JP4215934B2 - Ultrasonic flaw detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic flaw detection equipment to detect using ultrasound defects occurring in the subject, in particular, occur to the outer peripheral edge limited such threaded portion of the bolt as the subject and, or it relates to the ultrasonic flaw detection equipment capable of detecting a defect generated inclined in a direction deflected outgoing direction of the ultrasonic waves.
[0002]
[Prior art]
A screw part such as a bolt that combines and integrates split surfaces such as a gas turbine casing that is divided into two parts is subject to great stress and may cause cracking. It is essential to prevent this.
As this crack detection means, an ultrasonic flaw detection method that uses an ultrasonic flaw detection apparatus to which an ultrasonic flaw detection sensor (hereinafter referred to as a UT sensor) is applied has been known.
[0003]
This ultrasonic flaw detector introduces ultrasonic waves into the subject such as bolts, and detects the reflection echo that is bounced from the defects (cracks) occurring inside, thereby detecting the presence of defects in the subject. Is detected and detected.
That is, in the conventional ultrasonic flaw detector, as shown in FIG. 5, an ultrasonic flaw detection sensor 102 is installed on an end surface 101a of a bolt 101 as a subject, and the bolt 101 is parallel to the axial direction of the bolt 101 from the bolt end surface 101a. The ultrasonic wave 103 is emitted inside the.
[0004]
If the ultrasonic wave 103 emitted from the UT sensor 102 into the bolt 101 does not have a crack 105 that forms a discontinuous structure in the bolt 101, the ultrasonic wave 103 is not reflected and the crack 105 in the bolt 101 is generated. It can be detected that there is no.
[0005]
However, when there is a discontinuous structure due to, for example, a crack 105 generated from the screw portion 101b of the bolt 101 in the path of the ultrasonic wave 103 emitted from the UT sensor 102 as shown in FIG. The ultrasonic wave 103 emitted inside 101 is reflected by the crack 105.
The reflected wave (reflected echo) 106 that is reflected is detected by the UT sensor 102 when the crack 105 is generated in a plane perpendicular to the emission direction of the ultrasonic wave 103, and the time between the emission time and the incident time. The difference Δt ′ is measured, and the defect such as the crack 105 generated in the bolt 101 and its position are detected by the product calculation Δt ′ × v from the time difference Δt ′ and the known sound velocity v in the bolt. be able to.
[0006]
In the ultrasonic flaw detection method using the conventional ultrasonic flaw detector, the UT sensor 101 that generates a so-called vertical beam that emits the ultrasonic wave 103 to coincide with the axial direction of the bolt 101 is used as the UT sensor 102. It was used.
For this reason, as shown in FIG. 6A, when the crack 105 generated from the screw portion 101b of the bolt 101 remains in the depth range of the screw thread or as shown in FIG. Even in the case where it occurs inside the bolt 101 that is greater than the depth of the mountain, when the direction of the crack 105 is deflected from the direction orthogonal to the transmission direction (vertical beam direction) of the ultrasonic wave 103, The reflected wave 106 reflected by these cracks 105 may not be obtained by the UT sensor 102, or the reflected wave 106 may not return to the sensor 102 and cannot be detected by the UT sensor 102, making it difficult to detect defects such as the crack 105. It was.
[0007]
Further, since a UT sensor 102 that generates a vertical beam is used, even if a defect such as a crack 105 does not occur in the bolt 101, the crack 105 as shown in FIG. Also, the reflected echo 106 is not incident on the UT sensor 102, and there is a problem that it is impossible to distinguish whether or not a defect such as a crack 105 has occurred.
[0008]
[Problems to be solved by the invention]
The present invention eliminates the problems of the conventional ultrasonic flaw detection apparatus described above and the ultrasonic flaw detection technique performed by using this apparatus, so that the microcrack stays within the thread height and the object within the object. and to provide an ultrasonic flaw detection equipment capable of detecting cracks occurring in the state inclined from the vertical plane which is perpendicular to the direction of the ultrasonic wave emitted within.
[0009]
[Means for Solving the Problems]
For this reason, the ultrasonic flaw detector of the present invention is the following means.
[0010]
(1) An annular gear provided at the upper end of a support body that surrounds and arranges the outer periphery of the subject for detecting a defect occurring inside, and at the upper end is provided to surround the entire outer periphery of the subject. An arranged fixing jig was provided.
