JP4049985B2 - Ultrasonic flaw detection apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic flaw detection apparatus and method for inspecting a defect such as a crack generated in a blade implantation portion of a rotor wheel of a steam turbine.
[0002]
[Prior art]
In a steam turbine, a strong centrifugal force acts as the rotor rotates during turbine operation, causing excessive stress and vibration in the blade implantation part where the blades of the rotor wheel are implanted, and cracks are generated there. Sometimes. For this reason, the blade wheel implantation portion of the rotor wheel is inspected by a nondestructive inspection method, particularly an ultrasonic flaw detection method, in a periodic inspection. In this inspection, the scanning of the ultrasonic probe is performed over the entire circumference of the rotor wheel to which the blades are attached.
[0003]
FIG. 10 is a perspective view showing an example of a rotor taken out from the turbine casing for inspection. A large number of blades 3 are attached to the rotor 1 in an annular row on each rotor wheel 2. The mounting portion is the blade implantation portion 5. The rotor wheel 2 in which one row of blades 3 is implanted and the rotor wheel 2 in which the other rows of blades 3 are implanted are close to each other, and the inspection by the ultrasonic probe is performed by connecting the ultrasonic probe to the rotor wheel 2. This is done in contact with the surface. Therefore, the scanning by the ultrasonic probe is blocked by the blade 3 and cannot be performed as expected.
[0004]
FIG. 11 is a partially cutaway perspective view of the rotor showing a state in which the ultrasonic probe is operated by scanning the entire circumference for ultrasonic flaw detection of the rotor wheel 2. The ultrasonic probe 4 is placed on one side surface of the rotor wheel 2, and the ultrasonic beam U is incident on the blade implanting portion 5 of the rotor wheel 2 from there. As shown in FIGS. 12 (a) and 12 (b), the ultrasonic beam U reaches the blade implantation portion 5, and if there is an axial crack 6 there, the ultrasonic beam U is cracked in the axial direction. The reflected wave reaches the ultrasonic probe 4 that has emitted the ultrasonic beam U, and is detected as a defect. This scanning is performed over the entire circumference of the rotor wheel 2 and is also performed on the opposite side in the same manner as scanning on one side.
[0005]
Further, when a reflected echo is detected, as shown in FIG. 13, in order to carry out a more detailed inspection, the transmitting ultrasonic probe 4a and the receiving ultrasonic probe 4b are arranged and again all of them are arranged. Scan over the circumference. As shown in FIGS. 14 (a) and 14 (b), the ultrasonic beam U emitted from the ultrasonic probe for transmission 4a reaches the blade implantation part 5, and is reflected by the axial crack 6, and this reflected wave. When U ′ reaches the receiving ultrasonic probe 4b, it is detected as a defect. This method is called a pitch catch method and can detect internal defects with high sensitivity.
[0006]
[Problems to be solved by the invention]
However, it is control of the flaw detection position that becomes a problem when the above-described inspection is automated. That is, when an instruction echo is detected by flaw detection, it is necessary to specify the position thereof, and accurate position control in flaw detection is a problem.
[0007]
In addition, the size and shape of the turbine rotor to be inspected differ from one another, and the number of blades varies from paragraph to paragraph. Therefore, in order to know the flaw detection position accurately, the flaw detection must be taken into account. Must be configurable to indicate position.
[0008]
In the conventional method, the effective beam path is limited to the vicinity of the first hook portion of the blade implantation portion 5 obtained by calculation. Therefore, the present situation is that the echoes appearing outside the beam path are ignored, and the flaw echoes detected by reflection inside the blade implantation part 5 may be overlooked.
[0009]
In the past, it was difficult to identify whether the detected echo was due to rust, pitting corrosion, or crack defects, and it was difficult to evaluate the size of cracks due to the experience of the inspector. It is a thing. In addition, since the A scope is used for the evaluation of the inspection, and only the peak value of the waveform is the object of the evaluation, the determination depends on the skill of the inspector, and the record remains only in the numerical value, so it is difficult to understand visually.
