gear drive - ABM

Application and Development in Large
Scale Grinding Mill Gear Drive

1 Foreword

1
SABC(ABC) will
replace the
traditional three
sections of crushing
/ball-milling
Simplifying process,
Saving investment,
Increasing output.
Process Optimization
1.1 Development Tendency
2
Ball Mill
Ф 26 (28)
Ф 7.9m (8.5m)
AG/SAG Mill
Ф 40 (44)
Ф 12.2m(13.4m)
Large in Specification
3
Various drive
modes and
various bearing
types.
Optimization of
Auxiliary
Equipment.
Structure Diversification
4
DCS system
becomes more
perfect
and achieves
closed-loop
control of
process
optimization.
Operation Automation

Mill Diameter D0 (m)
14
12
10
8
6
4
2
0
Mill Diameter.
1960 1970 1980 1990 2000 2010
Years
Ball Mill SAG Mill
1.2 Large in Specification
Power P0 (MW)
30
25
20
15
10
5
0
Mill Power
1960 1970 1980 1990 2000 2010
Years
Ball Mill SAG Mill

The specification of equipment tends to large which can achieve
-- Expanding the scale of production
-- Reducing the initial investment and operation costs
-- Saving energy
-- Improving the components reliability and service life
-- Reducing down time and improving operation efficiency
-- Increasing recovery
-- Maximizing benefits

Drive mode
Single motor gear
drive
Double motors gear
drive
Ring motor
gearless drive
1.3 Drive Mode
The large in specification requires diversification of drive mode which
mainly depends on gear manufacturing capacity
Maximum power
P 0MW
8.511.5
1723
1723

Single motor drive
synchronous motorair clutch asynchronous motorreducer

Double motors drive
Double synchronous motors drive Double asynchronous motors drive

Low speed
Synchronous motor and asynchronous motor
synchronous
motor
+ Air clutch
+ Open gear
Gear Gear drive drive
drive
High speed
asynchronous
motor
+ Reducer
+ Open gear

Advantages
of
synchronous
drive
1 Without reducer, reducing in failure rate and increasing in drive
efficiency
2 Advancing in power factor which can make up for grid power factor
of concentrator and reduce operation cost
3 Brushless excitation increases its reliability
4 Large air gap makes its ventilation cooling conditions well
5 With air clutch, motor can be no-load startup, which reduces
starting current and torque, and also plays a safety protection role

Key factors of double motor drive

The key problem of double motors drive is equilibrium loadings:
1 Double synchronous motors drive
GE Quadramatic system adopts double low speed synchronous motor and double air
clutchs.
Special air clutch pulse technology can correct disequilibrium loadings and realize
coarse adjustment; Q winding and regulating device of motor can correct motor load
angle and realize coarse adjustment.
ABB ACS system adopts double high-speed synchronous motors whose frequency
conversion technology can relize the double motors equilibrium loadings.
2 Double asynchronous motors drive
due to its soft features, it easily realize equilibrium loadings.

The restriction of gear processing technology creates high power gearless drive
technology (ring motor) which has the features that it is not limited by power, its
drive system relatively simple and high efficiency.
1 The initial investment will be higher about 25% than that of gear drive.
2 Dimension of ring motor is large, so it needs large lifting equipment and long
installation period.
3 The equipment need special maintenance personnel.

Gearless Drive (Ring Motor)

For the reasons above,
Advantages of gear drive
gear drive is the preferred choice of grinding mill.
1 Initial investment and operation cost are reduced;
2 Successful operation of thousands of equipment proved the
reliability and durability of gear drive;
3 At present, we can provide 23MW gear assembly which can
replace gearless drive(ring motor) in a wide range.

