JP2839586B2 - Turbine blade connection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a coupling device for a turbine rotor blade, and more particularly to a turbine rotor blade that can effectively suppress vibration of the turbine rotor blade during operation. It relates to a coupling device.

(Conventional technology) Since excessive centrifugal force acts on the turbine blade at the time of high-speed rotation, consideration is given to the stress of each part of the turbine blade at the time of turbine design so as to have a sufficient margin with respect to the allowable stress of the material. However, as the capacity of turbines increases,
The length of the turbine rotor blade has been increased, and especially in the case of a long blade such as a low-pressure last stage blade, a design has been made in which there is not enough room for the material strength locally.

On the other hand, with the increase in base load operation of nuclear power generation in recent years, relatively large-capacity thermal turbines are often used for power load adjustment. In the thermal turbine for load adjustment, operation such as frequent start and stop on a daily basis (hereinafter referred to as DSS operation) and low-load operation that is significantly below the design point of the turbine are performed.

When designing a turbine blade with long blades, it is generally designed to be sufficiently detuned so that the natural frequency of the blade does not coincide with an integral multiple of the rotation speed at the rated rotation speed. When the rotation is performed, the natural frequency of the blade and the rotational frequency component coincide with each other when the rotation is increased or decreased, and resonance occurs, and a large vibration stress may be generated on the blade. Further, in the operation under the low load condition, the vortex or the disturbance of the flow due to the separation of the flow of the driving fluid acts on the turbine blade as an exciting force, so that the vibration stress of the turbine blade increases.

In particular, since the turbine blade on the low pressure final stage blade side is a long blade, it is inevitable that the turbine blade is exposed to a severe environment in terms of both static stress and vibration stress.

As a method of reducing the vibration of the turbine blade,
There is a turbine rotor blade connecting device that provides a through hole in a middle portion of a steam passage portion of each blade, and connects adjacent blades through a tie wire to each of the through holes. In this case, the vibration of the turbine blade is suppressed by utilizing the friction between the tie wire and the inner surface of the through hole due to the centrifugal force acting on the tie wire.

As another typical example, there is a coupling device for turbine blades described in Japanese Patent Publication No. 52-18841. This coupling device is ninth
As shown in FIG.
And a lug 2a (hereinafter, referred to as a lug) is provided on the boss 2, and the opposing lugs are connected to each other by a cylindrical connecting piece (hereinafter, referred to as a sleeve) 3, and the adjacent turbine blades 1 are formed. It connects the two. In this connection device, the friction between the surfaces of the lug 2 a and the sleeve 3 generated by the centrifugal force acting on the sleeve 3 suppresses the vibration of the turbine rotor blade 1.

(Problem to be Solved by the Invention) In the conventional turbine rotor blade connecting device, in the former connection of the turbine rotor blades by the tie wire, the stress around the through hole of the blade effective portion increases. In particular, the blade stress may locally become a stress close to the material strength due to the increase in centrifugal force accompanying the elongation of the turbine blade, but stress concentration is likely to occur around the tie wire hole. This stress concentration is generally avoided by increasing the thickness of the wing around the tie wire hole.
However, another problem with long wings is that untwisting of the wings due to centrifugal force creates a bending moment in the tie wire. The bending stress due to the untwist of the wing, the bending stress due to the centrifugal force of the tie wire itself, and the vibration of the wing may be applied, and the tie wire may be damaged.

