JP2000034903A - Rotor mounting structure of turbine moving blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent and suppress fretting fatigue and to make a structure with high stability and high reliability by forming the side of a rotor into a theft shape at a boundary part of a bearing surface formed by a rotor and a blade root of a moving blade buried into the rotor. SOLUTION: What is called theft working in which a circular arc of a fixed radius and clearance amount at fixed intervals connected with this circular arc are provided is performed for the shape of the side of a rotor 1 at a boundary part of a bearing surface 4 of the rotor 1 and a blade 2. By making a concrete theft dimension of a theft shape by this theft working as a circular arc of a radius 0.5 to 2 mm and clearance amount of intervals 0.2 to 0.3 mm at a boundary part of the bearing surface 4, stress at the boundary part related to fretting fatigue at this location can be reduced and generation of a crack can be suppressed. Thus, a rotor mounting structure of a turbine moving blade with high safety and high reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor rotor mounting structure for a turbine rotor blade, which prevents fretting fatigue generated in the rotor when the rotor blade of a steam turbine or the like is embedded in a blade groove of the rotor. is there.

[0002]

2. Description of the Related Art In general, when a member which is in contact connection is slipped due to a load variation at a surface pressure acting portion, fretting fatigue is easily generated at a moving boundary portion thereof, and a rotor such as a steam turbine is used. Damage due to the fretting fatigue is also concerned at the contact joint between the blade groove and the blade root.

FIG. 4 shows the state of contact between a conventional rotor blade groove and a rotor blade root. Since the blade 2 has its root inserted into the groove of the rotor 1 and the shim 3 is fixed to the bottom of the blade in that state, the bearing surface 4 where the rotor 1 and the blade 2 come into contact has a high surface. Pressure 6 will act.

[0004] In this state, the turbine repeatedly starts and stops, so that a difference in thermal expansion occurs between the rotor 1 and the blade 2 due to a difference in the respective materials.
Occurs.

[0005]

Therefore, in the above-mentioned conventional device, the above-mentioned necessary condition for fretting fatigue to be generated at the boundary portion which becomes the bearing surface 4 is satisfied, and the crack 5 is formed in the rotor. Can occur.

In order to prevent such fretting fatigue, the surface pressure 6 and the relative slip 7 are reduced, or a boundary between the bearing surface 4 and the bearing 6 caused by the surface pressure 6 and the relative slip 7. It is necessary to reduce the stress at the location where the crack 5 occurs.

The present invention has been made under such a background, and prevents and suppresses the fretting fatigue and the generation and growth of cracks caused by the fretting fatigue, which have been concerned in the prior art. It is an object of the present invention to provide a highly secure and reliable turbine rotor blade rotor mounting structure.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a rotor side at a boundary between bearing surfaces formed by a rotor and a rotor blade root embedded in the rotor. An object of the present invention is to provide a rotor mounting structure for a turbine rotor blade having a slim shape.

That is, according to the present invention, the rotor side at the bearing surface boundary portion between the rotor and the rotor blade root is formed into an arc having a predetermined radius and a slack shape connected to the arc and having a predetermined clearance. With this shape, the stress at the boundary portion is reduced to prevent and suppress the occurrence and growth of fretting fatigue and the accompanying crack.

Further, the present invention provides a rotor mounting structure for a turbine rotor blade, wherein the sneaking shape is formed with an arc having a radius of 0.5 to 2 mm and a clearance of 0.2 to 0.3 mm. .

That is, according to the present invention, the radius of the circular arc is 0.5 at the boundary between the bearing surface of the rotor and the blade of the rotor blade.
２2 mm, with a clearance of 0.2 to 0.3 mm, to prevent fretting fatigue at this position and to reliably prevent and suppress the occurrence and growth of cracks associated therewith. It is.

[0012]

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 and redundant explanations will be omitted, and the description will focus on points unique to the present embodiment. .

FIG. 1 shows a blade groove of a steam turbine rotor employing a slack shape for preventing fretting fatigue according to the present embodiment. FIG. 2 shows an experimental model for verifying the effect of preventing fretting fatigue, and FIG. 3 shows the results of an experiment using the experimental model of FIG.

That is, in the present embodiment, the shape of the rotor 1 side at the boundary between the bearing surface 4 of the rotor 1 and the blade 2 is not a conventional planar shape, but is connected to an arc of a fixed radius and connected to the arc. With a certain amount of clearance,
The so-called squeezing process is performed.
Arc with a radius of 0.5 to 2 mm at the boundary of
By setting the clearance to 0.3 mm, the stress at the boundary portion related to fretting fatigue at this position is reduced, and the occurrence of cracks is suppressed.

The prevention of fretting fatigue due to the slack shape in the present embodiment configured as described above was verified using an experimental model shown in FIG.

That is, as shown in FIG. 2A, an outline of the entire experimental model is shown and FIG. 2B is an enlarged view of a main part B. In this experimental model, the rotor test piece 11 is sandwiched between the wing test pieces 12. Then, a pressing force 23 was applied to apply a surface pressure 16.

In this state, the actuator 22 was moved up and down to give a predetermined relative slip 17 to the bearing surface 14, and a fretting fatigue test was performed.

As shown in FIG. 3, the specifications of the experiment were as follows: test speed: 10 cpm, surface pressure: 40 kgf / m
m ² , relative slip: 40 μm, number of tests 10 ⁴ times,
0.9mm, 0.5m radius of arc to determine the shape
m, 2 mm, etc., and a crack 15 at the boundary of the bearing surface 14 and a crack 1 at the R portion while increasing by 0 to 0.1 mm in increments of 0 to 0.1 mm without any clearance amount for each radius of each arc.
The occurrence of 5 ′ and its length were verified.

FIG. 3 is a representative plot of the results when the radius of the arc is set to 0.9 mm. According to FIG. 3, there is shown a case where there is no so-called sneaking with a clearance of 0 mm and a radius of 0 mm. : 0.2mm, radius: 0.9
Comparing the case with the squeezing process of mm, the crack 15 is about 300 μm in the former and about 100 μm in the latter, and the crack 15 is clearly shorter in the latter, so that the fretting fatigue crack is suppressed. It turns out that the processing is effective.

However, if the clearance 19 is as large as 0.4 mm or more, low cycle fatigue occurs at the same time, and the work surface which regulates the clearance 19 has a crack 15 'at the R portion connected to the arc.
In order to prevent fretting fatigue, the clearance 19 is about 0.1 to 0.3 mm, preferably 0.2 to 0.3 mm.
It is important to set 0.3 mm and the radius 18 of the arc between 0.5 and 2 mm.

As described above, the description has been made based on the result when the radius of the arc is set to 0.9 mm. However, even if the radius of the arc is changed to a plurality of values such as 0.5 mm and 2 mm, the result is not changed. Showed the same tendency.

As described above, according to the present embodiment, at the boundary between the bearing surface 4 of the rotor 1 and the blade 2, the rotor 1
It has been clarified that cracking of the bearing surface 4 can be prevented or suppressed by making the shape of the side appropriate sneaking processing.

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

[0024]

As described above, according to the present invention, the rotor of the turbine rotor blade has a slender rotor side at the boundary of the bearing surface formed by the rotor and the rotor blade root embedded in the rotor. The mounting structure reduces the stress at the boundary by using a circular arc with a predetermined radius on the rotor side at the boundary between the rotor and the blade root and the bearing surface at the boundary between the rotor and the blade. As a result, fretting fatigue and the occurrence and growth of cracks caused by the fretting fatigue were prevented and suppressed, and a highly reliable and highly reliable rotor rotor mounting structure for turbine blades was obtained.

According to the second aspect of the present invention, the slack shape machined on the rotor side is an arc with a radius of 0.5 to 2 mm and a slack size with a clearance of 0.2 to 0.3 mm. The rotor mounting structure of the turbine rotor blade with the above features ensures fretting fatigue at the boundary between the bearing surface of the rotor and the rotor blade root and the reliable prevention and suppression of crack generation and growth associated with it. As a result, a highly reliable and highly reliable rotor mounting structure for the turbine blade can be obtained.

[Brief description of the drawings]

1A and 1B show a rotor mounting structure of a turbine rotor blade according to an embodiment of the present invention, in which FIG. 1A is a partial cross-sectional view showing the entire view of a blade root portion, FIG. (C) is an enlarged view of a portion C in (b).

FIGS. 2A and 2B show an experimental model for confirming the effect of the present embodiment, and FIG.
(B) is an enlarged view of a B portion of (a).

FIG. 3 is an explanatory diagram showing an experimental result based on the experimental model of FIG. 2;

4A and 4B show a conventional rotor mounting structure of a turbine rotor blade, in which FIG. 4A is a partial cross-sectional view showing the entire blade root portion, and FIG. 4B is an enlarged view of a portion B in FIG.

[Explanation of symbols]

 Reference Signs List 1 rotor 2 blade 3 shim 4 bearing surface 5 crack 6 surface pressure 7 relative slip 8 radius 9 clearance 11 rotor test piece 12 blade test piece 14 bearing surface 15 crack 16 surface pressure 17 relative slip 18 radius 19 clearance 21 load cell 22 Actuator 23 Pressing force

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Keiichiro Miyajima 2-1-1 Shinhama, Arai-machi, Takasago-shi, Hyogo F-term in Takasago Works, Mitsubishi Heavy Industries, Ltd. 3G002 FA03 FB00 FB01

Claims (2)

[Claims] 1. A rotor mounting structure for a turbine rotor blade, wherein a rotor side has a slack shape at a boundary between a bearing surface formed by a rotor and a rotor blade root embedded in the rotor. 2. The sneaking shape has a radius of 0.5 to 2 mm.
The rotor mounting structure for a turbine rotor blade according to claim 1, wherein the arc is formed with a clearance of 0.2 to 0.3 mm.