WO2005071227A1

WO2005071227A1 - Method and device for repairing integrally bladed rotors

Info

Publication number: WO2005071227A1
Application number: PCT/DE2004/002796
Authority: WO
Inventors: Armin Eberlein; Albert-Valentin Schneider
Original assignee: Mtu Aero Engines Gmbh
Priority date: 2004-01-21
Filing date: 2004-12-22
Publication date: 2005-08-04
Also published as: DE102004002965A1

Abstract

The invention relates to a method for repairing integrally bladed rotors, comprising at least the following steps: a) provision of an integrally bladed rotor (10), at least one blade (12) of which requires repair; b) patching of the blade or each blade of the rotor (10) requiring repair (12); c) thermal treatment, in particular stress-relief annealing, of the integrally bladed rotor (10), said treatment being applied locally to the rotor blade or blades (12) that have been patched; d) surface hardening and/or surface finishing and/or surface coating of the integrally bladed rotor (10), said treatment being applied locally to the patched and thermally treated, in particular stress-relief annealed rotor blade or blades (12).

Description

Method and device for repairing integrally bladed rotors

The invention relates to a method for repairing integrally bladed rotors according to the preamble of claim 1. Furthermore, the invention relates to a device for the heat treatment of integrally bladed rotors when repairing the same according to the preamble of patent claim 8.

Integrally bladed rotors of, for example, gas turbines, in particular of aircraft engines, are subject to high loads and thus wear during operation. In addition to oxidation, corrosion or erosion, integrally bladed rotors can also be damaged by bird strikes or hailstorms, for example. It may be necessary to repair individual rotor blades of the integrally bladed rotor by welding a so-called patch. In the repair of integrally bladed rotors, the state of the art proceeds such that after one or more rotor blades of the integrally bladed rotor have been repaired, the entire integrally bladed rotor is heat-treated and then surface hardening and surface smoothing and optionally surface coating of the entire integrally bladed Rotor is carried out. In an extreme case, this means that according to the prior art, even if only a single rotor blade of the integrally bladed rotor has to be repaired, the entire integrally bladed rotor must be subjected to the heat treatment and the subsequent surface treatment. This is disadvantageous since the repair of integrally bladed rotors becomes complex and expensive, and because this reduces the fatigue strength or service life of the integrally bladed rotor. Repeated heat treatment and surface hardening can cause material embrittlement or material change on the integrally bladed rotor, which is the reason why the heat treatment and the subsequent surface treatment cannot be repeated as often as desired.

Proceeding from this, the present invention is based on the problem of a novel method for repairing integrally bladed rotors and a novel device. To create heat treatment of integrally bladed rotors when repairing them.

This problem is solved in that the aforementioned method for repairing integrally bladed rotors is further developed by the features of the characterizing part of patent claim 1. The method according to the invention comprises at least the following steps: a) providing an integrally bladed rotor to be repaired on at least one rotor blade; b) repairing the or each rotor blade of the integrally bladed rotor to be repaired; c) heat treating, in particular stress relieving, the integrally bladed rotor locally on the or each repaired rotor blade; d) surface hardening and / or surface smoothing and / or surface coating of the integrally bladed rotor locally on the or each repaired and heat-treated, in particular stress-relieved, rotor blade.

In the sense of the present invention, it is proposed to heat-treat an integrally bladed rotor only in the region of the rotor blades, which have to be repaired when the integrally bladed rotor is repaired. The heat treatment and the subsequent surface treatment are therefore only carried out locally on the rotor blades to be repaired. This reduces repair time and repair costs. Since the heat treatment and the subsequent surface treatment are only carried out locally on the sections of the integrally bladed rotor on which repairs are carried out, material embrittlement or material changes are avoided on the remaining areas or sections of the integrally bladed rotor. In this way, the service life of the integrally bladed rotors can be optimized, since the integrally bladed rotor can be repaired more frequently.

