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

Abstract

Method for controlling the positioning of at least one rotor disc (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 connecting rod by means of an assembly (23) comprising a main device (24) coupled to a free face (13a) of the rotor disc (2) and at least one first reference device (25, 26) coupled to the connecting rod (3); the assembly (23) further comprises at least three laser emitters (28) coupled to one between the main device (24) and the at least one first reference device (25, 26) and at least three corresponding photosensitive 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 intercept a laser beam (B) emitted by the corresponding laser emitter (28).

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to European patent application no. 20169754.7, filed on April 16, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a method and components for controlling the positioning of the connecting rods of a rotor disk assembled around a portion of a gas turbine. Background Technology

[0004] Gas turbine rotors used to generate electricity typically consist of multiple bladed rotor disks that are centered on a shaft and connected to each other. The connection between adjacent rotor disks is achieved using a Hirth joint.

[0005] Therefore, each rotor disk has two corresponding annular bodies with radial teeth, known as Hirth teeth, one on each face. The annular bodies are connected to the annular bodies of adjacent disks to form what is known as Hirth joints.

[0006] The rotor disk is equipped with corresponding blade groups and is bound into a pack by a central connecting rod, which engages with the corresponding central hole of the rotor disk.

[0007] Each bladed disk is defined as either a compressor rotor stage or a turbine rotor stage.

[0008] Gas turbine rotors must be manufactured and assembled with the highest precision to ensure near-perfect balance. Given the quality and high speeds (rotors typically rotate at 3000 rpm or 3600 rpm, depending on national standards), even the smallest defect can cause dangerous vibrations beyond permissible limits, forcing the equipment to be stopped for corrective interventions designed to bring the vibrations back to permissible limits.

[0009] Assembling the rotor currently involves stacking rotor disks around a central connecting rod arranged in a vertical position. Due to the fact that contact between the disks occurs via the aforementioned Hirth gear, the rotor disks self-center.

[0010] Assembling rotors typically requires stacking a large number of rotor disks (e.g., about twenty). Therefore, even a lack of uniformity in just one of these disks (e.g., due to the fact that the disks have non-parallel faces) is enough to result in a skewed stack at the end of the stacking step, i.e., a stack in which the center of the last disk is not vertically aligned with the center of the first disk.

[0011] The compliance of the discs is generally controlled when the rotor has been clamped. In particular, the rotor compliance of the discs is generally controlled on a horizontal tilt and transported to a lathe where it is possible to measure the "run-out" eccentricity of each disc with respect to the axis formed by the bearings. Possible corrective actions require the disassembly of the rotor.

[0012] Furthermore, the currently available tools and methods require infrastructures (cranes, tower cranes, etc.) and a long time to evaluate and correct the stack.

[0013] Control methods are known for controlling the compliance of the discs before the stack. However, they do not ensure the detection of all the non-compliances of the discs, since the operator is required to perform manual activities and personal evaluations. Therefore, the precision of the check and correction and the time required cannot be considered satisfactory.

[0014] Another control method is disclosed in patent application no. EP3330484A1 filed by the present applicant. Said method detects the tilt of the rotor disc with respect to the horizontal plane and / or the eccentricity of the rotor disc with respect to the connecting rod by means of a ring-shaped device. However, according to said technical solution, the reference for measuring the eccentricity of a single disc is the outer surface of the connecting rod.

[0015] Said technical solution cannot be adopted for rotors already in use (for example for maintenance activities).

[0016] In fact, in overhauled rotors, 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 thermal-mechanical stresses it is subjected to during operation.

[0017] In other words, the outer surface of the central connecting rod cannot be considered an effective geometric reference for the eccentricity measurement. SUMMARY

[0018] Therefore, one object of the present application is to provide a method for controlling the positioning of the rotor discs around the connecting rod of a gas turbine rotor that is precise and reliable and avoids or minimizes the occurrence of balancing errors.

[0019] In this way, the evaluation and correction operations to be performed on a rotor already clamped are minimized.

[0020] According to these objects, the present application relates to a method for controlling the positioning of the rotor discs around the connecting rod of a partially assembled rotor of a gas turbine; the connecting rod extends along a longitudinal axis;

[0021] The method comprises:

[0022] • positioning the link so that the longitudinal axis extends substantially vertically;

[0023] • detecting the eccentricity of the rotor disc with respect to the longitudinal axis of the link 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 link; the assembly further comprises at least three laser emitters coupled to one of the main device and the at least one first reference device, and at least three corresponding light-sensitive sensors coupled to the other of the main device and the at least one first reference device; the light-sensitive sensors are arranged so as to intercept the laser beams emitted by the corresponding laser emitters.