Total Power P0 (MW)
35
30
25
20
15
10
5
0
1.4 The limits of gear drive
P0 = f(D0)
0 2 4 6 8 10 12 14
Diameter D0 (m)
SAG Mill Ball MILL Single Pinion Limit Dual Pinion Limit

All kinds of drive ratio

Based on Stuart M. Jones and Jr. Moris Fresko's world statistical data of AG/SAG
calculated according to total power( to 2010)
ring motor 26% power>23MW 7%
power

2 Design

Gear failure forms
2.1 Gear failure forms
--Teeth broken caused by overload and fatigue
-- Wear normal wearabrasive wearscratchglue together
scuffing corrosive wear
-- Pitting Initial pitting destructive pittingfatigue pitting flaking
-- Crack quenching/solidification cracking materials crack
shallow crackfatigue crack
-- Distortion dent rippleroll extrusionheat flow
-- Corrosion chemical corrosionabrasion
-- Other types of damage galvanic corrosionoxidationoverheating

Main forms of grinding mill gear failure
-- pinion tooth broken (Poor heat treatment or fatigue toothbroken)
-- gear pitting (contact fatigue)
pinion tooth broken gearwheel pitting

Reasons of gear failure
-- caused by design and manufacturing:
design mistakes
material selection
manufacturing quality
-- caused by usage and maintenance:
faulty lubrication
installation mistakes
bad operation

2.2 Gear strength calculation AGMA standard
Internationally accepted AGMA standard for open gear strength calculation,
there are 3 versions:
1970 1988 2006
AGMA321.05 AGMA6004-F88 ANSI/AGMA6114-A06

Correction factors

2006 version Adding content
Material (SGI, ADI)
Check (M1,M2)
Service life
Flange thickness
Profile modification
Instantaneous overload
Supporting type
Service coefficient
Other coefficients

Comparison of three strength calculation standard
Comparison of three strength calculation standard
1 AGMA 321.05 (1970 version)
more conservative it has been used for more than40 years, not appear
failure, and approved by many companies, but its service coefficient has
been corrected;
2 AGMA 6004-F88 (1988 version)
calculated by Q8 and manufactured by Q10, its result is equal to 1970
version;
3 AGMA 6114-A06 (2006 version)
the result is between 1970 and 1988 standard, and taken more
consideration about factors based on advanced gear technology, and
accepted by many companies.

CITIC apply AGMA 6114-A06 (2006 version) based on many years
experience for gear design and manufacturing.
The development of CITIC exposed gear calculation program CS06-10.2
(the latest version)
The results of 3 AGMA standard can be quickly got , and the calculation
basis is 2006 standard
2.3 Program and Spectrum of CITIC gear
After optimization of gear parameters, we have completed CITIC gear
specification spectrum CT06-01.1

The drive of high power gear requires higher tooth surface
hardness and machining precision
Increase of gear
diameter
Increase of
transmission power
Requirements of high power gear
<
Increase of tooth surface hardness
Increase of mill
diameter
Inincrease of stalled
power
Improvement of machining accuracy

Current available tooth surface hardness and machining precision
Tooth surface
hardness
Machining
precision
Gear
HB300~350
AGMA 10
ISO 7
Pinion
HRC57~61
AGMA 12
ISO 5

Total Power P0 (MW)
25
20
15
10
5
Tooth surface hardness — Total installed power
P0 = f(HB)
0
160 180 200 220 240 260 280 300 320 340
Minimun Surface Hardness of Gear (HB)
Single Pinion Dual Pinon
Strength (N/mm 2 )
1200
1100
1000
900
800
700
600
500
400
300
Hardness-Strength
200
160 180 200 220 240 260 280 300 320 340 360
Hardness (HB)
Tensil Strength(min) Yield Strength(min)

Total Power P0 (MW)
25
20
15
10
5
0
Gear normal module — Total installed power
P0 = f(mn)
0 5 10 15 20 25 30 35 40 45 50
Normal Modulus mn (mm)
Single Pinion Dual Pinion

Total Power P0 (MW)
25
20
15
10
5
0
External diameter of gear — Total installed power
SAG Mill P0 = f(d0)
9 10 11 12 13 14 15 16
External Diameter of Gear d0 (m)
Single Pinion Dual Pinion
25
20
15
10
5
0
Ball Mill P0 = f(d0)
SAG Mill Ball Mill
Total Power P0 (MW)
9 10 11 12 13 14 15 16
External Diameter of Gear d0 (m)
Single Pinion Dual Pinion