The device according to the invention for the heat treatment of integrally bladed rotors when repairing them is defined in independent claim 8. Preferred developments of the invention result from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being restricted to this. It shows:

1 shows a detail of an integrally bladed rotor with two repaired or to be repaired rotor blades in a front view;

2 shows a device for repair, namely for heat treatment, of a rotor blade of an integrally bladed rotor in the region of a short weld in a highly schematic front view;

3 shows a device for repair, namely for heat treatment, of a rotor blade of an integrally bladed rotor in the region of a long weld seam in a highly schematic front view;

4 shows a further device for repair, namely for heat treatment, of integrally bladed rotors in a highly schematic front view; and

Fig. 5 shows a protective gas bell for use in the repair, namely the heat treatment, of integrally bladed rotors in a highly schematic front view.

The present invention is described in greater detail below with reference to FIGS. 1 to 5.

1 shows a section of an integrally bladed rotor 10 of a gas turbine, namely an aircraft engine, the integrally bladed rotor 10 having a disk-shaped base body 11 and a plurality of rotor blades 12 connected to the disk-shaped base body 11. Such an integrally bladed rotor 10 with a disk-shaped base body 11 is also referred to as a blisk (bladed disk).

Two rotor blades 12 of the integrally bladed rotor 10 according to FIG. 1 have a repair section 13 or 14, the repair sections 13 or 14 being provided by welding a so-called patch 15 or 16 to the respective rotor blade 12. A weld seam 17 or 18 runs between the patch 15 or 16 and the respective rotor blade 12. As can be seen in FIG. 1, the two patches 15 and 16 and weld seams 17 and 18 differ in their geometric dimensions. The patch 15 or the white seam 17 extends essentially in the radial direction of the respective rotor blade 12, the radial extent of the rotor blades 12 being identified by lines 19. This results in a relatively long weld 17 between the patch 15 and the respective rotor blade 12, which is why such a repair section 13 is referred to below as a long patch. In contrast, the patch 16 extends essentially only in the region of a radially outer blade tip of the respective rotor blade 12, with a weld seam 18 running obliquely or transversely to the radial extent of the rotor blade 12. The weld seam 18 between the patch and the corresponding rotor blade 12 is opposite the weld seam 17 between the patch 15 and the respective rotor blade 12 is relatively short, which is why such a repair section 1 4 is referred to below as a short patch.

1 shows the repair sections 13 and 14 in each case in the region of a flow inlet edge of the respective rotor blades 12. It goes without saying that such repair sections can also occur in the region of a flow outlet edge of the rotor blades 12. Accordingly, such short patches or long patches may also be present in the area of the flow exit edges (not shown) in the area of the rotor blades 12.

Since the cross-sectional profile of the rotor blades 12 changes greatly on the one hand via their radial extension and on the other hand between the flow inlet edge and the flow outlet edge thereof, the short patches and the long patches in the region of the flow inlet edge and the flow outlet edge have different geometries, which is more important when repairing such integrally bladed blades Rotors 10 is to be observed.

According to the inventive method for repairing integrally bladed rotors, the procedure is such that after provision of an integrally bladed rotor 10 to be repaired on at least one rotor blade 12, the or each rotor blade 12 to be repaired is repaired. Mending the or everyone to repair the rotor Blade 12 of the integrally bladed rotor 10 is preferably made by welding a so-called patch 15 or 16 to form a repair section 13 or 14 on the rotor blade 12.

In the sense of the present invention, the integrally procured rotor 10 is then locally heat-treated on the or each repaired rotor blade 12, namely stress-relieved. The heat treatment or stress relief annealing therefore takes place in the sense of the present invention only on the rotor blades 1 2, which have been repaired by welding a patch 15 or 16. The stress relieving takes place by induction heating or electromagnetic heating locally in the area of the respective repair section 13 or 14 on the respective rotor blade 12. Since, as already mentioned, the repair sections 13 and 14 depend on whether they are designed as a short patch or as a long patch and, depending on whether the repair section is located in the region of a flow entry edge or a flow exit edge of the respective rotor blade 12, have very different geometries, heaters adapted to the respective repair section are used for heat treatment or for stress relief annealing.

The stress relieving or heat treatment is preferably carried out under a protective gas atmosphere, for which purpose a suitably adapted protective gas bell is used. At this point it should be pointed out that the stress relief annealing or the heat treatment can take place after the patch has been welded on and after the welded patch has been pre-milled. After pre-milling, there is better accessibility.

