Mill Bearings And Lubrication (tst)

Mill Bearings and Lubrication

Objectives

To know the types of bearing systems on tube mills To understand the lubricating system for the bearings To be able to assess condition of the bearing system

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Agenda  Design   

General Bearing Lubrication Systems QCE standards for bearings and tires

 PMRs 

Inspections

 Troubleshooting  Bearing Replacement

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Mill Bearings  The following pictures shows the two main bearing types

Slide Shoe Bearings

Trunnion Bearings

(e.g. in Combination with Central Drive)

(e.g. in Combination with Pinion Drive)

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Mill with Slide Shoe Bearings Thrust Bearing (axial)

Slide Shoe Bearings in Combination with DMGH Drive

Slide Shoe (radial)

(Flender Combiflex) 5

Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Mill with Slide Shoe Bearings Slide Shoe

Double Slide Shoe Bearings in Combination with DMGH Drive (Flender Combiflex)

Fixed Support

Adjustable Support 6

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Adjustment of Slide Shoe Bearings

Static bearing shoe

Adjustable bearing shoe

Pre setting of adjustable bearing shoes by manual check at pressure gauges (5 bar difference is tolerated) Final adjustment according to bearing temperature during operation (3 °C temperature difference between each bearing shoe within one mill side is tolerated) Set points: Slide Shoe Temperature: 75°C  Alarm

80° C  Mill stop 7

Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Alarm Settings Trunnion bearings •70°C Alarm , 75°C Mill stop Trunnion bearings without temperature device, have to be checked by Pyrometer directly on the trunnion shaft surface during mill operation

• Changing of oil 1 time a year Pinion bearings • 60° Alarm, 65°C mill stop Bearings without temperature device, have to be checked by Pyrometer directly on the pinion shaft

•Changing of oil 1 time a year •Vibrations in horizontal, axial and vertical direction up to 7,1 mm/s are tolerated Slide Shoe bearings  75° Alarm, 80°C mill stop Holcim Group Support

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Slide Shoe Bearing Slide Shoe

Swivel Bearing

Hydraulic Cylinder

Lock Nut

Thrust Bearing

Housing

Pressure Port Holcim Group Support

Base Frame Ball Mill Bearings and Lubrication

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Lubrication Principle  For both, trunnion and slide shoe system the basics are

the same  Oil is used to lubricate the surface between the rotating

parts and the fixed foundations

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Trunnion Bearing

White Metal

Spherical Calotte

Bearing Housing 11

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Lubrication System

Low Pressure High Pressure

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Components of the Lubrication System 7

6

8 9

5 3

8

2 7

4 2

3

5

12 1

3

2

2 1

11 10 10

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Components of the Lubrication System 1.

Low Pressure Pump

2.

Check Valve

3.

Pressure Relief Valve

4.

Recirculating Valve for Heating Up

5.

Filter system with differential pressure gauge

6.

Oil Cooling, heat exchange system

7.

Flowmeter

8.

Temperature Sensor

9.

Water/Glycol Heat Exchanger for Bearing

10. Pressure Sensor 11. Tank Heater with Temperature Control 12. High Pressure Pump 14

Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Disadvantage Advantage

Comparison

Slide Shoes

Trunnion

No limitation in mill size No complicate casting required Simpler design of outlet diaphragm Big openings allow higher gas flow

Well known design Lower bearing surface speed  less heat generation due to friction in oil film

Need precise adjustment work (especially with 4 shoes per side) very sensitive for inadequate lubrication

High stressed area in the transition between trunnion and wall  (risk for cracks) Gas temperature affects bearing temp 15

Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

The Two Main Problems with Trunnion Bearings 

Lack of Lubrication:  



Metal to metal contact Heat generation and melting of the White Metal

Hydro Dynamic Fatigue:  

 

Oil gets pressed into micro structure of the White Metal The high oil pressure forms microscopic cracks The cracks grows and connect to each other Peaces of White Metal break out  Bearing Failure

Note: The Hydro Dynamic Effect is increased by:  High porosity of the White Metal casting  High specific bearing pressure (heavy Mill / Small Bearing)  Run out on Trunnion  Oil film pressure peaks 16

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Damaged Trunnion Bearing

Cracked White Metal Layer

Heavy Breakouts due to Hydro Dynamic Effect 17

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Quality Control of Equipment - Bearing  A final inspection after manufacturing of a new bearing

should include the following:    

   

Visual inspection Ultrasonic test and hammer test of bonding White Metal thickness measurement Dye penetration test of borders Surface roughness test Hardness Test Curve radius and other Dimensions Review of documents and certificates

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Measuring Play in Trunnion Bearing  The play for trunnion bearings is crucial for a proper

lubrication film between the trunnion and the bearing Value for a 120° bearing

For a 180° bearing

b = 710 mm  x1 & x3 b = 910 mm  x2 & x4

Without Load Ø Trunnion

Example:

1350

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b

Full Load Without load

Fully loaded

120° Bearing

X1

X2

X3

X4

200

0,6

0,3

0,3

0,2

Ball Mill Bearings and Lubrication

19 27.09.2019/TST

Bearing Replacement - General  The mill must be lifted and

secured in place to allow the bearing to be removed  Using the overhead crane, slide

out the bearing with a nylon strap. Keep tight as you pull it away  Check the bearing “play”

when installing, and scrape to supplier recommendation as necessary 20

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Bearing Replacement - General

 Check that there is sufficient

axial clearance between liner and trunnion

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Extra Slides

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Example of Operational Settings

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Holcim Group Support floating bearing

........................ mm.

KP supply

Test run:

Running-in side

Krupp Polysius:

Place:

Signature

Running-out side

Prior to scraping

The dimensions have been checked in

Running-out side

Gaps at trunnion bearings

Polysius

Code word/ Client:

Ball mill:

Bearing temp.

after

*) rated size see data on attached page

Running-in side

has been changed

hrs

Surface of main contact

without load

After scraping

with load

fixed bearing

supplied by client

With load

4. The following dimensions have been checked on ...............

3. The trunnion bearing of

2. The diameter of the trunnion is

Signature

27.09.2019/TST

Date:

Without load

Running-in side

about 1/3

Check with feeler gauge

Gaps at trunnion bearing (bearing clearance)

1. The bearing bush is

Client:

Ball Mill Bearings and Lubrication 24

Ball Mill Bearings and Lubrication 27.09.2019/TST

Date:

Place:

Signature

Installed with full mill load

Gaps at trunnion bearings Enclosure

Polysius

Code word/ Client:

Ball mill:

alarm at 70 °C shut-down at 75 °C in normal case Deviations of the values mentioned above only with the agreement of the mill department Bearing temperatures:

Krupp Polysius:

Signature

Client:

Trunnion bearing with load

Surface of main contact. About 90 % of contact should be achieved.

Test run: after 8 hrs of operation the bearing temperatures should be stabilised

Trunnion bearing Ø

Trunnion bearing without load

Trunnion bearing without load

Trunnion bearing with load

Gaps at trunnion bearing (bearing clearance)

Rated dimensions

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Trunnion Bearing

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST

Slide Shoe System

Slide Shoe

Lubrication System 27

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Ball Mill Bearings and Lubrication

27.09.2019/TST

Trunnion Bearing

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Holcim Group Support

Ball Mill Bearings and Lubrication

27.09.2019/TST