JP2966515B2 - Ultrasonic inspection method and ultrasonic inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a structure made of a steel material or the like using ultrasonic waves.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting without breaking, and more particularly to an optimal method for inspecting a dovetail portion (a root portion of a blade and a blade implant portion of a disk) of a turbine having a complicated shape.

[Conventional technology]

In the conventional inspection method, as shown in FIG. 7, a probe is installed on a flat portion (a fluid inlet side or an outlet side) of a dovetail portion, and the presence or absence of a defect is determined by receiving a reflected wave from the defect. It is to judge. This method uses the circumferential direction (θ)
It is suitable for detecting a defect 3 that extends in the uniaxial direction (z). However, when trying to detect a radial defect 4 that extends in the axial direction (z) and one radial direction (r), the reception intensity is small because the area of the defect irradiated with ultrasonic waves is small, and it is difficult to detect the defect. . On the other hand, a method for detecting this radial defect is described in Materials, Evaluation 41-13.
(1983) pages 1511 to 1516 (Materials Evaluati
on, vol. 41, No. 13 (1983) PP1511-1516). The disk described in this document has a shape shown in FIG. 8, and a probe can be installed in a constricted portion below a dovetail portion. In this case, since the area of the radial defect 4 to which the ultrasonic wave is applied is large, the reception intensity of the ultrasonic wave is large and the defect can be detected.

[Problems to be solved by the invention]

The above conventional technique has a problem that it cannot be applied to the inspection of a disk dovetail portion having no constricted portion (inclined portion) below the dovetail portion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic inspection for a radial entry generated in a tab tail portion of an axial entry type turbine in which a tab tail groove is machined in a direction perpendicular to a disk surface regardless of whether or not the disk has a constricted portion. It is an object of the present invention to provide an ultrasonic inspection method and an ultrasonic inspection device that can be reliably detected by the method.

[Means for Solving the Problems] In order to achieve the above object, the present invention divides the inspection area of the tab tail portion of the axial entry type turbine in which the tab tail groove is machined in the direction perpendicular to the disk surface into three regions in the axial direction. And inspected in the following manner.

In the central part in the axial direction when divided into three regions, two probes are prepared for transmission and reception, and are respectively installed on the fluid inlet side and the outlet side of the disk. An ultrasonic wave is transmitted from a probe installed on the surface on the fluid inlet side, and a reflected wave from a defect is received by the probe installed on the outlet side. For inspection of both ends, two or one probe is provided on the surface on the fluid inlet side or the fluid outlet side. The ultrasonic wave transmitted from the probe is reflected and received by the defect and the surface on which the probe is not installed.

The presence or absence of a defect is determined based on whether or not a reflected wave from the defect can be received.

[Action]

In the inspection of the central portion in the axial direction divided into three regions, the ultrasonic wave transmitted from the probe is incident on the defect from an oblique direction and is reflected in a direction opposite to the incident direction. This reflected wave is received by another probe (reception probe) installed on the opposite side of the transmission probe. In the receiving probe, a reflected wave from the inner shape of the dovetail portion is obtained in addition to a reflected wave from the defect. Therefore, a time gate is set in advance on a time axis on which a reflected wave from the defect is obtained, and only the reflected wave from the defect is extracted. Therefore, if there is no defect, no signal is obtained in the gate, and the presence or absence of the signal in the gate determines the presence or absence of the defect. In the inspection of both ends, first, the ultrasonic wave reflected by the defect and then reflected by the surface opposite to the surface where the transmitting probe is installed (or the ultrasonic wave of the propagation path opposite thereto) is transmitted to another probe. Or receive with the same probe. In this case as well as in the central part in the axial direction, depending on whether there is a signal in the gate,
The presence or absence of a defect is determined.

〔Example〕

First, the inspection method will be described focusing on the installation surface of the probe. FIG. 9 shows a method for detecting a defect 4 occurring in the first hook. Probes are installed on the fluid inlet and outlet sides. Either may be the transmitting probe or the receiving probe, but here, the probe 5 on the fluid inlet side is used for transmitting, and the probe 6 on the outlet side is used for receiving. The ultrasonic wave actually transmitted into the test object (dovetail part) 1 spreads in a certain range depending on the size, frequency, and the like of the vibrator. But here,
The part with the highest intensity in the spread (hereinafter referred to as the sound axis)
At the position where the sound axis coincides with the inspection point 8.
Install 5,6. If the defect 4 exists at the inspection point 8, the ultrasonic wave 7 obliquely incident on the specimen (dovetail) 1 is reflected by the defect 4 and is reflected by the receiving probe 6 installed on the fluid outlet side. The position is reached (the probe is shown by a solid line in FIG. 9). When moving the inspection point 8 in the a direction of the axis (z), the transmission and reception probes 5, 6 are scanned in the a direction. On the other hand, when the inspection point 8 is moved in the b direction, the transmission and reception probes 5, 6 are scanned in the b direction. If you try to inspect both ends of the dovetail in this way,
Since a probe having a finite size cannot be installed, there is a region where ultrasonic waves cannot enter and inspection is impossible (A and C in FIG. 9). Therefore, in the inspection of the region A on the fluid inlet side, the first
As shown in FIG. 0, the transmitting and receiving probes 5, 6 are installed on the fluid outlet side. The ultrasonic wave 7 transmitted obliquely from the probe 5 is reflected by the defect 4, then reflected by the surface on the fluid inlet side, and received by the receiving probe 6. The same applies to the case where the positions of the probes 5 and 6 are reversed and the propagation paths are reversed. further,
In the inspection of the region C on the fluid outlet side, the transmitting and receiving probes 5, 6 are installed on the fluid inlet side as shown in FIG. The ultrasonic wave 7 transmitted obliquely from the probe 5 is reflected by the defect 4, then reflected by the surface on the fluid outlet side, and received by the receiving probe 6. Also in this case, the same result is obtained even when the positions of the probes 5 and 6 are reversed and the propagation paths are reversed. Area A
And C, since the probe has a finite size, the transmitting and receiving probes 5, 6 are placed on the same plane,
And it may not be able to be installed on the same line. In such a case, as shown in FIG. 12, the transmission and reception probes are shifted left and right, that is, arranged in a staggered manner, and the inspection is performed.

FIG. 1 shows an ultrasonic inspection apparatus for embodying the present method. In FIG. 1, 5 is a transmitting probe, 6 is a receiving probe, 7 is an ultrasonic wave, 9 is a transmitter, 10 is a receiver, 11 is a circuit for determining the presence or absence of a received wave, and 12 is a threshold value. Setting circuit, 13 is a gate setting device, 14 is a propagation distance measuring device, 15 is a peak value detector,
16 is a display.

 FIG. 2 is an explanatory diagram of a signal waveform.

First, an ultrasonic wave 7 (FIG. 2A) is transmitted from the transmission probe 5 in accordance with a transmission signal (FIG. 2A) from the transmitter 9. The ultrasonic wave 7 having propagated through the dovetail portion is received by the receiving probe 6 and sent to the receiver 10 (FIG. 2C). The received ultrasonic wave 7 has a signal in a gate (FIG. 2D) which has been set in advance and is equal to or more than a threshold value (FIG. 2E) set for noise elimination by a received wave presence / absence determining unit 11. Is determined. If a defect exists, a reflected wave equal to or larger than the threshold value is obtained in the gate, and the presence / absence determination unit 11 for the received wave determines that there is a signal. The signal obtained by the received wave presence / absence determining unit 11 is sent to a propagation distance measuring unit 14 and a peak value detector 15. The propagation distance measuring device 14 measures the time from transmission to reception of the signal, and multiplies the time (T) by the sound speed (v) of the test object to determine the propagation distance (L).

L = T × v (1) The peak value detector 15 calculates the peak value of the received wave and outputs it to the display 16. In FIG. 1, the arrangement of the probe for inspecting the central portion in the axial direction is described. However, when inspecting the both end portions, as shown in FIGS. A child is set up and inspected in the same way. Here, in order to confirm the inspection result and calculate the position of the defect, the propagation distance measuring device 14,
Although the peak value detector 15 is provided, these may not be provided.

Next, a second embodiment will be described with reference to FIG. FIG. 3 shows a configuration in which four probes (5a, 5b, 6a, 6b), 17 is a transmission probe switch, 18 is a transmission probe switch,
11 are the same as those shown in FIG. Inspection of the region A on the fluid inlet side is performed by connecting the transmitter 9 and the probe 5b by the transmission probe switch 17, and by using the probe 6b by the reception probe switch 18.
And the receiver 10 are connected. The ultrasonic wave 7 is transmitted from the probe 5b by the transmission signal from the transmitter 9. The ultrasonic wave propagated in the dovetail portion is received by the probe 6b and sent to the receiver 10. The subsequent signal flow is the same as in the first embodiment. However, the reception wave obtained in the case where the defect is present is such that the ultrasonic wave 7 is reflected by the defect and then reflected by the surface on the fluid inlet side,
This is an ultrasonic wave received by the probe 6b. Next, in the inspection of the central portion in the axial direction (region B), the transmitter 9 is connected to the probe 5a by the transmission probe switch 17, and the probe 6b is connected by the reception probe switch 18. And the receiver 10 are connected. After this, the signal flow
This is the same as the first embodiment. Finally, the region C on the fluid outlet side
Inspection of the transmitter 9 and the probe 5a by the transmission probe switch 17
The probe 6a and the receiver are connected by the receiving probe switch 18.
Connect with 10. The subsequent signal flow is the same as in the case of the inspection of the area A.

In the second embodiment shown in FIG. 3, it is not necessary to move the probe between the surface on the fluid inlet side and the surface on the outlet side, and only the operation of the switches 17 and 18 is sufficient. There is an advantage that the scanning of the stylus becomes easy.

In two embodiments, all areas are inspected using two probes. In the third embodiment described below, the regions A and C at both ends are inspected by one probe. As described above, the ultrasonic waves transmitted from the probe spread over a certain range, and the intensity of the ultrasonic waves decreases as the distance from the sound axis increases, as shown in FIG. Even when the probe receives an ultrasonic wave, the receiving sensitivity varies depending on the angle of incidence on the probe, and the distribution is the same as in FIG. This indicates that even if the defect or the receiving probe is not on the sound axis, the reflected wave from the defect can be received although the reception intensity is low. Therefore, in the third embodiment, as shown in FIG. 5 and FIG.
Inspect A and C with one probe. The inspection at the axial center is the same as in the first and second embodiments. The configuration of the apparatus is the same as that of the third embodiment except that the number of the installed probes is different (four in the second embodiment and two in the third embodiment). In the inspection of the region C, the probe 5 installed on the fluid inlet side is connected to the transmitter 9 by the transmission probe switch 17 and to the receiver 10 by the reception probe switch 18. The ultrasonic wave 7 transmitted from the probe 5 propagates in the dovetail portion and is received by the same probe 5 as the transmission. The inspection of the area A is the same as the inspection of the area C, except that the probe installed on the fluid outlet side is used.

In the third embodiment shown in FIGS. 5 and 6, only two probes are required, and there is no need to move the probe between the installation surfaces, so that the scanning of the probe is further facilitated. .

As described above, according to each embodiment of the present invention, the radial defects generated in the tab tail portion of the axial entry turbine in which the tab tail grooves are machined in the direction perpendicular to the disk surface are inspected in each of the inspection areas A, B, and C. Optimal probe placement conditions are given for each case, and the presence or absence of a radial defect can be reliably checked to confirm the soundness of the tab tail portion.

〔The invention's effect〕

According to the present invention, a radial defect generated in a tab tail portion of an axial entry turbine in which a tab tail groove is machined in a direction perpendicular to the disk surface can be reliably detected, so even in a dovetail portion having a non-necked structure, There is an effect that its soundness can be confirmed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a waveform explanatory diagram of FIG. 1, FIG. 3 is a block diagram of a second embodiment of the present invention, FIG. 4 is an intensity distribution diagram of an ultrasonic wave, FIG. 5 is an explanatory view of a third embodiment of the present invention, FIG. 6 is a right side view of FIG. 5, FIG. 7 and FIG. Explanatory diagrams, FIGS. 9 to
FIG. 12 is an explanatory diagram of the arrangement of the probes according to the present invention. 1 ... inspected object, 2 ... blade, 3 ... circumferential defect,
4 ... radial defect, 5 ... transmitting probe, 6 ... receiving probe, 7 ... ultrasonic wave, 8 ... inspection point, 9 ... transmitter, 10
... Receiver, 11 ... Received wave presence / absence detector, 12 ... Threshold setting device, 13 ... Gate setting device, 14 ... Propagation distance measuring device, 15 ... Peak value detector, 16 ... Display, 17 ... Transmitting probe switch, 18 ... Receiving probe switch.

Continuation of the front page (72) Inventor Shigeru Kajiyama 1168 Moriyama-cho, Hitachi City, Ibaraki Prefecture Energy Laboratory, Hitachi, Ltd. (56) References JP-A-1-161145 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G01N 29/00-29/28

Claims (4)

(57) [Claims] An ultrasonic wave is transmitted from a probe installed on a disk side surface of an axial entry type turbine disk to a dovetail portion of the axial entry type turbine disk.
In an ultrasonic inspection method for receiving a reflected ultrasonic wave from a dovetail portion and detecting a defect of the dovetail portion, an inspection site is divided into three regions of a fluid inlet side, a central portion, and a fluid outlet side, and a fluid inlet side region is provided. When inspecting, both the transmitting probe and the receiving probe are installed on the disk surface on the fluid outlet side to transmit and receive ultrasonic waves, and when inspecting the central area, the transmitting probe and the receiving probe are One of the receiving probes is installed on the disk surface on the fluid inlet side, and the other is installed on the disk surface on the fluid outlet side to transmit and receive ultrasonic waves.When inspecting the fluid outlet side area, the transmitting probe and the receiving probe are used. An ultrasonic inspection method, wherein both probes are placed on a disk surface on the fluid inlet side to transmit and receive ultrasonic waves. 2. An ultrasonic probe for transmitting ultrasonic waves from a probe disposed on a disk side surface of an axial entry type turbine disk to a dovetail portion of the axial entry type turbine disk, and applying a high voltage to the ultrasonic probe. A transmitter to apply, an ultrasonic probe to receive the reflected wave from the dovetail part, a receiver to amplify the received reflected wave signal, and a reflected wave signal received within a preset time gate. An ultrasonic inspection apparatus comprising means for comparing the amplitude with a threshold value to determine the presence or absence of a received wave, wherein two ultrasonic probes are arranged on both the fluid inlet side disk surface and the fluid outlet side disk surface. When inspecting the fluid inlet side area, connect both the transmitter and the receiver to the probe on the fluid outlet side disk surface, and when inspecting the central area, connect one of the transmitter and the receiver. Fluid outlet side day Connect the other end to the probe on the disk surface and the probe on the disk surface on the fluid inlet side,
In the case of inspecting the fluid outlet side area, a receiver probe switch and a transmitter probe switch that connect both the transmitter and the receiver to the probe on the fluid inlet side disk surface are provided. Ultrasonic inspection equipment. 3. The method according to claim 1, wherein when the fluid inlet side area and the fluid outlet side area are inspected, the transmission and reception of ultrasonic waves are performed by the same probe, and the central area is inspected. An ultrasonic inspection method is a method in which transmission and reception of ultrasonic waves are performed by separate probes. 4. The inspection apparatus according to claim 1, wherein the transmission probe and the reception probe are arranged in a staggered manner on the disk surface when inspecting the fluid inlet side region and the fluid outlet side region. Ultrasonic inspection method.