JP2020030070A - Ultrasonic flaw detection method and flaw detector - Google Patents

Abstract

To provide an ultrasonic flaw detection method by the TOFD method capable of detecting a crack inside a flaw detection target even in a case where the arrangement of a transmission-side probe and a reception-side probe is restricted.SOLUTION: An ultrasonic flaw detection method according to at least one embodiment includes the steps of: arranging the transmission-side probe configured to propagate ultrasonic waves of a longitudinal wave in a flaw detection target at a fixed refraction angle of 30 degrees or more and 45 degrees or less and the reception-side probe configured to receive an ultrasonic wave from the transmission-side probe in an extending direction of a groove formed in the flaw detection target member; and performing an ultrasonic flaw detection by the TOFD method using the transmission-side probe and the reception-side probe arranged in the extending direction of the groove.SELECTED DRAWING: Figure 15

Description

  The present disclosure relates to an ultrasonic inspection method and an inspection apparatus.

By performing the ultrasonic inspection by the TOFD method using the transmitting probe and the receiving probe arranged on the surface of the flaw detection target, a crack inside the flaw detection target can be detected. In the ultrasonic testing by the TOFD method, a position of a crack can be measured by receiving a diffracted wave from a tip of a crack inside a testing object (see Patent Document 1).
Patent Document 1 discloses that in the ultrasonic flaw detection by the TOFD method, the incident angle (refraction angle) of the ultrasonic wave in the flaw detection target is generally set to 45 to 55 degrees.
In the ultrasonic flaw detection by the TOFD method, the refraction angle is often set to 60 degrees.

JP 2001-228128 A

  In the ultrasonic flaw detection by the TOFD method, since the diffracted wave from the tip of the crack inside the flaw detection target is detected, the direction in which the transmitting probe and the receiving probe are lined up and the direction in which the crack extends is one. It was thought that it was difficult to obtain a diffracted wave from the tip of the crack, and it was difficult to detect the crack. Therefore, in the ultrasonic flaw detection by the TOFD method, the transmitting probe and the receiving probe are arranged so that the direction in which the transmitting probe and the receiving probe are arranged and the extending direction of the crack intersect. To perform flaw detection. However, depending on the flaw detection target, the arrangement of the transmission-side probe and the reception-side probe may be restricted due to, for example, interference with other members.

  Then, as a result of the inventor's intensive study, in the ultrasonic flaw detection by the TOFD method, the case where the direction in which the transmission-side probe and the reception-side probe are aligned and the direction in which the crack extends is the same. Also found that cracks could be detected. However, when the direction in which the transmitting probe and the receiving probe are aligned and the direction in which the crack extends coincide with each other, the incident angle of the ultrasonic wave in the flaw detection target, which is suitable for detecting the crack. However, the inventors have found that the incident angle is different from the incident angle (45 to 55 degrees) which is considered to be suitable in the conventional TOFD method.

  In view of the above circumstances, at least one embodiment of the present invention can detect a crack inside a flaw detection target even when the arrangement of a transmission probe and a reception probe is restricted. It is an object of the present invention to provide an ultrasonic flaw detection method and a flaw detection apparatus using the TOFD method.

(1) The ultrasonic testing method according to at least one embodiment of the present invention includes:
A transmitting probe configured so that a longitudinal ultrasonic wave propagates inside a flaw detection object at a fixed refraction angle of 30 degrees or more and 45 degrees or less, and receives an ultrasonic wave from the transmitting probe. And a receiving probe to be disposed along the extending direction of the groove formed in the flaw detection target member,
Performing ultrasonic flaw detection by the TOFD method by the transmission-side probe and the reception-side probe arranged along the extending direction of the groove;
Is provided.

As described above, as a result of the inventor's intensive study, in the ultrasonic flaw detection by the TOFD method, the case where the direction in which the transmitting probe and the receiving probe are aligned and the direction in which the crack extends coincides with each other. However, it was found that a crack could be detected. Further, as a result of intensive studies by the inventors, when the direction in which the transmission-side probe and the reception-side probe are aligned and the direction in which the crack extends coincide with each other, a flaw detection method suitable for crack detection is used. It has been found that the incident angle of the ultrasonic wave in the object, that is, the refraction angle is 30 degrees or more and 45 degrees or less.
In this regard, in the method (1), the transmitting probe configured to transmit the longitudinal ultrasonic wave through the flaw detection target at a fixed refraction angle of 30 degrees or more and 45 degrees or less, The side probe is arranged along the direction in which the groove of the flaw detection target member extends, and ultrasonic flaw detection by the TOFD method is performed. This makes it possible to detect a crack extending in the direction in which the transmitting probe and the receiving probe are arranged, that is, a crack extending in the same direction as the groove extending direction of the flaw detection target member. Therefore, even when there is a restriction on the arrangement of the probe and the transmission-side probe and the reception-side probe cannot be arranged along the direction intersecting the extending direction of the groove, the extending direction of the groove The crack extending in the same direction as the above can be detected by ultrasonic testing using the TOFD method.

(2) In some embodiments, in the method of the above (1), the step of arranging the transmission-side probe and the reception-side probe along the extending direction of the groove includes 30 degrees or more. The transmitting-side probe and the receiving-side probe, which are configured such that longitudinal ultrasonic waves propagate within the flaw detection target at the fixed refraction angle of 40 degrees or less, and the flaw detection target It is arranged along the extending direction of the groove formed in the member.

