JP2001193406A - Turbine impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine impeller provided with sufficient fatigue strength of a blade implanting part with a simple structure. SOLUTION: In a connecting structure of a turbine moving blade, having a fork type blade implanting part and a disk, in relation to a pin inserted into a blade side fork positioned on the axial direction center part, a center of the pin is slid to a barrel side from the circumferential direction width center of the blade side fork in the radial direction of the pin, and thereby an effective cross sectional area of the barrel side on which large bending stress is acted is increased, and the gravity center of the blade is positioned on the circumferential direction barrel side. Since the bending stress acted on a back side and the barrel side is released and equalized, local stress generated around a circle hole of the blade fork is reduced, and the strength reliability against low cycle fatigue and high cycle fatigue of the blade implanting part is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling structure between a rotor blade and a disk of a turbine impeller, and more particularly to a coupling structure between a turbine rotor blade and a disk suitable for a rotor blade on a low pressure side of the turbine impeller.

[0002]

2. Description of the Related Art An impeller of a turbine is usually made by implanting a moving blade around a disk constituting a rotor. In this case, a structure for implanting the moving blade into the disk is called a fork type. There is a wing implant.

FIG. 6 is a perspective view showing an example of a joint portion between a steam turbine blade and a disk having a fork type blade implant according to the prior art, and FIG. 7 (a) shows a blade side fork in a radial direction. FIG. 7 is a side view taken from
(b).

[0004] In these figures, reference numeral 1 denotes a turbine rotor blade, which has a blade portion 10 and a base portion (blade implantation portion) 6. The base portion 6 has a plurality of blades arranged in the axial direction of the turbine. The wing-side forks 12a, 12b, 12c,... Are formed, and a plurality of wing-side forks 12a to 12c are arranged so that their positions in the radial direction are different on a center line X orthogonal to the axis of the turbine. Holes 13 are provided.

[0005] Next, reference numeral 2 denotes a turbine rotor, although only one is shown in the figure, which has a plurality of disks 8 arranged in the axial direction of the turbine. Disk-side forks 9a, 9b, 9
.. are formed, and a plurality of holes 22 are provided in each of the disk-side forks 9a to 9 in accordance with the holes of the wing-side forks.

Then, a blade-side fork 1 of the turbine rotor blade 1
After inserting 2a ~ between the disk-side forks 9a ~ of the rotor 2, the plurality 13 and the holes 22 on the disk-side are aligned, and the pins 3 are inserted there along the axial direction of the rotor, and each fork is penetrated. Thus, the turbine blade 1 is attached to the disk 2.

By the way, since a large centrifugal force acts on the turbine blade during operation, a high stress is applied to the joint between the turbine blade and the disk.

Further, in the low pressure stage of the turbine, since the wet steam enters the gap between the blade implants and the corrosion products contained in the steam are concentrated, the joint between the turbine blade and the disk is not strong. It can be said that the environment is severe.

Therefore, in order to secure sufficient strength reliability even in such a severe environment, a material having high strength and resistant to a corrosive environment has been conventionally used as a material of the turbine.

For example, a 12Cr steel or a titanium alloy having a high specific strength is used for a turbine rotor blade, and a high-strength steel is used for a pin material.
Cr-Mo-V steel and 3.5% N for disc material
i-Cr-Mo-V steel or the like is used.

However, in recent years, there has been a strong demand for an improvement in the efficiency of steam turbines. As a result, longer blades have been used in the final stage of the low-pressure turbine impeller. There is also an increasing demand for improved strength.

In recent years, even in a combined cycle plant, long blades are often used in turbines for the purpose of further improving the power generation efficiency. In this case, the plant is frequently started and stopped. In addition, the blade implant must have sufficient reliability against low cycle fatigue in addition to maintaining sufficient strength.

Accordingly, in recent years, advanced technology has been required to secure the strength reliability of the wing implanted portion, and it is currently impossible for the prior art to cope with the problem. And increasing the thickness of the wing-side and disk-side forks.

However, when the axial thickness and the number of forks are increased as described above, the blade implant portion becomes large in the axial direction, so that the power generation plant becomes large and the blade profile at the root portion of the blade profile is formed. Problems such as an increase in pressure loss occur, and when the thickness is further increased in the circumferential direction, the number of implantable wings is reduced, and the performance is reduced. .

Therefore, instead of these methods, for example, Japanese Patent No. 2753236 discloses a technique for increasing the strength by inclining the insertion direction of the pin with respect to the axial direction and increasing the load bearing cross-sectional area of the pin. In Japanese Patent Application Laid-Open No. 57-10706, the center line of the pin is inclined with respect to the radial line so that the load is shared on the side surface of the wing-side fork to reduce the load acting on the pin. We suggest about technique to let you do.

[0016]

In the above prior art, no consideration is given to the trade-off relationship between maintaining the strength and reliability of the turbine impeller and difficulty in manufacturing and assembling. There was a problem in balancing these.

However, in the case of the prior art disclosed in the above publication, it is necessary to incline the insertion direction of the pin with respect to the axial direction or to incline the center line of the pin with respect to the radial line. The problem of difficulty in manufacturing and assembling arises.

As described above, as the turbine blade length increases, the centrifugal force acting on the rotor blades increases, and when a long blade is applied to a combined cycle, the number of times of starting and stopping the plant increases. At the present time, at the joint between the blade and the disk where the stress concentration is large, it is more difficult to secure the strength reliability than before.

Under such circumstances, at the joint between the blade and the disk, sufficient strength reliability is ensured against low-cycle fatigue caused by starting and stopping and high-cycle fatigue in a corrosive environment subjected to high average stress. There is a need to.

An object of the present invention is to provide a turbine impeller capable of sufficiently obtaining the fatigue strength of a blade implant portion with a simple configuration.

[0021]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a turbine impeller in which a turbine blade is coupled to a rotor disk by penetrating a pin into a fork implant portion, wherein a center of the pin penetrates a blade-side fork. Is shifted from the center of the circumferential width of the wing-side fork at the portion where the pin is located to the wing-ventilated side, so that the stress on the wing-ventilated side and the wing-back side of the wing-side fork is balanced. You.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a turbine impeller according to the present invention will be described in detail with reference to the illustrated embodiments.

FIGS. 1 to 5 show a turbine blade 1 according to a first embodiment of the present invention. In these figures, a blade portion 10, a base 6, and a plurality of blade side forks 12 are shown.
a, 12b, 12c,..., a plurality of holes 13 are the same as those of the conventional turbine blade 1 shown in FIGS. 6 and 7.

The turbine blade 1 shown in FIGS. 1 to 5 also has a turbine rotor 2 like the prior art shown in FIG.
Disk-side fork 9 formed on the disk 8
After inserting the wing-side forks 12a to a, 9b, 9c,..., the pin 3 is attached to each of the holes 13, 22 in the same manner.

FIG. 1 is a side view of the wing-side implanted portion viewed from the circumferential direction. FIG. 2 is a sectional view taken along line AA of FIG.
3 is a sectional view taken along line BB, and FIG. 4 is a sectional view taken along line CC. Further, FIG.
It is the figure seen from the direction.

Nine wing-side forks 1 arranged in the axial direction
2a to 12i and disk-side forks (9a to 9 in FIG. 6), which are not shown but are also distributed in the axial direction, are alternately implanted, and they are holes 13 having different radial positions.
Are fastened to each other by inserting the pins 3 into the holes.

As shown in FIG. 2, the blade root profile 5 which is a cross section of the root of the blade portion 10 has a shape which is curved toward the back side of the blade in the circumferential direction and drawn as shown in the figure. Therefore, a stepped portion 7 in the circumferential direction is formed on the base portion 6 in accordance with this, so that the blade root profile 5 is appropriately arranged on the base portion 6.

Here, the angle θ of the stepped portion 7 is desirably set to 20 ° or more and 70 ° or less so that the blade root profile 5 is appropriately arranged on the base portion 6.

The base portion 6 is provided with wing-side forks 12a to 12c. The first wing-side fork 12a from the axial end is also provided so as to be appropriately disposed on the base portion 6.
And the wing-side fork 12b are formed so as to be shifted in the circumferential direction to the wing-ventilation side with respect to the forks 12e to 12i located at the axial center, have semicircular holes 13a on both sides, and connect adjacent wings and pins. Share.

Next, the second wing-side forks 12c and 12d from the axial end are disposed in the stepped portion 7, and therefore have a parallelogram cross section according to the shape of the stepped portion 7. And located at the center in the axial direction excluding the second wing-side fork from each end in the axial direction.
The wing-side forks 12 e to 12 i are provided on the stepped portion 7 in accordance with the blade root profile 5.

Thereafter, the turbine blade 1 is connected to the blade-side forks 12a to 12
, The plurality of holes 13 on the wing side fork and the holes 22 on the disk side are aligned, and the pin 3 is inserted along the axial direction of the rotor to penetrate each fork. Is attached to the disk 2.

In the prior art, as shown in FIG. 7B, the holes 13 of the wing-side forks 12 are each provided with an axis C.
, The circumferential width W _A at the position of each hole of the wing-side fork 12,
W _B, are positioned on the radial direction line X passing through the center of the W _C.

In this embodiment, as shown in FIG. 4, the wing-side forks 12e to 12i are aligned with a radial straight line X passing from the axis C to the center of the circumferential width of the wing-side forks 12e to 2i. Each hole 13 is formed so as to be located on a radial straight line X _OFF which is displaced by a predetermined angle in the circumferential ventral direction, which is a feature of the present invention.

Next, as described above, the center position of the hole 13 of the wing-side forks 12e to 12i located at the center in the axial direction, that is, the center position of the pin 3 is moved from the center of the circumferential width of the fork 12 to the wing side. The function and effect of the above will be described.

Now, assuming that the circumferential spacing of each wing-side fork hole 13 is the same, in the case of this embodiment, FIG.
The distance 14 between the back side of the blade root profile 5 and the back side of the base portion 6 can be secured larger than in the case of the prior art, and therefore, the position of the center of gravity of the blade can be arranged further in the circumferential ventral direction, As a result, the bending load acting on the wing-side fork 12 is suppressed, and the difference in stress generated between the wing-side fork and the wing-side is alleviated. As a result, the wing-side fork of the wing-side fork is balanced with the stress on the wing-side. .

As shown in FIG. 2, the blade root profile 5 has an arcuate shape in the circumferential direction. Therefore, as shown in FIG. In the case of, not only a uniform tensile load,
A large bending load acts, and as a result, the stress is higher on the back side of the wing-side fork than on the belly side.

Generally, fatigue fracture occurs at a location where local stress is high. For this reason, in the wing-side fork according to the prior art, it can be considered that the unevenness of the stress on the back side and the abdomen side lowers the strength.

FIG. 8 schematically shows the distribution of loads acting along the path 15 from the ventral side to the back side of the upper surface of the wing-side fork 12i of the wing-side fork 12i located at the center in the axial direction shown in FIG. As shown.

In FIG. 8, the solid line is the characteristic of the above-described embodiment, and the broken line is the characteristic of the prior art. As is clear from this figure, the pin is arranged at the center of the circumferential width of the wing-side fork. By moving the center of the pin in the circumferential ventral direction with respect to the circumferential width center of the wing-side fork, the load acting on the dorsal side is reduced, and the difference between the loads generated on the ventral side and the dorsal side is reduced. As a result, it is understood that the stress is balanced between the wing ventral side and the wing rear side of the wing-side fork.

In the above embodiment, the distance δ between the center of the pin 3 inserted into the hole 13 on the outer peripheral side shown in FIG. it is desirable to proportion of 0.03 or more 0.13 or less with respect to the circumferential width W _a of the blade-side fork.

The same applies to the positions of the pins 3 located at the middle and inner peripheral sides, that is, the positions of the holes 13, and the center of each pin (or hole) and the circumferential width center line X of the wing-side fork.
The distance between the circumferential width W _B of the blade-side fork in the radial position of each pin, with respect to W _C, respectively 0.03 or 0.
It is desirable that the ratio be 13 or less.

Next, the reason why this range is appropriate will be described below.

[0043] We define the ratio of the distance [delta] with respect to the fork circumferential width W _A as a mobile ratio [delta] / W _A of the pin center.

In the structure of the embodiment of the present invention shown in FIG. 9A, a load received from the wing is simulated at an intersection 31 with the center line of the pin on the fork upper surface 30, and a tensile load 32
When added with a bending moment 33, 10 the relationship between the maximum principal stress occurring in dorsal and circular hole edge of the ventral side of the moving rate [delta] / W _A and the blade-side fork pin center (a), to (b) Show.

Here, when the movement amount of the pin center is 0,
In this case, the ratio of the stress caused by the bending moment 33 at the point 34 where the maximum bending stress acts on the top surface of the fork to the stress caused by the uniform load 32 is equal to that of the prior art shown in FIG. The case of 7 is shown in FIG. 10 (a), and the case of this ratio being 0.1 is shown in FIG. 10 (b).

At this time, the ratio between the tensile stress and the bending stress due to the uniform load 32 can take various values depending on the shape of the blade profile, the positional relationship between the position of the center of gravity of the blade and the width of the fork, and the connection conditions of the blade. However, if it is a general wing structure, the above ratio may be considered to be 0.1 to 0.7.

In FIG. 10, the maximum value of the principal stress on the back side of the blade and the principal stress on the ventral side of the three circular holes at the radially outer, intermediate, and inner circumferential sides are shown. Are shown.

First, the case where the stress ratio in FIG. 10A is 0.7 will be described. This corresponds to the case where the ratio of the bending load acting on the fork is the largest.

When the moving ratio of the center of the pin shown in FIG. 9B is 0, a higher stress is applied to the back side of the circular hole edge than to the ventral side as shown in FIG. It has occurred.

Therefore, as shown in FIG. 9 (a), when the center of the pin is moved to the ventral side, the effective cross-sectional area on the dorsal side increases, so that the stress on the dorsal side decreases, and accordingly the stress on the ventral side decreases. Stress increases. When the moving ratio of the center of the pin is increased and exceeds 0.13, the stress on the ventral side becomes larger than that on the dorsal side, and the strength of the stress is reversed.

From the above, it can be seen that when the stress ratio is 0.7, the optimal pin center movement ratio at which the maximum principal stress generated on the back side and the abdomen side is the lowest is 0.13. .

Next, the case where the stress ratio in FIG. 10B is 0.1 will be described. This corresponds to the case where the ratio of the bending load acting on the fork is the smallest.

When the stress ratio in FIG. 10 (b) is 0.1, the optimum pin center movement ratio at which the maximum principal stress generated on the back side and the abdomen side becomes the lowest is as shown in FIG. .03. Naturally, when the bending stress is small, the optimum pin center movement ratio tends to be smaller than when the bending stress is large.

Therefore, according to the embodiment of the present invention, the distance δ between the center of the pin 3 inserted into the hole 13 on the outer peripheral side and the center line X in the circumferential direction of the wing-side fork is determined as follows. 0.03 against fork circumferential width W _A
It is desirable to set the ratio to 0.13 or less.

According to this embodiment, the center line X _{OFF of the} pin is shifted to the abdominal side in the circumferential direction with respect to the circumferential center line X of the wing-side fork with respect to the fork located in the axial center portion. The effective cross-sectional area on the back side on which a large bending stress acts is increased, and as a result, the difference in stress generated between the back side and the ventral side of the wing fork is reduced.

Therefore, according to this embodiment, since the local stress generated at the edge of the circular hole of the wing-side fork is reduced, the fatigue strength can be increased.

By the way, the second wing-side forks 12c and 12d from the axial end shown in FIG.
Contrary to the other wing-side forks 12e to 12i, as shown in FIG. 3, there is a possibility that the back-side cross sections 20c and 20d are smaller than the ventral-side cross sections 21c and 21d. Here, 20e to 20i are cross sections on the back side of the other wing side forks 12e to 12i, and 21e to 21i are cross sections on the ventral side of the other wing side forks 12e to 12i.

However, in this embodiment, the center of the wing-side forks 12e to 12i located at the center in the axial direction has been moved to the abdominal side in the circumferential direction. And ventral section 21c, 21
The difference in the area of d can be reduced, which has the effect of increasing the strength of the second wing-side fork from the axial end.

In this case, in order to secure sufficient strength, the outer shape line 22 of the pin is formed at the vertex 19 of the parallelogram of the cross section.
Here, it is preferable that the diameter of the three pins 3 is the largest at the radially outermost pin, and the diameter of the three pins 3 is the largest at the inner peripheral side. It is desirable that the diameter be smaller as the position is located. This is a result in consideration of the fact that a pin located closer to the radially outer peripheral side has a larger loading load.

However, for a wing having a short wing length and the strength of the wing implantation portion is not so severe, the diameter of the three pins is set to be the same in order to reduce the types of pin drilling tools and to increase the working efficiency. Is also good.

For these pins 3, the larger the diameter, the lower the strength of the fork, and the smaller the diameter, the lower the strength of the pins themselves.

In consideration of this, according to the embodiment of the present invention, the ratio of the diameter of each pin to the circumferential width of the wing fork at the radial position where each pin passes is 0.2 or more and 0.2 or less. It is desirable to select so as to be 5 or less.

At this time, it is desirable that the dimensional tolerance between the pin 3 and the hole 13 is 0.2% to 0.6% of the pin diameter.

Here, if the tolerance is too small, the strength against fretting fatigue caused by the rubbing of the contact portion between the pin and the pin hole decreases, and the pin and the pin hole are easily fixed during the periodic inspection, and the pin is pulled out. On the other hand, if the tolerance is too large, the local stress generated at the edge of the circular hole of the fork becomes large, causing a problem that the fatigue strength is reduced and the response to vibration is increased. It is because.

By the way, regarding the wing-side fork 12,
As shown in FIG. 1, the axial thickness 16a of the portion through which the pin located on the radially outer peripheral side passes is the thickest, and the axial thickness 16b, 1
6c, on the other hand, as for the disk side fork 21, as shown in FIG. 6, the axial width of the portion where the pin located on the radially inner peripheral side passes is the thickest, It has a shape in which the thickness in the axial direction decreases as it is located on the outer peripheral side.

This is a result of considering that the nominal stress in the cross section near the pin passing through both the wing-side fork and the disc-side fork becomes substantially equal. The axial thickness 16b of the wing-side fork is preferably such that the ratio of the portion through which the pin on the radially outer peripheral side passes to the axial thickness 16a of the wing-side fork is 0.5 to 0.8. The axial thickness 16c of the wing-side fork at the portion where the inner peripheral pin passes is 0.2 to 0.5 with respect to the axial thickness 16a of the wing-side fork at the portion where the radial outer pin passes. It is desirable to have.

At this time, it is customary to form a fillet in the step portion 9 having a different thickness in the axial direction of the fork, so that stress concentration is eased by this. The radius of the arc is 1mm
The above is desirable.

In the above embodiment, the case where the axial thickness of the wing-side fork 12 is the same for the fork located at the axial end and the axial center is generally described. When considered, the stress acting on the fork located at the axial center is increased.

Therefore, in an embodiment of the present invention, the axial width of the fork at the axial center may be thicker than the width at the axial end. 2 has the effect of increasing the strength reliability of the blade implant portion. Next, in FIG. 2, the axial end 17 of the blade root profile 5 is located on the first blade side from the axial end. It is desirable to be located on the forks 12a, 12b or at an axial end of the wing-side fork.

This is because the transmission of force to the fork located at the axial end is improved.

Here, in the above-described embodiment, the case where nine wing-side forks are provided in the axial direction has been described. However, as an embodiment of the present invention, if the number of forks is three or more, other forks are used. Obviously, the same operation and effect can be expected.

In the same manner, in the above-described embodiment, the structure in which the three pins are fastened by passing three pins in the radial direction has been described. However, similar effects can be expected with other numbers of pins.

However, if there is only one pin in the radial direction, the rotation cannot be restrained, which is not appropriate. Further, if the number of pins is increased, the sharing of the pins located on the radially inner peripheral side becomes small. In consideration of the fact that the effect of increasing the number of pins is hardly obtained, it is generally desirable that the number of pins located in the radial direction be two or more and four or less.

Next, another embodiment of the present invention will be described.

First, FIGS. 11A and 11B show a second embodiment of the present invention. Here, FIG. 11A is a side view of the wing-side fork viewed from the circumferential direction, and FIG. ) Is a cross-sectional view as seen from the AA direction in FIG. 2A, and as is apparent from FIG. 2B, this embodiment is the second wing-side fork 12c from the axial end. , And 12d are modified hexagons, and the other points are the same as those of the first embodiment described with reference to FIG. 1. The center of the pin is located on the ventral side with respect to the center of the circumferential width of the wing-side fork. are doing.

In the case of this embodiment, the sectional shapes of the second wing-side forks 12c and 12d from the axial end are modified into hexagonal shapes, so that the parallelogram-shaped wing-side forks 12c and 12d in the embodiment of FIG. In comparison, the back side cross sections 20c, 2d of these second wing side forks 12c, 12d
0d can be secured large, and there is an effect that the strength can be increased.

Here, FIG. 11C also shows AA in FIG. 11A.
FIG. 6 is a cross-sectional view as viewed from the direction, which shows a third embodiment of the present invention. In this embodiment, the angle θ of the step of the base portion 6 is increased, and The cross-sectional shapes of the first wing-side forks 12c and 12d can be made rectangular.

FIG. 11 (c) is also similar to the embodiment of FIG. 11 (b), in which the back side cross sections 20c, 20d of the second wing-side forks 12c, 12d can be kept large, and the strength can be increased. There is an effect that can be.

Here, the angle θ at this time is 40
It is desirable that the angle is 70 ° or more and 70 ° or less.

Next, FIGS. 12 (a), 12 (b) and 12 (c) show a fourth embodiment of the present invention. Here, FIG. 12 (a) is a side view of the wing-side fork viewed from the circumferential direction. (B) of the figure is a cross-sectional view as viewed from the AA direction in FIG. (A), and (c) is a cross-sectional view as viewed from the BB direction in (a) of FIG.

In the fourth embodiment, as shown in the figure, the portion 23 of the base portion 6 provided with the three wing-side forks 12g to 12i located at the center in the axial direction is moved rearward. Thereby, these three wing side forks 12g
Only in the case of １２12i, the center of the pin is moved to the ventral side with respect to the center of the fork width.

Here, of a plurality of wing-side forks arranged generally in the axial direction, the bending stress acting on the back side and the abdomen side of the wing-side fork located at the center in the axial direction becomes the largest, but according to this embodiment, 3 where bending stress increases
The center of the pin 3 is selectively shifted only for the wing-side forks 12g to 12i of the book, so that the strength can be efficiently increased.

In this embodiment, the center 3 in the axial direction is used.
Increased the amount of movement in the circumferential direction for the book fork,
It is not necessary to separately limit the number to three, and it is apparent that the same effect can be obtained as long as the fork is moved to the rear side as it approaches the center in the axial direction.

Next, FIG. 13 shows a fifth embodiment of the present invention. FIG. 13 (a) is a side view of the wing-side implant viewed from the circumferential direction.
(b) is a cross-sectional view as viewed from the AA direction in FIG. (a), and FIG.
3 shows a cross-sectional view as viewed from the CC direction.

Here, the wing length is short and the number of wing forks is 5
For smaller wings, the first wing-side fork from the axial end may not need to be circumferentially shifted with respect to the fork located at the axial center.

