The dependence of the measured values
L from distance (a+b) and R from distance (a+b+c)
respectively becomes obvious from the straight lines in Fig. 1. They intersect the axis in the
measuring planes. The forces in the measuring planes increase linearly with increasing
distance. It is quite obvious that the the effects of force relations increase in the ratio
ba
L
+
and
cba
R
++
respectively
with increasing distance. Consequently the mistake in the calculated unbalance
U
R
will be
disproportionately large if the sensitivity of only one transducer changes following different
influences such as temperature, fatigue, shock, overload, vibrations in transport, humidity, etc.
The target should be to reduce the effects of force relations such that any change in the
sensitivity of one transducer does not affect unbalance readings disproportionately when
calculated by a plane separator circuit.
The disadvantages specified above are basically typical of a vibratory system with outboard
rotors. Using state-of-the-art technology an improvement is hardly possible because of given
physical restrictions.
A possibility to improve the results is the physical displacement of the right measuring plane
to outside the machine housing such as illustrated in
Fig. 2. In this case the hollow space
inside the rim is used, for instance with
geodyna 3001 of HWT and all machine types of
Balco. Given the rim shapes as they are displacement is quite limited and possible for one
measuring plane only.
Fig. 2
Measuring system with physical support of the rotor outside the machine housing
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