JP3962486B2 - Turbine blade rotor mounting structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotor mounting structure for a turbine rotor blade that prevents fretting fatigue generated in a rotor when a rotor blade such as a steam turbine is embedded in a blade groove of the rotor.
[0002]
[Prior art]
In general, a contact-bonded member is subject to fretting fatigue at its moving boundary when slippage due to load fluctuation occurs at the surface pressure acting site, and the rotor blade groove and blade root of a steam turbine, etc. There is also concern about damage due to this fretting fatigue even at the contact joint location.
[0003]
Based on FIG. 4, the contact state of the conventional rotor blade groove and the blade root is shown.
Since the blade root 2 is inserted into the groove portion of the rotor 1 and the shim 3 is driven into and fixed to the bottom of the blade root in this state, the bearing surface 4 where the rotor 1 and the blade 2 are in contact has a high surface. The pressure 6 will act.
[0004]
In this state, the turbine is repeatedly started and stopped, so that a difference in thermal expansion occurs between the rotor 1 and the blade 2 due to the difference in the materials, and accordingly, a relative slip 7 occurs between the two.
[0005]
[Problems to be solved by the invention]
Therefore, in the conventional one as described above, a necessary condition for generating fretting fatigue is satisfied at the boundary portion which becomes the bearing surface 4 described above, and there is a possibility that a crack 5 is generated in the rotor.
[0006]
In order to prevent such fretting fatigue, the surface pressure 6 and the relative slip 7 are reduced, or a crack 5 which is a boundary portion of the bearing surface 4 caused by the surface pressure 6 and the relative slip 7. Therefore, it is necessary to reduce the stress at the location where this occurs.
[0007]
The present invention has been made under such a background, and prevents and suppresses the above-mentioned fretting fatigue and the generation and growth of cracks associated therewith, which have been a concern in the prior art, and maintains a robust structure. It is an object of the present invention to provide a rotor mounting structure for a turbine blade having high safety and high reliability.
[0008]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems, and at the boundary portion of the bearing surface formed by the rotor and the blade root embedded in the rotor, the rotor side is formed in a sparse shape, A distance between an arc of 0.5 to 2 mm in radius contacting the end of the bearing surface and the rotor side surface excluding the clearance, and an interval between the bearing line and an extension line of the bearing surface of 0.2 to 0.2 mm. The present invention provides a rotor mounting structure for a turbine rotor blade formed with a clearance of 0.3 mm.
[0009]
That is, according to the present invention, the rotor side at the bearing surface boundary portion between the rotor and the blade root is configured to have a circular arc with a predetermined radius and a corner shape connected to the circular arc and having a predetermined gap amount. The stress at the boundary is reduced to prevent or suppress fretting fatigue and the accompanying crack growth and growth.
[0011]
Stated more specifically, the present invention bearing surface boundary of the rotor and the rotor blade root, as stealing dimensions of relief shape and its processed into the rotor side, except for the ends and plow of the bearing surface the The radius of the arc contacting the surface on the rotor side is 0.5 to 2 mm, and the fillet shape is connected to the arc and the clearance between the bearing surface and the extension line is specified as 0.2 to 0.3 mm. By doing so, the fretting fatigue in the range divided by this shape and numerical value, and the reliable prevention and suppression of crack generation and growth associated therewith are remarkable.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
Note that the same parts as those of the above-described conventional ones are denoted by the same reference numerals in the drawings, and redundant explanations are omitted, and explanations are made by focusing on points peculiar to the present embodiment. .
[0013]
FIG. 1 shows a steam turbine rotor blade groove portion adopting a thin 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 a result of an experiment using the experimental model of FIG.
[0014]
That is, in the present embodiment, the shape of the rotor 1 side at the boundary portion between the bearing surface 4 of the rotor 1 and the blade 2 is not a conventional planar shape, but a circular arc with a constant radius and a constant interval connected to the arc. A so-called “thickening” process is performed, and a specific thinning dimension of the thinning shape resulting from this processing is as follows: an arc having a radius of 0.5 to 2 mm at the boundary portion of the bearing surface 4 and an interval of 0 By setting the clearance to 2 to 0.3 mm, the stress at the boundary part involved in fretting fatigue is reduced at this position, and crack generation is suppressed.
[0015]
In the present embodiment configured as described above, the fretting fatigue prevention by the thin shape was verified by the experimental model of FIG.
