CN113530608A - Method and assembly for controlling the positioning of at least one rotor disc around a connecting rod of a partially assembled rotor - Google Patents

Abstract

Method for controlling the positioning of at least one rotor disk (2) around a connecting rod (3) of a partially assembled rotor (1) of a gas turbine, comprising: positioning the connecting rod (3) so that its longitudinal axis (A) extends substantially vertically; detecting the eccentricity of the rotor disc (2) with respect to the longitudinal axis (A) of the tie rod by means of an assembly (23), the assembly (23) comprising a main device (24) coupled to the free face (13a) of the rotor disc (2) and at least one first reference device (25,26) coupled to the tie rod (3); the assembly (23) further comprises at least three laser emitters (28) and at least three respective light sensitive sensors (30), the at least three laser emitters (28) being coupled to one between the host device (24) and the at least one first reference device (25,26), the at least three respective light sensitive sensors (30) being coupled to the other between the host device (24) and the at least one first reference device (25, 26); the light-sensitive sensors (30) are arranged so as to block the laser beams (B) emitted by the respective laser emitters (28).

Description

Method and assembly for controlling the positioning of at least one rotor disc around a connecting rod of a partially assembled rotor

Cross Reference to Related Applications

This patent application claims priority from european patent application No. 20169754.7 filed on 16/4/2020, the entire disclosure of which is incorporated herein by reference.

Technical Field

The invention relates to a method and an assembly for controlling the positioning of a connecting rod of a rotor disk around a partially assembled rotor of a gas turbine.

Background

The gas turbine rotor of a plant for generating electrical energy generally comprises a plurality of bladed rotor disks, which are centred on a shaft and coupled to one another. The coupling between adjacent rotor disks is obtained by means of a Hirth joint (Hirth joint).

Each rotor disc is therefore provided with two respective annular bodies provided with radial teeth, so-called Hirth tooth sets, one on each face. The rings are coupled to the rings of adjacent discs in order to build a so-called Hirth joint.

The rotor disc is provided with respective sets of blades and is bound in packs (packs) by a central link which engages a respective central hole of the rotor disc.

Each bladed disk defines a compressor rotor stage or a turbine rotor stage.

Gas turbine rotors must be produced and assembled with the highest precision in order to ensure near perfect balance. Considering the mass and the high rotation speed (the rotor usually rotates at 3000rpm or 3600rpm, depending on the standards of different countries), even the smallest defects can cause dangerous vibrations that exceed the allowable limits, forcing the plant to be stopped in order to carry out corrective interventions aimed at bringing the vibrations back to the allowable limits.

Assembling the rotor currently involves stacking the rotor disks around a central link arranged in a vertical position. The rotor disks center themselves automatically due to the fact that the contact between the disks occurs by the above-mentioned Hirth toothing.

Assembling a rotor typically requires stacking a large number of rotor disks (e.g., about twenty). Thus, a lack of uniformity in only one of these discs (for example, due to the fact that the discs have non-parallel faces) is sufficient to obtain a tilted stack at the end of the stacking step, i.e. a stack in which the centre of the last disc is not vertically aligned with the centre of the first disc.

Disc compliance is typically controlled when the rotor has been clamped. In particular, the rotor compliance of the disks is typically controlled on a rotor that is tilted horizontally and transported to a lathe, where the "run-out" eccentricity of each disk relative to the axis formed by the bearings can be measured. Possible corrective actions may require disassembly of the rotor.

Furthermore, the currently available tools and methods require infrastructure (cranes, etc.) and require a long time to evaluate and revise the stacks.

Control methods are known for controlling compliance of the discs prior to stacking. However, they do not ensure that all non-compliance of the disc is detected, since the operator needs to perform manual activities as well as personal evaluation. Therefore, the accuracy for inspection and correction and the time required cannot be considered satisfactory.

Another control method is disclosed in patent application No. EP3330484a1 filed by the present applicant. The method detects the inclination of the rotor disk relative to the horizontal plane and/or the eccentricity of the rotor disk relative to the connecting rod by means of the annular device. However, according to said solution, the reference for measuring the eccentricity of the single disc is the outer surface of the connecting rod.

Said solution cannot be adopted for already used rotors (for example for maintenance activities).

In a overhauled rotor, in fact, the central connecting rod cannot be used as an effective reference for axial symmetry, since it is generally deformed due to the long time and the thermomechanical stresses it is subjected to during operation.

In other words, the outer surface of the center link cannot be considered as an effective geometric reference for eccentricity measurements.