The annular gear is arranged on the fixing jig by arranging a magnet or the like between the fixing jig and the gear, and the fixing jig and the gear are not fixed. It is preferable that the magnetic attraction is arranged at a predetermined position so that it can be removed freely without using a removal tool or the like after the defect is detected, and the working time can be shortened.
[0011]
(2) An encoder that is provided with a gap between the fixing jig and the upper and outer circumferences of the subject, and is rotated along the outer circumference of the subject and meshes with a gear provided on the fixing jig and rotates. An encoder that detects the rotation angle around the outer periphery of the subject from the rotation of the gear and the encoder gear, and a slide on the sensor guide plate at the rotation angle position around the outer periphery of the subject, and is movable in the radial direction above the subject. Can be placed at any rotation angle position of the subject, can emit ultrasonic waves with a refraction angle deflected from the axial direction into the subject, such as screw grooves formed on the outer periphery of the subject perpendicular to the direction of ultrasonic emission Reflected echoes reflected from the vertical plane inside the subject's outer periphery can be received in the same direction as the launch direction, and reflected echoes from defects occurring inside the subject that are not reflected in the same direction as the launch direction of the ultrasonic wave Cannot receive Conventional UT sensor to the corresponding beveled UT sensor was a sensor guide plate equipped respectively.
[0012]
As the oblique angle UT sensor, the emitted ultrasonic wave is perpendicular to any of the vertical surfaces formed in the height direction inside the subject outer periphery, such as the tooth surface of the screw groove formed inside the subject outer periphery. It is preferable to use a plurality of ultrasonic waves having different refraction angles from the axial direction of the emitted ultrasonic waves so that the incident ultrasonic waves can be incident on the axis.
Further, a driving device that controls and rotates the sensor guide plate around the outer periphery of the subject and a driving device that controls and drives the oblique UT sensor in the radial direction of the subject and slides and moves the sensor guide plate on the sensor guide plate , respectively. It is preferable to provide them.
[0013]
(A) This enables not only detection of defects such as cracks occurring in the center of the subject due to emission of ultrasonic waves parallel to the subject axis to the inside of the subject as in the case of a conventional UT sensor, Detection of defects such as cracks occurring in the outer periphery of a subject in which a screw groove or the like is engraved is performed by selecting a refraction angle from a plurality of bevel angle UT sensors having different refraction angles, a bevel angle UT sensor Depending on the combination of the amount of movement of the subject in the upper radial direction and the setting of an arbitrary angle of the oblique angle UT sensor based on the amount of rotation of the sensor guide plate around the subject, various angles such as the tooth surface angle of the thread groove can be obtained. Even if it is formed, or even if it is formed at a predetermined angle, it is formed on the outer periphery of the subject such as the tooth surface of the screw groove even when the incident angle changes due to the difference in the height direction where the screw groove is arranged. Ultrasound from inside to vertical surface Can be incident perpendicularly, the reflection echo from inside the subject is not a defect has occurred will be able to be incident at an oblique angle UT sensor.
[0014]
Therefore, even if the defect such as a crack occurring inside the subject is a minute defect of the depth of the screw groove starting from the tooth surface of the screw groove, the total height of the subject is surely It can be detected over the entire circumference.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an ultrasonic flaw detector according to the present invention will be described with reference to the drawings.
[0031]
In the figure, members that are the same as or similar to those shown in FIGS. 5 and 6 are given the same reference numerals, and descriptions thereof are omitted.
FIG. 1 is a diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention. FIG. 1 (a) is a plan view, FIG. 1 (b) is a side view, and FIG. 1 (c) is FIG. FIG.
[0032]
As shown in the figure, the ultrasonic flaw detector according to the present embodiment has an oblique angle UT arranged in the radial direction of the bolt end surface 101a in order to make an oblique ultrasonic wave (hereinafter referred to as an ultrasonic beam) 113 enter the bolt 101. A sensor guide plate 114 for moving and scanning the sensor 110 in the radial direction 111 of the bolt end surface 101a and the circumferential direction 112 of the outer periphery of the side surface, and holding the sensor guide plate 114 above the bolt 101, It consists of a fixing jig 118 having a gear 117 for transmitting a rotation amount arranged at the upper end.
[0033]
In addition, the sensor guide plate 114 and the fixing jig 118 rotate the sensor guide plate 114 in the circumferential direction 112, cause the oblique angle UT sensor 110 to scan the bolt 101 in the circumferential direction 112, and the bolt 101 in the rotational position. Are separated from each other from the necessity of scanning in the radial direction.
That is, the fixing jig 118 is concentric with the nut 120 via the magnet 121 at the upper end of the nut 120 screwed into the threaded portion 104 engraved on the outer peripheral surface of the bolt 101. In addition, an annular gear 117 is also provided on the upper end of the fixing jig 118. The annular gear 117 is also arranged concentrically with the nut 120 and has teeth arranged on the outer peripheral surface.
[0034]
The sensor guide plate 114 is disposed in the radial direction 111 of the bolt end surface 101a, and detects the amount of movement in the circumferential direction 112 of the oblique UT sensor 110 that rotates in the circumferential direction 112 as the sensor guide plate 114 rotates. In addition to the engagement between the encoder gear 116 and the gear 117, the sensor guide plate 114 and the fixing jig 118 are separated from each other. .
[0035]
Further, the encoder 115 is arranged above the sensor guide plate 114 on the support base, which is arranged in the radial direction of the bolt end surface 101 and fixed to the upper end of the sensor guide plate 114 in the same manner as the oblique angle UT sensor 110 provided on the sensor guide plate 114. The encoder gear 116 meshed with the gear 117 is rotated along the outer periphery of the bolt 101 to move the sensor guide plate 114 in the circumferential direction, whereby the sensor guide plate 114 is rotated. Can be scanned in the circumferential direction 112.
In order to detect the scanning amount of the oblique angle UT sensor 110, the encoder 115 is equipped with a circumferential length device 119 for displaying the length of the signal from the encoder 115.
[0036]
Further, in the scanning in the radial direction 111 of the oblique angle UT sensor 110, the radius of the bolt end surface 101a that rotates along the outer periphery of the bolt 101 by rotating the encoder gear meshed with the gear 117 is fixed to the sensor guide plate 114. The oblique angle UT sensor 110 is slid in the radial direction 111 on the guide plate disposed in the direction 111, thereby scanning the radial direction 111 at the arbitrary circumferential direction 112 position of the bolt 101.
[0037]
That is, a UT sensor that emits ultrasonic waves or receives reflected waves to detect defects such as the crack 105 generated in the bolt 101 is a vertical beam like the UT sensor 102 shown in FIGS. For example, an oblique angle UT sensor 110 that emits ultrasonic waves by deflecting 30 °, 45 °, 60 °, or 75 ° from the vertical beam direction or receives reflected waves is used. I am doing so.
[0038]
Therefore, in the present embodiment in which the oblique angle UT sensor 110 is used, the oblique angle UT sensor 110 that emits ultrasonic waves having a refraction angle that is deflected by a specific angle and the radial direction 111 of the oblique angle UT sensor 110. By the combination with the position, the angle of the ultrasonic beam 113 emitted toward the inside of the bolt 101 is engraved on the outer periphery of the bolt 101 and provided opposite to the direction in which the ultrasonic beam 113 is transmitted. The ultrasonic beam 113 is emitted at an angle at which the ultrasonic beam 113 is incident on the tooth surface (hereinafter referred to as an opposing tooth surface) 122 of the screw portion 101b substantially perpendicularly.
[0039]
The ultrasonic flaw detection apparatus according to the present embodiment has the above-described configuration, and the oblique angle UT sensor 110 emits an ultrasonic beam 113 that is substantially perpendicularly incident on the tooth surface facing the screw portion 101b. Therefore, the reflected echo 123 from the opposing tooth surface 122 of the screw portion 101b can be detected. From the state of the reflected echo 123, the crack 105 occurring in the portion where the screw portion 101b of the bolt 101 is not provided is of course. In other words, it is possible to detect the crack 105 occurring in the portion of the screw portion 101b that is not higher than the thread height.
[0040]
That is, as shown in FIG. 2, when the oblique angle UT sensor 110 is disposed at the healthy portion position 124 a in the circumferential direction 112 and the radial direction 111 in which the ultrasonic beam 113 can be emitted toward the opposed tooth surface 122 without a crack, A reflection echo peak 123a as shown in FIG. 2C is obtained from the reflection echo 123 from the opposing tooth surface 122 of each screw portion 104.
[0041]
On the other hand, when the oblique angle UT sensor 110 is arranged at the unhealthy portion position 124b in the circumferential direction 112 and the radial direction 111 in which the ultrasonic beam 113 is emitted toward the opposing tooth surface 122 where the crack 105 is generated. Since the reflected echo 123 is not received by the sensor from the opposing tooth surface 122 of the screw portion 104 where the crack 105 is generated, the reflected echo peak 123a disappears as shown in FIG. Compared to 123a or smaller.
