JP2002349207A - Turbine rotor blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase degree of freedom of pinhole arrangement of a turbine rotor blade and a rotor wheel planting part, and to reduce shearing stress generated around the pinhole of the each planting part. SOLUTION: This turbine rotor blade is provided with a blade 1 including the forked planting part 2 and a wheel 5 including a groove 6 corresponding to the planting part 2 of the blade 1 at an out circumference part and has a forked planting structure making pin holes 4, 8 formed on a groove forming wall 7 of the wheel 5 and the planting part 2 of the blade 1 coincide with each other and inserting the planting part 2 of the blade 1 into the groove 6 of the wheel 5 and locking the same with a pin. The pinhole 8 formed on the groove- forming wall 7 of the wheel 5 and the pinhole 4 formed on the planting part 2 of the blade 1 is arranged in a staggered arrangement relative to a rotor radius line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade implant structure for an axial flow turbine, and more particularly to a blade implant structure for reducing stress at an implant portion.

[0002]

2. Description of the Related Art An axial flow turbine is composed of a number of moving blades arranged in a circumferential direction of a rotor and a stationary blade (nozzle) fixed to a turbine casing. An axial flow turbine is formed by forming a turbine stage in pairs and arranging the stages in a plurality of stages.

[0003] The high-pressure steam, which is a working fluid introduced into this paragraph, gradually expands as it passes through each paragraph, and the energy is converted into rotational energy of the rotor blades, thereby rotating the rotor. Driven. In response to the demand for increasing the working fluid volume of the turbine accompanying the recent increase in the capacity of the power generation plant, and the demand for compact equipment arrangement, the turbine rotor blades have been made longer. In particular, since a large centrifugal force acts on the last stage blade of the low-pressure turbine and the rotor blade near the last stage, which have been enlarged due to the longer blade, the implanted portion that is connected to the rotor shaft is more reliable. A desired structure is desired.

[0004] A saddle-shaped structure, a Christmas tree-shaped structure, a T-shaped structure, a fork-shaped structure and the like are used as an implanted structure of the turbine blade, and the strength and manufacturability required for the implanted portion (easiness of assembly and cost). ), The structure is selected. Among them, the fork-shaped structure is a structure mainly applied to the final stage and its front wing, and is designed to withstand a large centrifugal force.

FIG. 5 shows a conventional example of a moving blade having a fork-shaped implantation structure. FIG. 5 shows a bird's-eye view of the implanted portion formed at the lower end of one blade, in which a fork-like implanted portion 2 is integrally formed at the base of the wing 1, and a plurality of implanted component components (Hereinafter referred to as "fork-shaped support")
3 are formed. Each fork-shaped support is
The thickness is designed so as to gradually decrease in the direction of the center of the rotor. Generally, the thickness changes in three stages.

A plurality of pin holes 4 are formed in each step along the radial direction of the rotor, and are mounted on wheels, which are implanted parts on the rotor side, via pins (not shown). Conventionally, these pin holes 4 are linearly arranged on the radius line of the rotor. FIG. 6 is a view of the fork-shaped support portion 3 of the wing 1 as viewed from the side, and the respective pin holes 4 are linearly arranged on the rotor radial line C1, which is the center of gravity.

FIG. 7 shows the shape of a wheel 5 which is an implanted portion on the rotor side corresponding to the implanted portion 2 of the blade 1, and shows a cross section cut along an arbitrary radius line and a bird's eye view. Grooves 6 corresponding to the shape of the fork-shaped support portion 3 of the wing 1 are formed in the outer periphery of the wheel 5, and a pin hole 8 is formed in each groove forming wall 7 at a position corresponding to the pin hole 4 of the wing 1. Each is drilled.

[0008]

In the design of the fork-shaped implant described above, the load sharing and shear stress of the pin,
The stresses around the pin holes 4 and 8 of the wing 1 and the wheel 5 are evaluated, and optimization is performed so that each stress is less than a design allowable value with respect to the strength of the material.