As a result of intensive studies by the inventors, when the direction in which the transmission-side probe and the reception-side probe are aligned and the direction in which the crack extends coincide with each other, a more suitable refraction angle is 30 degrees or more and 40 degrees or more. Degrees.
In this regard, the method (2) uses a transmitting probe configured so that longitudinal ultrasonic waves propagate through the flaw detection target at a fixed refraction angle of 30 degrees or more and 40 degrees or less. Thus, the ultrasonic flaw detection method is more suitable for detecting a crack extending in the same direction as the groove extending direction of the flaw detection target member.

(3) In some embodiments, in the method of the above (1) or (2), in the step of performing the ultrasonic flaw detection by the TOFD method, the transmitting probe and the receiving probe are connected to each other. Detect cracks extending along the line-up direction.

  As described above, the method (1) or (2) is suitable for detecting a crack extending in a direction in which the transmitting probe and the receiving probe are arranged. Therefore, according to the method (3), the crack extending in the direction in which the transmitting probe and the receiving probe are aligned, that is, extending in the same direction as the extending direction of the groove of the flaw detection target member. Cracks can be detected by ultrasonic testing using the TOFD method.

(4) In some embodiments, in any one of the above methods (1) to (3),
The transmission-side probe has a wedge member,
In the step of performing the ultrasonic flaw detection by the TOFD method, a surface extending along a direction in which the transmission-side probe and the reception-side probe are arranged, and a surface of the wedge member facing the flaw detection target member A planar crack extending in a direction perpendicular to the direction is detected.

As a result of intensive studies by the inventors, while extending along the direction in which the transmission-side probe and the reception-side probe are aligned, the wedge member extends in a direction orthogonal to the surface of the wedge member facing the member to be inspected. It has been found that a planar crack can be detected.
Therefore, according to the above method (4), the transmission side probe and the reception side probe extend along the direction in which they are arranged, and extend in the direction orthogonal to the surface of the wedge member facing the member to be inspected. Can be detected.

(5) In some embodiments, in any one of the above methods (1) to (4), in the step of performing ultrasonic inspection by TOFD, the transmission arranged along the extending direction of the groove. Ultrasonic testing is performed by the TOFD method while moving the side probe and the receiving side probe along the extending direction of the groove.

  According to the above method (5), by moving the transmission-side probe and the reception-side probe along the extending direction of the groove, scanning can be performed along the extending direction of the groove. Cracks that are likely to occur can be detected efficiently.

(6) In some embodiments, in the method of the above (5),
Prior to performing the step of performing the ultrasonic flaw detection by the TOFD method, the method further includes the step of adjusting the positions of the transmission-side probe and the reception-side probe in a direction orthogonal to the extending direction of the groove.

If the position of the crack extending in the same direction as the extending direction of the groove and the positions of the transmitting probe and the receiving probe are displaced in a direction orthogonal to the extending direction of the groove, the amount of displacement is reduced. The larger it is, the more difficult it is to detect cracks.
In this regard, in the above method (6), the approximate position of the crack in the direction orthogonal to the extending direction of the groove is grasped, for example, by preliminary flaw detection, and then the groove and the transmitting side are adjusted to that position. The distance between the probe and the receiving probe can be adjusted. Then, after adjusting the distance between the groove and the transmission-side probe and the reception-side probe, ultrasonic inspection is performed while moving the transmission-side probe and the reception-side probe along the extending direction of the groove. By doing so, it is possible to improve the detection accuracy of a crack that is likely to occur near the groove.

(7) In some embodiments, in any one of the above methods (1) to (6),
The flaw detection target is a rotor disk of a turbine,
The groove is a blade groove of the rotor disk, extends in a circumferential direction of the rotor disk,
The rotor disk has a disk surface oriented in a direction parallel to a rotation axis of the rotor disk,
In the step of disposing the transmitting probe and the receiving probe along the extending direction of the groove, the transmitting probe and the receiving probe may be extended by extending the wing groove. It is arranged on the disk surface along the direction.

In a turbine such as a gas turbine or a steam turbine, a turbine blade is fixed to a rotor disk with a blade root portion of the turbine blade inserted into a blade groove formed in the rotor disk of the turbine.
For example, a steam turbine is operated under a high temperature condition, and therefore, when used for a long time, a crack may be generated in a stressed portion due to stress corrosion cracking or the like. This crack often occurs near the blade groove along the extending direction of the blade groove. Therefore, in the conventional ultrasonic testing using the TOFD method, the transmitting probe and the receiving probe are arranged in a direction orthogonal to the extending direction of the blade groove, and are arranged along the extending direction of the blade groove. Cracks, which often occur during the operation, were detected.
However, since a plurality of rotor disks are arranged along the direction in which the rotation axis of the rotor extends, for example, if the distance between the rotor disks is short, the probe may interfere with an adjacent rotor disk, for example. Therefore, it may be difficult to arrange the transmission-side probe and the reception-side probe along a direction intersecting with the extending direction of the blade groove.