[0042]
By applying this principle and paying attention to the waveform of the reflected echo peak 123a, it is possible to detect the presence or absence of a defect occurring inside the bolt 101 of the crack 105.
Further, by moving the oblique angle UT sensor 110 in the radial direction 111 and scanning, it is possible to detect flaws in the threaded portion in which the position of the bolt 101 in the height direction is changed.
[0043]
Further, this method is an oblique angle method, and the direction of the reflected echo 123 is deflected by the ultrasonic wave incident on the screw portion 101b and the defect such as the crack 105, and the reception portion of the oblique angle UT sensor 110 Since it is not received, even if the crack 105 direction is tilted in any direction, and even if the defect portion such as the crack 105 is a small crack that is smaller than the thread of the screw portion 101b and stays in the screw, This is an effective flaw detection technique. Further, in order to measure the length of the obtained defect in the circumferential direction 112, it is necessary to scan the circumferential direction 112 while the oblique angle UT sensor 110 is directed in the radial direction 111. This makes scanning difficult.
On the other hand, these scans can be easily executed by using the sensor guide plate 114.
[0044]
The sensor guide plate 114 is attached to the bolt 101, but has a separation structure from the fixing jig 118. Therefore, the sensor guide plate 114 rotates in accordance with the scan in the circumferential direction 112 by the oblique angle UT sensor 110. Since the encoder gear 116 rotates along the gear 117 of the fixing jig 118 as it rotates, the encoder 115 can detect the scanning amount in the circumferential direction 112 and displays the signal from the encoder 115 in length. The circumferential length display device 119 can easily measure the length 112 of the detected defect in the circumferential direction.
[0045]
Next, FIG. 3 is a figure which shows the 1st reference example of the ultrasonic flaw detector of this invention, Fig.3 (a) is a top view, FIG.3 (b) is a side view.
As shown in the figure, in the ultrasonic flaw detector of the present reference example , a bolt 101 is applied by applying a phased array UT sensor 130 instead of the oblique angle UT sensor 110 used in the first embodiment described above. A defect such as a crack 105 of the screw portion 101b is detected.
[0046]
The phased array UT sensor 130 performs electronic scanning by electronically scanning ultrasonic waves by controlling the phase (phase) of the sensor groups arranged in an array. The independently driveable ultrasonic waves in the sensor. By adjusting the driving time (delay time) of the vibrator, it is possible to transmit ultrasonic waves in a desired direction, that is, a direction deflected from the axial direction of the phased array UT sensor 130, that is, a so-called refraction angle θ.
[0047]
Therefore, by arranging the phased array UT sensor 130 at the center of the bolt end surface 101a and adjusting the delay time, the ultrasonic wave 103 incident on the opposing tooth surface 122 of the screw portion 101b is converted into, for example, the screw groove teeth on the outer peripheral surface of the bolt 101. It is possible to make the angle incident substantially perpendicularly to the surface or the like, and a reflection echo 123 similar to that obtained when the oblique angle UT sensor 110 is scanned in the radial direction of the bolt 101 can be obtained.
[0048]
Furthermore, since the transmission direction of the ultrasonic waves can be controlled by changing the delay time, the refraction angle θ in which the direction of the reflected echo 123 from the opposing tooth surface 122 deviates greatly from the direction of the ultrasonic wave 103 incident on the opposing tooth surface 122. When control is performed to increase, ultrasonic beam scanning in the axial direction 133 of the shallow position screw portion 131 is performed, and the reflected echo 123 from the opposing tooth surface 122 is shown in FIGS. 3 (c) and 3 (d). When the control is performed so that the refraction angle θ is small, the ultrasonic beam scan in the axial direction 133 of the deep screw portion 132 is performed, and the reflected echo 123 from the opposing tooth surface 122 is shown in FIG. Detection is performed as shown in FIG.
[0049]
Further, when there is a defect such as a crack 105, the reflected echo 123 from the opposing tooth surface 122 where the crack 105 exists is a shallow position screw portion 131, a deep position, as in the oblique angle UT sensor 110 in the first embodiment. Regardless of the screw part 132, it disappears as shown in FIGS. 3D and 3F, so that the presence or absence of a defect can be detected.
As described above, when the phased array UT sensor 130 is applied to detect a defect occurring in the subject, the ultrasonic beam can be scanned in the axial direction 133 by changing the refraction angle θ147. Therefore, the flaw detection in the height direction of the screw portion 101b can be performed without moving the phased array UT sensor 130 for scanning.
[0050]
The angle range in which the refraction angle θ147 can be varied is limited to the range in which the reflected echo 123 is received by the phased array UT sensor 130.
However, flaw detection in the height direction of the screw portion 101b can be performed without limitation by applying linear array scanning.
[0051]
Furthermore, in the case of the phased array UT sensor 130 in which ultrasonic transducers are arranged in a matrix, the ultrasonic beam can be scanned in the circumferential direction 112 by controlling the delay time. Without scanning, it is possible to carry out the flaw detection on the entire periphery.
[0052]
Next, FIG. 4 is a figure which shows the 2nd reference example of the ultrasonic flaw detector of this invention, FIG. 4 (a) is a top view, FIG.4 (b) and FIG.4 (c) are side views.
As shown in the figure, in the ultrasonic flaw detector of this reference example , a small refraction angle θ that does not receive the reflection echo 123 from the screw portion 101b, instead of the oblique angle UT sensor 110 used in the first embodiment described above. A converging-type oblique angle sensor 140 having the following is applied to detect a defect such as a crack 105 of the screw portion 101b of the bolt 101.
[0053]
Since the converging oblique angle sensor 140 emits a focused focused ultrasonic beam 141, the converging oblique angle sensor 140 is generally used as a technique for detecting the reflected echo 123 from the tip of a defect such as the crack 105.
The converging-type oblique angle sensor 140 is disposed on the bolt end surface 101a, and the refraction angle θ is a very shallow angle at which the converging-type oblique angle sensor 140 does not receive the reflection echo 123 from the opposing tooth surface 122 of the screw portion 101b. It is said.
[0054]
Therefore, as shown in FIG. 4C, the reflection echo 123 is not received by the converging-type oblique angle sensor 140 unless there is a defect such as a crack 105 in the bolt 101. The generated defect tip reflection echo 142 is received, and the presence or absence of the crack 105 can be detected based on the presence or absence of the defect tip reflection echo 142.
Further, the defect portion tip reflection echo 142 is from the tip portion of the crack 105 or the like and does not depend on the inclination of the defect such as the crack 105.
[0055]
Therefore, by applying the converging-type oblique angle sensor 140, even an inclined crack 105 can be detected.
Further, the defect depth reflection echo 142 from the detected tip of the crack 105 or the like and the distance Y144 between the screw bottom 143 and the central position of the converging-type oblique angle sensor 140 measured in advance are used to calculate the defect depth according to the following equation. T145 can be identified.
[0056]
T = Y-W Cos θ
Here, T is the defect depth 145 from the screw bottom 143, Y is the Y distance 144, W is the beam path length 146, and θ is the refraction angle 147.
[0057]
In this way, by applying the so-called end echo method, which uses the converging-type oblique angle sensor 140 and uses the defect tip reflection echo 142 generated from the end of the crack 105 or the like, the inclined crack 105 or the like is applied. , And the distance l between the tip of the defect such as the crack 105 and the center position of the converging-type oblique angle sensor 140 and the defect depth T145 from the screw bottom 143 can be identified.
[0058]
【The invention's effect】
As described above, according to the ultrasonic flaw detection apparatus of the present invention, the annular shape provided at the upper end of the support disposed on the outer periphery of the subject for detecting an internal defect and surrounding the outer periphery of the subject. The fixed jig with the upper gear arranged at the upper end, the fixed jig and the encoder gear that rotates with the gear and the upper outer periphery of the object, and the encoder that detects the rotation angle around the object from the encoder gear rotation , Can slide in the radial direction of the subject by sliding on the sensor guide plate at the rotational position, emits ultrasonic waves with a predetermined refraction angle into the subject, and is provided perpendicular to the firing direction on the outer periphery of the subject A sensor guide plate having an oblique angle UT sensor that receives only the reflected echo reflected from the surface and does not receive the reflected echo from the defect portion is provided.
[0059]
As a result, it is possible to detect a defect in the center of the subject by emitting ultrasonic waves parallel to the subject axis, and to detect a defect occurring on the outer periphery of the subject by selecting an oblique UT sensor having a different refraction angle, Even when the angle of the vertical plane is different or the incident angle changes due to the difference in the height direction even if the angle of the vertical plane is different by the combination of the amount of movement that slides and moves in the upper radial direction of the specimen, the amount of rotation around the subject, Ultrasonic waves can be incident perpendicularly to the vertical surface of the subject outer periphery, and even a minute defect in the subject outer periphery can be detected over the entire height and circumference of the subject.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention, FIG. 1 (a) is a plan view, FIG. 1 (b) is a cross-sectional view, and FIG. 1 (c) is FIG. Detailed view of part A shown in FIG.