[0010]
Ultrasonic flaw detection of the rotor wheel 2 needs to be inspected during the regular inspection period of the steam turbine, for example, all the stages of the three to four rotors 1. However, in the current state of equipment inferior in efficiency, it is limited to the inspection period. In some cases, inspection cannot be performed at all times, and it is required to work efficiently without spending unnecessary time in scanning.
[0011]
An object of the present invention is to provide an ultrasonic flaw detection apparatus and method that can significantly improve the efficiency and accuracy of scanning including incidental operations and can maintain good detection sensitivity.
[0012]
[Means for Solving the Problems]
An ultrasonic flaw detector according to a first aspect of the present invention includes a first flaw detector provided on both side surfaces of a rotor wheel of the rotor so as to face each other with the rotor wheel interposed therebetween and to be movable in the circumferential direction along the outer peripheral portion of the rotor. A second probe holder, an ultrasonic probe that is provided in each of the first and second probe holders to detect a defect generated in a blade implantation portion of the rotor wheel, and Both the first and second probe holders are provided so as to be connected to each other at positions beyond the blades of the rotor wheel, and the first and second probe holders are provided on both sides of the rotor wheel. A link mechanism that operates in conjunction, a sensor for detecting a zero point that is provided in the first or second probe holder, and detects a reflector that is attached to a blade that is desired to be a zero point among the blades of the turbine wheel; Zero inspection A processing device that converts a scanning distance, which varies depending on the size of a rotor to be flaw detected, into radians based on a detection signal from a sensor for detection, and that processes a detection signal from the ultrasonic probe, and is processed by the processing device A display device for displaying the result of the measurement, and the processing device performs the data processing for displaying the flaw detection data obtained from the ultrasonic probe on a B scope, and then the blade of the paragraph examined in advance Based on the number of groups, the number of blades in each group, and the number of blades to which the zero point detecting reflector is attached, 360 degrees is equally divided by the total number of blades, and the group boundary position of the blades and The boundary position of the blade is calculated, and the display device displays the flaw detection data in association with the group boundary position of the blade and the boundary position of the blade .
[0013]
In the ultrasonic flaw detector according to the first aspect of the present invention, the processing device outputs a detection signal from a zero detection sensor provided in the first or second probe holder before performing the ultrasonic flaw detection. Based on this, the scanning distance that varies depending on the size of the rotor to be detected is converted to radians. Then, the detection signals from the ultrasonic probes held in the first and second probe holders are processed, and the results are displayed on the display device. Thereby, the zero point of the flaw detection data can be easily set regardless of the size of the rotor to be flaw detected.
[0015]
The ultrasonic inspection apparatus according to the invention of claim 1, further after data processing for displaying the inspection data obtained from the respective ultrasonic probes in B-scope, pre investigated blades of the paragraph The group boundary of the blades and the boundary of the blades are respectively displayed according to the number of the blades, the number of blades in each group, and the number of the blades to which the reflecting plate for detecting the zero point is attached. Since the line of the group boundary and the blade boundary is displayed on the B scope of the flaw detection result, when an instruction echo is detected, it can be easily evaluated at which position of which paragraph it is detected.
[0016]
According to a second aspect of the present invention, there is provided the ultrasonic flaw detector according to the first aspect of the invention, wherein the processing device is based on a peak position of an instruction echo on both of the B scopes of the ultrasonic probe facing each other across the rotor wheel. And evaluating the size of cracked defects.
[0017]
In the ultrasonic flaw detector according to the invention of claim 2 , in addition to the operation of the invention of claim 1, data processing for displaying flaw detection data obtained from each ultrasonic probe with a B scope is performed, and the rotor wheel is The size of the cracked defect is evaluated by examining the peak position of the indication echo in the B scope of the ultrasonic probe facing each other. When a crack defect is detected, it can be easily determined whether or not there is a size that penetrates the first hook portion in evaluating the size.
