US2994507A - Blade locking structure - Google Patents

Description

Aug. 1, 19 1 H. F. KELLER EI'AL BLADE LOCKING STRUCTURE Filed Jan. 25, 1959 I INVE RS HAROLD F. K LER JACK E. ME KEY United States Patent 2,994,507 BLADE LOCKING STRUCTURE Harold F. Keller, Mission, Kans., and Jack E. McCoskey,

Hickman Mills, Mo., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 23, 1959, Ser. No. 788,536

4 Claims. (Cl. 253-77) This invention relates to blading for rotary fluid utilizing machines, such as turbines, compressors and the like, more particularly to an arrangement for locking the blades in position in the blade supporting member, and has for an object to provide improved structure of this type.

It is a further object of the invention to provide a blade locking arrangement of the above type which is simple in construction, which may be inspected visually and which may be easily inserted and removed for servicing without damage to the blading, blade supporting member or the blade locking components.

Briefly, according to the invention, there is provided blade locking structure for retaining blading in a rotor disc against axial movement. The blading, in the example illustrated, is of the side entry type having a root portion of bulbous shape received in an axially extending recess provided in the rim of the disc. In blade root arrangements of this type, the blade is positively retained in the recess against radial outwardly directed movement during rotation of the disc. However, additional locking means is required to prevent slidable movement in axial direction.

In accordance with this invention, a radially inwardly facing groove is formed in the end face of the blade root and radially outwardly facing grooves of arcuate shape are formed on the rim portion of the disc so that, when the blade is disposed in the recess, the grooves are in longitudinal alignment with each other. A flexible member of longer length than the blade groove is received in the grooves, thereby to lock the blade against axial movement, and is formed with a deflectable central portion which is movable in radially inwardly direction to release the blade when it is desired to remove the blade from the disc. The spring member may also be radially inwardly deflected to permit reception within the blade groove during assembly.

A further feature of the invention resides in forming the spring member with means engaging the opposed side faces of the blade root, thereby to retain the spring member against longitudinal movement thereof during operation. Since each blade is thus locked against axial movement by an individual spring member, the blades may be individually removed for repair or replacement, if necessary, Without damage to the components.

The foregoing and other objects are effected by the invention 'as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

FIG. 1 is a perspective view of a peripheral portion of a rotor disc having a pair of blades locked therein in accordance with the invention, and a third blade removed therefrom to illustrate the novel blade locking structure;

FIG. 2 is a fragmentary sectional view taken on line II-l1 of FIG. 1;

FIG. 3 is a sectional view taken on line IIIIII of FGHZ; and

FIG. 4 is a sectional view taken on line IVIV of FIG. 2.

Referring to the drawing in detail, there is shown the peripheral rim portion of a blade supporting member or rotor disc having a plurality of blades 11 mounted "ice therein. Although the entire rotor disc has not been shown, as well known in the art, it is of circular shape and the blades 11 are mounted therein in an annular array. Also, as well known in the art, during rotation of the disc 10, the blades 11 are influenced by centrifugal forces urging them in radially outwardly direction and are further influenced by fluid flow therepast in axial courses tending to move them axially.

As well known in the art, the blades 11 ar substantially identical to each other and include a radially outwardly directed vane portion 12 of suitable airfoil cross section and a base or root portion 14. The disc 10 is provided with an annular row of recesses 16 for receiving the blade roots 14. The recesses 16 extend axially of the disc 10 and have radially outwardly facing openings. Further, as illustrated, the blade roots 14 are of the side entry type so that they may be inserted into the recesses from either side of the disc. To retain the blades 14 in the disc against the radially outwardly directed centrifugal forces, the blade roots 14 and the complementary recesses 16 are of bulbous cross section. In the illustration, this bulbous shape is shown as a conventional dove-tail.

The root portion 14 of each blade 11 has a pair of opposed side faces 18 and an end face portion 19. In the end face portion 19 there is formed a groove 20 extending from one side face to the other. The groove is open at its radially innermost end and is of generally rectangular cross-sectional shape.

The disc member 10 has a peripheral rim portion 21 of circular shape and an end face portion 22 disposed in a plane normal to the axis of rotation of the disc. The peripheral portion 21 has formed therein an annular group of arcuate grooves 23 interposed between pairs of adjacent recesses 16 and communicating at their ends therewith. The grooves 23 are of generally rectangular cross-sectional shape of somewhat wider width than the blade groove 20 and have radially outwardly facing openings formed therein.

The blade 11 is locked against axial movement relative to the disc 10 by an individual spring clip member 25. The spring clip member 25 is preferably formed of sheet material having its end portions 26 bent towards each other to impart a generally C-shape to the clip, as best shown in FIG. 3. The width of the end portions 26 of the clip is about the same as the width of the grooves 23 formed in the disc member. However, as best illustrated in FIG. 4, the clip is formed with a central portion of reduced width 27. Preferably, the width of the central portion 27 is substantially the same as the width of the groove 20 in the blade. Also, as best shown in FIGS. 1 and 4, a pair of shoulders 28 are defined at the junctions between the end portions 26 and the central portion 27, which shoulders are spaced from each other a distance equal to the space between the side faces 18 of the blade root portion.

The blade and blade locking components may be assembled in several ways. For example, in one method of assembly, the spring clip 25 is first positioned in the grooves 23 of the disc, with its central portion 27 in alignment with the recess 16. The blade 11 is then slidably received in the recess '16 from the left side of the disc, as shown in FIG. 1, until further movement is arrested by abutment of the end face 19 of the blade root with the central portion 27 of the clip. The central portion 27 of the clip is then deflected in radially inwardly direction to permit further movement of the blade to the right until the groove 20 in the blade is aligned with the longitudinal axes of the grooves 23 in the disc. The clip member is then released and allowed to spring back to its normal position, as shown in FIG. 3, thereby to move upwardly into the groove 20 of the blade. Since locked against axial movement in either direction.