In the latter connection device for a turbine blade using a lug sleeve, among the combined lug 2a and sleeve 3, the shape of the sleeve 3 is determined in consideration of the untwist of the blade as shown in the plan view of FIG. By forming a cutout in a part of the sleeve end faces 4a and 4b, it is formed in a U shape, and the cutout is made parallel to the other end of the sleeve facing away. Further, as shown in FIG. 11, the cross-sectional shape of the fitting portion between the sleeve 3 and the lug 2a has a shape close to streamline in both cases. The reason for adopting such a non-circular cross section is firstly to prevent the sleeve 3 from rotating around the lug 2a to accelerate the wear of both, and secondly, to reduce the flow resistance of the driving fluid. This is for reduction. Also between the inner peripheral surface and the lug 2a the outer peripheral surface of the sleeve 3, the gap S _1, S ₂ are formed, movement of the sleeve 3 by the gap S _1, S ₂ can be smoothly maintained. The angle between the sleeve end surfaces 4a and 4b is determined by the untwist amount of the blade cross section where the lug 2a is formed. However, it is difficult to accurately grasp the amount of untwist in the middle portion of the wing, and it is very difficult to properly set the angle α between the end faces 4a and 4b. If the angle α between the end surfaces 4a and 4b is small, the sleeve 3 restrains the wing when the wing is untwisted, causing excessive stress on the wing. Conversely, if the angle α is too large, the sleeve 3 may fall off before the wings untwist or when the untwist returns.

Further, the sleeve 3 has a serious problem in processing.
First, there are two methods for processing the end face of the sleeve 3. One of the methods is to process the end faces 4a and 4b of the sleeve one by one in a separate process, and to make the boundary between the end face 4a and the end face 4b a smooth R shape by hand finishing.
The process from 4a to the end face 4b is processed in one process using an NC machine tool.

In the first sleeve processing method, there are problems such as an increase in the time for replacement of the material due to an increase in the number of processes, generation of a processing error due to the replacement, and a difference between the finished shape and the design shape due to the intervention of hand finishing. Further, in the second sleeve processing method, since the cutting direction changes suddenly from the sleeve end face 4a to the end face 4b, the cutting resistance of the cutter changes, chatter vibration and the like are easily generated, and a processing error occurs. These shape or dimensional errors cause the sleeve to constrain the wing and thus cause excessive stress.

On the other hand, in a conventional turbine rotor blade coupling device in which notches are formed at both end surfaces of the sleeve, there is a risk that the sleeve may be set in the opposite direction due to a human error when the turbine rotor blade is assembled. This issue is discussed below.
This will be described with reference to FIG. 12 and FIG.

That is, FIG. 12 is a diagram showing a structure in which the turbine blades 1 are connected to each other by the sleeve 3 so that the axes of the adjacent lugs 2a, 2a are aligned with each other when the turbine blades 1 are stationary. However, the mounting direction of the sleeve 3 is opposite to the original direction, and the notches 100, 100 of the sleeve 3 are located on the rotor blade trailing edge side on the rotation front side, and are located on the rotor blade leading edge side on the rotation rear side. ing. As is apparent from the cross-sectional shapes of the sleeve 3 and the lug 2a shown in FIG. 11, the sleeve 3 cannot be mounted left and right reversed, but a human error in mounting the sleeve 3 back and forth with respect to the rotating blade rotation direction. The probability of occurrence of is very small but possible.

When the turbine blades assembled as shown in FIG. 12 are rotated at a high speed, the adjacent lugs 2a, 2a are shifted to each other right and left due to clockwise untwist deformation of the blade 1 as shown in FIG. At this time, the sleeve 3
Both ends on the side where no boss is formed may interfere with the boss 2 or easily fall off. However, in an actual turbine blade, the sleeve 3 itself may be damaged before the interference becomes severe,
Or, as a result of the sleeve 3 being sandwiched between the opposing bosses 2, 2, the untwisted deformation of the moving blade 1 is restrained, and excessive stress is generated in the moving blade 1, which may damage the moving blade 1. Is also left.

As described above, in the conventional turbine blade connection device, delicate differences in the design dimensions of each part, processing errors or assembly work errors can cause excessive stress on the blades,
In thermal power turbine long blades and the like in severe use environments, a more reliable turbine blade connection device is desired.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a highly reliable and excellent turbine rotor blade connection device for a turbine long blade exposed to a severe operating environment such as low load and DSS operation.

[Configuration of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems of the prior art, a connecting device for turbine blades according to the present invention has a structure in which a number of turbine blades mounted on the outer periphery of a turbine rotor face each other. A boss is formed on the blade surface, lugs are provided at both ends of the boss in the axial direction of the boss, and turbine blades adjacent to each other are movably connected to each other by a sleeve interposed in the lug. In the connecting device, at least one of the end surface of the sleeve and the seat surface of the lug is formed into a smooth curved surface, and the center of curvature of the smooth curved surface is offset from the center of the sleeve axis in the turbine rotor axial direction.

