JPH0244245A - Ultrasonic flaw detector for turbine rotor - Google Patents

Abstract

PURPOSE:To obtain a highly reliable ultrasonic flaw detector at a low cost without use of a shoe by making an ultrasonic wave incident into a turbine rotor emmersed in water from a probe with water as medium to detect flows receiving reflected wave from an internal defect. CONSTITUTION:Water 2 is stored into a water tank 4 to immerse a turbine rotor 6 sufficiently thereinto and an ultrasonic beam 22 is made incident into the rotor 6 with the water 2 as medium from a probe 14. Under such a condition, a rotor rotating device 12 is driven to rotate the rotor 6 and flaws are detected over the entire circumference thereof 6. An angle of incidence of the beam 22 is obtained easily by adjusting a holder so that an inclination to the rotor 6 of the probe 14 reaches a specified angle. The probe 14 performs a transmission and reception concurrently with a built-in vibrator by being cut out of a piezo-electric material and receives reflected wave from an internal defect. In this manner, after the end of a flaw detection at one part, the holder is adjusted to set the ultrasonic beam for the subsequent flaw detection position and then, another flaw detection is performed. This eliminates the use of any shoe thereby enabling detection of flaws in such a manner as to be easy to handle with limited incidence loss and inexpensive and stable with limited noise.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an ultrasonic flaw detection method that detects internal defects such as cracks that occur during use of a turbine rotor during inspection when the turbine rotor is out of operation. Regarding equipment.

[Conventional technology]

Turbine rotors are forced to rotate at high speeds under high temperatures, so it is necessary to check their soundness during use. It is especially important to check the health of a device that has been used at high temperatures for a long time or has been started and stopped many times.

In a turbine rotor, stress is maximum at the center of the rotor due to centrifugal force caused by operation. Therefore, usage progresses,
As the rotor material deteriorates, cracks may first occur in the center of the rotor due to operation or deterioration of the rotor material, and this is one of the major causes of impairing the integrity of the rotor material. Therefore, as a means of confirming the soundness of the rotor material, it is essential to detect cracks that occur in the center of the rotor, and ultrasonic flaw detection is used for this flaw detection.

[Problem to be solved by the invention]

FIG. 4 is a sectional view showing the entire turbine rotor 6, in which the blades 18 and the labyrinth ring 20 are implanted. To perform ultrasonic flaw detection on a turbine rotor 6 that does not have a center hole, the probe 14 is brought into close contact with the outer circumferential surface of the turbine rotor 6 using the implanted part of the blade 18 and the area that avoids the labyrinth ring 20. This is carried out by injecting the acoustic beam 22 into the turbine rotor 6. That is, this flaw detection is carried out as shown in the cross-sectional views of FIG. 5 and FIG. 6, which show the section taken along line AA in FIG. First, as shown in FIG. 5, in order to detect defects in all directions with respect to the diametrical direction 6b of the turbine rotor 6,
It is required to perform flaw detection at several angles α by changing the angle α between the diametrical direction 6b and the ultrasonic beam 22, and the flaw detection at these angles α covers the entire circumferential and axial length of the turbine rotor 6 as shown by the arrow 24. Usually carried out over a period of time. In order to make the ultrasonic beam 22 enter the inside of the turbine rotor 6 at an angle α, as shown in FIG. incident. The inclination of the probe 14 to obtain the angle α and the angle θ are determined by the following formula C11.

α=sin −' (--sin θ) ・・
...---(11C! Here, C1: Speed of sound inside the shoe 26 C!: Speed of sound inside the turbine rotor 6, that is, the shoe 26 has an inclination of angle θ and is in close contact with the turbine rotor 6 without any gaps. Ultrasonic beam 22
In order to improve the incidence of the flaws, it is necessary to prepare a large number of shoes 26 having a curvature that matches the outer circumferential curvature of the turbine rotor 6 for each incident angle α and for each different outer diameter of the turbine rotor 6 in the flaw detection section. .

FIG. 7 is a sectional view showing a state in which ultrasonic flaw detection is performed via a grooved shoe 28 that avoids the labyrinth ring 2o for flaw detection. FIG. 8 is a cross-sectional view showing details of the labyrinth ring 20. A groove 6c is provided in the turbine rotor 6, and a ring-shaped labyrinth ring 20 with an L-shaped cross section is formed in the groove 6c.
A ring-shaped corner [30] is implanted and fixed by driving it in place, and the gap between it and the casing side element (not shown) is reduced to create a labyrinth (Labyrinth).
8) to prevent steam leakage.

The grooved shoe 28 shown in FIG.
Similar to the shoe 26 in the figure, it has an inclination of an angle θ according to the incident angle α of the ultrasonic beam 22, and is in close contact with the turbine rotor 6 without any gaps to improve the incidence of the ultrasonic beam 22. It is necessary to prepare a large number of grooved shoes 28 having a curvature matching the outer circumferential curvature of the turbine rotor 6 for each incident angle α and each outer diameter of the turbine rotor 6 in the flaw detection section.

In general, the turbine rotor 6 has many stages with different diameters, and a plurality of labyrinth rings 20 are implanted in each stage, and the spacing between adjacent labyrinth rings 20 often differs from stage to stage. , the number of grooved shoes 28 that must be prepared is enormous;
There was a problem in that it was extremely uneconomical and required many man-hours to store and search for it when necessary. Also, Shu 26.
The I-equipped shoe 28 and the turbine rotor 6 come into contact with each other as hard objects, and the two do not fit well, causing a propagation loss of the ultrasonic beam 22 at the contact surface between the two, and reducing the intensity of the incident ultrasonic beam 22. There's a problem.

Furthermore, in the grooved shoe 28, since the labyrinth ring 20 is avoided by providing the groove 28a, the propagation of the ultrasonic beam 22 is hindered by the groove 28a, and the incident intensity of the ultrasonic beam 22 is further reduced. There is.

The present invention minimizes the incident propagation loss of the ultrasonic beam to the turbine rotor without using shoes with different shapes or dimensions, or shoes with grooves, thereby achieving an overall low cost, easy handling, and stability. The purpose of the present invention is to provide an ultrasonic flaw detection device for turbine rotors.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an ultrasonic flaw detection device for a turbine rotor that non-destructively detects internal defects in a turbine rotor using ultrasonic waves. A water tank for storing water and immersing the entire turbine rotor in this water, and a pair of roller holders provided in the water tank for rotatably supporting the turbine rotor by loading the turbine rotor on the rollers. and,
a rotor rotation device that is connected to one end of a turbine rotor provided in the water tank and supported by the pair of roller holders to rotate the turbine rotor; and a fixed measurement distance from the surface of the turbine rotor to be inspected for flaws. The ultrasonic probe is provided with an ultrasonic probe supported by a holder whose installation position is variable and separated by a distance, and an ultrasonic nozzle which is detachably attached to the probe.

[Effect]

In the present invention, the entire turbine rotor is immersed in a water tank in which water as an ultrasonic medium is stored, and the turbine rotor is rotatably supported by being loaded on a roller holder provided in the water tank. One end of the turbine rotor is connected to a rotor rotation device installed in the water tank to rotate the turbine rotor, and an ultrasonic nozzle installed at a certain measurement distance from the surface of the turbine rotor to be inspected is attached and detached. Since it is an ultrasonic flaw detection device equipped with ultrasonic probes that can be placed freely, it can stably and reliably transmit and receive ultrasonic waves into the turbine rotor using water as a medium without using a shoe. Furthermore, it is possible to reduce the ultrasonic incidence loss even at the labyrinth ring implantation site, and furthermore, it is possible to minimize the noise accompanying the scattering of ultrasonic waves even in a narrow space.

〔Example〕

FIG. 1 is a sectional view showing the entire embodiment of the present invention.

In FIG. 1, there is a water tank 4 in which water 2 serving as a medium for ultrasonic waves is stored, and the entire turbine rotor 6 is immersed in this water. A pair of roller holders 10 having a pair of rotatable rollers 8, 8 are provided in the water tank 4, and the turbine rotor 6 is loaded onto the roller 88 using a loading means such as a crane. 6 is rotatably supported. In addition, a rotor rotating device 12 is provided in the water tank 4.
A rotor rotation device 12 is provided at one end 6a of the turbine rotor 6 supported by a pair of roller holders 10.10.
are connected to rotate the turbine rotor 6. An ultrasonic probe 14 is supported by a holder (not shown) whose position W is variable, and is provided at a certain measurement distance from the surface of the turbine rotor 6 to be inspected. The probe 14 has a built-in vibrator cut out of a piezoelectric material such as crystal or barium titanate, and this vibrator serves both for transmission and reception. Further, the probe 14 is provided with an ultrasonic nozzle 16 in its transmitting/receiving section in a detachable manner. The turbine rotor 6 has blades 18 and a plurality of labyrinth rings 20 implanted in each stage.

A flaw detection operation using the ultrasonic flaw detection apparatus of the present invention configured as described above will be described next.

(a) The empty water tank 4 that does not contain water 2 is provided with a roller holder IO and a rotor rotating device 212.

In order to detect multiple types of turbine rotor 6 within a certain size range, each part has different dimensions, so one
A sliding mechanism may be provided so that the distance between the pair of roller holders 10.10 can be adjusted and the center height of the rotor rotating device can be adjusted for centering. Further, the probe 14 is moved by adjusting the holder to a position where it does not interfere with the cargo handling work of the turbine rotor 6.

(b) The turbine rotor 6 is unloaded by a loading means such as a crane, and the pair of rollers 8 on the roller cradle 10.10 is loaded.
．． Load it on top of 8. One end 6a of the turbine rotor 6 on the rotor rotation device 12 side is connected to the rotor rotation device 12. At this time, it is convenient to connect via a flexible joint because the connection work is facilitated and smooth power transmission is possible. .

(c) Adjust the holder and install the probe 14 at the desired flaw detection position. At this time, the probe 14 is equipped with an ultrasonic nozzle 16 if necessary.

(d) A desired amount of water 2 is stored in the water tank 4, and the turbine rotor 6 is sufficiently immersed.

(The ultrasonic beam 22 is input from the ladle probe 14 into the turbine rotor 6 through the water 2 as a medium. In this case,
Since water 2 is used as a medium instead of a solid medium like the shoe 26 of the conventional example, the ultrasonic beam 22 is extremely stable and enters the turbine rotor 6 with little incident loss.

(f) In this state, the rotor rotation device ff12 is driven to rotate the connected turbine rotor 6, and the entire circumference of the turbine rotor 6 is inspected for flaws. To obtain the incident angle α of the ultrasonic beam 22 (see FIGS. 5 and 6 above), the probe 1
4 with respect to the turbine rotor 6 can be easily obtained by adjusting and tilting the holder to a predetermined angle θ (see FIG. 6). The angle θ of this inclination is, according to the above fl1 formula,
C, is obtained by replacing the sound speed in the shoe 26 with the sound speed in water. At the labyrinth ring 20, there is some incident loss even when water 2 is used as a medium, but the incident loss is equal to the amount of the incident loss due to the propagation being obstructed by a28a of the grooved shoe 28 explained in FIG. 7 of the conventional example. Therefore, the incident loss of the ultrasonic beam 22 is significantly reduced compared to when using the grooved shoe 28.

(G) After flaw detection of one part is completed in this manner, the holder is adjusted, the probe I4 is placed at the next flaw detection position, and flaw detection is performed in the same manner as described above.

(After flaw detection has been completed at all flaw detection positions on the turbine rotor 6, drain the water 2 from the water tank 4, move the probe 14 to a position where it will not interfere with cargo handling work, and
Release the connection between the one end 6a and the rotor rotation device 12,
The turbine rotor 6 is carried out by a loading means such as a crane.

When subsequently performing ultrasonic flaw detection on the next turbine rotor 6, the next flaw detection may be performed without discharging the water 2 if cargo handling and connection work are not difficult. However, if the ultrasonic flaw detection device is to be stopped for a long period of time after the work is finished and before the next flaw detection, drain the water 2 and remove the roller holder 10. Rotor rotation device 12. Probe 14. Equipment such as the ultrasonic nozzle 16 should be thoroughly wiped with water and treated to prevent rust.

Figures 2 and 3 are F! J contact blade 18.18
Fig. 2 is a cross-sectional view showing the state in which only the probe 14 is used, and Fig. 3 is a cross-sectional view showing the state where only the probe 14 is used. 14 is a sectional view showing a state in which the ultrasonic nozzle 16 is attached to the ultrasonic nozzle 14 and used.

In FIG. 2, in addition to the ultrasonic beam 22 incident on the turbine rotor 6, a diffused ultrasonic beam 22a is
For example, the beam hits the blades 18, 18 and is reflected therein as a scattered beam 22b which is received by the probe 14, increasing noise and interfering with flaw detection of the turbine rotor 6.

FIG. 3 shows a device in which the drawbacks explained in FIG. 2 are eliminated, and an ultrasonic nozzle 16 is attached to the probe 14. This ultrasonic nozzle 16 is made into a cylindrical shape with external dimensions that can be inserted between the blades 18 and 18, and the diffused ultrasonic beam 22a is reflected on the inner surface of the ultrasonic nozzle 16 as shown in the figure, causing a turbine. However, the scattered beams from this do not reach the probe 14 and are not received, reducing noise. Therefore, even in such a narrow space, the ultrasonic beam 220 is stable and has little incident loss. Sonic flaw detection can be performed. Since the dimensions of the narrow part of the turbine rotor vary widely, a plurality of ultrasonic nozzles 16 with different external dimensions are prepared, and depending on the situation, the ultrasonic nozzle 16 with the optimum size is selected from the probe 14. For this purpose, the ultrasonic nozzle 16 is detachably attached to the probe 14.

〔Effect of the invention〕

According to the present invention, the entire turbine rotor is immersed in water, and an ultrasonic beam is transmitted to the turbine rotor from a probe equipped with an ultrasonic nozzle using the water as a medium, and is incident on the turbine rotor.
The ultrasonic flaw detection device detects flaws by receiving reflected waves from internal flaws with a probe, so there is little loss of ultrasonic waves and less noise, even in narrow spaces and complex-shaped parts of the fat turbine rotor. Stable flaw detection becomes possible, and fb) The angle θ of the probe relative to the turbine rotor is adjusted and the holder is tilted to a predetermined angle, making it easy to set the incident angle α of the ultrasonic beam to the desired value. As a result, since there is no need to use a shoe like in the conventional example, the incident propagation loss of the ultrasonic beam to the turbine rotor is minimized, resulting in an overall low cost and easy handling. It is possible to provide an ultrasonic flaw detection device for a turbine rotor that is easy, stable, and has a high degree of single rotation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the entire embodiment of the present invention, FIGS. 2 and 3 show a case where the distance between adjacent blades is narrow and the probe cannot fit between the blades, and FIG. A sectional view showing the state in which only the probe is used, Fig. 3 is a sectional view showing the state in which the ultrasonic nozzle is attached to the probe, and Fig. 4 is a sectional view showing the entire turbine rotor. , Fig. 5 to Fig. 7 are drawings showing a conventional example, Fig. 5 is a cross-sectional view taken along the line A-A in Fig. 4 showing the state of incidence and propagation of the ultrasonic beam, and Fig. 6 is a cross-sectional view showing the incident propagation state of the ultrasonic beam. A cross-sectional view taken along line A-A in Fig. 4 shows the state where the ultrasonic beam is incident on the turbine rotor at an angle α, and Fig. 7 shows ultrasonic flaw detection via a grooved shoe that avoids the labyrinth ring for flaw detection. FIG. 8 is a sectional view showing details of the labyrinth ring. 2: water, 4: water tank, 6: turbine rotor, 10: roller pedestal, 12: rotor rotation device, 14: probe, 16:
Ultrasonic nozzle, 20 Labyrinth ring, 22: Ultrasonic beam, 26: Shoe, 28: Grooved shoe. Figure 1 Figure 2 Figure 6 Figure 4 Figure 1 Figure 6

Claims (1)

[Claims] 1) In a turbine rotor ultrasonic flaw detection device that non-destructively detects internal defects in a turbine rotor using ultrasonic waves, water, which serves as a medium for ultrasonic waves, is stored inside the device and the entire turbine rotor is immersed in this water. a water tank provided in the water tank, a pair of roller holders provided in the water tank and including a pair of rotatable rollers, on which a turbine rotor is loaded and rotatably supported; A rotor rotation device that rotates the turbine rotor by being connected to one end of the turbine rotor supported by a pair of roller holders, and a holder that can be installed at a variable distance from the surface of the turbine rotor to be inspected. An ultrasonic flaw detection device for a turbine rotor, comprising: an ultrasonic probe that is supported and provided; and an ultrasonic nozzle that is detachably attached to the probe.