[0018]
The ultrasonic flaw detector according to the invention of claim 3 is the invention of claim 1, wherein the processing device performs data processing for displaying flaw detection data obtained from each of the ultrasonic probes on a B scope, After the effective flaw detection range is set, a circular graph having a radius at the maximum value at each scanning position is created and displayed on the display device.
[0019]
The ultrasonic inspection apparatus according to the invention of claim 3, in addition to the effect of the invention of claim 1, performs data processing for displaying the inspection data obtained from the ultrasound probe in B-scope, the effective flaw detection range After setting, the maximum value at each scanning position is displayed in a circular graph. As a result, a display is provided so that the position of the inspection paragraph can be identified.
[0020]
In the ultrasonic flaw detection method according to the invention of claim 4 , the first and second probe holders are arranged on both side surfaces of the rotor wheel of the rotor so as to face each other with the rotor wheel sandwiched therebetween, Two ultrasonic probes are provided in each of the second probe holders, and the first and second probe holders are circumferentially moved along the outer periphery of the rotor by the rotation of the rotor. In the ultrasonic flaw detection method for detecting a defect generated in the blade-implanted portion of the rotor wheel by the ultrasonic probe, a reflector is attached to a blade desired to be a zero point among the blades of the turbine wheel, A sensor for detecting a zero point for detecting a reflecting plate is provided in the first or second probe holder, and the rotor is rotated to detect the reflecting plate for the second time from the first detection by the sensor for detecting the zero point. Reflection Of the running 査 distance calculated to the detection, converting the scanning distance to radians, said after data processing for displaying the inspection data obtained from the ultrasound probe in B-scope, pre investigated the paragraph Based on the number of blade groups, the number of blades in each group, and the number of blades to which the zero point detection reflector is attached, 360 degrees is equally divided by the total number of blades, and the group boundary of the blades position and calculates the boundary position of the vane, and detects correspondence of flaw detection data from the ultrasonic probe on the running 査 distance one rotation of the rotor which is radians converted.
[0021]
In the ultrasonic flaw detection method according to the invention of claim 4 , the rotor is rotated, the reflecting plate is detected by a zero point detecting sensor that moves in the circumferential direction along the outer periphery of the rotor, and the first detection of the reflecting plate is performed. seeking running 査 distance to the detection of the second reflector, and converts the scanning distance in radians, corresponding to flaw detection data from the radians converted ultrasonic probe over running 査 distance for one rotation of the rotor Then detect.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram of an ultrasonic flaw detector according to an embodiment of the present invention.
[0023]
In FIG. 1, the ultrasonic flaw detection apparatus includes a first probe holder 11 a and a second probe holder 11 b that are disposed so as to face each other with the rotor wheel 2 sandwiched between both side surfaces of the rotor wheel 2 of the rotor 1. It has. The first probe holder 11a has two ultrasonic probes 12a and 12b that are in contact with one surface of the rotor wheel 2 for flaw detection, and the two ultrasonic probes 12a, A zero point detection sensor 27 is provided at the center of 12b.
[0024]
Further, a brush 13 and a spatula 14 are provided in combination with the two ultrasonic probes 12a and 12b. The brush 13 applies a contact medium to the surface of the rotor wheel 2 to be flaw-detected, and the spatula 14 removes the contact medium from the surface of the rotor wheel 2 after flaw detection with the ultrasonic probes 12a and 12b.
[0025]
That is, the brush 13 and the spatula 14 are arranged on the same circumference as the two ultrasonic probes, and the brush 13 is positioned at the head of the two ultrasonic probes 12a and 12b. At the tail, the brush 13 is first applied with the contact medium, and later the spatula 14 is configured to wipe it off.
[0026]
The first and second probe holders 11a and 11b are connected to each other by a link mechanism 15 in order to link their movements during scanning by the ultrasonic probes 12a and 12b on both surfaces of the rotor wheel 2. Tied. The link mechanism 15 connects both the probe holders 11a and 11b at a position beyond the tip of the blade implanted in the rotor wheel 2.