Further, in order to solve the above-described problem, the connecting device of the turbine blade has both end surfaces of the sleeve formed in an arc surface (curved surface) having a predetermined radius of curvature, and is formed at both end portions of the sleeve. The center of curvature of each arc surface is offset from the center of the sleeve axis in the turbine rotor axial direction, and both centers of curvature are provided symmetrically with respect to the center of the sleeve, or the lug seating surface is formed as a convex curved surface protruding toward the sleeve. It was done.

Further, both end surfaces of the sleeve may be formed in a plane shape parallel to the direction perpendicular to the axis, and notches may be formed in the seat surfaces of the opposing lugs to face each other.

(Operation) With this configuration of the turbine moving blade coupling device, the sleeve smoothly moves along the curved surface when the turbine moving blade undergoes untwist deformation as the rotation of the turbine rises. In the shifting process from the standstill to the rated speed, there is no inflection point or singular point in the cross-sectional shape of both ends of the sleeve, so the sleeve and lug or the sleeve and lug seat surface move smoothly without sticking at all. Things. Also, during the rated rotation of the turbine, the sleeve slides between the lugs without sticking, and an excellent friction mechanism is obtained, so that it is possible to exhibit an excellent vibration damping effect on the vibration of the turbine blade. .

Also, without providing notches on both end faces of the sleeve itself,
When both end surfaces are formed in a plane shape parallel to the direction perpendicular to the axis, and the notch is formed only in the bearing surface of the lug, there is no difference in shape between the front and rear of the sleeve. Therefore, even when the arrangement direction of the sleeve is mistaken during the assembly of the moving blade, the movement of the sleeve is not affected. Therefore, the rotor blade can be easily assembled without paying much attention to the mounting directions before and after the sleeve.

Further, since the sleeve itself is not notched, the contact area with the lug does not decrease. That is, compared to the conventional device in which the sleeve itself is notched, the sliding friction force between the sleeve and the lug is less likely to decrease, and an excellent vibration damping effect can be obtained.

(Embodiment) Hereinafter, an embodiment of a connecting device of a turbine bucket according to the present invention will be described with reference to FIGS. 1 to 8.

FIG. 1 shows a turbine wheel provided with a turbine rotor blade connecting device according to the present invention. In this turbine wheel, a turbine rotor blade 12 is implanted on an outer peripheral portion of a rotor wheel 10 as a turbine rotor via an implant 11. The turbine rotor blade mounting structure shown in FIG. 1 is an exemplification, and the connection structure can be applied to any known turbine blade mounting structure. A sleeve 13 is interposed at the center between adjacent blades of the turbine rotor blade 12, and this sleeve 13
The adjacent turbine rotor blades 12 are interconnected.

FIG. 2 is a plan view showing a connecting device of the turbine rotor blades 12,
The stationary state before the turbine rotor blade 12 undergoes untwist deformation is shown by taking out two turbine rotor blades 12 and 12. Bosses 15 are provided at the center of the blades of the turbine blades 12, 12, and lugs 16 a, 16 b are provided at both ends of the boss 15 so as to protrude in the axial direction of the boss 15, respectively. These bosses 15
The lugs 16a and 16b are formed integrally or integrally with the turbine blade 12. One side protruding portion (lug) 15a of the boss 15 of one turbine blade 12 is connected to the boss 1 of the adjacent turbine blade 12.
It faces 5 protrusions (lugs) 15b. In the present embodiment, the case where the axes of the lugs 16a and 16b which are adjacent to each other are shifted from each other in the stationary state has been exemplified.

Adjacent turbine blades 12, 12 are movably connected by a sleeve 13 provided with lugs 15a, 15b projecting from both ends of the boss 15. The ends 13a and 13b of the sleeve 13 are formed into a curved shape that is convex outward. As the shape of the curve, any curve such as an arc having a constant curvature, a cycloid curve, and an involute curve can be used. A clearance CL is set between the bearing surfaces of the lugs 16a and 16b and the sleeve 13, and the sleeve 13 can move in the circumferential direction of the turbine wheel.

