JPH08303205A - Turbine moving blade - Google Patents

Abstract

PURPOSE: To prevent vibration of a moving blade alone so as to increase rigidity by arranging semi-elliptic holes along the longitudinal directions of respective face on the opposed side faces between integral shrouds. CONSTITUTION: A moving blade 1 consists of a dovetail 2 to be inserted into a disk in a rotor, a blade part 3, and an integral shroud 4. On a circumferential end face 4a in the integral shroud 4, a send-elliptic hole 5 along the longitudinal direction of the integral shroud side face is perforated for insertion of a plate spring. In the same way, a hole 5 for insertion of a plate spring is perforated in a face 4b opposed to the circumferential end face 4a in the integral shroud 4. When the dove tail 2 is inserted into a blade groove and a circular blade cascade is formed, the holes 5 function as a single hole along the longitudinal direction of a single elliptic integral shroud side face. In this way, connection effect between the adjacent integral shrouds is generated, so that rigidity increasing effect and vibration damping effect for the circular blade cascade can be accomplished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shrouded rotor blade which is integrally machined into a rotor of a turbine to form an annular blade row.

[0002]

2. Description of the Related Art An axial turbine includes a rotor blade which is embedded in an annular blade groove formed around a disk of a rotor to form an annular blade row, and flows out from a stationary blade which forms a paragraph with the rotor blade. The rotating fluid is blown onto the rotor blades to rotate the rotor and generate power.

As one of such moving blades, one shown in FIG. 6 is known. In FIG. 6, a rotor blade 1 includes a dovetail 2 that is implanted in a disk of a rotor, a blade portion 3 that extends from the dovetail 2, and an integral shroud 4 that covers an upper end of the blade portion 3.
The dovetail 2, wings 3, and integral shroud 4 are machined together.

In such a moving blade, as shown in FIG. 7, the opposite side surfaces 4a and 4b of the integral shroud 4 of a plurality of adjacent moving blades 1 are in contact with each other, and the dovetail 2 is also in contact with the same side surface. And is embedded in a disk provided on the rotor to form an annular blade row.

As described above, in the moving blades forming the annular blade row, the integral shroud and the dovetail of the adjacent moving blades are in contact with each other, whereby the vibrations of the moving blades generated when the turbine is rotated are attenuated and the vibrations are reduced. .

[0006]

In the rotor blades of the annular blade row formed as described above, there is a gap between the adjacent integral shrouds due to centrifugal force or thermal expansion generated when the turbine rotates, and the rotor blades adjacent to each other. No longer contact. For this reason,
Since the damping effect of vibration is lost and the blade vibrates independently,
There is a problem that the stress due to this vibration becomes large, and in the worst case, the moving blade is damaged.

It is an object of the present invention to prevent the moving blades forming the annular blade row from vibrating independently when the turbine is rotating, and connecting the moving blades to each other so that the dynamic constituent unit of the annular blade row is not a single blade. Another object is to provide an axial flow turbine blade whose rigidity can be increased by forming a group blade in which a plurality of blades are connected.

[0008]

In order to solve the above-mentioned problems, the present invention relates to a dovetail which is planted in an annular blade groove provided around a rotor, and a blade portion which extends from the dovetail.
Integral shroud covering the upper end of the blade is sequentially machined into a blade, and the dovetail is sequentially inserted into the blade groove, and the blade is installed at a predetermined pitch to form an annular blade row. When inserting the dovetail into the blade groove to form an annular blade row in a moving blade, semi-elliptical holes along the longitudinal direction of each surface are provided on the opposite side surfaces between the integral shrouds, and the shroud is formed. An oval hole is formed when the opposite surfaces of the blade face each other so that they face each other, a leaf spring is inserted into the hole, and the deflection of the leaf spring is expected to occur when the turbine is rotated integral. By inserting it in a state larger than the gap between the shrouds to form an annular blade row, a predetermined blade connection effect can be obtained even during rotation.

[0009]

[Function] The leaf spring between the integral shrouds of the rotor blade is
In the circumferential gap between the annular shrouds between the integral shrouds, which is expected to occur during turbine rotation, the holes installed on the opposite sides of the integral shroud face each other to form a single hole. More than happy
Use a large annular blade circumferential direction. Since the sum of the circumferential lengths of the turbine blades in the integral shroud is designed so as to form an annular blade row without a gap, a leaf spring is used when the blades form an annular blade row in the above method. , The initial deformation is given in the circumferential direction of the annular blade row.