2 is a diagram showing an ultrasonic flaw detection method according to the first embodiment of the present invention shown in FIG. 1, in which FIG. 2 (a) is a plan view, FIG. 2 (b) is a cross-sectional view, and FIG. FIG. 2 is a diagram showing a peak reflection echo from the inside of a subject without a defect, FIG. 2D is a diagram showing a peak reflection echo from the inside of a subject with a defect,
3A and 3B are diagrams showing a first reference example of the ultrasonic flaw detector of the present invention, in which FIG. 3A is a plan view, FIG. 3B is a cross-sectional view, and FIG. FIG. 3D is a diagram showing a peak reflection echo from the inside of the subject without defect, FIG. 3D is a diagram showing a peak reflection echo from the inside of the subject having defect when the refraction angle is large, and FIG. FIG. 3 (f) is a diagram showing a peak reflection echo from the inside of a subject having no defect when the refraction angle is small, and FIG. 3 (f) is a diagram showing a peak reflection echo from the inside of the subject having a defect when the refraction angle is small;
FIGS. 4A and 4B are diagrams showing a second reference example of the ultrasonic flaw detector according to the present invention, FIG. 4A is a plan view, and FIG. 4B is an ultrasonic flaw detection of a subject having no defect. FIG. 4C is a cross-sectional view when performing ultrasonic flaw detection on a defective object, and FIG. 4D is a diagram showing a reflection echo from the inside of the object without a defect. 4 (e) is a diagram showing a peak reflection echo from the inside of a defective subject,
5A and 5B are diagrams showing a conventional ultrasonic flaw detector, in which FIG. 5A is a plan view, and FIG. 5B is a diagram in which a defective portion is generated up to the center of a subject, and a reflected echo from the defective portion is UT. Cross section when reaching the sensor,
FIG. 6 shows a diagram in which ultrasonic flaw detection is performed by the conventional ultrasonic flaw detector shown in FIG. 5, and FIG. 6 (a) shows that a defect occurs on the outer periphery of the subject and the defect cannot be detected. FIG. 6 (b) is a cross-sectional view for explaining this, even though the defect portion has occurred up to the center of the subject, so that the defect portion cannot be detected because the defect portion is inclined. FIG.
[Explanation of symbols]
101 Bolt 101a Bolt end face 101b (Bolt) Screw part 102 UT sensor 103 Ultrasonic wave 104 Screw part 105 Crack 106 Reflected wave 110 Oblique angle UT sensor 111 Radial direction 112 Circumferential direction 113 (Inclined angle ultrasonic wave) Ultrasonic beam 114 Sensor guide Plate 115 Encoder 116 Encoder gear 117 Gear 118 Fixing jig 119 Circumferential length display device 120 Nut 121 Magnet 122 Opposing tooth surface 123 Reflected echo 123a Reflected echo peak 124a Healthy part position 124b Unhealthy part position 130 Phased array UT sensor 131 Shallow Position screw part 132 Deep position screw part 133 Axial direction 140 Focusing type oblique angle sensor 141 Focusing ultrasonic beam 142 Defect tip reflection echo 143 Screw bottom 144 Distance Y
145 Defect depth T from screw bottom
146 Beam path W
147 Refraction angle θ

Claims (1)

An ultrasonic wave is emitted from the UT sensor placed on the upper end of the subject to the inside of the subject, a reflection echo from a defect inside the subject is received, and a defect generated inside the subject is detected by this received signal. In the ultrasonic flaw detector, a fixing jig provided at an upper end of a support body that is disposed so as to surround the outer periphery of the subject, and an annular gear is disposed at the upper end so as to surround the outer periphery of the subject; A fixing guide and a gap are provided so as to surround the upper outer periphery of the subject, and the sensor guide plate rotates along the upper outer periphery. The sensor guide plate meshes with the gear to encoder gear which rotates the periphery of the object, the upper side of the sensor guide plate wherein the encoder and the subject to slide the sensor guide plate on detecting the rotation angle of the outer circumference around the subject by the rotation of the encoder wheel As the UT sensor that is movable in the radial direction, emits the ultrasonic wave deflected from the axial direction into the subject, and can detect the reflected echo reflected by the vertical surface formed on the inner periphery of the subject. An ultrasonic flaw detector provided with a bevel angle UT sensor .

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