[0016]
That is, as shown in FIG. 2 (a), an outline of the same experimental model, and in FIG. 2 (b), an enlarged view of the main part B, the rotor test piece 11 is sandwiched between the blade test piece 12 and pressed. A surface pressure 16 was applied by applying a force 23.
[0017]
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.
[0018]
As shown in FIG. 3, the test parameters are as follows: test speed: 10 cpm, surface pressure: 40 kgf / mm ² , relative slip: 40 μm, number of tests 10 ⁴ times, and the radius of the arc that determines the thinning shape. A plurality of values such as 0.9 mm, 0.5 mm, 2 mm, etc. are selected, and the crack 15 at the boundary portion of the bearing surface 14 is increased in increments of 0 to 0.1 mm, which corresponds to the amount of clearance for each arc radius, and R The presence or absence and the length of the partial crack 15 ′ were verified.
[0019]
FIG. 3 is a plot of the results obtained when the radius of the arc is 0.9 mm as a representative. According to this plot, there is no so-called thinning with a clearance of 0 mm and a radius of 0 mm, and a clearance of 0. Comparing the case of 2 mm with a radius of 0.9 mm, the crack 15 is about 300 μm compared to the former about 100 μm, and the latter is obviously shorter and the fretting fatigue is shorter in the latter. It can be seen that the thinning process is effective for suppressing cracks.
[0020]
However, if the clearance 19 is increased to 0.4 mm or more, low cycle fatigue is caused, and the crack 15 ′ in the R portion where the machining surface that regulates the clearance 19 is connected to the arc increases. In order to prevent ting fatigue, it is important to set the clearance 19 to about 0.1 to 0.3 mm, preferably 0.2 to 0.3 mm, and the arc radius 18 to 0.5 to 2 mm.
[0021]
In addition, as described above, the explanation is based on the result when the radius of the arc is 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 the same. Showed a trend.
[0022]
As described above, according to the present embodiment, cracking of the bearing surface 4 is prevented by making the shape of the rotor 1 side appropriate thinning at the boundary between the bearing surface 4 of the rotor 1 and the blade 2. It became clear that it can be suppressed.
[0023]
Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention. Absent.
[0024]
【The invention's effect】
As described above, according to the present invention, since the rotor mounting structure of the turbine rotor blade is formed so that the rotor side is thin at the boundary portion of the bearing surface formed by the rotor and the rotor blade blade root embedded in the rotor, , The rotor side at the bearing surface boundary between the rotor and rotor blade root has a circular arc with a predetermined radius and this corner shape connected to the circular arc and spaced by a predetermined clearance to reduce the stress at the boundary and fretting fatigue In addition, it is possible to prevent and suppress the generation and growth of cracks associated therewith, and to obtain a highly safe and reliable rotor rotor blade mounting structure.
[0025]
In particular, according to the present invention, the above-described cut-out shape processed on the rotor side is connected to an arc having a radius of 0.5 to 2 mm contacting the end of the bearing surface and the surface on the rotor side excluding the clearance, and the arc. Since the gap between the bearing surface and the extension line of the bearing surface is specified as a clearance shape and a clearance dimension of 0.2 to 0.3 mm , the bearing surface boundary portion between the rotor and the blade root is outside the specified dimension. As a result, it is possible to reliably prevent and suppress fretting fatigue and the generation and growth of cracks associated therewith, and to obtain a highly safe and reliable rotor blade rotor mounting structure. Was made.
[Brief description of the drawings]
FIG. 1 shows a rotor mounting structure of a turbine rotor blade according to an embodiment of the present invention, (a) is a partial cross-sectional view showing the entire appearance of the blade root part, (b) is an enlarged view of part B of (a), (C) is the C section enlarged view of (b).
FIGS. 2A and 2B show an experimental model for confirming the effect in the present embodiment, in which FIG. 2A is a related configuration diagram of the entire experimental model, and FIG.
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, wherein FIG. 4A is a partial cross-sectional view showing the entire blade root portion, and FIG. 4B is an enlarged view of portion B of FIG.
[Explanation of symbols]
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 Pushing force

Claims (1)

At the boundary of the bearing surface formed by the rotor and the blade blade root embedded in the rotor, the rotor side is formed in a thin shape, and the thin shape is formed on the rotor side excluding the end of the bearing surface and the clearance amount. A turbine motion characterized in that it is formed with a clearance of 0.2 to 0.3 mm between an arc having a radius of 0.5 to 2 mm in contact with the surface and an extension line of the bearing surface connected to the arc. Wing rotor mounting structure.

Images