U.S. patent application number 11/552296 was filed with the patent office on 2007-06-21 for oxidation protected blade and method of manufacturing.
Invention is credited to Alan Bouthillier, Alan Juneau, Danlel Lecuyer.
Application Number | 20070141965 11/552296 |
Document ID | / |
Family ID | 37449866 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070141965 |
Kind Code |
A1 |
Juneau; Alan ; et
al. |
June 21, 2007 |
OXIDATION PROTECTED BLADE AND METHOD OF MANUFACTURING
Abstract
The surface of a gas turbine blade is machined with a
material-removing tool and simultaneously, an anti-oxidation
coating is deposited on the surface using eletrospark
deposition.
Inventors: |
Juneau; Alan; (Mount-Royal,
CA) ; Lecuyer; Danlel; (Verdun, CA) ;
Bouthillier; Alan; (Ste-Julie, CA) |
Correspondence
Address: |
OGILVY RENAULT LLP (PWC)
1981 MCGILL COLLEGE AVENUE
SUITE 1600
MONTREAL
QC
H3A 2Y3
CA
|
Family ID: |
37449866 |
Appl. No.: |
11/552296 |
Filed: |
October 24, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11231829 |
Sep 22, 2005 |
7140952 |
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11552296 |
Oct 24, 2006 |
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Current U.S.
Class: |
451/54 |
Current CPC
Class: |
F05D 2230/31 20130101;
F05D 2230/90 20130101; F05D 2230/10 20130101; C23C 26/00 20130101;
F01D 5/288 20130101; Y10T 29/49316 20150115; F05D 2230/80 20130101;
F05D 2300/611 20130101 |
Class at
Publication: |
451/054 |
International
Class: |
B24B 1/00 20060101
B24B001/00 |
Claims
1. A method of providing oxidation protection to an airfoil blade
of a gas turbine engine, the method comprising the steps of:
providing the airfoil blade with a first anti-oxidation coating
applied to an outer surface thereof; adjusting a tip clearance
dimension of the airfoil blade by grinding a tip portion of the
blade, thereby at least partially removing a layer; and then
depositing a second oxidation-resistant coating to at least said
ground tip portion using electrospark deposition.
2. The method of claim 1 wherein the oxidation-resistant coating
material applied by electrospark deposition is MCrAlY.
3. The method of claim 1 wherein the tip portion includes an edge
of a pressure side of the blade.
4. The method of claim 1 wherein the steps of grinding and
electrospark deposition are repeated, in sequence, at least
once.
5. The method of claim 4 wherein said repeated grinding step
partially removes a coating layer previously deposited by said
electrospark deposition.
6. The method of claim 1 wherein the step of electrospark
deposition includes applying said second coating in at least some
areas where said first coating remains.
7. The method of claim 1 further comprising providing additional
second coating material at a gap at the tip portion of the
blade.
8. The method of claim 1 further comprising superposing multiple
layers of said second coating on top of one another.
9. The method of claim 1 further comprising providing a recessed
portion of the tip portion with additional layers of said second
coating relative to non-recessed portions of the blade.
10. A method of providing oxidation protection to a coated airfoil
blade of a gas turbine engine, the method comprising the steps of:
removing at least a portion of a coating from a tip portion of the
blade; and then depositing an oxidation-resistant coating to said
tip portion using electrospark deposition.
11. The method of claim 10 wherein a portion of a parent material
of the blade is also removed with the at least a portion of the
coating.
12. The method of claim 11 wherein the parent material and coating
are removed to adjust a tip clearance height of the blade.
13. The method of claim 10 wherein the step of removing is
performed by grinding.
14. The method of claim 10 wherein the oxidation-resistant coating
is MCrAlY.
15. The method of claim 10 wherein the oxidation-resistant coating
applied to at least an edge of the tip portion adjacent a pressure
side of blade.
Description
CROSS-REFERENCE TO RELATED U.S. APPLICATION
[0001] The present application is a continuation of U.S. patent
application Ser. No. 11/231,829 filed Sep. 24, 2005, which
application is hereby incorporated by reference.
TECHNICAL FIELD
[0002] The field of invention relates generally to the protection
of blades in a gas turbine engine and, more particularly, to a
blade provided with an oxidation protection layer and a method of
manufacturing the same.
BACKGROUND OF THE ART
[0003] In small gas turbine engines, the shrouds located around the
turbine blades are generally not provided with a layer of abradable
material, as is the case for some larger engines. Reasons for this
include the facts that large engines may have more carcass
distortions and more misalignment between centerlines of the rotor
and shrouds. A distortion or misalignment may cause a localized rub
between a shroud segment and all blades. Without an abradable
system, this may leave a relatively large gap around the periphery
of the rotor and reduce the efficiency of the engine. Smaller
engines take advantage of having less carcass distortions and
misalignments by designing to have tighter tip clearances. One
method of achieving tight tip clearances on smaller engines is to
machine blades to their final dimensions so that the designed tip
clearance is achieved even without a running-in period.
[0004] Whenever parts are machined to their final dimension, for
instance using a grinder, some material is removed. Since the parts
are coated with one or more protective layers before the final
machining process, removing more material than the thickness of the
protective layer or layers will leave the base material exposed.
The exposed areas will then be prone to oxidation. Oxidation is
particularly severe at the edge of the pressure side of blades This
ultimately results in a premature wear of the blades.
[0005] Accordingly, there is a need to provide an improved way of
protecting from oxidation the surfaces of the blades that are
machined because their base material is exposed once machined to
their final dimension.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention provides a method of
providing oxidation protection to an airfoil blade of a gas turbine
engine, the method comprising the steps of: providing the airfoil
blade with a first anti-oxidation coating applied to an outer
surface thereof, adjusting a tip clearance dimension of the airfoil
blade by grinding a tip portion of the blade, thereby at least
partially removing a layer; and then depositing a second
oxidation-resistant coating to at least said ground tip portion
using electrospark deposition.
[0007] In another aspect, the present invention provides a method
of providing oxidation protection to a coated airfoil blade of a
gas turbine engine, the method comprising the steps of: removing at
least a portion of a coating from a tip portion of the blade; and
then depositing an oxidation-resistant coating to said tip portion
using electrospark deposition.
[0008] Further details of these and other aspects of the present
invention will be apparent from the detailed description and
accompanying figures.
DESCRIPTION OF THE DRAWINGS
[0009] Reference is now made to the accompanying figures depicting
aspects of the present invention, in which:
[0010] FIG. 1 is a schematic view of a gas turbine engine showing
an example of a possible environment in which the turbine blades
are used; and
[0011] FIG. 2 is a schematic view of the manufacturing process, in
accordance with a preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] FIG. 1 illustrates a gas turbine engine 10 of a type
preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a multistage compressor 14 for
pressurizing the air, a combustor 16 in which the compressed air is
mixed with fuel and ignited for generating an annular stream of hot
combustion gases, and a turbine section 18 for extracting energy
from the combustion gases. This figure shows one possible
environment in which blades with oxidation protection can be used.
It should be noted at this point that the invention is equally
applicable to other kinds of gas turbine engines, such as turbo
shafts or turbo props.
[0013] FIG. 2 schematically shows a surface of a blade 20 being
manufactured in accordance with the present invention. It shows
that material is removed from the surface using a material-removing
tool, for instance a grinder 22. If the grinder 22 removes more
material than the thickness of the original anti-oxidation layer 24
of the blade 20, the base material will be exposed. However, at the
same time, a very thin layer of anti-oxidation coating 26 is
applied using an electrospark applicator 28 to solve that
problem.
[0014] Electrospark deposition (ESD) is a pulsed micro-welding
process. Based on short duration, high current pulses, ESD imparts
a low heat input to the base material, resulting in little or even
no modification of the substrate microstructure. The base material
remains near to ambient temperature so that thermal distortion,
shrinkage and high residual stresses are avoided. The precision of
the machining is thus intact. An example of a corrosion resistant
material is MCrAlY.
[0015] The grinder 22 and the applicator 28 can be mounted on the
same frame (not shown), which will preserve the datum line and
increase the precision of the machining. The frame can be movable
with reference to the blade 20, or vice-versa. Another possibility
is to mount the blade 20 on a rotating support while the grinder 22
and the applicator 28 are fixed. This rotating support can be a
rotor disk.
[0016] The combined machining and eletrospark deposition can be
repeated one or more times for each surface until the final
dimension is obtained. The machining may, in that case, even remove
some of the anti-oxidation coating 26 previously laid by the ESD as
part of the material being removed. Likewise, the anti-oxidation
coating 26 can be applied on a partially-removed anti-oxidation
layer 24.
[0017] The ESD tool may be designed to have a conformal shape to
the blade 20 or its tip. This way, it is possible to apply the
coating on the whole surface simultaneously. Yet, the ESD tool may
be a rotating tool mounted on a wheel-like support.
[0018] Overall, the apparatus and the method of the present
invention allow blades of gas turbine engines to have tight tip
clearances, which is particularly useful in the case of small gas
turbine engines. It allows the blades to have these tight tip
clearances without leaving the base surface with no protection,
thus prone to oxidation.
[0019] If desired, the gap at the tip of a blade 20 may receive
additional coating using the electrospark deposition. It is
possible to superpose multiple layers of anti-oxidation coating 26
to increase the protection. Some areas may still be prone to wear
with only one layer and accordingly, the additional thickness of
many layers of anti-oxidation coating 26 will prevent the base
material from being uncovered.
[0020] Recessed portions of blades can receive more anti-oxidation
coating than non-recessed portions without affecting the tip
clearance.
[0021] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. For example, the material-removing tool can be
different than a grinder and may include any other equivalent
machining device, such as a milling cutter. The coating material is
not limited to MCrAlY and other anti-oxidation coatings can be
used, as apparent to a person skilled in the art. The process being
disclosed herein is not limited to new blades and can be used for
refurbished blades. Still other modifications which fall within the
scope of the present invention will be apparent to those skilled in
the art, in light of a review of this disclosure, and such
modifications are intended to fall within the appended claims.
* * * * *