[0024] Another object is to provide an assembly for controlling the positioning of a rotor disc around a link of 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 disc, thereby minimizing the manual activities of the operators and the personal assessment.

[0025] According to these objects, the present application relates to an assembly for controlling the positioning of at least one rotor disc around a link of a partially assembled rotor of a gas turbine; the link extends along a longitudinal axis;

[0026] The assembly comprises:

[0027] • a main device, which in use is coupled to the free face of the rotor disc; and

[0028] • at least one first reference device, which in use is coupled to the link;

[0029] • at least three laser emitters coupled to one of the main device and the at least one first reference device; and

[0030] • at least three corresponding light-sensitive sensors coupled to the other of the main device and the at least one first reference device; the light-sensitive sensors are arranged so as to intercept the laser beams emitted by the corresponding laser emitters. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will now be described with reference to the accompanying drawings, which show non-limiting embodiments thereof, in which:

[0032] – Figure 1 is a side view of a gas turbine rotor with a cross section along a vertical axial plane;

[0033] – Figure 2 is Figure 1 a perspective view of a detail of the gas turbine rotor of

[0034] – Figure 3 is Figure 1a side view of the rotor of the gas turbine engine of Figure 1 a perspective view of a first detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of

[0035] – Figure 4 a bottom perspective view of a second detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0036] – Figure 5 a top perspective view of a second detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0037] – Figure 6 a perspective view of a third detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0038] – Figure 7 a perspective view of a third detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0039] – Figure 8 a schematic view of a fourth detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0040] – Figure 9 a schematic view of a fifth detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0041] – Figure 10 a schematic block diagram of a sixth detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1

[0042] – Figure 11 a schematic top view of a seventh detail of the assembly for controlling the positioning of the connecting rod of the gas turbine engine rotor of Figure 1 DETAILED DESCRIPTION

[0043] In Figure 1 ​​​​​​​​In the drawings, reference numeral 1 refers to a gas turbine rotor of a plant for the production of electric energy, comprising a plurality of discs 2 aligned along an axis A and bound into a pack by means of a central link 3. The central link 3 extends along the longitudinal axis A. A first group of discs 2, provided with respective first rotor blades 5, defines a compressor section la of the rotor 1, while a second group of discs 2, provided with respective second rotor blades 6, defines a turbine section lb of the rotor 1. The compressor section la and the turbine section lb are separated from each other by spacer discs 7, which substantially act as spacer elements and are substantially shaped as cylinders. In use, a combustion chamber (not shown) of the gas turbine is arranged around the spacer discs 7.

[0044] Reference is made to Figure 2 Each rotor disc 2 is provided with a central through hole 8 and with a peripheral edge 9 provided with a plurality of seats 10 suitably shaped so as to be engaged by the respective first rotor blades 5 or to the respective second rotor blades 6.

[0045] The central hole 8 will be engaged, in use, by the link 3 of the rotor 1.

[0046] Each rotor disc 2 is further provided, on each face 13a, 13b of the rotor disc 2 (in the drawings Figure 2 only the face 13a of the rotor disc 2 is well visible) with a radial toothing 12, commonly known as Hirth joint.

[0047] Preferably, the radial toothing 12 is arranged along the respective face close to the peripheral edge 9 of the rotor disc 2.

[0048] The radial toothing 12 is positioned and shaped so as to be coupled to the respective toothing of the adjacent rotor disc 2, so as to build a so-called Hirth joint, and to ensure the stable coupling of the rotor discs 2.

[0049] Figure 3 A partially assembled rotor 1 is shown, in which the link 3 is arranged and supported in a vertical position. In other words, the link 3 is positioned so that the longitudinal axis A is substantially vertical.

[0050] Reference is made to Figure 1 and Figure 3 The link 3 is provided with a first end 15 and with a second end 16 axially opposite to the first end 15.

[0051] In use, the first end 15 is coupled to a front shaft 18 (visible in Figure 1 and 3 ) while the second end 16 protrudes from a rear hollow shaft 19 (visible only in Figure 1 ).

[0052] Preferably, the front shaft 18 is housed in a stacking pit 21, which ensures the correct and stable vertical positioning of the link 3.

[0053] Figure 3 The configuration shown in the middle can occur during the assembly of the rotor 1, when the rotor discs 2 are stacked one on top of the other so that the radial toothed ring bodies 12 of adjacent rotor discs 2 can be coupled to each other, thus building the Hirth joint, as well as during the disassembly of the rotor 1, when the rotor discs 2 are removed one by one.

[0054] The method for controlling the positioning of at least one rotor disc 2 around the connecting rod 3 according to the present application is applied to a partially assembled rotor 1 as shown in the configuration of Figure 3

[0055] The method comprises detecting at least one parameter relating to the position of the at least one rotor disc 2 with respect to one or more references.

[0056] In particular, the method comprises detecting the eccentricity of the rotor disc 2 with respect to the longitudinal axis A with an assembly 23 for controlling 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 connecting rod 3.

[0057] Preferably, the detection of the eccentricity of the rotor disc 2 is obtained by means of at least three laser emitters 28 coupled to one between the main device 24 and the at least one reference device 25, and at least three respective photosensitive sensors 30 coupled to the other between the main device 24 and the at least one reference device 25.

[0058] The three laser emitters 28 are preferably arranged at 120° from each other.

[0059] The photosensitive sensors 30 are also arranged at 120° from each other and are arranged to block the beam of the respective laser emitter 28.

[0060] In the non-limiting example disclosed and illustrated herein, the detection of the eccentricity is made by means of the main device 24 coupled to the free face 13a of the rotor disc 2 and the two reference devices 25, 26 coupled to the connecting rod 3.

[0061] Therefore, in the non-limiting example disclosed and illustrated herein, a first measurement of the eccentricity is made using the main device 24 and the reference device 25, while a second measurement of the eccentricity is obtained using the main device 24 and the reference device 26.

[0062] With reference to Figure 3 , the reference device 25 is coupled near the first end 15 of the connecting rod 3, while the reference device 26 is coupled near the second end 16 of the connecting rod 3. The main device 24 is coupled to the free face 13a of the rotor disc 2 whose position needs to be controlled.

[0063] ​The reference device 25 is preferably fixed to the front shaft 18. More preferably, the reference device 25 is fixed to a portion 31 of the front shaft 18 (see also Figure 1 ), comprised between the first rotor disk 2 and an annular seat 32 formed in the front shaft 18 and configured to house, in use, a compressor ring bearing (not shown in the drawings).

[0064] 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 substantially along a vertical direction.

[0065] With reference Figure 3 , each laser emitter 28 is coupled to a base structure 35, which is provided with positioning means 36. The positioning means 36 are configured to adjust the position of the laser emitters 28. In use, the positioning means 36 are adjusted so that each laser emitter 28 of the reference device 25 emits a laser beam along a substantially vertical direction.

[0066] The positioning means 36 (see Figure 3 ) have multiple degrees of freedom. In particular, the positioning means 36 comprise 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.

[0067] The angular adjustment of each laser beam B emitted by the laser emitters 28, i.e. the rotation about the axes O1 and O2, can be controlled manually or electrically. According to a variant not shown, the positioning means can be replaced by positioning means similar to those that will be described hereinafter and shown in Figure 8 and 9 . Preferably, the reference device 25 is provided with an annular base 39, from which at least three spokes 40 protrude (only two of which are visible in Figure 3 ). Each spoke 40 has a free end 41 to which a respective laser emitter 28 is coupled.

[0068] The free ends 41 of the spokes 40 are arranged at 120° from each other. Preferably, the spokes 40 are arranged radially about the annular base 39.

[0069] The length of the spokes 40 is substantially greater than the maximum height of the compressor blades 5 and turbine blades 6, so that, when the reference device 25 is fixed to the rotor 1, the free ends 41 of the spokes 40 protrude beyond the compressor blades 5 and turbine blades 6.

[0070] Preferably, the annular base 39 can be opened and closed so as to allow it to be positioned and fixed about the portion 31 of the front shaft 18.

[0071] With reference Figure 3 and Figure 4and the non-limiting example shown in 5, with reference to the device 26 is coupled to the second end 16 of the link 3 and is retractable. In particular, the device 26 comprises a cage structure 43 fixed to the link 3 and at least three retractable arms 44 housed in the cage structure 43 and 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 Figure 3 and 5 ), to a stop position, in which the arm 44 is retracted and is completely housed in the cage structure 43 (configuration shown in Figure 4 ). Each arm 44 is a hinged arm, having one end 45 coupled to a movable sleeve 46 and one free end 47 coupled to a respective photosensitive sensor 30.