FIG. 3 shows the case where the shape of the sleeve 13 is a curved surface at the side end of the sleeve 13 is an arc having a constant curvature. Sleeve 13
The end faces 13a and 13b are arc radius is R ₁ and R ₂ each center C ₁ and C ₂ of the arc are offset to the left and right with respect to the axial center of the sleeve 13. That is, the center C ₁ and C ₂ of each arc is offset a radial from the axis center of the sleeve 13 in the direction along the axial direction of the turbine rotor. The overall offset amount S is set by the untwist amount of the rotor blade and the like.

 Next, the operation of the coupling device for the turbine blade will be described.

FIG. 4 is an enlarged view showing a connected state after the turbine rotor blade has been untwisted. In this case, the end face 13 of the sleeve 13
Since a and 13b are arc surfaces (or may be spherical),
Following the untwist of the turbine blades 12, 12, the sleeve 13 moves smoothly without sticking to the lugs 16a, 16b, and transitions to the state shown in FIG. Therefore, while the rotation of the turbine blade 12 is rising, the sleeve 13
And no high stress is generated by the lag constraint.

The relative movement of the sleeve 13 with respect to the blade after the turbine rotor blade 12 has been untwisted is mainly a reciprocating motion in the sleeve axial direction indicated by arrows B ₁ and B ₂ , and the sleeve 13 which has received centrifugal force.
And the sliding friction between the lower surfaces of the lugs 16a and 16b provides a vibration damping effect of the turbine blade.

Further, when the end shape appearing in the plan view of the sleeve 13 according to the present invention is an arc shape, the following operation is obtained.

First, the sleeve 13 is moved in the direction of arrow B ₁ lug 16
When the seat of b comes into contact with the sleeve 13, the reaction force F ₁
Act on. The direction of the reaction force F ₁ is an end 13a of the sleeve 13
Of a normal direction of the arcuate surface, facing the direction of the arc of curvature of the center C _1. Accordingly moment counterclockwise Figure 4 is generated in the sleeve 13, the lugs 16a, the reaction force of the rotor shaft direction F ₃ and F ₄ will act against 16b. That is, the sleeve 13 and the lug 1 are also provided on the side surfaces of the lugs 16a and 16b.
The frictional forces μF ₃ and μF ₄ with 6a and 16b are generated, and become effective vibration damping mechanisms.

Counterclockwise moment in the same manner even when moving the sleeve in the direction opposite the arrow B ₂ are the same effect occurs to the arrow B _1.

Further, since the end face of the sleeve has an arcuate shape, the amount of untwist of the turbine rotor blade cannot be set accurately, and even if the position where the reaction force F ₁ acting on the sleeve 13 acts changes, the reaction force F ₁
Direction is always facing the center C ₁ of arc sleeve end.
Sleeve 13 is similar for the arrow B ₂ movement.
Therefore, a counterclockwise moment acts as in the normal design position, and the lugs 16a, 16b inevitably come into contact with the side surfaces of the sleeve 13. If the bearing surfaces of the lugs 16a and 16b and the end surface of the sleeve 13 are respectively flat, there is a disadvantage that the movement of the sleeve 13 with respect to the wing is easily restricted.

End of sleeve 13 that constitutes a connection device for turbine blade
Another great advantage of making each of the arcs 13a and 13b an arc is an advantage in processing the sleeve. sleeve
Even if the end of 13 is formed in an arc shape or the curvature is changed, if the change rate is made small and a smooth curved surface shape, the cutting resistance of the cutter when processing the sleeve end is Does not suddenly change, there is no problem such as chatter or bending of the cutter, and the designed shape can be accurately machined. In addition, since the end face of the sleeve 13 having such a shape can be easily processed in one step by using the NC machining mechanism, there is an advantage in terms of processing cost. Especially the third
As shown in the figure, when the end of the sleeve 13 is an arc having a constant radius of curvature R ₁ , R ₂ , even with a general-purpose machine tool other than NC, the material is rotated around the center C ₁ and C ₂ of the arc so that the sleeve 13 Each end can be processed in one step.

