US2090468A - Turbine blade - Google Patents

Description

Aug. 17, 1937. D. 5. BROWN 2,090,468

' TURBINE BLADE v Filed Feb. 7, 1955' 2 Sheets-Sheet. 1

N vE/vTo 'Mk/ MM J QQW ATEQTRNE vs Aug. 17, 1937. I s, BRQWN 2,090,468

TURBINE BLADE Filed Feb. 7, 1936 2 Sheets-Sheet 2 a b Fa /4.

ATTORN YS Patented Aug. 17, 1937 UNITED STATES TURBINE m nus; 1

David Somers Brown, Wall send-on-Tyne, England, assignor to The Parsons Machine Steam Turbine Comp y,

Tyne, England Limited, Wallsend-on- Application February '7, 1936, Serial No. 62,741 a In Great Britain February 15, 1935 7' Claims. (c1. 252 -77.)

The invention relates to turbine blades and more particularly to assemblies of such blades into unit groups, such as sectors, for mounting on their carrier members;

According to one method'of manufacturing such aunit group, blades andpacking sections are arrangedalternately in a'former to build up a sector of the required size and are held in place temporarily, e. .g., by' a root-wire threaded through them, by a shroud, or by tack-welding,

theassernbly beingthen removed from the formerand theappropriate part dipped into a suitable flux, e-. g., a solution of borax, for cleaning purposes and subsequently into a bath of or containing an appropriate molten metal, e. g., a brazing mixture; whichflows intothe spaces between the packings and blades and effects the desired attachment.

According to another method, as described, e. g.,

0 in U. S.- patent specification, No. 655,414, the blades are inserted between the teeth of a kind of base comb, theteeth'being bent over to hold the blades in place before cleaning and brazing.

With these methods, and particularly when the packing sections are'produced by rolling, drawing or similar processes, it is found that the'engaging surfaces in some cases fit too closely and that the flux or brazing mixture or the like cannot enter sufiiciently freely between the surfaces of attachment.

The main object of the invention is to overcome these diflficulties.

With such an object, the invention consists in the improved blade assemblies, blades and packing pieces hereinafter described and particularly pointed out in the claims appendant hereto.

Referring to the accompanying diagrammatic drawings:-

Figure 1 shows a side view of one form of assembly of blades and intermediate distance pieces, held in place by a root wire;

Figure 2 being an elevation of one blade and distance piece;

Figure 3 shows an elevation of one blade and distance piece having a longitudinal ridge on each face;

Figure 4 being a corresponding end view of two blades and three distance pieces;

Figures 5 and 6 are views similar to Figures 3 and 4 in which the distance pieces each have three longitudinal ridges on one face and two on the other; 1 Figures '7, 8, 9 and 10 show modified forms in which the projections take the form of isolated patches arranged at the angles of a triangle;

.ing sections, b, shaped to correspond with the 10 adjacent contours of the blades and disposed near their roots, the packing sections, if desired, projecting on one or both sides beyond the line of blades as shown at c in' Figure 2, to assist in the attachment of the built-up sector to the rotor or 15 stator. a.

According to one form of the present invention,-(see Figures 3 and 4) each packing section,

b,- is provided with a slightly raised ridge, d, running across its two faces associated with the 20 adjacent blades, the ridge being very readily produced at the time a length of metal is rolled, drawn, extruded or otherwise brought to shape before'being'cut into short lengths to form the packing sections. 5

The blades and packing so assembled may be temporarilyheld in place by a wire, e, threaded through the packing sections and adjacent roots of the -blades,-(see Figures 1 and 2) by tackwelding or as heretofore proposed by a binding 30 wire or by a shroud.

The appropriate part of the assembly is then dipped into a cleaning bath, preferably in a boil-. ing condition, and immediately afterwards immersed in molten metal, e. g., .a brazing mixture, 35 which on cooling effects the permanent attachment between the blades and packing sections.

Owing to the ridges, d, provided on the packing sections, it will be seen that a slight space is left between blades and sections into which the 40 flux and metal have ready access.

According to another form of the invention, (see Figures 5 and 6) each packing section, b, is provided with five projecting ridges, d, parallel to the length of the blade, three on the one face 45 and two on the other.

Or alternatively, two ridges may be provided on each face or any other number of ridges may be provided in any desired combination.

In this case, the temporary connection is pref- 5O erably made by a threaded wire, e, since tack-welding on the lower surfaces of blades and packing sections may close entirely access of the flux or the like to the space between the two parallel ridges and the blade in contact therewith. 5

Similar methods are applicable to the case in which the blades are mounted on a base comb as referred to above.

It will be understood that the slight projections, having regard to the functions they perform, may be of many different shapes and if isolated patches, 1, (see Figures '7 and 8, where the patches are circular and Figures 9 and 10 where they are square) are preferably arranged at the angles of a triangle with the apex either up-or down as shown so as to provide three projections per pair of surfaces to be attached, it may be two on one surface and one on the other,

with a view, as explainedabove, to maintaining automatically the spaces between blades and packing sections of uniform width.

With such a three-point support, however, it is not essential that three isolated patches should be provided but that three points triangularly disposed at a reasonable distance apart can be selected from the projections provided, say in the formof two parallel ridges, as above de scribed.

According to an alternative form, (see Figures 11 to 14) the projections are made on the blades and either take the form of ridges or patches as above or are provided by corrugating the'knife edge of the blade to a sinusoidal form in way of the packing sections as shown at h, Figure 12, the hollows and troughsof the corrugations being made, by pinching areas such as 1', Figure II, a1- ternately in opposite directions. In this way the corrugations diagrammatically shown in Figures 13 and 14 project from the untreated edge of the blade and hold the packing sectional), a slight distance apart,

While in general not so convenient, the desired spacing of blades and packing sections may in some cases be secured by introducing a'length of wire of suitable gauge, e. g., a staple straddling the assembling wire, e, before completing the union.

I wish it to be understood that the term turbine blade? as used above is broad enough to include the blades of turbo-compressors and the like.

Other variations may be made from the precise details of construction and methods of procedure described above without exceeding the scope of the invention.

joining material in said free spaces.

2. A vunit group of assembled turbine blades as claimed in claim 1, in which at least one of, said juxtaposedsurfaces has such spacing devices integral with s'aid surface.

3. A unit group of assembled turbine blades as claimed-in claim 1, in which said spacing de- 1 vices have operative, parts arranged in triangular configuration to prevent tilting.

4. A unit group of assembled turbine blades as claimed in claim 1, in which said spacing devices take the form of ridges parallel to the length of the relevant blade. V

5. A unit group of assembled turbine blades of the character described, comprising a series of blades with knife edges sinusoidal at least at their root ends, intermediate root pieces with surfaces juxtaposed adjacent to said sinusoidal parts of said blades, together with joining material filling the space between said root pieces and said juxtaposed sinusoidal parts.

6. A unit group of assembled turbine blades of the character described, comprising in combination a seris of turbine blades each having a root; associated packing pieces disposed in the neighborhood of said roots with surfaces of said roots and of said packing-pieces juxtaposed and spacing projections locatedbetween said juxtaposed surfaces and individually integral with one of them, said spacing devices comprising isolated patches of small thickness in triangular configuration, with joining material in the free spaces left between said juxtaposed surfaces.

'7; As an article of manufacture, a root packing piece forspaced turbine blades, in which at least one operative face has integral therewith a plurality of isolated spacing projections of small thickness, said projections being arranged in triangular configuration.

DAVID soMERs BROWN.

CERTIFICATE OF CORRECTIONG Patent No. 2,090,1458. August 17, 1957.

DAVID SOPIEIRS BROWN.

It is hereby certified that the name of the assignee in the above numbered patent was erroneously described and specified as "The Par sons Machine Steam Turbine Company, Limited" whereas said nameshould have been described and specified as The Parsons Marine Steam Turbine Company, Limited, of wallsend-on-Tyne, England, as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of October, A. D. 1957.

I Henry Van Arsdale. Acting Commissioner of Patents.

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