JP2854722B2 - Steam turbine blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine,
More particularly, it relates to a steam turbine blade having an integrally formed shroud.

[0002]

2. Description of the Related Art Conventional steam turbines have used blades having a shroud integrally molded at the tip. For example,
In the moving blade shown in FIGS. 3A and 3B, the blade root 12, the blade 13, and the shroud 14 are integrally formed, and are fitted and fixed to the impeller 11. Further, as shown in FIGS. 3C and 3D, the circumferential end faces of the blade root 12 and the shroud 14 are inclined in the same direction with respect to the axial direction, and the inclined surfaces of both the blade root 12 and the shroud 14 are formed. 16,1
7 is assembled with the opposing inclined surfaces of the adjacent moving blades and the surface pressure 8. 4 (a) and 4 (b), the blade root 12, the blade 13 and the shroud 14 are integrally formed, but are integrally connected to the impeller 11 by a connecting pin 19 and fixed. Have been. As shown in FIGS. 4C and 4D, the blade is assembled with the shroud 14 adjacent to one inclined surface 17 of the shroud 14 with a surface pressure 8. In any case, the object is to suppress the blade vibration by making the blade continuous all around.

[0003]

FIG. 3 (a)
In the moving blade structure shown in FIGS. 1 and 2B, as shown in FIGS. 1C and 1D, a rotating moment 9 for rotating the moving blade by the surface pressure 8 applied to the inclined surfaces 17 and 16 respectively. And 10 are generated on the shroud 14 and the blade root 12, respectively, and are supported by the contact surfaces 18 between the blade root 12 and the impeller 11. In the moving blade structure shown in FIGS. 4A and 4B, as shown in FIGS. 4C and 4D, a rotational moment 9 for rotating the moving blade by the surface pressure 8 applied to the inclined surface 17 is used. Is generated, but the rotational moment 9 is supported by the connecting pin 19 with the impeller 11. Therefore, in the moving blade having such a structure, an excessively large additional force acts on the contact surface 18 between the shroud 14 and the impeller 11 or the connecting pin 19 connecting the blade root 12 and the impeller 11, and There is a problem that deformation occurs and strength is reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate a rotational moment for rotating a moving blade, and to integrally mold an impeller and a pin without applying an additional force and without reducing strength. To provide a steam turbine blade having a shroud. [Configuration of the Invention]

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a steam turbine blade having a shroud integrally formed with a blade at a tip thereof, wherein a blade root portion of the blade and a rotational direction of the shroud are provided. By forming a part of both end surfaces as inclined surfaces inclined in opposite directions to the axial direction at the blade root and shroud, rotation generated when adjacent blades are assembled with surface pressure on inclined surfaces The present invention is characterized in that the moment is offset in a direction opposite to each other between the blade root and the shroud.

[0006]

According to the present invention, the rotational moments acting on the steam turbine blades are mutually reversed at the blade root portion and the shroud, and cancel each other. Therefore, no additional force is applied to the impeller and the pin as in the prior art, so that the strength of the moving blade is not reduced and the effect of suppressing vibration is not impaired.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a steam turbine blade according to an embodiment of the present invention. As shown in FIG. 1, the blade 1 has a blade root 2, a blade 3, and a shroud 4 integrally formed. The steam inlet sides of both end surfaces 5 in the rotation direction of the blade root 2 are inclined surfaces 6 inclined with respect to the axial direction. On the other hand, on the steam outlet side of both ends in the rotation direction of the shroud 4, an inclined surface 7 opposite to the inclined surface 6 of the blade root portion 2 with respect to the axial direction is provided.

The rotor blade 1 molded in such a manner is shown in FIG.
As shown in (a), the shroud 4 is assembled so that the inclined surface 7 of the shroud 4 maintains a predetermined surface pressure 8 with the inclined surface of the adjacent moving blade. Further, as shown in FIG. 2B, the inclined surface 6 of the blade root portion 2 has a predetermined surface pressure 8
Assemble to keep Further, the moving blade 1 is configured to form one moving blade group that is continuous over the entire circumference, thereby suppressing vibration of the moving blade.

According to this embodiment, as shown in FIGS. 2A and 2B, a rotational moment 9 generated in the shroud 4 by the surface pressure 8 and a rotational moment generated in the blade root 2 by the surface pressure 8 Since the directions are opposite to each other,
Both moments cancel each other out. Therefore,
As in the prior art, no additional force acts on the connecting pin connecting the blade root and the impeller, so that the strength of the connecting pin does not decrease. Also, no additional force acts on the contact surface between the impeller and the moving blade. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the scope of the invention.

[0011]

As described above, according to the present invention,
Since no additional force is applied to the impeller and the connecting pin without impairing the effect of suppressing the vibration of the moving blade at all, it is possible to provide a group of highly reliable steam turbine moving blades around the entire circumference.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of the present invention.

2A is a diagram schematically showing the pressure and the rotational moment acting on the shroud of FIG. 1, and FIG. 2B is a diagram schematically showing the pressure and the rotational moment acting on the blade root of FIG. FIG.

FIG. 3A is a perspective view of a conventional moving blade, and FIG.
Is a partial cross-sectional view in which a rotor blade is assembled to an impeller, FIG. 4C schematically shows pressure and rotational moment acting on a shroud, and FIG. 4D shows pressure and rotational moment acting on a blade root. The figure which shows typically.

FIG. 4 (a) is a perspective view of another conventional moving blade, FIG. 4 (b) is a partial cross-sectional view of the moving blade assembled to the impeller, and FIG. 4 (c).
FIG. 3 is a diagram schematically showing a pressure and a rotational moment acting on a shroud, and FIG. 3 (d) is a diagram schematically showing a pressure and a rotational moment acting on a blade root.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Moving blade, 2 ... Blade root part, 3 ... Blade part, 4 ... Shroud, 5
... end face of blade root rotation direction, 6 ... blade root slope, 7 ... shroud slope, 8 ... surface pressure, 9 ... rotational moment generated in shroud, 10 ... rotational moment generated in blade root,
11 ... impeller, 18 ... rotor / wheel contact surface, 19 ... connecting pin.

Claims (1)

(57) [Claims] 1. A steam turbine blade having a shroud integrally formed with a moving blade at a tip thereof, a blade root portion of the moving blade and a part of both end surfaces in a rotational direction of the shroud are axially separated by the blade root portion and the shroud. On the other hand, by making the inclined surfaces inclined in opposite directions to each other, the rotating moment generated when the adjacent moving blades are assembled with the surface pressure on the inclined surface becomes opposite to each other at the blade root portion and the shroud. A steam turbine blade characterized by being configured to cancel each other.