[0027]
Furthermore, although illustration is omitted, the second probe holder 11b is also arranged on the same circumference as the two ultrasonic probes 12c and 12d and the two ultrasonic probes 12c and 12d. A brush 13 and a spatula 14. In addition, a reflecting plate is attached to the blade 3 of the turbine wheel 2 that is desired to be set to the zero point, and the zero point detection sensor 27 detects the reflecting plate.
[0028]
The processing device 7 receives the detection signal from the zero point detection sensor 27 and the detection signals from the ultrasonic probes 12a to 12d, and the size of the rotor to be detected based on the detection signal from the zero point detection sensor 27. The different scanning distances are converted into radians by. In addition, the detection signals from the ultrasonic probes 12a to 12d are processed, and the flaw detection data is displayed on the display device 8 together with the detection position converted into radians.
[0029]
FIG. 2 is a front view of the vicinity of the first probe holder 11a of the ultrasonic flaw detector shown in FIG. The first probe holder 11a includes two telescoping support legs 16a and 16b each configured to be extendable, a bridge member 17 connecting the two support legs 16a and 16b, and two super It comprises an arm 18 that holds the acoustic probes 12a and 12b, and two holders 19 and 20 that hold the brush 13 and the spatula 14, respectively. A zero point detection sensor 27 is provided on the blade side of the first probe holder 11a.
[0030]
The two support legs 16 a and 16 b are each provided with a roller 22 that is guided by the convex portion 21 of the rotor 1 and rotates while sliding on the surface of the rotor 1 at the lower end thereof. Further, of the two holders 19 and 20, one holder 19 that holds the brush 13 located at the head is fixed to the front support leg 16a, while the other holder 20 that holds the spatula 14 located at the rear. Are fixed to the rear support legs 16b.
[0031]
Although not shown, the second probe holder 11b is also composed of two similar support legs, a bridge member, an arm, and two holders.
[0032]
FIG. 3 is a side view of the first probe holder portion of the ultrasonic flaw detector shown in FIG. As shown in FIG. 3, a reflector 28 is provided on the blade 3 side, and a zero point detection sensor 27 for detecting the position of the reflector 28 is provided in the first contact holder 11a. When the first and second contact holders 11a and 11b are guided by the convex portion 21 of the rotor 1 and the surface of the rotor 1 is rotated by the roller 22, the zero point is detected every rotation.
[0033]
Further, the positions of the holders 19 and 20 can be adjusted on the support legs 16a and 16b. By adjusting these positions, the brush 13 (not shown) and the spatula 14 are brought into contact with the surface of the rotor wheel 2. The state can be kept constant.
[0034]
When flaw detection is performed on the rotor wheel 2, first, based on the detection signal from the zero point detection sensor 27, the scanning distance that varies depending on the size of the flaw detection target rotor is converted to radians.
[0035]
FIG. 4 is a flowchart showing the operation in that case. First, the zero point detection sensor 27 is attached to the first probe holder 11a, and the reflecting plate 28 is pasted on the blade 3 that becomes the zero point (step 101). Next, the rotor 1 is rotated (step 102). When the reflecting plate 28 is detected for the first time by the zero point detecting sensor 27, the processing device 7 starts counting the encoder (step 103), and the reflecting plate 28 is detected for the second time by the zero point detecting sensor 27. Then, the count of the encoder is stopped (step 104). Thereby, 360 degrees of the rotor 1 is set (step 105). In this way, the 360-degree scanning distance that is different for each rotor 1 is counted by the encoder, 360 degrees is set, and the scanning distance that varies depending on the size of the rotor 1 is converted to radians.
