JP2001073706A - Repair method of turbine rotor blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable repair processing in spite of pre-twist and minimize mismatch due to accumulation of tolelance. SOLUTION: The turbine rotor blade 10 is formed with platform 12 at bottom of wing 11 and tip shroud 13 at top, so that, when tips of fin 13B, 13C get worn from use with turbine engine, the turbine 10 can be re-formed to proper shape given machining process for repair by fixing it with jigs making use of datum (X1, Y1, Y2, Z1, Z2, Z3) set by tip shroud 13, after build up welding said parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing a tip blade of a rotor of an axial flow turbine having a tip shroud portion at an outer end thereof.

[0002]

2. Description of the Related Art As shown in FIG. 3, which is a partial cross-sectional view of a relevant portion, a plurality of turbine blades 10 are implanted on an outer peripheral surface of a turbine disk. In the figure, reference numeral 30 denotes a stationary blade.

The turbine blade 10 'is formed by precision casting of a material such as a Ni-based alloy. As shown in FIG. 4, a platform 12 is provided at a lower end of a three-dimensional blade 11 and a tip shroud 13 is provided at an upper end. Provision, platform 12
Is fixed to the turbine disk 20 by a dovetail 12A protruding from the lower side.

[0004] By the way, not only such turbine blades, but also when machining only a required part of a part having a complicated shape formed by casting to obtain a product (finished product), the part is stably provided. A plurality of reference points (datums) that can be held are set, and using these datums, positioning and fixing are performed by a jig and machining is performed. The datum is usually set dispersed throughout the part.

In the illustrated turbine rotor blade 10 ', a total of six datums, D, are set at four points on the platform, one point on the blade part, and one point on the tip shroud, as shown in the figure, and the platform 12 and the tip shroud are set. 13, both sides,
Fins 13B, 13 erected on tip shroud 13
The upper edge of C is machined.

Here, the turbine blade is twisted (pre-twisted) at a predetermined angle about the Z-axis from the mounting shape (shape at mounting) on the turbine disk, and corrects the twist. By elastically deforming in the direction and attaching the turbine shroud to the turbine disk, both side surfaces of the tip shroud of the adjacent turbine blade are closely positioned and fixed to the turbine disk.

A jig used for machining a turbine blade having a pretwist as described above is naturally manufactured based on a free state including a twist amount of the pretwist.

[0008]

By the way, when a turbine rotor blade having a pretwist as described above is mounted on a turbine engine and used for use, it undergoes plastic deformation due to creep in order to heat up in a stressed state. As a result, the twist amount of the pre-twist decreases.

For this reason, when a problem such as wear occurs in the used turbine blade and repair is required, there arises a problem that machining cannot be performed using a jig newly manufactured. That is, the fins 13B erected on the chip shroud 13,
When wear occurs at the tip of 13C, as shown in FIG. 5, which is an enlarged view of the portion X in FIG. Since the twist amount of the twist is different, the jig at the time of new manufacture cannot be used.

[0010] In order to enable machining using a jig at the time of new manufacture, twisting must be performed so that the amount of twist is equal to that at the time of new manufacture. There are many elements that are unsuitable for twisting such as structure and surface coating, and such processing has been extremely difficult.

Further, even when the amount of twist of the pre-twist is correct, if the datum is set to be dispersed throughout the turbine blade, the positional tolerance of the surface to be repaired with respect to the datum and the processing tolerance due to machining will be different. As a result, there is a mismatch that needs to be corrected because it causes stress concentration at the boundary between the existing casting surface and the repaired surface, as shown in FIG. There was a fear.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to perform repair processing irrespective of a change in pre-twist and reduce a mismatch caused by accumulation of tolerances. The purpose is to provide a repair method.

[0013]

According to the present invention, there is provided a method for repairing a turbine rotor blade according to the present invention, wherein a datum is set in the tip shroud part in a rotor blade of an axial flow turbine having a tip shroud part at an outer end. The fin of the tip shroud is repaired with reference to the datum.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a front view of a turbine blade to be repaired by using the turbine blade repair method according to the present invention, and FIG. 2 is an enlarged view of a tip shroud portion thereof, and FIG. ) Is a front view.

