JPH02169802A - Turbine blade lacing wire structure - Google Patents

Abstract

PURPOSE:To prevent a turbine blade group from being damaged by incorporating a blade vibration damping function to a coupling section in which lacing wires of turbine blade groups are connected through the intermediary of reinforcing sleeves so as to prevent resonance in the turbine blade groups. CONSTITUTION:Several turbine blades 11 are coupled together by means of a plurality of lacing wires 12a, 12b so as to be divided into a plurality of turbine blade groups. There is provided a reinforcing sleeve 13a into which end parts of the lacing wires among the turbine blade groups are inserted. A rivet 17 which pierces through the center part of the reinforcing sleeve 13a on a diametrical direction is caulked so as to couple the lacing wires 12a, 12b of the turbine blade groups. With this arrangement, the stiffness is increased so as to resist a vibration exciting force given by steam streams, and further, the vibration of the turbine blades 11 in the rotational direction is reduced so as to facilitate the retuning thereof. Accordingly, it is possible to prevent the turbine blade groups, the lacing wires 12a, 12b and the like from being damaged.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a turbine blade lacing wire that connects adjacent turbine blades by passing a lacing wire through a hole formed in a turbine blade in a steam turbine or the like. Regarding structure.

(Prior Art) In recent years, steam turbines in thermal power plants and nuclear power plants have increased the steam flow path area of the low-pressure stage to reduce exhaust loss in the low-pressure stage, thereby increasing the output of a single steam turbine. is planned. As the steam flow path area increases, the length of the blades in the low pressure stage increases, and the circumferential speed at the tip of the blade remains at a high speed far exceeding the speed of sound during turbine operation.

On the other hand, the condenser of a large steam turbine is generally placed directly below the low-pressure turbine rotor, and the steam that has passed through the low-pressure final stage is diverted from the axial direction to the vertical direction and then transferred to the condenser. be led to.

This diverted flow causes non-uniform static pressure distribution in the circumferential direction at the low-pressure final stage blade outlet, and therefore an excitation force acts on the blade.

Generally, when steam flow is uneven in the tangential direction of the turbine, if the natural frequency of any blade matches an integral multiple of the turbine rotation speed, it will resonate and receive a large excitation force, causing the blade and the parts attached to the blade to resonate. may cause fatigue failure. Therefore, when designing the structure of the blade, a detuning design is performed in order to avoid coincidence between an integral multiple of the turbine rotational speed and the natural frequency of the blade.

In particular, since the low-pressure final stage blades are long and large, their natural frequency is higher than that of short blades, so when receiving an excitation force, the natural frequency of the blades tends to match a low multiple of the turbine rotational speed. Therefore, racing wires are installed for the purpose of interrogating the excitation force to avoid coincidence between the two.

The structure of this lacing wire is roughly divided into loose type and blazed type.

As shown in FIGS. 7 and 8, in the loose type racing wire structure, a through hole 2 is provided in the turbine blade 1 in the circumferential direction, and an arcuate or annular racing wire 3 is passed through the through hole 2. It has a structure in which several or all of the 100-odd turbine blades 1 are connected to each other, and during turbine operation, the racing wire 3 and the turbine blade 1 are moved through the through hole 2, and the +! [This dampens the vibrations of the turbine blade 1. Note that the reference numeral 4 does not indicate a stop.

In addition, as shown in FIGS. 9 and 10, the blazed racing wire structure has a through hole 2△ in the turbine blade 1△, and the through hole 2A is similar to the above-mentioned loose type racing wire structure. It has a structure in which adjacent turbine blades 1A are connected to each other through an arcuate or annular racing wire 3A, and the turbine blade 1A and the racing wire A73A are further bonded by a silver brazing material 5. 3A and the rigidity of the silver brazing filler metal 5 to damp vibrations of the turbine blade 1A.

(Problem to be solved by the invention) These racing wire structure types and turbine blades 1
．． The number of spellings of 1A is determined by considering the tie characteristics of turbine blade 1° 1A, but since the total number of blades in each paragraph is restricted by turbine performance etc., the number of spellings is not necessarily the same even within the same paragraph. is not limited. In this case, I between the turbine rotation speed and the natural frequency of the turbine blade 1.1A
This means that you will not be able to get the ll tone sufficiently.

