Balancing Rotating masses -flywheels- rotors- Impellers with IPhone

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Support this channel on Patreon https://www.patreon.com/user?u=3620781 Check out my store front https://www.amazon.com/shop/nobox7 https://www.patreon.com/user?u=3620781oxygen bottle valve In this video we look into static balancing, balancing rotoating masses is very difficult so i decided to try a new aproauch to the problem of rotor balancing .
be found in a rotor whose diameter is
less than 7 to 10 times its width. In the
case of a cylinder, shown in Fig. 2, it is
possible to have two equal masses
placed symmetrically about the centre
of gravity, but positioned at 180° from
each other. The rotor is in static balance,
i.e. there is no eccentricity of the
centre of gravity, but when the rotor
turns, the two masses cause a shift in
the inertia axis, so that it is no longer
aligned with the rotation axis, leading
to strong vibrations in the bearings.
The unbalance can only be corrected
by taking vibration measurements
with the rotor turning and adding correction
masses in two planes.
The difference between static balance
and couple balance is illustrated
in Fig. 3. It can be seen that when the Fig. 2. Couple unbalance
rotor is stationary, the end masses balance
each other. However, when it rotates,
a strong unbalance is experienced.

Dynamic Unbalance, illustrated in
Fig. 4, is a combination of static and
couple unbalance and is the most common
type of unbalance found in rotors.
To correct dynamic unbalance, it
is necessary to make vibration measurements
while the machine is running
and to add balancing masses in
two planes.
Rotors are classified as being either
rigid or flexible. This Application
Note is concerned with rigid rotors
only. A rigid rotor is one whose service
speed is less than 50% of its first
critical speed. Above this speed, the
rotor is said to be flexible. A rigid
rotor can be balanced by making corrections
in any two arbitrarily selected
i rnr u i ■ A £ Fig. 3. Static balance, couple unbalance
planes. I he balancing procedure tor *
flexible rotors is more complicated,
because of the elastic deflections of
the rotor.
Fig. 4. Dynamic unbalance
O
Principle of Balancing
A rotor is balanced by placing a correction
mass of a certain size in a position
where it counteracts the unbalance
in the rotor. The size and position.
of the correction mass must be
determined.
The principle of performing field
balancing is to make (usually temporary)
alterations to the mass distribution
of the rotor, by adding trial
masses, and to measure the resulting
phase and magnitude of bearing vibration.
The effects of these trial corrections
enable the amount and position
of the required correction mass to be
determined. The values are usually
calculated with the aid of a pocket
calculator.
Fig. 5. The basic measurement chain
Any fixed point on the bearing experiences
the centrifugal force due to
the unbalance, once per revolution of
the rotor. Therefore in a frequency
spectrum of the vibration signal, unbalance
is seen as an increase in the
vibration at the frequency of rotation.
The vibration due to the unbalance
is measured by means of an accelerometer
mounted on the bearing housing,
see Fig. 5. The vibration signal is
passed through a filter tuned to the
rotational frequency of the rotor, so
that only the component of the vibration
at the rotational frequency is
measured. The filtered signal is
passed to a vibration meter, which displays
the magnitude. The indicated
vibration level is directly proportional
to the force produced by the unbalanced
mass.
The phase meter measures and displays
the phase between the signal
from the tachometer probe (the reference
signal) and the filtered vibration
signal. The angle displayed by the meter
enables us to locate the angular
position on the rotor of the unbalance,
relative to the datum position. DISCLAIMER: In this video description contains affiliate links, which means
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