JP2000018002A - Moving blade for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress each vibration in the axial direction and a circumferential direction of moving blades so as to improve vibration resistant strength by forming a shroud arranged on moving blade top parts of a steam turbine in a shape fitted mutually by restricting movement of the axial direction and the circumferential direction at an end surface adjacent to a circumferential direction of a turbine rotor. SOLUTION: A shroud 3 which extends in a circumferential direction enclosing a turbine rotor 1 and which is arranged extending over tip parts of a plurality of moving blades 2, is fitted to tenons 4 protruded on a top part of each moving blade 2, a plurality of moving blades 2 are integratedly formed so as to constitute a blade group. In the shroud 3, an end surface 3b mutually faced to the other shroud 3 adjacent in a circumferential direction is mutually formed in a saw tooth shape, the crest and trough of the saw tooth, and an edge line between them are brought into contact with each other, and are fitted mutually. The shrouds 3 are brought into contact with each other at an end surface 3b having a part extending in an axial direction and a circumferential direction, and movement of the shrouds 3 are restricted so as to suppress each vibration in the axial direction and the circumferential direction of each moving blade 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving blade of an axial rotating machine such as a steam turbine.

[0002]

2. Description of the Related Art A schematic structure of a moving blade of a steam turbine will be described with reference to FIG.

FIG. 2 shows a typical configuration of a first stage of a steam turbine, in which a large number of nozzles 12 are embedded in a partition plate 11 fixed to a vehicle cabin 14 in a circumferential direction.
A packing ring 13 is arranged at the inner peripheral end of the base 1 to form a stationary vane.

Next, a plurality of moving blades 2 are arranged downstream of the stationary blades. The moving blades 2 are embedded in the turbine rotor 1 side by side in a circumferential direction. A shroud 3 is arranged in the space, and a plurality of blades 2 adjacent to each other in the circumferential direction are bound by the shroud 3.

FIG. 3 shows a related structure between the rotor blade 2 and the shroud 3. A plurality of rotor blades 2 having blade roots embedded in the turbine rotor 1 by a Christmas tree structure or the like (not shown) have respective radii. The tenon 4 is caulked to the shroud 3 at the leading end in the direction, is divided into a plurality of pieces in the circumferential direction, and constitutes a plurality of blade groups each having an integrated structure.

[0006]

In the conventional rotor blade group configuration as described above, the circumferential end faces of the shrouds 3 forming adjacent blade groups are indicated by reference numeral 3a in FIG. In this case, the shroud 3 is not completely effective in damping the turbine in the circumferential direction and the axial direction, and the shroud 3 has a vibration-proof strength due to the strength of the moving blade 2 itself.

However, since the moving blade 2 is not originally integral with the turbine rotor, but is integrated by fitting an uneven portion called a Christmas tree structure or the like as described above, The vibration resistance of the wing 2 itself was naturally limited.

SUMMARY OF THE INVENTION The present invention solves such a problem in the prior art, and proposes a moving blade of a steam turbine having improved vibration proof strength by devising a connection and joining form between shrouds constituting a moving blade group. The task is to provide.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a shroud provided at the top of a moving blade of a steam turbine is provided at an end face which is adjacent to a turbine rotor in a circumferential direction. An object of the present invention is to provide a moving blade of a steam turbine having a shape in which the movement in the axial direction and the circumferential direction is restricted and fitted to each other.

That is, according to the present invention, the end faces of the shrouds of the rotor blade apexes that are circumferentially adjacent to each other are shaped so as to fit together while restricting both axial and circumferential movement. The present invention is designed to suppress the vibration in the axial direction and the vibration in the circumferential direction of the turbine.

The present invention also provides a steam turbine bucket in which the end face of the shroud has a serrated shape.

In other words, according to the present invention, the end faces of the shrouds at the tops of the blades adjacent in the circumferential direction are formed in a saw-tooth shape and are fitted to each other. Alternatively, the axial and circumferential reaction forces at the portion having the shape from the valley to the peak suppress vibration in the axial direction and in the circumferential direction of the turbine.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. Note that the same parts as those of the above-described conventional one are denoted by the same reference numerals in the drawings, and redundant description will be omitted as much as possible, and the points unique to the present embodiment will be mainly described.

A shroud 3 extending in the circumferential direction around the turbine rotor 1 and disposed over the tops of the plurality of moving blades 2 is fitted to a tenon 4 protruding from the top of each moving blade 2. And shrunk 3 by caulking Tenon 4
By integrating the blades, a plurality of blades 2 are spelled out to form an integrated blade group.

Here, the shroud 3 is formed so that the end faces 3b facing each other with the other shroud 3 adjacent in the circumferential direction are formed in a sawtooth shape, and the peaks and valleys of the sawtooth, and the valley-to-valley or the valley-to-peak. The leading ridges are in contact with each other and fitted.

As described above, the shroud 3 installed on the top of the moving blade 2 in the present embodiment has a saw-tooth shape on both end surfaces 3b, and the shaft is formed at the shroud 3 portion of the adjacent moving blade 2. The end face 3b having a portion extending in the direction and in the circumferential direction can be in contact with each other. Therefore, the axial and circumferential movement is regulated by the saw-tooth-shaped contact fitting, and the Vibration and circumferential vibration are damped.

The gap C between the end faces of the shroud 3 configured to be in contact with each other and fitted as described above is not finished to a state where the shroud 3 is completely contacted and fitted in the manufacturing stage, but is not completed during operation. It is manufactured in consideration of the thermal expansion of each part so that this gap becomes zero.

As described above, according to the present embodiment, among the end faces of the shroud, the end face extending in the axial direction or having a large amount of the axial extension component has a vibration damping effect on the circumferential blade vibration. The end face that extends in the circumferential direction or has a large amount of circumferentially extending components has a vibration damping effect against the moving blade vibration in the axial direction, thereby obtaining a moving blade of the turbine with improved vibration resistance.

Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to these embodiments.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0020]

As described above, according to the present invention, the shroud provided at the top of the moving blade of the steam turbine moves axially and circumferentially at the circumferentially adjacent end face of the turbine rotor. Since the blades of the steam turbine are configured so as to have a shape that is regulated and fitted to each other, the axial end surface has a vibration damping effect on the circumferential blade vibration and the circumferential end surface. Has a damping effect on the rotor blade vibrations in the axial direction, and together, it is possible to obtain turbine blades with enhanced vibration resistance, and to obtain highly safe and reliable turbine blades. Was made.

According to the second aspect of the present invention, the blade of the steam turbine is configured such that the fitting shape of the end face of the shroud is serrated, so that the shape is defined by the serrated shape. The end face having a large amount of axial extension component and the end face having a large amount of circumferential extension component respectively have a vibration damping effect against circumferential blade vibration and axial blade vibration,
The combination of the two makes it possible to obtain a turbine rotor blade with improved vibration resistance, and to obtain a highly reliable and highly reliable turbine rotor blade.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a main part of a rotor blade of a turbine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a general arrangement relationship between a moving blade and a stationary blade of a turbine.

FIG. 3 is an explanatory diagram that emphasizes a part A of FIG. 2 and schematically illustrates a main part of a rotor blade of a conventional turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine rotor 2 Moving blade 3 Shroud 4 Tenon 11 Partition plate 12 Nozzle 13 Packing ring 14 Cabin

Claims (2)

[Claims] 1. A shroud provided at the top of a rotor blade of a steam turbine has a shape in which axial and circumferential movements are restricted by circumferentially adjacent end faces of a turbine rotor so as to fit each other. A blade of a steam turbine characterized by the above. 2. The moving blade of a steam turbine according to claim 1, wherein a fitting shape of an end face of the shroud is saw-toothed.