EP2378065B1 - Method for repairing a rotor assembly of a turbo engine. - Google Patents

Description

The present invention relates to a method for repairing a rotor assembly of a turbomachine, a ring member for a rotor assembly of a turbomachine and a rotor assembly for a turbomachine.

Although applicable to any turbomachinery, the present invention and its underlying problem with respect to a rotor assembly for a high pressure compressor will be explained in more detail.

The Fig. 5 to 8 The drawing shows an internally known rotor assembly 2 for a high-pressure compressor.

The rotor assembly 2 has, as Fig. 5 to take a rotor 4 on. The rotor assembly 2 further comprises blades 6, 8. Fig. 5 shows by way of example only one blade 6, 8 of a row of blades, each of which is arranged along the circumference of the rotor 4. In a first of two regions 10, 12 of the rotor assembly 2, the blades 6 are respectively held in axial grooves 14 in the rotor 4 in the radial direction in a form-fitting manner, for example by means of a dovetail or pine cone connection. In the present case, the terms "axial", "radial" and "circumferentially" refer to a central axis 16 of the rotor 4. In order to prevent slippage of the blades 6 from their grooves 14 in the axial direction, retaining plates 18 (English: retaining plates ) are arranged in the form of ring sections in a circumferentially extending groove 20 in the rotor 4 and in a circumferentially extending groove 22 of each blade 6, thus ensuring positive engagement in the axial direction between each blade 6 and the rotor 4 Fig. 5 For the sake of clarity, only one of a plurality of holding plates 18 arranged along the circumference in the grooves 20 and 22 is shown. Further, a plurality of closing plates (not shown) are usually provided, which are each arranged in a gap between two retaining plates 18. The locking plates differ essentially from the retaining plates 18 in that that the strike plates are not inserted as the retaining plates 18 along the circumference in the grooves 20, 22, but by forming them in the grooves 20 and 22 are driven.

In the second region 12 of the rotor 4 is formed with circumferentially extending grooves 24 which are in the radial direction with the blades 8 positively, for example by means of a dovetail or Pannenzapfenverbindung in engagement. In the second region 12, the rotor 4 has longitudinally extending grooves 26 in front of and behind each row of airfoils 8 in its circumferential direction. The grooves 26 are also in Fig. 6 shown, which is a sectional view A from Fig. 5 shows. In each of the grooves 26, a damper ring 28 (English: damper ring) is arranged, such as Fig. 6 refer to. Fig. 6 only illustrates two of the grooves 26 with the damping rings 28 for better understanding.

Fig. 7 shows the damping ring 28 in an enlarged plan view B from Fig. 6 , The damping ring 28 is formed for the purpose of its assembly on the rotor 4 over a part of its circumference of time, thereby forming the two ends 30 and 32, which are each rounded. The damping rings 28 move during the rotation of the rotor assembly 2 relative to the rotor 4 and the blades 8. The resulting friction damps unwanted vibrations of the rotor assembly. 2

Fig. 8 illustrates an enlarged partial view C from Fig. 6 , The groove 26 is formed by two opposing collars 34 and 36 and by a bottom 38. The original state of the groove 26 is in Fig. 8 shown in dashed lines. The above-described relative movement between the damping ring 28 and the rotor 4 now leads to the fact that in particular the ends 30 and 32 of the damping ring 28 dig into the collars 34, 36 of the groove 26. This creates, for example, a notch 40 in the collar 36. If this notch 40 exceeds predetermined dimensions, this is advantageously to be rounded. This is usually done by the material surrounding the notch is removed for example by means of a milling head or grinding head. The rounded area is in Fig. 8 designated by the reference numeral 42. After rounding, the damping ring 28 is inserted back into the groove 26 and the rotor assembly 2 is put back into operation. During operation, the ends 30 and 32 of the damping ring 28 are caught entangled in the rounded portion 42, so that it comes within a short time to re-serration or there is a risk that one end of the damping ring 28 in the axial direction of the blades 8 passes by. If there is enough material left for further rounding, the rotor will be repaired again. Otherwise, the rotor may need to be completely replaced. But especially in the latter case, this leads to very high costs, since the rotor body is made of titanium in a very complex process.

