US1187450A - Steam-turbine. - Google Patents

Description

c. E. SEARCH.

STEAM TURBINE.

APPLICATION FILED FEB. 9, |914.

Patented June 13, 1916.

ZfSHEETS-SHEET I.

C. E. SEARCH.l

STEAM TURBINE.

APPLICATION man m1. 9, 1914.

Patented June 13, 1916.y

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFTCE.

CHARLES EDWIN SEARCH, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-CHALMER MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

STEAM-TURBINE.

Patented J une 13, 1916.

Application filed February 9, 1914. Serial-No. 818,156.

To all whom t may concern.' f

Be it known that I, CHARLES EDWIN SEARCH, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, has invented a certain new and useful Improvement in Steam-Turbines, of which the following is a specification.

This invention relates to steam turbines and more particularly to a method of securing the shroud to the blade ends and ofA tudinally corrugated shroud having formed thereon means for properly spacing and angling single-surfaced blade ends, the shroud being secured to the blade ends by fusion of metal.

Another object is to provide a simple method of forming the means for positioning the blade ends by forming positioning surfaces on the corrugation in such a way as to coact with the working faces of the blades longitudinally to a 4considerable extent.

The expression single-surfaced end as used herein is intended to apply to a blade end which is free of any projection or recess abruptly interrupting the continuity of the end surface of the blade. The expression therefore includes blade ends having surfaces which are either plane or curved,

these surfaces being either perpendicular or oblique relative to the edges ofthe blade.

It has heretofore' been proposed to fasten a shroud to the ends of turbine blades by rforming tenons at the ends of the blades considerable blade stock is wasted in forming the tenons or projections at theblade ends. Another objection to the riveted-over fastening is that because of the localfastening of the shroud to the bla-de ends, the shroud base must of necessity be made considerably heavier', thus increasing the stress on the fasteners due to centrifugal force and also increasing the cost of construction. With the device of the present invention these objections are eliminated. In addition, the corrugation of the shroud of the present invention combined with its fastening to the blade ends by fusion of metal makes the shroud in the completed structure very much stiffer and stronger.

A clear conception of several embodiments of the invention may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views.

Figure 1 is a plan View of a fragment of one form of shroud attached to a plurality of blades. Fig. 2 is a transverse vertical section through fragments of the shroud and blades disclosed in Fig. l, the section being taken along the line II-II of Fig. 1 looking in the direction of the arrow. Fig. 3 is a transverse vertical section through the shroud disclosed in Fig. l, showing the same attached to a fragment of a blade, the section being taken at a portion of the shroud between successive blades. verse vertical section through the shroud disclosed in Fig. l, showing the same attached to a fragment lof a blade, the section being taken at one o'f the working faces of the blade. Fig. 5 is a plan View of a fragment of another form of shroud attached to a plurality of blades. Fig.V 6 is a transverse vertical section through fragments of the shroud and blades disclosed in Fig. 5, the section being taken along the line VI--VI of Fig. 5. Fig. 7 is a transverse vertical section through the shrouddisclosed in Fig.. 5, showing the same, attached to a fragment of a blade, the section being taken at a portion of the shroud between successive blades. Fig. 8v is a transverse vertical section through the shroud disclosed in Fig. 5, showing the same attached to a fragment of l a blade, the section being taken at one of the working faces of the blade. Fig.

Fig. 4 is a trans- 9 is a plan View of a fragment of still an- 110 section being taken at a portion'of the shroud between successive blades. Fig. 12 is a transverse vertical section through the shroud disclosed in Fig. 9, showing the samel attached to a fragment of a blade, the

section being taken at one of the working faces of the blade. Fig. 13fis a transverse vertical section through'fragments of still another form of shroud and blades, the section being taken along the line XIIIe-XIII of Fig. 14. Fig. 14 is a transverse sectional view through 'a plurality of blades having attached thereto a fragment of the shroud as disclosed in Fig. 13, the section being Ataken near the blade ends.` Fig. 15 is a transverse vertical section through the shroud disclosed in Fig. 13, showing the same attached to a fragment of a blade, the section being taken at a portion of the shroud between successive blades. Fig. 16

is a transverse vertical section through the. shrouddisclosedin Fig. 13, showing thesame attached to a fragment of blades, the section being taken at one of the working faces of the blade. Fig. 17 is a transverse vertical section through fragments of still another form of shroud and blades, the section being taken lalong the line XVII-XVII of Fig. 18. Fig. 18 is a transverse sectional View through a plurality of blades having attached thereto. a fragment of the shroud as disclosed in Fig. 13, the section being taken near the blade ends. Fig. 19 is a transverse vertical section through the shroud disclosed in Fig. 17 showing the same attached to a fragment of a blade, the section being taken at a portion of the shroud between successive blades. Fig. 20 is a transverse vertical section through -the shroud disclosed in Fig. 17, showing the same'attached to a fragment of a blade, the section being taken at one of the working faces of the blade.