The coupling device of the turbine rotor blade has a curved end surface of the sleeve 13 so that the movement of the sleeve 13 during rotation ascent is smooth, and the lugs 16a, 16b and the sleeve 1
No high stress is generated in the turbine blade 12 by the stick 3 or the like. While the turbine blade 12 is rotating, the lug 16
A moment due to the reaction force between the seats a and 16b and the end of the sleeve 13 acts on the sleeve 13, friction occurs on the side surfaces of the lugs 16a and 16b, and a vibration damping effect on the vibration of the turbine blade 12 is generated. Even if the position of the sleeve 13 deviates from the design movement position at the time of untwisting, the same effect is obtained.

Further, by forming the end of the sleeve 13 into an arcuate curved surface, processing becomes accurate and easy.

FIG. 5 shows a second embodiment of the connecting device for turbine blades.

The connecting device of the turbine rotor blades is
A boss 20 is formed at the center of the wing, and lugs 21a and 21b project from both ends of the boss 20 in the axial direction of the boss. A sleeve 22 movably connects adjacent turbine blades 12, 12 via lugs 21a and 21b. In this embodiment, the end surfaces of both ends 22a and 22b of the sleeve 22 are formed so as to form a flat surface, and instead, the bearing surfaces 2 of the lugs 21a and 21b of the boss 20 are formed.
3a and 23b form a curved surface with curvature radii R ₃ and R ₄ . C ₃ , C ₄
Is the center of curvature of the arc (curved surface). That is, the center of curvature C ₃ of provided on the ventral side of the turbine blade 12 the seat surface 23b is a radial direction from a shaft center of the sleeve 22 in a direction along the axial direction of the turbine rotor, the offset amount and S ₃ It is offset to such a position. On the other hand, the center of curvature C ₄ bearing surface 23a provided on the back side of the turbine blade 12 is a radial direction from a shaft center of the sleeve 22 in a direction along the axial direction of the turbine rotor, the offset amount and S ₄ It is offset to such a position. The respective curvature radii R ₃ and R ₄ and the total offset amount (S ₃ + S ₄ ) are set in consideration of the untwist amount of the turbine rotor blade 12 and the like. FIG. 5 shows a state after the turbine blades 12, 12 have been untwisted by centrifugal force.

According to this, when the sleeve 12 reciprocates in the circumferential direction of the turbine wheel, the sleeve 22 becomes the lug seat 23a or 23b.
When a contact is made, a reaction force is applied in the normal direction of the
A counterclockwise moment acts on 22. For this reason,
Due to the centrifugal force of the sleeve 22, the lower surface of the lugs 21a and 21b
In addition to contacting the sleeve 2, the sleeve 22
The contact with the cylinder surely occurs, and an effective vibration damping effect due to friction can be expected. Further, since the bearing surfaces 23a, 23b of the lugs 21a, 21b are formed in an arc shape, even when the amount of untwist of the turbine rotor blades changes due to the rise and fall of the rotation of the turbine wheel, the sleeve 22 holds the lugs 21a, 21b. It is possible to move smoothly without sticking to the surfaces 23a and 23b.

Further, according to the second embodiment shown in FIG.
Since there is no notch or the like in itself, there is no difference in shape before and after the sleeve 22. Therefore, at the time of assembling the rotor blade, the function of the sleeve 22 does not change even if the arrangement direction of the sleeve 22 is reversed. Therefore, since it is not necessary to pay attention to the mounting direction of the sleeve 22,
Is easy to assemble.

Further, since notches are not formed in the sleeve 22 itself, the contact area with the lugs 21a, 21b does not decrease.
That is, in the conventional device formed by cutting the three 22 itself, the contact area between the sleeve and the lug is reduced and the vibration damping effect due to the frictional force is reduced, but in this embodiment, the effect is not likely to be reduced.

