Colibri Sander BLO 80 2 1 C 30 Instrukcja Użytkownika Pobierz pdf (Strona 20)

Why is balancing important?

Force (F) generated by unbalance can be calculated from formula:

F(Kg)= 0 . 001 x(gmm)x(RPM/ 1000 )

F(Kg)= 0 . 001 x(w x r)x(RPM/ 1000 )

where w = Unbalance weight in grams

r = Radius in millimetres

Effects of Unbalance

Reduced component life.

Bearings, seals, windings, rotor bars, foundations, supports.

Impaired clearancs / tolerances.

Component displacement, Reactive misalighment.

Resonance.

Flexing of critical speed rotors.

Excessive vibration and noise

Health / safety considerations

Poor product quality.

Diagnosing Unbalance

Vibration frequency equals rotor speed.

Vibration predominantly RADIAL in direction.

Stable vibration phase measurement.

Vibration phase shifts in direct proportion to measurement

direction.

Causes of unbalance

Rotor not mass centred geometrically

Machining / casting inaccuracioes.

Fitting / assembly tolerance inaccuracies.

Uneven mass distribution

Windings / commutator segments.

Blow holes / inclusions in castings.

Component mismatch.

Keys / keyways.

Causes of unbalance

Service effects

Thermal dimensional changes:

Stress relieving.

Uneven thermal growth.

Thermal displacement / loosening of components.

Displacement / settling of components:

Windings Impellers Fan side plates.

Deposit build-up / Erosion / corrosion.

Rotor flexibility

Forced whip.

critical speed deflection.

Induced by other forces

Aerodynamic.

Hydraulic.

Electrical.

SPINDLE BALANCIN

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Colibri Sander BLO 80 2 1 C 30 Instrukcja Użytkownika Strona 20

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