US2918977A

US2918977A - Blade assembly

Info

Publication number: US2918977A
Application number: US593474A
Authority: US
Inventors: Sidney H Fedan; Norman J Ely
Original assignee: Koppers Co Inc
Current assignee: Beazer East Inc
Priority date: 1956-06-25
Filing date: 1956-06-25
Publication date: 1959-12-29
Anticipated expiration: 1976-12-29

Description

S. H. FEDAN ET AL BLADE ASSE BLY Dec. 29, 1959 4 Sheets-Sheet 1 Filed June 25, 1956 INVENTORS .r f m 3 T L 10 Dec. 29, 1959 s. H. FEDAN ETAL 2,918,977

' BLADE ASSEMBLY Filed June 25, 1956 4 Sheets-Sheet 2 IN V EN TOILS \SJDA/d. 7' F5 061/ Norma M J. .64 7.

agi/3M.

J a rroEM/i? v Dec. 29, 1959 Filed June 25, 1956 S. H. FEDAN ET AL BLADE ASSEMBLY 4 Sheets-Sheet 3 INVENTOR-S. 8101/57 16 FISDQA/ Nozmaa/ J. .5477

their a 7- roeA/s r Dec. 29, 1959 s. H. FEDAN ET AL 2,918,977

BLADE ASSEMBLY Filed June 25, 1956 4 SheetsSheet 4 IN V EN TOR-S QSJDA/ZY M F5044 United States Patent F BLADE ASSEMBLY Sidney H. Fedan and Norman J. Ely, Baltimore,'Md., assignors to Koppers Company, Inc., a corporation of Delaware Application June 25, 1956, Serial No. 593,474

"6 Claims. (Cl. 170-159) This invention relates to blade assemblies and more particularly to blade assemblies for industrial fans and to a method of making such assemblies.

With the rapid industrial expansion of today, there has been an ever increasing demand for eflicient and adequate heat exchange equipment to accommodate the waste heat inherent to such expansion. To meet this demand, industry has turned to such heat exchange means as the cooling tower and the radiator-type cooler, both of which means are dependent upon the industrial cooling fan.

'These industrial fans have had to be more than just a paddle wheel in order to move air in an efficient manner without excessive speeds of rotation and, in the past, some of the earlier models of industrial cooling fans have been similar to the common desk fan or airplane-type propeller. Today, there are many types of fan blade assemblies as Well as several well'known'methods of constructing such fan blade assemblies,including methods wherein laminated wood is carved and covered by plastic .to form the industrial fan blade, wherein the industrial fan blade is formed from plastic material itself, and wherein the industrial fan blade is formed from cast metal. Although these various assemblies and the various methods of manufacturing them have met some of the fan blade problems of corrosion, strength, fatigue, efliciency, sound level, and balance, none has been able to meet with all of these above-mentioned problems as efliciently as has the present invention. 7

The present invention provides a fan blade that is lightweight, resistant to fatigue and corrosion, aerodynamically efficient, and of high strength. In addition, the present invention provides an economical and eflicient method of manufacturing such a blade in a straightforward and uncomplicated manner.

Various other features of the present invention will become obvious with a reading of the disclosure set forth hereinafter.

More particularly, the present invention provides a method of making a blade assembly comprising the steps of casting .a quantity of selected quality lightweight metal in a .mold to form a metallic shank member, extruding a further quantity of selected quality lightweight metal to form a ribbed camber member and a thrust member of a blade section, stamping a selected quality lightweight metal plate to form a tip member of such blade section, and Welding the cast shank member, the extruded camber member, the extruded thrust member, and the stamped member together to form a metallic blade assembly. The present invention also provides a blade assembly which includes a retention shank member having integral therewith a transverse flange and an anchor-extending from the flange, and a blade section fixed to the shank mem her, the blade section including a camber member having a ribbed face, a thrust member including a face portion fixed to the camber member in facing relation with the ribbed face thereof, and a tip member closing the open end of the joined camber and thrust members, the camber member having at its root end a socket of configuration 2,918,977 Patented Dec. v29.,

identical to theanchor of the shank member to receive the anchor so that the sides of the anchor abut against the sides of the socket and the root end side of the camber member abuts against the side of the transverse flange of the shank member. Further, the present'invention provides interlocking means along the abutting sides to interlock the blade section to the shank member.

