GB1498471A - Shaft alignment apparatus and method - Google Patents

Abstract

1498471 Measuring shaft alignment electrically BENTLY NEVADA CORP 3 Oct 1975 [10 Oct 1974 40570/75 Heading G1N [Also in Division F2] The invention relates to apparatus for measuring the misalignment between two shafts connected by a flexible coupling. As shown, Fig. 2, a driving shaft 17 forming part of a fixed machine is connected to a driven shaft 18 by a flexible coupling 12 comprising two hubs 26, 27, Fig. 3, which are keyed to the respective shafts and spaced apart by a flexible tube 34 carrying a diaphragm 37 at each end. Secured to guard rings 39 bolted to flanges 28, 29 on the hubs 26, 27. The guard rings 39 have four cut-outs 46 in each of which is located a plate 47 rigidly attached by a collar 48 to the tube 34, the inner surface of the plates 47 being perpendicular to the axis of tube 34 and normally flush with the inner face 43 of the guard rings 39. Located near each ring 39 is a vertical yoke 52 carrying four proximity probes 51, e.g. eddy current probes, measuring the distances between the yoke 52 and the locally associated plates 47 or the face 43 of the guard ring 39. Two similar probes 56 mounted on a bracket 57 scan the circumferential surface 58 of the flange 29 which is formed with four notches 59 in line with the plates 47, to produce differential signals which determine whether the probes 51 are facing plates 47 or the faces 43 of the guard rings 39. A mathematical analysis shows how the signals from the light probes 51 can be combined to determine parallel misalignments in the vertical and horizontal planes, and angular misalignments in the vertical and horizontal planes. The signals are combined to determine the modifications in height necessary at the bearing supports of the driven shaft to obtain proper alignment. The probe signals may also be used to determine compression or stretch in the axial direction. An alternative arrangement for measuring radial displacement is also described. The measuring apparatus may be used with a gear-type flexible coupling 151, Fig. 9, comprising a tube 152 with internal gear teeth 153 which mesh with spur gears 161, 162 formed on hubs 156, 157 secured to shafts 158, 159 which are to be coupled.