EP1345732A1

EP1345732A1 - Method for smoothing the surface of a gas turbine blade

Info

Publication number: EP1345732A1
Application number: EP01989541A
Authority: EP
Inventors: Andrea Bolz; Martin Feldhege
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2000-12-27
Filing date: 2001-11-29
Publication date: 2003-09-24
Anticipated expiration: 2021-11-29
Also published as: US20040097170A1; US7014533B2; EP1345732B1; DE50106828D1; EP1219389A1; WO2002051586A1; US7118464B2; US20060194526A1; JP2004516159A; CN1481293A

Abstract

The invention relates to a method for smoothing the surface of a gas turbine blade (1), especially having a McrAlY anticorrosion layer. The surface (14) of the gas turbine blade (1) is smoothed by means of a drag finish process, especially with a multiaxial movement. A first ring-shaped container (23) is filled with a liquid abrasive medium (27). A second container (25) which is arranged next to the first container (23) is filled with a second liquid abrasive medium (29). Said abrasive medium (27) contains emulsion-type abrasive bodies of a defined average size. The second abrasive medium (29) contains second emulsion-type abrasive bodies, the average size thereof being smaller than that of the abrasive bodies of the abrasive medium (27). A pivoting arm (31) is arranged between and above said containers (23, 25) and can be pivoted along a pivoting direction (32). A drag device (33) is arranged on the pivoting arm (31). Said drag device (33) leads a gas turbine blade on a carrier arm (41) through the abrasive medium (27). A first axis (35) for the movement of the gas turbine blade (1) is thus defined by a rotation of the drag device (33). A second axis (37) is defined by a tilting movement of the carrier arm (41). A third axis (39) for the movement of the gas turbine blade (1) is defined by a rotation of the carrier arm (41).

Description

description

Process for smoothing the surface of a gas turbine blade

The invention relates to a method for smoothing the surface of a gas turbine blade, in particular a gas turbine blade with an anti-corrosion layer.

DE-A-39 18 824 and US-A-5, 105, 525 show an iron soleplate which has a particularly scratch-resistant, well slidable and easy-to-clean surface. The soleplate is coated with a hard nickel alloy and ground and polished in a drag-grinding process.

US-A-4, 321, 310 describes a method for producing a coating on a gas turbine blade. The gas turbine blade has a base made of a cobalt-based or nickel-based superalloy. An adhesion promoter layer of the MCrAlY type is applied to this base material. M denotes a combination of the metals nickel and cobalt, for example. Cr stands for chrome and AI for aluminum and Y for yttrium. A ceramic layer made of zirconium oxide is applied to this adhesion promoter layer and has been grown in the shape of a stem, the stems being directed essentially perpendicular to the surface of the base body. Before the zirconium oxide layer serving as a thermal insulation layer is applied to the adhesion promoter layer, the adhesion promoter layer is polished until a surface roughness of about 1 μm is achieved.

From US-A-5, 683, 825 a method for applying a thermal barrier coating to a component of a gas turbine also emerges. A NiCrAlY adhesion promoter layer is applied to a base body by low-pressure plasma spraying. The surface of the adhesion promoter layer is polished so that it has a surface roughness of approximately 2 μm having. A ceramic thermal insulation layer with yttrium-stabilized zirconium oxide is applied to the adhesion promoter layer polished in this way by means of a vapor deposition process (PVD, Physical Vapor Deposition). In this case, the thermal insulation layer is preferably applied using the so-called electron beam PVD method. The thermal barrier coating can also be applied by means of plasma spraying.

US Pat. No. 5,498,484 likewise describes the application of a heat insulation layer to an adhesion promoter layer of a component of a gas turbine. The average surface roughness of the adhesion promoter layer is stated to be at least over 10 μm.