By the initial deformation applied to the leaf spring, an elastic force is generated in the circumferential direction of the annular blade row, and the initial elastic force acts between the adjacent integral shrouds as an initial tension in the circumferential direction of the annular blade row. Even if a gap occurs between the integral shrouds of adjacent moving blades due to centrifugal force or thermal expansion during turbine rotation due to the circumferential tension of the annular blade row due to this leaf spring,
Since the leaf spring has been sufficiently deformed in advance, tension is constantly generated in the leaf spring in the circumferential direction of the annular blade row, the contact by the leaf spring is always maintained by this tension, and the connection between adjacent blades is always maintained. Therefore, the rotor blades that form the annular blade row are group blades, and the rigidity is increased compared to the case where a blade is not inserted and it becomes a single blade, and the vibration damping effect due to the friction between the spring and the shroud. Therefore, the blades can be prevented from being damaged.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view of a rotor blade showing an embodiment of the present invention, and FIG. 2 is a plan view of the rotor blade tip end portion as seen from the outer peripheral side in the radial direction. In FIG. 1 and FIG. 2, a rotor blade 1 is a dovetail 2 that is implanted in a disk of a rotor, a blade portion 3 extending from the dovetail 2, and a blade portion 3.
And an integral shroud 4 covering the upper end of the dovetail 2, the blade 3, and the integral shroud 4 are integrally machined.

A semi-elliptical hole 5 is formed in the circumferential end surface 4a of the integral shroud 4 of the moving blade 1 along the longitudinal direction of the side surface of the integral shroud for inserting a leaf spring.
Further, a hole 5 for inserting a leaf spring is likewise formed in the surface 4b of the integral shroud 4 which faces the circumferential end surface 4a. When the dovetail is inserted in the blade groove to form the annular blade row, the hole 5 is formed into an elliptical integral shroud as shown in FIG. 2 when the opposite surfaces of the shroud face each other so as to contact each other. It functions as one hole along the longitudinal direction of the side surface. FIG. 3 shows an enlarged view of the hole for inserting the leaf spring as seen from the direction of the circumferential end surface 4a. Further, FIG. 2 is a plan view of the blade tips when the adjacent integral shrouds are connected to each other as viewed from the outer peripheral side in the radial direction, and the hole 5 for inserting the leaf spring functions as one hole. A perspective image shows a state in which a leaf spring having an initial deformation is installed therein. 2 and 3
As shown in Fig. 5, the leaf spring connecting hole 5 has an elliptical shape along the longitudinal direction of the side surface of the integral shroud when viewed from the circumferential end surface 4a, and its radial upper and lower end surfaces have a planar shape. In addition, the end surface of the hole 5 in the circumferential direction of the annular blade row is also formed in a planar shape so as to have a large contact area with the leaf spring. By thus increasing the contact area with the leaf spring on the upper and lower end surfaces in the radial direction and the end surfaces in the circumferential direction of the hole 5, a vibration damping effect due to contact friction can be obtained, which effectively acts on vibration damping. In addition, the upper surface in the radial direction, that is, the outer peripheral side surface, causes the inserted leaf spring to be pressed against the outer peripheral side surface due to the centrifugal force that acts when the turbine is rotated, thereby connecting adjacent integral shrouds to each other. The effect is produced and the annular blade stiffness is thereby increased. This is a blade connecting effect and an annular blade row rigidity increasing effect obtained by inserting a plate-shaped member into the hole 5, and the insert is a spring-shaped member having an initial displacement, and the rotor blade is caused by the initial tension. It is different from the coupling effect and the effect of increasing the rigidity of the annular blade cascade.

If the rotor blades 1 are sequentially inserted into the blade grooves provided in the rotor and a force is applied to the rotor blades 1 to form an annular blade row in which the rotor blades are implanted at the theoretical pitch, the initial displacement of the leaf spring causes The elastic initial tension is generated in the leaf spring. This acts as an initial tension between adjacent integral shrouds. Due to this initial tension, when the turbine rotates, even if there is centrifugal force or thermal expansion, the contact between the adjacent blades via the leaf spring of the integral shroud is maintained, which allows the blades to maintain the group blade structure, The rigidity of the entire annular cascade is increased. Further, the vibration is reduced while maintaining the vibration damping effect.

That is, as shown in FIG. 2, opposite sides 4a and 4b of the parallelogram of the integral shroud 4 are opposed to each other.
Are parallel to the opposing side surfaces of the adjacent integral shrouds 4, and the half holes provided on the respective end surfaces face each other to form one hole 5.

On the other hand, the leaf spring 6 inserted into the hole 5 is constantly in contact with the adjacent integral shroud at the intermediate position 8 of the integral shroud 4.

Therefore, a gap is created between the contact surfaces of the adjacent integral shrouds 4 due to centrifugal force or thermal expansion during turbine rotation, and even if the adjacent moving blades do not come into contact with each other, the adjacent springs move through the leaf springs 6. Since the blades are securely connected, the effect of increasing the rigidity of the entire annular blade row and the effect of damping vibration can be obtained.

Further, FIG. 4 shows a general leaf spring, and FIG. 5 shows a leaf spring in a substantially elliptical shape. The upper and lower end surfaces of the leaf spring 6 in the radial direction are formed in the same plane shape as the upper and lower end surfaces of the hole 5 in the radial direction in order to maximize the contact area and the planar shape of the upper and lower end surfaces of the hole 5 in the radial direction. Although the leaf spring used in the present invention is not limited, as shown in FIG. 5, the leaf spring is formed into a substantially elliptical shape, arcuate portions are provided on both sides, and a cutout portion is provided at one place in the center of the straight portion. By providing the above, it is possible to obtain a larger elastic tension for the same deflection with the leaf spring having the same size. That is, FIG.
With a leaf spring with a shape like this, it is easy to maintain contact with the leaf spring when forming the annular blade row because the initial displacement can be large but the tension accompanying it cannot be so large, but the tension is large. Since it does not exist, the increase in rigidity due to that is not large. Further, with a leaf spring that is simply elliptical without a notch, a large amount of tension can be obtained by the semi-arcuate portions provided at both ends, but the deflection of the spring cannot be increased. This means that the holes installed on the opposite side faces of the integral shroud face each other in the annular blade row circumferential gap between the integral shrouds, which is expected to occur when the turbine rotates as a leaf spring to be inserted, forming one hole. When using a larger one in the circumferential direction of the annular blade row than the sum of the depths of the holes when
It means that you have to use a big spring. Further, such a characteristic of the leaf spring which is simply made into a substantially elliptical shape without providing a notch has a characteristic that the blades of the present invention are sequentially inserted into the blade groove and the blades are installed at a predetermined pitch. Large initial tensions can create manufacturing difficulties when forming the annular cascade. However, as shown in FIG. 5, a leaf spring having semi-circular arc portions at both ends and a notch provided at one of the straight portions has a large amount of deflection and tension generated thereby in a well-balanced manner, and the leaf spring itself. The shape of can also be small. By using such a leaf spring, the integral shrouds are connected to each other with a larger tension, so that a larger rigidity increasing effect and vibration damping effect of the turbine annular blade row can be obtained.

Further, as shown in FIG. 5, a protruding portion 7 is provided in the notch portion of the leaf spring so that the protruding portion 7 is in contact with the hole 5 at that portion. When manufacturing the leaf spring, make this part slightly larger by the amount to be shaved, and insert the leaf spring into the elliptical hole that is formed when the opposite faces of the shroud face each other so that they face each other. When the blades are inserted into the blade groove one by one and the rotor blades are installed at a predetermined pitch to form an annular blade row, this portion is ground and the interval between the opposing integral shrouds acts on the leaf spring. The initial tension due to can be adjusted. This is more workable than the method of adjusting the initial tension acting on the leaf spring between the opposing integral shrouds by cutting the end of the leaf spring having the shape shown in FIG.

[0019]

According to the present invention, when a rotor blade is planted in an annular blade groove provided around the rotor to form an annular blade row, on the opposite circumferential side surfaces of the integral shroud,
A semi-elliptical hole is formed so that an elliptical hole along the longitudinal direction of the side surface is formed when the opposite surfaces of the shroud face each other so that they are in contact with each other. Rather than the sum of the depths of holes when the holes installed on the opposite side surfaces of the integral shroud face each other in the circumferential gap of the annular blade row between the integral shrouds to form one hole. By installing a leaf spring with a large circumferential dimension in the annular blade row to form the annular blade row, initial tension is generated in the integral shroud of the adjacent moving blades via the leaf spring, so turbine rotation, centrifugal force Even if thermal expansion occurs, the contact between the integral shrouds of adjacent moving blades is maintained via the leaf springs, and the connection between adjacent moving blades is always maintained. Rotor blade forms a Guntsubasa that make up the,
Rigidity is increased as compared with the case where a single blade is formed without inserting a leaf spring, and damage to the moving blade can be prevented. Further, the contact between the leaf springs makes it possible to obtain the frictional force necessary to maintain the vibration damping effect, so that the vibration of the moving blade during turbine rotation is reduced, and the damage to the moving blade can be prevented. In addition, by making both the outer circumferential end surface of the leaf spring and the end surface of the hole provided in the shroud in contact with the outer circumferential end surface of the leaf spring flat so that the contact area is large, the initial tension of the leaf spring is added and the turbine is rotated. The inserted leaf spring is pressed against the outer peripheral side surface due to the centrifugal force that acts when it is generated, which creates a connecting effect between adjacent integral shrouds, increasing the rigidity of the annular blade row and the vibration damping effect. Obtainable.

Further, in the method of the present invention, in order to maintain the connection between the moving blades, the tension applied to the integral shroud is changed by changing the stagger angle of the moving blades as compared with that obtained by initial twisting of the moving blades. Therefore, it is possible to obtain the rigidity increasing effect and the vibration damping effect of the annular blade row completely independently of the aerodynamic performance of the moving blade.

Further, when the dovetails of the moving blades are sequentially inserted into the annular blade grooves provided around the rotor and the moving blades are installed at a predetermined pitch to form the annular blade row, the process differs from the prior art. The only thing to do is to insert the leaf springs that have undergone initial deformation into the opposite sides of the integral shroud of the adjacent blades, and adjust that also by scraping the edge of the leaf spring or the margin provided on the leaf spring. There is no need to develop new manufacturing technology because it can be done more easily.

[Brief description of drawings]

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

FIG. 2 is a plan view of an embodiment of the rotor blade of the present invention and the tip end portions of the rotor blades arranged adjacent to each other as seen from the outer peripheral side in the radial direction.

FIG. 3 is an explanatory view of holes for inserting leaf springs provided on the circumferential side surface of the integral shroud.

FIG. 4 is a plan view of a general leaf spring.

FIG. 5 is a plan view of a leaf spring deformed into a substantially elliptical shape.

FIG. 6 is a front view of a turbine rotor blade.

FIG. 7 is a plan view seen from the outer peripheral side in the radial direction when the moving blades of FIG. 6 are arranged adjacent to each other.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Moving blade, 2 ... Dovetail, 3 ... Wing part, 4 ... Integral shroud, 5 ... Hole for inserting leaf spring, 6 ... Leaf spring, 7
… Shavings of leaf springs.

Claims (3)

[Claims] 1. A dovetail inserted into an annular blade groove provided around a rotor, a blade portion extending from the dovetail, and a shroud provided at an upper end of the blade portion are integrally machined, In the turbine blade that inserts the dovetail into the blade groove and installs the blades at a predetermined pitch to form an annular blade row, in the facing surfaces of the shrouds of the adjacent blades, in the longitudinal direction of each surface. A semi-elliptical hole extending is provided so that an oval hole is formed when the facing surfaces of the shroud face each other in such a manner that they are in contact with each other. A turbine rotor blade characterized in that the rotor blades are made to connect adjacent rotor blades by exerting tension in a direction. 2. The size of the leaf spring itself according to claim 1, wherein the leaf spring is inserted into the leaf spring which has a curvature at both ends thereof and is provided with a notch at a central portion of a straight line portion so as to have a substantially elliptical shape. A turbine rotor blade that can obtain a large circumferential tension in the annular blade row for a certain amount of deflection without increasing the value. 3. The plate according to claim 1, wherein both the outer peripheral end face of the leaf spring and the end face of the hole provided in the shroud which is in contact with the outer peripheral end face of the leaf spring are made flat to obtain a large contact area. In addition to the initial tension of the spring, a turbine blade that creates the effect of connecting adjacent integral shrouds by pressing the inserted leaf spring against the outer peripheral side surface by the centrifugal force that acts when the turbine is rotated.