Subsequent to the heat treatment, surface hardening and / or surface smoothing and / or surface coating of the integrally bladed rotor 10 takes place locally on the or each repaired and heat-treated rotor blade 12. The heat treatment and the surface treatment of the integrally bladed rotor 10 are accordingly applied to the repaired rotor blades 12 limited. This can significantly reduce repair times on integrally bladed rotors. Repair costs can also be significantly reduced. It is further within the scope of the present invention to continuously monitor the heat treatment of the integrally bladed rotor 10 locally on the or each repaired rotor blade 12 by temperature measurements and to regulate it as a function thereof. For this purpose, sensors for temperature measurement are assigned to the heating device, which serves to heat the rotor blades 12 locally in the area of the respective repair sections. With the aid of these sensors, the temperature on the respective rotor blade 12 can be continuously recorded. Corresponding temperature measurement values are forwarded to a control device which controls the heat treatment of the rotor blades 12 as a function of the measurement values and predetermined temperature setpoints.

As already mentioned, the repair sections differ depending on whether there is a short patch or a long patch on the respective repair section, and depending on whether the repair section runs in the region of a flow inlet edge or a flow outlet edge of the rotor blade 12, due to their geometric dimensions. In the sense of the present invention, a heating device adapted to the respective repair section is used for the heat treatment. The heating device enables stress relieving locally in the area of the respective repair section by induction heating or electromagnetic heating.

FIG. 2 shows such a heating device 20 for a repair section in the form of a short patch on the flow entry edge of a rotor blade 12 of an integrally bladed rotor 10. The heating device 20, which is shown in a highly schematic manner in FIG. 2, has two induction coils or two electromagnetic coils Converter, wherein a first induction coil or a first electromagnetic converter is adapted to a suction side and a second induction coil or a second electromagnetic converter to a pressure side of the repair section of the rotor blade 12. The induction coils are adapted to the cross-section of the repair section in order to enable uniform heating of the repair section or the respective weld seam. Each of the two coils is preferably embedded in a ceramic. The ceramic serves to stabilize the coils and the exact position The same on the suction side and the pressure side of the repair section. It is also possible that the heating means, induction coil is formed of only one, preferably embedded in a Ke ^¬ Ramik, said coil o- to a suction side of which is adapted to a pressure side of the repair portion of the rotor blade.

Since, as already mentioned, the heating devices are adapted to the geometrical dimensions of the repair section, four different heating devices are preferably provided in the sense of the present invention, namely a heating device for a short patch in the region of the flow inlet edge, a heating device for a long patch in the area of the flow inlet edge, a further heating device for a short patch in the area of the flow exit edge and a further heating device for a long patch also in the area of the flow exit edge of a rotor blade.

The induction coils or electromagnetic transducers embedded in the ceramic are positioned on the suction side or pressure side of the repair section in such a way that they come into contact with the ceramic surface on the repair section or on the airfoil of the rotor blade 12 and extend over the area of the weld seam. According to a first alternative of the present invention, a separate frequency unit is assigned to both the induction coil for the suction side and the induction coil for the pressure side, so as to control or regulate the high-frequency induction heating of the repair section. In this case, both in the area of the suction side and in the area of the pressure side of a repair section, the coil embedded in the ceramic or the electromagnetic transducer embedded in the ceramic is positioned separately and fastened separately, so that each induction coil half forms a separate unit. In contrast to this, it is also possible to couple the two induction coil halves to one another by attaching connecting pieces, so that only one frequency unit has to be provided for both induction coil halves. The two connecting pieces required for this are also suitable for induction and are connected to the same after the coils or electromagnetic transducers embedded in ceramic have been positioned. It should be pointed out that the coils or transducers are of course designed in such a way that the different thicknesses of the repair sections are taken into account in order to make the heat input into the respective repair section more uniform. The positioning of the induction coils or electromagnetic transducers on the suction side and the pressure side of the repair section is also carried out in such a way that a constant distance between the heating device and the repair section is maintained. This also makes it possible to achieve more uniform heat input and thus a reproducible heat treatment process on the rotor blades of the integrally bladed rotor.