US-A-5, 645, 893 relates to a coated component with a base body made of a superalloy and with an adhesion promoter layer and a heat insulation layer. The adhesion promoter layer has a platinum aluminide and an adjoining thin oxide layer. The thin oxide layer has aluminum oxide. The thermal insulation layer, which is applied by means of the electron beam PVD process, adjoins this oxide layer. Here, zirconium oxide stabilized with yttrium is applied to the adhesion promoter layer. Before the adhesion promoter layer is applied, the surface of the base body is cleaned using a coarse sandblasting process. Aluminum oxide sand is used to remove the material from the base body.

The object of the invention is to provide a method for smoothing the surface of a gas turbine blade, which leads to a sufficiently smooth surface of the gas turbine blade in a particularly efficient and cost-effective manner.

According to the invention, this object is achieved by specifying a method for smoothing the surface of a gas turbine blade, in which the gas turbine blade is trailed with a ÜO) to r

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or concave shape of the suction or pressure side, there is a risk of inconsistent removal on the surface during drag grinding. This is avoided by the described superimposition of movements and thus, above all, maintaining the aerodynamically strictly specified surface shape. This ensures a uniform layer thickness of an applied corrosion protection layer.

D) The surface preferably has a roughness of Ra = 5 to 13 μm before smoothing and a roughness of Ra = 0.05 to 1 μm after smoothing.

E) A first smoothing in the grinding medium is preferably followed by a second smoothing in a second grinding medium, the final roughness that can be achieved by the second grinding medium being smaller than the final roughness that can be achieved by the first grinding medium. Such a repeated grinding process in different grinding media results in particularly high smoothing. In particular, exactly two grinding processes take place, and the second grinding process can be referred to as a polishing process. The grinding medium is e.g. a liquid medium, which can consist of water or an aqueous grinding emulsion and contains grinding wheels. The grinding media of the first grinding medium are preferably larger than the grinding media of the second grinding medium.

The statements according to items A) to E) can also be combined with one another in any way.

The invention is explained in more detail by way of example with reference to the drawing. Some of them show schematically and not to scale:

1 shows a gas turbine blade and 2 shows a grinding device and a method for surface treatment of a gas turbine blade.

The same reference symbols have the same meaning in the different figures.

FIG. 1 shows a gas turbine blade 1 with an airfoil 3, a platform 5 and a blade root 7. The airfoil 3 has a pressure side 9 and a suction side 11 which adjoin one another at an inlet edge 13 and a trailing edge 12. The airfoil 3, like the surface of the platform 5 facing the airfoil 3, is provided with a corrosion protection layer 15. The corrosion protection layer 15 is a metallic alloy of the MCrAlY class. Cooling ducts 17 open on the surface 14 of the airfoil 3.

In operation, the gas turbine blade 1 is exposed to a hot gas at a very high temperature. The corrosion protection layer 15 serves to protect against corrosion and oxidation by the hot gas. For use at particularly high temperatures, a ceramic thermal insulation layer 19 can also be applied to the corrosion protection layer 15. In this case, the corrosion protection layer 15 also serves as an adhesion promoter layer between the base body of the gas turbine blade 1 and the ceramic heat insulation layer 19. Before the application of such a ceramic heat insulation layer 19, the corrosion protection layer 15 must be smoothed. An efficient and inexpensive smoothing process is explained in more detail with reference to FIG. 2. To cool the gas turbine blade 1, a cooling medium 18, preferably cooling air, is led out of the cooling channels 17. The cooling medium 18 forms a protective cooling film on the surface 14.

FIG. 2 shows a grinding device 21. A liquid grinding medium 27 is filled in a first annular container 23. Arranged next to the first container 23 OO ω to t

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3 Q 3 μ- 3 Φ 0 μ-> Ω CO 3 sQ HO o to 3 3 DJ UA φ φ J 3 Φ 3 3 = et 3 Hi Q tc P. 3 3 3 Ω tr Φ ιP φ Φ rt Φ Hi 3 H ¹ μ- QA 3 3 rt 3 rt CO

CO 3 DJ o μ- μ- ιQ μ- tr co 3 co 3 s: φ μ- μ- tr rt Φ CO μ- tr CO

Ω Φ oo Φ CQ 3 Q DJ Φ UA φ C α Ω t rt Φ Ω CQ μ- 3 Φ QA QQ DJ: μ- tr μ- μ ¹ P. rt o C Φ 3 φ 3 Φ tr Φ o μ- iQ tr et P. O 3 Φ P. 3 HQ

