JPH06264702A - Turbine blade connecting device - Google Patents

Abstract

(57) [Summary] [Purpose] Set the center line of the lugs facing the adjacent turbine rotor blades to an appropriate position. [Structure] Center lines 8 and 8 of lugs 2a and 2a facing each other
Are distributed from the base line X and are set so as to be located in opposite directions to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine rotor blade coupling device capable of stabilizing and effectively suppressing vibration of a turbine rotor blade during operation.

[0002]

2. Description of the Related Art An excessive centrifugal force acts on a moving blade of a turbine at a high speed, so that the stress of each portion of the moving blade of the turbine is designed to have a sufficient margin with respect to an allowable stress of a material when the turbine is designed. There is. However, in recent years, turbine blades, especially low-pressure final-stage blades, have been lengthened from the perspectives of improving turbine efficiency, increasing capacity, and downsizing power generation units. There is also an extreme design not found in. On the other hand, in recent years, with the increase in base load operation of nuclear power generation, thermal power turbines are often used for adjusting the load of electric power. This thermal turbine for load adjustment is operated such that it is frequently started and stopped on a daily basis, and is operated at a low load that is far below the design point of the turbine.

When designing a long-blade turbine moving blade, generally, at the rated rotation speed, the blade's natural frequency is sufficiently detuned so that it does not match an integral multiple of the rotation speed. If it is stopped frequently, the natural frequency of the blade and the rotational speed component will resonate when the rotational speed goes up or down,
Large vibration stress may occur on the blade. Further, in operation under low load conditions, eddy current or turbulence of flow due to flow separation acts on the turbine rotor blade as an exciting force, which may increase vibration stress of the turbine rotor blade.

In particular, the turbine rotor blade on the final stage blade side becomes a long blade, and it is inevitable that the turbine rotor blade will be constantly exposed to a severe environment in terms of both static stress and vibration stress. A typical method for attenuating the vibration of a turbine rotor blade is a turbine rotor blade coupling device for coupling adjacent blades by forming a through hole in the center of each blade and passing a tie wire through each through hole. . In this case, the centrifugal force acting on the tie wire suppresses the vibration of the turbine rotor blade by utilizing the surface friction between the tie wire and the inner surface of the through hole.

Another representative example is a turbine blade connecting device described in Japanese Patent Publication No. 52-18841. As shown in FIG. 6, this connecting device forms a boss 2 on the blade surfaces of the turbine rotor blade 1 which face each other, and further projects a boss 2 a on the boss 2.
(Hereinafter referred to as a lug), opposing lugs are connected by a tubular connecting piece (hereinafter referred to as a sleeve) 3, and adjacent turbine moving blades 1 are connected to each other (hereinafter referred to as a lug sleeve). Called the connection structure). This connecting device is also a lug 2 generated by centrifugal force acting on the sleeve 3.
The surface friction between a and the sleeve 3 suppresses the vibration of the turbine rotor blade 1.

[0006]

In the conventional turbine rotor blade connecting device, when the turbine blades are connected by the above-mentioned tie wire, the stress around the through hole of the blade effective portion becomes high. In particular, the stress of the blade can be locally close to the strength of the blade material due to the increase of the centrifugal force due to the lengthening of the turbine blade, and the stress concentration always occurs around the tie wire hole. This stress concentration is generally reduced by increasing the thickness of the blade around the tie wire hole. However, another problem with long blades is that the untwisting of the blades due to centrifugal force causes a bending moment in the tie wire. Bending stress due to untwisting of the blade, bending stress due to centrifugal force of the tie wire itself, and vibration of the blade may be added to cause breakage of the tie wire. In order to reduce the phenomenon in which the tie wire is bent by the untwist of the blade due to this centrifugal force, the diameter of the through hole of the blade effective portion is enlarged. However, excessive enlargement of the diameter of the through-hole reduces the strength of the blade effective portion, promotes the entry of foreign matter between the through-hole and the tie wire, and may reduce the vibration damping action, which is not preferable. In addition, corrosion products in the steam may accumulate around the tie wire holes and reduce the blade material strength.

By the way, in the turbine rotor blade coupling device of the lug / sleeve coupling structure, since there is no through hole in the blade surface, there is no concern of stress concentration, and it is widely used as an actual machine.
The turbine blade connecting device of this lug / sleeve connecting structure will now be described in more detail.

