US2431064A

US2431064A - Method of producing hollow propeller blade constructions

Info

Publication number: US2431064A
Application number: US501192A
Authority: US
Inventors: James H Mckee
Original assignee: Curtiss Wright Corp
Current assignee: Curtiss Wright Corp
Priority date: 1943-09-03
Filing date: 1943-09-03
Publication date: 1947-11-18
Anticipated expiration: 1964-11-18

Description

J. H. McKEE Nov. 18, 1947.

METHOD OF PRODUCING HOLLOW PROPELLER BLADE CONSTRUCTIONS Filed Sept. 3, 1943 2 Sheets-Sheet 1 INVEN TOR. 7amesEMcKe Nov. 18, 1947. J. H. McKEE 2,431,064

METHOD OF PRODUCING HOLLOW PROPELLER BLADE CONSTRUCTIONS Filed Sept. 3, 1943 2 Sheets-Sheet 2 m k b Q i t INVENTOR. .famearH .416. K26

ATTO/f/VEK Patented Nov. 18, 1947 METHOD or PRODUCING noL'Low PRO- PELLER BLADE consranc'rrons James H. McKee, North Caldwell, N. J., assignor to Curtiss-Wright Corporation, a corporation of Delaware Application September 3, 1943, Serial No. 501,192

ration to thereby provide an own channel for the insertion between said plates of a welding electrode or equivalent means for securing said memher in reinforcing position.

Various other objects, advantages and features of my invention will become apparent from the following detailed description.

My invention resides in the propeller plate, reinforced propeller blade, novel methods, constructions and arrangements of the character hereinafter described and claimed.

For an understanding of my invention, reference is to be had to the accompanying drawings.

in which:

Fig. 1 is a plan view showing a camber propeller plate;

Fig. 2 is a longitudinal, vertical sectional view showing a thrust propeller plate;

Fig. 3 is a longitudinal, vertical sectional view showing the camber propeller plate of Fig. 1 and an attached connecting member;

Fig. 4 is a transverse, vertical sectional view illustrative of a propeller plate while subjected to a shaping operation;

Figs. 5 and 6 are transverse vertical sectional views illustrative of a welding operation per- 6 Claims. (Cl. 29-1563) enerally is of elliptical configuration in correspondence with the aforesaid shallow opening of the camber plate C and, to less extent than the latter, it has convex shape. As will be noted from Fi 2, said thrust plate 1'' does not comprise a shank section as does the camber plate C.

As illustrated, the plates C and T comprise the respective longitudinally extending integral ribs 1- and TI which, when said plates are assembled, are disposed substantially in facing relation or in a common plane. In the form of the invention herein shown, although not necessarily, the ribs 1" formed on a blade construction or a partially completed propeller blade;

Fig. 7 is a transverse, vertical sectional view illustrating a step in the production of the hollow propeller blade of my invention; and

Figs. 8 and 9 are transverse, vertical sectional views illustrative of the complete propeller blade.

Referring to Figs. 1 and 2, I have shown a metallic camber plate C and a metallic thrust plate T of the general character known in the art for forming a hollow propeller blade B as shown in Figs. 8 and 9.

As illustrated, the camber plate C comprises a tubular shank l. having extending therefrom the plate proper 2 which generally is of convex configuration, the convexity decreasing in a progressive manner as the tip of the plate is approached whereby said camber plate C defines a shallow opening of generally elliptical configuration. The thrust plate '1 comprises a plate properia which and Ti are formed, as described in my pending application, Serial No. 493,314, filed July 2, 1943; by subjecting uniformly thick plane sheets of metal, which form the blank plates for the respective camber and thrust plates C and '1 herein disclosed, to two or more milling operations whereby each sheet of metal is longitudinally tapered in such manner that the thickness of each sheet'of metal decreases longitudinally therealong toward the tip of the blade. The milling cutter is so shaped or arranged that, while the taperin operation proceeds, a longitudinal strip'of the original sheet of metal remains intact, this strip of metal forming the aforesaid rib 1' or H, the ends thereof toward the left terminating approximately at the respective locations a, Figs. 1, 2, and 3. As a result of the described milling operations, the thickness 0; height of each of the ribs r and H increases progressively in a direction extending longitudinally along the propeller blade toward the tip thereof. Further, it is desirable that the milling cutter be so shaped that the described operation causes each of the ribs r or rl to be bordered by fillets J as illustrated.

After the blank plates have been milled as described above, the camber plate C and the thrust plate '1' are broughttothe finished form herein disclosed in Figs. 1, 2, and 3, by subjecting each of the partially completed propeller plates having the integral longitudinal ribs, respectively, to suitable milling, trimming and shaping operations, the convex configuration and the twist being imparted to the plate during the operation last noted, all as generally referred to in said pending application, Serial No. 493,314, filed July 2, 1943. Thereafter, the aforesaid shallow opening of the camber plate C is closed by the thrust plate '1 when the two plates are secured together by weld metal 3 as shown in Figs. 8 and 9, to form the propeller blade.

