US2788569A

US2788569A - Fabrication of sheet stock blades for fluid flow machines

Info

Publication number: US2788569A
Application number: US418167A
Authority: US
Inventors: Edward A Stalker
Original assignee: Stalker Development Co
Current assignee: Stalker Development Co
Priority date: 1954-03-23
Filing date: 1954-03-23
Publication date: 1957-04-16
Anticipated expiration: 1974-04-16

Description

April 16, 1957 E. A STALKER 2,738,569

FABRICATION OF SHEET STOCK BLADES FLUID FLOW MACHINES Filed March 215, 1954 2 Sheets-Sheet 1 i H "1 Z 2 flgi /6C /6d J: 4/

, INVENTOR.

April 16, 1957 E. A. STALKER 2,788,569

FABRICATION OF SHEET STOCK BLADES FOR FLUID FLOW MACHINES Filed March 23, 1954 2 Shets-Sheet 2 IIIIII-I II Q L 2". F 5

82 INVENTOR.

United States Patent FABRICATION OF SHEET STOCK BLADES FOR FLUID FLOW MACHINES Edward A. Stalker, Bay City, Mich assignor to The Stalker Development Company, Bay City, Mich, a corporation of Michigan Application March 23, 1954, Serial No. 418,167

8 Claims. (Cl. 29-1563) This invention relates to blades for compressors, turbines and the like.

An object of this invention is to provide a means of fabricating blades economically from sheet stock such as sheet metal.

Another object is to provide a means of fabricating sheet stock blades which require a minimum of fixtures for supporting the blade parts in proper relation while they are being soldered together.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in the accompanying drawings in which Figure 1 is a side elevation of a blade according to this invention;

Figure 2 is a section on line 2-2 in Figure 1;

Figure 3 shows a fragment of a partly formed blade blank;

Figure 4 shows the blank of Figure 3 with a recess;

Figure 5 shows the blade blank of Figure 4 in a machine for performing other operations on the blank;

Figure 6 shows a fragment of a blade blank as formed by the machine of Figure 5;

Figure 7 shows a nose fragment of a blade blank undergoing a forming operation;

Figure 8 shows a blade blank before a soldering operation;

Figure 9 shows an alternate form of a blade blank before undergoing the operation of Figure 7;

Figure 10 is a view of a rack and blades for use in soldering the blades in a furnace;

Figure 11 is an alternate arrangement for treating a blade blank;

Figure 12 is a sectional view of the blade blank after the operations indicated in Figure 11 are performed;

Figure 13 is a section of the upper blade blank before the nose operation;

Figure 14 is the blank of Fig. 13 in the tool for forming the nose portion of the blank; and

Figure 15 is a section of the upper and lower blanks fixed together for the soldering operation.

Reference is made to the application of Daniel J. Clarke and Edward A. Stalker, Ser. No. 282,012, filed April 12, 1952, entitled Hollow Blades and Manufacture Thereof.

In some blades for compressors, turbines and the like it is desirable or necessary to fabricate them from relatively thin sheet providing them with nose radii which are less than the thickness of the material. In such instances the small nose radii can be provided by making the blade of two parts, the upper and lower walls. Each part is scarfed properly so that when the two parts are brought into registration, the proper nose radii are or can be formed.

When the blade walls are thin, for instance having a thickness of about 0.015 inch, it is very diflicult to align the abuttingedges and hold them in alignment during the soldering operatiom 11 In this invention a unique technique is employed to position the parts of the blade which excludes the need for fixtures to determine the relative position of the parts. This saves the cost of the fixtures and the cost of reconditioning them from time to time. After each pass through the brazing furnace the dimensions of the fixtures change and after a few passes they must be corrected.

Referring now to the drawings a compressor blade 10 is shown in Figs. 1 and 2. It is comprised of the upper part 12 and the lower part 14. These have the nose surfaces 16a and 16b respectively abutting each other at the leading edge (L. E.) on line 16. The parts are lapped at 20 along the separate trailing edge (T. E.) portions.

