U.S. patent application number 11/115371 was filed with the patent office on 2006-11-02 for arcuate nozzle segment and related method of manufacture.
This patent application is currently assigned to General Electric Company. Invention is credited to William Edward Adis, Robert James Bracken, Larry Duclos, David Orus Fitts, Sterling R. Hathaway, Ronald W. Korzun.
Application Number | 20060245923 11/115371 |
Document ID | / |
Family ID | 36994715 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060245923 |
Kind Code |
A1 |
Fitts; David Orus ; et
al. |
November 2, 2006 |
Arcuate nozzle segment and related method of manufacture
Abstract
A method of manufacturing reaction nozzles for a turbine
comprising (a) providing a piece of flat plate stock of
predetermined size and thickness; and (b) machining the piece of
flat plate stock to form a unitary, arcuate reaction nozzle segment
including at least two adjacent nozzle airfoils.
Inventors: |
Fitts; David Orus; (Ballston
Spa, NY) ; Bracken; Robert James; (Niskayuna, NY)
; Hathaway; Sterling R.; (Schenectady, NY) ;
Korzun; Ronald W.; (Clifton Park, NY) ; Duclos;
Larry; (Unity, ME) ; Adis; William Edward;
(Scotia, NY) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
36994715 |
Appl. No.: |
11/115371 |
Filed: |
April 27, 2005 |
Current U.S.
Class: |
415/209.2 |
Current CPC
Class: |
F01D 9/02 20130101; F01D
9/041 20130101; F01D 9/04 20130101 |
Class at
Publication: |
415/209.2 |
International
Class: |
F01D 9/00 20060101
F01D009/00 |
Claims
1. A method of manufacturing reaction nozzles for a turbine
comprising: (a) providing a piece of flat plate stock of
predetermined size and thickness; and (b) machining said piece of
flat plate stock to form a unitary, arcuate reaction nozzle segment
including at least two adjacent nozzle airfoils.
2. The method of claim 1 wherein said reaction nozzle segment also
includes a common tip shroud cover and a common dovetail hook at
opposite ends of, and spanning, said at least two adjacent nozzle
airfoils.
3. The method of claim 1 wherein said flat plate stock is comprised
of a stainless steel alloy.
4. The method of claim 3 wherein said stainless steel alloy
comprises a 400 Series stainless steel with 12% chromium.
5. The method of claim 1 wherein each of said arcuate segments
spans substantially 180.degree..
6. The method of claim 1 wherein each of said arcuate segments
spans substantially 90.degree..
7. A method of manufacturing reaction nozzles for a turbine
comprising: (a) providing a single piece of flat plate stock of
predetermined size and thickness; and (b) cutting said flat plate
stock to form a 360.degree. ring; (c) cutting said 360.degree. ring
into two or more arcuate segments; and (d) machining each of said
segments to include a plurality of nozzle airfoils.
8. The method of claim 7 wherein, during step (d), each segment
also includes an integral, common tip shroud cover and an integral,
common dovetail component.
9. The method of claim 7 wherein steps (b) and (c) are carried out
with wire EDM.
10. The method of claim 7 wherein, during step (c), said ring is
cut into two 180.degree. segments.
11. The method of claim 7 wherein, during step (c), said ring is
cut into four 90.degree. segments.
12. The method of claim 7 wherein said flat plat stock is comprised
of a stainless steel alloy.
13. The method of claim 12 wherein said stainless steel alloy
comprises a 400 Series stainless steel with 12% chromium.
14. A reaction nozzle component for a steam turbine comprising a
unitary arcuate segment formed to include a plurality of adjacent
nozzle airfoils.
15. The reaction nozzle component of claim 14 wherein said
plurality of nozzle airfoils extend radially between a common tip
shroud and a common dovetail component.
16. The reaction nozzle component of claim 14 wherein each segment
spans substantially 180.degree..
17. The reaction nozzle component of claim 14 wherein each segment
spans substantially 90.degree..
18. The reaction nozzle component of claim 14 wherein said segment
is composed of a stainless steel alloy.
19. The method of claim 18 wherein said stainless steel alloy
comprises a 400 Series stainless steel with 12% chromium.
