JP3754555B2 - Method and apparatus for detecting flaws on the surface and inside of the leading edge of a turbine blade - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a turbine blade flaw detection method and a flaw detection device, and more particularly, to a flaw detection method and a flaw detection device suitable for flaw detection on the surface and inside of a turbine blade leading edge for thermal power generation.
[0002]
[Prior art]
Since turbine blades for power generation are used at high temperatures, regular inspections have conventionally been performed for the purpose of confirming their soundness.
[0003]
In this periodic inspection, the penetrant flaw detection method is mainly employed, but this penetrant flaw detection method has a disadvantage that only surface flaw detection can be performed.
[0004]
In particular, a turbine blade, particularly a turbine blade for thermal power generation, has a cooling hole formed in the inside from the blade root portion to the tip portion. In the penetrant flaw detection method, the cooling hole formed inside the blade leading edge portion is formed. There is a problem that the entire surface and the vicinity of the peripheral wall cannot be detected.
[0005]
[Problems to be solved by the invention]
On the other hand, there is an ultrasonic flaw detection method as a flaw detection method inside the turbine blade. In this ultrasonic flaw detection method, flaw detection is possible by scanning an ultrasonic probe in contact with the blade surface extending from the blade root to the tip of the turbine blade, but the surface of the turbine blade is heated to a high temperature. In the ultrasonic flaw detection method that scans with direct contact with the ultrasonic probe due to exposure and erosion, the coupling between the ultrasonic probe and the blade surface is not stable, and the scanning is stable. Can not be done. That is, there is a problem that echoes from the surface of the turbine blade are large and echoes due to defects at the blade leading edge are buried in the echoes of the surface reflection, so that accurate and quick inspection cannot be performed.
[0006]
The present invention has been made in view of the above circumstances, and its purpose is to detect the surface of the front edge of the turbine blade or the inside thereof without being affected by the surface roughness of the blade surface of the front edge of the turbine blade. Another object of the present invention is to provide a flaw detection method and a flaw detection device for the surface and the inside of a turbine blade leading edge that enable periodic inspection of potential and obvious defects by accurately and rapidly flawing the turbine blade.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the method for flaw detection of a turbine blade leading edge according to claim 1 of the present invention has a cooling hole penetrating from the blade root to the tip at the leading edge, and the rotor has A method of flaw-detecting a leading edge portion of a turbine blade to be fixed by an ultrasonic probe, and having a shape extending from a blade root portion to the tip portion of the turbine blade and made of a resin capable of propagating ultrasonic waves A contact member is brought into close contact with the turbine blade surface from the blade root portion to the tip portion, and an ultrasonic probe is brought into close contact with the resin contact member to scan between the blade root portion and the tip portion. Thus, flaw detection is performed on the surface and the inside of the leading edge portion of the turbine blade.
[0008]
According to a second aspect of the present invention, there is provided a flaw detection apparatus for a surface and an interior of a turbine blade leading edge, wherein the front edge of the turbine blade having a cooling hole penetrating from the blade root to the tip is formed in the leading edge. An apparatus for flaw detection with an ultrasonic probe, which is made of a resin contact member capable of propagating ultrasonic waves by adhering along the shape of the tip from the blade root of the front edge of the turbine blade, and the resin An ultrasonic probe that is brought into close contact with a contact member and reciprocally scans between the blade root portion and the tip portion, and the resin contact member is closely attached to and supported by the front edge portion of the turbine blade. And a reciprocating mechanism provided on the support for reciprocating the ultrasonic probe between the blade root and the tip.
[0009]
In the flaw detection device on the surface and inside of the turbine blade leading edge according to claim 3 of the present invention, the fitting pin fitted into the cooling hole extending from the blade root portion toward the tip portion of the turbine blade, and the The support body is detachably fixed to the turbine blade by a support body including a clamp mechanism that clamps the turbine blade from both sides in the thickness direction thereof, and the fitting pin and the clamp mechanism.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the surface and internal flaw detection method and flaw detection apparatus according to the present invention will be described below with reference to the drawings.
[0011]
FIG. 1 is an explanatory diagram of a case where a resin contact member 3 capable of propagating ultrasonic waves is brought into contact with the front edge portion 2 of the blade surface of the turbine blade 1 and flaw detection is performed using the ultrasonic probe 4. is there. A cooling hole 5 for air cooling is formed through the front edge 2 of the turbine blade 1 from the base fixed to the rotor to the tip 7.
[0012]
The ultrasonic probe 4 is supported on a support 8 via a gimbal mechanism 9. The support 8 has a frame portion 10 extending in the vertical direction. A motor 11 is fixed to the upper portion of the frame portion 10. An encoder 12 is provided below the frame portion 10. A toothed pulley 14 is provided on the output shaft 13 of the motor 11, and a timing belt 15 is stretched between the toothed pulley 14 and the encoder 12.