Disclosure of Invention

It is therefore an object of the present invention to provide a method for controlling the positioning of a rotor disk around a link of a gas turbine rotor which is accurate and reliable and avoids or minimizes the occurrence of balancing errors.

In this way, the evaluation and correction operations to be carried out on the already clamped rotor are minimized.

In accordance with these objects, the present invention relates to a method for controlling the positioning of a connecting rod of a rotor disk around a partially assembled rotor of a gas turbine; the connecting rod extends along a longitudinal axis;

the method comprises the following steps:

positioning the link so that the longitudinal axis extends substantially vertically;

detecting the eccentricity of the rotor disc with respect to the longitudinal axis of the tie rod by means of an assembly comprising a main device coupled to the free face of the rotor disc and at least one first reference device coupled to the tie rod; the assembly further includes at least three laser emitters coupled to one between the master device and the at least one first reference device, and at least three corresponding light sensitive sensors coupled to another between the master device and the at least one first reference device; the light-sensitive sensors are arranged so as to block the laser beams emitted by the respective laser emitters.

Another object is to provide an assembly for controlling the positioning of the tie-rods of a rotor disk around a partially assembled rotor of a gas turbine which is precise, reliable and capable of simplifying the operations to be carried out to check the compliance of the disk, minimizing manual activities and personal evaluations of the operator.

In accordance with these objects, the present invention relates to an assembly for controlling the positioning of at least one rotor disk around a connecting rod of a partially assembled rotor of a gas turbine; the connecting rod extends along a longitudinal axis;

the assembly includes:

a primary device coupled, in use, to a free face of the rotor disc; and

at least one first reference device, which is coupled, in use, to the link;

at least three laser transmitters coupled to one between the master device and the at least one first reference device; and

at least three respective light sensitive sensors coupled to the other between the master device and the at least one first reference device; the light-sensitive sensors are arranged so as to block the laser beams emitted by the respective laser emitters.

Drawings

The invention will now be described with reference to the accompanying drawings, which illustrate non-limiting embodiments of the invention, and in which:

FIG. 1 is a side view of a gas turbine rotor, with a section along a vertical axial plane;

FIG. 2 is a perspective view of a detail of the gas turbine rotor of FIG. 1;

figure 3 is a side view of the rotor of figure 1 partially assembled during a step of the method according to the invention;

fig. 3a is a perspective view of a first detail of an assembly for controlling the positioning of a rotor disk around a tie rod of the gas turbine rotor of fig. 1;

FIG. 4 is a bottom perspective view of a second detail of an assembly for controlling the positioning of a rotor disk around a connecting rod of the gas turbine rotor of FIG. 1;

FIG. 5 is a top perspective view of a second detail of an assembly for controlling the positioning of a rotor disk around a tie rod of the gas turbine rotor of FIG. 1;

fig. 6 is a perspective view of a third detail of the assembly for controlling the positioning of the rotor disk around the tie-rods of the gas turbine rotor of fig. 1 in the first operating configuration;

fig. 7 is a perspective view of a third detail of the assembly for controlling the positioning of the rotor disk around the tie-rods of the gas turbine rotor of fig. 1 in a second operating configuration;

FIG. 8 is a schematic view of a fourth detail of an assembly for controlling the positioning of a rotor disk around a connecting rod of the gas turbine rotor of FIG. 1;

FIG. 9 is a schematic view of a fifth detail of an assembly for controlling the positioning of a rotor disk around a tie-rod of the gas turbine rotor of FIG. 1, according to a variant of the invention;

FIG. 10 is a schematic block diagram of a sixth detail of an assembly for controlling the positioning of a rotor disk around a tie rod of the gas turbine rotor of FIG. 1;

fig. 11 is a schematic top view of a seventh detail of an assembly for controlling the positioning of a rotor disk around a connecting rod of the gas turbine rotor of fig. 1.

Detailed Description

In fig. 1, reference numeral 1 designates a gas turbine rotor of a plant for generating electrical energy, comprising a plurality of disks 2 aligned along an axis a and bound in packets by means of a central link 3. The central link 3 extends along a longitudinal axis a. The first set of discs 2 provided with respective first rotor blades 5 defines a compressor section 1a of the rotor 1, while the second set of discs 2 provided with respective second rotor blades 6 defines a turbine section 1b of the rotor 1. The compressor section 1a and the turbine section 1b are separated from each other by a spacer disk 7 without blades, the spacer disk 7 essentially acting as a spacer element and being substantially cylindrically shaped. In use, a combustion chamber (not shown) of the gas turbine is arranged around the spacer disk 7.