In the first and second embodiments, one of the sleeve end surface and the lug seat surface is formed into a smooth curved surface. However, both the sleeve end surface and the lug seat surface are formed into a smooth curved surface. It may be shaped. For example, the sleeve end surface may be formed on a convex arc surface and the lug seat surface may be formed on a concave arc surface, or the sleeve end surface may be formed on a concave arc surface and the lug seat surface may be formed on a convex arc surface. In these cases, the radius of curvature of the concave arc surface is larger than the radius of curvature of the convex arc surface.

FIG. 6 shows a third embodiment of the coupling device for turbine blades.

The connecting device of the turbine rotor blades is
A boss 30 is formed at the center of the wing, and lugs 31a and 31b protrude from both ends of the boss 30 in the axial direction of the boss. The sleeve 32 is connected to the adjacent turbine blades 12, 12 via lugs 31a, 31b.
They are movably connected to each other. The end surface shape of the end of the sleeve 32 is a linear planar shape as in the embodiment of FIG.

On the other hand, as shown in the plan view of FIG. 6, the bearing surfaces of the lugs 31a and 31b have smooth, letter-shaped surfaces 33a and 33b; and 34a and 34b, respectively. The surfaces 33a and 34a are opposing surfaces before the turbine blade 12 is untwisted, that is, at rest, and the surfaces 33b and 34b are the opposing surfaces after the turbine blade 12 is untwisted, that is, at the time of rated rotation. .
If the sleeve 32 reciprocates in the circumferential direction of the turbine wheel while the turbine blade 12 is rotating, the contact position with the lug seat is eccentric, so that a counterclockwise moment acts on the sleeve 32 in FIG. Also, friction occurs with the sleeve 32 on the lug side surface. Therefore, the lugs 31a,
The friction between the lower surface and the side surface of the 31b produces a sufficient vibration damping effect. Further, since the end face of the sleeve 32 is straight and smooth, it is possible to smoothly follow the untwist deformation of the turbine blade 12.

Also, in the case of the present embodiment, since there is no notch or the like in the sleeve 32 itself, there is no difference in shape before and after the sleeve 32. Therefore, the function of the sleeve 32 is not lost even if the arrangement direction of the sleeve 32 is reversed when the moving blade is assembled, and the moving blade can be easily assembled.

Further, since notches are not formed in the sleeve 32 itself, the contact area with the lugs 31 and 31b does not decrease, and there is little possibility that the vibration damping effect due to the frictional force is reduced.

Next, a description will be given of a turbine blade connection device according to a fourth embodiment with reference to FIGS. 7 and 8. FIG.

FIG. 7 is a plan view showing two turbine blades 12 in a stationary state before the turbine blades 12 are untwisted. Boss 4 at almost the center of turbine blade 12
0, 40a, 40 are provided, and at both ends in the axial direction of the boss 40,
Lugs 41a and 41b are provided to protrude, respectively. These bosses 40 and lugs 41a, 41b are formed integrally or integrally with the turbine blade 12. Further, in this embodiment, an example is shown in which the axial center positions of the opposing lugs 41a and 41b coincide with each other when the turbine blade 12 is stationary. The adjacent turbine blades 12, 12 are movably connected by sleeves 42 interposed in lugs 41a, 41b projecting from both ends of the boss 40. And the bearing surfaces 43a, 4 of the adjacent opposing lugs 41a, 41b
Notches 101a and 101b are formed in 3b so as to face each other. The notches 101a and 101b are formed so as to be inclined from the substantially central position of the lugs 41a and 41b toward the peripheral direction. On the other hand, both end surfaces 44a and 44b of the sleeve 42 are formed in a plane shape parallel to the direction perpendicular to the axis.

FIG. 8 is a plan view showing a state in which the turbine blade 12 equipped with the coupling device of the turbine blade shown in FIG. 7 is rotated at a high speed, and shows a state in which the turbine blade 12 is untwisted. . At this time, since the axial center positions of the adjoining lugs 41a and 41b are shifted from each other, the sleeve 42
Is rotated clockwise with respect to the direction of rotation of. In this state, the gap between the end surfaces 44a, 44b of the sleeve 42 and the bosses 40a, 40b is reduced. However boss 4
Since the cutouts 101a and 101b are provided in 0a and 40b, the sleeve 42 does not interfere with the bosses 40a and 40b, and the sleeve 42 prevents untwist deformation of the turbine blades 12 and 12. Not at all. In other words, even if the sleeve 42 has no cut, the opposing boss 40
The notches 101a and 101b formed in the a and 40b allow the untwisted deformation of the turbine moving blade 12, and the sleeve 42 can smoothly follow the deformation of the turbine moving blade 12.

Further, since no cut is formed in the sleeve 42 itself as in the conventional device, there is no directionality in the front-back direction with respect to the rotation direction of the turbine blade 12. Therefore the turbine blade
Even if the worker mistakenly arranges the mounting direction of the sleeve 42 during the assembling operation of 12, the connection characteristics are not affected.

Furthermore, since the bearing surfaces 43a and 43b of the lugs 41a and 41b of the turbine blade 12 are notched, the sleeve 42 does not stretch even when the turbine blade 12 is untwisted due to centrifugal force during rotation. It is also possible to prevent an excessive stress from acting locally on 12.

In addition, as shown in FIGS. 10 and 12, in the case of the present embodiment, the sleeve 42 itself is not notched as compared with the case of the conventional device in which a cut is formed in the sleeve 3, so that the sleeve 42 and the lug 41a are formed. , 41b does not decrease. Therefore, the damping action caused by the sliding frictional force between the sleeve 42 and the lugs 41a, 41b is hardly reduced, and a turbine blade having a high damping effect can be formed.

On the other hand, the difference in the centrifugal force between the case where the notch is formed in the sleeve 42 and the case where the notch is not formed is small, but the bosses 40a, 40
Since the reduction amount of the centrifugal force when the notches 101a and 101b are formed in b is extremely large, it is extremely effective in relieving the stress acting on each part of the turbine rotor blade 12.

In the fourth embodiment shown in FIGS. 7 and 8, when the turbine blades 12 are stationary, the axes of the lugs 40a and 40b are aligned, while the turbine blades 12 are untwisted during rotation. In this case, the axes of the lugs 41a and 41b are shifted. However, contrary to the fourth embodiment, when the axis is shifted at the time of rest, while the axis is aligned at the time of rotation, the inclination direction of the notch formed on the end faces 43a, 43b of the lugs 41a, 41b is It goes without saying that it is opposite to the notches 101a and 101b shown in FIG.

〔The invention's effect〕

As described above, in the turbine rotor coupling device according to the present invention, at least one of the end surface of the sleeve and the bearing surface of the lug is formed into a smooth curved surface, and the center of curvature of the smooth curved surface is set at the center of the sleeve axis. The sleeve moves smoothly in accordance with the change in the amount of untwist deformation of the turbine blade due to the rise and fall of the rotation of the turbine, and the untwist of the turbine blade Does not constrain deformation. Therefore, no high stress is generated on the turbine blade due to the lug constraint.

In addition, at least one of the end surface of the sleeve and the bottom surface of the lug is formed into a smooth curved surface, and the center of curvature of the smooth curved surface is radially offset from the center of the sleeve axis. There is no inflection point or singular point, the sleeve and lug exhibit smooth movement without sticking, and the moment applied to the sleeve ensures the contact with the sleeve not only on the lug bottom surface but also on the lug side surface The friction surface increases, and effective vibration damping effect due to friction can be expected.
Since the processing is performed with a smooth curved surface shape, the design shape can be processed accurately and accurately without a small change rate of the curved surface and abrupt change in the cutting resistance of the cutter.

In addition, if both ends of the sleeve are formed in an arc surface, and the center of curvature of the arc surface is offset in the radial direction from the axis of the sleeve, the sleeve receives a moment in a horizontal plane in addition to the rotational centrifugal force. In addition to the contact with the sleeve on the lower surface, the contact with the sleeve is also ensured on the lug side surface. For this reason, the frictional surface increases due to the increase in the number of contact portions, and the sleeve has a vibration damping effect more than before, and it is possible to suppress the vibration stress generated in the turbine blade to a low level.