  In this regard, according to the method (7), since the transmitting probe and the receiving probe are arranged on the disk surface along the extending direction of the blade groove, they intersect with the extending direction of the blade groove. Even when it is difficult to arrange the transmitting probe and the receiving probe along the direction in which the transmitting probe and the receiving probe are arranged, the transmitting probe and the receiving probe can be arranged on the disk surface. In the method (7), a crack extending in the direction in which the transmitting probe and the receiving probe are arranged can be detected, so that the crack extending in the same direction as the extending direction of the blade groove can be detected. Can be detected. Therefore, even when there is a restriction on the arrangement of the probes and it is not possible to arrange the transmitting probe and the receiving probe along the direction intersecting with the extending direction of the blade groove, the extension of the blade groove is not sufficient. A crack extending in the same direction as the existing direction can be detected by ultrasonic testing using the TOFD method.

(8) In some embodiments, in any one of the above methods (1) to (6),
The flaw detection target is a rotor disk of a turbine,
The groove is a blade groove of the rotor disk, extends in a circumferential direction of the rotor disk,
The rotor disk has a disk surface facing in a direction parallel to the rotation axis of the rotor disk, and a conical surface formed radially outward from the disk surface,
In the step of disposing the transmitting probe and the receiving probe along the extending direction of the groove, the transmitting probe and the receiving probe may be extended by extending the wing groove. It is arranged on the conical surface along the direction.

  According to the above method (8), since the transmitting probe and the receiving probe are arranged on the conical surface along the extending direction of the blade groove, the extending direction of the blade groove is as described above. Even when it is difficult to arrange the transmitting probe and the receiving probe along the direction intersecting with the transmitting probe, the transmitting probe and the receiving probe can be arranged on the conical surface. . In the method (8), a crack extending in the direction in which the transmitting probe and the receiving probe are arranged can be detected, so that the crack extending in the same direction as the blade groove extends. Can be detected. Therefore, even when there is a restriction on the arrangement of the probes and it is not possible to arrange the transmitting probe and the receiving probe along the direction intersecting with the extending direction of the blade groove, the extension of the blade groove is not sufficient. A crack extending in the same direction as the existing direction can be detected by ultrasonic testing using the TOFD method.

(9) The flaw detector according to at least one embodiment of the present invention includes:
A transmitting-side probe having a transmitting-side ultrasonic transducer and a transmitting-side wedge member configured to transmit a longitudinal ultrasonic wave through a flaw detection target object at a fixed refraction angle of 30 degrees or more and 45 degrees or less. When,
Receiving-side ultrasonic transducer, and a receiving-side probe having a receiving-side wedge member,
A holding unit that holds the transmission-side probe and the reception-side probe facing each other,
A control device for performing ultrasonic flaw detection by the TOFD method using the transmission-side probe and the reception-side probe,
Is provided.

As described above, as a result of the inventor's intensive study, in the ultrasonic flaw detection by the TOFD method, the case where the direction in which the transmitting probe and the receiving probe are aligned and the direction in which the crack extends coincides with each other. However, it was found that a crack could be detected. Further, as a result of the inventor's intensive studies, when the direction in which the transmitting probe and the receiving probe are aligned and the extending direction of the crack coincide, the refraction angle suitable for detecting the crack is determined. Was found to be 30 degrees or more and 45 degrees or less.
In that regard, in the configuration of the above (9), the transmission side having the transmission side wedge member configured so that the longitudinal ultrasonic wave propagates in the flaw detection target at a fixed refraction angle of 30 degrees or more and 45 degrees or less. Ultrasonic testing by the TOFD method can be performed with the probe and the receiving probe facing each other. This makes it possible to detect a crack extending in the direction in which the transmitting probe and the receiving probe are arranged. Therefore, there is a restriction on the arrangement of the probes, and the direction in which the transmitting probe and the receiving probe are lined up, that is, the direction of the holding unit is limited, and the transmitting probe and the receiving probe are separated. Even when the direction in which the cracks are arranged and the direction in which the cracks extend are the same, the cracks can be detected by ultrasonic testing using the TOFD method.

(10) In some embodiments, in the configuration of the above (9),
At least two guide rollers,
A main body frame to which the holding portion is attached so that the guide roller is rotatably held, and the transmission probe and the reception probe are arranged along a guide direction by the guide roller. ,
Is further provided.

  According to the above configuration (10), by performing ultrasonic flaw detection while guiding the transmitting probe and the receiving probe with respect to the flaw detection target using the guide rollers, scanning can be performed in the guide direction of the guide rollers. . Thus, not only a crack extending in a direction intersecting the guide direction by the guide roller but also a crack extending along the guide direction can be efficiently detected.

(11) In some embodiments, in the configuration of (10), an adjusting unit for adjusting a position of the holding unit in the main body frame in a direction intersecting with the guiding direction is further provided.

  According to the configuration of the above (11), even when the range in which the guide roller can move on the surface of the flaw detection target is limited due to, for example, the shape of the flaw detection target, the adjustment unit makes contact with the guide roller. By adjusting the distance to the holding unit, the range in which the transmission-side probe and the reception-side probe are guided by the guide roller can be adjusted.

(12) In some embodiments, in the configuration of the above (10) or (11), a direction in which the transmission-side probe and the reception-side probe are aligned is the same as the guiding direction. The first attitude in which the holding unit is attached to the main body frame, and the holding unit is configured such that a direction in which the transmission-side probe and the reception-side probe are aligned is a direction orthogonal to the guiding direction. The apparatus further includes a posture changing unit that can change the posture of the holding unit to at least two postures of a second posture attached to the main body frame.