As more fully disclosed in my pending application, Serial No. 496,232, filed July 26, 1943, granted August 2'7, 1946, No. 2,406,471, a connecting or reinforcing metallic member or section of metal M of suitable tapered configuration is suitably held on the plate rib r throughout a distance d thereof, Fig. 3. While said connecting member M is thus held, it is secured to said rib r in any suitner, as, for example, by metallic arc, resistance or atomic hydrogen welding. By this operation, the structure shown in Fig. 3 is produced.

In accordance with the invention, the finished thrust plate T of the character referred to above is subjected to a reverse shaping operation prior to the time that it is assembled with the camber plate to form the complete blade. Thus, as shown in Fig. 4, I provide relatively movable die members MI and M2 having a length the same as or less than that of the thrust plate T, the die MI being provided with a longitudinally extending groove gl for the reception of the rib rl. With the die members MI and M2 open, the finished thrust plate T is properly positioned between them whereupon, by closing said die members MI and M2, the thrust plate T is given the reverse configuration shown in. Fig. 4.

After completion of the foregoing operation, the thrust plate T is assembled in proper relation with the camber plate and connecting member structure shown in Fig. 3 to thereby produce a propeller blade arrangement as shown in Figs. 5 and 6. As indicated in Fig. 2, the rib rl terminates short of the tip of the plate T a distance dl and, as indicated in Fig. 3, the rib r terminates short of the tip of the plate C a distance d2. Further, as will be understood from the aforesaid Patent No. 2,406,471, the ribs r and TI are suitably trimmed throughout a distance d3 so that, when the two plates T and C are properly assembled, facing surfaces of said ribs engage or closely approach each other throughout said distance (13. Further, when said plates are properly assembled, the upper surface of the connecting member M either engages or closely approaches the lower surface of the rib rl of the thrust plate T throughout the distance d, Fig, 3.

By suitable means, not shown, the plate T is held in proper assembled relation with respect to the plate C and the attached connecting member M whereupon, in accordance with the invention, the facing surfaces of the ribs r and T! are secured together throughout the distance d3, Figs. 2 and 3, and the facing surfaces of the connecting member M and the rib r are secured together throughout the distance d, Fig. 3.

In the form of the invention herein illustrated, although not necessarily, there is utilized for the purpose aforesaid, an electrode e of suitable metallic arc welding apparatus. By reason of the fact that the thrust plate 'I' was reversely set as described above, a passage or channel exists extending lengthwise of the propeller blade 50 that the electrode e may be readily positioned in operative relation to the two sets of facing surfaces last described to produce a welded joint n02 throughout a distance d3 between said facing surfaces of the ribs 1' and TI and a welded joint w3 throughout a distance d between said facing surfaces of the connecting member M and the rib r. Further, by reason of the reverse configuration imparted to the thrust plate T, it becomes practical to introduce suitable filing or scraping tools interiorly of the hollow propeller blade in order to clean the welded joints w2 and w3.

By the operations described above, a short section of the thrust plate rib rl is secured directly to the camber plate rib r, the remainder of the thrust plate rib rl being secured directly to the facing surface of the connecting member M to thereby produce the blade construction illustrated in Figs. 5 and 6.

After completion of the foregoing, multi-section welding mandrels m as known in the art are positioned within the hollow blade construction at each side of the reinforcing arrangement comprising the connecting membe'rM. Thereupon, an adjustable platen, h forming a part of a special table type welding jig or fixture, is operatively associated with the blade construction and mandrel structure, said adjustable platen it being lowered to exert pressure thereon to restore the thrust plate T to its original or finished configuration as shown in Fig. 7 and to hold it in such configuration. Thereafter, the weld metal sections 3 are deposited in known manner to positively weld the thrust and camber plates T and C to each other at their leading and trailing edges. This results in the production of the complete propeller blade illustrated in Figs. 8 and 9.

As stated, the die members MI and M2 may have a length the same as the thrust plate T. Alternatively, said die members MI. and M2 may be substantially shorter than said thrust plate T and utilizable for reversely shaping the latter only throughout the thicker section thereof.

The blade reinforcement comprising the rib r and H together with the connecting member M increases the stiffness of the propeller plates with resultant decrease in the amplitude of plate vibration or deflection which may be excited aerodynamically or by engine pulsations. As a result, stresses within the plates are reduced. Further, such increase in stiffness of th propeller plates raises the natural frequency thereof above the range of objection-able frequencies to some extent at least and this decreases the amplitude of plate vibration or deflection.

With respect to a propeller blade wherein the interior chamber is sealed, deformation of the airfoil surface may arise due to the difference of aerostatic pressures exteriorly and interiorly of the blade, this being caused (1) by pressure differences resulting from changes in altitude and (2) by pressure differences due to centrifugal action on the air in the interior blade chamber. The aforesaid blade reinforcement comprising the ribs 1' and TI together with the connecting member M decreases this deformation of the airfoil surface.

Within the purview of the invention, it shall be understood that the section of the thrust plate T at the right of the rib rl, Fig. 5, may retain its finished configuration while the section of said thrust plate Tat the left, Fig. 5, is reversely bent as and for the purpose described. This follows because, if desired, only one side section of said thrust plate T need be given the aforesaid reverse configuration for the purpose of providing an open channel through which a welding electrode or equivalent may be introduced for the purpose stated. By reverse configuration, I mean any configuration which is imparted tothe completed thrust plate T, which changes it from its completed state for the purpose stated. Obvi, ously, the dies MI and M2 may have various configurations which need not be necessarily arcuate as illustrated.

While the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. In the art of producing a hollow blade construction, comprising ribbed convex plates, the steps which consist in shaping one of said ribcarrying propellerplates in part at least reversely as regards the exterior convex configuration thereof, assembling said plate with the other rib carrying propeller plate with the rib thereof facing a spacing member welded to and project ing from the rib on said other plate whereby, due to the reverse configuration of said first named plate, an open longitudinally extending channel is formed at the respective edges of the blade construction, and inserting a welding electrode into said channel and between said plates to form a welded joint between said first named rib and said spacing member.

2. In the art of producing a hollow blade construction, comprising ribbed convex plates the steps which consist in shaping one of said ribcarrying propeller plates in part at least reversely as regards the exterior convex configuration thereof, assembling said plate with the other rib carrying propeller plate with the rib of said reversed plate facing a longitudinally tapered spacing member welded to and projecting from the rib formed on said last named plate whereby, due to the reverse configuration of said first named plate, an open longitudinally extending channel is formed at the respective edges of the blade construction, and inserting a welding electrode into said channel and between said plates to form a welded joint between said first named rib and said spacing member, shaping said first named plate to restore it to its original convex configuration, and welding said plates together at the marginal edges thereof to form the blade construction.

3. In the art of producing a hollow propeller blade comprising ribbed convex plates, the steps which consist in shaping one of said rib-carrying propeller plates so that it has approximately reverse concave-convex configuration as regards the exterior convex configuration thereof, -disposing said plate generally in blade-forming relation with the other rib carrying propeller plate and with the rib thereof facing a longitudinally tapered spacing member welded to and projecting from the rib formed on said last named plate whereby, due to the reverse configuration of said first named plate, an open longitudinally extending channel is formed at the respective edges of said plates, inserting a welding electrode into welded Joint between said first named rib and said spacing member, inserting a pair of complementary sectional mandrels between said plates one on each side of said spacing memben'shaping said first named plate to restore it to its original convex configuration, and welding said plates together at the marginal edges thereof to form the propeller blade.

4. In the art of producing a hollow blade construction comprising ribbed convex plates at least one of said ribs being so extended as to constitute at least in part a plate spacing means when Joined with the other rib, the steps which consist all) in shaping one of said rib carrying propeller plates in part at least reversely as regards the exterior convex configuration thereof, assembling said plate with the other rib carrying propeller plate with the rib thereof facing and abutting the rib on said first named plate whereby, due to the reverse configuration of said first named plate, an open longitudinally extending channel is formed at the respective edges of the blade construction and inserting a welding electrode into said channel and between said plates to form a welded joint between said ribs.

5. In the art of producin a hollow blade construction comprising ribbed convex plates at least one of said ribs being so extended as to constitute at least in part a plate spacing means when Joined with the other rib, the steps which consist in shaping one of said rib carrying propeller plates in part at least reversely as regards the exterior convex configuration thereof, assembling said "plate with the other rib carrying propeller plate with the rib thereof facing and abutting the rib on said first named plate, whereby, due to the reverse configuration of said first named plate, an open longitudinally extending channel is formed at the respective edges of the blade construction, inserting a welding electrode into said channel and between said plates to form a welded joint said plate with the other rib carrying propeller said channel and between said plates to form a plate with the rib thereof facing and abutting the rib on said first named plate, whereby, due to the reverse configuration of said first named plate. an open longitudinally extending channel is formed at the respective edges of the blade construction and inserting a welding electrode into said channel and between said plates toiorm a welded joint between said rib, inserting an abrading tool'into said channel and between said plates to clean the welded joint, and thereafter reshaping said first named plate convex to close the open longitudinally extending channel preparatory to completing said blade.

JAMES H. MCKEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS