 kNm

Force reacted by ring gear attached to stationary base plate

Component testing … demonstrated 99% reliability at 95% confidence

Input Housing Carrier High Speed Gear Bearing


Cold Chamber Lube System Flow Rate

Strain Gauge Testing

Systems level testing


Simulates 20 yr life on gearing– Loads increased to decrease total test time– 3x and 2x overloads– Run on dedicated engineering test stand

Monitoring– Bearing and oil temperatures– Oil pressures– Stresses in critical components– Power, torque, and speed– Gear wear patterns– Particle count

Capability– 2.5 MW @ 1440 rpm continuous

HALT “graduation” test


Gear Mesh Pattern

- All gear contact patterns were good and passed typical acceptance criteria.

- Gear contact patterns & condition are best indicators of system validation.

- Validates deflection calculations in structures, shafts and bearings

- Validates adequate lube flow


Constraints – Maintenance Perspective

• Filtration – Lube oil used needs regular filtration & maintenance

• Contamination of Oil w/metal particles

• Load Management

• Monitor noise

• Periodic oil sampling

• Shipping & Logistics – Weight & shape of the Gearboxes causing a challenge for shipping & logistics

• Condition based monitoring system – Proactively monitors, detects impending drive train issues, enabling increased availability & decreased maintenance costs

• Uptower Inspection Technology – Barkhausen Noise, Eddy Current

• Can only climb two or three towers per day!

Wind farms in Ocean- greater challenge for maintenance

Large Cranes Used for installation, repair & accessibility


Barkhausen Noise – Uptower Inspections

.

No other teeth had comparative BH values as the damaged teeth. GB was repaired and placed back in service.

1sttooth

2nd tooth

1sttooth

2ndtooth

Surface defect Caused by grind temper

Leveraging uptower inspection and repair


Gear Case Depth Eddy Current Inspection

DescriptionGE-conceived technology that enables non-destructive examination of Gear manufacturing quality

Benefits•Advances state of the art in gear

manufacturing and wind turbine gearbox quality

•Eliminates need for sacrificial parts during gear manufacturing

•Reduces gear inspection process cycle time … manufacturing productivity improvement

•Enables examination of gears after installation in the gearbox

Eddy Current System

Gear Case Depth Profile

0

10

20

30

40

50

60

70

2000 3000 4000 5000 6000 7000 8000 9000 10000

Distance from Edge (µm)

Rc

scan 1

scan 2

scan 3

Gear Case

Case


Location of 2 MW generator coupling

3.5 MW IntegraDrive in

the space of a 3-stage 2.3 MW

gearbox

Turbine Efficiency Comparison

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

P/P rated

Effici

ency

IntegraDrive

Standard DFIG

Conventional Gbx &

Generator

IntegraDrive

No. of Bearings 26 11

No. of Gear Meshes 15 6

Efficiency Range 96.5% - 97.0% 99.3%

System Efficiency 90% 93%

Generates 6% higher AEP versus conventional DFIG drive train

Modular flywheel coupling system … common interface for

multiple suppliers

Compound Planetary Gearbox

PM Generator

IntegraDrive geared generator


Challenges of Design, Manufacturing Validation of large Gearboxes used in wind Turbine Applications

June 12-13 2009, Cornell University

Mike Sirak

Tony Giammarise


X section of a typical 1.5 MW Wind Turbine Gear Drive converts

~ 18 rpm input to 1440 rpm output; hence a speed increasing drive system

GE Energy has the entire system. We at Power Drives are building only the Gear drive portion of the system

This is a talk to show you some of the hardware, and the manufacturing methods/ materials used


Stats for a typical 1.5 MW system

Cut in wind speed 3.5m/s

Cut out Wind speed 25m/s

Rotor diameter 77m

Rotor speed 11.0 to 20.4 rpm

Swept Area 4657 m2

Tower height 80 to 100 m

Near Future 2.0 to 2.5 MW near term, land based (already here in Europe)

Stats for a mating gearbox

Input rpm 18

Output rpm 1440

Ratio 85.71

Input power 1660Kw

Input rated Torque 947000 Nm


The practical issues with Big wind machines and the scale of things :

• Installation

• logistics and access

• Scale reflected in cost and available suppliers; their capacity and location, logistics