20. The reaction nozzle of claim 15 wherein said common dovetail
component comprises a dovetail hook.
21. The reaction nozzle of claim 15 wherein said common dovetail
component comprises a centerline support mechanism for a
180.degree. arcuate segment.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a method of producing steam
turbine components and, specifically, dovetailed reaction nozzle
segments.
[0002] Current fixed reaction nozzle stages that are located
between rotating turbine stages (or wheels) are made up of
individual nozzles that are individually inserted within a dovetail
slot in a fixed nozzle carrier or turbine casing. The nozzles are
formed with integral dovetails at their radially outer ends and
integral tip shrouds at their radially inner ends. These nozzles
are designed to maintain tip shroud contact throughout operation by
incorporating appropriate cover or tip shroud interference along
with a pre-twisted cold airfoil portions. During assembly of such
nozzles, it has been difficult to confirm that the required cover
or tip shroud interference has been obtained. In addition, the
process of pre-twisting the nozzle airfoils at assembly causes the
airfoils to deviate from the "design" airfoil shape. This can
potentially reduce the efficiency of the airfoil.
BRIEF DESCRIPTION OF THE INVENTION
[0003] The present invention substantially eliminates many issues
relating to individually formed nozzle airfoils. In accordance with
an exemplary embodiment, a plurality of nozzles are manufactured by
machining from a single piece of flat plate stock. For example, in
one exemplary embodiment, a single solid donut-shaped ring is cut
from flat plate stock and then cut into two 180.degree. segments.
The cut ends of the segments may then be configured for temporary
attachment to a machining jig or the like, or the segments may be
temporarily joined together (by, e.g., bolts) on a jig and
subsequently machined to include integral shroud covers, airfoils
and dovetails. After machining, the two 180.degree. segments are
loaded into the nozzle carrier or casing dovetail in the usual
manner.
[0004] In another arrangement, four 90.degree. segments may be cut
from the solid ring and subsequently machined to each include 25%
of the required nozzles. Alternatively, arcuately shorter segments
may be machined to include as few as two integral nozzle airfoils,
thus still reducing the nozzle components by half.
[0005] In all cases, proper spacing between arcuate nozzle segments
can be maintained through the utilization of shims of appropriate
thickness placed between the segments and the carrier or casing
dovetail.
[0006] Accordingly, in one aspect, the invention relates to a
method of manufacturing reaction nozzles for a turbine comprising
(a) providing a piece of flat plate stock of predetermined size and
thickness; and (b) machining the piece of flat plate stock to form
a unitary, arcuate reaction nozzle segment including at least two
adjacent nozzle airfoils.
[0007] In another aspect, the invention relates to a method of
manufacturing reaction nozzles for a turbine comprising (a)
providing a single piece of flat plate stock of predetermined size
and thickness; and (b) cutting the flat plate stock to form a
360.degree. ring; (c) cutting the 360.degree. ring into two or more
arcuate segments; and (d) machining each of the segments to include
a plurality of nozzle airfoils.
[0008] In still another aspect, the invention relates to a reaction
nozzle component for a steam turbine comprising a unitary arcuate
segment formed to include a plurality of adjacent nozzle
airfoils.
[0009] The invention will now be described in connection with the
drawings identified below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a known steam turbine
reaction nozzle;
[0011] FIG. 2 is a perspective view of a unitary arcuate reaction
nozzle segment in accordance with an exemplary embodiment of this
invention;
[0012] FIG. 3 is a plan view of a piece of flat plate stock marked
for cutting a 360.degree. ring from the stock;
[0013] FIG. 4 is a plan view of the ring removed from the plate
stock of FIG. 3 and cut to form two 180.degree. arcuate
segments;
[0014] FIG. 5 is an exploded view of the two 180.degree. arcuate
segments of FIG. 4 modified for temporary attachment to a jig or to
each other for machining; and
[0015] FIG. 6 is a plan view of a solid ring cut into four
90.degree. segments for subsequent machining in accordance with
another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] With reference initially to FIG. 1, a conventional steam
turbine reaction nozzle 10 includes an airfoil 12 and an integral
radially inner tip shroud or cover 14. The radially outer end of
the nozzle is formed with a base 16 having a dovetail
configuration. Specifically, the base or dovetail 16 is provided
with a pair of flanges 18 and 20 projecting in both axially
upstream and downstream directions, defining recesses 22
therebetween. It will be appreciated that the nozzle casing or
carrier (not shown) is provided with generally correspondingly
shaped dovetail grooves which allow the nozzles 10 to be
individually loaded into the carrier or casing at a conventional
notched cut-out. Thus, each nozzle can be loaded into the dovetail
slot in the carrier until the entire row of nozzles has been
assembled. It will also be appreciated that the dovetail
arrangement may be reversed, with the dovetail groove component
formed in the nozzle and the dovetail hook component formed on the
carrier or casing.
[0017] FIG. 2 illustrates a unitary arcuate dovetail reaction
nozzle component or segment manufactured in accordance with an
exemplary embodiment of the invention. The segment 24 is machined
from a single piece of flat metal plate stock and includes a
plurality of adjacent airfoil portions (or simply "airfoils") 26
with an integral, common tip shroud or cover 28 at the radially
inner ends of the airfoils, and an integral, common dovetail hook
30 at the radially inner ends of the airfoils. As will be described
further below, the arcuate length of the segments may be varied as
desired to include as few as two airfoils or as many as 50% of the
airfoils required for a full 360.degree. reaction nozzle ring. In
one embodiment, the common dovetail comprises a centerline support
mechanism for a 180.degree. segment.
[0018] Turning to FIG. 3, a donut-shaped ring 36 is initially cut
from a single piece of flat plate stock 38, using any conventional
cutting technique, for example, wire electrical discharge machining
(EDM). With the ring 36 removed from the plate stock as shown in
FIG. 4, the ring is cut into two 180.degree. segments 40 and 42,
again using conventional cutting processes. The separated segments
40 and 42 may be provided with any suitable end flanges as shown at
44, 46 that permit the segments to be bolted to a machining jig in
alignment with each other, similar to their alignment when
assembled in upper and lower carrier or casing components.
Alternatively, the segments 38, 40 may be temporarily bolted
together and otherwise secured to the jig for machining. The
segments 38 and 40 are then machined to include the airfoils 26,
integral tip shrouds or tip covers 28, and dovetail hooks 30 as
shown in FIG. 2, but noting that FIG. 2 illustrates an arcuately
shorter segment. After machining, the segments 38 and 40 are
disassembled or removed from the jig and are ready for insertion
into the carrier or casing dovetail groove.
[0019] In an alternative arrangement as shown in FIG. 6, a solid
ring 48 may be cut from the flat plate stock into four individual
90.degree. segments 50, 52, 54 and 56 and machined to each include
25% of the required airfoils. In other embodiments, the arcuate
length of the airfoil segments may be altered as desired with each
segment including at least two airfoils.
[0020] In the exemplary embodiment, the flat plate stock 38 may be
high grade 400 Series stainless steel with 12% chromium, or other
suitable material.
[0021] In order to maintain proper circumferential spacing of the
airfoils, shims of appropriate thickness may be placed between the
segments at the dovetail. The segments may be held in place in the
dovetail via conventional radial end or axial shims which eliminate
the radial end or axial gap between the segment dovetail and the
dovetail groove in the casing or carrier.
[0022] By machining airfoils in this fashion, a number of issues
associated with the current individual reaction nozzle design can
be substantially eliminated or at least minimized including: [0023]
tip shroud interference and associated manufacturing and assembly
difficulties; [0024] untwist of shrouds and airfoils during
operation; [0025] axial clearance issues related to the piece-part
twist variation at assembly and during operation; [0026] assembling
individual nozzle/pins for each stage; [0027] the need to perform
in-process assembly checks such as twist, shingling and throat area
measurements; [0028] the need for standing assembled modal tests
and associated costs and scheduling impacts of each test; [0029]
ergonomic concerns related to assembling individual loading pins
for individual nozzles.
[0030] In addition to eliminating the issues above, the machined
segment concept in accordance with this invention also improves the
ability to service/repair rows relative to current practice;
creates a known/repeatable/unvarying boundary condition; reduces
the number of parts per stage; and insures that segments are
assembled in the correct location/direction.
[0031] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *