JP2000297605A - Movable blade fastening device on fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening device that enables easy processing and space- saving, surely fastening an operating wheel and movable blade at a position in the axial direction with high strength. SOLUTION: A lateral hole in the axial direction and a longitudinal hole, penetrating from a bottom portion of a dovetail 9 to the wheel center connecting to the lateral hole, are processed on a movable blade dovetail portion. A hemispherical groove is processed on a wheel 1 to be located at the same position as the longitudinal hole penetrating from the bottom portion of the dovetail 9 when assembled. After assembling a movable blade 3 and the wheel 1, a steel ball 6 is guided to a coupling line between the movable blade dovetail bottom portion and the wheel 1 by inserting the steel ball 6 from the lateral hole processed on the movable blade 3 and to a wheel groove portion through the longitudinal hole. The position of the operating movable blade 3 and wheel 1 in the axial direction is fastened, by inserting a knock pin 7 into the lateral hole of the movable dovetail portion and fixing the steel ball 6 to the coupling line between the movable blade dovetail bottom portion and the wheel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a moving blade used in a fluid machine such as a steam turbine, a gas turbine, and an axial compressor to a wheel.

[0002]

2. Description of the Related Art As a general moving blade fixing device in the axial direction, a device for fixing a plate by sandwiching a plate on a groove fitting surface between a moving blade and a wheel, inserting the moving blade, and bending both ends thereof is known. 1
Proposed in 19392.

[0003] Alternatively, an apparatus for fixing the rotor blade dovetail to the bottom using a taper pin has been proposed in Japanese Patent Application Laid-Open No. Sho 62-55402.

Further, as a simple fixing method, the rotor blade is fixed by caulking a wheel near a blade dovetail.

[0005]

SUMMARY OF THE INVENTION
In the fixing device for the wheel, there is a problem that a gap is generated between the both end surfaces of the wheel and the plate due to the R portion that can be formed at the time of plate bending, which causes play of the moving blade during turbine operation.

Further, the fixing device disclosed in Japanese Patent Application Laid-Open No. 62-55402 has a problem that if the length of the taper pin is longer than the wheel interval, it becomes impossible to assemble.

Further, the fixing by caulking the wheel has a problem in strength because the caulked portion of the wheel is shaved during disassembly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device in which the axial position of a wheel and a moving blade in an operating state can be securely fixed with high strength in an operating state in consideration of these points, and the machining is easy and requires a small space. Is to do.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a blade dovetail portion having an axial lateral hole and a vertical hole penetrating from the dovetail bottom toward the center of the wheel connected to the axial hole, and the wheel has a vertical hole penetrating from the dovetail bottom. By processing the hemispherical groove that will be in the same position at the time of assembly and further assembling the moving blade and the wheel, inserting a steel ball from the horizontal hole processed into the moving blade, and inserting a steel ball into the wheel groove through the vertical hole, After inserting a steel ball at the joint between the rotor blade dovetail bottom and the wheel, insert a knock pin into the side hole of the rotor blade dovetail section, and fix the steel ball at the joint between the rotor blade dovetail bottom and the wheel. Fix the axial position of the bucket and wheel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail. FIG. 1 is a partial cross-sectional view of a connecting portion between the rotor blade 3 and the wheel 1, and a dovetail 9 having a shape just fitted into an axial dovetail groove 8 provided in the wheel 1.
Are formed at the bases of the three moving blades, and they are joined by fitting each other. In order to keep the moving blade 3 inserted into the wheel 1, a fixing device is provided to the moving blade 3 and the wheel 1.

FIG. 4 shows a moving blade side fixing device. The moving blade 3 is provided with a horizontal hole 5 extending from the end face of the dovetail 9 in the axial direction of the wheel 1 and a vertical hole 4 penetrating from the horizontal hole 5 to the bottom of the dovetail 9 of the moving blade 3. I can. The horizontal hole 5 and the vertical hole 4 are steel balls 6 shown later.
Pass smoothly, and the hole diameter should not be too large.

Further, at the axial position of the wheel 1 where the center line of the horizontal hole 5 and the vertical hole 4 intersect, the dovetail 9 of the vertical hole 4
It is assumed that the height from the bottom surface is equal to the radius of the steel ball 6. Further, the horizontal hole 5 can be drilled at a position satisfying the height condition of the vertical hole 4 at the axial position of the wheel 1 where the center line of the horizontal hole 5 and the vertical hole 4 intersect.

FIG. 7 shows a wheel-side fixing device, in which a lateral hole 5 of the rotor blade 3 is previously provided on the upper surface of the dovetail groove 8 of the wheel 1.
A hemispherical groove 2 extending toward the center of the wheel 1 is formed at an axial position of the wheel 1 where the center line of the vertical hole 4 intersects with the center line of the wheel 1.

The hemispherical groove 2 has a center at the bottom of the dovetail 9 of the moving blade 3 and has a diameter equal to the diameter of the steel ball 6 in the operating state of the fluid machine.

After assembling the wheel 1 and the rotor blade 3, the wheel is rotated so that the vertical hole 4 is located directly above the wheel 1, a steel ball 6 is inserted from the horizontal hole 5, and the dovetail 9 of the rotor blade 3 is inserted from the vertical hole 4 to the bottom surface. , The steel ball 6 fits into the hemispherical groove 2.

Further, the distance from the end face of the dovetail 9 of the rotor blade 3 having the same diameter as the horizontal hole 5 and having the horizontal hole 5 to the axial position of the wheel 1 where the center line of the horizontal hole 5 and the vertical hole 4 of the rotor blade 3 intersects. A long dowel pin 7 approximately equal to the entire length of the lateral hole 5 is inserted into the lateral hole, and the dovetail 9 end face of the bucket 3 is fixed by caulking. Here, a screw hole is formed in advance on the end face of the knock pin 7 in consideration of disassembly.

As described above, the wheel 1 in the driving state
And the rotor blades 3 have their axial positions fixed by steel balls 6.

When disassembling the wheel 1 and the rotor blade 3,
The swaged portion of the end face of the dovetail 9 of the rotor blade 3 is shaved, and the knock pin 7 is pulled out using the screw hole.

Further, the wheel 1 is rotated so that the vertical hole 4 is directly below the wheel 1. As a result, the steel ball 6 comes out of the hemispherical groove 2 through the vertical hole 4 to the horizontal hole 5, and the wheel 1
Can be removed from the moving blade 3.

As another embodiment, this structure is also possible by drilling the vertical hole 4 and the horizontal hole 5 in the wheel 1 and drilling the hemispherical groove 2 at the bottom of the dovetail 9 of the bucket 3.

Further, the hemispherical groove 2 provided in the dovetail groove 8 of the wheel 1 is extended in a direction perpendicular to the wheel axis direction with respect to the center position as a laterally elongated groove, so that a margin is provided in a direction perpendicular to the wheel groove. To facilitate the assembly operation.

Furthermore, the spherical groove 2 provided in the dovetail groove 8 of the wheel 1 can be changed to a conical groove formed by processing with a drill tip, thereby simplifying the processing operation.

The fixing device according to the present invention can be assembled without exceeding the axial length of the wheel 1 if the distance between the front and rear sections of the wheel 1 is longer than the length of the knock pin 7 in the operating state.

[0024]

As described above, according to the present invention, the axial space of the wheel can be further reduced as compared with the conventional fixing device.

That is, since the axial force acting on the rotor blade can withstand the shear strength of the steel ball, it is necessary to use a shaft having a sufficiently small steel ball diameter that can be accommodated in the limited space above the dovetail groove. Can withstand directional forces. Therefore, unlike the conventional type, there is no need for an extra axial space for fixing in the axial direction.

Further, the structure is simpler than that of the conventional fixing device, and it is easy to manufacture and assemble.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the entire structure of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a side view seen from the direction of arrow A in FIG. 1;

FIG. 4 is a front view of a moving blade.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a side view as seen from the direction of arrow B in FIG. 4;

FIG. 7 is a sectional view of a wheel.

FIG. 8 is a plan view of a wheel.

FIG. 9 is a side view as seen from the direction of arrow C in FIG. 7;

[Explanation of symbols]

1 ... wheel, 2 ... hemispherical groove, 3 ... rotor blade, 4 ... vertical hole,
5 ... side hole, 6 ... steel ball, 7 ... knock pin, 8 ... dovetail groove, 9 ... dovetail.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mitsuo Kobori 3-2-2, Sachimachi, Hitachi-shi, Ibaraki F-term in Hitachi Engineering Services Co., Ltd. (Reference) 3G002 FA04 FA08 FA10 FA11 FB02 FB06

Claims (4)

[Claims] 1. A structure in which a dovetail of a moving blade is axially inserted into a dovetail groove provided in a wheel and a moving blade is mounted on the wheel, wherein the dovetail portion of the moving blade is axially inserted from an axial end face. The dovetail groove is provided with a lateral hole extending therethrough and a longitudinal hole connected therewith and penetrating to the center of the wheel to the bottom of the dovetail when assembling the wheel and the moving blade, and having a center line concentric with the longitudinal hole when assembling the wheel and the moving blade. After the blade is inserted into the wheel, the blade is inserted into the wheel, the steel ball is inserted into the groove provided in the dovetail groove from the lateral hole through the vertical hole, and then the knock pin is inserted into the lateral hole, whereby the wheel in an operating state is obtained. A fixing device that fixes the axial position of the rotor and blade. 2. The fixing device according to claim 1, wherein the depth of the groove is set so that the boundary surface between the moving blade and the wheel passes through the center of the steel ball, and the axial position of the wheel and the moving blade is fixed. apparatus. 3. The fixing device according to claim 1, wherein the horizontal hole and the vertical hole are provided in a side surface of the wheel, and the bucket dovetail is provided with a groove to achieve the same function as in the first embodiment. 4. A wheel and a moving blade according to claim 1, wherein said steel ball is made of a material having a mechanical strength equal to or higher than that of the steel ball, such as ceramics, Ni-based alloy and Co-based alloy. A fixing device that fixes the axial position.