GB831955A - Improvements in and relating to dynamic balancing machines - Google Patents

Abstract

831,955. Measuring rotor unbalance electrically. PARSONS & CO. Ltd., C. A. May 28, 1957 [March 2, 1956], No. 6585/56. Class 40 (1). [Also in Group XXXVI] The magnitude and phase of the unbalance of a rotor in two bearing planes is determined by measuring the magnitude and phase of the voltage required to reduce the unbalance indications to zero, and are combined with similar measurements of unbalance due to calibrating weights in each of two balancing planes to determine the magnitude and phase of the unbalance in the two balancing planes. As shown (Fig. 1), a rotor a, supported in bearings b, c, has its unbalance detected by inductive pick-ups d, e mounted on the bearing pedestals. A 3-phase generator h is driven with the rotor and supplies the stator of a selsyn unit, whose rotor is rotatable to produce a voltage of the correct phase which is fed via a potentiometer to neutralize the unbalance signal of each pick-up separately, the phase and magnitude of the opposing voltage being indicative of the phase and magnitude of the unbalance at each bearing. With the unbalance voltages thus neutralized electrically, a calibration weight is placed in a known position in balancing plane k and the new unbalance voltages measured as before. This is repeated with the calibration weight in balancing plane n, and the six readings are combined vectorially to determine the magnitude and phase of the unbalance in the balancing planes k, n.