JPH106010A - Steam turbine rotor assembling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an assembling method capable of stable welding without any entrapment of slag and adherence of molten metal in joining between each rotor part. SOLUTION: A rotor 6 is formed in the vertical direction by stacking plural rotor part with a narrow gap between each rotor, and the joining part is joined using a TIG welding with a welding torches 4a and 4b while rotating the rotor 6 after arranging the welding torch 4a and 4b to the joining part between the rotor part provided with the narrow gap. Whereby, the assembling method, capable of obtaining the excellent bead face and forming the high quality of joined part at a high efficiency, is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for assembling a steam turbine rotor.

[0002]

2. Description of the Related Art In assembling a steam turbine rotor for thermal or nuclear power, as shown in FIG. 2, the disk is divided into a plurality of parts and the divided parts are joined by welding to form a rotor 6.

[0003] As a conventional welding method for joining the divided parts in assembling the rotor, a submerged arc welding method is adopted. An electrode wire is fed into a powdery or granular flux which has been sprayed on a base material in advance. The automatic arc welding was performed continuously by igniting an arc between the tip and the base material.

[0004] The feature of this welding is that a welding current is supplied to the wire immediately before the arc, so that a large current welding can be performed, the efficiency is very high, and a weld surface with a deep penetration and a stable welding can be obtained. It is.

However, there are the following disadvantages. That is, since the arc is not visible because it is wrapped in the flux, welding cannot be performed while checking whether welding is appropriate. Due to the deep penetration, various properties of the weld metal are greatly affected by the composition of the base metal and the like. Alternatively, in the case of a steel type in which the precision of groove processing is severe, in the case of high current welding, the performance of the heat-affected zone is deteriorated.

[0006]

As mentioned above, submerged arc welding has its advantages as well as its disadvantages. In the main parts of a steam turbine such as a rotor, the disadvantages of submerged arc welding are adversely affected. Is more important.

[0007] In the assembly of a rotor to which the conventional submerged arc welding method is applied, slag is involved during welding, or welding metal adheres due to short-circuit from the tip of the torch to the base material wall. However, small and stable welding was difficult. The present invention seeks to solve the above problems.

[0008]

According to a first aspect of the present invention, there is provided a method of assembling a steam turbine rotor in which a rotor portion formed by dividing an axial direction into a plurality of portions is joined to form an integral rotor. The plurality of rotor portions are stacked vertically with a narrow gap therebetween to form a rotor in the vertical direction, and a welding torch is disposed in the narrow gap between the rotor portions. Then, the welding is performed while rotating the rotor. An arc is generated from a torch to perform tungsten inert gas welding (hereinafter referred to as TIG welding).

In the present invention, the respective rotor portions are joined by TIG welding. In the TIG welding, an arc is generated between the tungsten electrode and the base material in an inert gas atmosphere to thereby form the base material. In addition, the arc forms a stable bell-shaped soft arc over a wide current range to create a quiet weld pool, and the torch operation is simple and current adjustment is easy. Things.

[0010] Therefore, even in the case of a rotor using a material sensitive to oxidation and nitriding, a high-quality welded joint can be obtained, a smooth bead surface can be formed, and good welding can be performed even in a horizontal position. It is possible.

Further, since the joint between the rotor portions is welded as a narrow gap, the TIG having low heat input concentration and low thermal efficiency is used.
Despite the use of a welding method, highly efficient joining is possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for assembling a steam turbine rotor according to one embodiment of the present invention will be described with reference to FIG.

In the assembling method according to the present embodiment shown in FIG. 1, the rotor 6 is vertically formed by stacking disks as rotor portions with a narrow gap therebetween.
After a plurality of (only two are shown in FIG. 1) welding torches 4a and 4b are disposed in one narrow gap between the disks, the rotor 6 is rotated with its center axis as a rotation axis. An arc is generated between the welding torches 4a, 4b and the rotor 6 while performing TIG welding.

The TIG welding apparatus used in the assembling method according to the present embodiment includes a welding head 8a integrated with a welding torch 4a and a manipulator 5 on which a wire feeder 9a is mounted, as shown in FIG. Welders 1a, 1b connected to torches 4a, 4b, respectively, and cooling water circulating devices 2a, 2
b, are formed by operation panels 3a and 3b connected to the welding machines 1a and 1b, respectively, and provided with remote control push buttons 7a and 7b.

In the above, when joining the disks of the rotor 6 while rotating the rotor 6, a plurality of welding torches 4 a, which simultaneously generate an arc with the rotor 6.
4b is moved by the manipulator 5 in the radial direction of the rotor section, and the welding torches 4a and 4b
Perform IG welding.

The TIG welding method is a method in which an arc is generated between a tungsten electrode and a base material in an atmosphere of an inert gas such as argon or helium to weld-weld a weld metal. Therefore, it does not require a flux, and is suitable for welding a material sensitive to oxidation and nitriding such as high alloy steel such as a rotor material, and a high quality welded portion can be obtained.

The arc is a bell-shaped stable soft arc over a wide range of current, and a quiet weld pool is formed, so that a smooth bead surface can be obtained. ) Because it is easy to adjust,
It can be welded in all positions.

However, it is not suitable for high-speed and high-efficiency welding due to the low concentration of heat input and low thermal efficiency. For this reason, in the present embodiment, the groove shape is narrowed, and the welding torches 4a, 4
The welding is performed by using a plurality of b at the same time, thereby enabling welding with high working efficiency.

As a result, since there is no slag entrapment, which is a feature of TIG welding, and there is no occurrence of adhesion of a weld metal, it is possible to realize a weld joint having no defects and high construction efficiency.

[0020]

According to the method of assembling a steam turbine rotor of the present invention, a plurality of rotor portions are stacked vertically with a narrow gap therebetween to form a rotor in the vertical direction. After arranging the welding torch to the joint, the joint is joined by TIG welding using the welding torch while rotating the rotor, whereby a good bead surface can be obtained, An assembly method capable of forming a high-quality joint with high efficiency is realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a TIG welding device according to one embodiment of the present invention.

FIG. 2 is a sectional view of a steam turbine rotor.

[Explanation of symbols]

 1a, 1b Welding machine 4a, 4b Welding torch 5 Manipulator 6 Rotor

Claims (1)

[Claims] 1. A method for assembling a steam turbine rotor in which rotor parts formed by dividing an axial direction into a plurality of parts are joined to form an integral rotor, wherein the plurality of rotor parts are formed with a narrow gap therebetween. Forming a rotor in the vertical direction by stacking, and arranging a welding torch in a narrow gap between the rotor portions, and then performing tungsten inert gas welding by generating an arc from the welding torch while rotating the rotor. A method for assembling a steam turbine rotor.