With reference to fig. 2, each rotor disk 2 is provided with a central through hole 8 and a peripheral edge 9, the peripheral edge 9 being provided with a plurality of seats 10, the plurality of seats 10 being suitably shaped so as to be engaged by a respective first rotor blade 5 or to a respective second rotor blade 6.

The central bore 8 will be engaged in use by the connecting rod 3 of the rotor 1.

Each rotor disc 2 is also provided with a radial tooth ring body 12, commonly called Hirth toothing, on each face 13a, 13b of the rotor disc 2 (only the face 13a of the rotor disc 2 is well visible in fig. 2).

Preferably, the radial tooth-ring bodies 12 are arranged along respective faces close to the peripheral edge 9 of the rotor disc 2.

The radial tooth-ring bodies 12 are positioned and shaped to couple to corresponding ring bodies of adjacent rotor disks 2, so as to build a so-called Hirth joint and ensure a stable coupling of the rotor disks 2.

Fig. 3 shows a partially assembled rotor 1, wherein the connecting rod 3 is arranged and supported in a vertical position. In other words, the connecting rod 3 is positioned so that the longitudinal axis a is substantially vertical.

Referring to fig. 1 and 3, the connecting rod 3 is provided with a first end 15 and a second end 16 axially opposite the first end 15.

In use, the first end 15 is coupled to a front axle 18 (fig. 1 and 3) and the second end 16 protrudes from a rear hollow axle 19 (visible only in fig. 1).

Preferably, the front axle 18 is housed in a stacking pit (stacking pit)21, which ensures correct and stable vertical positioning of the tie rod 3.

The configuration shown in fig. 3 may occur during assembly of the rotor 1 (when the rotor disks 2 are stacked on top of each other so that the radial tooth-ring bodies 12 of adjacent rotor disks 2 can be coupled to each other, thus building a Hirth joint) and during disassembly of the rotor 1 (when the rotor disks 2 are removed one by one).

The method according to the invention for controlling the positioning of at least one rotor disk 2 around a connecting rod 3 is applied to a partially assembled rotor 1 as shown in the configuration of fig. 3.

The method comprises detecting at least one parameter related to the position of at least one rotor disc 2 relative to one or more references.

In particular, the method comprises detecting the eccentricity of the rotor disc 2 with respect to the longitudinal axis a with an assembly 23, the assembly 23 being used to control the positioning of the rotor disc 2, comprising a main device 24 coupled to the free face 13a of the rotor disc 2, and at least one reference device 25,26 coupled to the tie rod 3.

Preferably, the detection of the eccentricity of the rotor disc 2 is obtained by at least three laser emitters 28 coupled to one of the primary device 24 or the at least one reference device 25 and at least three corresponding light-sensitive sensors 30 coupled to the other one of the primary device 24 and the at least one reference device 25.

The three laser emitters 28 are preferably arranged 120 ° from each other.

The light sensitive sensors 30 are also arranged at 120 ° from each other and are arranged to block the light beams of the respective laser emitters 28.

In the non-limiting example disclosed and illustrated herein, the detection of the eccentricity is carried out by means of a main device 24 coupled to the free surface 13a of the rotor disc 2 and two reference devices 25,26 coupled to the connecting rod 3.

Thus, in the non-limiting example disclosed and illustrated herein, a first measurement of eccentricity is made using the master device 24 and the reference device 25, while a second measurement of eccentricity is obtained using the master device 24 and the reference device 26.

Referring to fig. 3, a reference device 25 is coupled near the first end 15 of the link 3, while a reference device 26 is coupled near the second end 16 of the link 3. The main device 24 is coupled to the free surface 13a of the rotor disc 2 whose position needs to be controlled.

The reference device 25 is preferably fixed to the front axle 18. More preferably, the reference device 25 is fixed to a portion 31 (see also fig. 1) of the front shaft 18, this portion 31 being comprised between the first rotor disc 2 and an annular seat 32, the annular seat 32 being formed in the front shaft 18 and being configured to house, in use, a compressor ring bearing (not shown in the drawings).

In the non-limiting example disclosed and illustrated herein, the reference device 25 supports three laser emitters 28, each of which is configured to emit a laser beam B in a substantially vertical direction.

Referring to fig. 3a, each laser emitter 28 is coupled to a base structure 35, the base structure 35 being provided with positioning means 36. The positioning device 36 is configured to adjust the position of the laser transmitter 28. In use, the positioning device 36 is adjusted so that each laser emitter 28 of the reference device 25 emits a laser beam in a substantially vertical direction.