A similar problem arises in the retaining plates 18 and the locking plates, not shown, which also dig in particular with their corners and edges in the grooves 20 and generate notches there or there is a risk that a retaining plate 18 in the axial direction of the blades 8 passes by or gets damaged. The notches in the grooves 20 are currently being repaired in the same manner as described above for the groove 26, also causing the problem of the above-mentioned re-serration.

In the publication US 4,817,455 A1 ring elements are disclosed for a rotor assembly, wherein in a ring portion a circumferentially extending groove is arranged in which engages an engagement element.

On this basis, it is an object of the present invention to provide an improved repair method, an improved ring element and / or an improved rotor, so that the life of a rotor of the rotor assembly is extended.

This object is achieved by a method with the features of Patent claim 1, solved by a ring element with the features of claim 5 and by a rotor assembly having the features of claim 10.

Accordingly, a method of repairing a rotor assembly of a turbomachine having a rotor with a circumferentially extending groove for receiving a ring portion is provided with the following steps. In a first step, a notch in the groove is rounded. Before, simultaneously or hereafter a recess is incorporated into the groove. Thereafter, the ring portion is inserted into the groove, wherein at least one engaging element formed on the ring portion engages in the recess for forming an anti-rotation in the circumferential direction.

The idea underlying the present invention is to prevent a relative movement in the circumferential direction between the ring portion and the groove. In the event that the ring portion is formed, for example, as a damping ring, this has the advantage that in particular the ends of the damping ring by means of the rotation no longer in the rounded area or a random range can be incorporated, which is extended as a result, the life of the rotor. In the event that the ring portion is formed, for example, as a retaining plate or locking plate, there is the advantage that in particular the corners or edges of the retaining plates or locking plates can not dig into the rounded area or lost due to the rotation, which also here An extension of the life of the rotor can be achieved.

Although the advantage of the invention especially comes into play especially when already a rounded portion is present in the groove in which the ends of the damping ring or the corners and edges of the retaining plates or locking plates can dig, so it is according to the invention also intended to provide the rotor assembly from the beginning with the rotation between the ring portion and the rotor and not form them first in the repair process.

Advantageous developments emerge from the subclaims.

In the present case, a "ring section" is to be understood, in particular, as meaning a damping ring, a holding plate for a blade or a striking plate, in each case for a rotor arrangement of a turbomachine.

In the present case, a "notch" is understood as meaning, in particular, a defect in the material of the rotor, which, if it is not repaired, can lead to failure of the rotor.

In the present case, a "recess" is preferably to be understood as meaning a pocket or a breakthrough.

According to a preferred embodiment of the method according to the invention, the at least one engagement element is mounted prior to insertion of the ring portion in the groove on this, in particular welded or soldered. Advantageous Thus, the existing ring section is not replaced by a new ring section to which the at least one engagement element is attached. Rather, the existing ring portion is first removed from the groove, thereafter the notch rounded, incorporated the recess and then the provided with the one engagement member ring portion are re-inserted into the groove. By means of this development, advantageously less ring sections, which are comparatively expensive, are required.

For example, one, two or four engagement elements can be provided.

According to a further preferred refinement of the method according to the invention, the at least one engagement element is formed by means of reshaping, in particular bending, of a partial region of the annular section. As in the above development, it is also advantageous in this development to continue to use the original ring section. Furthermore, according to this development, the at least one engagement element is formed by the ring portion itself, whereby additional components can be saved.

According to a further preferred embodiment of the method according to the invention, the recess is incorporated into a collar of the groove opposite the notch such that a tool for rounding the notch is substantially rectilinearly movable through the recess to the notch. According to this development, the recess has a double function: On the one hand, it provides good accessibility for a tool, for example for a milling head, to the notch in order to round it. On the other hand, it serves as a counterpart for the engagement element and thereby ensures the described rotation.