[0072] Each arm 44 is configured to have a length in the operating position so that each photosensitive sensor 30 can detect the laser beam B' emitted by the respective laser emitter 28, which is supported by the master device 24 as will be detailed hereinafter. Obviously, the arms 44 are arranged at the same angular position of the laser beams B' emitted by the laser emitters 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 a shaft 49. When the sleeve 46 is in the upper position (configuration shown in Figure 4 ), the arms 44 are in the stop position, while when the sleeve 46 is in the lower position (configuration shown in Figure 5 ), the arms 44 are in the operating position.

[0073] The sleeve 46 is preferably moved by a remotely controlled tool (not shown).

[0074] With reference to Figure 3 , the master device 24 is coupled to the free face 13a of the rotor disc 2. With free face we mean here and hereinafter the face of the rotor disc 2 which is not coupled to the other face of the adjacent rotor disc 2.

[0075] As already pointed out, the method according to the present application can be applied both during the assembly and during the disassembly of the rotor 1.

[0076] During the assembly, the detection of the position of the disc 2 occurs before the other rotor disc 2 is stacked on the controlled rotor disc 2, while during the disassembly, the detection of the position of the rotor disc 2 occurs before the controlled rotor disc 2 is removed.

[0077] As a consequence, the method according to the present application requires that the master device 24 is coupled to one rotor disc 2 at a time.

[0078] However, this does not mean that positioning control must be implemented on each disc of the rotor 1. It is also possible to control the positioning of the group of coupled rotor discs 2 by means of detection of the positioning of the rotor disc 2 with free face belonging to the group.

[0079] With reference to Figure 6 and 7 In the illustrated non-limiting example, the master device 24 comprises a support 53, a centering system 54 configured to center the support 53 on the controlled rotor disc 2, and at least three laser emitters 28 and at least three photosensitive sensors 30 coupled to the support 53.

[0080] The support 53 comprises an annular frame 58 and at least three spokes 60 having a protrusion extending radially from the annular frame 58 and arranged at 120° from each other. Each spoke 60 supports a respective photosensitive 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 facing the reference device 25 in use. Preferably, the photosensitive sensor 30 is coupled to the free end 61 of the respective spoke 60.

[0081] The length of the spokes 60 is substantially greater than the maximum height of the compressor blades 5 and turbine blades 6 so that, when the master device 24 is coupled to the rotor disc 2, the free ends 61 of the spokes 60 protrude beyond the compressor blades 5 and turbine blades 6. 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 emitters 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.

[0082] Preferably, the annular frame 58 has one coupling face 62 (visible in Figure 6 ) and one operating face 63 (visible in Figure 7 ), the coupling face 62 facing, in use, the controlled rotor disc 2, and the operating face 63 being opposite the coupling face 62.

[0083] The coupling face 62 is coupled to the centering system 54, while the operating face 63 supports the 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 center of the annular frame 58, which coincides, in use, with the longitudinal axis A.

[0084] For example, the laser emitters 28 are placed on the operating face 63 along a circle having a diameter of about 0.6 m. The spokes 60 are preferably arranged on the operating face 63.

[0085] Preferably, the support 53 comprises a further annular element 65 configured to protect the electronic devices (batteries, tilt sensors, control electronics, laser emitters 28, etc.) during the movement of the main device 24. This further annular element 65 is also configured so as to provide a hooking point for lifting the support 53, for example by means of a crane (not shown).

[0086] In the non-limiting example described and illustrated herein, the support 53 has dimensions compatible with those of the connecting rods 3 and of the rotor discs 2 that make up the rotor 1.

[0087] With reference to Figure 6 , the centring system 54 comprises at least two portions 67 of Hirth toothed annulus, which can be coupled to respective portions of the radial toothed (Hirth) annulus 12 arranged on the free face 13a of one of the rotor discs 2 that make up the rotor 1.

[0088] In order to be coupled to the radial toothed annulus 12 of any rotor disc 2 of the rotor 1, the portions 67 of Hirth toothed annulus must be shaped so as to have a minimum radius equal to the internal diameter of the radial toothed annulus 12 of the minimum rotor disc 2 and a maximum radius equal to the external diameter of the radial toothed annulus 12 of the maximum rotor disc 2.