The positioning device 36 (see fig. 3A) has multiple degrees of freedom. In particular, the positioning device 36 comprises at least two adjustment elements 37a, 37b, which are rotatable about respective rotation axes O1, O2. The rotation axes O1, O2 are orthogonal with respect to each other.

The angular adjustment of each laser beam B emitted by laser emitter 28 (i.e., rotation about axes O1 and O2) may be controlled manually or electronically. According to a variant not shown, the positioning means can be replaced by positioning means similar to those described later and shown in fig. 8 and 9. Preferably, the reference device 25 is provided with an annular base 39 from which at least three spokes 40 (only two of which are visible in fig. 3) protrude. Each spoke 40 has a free end 41 to which a respective laser emitter 28 is coupled.

The free ends 41 of the spokes 40 are arranged 120 deg. from each other. Preferably, the spokes 40 are arranged radially around the annular base 39.

The length of the spokes 40 is sufficiently greater than the maximum height of the compressor blades 5 and turbine blades 6 so that the free ends 41 of the spokes 40 protrude beyond the compressor blades 5 and turbine blades 6 when the reference device 25 is fixed to the rotor 1.

Preferably, the annular base 30 can be opened and closed to allow it to be positioned and secured around a portion 31 of the front axle 18.

With reference to the non-limiting example shown in fig. 3 and 4 and 5, the reference device 26 is coupled to the second end 16 of the connecting rod 3 and can be retracted. In particular, the reference device 26 comprises a cage structure 43 and at least three retractable arms 44, the cage structure 43 being fixed to the connecting rod 3, the at least three retractable arms 44 being housed in the cage structure 43 and being arranged at 120 ° from each other. Each arm 44 is movable from an operating position, in which the arm 44 extends outside the cage structure 43 (configuration shown in figures 3 and 5), and a rest position, in which the arm 44 is retracted and completely housed in the cage structure 43 (configuration shown in figure 4). Each arm 44 is an articulated arm having one end 45 coupled to a movable sleeve 46 and one free end 47 coupled to the respective photosensitive sensor 30.

Each arm 44 is configured to have a length in an operative position such that each photosensor 30 is capable of detecting a laser beam B' emitted by a respective laser emitter 28, the laser emitters 28 being supported by the host device 24 as may be described in detail hereinafter. Obviously, the arms 44 are arranged at the same angular position of the laser beam B' emitted by the laser emitter 28. Preferably, the photosensitive sensors 30 coupled to the arms 44 are arranged at the same radial distance from the longitudinal axis a. The movable sleeve 46 is arranged around the shaft 49. When the sleeve 46 is in the upper position (the configuration shown in fig. 4), the arm 44 is in the rest position, and when the sleeve 46 is in the lower position (the configuration shown in fig. 5), the arm 44 is in the operating position.

The sleeve 46 is preferably moved by a remotely controlled tool (not shown).

Referring to fig. 3, the main device 24 is coupled to the free face 13a of the rotor disc 2. By free face we mean here and hereafter the face of a rotor disc 2 which is not coupled to another face of an adjacent rotor disc 2.

As already indicated before, the method according to the invention can be applied both during assembly and disassembly of the rotor 1.

During assembly, the detection of the position of the disk 2 takes place before another rotor disk 2 is stacked on the rotor disk 2 to be controlled, whereas during disassembly, the detection of the position of the rotor disk 2 takes place before the rotor disk 2 to be controlled is removed.

As a result, the method according to the invention requires that the main device 24 is coupled to one rotor disc 2 at a time.

However, this does not mean that positioning control must be implemented for each disk of the rotor 1. The positioning of the group of coupled rotor disks 2 can also be controlled by means of a detection of the positioning of the rotor disks 2 with free faces belonging to the group.

Referring to the non-limiting example illustrated in fig. 6 and 7, the primary device 24 includes a rack 53, a centering system 54, and at least three laser emitters 28 and at least three light-sensitive sensors 30 coupled to the rack 53, the centering system 54 being configured to center the rack 53 on the rotor disk 2 being controlled.

The support 53 comprises a ring-shaped frame 58 and at least three spokes 60, the spokes 60 having projections extending radially from the ring-shaped frame 58 and being arranged at 120 ° from each other. Each spoke 60 supports a respective light sensitive sensor 30. Preferably, the photosensitive sensor 30 is coupled to the side of the spoke 60 facing the free face 13a of the rotor disc 2. In other words, the photosensitive sensor 30 is coupled to the side of the spoke 60 that in use faces the reference device 25. Preferably, the photosensitive sensors 30 are coupled to the free ends 61 of the respective spokes 60.

The length of the spokes 60 is sufficiently greater than the maximum height of the compressor blades 5 and turbine blades 6 so that the free ends 61 of the spokes 60 protrude beyond the compressor blades 5 and turbine blades 6 when the main device 24 is coupled to the rotor disk 2. The sensors 30 are placed on the spokes 60 at the same angular position and at the same radial distance from the longitudinal axis a of the laser beam B emitted by the laser emitter 28 on the reference device 25. For example, the sensors 30 are placed on the spokes 60 along a circle having a diameter of about 3.5 m.

Preferably, the annular frame 58 has a coupling face 62 (visible in fig. 6) and an operating face 63 (visible in fig. 7), the coupling face 62 facing, in use, the rotor disk 2 to be controlled, the operating face 63 being opposite to the coupling face 62.

The coupling surface 62 is coupled to the centering system 54, while the operating surface 63 supports at least three laser emitters 28. The laser emitters 28 are configured to emit respective laser beams B' and are arranged at 120 ° at the same radial distance from the centre of the annular frame 58 (coinciding, in use, with the longitudinal axis a).

For example, the laser transmitter 28 is placed on the operation face 63 along a circle having a diameter of about 0.6 m. The spokes 60 are preferably arranged on the operating face 63.

Preferably, the stand 53 comprises a further annular element 65, which annular element 65 is configured to protect the electronics (battery, inclination sensor, control electronics, laser emitter 28, etc.) during movement of the main device 24. The further ring element 65 is also configured so as to provide a hooking point for lifting the support 53, for example by means of a crown block (not shown).

In the non-limiting example described and illustrated herein, the support 53 has dimensions compatible with the dimensions of the tie-rods 3 and of the rotor disks 2 that make up the rotor 1.

With reference to fig. 6, the centering system 54 comprises at least two portions 67 of a Hirth toothing ring, which can be coupled to respective portions of a radial toothing (Hirth) ring 12 arranged on the free face 13a of one of the rotor disks 2 making up the rotor 1.

In order to be coupled to the radial toothing bodies 12 of any of the rotor discs 2 of the rotor 1, the portion 67 of the Hirth toothing body must be shaped so as to have a minimum radius equal to the inner diameter of the radial toothing body 12 of the smallest rotor disc 2 and a maximum radius equal to the outer diameter of the radial toothing body 12 of the largest rotor disc 2.

Furthermore, the portion 67 of the Hirth toothing ring must have teeth oriented like the teeth of the radial toothing ring 12, i.e. towards the centre of the rotor disc 2, retaining all its other parameters (inclination of the walls of the teeth, number of teeth, etc.) in order to ensure a correct and stable coupling between this portion 67 and the radial toothing ring 12 of the rotor disc 2.

If there are two portions 67 of the Hirth toothing ring, they are diametrically opposite.

In the non-limiting example described and illustrated herein, the centering system 54 comprises three portions 67, which are separated and arranged on the same plane, preferably about 120 ° from each other.

The three portions 67 are substantially identical.

Each laser emitter 28 coupled to the operating face 63 of the annular frame 58 of the carriage 53 is preferably coupled to an orientation device 70 (fig. 8), the orientation device 70 being configured to adjust the position of the laser emitter 28 so that the laser beam B' emitted by the laser emitter 28 is substantially vertical.

Referring to the non-limiting example illustrated in fig. 8, the orientation device 70 includes a housing 71 containing a fluid 72. The fluid is, for example, mercury in liquid form. The housing is coupled to the operating face 63 of the ring frame 58.

The laser transmitter 28 is arranged in a housing 71 floating on a fluid 72. Since the free surface 73 of the fluid 72 is always substantially horizontal independently of the inclination of the surface 63 of the support housing 71, the laser transmitter 28 can always emit laser light B' substantially vertically.

The orientation means 70 of fig. 8 works correctly if the laser emitter 28 has to emit a laser beam upwards, i.e. towards the end 16 of the connecting rod 3.

According to the variant shown in fig. 9, the laser emitter 28 is coupled to the surface 62 of the annular frame 58 of the support 53 so as to emit a laser beam downwards, i.e. towards the end 15 of the connecting rod 3. In this case, each laser emitter 28 is coupled to an axially symmetric body 75, the axially symmetric body 75 being hinged to the surface 62 of the annular frame 58 of the support 53. The body 75, due to its structure and weight, will be oriented so that the laser beam B' emitted by the laser emitter 28 is always substantially vertical, independently of the inclination of the surface 62 supporting the body.

According to a variant not illustrated, the laser emitter may be coupled to other types of devices capable of correctly adjusting the orientation of the laser beam. Such as a mechanized device or other known laser leveling systems.

Referring to fig. 7, preferably, the primary device 24 also includes a dual-axis inclinometer 78, the dual-axis inclinometer 78 being coupled to the rack 53 and configured to measure the inclination of the rack 53 with respect to two orthogonal axes.

Since the support 53 is integral with the rotor disc 2 to which it is coupled, the two-axis inclinometer 78 measures the inclination of the rotor disc 2 to which the main device 24 is coupled.

Preferably, a dual-axis inclinometer 78 is coupled to surface 63 of annular frame 58 of stand 53.

The main device 24 also comprises at least two distance detectors 80 coupled to the support 53 and arranged at respective points (indicated with a dashed line in fig. 7) belonging to the same circle. The distance detector 80 is oriented towards the center of the circle. In this way, in use, the distance probe 80 detects the distance in the radial direction relative to the connecting rod 3.

In the non-limiting example described and illustrated herein, the primary device 24 includes three distance detectors 80, preferably arranged along a circle at 0-90-225.

Preferably, the distance detector 80 is coupled to the operative surface 63 of the annular frame 58 and is arranged at a radial distance from the center of the annular frame 58 that is shorter than the radial distance of the laser emitter 28. In other words, the distance detector 80 is arranged internally with respect to the laser emitter 28.

The distance detector 80 is preferably a contactless detector, such as a laser triangulation system; the distance probe 80 allows measuring also the eccentricity of the outer surface of the connecting rod 3 (used and possibly deformed) with respect to a virtual cylinder coaxial with the longitudinal axis a of the rotor 1.

Referring to FIG. 3, in use, the laser emitter 28 on the reference device 25 emits a laser beam B to the photosensor 30 of the host device 24, while the laser emitter 28 of the host device 24 emits a laser beam B' to the photosensor 30 of the reference device 26.

According to a variant not illustrated, the reference device 25 comprises a light-sensitive sensor, while the main device 24 comprises a laser emitter emitting a laser beam towards the light-sensitive sensor of the reference device.

According to a variant not illustrated, the reference device 26 comprises a laser emitter emitting a laser beam towards a respective photosensitive sensor 30 of the host device.

Each photosensitive sensor 30 is configured to detect the laser beam impinging thereon and to provide a radial position of the impingement point relative to the longitudinal axis a.

Referring to fig. 10, the photosensor 30 on the host device 24 can provide respective radial distances R1, R2, R3 relative to the longitudinal axis a by detecting the laser beam B emitted by the laser emitter 28 on the reference device 25 (the lower one), while the photosensor 30 on the reference device 26 (the upper one) can provide respective radial distances R1', R2', R3 'relative to the longitudinal axis a by detecting the laser beam B' emitted by the laser emitter 28 on the host device 24.

The laser transmitter 28 is preferably a low power laser transmitter to ensure operator safety. To avoid detection of external light noise by the photosensor 30, the laser transmitter 28 emits a laser beam with frequency modulation. In this way, the photosensitive sensor 30 may be provided with a suitable filter.

The value is sent to the control means 85. The control device 85 includes a first eccentricity calculator 86 and a second eccentricity calculator 87.

Referring to FIG. 11, the first eccentricity calculator 86 is configured to detail the radial distances R1, R2, R3, define a circle passing through the points detected by the sensor 30, and calculate an eccentricity value Vecc of the circle with respect to the center of symmetry "O" of the host device 24.

In case of pronounced (but atypical) tilting of the reference device 25, the radial distances R1, R2, R3 have to be fitted using ellipses (instead of circles); the ellipse may be calculated by considering the data detected by the inclinometer 78 (which is an input to block 86).

The second eccentricity calculator 87 is similarly configured to detail the radial distances R1', R2', R3 ', define a circle (or ellipse taking into account the data of the inclinometer 78) passing through the points detected by the sensor 30, and calculate an eccentricity value Vecc' of the circle (or ellipse) with respect to the center of symmetry "O" of the main device 24.

The eccentricity values Vecc, Vecc' are sent to an evaluation module 90, in which data about the eccentricity of each disk 2 of the rotor 1 are remembered and an evaluation of the positioning of each rotor disk 2 can be detailed.