However, if the pin holes 4, 8 are linearly arranged on the radial line of the rotor, the centrifugal force of the blade 1 increases, and when the entire blade 1 is displaced outward in the axial direction, the pin 9 Since the degree of freedom in the distance between the pin holes 4 and 8 is lost, the shear stress acting on the end (lower part in the figure) of the pin holes 4 and 8 on the inner peripheral side of the rotor in the blade implant portion 2 becomes excessive. there is a possibility. On the other hand, in the implanted portion of the wheel 5, the shear stress acting on the end portions (upper part in the figure) of the pin holes 4 and 8 on the outer peripheral side of the rotor becomes excessive.

FIGS. 8A, 8B, and 8C show the positions of the wing 1 and the wheel 5 when the wing 1 is displaced by a centrifugal force acting on the wing 1 and the wheel 5 in the implantation structure. And the locations where the centrifugal force of the wing 1 acts on the pin holes 4 and 8 via the pins and the shear stress is generated by the load. FIG. 8A shows a fork-shaped support portion 3 of the implant portion 2 of the wing 1 displaced outward by centrifugal force.
And the groove forming wall 7 of the wheel 5 which is an implanted portion on the rotor side.
FIG. 3 is a diagram showing a state in which a part is enlarged to show a cross section in a rotor circumferential direction.

The centrifugal force causes the fork-shaped support portion 3 to be displaced outward together with the wings 1, so that the pin 9 is also displaced outward by being dragged by the pin hole 4 provided in the support portion 3. On the other hand, the position of the pin hole 8 on the side of the wheel 5 does not change even when the rotor rotates, so that the displacement of the pin 9 is restricted by the pin hole 8. As a result, during assembly (at rest)
The gap between the pin 9 and the pin holes 4 and 8 was
Therefore, the pin hole 8 is biased toward the upper portion, while the pin hole 8 is biased toward the lower portion. Conversely, a load acts on the lower part of the pin hole 4 by the pin 9 and acts on the upper part of the pin hole 8. In the implant portion 2 of the wing 1 shown in FIG.
For each of the loads Fc1, Fc2, and Fc3 acting from, shear stresses Sb1, Sb2, and Sb3 are generated below them. On the other hand, on the groove forming wall 7 on the wheel 5 side shown in FIG.
2, Fc3, shear stress Sw1, Sw
2 and Sw3 occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and increases the degree of freedom in setting the distance between the pin holes in the radial direction of the rotor, facilitates the relaxation of the stress around the pin holes, and reduces the size of each implanted portion. It is an object of the present invention to provide a turbine blade capable of reducing shear stress generated around a pin hole of the turbine blade.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a wing having a fork-shaped implanted portion and a wheel having a groove corresponding to the implanted portion on the outer peripheral portion are provided. A turbine blade having a fork-shaped implanted structure in which pin holes formed in both the groove-forming wall of the wheel and the implanted portion of the blade are aligned and locked by a pin, wherein the groove-forming wall of the wheel is provided. And a pin hole formed in the implanted portion of the blade is arranged in a staggered manner with respect to a rotor radial line.

According to the second aspect of the present invention, in the turbine rotor blade according to the first aspect, the pin holes are formed at three different positions in the radial direction of the rotor at each of the implanted portions of the blade. The inner peripheral pin hole located on the peripheral side and the outer peripheral pin hole located on the outer peripheral side are formed on the center line of the wing, and the intermediate pin holes located at intermediate positions with respect to the rotor radial direction of these pin holes are: A turbine blade is provided at a position offset in the rotor circumferential direction from the center of gravity line.

According to a third aspect of the present invention, in the turbine rotor blade according to the first aspect, the pin holes are formed at three different positions in the radial direction of the rotor at each of the implanted portions of the blade, and the pin holes are formed in the radial direction of the rotor. The inner peripheral side pin holes located on the peripheral side and the outer peripheral side pin holes located on the outer peripheral side are formed on an alignment reference line, and the intermediate pin holes located at intermediate positions of these pin holes with respect to the rotor radial direction are arranged. A turbine rotor blade is provided at a position offset from a reference line in a rotor circumferential direction.