[0036]
Here, the first probe holder 11a includes two ultrasonic probes 12a and 12b, and the second probe holder 11b also includes two ultrasonic probes 12c and 12d. These are in contact with the surface of the rotor wheel 2. These ultrasonic probes 12 a to 12 d emit an ultrasonic beam toward the blade implantation portion 5 of the rotor wheel 2 and receive, for example, a reflected wave from the crack 6 in the blade implantation portion 5. Then, the processing device 7 performs data processing for displaying the flaw detection data obtained from the ultrasonic probe 12 on the B scope, and when displaying the flaw detection data on the display device 8, the group boundary L1 and the blade boundary of the blade 3 are displayed. L2 is also displayed. Here, several blades are connected together by a connecting member and integrated, and the number of blade groups refers to the number of blade groups in this case.
[0037]
FIG. 5 is an explanatory diagram of a display example of flaw detection data displayed on the display device 8. FIG. 5 shows the flaw detection result by the B scope obtained by one ultrasonic probe 12a.
[0038]
When the group boundary L1 and the blade boundary L2 of the blade 3 are displayed together with the flaw detection data, the number of blade groups in the paragraph examined in advance, the number of blades in each group, and the reflector 28 for detecting the zero point are pasted. Based on the number of blades in the first group, 360 degrees is equally divided by the total number of blades, and the group boundary position and boundary position of the blades 3 are calculated and displayed.
[0039]
FIG. 6 is a flowchart showing the operation when displaying the group boundary position and boundary position of the blade together with the flaw detection data by the B scope.
[0040]
First, the number of blade groups in the paragraph, the number of blades in each group, and what number in the first group the number of blades 3 serving as the zero point are input (step 111). Next, the entire circumference of 300 degrees is divided by the total number of blades input in step 111, and the angle per blade is calculated (step 112). Further, the group boundary L1 and the blade boundary L2 are displayed in different colors for the B-scope flaw detection data displayed after the flaw detection (step 113). In addition, a number indicating the number of groups is displayed beside the line indicating the group boundary L1. In FIG. 5, the cases of the 8th group and the 9th group are shown.
[0041]
By performing such display, it is possible to easily know how many blades in which group the detected instruction echo is located.
[0042]
The flaw detection data in FIG. 5 shows the B scope obtained as a result of flaw detection, but it is possible to widen the beam path range by expanding the beam path range behind the conventional effective beam path range. . That is, with respect to the range of the beam path that has been the object of evaluation in the conventional inspection, the delayed echo that appears from the rotor shape is also subject to evaluation with the range being doubled backward. This makes it possible to reliably detect an instruction echo that has been missed in the past, and to detect even a small defect with high accuracy.
[0043]
Next, FIG. 7 is a flowchart showing a procedure for evaluating the size of a crack defect based on flaw detection data detected by the ultrasonic probe 12. First, it is confirmed whether or not the detected indication echo has a tail behind the beam path (step 121). If no indication echo with tailing is confirmed, it is determined that the echo is due to rust or pitting (step 122).
[0044]
On the other hand, when an instruction echo having a tail is detected behind the beam path,
It is determined whether both of the ultrasonic probes facing each other across the rotor wheel have a peak on the band-like echo indicating the first hook portion (step 123).
[0045]
When there is no peak on the belt-like echo, it is determined that the crack defect has a size that does not reach the first hook portion of the blade implantation portion as shown in FIG. 8A (step 124). ). On the other hand, if there is a peak on the belt-like echo, it is determined that there is a crack defect of a size or larger that penetrates the first hook portion of the blade implantation portion as shown in FIG. 8B (step 125). .
[0046]
That is, in the confirmation in step 121, if an instruction echo having a tail is confirmed, it indicates that a crack defect exists. Next, referring to the B scope of each ultrasonic probe, By checking whether or not there is an echo peak on the band-shaped instruction pattern indicating one hook portion, it is determined whether or not there is a crack defect larger than the size penetrating the first hook portion.
[0047]
When there is an echo peak on the band-shaped indicating pattern indicating the first hook part in both of the ultrasonic probes located between the rotor wheels, the defect indicated by the indicating echo penetrates the first hook. Or have a larger size.