Total Power P0 (MW)
25
20
15
10
5
Weight of gear —Total installed power
P0 = f(G)
0
60 70 80 90 100 110 120 130 140 150 160
Estimated Weight of Gear G (t)
Single Pinion Dual Pinion

13-23 MW Gear parameter – SAG double motor
(from CITIC gear spectrum)

13-23 MW Gear parameter- Ball mill double motor
(from CITIC gear spectrum)

Type SAG Mill Ball Mill
Specification Φ 12.8×6.4 m (Φ 42×21 ft) Φ 8.5×14.6 m (Φ 28×48 ft)
Specification
of drive motor
Type of drive
motor
Drive mode
2×11500 = 23000 kW 2×11500 = 23000 kW
Double asynchronous
motor/Double synchronous
motor
Double asynchronous
motor/Double synchronous
motor
asynchronous motor+reducer+open gear or low speed
synchronous motor+air cluth+open gear
Module of
gear 45 45
Diameter of
addendum 15340 mm 6 discs 13200 mm4 discs
Width of gear
23 MW Ultra large gear
1150 mm 1150 mm

Gear with installed power of 23 MW
should meet
Diameter of addendum d 0 = 15.4 m
Normal module m n = 45 mm
Minimum hardness of tooth surface HB = 300
Weight G = 150 t
The above information determine
Smelting
Casting
Heat treatment
Machining machine
Cutting tools

Ø7.9×13.6 m ball mill gearfour parts bolted structuretightened by special nuts which
reduce field installation work load.

Ø7.9×13.6 m ball mill pinion shaft group

Gearguard equiped with:
1 Infrared thermometer
Monitors tooth surface
temperature on line to avoid
gearing face superheated;
2 Heater
To avoid oil accumulation
when temperature is too low

2.6 Finite Element Analysis FEA
vectogram of comprehensive displacement on gear integral joint

schematic drawing for applying load
on the tooth face
the drawing of Von Mises stress on the
local nodes of the gear

vector gram of comprehensive displacement on the local nodes of
gear (deformation has been amplified for 500 times)

finite element analysis and stiffness analysis for gear guard wind load
to ensure the stiffness of large diameter gear guard in the outdoor environment.

3 Manufacture

Material is smelted in vacuum electric-arc furnace, refined in steel ladle and
deaerated in vacuum.
Casting adopts ring riser.
The process of smelting and pouring is simulated on computer.The company
introduces the world famous simulation software:
Britain JmatPro material software
Germany Magma casting software
France Sysweld welding,heat treatment software, etc
The quality of castings has been greatly enhanced through the application of
these softwares.
3.1 Casting

Simulation software — ring riser
Casting
Solidfication

Smelting
80 t electric-arc furnace

150 t ladle refining furnace

3.2 Forging
The world largest 18500 t oil hydraulic press and operating machine for free forging
The weight of the largest forging piece is 400 t

3.3 Heat treatment
7×16m 9×12m furnace for heat treatment

Carburizing and Quenching for pinion
Φ1.7×6.7m carburizing furnace

3.4 Machining
16 m CNC vertical lathe

22 m heavy-duty vertical lathe

Gear rack shaper
12 m rack shaping machine

Gear hobbing
16m CNC hobbing machine

Mechanically clamped carbide hobs can effectively guarantee ccuracy
of gear tooth surface.
Cutting tool
Kenner modulus 36 mechanically clamped carbide hobs

Hobbing for pinion
Φ1.4 m horizontal hobbing machine

Grinding and profile modification for pinion
Φ2.8 m molding gear grinding machine

Pouring
Australia SINO project, gear pouring
external diameter 11.7 m net weight 118 t liquid steel weight 375 t

Rolling test
rolling test between pinion and gear

Environment - temperature control
It is extremely important to control the environment
temperature, especially the last procedure, which
ensure gear machining precision.
Temperature
control