According to an advantageous further development of the present invention, the heating device 20 can be assigned a cooling device 21. In the exemplary embodiment in FIG. 2, the cooling device 21 consists of a plurality of cooling jaws 22 and 23, which, like the heating device 20, are adapted to the contour or to the geometric dimensions of the repair section. The cooling jaws 22 and 23 are preferably air-cooled or water-cooled copper mold jaws, with at least one such copper mold jaw coming into contact on the suction side and on the pressure side of the repair section. A targeted heat dissipation can be implemented via the cooling device in order to avoid undesired heating of areas of the rotor blade 1 2 which adjoin the repair section. The cooling jaws are positioned on the repaired rotor blade 12 following the induction coil halves. The cooling jaws 22 and 23, like the induction coil halves of the heating device 20, are adapted to the respective repair section of the rotor blade 12 in accordance with the contour. It is also possible for the cooling device to be formed solely from a cooling jaw, this cooling jaw being adapted to the suction side or to the pressure side of the repair section of the rotor blade.

3 shows a rotor blade 12 together with a heating device 20, the heating device 20 being adapted to the contour or the geometric dimensions of a repair section in the region of a flow exit edge of the rotor blade 12, which is designed as a so-called long patch. With regard to the heating device 20 of FIG. 3, reference can be made to the statements made in connection with FIG Heater 20 are referenced. The only difference between the two heating devices 20 of FIGS. 2 and 3 is that the heating device 20 according to FIG. 2 is a heating device which is adapted to a short patch in the region of the flow inlet edge of the rotor blade 12, whereas it is 3 is a heating device which is adapted to a long patch in the region of a flow exit edge of the rotor blade 1.

4 shows a further rotor blade 12 of the integrally bladed rotor 10 with a welded-on patch 24. The heating device 20 in turn extends in the region of a weld seam 25 between the patch 24 and the rotor blade 12. The heating device 20 is again designed as an induction heating device. wherein induction coils or electromagnetic transducers are embedded in a ceramic and are adapted to the geometric shape of the repair section in the area of the weld seam 25. In the exemplary embodiment in FIG. 4, the heating device 20 is in turn assigned a cooling device 21. In the exemplary embodiment in FIG. 4, the cooling device 21 is formed by a plurality of air-cooled or water-cooled copper tappets 26. The copper tappets 26 bear against the actual contour of the rotor blade 12 and of the patch 24, as a result of which an improved heat dissipation and thus an improved cooling effect is provided compared to the cooling jaws 22 and 23 in FIG. 2. It is also possible to combine cooling jaws 22 and 23 with copper tappets 26 to form a cooling device.

In contrast to the exemplary embodiments shown, it is also possible to integrate a circumferential groove in the welded patch 15, 16 or 24, which prevents heat dissipation in areas adjacent to the patch. In this way too, the heat input to the repair section can be limited locally.

The heat treatment or the stress relief annealing of the rotor blade 12 repaired by welding a patch is preferably carried out under a protective gas atmosphere. For this purpose, the repaired rotor blade 12 is positioned together with the heating device 20 and the cooling device 21 in an adapted protective gas bell 27. For reasons of a simpler representation, only the protective gas bell 27 together with the rotor blade 12 positioned in the protective gas bell 27 is shown in FIG. 5. On the illustration of the heating device 20 and cooling device 21 has been omitted in FIG. 5. The protective gas bell 27 is adapted in such a way that only the rotor blade 12 is positioned in the protective gas bell 27, which is repaired by welding a so-called patch and on which the heat treatment must consequently be carried out. All other rotor blades 12 are preferably not covered by the protective gas bell 27. In a lower region, in which the rotor blade 12 is inserted into the protective gas bell 27, the latter has a sealing device 28. In the exemplary embodiment shown, the sealing device 28 is designed as a hose which is inflated after the protective gas bell has been positioned and fastened, and thus seals the seal the shielding gas bell 27 introduced rotor blade 12 compared to the other parts of the integrally bladed rotor 10. An air connection for introducing or discharging the air into the hose is identified in FIG. 5 by the reference number 29.