[0089] Furthermore, the portions 67 of Hirth toothed annulus must have teeth oriented like the teeth of the radial toothed annulus 12, i.e. towards the centre of the rotor disc 2, preserving all the other parameters (inclination of the walls of the teeth, number of teeth, etc.) so as to ensure the correct and stable coupling between the portion 67 and the radial toothed annulus 12 of the rotor disc 2.

[0090] If there are two portions 67 of Hirth toothed annulus, they are diametrically opposite.

[0091] In the non-limiting example described and illustrated herein, the centring system 54 comprises three portions 67, which are separate and arranged on the same plane, preferably at approximately 120° from each other.

[0092] The three portions 67 are substantially identical.

[0093] Each laser emitter 28 coupled to the operating face 63 of the annular frame 58 of the support 53 is preferably coupled to an orientation device 70 (see Figure 8 ) 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.

[0094] With reference to Figure 8 the non-limiting example illustrated in the figure, the orientation device 70 comprises a housing 71 containing a fluid 72. The fluid is, for example, mercury in liquid state. The housing is coupled to the operating face 63 of the annular frame 58.

[0095] The laser emitters 28 are arranged in the housing 71 floating on the fluid 72. Since the free surface 73 of the fluid 72 is always substantially horizontal independently of the inclination of the surface 63 on which the housing 71 is supported, the laser emitters 28 are able to always emit the laser beams B' substantially vertically.

[0096] If the laser emitters 28 have to emit upward laser beams, i.e. towards the end 16 of the link 3, the orientation device 70 works correctly. Figure 8

[0097] According to the variant shown in Figure 9 , the laser emitters 28 are coupled to the surface 62 of the annular frame 58 of the support 53 so as to emit the laser beams downward, i.e. towards the end 15 of the link 3. In this case, each laser emitter 28 is coupled to an axially symmetric body 75 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 beams B' emitted by the laser emitters 28 are always substantially vertical independently of the inclination of the surface 62 on which it is supported.

[0098] According to a variant not shown, the laser emitters can be coupled to other types of devices able to correctly regulate the orientation of the laser beams. For example, mechanized devices or other known laser leveling systems.

[0099] With reference to Figure 7 , preferably the main device 24 also comprises a two-axis inclinometer 78 coupled to the support 53 and configured to measure the inclination of the support 53 with respect to two orthogonal axes.

[0100] 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.

[0101] Preferably, the two-axis inclinometer 78 is coupled to the surface 63 of the annular frame 58 of the support 53.

[0102] The main device 24 also comprises at least two distance probes 80 coupled to the support 53 and arranged on respective points belonging to the same circle (indicated with a dashed line in Figure 7 ). The distance probes 80 are oriented towards the center of the above-mentioned circle. In this way, in use, the distance probes 80 detect the distance with respect to the link 3 along a radial direction.

[0103] In the non-limiting example described and shown herein, the main device 24 comprises three distance probes 80, which are preferably arranged at 0°-90°-225° along the circle.

[0104] ​Preferably, the distance probe 80 is coupled to the operating surface 63 of the annular frame 58 and is arranged at a radial distance from the centre of the annular frame 58 shorter than the radial distance of the laser emitter 28. In other words, the distance probe 80 is arranged internally with respect to the laser emitter 28.

[0105] The distance probe 80 is preferably a contactless probe, for example a laser triangulation system; it allows to measure also the eccentricity of the outer surface of the connecting rod 3 (used and possibly deformed) with respect to a virtual cylinder coaxial to the longitudinal axis A of the rotor 1.

[0106] With reference to Figure 3 In use, the laser emitter 28 on the reference device 25 emits a laser beam B towards the photosensitive sensor 30 of the master device 24, while the laser emitter 28 of the master device 24 emits a laser beam B' towards the photosensitive sensor 30 of the reference device 26.

[0107] According to a variant not illustrated, the reference device 25 comprises a photosensitive sensor, while the master device 24 comprises a laser emitter which emits a laser beam towards the photosensitive sensor of the reference device.

[0108] According to a variant not illustrated, the reference device 26 comprises a laser emitter which emits a laser beam towards the respective photosensitive sensor 30 of the master device.

[0109] Each photosensitive sensor 30 is configured to detect the laser beam which impinges on it and to provide the radial position of the point of impact with respect to the longitudinal axis A.

