DE102004059904A1 - Moving blade e.g. for turbo machine, has blade point which faces stator in turbo machine and contacts into channel of stator with blade point provided in such way that blade contacts channel at its edges and into rotor - Google Patents

Abstract

The rotor blade (10) has a blade point (13), which faces a stator in a turbo machine and contacts into a channel of a stator (15). The blade point is provided in such a way that the blade contacts the channel (22) at its edges (25, 26), and into the rotor. The blade point can be varied in length. An independent claim is included for a method.

Description

TECHNICAL TERRITORY

The The present invention relates to the field of turbomachinery. It concerns a blade for the rotor blading of a turbomachine according to the preamble of claim 1 and a process for their preparation.

For the efficiency a turbomachine, e.g. a turbine or a compressor It is important that the game between the blade tips of the blades the rotor blading and the opposite boundary surface on the stator preferably is low. Through manufacturing tolerances and thermomechanical changes It can happen that the rotor blading with the stator collided.

In order to ensure a controlled rubbing in case of a collision of the rotor blading with the stator, the rotor blading is usually according to 1 designed. The on a rotor 20 fixed blade 10 which is part of a blade extending over the rotor circumference terminates in a blade tip 13 that is a stator 15 opposite. The blade 10 has in relation to the flow direction 21 of the medium flowing through the blading, a flow inlet edge 11 and a flow exit edge 12 , The blade 10 is with an abrasive layer 14 at the blade tip 13 Mistake. The abrasive layer 14 protects the rotor blading from wear and penetrates into the stator 15 one. On the stator 15 remains a groove 16 with a certain depth of penetration back, the part of the game S between the blade tip 13 and the bottom of the groove 16 is. The groove 16 has against the flow direction 21 an entry edge 17 and in the flow direction, a trailing edge 18 , These edges create stalls 19 and turbulence, which leads to a deterioration of the efficiency of the turbomachine.

Along the blade 10 , from the flow entry edge 11 to the flow outlet edge 12 , a pressure difference dp is distributed over the blade, which in 2 is shown schematically as a function of the location coordinate x. In the middle of the blade 10 (Section b of the dp (x) curve), where there is a large dp, has a loss of dp greatly affecting the efficiency of the blade.

In the area of the flow inlet edge 11 and the flow outlet edge 12 where there is a small dp (sections a and c of the dp (x) curve), dp loss has little effect on the efficiency of the blade. Thus, the game S must be between the blade tip 13 and the stator 15 in the middle region (b) of the blade are kept as small as possible. The game S between Stator 15 and the blade tip 13 at the flow inlet edge 11 and the flow outlet edge 12 On the other hand, it has little significance for the efficiency of the blade.

By the circumstances described above, namely the significant negative influence of Strömungsverwirbelungen at the entry and exit edges 17 . 18 the groove 16 and the low impact of the games on the flow inlet and outlet edges 11 . 12 on efficiency, it is desirable to avoid such entry and exit edges at the expense of increased clearance.

PRESENTATION THE INVENTION

It The object of the invention is to provide a blade for a turbomachine and to provide a method of producing the same by which the Disadvantages of known blades with regard to rubbing the Vane tips are avoided in the stator and in particular an improved efficiency of the turbomachine is achieved.

The The object is achieved by the entirety of the features of claims 1 and 14 solved. The essence of the invention is to form the blade tip in such a way that rubbed by the blade tip in the rotor groove their edges is formed expiring. This will break the flow and Whirling in the area of the grooved groove is reduced while at the same time the game between rotor blading and stator continues in the middle Area of the blade tip can be kept as low as possible.

Prefers this behavior is achieved by the blade tip a given cutting capacity which varies along the blade tip. Especially is the cutting ability to the flow entrance and exit edges minimally and reaches in the middle between the flow entry and exit edges Maximum. Very cheap is it when the cutting ability to the flow entrance and -austrittskanten goes to zero.

It has proven to be ideal when cutting power along the blade tip in dependence from the location coordinate follows a curve that the curve of the pressure difference at the blade tip in dependence from the location coordinate.

Especially just lets the desired Behave the blade when the cutting capacity of the Blade tip is given by an abrasive layer, with which the blade tip is provided, wherein the abrasive layer in particular from an abrasive material embedded in a suitable filling material consists. For example, cubic boron nitride has as abrasive substance proven.

The Variation in cutting ability is preferably by a variation in the abrasive layer caused selectively on the blade tip. To a vanishing cutting power at the edges of the blade tip achieve, the abrasive layer is preferably only in a middle Applied portion of the blade tip.