According to a fourth aspect of the present invention, in the turbine rotor blade according to the first aspect, the pin holes are formed at three different positions in the radial direction of the rotor in each of the implanted portions of the blade, and are located at intermediate positions among them. The intermediate pin hole is formed at the position of the center of gravity line, and the inner peripheral pin hole located on the inner peripheral side in the rotor radial direction and the outer peripheral pin hole located on the outer peripheral side are formed at positions offset in the rotor circumferential direction from the center line. A turbine blade is provided.

According to a fifth aspect of the present invention, in the turbine rotor blade according to the first aspect, the pin holes are formed at three different positions in the radial direction of the rotor at each of the implanted portions of the blade, and are located at intermediate positions among them. The intermediate pin hole is formed on the arrangement reference line, and the inner peripheral pin hole located on the inner peripheral side along the rotor radial direction and the outer peripheral pin hole located on the outer peripheral side are offset in the rotor circumferential direction from the arrangement reference line. Provided is a turbine blade characterized by being formed at a position.

[0018] In the invention according to claim 6, claims 1 to 5 are provided.
In the turbine rotor blade according to any one of the above, the interval between the pitch circle at the outer peripheral pin hole position and the pitch circle at the intermediate pin hole position is the pitch circle at the intermediate pin hole position and the inner peripheral pin hole position. A turbine rotor blade characterized in that the distance from the pitch circle is different.

According to the seventh aspect of the present invention, in the turbine rotor blade according to the sixth aspect, the interval between the pitch circle at the outer peripheral pin hole position and the pitch circle at the intermediate pin hole position is different from the pitch circle at the intermediate pin hole position. A turbine rotor blade is provided which is smaller than the interval between the pitch circle and the pitch circle at the position of the inner peripheral side pin hole.

According to an eighth aspect of the present invention, in the turbine rotor blade according to the sixth aspect, the interval between the pitch circle at the intermediate pin hole position and the pitch circle at the inner peripheral pin hole position is equal to the outer peripheral pin hole position. A pitch smaller than the pitch circle at the position of the intermediate pin hole and the pitch circle at the position of the intermediate pin hole.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turbine blade according to the present invention will be described below with reference to the drawings. In addition,
In the turbine blade shown in the following embodiments, the configuration other than the pin hole arrangement is the same as that of the conventional example. Therefore, the same reference numerals as those used in FIGS. I will explain.

First Embodiment (FIG. 1) FIG. 1 is an explanatory view showing a first embodiment of the present invention.
(A) shows the configuration of the wheel implantation section, and (B) shows the configuration of the wing implantation section. As shown in these figures, the turbine blade of the present embodiment has a blade 1 having a fork-shaped support portion 3 as an implant portion 2 and a groove 6 corresponding to the fork-shaped support portion 3 of the blade 1 on an outer peripheral portion. Wheel 5. Then, the pin holes 8 (8a, 8b, 8c) formed in the groove forming wall 7 of the wheel 5 and the pin holes 4 (4a, 4b, 4c) formed in the fork-shaped support portion 3 of the wing 1 are aligned with each other. The blade is fixed by a pin (not shown) to form a turbine rotor blade.

In such a configuration, the pin hole 8 formed in the groove forming wall 7 of the wheel 5 and the pin hole 4 formed in the fork-shaped support portion 3 of the blade 1 are connected to the rotor radial line (from the rotor center axis to the rotor radial line). The reference radius lines C1, C11, C12, and C13, which are lines extending perpendicularly to the outer peripheral surface, are arranged in a staggered manner. That is, in the present embodiment, the pin holes 4 and 8 are provided at predetermined intervals by varying the positions of the fork-shaped support portions 3 of the blade 1 in the radial direction of the rotor.
The outer peripheral pin holes 4a, 8a located on the outer peripheral side along the radial direction of the rotor and the inner peripheral pin holes 4c, 8c located on the inner peripheral side are respectively formed by the reference radius line of the blade 1. It is formed on C1, C11, C12, and C13. In addition, these pin holes 4a, 4c and pin holes 8a,
The intermediate pin holes 4b, 8b at the intermediate position of 8c are formed at positions offset from the reference radial lines C1, C11, C12, C13 in the rotor circumferential direction. The reference radius line is set in accordance with the center of gravity of the blade 1 and when the array reference line blade 1 slightly offset from the center of gravity is implanted in the rotor, the reference radius determined in advance by design is set. Sometimes a line is set.