It is to be understood that various changes can be made by one skilled in the art in the several steps of the method disclosed herein and in the several parts of the blade assembly also disclosed herein without departing from the scope or spirit of this present invention. 1

Referring to the drawings:

Figure 1 is a perspective view of an advantageous embodirnent of the present invention, disclosing one face of an assembled blade section prior to its assembly with a hub-member;

Figure 2 is an exploded perspective view of the various members which are joined together to form the blade assembly of Figure 1, this view showing the other face of of the assembled blade section and retention shank member;

Figure 7 is a cross-sectional view taken in a plane passing' through line VII VII of Figure 6, showing details of a portion of the interlock between the assembled camber member of the blade section and the retention shank member;

Figure 8 is a cross-sectional view taken in a plane passing through line VIII-VIII of Figure 7, showing further details of'the interlock between the assembled camber and retention shank members;

Figure 9 is an enlarged broken plan view of a modified,

assembled blade section and retention shank member, disclosing a further advantageous embodiment of the present invention: I

Figure 10 is a cross-sectional view of the modified assembled blade section and'retention shank member of Figure 9, taken in a plane passing through line X-X of Figure 9. I I

As can be seen in Figure 1 of the drawings, the blade assembly of the present invention broadly comprises a retention shank member 6 and blade section 7. Referring to Figure 2, blade section 7 includes camber member 8, thrust member 9 and tip member 11. When the blade is properly assembly together, as will be described hereinafter, spindle 12 of the shank member is nested in the hub socket 13 of hub 14 and held in place by clamping bracket 16 fastened to hub 14 by means of tap bolts 17 (Figure 1).

In an advantageous embodiment of the invention described hereinafter, the blade sizes can range for fans from approximately 9v feet to approximately 22 feet in diameter. For blades used in fan models 9 feet through 10 feet in diameter, the chord width of the blade can be 10 inches. For blades use in fan models 11 feet through 14 feet in'diameter, the chord width can be 12 inches and for blades used in fan models 16 feet through 22 feet in diameter, the chord width can be 16 inches. In this connection, it is to be noted that when the chord width is 16 inches, a modified construction of the blade section can be provided in order to effect an economy in the blade assembly.

Figures 9 and 10 of the drawings and described hereinafter.

Referring to Figures 2-5 of the drawings, it can be seen that shank member 6 includes the aforementioned "spindle 12,'trans verse flange portion 18 integral with this spindle, and'anchor portion 19 integral with and extending from this transverse flange portion. Provided along 'the'sides of the transverse flange portion 18 on either side of theextending anchor 19 are interlock projections 21, these interlock projections serving to interlock the 'blade section to the shank member as will be described hereinafter. Referring particularly to Figure of the drawings, it 'can be seen that the interlock projections 21 each have a reduced head portion 22. This head portion, in turn, is stepped down or reduced at one side 25 (Figure 3) 'so that the head portion is adapted to engage properly "withchanneled ribs in the camber member of the blade T section when the sides of the anchor of the shank member are positioned to abut against the sides of the socket of the camber member. It also .can be seen that each interlock projection 21 is provided with wells 23. The

wells 23 are adjacent the reduced head portion 22 and on opposite sides thereof, these Wells serving to receive 'weldin'g material used to fix the". camber member to the shank member v rn addition to the aforementioned interlockprojections 21, further interlock means of similar construction are provided at the extremity of the anchor 19 of the {-shank member. Referring particularly to Figure 3 of the dr'awings it can be seen that the extremity of the anchor member is provided with spaced

ribs

26, 27, and 28 with a, groove 31 interposed between the

ribs

26 and 27, and

'ag roov'e 32 interposed between the

ribs

27 and 28. These ribs and grooves on the anchor portion are adapted to align with the hereinafter described ribs and grooves of Ithe'camber member of the blade section. As can clearly 'beseen in Figures 3 and 4, at the extremities of each the