As shown in FIG. 7, a turbine blade connecting device having a lug / sleeve connection structure, which has been conventionally used, has a structure in which, as shown in FIG. The center lines 8, 8 of the lugs 2a, 2a provided on the above are aligned with each other to cap the sleeve 3, and at the time of rated rotation, the center lines 8, 8 are moved to a given amount D under the influence of untwist. Then, the type that restrains the movement with the sleeve 3,
Further, as shown in FIG. 8, when assembling, the lugs 2a,
There is a type in which the center lines 8 and 8 of the lugs 2a are set to be offset by a given amount D and the center lines 8 and 8 of the lugs 2a and 2a are made to coincide with each other at the rated rotation.

However, in both the former and latter types, the inner diameter of the sleeve 3 should be made large in consideration of the given amount D by which the center lines 8, 8 of the lugs 2a, 2a move. Therefore the inner wall of the sleeve 3 and the lug 2
A gap is formed between the side walls of a and 2a. When a gap is formed, the corrosion products and foreign substances mixed in the steam accumulate, resulting in scratches and corrosion on the contact surface between the lug and sleeve, which reduces the strength of the material and the damping effect. There was a risk of being invited.

In consideration of such circumstances, the present invention maintains the basic concept that the center line of the lugs provided on the blade surfaces of the turbine rotor blades facing each other moves from the time of assembly to the time of rated rotation, but By setting the center line to the proper position,
It is an object of the present invention to disclose a turbine blade connecting device that achieves an excellent connecting effect by minimizing the inner hole diameter of the sleeve that covers the lugs.

[0011]

In order to achieve this object, the invention described in claim 1 forms a boss on the blade surfaces of a large number of turbine rotor blades mounted on the outer periphery of a turbine rotor, which face each other. However, lugs are provided at both ends of these bosses in the axial direction of the bosses, and in a connecting device of turbine moving blades that enables possible connection of adjacent turbine moving blades with a sleeve that covers the lugs. When the turbine rotor blades are stationary and the turbine rotor is stationary, the center lines of the opposing lugs move so that the center lines of the opposing lugs move to the opposite positions to those of the opposing lugs, with the base lines where the center lines of the opposing lugs coincide. It is characterized by setting the center line. Further, the invention described in claim 2 is characterized in that the center lines of the mutually opposing lugs are set so that the center lines of the mutually opposing lugs move to positions which are opposite to each other by the same amount.

[0012]

In the invention described in claim 1, the total amount of movement of the center lines of the opposing lugs is the same as in the prior art,
Since the movement of the center lines of the individual lugs is based on the base line where the center lines of the lugs facing each other coincide, the movement amount of the center lines of the individual lugs can be made smaller than in the prior art. Therefore, the gap between the lug and the sleeve can be made smaller than before, and the infiltration of foreign matter and corrosion products can be prevented as much as possible.

According to the second aspect of the present invention, the lugs of the mating lugs are moved so that the lugs of the mating lugs move to the opposite equidistant positions with the base lines of the lugs facing each other as the boundaries. Since the center line is set, the inner hole diameter of the sleeve that covers the lugs can be made axially symmetric, and the manufacture thereof can be facilitated and downsized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turbine rotor blade connecting device according to the present invention will be described with reference to FIGS. FIG. 1 shows a turbine impeller provided with a turbine rotor blade connecting device according to the present invention. In this turbine impeller, turbine rotor blades 1, 1 are implanted as a turbine rotor on an outer peripheral portion of a rotor wheel 9 via an implanting portion 10.

A boss 2 and a lug 2a are integrally or integrally provided with the blade surface in the center between adjacent blades of the turbine rotor blades 1, 1, and these boss 2 and lug 2a are capped by a sleep 3. The turbine rotor blades 1 and 1 are movably connected.

FIG. 2 is a plan view showing a turbine blade connecting device according to the present invention, showing the turbine rotor blades 1, 1 in an assembled state at rest before untwisting. That is, the bosses 2 are formed on the blade surfaces of the turbine rotor blades 1, 1 that face each other.
2 is provided so as to project, and the lugs 2a, 2 are provided along the boss axis.
a is extended. The center lines 8 and 8 of the lugs 2a and 2a are set in advance to the left and right with a base line X where the center lines 8 and 8 coincide with each other as a boundary. The sleeve 3 is capped on the lugs 2a, 2a having the center lines 8, 8 deviated from the base line X, forming gaps 6, 6 between the sleeve 3 and the bearing surfaces 5, 5 of the bosses 2, 2. These gaps 6 and 6 are sleeve 3
As an assembly allowance when crowning
7 shows the behavior of the sleeve moving from the alternate long and short dash line to the solid line when the turbine blade receives untwist. As shown in (), this is an indispensable dimension for the peripheral wall of the sleeve 3 to act as a frictional force on the side walls of the lugs 2a, 2a when the turbine rotor blades 1, 1 are untwisted at the rated rotation. However, if the clearances 6 and 6 are provided with an excessive margin, the sleeve 3 will fall out of the lugs 2a and 2a, so that it is kept to the minimum necessary.

