US3254831A

US3254831A - Blade ring structure

Info

Publication number: US3254831A
Application number: US271901A
Authority: US
Inventors: Berger Hans
Original assignee: BMW Triebwerkbau GmbH
Current assignee: BMW Triebwerkbau GmbH
Priority date: 1962-04-19
Filing date: 1963-04-10
Publication date: 1966-06-07
Anticipated expiration: 1983-06-07
Also published as: GB981839A

Description

June 7, 1966 H. BERGER 3,254,831

BLADE RING STRUCTURE Filed April 10, 1963 IHUEnToR Hans Ber- 9M2) Q'ITO Rn EYS United States Patent 3 Claims. c1.230-134 The present invention relates to a blade ring structure for turbo-machines having hollow blades which are connected with the disk-like side'elements of the blade ring within apertures thereof by means of flanged or peened over rim zones, and has as its object the construction thereof at the connecting places between the lateral disklike elements of the blade ring and the hollow blades.

It is known in the prior art to extend hollow blades with uniform wall thickness through apertures in the lateral disks, which apertures correspond to the contour of the blades, and to weld to the lateral disk-like elements the outwardly projecting rim of the blades or to connect these rims with the lateral discs by caulking. Additionally, it is known in the prior art to provide such blades with lugor tab-like extensions and to pass these extensions through apertures in the lateral disk-like elements corresponding to the cross section thereof and to flange or fold over these extensions.

These prior art constructions, however, entail the disadvantage of relatively poor form stability of the assembled blade ring structure. With welded connections primarily the distortion and warping both of the blades as well as of the lateral disk-like elements are very disadvantageous. Lug-type or tab-type connections are complicated from the manufacturing point of view of the blades as also their dimensional stability during operation is insuflicient, particularly with blade rings that are exposed to high operating temperatures. In this respect the occurrence of high thermal stresses and deformations is also disadvantageous with welded constructions.

The present invention aims at avoiding these disadvantages and at creating a hollow blade ring structure which, with simplest manufacture and easy connection of the blades with the lateral disk-like elements, assures the highest safety in operation. The present invention essentially consists in reducing the cross section of the blades along the line of intersection thereof with the lateral disk-like elements in the direction toward the ends thereof in a step-like manner, extending the reduced end regions of the blades through apertures in the lateral disk-like elements which apertures correspond to the reduced cross sectional contour of the blades, and by flanging or peening over the end regions of the blade protruding beyond the outer side of the lateral disk element.

The blades may be manufactured either by precisioncasting or from drawn or rolled sectional band material by cutting to length and bending of the blade contour, whereby the lateral end regions of the blade with reduced cross section are prefabricated already in the band cross section as rim strips with reduced thickness on both sides as compared to the center area thereof.

In the blade ring structure according to the present invention the hollow blades abut with the step-like offsets and with the surfaces of the end regions thereof laterally'against the lateral disk-like elements and against the internal surfaces of the apertures thereof. By reason of such an arrangement the blade receives a highgrade positive form-locking connection with the lateral disk-like elements by means of which is attained a particularly high dimensional stability of the blade ring. On the other hand, thermal stresses caused by differing thermal expansions of the blade ring parts are largely avoided by a certain yieldingness of the connection utilized in accordance with the present invention. .From this again follows the possibility of a particularly thin-walled and lightweight construction with still sufficiently rigid form. A further advantage of the present invention resides in the possibility of utilizing non-Weldable materials.

All of these advantages are obtained with relatively simple and inexpensive manufacture whereby the relatively inexpensive manufacture is not dependent on expensive installations and dies so that such manufacture is also economically feasible with the manufacture of relatively small batches, i.e., with small numbers of manufactured blades.

Accordingly, it is an object of the present invention to provide a method for manufacturing a blade ring structure for turbo-machines which is simple and inexpensive, lends itself readily to small series productions, and produces a high-grade assembled product.

Another object of the present invention resides in the provision of a method for manufacturing blade ring structures particularly for turbo-machines which permits the use of non-weldable, lightweight materials, obviates the 'need for expensive assembly installations and enables the ready maintenance of small tolerances in the manufacture and assembly.

Still another object of the present invention resides in the provision of a blade ring structure with hollow blading, particularly for turbo-machines which obviates the drawbacks and shortcomings encountered'with the prior art constructions by relatively simple and inexpensive means.

Another object of the present invention resides in the provision of a blade ring structure for turbo-machines which assures accurate maintenance of the involved tolerances as well as high rigidity in the shape thereof.

Still a further object of the present invention resides in the provision of a blade ring structure which eliminates the need of welded connections and therewith the danger of distortions, warpings, or thermal stresses.

A still further object of the present invention resides in the provision of a blade ring structure, intended to be exposed to high temperatures, which minimizes any drawbacks that may be caused by the occurrence of high thermal stresses or deformations, for example, as may be the case with welded joints.

Still another object of the present invention resides in the provision of a blade ring structure for use in a turbo-machine which permits simple manufacture and easy connection of the parts, assures a high-grade positive form-locking connection without welded joints that is capable of a limited yieldingness, and offers the possibility of utilizing relatively thin-walled and lightweight materials that need not be weldable.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

FIGURE 1 is a perspective view of a hollow blade for a blade ring structure in accordance with the present invention,

FIGURE 2 is a perspective view of the sectional band material forming the starting material for the hollow blade of FIGURE 1,

FIGURE 3 is a partial, cut perspective view of a blade ring structure provided with an inserted hollow blade, in accordance with the present invention, and

FIGURE 4 is a partial perspective view, on an enlarged scale, with parts thereof cut away, of a blade Patented June 7, 1966 a a ring structure illustrating the engagement of the blade into the lateral disk-like elements.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, reference numeral 1 designates therein a hollow blade made according to the present invention in one piece from a prefabricated sectional band material 2 (FIGURE 2), provided on both sides thereof with rim strips 2' of reduced thickness. It is possible to manufacture the blade 1 by simple operations by suitably bending the strip material to conform to the blade shape and by partial removal of the reduced connecting flange arranged at the

ends

3 and 4 within the area of the pointed trailing end portion 6 of the blade. The assembly into the lateral disk-

like elements

7 and 8 of the blade ring which consists of sheet-metal rings is also realized in a simple manner by insertion of the thinned or reduced connectingflanges 5 into apertures 9 corresponding in form and extent to these flanges and provided within the sheet-

metal rings

7 and 8. The securing of the blades 1 and the connection of the two sheet-

metal rings

7 and 8 with each other for completion of the blade ring is realized by folding or beading over the reduced connecting flanges 5. In the completed connection, the sheet-metal rings 7 and 8- are pressed by the folded connecting flanges against the step-like offset along the blade rims and are positively retained thereat in a form-locking manner. This connection produces high accuracy and form-rigidity as well as very high dimensional stability, and is largely free of thermal stresses at elevated temperatures.

While I have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications within the spirit and scope thereof and I therefore do not wish to be limited to the details shown and described herein but spanwise length to define the fluid working portion of the blade, each of said blades terminating in opposed ends, each of the said opposed ends of said hollow blades having the outer periphery thereof substantially reduced in thickness to define a shoulder stop and a continuous peripheral supporting flange for said blade end, said blade ring structure further comprising a pair of substantially flat blade suporting discs, each of said disc having a plurality of apertures therein, snugly receiving the corresponding supporting end flanges of the hollow blades therein, and each of said discs engaging the shoulder stops thereof to prevent spanwise movement of the disc relative to the blades in one direction, said flanges being outwardly turned from the hollow interior of the blades whereby said flanges tightly engage the side of the disc opposite to the side engaging said shoulder stops whereby the disc'is securely locked to the said one end of the blades to prevent separation therefrom in a direction opposite to said first direction, said hollow blades each consisting of a bent strip of material closed upon itself, said apertures in said supporting discs corresponding to the contour of the blade at the peripheral supporting flange thereof.

3. A blade ring structure for a turbo-machine, said blade ring structure comprising a plurality of precision cast hollow blades, each of said hollow blades having a substantially constant thickness throughout its spanwise length to define the fluid working portion of the blade,

each of said blades terminating in opposed ends, each of intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim: I

1. A blade ring structure for a turbo machine, said blade ring structure comprising a plurality of hollow blades, each of said hollow blades having a predetermined substantially constant thickness throughout its spanwise length to define the fluid working portion of the blade, each of said blades terminating in opposed ends, each of the said opposed ends of said hollow blades having the outer periphery thereof substantially reduced in thickness to define a shoulder stop and a continuous peripheral supporting flange for said blade end, said blade ring structure further comprising a pair of substantially flat blade supporting discs, each of said discs having a plurality of apertures therein, snugly receiving the corresponding supporting end flanges of the hollow blades therein, and each of said discs engaging the shoulder stops thereof to prevent spanwisemovement of the disc relative to the blades in one direction, said flanges being outwardly turned so as to tightly engage the side of the disc opposite to the side engaging said shoulder stops whereby the disc is securely locked to the said one end of the blades to prevent separation therefrom in a direction opposite to said first direction.

2. A blade ring structure for a turbo machine, said blade ring structure comprising a plurality of hollow blades, each of said hollow blades having a predetermined substantially constant thickness throughout its the said opposed ends of said hollow blades having the outer periphery thereof substantially reduced in thickness to define a shoulder stop and a continuous peripheral supporting flange for said blade end, said blade ring structure further comprising a pair of parallel substantially flat blade supporting discs, each of said discs having a plurality of apertures therein, snugly receiving the corresponding peripheral supporting flanges of the hollow blades therein, and each of said disc engaging the shoulder stops thereof to prevent spanwise movement of the disc relative to the blades in one direction, said flanges being outwardly turned so as to tightly engage the side of the disc opposite to the side engaging said shoulder stops whereby the disc is securely locked to the said one end of the blades to prevent separation therefrom in a direction opposite to said first direction.

References Cited by the Examiner UNITED STATES PATENTS 1,362,853 12/1920 Darling 253--77 1,706,118 3/1929 Hopkins 29512 1,825,622 9/1931 Kennedy 230l34.45 1,876,518 9/1932 Mathis 29-l56.8 1,983,201 12/1934 Van Rijswijk 230l34.45 2,337,619 12/1943 Miller 253'77 2,771,622 11/ 1956 Thorp 253-77 3,074,151 1/1963 Kroeckel 23--156.8

.FOREIGN PATENTS 608,797 4/ 1926 France. 661,178 11/1951 Great Britain.

SAMUEL LEVINE, Primary Examiner.

JOSEPH H. BRANSON, IR., Examiner.

H. F. RADUAZO, Assistant Examiner.

Claims

1. A BLADE RING STRUCTURE FOR A TURBO MACHINE, SAID BLADE RING STRUCTURE COMPRISNG A PLUALITY OF HOLLOW BLADES, EACH OF SAID HOLLOW BLADES HAVING A PREDETERMINED SUBSTANTIALLY CONSTANT THRICKNESS THROUGHOUT ITS SPANWISE LENGTH TO DEFINE THE FLUID WORKING PORTION OF THE BLADE, EACH OF SAID BLADES TERMINATING IN OPPOSED ENDS, EACH OF THE SAID OPPOSED ENDS OF THE HOLLOW BLADES HAVING THE OUTER PERIPHERY THEROF SUBSTANTIALLY REDUCED IN THRICKNESS TO DEFINE A SHOULDER STOP AND A CONTINUOUS PERIPHERAL SUPPORTING FLANGE FOR SAID BLADE END, SAID BLADE RING STRUCTURE FURTHER COMPRISING A PAIR OF SUBSTANTIALLY FLAT BLADE SUPPORTING DISCS, EACH OF SAID DISCS HAVING A PLRUALITY OF APERTURES THEREIN, SNUGLY RECEIVING THE CORRESPONDING SUPPORTING END FLANGES OF THE HOLLOW BLADES THEREIN, AND EACH OF SAID DISCS ENGAGING THE SHOULSER STOPS THEREOF TO PREVENT SPANWISE MOVEMENT OF THE DISC RELATIVE TO THE BLADES IN ONE DIRECTION, SAID FLANGES BEING OUTWARDLY TURNED SO AS TO TIGHTLY ENGAGE THE SIDE OF THE DISC OPPOSITE TO THE SIDE ENGAGING SAID SHOULDER STOPS WHEREBY THE DISC IS SECURELY LOCKED TO THE SAID ONE END OF THE BLADES TO PERVENT SEPARATION THEREFROM IN A DIRECTION OPPOSITE TO SAID FRIST DIRECTION.