For example, when performing a flaw detection in a narrow place, in one of the first posture and the second posture, for example, the cable of the ultrasonic transducer interferes with the surroundings, making it difficult to carry out the flaw detection. A change in posture may change the feasibility of flaw detection, for example, interference between the cable and the surroundings can be avoided and flaw detection becomes easier.
In this regard, according to the configuration (12), the posture of the holding unit can be changed to at least the first posture and the second posture, so that flaw detection can be efficiently performed even in a narrow place, for example.

(13) In some embodiments, in any one of the configurations (9) to (12),
Each of the transmission-side ultrasonic transducer and the reception-side ultrasonic transducer has a columnar housing, and includes a cable that projects radially outward from a side surface of the housing.
The transmission-side ultrasonic transducer, in a plan view of the transmission-side probe and the reception-side probe, between the cable of the transmission-side ultrasonic transducer and a side surface of the housing of the reception-side ultrasonic transducer. Attached to the transmission-side wedge member so that the distance is within twice the thickness of the housing,
The receiving-side ultrasonic transducer, in the plan view, the distance between the cable of the receiving-side ultrasonic transducer and the side surface of the housing of the transmitting-side ultrasonic transducer is not more than twice the thickness of the housing. The cable is attached to the reception-side wedge member such that the cable does not overlap with the cable of the transmission-side ultrasonic transducer in the plan view.

When bending the cable of the ultrasonic transducer, it is necessary to secure a curvature radius of a certain degree or more in order to avoid problems such as disconnection. Therefore, for example, when flaw detection is performed in a narrow place, the cable may interfere with the surroundings.
For example, the cable of the transmitting ultrasonic transducer is projected in the direction opposite to the direction in which the receiving ultrasonic transducer exists when viewed from the transmitting ultrasonic transducer, and the cable of the receiving ultrasonic transducer is similarly received. Consider a case where the transmission-side ultrasonic transducer is projected in a direction opposite to the direction in which the transmission-side ultrasonic transducer is present when viewed from the side ultrasonic transducer. In this case, the two cables are separated from the transmission-side ultrasonic transducer and the reception-side ultrasonic transducer at a position apart from the intermediate position between the transmission-side ultrasonic transducer and the reception-side ultrasonic transducer in plan view, from the intermediate position. Each of them protrudes in the direction away from each other.

On the other hand, in the configuration (13), the two cables are disposed so as to pass through the vicinity of the side surface of the housing of the ultrasonic transducer on the other side in the plan view. In this case, the two cables are connected to the intermediate position from the transmitting ultrasonic transducer and the receiving ultrasonic transducer located at positions away from the intermediate position between the transmitting ultrasonic transducer and the receiving ultrasonic transducer in plan view. Each of them protrudes toward the approaching direction. Therefore, when the cable is bent at a certain radius of curvature, the distance over which the two cables project in the direction in which the transmitting probe and the receiving probe are arranged in plan view is two distances as described above. The length can be reduced as compared with the case where the cables protrude away from the ultrasonic transducers on the other side.
Therefore, the cables are less likely to interfere with the surroundings than in the case where the two cables protrude away from the other ultrasonic transducer as described above.

  According to at least one embodiment of the present invention, it is possible to detect a crack inside a flaw detection target object even when there are restrictions on the arrangement of a transmission-side probe and a reception-side probe.

It is a schematic plan view of the flaw detector according to some embodiments. It is a typical side view of a flaw detector concerning some embodiments. It is a schematic plan view for explaining arrangement of a transmitting side probe and a receiving side probe in a flaw detector according to some embodiments. It is a typical side view for explaining arrangement of a transmitting side probe and a receiving side probe in a flaw detector concerning some embodiments. It is a typical side view for explaining arrangement of a transmitting side probe and a receiving side probe in a flaw detector concerning some embodiments. It is a functional block diagram of a flaw detection device concerning some embodiments. It is a figure for explaining a 2nd posture. It is a figure for explaining a 3rd posture. FIG. 2 is a schematic plan view of the flaw detector in a state where the holding unit has been moved to a position different from the width direction in FIG. 1. FIG. 4 is a cross-sectional view of the vicinity of an outer peripheral portion of the rotor disk as viewed from a circumferential direction of the rotor disk. FIG. 4 is a cross-sectional view of the vicinity of an outer peripheral portion of the rotor disk as viewed from a circumferential direction of the rotor disk. FIG. 4 is a cross-sectional view of the vicinity of an outer peripheral portion of the rotor disk as viewed from a circumferential direction of the rotor disk. FIG. 4 is a diagram schematically illustrating an example of a case in which a transmission-side probe and a reception-side probe are arranged along the radial direction of a rotor disk to perform ultrasonic flaw detection. It is a typical top view for explaining cable management, and (a) is an example when a cable is made to protrude mutually in the direction opposite to an ultrasonic transducer of the other party, and (b) FIG. 4 is a diagram illustrating a state of cable management in some embodiments. It is a flowchart which shows the procedure of a process in the ultrasonic flaw detection method which concerns on some embodiments. It is sectional drawing which looked at the outer periphery part of the rotor disk which has a conical surface from the circumferential direction of the rotor disk.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.
For example, expressions representing relative or absolute arrangement such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly described. Not only does such an arrangement be shown, but also a state of being relatively displaced by an angle or distance that allows the same function to be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which indicate that things are in the same state, not only represent exactly the same state, but also have a tolerance or a difference to the extent that the same function is obtained. An existing state shall also be represented.
For example, the expression representing a shape such as a square shape or a cylindrical shape not only represents a shape such as a square shape or a cylindrical shape in a strictly geometrical sense, but also an uneven portion or a chamfer as long as the same effect can be obtained. A shape including a part and the like is also represented.
On the other hand, the expression “comprising”, “comprising”, “including”, “including”, or “having” one component is not an exclusive expression excluding the existence of another component.