[0110] With reference to Figure 10 The photosensitive sensor 30 on the master device 24 is able to provide the respective radial distance R1, R2, R3 with respect 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 photosensitive sensor 30 on the reference device 26 (the upper one) is able to provide the respective radial distance R1', R2', R3' with respect to the longitudinal axis A by detecting the laser beam B' emitted by the laser emitter 28 on the master device 24.

[0111] The laser emitters 28 are preferably low-power laser emitters to ensure the safety of the operators. In order to avoid the detection of external light noise by the photosensitive sensors 30, the laser emitters 28 emit laser beams with frequency modulation. In this way, the photosensitive sensors 30 can be provided with suitable filters.

[0112] Said values are sent to a control device 85. The control device 85 comprises a first eccentricity calculator 86 and a second eccentricity calculator 87.

[0113] With reference to Figure 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 sensors 30 and calculate the eccentricity value Vecc of said circle with respect to the centre of symmetry "O" of the main device 24.

[0114] In the case of a significative (but not typical) inclination of the reference device 25, the radial distances R1, R2, R3 must be fitted using an ellipse (instead of a circle); this ellipse can be calculated by considering the data detected by the inclinometer 78 (which is an input of the block 86).

[0115] The second eccentricity calculator 87 is similarly configured to detail the radial distances R1', R2', R3', define a circle (or an ellipse considering the data of the inclinometer 78) passing through the points detected by the sensors 30 and calculate the eccentricity value Vecc' of said circle (or ellipse) with respect to the centre of symmetry "O" of the main device 24.

[0116] The eccentricity values Vecc, Vecc' are sent to the evaluation module 90, where the data regarding the eccentricity of each disc 2 of the rotor 1 are memorized and can detail the evaluation of the positioning of each rotor disc 2.

[0117] According to one variant, not illustrated, the control device 85 comprises only one eccentricity calculator.

[0118] According to one embodiment, not illustrated herein, the control device 85 comprises a further module configured to give indications of possible corrective actions to be implemented as a function of the detected eccentricity values.

[0119] Preferably, the data detected by the light-sensitive sensors 30 are sent to the control device 85 by means of wi-fi communication.

[0120] Preferably, the laser emitters 28 are also remotely controlled by means of wi-fi communication.

[0121] Preferably, the control device 85 is not coupled to the support 53 and is integrated into an external processor (for example a tablet) available to the operator who follows the assembly / disassembly of the rotor 1. In this way, the tablet can give the operator information regarding the correct positioning of the discs on the stack with respect to all the errors and, in any case, store this information.

[0122] In use, in order to control the positioning of the rotor discs 2 around the connecting rod 3, the operator must position the rotor 1 vertically by means of a crane (not illustrated). Preferably, the front shaft 18 of the rotor 1 is housed in the stack pit 21 to ensure the correct and stable vertical positioning of the connecting rod 3.

[0123] Reference devices 25 and 26 are then coupled to the rotor 1 near the end 15 and the end 16 of the connecting rod 3, respectively, by means of a crane.

[0124] 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.

[0125] The positioning of the main device 24 on the rotor disc 2 is adjusted so as to ensure that the laser emitter 28 is substantially vertically aligned with the corresponding light-sensitive sensor 30.

[0126] The main device 24 is also moved by means of the crane.

[0127] After positioning the main device 24, the laser emitter 28 is activated and the eccentricity of the controlled disc is evaluated.

[0128] Preferably, the inclinometer 78 and the distance probe 80 are also activated so as to improve the control of the positioning of the rotor disc 2.

[0129] Advantageously, the assembly 23 and the method for controlling the positioning of the rotor discs according to the present application allow to improve and optimize the assembly of the rotor 1, avoiding to assemble unbalanced rotors and, in particular, the costs deriving from one or more corrective interventions on already assembled rotors.

[0130] The assembly 23 and the method for controlling the positioning of the rotor discs according to the present application can also be applied to already assembled rotors assembled with the existing assembly techniques.

[0131] In the case of already assembled rotors, the assembly 23 and the method according to the present application can be applied during the disassembly of the rotor 1 disc by disc.

[0132] During the disassembly, the rotor discs 2 are removed one at a time and the assembly is used to detect the position of each rotor disc 2 until the rotor disc (or the rotor discs) is found to be the cause of the unbalance of the rotor 1.