The embodiment shown in FIG. 13 corresponds to such a case. As shown in FIG. 13, the center positions of the holes 13 and the pins 3 in all the wing-side forks 12a to 12e are set in the circumferential direction of the wing fork. It is positioned on the center line X _OFF shifted to the abdominal side in the circumferential direction with respect to the width center line X. Therefore, according to this embodiment, the same operation and effect as the other embodiments described above are expected. it can.

[0087]

According to the present invention, in the coupling structure of the turbine rotor blade and the disk having the fork-shaped blade implantation portion, a large bending can be achieved by changing the position of the blade-side fork coupling pin located at the axial center portion. By increasing the effective cross-sectional area on the ventral side on which the stress acts and by positioning the center of gravity of the blade on the ventral side in the circumferential direction, the bending stress acting on the dorsal side and the ventral side can be reduced.

Therefore, according to the present invention, the local stress generated around the circular hole of the blade fork can be reduced, and there is an effect of increasing the strength reliability of the blade implant portion against low cycle fatigue and high cycle fatigue.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of a turbine rotor blade in an embodiment of a turbine impeller according to the present invention.

FIG. 2 is a sectional view of a turbine rotor blade according to an embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a turbine rotor blade-side fork portion according to the embodiment of the present invention.

FIG. 4 is a side view of a turbine bucket side fork portion according to the embodiment of the present invention.

FIG. 5 is a side view of the entire turbine rotor blade-side fork portion according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a coupling structure of a turbine blade and a disk having a general fork-shaped blade implant.

FIG. 7 is an explanatory view of a turbine rotor blade fork section in the related art.

FIG. 8 is a characteristic diagram showing a load distribution at a turbine bucket side fork.

FIG. 9 is an explanatory diagram of stress in a turbine bucket side fork.

FIG. 10 is a characteristic diagram for explaining a relationship between a pin position and a stress.

FIG. 11 is an explanatory view of a turbine bucket according to another embodiment of the present invention.

FIG. 12 is an explanatory diagram of a turbine bucket according to another embodiment of the present invention.

FIG. 13 is an explanatory view of a turbine bucket according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine rotor blade 2 Turbine rotor 3 Pin 5 Blade root profile 6 Base part 7 Base circumferential stepped part 8 Turbine rotor disk 9a to disk side fork 10 Blade part 12a to 12i Blade side fork 13 Hole on blade side fork side 13a Half circle Hole 14 Distance between the back side of the blade root profile and the back side of the base section 15 The path from the ventral side to the back side of the upper surface of the wing side fork 16a, 16b, 16c Thickness in the axial direction of the wing side fork 17 Blade root section profile end 19 Quadrilateral Apex 20c-20i Cross section on the back side of wing side fork 21c-21i Cross section on the ventral side of wing side fork 22 Hole on disk side fork side

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeo Sakurai 502 Kandachi-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Kiyoshi Namura 7-2-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Power and Electricity Research Laboratory (72) Inventor, Naoaki Shibashita 3-1-1, Komachi, Hitachi, Ibaraki Pref.Hitachi, Ltd., Thermal and Hydropower Division (72) Inventor, Takeshi Onoda, Ibaraki 3-1-1, Sachimachi, Hitachi-shi, Hitachi, Ltd. Thermal and Hydro Power Division, Hitachi, Ltd. (72) Inventor Shimichi Inoue 3-1-1, Sachimachi, Hitachi-shi, Hitachi, Ibaraki Prefecture F, Thermal and Hydro Power Division, Hitachi, Ltd. Terms (reference) 3G002 FA05 FA08 FB01

Claims (2)

[Claims] 1. A turbine impeller in which a turbine rotor blade is connected to a rotor disk by penetrating a pin into a stud portion of a fork, wherein a position where the center of the pin penetrates a blade-side fork is defined by a portion where the pin is located. A turbine impeller, which is shifted from the center of the circumferential width of the wing-side fork to the wing-ventilation side so as to obtain a balanced stress on the wing-side and wing-back side of the wing-side fork. 2. The invention according to claim 1, wherein the displacement amount is 0.0 of a circumferential width of the wing-side fork.
A turbine impeller, wherein the turbine impeller is configured to have a value of 3 or more and 0.13 or less.