FIG. 1 is a schematic plan view of a flaw detector according to some embodiments. FIG. 2 is a schematic side view of a flaw detector according to some embodiments. FIG. 3 is a schematic plan view for explaining an arrangement of a transmitting probe and a receiving probe in the flaw detector according to some embodiments. FIG. 4 is a schematic side view for explaining the arrangement of the transmitting probe and the receiving probe in the flaw detector according to some embodiments. FIG. 5 is a schematic side view for explaining an arrangement of a transmission-side probe and a reception-side probe in a flaw detection apparatus according to some embodiments. It is the figure seen along the direction toward a child. FIG. 5 shows cracks in the transmitting probe, the receiving probe, and the flaw detection target (rotor disk) in FIG. 4 along the direction from the transmitting probe to the receiving probe. FIG. FIG. 6 is a functional block diagram of a flaw detector according to some embodiments.
A flaw detector 100 according to some embodiments shown in FIGS. 1 to 6 is an apparatus for performing ultrasonic flaw detection by the TOFD method, and can detect a crack inside a flaw detection target. The flaw detector 100 according to some embodiments can be used, for example, for detecting cracks generated in a rotor disk 1 of a turbine rotor in a turbine such as a gas turbine or a steam turbine. FIG. 1 shows a state in which a flaw detector 100 is arranged on a disk surface 2 of a rotor disk 1 which faces in a direction parallel to a rotation axis (not shown).

The flaw detection apparatus 100 according to some embodiments includes a transmission-side probe 110, a reception-side probe 120, a holding unit 140, and a control device 102. Further, the flaw detection device 100 according to some embodiments includes a main body frame 150, a guide roller 180, and a rotary encoder 131.
For convenience of description, a direction perpendicular to the surfaces 112a, 122a of the transmission-side wedge member 112 and the reception-side wedge member 122, which will be described later, facing the flaw detection target is defined as a vertical direction, and a direction in which the surfaces 112a, 122a are defined as a downward direction. The surfaces 112a and 122a are also referred to as lower surfaces 112a and 122a. Further, the same direction as the guide direction by the guide roller 180 described later is referred to as a guide direction. The same direction as the direction in which the rotation axis of the guide roller 180 extends may be referred to as the width direction.

The transmission-side probe 110 is configured so that the transmission-side ultrasonic transducer 111 and the longitudinal ultrasonic wave 115 propagates through the flaw detection target at a fixed refraction angle θ of 30 degrees or more and 45 degrees or less. The transmission-side wedge member 112 is provided (see FIG. 4). Note that the refraction angle θ is a direction orthogonal to the surface of the flaw detection target (for example, the rotor disk 1) facing the transmission side wedge member 112 (that is, the above-described vertical direction), and a traveling direction of the ultrasonic wave 115 in the flaw detection target. And the angle difference.
The receiving probe 120 includes a receiving ultrasonic transducer 121 for receiving a lateral wave, a bottom surface reflected wave, and an ultrasonic wave 125 from the crack 20, and a receiving wedge member 122.
The transmitting-side ultrasonic transducer 111 and the receiving-side ultrasonic transducer 121 are single-element transducers. That is, the transmitting probe 110 and the receiving probe 120 are so-called fixed angle probes.

The transmission-side ultrasonic transducer 111 has a cylindrical housing 111a, and includes a cable 113 protruding radially outward from a side surface of the housing 111a. One end of the cable 113 is attached to a side surface of the transmission-side ultrasonic transducer 111 via a connector 114. The other end of the cable 113 is connected to the control device 102.
Similarly, the receiving-side ultrasonic transducer 121 has a cylindrical housing 121a, and includes a cable 123 protruding radially outward from a side surface of the housing 121a. One end of the cable 123 is attached to a side surface of the receiving ultrasonic transducer 121 via a connector 124. The other end of the cable 123 is connected to the control device 102.

The holding unit 140 is a holding member that holds the transmission-side probe 110 and the reception-side probe 120 so as to face each other. Although not shown, the holding unit 140 may be configured so that the distance between the transmitting probe 110 and the receiving probe 120 can be adjusted.
The holding section 140 has a shaft section 141 that extends vertically above the transmission-side probe 110 and the reception-side probe 120.

The holding unit 140 is attached to the main body frame 150 via an adjusting unit 160 and a posture changing unit 170 described later. In some embodiments, the body frame 150 rotatably holds the four guide rollers 180. Although not shown, the guide roller 180 may be rotatably attached to the main body frame 150.
The guide roller 180 is configured to be attracted to a flaw detection target object by a magnetic attraction force.