While the figures-of the drawing in each case disclose rotor or movable blading of a parallel How turbine of the Parsons type,"it is to be understood that the inventionfis equally applicable to stator or stationary' blading, as well as to other types of turbines.' The shroud in each case is made very light and is provided with parallel side walls for the purpose of facilitating machin- A- ing of the assembled structure, in order to secure a close lit between the shroud and 1 the stationary turbine casing. This invention is not, however, limited to .channel shaped shrouds. The blades. 1 in eachpof the disclosures have single-surfaced ends and are secured to suitable foundation segments in the usual manner.

Referring specifically to Figs. 1, 2, 3 and 4, the channel shaped shroud 2 is formed of stock having a continuous longitudinal corrugation or projection 7 near the mid portion thereof. This` corrugation or pro= jection 7 may be formed by distortion of shroud stock normally having either a curved or a plane base portion, but is preferably formed during the manufacture of the shroud stock, either by rolling or drawing, and forms a continuous longitudinal arch on the shroud which greatly enhances the stiffness ofthe shroud stock. In order `to provide means for positioning, that is, properly spacing and angling the blade ends, the shroud 2 is provided with' a series of punched holes 3 passing' transversely therethrough at the corrugation or projection 7 to form recesses in the projection. The surfaces of two opposite walls of the holes 3 conform to the contour of the working faces of the blades, and coact therewith longitudinally to a considerable extent. The holes 3 are formed by means of a die which is of a projected width equal to the maximum width of the projection 7. -After the recesses in the projection 7 have been formed by the formation of the holes 3, the shroud 2 is applied to the single-surfaced blade ends .and is united thereto by fusion of metal, either by soldering, brazing, welding or in any other way. In the drawings the union has been made by brazing, theadded fusible material being represented as a fillet 5 adjacent the ends of the blades.

Referring specifically to Figs. 5, v6, and 8, the channel shaped shroud 12 is formed of stock having a continuous longitudinal corrugation or projection 17 vnear the mid portion thereof, this corrugation being formed as'" indicated hereinabove. The

means for positioning, that is, properlyl Aof the blades 1 and coacting therewith longitudinally to' a considerable extent. After 4 vthe recesses have been formed in the projections 17, the shroud 12 is applied to the single-surfaced blade ends and is united therewith by fusion of metal as lindicated hereinabove. Innthe drawing this union .has been indicated as having been accomplished by brazing, the added fusible material beingv represented by fillets 15 adjacent the ends of the blades 1. The shearing of the metal of the projection 17 is not, however, to be considered as perforating, as this term is intended to apply only to the form of shroud disclosed in Figs. l to 4 inclusive.

Referring specifically to Figs. 9, 10', 11 and 12, the channel shaped shroud 22 is formed of stock which primarily has a continuous longitudinal corrugation or projection 27 near the mid portion thereof. This corrugation is again preferably `formed as indicated hereinabove. The means for positioning the blade ends consists of a series of transverse recesses in the projection 27, these recesses being formed by forcing back the portions 23 of the projection 27 so as to bring the same into alinement with the normal base of the shroud 22. The recesses are thus formed with opposite walls having surfaces conforming to the contour of the working faces of the blades 1 and coacting therewith longitudinally to a considerable extent, but not to the same degree as in thev forms hereinabove described. After the recesses have been formed, the shroud 22- is applied to the single-surfaced blade ends and is united thereto by fusion of metal, the added fusible material being represented as fillets 25 adjacent the ends of the blades 1.

.Referring specifically to Figs. 13, 14, 15 and 1G, the channel shaped shroud 32 is formed of stock having a pair of substantially parallel continuous longitudinal' pro- `jections 37 extending along the blade side thereof. These projections 37 are preferably formed during the manufacture of the shroud stock either by rolling or drawing the shroud strip with the continuous projections thereon. The means for properly positioning the blade ends are produced by forming a series of recesses in the projections 37. The recesses are formed with opposite walls having surfaces conforming to the contour of the working faces of the blades 1 and coacting therewith longitudinally to a considerable extent. The recesses in the projections 37 are formed by forcing back the metal of the projections wherever it is desired to have a recess, permitting the metal so displaced from the projections to build up in the form of plow, spread-out mounds or projections 33 on the outer side of the shroud base. After the recesses have been properly formed in the projections 37, the shroud 32 is applied to the single-surfaced ends of the-blades and is united thereto by fusion of metal as indicated hereinabove. vThis construction has the advantage that thebacking die used in forming the recesses does not necessarily have to be receded in order to permit feeding forward of the shroud stock which is secured to an intermittently fed support. In this case thel shroud stoel* will spring sufliciently to permit the dislocation of the mound from the l stationary backing die. It is preferable, however, to recede the backing die for this purpose.

Referring specifically to Figs. 17, 1S, 19 and 20, the channel shaped shroud 42 is formed of stock having a surface on the blade side thereof comprised of rectilinear transverse elements. The means for properly positioning the blade ends are produced by first locally distorting the shroud base to form projections 47 on the blade side thereof, after which the portions of the projections 47 in line with the blades are restored to form recesses at the desired portions` thereof, by forcing back the portions 43 of the projections 47 to bring these portions 43 into realinementfwith the shroud base. The recesses are formed with opposite walls having surfaces conforming to the .contour of the working faces of the blades 1 and coacting therewith longitudinally to a considerable extent. The shroud 42 after recessing is applied to the single-surfaced ends of the blades 1 and is united thereto by fusion of metal as indicated hereinabove.

With the type of shroud 2 disclosed in Figs. 1 to 4 inclusive, there are practically no local projections extending from the shroud stock and tending to produce any undesirable retardation of theturbine rotor. In the form of shroud 32 disclosed in Figs. 13 to 16 inclusive, the mounds 33 are so low and spread out as to produce substantially no retardation of the turbine rotor. The form of shroud 42 disclosed in Figs. 17 to 20 inclusive, would produce substantially no retardation to the rotation of the rotor as there are no local projections extending outwardly from the normal base of the shroud. The forms of shroud 32, 42, shown inFigs. 13 to 20, inclusive, are especially applicable to the larger sizes of blading because of the increased distance between the limits of transverse contact between the positioning surfaces and one of the working faces of the blade. j

It will be noted that with all of the constructions herein disclosed, a blade l1 having a singlesurfaced end may be utilized thereby eliminating waste of blade stock. The shroud itself `in each case is formed with spacing and angling means thereon. The fact that the shroud in each case is secured to the blade ends by fusion of metal together with the distortion of the shroud, also permits formation of a shroud strip which is very light in structure and which still possesses the requisite. rigidity and strength. It should furthermore be noted that in each case the shroud at a blade is formed with a recessed projection in contradistinction tothe formation of a shroud with a series of projections leaving recesses between them for the blade ends, although here the original projection is in fact altered by the recessing to form divisional projections. In the form disclosed in Figs. 17 to 2O inclusive, the recessed projection at a blade is discontinuous With the corresponding recessed projection of an adjacent blade so there Will be less tendency to produce eddying of the steam between the blades in this structure. v

It should be understood that vit is not desired to be limited to the exact details of construction shown and described except as required by the scope of the appended claims, for obvious modications Will occur to a person skilled in the art.

It is claimed and desired to secure b Letters Patent,-

1. The process'of providing a blade with a shroud comprising, forming said shroud with a continuous longitudinal corrugation, recessing said corrugation to form a surface, forming said blade With a single-surfaced end, applying said shroud to have said blade end lie Within said recess and with said corrugation surface coincident with a side face of said blade, and uniting said blade andsaid shroud by fusion of metal.

2. The process of providing a bla'de With a shroud comprising, forming said shroud With a continuous projection having a de-y jection surface coincident with a side faceof said blade, and uniting said blade and said shroud by fusion of metal.

3. The process of providing a blade With a shroud comprising, forming said shroud With a continuous longitudinal corrugation, distorting the metal of said corrugation to form a recess, forming said blade With a single-surfaced end, applying said shroud to have said blade end lie Within said recess, and uniting said blade and said shroud by fusion of metal.

4. The process of providing a blade with a shroud comprising, formingsaid shroud With a continuous projection having a depression on the opposite side thereof, distorting the metal of said projection to form a recess, forming said blade with a singlesurfaced end, applying said shroud to have said blade end lie Within said recess, and uniting said blade and said shroud by fusion of metal.

5. The process of providing a blade With a shroud comprising, forming said shroud With a projection, distorting the metal of said projection to form a recess, forming,4

said blade With a single-surfaced end, applying said shroud to have said blade end lie Within said recess, and uniting said blade and said shroud by fusion of metal.

6. The process o f providing a blade with a shroud comprising, forming an imperforate shroud` With a -.projection, distorting the metal of said projection to form a recess, forming said blade with a single-surfaced end, applying lsaid shroud to have said blade end lie Within said recess, and uniting said blade and said shroud byfusion of metal. j

In testimony whereof, the signature of the inventor is aiiixed hereto in the presence of tWo witnesses.

C. EDWIN SEARCH.

Witnesses:

J. M. J. KEOGH, W. H. LIEBER.

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