01 unbalance - definitions

8/3/2019 01 Unbalance - Definitions

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Balancing andDiagnostic Systems

Unbalanc

e

consequences,causes,definitions...

Fundame

ntals-Part1

unbalance,C.o.G

.,eccen

tricity,cen

trifugalforc

e,vek

tor...

Fundame

ntals-Part2

axialunbalanced

istributiononrigidrotors,type

sofunbalances...

Tolerances

quality

grade,allocationofbalancin

gplanes...

Measurin

gUnbalance

balancin

gmachin

es,accomodation,drive,mea

surin

gprinciples...

Balancingspeeddetermin

edby

balancin

gmasch

ine,rotor,econom

y,safety...

Correctio

nofUnbalance

typesofcorrectio

n(add,remove,shift),econom

y,errors,tolerance...

Errors

phenomena,causes,types,cure

(typicalexam

ples

)...

Stateofa

Rotor

rigidrotor

(consta

ntbehaviour),otherrotors

(variable~

)...

Addentum

articles...


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Why Balance ?


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What isbalancinggood for?

Seminar-Chapter-Subject-Page 11-01-01-01

Reasons for balancing

Unbalance can ...

Increase: stresswearvibration

noise

Reduce: functionlife spancomfortproduct quality

Disturb: machines

humans


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Whatcausesunbalance?


Design and Drawing Errors

parts not symmetrical

non-machined surfaces

run-out

Errors in Materials

voids in cast parts

changing density of material

uneven / unsymmetrical

run-out of antifriction bearingse.g. ball bearings

Conditions in Operation,Environment and Transportation

Causes of unbalance

Unbalance can result from ...

Production and Assembly Errors

error in shape / outline whenwelding or casting

missalignment e.g. of journalseccentric, inclined

plastic deformation e.g.

missaligned assembly,

transportation

internal stress,

permanent deformation

shrink-fit, welding

variation of material / parts

e.g. srews, washers

balancing errors


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It started at an early age

A phenomenon was discoveredAn unbalanced waterwheel willposition itself such that its center ofgravity will be below the axle when the

waterwheel is stationary.


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Knowledge slowly ripens

Unbalance is a vector By adding a mass m

m of the correct amount ata correct position

the waterwheel will be in balance.

It will now turn smoothly evenwith lower current

The beginning ofbalancing technique.


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Modern times bring further understanding

.

There are several unbalance conditions


Two opposing excentric massescan only be detected duringrotation due to centrifugal forces.

The phenomenon is called couple unbalance


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What is balancing?

DIN ISO 1925

November 1996

A definition according to DIN ISO 1925

Balancing is a procedure during which themass distribution of a rotor

corrected to ensure that theresidual unbalances

within fixed limits.

is tested and if

necessaryrespectively the

vibrations of the bearing stubs or the bearingforces will remain

ISOdefinition


01 unbalance - definitions

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