According to a further preferred development of the ring element according to the invention, the at least one engagement element is designed as a bump, which extends in the axial direction of the ring portion thereof. Such a hump is well suited to having a corresponding recess in the waistband the groove cooperate.

According to a further preferred development of the ring element according to the invention, the ring portion is formed with two first, spaced apart engagement elements, which are adapted to abut after insertion of the ring portion in the groove against opposite ends of the recess. The aim is to provide an anti-rotation in both circumferential directions, ie clockwise and counterclockwise. Since the area to be rounded in some cases extends over a comparatively large circumferential length and the recess is therefore correspondingly long, it would be appropriate to provide a correspondingly long engagement element as well. However, since this leads to a high weight, it is provided according to this development, dividing the engagement element into two engagement elements of only small length in the circumferential direction of the ring, which are arranged so that they are opposite to the insertion of the ring portion in the groove Abut ends of the recess. Of course, it is also conceivable to provide the recess at any other area of the collar or the bottom of the groove, so not necessarily opposite the notch.

According to a further preferred development of the ring element according to the invention, the ring portion is formed as a damping ring, retaining plate for at least one blade of the rotor assembly or striking plate of the rotor assembly.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying figures of the drawing.

Fig. 1

in einer perspektivischen Ansicht eine Nut mit einer verrundeten Kerbe und einer Ausnehmung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;

Fig. 2

in einer perspektivischen Ansicht einen Abschnitt eines Ringelements gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;

Fig. 3

die Ansicht aus Fig. 1, wobei das Ringelement aus Fig. 2 in die Nut eingesetzt ist;

Fig. 4

das Ringelement aus Fig. 2 in einer Ansicht entlang dessen Mittelachse;

Fig. 5

in einer perspektivischen Ansicht eine der Anmelderin intern bekannte Rotoranordnung;

Fig. 6

eine Schnittansicht A aus Fig. 5;

Fig. 7

eine vergrößerte Draufsicht B aus Fig. 6; und

Fig. 8

eine vergrößerte Ansicht C aus Fig. 6.

From the figures show:

Fig. 1

in a perspective view a groove with a rounded notch and a recess according to an embodiment of the present invention;

Fig. 2

in a perspective view a portion of a ring member according to an embodiment of the present invention;

Fig. 3

the view Fig. 1 , wherein the ring element made Fig. 2 inserted into the groove;

Fig. 4

the ring element Fig. 2 in a view along the central axis thereof;

Fig. 5

in a perspective view of the applicant internally known rotor assembly;

Fig. 6

a sectional view A from Fig. 5 ;

Fig. 7

an enlarged plan view B from Fig. 6 ; and

Fig. 8

an enlarged view C from Fig. 6 ,

In the figures, the same reference numerals designate the same or functionally identical components, unless indicated otherwise.

Fig. 1 is based on a perspective view D Fig. 8 , It is therefore with regard to the following explanations at least partially to the Ausführungsgen in connection with the Fig. 5 to 8 directed. A contour of the state of the rotor 4 with the notch 40, as in Fig. 8 is shown in Fig. 1 shown in dashed lines. The damping ring 28 is already out of the groove 26 in Fig. 1 taken from. This condition is assumed for the following description.

First, the groove 26 is usually cleaned and inspected for notches 40. Will a notch 40, as in Fig. 1 shown, found, so in a next step, a continuous recess 44, for example by means of a milling head 46 in the collar 34 opposite the collar 36, which has the notch 40, milled. The extent of the recess 44 in the circumferential direction preferably corresponds at least to the extent of the region 42 to be rounded in the circumferential direction.

In a further step, the milling head 46 or another tool, such as a grinding head, in the in Fig. 1 shown arrow direction 48 through the formed recess 44 through substantially at right angles to the collar 36 driven to round the notch 40 and thus to form the rounded portion 42.

