Turbine blade and cooling hole working method therefor

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention particularly relates to a turbine blade having a cooling hole with improved cooling efficiency and a method for processing the cooling hole.

【0002】

[Conventional technology]

Heat-resistant alloys have been conventionally used for high-temperature members such as turbine blades, combustors, and shroud segments of gas turbines because they are kept at the combustion gas temperature of gas turbines.

【0003】

Further, in order to prevent the temperature of these high temperature members from rising, a technique for cooling the high temperature members by using cooling air having a temperature lower than the combustion gas temperature has been developed. Examples of these cooling techniques include convection cooling, impingement cooling, film cooling and transpilation cooling.

【0004】

Among these, in film cooling, a large number of film cooling holes are provided on the surface of the base material in order to cool the temperature of the surface of the base material. Then, cooling air is blown out from these cooling holes to the wall surface of the turbine blade or the like, and the cooling air forms a film-like cooling air layer on the surface of the turbine blade to protect the base material from the high temperature gas flow.

【0005】

Conventionally, electric discharge machining has been applied to the production of film cooling holes.

【0006】

In electric discharge machining, a mold electrode having the same shape as the cooling hole to be finally produced is produced to produce a cooling hole. For this reason, electric discharge machining has the advantage that cooling holes of any shape can be manufactured with high accuracy, but the cost is high because a mold electrode is manufactured for each cooling hole. In addition, there was a problem that it took time and effort for processing.

【0007】

Therefore, in recent years, by adopting laser machining using a YAG laser having a high pulse shape or the like, the cost in cooling hole machining has been reduced and the production efficiency of film cooling hole fabrication has been improved.

【0008】

For example, as described in Japanese Patent Application Laid-Open No. 9-144504, laser machining is applied to the formation of cooling holes.

【0009】

FIG. 7 is a diagram showing an example of a cooling hole processing method for a gas turbine stationary blade.

【0010】

As shown in FIG. 7, the base material of the gas turbine vane 1 is provided with a large number of film cooling holes 2.

【0011】

In these film cooling holes 2, the laser light 3 oscillated from a YAG laser oscillator (not shown) is focused by the condenser lens 4, and the focused laser light is applied to the gas turbine stationary blade 1 to irradiate the gas turbine. It is formed through the base material of the stationary blade 1.

【0012】

[Problems to be Solved by the Invention]

However, although the cooling holes are produced by the above-mentioned laser light, which has an advantage that the cost can be reduced as compared with the electric discharge machining, the shape of the cooling holes is limited, so that a sufficient cooling effect cannot be obtained. Had the problem.

【0013】

FIG. 8 is a diagram showing a cross-sectional shape of the cooling hole by laser processing.

【0014】

As shown in FIG. 8A, the cooling air flows from the inside (upstream side) of the gas turbine vane 1 to the outside (downstream side) as shown by arrow A. However, in the cooling hole 2 produced by the laser, there is a range in which the cooling hole 2 is not sufficiently cooled in the vicinity 5 on the downstream side of the outlet, and therefore a sufficient cooling effect cannot be obtained.

【0015】

Further, in order to cool the area near the downstream side of the cooling hole 2 outlet 5 that is not sufficiently cooled, Japanese Patent Application Laid-Open No. 9-144504 expands the downstream side of the cooling hole outlet as shown in FIG. 8 (b). The diameter cooling hole 6 is machined. However, even in this case, a sufficient cooling effect could not be obtained yet.

【0016】

In this way, when the gas temperature used in the cooling holes 2 and 6 shown in FIGS. 8 (a) and 8 (b) becomes higher, the turbine blades will rise due to the rise in the substrate temperature during operation. There was a problem that it could be damaged.

【0017】

The present invention has been made to solve such a problem, and provides a gas turbine blade having improved cooling efficiency and a cooling hole processing method thereof while efficiently forming cooling holes to reduce costs. The purpose is to do.

【0018】

[Means for solving problems]

The invention according to claim 1 is a method for forming a plurality of cooling holes for blowing cooling gas onto a base material of a turbine blade by laser processing, wherein the base material is irradiated with laser light to have a small diameter. After the piercing step of forming the cooling hole of the above, the optical axis of the laser beam is inclined with respect to the central axis of the small diameter hole to form a diffusion-shaped cooling hole whose diameter is gradually increased toward the surface of the base material. A diffusion-shaped hole forming step is performed, and then a straight-shaped hole forming step is performed in which the optical axis of the laser beam is circularly moved around the central axis of the small-diameter hole to form a straight-shaped cooling hole having the same diameter. It is characterized by that.

【0019】

According to the present invention, by using laser machining, it is possible to efficiently machine a cooling hole whose diameter is gradually expanded toward the surface of the base material. Therefore, a gas turbine blade having improved cost reduction and cooling efficiency can be obtained. Obtainable.

【0020】

In the invention according to claim 2, in the cooling hole processing method for turbine blades according to claim 1, in the piercing step and the straight shape hole forming step, the focal position of the laser beam is set on the surface of the base material on the cooling air outlet side. The diffusion shape hole forming step is characterized in that the focal position of the laser beam is set on the inner surface of the base material on the cooling air inlet side.

【0021】

According to the third aspect of the present invention, in the cooling hole processing method for turbine blades according to the first or second aspect, the inclination angle of the optical axis of the laser beam with respect to the base material is set to 2 ° to 30 °, and an oval opening is formed. It is characterized by forming a diffusion-shaped hole having a portion.

【0022】

In the present invention, the base material of the turbine blade can be efficiently cooled by forming a diffusion-shaped hole having an oval-shaped opening (a rectangular shape in which both short sides are semicircular (race track shape)). .. Further, the opening of the cooling hole is not limited to an oval shape, and the cooling performance can be changed at any time by changing the shape of the opening of the cooling hole depending on the location of the turbine blade provided with the cooling hole. ..

【0023】

The angle of inclination of the optical axis of the laser beam with respect to the base material depends on the plate thickness, but when the plate thickness is 1 to 2 mm, the angle of inclination of the optical axis of the laser light with respect to the base material is 3 °. The range of ~ 7 ° is preferable.

【0024】

The invention according to claim 4 sets the inclination angle of the optical axis of the laser beam with respect to the base material to 5 ° to 25 ° in the cooling hole processing method for the turbine blade according to claim 1 or 2, and the laser beam. It is characterized in that the optical axis of the above is swirled by 1 ° to 45 ° to form a diffusion-shaped hole having a fan-shaped opening.

【0025】

In the present invention, the cooling area of the base material can be improved by forming a diffusion-shaped hole having a fan-shaped opening. It is more preferable that the angle of inclination of the optical axis of the laser beam with respect to the substrate is 10 ° to 15 °, and the optical axis of the laser beam is 15 ° to 25 °.

【0026】

The invention according to claim 5 is the method for machining a cooling hole of a turbine blade according to any one of claims 1 to 4, wherein the straight-shaped hole is laser-machined and the diffusion-shaped hole is electric-discharge-machined to machine the cooling hole. Alternatively, both the straight-shaped hole and the diffusion-shaped hole are subjected to electric discharge machining to machine a cooling hole.

【0027】

According to laser processing, the shape processability of the cooling hole is good, and the cost can be reduced. On the other hand, electric discharge machining is more excellent in workability and can produce a highly accurate shape, but on the other hand, it has a drawback that the cost is high. Therefore, a desired turbine blade can be obtained by using either laser machining or electric discharge machining in consideration of these various conditions.

【0028】

According to the invention of claim 6, in the method for machining a cooling hole of a turbine blade according to claim 5, the electric discharge machining electrode is composed of a Cu flat plate electrode having a plate thickness of 0.05 to 5.0 mm, and the Cu flat plate electrode is manufactured. It is a saw-shaped electrode having a mold shape of a diffusion-shaped hole.

【0029】

According to the present invention, since the electric discharge machine electrode is made of a thin flat plate electrode, it can be easily manufactured and the cost can be reduced. Further, since the electric discharge machining electrode has a saw-shaped shape, the cooling hole can be efficiently machined.

【0030】

The invention according to claim 7 is characterized in that, in the method for machining a cooling hole of a turbine blade according to claim 5 or 6, the electric discharge machining electrode is circularly moved along the shape of a diffusion-shaped hole to perform electric discharge machining.

【0031】

The turbine blade according to claim 8 is arranged inside the base material of the turbine blade, has a straight-shaped hole having the same diameter, is arranged outside the base material of the turbine blade, and is gradually expanded toward the surface of the base material. It is characterized by having a cooling hole composed of a diffusion-shaped hole.

【0032】

The turbine blade according to claim 9 is manufactured by the cooling hole processing method for the turbine blade according to claims 1 to 7.

【0033】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6.

【0034】

First Embodiment (Figs. 1 to 3) In the present embodiment, a laser beam is used to form an air outlet of the gas turbine stationary blade, that is, a gas turbine stationary blade having an oval shape (a rectangular shape in which both short sides are semicircular (race track shape)). A cooling hole having an opening was made. Further, this cooling hole is composed of a straight-shaped cooling hole and a diffusion-shaped cooling hole.

【0035】

A Ni- or Co-based superalloy was used as the base material for the gas turbine blade, and the plate thickness of the gas turbine blade surface was in the range of 1.0 mm to 5.0 mm. In addition, a YAG laser was adopted as the laser.

【0036】

FIG. 1 is a diagram showing a method of processing cooling holes in a gas turbine stationary blade.

【0037】

As shown in FIG. 1A, the base material 10 of the gas turbine stationary blade was irradiated with the laser beam 12 focused by the condenser lens 11. At this time, the angle Θ between the stationary blade surface of the gas turbine and the central axis of the cooling hole was set in the range of 15 ° to 45 °.

【0038】

The procedure for drilling cooling holes with a laser will be described below.

【0039】

First, a process called piercing, in which holes were made as small as possible, was applied to the base material 10 of the gas turbine stationary blade. The piercing diameter φ was set in the range of 0.1 to 0.2 mm, and other conditions for piercing formation were shown in Table 1.

【0040】

[table 1]

<img file="JP2000141069A_D0001.tif" />【0041】

As shown in Table 1, the piercing conditions are such that the pulse width of the laser beam is 0.1 to 2.0 ms, the laser energy is 5 to 20 J / pulse, and N is used as the drilling gas.₂Gas, Ar gas, O₂Using gas or air, gas pressure is 2 ~ 10kgf / cm₂And said. Then, the laser beam 12 was not moved, and the focal position of the laser beam 12 was set to the surface of the base material 10 of the gas turbine stationary blade.

【0042】

Then, the number of shots was set so that the irradiation was stopped when the laser beam 12 penetrated. The piercing formation differs depending on the plate thickness of the base material 10, but in the present embodiment, the piercing is completed in a few shots.

【0043】

Next, a diffusion-shaped cooling hole was formed.

【0044】

The angle of incidence Θ of the laser beam 12 on the base material 10 was not changed as the angle of incidence Θ at the time of piercing formation, and the focal position of the laser beam 12 was set on the inner surface of the gas turbine stationary blade. Then, as shown in FIG. 1 (b), the laser beam 12 was moved from (L) to (M) by inclining the angle δ in the range of 1 ° to 30 ° around the focal position. .. Then, after passing through (L) to (M), the laser beam 12 was similarly moved from (M) to (N). As shown in Table 1, the hole processing conditions when forming the cooling hole of the diffusion shape are as shown in Table 1, the pulse width of the laser beam is 0.1 to 2.0 ms, the pulse duty is 5 to 50 Hz, the laser energy is 5 to 20 J / pulse, and the hole is drilled. The speed was set to 1 ° to 10 ° / sec. Also, as a gas for drilling, N₂Gas, Ar gas, O₂Using gas or air, gas pressure is 2 ~ 10kgf / cm²And said.