[0013]
The frame portion 10 is provided with a linear guide hole 16 extending in the vertical direction. A moving body 17 is connected to the timing belt 15 via a linear guide hole 16, and a guide rod 18 is provided on the moving body 17. The gimbal mechanism 9 includes the guide rod 18, a block 19 guided by the guide rod 18, a spring 20 that urges the block 19 in the direction of arrow A, and an ultrasonic probe 4 that is implanted in the block 19. It is comprised from the support plate 21 supported so that a movement is possible.
[0014]
The resin contact member 3 typically has a shape along the outer shape of the leading edge 2 as shown in FIG. 2 on the side of the surface 3b that contacts the turbine blade leading edge 2. By bringing the resin contact member 3 into contact with the turbine blade leading edge 2, a gap between the resin contact member 3 and the front edge 2 through which the cooling hole is penetrated is directly applied to the front edge 2. The acoustic impedance of the gap between the resin contact member 3 and the front edge 2 can be made smaller than the gap generated between the front edge 2 and the ultrasonic probe 4 when the probe 4 is brought into contact. In order to further reduce the mismatch, it is desirable to fill the gap with a filling material such as glycerin.
[0015]
The motor 11, the encoder 12, the pulley 14, the timing belt 15, the moving body 17, and the gimbal mechanism 9 reciprocally scan between the blade root portion 6 and the tip portion 7 with the ultrasonic probe 4 in close contact with the resin contact member 3. A reciprocating mechanism 22 is configured, and a filling material such as glycerin is also applied to the surface 3a of the resin contact member 3 so that the ultrasonic probe 4 is smoothly reciprocated.
[0016]
The support 8 is provided with an upper plate 23 at the top thereof, and the resin contact member 3 is supported by the upper plate 23. The upper plate 23 is provided with a fitting pin 24 at a location corresponding to the cooling hole 5, the tip of the upper plate 23 is bifurcated and bent downward, and a clamp mechanism 25 is provided on the bent plate portion 23a. Yes. The clamp mechanism 25 is generally composed of a disc-shaped knob 26, a disc-shaped elastic clamping member 27, and a screw member 28 that is screwed into a screw hole (not shown) formed in the bent plate portion 23a. The clamp mechanism 25 is a turbine. The blade 1 is clamped from both sides in the thickness direction. The support 8 is used as an inspection jig that is detachably fixed to the turbine blade 1 during the periodic inspection by the clamp mechanism 25 and the fitting pin 24, and the resin contact member 3 is thereby provided through the cooling hole. It is closely attached to the front edge 2.
[0017]
The driving of the motor 11, the scanning position information of the ultrasonic probe 4 from the encoder 12, and the transmission / reception control of the ultrasonic wave of the ultrasonic probe 4 are performed by the flaw detector main body 29 shown in FIG. The flaw detection apparatus main body 29 includes a battery 30, a flaw detection circuit 31, a scanning control circuit 32, and a printer 33. The battery 30 is supplied with AC 100 V power via a battery charger 34. When the switch (not shown) is turned on, the scanning control circuit 32 drives the motor 11 via the cable 35. As a result, the timing belt 15 is rotated, and pulse information of the encoder 12 rotated by the rotation of the timing belt 15 is input to the scanning control circuit 32 via the cable 35, whereby the scanning position of the ultrasonic probe 4 is detected. Information is detected.
[0018]
The ultrasonic probe 4 includes, for example, those shown in FIG. 4A and FIG. 5A, and receives ultrasonic waves reflected from the transducer 36 and the front edge 2 that transmit ultrasonic waves. Receiver (not shown). Transmission / reception of signals between the ultrasonic probe 4 and the flaw detection circuit 31 is performed via a cable 37. Then, the flaw detection circuit 31 outputs flaw detection inspection information to the printer 33 for each predetermined scanning position information, and the printer 33 prints out the information.
[0019]
Next, when the ultrasonic probe 4 is directly brought into contact with the front edge portion 2 without interposing the resin contact member 3 and scanned, the resin contact member 3 is moved to the ultrasonic probe 4 and the front edge portion. 2 and a comparative example of the result of flaw detection of the front edge 2 by interposing a filling material that fills the gap between the front edge 2 and the resin contact member 3.
[0020]
FIG. 4A shows a case where the ultrasonic probe 4 is directly brought into contact with the front edge portion 2 without the resin contact member 3 interposed, and flaw detection scanning is performed, and FIG. 4B shows the flaw detection result. It is a graph.
[0021]
Here, it is assumed that a defect 38 exists on the surface of the front edge portion 2 penetrating the cooling hole, and a defect 39 exists on the peripheral wall of the internal cooling hole 5. When scanning with the ultrasonic probe 4 in direct contact with the front edge portion 2, the surface of the front edge portion 2 is greatly roughened, so that the scanning is not performed smoothly, and the ultrasonic probe 4 vibrates during scanning. And the presence of a gap makes the incidence of ultrasonic waves unstable, and the echo 40 from the surface of the leading edge 2 is large as shown in FIG. Is buried in the echo 40 from the surface, and it cannot be determined whether or not the defect 38 exists on the surface. In FIG. 4B, 41 is an ultrasonic wave transmission output, and 42 is an echo based on a defect 39 existing inside.
[0022]
FIG. 5 (a) shows that the resin contact member 3 is interposed between the front edge portion 2 penetrating the cooling hole and the ultrasonic probe 4, and between the front edge portion 2 and the resin contact member 3. FIG. 5B is a graph showing the flaw detection result when a flaw detection scan is performed on the front edge portion 2 with a filler filling the gap therebetween. In FIG. 5B, a filling material that fills the gap between the ultrasonic probe 4 and the resin contact member 3 is also interposed on the surface of the resin contact member 3 with which the ultrasonic probe 4 is in sliding contact. The obtained flaw detection results are shown.
[0023]
According to the present invention, since the ultrasonic probe 4 does not vibrate greatly during scanning and there is almost no gap, the leading edge 2 has a large possibility that a cooling hole is penetrated and a defect has a serious result. The echo 40 from the surface based on the surface roughness or the like is small, and the echo 43 based on the defect 38 inside the turbine blade is not buried in the echo 40. Reference numeral 44 denotes an echo reflected at the interface between the resin contact member 3 and the ultrasonic probe 4.
[0024]
【The invention's effect】
According to the flaw detection method and flaw detection device for the surface and inside of the turbine blade leading edge according to the present invention, it is possible to perform flaw detection inspection without being affected by the surface roughness of the turbine blade leading edge surface caused by using the actual machine. Therefore, there is an effect that the surface of the leading edge portion of the turbine blade having a complicated shape of the turbine blade and the inside thereof can be inspected accurately and quickly.
[Brief description of the drawings]
FIG. 1 is a side view of a surface of a turbine blade leading edge and an internal flaw detector according to the present invention.
FIG. 2 is a top view of the surface of a turbine blade leading edge and an internal flaw detector according to the present invention.
FIG. 3 is a circuit diagram of the flaw detection apparatus on the surface and inside of the turbine blade leading edge according to the present invention.
FIG. 4 is an explanatory diagram of a case where flaw detection scanning is performed with an ultrasonic probe in direct contact with the blade surface without interposing a resin contact member. FIG. The conceptual diagram which carries out a flaw detection scan by making an acoustic probe contact the blade surface is shown, and (b) is a graph which shows the flaw detection result.
FIG. 5 is an explanatory diagram for explaining the operation of a turbine blade surface and an internal flaw detector according to the present invention, wherein (a) shows a resin contact member between the blade surface and an ultrasonic probe; A conceptual diagram of performing flaw detection scanning on the blade surface by interposing a filling material filling the gap between the front edge portion having the cooling hole and the resin contact member is shown, and (b) shows the flaw detection result. It is a graph.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Turbine blade 2 ... Leading edge part 3 ... Resin contact member 4 ... Ultrasonic probe 5 ... Turbine blade cooling hole 6 ... Blade root part 7 ... Tip part

Claims (3)

It has a cooling hole penetrating from the blade root part to the tip part at the leading edge part, and is a method of flaw-detecting the leading edge part of the turbine blade fixed to the rotor with an ultrasonic probe,
A resin contact member having a shape extending from the blade root portion of the turbine blade to the tip portion and capable of propagating ultrasonic waves is brought into close contact with the turbine blade surface from the blade root portion to the tip portion. The front surface of the turbine blade is flaw-detected by scanning the probe between the blade root portion and the tip portion while bringing the acoustic probe into close contact with the resin contact member. Edge inspection method. The leading edge of the turbine blade to have a formed through cooling holes over the distal portion from the blade root to the leading edge to a device for testing by the ultrasonic probe,
A resin contact member capable of propagating ultrasonic waves by adhering along the shape of the tip from the blade root of the front edge of the turbine blade;
An ultrasonic probe that closely contacts the resin contact member and reciprocally scans between the blade root and the tip;
A support for closely supporting the resin contact member to the front edge of the turbine blade; and
A reciprocating mechanism provided on the support and reciprocating the ultrasonic probe between the blade root and the tip;
The surface of the front edge part of the turbine blade and the internal flaw detection device characterized by comprising.   The support body having a fitting pin fitted into the cooling hole extending from the blade root portion of the turbine blade toward the tip portion, and a clamp mechanism for clamping the turbine blade from both sides in the thickness direction; The surface of the front edge part of the turbine blade and an internal flaw detector according to claim 2, wherein the support body is detachably fixed to the turbine blade by the fitting pin and the clamp mechanism. .

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