3.5 Delivery commissioning
CITIC HIC has unique advantages of factory assembly ,no-load commissioning for large scale
grinding mill.
All critical parts are manufactured in our company.
special test platform and generator system for commissioning
No-load commissioning can check gear assembly and meshing, to find and solve possible
problems in advance, and ensure success installation of grinding mill on site for one time.

installed power
2x5586 kW
external diameter of
gear Φ13m
Dexing Copper Mine of Jiangxi Copper Company (22500 t /d)
installed power
2x5586 kW
external diameter of
gear Φ10.8m
Φ10.37×5.19 m SAG (11172kW) Φ7.32×10.68 m ball mill (11172kW)
delivery commissioning in april, 2010

installed power
2x6343 kW
Wushan Copper-molybdenum Mine in inner Mongolia ( 35000 t /d)
external diameter of
gear Φ13.3m
installed power
2x8500 kW
external diameter of
gear Φ11.6m
Φ11×5.4 m SAG (12686 kW) Φ7.9×13.6 m ball mill (17000 kW)
delivery commissioning in october, 2011

Australia SINO Iron Mine (230000 t /d)
installed power
2x7800 kW
external diameter of
gear Φ11.7m
Φ7.9×13.6m ball mill (15600kW double asynchronous motors) 6 sets
delivery commissioning in july, 2009 of first set

installed power
2x6750 kW
external diameter of
gear Φ10.8m
Taiyuan Iron and Steel Co. (66700 t /d)
installed power
2x5500 kW
external diameter of
gear Φ10.8m
Φ7.32×12.5 m (13500 kW)Φ7.32×11.28 m (11000 kW) ball mill each 3 sets
delivery commissioning in may, 2011

4 Application

1 The following parameters must meet inspection
requirements when installing,
(1) radial run-out of gear
(2) end face run-out of gear
4.1 Installation and commissioning
(3) contact area of meshing between pinion and gear
(4) back lash between pinion and gear

2 Tooth surface temperature monitoring (especially in the early operation period )
if temperature difference is over 10 0 C along tooth width, it means poor
contact between tooth surface. The possible reasons followed:
-- skew of gear caused shell distortion when full load
-- foundation bolt looseness
-- foundation subsidence etc
It need readjustment
3 Tooth surface vibration monitoring (installed on pinion bearing pedestal)
to avoid system resonance, it need to do modal analysis for equipment and
foundation in advance.

finite element mesh of global ball mill and foundation model

engage -X links model overall displacement, self weight + charge mass, view 1
(10% exaggerated scale)

喷射润滑装置
喷射润滑装置
4.2 Lubrication

4.3 Control
The control and protection system adopt PLC control, touching screen display and multiple
detection device to ensure reliability of operation and realize automatic control.

6 Bibliography

1 D.Danecki F.Thomas A.Grandy H.Walters
Selection and Evaluation of Grinding Mill Motors and Drives (2003)
2 M.Jones, Jr.Moris Fresko
Autogenous and Semiautogenous Mills 2010 Update
Gear strength standard
3 ANSI/AGMA6114-A06
Gear Power Rating for Cylindrical Shell and Trunnion Supported Equipment
(Metric Edition)

Gear accuracy standard
4 ANSI/AGMA2015-1-A01
Accuracy Classification System-Tangential Measurements for Cylindrical Gears
5 ANSI/AGMA2015-2-A01
Accuracy Classification System-Radial Measurements for Cylindrical Gears
6 GB/T10095.1-2008 / ISO1328-1:1995
Cylindrical Gears System of Accuracy - Part 1: Definitions and Allowable Values
of Deviations Relevant to Corresponding Flanks of Gear Teeth
7 GB/T10095.2-2008 / ISO1328-2:1997
Cylindrical Gears System of Accuracy - Part 2: Definitions and Allowable Values
of Deviations Relevant to Radial Composite Deviations and Runout Information

Thank You!