Before, during and / or after the steps described above, two engagement elements 48 in the form of bumps are welded or soldered to the damping ring 28 after its removal from the groove 26, as in FIG Fig. 2 is shown. The bumps 48 extend from a side surface 50 of the damping ring 28, preferably in the axial direction in their welded state. Further, the bumps 48 on different sides of a disconnection point, not shown, for opening the damping ring 28, as above in connection with Fig. 7 described, arranged. The damping ring 28 forms a ring element 54 together with the engagement elements 48.

Alternatively, the engagement elements can each be produced by bending a portion 49 of the damping ring 28, for example in the axial direction, as in FIG Fig. 2 shown. The bent portion 49 is in Fig. 2 dashed and shown only at one point of the damping ring 28. However, it is just as possible to produce several bent portions, for example, according to the arrangement of the bumps 48 in Fig. 2 ,

Furthermore, the damping ring 28 may be formed with two further engagement elements 60, for example in the form of bumps or bent-over portions, as in FIG Fig. 4 shown. The engagement elements 60 engage in a recess 44 correspondingly formed and substantially opposite recess (not shown) in the collar 34 a. The engagement elements 48 or 49 and 60 are arranged according to this embodiment mirror-symmetrically with respect to two the Ftingmittelpunkt 61 intersecting and perpendicular to each other arranged axes 62, 64 on the damping ring 28 and have approximately the same masses. As a result, an imbalance due to otherwise unevenly distributed masses can be advantageously avoided.

In a further method step, the ring member 54 is again inserted into the rotor body 4, that is, the damping ring 28 is inserted into the groove 26, in which case the bumps 48 (or the bent portions 49) engage in the recess 44 and against opposite ends 56 of Recess 44 abut. The bumps 48 thereby prevent the damping ring 28 from rotating in the counterclockwise direction in the circumferential direction 58.

This rotation prevents that in particular the end 30 of the damping ring 28 digs into the rounded portion 42 and there again leads to the formation of notches 40 and that move the end 30 of the damping ring 28 past the blades 8 in the annulus and consequential damage the rotor 4 and the blades 8 trigger. The life of the rotor 2 can thus be extended.

The rotor 2 can now be put into operation again.

The application of the invention to the retaining plates 18 or the locking plates, not shown, would be exactly as it was explained above in connection with the figures 1 to 4. The only difference would be essentially that the damping ring 28 would be replaced by a retaining plate 18 or a strike plate.

In the present case, "one" or "one" does not exclude a multiplicity. It should also be noted that features or steps described in connection with one of the above embodiments also in combination with features or steps of other embodiments described above may be used. The developments and exemplary embodiments described herein for the method apply correspondingly to the ring element and the rotor arrangement, and vice versa.

Claims (4)

1. Method for repairing a rotor arrangement (2) of a turbo machine, said rotor arrangement having a rotor (4) having a groove (26) extending in the peripheral direction (58) thereof for receiving a ring section (18; 28), wherein a notch (40) is present in the groove (26), said method having the following steps:

   - chamfering the notch (40) in the groove (26);

   - incorporating a recess (44) into the groove (26); and

   - inserting the ring section (18; 28) into the groove (26), wherein at least one engagement element (48; 49) formed on the ring section (18; 28) engages with the recess (44) to form anti-twist projection in the peripheral direction (58).
2. Method according to claim 1,
   characterised in that
   before the insertion of the ring section (18; 28) into the groove (26), the at least one engagement element (48) is attached to this ring section, in particular welded on or soldered on.
3. Method according to claim 1,
   characterised in that
   the at least one engagement element (49) is formed by way of remodelling, in particular blending, a partial region of the ring section (18; 28).
4. Method according to at least one of the preceding claims,
   characterised in that
   the recess (44) is incorporated into a collar (36) of the groove (26) opposite the notch (40) in such a way that a tool (46) for chamfering the notch (40) is able to move in a substantially straight line through the recess (44) to the notch (40).

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