【0045】

And finally, a straight-shaped cooling hole was formed.

【0046】

First, the focal position of the laser beam 12 set on the inner surface of the gas turbine stationary blade was returned to the focal position at the time of piercing formation, that is, the focal position of the laser beam 12 was returned to the surface of the base material 10 of the gas turbine stationary blade. After that, a circular shape was drawn while moving the laser beam 12, and a straight-shaped cooling hole was formed. As shown in Table 1, the hole processing conditions when forming a straight-shaped cooling hole are 0.1 to 2.0 ms for the pulse width of the laser beam, 5 to 50 Hz for the pulse duty, 5 to 20 J / pulse for the laser energy, and drilling. The speed was set to 1 to 50 mm / min (depending on the plate thickness). Also, as a gas for drilling, N₂Gas, Ar gas, O₂Using gas or air, gas pressure is 2 ~ 10kgf / cm²And said.

【0047】

Figure 2 shows the cooling holes of the gas turbine vane produced by such a procedure.

【0048】

FIG. 2 is a diagram showing cooling holes seen from the upper surface of the base material of the gas turbine stationary blade.

【0049】

As shown in FIG. 2, the cooling hole on the upstream side, that is, the inner surface side of the gas turbine vane, which is the air inlet of the cooling hole 13, is a cylindrical shape, that is, a straight shape cooling hole (hereinafter referred to as straight shape hole). The diameter φ of the straight-shaped hole 14 was 14, and the diameter φ was in the range of 0.2 to 6.0 mm. The diameter of the straight-shaped hole 14 is expanded from substantially the center of the gas turbine stationary blade base material to form a diffusion-shaped cooling hole (hereinafter, referred to as diffusion-shaped hole) 15. Then, an oval-shaped opening (a rectangular shape in which both short sides are semicircular (race track shape)) is provided on the downstream side, which is the outlet of the cooling air, that is, on the surface of the base material of the gas turbine stationary blade. The diameter of the cooling hole 13 is expanded from the upstream side to the downstream side.

【0050】

FIG. 3 is a comparative diagram showing the cooling area on the surface of the gas turbine vane due to the difference in the shape of the cooling holes.

【0051】

As shown in FIG. 3A, the outlet shape of the conventional cooling hole 16 is a circular opening, and the region 17 through which the cooling air flows from the upstream side to the downstream side, that is, the cooling area is increased so much. Not. On the other hand, in the present embodiment, the outlet shape of the cooling hole 13 is an oval opening, and the region 18 through which the cooling air flows from the upstream side to the downstream side, that is, the cooling area is the conventional cooling hole 16. It has increased dramatically in comparison.

【0052】

From this, as shown in FIG. 3 (b), in the past, only a part of the downstream side of the cooling hole 16 was cooled, and the cooling effect was not so excellent. However, according to the present embodiment, the cooling effect is not so excellent. Since the outlet shape of the cooling hole 13 is oval, the cooling area is widened, and the cooling performance of the gas turbine stationary blade base material can be dramatically improved.

【0053】

According to the present embodiment, the base material 10 can be efficiently cooled by arranging the cooling holes 13 in the base material 10 of the gas turbine stationary blade by narrowing the distance between the cooling holes 13. Therefore, even when the exposed gas temperature is high, the base material 10 is sufficiently cooled, so that the deterioration of the base material 10 can be promoted and the high temperature strength during operation can be maintained.

【0054】

Further, by forming the straight-shaped hole 14 at the end in the processing of the cooling hole 13, the molten layer remaining on the inner surface of the cooling hole 13 can be minimized in the formation of the piercing and diffusion-shaped holes 15.

【0055】

Further, according to the present embodiment, when the diffusion-shaped hole 15 is formed, the focal position is moved to the inner surface of the gas turbine stationary blade base material, so that the change in the minimum hole diameter of the base material 10 is suppressed and the cooling hole 13 is formed. The damage of the base material 10 on the inner surface can be reduced. Although not used in this embodiment, a protective material can be inserted into the base material 10 of the gas turbine stationary blade in order to suppress damage to the inner surface of the blade of the laser beam 12.