FIG. 3 is a cross-sectional view of a turbine blade connecting device, in which the lug 2a integrally or integrally provided with the boss 2 and the sleeve 3 are fitted to each other along the inner peripheral wall of the sleeve 3. An evenly divided gap is formed, and a relatively wide gap 7 is locally formed, so that the gap is loosely fitted.

By the way, with respect to the above-mentioned baseline X, the lugs 2a,
The center lines 8 and 8 of 2a are set by being distributed to the left and right at the time of assembly, and it is most desirable that the distribution setting positions are equal position. This is because, as shown in FIG. 4, when the center line 8 of one of the lugs 2a is set to the left side and the center line 8 of the other lug 2a is set to the right side with respect to the base line X at the time of assembly, a rated rotation is obtained. At this time, the turbine rotor blades 1, 1 are untwisted, so that the center line 8 of the one lug 2a, which is set to the left side with respect to the base line X, is moved to the right side and is set to the right side with respect to the base line X. The center line 8 of the other lug 2a that has been moved to the left, and these movement amounts are relative movement amounts D of the center lines 8 and 8.
On the other hand, it is empirically confirmed that the distribution is within the range of D / 2 when distributed from the base line X.

Therefore, from the time of assembly to the time of rated rotation with respect to the base line X, it is premised that the center lines 8, 8 of the lugs 2a, 2a move to the left and right opposite positions, and the amounts of movement are both equal. The so-called offset design
If it is adopted when setting the center lines 8 and 8 of the lugs 2a, 2a, the damping effect given to the lugs 2a, 2a of the sleeve 3 is high, and the corrosion products deposited in the gap between the sleeve and the lug are reduced, Further, it is convenient in terms of manufacturing that the shape of the sleeve 3 can be made small, which is expected to make a dramatic use in this field.

[0020]

As described above, in the coupling device for different turbine dynamics according to the present invention, the center lines of the lugs facing mutually adjacent turbine moving blades are distributed to the left and right with respect to the base line during assembly. If the reverse position is set to, the set lug centerlines will move in opposite directions relative to the base line during rated rotation, so the lugs will be capped to match this amount of movement. The sleeve can be molded and is smaller than the prior art.

Therefore, in the turbine coupling device according to the present invention, under high vibration damping effect, corrosion products are prevented from accumulating due to the reduction of the clearance between the lug and the sleeve due to the downsizing of the sleeve, and occur during the rotation of the turbine blade. It has an excellent effect that the centrifugal force can be relatively reduced.

[Brief description of drawings]

FIG. 1 is an inclined view showing an embodiment of a turbine blade connecting device according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a diagram showing an example for explaining the movement of the center line position during assembly and rated rotation of the lug according to the present invention.

FIG. 5 is a diagram for explaining the behavior of the lug according to the present invention.

FIG. 6 is an assembly diagram showing a conventional turbine blade connecting device.

FIG. 7 is a diagram showing an example for explaining that the center line position of the lug during conventional assembly moves during rated rotation.

FIG. 8 is a diagram showing another embodiment for explaining that the center line position of the lug during conventional assembly moves during rated rotation.

[Explanation of symbols]

 1 ... Turbine rotor blade 2 ... Boss 2a ... Lug 3 ... Sleeve 8 ... Lug center line X ... Base line

Claims (2)

[Claims] 1. A boss is formed on the blade surfaces of a large number of turbine rotor blades mounted on the outer periphery of a turbine rotor, which face each other, and lugs are provided at both ends of these bosses in the axial direction of the boss. In a turbine blade connecting device in which turbine blades adjacent to each other are movably connected by sleeves to be crowned, with the base lines where the center lines of the lugs facing each other coincide,
Turbine motions are characterized in that the center lines of the opposing lugs are set so that the center lines of the opposing lugs move to positions opposite to those before until the turbine rotor blades are stationary and at the rated speed. Wing connecting device. 2. A boss is formed on the blade surfaces of a large number of turbine rotor blades mounted on the outer periphery of a turbine rotor, which face each other, and lugs are provided at both ends of these bosses toward the boss axis. In a turbine blade connecting device in which turbine blades that are adjacent to each other are movably connected to each other with a capping sleeve, the turbine rotor is stationary and the rated rotation is taken at the boundary line where the center lines of the lugs that face each other coincide. 2. The turbine rotor blade according to claim 1, wherein the center lines of the mating lugs of the two are set so that the center lines of the mating lugs of the two move to positions that are opposite to each other. Connecting device.