The illustrated turbine blade 10 has a platform 12 at the lower end of a blade 11 and a tip shroud 13 at the upper end.
Is formed.

The chip shroud 13 has two fins 13B and 13C standing up and down on the upper surface of a substantially flat base 13A.

A dovetail 12A protrudes below the platform 12, and the turbine blade 10 is fixed to a turbine disk (not shown) by the dovetail 12A.

In FIG. 1, the direction orthogonal to the plane of the paper is the X axis,
In the figure, the left-right direction orthogonal to the axis is the Y axis, and the extending direction of the wing 11 orthogonal to the X axis and the Y axis is the Z axis.

The fins 13 of the tip shroud 13 are mounted on a turbine engine and used.
When wear occurs at the tips of B and 13C, after overlay welding is performed on the portions, datums (X1, Y1, Y2, Z) set on the tip shroud 13 as shown in FIG.
(1, Z2, Z3), the turbine blade 10 is positioned and fixed by a jig, and is machined for repair to be formed into a regular shape.

The datum has one point (X1) on the side edge of one fin 13B defining the X-axis direction, and two points (, Y1, D1) defining the Y-axis direction on one side of the fin 13B. Y2), three datums (Z1, Z2, Z3) defining the Z-axis direction are set on the lower surface of the chip shroud.

The tip shroud 13 has very little influence of the pre-twist, and the datums (X1, Y1, Y2, Z1, Z2,
By performing machining using Z3), highly accurate machining can be performed regardless of whether the pretwist returns due to use. In other words, it is possible to repair a turbine rotor blade which is mounted on a turbine engine and used for use and undergoes plastic deformation to reduce the amount of twist of the pre-twist.

Further, a datum (X
1, Y1, Y2, Z1, Z2, Z3), the tolerance of the position of the surface to be repaired with respect to the datum and the machining tolerance due to machining are small, and the existing casting surface which causes stress concentration and repair is repaired. The mismatch at the boundary with the processing surface can be reduced.

Incidentally, the setting position of the datum is not limited to the above configuration example, but can be changed as appropriate in the vicinity of the chip shroud 13.

[0025]

As described above, according to the turbine blade repair method of the present invention, the datum is set in the tip shroud portion, and the fin of the tip shroud portion is repaired based on the datum. Repair work with high precision is possible even for turbine blades that are mounted on a turbine engine and used for use, and undergo plastic deformation to reduce the amount of twist of the pretwist.

Further, the positional tolerance of the surface to be repaired with respect to the datum and the processing tolerance due to machining are less accumulated, and the mismatch of the boundary between the existing casting surface and the repaired surface, which causes stress concentration, can be reduced.

That is, repair processing can be performed irrespective of changes in pre-twist, and mismatch due to accumulation of tolerances can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a turbine rotor blade which is repaired by using the turbine blade repair method according to the present invention.

FIGS. 2A and 2B are enlarged views of a tip shroud portion, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is a partial sectional view of a rotor blade stage in the axial flow turbine.

FIG. 4 is a front view of a turbine rotor blade.

FIG. 5 is an enlarged view of a part X in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Turbine rotor blade 13 Chip shroud (tip shroud part) 13B, 13C Fin X1, Y1, Y2, Z1, Z2, Z3 Datum

Continued on the front page (72) Inventor Eiji Sakai 3-5-1 Mukodai-cho, Tanashi-shi, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. Tanashi Factory (72) Inventor Masanobu Baba 3-5-1 Mukodai-cho, Tanashi-shi, Tokyo No.Ishikawa Shima-Harima Heavy Industries, Ltd.

Claims (1)

[Claims] 1. A blade of an axial flow turbine having a tip shroud portion at an outer end, wherein a datum is set in the tip shroud portion, and fins of the tip shroud portion are repaired based on the datum. Repair method for turbine blades.