• Unscheduled maintaince

~240 ft, (80 m)

sky hook


Gearbox Design is based on a design process where requirements are flowed to Drive Systems from:

•Turbine manufacturers

•public standards

•insuring bodies

•Internally imposed guidelines

Typical Design deliverables include

•Geometrical/Dimensional envelope, details in aux equipment placement

•Power capabilities, input rpm’s output rpm’s

•Weight limit

•Environmental operational conditions

•Temperature extremes

•Wind class

•Emergency stops/overload conditions

•Noise limits

•Reliability guarantees

•Certification from insuring body


Gear box materials flow from design requirements, customer requirements and insurance bodies

Structural Components

Moderately large Machined Ductile Iron Castings with

Soundness requirements

Mechanical and Microstructural requirements

Environmental Requirements (Cold weather, -40C)

Gearing

Forged raw materials

Clean Steel Technology required for gear steels

Carburized and hardened

Extensive high tolerance machining AGMA class 12 and higher

Extensive Secondary heat treatments/ finishing operations/ inspections for final acceptance


Bearings

Extensive use of rolling element bearings

~ less than 10% mass of a 1.5 MW gear box are the bearings

Commercially produced by the leading global bearing suppliers

Clean steel technology required

Both thru hardened and case carburized utilized

Bearing issues:

design loads and their complete measurement

Global supply issues of capacity timely deliveries

Earlier generation of gear boxes had life limited bearing failures

.


20000 lbs of 32000 lbs total of the gearbox mass for a 1.5 MW Box is structural castings. Half of that is in one casting.


First stage planetary gears carrier cast ductile iron

Heavy walled Ductile Iron Issues

•Designing for optimized weight to strength ratios

•Soundness of castings and surface quality

•Consistency of Mechanical properties and microstructure throughout

•Cold weather requirement and fracture toughness measurement

•Global supply chains also represent additional manufacturing/ quality risks


Ductile (spheroidal) Iron metallurgy

What it it?

Why Ductile?

Standard structural material, Effectively easy to cast, Lower costs as compared to cast steel, better yields and comparable mechanical properties, machines readily, and insuring bodies allow it!

Properties

Common grade used by many Wind turbine producers

100X Microstructure ferritic ductile Iron


Other structural Castings found in wind turbine system are similar to those within the gear box.

Hub Casting

Bedplate Casting


Bearing locations in a 1.5MW compound planetary gear arrangement

Bearings shown in various colors


Examples of Roller bearing types and usage within a 1.5 MW gear box


Overview of Wind Gearing

Forged raw materials using

Clean Steel Technology & high Hardenability Steels

Carburized and hardened helical gearing

Extensive high tolerance machining AGMA class 12 and higher for reduction of noise, better load sharing

Extensive heat treatments/ finishing operations/ inspections for final acceptance


Clean Steel Technology a Definition

Timken Para-premium

ESR requirement

Steel cleanliness by various melting methods

Air melt requirement

Steel making methods utilized for Clean Steel

•Bottom taping EAF

•Ladle refined

•Deoxidized

•Vacuum degassed

•Bottom poured ingot or con-cast

•Protected from re-oxidation during teeming/casting

•Careful limits on Hydrogen and Oxygen

All of the above need to be done to assure high quality steel

Increasing cost

2x

X

Decreasing steel quality

Double melting

Single melted standard air

Gear & Bearing quality


Manufacturing sequence for typical precision Wind gears

Steel making/ ingot production

Grades 18CrNiMo7-6, 43B17, 4820 and similar

Clean steel technology required/ No naughty bits in the steel/ inspect it

Forging operations to rough shape ingot into forged blank

heat it/ beat it / heat treat it and then inspect it

Gear making operations

rough it, hob it ( First outline of the tooth form )

prep it for carburizing

pump carbon into the surface (Extensive diffusion based high temperature controlled cycles changing the near surface to a different alloy!)

