JPH04356379A - Stationary blade ring for steam turbine utilizing electron beam welding - Google Patents

Abstract

PURPOSE:To prevent voids generated on the electron beam tip of base metals to be subjected to electron beam welding from overlapping each other. CONSTITUTION:Since insertion type stagger parts 9 are provided on the central part of the base metals to be subjected to electron beam welding and electron beams are emitted along welding seams 7a, respectively from both upper and lower surfaces of an outer ring 1 and a spacer ring 5 which are base metals, the voids 8 are prevented from overlapping each other and a stationary blade ring with increased strength of welded zones 7 can be manufactured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a stator vane ring for a steam turbine produced by electron beam welding.

0002

2. Description of the Related Art FIG. 2 is a perspective view of a stator vane ring of a steam turbine. Conventionally, in a stator vane ring, a nozzle piece 3 is attached between an outer ring 1 and an inner ring 2 which are divided into two parts. Figure 3
is a perspective view of the main part of a hand-welded stator vane ring, and (A
) shows a nozzle piece, and FIG. 3(B) shows a state in which the nozzle piece of FIG. 3(A) is welded to an outer ring and an inner ring. The nozzle piece 3 is integrally formed with fitting parts 3a and 3b having protrusions. Fitting portions 3a, 3 of nozzle piece 3
b was inserted into the groove of the outer ring 1 and the groove of the inner ring 2, and the end face of the fitting part 3a and the outer ring 1, and the end face of the fitting part 3b and the inner ring 2 were manually welded. 4 indicates a hand welded part. In this example, thermal stress is generated in the fitted portions 3a, 3b during welding, so the wall thickness of the fitted portions 3a, 3b had to be increased.

[0003] There is also a stator blade ring for a steam turbine made by electron beam welding. The depth that the electron beam penetrates into the solid metal is proportional to the accelerating voltage. Therefore, no surface melting occurs as long as the material remains in a molten state. Electron beam welding, which is actually used, utilizes deep penetration. When the power density of the beam is high and a narrow, deep hole is formed in the molten pool, the area around this hole is heated and melted by the energy of the beam dispersed from the beam axis, so it is used as a heat source, unlike arc welding. , a wire heat source that is inserted perpendicularly into the material. Electron beam welding has the following characteristics. a) Microbeam diameter The diameter of an electron beam can be narrowed down to a very small diameter electromagnetically or electrostatically. b) Localized high-temperature heating Electron beams can be narrowed down to an extremely small spot, and electrons can be heated extremely quickly in a vacuum, making it possible to apply heating energy with extremely high power density to minute parts of the workpiece. be. c) Penetrability into the interior of the material When an electron beam is viewed as a tool, the electrons penetrate into the interior of the solid, giving machining energy to the interior of the material. d) High-speed controllability Since electrons have a small mass and a large charge capacity, it is extremely easy to control them electrically or magnetically at high speed. e) Chemical cleanliness The electron beam is purely electrical energy. Combined with the cleanliness of operating in a vacuum, the electron beam enables chemically clean welding work. f) Wide range of powers and power densities The power of the electron beam can be increased up to 100 times or more using the same equipment.
The beam current can be varied simply by changing the accelerating voltage or both.

FIG. 4 is a perspective view of a main part of a stator vane ring of a steam turbine made by conventional electron beam welding, in which (A) of FIG. 4 shows a nozzle piece, and (B) of FIG. This shows the nozzle piece welded to the outer ring and inner ring. While processing the nozzle piece 3, a nozzle piece attachment hole 6 is provided in the two spacer rings 5 on the outer diameter side and the inner diameter side by laser machining, and the nozzle piece 3 is attached to the nozzle piece attachment hole 6. The spacer ring 5 to which the nozzle piece 3 is attached in this way is fitted onto the outer ring 1 and the inner ring 2, and the end faces of the outer ring 1 and the spacer ring 5 are electron beam welded. 7 shows a welded part by electron beam welding.

FIG. 5 is a sectional view of a welded part of a stator vane ring by conventional electron beam welding. In FIG. 5, the outer ring 1 and the spacer ring 5 are brought into contact with each other so that the weld seam 7a is in a straight line, and an electron beam is applied from the upper and lower surfaces to form a welded part 7 by the electron beam.

[0006] Electron beam equipment is limited in beam energy and continuous time due to the strength of the hardware, and when electron beam welding of thick parts of plates, it is difficult to penetrate the plate from only one side with the beam, and A method was adopted in which beams were struck from both sides of the board to a depth of half the depth. If the beam is applied from both sides of the plate in this manner, voids 8 will accumulate in the center of the plate thickness, reducing the strength of the welded portion 7. Therefore, countermeasures were required to increase the strength.

It is an object of the present invention to provide a stationary blade ring for a steam turbine by electron beam welding, in which the strength of the welded part is increased by preventing voids generated at the tip of the electron beam of a base material to be electron beam welded to overlap. With the goal.

[0008]

[Means for solving the problem] In a stator vane ring for a steam turbine in which a nozzle piece is electron beam welded between an outer ring and an inner ring via a spacer ring, the nozzle piece is fitted into the center part of the base material to be electron beam welded. The above object is achieved by providing a staggered part and performing welding by driving an electron beam along the welding seam from both sides of the base material.