[0133] The application of the assembly 23 during the disassembly of the rotor 1 is advantageous compared to the currently known solutions, since it gives an objective indication of the positioning of each rotor disc 2 without introducing the element of the personal assessment of the operator.

[0134] Moreover, for example in the following cases, you are not forced to completely disassemble the rotor 1:

[0135] • if the rotor disc 2 that is the cause of the unbalance is identified before all the rotor discs are removed;

[0136] • if it is confirmed that at least two disks or two groups of disks (even possibly non-adjacent) have a tilt that can be compensated by a correct corrective action (i.e. a rotation with respect to the axis A of one of the disks or groups of disks) that brings back the stack of rotor disks, as a whole, within the given error.

[0137] Basically, the confirmation of the unbalance does not always lead to the replacement of the rotor disk 2. As a matter of fact, the unbalance can simply be corrected by a correct rotation of the rotor disk. In this case, the device has an important role in establishing whether the corrective action is effective and sufficient to compensate the unbalance.

[0138] Finally, it is clear that the components and the methods described herein can be changed and modified without thereby departing from the scope of protection of the attached claims.

Claims

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: 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 connecting rod by means of an assembly (23) comprising a main device (24) coupled to a free face (13a) of the rotor disc (2) and at least one first reference device (25) coupled to the connecting rod (3); the assembly (23) further comprises at least three laser emitters (28) coupled to one between the main device (24) and the at least one first reference device (25) and at least three respective photosensitive sensors (30) coupled to the other between the main device (24) and the at least one first reference device (25); the photosensitive sensors (30) are arranged so as to intercept a laser beam (B) emitted by the respective laser emitter (28).

2. The method of 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 emitters (28) by means of the at least three photosensitive sensors (30) and issuing a signal of the occurrence of an eccentricity (Vecc; Vecc’) on the basis of the detected radial distances (R1, R2, R2; R1’, R2’, R3’).

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

4. The method of claim 1 or 2, wherein, The at least one reference device (25; 26) comprises at least three support elements (40; 44), each of which supports one between the laser emitters (28) and the photosensitive sensors (30).

5. The method of claim 3, wherein, The assembly (23) comprises a second reference device (26); the first reference device (25) is coupled near the first end (15) and the second reference device is coupled to the second end (16).

6. The method of 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 arranged on the first reference device (25) by means of at least three photosensitive sensors (30) arranged on the main device (24); - measuring the second radial distance (R1', R2', R3') between the longitudinal axis (A) and each laser beam (B') emitted by a second laser emitter arranged on the main device (24) by means of at least three photosensitive sensors (30) arranged on the second reference device (26); - signalling a second eccentricity occurrence (Vecc') on the basis of the second radial distance (R1', R2', R3').

7. The method of claim 1 or 2, wherein, At least one laser emitter (28) is coupled to a directional device (70, 75) 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.

8. The method according to claim 1 or 2, further comprising the step of measuring the inclination by means of a inclinometer (78) coupled to the main device (24).

9. 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) which, in use, is coupled to a free face (13a) of the rotor disc (2); and - at least one first reference device (25) which, in use, is coupled to the connecting rod (3); - at least three laser emitters (28) coupled to one of the main device (24) and the at least one first reference device (25); and - at least three respective photosensitive sensors (30) coupled to the other of the main device (24) and the at least one first reference device (25); the photosensitive sensors (30) are arranged so as to intercept the laser beam (B) emitted by the respective laser emitter (28).

10. The assembly of claim 9, wherein, - the at least three photosensitive sensors (30) are configured to measure a radial distance (R1, R2, R3; R1', R2', R3') between the longitudinal axis (A) and each laser beam (B) emitted by the laser emitters (28).

11. The assembly according to claim 10, comprising control means (85) configured to signal an eccentricity occurrence (Vecc; Vecc') on the basis of the detected radial distance (R1, R2, R2; R1', R2', R3').

12. The assembly of any of claims 9 to 11, wherein, - the at least one reference device (25; 26) comprises at least three support elements (40; 44), each of which supports one between the laser emitters (28) and the photosensitive sensors (30).

13. The assembly of any of claims 9 to 11, wherein, - the at least one first reference device (25) is coupled, in use, in the proximity of the first end (15) and / or of the second end (16) of the connecting rod (3).

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

15. The assembly of any of claims 9 to 11, wherein, At least one laser emitter (28) is coupled to a directing device (70; 75) 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.

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