rib members

26, 27, and 28, there is provided'a reduced head portion 34, this head portion having adjacent thereto, and on oppositel sides thereof, wells 36 which are also adapted to receive welding material for fixing the camber member to the shank member; It is to be noted further that the spindle portion of the shank member 6 can be provided, as is known in the art, with a recess 37 in order. to provide. for proper balance of Shank member 6, in an advantageous embodiment of the. present invention can be a permanent mold casting of aluminum alloysuch as that commercially designated ,A356,T71 The alloy A356-T71 has a chemical com position of 7.0% silicon and 0.3% magnesium with the balancealuminum and it is a member of the siliconmagnesium family of alloys. By using such' an alloy, it is possible to obtain excellent-casting features in carryjing out the'processjof castingthe shank member in a permanent mold and it is further possible to obtain a shank member of high strength and good resistance to icorrosion. Inthis connection, it is to be noted that this alloy has been found to have a tensile strength of 32,000 p.s.i., a yield strength of 24,000 p.s.i., an elongation of and an endurance limit of 11,000 p.s.i. Furthermore,.the resulting permanent-mold cast shank member has proven to have higher mechanical properties due to its better metallurgical structure than a sand-cast shank 'member and has proven to havea superior surface finish,

5 and 28.

The ribs serve to add to the desired structural rigidity of the camber member,

ribs

26', 27, and 28 being arranged to align with

ribs

26, 27, and 28 respectively of anchor 19 when the blade is assembled.

5 The socket 38 (Figure 2) of the camber member is of a configuration identical to the anchor 19 of the shank member and serves to receive the anchor when the blade is assembled so that the sides of the anchor abut against the sides of the socket and the root-end sides of the 10 camber member abut against the sides of the transverse flange portion 18 of the shank member. When this occurs, the stepped down portions 25 of the reduced head portions 22 of each of projections 21 interlock into the recesses formed at the root ends of channeled ribs 26 At the same time, the reduced head portions 34 provided on each of the

ribs

26, 27, and 28 of the anchor interlock into the recesses formed by channeled ribs 26', 27', and 28' along the bottom side of the socket 38 in the camber member. Thus, an interlocking arrangement is effected between the camber member and the shank member. With such an arrangement, a ready positioning and alignment means is provided for assembling the two members together and blade bending .moment is resisted firmly between the shank member and the camber member after such assembly.

thermore, the ribs 26', 27', 28', 41, and .42, which serve to provide structural stiffness and interlock as aforedescribed, and which also serve to support the face portion of .the thrust member 9 when it is assembled with the camber member, are more readily and efficiently formed by such extrusions. a t

In an advantageous embodiment of the invention, the aluminum alloy used to form a camber member can be -one which is known commercially as 6063-T6. The

physical properties of 6063-T6 have been foundto include a tensile strength of 35,000 p.s.i., a yield strength -of 31,000 p.s.i., an elongation of 12%, and an endurance limit-of 9,500 p.s.i. The chemical composition of this alloy is 0.4% silicon, 0.7% magnesium and the balance aluminum, this alloy also being a member of the siliconmagnesium family of alloys. With the use of such an alloy for the camber member, the camber has a pleasing surface finish, adequate strength for diverse structural applications, and a good resistance to corrosion.

,. It is to be understood that the thrust member 9 (Fig- .ures -1 and 2) can also be of aluminum extrusion alloy 6063-T6, tothus have the same physical properties and metallurgical characteristics as described above'for the camber section. In an advantageous embodiment of the invention, the minimum thickness of the camber section extrusion can be approximately 75 of an inch with solid sections at the leading and trailing edges of 1% inches and 1% inches, respectively. As for the thrust member, for blades having chord widths from 10 inches through 112 inches, thethrust member can be substantially all face portion of inch thickness and can be of substantially the samesize and configuration as the camber member, ,as shown in the embodiment disclosed in Figure 2 of the drawings. ;However,-in instances where blades having chord widths of 16 inches aredesired, it is then advantageous that the face portion of the thrust member be in creased in thickness to of an inch and that the thrust member be extruded to include, not just the face portion, but" a portion of the camber member aswell, and that the member be'extruded to include a portion of the thrust member. With such an arrangement, it is then possible to extrude both a narrower camber member and a narrower thrust member, thus obtaining those economies commensurate with extrusion practices for narrow members and, at the same time, obtaining the wider 16 inch chord width through an interlocking of the two members. Referring to Figures 9 and 10, specific details of such an interlocked camber and thrust member arrangement are disclosed. As can be seen in Figure 10, camber member 60 of this advantageous embodiment of the invention, which for the most part is like camber member 8 of Figure 2, is provided with