According to a variant not illustrated, the control device 85 comprises only one eccentricity calculator.

According to an embodiment not shown herein, the control means 85 comprise a further module configured to give an indication of the possible corrective action to be carried out as a function of the detected eccentricity value.

Preferably, the data detected by the photosensitive sensor 30 is sent to the control device 85 by means of wi-fi communication.

Preferably, the laser transmitter 28 is also remotely controlled via wi-fi communication.

Preferably, the control device 85 is not coupled to the stand 53 and is integrated into an external processor (for example a tablet computer) available to the operator following the assembly/disassembly of the rotor 1. In this way, the tablet computer can give the operator information about the correct positioning of the disks on the stack with respect to all errors and, in any case, store this information.

In use, in order to control the positioning of the rotor disc 2 around the tie rod 3, an operator must position the rotor 1 vertically by means of a crane (not shown). Preferably, the front shaft 18 of the rotor 1 is housed in a stacking pit 21 to ensure correct and stable vertical positioning of the connecting rod 3.

The reference devices 25 and 26 are then coupled to the rotor 1 near the ends 15 and 16 of the connecting rod 3, respectively. The reference devices 25 and 26 are moved by a crane.

After the reference devices 25 and 26 have been correctly positioned, the main device 24 is arranged on the free face 13a of the rotor disc 2.

The positioning of the primary device 24 on the rotor disk 2 is adjusted to ensure that the laser emitters 28 are substantially vertically aligned with the respective photosensitive sensors 30.

The main device 24 is also moved by using a crane.

After positioning the master device 24, the laser transmitter 28 is activated and the eccentricity of the controlled disk is evaluated.

Preferably, the inclinometer 78 and the distance detector 80 are also activated in order to improve the control of the positioning of the rotor disk 2.

Advantageously, the assembly 23 and the method for controlling the positioning of rotor disks according to the invention allow to improve and optimize the assembly of the rotor 1, avoiding the assembly of an unbalanced rotor, and in particular avoiding the costs resulting from implementing one or more corrective interventions on an already assembled rotor.

The assembly 23 and the method for controlling the positioning of rotor disks according to the invention can also be applied to already assembled rotors assembled with prior art assembly techniques.

In the case of an assembled rotor, the assembly 23 and the method according to the invention can be applied during disassembly of the rotor 1 disk by disk.

During disassembly, the rotor disks 2 are removed one at a time, and the assembly is used to detect the position of each rotor disk 2 until that rotor disk (or rotor disks) is found to be the cause of the imbalance of the rotor 1.

The application assembly 23 is advantageous compared to the currently known solutions during the disassembly of the rotor 1, since it gives an objective indication of the positioning of each rotor disc 2, without introducing personal evaluation elements of the operator.

Furthermore, you do not have to completely disassemble the rotor 1, for example in the following cases:

rotor disks 2 if the cause of the imbalance is confirmed before all the rotor disks are removed;

if at least two disks or two groups of disks (possibly even non-adjacent) are identified, which have a tilt that can be compensated, for example, by a correct corrective action (i.e. a rotation relative to the axis a of one of the disks or of the group of disks) that brings the stack of rotor disks back into alignment, the stack of rotor disks as a whole being within a given error.

Basically, the confirmation of the unbalance does not always lead to a replacement of the rotor disk 2. As a matter of fact, the unbalance can be corrected simply by means of a correct rotation of the rotor disk. In this case, the device 16 has an important role in establishing whether the corrective action is effective and sufficient for compensating the imbalance.

Finally, it is clear that the components and methods described herein can be subject to variations and modifications without thereby departing from the scope of protection of the appended claims.

Claims (15)

1. Method for controlling the positioning of at least one rotor disk (2) around a connecting rod (3) of a partially assembled rotor (1) of a gas turbine; the connecting rod (3) extends along a longitudinal axis (A);

the method comprises the following steps:

positioning the connecting rod (3) so that the longitudinal axis (A) extends substantially vertically;

-detecting the eccentricity of the rotor disc (2) with respect to the longitudinal axis (a) of the tie rod by means of an assembly (23), the assembly (23) comprising a main device (24) coupled to the free face (13a) of the rotor disc (2) and at least one first reference device (25,26) coupled to the tie rod (3); the assembly (23) further comprises at least three laser emitters (28) coupled to one between the host device (24) and the at least one first reference device (25,26) and at least three respective light sensitive sensors (30), the at least three respective light sensitive sensors (30) being coupled to the other between the host device (24) and the at least one first reference device (25, 26); the photosensitive sensors (30) are arranged so as to block the laser beams (B) emitted by the respective laser emitters (28).