In addition, the racing wire 3.3A is subjected to superimposed excessive centrifugal force and excitation force due to the steam flow in the rotational radial direction during turbine operation, so even if sufficient detuning is performed, the racing wire 3.3A It can be said that the condition of use is severe enough to cause breakage.

Furthermore, since several adjacent blades are tied together, the excitation force of the steam flow causes the turbine blade 1.1A to deflect in the blade rotation direction, that is, in the tangential direction. will be further encouraged.

Therefore, after a predetermined period of operation, the inside of the turbine is periodically opened to inspect the racing wire 3.3A for breaks 10, and if breaks or cracks are found, they can be promptly repaired. It is summarized.

It is clear that these repairs require a considerable amount of U, 1/7i1, and in turn will affect the reliability of the steam turbine.

The present invention has been made in consideration of the above circumstances, and it increases the rigidity by connecting the racing wires of each turbine blade group, and also improves the resonance of the turbine blade nT by providing the connection part with a blade vibration damping function. The turbine blade racing wire V can prevent damage to the turbine blade group, racing wire, etc.
The purpose is to provide structure.

(Structure of the Invention) (Means for Solving the Problems) The present invention provides a turbine blade racing wire ψ which connects the turbine blades to each other by passing a racing wire through a single hole machined in the turbine blade.
In the structure, a large number of turbine blades are connected in a plurality of groups in the circumferential direction by a plurality of racing wires A7, and a reinforcing sleeve is provided into which the end of the racing wire A7 is inserted between each turbine blade group. A rivet is provided that passes through the turbine blade in the diametrical direction, and this rivet is caulked to connect the racing wires of each turbine blade group.

(Function) Since the present invention connects the racing wire A7 of each turbine blade group through the reinforcing sleeve, the entire circumference-group structure is equivalent to the case where turbine blades in the same row are tied with one racing wire. Become. This structure corrects the deflection of the turbine blades in the blade rotation direction, that is, the tangential direction, due to the excitation force of the steam flow, and increases rigidity by connecting the lacing wires of each turbine blade, which prevents breakage. Can withstand severe usage conditions. Furthermore, since the natural vibration in the tangential direction is reduced,
Detuning from resonance becomes easy.

(Example) Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partially cutaway front view of a turbine equipped with an embodiment of the turbine blade lacing wire structure according to the present invention. In FIG. 1, a large number of turbine blades 11 are installed on the outer periphery of an impeller 10, and these large number of turbine blades 11 are connected to, for example, four racing wires 12a, 1
2b, 12c.

It is connected to four turbine blade groups in the circumferential direction by 12d. Racing wires 12a to 12 for each turbine blade group
d is a reinforcing sleeve 13a.

13b, 13c, and 13cJ. The number of racing wires 128 to 12d is
1 to the impeller 10 and the racing wire 1
2a to 12d may be determined based on operational restrictions for inserting the blades 2a to 12d into the turbine blade 11, and there is no need to limit the number of trees to four.

In this embodiment, a loose racing wire structure is adopted as shown in FIGS. 2 and 3, and each turbine blade 11
Racing wire r12a~1 is inserted into the through hole 14 secured in
2b is penetrated. The ends of the racing wires 12a to 12d that connect the turbine blade groups are respectively inserted into reinforcing sleeves 138 to 13d, and each racing wire 12
A gap 15 is formed between the ends a to 12d. The ends of each racing wire 12a to 12d are covered with a reinforcing sleeve 13.
When inserting into wires a to 13d, each lacing wire 1
28 to 12d are shifted in the length direction, and each reinforcing sleeve 138 to 13d is sequentially installed using the gap 15.

A rivet hole 16 penetrating in the diametrical direction is formed in the longitudinal center of each of the reinforcing sleeves 138 to 13d, and a rivet 17 is inserted into the rivet hole 16. Therefore, the width of the gap 15 is formed to be slightly larger than the diameter of the rivet 17.

