JPH11257010A - Axial-flow turbine moving blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability in terms of strength of the entire inset portion without decreasing the turbine stage performance. SOLUTION: The outer periphery of a rotor disk 1 is formed with a convex hook extending circumferentially. The hook is engaged with the inset portion of each blade which is arranged circumferentially to hold it. Also, the inset portion of a stop blade 6 is attached to a radial notch formed to the rotor disk 1. A key 9 is inserted overstriding both inset portions of the stop blade 6 and an adjacent blade 7 so as to prevent the stop blade 6 from coming out. Furthermore, the stop blade 6 and a blade 21 located at a symmetric position with the above stop blade relative to a rotational axis 20 of the turbine are made of a material having a small specific gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade of an axial flow turbine such as a steam turbine or a gas turbine, and more particularly, to a key spanning a stud blade and an implant of an adjacent blade adjacent to the stop blade. The present invention relates to a blade of an axial flow turbine in which a stop blade is engaged with a rotor disk by insertion.

[0002]

2. Description of the Related Art Generally, in a rotor blade of an axial flow turbine such as a steam turbine, a number of blades are arranged in a circumferential direction on an outer periphery of a rotor disk, and are rotationally driven by a high-temperature and high-pressure fluid flowing between the blades. It is to be done.

[0003] As a method of disposing a large number of wings, a so-called dovetail structure is usually used.
The blades are sequentially incorporated by bringing the blades into contact with the outer peripheral surface of the rotor disk and sliding in the circumferential direction from the insertion position where a part of the hook provided in the circumferential direction is removed. At the insertion position where a part of the hook is removed, a stop wing or a stop member is provided to eliminate a circumferential gap between many wings and insert a key between adjacent wings. However, the stopper blade or the stopper member is prevented from coming off due to the centrifugal force.

FIG. 5 is an exploded perspective view showing an attached state of a blade 2 to a rotor disk 1 of a turbine, and a plurality of circumferentially extending hooks 3 are provided on both sides of an outer peripheral portion of the rotor disk 1. Are formed, and the wing 2
The groove formed in the implanted portion 2a is fitted and engaged with the hook 3 of the rotor disk 1.

By the way, in the above-mentioned moving blade, at least one radially extending notch 5 is provided on the outer peripheral portion of the rotor disk 1, and the blade 2 is implanted from the notch 5. The assembly is performed by inserting the portion 2a in the radial direction of the rotor disk, engaging the groove formed in the implant portion 2a with the hook 3, and sequentially moving the blade in the circumferential direction. The notch 5 assembled at the end of one stage of the wing is provided with a retaining wing 6 or a stopper.

Since the stop blade 6 is located in the notch 5 of the rotor disk 1 as described above, the stop blade 6 comes off the rotor disk during rotation.
Therefore, as shown in FIG. 6, a key groove 8 parallel to the axis of the rotor is formed in each of the implanted portions 6a, 7a of the retaining blade 6 and the adjacent blade 7 adjacent thereto, and is formed by the key grooves 8. The key 9 is inserted in the hole. A key 9 is similarly inserted between the adjacent wing 7 and the adjacent wing 10 that is further adjacent to the adjacent wing 7. Therefore, the stop wing 6
Is supported by the adjacent blades 7 and 10 via the key 9 to prevent the stopper blade 6 from coming off. Normally, it is considered that the key 9 alone is sufficient to fix the retaining wing 6.
Stop pins 12 are inserted into 1a and 11b so that the lift of the stop blades 6 due to centrifugal force is completely prevented.

[0007]

However, in such a case, the centrifugal force applied to the stop blade is applied to the adjacent wing 7 via the key 9, and therefore the upper side of the key 9 of the implanted portion 7 a of the adjacent wing 7. However, there is a problem that a shear stress is generated which is not generated by the normal blade, and the strength becomes stricter than other blades.

[0008] Therefore, as shown in FIG. 7, it has been proposed to use a stopper 13 from which the effective portion of the wing is removed in place of the above-mentioned wing.

However, in the case where the stopper 13 from which the wing effective portion of the stopper wing is removed is used as described above, since there is no effective wing portion at that portion, it becomes a passage for steam, and a paragraph of the paragraph using the stopper is used. There is a problem that the performance is reduced, and that there is no effective portion of the wing, so that a snubber wing having a high vibration damping capacity and a whole group spelling structure cannot be applied. Further, there is a problem that the weight balance of the entire paragraph is lost because a part of the wings is lightened.

In view of the above, the present invention provides an axial flow turbine blade capable of improving the strength reliability of the entire implanted portion without deteriorating the stage performance of the turbine. Aim.

[0011]

According to a first aspect of the present invention, the implanted portions of the respective blades arranged in the circumferential direction are fitted and held on circumferentially extending convex hooks formed on the outer peripheral portion of the rotor disk. At the same time, the implanted portion of the stop blade is attached to the radial cutout formed in the rotor disk, and a key is inserted across both the implanted portions of the stop blade and the adjacent blade adjacent to the stop blade. In the axial turbine rotor blade configured to prevent the stop blade from coming off, the stop blade and the blade located at a position symmetrical to the stop blade with respect to the turbine rotation axis are formed of a material having a low specific gravity. And

According to a second aspect of the present invention, the implanted portions of the respective blades arranged in the circumferential direction are fitted and held on circumferentially extending convex hooks formed on the outer peripheral portion of the rotor disk. Attachment portions of the stop blades are attached to the radial cutouts formed on the rotor disk, and a key is inserted across both the implant portions of the stop blades and the adjacent blades adjacent to the stop blades. In the axial flow turbine rotor blade which is prevented from coming off, the contact position between the key and the key groove into which the key is inserted is formed so as to be closer to the inner circumferential direction of the turbine than the key or the center of the key groove. It is characterized by having done.

Further, the third invention is characterized in that the position of the key and the key groove into which the key is inserted are located in the turbine inner circumferential direction from the center position of the solid thickness.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing an embodiment of the first invention, in which a stop blade 6 is formed of a metal material having a specific gravity lighter than that of a normal blade such as a titanium alloy. Axis 20
The blades 21 symmetrical with respect to the blade 21 are also made of a metal material having a low specific gravity, such as a titanium alloy, like the stopper blade 6. Other points are the same as those shown in FIG. 5 and FIG.

However, in this case, since the stop blade 6 has a blade effective portion like a normal blade, the stage performance of the turbine is not reduced, and the stop blade 6 is formed of a relatively lightweight material. Therefore, the centrifugal force applied to the implanted portion of the stop blade 6 and the key 9 and the rotor disk side implanted portion and the centrifugal force applied to the adjacent blade 7 via the key 9 are reduced. For this reason, the stress generated in the implanted portions of the retaining wing 6 and the adjacent wing 7 and the implanted portion on the rotor disk side is reduced, and the structural strength reliability of the portions is improved.

Further, since the wing 21 located at a position symmetrical with the stop blade 6 and the turbine rotating shaft 20 is formed of the same lightweight metal as the stop blade 6, the stop blade 6 and the blade at a position symmetrical to the stop blade 6 are formed. Since the centrifugal force of the centrifugal force 21 is reduced in proportion to the ratio of the specific gravity of the wing material to each other, the balance of the centrifugal force is almost balanced. Conventionally, when adjusting the weight balance, notches are provided on the inner surface side of the solid part of the implanted part of the wing to adjust the weight, but depending on the amount of weight adjustment, the solid part of multiple wings must be cut off And it takes time and effort. On the other hand, in the present invention, since the stop blade 6 and the blade 21 at the symmetrical position are lighter than each other, the trouble of balance adjustment can be omitted or reduced.

In the above embodiment, the stop blades 6 and the like are formed of a lightweight alloy such as a titanium alloy. However, the stop blades 6 and the blades 21 symmetrically located with the stop blades 6 are made of a lightweight material such as FRP. It may be formed of a relatively lightweight material such as a composite material or fiber reinforced ceramics. Thus, also in this case, the same effects as those of the above embodiment can be obtained.

FIGS. 2 and 3 are views showing the second invention, in which holes formed by key grooves formed on opposing surfaces of the implanted portions 6a, 7a of the retaining wing 6 and the adjacent wing 7 are shown. 22 is formed in a substantially triangular shape in which the radially outer portion of the rotor blade is a vertex. Similarly, a key 23 to be inserted into the hole 22 has a substantially triangular cross section corresponding to the hole 22. is there.

