JPH07332015A - How to repair a steam turbine impeller - Google Patents

Abstract

PURPOSE:To firmly fix clamps without using any pin by removing a blade from a bedding part of a damaged wheel, fixing the trapezoidal clamps, which are brought into contact with the adjacent blades on their slanting surfaces, in the wheel part, and receiving a radius directional load on the slanting surfaces. CONSTITUTION:When damage such as a crack is caused in a bedding part, of a wheel 1, a blade 3 in this part is removed and a part, of a bedding part 11 of each blade 3 adjacent to the damaged blade is cut off, and trapezoidal clamps 12 are fixed from both sides of the wheel 1 by means of a combination bolt 13. If the wheel 1 is rotated at a high speed, centrifugal force is applied to the trapezoidal stopping clamps 12 in the radius direction, and the centrifugal force is supported by slanting surfaces machined in the bedding parts 11 of the blades 3 adjacent to the clamps 12. In this repairing method, the clamps can be firmly fixed even when it is difficult to drive a pin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine,
In particular, the present invention relates to a method of repairing an impeller used for temporary repairs when a wheel of a rotor shaft is damaged. The present invention relates to a repair method for a steam turbine impeller.

[0002]

2. Description of the Related Art FIG. 5 shows the shape of a wheel of an impeller of a general steam turbine. On the outer periphery of a wheel 1 provided on a rotor shaft (not shown), an implanting portion 2 is provided which forms a circumferential groove for attaching the blade 3. A notch 4 shown in FIGS.
The blades 3 are attached to the wheel 1 by fitting the blades 3 into the wheel implant portions 2 from the notches 4 and shifting them in the circumferential direction. A structure is often used in which the blade 3 is assembled on the entire circumference, and then the stopper plate 5 shown in FIGS.

In a steam turbine of a thermal power plant, a nuclear power plant, a geothermal power plant, or the like, an impeller exposed to a wet steam atmosphere may have cracks or the like in the implant portion 2 of the wheel 1 due to corrosion fatigue or stress corrosion cracking. Damage often occurs. Examples of damage to these implants 2 are shown in FIGS. 8 (a) and 8 (b). In the figure, 10 indicates a crack.

Conventionally, as a repair method in such a case, the blade 3 of the portion damaged by a method such as cutting is extracted,
As shown in FIG. 9, the implant 2 of the damaged portion is cut into a shape similar to the notch 4 of FIG.
Is attached to the wheel and fixed using the repair pin 9.

[0005]

However, even if an attempt is made to fix the pin 9 to the wheel to which the repair stopper 8 is attached, when the damaged portion covers a wide range, the scraped portion becomes large and there is no portion to hit the pin 9. is there. Further, although the pin 9 receives a load in the radial direction, the stress of the wheel 1 hitting the pin 9 becomes high, and there is a drawback that the repair method lacks reliability.

An object of the present invention is to provide a method of repairing a steam turbine impeller in which a stopper plate can be firmly fixed without using a pin when fixing the stopper plate to a wheel.

[0007]

SUMMARY OF THE INVENTION The present invention removes a blade from a damaged wheel implant and affixes a trapezoidal clasp that contacts the blade adjacent to the wheel on a slope to provide radial loading. Is to be received on the slope.

In another invention, instead of the trapezoidal stopper, a stopper having a notch is fixed to the inner diameter side of the adjacent blades. Further, in another invention, instead of the trapezoidal stopper, a stopper which is fixed by a bolt is fixed.

[0009]

According to this repair method, even if it is difficult to hit the pin due to the damaged state of the wheel, the trapezoidal clasp can firmly fix the clasp without using the pin.

[0010]

Embodiments of the present invention will be described with reference to FIGS. In FIG. 2, when the implant portion 2 of the wheel 1 is damaged, for example, when a crack 10 occurs, the blade 3 of that portion is removed and a portion 11a of the implant portion 11 of the adjacent blade 3 is removed.
From the outside. Next, as shown in FIG. 1, trapezoidal stoppers 12 are assembled from both sides of the wheel 1 and fixed by bolts 13.

When the wheel 1 rotates at high speed, the trapezoidal clasp 12 receives a centrifugal force in the radial direction. This power is a stopper
It is supported by a beveled surface on the implant 11 of the blade 3 adjacent to 12. Since the clasp 12 is assembled from both sides of the wheel 1 in the axial direction and is assembled by the bolt 13 located outside the wheel 1, the crack 10 of the wheel 1
Almost no force is applied to the occurrence part of.

Therefore, according to this blade repair method, reliable blade repair can be performed even when the conventional blade repair method is difficult due to the damage condition of the wheel 1. Another embodiment of the present invention will be described with reference to FIG.

In the present embodiment, when the wheel 1 is damaged, the blade 3 of that portion is removed, and the groove 14 is formed in the wheel 1 inside the implanting portion 11 of the adjacent blade 3. The repair stopper 15 is provided with a convex portion 16 to be fitted into the groove 14 inside the blade 3.

In this repair method, the load of the stopper plate 15 in the radial direction is supported by the implant portion 11 of the blade 3 through the convex portion 10 of the stopper plate 15 which is inserted into the groove 14 inside the adjacent blade 3. Further, another embodiment will be described with reference to FIG.

In this embodiment, the blades 3 are removed and screw holes 17 are formed in the wheel 1 between the adjacent blades 3. Screw hole
The depth of 17 is formed deeper than the damaged part. The repair clasp 18 is fixed by a fixing bolt 19. In this repair method, the radial load of the clasp 15 is supported by the bolt 19.

[0016]

As described above, according to the present invention, a trapezoidal stopper which is in contact with a blade adjacent to a wheel portion on an inclined surface or a stopper having a notch on the inner diameter side of the adjacent blade or a stopper fixed by a bolt is fixed. Therefore, even if it is difficult to hit the pin due to the damaged condition of the wheel, the stopper plate can be firmly fixed.

[Brief description of drawings]

FIG. 1 is a process diagram showing a repair method according to the present invention.

FIG. 2 is a process diagram showing a repair method according to the present invention.

FIG. 3 is a process drawing showing another embodiment of the present invention.

FIG. 4 is a process drawing showing another embodiment of the present invention.

FIG. 5 is a perspective view showing a main part of a conventional steam turbine impeller.

FIG. 6 is a perspective view showing a main part of a conventional steam turbine impeller.

FIG. 7 is a process diagram showing a conventional repair method.

FIG. 8 is a diagram showing an example of damage to a wheel.

FIG. 9 is a process diagram showing a conventional repair method.

[Explanation of symbols]

 1 Wheel 3 Blades 11 Implants 12, 15, 18 Clasps 13, 19 Bolts 14 Grooves 16 Convex parts

Claims (3)

[Claims] 1. A vane is removed from an implant portion of a damaged wheel, and a trapezoidal clasp contacting the vane adjacent to the wheel portion on a slope is fixed, and a load in the radial direction is received on the slope. A method of repairing a steam turbine impeller characterized by the above. 2. The method for repairing a steam turbine impeller according to claim 1, wherein instead of the trapezoidal stopper, a stopper having a notch is fixed on the inner diameter side of the adjacent blades. 3. The method of repairing a steam turbine impeller according to claim 1, wherein a stopper metal fixed by a bolt is fixed instead of the trapezoidal stopper metal.