After inserting the rivet 17, each lacing wire 12a to 12dtfit is tied by caulking the rivet 17 from the opposite side to the insertion direction. In this case, as shown in FIGS. 3 and 4, each racing wire rl 2
By forming the notches 18 at the ends of the reinforcing sleeves 13a to 13d, the inner circumferences of the rivet holes 16 of the reinforcing sleeves 13a to 13d are caulked and come into contact with the surfaces of the notches 18, making the connection even more reliable. Become.

When applying the above turbine blade racing wire structure to a blazed type racing wire structure, since the racing wires 12a to 12d cannot be shifted in the length direction, the gaps 15 between the racing wires 12a to 12d are
is relatively large, and the reinforcing sleeves 13a to 13d
By enlarging the inner shape of the lacing wire 12
Each racing wire 12a without shifting a to 12d
Insert the ends of ~12d into reinforcing sleeves 13a-13d.

In this way, according to the above embodiment, a large number of turbine blades 11 installed on the outer periphery of the impeller 10 are connected by four racing wires (t12a to 12d) to form four turbine blade groups, The ends of the racing wires 12a to 12d of each turbine blade group are reinforced with sleeves 13a to 13a.
Increase the rigidity by connecting via 13d,
It is possible to resist the excitation force caused by the steam flow, and detuning is facilitated by reducing vibrations in the rotational direction of the turbine blades. Therefore, damage to the turbine blades 11, racing wires 12a to 12d, etc. can be prevented, and the operating rate of the turbine can be improved.

5 and 6 are cross-sectional views showing a second embodiment of the present invention. In this embodiment, each racing wire 12a-1
2d is slidably inserted into each of the reinforcing sleeves 13a to 13d, and a gap δ is formed between the ends and the rivet 17. As a result, each of the reinforcing sleeves 13a to 13d covers the outer periphery of the racing wires V12a to 12d by a gap δ j3.
Since the reinforcing sleeves 13a to 13d slide due to the excitation of the turbine blade 11 by the steam flow, this acts as a damping force against vibration. Although this example is shown using a loose racing wire structure, it would work similarly for a brazed racing wire structure.

By optimally selecting these structures and the locations used, detuning from resonance can be easily achieved.

In addition, in the first embodiment, by changing the material of the rivet 17, the value of the natural frequency in the blade rotation direction can be changed. In other words, changing the material will change the hardness, which will result in 1f in the blade rotation direction! The magnitude of the initial attenuation changes.

In this case, the magnitude of attenuation also changes depending on the number of racing wires 12a to 12d, so when detuning the resonance, the optimal combination is selected by changing the number of racing wires 12a to 12d and the material of the rivet 17. be able to.

[Effects of the Invention] The turbine blade racing wire structure according to the present invention connects a large number of turbine blades in a plurality of groups in the circumferential direction by a plurality of racing wires, and has a reinforcing sleeve in which the end portion of the racing wire is inserted between each turbine blade group. A rivet was provided that penetrates the reinforcing sleeve from the diametrical direction, and this rivet was caulked to connect the racing wires of each turbine blade group, increasing the rigidity and resisting the excitation force caused by the steam flow. At the same time, llf1w4 is facilitated by reducing vibration in the blade rotation direction. Therefore, damage to the turbine blade group, racing wires, etc. can be prevented, and the operating rate of the turbine can be improved.

FIG. 14 is a block diagram showing a conventional blazed racing wire structure, and FIG. 10 is a sectional view taken along the line X--X in FIG. 9.

11...Turbine blade, 12a-12d...Racing wire, 13a-13d...Reinforcement sleeve, 14
...L"5 through holes, 17...rivets.

[Brief explanation of the drawing]

Claims (1)

[Claims] In a turbine blade racing wire structure in which a racing wire is passed through a through hole machined in a turbine blade and the turbine blades are connected to each other by the racing wire, a large number of turbine blades are connected in a plurality of groups in the circumferential direction by a plurality of racing wires, A reinforcing sleeve is provided into which the end of the racing wire is inserted between each turbine blade group, and a rivet is provided that penetrates approximately the center of this reinforcing sleeve from the diametrical direction.This rivet is caulked to connect the racing wires of each turbine blade group. Turbine blade lacing wire structure featuring: