JP2602936B2 - Turbine blade racing wire structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a turbine blade racing wire structure for connecting a turbine blade adjacent to a through hole formed in a turbine blade of a steam turbine or the like through a racing wire. About.

(Prior Art) In recent years, steam turbines of thermal power plants and nuclear power plants have increased the output of a single unit of a steam turbine by increasing the steam flow passage area in a low pressure stage and reducing exhaust loss in the low pressure stage. Is planned. As the steam flow path area increases, the length of the blade in the low-pressure stage increases, and the peripheral speed at the blade tip during turbine operation has reached a high speed far exceeding the speed of sound.

On the other hand, the condenser of a large steam turbine is generally disposed directly below the low-pressure turbine rotor, and the steam that has passed through the last stage of the low-pressure turbine changes its flow direction from the axial direction to the vertical direction, and Led to. Due to this diverted flow, a non-uniform static pressure distribution is generated in the circumferential direction at the outlet of the low-pressure last stage blade, so that an exciting force acts on the blade.

In general, when the steam flow is uneven in the tangential direction of the turbine, if the natural frequency of any of the blades is equal to an integral multiple of the turbine speed, the blade resonates and receives a large excitation force,
The blades and the components attached to the blades may cause fatigue failure. Therefore, in designing the structure of the blade, detuning design is performed in order to avoid a match between an integral multiple of the turbine speed and the natural frequency of the blade.

In particular, since the low-pressure last stage blade becomes longer, the natural frequency of the blade tends to coincide with a low multiple of the turbine speed when receiving an excitation force because the natural frequency is lower than that of the short blade.
Therefore, a racing wire is provided for the purpose of avoiding the coincidence by controlling the excitation force.

The structure of this racing wire is roughly classified into a loose type and a blazed type.

The loose type racing wire structure is shown in FIGS.
As shown in the drawing, a through hole 2 penetrating in the circumferential direction is provided in a turbine blade 1, and an arc-shaped or annular lacing wire 3 is passed through the through hole 2, and a total of more than one hundred turbine blades 1 A lacing wire 3 and a turbine blade 1 are slid through a through hole 2 during operation of the turbine,
The vibration of the turbine blade 1 is attenuated by the friction. Note that reference numeral 4 denotes a retaining member.

In addition, as shown in FIGS. 9 and 10, the blazed type racing wire structure has a through hole 2A in the turbine blade 1A as in the loose type racing wire structure,
The arcing or annular racing wire 3A is inserted into the through hole 2A.
The turbine blades 1A and the racing wires 3A are connected to each other via the
And damping the vibration of the turbine blade 1A by utilizing the rigidity of the racing wire 3A and the silver brazing material 5 during the operation of the turbine.

(Problems to be Solved by the Invention) These types of racing wire structures and turbine blades
The spelling number of 1,1A is determined in consideration of the vibration characteristics of the turbine blades 1,1A. However, since the total number of blades in each paragraph is limited by turbine performance, etc., the spelling number is not necessarily the same in the same paragraph. Not necessarily. In this case, the detuning between the turbine speed and the natural frequency of the turbine blades 1 and 1A cannot be sufficiently obtained.

In addition, since the racing wires 3, 3A have an excessive centrifugal force and an exciting force due to a steam flow superimposed in the radial direction of rotation during turbine operation, the detuning is sufficiently performed. It can be said that the device is in a severe use condition in which cut-off occurs.

Furthermore, since several adjacent blades are spelled in one, the turbine blades 1 and 1A bend in the blade rotation direction, that is, the tangential direction due to the excitation force of the steam flow. Will be further encouraged.

Therefore, after the operation for a predetermined period, the inside of the turbine is periodically opened and the racing wires 3, 3A are inspected for breakage.
If cuts or cracks are found, it is requested that they be repaired promptly. Obviously, these repairs can be quite time consuming and costly, thus affecting the reliability of the steam turbine.

The present invention has been made in consideration of the above-described circumstances. In addition to increasing the rigidity by connecting the racing wires of each turbine blade group, and having a blade vibration damping function at the connection portion, the resonance of the turbine blade group is improved. An object of the present invention is to provide a turbine blade racing wire structure capable of preventing damage to a turbine blade group, a racing wire, and the like.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a turbine blade racing wire structure in which a racing wire is passed through a through hole formed in a turbine blade, and the racing wire connects the turbine blades to each other. Numerous turbine blades are connected in a plurality of groups in the circumferential direction by a plurality of notched racing wires, and a reinforcing sleeve for inserting a racing wire end between the turbine blade groups is provided. A rivet is inserted from the turbine diameter direction into the through-hole provided in the hole, and the rivet is caulked to bring the inner periphery of the through-hole into close contact with the slanted notch at the end of the racing wire, thereby connecting the racing wires of each turbine blade group. Alternatively, pass a lacing wire through a through hole formed in the turbine In a turbine blade racing wire structure in which turbine blades are connected to each other by ears, a reinforcing sleeve for connecting a number of turbine blades in a plurality of groups in a circumferential direction by a plurality of racing wires and inserting a racing wire end between the turbine blade groups. A rivet is inserted from a turbine diametrical direction into a through hole provided at a substantially central portion of the reinforcing sleeve, and the rivet is caulked by providing a gap in which the reinforcing sleeve is slidable in the axial direction. Are connected.

(Operation) In the present invention, since the racing wires of each turbine blade group are connected via the reinforcing sleeve, a structure of a group around the same circumference as when turbine blades of the same paragraph are spelled by one racing wire is obtained. 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 the rigidity due to the connection of the racing wires of each turbine blade. It can withstand severe operating conditions. Furthermore, since natural vibration in the tangential direction is reduced,
Detuning from resonance is facilitated.

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

FIG. 1 is a partially cutaway front view of a turbine provided with one embodiment of a turbine blade racing wire structure according to the present invention. In FIG. 1, a large number of turbine blades 11 are implanted on the outer periphery of an impeller 10, and the large number of turbine blades 11 are, for example, four racing wires 12a, 12b, 12c, 12c.
By d, it is connected to four turbine blade groups in the circumferential direction.
The racing wires 12a to 12d of each turbine blade group are connected via reinforcing sleeves 13a, 13b, 13c, 13d, respectively. The number of racing wires 12a to 12d is
Difficulties in planting 11 on impeller 10 and racing wayers 12a-1
What is necessary is just to determine from the restriction | limiting in the operation | work which inserts 2d into the turbine blade 11, and it is not necessary to limit to four.

In this embodiment, a loose type racing wire structure is adopted as shown in FIGS.
The racing wires 12a to 12b penetrate through the through holes 14 secured in the above. Ends of the racing wires 12a to 12d connecting the turbine blade groups are inserted into reinforcing sleeves 13a to 13d, respectively, and a gap is provided between the ends of the racing wires 12a to 12d.
15 is formed. When inserting the ends of the racing wires 12a to 12d into the reinforcing sleeves 13a to 13d, the racing wires 12a to 12d are shifted in the length direction, and the reinforcing sleeves 13a to 13d are sequentially used by using the gap 15. Install.

A rivet hole 16 that penetrates in the diametric direction is formed at a substantially central portion in the length direction of the reinforcing sleeves 13a 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, the racing wires 12a to 12d are connected by caulking the rivet 17 from the side opposite to the insertion direction. In this case, as shown in FIGS. 3 and 4, a notch 18 is formed at the end of each of the racing wires 12a to 12d, so that the reinforcing sleeve 13 is formed.
The inner circumference of the rivet hole 16 of a to 13d is notched due to caulking
In contact with the 18th surface, the connection is more secure.

When applying the 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, a relatively large gap 15 between the racing wires 12a to 12d is taken. In addition, by increasing the inner diameter of the reinforcing sleeves 13a to 13d, the end of each of the racing wires 12a to 12d can be fixed without shifting the racing wires 12a to 12d.
Insert into a ~ 13d.

As described above, according to the above-described embodiment, a large number of turbine blades 11 implanted on the outer periphery of the impeller 10 are connected to four racing wires.
12a to 12d are connected to each other to form four turbine blade groups, and the racing wires 12a to 1
By connecting the ends of 2d via the reinforcing sleeves 13a to 13d, the rigidity can be increased and the excitation force due to the steam flow can be increased, and the detuning can be achieved by reducing the vibration in the turbine blade rotation direction. It will be easier. Therefore, damage to the turbine blades 11, the racing wires 12a to 12d, and the like can be prevented beforehand, and the operating rate of the turbine can be improved.

5 and 6 are sectional views showing a second embodiment of the present invention. In this embodiment, each of the racing wires 12a to 12d
Is slidably inserted into each of the reinforcing sleeves 13a to 13d, and a gap δ is formed with the rivet 17. As a result, each of the reinforcing sleeves 13a to 13d
Since the outer circumference of 2d can be slid for a gap of 28 minutes, the steam flow to the turbine blade 11 causes the reinforcing sleeves 13a to 13d to slide, which acts as a damping force against vibration. Although this embodiment shows a case in which a loose type racing wire structure is employed, the same operation can be achieved in the case of a blazed type racing wire structure. By optimally selecting these structures and locations to be used, detuning from resonance can be easily achieved.

The value of the natural frequency in the blade rotation direction can be changed by changing the material of the rivet 17 in the first embodiment. That is, if the material is changed, the hardness changes, which changes the magnitude of the attenuation of the vibration in the blade rotation direction. In this case, the racing wire 12a
Since the magnitude of the attenuation also changes depending on the number of 1212d, the optimal combination can be selected by changing the number of racing wires 12a〜12d and the material of the bet 17 in the detuning of the resonance.

〔The invention's effect〕

The turbine blade racing wire structure according to the present invention includes:
A plurality of racing blades having inclined cutouts formed at the ends connect a large number of turbine blades in a plurality of groups in a circumferential direction, and a reinforcing sleeve for inserting a racing wire end between each turbine blade group is provided. A rivet is inserted from a turbine diameter direction into a through hole provided at a substantially central portion of the reinforcing sleeve, and the rivet is caulked to bring the inner periphery of the through hole into close contact with the oblique notch at the end of the racing wire so as to make each turbine blade group. Since the lacing wires are connected, the rigidity is increased to resist the exciting force of the steam flow,
Separation is facilitated by reducing vibration in the blade rotation direction. In addition, a plurality of turbine blades are connected to a plurality of groups in a circumferential direction by a plurality of racing wires, and a reinforcing sleeve for inserting an end of the racing wire between the respective turbine blade groups is provided. A rivet is inserted into the hole from the turbine diametric direction, and the rivet is caulked by providing a gap in which the reinforcing sleeve can slide in the axial direction, and the racing wires between the turbine blade groups are connected. It becomes possible, and detuning from resonance becomes easy by selecting the installation position. Therefore, damage to the turbine blade group, the racing wire, and the like can be prevented, and the operation rate of the turbine can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway front view showing a turbine equipped with a first embodiment of a turbine blade racing wire structure according to the present invention, and FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, FIG. 4 is a cross-sectional view taken along the line III-III in FIG. 2, FIG. The figure shows the second embodiment of the present invention.
FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5, FIG. 7 is a structural view showing a conventional loose-type racing wire structure, and FIG. 8 is FIG. In
FIG. 9 is a sectional view taken along line VIII-VIII, FIG. 9 is a configuration diagram showing a conventional blazed type racing wire structure, and FIG. 10 is a sectional view taken along line XX in FIG. 11… Turbine blades, 12a to 12d… Racing wires,
13a to 13d: reinforcement sleeve, 14: through hole, 17: rivet.

Claims (2)

(57) [Claims] 1. A turbine blade racing wire structure in which a racing wire is passed through a through hole formed in a turbine blade and the turbine blade is 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 racing wire, and a reinforcing sleeve for inserting an end of the racing wire between the turbine blade groups is provided. A turbine diameter is provided in a through hole provided at a substantially central portion of the reinforcing sleeve. A rivet is inserted from the direction, the rivet is caulked, and the inner periphery of the through hole is brought into close contact with the oblique notch at the end of the racing wire to connect the racing wires of each turbine blade group. Wire structure. 2. A turbine blade racing wire structure in which a racing wire is passed through a through hole formed in the turbine blade and the turbine blade is connected to each other by the racing wire. A reinforcing sleeve is provided for connecting the ends of the racing wires between the turbine blade groups, and a rivet is inserted from a turbine diametrical direction into a through hole provided at a substantially central portion of the reinforcing sleeve. A turbine blade racing wire structure, wherein a sleeve is provided with a gap slidable in the axial direction and caulked to connect a racing wire between the turbine blade groups.