US 3694882 A
A turbine rotor blade path seal consists of a corrugated strip of sheet metal secured edgewise in an annular groove in the turbine cylinder or casing. The corrugated seal strip requires no edge rolling for the various diameters of the different stages of a multi-stage turbine. Thus, one pattern of a seal strip which is easily customized and assembled can be utilized for all stages of a turbine. The seal strip is caulked or interlocked in the groove at assembly by means of a special tool.
Claims available in
Description (OCR text may contain errors)
United States Patent [151 3,694,882 Desmond [4 1 Oct. 3, 1972  METHOD FOR PROVIDING A 940,802 11/1909 Green ..415/172 CORRUGATED SEAL IN AN ELASTIC 1,424,242 8/1922 Flanders ..415/174 FLUID MACHINE Inventor: John William Desmond, Media, Pa.
Assignees: Westinghouse Electric Corporation; Pittsburgh Electric Corporation, Pittsburgh, Pa.
Filed: Sept. 24, 1970 Appl. No.1 75,194
US. Cl. ..29/ 156.8 R, 29/DIG. 34, 277/ l .277/53, 277/96, 415/172, 415/174 Int. Cl. ..B2lk 3/04 Field of Search...29/l56.8 R, DIG. 34; 415/174, 415/171, 172; 277/53, 96,1
References Cited UNITED STATES PATENTS Comery ..277/53 Primary Examiner-John F. Campbell Assistant Examiner-Donald C. Reiley, Ill Attorney-A. T. Stratton, F. P. Lyle, F. Cristiano, Jr. and F. J. Baehr, Jr.
ABSTRACT A turbine rotor .blade path seal consists of a corrugated strip of sheet metal secured edgewise in an annular groove in the turbine cylinder or casing. The corrugated seal strip requires no edge rolling for the various diameters of the different stages of a multistage turbine. Thus, one pattern of a seal strip which is easily customized and assembled can be utilized for all stages of a turbine. The seal strip is caulked or interlocked in the groove at assembly by means of a special tool.
6 Claims, 7 Drawing Figures PATENTEBIIBT 3 I972 SHEET 2 OF 2 FIG. 3.
METHOD FOR PROVIDING A CORRUGATED SEAL IN AN ELASTIC FLUID MACHINE BACKGROUND or THE INVENTION This invention relates, generally, to elastic fluid machines and, more particularly, to rotor blade path seals for axial flow turbines.
In order to control leakage of the motive fluid past the rotor blades of a multi-stage axial flow turbine, it is desirable to provide a seal around each row of blades in the space between the outside diameter of the blades and the inside diameter of the turbine cylinder or casing. l-leretofore, it has been necessary to manufacture seal members having different curvatures for each stage, since the diameters are different for each stage of a multi-stage turbine. This invention provides a seal member which can be utilized for all stages of a turbine and does not require special forming equipment at the assembly area either in the shop or in the field.
SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a corrugated strip of sheet metal is secured edgewise in an annular groove in a turbine casing to provide an annular seal strip around a row of rotor blades. The corrugated strip is initially rectilinear, but easily conforms to the' curvature of the casing when it is installed and requires no edge rolling for the various diameters of different stages. The strip is secured in the cylinder by peening or caulking it in the groove by means of an assembly tool. The sealing action of the corrugated strip is accomplished by having the end of the strip in full contact with the bottom of the groove.
BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the nature of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawing, in which:
FIG. 1 is a view, in elevation, of a portion of an axial flow turbine having a rotor blade path seal constructed in accordance with principles of the invention;
FIG. 2 is a view, in section, taken along the line Il-II of FIG. 1;
FIG. 3 is a view, in plan, of a portion of a seal strip employed in FIG. 1;
FIG. 4 is a view, in elevation, of the seal strip shown in FIG. 3;
FIG. 5 is a view, partly in elevation and partly in section, showing the manner of utilizing an assembly tool to install the seal strip;
FIG. 6 is an enlarged detail view of the lower portion of the assembly tool and the seal strip; and
FIG. 7 is an isometric view showing a portion of the seal strip installed in the turbine cylinder.
DESCRIPTION OF THE PREFERRED EMBODIMENT may be secured to arcuate shroud segments 16 leaving an annular clearance space 18 between the casing 12 and the shroud 16 as shown in FIG. 2. v
In order to restrict the flow of the elastic motive fluid around the rotor blades, an annular seal 20 is provided in the space 18. As shown, the seal 20 is a corrugated strip of sheet metal secured edgewise, in an annular groove 22 provided in the casing 12 and encircling the annular row of rotor blades 14. A major portion of the seal strip extends beyond the casing 12 towards the rotor blades.
As shown more clearly in FIG. I, the corrugation impart flexibility tothe seal strip 20 and permit it to conform to the curvature of the casing 12 when the strip is inserted edgewise into the groove 22. Thus, no edge rolling of the seal strip is required for the various diameters of different stages in a multi-stage turbine. The corrugations permit edge forming during normal assembly without using edge rolling equipment.
. In accordance with the usual practice, the turbine casing 12 is divided into an upper half and a lower half bolted together at horizontal joints 24. Thus, the seal 20 may be made in two halves, each half being of suff cient length to reach from one horizontal joint to the other when installed in the groove 22.
As shown more clearly in FIG. 2, the seal 20 'is disposed transversely of the direction of flow of the" As shown more clearly in FIG. 3, the height of the corrugations of the seal strip 20 is such that the strip fits snugly into the groove 22. Each ridge has a flat surface 28 which contacts a side of the groove'22 and a ligament 29 disposed between the flat surfaces 28 at an oblique angle with respect to the surfaces 28, to allow the corrugated strip todeform to accommodate the insertion of the corrugated strip tightly inthe groove 22, thereby preventing leakage of the motive fluid through the groove.
The seal strip 20 may be installed and secured in the groove 22 by means of an assembly tool 30 shown in FIG. 5. The tool 30 comprises a peening or caulking member 32 movably disposed inside an inner sleeve 34 which is movably disposed inside an outer sleeve 36, a compression spring 38 surrounding the sleeve 34 between the lower end of the sleeve 36 and a flange 40 on the sleeve 34, and a wedge 42 disposed at the lower end of the caulking member 32. The members of the tool are retained together by means of a pin 44 secured in the sleeve 36 and extending through elongated slots 46 and 48 in the sleeve 34 and the member 32, respectively.
As shown more clearly in FIG. 6, the wedge 42 is movably attached to the caulking member 32 by two plates 50 secured to opposite sides of the wedge and a pin 52 secured in the member 32 and extending into openings 54 in the plates 50 which extend a short distance along opposite sides of the member 32. The.
openings 54 are of such a size that limited movement of the member 32 relative to the wedge 42 is permitted.
As shown in FIGS. 5 and 6, when the tool 30 is held on the corrugated strip 20 with the member 32 extending between corrugations and a cutting projection 56 at the lower end of the member 32 facing a flat surface 28 of the strip and pressure is applied on the sleeve 36 to compress the spring 38, the upper end of the member 32 may be struck with a hammer to cause the projection 56 to cut and force a projection 58 from the flat surface 28 of the strip into a sidewall of the groove 22 in the cylinder 12. When the upper end of the member 32 is struck with the hammer the bottom end strikes the sloping surface 60 of the wedge 42, thereby causing the projection 56 to drive the projection 58 into the side wall of the groove. During this caulking operation the pressure of the spring 38 on the sleeve 34 is held on the corrugated strip 20 assures that the strip is fully inserted into the groove 22. When pressure on the sleeve 36 is released, the tool 30 can be withdrawn and then utilized to caulk or interlock the seal strip at another point as shown in FIG. 7. The seal strip may be interlocked at any desired number of points.
A commercial benefit of this invention is that the seal strip can be replaced in the turbine in the field quickly and economically, thereby avoiding the delay required to return the turbine to the factory. The flexible corrugated seal permits the seal strip sections to be shipped and handled conveniently as straight, i.e., rectilinear, sections.
From the foregoing description it is apparent that the invention provides a turbine rotor blade path seal member which can be economically manufactured and installed. The seal member can be utilized for all stages of a multi-stage turbine and does not require special forming equipment at the assembly area.
I claim as my invention:
1. A method for providing an annular strip between rotating and stationary portions of an elastic fluid machine comprising the steps of:
forming an annular groove having generally radially extending sidewalls in one of said portions of said machine,
inserting a corrugated strip of sheet material edgewise into said groove with said strip extending beyond said groove,
deforming the strip to an annular shape,
shearing and deforming a portion of said strip, and
driving said sheared and deformed portion of said strip into at least one of said sidewalls of said groove thereby securely fastening said strip in said groove.
2. The method as set forth in claim 1, wherein the steps of shearing and deforming the strip and driving the sheared portion into at least one sidewall of the groove are performed simultaneously utilizing an assembling tool.
3. The method as set forth in claim 1 and further comprising the steps of pressing the corrugated strip against the bottom of the groove, saidpressing step being performed prior to the step of shearing and deforming.
4. The method as set forth in claim 1 and further comprising the step of forming the corrugated strip with flat surfaces which engage the sides of the groove and shearing and deforming the strip in a plurality of locations disposed within the flat surfaces.
5. The method as set forth in claim 4 and further com risin e ste of formin the c rru ated stri so as t8 hav l igameihts betweet the flat surfaces and disposing said ligaments at an oblique angle with respect to the flat surfaces so as to accommodate the step of inserting the corrugated strip into the groove.
6. A method for providing an annular seal between rotating and stationary portions of an elastic fluid machine comprising the steps of:
forming an annular seal having generally radially extending sidwalls in one of said portions of said machine,
inserting a rectilinear corrugated strip of sheet material edgewise in said groove with said strip extending beyond said groove,
progressively deforming the strip to an annular shape,
shearing and deforming a portion of said strip, and
driving the shearing and deformed portion of said strip into at least one of said sidewalls of said groove, thereby securely fastening said strip in said groove.