  In the embodiment shown in FIG. 1, for example, the treads T of the four guide rollers 180 are smaller than the width in the width direction of the main body frame 150. The size in the width direction may be the same as or larger than the size in the width direction of the main body frame 150. Also, for example, in the embodiment shown in FIG. 1, the wheel base W / B of the four guide rollers 180 is larger than the size of the main frame 150 in the guide direction, but the wheel base W / B of the four guide rollers 180 is larger. B may be the same as the size of the main body frame 150 in the guiding direction or smaller than the size of the main body frame 150 in the guiding direction.

  One of the guide rollers 180 is configured such that the rotation angle of the guide roller 180 is detected by the rotary encoder 131. When the flaw detection device 100 is guided on the flaw detection target by the guide roller 180, the rollers other than the four guide rollers described above are configured to roll on the flaw detection target, and the rotation angle of the roller is changed. The detection may be performed by the rotary encoder 131. The detection signal of the rotary encoder 131 is output to the control device 102. The control device 102 calculates the moving distance of the flaw detection device 100 based on the detection signal of the rotary encoder 131.

The adjustment unit 160 is an adjustment mechanism for adjusting the position of the holding unit 140 in the body frame 150 in the width direction. The adjusting section 160 has an adjusting screw section 161 and an arm section 163.
The adjusting screw 161 is a male screw extending in the width direction, and is rotatably supported by the adjusting screw support 152 of the main body frame 150. A knob 162 for rotating the adjusting screw 161 is attached to one end of the adjusting screw 161.

The arm portion 163 is a member extending in the same direction as the guide direction by the guide roller 180, and has a female screw portion 164 connected to the adjusting screw portion 161 at one end, and a shaft portion of the holding portion 140 at the other end. A shaft holding portion 165 for holding the shaft 141 is formed.
The shaft holding portion 165 includes a pair of holding portions 165a and 165b that can hold the side surface of the shaft portion 141 from the width direction, and a bolt 166 that adjusts an interval between the holding portions 165a and 165b. The bolt 166 passes through a through hole (not shown) formed in one holding portion 165a and is connected to a female screw portion (not shown) formed in the other holding portion 165b.
When the bolt 166 is tightened, the distance between the pair of holding portions 165a and 165b is reduced, and the shaft 141 is fixed to the shaft holding portion 165. When the bolt 166 is loosened, the interval between the pair of holding portions 165a and 165b increases, and the shaft 141 can rotate with respect to the shaft holding portion 165.

  The control device 102 is a control device for performing ultrasonic flaw detection by the TOFD method using the transmission-side probe 110 and the reception-side probe 120. The control device 102 controls the transmission-side ultrasonic transducer 111 so that the transmission-side ultrasonic transducer 111 emits an ultrasonic wave. The control device 102 stores the waveform of the ultrasonic wave received by the receiving-side ultrasonic transducer 121 in a storage unit (not shown). The control device 102 visualizes a crack inside the flaw detection target based on the waveform of the ultrasonic wave received by the receiving-side ultrasonic transducer 121.

In the flaw detector 100 according to some embodiments configured as described above, as shown in FIGS. 1 and 2, the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged (the horizontal direction in the drawing). The first posture in which the holding unit 140 is attached to the main body frame 150 can be taken so that the guiding direction by the guide roller 180 is the same as the direction.
In addition, in the flaw detector 100 according to some embodiments, the transmitting side probe 110 and the receiving side probe are rotated as shown in FIG. The holding portion 140 can be in the second posture in which the holding portion 140 is attached to the main body frame 150 so that the direction in which the holding portions 120 are aligned (vertical direction in the drawing) is perpendicular to the direction of guidance by the guide roller 180. FIG. 7 is a diagram for describing the second posture.
Further, in the flaw detection device 100 according to some embodiments, the transmitting side probe 110 and the receiving side probe are rotated by rotating the shaft portion 141 with respect to the shaft holding portion 165 as shown in FIG. The third position in which the holding unit 140 is attached to the main body frame 150 can be taken so that the direction in which the holding units 140 are aligned with the direction intersecting with the guide direction by the guide roller 180 and the width direction. FIG. 8 is a diagram for describing the third posture. FIG. 8 illustrates an example in which the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged is inclined by 45 degrees with respect to the guide direction of the guide roller 180.
That is, the flaw detector 100 according to some embodiments includes the attitude changing unit 170 that can change the attitude of the holding unit 140. Specifically, posture changing section 170 includes a shaft section 141 and a shaft holding section 165.

  In the flaw detection apparatus 100 according to some embodiments, the flaw detection target is guided by the guide roller 180 in the state where the posture of the holding unit 140 is any of the above-described first posture, second posture, and third posture. Can detect flaws inside objects.

Further, in the flaw detector 100 according to some embodiments, as shown in FIGS. 1 and 9, the position of the holding unit 140 in the width direction of the main body frame 150 can be adjusted by the adjusting unit 160. FIG. 9 is a schematic plan view of the flaw detector in a state where the holding unit 140 has been moved to a position different in the width direction from FIG.
Specifically, when the adjusting screw 161 is rotated by rotating the knob 162, the arm 163 having the female screw 164 coupled to the adjusting screw 161 moves in the width direction. As a result, the shaft portion 141 held by the shaft holding portion 165 of the arm portion 163, that is, the holding portion 140 moves in the width direction with respect to the main body frame 150.