Basically the abrasive layer applied raised on the blade tip become. Very cheap However, it is when the selectively applied abrasive layer recesses fills in the blade tip; such that the length the shovel over the blade width is uniform.

Farther exists within the scope of the invention, the possibility of the thickness of the abrasive Layer and / or the density of the abrasive in the abrasive layer and / or the incorporation of the abrasive in the abrasive layer location-dependent embody.

A preferred embodiment of the method according to the invention is characterized in that, for coating the blade tip with the abrasive material, an abrasive substance is embedded in a suitable filling material and applied to the blade tip (FIG. 13 . 43 ) is applied, wherein preferably cubic boron nitride is used as the abrasive.

Especially It is advantageous if when coating the blade tip with the abrasive layer the abrasive layer depending on location so is varied, that a locally dependent varying cutting capacity of Blade tip results.

Especially The abrasive layer can be selective only in a specific section the blade tip are applied, the abrasive layer preferably only in a central portion of the blade tip is applied, and the blade tip at the flow inlet edge and flow outlet edge remains free.

In In this context, it is advantageous if in the particular section first, especially by milling or grinding, a recess introduced into the blade tip is, and then when the recess with the abrasive layer, in particular to the original one Height, is refilled. The recess is preferably trough-shaped and has a depth between 0.1 and 0.5 mm.

The location-dependent Variation of the abrasive layer may in particular by a variation one or more process parameters when applied along the Blade tip can be effected. If the abrasive layer by means of Laser deposition welding via driving the blade tip driving, with abrasive and filler at the same time as bundled Powder jet directed to the blade tip and with a high power laser locally melted, it lends itself to being used as a process parameter the travel speed or feed rate and / or the amount of powder per unit time and / or the laser power varies become.

Especially Cheap it is when the process parameters during the application of the abrasive layer be controlled fully automatically along the blade tip, wherein set the molten bath temperature along the blade tip so Make sure that it is in the middle section of the blade tip for extra efficient incorporation of the abrasive material, the melt bath temperature while of the order process is measured, and the measurement signal as a controlled variable for the controller the laser power is used.

SHORT EXPLANATION THE FIGURES

The Invention is intended below with reference to embodiments in connection closer to the drawing explained become. Show it

1 in a simplified representation of a blade of a rotor blading with the associated, rubbed into the stator groove according to the prior art;

2 the curve of the location-dependent variation of the pressure difference along a blade tip;

3 in one too 1 Comparative illustration of a blade with varying along the blade tip cutting capacity according to a preferred embodiment of the invention; and

4 a schematic perspective view of a method for producing a blade tip with locally varying cutting power according to a preferred embodiment of the invention.

WAYS TO PERFORM THE INVENTION

As already mentioned, a location-dependent pressure difference dp (x) arises along the blade 2 , In the middle of the blade (section b), where there is a large dp, a loss of dp has a major influence on the efficiency of the blade. In the area of the flow entry and exit edges, where there is a small dp (sections a and c), dp loss has little effect on the efficiency of the bucket. Thus, on the one hand the play between the blade tip and the stator in the central region of the blade must be kept as small as possible, while the game between the stator and the blade tip at the flow inlet and flow outlet edge has little significance for the efficiency of the blade.

It is therefore possible to permit wear of the blade tip (or a removal of the abrasive layer which protects against wear) in the region of the flow inlet and outlet edge, in order to cut the groove into the stator in an expiring manner. Such a configuration of blade and groove is in 3 reproduced: The on the rotor 20 fixed blade 10 with the flow inlet edge 11 and the flow exit edge 12 has at the blade tip 13 an abrasive layer 28 at the flow entry edge 23 and at the flow exit edge 24 disappears, ie selectively applied. As a result, an expiring groove 22 in the stator 15 rubbed in, their edges 25 ; 26 ungraded in the adjacent areas of the stator 15 pass. This will cause the stall 27 and turbulence in the groove 22 reduced. However, the clearance between the rotor blading and the stator will still be in the middle of the blade tip 13 kept as low as possible. Ideally, the cutting capability follows along the blade tip 13 a curve, that of the pressure difference dp from 2 equivalent.

• – Gute Anbindung zwischen abrasiver Spitze und Schaufelkörper
• – Hohes Schneidvermögen
• – Geringe Beeinflussung der mech. Eigenschaften und Geometrie der Schaufel
• – Wirtschaftlichkeit

One method of optimizing blade cutting capability is to coat blade tips with abrasive material. For this purpose, suitable abrasives, such as cubic boron nitride, embedded in a suitable filler material and on the blade tip 13 be applied. This can be done for example by galvanic coating, brazing of individual hard particles, or by laser. Important criteria for the selection of the material combination and the method are:

• - Good connection between abrasive tip and blade body
• - High cutting capacity
• - Low influence of the mech. Properties and geometry of the blade
• - Economics

In particular laser deposition welding (LMF: Laser Metal Forming) meets all these requirements. In this case, abrasive material and filler material are simultaneously directed as a bundled powder jet onto the blade tip and locally melted with a high-power laser, as described in US Pat 4 is shown. The blade tip 43 a blade 30 holding a shovel foot 29 , a platform 31 and an airfoil 32 has, with an abrasive layer 33 provided with a zone with a molten bath 34 over the blade tip 43 to be led. To produce the molten bath, a laser beam coating device is used 35 (Laser / powder head), in which one by means of a light guide 37 supplied laser beam 36 over a dichroic 45 ° level 40 focusing down on the blade tip is directed. Through a side supply line 41 becomes a powder-carrier gas mixture 42 in the area of the molten bath 34 fed. The temperature radiation of the molten bath 34 is through the head and the dichroic mirror 40 as an optical temperature signal 39 in an outgoing light guide 38 fed and passed to a pyrometer, where the temperature of the molten bath 34 can be determined. Such a technique including an associated control is described in detail in WO-A2-2004 / 090290.

With a suitable choice of process parameters, the blocky, sharp-edged shape of the abrasive particles is retained and there is a solid, crack-free connection between the blade and the abrasive tip. Particularly attractive in this method is the use of modern solid-state lasers (Nd-YAG, diode lasers, fiber lasers, disklasers, etc ...), since these energy sources can be spatially separated from the coating location by fiber coupling. By means of a flexible glass fiber as a light guide, the laser radiation can be guided, for example, to a CNC system or a robot with a special coaxial laser / powder head (see 4 ), which provides the flexibility needed for the automated coating of complex three-dimensional components.

The suitable process window is mainly due to the choice of material and determines the geometry of the blade to be coated. It will usually a uniform Desired coating thickness. Because the thickness of the job is also essential influenced by the process parameters, it is necessary to tailor these to the requirements.

In the present case, it is now proceeded to optimize the blade tip by targeted control of the coating at the same time also in terms of aerodynamics during operation. For this purpose, the cutting action by local change of Be stratification so that a rubbing behavior results, as in 2 and 3 is indicated.

• 1. Selektives Beschichten: Die Abrasivschicht wird nicht mehr entlang der ganzen Schaufel, sondern nur im mittleren Abschnitt b von 2 aufgebracht. Dadurch bekommt die Schaufel in diesem Bereich verbesserte Schneideigenschaften, während an Strömungsein- und -austrittskante 23 bzw. 24 ein Abrieb von Schaufelmaterial auftritt. Als Ergebnis erhält die entstehende Nut 22 im Stator 15 den in 3 dargestellten gewünschten Verlauf.
• 2. Selektives Beschichten mit Vorbereitung: Die Beschichtung erfolgt im wesentlichen wie in 1.) beschrieben. Es wird jedoch vor der Beschichtung in die Schaufelspitze eine flache muldenartige Ausnehmung bzw. Mulde (Tiefe zwischen 0.1 und 0.5 mm) in die zu beschichtende Schaufelendfläche gefräst oder geschliffen. Abrasivmaterial wird lediglich in der vorbearbeiteten Zone aufgebracht. Mit dieser Variante erhält die Schaufel eine einheitliche Länge und gleichzeitig die gewünschten, entlang der Länge variierenden Schneideigenschaften.
• 3. Variation der Prozessparameter entlang der Schaufelspitze: Hierzu eignet sich vor allem der Laserprozess aufgrund seiner guten Kontrollierbarkeit. Es können beim LMF-Prozess sowohl die Vorschubgeschwindigkeit zwischen Laser und Schaufel, als auch Pulvermenge, Laserleistung und Kombinationen dieser Parameter verändert werden. Wichtig ist dabei die Zeitkonstante des zu verändernden Parameters, die klein gegenüber den typischen Beschichtungszeiten sein muss, damit die Beeinflussung kontrolliert verläuft. Bei der geschilderten Methode mit pulverförmiger Materialzufuhr eignet sich deshalb insbesondere die Variation von Vorschubgeschwindigkeit und Laserleistung. So wird bei konstanter Förderrate und Laserleistung im Bereich der Strömungsein- und -austrittskante 23 bzw. 24 die Vorschubgeschwindigkeit erhöht, wodurch an diesen Orten weniger Abrasivmaterial aufgetragen wird und damit eine reduzierte Schneidwirkung bewirkt wird. Eine kontrollierte Veränderung der Vorschubgeschwindigkeit ist durch entsprechende Programmierung reproduzierbar erreichbar.
• 4. Automatische Regelung der Prozessparameter entlang der Schaufelspitze: Dazu wird durch on-line Bestimmung von Prozessparametern und Rückkopplung an die Lasersteuerung eine vollautomatische Regelung entlang der Schaufelspitze realisiert. Es wird ausgenützt, dass die Einbindung von Abrasivteilchen besonders effizient erfolgt, wenn die Temperatur der vom Laser aufgeschmolzenen Zone innerhalb festgelegter Grenzen liegt. Die Schmelzbadtemperatur wird nun entlang der Schaufel so vorgegeben, dass es im mittleren Bereich der Schaufel zur besonders effizienten Einbindung von Abrasivteilchen kommt. Die Schmelzbadtemperatur in der Wechselwirkungszone wird dabei während des Auftragsprozesses mit einem Pyrometer gemessen. Das optische Temperatursignal 39 aus dem Schmelzbad 34 wird dazu über einen Lichtleiter 38 zu einem Pyrometer übertragen und dient als Regelgrösse für die Steuerung der Laserleistung (siehe 4 und die Druckschrift WO-A2-2004/090290).

