Method and device for polishing the surface of a gas turbine blade

Abstract

The invention relates to a method and device for polishing the surface of a gas turbine blade. According to the invention, a metallic anticorrosive layer is polished by using a stream of dry ice whereby preventing the surface from becoming contaminated and obtaining cost advantages.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is the US National Stage of International Application No. PCT / EP02 / 12520, filed Nov. 8, 2002 and claims the benefit thereof. The International Application claims the benefits of German application No. 01128915.4 EP filed Dec. 5, 2001, both of the applications are incorporated by reference herein in their entirety.FIELD OF THE INVENTION [0002] The invention is in the field of gas turbine blades or vanes and involves the application or refurbishment of a protective layer or protective layer system on gas turbine blades or vanes. BACKGROUND OF THE INVENTION [0003] Protective layer systems on gas turbine blades or vanes are shown, for example, in U.S. Pat. No. 4,321,310, U.S. Pat. No. 4,676,994 or U.S. Pat. No. 5,238,752. Gas turbine blades and vanes are exposed to very high temperatures. To enable them to have the required resistance to high temperatures, therefore, they are made from materials which are able to withstand ...

AI Technical Summary

Benefits of technology

[0017] Removal by means of dry ice avoids contamination by foreign substances. Moreover, the metallic base body of the gas turbine blade or vane is not adversely affected, and moreover no material whatsoever is removed from the high-temperature corrosion-resistant layer.

[0018] Therefore, the surface of the gas turbine blade or vane can be smoothed or deburred easily and with a high quality, or may also have the entire ceramic thermal barrier coating removed from it.

[0019] Smoothing by means of a dry ice jet on the one hand provides the time and cost benefit of a sand-blasting process over, for example, a grinding process. On the other hand, however, the main drawback of a conventional sand-blasting process, namely contamination of the blade or vane surface with particles of the sand jet, is avoided. The dry ice particles sublime immediately and without leaving residues on contact, with the result that there is no accumulation or chemical reaction of any type. Furthermore, no blasting residues remain to be disposed of.

[0024] It is preferable for the smoothing to be carried out in fully automated fashion. A multiaxis holder for the gas turbine blade or vane or multiaxis guidance of the dry ice jet makes it possible to reach any region of the surface which is to be smoothed.

[0027] The invention also provides an apparatus for removing ceramic material of a ceramic thermal barrier coating on the surface of a gas turbine blade or vane, having a holder for the gas turbine blade or vane and having a nozzle for emitting a dry ice jet, and having a multi-axis manipulation device for moving the dry ice jet relative to the gas turbine blade or vane in such a manner that completely automated removal of the ceramic material of the gas turbine blade or vane becomes possible.

Problems solved by technology

Consequently, it has a relatively high roughness, which is undesirable.

The grinding process is not only time-consuming but also entails the risk of prior uncontrolled removal of material at exposed edges.

The known sand-blasting processes in particular have the drawback that solid particles of the jet may become included in the protective layer, thereby unacceptably reducing the surface quality.

Drilling by means of a laser beam offers time and cost benefits but often leads to the formation of burrs and contaminations formed from fused-on or remelted particles on account of the action of heat.

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