  In the flaw detector 100 according to some embodiments configured as described above, for example, the flaw detector 100 is arranged on the disk surface 2 of the rotor disk 1, and the flaw detector 100 is moved along the circumferential direction of the rotor disk 1. Ultrasonic flaw detection by the TOFD method can be performed inside the rotor disk 1 while moving.

In a turbine such as a gas turbine or a steam turbine, a turbine blade is fixed to the rotor disk 1 with a blade root portion of the turbine blade inserted into a blade groove formed in the rotor disk 1 of the turbine.
For example, a steam turbine is operated under a high temperature condition, and therefore, when used for a long time, a crack may be generated in a stressed portion due to stress corrosion cracking or the like. This crack often occurs near the blade groove along the extending direction of the blade groove.

  For example, as shown in FIG. 1 and FIGS. 10 to 12, when a T-root type blade groove 5 is formed along the circumferential direction of the rotor disk 1 in the rotor disk 1, it is surrounded by a dashed circle A in FIG. Cracks 20 are likely to occur at the radially outer corners of the blade groove 5. 10 to 12 are cross-sectional views of the vicinity of the outer peripheral portion of the rotor disk 1 as viewed from the circumferential direction of the rotor disk 1. 10 to 12, in the flaw detector 100, the transmitting probe 110 and the receiving probe 120 are shown, and other components are not shown. FIG. 10 shows an example in which a crack 20 is generated from the inner circumferential surface of the blade groove 5 toward a rotation axis (not shown) of the turbine (hereinafter, also referred to as an axial direction). FIG. 11 shows an example in which a crack 20 is generated in the axial direction in a state in which the inner circumferential surface of the blade groove 5 is inclined radially outward of the rotor disk 1. FIG. 12 shows an example in which a crack 20 is generated from the inner peripheral surface of the blade groove 5 toward the radial outside of the rotor disk 1.

  These cracks 20 often occur along the extending direction of the blade groove 5, that is, along the circumferential direction of the rotor disk 1. Therefore, in the conventional ultrasonic flaw detection by the TOFD method, as shown in FIG. 13, the transmission probe 110 and the reception probe 120 are arranged along a direction orthogonal to the extending direction of the blade groove 5. Thus, a crack 20 that often occurs along the extending direction of the blade groove 5 is detected. FIG. 13 is a diagram schematically illustrating an example in which the ultrasonic probe is arranged by arranging the transmission-side probe 110 and the reception-side probe 120 along the radial direction of the rotor disk 1.

  In the ultrasonic flaw detection by the TOFD method, in order to detect a diffracted wave from the tip of the crack 20 inside the flaw detection target, as shown in FIG. 4 and FIGS. If the direction in which the elements 120 are arranged and the direction in which the cracks 20 extend coincide with each other, it has been considered that it is difficult to obtain a diffracted wave from the tip of the crack 20 and it is difficult to detect the crack 20. Therefore, in the ultrasonic flaw detection by the TOFD method, as shown in FIG. 13, the transmitting side probe 110 and the receiving side probe 120 are arranged such that the direction in which the transmitting side probe 110 and the receiving side probe 120 are arranged intersects and the direction in which the crack 20 extends is crossed. The flaw detection is performed by disposing the probe 110 and the receiving probe 120.

However, depending on the flaw detection target, the arrangement of the transmission-side probe 110 and the reception-side probe 120 may be restricted by reasons such as interference with other members.
For example, in a turbine, since a plurality of rotor disks 1 are arranged along the direction in which the rotation axis of the rotor extends, for example, when the distance between adjacent rotor disks 1 is short, the rotor disks 1 are adjacent to the probes 110 and 120. For reasons such as interference with the rotor disk 1, it may be difficult to arrange the transmission-side probe 110 and the reception-side probe 120 along a direction intersecting with the extending direction of the blade groove 5. .

Then, as a result of the inventor's intensive study, in the ultrasonic flaw detection by the TOFD method, the case where the direction in which the transmitting probe 110 and the receiving probe 120 are aligned and the extending direction of the crack 20 match. However, it was found that the crack 20 could be detected. However, if the direction in which the transmission-side probe 110 and the reception-side probe 120 are aligned and the direction in which the crack 20 extends coincide with each other, an ultra-small object within the flaw detection target suitable for detecting the crack 20 is used. The inventors have found that the incident angle of the sound wave, that is, the refraction angle is different from the refraction angle (45 to 55 degrees) which is considered to be suitable in the conventional TOFD method. Specifically, when the direction in which the transmitting probe 110 and the receiving probe 120 are aligned and the extending direction of the crack 20 match, the refraction angle θ suitable for detecting the crack 20 becomes The inventors have found that the angle is not less than 30 degrees and not more than 45 degrees.
In addition, when the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged and the direction in which the crack 20 extends coincide with each other, the refraction angle more suitable for detection of the crack 20. was found to be 30 degrees or more and 40 degrees or less.

