JPH0711509B2 - Turbine component deterioration detection device - Google Patents

Description

The present invention relates to a deterioration detecting device for a turbine component.

(Prior Art) Creep damage occurs in the groove shoulder (2) of the high / intermediate pressure turbine blade (18) as shown in Fig. 2 due to long-term use, and this causes the creep damage to cause blade scattering accident. Occurs, so
It is necessary to inspect the groove shoulder (2) of the turbine blade (18) for creep damage.

(Problems to be solved by the invention) However, conventionally, when inspecting the creep damage of the groove shoulder (2) of the turbine blade (18), the turbine blade (18) is pulled out to clean the inner surface of the groove shoulder (2). The only way to inspect was with the naked eye. In this case, a non-destructive check is possible, but on the other hand, it is difficult to see the inner surface of the groove shoulder (2) even if the turbine blade (18) is pulled out. Also, removing the turbine blade (18) is a large task, and it takes a long time to inspect the ruler.
Little inspection was done for creep damage on the groove shoulders (2) of the turbine blades (18).

The present invention is proposed in view of the above problems, and an object of the present invention is to perform a deterioration inspection of a turbine component that can be accurately inspected for non-destructive creep damage of the turbine component and not by visual inspection. The point is to provide the device.

(Means for Solving the Problems) In order to achieve the above object, the present invention has an ultrasonic probe that contacts a turbine component, and a signal processing circuit connected to the ultrasonic probe. , A fixed coupling transducer for directly targeting the damaged region of the turbine to the ultrasonic probe, ultrasonic echoes in different directions that enter the damaged region of the turbine component from different directions and return from there And a variable angle transducer for receiving the signal processing device, and the signal processing device has a level for correcting a damaged region echo by comparing a variation factor of an echo level based on a coupling disparity between an ultrasonic probe and a turbine component with a reference echo. A correction circuit, an averaging circuit that prevents the entry of electrical noise, a level controller for damaged area echoes, a correlation circuit, an echo frequency analysis circuit, and these level adjusters, correlation circuits, and frequency components. A determination circuit for determining the degree of creep damage connected to the analysis circuit is provided.

(Operation) The deterioration detecting device for a turbine component of the present invention is configured as described above, and a fixed coupling oscillator and an angle for providing a damage region echo returning from a damage region of the turbine on the ultrasonic probe are provided. It is received by the variable transducer and sent to the level correction circuit of the signal processing circuit, where the factor of echo level variation based on the coupling disparity between the ultrasonic probe and the turbine component is corrected and compared with the reference echo. The corrected damage area echo is sent to the averaging circuit to prevent the inclusion of electrical noise, etc., and then this averaging circuit is sent to the damage area echo level adjuster, correlation circuit and echo frequency analysis circuit for creep damage. The degree of creep damage is determined from the level adjuster, the correlation circuit, and the frequency analysis circuit to the determination circuit. Then, "damage relation data" between the damage change and these pieces of information is obtained in advance by an experiment, and the judgment circuit performs weighting based on this data to improve the judgment accuracy.

(Embodiment) Next, an embodiment of the deterioration detecting device for a turbine component of the present invention will be described with reference to FIG. 1. (1) is an ultrasonic probe, and the ultrasonic probe (1) is a turbine A transducer for a coupling check, which directly targets the creep damage (3) of the blade groove shoulder (2) (fixed position, flat transducer or focus probe) (4), and a transducer (rotation direction ( 6) variable angle focus probe) and (5).

The oscillator (5) is rotated by a desired angle about an axis (7) of a driving device (not shown) such as a stepping motor. The rotation angle of the vibrator (5) is checked by means (not shown) such as an encoder attached to the shaft (7). These oscillators (4) (5)
Ultrasonic waves are transmitted and received between the two flaw detectors (8) and (9).

Reference numeral (10) is a signal processing circuit, and the level correction circuit (11) of the signal processing circuit (10) is a factor for varying the echo level based on the coupling difference between the ultrasonic probe (1) and the rotor surface (12). Is compared with the reference echo signal and corrected.

(13) is an averaging circuit for preventing mixing of electrical noise and the like, and is designed to improve the S / N of the level-corrected echo.

(14) is a damaged area echo level adjuster, (15) is a correlation circuit, (16) is an echo frequency analysis circuit, (17) is a judgment circuit, and an averaging circuit (13) is a level adjuster (14). And the correlation circuit (15) and the echo frequency analysis circuit (16) are connected, and the level adjuster (14), the correlation circuit (15) and the echo frequency analysis circuit (16) are connected to the determination circuit (17). is doing.

The present invention is applicable to fine creep damage (deterioration) of turbine parts.
It is difficult to make a decision with only one piece of information, and information (plural pieces of information) from the level adjuster (14), the correlation circuit (15) and the echo frequency analysis circuit (16) is detected. Is sent to the decision circuit (17), while the decision circuit (17) weights the data to improve the decision accuracy.

Next, the operation of the deterioration detecting device for a turbine component shown in FIG. 1 will be specifically described. It is considered that creep damage of the groove shoulder (2) of the turbine blade occurs from the groove shoulders (2) to (3) in view of stress and progresses in that direction. Therefore, the transducer (probe) (5) is easy to detect this, and the transducer (probe) (4) cannot expect that much detection. However, in any case, the creep damage (3) is
Since it is minute, its detection is not easy, and it is necessary to detect it with high sensitivity.

At this time, a change in signal level occurs due to the coupling of the ultrasonic probe (1). Therefore, if two echoes are detected by the coupling check transducer (4) and the signal obtained by the transducer (probe) (5) is corrected so that the echo levels are the same as before, creep will occur. The degree of damage can be grasped more accurately.

As the creep damage (3) progresses, many fine echoes are randomly generated. When the signal generation state is converted in this way, the correlation function (as a function, the oscillator (4)
(5) Autocorrelation of each signal, cross-correlation between the transmission signal and reception signal of the oscillator (4) or the oscillator (5), oscillator (4)
Or the mutual relation of the received signals of the vibrator (5) is considered). Correlation circuit (1
If it is detected by 5), a minute damage change can be detected.
Similarly, since the frequency components also change, if the frequency analysis circuit (16) also detects these frequency component changes, the damage change detection information is extracted. Also, [damage relation data] between the damage change and these pieces of information is obtained in advance by an experiment, and a judgment circuit (17) performs weighting based on this data to improve judgment accuracy.

Next, the above point will be supplementarily described.

(1) First, a supplementary explanation will be given on the deterioration phenomenon (creep damage) of turbine components.

As a deterioration phenomenon (creep damage) of a turbine component, there is a micro void (a minute void) as illustrated in FIG. 3 (b). When such micro voids occur,
The following phenomena occur due to scattering and attenuation of ultrasonic waves.

Reflection signal change: Due to scattering, the echo from part B (in the material) increases. Further, the echo at the A portion (bottom portion) is reduced.

Frequency component change: The ultrasonic wave is attenuated due to scattering etc., but the attenuation state changes depending on the frequency. Usually, the high frequency component contained in the echo is attenuated more.

Others (with respect to correlation): There are various methods of sensitization. For example, if the autocorrelation of the echo from the B section is taken,
It is considered that the correlation value changes due to deterioration. That is,
A sound wavelength ultrasonic echo is as shown in FIG. When microvoids are generated, reflection also occurs from here, so that an echo from the B portion is generated and an echo at the A portion is reduced as shown in FIG. 4 (b). Further, when the autocorrelation is taken only by the echo of the B section, the correlation value immediately becomes 0 as shown in FIG. 5 (a), but at the time of deterioration, the B section has not only electrical noise but also an ultrasonic echo signal. Therefore, the echo changes as shown in FIG.

It should be noted that the actual B section echo is a minute signal, and further has electrical noise as shown in FIG. Although not related to deterioration, the ultrasonic coupling state changes depending on how the ultrasonic probe (1) and rotor (subject) (12) are pressed. This is because ultrasonic waves are multiple-reflected in couplant (water or oil) as shown in FIG. 6 and cause interference, and therefore correction is necessary when the signal level change is strictly measured.

(2) Next, the above-mentioned operation will be supplementarily described.

First, the ultrasonic signals are averaged and random electrical noise is reduced to obtain only the purest ultrasonic signal. Next, for example, the correction shown in FIG. 7 is performed in order to prevent the echo from changing due to the coupling. That is, when the signal changes from the good coupling shown in FIG. 7 (a) to the poor coupling shown in FIG. 7 (b), due to the poor coupling,
Since the passage between the ultrasonic probe (1) and the rotor (subject) (12) is only bad, the signals are similarly reduced in both the A section and the B section. For this reason, if the sensitivity correction is performed so that the signal of the section A is always constant and the signal of the section B is checked, the influence of coupling can be removed from the signal of the section B.

Next, from such a signal (for example, the signal of the part B),
Check the degree of deterioration.

Signal level: If the deterioration is large, the signal in the B section also becomes large.

Frequency component: Frequency analysis is performed to check, for example, a high frequency component. When the deterioration is large, the high frequency component is small when comparing the high frequency component and the low frequency component (normal example).

Correlation: For example, when an autocorrelation is taken, the value of the correlation function changes as compared to when there is no deterioration.

Although the degree of deterioration can be determined by each of these outputs, the determination circuit (17) makes a determination to further improve the accuracy.

For example, each circuit output is taken as follows.

Level judgment output L ... Signal amplitude of B part Frequency analysis Correlation S ... A width where the correlation value becomes 0.5 as shown in FIG.

And for R _{1 to} R _n as samples with different deterioration degrees R,
Measure each value. For example, , A, B, so that the error is minimized
Decide on C. When an unknown sample comes next using these A, B, and C, the deterioration degree R is obtained by R = AL + BF + CS, and is output from the judgment circuit (17).

(Effects of the Invention) As described above, the deterioration detecting device for a turbine component according to the present invention has a fixed coupling check vibrator and a variable angle vibration in which an ultrasonic probe is provided with a damaged region echo returning from the damaged region of the turbine. Received by the child and sent to the level correction circuit of the signal processing circuit, where the factors of echo level variation due to the coupling disparity between the ultrasonic probe and the turbine component are corrected by comparison with the reference echo, and this corrected damage is corrected. Sending the area echo to the averaging circuit to prevent mixing of electrical noise etc., then sending from the averaging circuit to the level adjuster of the damaged area echo, the correlation circuit, the frequency analysis circuit of the echo,
The degree of creep damage is determined, and further sent from the level adjuster, correlation circuit and frequency analysis circuit to the determination circuit to determine the degree of creep damage. Then, "damage relation data" between the damage change and these information is obtained in advance by an experiment, and the judgment circuit performs weighting based on this data to improve the judgment accuracy. Personality can be inspected destructively and without relying on the naked eye inspection.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a deterioration detecting device for a turbine component of the present invention, FIG. 2 is an explanatory diagram showing a damaged region of the turbine component, and FIG. 3 is an explanatory diagram showing scattering and attenuation of ultrasonic waves. ,
FIG. 4 is an explanatory view showing changes in ultrasonic echoes, FIG. 5 is an explanatory view showing a relationship between a correlation value and delay time, and FIG. 6 is an explanatory view showing a state of ultrasonic waves reflected multiple times between couplants, 7th
FIG. 8 is an explanatory diagram showing a signal change due to coupling, and FIG. 8 is an explanatory diagram showing a correlation value width. (1) ... ultrasonic probe, (2) ... turbine blade groove shoulder, (3) ... creep damage region, (4) ... coupling for vibrators for coupling, (5) ... variable angle Oscillator,
(6) …… Rotation direction, (7) …… Axis, (8) (9) ……
Flaw detector, (10) …… Signal processing circuit, (11) …… Level correction circuit, (12) …… Roller surface, (13) …… Averaging circuit,
(14) …… Level controller for damaged area echo, (15) ……
Correlation circuit, (16) …… Echo frequency analysis circuit, (17)
...... Judgment circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Enami 2-1-1 Niihama, Arai-cho, Takasago-shi, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Research Institute (72) Inventor Ito 2--1 Niihama, Arai-cho, Takasago-shi, Hyogo Prefecture No. 1 Mitsubishi Heavy Industries, Ltd., Takasago Laboratory (56) Reference JP 54-153691 (JP, A) JP 59-17154 (JP, A) JP 58-99748 (JP, A)

Claims (1)

[Claims] 1. An ultrasonic probe for contacting a turbine component,
A signal processing circuit connected to the same ultrasonic probe, and a fixed coupling check vibrator for directly targeting a damaged region of the turbine to the ultrasonic probe, and a turbine component from a different direction. A variable angle transducer that receives ultrasonic echoes in different directions that enter and return from the damaged region of the ultrasonic wave, and the echo level based on the coupling difference between the ultrasonic probe and the turbine component is provided in the signal processing device. A level correction circuit that corrects the damaged area echo by comparing the fluctuation factor of the reference echo with the reference echo, an averaging circuit that prevents the mixing of electrical noise, a level controller for the damaged area echo, and a correlation circuit,
A deterioration detecting device for a turbine component, comprising: an echo frequency analysis circuit; and a determination circuit for determining the degree of creep damage connected to the level adjuster, the correlation circuit, and the frequency analysis circuit.