For online monitoring of the heat treatment, temperature sensors are preferably integrated in the heating device 20. Eight temperature sensors are preferably provided, four temperature sensors being assigned to the suction side and a further four temperature sensors being assigned to the pressure side of the repair section of the rotor blade 12. Four temperature sensors are therefore integrated as sensors in each induction coil half of the heating device. These transmit their measurement signals to a control device (not shown), which compares the actual values determined by the temperature sensors with predetermined target values and regulates the heating power of the heating device as a function thereof, in order to achieve the desired heating of the repaired rotor blade 12 in the area of the respective repair section.

Claims

claims

1. A method for repairing integrally bladed rotors, characterized by the following steps: a) providing an integrally bladed rotor (10) to be repaired on at least one rotor blade (12), b) repairing the or each rotor blade (12) of the integrally to be repaired bladed rotor (10), c) heat treating the integrally bladed rotor (10) locally on the or each repaired rotor blade (12), d) solidifying surfaces and / or surface smoothing and / or surface coating the integrally bladed rotor (10) locally on the or each repaired and heat-treated rotor blade (12).

2. The method according to claim 1, characterized in that the repair of the or each rotor blade to be repaired (12) of the integrally bladed rotor (10) by welding a patch (15, 16) to form a repair section (13, 14) on the respective Rotor blade (12) takes place.

3. The method according to claim 1 or 2, characterized in that the heat treatment is carried out by stress relieving.

4. The method according to claim 3, characterized in that the stress relieving of the integrally bladed rotor (10) is carried out locally on the or each repaired rotor blade (12) by induction heating.

5. The method according to claim 4, characterized in that an induction heating device (20) adapted to the repair section (13, 14) is used for induction heating.

6. The method according to one or more of claims 3 to 5, characterized in that the stress relieving of the integrally bladed rotor (10) is carried out locally on the or each repaired rotor blade (12) using an adapted protective gas bell (27).

7. The method according to one or more of claims 3 to 6, characterized in that the stress relieving of the integrally bladed rotor (10) locally on the or each repaired rotor blade (12) is continuously monitored by temperature measurement and is regulated as a function thereof.

8. Device for the heat treatment of integrally bladed rotors when repairing the same, characterized in that it is designed as a heating device (20) which is attached to a repair section (13, 14) of a rotor blade (12) of an integrally bladed rotor (10) it is adapted that the integrally bladed rotor (10) can be heat-treated locally on the repair section (13, 14) of the rotor blade (12), preferably by stress relief annealing.

9. The device according to claim 8, characterized in that it is formed from an induction coil, preferably embedded in a ceramic, this coil being adapted to a suction side or to a pressure side of the repair section (13, 14) of the rotor blade (12).

10. The device according to claim 8, characterized in that that it is formed from at least two induction coils, preferably embedded in a ceramic, a first coil being adapted to a suction side and a second coil to a pressure side of the repair section (13, 14) of the rotor blade (12).

1 1. Device according to one or more of claims 8 to 10, characterized in that it is adapted to a weld seam (17, 18, 25) between a patch (1 5, 16, 24) and the rotor blade (12) to be repaired ,

12. The device according to one or more of claims 8 to 1 1, characterized in that the same has a cooling device (21) in order to improve the heat treatment locally at the repair section of the rotor blade (12) by the fact that at least one, the Repair section adjoining section of the rotor blade heat can be dissipated.

13. The apparatus according to claim 12, characterized in that the cooling device (21) on a suction side and / or on a pressure side of the repair section of the rotor blade, air-cooled or water-cooled cooling jaws (22, 23), wherein on the suction side and / or on at least one cooling jaw comes into contact with the pressure side.

14. The apparatus according to claim 12 or 13, characterized in that the cooling device (21) has a plurality of air-cooled or water-cooled copper tappets (26), wherein a plurality of copper tappets (26) come to rest on the repair section of the rotor blade (12).

15. The device according to one or more of claims 8 to 14, characterized in that that several temperature sensors for continuous monitoring of the heat treatment, in particular the stress relief annealing, are integrated in the same.

16. The apparatus according to claim 15, characterized in that eight temperature sensors are integrated in the same, four for a suction side and four for a pressure side of the repair section of the rotor blade.