More specifically, in FIG. 1A, the reference radius line C1 of the pin hole 8 provided in the groove forming wall 7 of the wheel 5 is shown.
Reference numerals 1, C12, and C13 indicate arrangement reference positions for three blades, and the reference radius lines C11, C12, and C13 have inclinations of a predetermined angle α. As described above, these reference radius lines C11, C12, and C13 can be set to match the center of gravity of the blade 1 or can be set to a slightly offset reference line of the blade 1. α is an angle obtained by dividing 360 degrees of the entire circumference by the number of blades planted in one paragraph. Radial lines indicated by D12 and D13 are lines that bisect the angle α, and coincide with adjacent surfaces of the blades 1.

FIG. 1B shows the arrangement of pin holes 4a, 4b, 4c formed in the fork-shaped support portion 3 on the blade 1 side. The outer peripheral pin hole 4a and the inner peripheral pin hole 4c are arranged on a reference radius line C1 corresponding to the radius line (for example, C12) of the rotor. Radial lines D12, D1 corresponding to the surface
3. That is, the half cracked pin hole 4b
Is completely closed together with the intermediate pin hole 4b of the other adjacent wing 1.

In this embodiment, as described above, the pin holes 4 and 8 are arranged in a staggered manner with respect to the rotor radial line, and
By arranging the intermediate pin holes 4b and 8b among the pin holes 4 and 8 by moving the half of the blade pitch in the circumferential direction of the rotor, the degree of freedom in setting the rotor radial interval between the pin holes is reduced. The stress around the pin hole is easily alleviated.

According to such a configuration, the pin holes 4 and 8 are arranged in a staggered manner, and, for example, the intermediate pin holes 4b and 8b are moved by a half pitch in the circumferential direction of the rotor, so that the outer peripheral side pin holes 4a and 8b are moved. Since there is no intermediate pin hole on the same radius line between the inner pin hole 4c and the inner peripheral side pin holes 4c, 8c and the position adjustment of the pin hole becomes easy, the shear stress due to the load acting through the pin is easily reduced. Can be alleviated.

If the degree of freedom in setting the position of the pin hole is increased, the height of the implanted portion in the radial direction of the rotor can be designed to be small, the centrifugal force of the entire blade can be reduced, and the stress of the implanted portion can be further reduced. There is also a superimposition effect of As the degree of freedom in implant design increases, it becomes easier to increase the blade length, and it becomes possible to design a turbine having higher performance or a turbine having a higher output.

As described above, according to the present embodiment, the pin holes 4, 8 are arranged in a staggered manner with respect to the rotor radial line, so that the pin hole interval in the rotor radial direction is substantially widened, and the conventional pin holes 4, 8 are arranged in a staggered manner. It is easy to reduce the shear stress below the pin hole of the wing, which tends to be severe in the arrangement, and it is also easy to reduce the shear stress above the pin hole in the wheel implant. In addition, from the viewpoint of the stress distribution, although the stress is conventionally concentrated on a straight line, the effect of dispersing the stress is expected because the pin holes are sparsely arranged.

Second Embodiment (FIG. 2) FIG. 2 is an explanatory view showing a second embodiment of the present invention.

Only the wing 1 of this embodiment is shown. In the present embodiment, three pin holes 4 are formed at predetermined intervals with different positions in the rotor radial direction at the respective implanted portions 2 of the blade 1. Of these, the intermediate pin hole 4b at the intermediate position is formed at a position along the center of gravity of the wing 1,
Inner peripheral pin hole 4c located on the inner peripheral side along the rotor radial direction
And the outer peripheral side pin hole 4a located on the outer peripheral side has a half crack shape at a position offset by ±± pitch in the rotor circumferential direction from the center of gravity line as the reference radius line C12 which is both end surfaces of the fork-shaped support portion 3. Is formed. Note that the reference radius line C12 may be replaced with an arrangement reference line having a slightly shifted position in the rotor radial direction, instead of the center of gravity line.

As described above, according to the present embodiment, the outer peripheral side pin hole 4a and the inner peripheral side pin hole 4c are each formed in a half crack, and the intermediate pin hole 4b is formed in the reference radius line C1 of the blade 1.
2 are arranged. Therefore, also in this embodiment, similarly to the first embodiment, it is possible to reduce the shear stress of the blade and the wheel implant portion.

Third Embodiment (FIG. 3) FIG. 3 is an explanatory view showing a third embodiment of the present invention.

In this embodiment, only the wheel 5 is shown. In the present embodiment, the pitch circle Ra of the outer peripheral side pin hole 8a is
The distance S1 between the pitch circle Rb of the intermediate pin hole 8b and the pitch circle Rb of the inner pin hole 8c is different from the distance S2 between the pitch circle Rb of the intermediate pin hole 8b and the pitch circle Rc of the inner peripheral side pin hole 8c.

In the illustrated example, the distance S1 between the pitch circle Ra of the outer peripheral side pin hole 8a and the pitch circle Rb of the intermediate pin hole 8b.
Is the pitch circle Rb of the intermediate pin hole 8b and the inner peripheral side pin hole 8c.
Is smaller than the interval S2 between the pitch circle Rc and the pitch circle Rc.

That is, when the pitch radii of the outer peripheral pin hole 8a, the intermediate pin hole 8b and the inner peripheral pin hole 8c are respectively R1, R2 and R3, the pitch circle radius R1 is reduced by making R1 smaller than in the conventional example. The distance S1 between R2 and R2 is smaller than the distance S2 between R2 and R3.

According to the present embodiment as described above, the intermediate pin hole 8b and the inner peripheral pin hole 8c approach each other, so that the wheel implanted outer peripheral pin hole 8
a The shear stress on the upper part can be reduced.

Fourth Embodiment (FIG. 4) FIG. 4 is an explanatory view showing a fourth embodiment of the present invention.

This embodiment shows the wing 1 and has an intermediate pin hole 4b.
The distance S2 between the pitch circle Rb and the pitch circle Rc of the inner peripheral pin hole 4c is smaller than the distance S1 between the pitch circle Ra of the outer peripheral pin hole 4a and the pitch circle Rb of the intermediate pin hole 4b. That is, in the pin hole arrangement of the wing implant portion 2, the pitch circle radii of the outer peripheral pin hole 4a, the intermediate pin hole 4b, and the inner peripheral pin hole 4c are set to R1, R2, and R3, respectively.
, R3 is made larger than the conventional example, and the interval S2 between the pitch circle intervals R2 and R3 is made smaller than the interval S1 between R1 and R2.

With such a configuration, the third
Contrary to the embodiment, the shear stress at the lower portion of the inner peripheral pin hole 4c of the blade implant 2 can be reduced.

[0041]

As described above, according to the present invention, the degree of freedom in the arrangement of the pin holes in the turbine rotor blades and the wheel implants is increased, and the shear stress generated around the pin holes in each implant is reduced. In addition, the stress distribution of the entire implant can be dispersed without being concentrated on one straight line. Since the effect of reducing the stress also enables the realization of a longer blade, the degree of freedom in blade design is expanded, and a turbine with better performance or a turbine with higher output can be designed.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams showing pin hole arrangements according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a pin hole arrangement according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a pin hole arrangement according to a third embodiment of the present invention.

FIG. 4 is an explanatory view showing a pin hole arrangement according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory view showing a conventional wing implantation structure.

FIG. 6 is an explanatory view showing a conventional pin hole arrangement for wing implantation.

FIG. 7 is an explanatory view showing a conventional wheel implantation structure.

FIGS. 8A, 8B, and 8C are explanatory views showing stress states around a pin hole for implanting a conventional wing and wheel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wing 2 Implantation part 3 Fork-shaped support part 4 Pin hole 5 Wheel 6 Groove 7 Groove forming wall 8 Pin hole 9 Pin

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Manabu Omiyama 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Toshiba Keihin Works (reference) 3G002 FA05 FA08

Claims (8)

[Claims] 1. A wing having a fork-shaped implant portion, and a wheel having a groove corresponding to the implant portion of the wing on an outer peripheral portion, formed on both a groove forming wall of the wheel and the implant portion of the wing. A turbine blade having a fork-shaped implantation structure in which the pin holes are aligned with each other and locked by a pin, a pin hole formed in a groove forming wall of the wheel and a pin hole formed in an implantation portion of the blade are attached to a rotor. A turbine rotor blade arranged in a staggered manner with respect to a radius line. 2. The turbine bucket according to claim 1, wherein
The pin holes are formed at three different positions in the radial direction of the rotor in each of the implanted portions of the blade, of which an inner pin hole located on the inner peripheral side in the rotor radial direction and an outer pin hole located on the outer peripheral side are included. Are formed on the center of gravity line of the wing, and the intermediate pin holes at intermediate positions of these pin holes with respect to the rotor radial direction are formed at positions offset from the center of gravity line in the rotor circumferential direction. Turbine blades. 3. The turbine bucket according to claim 1, wherein
The pin holes are formed at three different positions in the radial direction of the rotor in each of the implanted portions of the blade, of which an inner pin hole located on the inner peripheral side in the rotor radial direction and an outer pin hole located on the outer peripheral side are included. Is formed on the arrangement reference line, and the intermediate pin hole at an intermediate position of these pin holes with respect to the rotor radial direction is formed at a position offset in the rotor circumferential direction from the arrangement reference line. Bucket. 4. The turbine blade according to claim 1, wherein
The pin holes are formed at three different positions in the radial direction of the rotor in each of the implanted portions of the blade. Among them, the intermediate pin hole at the intermediate position is formed at the position of the center of gravity, and the inner hole located at the inner circumferential side in the radial direction of the rotor. A turbine blade, wherein the peripheral pin hole and the outer peripheral pin hole located on the outer peripheral side are formed at positions offset from the center of gravity line in the circumferential direction of the rotor. 5. The turbine bucket according to claim 1, wherein
The pin holes are formed at three different positions in the radial direction of the rotor at each of the implanted portions of the blade. Among them, the intermediate pin holes at the intermediate positions are formed on the arrangement reference line and located on the inner circumferential side along the radial direction of the rotor. The inner rotor side pin hole and the outer peripheral side pin hole located on the outer peripheral side are formed at positions offset from the arrangement reference line in the rotor circumferential direction. 6. The turbine rotor blade according to claim 1, wherein a distance between the pitch circle at the outer peripheral pin hole position and the pitch circle at the intermediate pin hole position is equal to the intermediate pin hole position. The pitch between the pitch circle and the pitch circle at the position of the inner peripheral side pin hole is different from each other. 7. The turbine bucket according to claim 6, wherein
The interval between the pitch circle at the outer pin hole position and the pitch circle at the intermediate pin hole position is smaller than the interval between the pitch circle at the intermediate pin hole position and the pitch circle at the inner pin hole position. Characteristic turbine blade. 8. The turbine bucket according to claim 6, wherein
The interval between the pitch circle at the intermediate pin hole position and the pitch circle at the inner peripheral pin hole position is smaller than the interval between the pitch circle at the outer peripheral pin hole position and the pitch circle at the intermediate pin hole position. Characteristic turbine blade.