quench it to make it hard

temper it to make is a little less hard but improve it’s toughness

grind it to very accurate finish dimensions

inspect it, measure it, making sure it meets print and is free from manufacturing defects

protect it during storage/shipment


Micro Hardness of a tooth Chip

30

35

40

45

50

55

60

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75

distance form ground surface

Ha

rdn

es

s in

HR

C c

on

ve

rte

d f

rom

V

ick

ers HRC;A

HRC;B

HRC;B1

Typical Case Carburized tooth form and the scale of things

Why Case harden gears

•Resist bending Fatigue loads

•Resist Surface contact Fatigue

•Add compressive residual stress to aid in the fatigue loading capabilities

•Core structure remains ductile

•Highest allowable design loads per all international standards

•Large capacity worldwide for this type of hardening process

Case hardening Terms

•Surface Hardness

•Effective Case depth to HRC 50

•Pitch line Case depth

•Root hardness

•Core hardness

A tooth form showing the surface hardening; scale is in mm

Core

region

Distance in mm from ground surface

Effective case depth

Surface Hardness


Typical Carburized Gear Process

Steel Run

(Heat)

Ingots

29” square

Billets14.5” round corner

MultsForgingsRough Machining

Heat Treat

Carb/Quench

Hard turn/ Grinding

Assembly into Gearbox

240k lbs 30 ingots/run 1 billet/ingot

6-8 mults/billet1 forging/mult1 gear/forging

2 gears/heat treat 1 gear/grind 1 gear/gearbox

Steel Supplier

Forging Supplier (Q =13)Gear Supplier

GE Transportation


916ABP1 HS Gear quality check listProcess Spec Check points Check Frequency

Raw material 9310H grade 2 per C50E76 Must from TIMKENcleanliness per ASTM A534 Every HeatHydrogen content besides chemistry Every Heat

Forging From Canton Drop Forging Reduction ratio

Normalize and temper B50E215 Viual check green painting Every piece

Rough Turning Process sheet Dimension check Every pieceDrilling / tapping Process sheet Dimension check Every piece

Forging soundness AGMA 923 grade 2 UT Every piece

Hobbing Process sheet M.O.P check Every piece

Tooth shapping Process sheet M.O.P check Every piece

Chamfer Process sheet Dimension check Every piece

Carb / Quench Hardness, metallurgical test Every heat lot

Shot peen AMS-S-13165 Coverage/saturation Every piece

Hard turning Process sheet Dimension check Every piece

Enternal tooth grinding Process sheet Gear charts / M.O.P Every piece

Internal spline grinding Process sheet Gear charts / M.O.P Every piece

Dynamic balance Process sheet Every piece

MPI AGMA 923 Every piece

Nital etch AGMA 2007 Every piece

Final inspection blue prints Dimension check, visual check Every piece

Typical Gear Quality Checks


Modern Gear Grinders required to meet the tolerance needs for wind gearing. High quality tolerances needed to reduce noise


Current grinding technology both measures, distributes stock and self corrects dimensions, before and during grinding

The requirements of Wind Gearing also require large capital investments.


Gear Tolerances and the scale of things

Typical AGMA Class 12 gearing found on a 40 inch diameter high speed gear

These magnitudes require temperature controlled grinding processes, temperature controlled measurement processes to produce accurate gears. Accurate tooth form assures uniform loading

Small numbers!


Issues in gear manufacture for wind gear systems

•Special problems of large forgings

•Distortion during heat treatment

•Distortion during quenching

•Achieving adequate case and or core properties in large parts

•Damaging hard surfaces during final grind operations

•Capacity worldwide for large high tolerance gear manufacture


Design success means:

•Understand the requirements

•Know and measure loads

•Utilize knowledge in Public Standards

•Understand the operating environment

•Detail and define requirements and flow them from System, to sub-System, to each component

•Inspect Components using the right methods and technologies

•Manufacture carefully Utilizing the right advanced and traditional tools

•Test to failure

The outcome is, the ability to achieve the level of reliability desired

Thank you


Scale of things: 1.5 MW units

1660 Kw = 2226 HP= 1.6 MW

•GE locomotive=4400 HP,so from a power view, half a locomotive up a pole.

•The entire structure, including the pole is ~ 220 Tons excluding the foundation=weight of locomotive

•The foundation weights ~500 tons


Lake Superior Late March w/ machines as cold as the photo looks

Above the Columbia River, mid summer

Operating Environment

-40C to +40 C

cornell wind workshop – 6-13-2009 challenges of large mmw gearboxes in wind turbine applications...

Documents

wind outlook wind resource

barrier slide

year slide

outstanding wind resource

mw arklow banks slide

cheap coal offshore

7ga87 gearbox slide