A targeted influencing of the cutting ability can be achieved by the following methods:

• 1. Selective coating: The abrasive layer is no longer along the entire blade, but only in the middle section b of 2 applied. This gives the blade in this area improved cutting properties, while at the flow inlet and outlet edge 23 respectively. 24 An abrasion of blade material occurs. The result is the resulting groove 22 in the stator 15 the in 3 shown desired course.
• 2. Selective coating with preparation: The coating is carried out essentially as described in 1.). However, a flat trough-like recess or depression (depth between 0.1 and 0.5 mm) is milled or ground into the blade end surface to be coated before coating into the blade tip. Abrasive material is applied only in the pre-machined zone. With this variant, the blade is given a uniform length and at the same time the desired cutting properties varying along the length.
• 3. Variation of the process parameters along the blade tip: This is especially the laser process due to its good controllability. In the LMF process, both the feed rate between the laser and the blade, as well as the amount of powder, laser power and combinations of these parameters can be changed. What is important here is the time constant of the parameter to be changed, which must be small compared to the typical coating times, so that the influence is controlled. In the described method with powdered material supply, therefore, in particular the variation of feed rate and laser power is suitable. Thus, at constant delivery rate and laser power in the area of the flow inlet and outlet edge 23 respectively. 24 increases the feed rate, whereby less abrasive material is applied at these locations and thus a reduced cutting action is effected. A controlled change in the feed rate can be reproducibly achieved by appropriate programming.
• 4. Automatic control of the process parameters along the blade tip: For this purpose, a fully automatic control along the blade tip is realized by on-line determination of process parameters and feedback to the laser control. It is exploited that the incorporation of abrasive particles is particularly efficient when the temperature of the melted by the laser zone within predetermined limits. The melt bath temperature is now set along the blade in such a way that particularly efficient incorporation of abrasive particles takes place in the middle region of the blade. The melt bath temperature in the interaction zone is measured during the application process with a pyrometer. The optical temperature signal 39 from the molten bath 34 This is done via a light guide 38 transferred to a pyrometer and serves as a controlled variable for the control of the laser power (see 4 and document WO-A2-2004 / 090290).

10

blade

11

Flow inlet edge

12

Flow outlet edge

13

blade tip

14

abrasive layer

15

stator

16 22

groove

17

leading edge

18

trailing edge

19

stall

20

rotor

21

flow direction

23

Flow inlet edge

24

Flow outlet edge

25 26

edge (Groove)

27

stall

28 33

abrasive layer

29

blade root

30

blade

31

platform

32

airfoil

34

melting bath

35

coater

36

laser beam

37, 38

optical fiber

39

optical temperature signal

40

dichroic mirror

41

supply line

42

Powder-carrier gas mixture

43

blade tip

S

game

a, b, c

section

dp

pressure difference

x

spatial coordinate (Blade tip)

Claims (25)

Blade ( 10 . 30 ) for the rotor blading of a turbomachine, which blade ( 10 . 30 ) a blade tip ( 13 . 43 ), which in the turbomachine is a stator ( 15 ) and when operating in the stator ( 15 ) a groove ( 22 ), characterized in that the blade tip ( 13 . 43 ) is formed such that from the blade tip ( 13 . 43 ) in the rotor ( 15 ) ne groove ( 22 ) at their edges ( 25 . 26 ) is designed to leak. Blade according to claim 1, characterized in that the blade tip has a predetermined cutting capability which is along the blade tip ( 13 . 43 ) varies. Blade according to Claim 2, characterized in that the cutting capacity at the flow inlet and outlet edges ( 23 . 24 ) is minimal and in the middle between the flow entry and exit edges ( 23 . 24 ) reaches a maximum. Blade according to claim 3, characterized in that the cutting capacity at the flow inlet and outlet edges ( 23 . 24 ) goes to zero. Blade according to claim 4, characterized in that the cutting capability along the blade tip ( 13 . 43 ) follows a curve corresponding to the curve of the pressure difference (dp) at the blade tip (x) as a function of the position coordinate (x) ( 13 . 43 ) as a function of the location coordinate (x). Blade according to one of claims 2 to 5, characterized in that the cutting capacity of the blade tip ( 13 . 43 ) through an abrasive layer ( 28 . 33 ) is specified, with which the blade tip ( 13 . 43 ) is provided. Blade according to claim 6, characterized in that the abrasive layer ( 28 . 33 ) consists of an embedded in a suitable filler abrasive. Blade according to claim 7, characterized in that that cubic boron nitride is used as abrasive. Blade according to one of Claims 2 to 8, characterized in that the variation in the cutting capacity is due to a variation in the abrasive layer ( 28 . 33 ) is caused. Blade according to claim 9, characterized in that the abrasive layer ( 28 . 33 ) on the blade tip ( 13 . 43 ) is selectively applied. Blade according to claim 10, characterized in that the abrasive layer ( 28 . 33 ) only in a middle section (b) of the blade tip ( 13 . 43 ) is applied. Blade according to claim 10 or 11, characterized in that the selectively applied abrasive layer ( 28 . 33 ) Recesses in the blade tip ( 13 43 ), such that the length of the blade is uniform across the blade width. Blade according to claim 9, characterized in that the thickness of the abrasive layer ( 28 . 33 ) and / or density of the abrasive in the abrasive layer ( 28 . 33 ) and / or the incorporation of the abrasive in the abrasive layer ( 28 . 33 ) is location-dependent. Method for producing a moving blade according to claim 1, characterized in that the blade tip ( 13 . 43 ) depending on location to form an abrasive layer ( 28 . 33 ) is coated with an abrasive material. A method according to claim 14, characterized in that for coating the blade tip ( 13 . 43 ) embedded with the abrasive material an abrasive in a suitable filler material and on the blade tip ( 13 . 43 ) is applied. Method according to claim 15, characterized in that that cubic boron nitride is used as abrasive. Method according to one of claims 14 to 16, characterized in that during coating of the blade tip ( 13 . 43 ) with the abrasive layer ( 28 . 33 ) the abrasive layer ( 28 . 33 ) is varied depending on the location so that a location-dependent varying cutting capacity of the blade tip ( 13 . 43 ). A method according to claim 17, characterized in that the abrasive layer ( 28 . 33 ) selectively only in a certain section (b) of the blade tip ( 13 . 43 ) is applied. A method according to claim 18, characterized in that the abrasive layer ( 28 . 33 ) only in a middle section (b) of the blade tip ( 13 . 43 ) is applied, and the blade tip ( 13 . 43 ) at the flow inlet edge ( 23 ) and flow outlet edge ( 24 ) remains free. A method according to claim 18 or 19, characterized in that in the specific section (b) first, in particular by milling or grinding, a recess in the blade tip ( 13 . 43 ) is introduced, and then that the recess with the abrasive layer ( 28 . 33 ), in particular to the original height. Method according to claim 20, characterized in that that the recess is trough-shaped and has a depth between 0.1 and 0.5 mm. A method according to claim 17, characterized in that the location-dependent variation of the abrasive layer ( 28 . 33 ) by a variation of a or more process parameters when applied along the blade tip ( 13 . 43 ) is effected. A method according to claim 22, characterized in that the abrasive layer ( 28 . 33 ) by laser deposition welding over the blade tip ( 13 . 43 ) is applied driving, wherein abrasive and filler material at the same time as a bundled powder jet on the blade tip ( 13 . 43 ) and locally melted with a high-power laser, and that the process speed or feed rate and / or the powder quantity per unit time and / or the laser power are varied as process parameters. A method according to claim 23, characterized in that the process parameters during the application of the abrasive layer ( 28 . 33 ) along the blade tip ( 13 . 43 ) are regulated fully automatically. A method according to claim 24, characterized in that the molten bath temperature along the blade tip ( 13 . 43 ) is predetermined so that in the middle section (b) of the blade tip ( 13 . 43 ) for the particularly efficient integration of the abrasive material, that the melt bath temperature during the order process is measured, and that the measurement signal is used as a controlled variable for the control of the laser power.