By the way, when the retaining blade 6 is radially pulled by the centrifugal force, a shear stress is generated in the key 23 itself. In the cross-sectional shape of the key shown in FIG. 2, the cross-sectional area and position of the portion a that bears the shear stress of the key 23 itself are shown in FIG.
Is the same as the conventional key 9, but the contact position between the key groove forming the hole 22 and the key 23 moves in the turbine inner circumferential direction from the center of the hole 22 and the key 23,
The cross-sectional area of the portion b that bears the shear stress above the key 23 of the adjacent wing 7 increases. Therefore, the key 2 of the adjacent wing 7
The shear stress in the portion above 3 is reduced, and the structural strength reliability of the portion can be improved.

FIG. 4 is a view showing an embodiment of the third invention, in which the positions of the key grooves 8 provided in the implanted portions 6a, 7a of the stop wing 6 and the adjacent wing 7 correspond to the solid thickness L. From the center of the turbine in the inner circumferential direction of the turbine.

Therefore, the cross-sectional area of the portion b that bears the shear stress in the solid portion above the key of the adjacent wing 7 in FIG. 4 is increased, and the shear stress in that portion can be reduced.
Structural strength reliability can be improved.

[0022]

As described above, the present invention is configured as described above, so that the stress generated in the stop wing and the adjacent wing can be reduced.
Structural strength reliability can be improved. In addition, the use of a stopper does not prevent a decrease in paragraph performance, so if the wing located at a position symmetrical to the stop wing is made of a lightweight material like the stop wing, the paragraph weight balance can be adjusted very easily. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an axial turbine blade showing an embodiment of a first invention.

FIG. 2 is a partial view of an axial flow turbine blade showing a schematic configuration of a second invention.

FIG. 3 is an enlarged view of a key part of FIG. 2;

FIG. 4 is a diagram showing an embodiment of the third invention.

FIG. 5 is an exploded, partial view of a conventional axial turbine blade.

FIG. 6 is a partial front view of a conventional axial turbine blade.

FIG. 7 is a partial front view showing another example of the conventional axial turbine blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor disk 2 Blade 2a Implanted part 3 Hook 5 Notch 6 Stopper 6a Implanted part 7 Adjacent wing 7a Implanted part 8 Keyway 9 Key 11a, 11b Pin hole 12 Stop pin 13 Stopper 20 Turbine rotating shaft 21 Wings located symmetrically with the stop wings 22 holes 23 keys

Claims (5)

[Claims] The present invention is characterized in that the implants of the respective blades arranged in the circumferential direction are fitted and held on circumferentially extending convex hooks formed on the outer peripheral portion of the rotor disk, and formed on the rotor disk. Attachment portion of the stop blade is installed in the radial cutout portion, and a key is inserted across both the implant portions of the stop blade and the adjacent blade adjacent to the stop blade to prevent the stop blade from coming off. An axial flow turbine rotor as described above, wherein the stop blade and the blade at a position symmetrical to the stop blade with respect to the turbine rotation axis are formed of a material having a low specific gravity. 2. The axial turbine blade according to claim 1, wherein the material having a low specific gravity is a titanium alloy. 3. The axial turbine blade according to claim 1, wherein the material having a low specific gravity is a lightweight composite material or a fiber reinforced ceramic. 4. The method according to claim 1, wherein the wings arranged in the circumferential direction are fitted to and held by circumferentially extending convex hooks formed on the outer circumferential portion of the rotor disk. Attachment portion of the stop blade is installed in the radial cutout portion, and a key is inserted across both the implant portions of the stop blade and the adjacent blade adjacent to the stop blade to prevent the stop blade from coming off. In the axial flow turbine rotor configured as above, the contact position between the key and the key groove into which the key is inserted,
An axial flow turbine rotor blade formed so as to be located on the inner circumferential side of the turbine from the center of a key or a key groove. 5. The method according to claim 5, wherein the wings arranged in the circumferential direction are fitted to and held by circumferentially extending ridge hooks formed on the outer circumferential portion of the rotor disk, and formed on the rotor disk. Attachment portion of the stop blade is installed in the radial cutout portion, and a key is inserted across both the implant portions of the stop blade and the adjacent blade adjacent to the stop blade to prevent the stop blade from coming off. In the axial flow turbine rotor configured as above, the position of the key and the key groove into which the key is inserted is located in the turbine inner circumferential direction from the center position of the solid thickness. .