ribs

66, 67, and 68, the

ribs

67 and 68 being of T-shape cross section substantially like the ribs 27' and 28 of the camber member 8. However, it will be noted that the rib 66 is of an L-shape cross section rather than a T-shape cross section. This arrangement facilitates eflicient interlock of the camber and thrust members as will be described hereinafter. It also will be noted that a portion of the camber member 60 adjacent the rib 68 is omitted, and it will be further noted that a portion of the camber member adjacent the rib 66 has integral therewith a flat overlap portion 70 which cooperates with the face portion of thrust member 71, the thrust member 71 including, in turn, an overlap portion 75 which cooperates with the camber member adjacent rib '68. Both the

overlap portions

70 and 75 are provided at their extremities with a hook-like construction 72, this hook-like construction serving to provide effective interlocking and welding of the camber and thrust members. From the disclosure in Figures 9 and 10, it can be seen that both the camber member 60 and the thrust member 71 have a shorter overall width as a result of the interlocking arrangement, and thus economies of extrusion through shorter widths can be obtained.

The tip member in an advantageous embodiment of the invention can be stamped from a A; inch thick aluminum alloy plate which can be of an alloy designated commercially as 606l-T6.

In assemblying the several above-described parts of the blade assembly as disclosed in Figures l-8, the camber member 8 and the shank member 6 are brought together with the anchor 19 of the shank member engaging in the socket 38 of the camber member and the interlocking means on the shank member, namely reduced

portions

25 and 34, properly nesting in the recesses provided by the channeled ribs 26', 27', and 28 of the camber member. The two members are then welded together by continuous welds of special alloy wire, which can be an alloy commercially designated 5154. A welding process known as the Consumable Electrode Process of welding has been found desirable for welding the two members together, this process utilizing an argon inert gas envelope to prevent oxidation. Such a process serves further to eliminate corrosion from flux entrapment, and its rapid application reduces the heat effect on adjacent metal.

Once the camber member and shank member are welded together, the thrust member 9 is fastened to the ribbed face of the camber member and is welded by a process like that above-described to the camber member along the sides of the

outer ribs

41 and 42. In this connection, it is to be noted that the thrust member and the camber member are not joined together along the

internal ribs

26, 27, and 28'. This serves to prevent any internal stressing at such areas. It also is to be noted that a well 50 is provided at the base of anchor 19 and that

wells

51 and 52 are provided along

ribs

41 and 42 respectively, these wells serving to receive welding material used to fix the thrust member to the assembled camber and shank members.

It is to be understood that the camber member 60 of Figures 9 and 10, is substantially like the camber member 8 at its root section and is assembled to a shank member 6 in substantially the same manner. In this '6 connection, it will be obvious from the above description that the thrust member71 is interlocked with camber member 60 and welded along the hook-like extremities 72, the hook-like arrangement serving to receive the welding material used to fix the members together.

With the three parts of the assembly welded together, the tip plate is then welded advantageously by the continuous weld process at the extremity of the joined camber and thrust members opposite the shank member in order to close the open end formed by the camber and thrust members. It is to be noted that vent holes are not required in the assembly described since the continuous weld process allows no entrance of moisture.

As a further step in preventing corrosion which so frequently arises in the corrosive atmosphere of industrial plants, the blade assemblies described above can be provided with a special surface preparation treatment and then covered with at least one coat of corrosion resistant paint. Such a surface preparation treatment can include dipping at least the blade section of the assembly in a multi-stage acid-etch bath to form a protective surface on the aluminum and to provide an improved surface for adhesion of corrosion resistant paint coating. 'It is to be noted that the aforementioned multi-stage acidetch dip bath can be of the commercially known Al'odine 100, which is a protective coating for aluminum developed by the American Chemical Paint Company of Ambler, Pennsylvania. This bath serves to form a thin, tough, durable, non-metallic amorphous phosphate surface on aluminum. The coating of corrosion resistant paint can then be put on over the top of the aluminum, advantageously in two coats. The paint can be of the catalyzed epoxy type which has great resistivity to corrosive mediums and also excellent adhesive properties. In this connection, it is to be understood that other similar type bath solutions and paint coatings can also be used to prevent corrosion.