Also, without providing notches on both end faces of the sleeve itself,
When both end surfaces are formed in a plane shape parallel to the direction perpendicular to the axis, and the notch is formed only in the bearing surface of the lug, there is no difference in shape between the front and rear of the sleeve. Therefore, even when the arrangement direction of the sleeve is mistaken during the assembly of the moving blade, the movement of the sleeve is not affected. Therefore, the rotor blade can be easily assembled without paying much attention to the mounting directions before and after the sleeve.

Further, since the sleeve itself is not notched, the contact area with the lug does not decrease. That is, compared to the conventional device in which the sleeve itself is notched, the sliding friction force between the sleeve and the lug is less likely to decrease, and an excellent vibration damping effect can be obtained.

With these effects, it is possible to provide an excellent turbine long blade which is sufficiently reliable even under severe operating conditions of the turbine.

[Brief description of the drawings]

1 is an explanatory view of a turbine rotor blade showing one embodiment of a turbine rotor blade connecting device according to the present invention, FIG. 2 is a plan view illustrating the configuration of the turbine rotor blade connecting device of the present invention, and FIG. Is a plan view illustrating the shape of the coupling device of the turbine blade,
FIG. 4 is a plan view for explaining the operation of the turbine rotor blade connecting device according to the present invention, and FIGS. 5 and 6 show second and third embodiments of the turbine rotor blade connecting device according to the present invention, respectively. FIG. 7 is a plan view showing a fourth embodiment of the present invention, FIG. 8 is a plan view showing a state where the turbine blade shown in FIG. 7 is rotated, and FIG. 9 is a conventional turbine blade. FIG. 10 is a plan view illustrating the configuration of a conventional turbine rotor blade connecting device, FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. 10, and FIG. FIG. 13 is a plan view showing another configuration example of the coupling device for the turbine blade, and FIG. 13 is a plan view showing a state where the turbine blade shown in FIG. 12 is rotated. 10 ... rotor wheel, 11 ... implant, 12 ... turbine blade, 13, 22, 32, 42 ... sleeve, 13 a, 13 b; 22 a, 22 b; 44
a, 44b …… Sleeve end face, 15,40 …… Boss, 16a, 16b; 21a,
21b; 31a, 31b; 41a, 41b ... rugs, 100, 101a, 101b ... notches.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01D 5/22-5/24

Claims (4)

(57) [Claims] 1. A boss is formed on opposing blade surfaces of a number of turbine blades mounted on the outer periphery of a turbine rotor, and lugs are provided at both ends of the boss so as to protrude in the boss axial direction. In a turbine blade connection device in which mutually adjacent turbine blades are movably connected by a sleeve, at least one of an end surface of the sleeve and a seat surface of the lug is formed into a smooth surface shape having a predetermined radius of curvature. A coupling device for a turbine rotor blade formed by molding and offsetting the center of curvature of this smooth curved surface from the center of the sleeve axis in the axial direction of the turbine rotor. 2. The method according to claim 1, wherein both end surfaces of the sleeve are formed as arc surfaces having a predetermined radius of curvature, and the center of curvature of each arc surface formed at both end portions of the sleeve is offset from the center of the sleeve axis in the turbine rotor axis direction. 2. The turbine rotor blade connecting device according to claim 1, wherein the connecting portions are located symmetrically with respect to the center of the sleeve. 3. The coupling device for a turbine rotor blade according to claim 1, wherein the lug is formed in a convex curved shape protruding toward the sleeve from the bearing surface of the lug. 4. A boss is formed on opposing blade surfaces of a large number of turbine blades mounted on the outer periphery of a turbine rotor, and lugs are provided at both ends of the boss so as to protrude in the boss axial direction. In a turbine blade connecting device in which mutually adjacent turbine blades are movably connected by a sleeve to be formed, both end surfaces of the sleeve are formed in a plane shape parallel to a direction perpendicular to an axis, and seats of adjacent opposing lugs are formed. A coupling device for a turbine blade, wherein a notch is formed on a surface of the turbine blade opposite to the surface.