JPH04274754A - Ultrasonic flaw detector for turbine rotor blade base - Google Patents

Abstract

PURPOSE:To constantly make ultrasonic waves incident constantly on a portion of a hook where defects are most likely to occur and scan to detect defects irrespective of a fluctuation in incident positions of the ultrasonic waves to the hook of a turbine rotor which occurs due to a drop of planarity due to adhesion or corrosion of an oxidation scale on a side of a disk. CONSTITUTION:An electron scanning type ultrasonic flaw detector 20 comprises an array ultrasonic probe 11 with a plurality of very small oscillators 12 linearly arranged and a gradient angle probe 4 which are placed symmetrically with respect to a radial direction of a disk 5 on the same side 6 of the disk 5 of a turbine rotor and made into contact with each other. The array ultrasonic probe 11 is used to make ultrasonic waves incident in a sector form on a hook of a blade base and scan them, and ultrasonic waves S reflected from a detect 3 in a direction of a lateral cross section of the hook 2 are received by the array ultrasonic wave probe 11. A signal controller senses magnitude of peak values of ultrasonic signals which are incident in a sector form to be reflected by the hook 2 and received by the gradient angle probe 4, compares the peak values, and automatically controls the signals to incident angles wherein ultrasonic waves incident in a sector form are freely adjusted within a predetermined angle range constantly in the vicinity of the hook.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection device for accurately detecting defects in the cross-sectional direction of a hook portion of a saddle-shaped blade implantation portion of a steam turbine rotor.

0002

[Prior Art] Conventionally, in order to detect defects that occur in the saddle-shaped blade implantation part of a steam turbine rotor, an ultrasonic probe is brought into contact with the side surface of the disc to detect flaws in the blade implantation part. equipment is used (for example, electronic scanning ultrasonic flaw detection equipment, Ultrasonic Flaw Detection Test III, P133, 1989
, Japan Nondestructive Association).

That is, as shown in FIGS. 7(a) and 7(b), in this type of flaw detection method using an ultrasonic probe, an angle probe 4 is placed on a side surface 6 of a disc 5 of a steam turbine rotor. The ultrasonic wave S reflected from the defect 3 is received by the angle probe 4, and the waveform of the ultrasonic signal converted into an electric signal is detected by the ultrasonic flaw detector 8. indicator (CR
T) 9 to identify the presence or absence of defects.

The above-mentioned flaw detection method is an example of an ultrasonic flaw detection apparatus for detecting defects occurring in the longitudinal direction of the blade implanted part 1, but the ultrasonic flaw detection apparatus shown in FIG. Ultrasonic waves are incident on the defect 3 in the cross-sectional direction from the angle probe 4 in the same way as in FIGS. Receiving the sound wave S with the angle probe 4,
The defect 3 can be detected by the ultrasonic flaw detector 8.

[0005]

[Problems to be Solved by the Invention] However, with such conventional ultrasonic flaw detection equipment, in the blade implanted portion 1 of the steam turbine rotor currently in service, the material strength decreases over time, and the As shown in a), a defect 3 in the cross-sectional direction may occur in the hook portion 2 of the blade implanted portion 1. For this reason, in ultrasonic flaw detection of the blade implanted part 1, the angle probe 4 is placed on the disc side surface 6 so that the ultrasonic wave S is incident on the hook part 2 as shown in FIG. 8(a). The contact position and the ultrasonic refraction angle θ are determined in advance, and ultrasonic flaw detection is performed. In addition, in order to detect flaws around the entire circumference of the hook portion 2 of the blade implantation portion 1, the angle probe 4 is moved and scanned in the circumferential direction on the disk side surface 6 as shown in FIG. 8(b). However, the disk side 6
is exposed to high-temperature, high-pressure steam during use of a steam turbine, so this surface may become uneven due to scale buildup, slight erosion, etc. Therefore, in the angle probe 4 in which the refraction angle θ of the ultrasonic wave is fixed, the direction of incidence of the ultrasonic wave on the hook portion is determined by the contact position on the disk side surface 6 as shown in FIG. A phenomenon occurs in which the arrival position changes from a suitable incident direction A to an unsuitable incident direction B, and the ultrasonic wave does not reach the hook portion where a defect may occur. This makes it difficult to detect defects with stable and high accuracy.

In order to compensate for the decrease in defect detection accuracy due to variations in the arrival position of ultrasonic waves, an array ultrasonic probe 11 is used as shown in FIG.
By controlling the phase of each transducer 12 of the ultrasonic wave line L, continuously changing the refraction angle θ of the ultrasonic line L, and performing fan-shaped incidence within the angular range λ, the blade implanted part 1 can be almost spread over a wide range. There is something to be detected at the same time. however,
This flaw detection method involves processing ultrasonic lines L having a large number of refraction angles θ, and the time required for flaw detection tends to be long.

An object of the present invention is to improve the angle of refraction of the ultrasonic probe at the vane implantation part of a steam turbine rotor, and in particular, to distinguish the angle of refraction of the ultrasonic probe at which the magnitude of the ultrasonic reception symbol is maximum. The object of the present invention is to improve defect detection accuracy by providing a discrimination circuit capable of specifying the position of the hook portion and automatically controlling the refraction angle so as to detect flaws in the vicinity thereof.

[0008]

[Means for Solving the Problems] In order to achieve the above object, an ultrasonic flaw detection device according to the present invention includes an array ultrasonic probe in which a plurality of micro vibrators are linearly arranged, and an angle probe. are arranged and abutted symmetrically in the direction of the disk radius on the same side of the disk of the turbine rotor, and the array ultrasonic probe injects ultrasonic waves into the hook part of the blade implantation part in a fan shape,
an electronic scanning ultrasonic flaw detector that uses an array ultrasonic probe to receive ultrasonic waves reflected from defects in the cross-sectional direction of the hook portion;
Detects the magnitude of the peak value of a group of ultrasonic signals incident in a fan shape, reflected by the hook part, and received by the angle probe, and compares the peak values to make the ultrasound signals incident in a fan shape. A signal controller is provided near the hook portion to automatically control the incident angle of the ultrasonic waves to a fan-shaped specific angle range that can be freely adjusted.

[0009]

[Operation] According to the present invention, ultrasonic waves are incident on the vane implantation part in a fan shape and scanned by an array ultrasonic probe placed in contact with the side surface of the disc of the steam turbine rotor and an electronic scanning ultrasonic flaw detector. While detecting the presence or absence of reflected waves from defects that may occur in the cross-sectional direction of the hook part, when the array ultrasonic probe is performed, the hook is detected by the angle probe placed on the same side of the disk. Identify the incident angle of the array ultrasonic probe at which the magnitude of the ultrasonic reception signal is maximum upon receiving the ultrasonic waves reflected from the hook part, and use this as a reference to ensure that the ultrasonic waves always enter the hook part. so that the refraction angle of the ultrasound waves from the array ultrasound probe is automatically controlled.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ultrasonic flaw detection apparatus of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1(a) is a block diagram of an ultrasonic flaw detection apparatus according to the present invention, and FIG. 1(b) is a partial cross-sectional view of a blade implanted portion 1 to be subjected to ultrasonic flaw detection. In FIG. 1(a), the setting data memory 21 of the electronic scanning ultrasonic flaw detector 20 contains an array ultrasonic wave for injecting the ultrasonic line L in a fan shape in the direction of the hook portion 2 according to the shape of the blade implanted portion 1. A plurality of strip-shaped micro-oscillators 12 forming the probe 11
Data such as the timing of oscillation is set and stored in advance. In addition, the multi-channel pulser 22 of the electronic scanning ultrasonic flaw detector 20 uses the central processing unit (CPU) 23 to control the trigger timing of the oscillation controller 24 based on the setting data stored in the setting data memory 21 in advance. The transmission timing of high-voltage pulses is controlled according to the signal instructions.

[0012] When performing ultrasonic flaw detection, an array ultrasonic probe 11 in which a plurality of micro vibrators are linearly arranged is used.
and the angle probe 4 are mounted on a truck 60, and are placed in contact with the same side surface 6 of the disc 5 of the steam turbine rotor so as to be symmetrical in the radial direction. At that time, the wheels 60a provided on the cart 60 are brought into contact with the rim portion 6a of the disc 5 to position it in the radial direction, and the reference points in the axial and circumferential directions of the disc 5 are determined, and then While moving the cart 60 along the rim portion 6a in the circumferential direction of the plate 5, scanning is performed by injecting ultrasonic waves in a fan shape.

When a defect 3 in the cross-sectional direction exists in the hook portion 2 of the blade implanted portion 1, the ultrasonic wave S reflected from the defect 3 is received by the array ultrasonic probe 11, and the received signal is sent to the receiver A25. The signal is amplified and detected. Receiver A2
The received signal amplified and detected in 5 is sent to the CRT signal generator 26, where it is sent to the acrylic shoe 35 in front of the transducer 12 of the array ultrasonic probe 11 as shown in FIG.
The propagation distances B1 to Bi to Bn within are corrected, and
As shown in FIG.
is displayed as a waveform. Although the fan-shaped incidence of the ultrasonic line L and the reception of ultrasonic waves by the electronic scanning ultrasonic flaw detector 20 are well-known techniques, in the embodiment of the present invention, as shown in FIG. A limited fan-shaped scan is performed on a portion of the portion 2 where the defect 3 is likely to occur.

That is, as shown in FIGS. 1(a) and 1(b), first, it is checked whether the ultrasonic waves S always reach the hook portion 2 or not. If there is a variation in the arrival position, correction is to be performed on the same side surface 6 of the array ultrasonic probe 11 and the disk 5, and at a position that is symmetrical in the radial direction of the array ultrasonic probe 11 and the disk 5. This is carried out using the bevel probe 4 and its signal controller 30, which are placed at a position where the ultrasound waves reflected according to the shape of the hook portion 2 can be received.

When there is no defect 3 in the hook part 2, the ultrasonic wave is incident on the hook part 2 from the array ultrasonic probe 11,
The ultrasonic wave S' reflected at the hook portion 2 is received by the oblique probe 4 in order to confirm the direction of refraction. A plurality of ultrasonic signals S' generated by the fan-shaped scan of the array ultrasonic probe 11 received by the angle probe 4 are transmitted to the electronic scanning ultrasonic flaw detector 2.
The timing controller 31 of the signal controller 30 receives the signal from the central processing unit 23 of 0, and the signal is received by the receiver B 32 in synchronization with the timing of incidence of the ultrasound from the array ultrasound probe 11. . The ultrasonic reception signal received by the receiver B 32 is sent to the peak comparator 34 after the magnitude of the peak value of the reception signal is detected by the peak detector 33 .

The ultrasonic signal whose peak value has been obtained by the peak comparator 34 is transmitted to the central ultrasonic line l2 among the ultrasonic lines l1, l2, l3 of the fan-shaped scan shown in FIG.
The central processing unit 23 of the electronic scanning ultrasonic flaw detector 20 is instructed to make the maximum peak value the central ultrasonic line 12.

Next, regarding the operation of the signal controller 30 shown in FIG. 1(a), as shown in FIG.
1 to perform fan-shaped scanning using three ultrasonic lines l1, l2, l3 having refraction angles θ1, θ2, and θ3 will be described using the block diagram of FIG.

As shown in FIG. 5, first, the peak detector 33 of the signal generator 30 shown in FIG.
The magnitudes of the peak values of ultrasonic waves P1 and P2 of l2 and l3
, P3 are detected as shown in Fig. 5(a), respectively.
As shown in (b), the peak comparator 34 compares the magnitudes P1, P2, and P3 of these peak values. If P2>P
1, P3, the ultrasonic waves are incident on the ultrasonic lines with refraction angles θ1, θ2, θ3, and P1>P2, P3
If so, use electronic scanning ultrasound to perform fan-shaped operation on the ultrasound lines l1-1, l2-1, l3-1, or if P3 > P1, P2, use the ultrasound lines l3+1, l2+1, l1+1. An instruction is given to the central processing unit 23 of the flaw detector 20. As a result, the central processing unit 2
3, ultrasonic lines l1, l2, .
lx can be controlled.

Therefore, according to this embodiment, the steam turbine rotor blade embedded portion 1 due to the change in the refraction angle θ of the ultrasonic wave
It is possible to suppress fluctuations in the direction of incidence of ultrasonic waves on the hook part 2, and to make the ultrasonic waves accurately enter the desired position of the hook part 2.

Next, another embodiment of the ultrasonic flaw detection apparatus of the present invention will be described.

As shown in FIG. 6, the ultrasonic flaw detection apparatus according to this embodiment includes a setting data memory 21, multi-channel pulsers 54 and 55, a central processing unit 23, and an oscillation controller 2.
4. Electronic scanning ultrasonic flaw detection device 20 consisting of receivers 57, 58, CRT signal generator 26, channel switch 56 and display 27; signal control consisting of timing controller 31, peak detector 33 and peak comparator 34; A container 30 is provided.

[0022] In the ultrasonic flaw detection device configured as described above,
The array ultrasonic probes 50 and 51 are installed in advance on the side surface 6 of the disk 5 so that the ultrasonic waves S are incident on the hook portion 2 of the blade implanted portion 1. However, when performing flaw detection by scanning the array ultrasonic probes 50 and 51 on the side surface 6 of the disk, the incident direction of the ultrasonic waves may shift. In order to correct this in the same way as in the previous embodiment and to always propagate the ultrasonic waves in the direction of the hook portion 2, in this embodiment, a group of pulses is applied to one of the array ultrasonic probes 50 from the multichannel pulser B55. generates an ultrasonic wave, propagates it, and receives the ultrasonic wave reflected by the hook portion 2 by the receiver 57 via the array ultrasonic probe 51. Then, the received signals are synchronized by the timing controller 31 of the signal controller 30,
After each peak value of the ultrasonic line is detected by the peak detector 33, these peak values are compared as in the previous embodiment. Then, the peak value is processed by a peak comparator 33 that discriminates whether the maximum peak value exists in the central ultrasonic line of the incident fan-shaped ultrasonic wave, and the result is transmitted to the central processing unit 23. The central processing unit 23 is a peak comparator 3
Based on the processing result of step 3, the direction of incidence of the fan-shaped ultrasound propagated from the array ultrasound probes 50 and 51 is adjusted so that it hits the hook portion 2.

According to this embodiment, even when the two array ultrasonic probes 50 and 51 are used to detect defects 3 occurring in the transverse direction of the blade implantation portion 1 of the steam turbine rotor, This has the effect that flaw detection can be performed accurately while always injecting ultrasonic waves into the hook portion 2 where defects are most likely to occur.

[0024]

[Effects of the Invention] Since the ultrasonic flaw detection device of the present invention is configured as described above, it is possible to detect defects occurring in the cross-sectional direction of the blade-embedded portion of the turbine rotor by detecting defects on the side surface of the disk of the turbine rotor. Even if there is a change in the incident position of the ultrasonic wave on the hook portion due to deterioration of its flatness due to adhesion and erosion of oxide scale, the change in the refraction angle of the ultrasonic wave can be automatically controlled. Therefore, the ultrasonic wave is always applied to and scanned the hook part of the blade implantation part where defects are most likely to occur, and the defect can be detected accurately and quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic flaw detection apparatus of the present invention.

FIG. 2 is an explanatory diagram of beam distance correction within the acrylic shoe of the array ultrasound probe.

FIG. 3 is a diagram showing an example of how defects are displayed on a display by an embodiment of the ultrasonic flaw detection device of the present invention.

FIG. 4 is an explanatory diagram of the ultrasonic line fluctuation correction effect according to an embodiment of the ultrasonic flaw detection apparatus of the present invention.

FIG. 5 is a block diagram illustrating an ultrasonic line variation correction function in an embodiment of the ultrasonic flaw detection apparatus of the present invention.

FIG. 6 is a block diagram showing another embodiment of the ultrasonic flaw detection device of the present invention.

FIG. 7 is an explanatory diagram of a conventional ultrasonic flaw detection method.

FIG. 8 is an explanatory diagram of fluctuations in the direction of incidence of ultrasonic waves according to a conventional technique.

FIG. 9 is an explanatory diagram of a conventional technique using an oblique flaw detector.

FIG. 10 is an explanatory diagram of a conventional technique using an array ultrasound probe.

[Explanation of symbols]

1. Feather implantation part 2 Hook part 3 Defects 4 Angle angle probe 5 Disk 6 Disc side 8 Ultrasonic flaw detector 9 Display 11 Array ultrasonic probe 12 Oscillator 20 Electronic scanning ultrasonic flaw detector 22 Multi-channel pulsar 23 Central processing unit 24 Oscillation controller 25 Receiver A 26 CRT signal generator 27 Display 30 Signal controller 31 Timing controller 32 Receiver B 33 Peak detector 34 Peak comparator 50 Array ultrasound probe A 51 Array ultrasound probe B 54 Multi-channel pulser A 55 Multi-channel pulser B 56 Channel switcher 57 Receiver I 58 Receiver II

Claims (1)

[Claims] Claim 1: In a turbine rotor having a plurality of saddle-shaped blade implants disposed in the circumferential direction, an array ultrasonic probe and an angle probe each having a plurality of micro-oscillators arranged in a linear manner are used. are arranged and abutted on the same side surface of the disk of the turbine rotor so as to be symmetrical in the radial direction, and the array ultrasonic probe injects ultrasonic waves into the hook part of the blade implantation part in a fan shape, and the hook part An electronic scanning ultrasonic flaw detector uses an array ultrasonic probe to receive ultrasonic waves reflected from defects in the cross-sectional direction of By detecting the magnitude of the peak value of the ultrasonic signal group and comparing the peak values, the ultrasonic group incident in a fan shape can always be adjusted to a predetermined fan-shaped angle range near the hook part. An ultrasonic flaw detection device comprising: a signal controller that automatically controls the incident angle.