Device for checking end runout of stator parts of thrust bearing assembly relative to rotor rotation axis

Abstract

FIELD: mechanical engineering.SUBSTANCE: invention relates to precision control of the geometry of thrust bearing units of turbomachines. The device comprises a rod (8) installed coaxially with the rotor (1) adapted for their joint rotation, and measuring heads-indicators (10, 11) secured to the rod (8) by means of adjustable rods (9) and holders (16). The rod (8) is rigidly secured directly to the end of the rotor (1). The device is equipped with two measuring heads-indicators (10, 11), which are installed diametrically opposite to each other at the same distance from the axis of rotation of the rotor (1). The measuring tips of the indicators are positioned perpendicular to the controlled surface of the stator parts adapted simultaneously recording readings every 45° of rotation of the rotor (1) followed by calculation of the absolute value of the axial runout Tb using the formula Tb = (I1 – I2) / 2⋅D / d.EFFECT: increasing the accuracy of measuring the end runout of surfaces for installing a thrust bearing unit relative to the axis of rotation of a levitating rotor.1 cl, 4 dwg, 1 tbl

Description

[0001] The invention relates to the field of monitoring body parts of mechanical engineering and can find application in monitoring the position of end surfaces of various assembly units that have tolerances for the relative position of such surfaces relative to the axis of the surface of rotation.

[0002] A method is known for measuring the end runout of a thrust disk, which uses magnetic stands with measuring heads mounted on a fixed stator part [UO 38.12.007-87 "Centrifugal compressors. General specifications for repairs." VNIKTIneftkhimoborudovanie, 1987, p. 16, Fig. 3.5, Table 3.4].

[0003] The disadvantage of the known method as applied to body parts is the impossibility of checking the axial runout of the installation locations of the thrust liners relative to the axis, and the specified permissible requirements for the runout of the plane of the thrust disk ≤0.02 mm should equally apply to the installation planes of the axial magnets.

[0004] Measuring instruments for monitoring the runout of end surfaces relative to the axis of the holes are known [M.O. Jacobson. Machine Tool Manufacturing Technology. Moscow: Mashinostroenie, 1966, 475 p. (Fig. 112g.)].

[0005] The disadvantage of measuring the perpendicularity of the end face relative to the axis of the part is that the device does not allow monitoring the runout of the end face of the holes of the body parts.

[0006] A device is known for monitoring the end runout of housing parts relative to the axis of the hole [KZ 33 766, published 12.07.2019], containing a clock-type indicator, a housing on which a measuring lever is mounted, supports, the value of the end runout relative to the axis of the hole at a given diameter is determined by rotating the device by 180° until the extreme values ​​​​of the runout of the axis of the hole relative to the end surface of the controlled part are found and according to the formula

[0007] a t = (I 1-I 2) L / H

[0008] where a t is the value of the end runout at a given diameter;

[0009] I1, I2 - readings of the clock indicator in extreme, respectively, largest and smallest positions;

[0010] L - distance from the lever axis to the dial indicator axis;

[0011] H - the distance from the axis of the lever to the axis of the point of contact of the lever with the surface of the hole.

[0012] It is impossible to use the known device due to the choice of the measurement surface - in the prototype, the radial surface is controlled relative to the axis of the hole, while in the proposed device, the end surface is controlled relative to the axis of rotation of the rotor. Also, the known device does not take into account the movement in the axis, since when measuring relative to the rotor, it is necessary to take into account the axial displacement of the rotor. In the proposed device, the measurement is carried out using two indicators and the difference in the values ​​​​of the strike is recorded in order to exclude the influence of axial movements during rotation of the rotor.

[0013] The closest to the invention in technical essence and the achieved result, a device for measuring the deviation from perpendicularity of the end of a submersible electric motor relative to the axis of the shaft is the Device for measuring the deviation from perpendicularity of the end of the housing of a submersible electric motor relative to the axis of the shaft [SU 1703954 A1. published 01 / 07 / 1992.], containing a cylindrical housing with external cylindrical guides, an indicator, a floating element in the form of a sleeve with a stop installed in the guides of the housing and spring-loaded along the axis and carrying the indicator and a stop located diametrically opposite the indicator.

[0014] The known device cannot be used because the rotation is imparted to the housing, not the shaft (rotor). The shaft's rotation is limited by a rigid rod stop connected to the housing. Furthermore, the floating element has a gap, so the housing fit on the shaft must be transient. The measurement is taken relative to the geometric axis of the shaft, not the axis of rotation.

[0015] The objective of the invention is to ensure control of the end runout of the housing parts of the thrust unit relative to the axis of rotation.

[0016] The technical result of the declared technical solution is to increase the accuracy of measuring the end runout of surfaces for installing the thrust bearing unit relative to the rotor rotation axis.

[0017] The technical result is achieved in that the device for monitoring the end runout of housing parts relative to the axis of rotation of the rotor is designed with the possibility of mounting directly on the rotor of a turbomachine and contains two indicators located diametrically to eliminate the influence of axial movement, while the value of the end runout at a given diameter is determined by rotating the rotor together with the device by 360° with the simultaneous recording of the indicator readings and the phase of the rotation angle through 45°, and the absolute values ​​​​of the end surface runout at each point relative to the levitation axis are determined by the formula

[0018] Tb = (I1-I2) / 2⋅D / d

[0019] where Tb is the end runout at a given diameter;

[0020] I1, I2 - readings of indicators located diametrically;

[0021] D - specified diameter;

[0022] d - diameter of the indicator installation circle

[0023] The claimed device is explained by drawings, in which Fig. 1 shows a diagram of the action of the forces of the axial (MA) magnet of the axial magnetic bearing (AMB); Fig. 2 is a schematic diagram of the installation of the claimed device; Fig. 3 is a diagram of the end runout measurements; Fig. 4 is a general view of the device.

[0024] The following device designations are shown on the graphic materials:

[0025] 1 - rotor;

[0026] 2 - machine body;

[0027] 3 - magnetic bearing housing (MPA);

[0028] 4 - spacer ring;

[0029] 5 - internal axial magnet;

[0030] 6 - radial magnetic bearing (RMB);

[0031] 7 - safety bearings;

[0032] 8 - barbell;

[0033] 9 - rod;

[0034] 10, 11 - measuring head (indicator);

[0035] 12 - clamp;

[0036] 13 - clamping screw;

[0037] 14 - holder clamp screw;

[0038] 15 - measuring head clamp screw;

[0039] 16 - holder.

[0040] Fig. 1 shows a diagram of the action of forces arising from the tilt of the thrust disk (SD) and the axial magnet (MA), where in the diagram MA is the axial magnet 17; SD is the thrust disk 18; F is the direction of action of forces 19; M is the direction of the resulting moment from tilt 20.

[0041] Fig. 2 shows a diagram of the installation of the proposed device on the rotor of a turbomachine, where in the diagram 21, 22, 23, 24 is the testing surface, the rotor 1 in levitation; the machine body 2 is the part being tested; the MPA body 3 is the part being tested; the spacer ring 4 is the part being tested; the internal axial magnet 5 is the part being tested; 6 is the radial magnetic bearing (RMB) 6; safety bearings 7; the rod 8 for fastening the holders of the indicators 10, 11 when testing the end runout of the housing parts relative to the axis of rotation; the rod 9 is the holder of the indicators 10, 11.

[0042] Fig. 3 shows a diagram of the sequence of recording the obtained data on the rotor 1 in levitation, where in the diagram: internal axial magnet 5 is the controlled part; indicator 10 (I1), indicator 11 (I2); horizontal plane 25 (X), vertical plane 26 (Y); planes for measuring the rotor position in the radial direction 27 (V) and 28 (W); measurement points 29 (T1), 30 (T2), 31 (T3), 32 (T4), 33 (T5), 34 (T6), 35 (T7), 36 (T8), specified diameter 37 (D); diameter of the circle 38 (d) of the installation of indicators 10, 11; arrow 39 is the direction of phase counting.

[0043] Fig. 4 shows the design of the device mounted on the machine body.

[0044] The proposed device is used to measure the end runout on four parts that are an integral part of a thrust bearing assembly relative to radial bearings, since increased runout of each part leads to a distortion of the axial magnet as shown in Fig. 1.

[0045] The device operates as follows.

[0046] The device is assembled in the following sequence (Fig. 4): rod 8 having a threaded section is screwed into the end of rotor 1 having a mating thread located deeper than the centering hole for making the shaft, providing a non-moving threaded connection of rod 8 with rotor 1. Next, clamp 12 is sequentially mounted through a larger hole on rod 8, rod 9 is inserted into the small hole of clamp 12 and preliminarily clamped with screw 13, holder 16 is connected to rod 9 and clamped with screw 14, indicator sleeve 10 is inserted into the split hole of holder 16 and clamped with screw 15, indicator leg 10 is set perpendicular to the measured surface with the required tension and screws are tightened to prevent spontaneous movement of the component parts. The rest of the device is assembled in a similar manner, and indicators 10 and 11 are positioned diametrically opposite at the same distance from the axis of rotor 1.The device is driven in the following way: the radial magnetic bearings 6 are put into operation, the rotor 1, at the same time, floats in the air gap of the magnetic bearings 6 without touching the safety bearings 7 in the radial direction and is centered in the air gap of the safety bearings, the readings are measured simultaneously by two indicators 10 and 11 every 45 degrees of rotation of the device together with the rotor 1 clockwise 39 (Fig. 3), at the same time, the rotor 1 in levitation has free axial movement within the gap of the safety bearing ± 0.30 mm.

[0047] The readings are recorded according to the diagram shown in Fig. 3.

[0048] An example of recording the results is shown in the table:

[0049] Table.

[0050] Example of recording the results of checking the runout of body parts

[0051] Reference points for readings (T1-T8) Indicator Readings (10, 11) Algebraic difference Algebraic difference Plane runout x0.01 mm Phase in degrees from I1 I1 (indicator 10) I2 (indicator 11) I1 (indicator 10) I2 (indicator 10) 1 5 0 0 0 8 4 0 2 6 +2 -2 +4 12 6 45 3 7 +4 -4 +8 16 8 90 4 8 +2 -2 +4 12 6 135 5 1 0 0 0 8 4 180 6 2 -2 +2 -4 4 2 225 7 3 -4 +4 -8 0 0 270 8 4 -2 +2 -4 4 2 315 1 5 -1 -1 0 - - -

[0052] Result: end runout of surface = 8⋅D / d⋅0.01 mm phase 90°.

[0053] The value of the axial runout depends on the readings of the indicators and the diameters D, d. The value of the axial runout Tb on the diameter D is calculated using the formula

[0054] Tb=(I1-I2) / 2⋅D / d

[0055] The obtained results of the magnitude and phase of the end runout of the housing 2 of the MPR unit, surface 24, housing 3 of the MPA unit, surface 23, spacer ring 4, surface 22, axial magnet 5 make it possible to ensure the end runout of the working part of the axial magnet 5, surface 21, up to 0.01 mm relative to the rotor rotation axis by turning any of the four (2, 3, 4, 5) end surfaces (21, 22, 23, 24) by a runout value equal to the runout of the working part of the axial magnet 5.

[0056] The permissible runout of housing 2, housing 3, spacer ring 4 for mounting the internal axial magnet, the working surface of magnet 5, and the thrust disk must not exceed 0.02 mm. Achieving a runout of 0.01 mm for the working surfaces of the thrust disk is only possible through combined machining with the rotor. Ensuring a runout of 0.01 mm for the end surface of the stator assembly for mounting the thrust part is only possible through simultaneous machining of the radial bearing seats and the end surface for the thrust part. This is quite expensive, and the result is not guaranteed, since the axis of rotation does not coincide with either the axis of the bores for the radial magnets or the centers of the backup bearings.

[0057] The manufacturing accuracy of the end surfaces of the housing components of serial turbomachines typically does not exceed 0.02 mm. Therefore, assembling several parts—the housing, bearing housing, spacer ring, and the thrust bearing itself—requires reworking to compensate for the manufacturing error on a partially assembled unit. After obtaining runout data for these parts, end surface 22 of spacer ring 4 is typically reworked, thereby achieving acceptable assembly accuracy both during production and during repairs.

[0058] The most accurate measurement of the end runout of the surfaces for installing the thrust bearing unit relative to the rotor rotation axis is achieved by using the rotor rotation axis itself in levitation as the base, rather than the manufacturing surfaces having their own tolerances, and by installing two measuring heads that compensate for possible rotor movements in the axial direction without the use of cents (stops), which in systems with magnetic bearings lead to rotor excitation and do not allow the end runout of the surfaces for installing the thrust bearing unit to be assessed.

[0059] The advantages include the ability to: measure the axial runout of housing parts relative to the rotor axis of rotation on a partially assembled turbomachine; move indicators to undamaged surfaces; perform the operation in any position of the controlled stator parts without disassembly, without the use of false shafts and control and measuring machines; compensate for axial movements of the rotor during rotation; and apply the device to turbomachines with plain bearings.

[0060] Determining the phase of maximum runout with the positioning of parts relative to each other to determine the magnitude and locations of deviations.

[0061] Achievement: high requirements for the end runout of the thrust part of turbomachines; standard level of rotor vibration displacement.

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