In the stator vane ring of a steam turbine made by electron beam welding according to claim 1, by electron beam welding the outer ring and the spacer ring and the inner ring and the spacer ring, the strength of the stator vane ring can be increased and suitable.

Furthermore, in the stationary blade ring of a steam turbine by electron beam welding according to claim 1, if the electron beam is driven from both sides of the base material to be welded by the electron beam to the depths from the center of the base material, voids can be eliminated. It is preferable to place it on top so that it does not overlap.

[0011]

[Operation] This invention provides an inset staggered part in the center of the base material to be welded with an electron beam, and the electron beam is driven from both sides of the base material along the welding seam of the base material, so the tip of the electron beam Since the voids that occur in the welds are different from each other and do not overlap, the strength of the welded part can be increased.

[0012] If the outer ring and spacer ring are electron beam welded, and the inner ring and spacer ring are also electron beam welded, the heat generated by the electron beam will be generated locally, so that the base metal will not be distorted by the heat. Because it does not occur,
The spacer ring can be made thinner.

Furthermore, if the electron beam is applied from both sides of the base material to be welded to the depths beyond the center of the base material, the electron beam will be applied along the welding seam to the fit-in staggered part in the center of the base material. Since a welded portion is formed, the strength of the welded portion can be increased.

[0014]

[Embodiment] A stator vane ring according to an embodiment of the present invention is shown in FIG.
Similarly to (A) and (B), the nozzle piece 3 is machined, and the nozzle piece mounting holes 6 are formed in the two spacer rings 5 on the outer diameter side and the inner diameter side by laser processing, and the nozzle piece mounting holes are Attach nozzle piece 3 to 6. Nozzle piece 3
Insert the spacer rings 5, 5 with attached spacer rings 5, 5 between the outer ring 1 and the inner ring 2.

FIG. 1 is a sectional view of a welded portion of a stator vane ring according to an embodiment of the present invention. In FIG. 1, the same parts as in FIG. 5 are given the same reference numerals. In FIG. 1, outer ring 1
and spacer ring 5 are electron beam welded, and
A fitted staggered portion 9 is provided in the center of both base materials, and when an electron beam is driven along each welding seam 7a from both the upper and lower surfaces of the base materials, the welded portion is heated locally by the electron beam and the welded portion is heated. 7, and the outer ring 1 and the spacer ring 5 are welded. Similarly, the inner ring 2 and the spacer ring 5 are electron beam welded. The voids 9 generated at the tip of the electron beam become misaligned, and the voids 9 do not overlap.

Note that the outer ring 1 and the spacer ring 5
If the electron beam is driven from the upper and lower surfaces of the base metal to the depths of the center of the base metal along the weld seam 7a of formed and increases the strength of the weld.

[0017]

[Effects of the Invention] According to the present invention, an inset staggered portion is provided in the center of the base material to be electron beam welded, and the electron beam is driven along the welding seam of the base material from both sides of the base material. Because the weld seams are staggered, the voids formed at the tip of the electron beam do not overlap. therefore,
Stator vane rings with increased strength at welded parts can be manufactured. Moreover, the telescoping staggers can support the pressure of the steam flowing through the vane ring.

If the electron beam is driven from both sides of the base material to be welded by the electron beam to the depths beyond the center of the base material, electron beam welding can be performed completely along the welding seam to the center of the base material. This makes it possible to manufacture a stator vane ring with increased strength at the welded part.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a welded portion of a stator vane ring according to an embodiment of the invention.

FIG. 2 is a perspective view of a stator vane ring of a steam turbine.

FIG. 3 is a perspective view of the main parts of a conventional hand-welded stationary vane ring, in which (A) shows a nozzle piece, and (B) shows a state in which the nozzle piece in (A) is welded to an outer ring and an inner ring. .

FIG. 4 is a perspective view of a main part of a stator vane ring made by conventional electron beam welding, in which (A) shows a nozzle piece, and (B) shows a state in which the nozzle piece in (A) is welded to an outer ring and an inner ring. show.

FIG. 5 is a sectional view of a welded portion of a stator vane ring by conventional electron beam welding.

[Explanation of symbols]

1 Outer ring 2 Inner ring 3 Nozzle piece 5 Spacer ring 6 Nozzle piece mounting hole 7 Welded part 7a　Weld seam 8 Void 9 Inset type discrepancy part

Claims (3)

[Claims] Claim 1: In a stator vane ring for a steam turbine in which a nozzle piece is electron beam welded between an outer ring and an inner ring via a spacer ring, there is an inset type discrepancy in the center of the base material to be electron beam welded. 1. A stator vane ring for a steam turbine by electron beam welding, characterized in that the ring is welded by driving an electron beam along the weld seam from both sides of the base metal. 2. A stator vane ring for a steam turbine by electron beam welding according to claim 1, wherein the outer ring and the spacer ring and the inner ring and the spacer ring are welded by electron beam. stationary wing ring. 3. The stationary blade ring of a steam turbine by electron beam welding according to claim 1, wherein the electron beam is driven from both sides of the base material to be welded by the electron beam to the depth from the center of the base material. Steam turbine stator blade ring made by beam welding.