Page 343 - Machinery Component Maintenance

Buluncing of Machinery Components 325

applied at the calculated angular positions. A subsequent check run
of the centrifuge will determine the correctness of the balancing
measures and will show whether an additional correction process is
required.

Explanation of Schedule and of Calculator Program

The results of the initial unbalance run, of both test runs, and the mag-
nitude of the calibrating masses used are entered in appropriately num-
bered spaces. After inserting balancing module, the measured values are
keyed into the pocket calculator. By calling up the stored data, the pocket
calculator immediately indicates the required masses for unbalance cor-
rection either in polar form or in the form of 90" components.
If the residual unbalance of the rotor exceeds the allowable tolerance,
it is possible to calculate the correction masses for further correction by
using the measured values of the check run but without any need for new
test runs. The influence coefficients which may on demand be indicated
and noted make it possible to rebalance a rotor without test runs even
after a long time interval.

Third Problem: Unbalance Vibration in Misting and Stranding Machine.
Machines for the production of wire rope, cable and flex operate with
multi-bearing rotor systems which consist of two or more part rotors cou-
pled together with angular rigidity. A type which frequently occurs in
practice is shown schematically in Figure 6-48. Rotor systems of this
type are difficult to balance in their completely assembled form on bal-
ancing machines but are better balanced divided into their individual ro-
tors. After assembling the balanced component rotors, new unbalances
can occur due to fits and tolerances, alignment errors and centrifugal
force loading. This is also the case when replacing rotating wear parts
such as, for example, the wire guide tube in stranding machines.
Any excessively large residual unbalance leads to considerable me-
chanical vibration and to the excitation of mounting and machine reso-
nances. Both of these factors can lead to damage of the machine and
physical and psychological strain on the operating personnel. Frequently
the only first aid measure available is a reduction in the production rate
by reducing the operational speed. This, however, is only tolerable over a
limited time span. The economics of the process require a longer term
solution that can only be found in field balancing the complete rotor sys-
tem.