【0056】

Second Embodiment (Fig. 4, Fig. 5) In the present embodiment, a cooling hole having a fan-shaped opening is formed in the gas turbine vane.

【0057】

FIG. 4 is a diagram showing a method of processing a cooling hole having a fan-shaped opening. Since FIG. 4 (a) has almost the same configuration as FIG. 1 (a) in the first embodiment, the same reference numerals are used for the same parts.

【0058】

As shown in FIG. 4A, the base material 10 of the gas turbine stationary blade was irradiated with the laser beam 12 focused by the condenser lens 11. At this time, the angle η between the stationary blade surface of the gas turbine and the central axis of the cooling hole was set in the range of 5 ° to 25 °.

【0059】

Further, the method of forming the cooling hole may be the same as that of the cooling hole having the oval opening in the first embodiment. After piercing, the diffusion-shaped hole 15 is formed, and finally the straight-shaped hole 14 is formed. Formed. As for the hole drilling conditions, the same hole drilling conditions as in Table 1 of the first embodiment were used.

【0060】

In this embodiment, as shown in FIG. 4B, the hole diameter φ of the straight-shaped hole 14 is 0.2 to 6.0 mm, and the fan-shaped angle δ is in the range of 1 ° to 45 °.

【0061】

In this way, a fan-shaped cooling hole 19 having a fan-shaped opening was obtained in the gas turbine stationary blade.

【0062】

FIG. 5 is a diagram comparing the temperature of the base material on the surface of the gas turbine vane due to the difference in the shape of the cooling holes.

【0063】

FIG. 5 (a) is a cross-sectional view showing the conventional cooling hole 16, and FIG. 5 (b) is a cross-sectional view showing the fan-shaped cooling hole 19 in the present embodiment.

【0064】

Further, FIG. 5 (c) shows a relationship diagram between the base material position of the cooling air and the base material temperature for the conventional cooling holes 16 and the fan-shaped cooling holes 19 .

【0065】

As shown in FIG. 5A, in the conventional cooling hole 16, the diameter of the cooling hole 16 does not change, so that the cooling air in the vicinity of the outlet of the cooling hole 16 is separated from the base material 10 of the gas turbine stationary blade. As shown in 5 (c), the temperature of the base material 10 was likely to rise. On the other hand, according to the fan-shaped cooling hole 19 of the present embodiment, as shown in FIG. 5B, the cooling hole 19 on the surface of the gas turbine stationary blade is expanded in diameter from substantially the center of the base material 10. The cooling air in the vicinity of the outlet of the cooling hole 19 does not separate from the gas turbine stationary blade base material 10. Therefore, as shown in FIG. 5C, the temperature of the base material 10 does not rise so much, and the temperature rise of the gas turbine stationary blade base material 10 can be effectively suppressed.

【0066】

Therefore, according to the present embodiment, by providing the cooling hole 19 having the fan-shaped opening, the cooling area where the cooling air comes into contact with the gas turbine stationary blade base material 10 is expanded, and the gas turbine stationary blade base material 10 has a cooling area. Cooling performance can be improved.

【0067】

Other embodiments (Fig. 6) In the present embodiment, it will be described that the cooling holes are produced by electric discharge machining to improve the efficiency of electric discharge machining.

【0068】

In the present embodiment, as in the first embodiment, a cooling hole having an oval opening is formed in the gas turbine vane.

【0069】

FIG. 6A is a diagram showing a saw-shaped electrode for electric discharge machining.

【0070】

As shown in FIG. 6A, the thickness of the saw-shaped Cu electrode 22 was 0.05 to 5.0 mm. The plate thickness needs to be changed depending on the shape of the cooling hole. Further, the angle Θ of the tip of the saw blade portion can be determined by the diffusion shape of the cooling hole to be produced.

【0071】

Such a saw-shaped electrode 22 is placed on a gas turbine stationary blade base material (not shown), the saw-shaped electrode 22 is moved in the vertical direction, and the saw-shaped electrode 22 is indicated by the arrow B shown in FIG. 6 (a). It was moved while rotating in the direction. As a result, the cooling hole 23 shown in FIG. 6 (b) can be produced by giving a curvature to the portion C shown in FIG. 6 (b) and using the saw-shaped electrode 22 as a template on the gas turbine stationary blade base material. it can.

【0072】

FIG. 6B is a diagram showing cooling holes seen from the upper surface of the base material of the gas turbine stationary blade. As shown in FIG. 6B, the cooling hole on the upstream side, that is, the inner surface side of the gas turbine vane, which is the air inlet of the cooling hole 23, has a cylindrical shape, that is, a straight shape hole 24, and the straight shape hole 24 Is expanded from almost the center of the gas turbine stationary blade base material to form a diffusion-shaped hole 25. A cooling hole 23 having an oval (race track shape) opening is provided on the downstream side, which is the outlet of the cooling air, that is, on the surface of the base material of the gas turbine stationary blade, from the upstream side to the downstream side. The diameter of the cooling hole 23 is expanded toward the direction.

【0073】

According to the present embodiment, when the diffusion shape is formed by electric discharge machining, the machining time is longer than that of machining using laser light, but the diffusion shape hole 25 can be formed with high accuracy. Although the saw-shaped electrode 22 is manufactured in the present embodiment, cooling holes may be formed by using a large number of electrodes having a straight shape.

【0074】

Further, in the present embodiment, the method of drilling the cooling holes of the gas turbine blade has been mainly described, but the same method can be applied to other high temperature parts.

【0075】

[Effect of the invention]

As described above, according to the turbine blade cooling hole processing method according to the present invention, cooling holes are efficiently formed to reduce costs, and the base material of turbine blades exposed to high temperature gas is efficiently cooled. By doing so, deterioration of the base material of the turbine blade can be prevented and the life can be extended.

【0076】

[Simple invention of drawings]

【0077】

[Figure 1]

The figure which shows the processing method of the cooling hole in the gas turbine stationary blade in 1st Embodiment of this invention.

【0078】

[Figure 2]

The figure which shows the cooling hole seen from the upper surface of the base material of the gas turbine stationary blade in 1st Embodiment of this invention.

【0079】

[Fig. 3]

The figure which shows the comparison of the cooling hole shape and the area where the cooling air flows to the downstream side on the blade surface in 1st Embodiment of this invention.

【0080】

[Fig. 4]

The figure which shows the processing method of the cooling hole which has a fan-shaped opening in 2nd Embodiment of this invention.

【0081】

[Fig. 5]

(a) is a cross-sectional view showing the conventional cooling hole 16, and (b) is a cross-sectional view showing a fan-shaped cooling hole, and is a comparative view showing the base material temperature on the surface of the gas turbine stationary blade due to the difference in the shape of the cooling hole.

【0082】

[Fig. 6]

(a) is a diagram showing a saw-shaped electrode for electric discharge machining, and (b) is a diagram showing a cooling hole seen from the upper surface of a base material of a gas turbine stationary blade.

【0083】

[Fig. 7]

A blade cross-sectional view illustrating a conventional laser drilling method.

【0084】

[Fig. 8]

Explanatory drawing which shows the conventional laser hole drilling method.

【0085】

[Explanation of symbols]

10 Gas turbine stationary blade base material 11 Condensing lens 12 Laser light 13 Cooling holes 14 Straight hole 15 Diffusion shape hole 16 Conventional cooling holes 17 Area where cooling air flows 18 Area where cooling air flows 19 Fan-shaped cooling hole 20 Near the outlet of cooling hole 16 21 Near the exit of cooling hole 19 22 Saw-shaped electrode 23 Cooling holes 24 Straight hole 25 Diffusion shape hole