Itwill further be noted by reference to FIG. 4 that the shoulders 28 of the clip engage the side faces 18 of the blade root, so that longitudinal movement of the clip in the recesses 23 is prevented, thereby assuring retention of the clip in proper position during operation of the rotor, as well as when the rotor is at rest. With this arrangement, as best shown in FIGS. 3 and 4 the clips 25 need not abut each other and may be of such length that a space 29 is provided therebetween.

Any one of the blades 11 may be individually removed for servicing, when desired, by deflecting the central portion 27 of the clip in radially inward direction. It will be noted that after assembly only the end portions of the clip are accessible, so that any suitable tool may be applied thereto at either one or both sides of the blade groove 20 to permit such deflection, whereupon the blade 11 is freely movable to the left and out of engagement with the clip.

Although the clip has been defined as having a deflectable central portion, the deflection characteristics of the central portion are enhanced by the C-shape of the clip, since the curved end portions 26 are also resilient and complement the deflection characteristics of the central portion. In fact, during removal of the clip, since the deflecting force is applied adjacent the ends of the clip, these end portions may be deflected sufliciently to permit disengagement of the clip from the blade groove. Conversely, during assembly, deflection of the clip is facilitated by applying a force to the central portion of the clip to permit such deflection.

The clips 25 may be varied in width, as desired, to provide any limited degree of axial movement to the blade. However, they are perferably formed to closely fit the grooves so that axial movement of the blades is is substantially minimized. Since the end portions 26 of the clip are easily visible after assembly, the blade locking components may be easily inspected visually for proper engagement of its components.

It will now be seen that the invention provides a highly improved blade locking structure which is simple to manufacture, yet highly reliable and eflective in operation. It will further be seen that the blade lock may be assembled and visually checked by relatively inexperienced personnel on a mass production basis.

It must also be pointed out that with the blade lock structure described above, the blade may be repeatedly removed for servicing without damage to the blade, the rotor disc or the clip.

While the invention has been shown in but one form, it will 'be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In a rotor construction, a blade member, a blade supporting member rotatable about its central axis and having a peripheral rim portion, said blade supporting member having an axially extending recess and an arcuate groove in endwise communication therewith, interlocking means to prevent radial separation of said blade member from said supporting member including a root portion received in said recess and arranged to retain said blade against radial displacement, said root portion having a groove formed therein extending circumferentially of said blade supporting member, the groove in said root portion and the groove in said blade supporting member being open-ended and facing each other, and a spring clip member received in said grooves and locking said root portion against movement in axial direction relative to said blade support member, said spring member being deflectable in radial direction to permit insertion and removal from one of said grooves and having a portion cooperating with said root portion to lock said spring member against circumferential displacement in said grooves.

2. In a rotor construction, a blade supporting member rotatable about its central axis and having a peripheral rim portion, said blade supporting member having an axially extending recess and a pair of arcuate grooves disposed on opposite sides of said recess and in endwise communication therewith, a blade member having a root portion of the interlocking side-entry type received in said recess, said root portion and said recess being'of complementary interlocking shape permitting movement of said blade in axial directions but restraining radial movement of said blade, said root portion having opposed side face portions and a groove extending therebetween, said grooves extending circumferentially of said blade supporting member, the groove in said blade member and the groove in said blade supporting member being openended and facing each other, and a spring clip member for locking said blade against movement in axial direction relative to said blade support member, said spring member being received in said blade groove and extending into the grooves of said blade supporting member and having a pair of shoulder portions cooperating with the side face portions of said root portion to lock said spring member against circumferential movement in said grooves.

3. In a rotor construction for an axial fluid flow machine, a disc member rotatable about its central axis and having a peripheral rim portion, said rim portion having an axially extending recess and a pair of radially out wardly open-ended grooves disposed on opposite sides of said recess and communicating therewith, a blade member having a radially extending vane portion and a root portion, said root portion being received in said recess, said root portion and said recess being of complementary bulbous shape and permitting axial movement of said blade but restraining said blade against radially outward movement, said root portion having a radially inwardly open-ended groove in end-to-end registry with said pair of grooves, and a O-shaped spring clip member for locking said blade against axial movement relative to said disc, said spring member being formed of flat material and having curved end portions and a central portion, said end portions being received in said pair of grooves and said central portion being received in said root groove, said end portions defining a pair of shoulders cooperating with said root portion for locking the spring member against movement in a direction transverse to the rotational axis of said disc member, said spring member being radially inwardly depressible and permitting insertion and removal of said spring member from said root groove.

4. In a rotor construction for an axial fluid flow machine, a disc member rotatable about a central axis and having a peripheral rim portion, said rim portion having an axially extending recess and a pair of radially outwardly open-ended grooves disposed on opposite sides of said recess and communicating therewith, a blade member having a radially extending vane portion and a root portion, said root portion being received in said recess, said root portion and said recess being of complementary interlocking shape permitting axial movement of said blade but restraining said blade against radially outward movement, said root portion having a radially inwardly openended groove in end-to-end registry with said pair of grooves, and an elongated spring clip member for locking said blade against axial movement relative to said disc, said spring member having end portions and a central portion, said end portions being received in said pair of grooves and said central portion being received in said root groove, said end portions defining a pair of shoulders cooperating with said root portion for locking the spring member against movement in a direction transverse to the rotational axis of said disc member, said central portion being displaceable radially inwardly relative to said end portions, whereby to permit insertion and removal of said spring member from said root groove and permitting locking and freeing the blade, respectively.

References Cited in the file of this patent UNITED STATES PATENTS Kroon Jan. 27, 1948 France Aug. 20, 1956

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