2. Method according to claim 1, wherein the step of detecting the eccentricity comprises measuring the distance (R1, R2, R3; R1', R2 ', R3 ') between the longitudinal axis (A) and each laser beam (B) emitted by the laser emitter (28) by means of the at least three photosensitive detectors (30) and signalling the occurrence of eccentricity (Vecc; Vecc ') on the basis of the detected radial distance (R1, R2, R2; R1', R2 ', R3 ').

3. A method according to claim 1 or 2, wherein the connecting rod (3) has a first end (15) and a second end (16), the first end (15) being arranged close to the floor when the connecting rod (3) is in the vertical position, the second end (16) being axially opposite to the first end (15); the at least one first reference device (25,26) is coupled in proximity to the first end (15) and/or the second end (16).

4. Method according to any one of the preceding claims, wherein said at least one reference device (25; 26) comprises at least three support elements (40; 44), each of said at least three support elements (40; 44) supporting one between said laser emitter (28) and said photosensitive sensor (30).

5. Method according to claim 3 or 4, wherein said assembly (23) comprises a second reference device (26); a first reference device (25) is coupled in proximity of the first end (15), while the second reference device is coupled to the second end (16).

6. A method according to claim 5, wherein the step of detecting the eccentricity of the rotor disc (2) comprises:

measuring a first radial distance (R1, R2, R2) between the longitudinal axis (a) and each laser beam (B) emitted by a first laser emitter (28) arranged on the first reference device (25) by means of at least three first photosensitive detectors (30) arranged on the main device (24);

measuring a second radial distance (R1 ', R2', R3 ') between the longitudinal axis (a) and each laser beam (B') emitted by a second laser emitter (28) arranged on the main device (24) by means of at least three second photosensitive detectors (30) arranged on the second reference device (26);

signaling a second eccentricity occurrence (Vecc ') based on the second radial distance (R1', R2 ', R3').

7. The method according to any of the preceding claims, wherein at least one laser emitter (28) is coupled to an orientation device (70, 75), the orientation device (70, 75) being configured to adjust the position of the laser emitter (28) such that the laser beam (B) emitted by the laser emitter (28) is substantially vertical.

8. The method of any of the preceding claims, further comprising the step of measuring tilt with an inclinometer (78) coupled to the primary device (24).

9. An assembly for controlling the positioning of at least one rotor disk (2) around a connecting rod (3) of a partially assembled rotor (1) of a gas turbine; the connecting rod (3) extends along a longitudinal axis (A);

the assembly comprises:

a main device (24) coupled, in use, to a free face (13a) of the rotor disc (2); and

at least one first reference device (25,26) coupled, in use, to said connecting rod (3);

at least three laser transmitters (28) coupled to one between the master device (24) and the at least one first reference device (25, 26); and

at least three respective light sensitive sensors (30) coupled to the other between the main device (24) and the at least one first reference device (25, 26); the photosensitive sensors (30) are arranged so as to block the laser beams (B) emitted by the respective laser emitters (28).

10. Assembly according to claim 9, wherein the at least three light-sensitive sensors (30) are configured to measure the radial distance (R1, R2, R3; R1', R2 ', R3 ') between the longitudinal axis (A) and each laser beam (B) emitted by the laser emitter (28).

11. Assembly according to claim 10, comprising a control device (85) configured to signal the occurrence of eccentricity (Vecc; Vecc ') based on the detected radial distance (R1, R2, R2; R1', R2 ', R3').

12. Assembly according to any one of claims 9 to 11, wherein said at least one reference device (25; 26) comprises at least three support elements (40; 44), each of said at least three support elements (40; 44) supporting one between said laser emitter (28) and said photosensitive sensor (30).

13. An assembly according to any one of claims 9 to 12, wherein said at least one first reference device (25,26) is coupled, in use, in proximity to the first end (15) and/or the second end (16) of the connecting rod (3).

14. Assembly according to claim 13, comprising a second reference device (26); the first reference device (25) is coupled in the vicinity of the first end (15), while the second reference device is coupled to the second end (16).

15. The assembly according to any one of claims 9 to 14, wherein at least one laser emitter (28) is coupled to an orientation device (70; 75), the orientation device (70; 75) being configured to adjust the position of the laser emitter (28) such that the laser beam (B) emitted by the laser emitter (28) is substantially vertical.

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