Since the thickness of the blade walls may be about 0.015 of an inch for a 10 inch span and 3 inch chord it is very difiicult to hold the abutting nose surfaces 16a and 16b in alignment while the parts are being soldered.

In practicing this invention the blade blank 22 is preferably stretched by dies to the form shown in Fig. 3 which is comprised of the upper wall 10a integral with the lower wall 14a through the junction piece 24.

The contour of the upper wall is preferably precisely formed at this stage between the points A and B. Also the contour of the lower wall is precisely formed at this stage of operation, extending from the points C to D. See Figs. 3 and 8.

In the next operation the recess 28 is cut in the junction piece from the point A to the point C as shown in Fig. 4. Thus the upper and lower edges of the recess coincide with a part of the nose surfaces which are to be butted subsequently. The thickness of the junction piece is preferably reduced to about 20 percent of the blade wall thickness.

The next operation extends the junction piece forward by swaging as shown in Fig. 6 and defines the full extent of the surfaces 16c and 16d which are to be the abutting surfaces at the leading edge on line 16 in Fig. 2.

As shown in Fig. 5 the blank 22 is gripped by the dies 30, 31 and 32, the former being seated in the recess 28. The die 32 has the recess 34 of such a width that when the die 30 is pressed upward portions of the thin junction piece are displaced upward along the sides of the die recess as shown in Fig. 6. Subsequently the plunger 36 is pressed upward giving the roof shape to the junction piece as seen in Fig. 6. The peak 38 of the junction piece provides a locating bend line for subsequent operations.

The blank is next removed from the dies of Fig. 6 and placed between the

aligned dies

40 and 41. Die 40 is pressed toward 41 and folds the junction piece about the peak line 38. Since the peak line 38 has been accurately formed and located in relation to the surfaces 16a and 16b, these will abut when the

opposite portions

42 and 43 are folded and flattened one onto the other as shown in Figs. 7 and 8. This also brings the nose surfaces of the upper and lower parts into aligned abutment defining a selected blade section rearward of the junction piece with an effective radius of curvature less than the thickness of the parts themselves.

If desired the trailing edges may be fixed together as by spot welding at 50, as shown in Fig. 9 before the junction piece is folded completely.

The trailing edges are preferably scarfed as shown at 51 and 53 in Figs. 8 and 9.

The opposing thicknesses of the junction piece are fixed together preferably by fusion with an electric current securing these pieces in proper alignment.

The upper and lower parts are now secured together at the trailing edge defining the proper blade sect-ions and the proper twist from root to tip.

The assembly is next placed in a simple rack 54 shown in Fig. 10 preferably the leading edge of the blade down. A wire of solder 55 is placed inside the blade at-the leading edge and in the groove 56 at the trailing edge and the'rack'an'd bla'de areplaced'in afurnace where they are heated to the soldering temperature.

The rack 54 is merely for supporting the blade inits upright position and is not needed -to determine the dimensions or relative positions of the parts. Hence the rack never needsto be reconditioned to establish dimen- SlOllS.

When the blade is removed from the furnace the trailing edge portions are cut oii at the locality 6d definingthe trailing edge (T. E.) ofthe blade. This edge is de'. urred by tumbling, sanding or the like.

The junction piece is trimmed off at the nose and the nose is rounded, on a sanding belt for instance.

In an'alternate procedure the recess 28 is omitted and thejuncti'on .piecefhasthe same thickness as the upper and lower'parts. See Fig. 11.

Theblank is clamped between the dies 32 and as. The intermediate die 70displaces the'junctionlpiece inward providing the relatively thin parallel portions 72 and '74 of'th'e junction piece. The inner die 76 is next pressed forward giving "the roof shape to'the junction piecethereby providing the bend line at the roof peak 8d. The resulting blank Fig. 12 is subsequently treated as described for blank 22'to form the blade.

In still another form of the invention each blade'part upper and lower, is stretched to the precise contour desired as shown in Fig. 13 for the upper part 3d. The trail- .ing edge portion is preferably scarfed at 82 as shown.

The segment which is subsequently to define the blade upper contour is indicated between E and F. The nose surface which is .toabut the nose surface of the lower partis 84 lying along line'86. 'See Figs. 13-45.

The upper .part'sil is clamped between dies 94) and 92, Fig. 14, with the surface defined by line 86 in line with the plunger 'die 94. When the plunger 94 is moved up ward it bends the end 93 of the part upward against an internal surface ofi90 and shears it to a selected thinness forming a nose junction piece or projection 95.

The lower part 96 is similarly treated with a projection 97. The'two parts so formed are shown in Fig. 15. They are fixed together'at the front .preferablyby fusing the material at 98 and at the rear preferably by the spot welds 99.

Solder wires 100 'an'dltll are placedrespectively at the nose and'tail portions and the assembly is soldered preferably by heating in a furnace. Subsequently thenose and tailare'finished to thedesired shape.

By forming the blade according to this invention the use of dimensioning and positioning -fixtures are eliminated. This saves their initial cost and the cost of maintaining them to accurate dimensions. Also byelintinatingthe fixtures "more'blades can be solderedsimultaneously in a given size of furnace. This also reduces the cost offabrication.

Accordingly it will now be clear that I have provided a unique and economical means of producing blades.

Although I have discussed thefabrication with respect to compressor blades it is to be understood that theinvention also'applies"toturbine blades and the like as well. Also'where reference is made herein to solder or soldering, such terms are intended to include equivalent brazing materials and a brazing operation.

While Ihave'illustrated a'specific'form in this invention it is to beunderstood that I do not intend to limit myself to this exact form but intend to claim my invention broadly as indicated by the appended claims.

I claim:

1. The process of fabricating blades for compressors and turbines having a nose radius smaller than the thickness of the bladewall closely adjacent the leading edge of said blade, comprising the steps of forming blade upper and lower parts to selected contours with an integral nose junctionpiecm-formingsaid junction piece to have-portions ofreduced thickness providing for abutting nose surfaces and a bend line between said parts spaced therefrom, 'folding said junction 'piece about said 'bend line bringing said reduced thickness parts into abutment at the nose surfaces thereof substantially defining said selected blade section rearward from said abutment and having an effective radius of curvature at said nose less than the thickness of the adjacent blade wall while maintaining precise .relative positioning of said blade parts through said integral junction piece, securing opposing portions of said piece together adjacent to the nose of said blade, and securing the trailing edge portions of said blade together, soldering said parts together at'the leading and trailing edge portions thereof, and cutting off said junction piece defining the blade nose of selected shape.

2. The process of fabricating a blade for compressors and turbines having a nose radius smaller than the thickness of the blade wall closely adjacent to the leading edge of said blade, comprising the steps of forming blade upper and lower parts to selected contours with an'integral nose junction piece, forming said junction piece to have portions thereof providing for abutting nose surfaces "and a' bend 'line'between said parts spaced'therefrom, folding said junction piece about said bend line bringing said parts 'into abutment at the nose surfaces thereof substantially defining said selected blade'sections rearward from said abutment and with an effective radius of curvature rearwardly of said'junction piece less than the thickness 'of said parts, said integral junction "piece retaining said abutting parts in precisely located relation to each other',securing opposing portions of said piece together adjacent to the nose of-said blade, securing the trailing edge portions of said blade together and placing said parts in a rack, heating said rack with said parts therein in a furnace during a'soldering operation with'substantially the whole'surfaces of said parts free of contiguous blade shaping fixtures while retaining said selected blade contours, and removing said junction piece leaving the'blade nose of selected shape.

3. The process of fabricating a hollow blade for compressors and turbines, said blade having a nose radius smaller than the thickness of the portion of the blade wall adjaeentto the leading edge of said blade, comprising the steps of stretch forming each of the upper and lower blade parts precisely to selected final blade contours corresponding substantially to the blade sections of thefinished blade also forming each said part with a projection at the nose thereof each with a nose surface of selected relation to the corresponding said part so that when said surfaces are brought int-o abutment said parts cooperate to define said blade sections rearward from said abutting surfaces with an effective radius of curvature rearwardly of said projection less than the thickness of said parts, fixing said projections together adjacent to the nose of'said blade with said nose surfaces in aligned abutting relation, securing the trailing edge portions of said'blade together, placing solder in the joints formed at theabutting surfaces of said parts,' supporting said parts in substantially free and unconfined relation and subjectingsaid'assembled partsto a brazing operation .to permanently .fix said parts together while retaining substantially said finished blade contours, and 'cuttingofizsaid projections defining the blade nose of selected shape.

'4. The process of fabricating blades for compressors and turbines comprisingthe.stepsof'forrning blade upper and lower parts integral with a nose junction piecewhose thickness is less'than that of said parts,.said parts being precisely formed to selected blade contours, folding said junction piece along a line spaced from the leading edges of said parts thereby bringing the nose. surfaces of said parts into aligned abutment defining a selected-blade section rearward from saidypiece with said junction-piece being foldedupon itself, securing opposing portions of said junction piece togethertadjacent the .-..11OS6 of said blade, and securing the trailing edge portions of said blade parts together by fusion, soldering said parts together at the leading and trailing edge portions, and removing said junction piece letving the blade nose of selected shape.

5. The process of fabricating blades for compressors and turbines comprising the steps of forming blade upper and lower parts integral with a nose junction piece, said parts being precisely formed to selected blade contours, swaging said junction piece to define abutting surfaces on each part at the nose thereof with said junction piece extending forward from said surfaces, folding said junction piece along a line spaced from the leading edges of said parts to bring said abutting surfaces of said upper and lower parts into registration and to bring opposite portions of said junction piece into precisely located relation with respect to each other, securing said opposite junction portions together, securing the trailing edge portions of said blade together, soldering said parts together at the leading and trailing portions thereof, and removing said junction piece leaving the blade nose of selected shape.

6. The process of fabricating blades for compressors and turbines comprising the steps of forming blade upper and lower parts to selected contours by stretching with an integral nose junction piece, forming said junction piece to have portions thereof providing for abutting nose surfaces and a bend line therebetween for positioning said upper and lower parts in relative positions for defining a selected blade section, folding said junction piece about said bend line bringing said blade parts into precisely located abutment at the nose surfaces thereof substantially defining said selected blade section rearward from said junction piece with an efiective radius of curvature less than the thickness of said parts, securing opposing portions of said piece together adjacent the nose of said blade to retain said precise location, securing the trailing edge portions of said blade together, soldering said parts together at the leading and trailing edge portions thereof, and removing said junction piece leaving the blade nose of selected shape.

7. The process of fabricating compressor and turbine blades from relatively thin upper and lower sheet metal parts bonded together at abutting surfaces along the lead ing and trailing edges comprising the steps of forming blade upper and lower parts from said thin sheet metal with an integral nose piece extending along the span of each part, said parts being precisely formed to selected biade contours defining leading edge lines at the junction of said nose pieces and said parts With said leading edge lines extending spanwise along the length of said parts, bending said nose piece along lines spaced from the lead ing edge line of each of said bladeparts respectively thereby bringing the nose surfaces of said parts into aligned abutment throughout the blade span and defining a selected blade section rearward from said leading edge line with said nose pieces in abutting contact, securing said nose pieces together, soldering said. blade parts together at the leading and trailing edge portions, and cutting off said junction pieces at said leading edges defining the blade nose of selected shape.

8. The process of fabricating blades for compressors, turbines and the like comprising the steps of forming blade upper and lower parts from sheet metal integral with a junction piece extending along the span of each part, said blade parts having free and separate spanwise edges opposite said junction piece, said blade parts being precisely formed to selected blade contours defining edge lines at the edge of said junction piece extending spanwise along the edge of said parts, folding said junction piece along a line spaced from said spanwise edge of said blade parts thereby bringing the nose and trailing edge surfaces of said blade parts into aligned abutment defining a selected blade section extending chordwise from said piece, securing the nose and trailing edge portions together, soldering said parts together at the leading and trailing edge portions, and removing said junction piece at the adjacent said blade edge defining the selected shape of the nose portion of the blade at the last said edge.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,348 Lampton Aug. 31, 1943 2,427,747 Schneider Sept. 23, 1947 2,514,525 Stulen July 11, 1950