In order to prevent galvanic attack when a blade assembly of aluminum and a hub of the dissimilar metal, iron, are united in wet or moist atmospheres, it has been found desirable to insulate these two dissimilar materials from one another. To accomplish this, the aluminum retention shank member 6 can also be treated with an Alodine surface and a two coat corrosion resistive paint, and the area of the hub where contact is made can be treated with a rust inhibitive coating such as Parko Lubrite over which a coat of aluminum metal paint can be applied. In this connection, it is to be understood that other similar type solutions and paint coatings can also be used to prevent galvanic attack.

By carrying out the process above-described and by forming a blade assembly in a manner as also described above, it is possible to provide an industrial fan blade assembly that is lightweight, that is easily formed, that is resistant to fatigue and corrosion, and that is economically fabricated and assembled, thus providing an excellent answer to the ever increasing problems of waste heat in our expanding industrial economy.

The invention claimed is:

1. A blade assembly comprising a unitary retention shank member, said shank member being formed with a transverse flange and an anchor projecting from said flange intermediate the ends thereof, a blade section fixed to said flange member, said blade section including a unitary camber member having transversely spaced longitudinally extending edges terminating at their root ends at the ends of said flange, a socket formed in said camber member intermediate said edges, said socket being shaped complementary to said anchor to receive in abutting relation said anchor so that the root end side of said camber member abuts against the side of said transverse flange, and means along said abutting sides to interlock said blade section to said shank member.

2. A blade assembly comprising a unitary retention shank member, said shank member being formed with a transverse flange and an anchor projecting from said flange intermediate the ends thereof, a blade section fixed to said flange member, said blade section including a unitary camber member having transversely spaced longitudinally extending edges terminating at the ends of said flange, a socket formed in said camber member intermediate said edges, said socket being shaped complementary to said anchor to receive in abutting relation said anchor so that the root end side of said camber member abuts against the side of said transverse flange, and complementary means formed along said abutting sides of said flange and said shank to interlock said blade section to said shank member.

3. A blade assembly comprising a unitary retention shank member, said shank member being formed with atransverse flange and an anchor projecting from said flange intermediate the ends thereof, a blade section fixed to said flange member, said blade section including a unitary camber member having transversely spaced longitudinally extending edges terminating at one end and having at least a portion of one face thereof formed with .a plurality of spaced ribs at the ends of said flange, a socket formed in said camber member intermediate said .edges, said socket being shaped complementary to said anchor to receive in abutting relation said anchor so that the root end side of said camber member abuts against the side of said transverse flange, and means provided" alongsaid'abutting sides of said flange and said shank coacting with said ribs to interlocksaid blade sectionto said shank member.

4. The invention as defined in claim 3 in which said blade assembly includes a thrust member fixed to said one camber faceand overlies said ribbed portion.

'5. The invention as defined in claim 3 in which said ribs extend coextensively with said camber member edges.

6. The invention as defined in claim 5 in which said blade assembly includes a thrust member fixed to said one camber face and overlies said ribbed portion and in which a member is fixed to the tip end of the blade to said thrust member and said camber member.

References Cited in the file of this patent UNITED STATES PATENTS 1,000,602 Jacobs Aug. 15, 1911 1,456,512 .Muller May 29, 1923 1,457,844 Leitner June 5, 1923 1,473,121 Nelson Nov. 6, 1923 1,516,556 Wilkinson Nov. 25, 1924 2,259,247 Dornier Oct. 14, 1941 2,430,854 Berliner Nov. 18, 1947 2,454,200 Perkins Nov. 16, 1948 2,535,917 Gruetjen Dec. 26, 1950 2,786,538 Blackburn et a1 Mar. 26, 1957