[0048]
On the other hand, there is an echo peak on a band-shaped indicating pattern indicating the first hook portion on either one of the ultrasonic probes located between the rotor wheels, and the other is a band-shaped indicating the first hook portion. If there is no echo peak on the pattern, it is evaluated that the defect indicated by the indication echo does not reach the first hook. In other words, the defect is smaller than when there is an echo peak on the band-shaped indicating pattern indicating the first hook portion in both of the ultrasonic probes at the position where the rotor wheel is sandwiched.
[0049]
In this way, the flaw detection data detected by the ultrasonic probe facing each other across the rotor wheel is displayed on the B scope, and the size of the cracked defect is evaluated by examining the peak position of the indication echo. It can be easily determined whether or not there is a size penetrating the one hook portion.
[0050]
Next, when the flaw detection data obtained from the ultrasonic probe 12 is displayed on the B scope, after setting an effective flaw detection range, the maximum value at each scanning position can be displayed on a circular graph. FIG. 9 is an explanatory diagram when flaw detection data is displayed in a circular graph. FIG. 9A is an explanatory diagram of a normal display form of a B scope, and FIG. 9B is an explanatory diagram of a display form of a circular graph. .
[0051]
FIG. 9B shows the result of circular display of the flaw detection result. The B scope obtained as a result of the flaw detection is displayed as shown in FIG. 9A, the effective beam path range (effective flaw detection range) H is determined, and the maximum value within the beam path is displayed as the radius of the circular graph. . Thereby, it is possible to easily recognize at which position in the paragraph the instruction echo is detected.
[0052]
【The invention's effect】
As described above, according to the present invention, the zero point detection sensor mounted on the probe holder can be used to detect the vane as the zero point, so that the setting of 360 degrees performed before the flaw detection is performed accurately. be able to. Further, by inputting the number of blades in the paragraph in advance, it is possible to know the number of blades in the first group of the detected instruction echo. Furthermore, by displaying the flaw detection result in a circle, it is possible to easily recognize which position in the paragraph the position of the instruction echo is.
[0053]
Whether or not the peak position of the indication echo indicating the crack defect is on the belt-like echo indicating the first hook portion with reference to the B scope obtained from the ultrasonic probe at the position where the rotor wheel is sandwiched It can be determined whether or not the size of the crack defect penetrates the first hook.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an ultrasonic flaw detector according to an embodiment of the present invention.
FIG. 2 is a front view of a first probe holder part of the ultrasonic flaw detector shown in FIG.
FIG. 3 is a side view of a first probe holder portion of the ultrasonic flaw detector shown in FIG.
FIG. 4 is a flowchart showing an operation when converting a scanning distance, which varies depending on the size of a flaw detection target rotor, into radians based on a detection signal from a zero point detection sensor according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram of a display example of flaw detection data displayed on the display device according to the embodiment of the present invention.
FIG. 6 is a flowchart showing an operation when displaying the group boundary position and the boundary position of the blade together with the flaw detection data displayed on the display device according to the embodiment of the present invention.
FIG. 7 is a flowchart showing a procedure for evaluating the size of a crack defect in the embodiment of the present invention.
FIGS. 8A and 8B are explanatory diagrams of a defect in a blade implantation part, wherein FIG. 8A is an explanatory diagram of a crack defect having a size that does not lead to penetration of the first hook part of the blade implantation part, and FIG. Explanatory drawing of the crack defect more than the magnitude | size which penetrates a 1st hook part.
FIG. 9 is an explanatory diagram when flaw detection data is displayed in a circular graph in the embodiment of the present invention, FIG. 9 (a) is an explanatory diagram of a normal display form of a B scope, and FIG. 9 (b) is a circular graph; Explanatory drawing of a display form.
FIG. 10 is a perspective view showing an example of a conventional turbine rotor.
FIG. 11 is a partially cutaway perspective view of a rotor showing an example in which an ultrasonic probe is operated by full circumference scanning for ultrasonic flaw detection of a conventional rotor wheel.
FIG. 12 is an explanatory diagram of the behavior of an ultrasonic beam in a conventional scanning method.
FIG. 13 is a partially cutaway perspective view of a rotor showing another example in which an ultrasonic probe is operated by full circumference scanning for ultrasonic flaw detection of a conventional rotor wheel.
FIG. 14 is an explanatory diagram of the behavior of an ultrasonic beam in another conventional scanning method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotor, 2 ... Rotor wheel, 3 ... Blade | tip, 4 ... Ultrasonic probe, 5 ... Blade | wing implantation part, 6 ... Crack, 7 ... Processing apparatus, 8 ... Display apparatus, 11 ... Probe holder, 12 DESCRIPTION OF SYMBOLS ... Ultrasonic probe, 13 ... Brush, 14 ... Spatula, 15 ... Link mechanism, 16 ... Support leg, 17 ... Bridge material, 18 ... Arm, 19, 20 ... Holder, 21 ... Convex part, 22 ... Roller, 27 ... Zero detection sensor, 28 ... Reflector

Claims (4)

First and second probe holders provided on both side surfaces of the rotor wheel of the rotor so as to face each other across the rotor wheel and to be movable in the circumferential direction along the outer peripheral portion of the rotor; And an ultrasonic probe that is provided in each of the two probe holders and detects a defect generated in a blade implantation portion of the rotor wheel, and both the first and second probe holders. A link mechanism that is connected to each other at a position beyond the blades of the rotor wheel and that operates the first and second probe holders in conjunction with each other on both side surfaces of the rotor wheel; A sensor for detecting a zero point provided on a second probe holder for detecting a reflector attached to a blade desired to be set as a zero point among the blades of the turbine wheel, and a flaw detection based on a detection signal from the sensor for detecting the zero point Comprising a processor for data processing the detection signals from the ultrasound probe converts the different scanning distances by the size of the elephant rotor to radians, and a display device for displaying the result the processed by the processing device The processing device performs data processing for displaying the flaw detection data obtained from the ultrasonic probe on a B scope, and then the number of blade groups in the paragraph examined in advance and the number of blades in each group are examined. And the blade to which the reflector for detecting the zero point is attached is divided into 360 degrees by the total number of blades based on what number in the first group, the group boundary position of the blades and the boundary position of the blades are calculated, A display device displays the flaw detection data in association with the group boundary position of the blades and the boundary position of the blades . 2. The processing apparatus evaluates the size of a crack-like defect based on a peak position of an instruction echo in both of the B scopes of an ultrasonic probe facing each other across the rotor wheel. Ultrasonic flaw detector. The processing device performs data processing for displaying flaw detection data obtained from each of the ultrasonic probes on a B scope, sets an effective flaw detection range, and then sets a circular graph having a maximum value at each scanning position as a radius. The ultrasonic flaw detector according to claim 1, wherein the ultrasonic flaw detector is generated and displayed on the display device. First and second probe holders are arranged on both side surfaces of the rotor wheel of the rotor so as to face each other with the rotor wheel interposed therebetween, and two each of the first and second probe holders. The ultrasonic probe is provided, the first and second probe holders are moved in the circumferential direction along the outer periphery of the rotor by the rotation of the rotor, and the rotor is moved by the ultrasonic probe. In the ultrasonic flaw detection method for detecting a defect generated in a blade embedded portion of a wheel, a zero point detection sensor for detecting the reflection plate is attached to a blade desired to be a zero point among the blades of the turbine wheel. or provided in the second probe retainer obtains a run 査 distance to the detection of the reflection plate detection from the second time of the first of said reflector by the zero point detecting sensor by rotating said rotor, said Scanning distance Was converted to radians, said after data processing for displaying the inspection data obtained from the ultrasound probe in B-scope, the number of blades of the pre investigated the paragraph, the number of blades in each group and Based on the number of the first group of the blades to which the zero point detection reflector is attached, 360 degrees is equally divided by the total number of blades, and the group boundary position of the blades and the boundary position of the blades are calculated, and radians ultrasonic flaw detection method characterized by detecting a flaw data from converted the ultrasonic probe on the running 査 distance one rotation of the rotor in association.

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