H 3 μ- 3 sQ Φ DJ 3 rt 00 φ CQ H 3 et O 3 H ¹ rt Φ 3 CO rt 3 μ- NO: rt φ φ 3: 3 3 Φ μ- tr rt 00 on Ω φ rt DJ 3 3 3 Φ ω Ω H Φ s: εp CQ μ- DJ tr 3 t 3 cr er (- ^> A CD tr H3 13 rt ιP a 3 μ- O 3 "Eo to Φ Φ Φ

Hi 3 φ μ- μ- φ 3 Eo 0 A rt 3 13 DJ μ- Q. c sQ 3 N tr s; 3 Φ oo μ- • 3 co

3 DJ 3 IV) 3 rt 3 Eo 3 3 Hi Φ DJ: rt 3 o Φ 3 φ Φ Φ Q 3 ^" Ω rt 3 Ω

Φ H ^ 1 Φ DJ: sQ ιQ Ω 3: fi N ι Q 3 3 φ Ω ω φ 3 3 CD: tr Φ σ H tr

0 3 et P. CQ tr 3 μ- 3 Φ 3 tr 00 t μ- tr PC Φ - ¹ 3 CQ μ- ιQ Φ s: co φ P. 3 3 M Φ 3 Ω rt CD 3 μ- rt Φ co μ - φ

3 Φ 3 μ- Ω 3 Φ Φ Φ QA μ- P. DJ μ- μ- 3 O QA Hi 3- φ μ- 3 Φ μ- o μ-

3 3 3 tr Φ μ- 3 μ- μ- φ Φ 3 3 3 DJ DJ 3 = 3 tr Ω Φ 3 ι- 3 Hi p. DJ CO td 3 3 φ 3 3 3 φ Φ CO co tr Φ - 3 3 fr o 3 tO 3 φ Q φ rt CO 3 μ- 1 3 13 o Q. 1 0: 3 φ O 1 1 Φ Φ φ rt 13 Φ Φ 3 3 1 1 3 1 1 1 1

a polishing process takes place through which a particularly high smoothing can be achieved.

A large number of gas turbine blades 1 can of course also be arranged on the towing device 33, so that a high throughput of gas turbine blades 1 can be achieved.

Claims

claims

1. A method for smoothing the surface (14) of a gas turbine blade (1), in which the gas turbine blade (1) is dragged with a drag device (33) through an abrasive medium (27) along a drag direction (36).

2. The method according to claim 1, wherein the gas turbine blade (1) has an outer corrosion protection layer (15) applied by thermal spraying.

3. The method according to claim 2, wherein the corrosion protection layer (15) consists of an alloy of the class MCrAlX, where M stands for one or more elements of the group (iron, cobalt, nickel), Cr is chromium, Al aluminum and X stands for one or more elements of the group (scandium, hafnium, lanthanum, rare earths).

4. The method according to claim 1, in which on the surface (14) cooling channels (17) for a cooling medium (18) to be guided from the interior of the gas turbine blade (1) open.

5. The method of claim 1, wherein the gas turbine blade (1) is dragged in a multi-axis movement.

6. The method of claim 1, wherein the gas turbine blade (1) is rotated during towing.

7. The method according to claim 1, wherein the gas turbine blade (1) is towed on a circular path (43).

8. The method according to claim 1, wherein the gas turbine blade (1) is periodically tilted perpendicular to the towing direction (36).

9. The method of claim 1, wherein the surface (14) before smoothing a roughness of Ra = 5 to 13 microns and has a roughness of Ra = 0.05 to 1 micrometer after smoothing.

10. The method according to claim 1, wherein after a first smoothing in the abrasive medium (27), a second smoothing takes place in a second abrasive medium (29), the final roughness achievable by the second abrasive medium (29) being smaller than that by the abrasive medium ( 27) achievable final roughness.