how to do field balancing by 904 or 907

8/4/2019 How to Do Field Balancing by 904 or 907

1/51

www.sendig.com 1

Typical Steps of field Balancing

Illustration with model 907

E-mail: [email protected], [email protected]

Telephone: +8610 82895321

Fax: +8610 82895320

http://www.sendig.com

Balancing Training Part 1
mailto:[email protected]:[email protected]:[email protected]:[email protected]


2/51

www.sendig.com 2

1. Collecting Machine data

2. Preparing Instrument & Sensor3. Balancing really required ?

4. Balancing possible ?5. Procedure of balancing

An Overview of the Steps


3/51

www.sendig.com 3

Step 1 - Collecting Machine data Understand the machine to be balanced

as much as possible

Collect machine data

Take a photo of the machine


4/51

Sample: Machine to be balanced

Impeller Parameter:

Diameter: 1400mm Thickness: 500mm

Blade Number: 12

Material:Fiberglass-Reinforced

Plastics

RPM: 1825 r/min

Bearing Model: ?

MotorParameter:

Power: 75kW

RPM: 1500 r/minOthers:

Belt transmission

Spring base

Manufacture: LG

Impeller

Bearing1 Bearing2

Motor


5/51

www.sendig.com 5

Step 2 - Preparing Instrument & Sensors

Sendig-904/907 dual-channel datacollector/analyser/balancer

A notebook computer Sendig-MCM3 Analysis Software


6/51

www.sendig.com 6

Sensors & Cable connecting

Attach reflectingpaper on shaft


7/51www.sendig.com 7

Step 3 - Balancing really required? Use 904/907 to measure overall vibration values

Compare with ISO Standard

1) Switch

to Analyzer

2) Use Collector to

measure vibration



6: Point: Motor-1-Side-2-XAlarm-mode: DisplacementFreq-Range: 500Hz

Sensor:4.6

New Data Old Data ACC xxx / xxx m/s2

VEL 7.2 / 2.1 mm/sDISP 68 / 12 m

ENV xx / xx m/s2

Horizontal VELOCITY is the critical parameter


9/51

Comparison with ISO2372



Overall Value Measurement

Acc. Vel. Disp. EnvelopePeak ms-2 RMS mm/s P_P um RMS ms-2

Hor. 88.81 9.95 101.5 5.268

Ver. 55.89 5.554 38.77 7.362

Sample


11/51

Measurement

9.95 mm/s

Not Permissible, Balancing really required !

Sample



Step 4-1: Balancing possible?single peak spectrum?

Use 904/907 to measure vibration spectrum

Only single peak spectrum can go for balancing

1) Switch

to Analyzer

2) Use Collector to

measure vibration

3) Use C-Spect to

see velocity spectrum



Sample of non-single peak spectrum- not suitable for Balancing


14/51

www.sendig.com 14

Sample of non-single peak spectrum- Better change bearing before balancing


15/51

www.sendig.com 15

Sample of single peak spectrumYou can reduce the vibration by Balancing


16/51

www.sendig.com 16

Step 4-2: Balancing possible ?90o phase difference?

Use 904/907 to measure vibration phase difference betweenvertical and horizontal directions

Only 90ophase difference can go for balancing

1) switch to balancerand use 2-planes

balancing procedure

2) Page down to InitialMeasurement to measure

vibration phase at X & Y

3) See if90o phase difference exist?


17/51

www.sendig.com 17

Phase Measurement:

Velocity Amplitude Phase

Vertical: 9.416 320

Horizontal: 3.08 116

Since phase difference is not 90o nor closer to 90o ,this means the

problem with the fan is something else other than unbalance.

Phase

difference

not 90o

SampleSample of non-90ophase difference

You cannot reduce the vibration by Balancing


18/51

www.sendig.com 18

1. Phase stable

2. Phase Measurement:

Velocity Amplitude Phase

Vertical: 0.693 73

Horizontal: 1.569 150

?

Phasedifference is

77o

SampleSample of nearly 90ophase difference

You can reduce the vibration by Balancing


19/51

www.sendig.com 19

Procedure of balancing

Balancing Training Part 2


20/51

www.sendig.com 20

Different Kinds Of

Imbalance1-plane

imbalance2-plane

imbalance


21/51

www.sendig.com 21

Characteristics Of

Imbalance

1. The vibration frequency is mainly composed of

RPM frequency. For each round the rotor turns, avibration is occurred.

2. The wave is an approximate sine wave.

3. There is a difference of 90o between the vertical

vibration phase and the horizontal one.

4. With RPM increasing, the vibration amplitude is

increased


22/51

www.sendig.com 22

Basic PrincipleOf 1 Plane Balancing

Q

AA01

0AP

amplitude phase RPM

A

1 select a plane to fix trial mass and a

point to measure, draw scale of phase

and sign of 0o phase

2 measure initial vibrationA0(phase

and amplitude)

3 fix a trial mass Q on the plane,

measure vibrationA1

4 calculate influence coefficients:

5 calculate balancing massP:


23/51

www.sendig.com 23

Illustration of 1 Plane Balancing

A0A1

A1- A0

o

drawA0 &A1, calculateA1-A0

measure the angle betweenA1-A0andA0

turn Q aalong the direction of ,gain the correct location of balancingmass.

the weight of balancing mass is asthe following :

Ko

QP

01

0

AA

AQP


24/51

www.sendig.com 24

Method of Influence

Coefficients Method of influence coefficients is

widely used, its step as the following

(1 plane balancing as example):

1 measure initial vibration

2 fix a trial mass

3 measure the vibration with the trial mass

4 calculate the result of balancing mass


25/51

www.sendig.com 25

IF THE INFLUENCE COEFFICIENTS ARE KNOWN, THE

STEP OF FIXING TRIAL MASS ARE IGNORED

The former steps are simplified as the following:

1) measure initial measurement

2) input influence coefficients

3) calculate the result of balancing mass


26/51

www.sendig.com 26

NOTICES DURING THE OPERATION

Confirm the dynamic

balancing are neededaccording to spectrum

and phase analysis.

Direction of phase:reverse to the

direction of rotation

Reflecting slice

phase


27/51

www.sendig.com 27

SELECTING PARAMETERS

Measure displacement or velocity formiddle or low speed machines

Measure velocity or acceleration for highspeed machines


28/51

www.sendig.com 28

CONFIRM whether the trial is suitable

The radius of loading trial mass is as same as loading

the amended mass

The turning speed is steady

beforeandaftertrialvaluedifference25%

phasedifference25okok


29/51

www.sendig.com 29

1-PLANE BALANCING

Withoutinfluencecoefficients

907

A

Tachosensor

Accelerometer


30/51

www.sendig.com 30

Operation Basic Prompt is displayed at the last line

Press and key to move the

cursor up and down

Press Enter to select iterm

Press number keys to input digits

To other MENU, press PgDn or

PgUp


31/51

www.sendig.com 31

Always make sure the Setting

is correct before the balancingEnter a digit, select 1 set of data from 10

Enter a digit, select plan number

Change by ENTER,

use displacement or velocity

for most machines

Input sensitivity (from

accelerometer certificate)


32/51

www.sendig.com 32

INITIAL MEASUREMENT Press Enter to measure

rotation speed first

Press Enter for a momentto measure vibration afterrotation speed becomesteady

After phase and amplitudebecome steady, pressEnter for a moment to endthe measurement


33/51

www.sendig.com 33

TRIAL ESTIMATION Input the 4

parameters

When cursor on 6thline, press Enter tocalculate trial range

Stop the machine, fixa trial mass accordingto the range


34/51

www.sendig.com 34

TRIAL MEASUREMENT Input phase and weight of the

trial, confirm whether it will beremoved afterward, restart themachine

Move cursor to 6th line, pressEnter to measure rotation speed

When RPM steady, press Enter a

moment to measure vibration When amplitude and phase

steady, press Enter for amoment to end themeasurement


35/51

www.sendig.com 35

TRIAL RESULT See what the 6th line

shows

If YES displayed, pressPg Dn to go on

If NO displayed, stopthe machine, adjust

trial mass, return to theearly page of TRAILMEASUREMENT,measure again


36/51

www.sendig.com 36

CALCULATION

Cursor on 2nd line, pressENTER to calculate influencecoefficients

The result is shown in 4th line

Cursor on 2nd line, pressEnter to calculate balancingmass

The result is shown in 3rd line


37/51

www.sendig.com 37

Decomposing/Splitting Input the 2 angles

Display the results

If nothing displayed atright side, change theorder of the 2 anglesand re-enter

Pa

Pa1

Pa2


38/51

www.sendig.com 38

VERIFICATION Cursor on 2nd line, press Enter

to measure rotation speed

When RPM steady, press Entera moment to measurevibration

When amplitude and phase

steady, press Enter for amoment to end themeasurement

The last 2 lines displays theresults


39/51

www.sendig.com 39

1-PLANE BALANCINGWith influence coefficients,

you do not need to add trial

mass. You need only

measure the initial vibration


40/51

www.sendig.com 40

SETTING PARAMETERS

Set Yes for the question

of Have influence

Coefficient?


41/51

www.sendig.com 41

INITIAL MEASUREMENT Press Enter to measure

rotation speed

Press Enter for a momentto measure vibration afterrotation speed becomesteady

When phase and amplitudebecome steady, pressEnter for a moment to endthe measurement


42/51

www.sendig.com 42

INPUT COEFFICIENTS

Move the cursor to the

4th line, inputamplitude and angle ofcoefficient

Press Pg Dn to the nextpage


43/51

www.sendig.com 43

Calculation, Decomposition &

verification

calculate

balancing mass

Decomposition

and verification

are the same as

illustrated earlier

Pa

Pa1

Pa2


44/51

www.sendig.com 44

2-PLANES BALANCING

Without influence coefficients

The main difference than 1-plane:

1. Need to add trial mass one after

another at the 1st plane and 2nd

plane

2. Need to use 2 vibration sensors

Sensors & Cable connecting


45/51

www.sendig.com 45

g

Attach reflectingpaper on shaft


46/51

www.sendig.com 46

SETTING PARAMETERS


47/51

www.sendig.com 47

INITIAL MEASUREMENT & TRIAL

ESTIMATION

Get 2

lines of

reading

here


48/51

www.sendig.com 48

TRIAL I MEASUREMENT Input phase

and weight of

the trial onplane 1,decide if it willbe removed,restart themachine


49/51

www.sendig.com 49

TRIAL II MEASUREMENT Input phase

and weight of

the trial onplane 2,decide if it willbe removed,restart themachine


50/51

www.sendig.com 50

Calculation, Decomposition &

Verification

calculate

balancing mass

Decomposition

and verification

are the same

as illustrated

earlier

Pa

Pa2

Pb Pb1

Pb2


51/51

2-PLANES BALANCING With

influence coefficients

With influence coefficients,

you do not need to add trialmass. You need only

measure the initial vibration.

how to do field balancing by 904 or 907

Documents