  In that regard, the flaw detector 100 according to some embodiments described above is configured such that the longitudinal ultrasonic waves 115 propagate through the flaw detection target at a fixed refraction angle θ of 30 degrees or more and 45 degrees or less. Ultrasonic flaw detection by the TOFD method can be performed with the transmitting probe 110 having the transmitting wedge member 112 and the receiving probe 120 facing each other. Thus, the crack 20 extending in the direction in which the transmitting probe 110 and the receiving probe 120 are arranged can be detected. Therefore, the arrangement of the probes 110 and 120 is restricted, and the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged, that is, the direction of the holding unit 140 is limited. Even when the direction in which the receiving probes 120 are arranged and the direction in which the crack 20 extends are the same, the crack 20 can be detected by ultrasonic inspection using the TOFD method.

Further, in the flaw detector 100 according to some embodiments described above, as shown in FIGS. 11 and 12, the crack 20 is a planar crack, and the transmission probe 110 and the reception probe 120 Extend in a direction different from the vertical direction, that is, the direction orthogonal to the lower surfaces 112a and 122a of the wedge members 112 and 122 (the axial direction in FIGS. 11 and 12). Not only can the crack 20 be detected. According to the flaw detector 100 according to some embodiments described above, as shown in FIGS. 5 and 10, the crack 20 is a planar crack, and the transmission probe 110 and the reception probe 120 are used. The inventors have found that the crack 20 can be detected even when the crack 20 extends in a direction perpendicular to the lower surfaces 112a and 122a of the wedge members 112 and 122, while extending in the direction in which.
As described above, in the flaw detection apparatus 100 according to some of the above-described embodiments, as illustrated in FIGS. 5 and 10, the transmission-side probe 110 and the reception-side probe 120 extend in the direction in which they are arranged. The planar crack 20 extending in the depth direction when viewed from the flaw detectors 110 and 120, that is, in the depth direction when viewed from the flaw detectors 110 and 120, can be detected.

  The transmission-side wedge member 112 may be configured so that the longitudinal ultrasonic waves 115 propagate through the flaw detection target object at a fixed refraction angle θ of 30 degrees or more and 40 degrees or less. In this case, the detection accuracy of the crack 20 can be further improved.

  When the transmission-side wedge member 112 is configured so that the longitudinal ultrasonic waves 115 propagate in the flaw detection target at a fixed refraction angle θ of 30 degrees or more and 45 degrees or less, and 30 degrees or more and 40 degrees or less In any of the cases where the transmission-side wedge member 112 is configured such that the longitudinal ultrasonic waves 115 propagate through the flaw detection target at the fixed refraction angle θ, the flaw detection according to some of the above-described embodiments is performed. The apparatus 100 can also detect a crack extending in a direction different from the direction in which the transmitting probe 110 and the receiving probe 120 are arranged.

  Further, in the flaw detection apparatus 100 according to some of the above-described embodiments, ultrasonic flaw detection is performed by guiding the flaw detection target with the transmission-side probe 110 and the reception-side probe 120 with the guide roller 180. , Can be scanned in the guide direction by the guide roller 180. Thus, not only the crack 20 extending in the direction intersecting the guide direction by the guide roller 180 but also the crack 20 extending in the guide direction can be efficiently detected.

  In the flaw detection apparatus 100 according to some of the above-described embodiments, the range in which the guide roller 180 and the body frame 150 can move on the surface of the flaw detection target is limited due to, for example, the shape of the flaw detection target. However, by adjusting the widthwise positional relationship between the guide roller 180, that is, the main body frame 150 and the holding unit 140, by the adjusting unit 160, the guide roller 180 guides the transmission-side probe 110 and the reception-side probe 120. You can adjust the range to do.

For example, when flaw detection is performed in a narrow place, in any one of the first posture and the second posture, for example, the cables 113 and 123 of the ultrasonic transducers 111 and 121 interfere with the surroundings, making it difficult to perform flaw detection. In the other posture, the interference between the cables 113 and 123 and the surroundings can be avoided and flaw detection can be easily performed.
In this regard, in the flaw detection apparatus 100 according to some of the above-described embodiments, since the attitude of the holding unit 140 can be changed, flaw detection can be performed efficiently even in a narrow place, for example.

(About routing of cables 113 and 123)
FIG. 14 is a schematic plan view for explaining the routing of the cables 113 and 123. FIG. 14A shows an example in which the cables 113 and 123 are protruded in directions opposite to the ultrasonic transducers 111 and 121 on the other side. FIG. 14B is a diagram illustrating a state in which the cables 113 and 123 are routed in the above-described some embodiments.

In the flaw detector 100 according to some embodiments described above, as shown in FIG. 3, each of the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer 121 has cylindrical housings 111a and 121a, Cables 113 and 123 protruding radially outward from the side surfaces of the housings 111a and 121a are provided.
As shown in FIG. 3, the transmission-side ultrasonic transducer 111 includes a cable 113 of the transmission-side ultrasonic transducer 111 and a reception-side ultrasonic transducer 121 in a plan view of the transmission-side probe 110 and the reception-side probe 120. It is attached to the transmission-side wedge member 112 such that the distance L from the side surface of the housing 121a is within twice the thickness D of the housing 121a.
Similarly, as shown in FIG. 3, the distance L between the cable 123 of the receiving-side ultrasonic transducer 121 and the side surface of the housing 111a of the transmitting-side ultrasonic transducer 111 is the same as shown in FIG. 3. The cable 123 is attached to the reception-side wedge member 122 such that the cable 123 does not overlap with the cable 113 of the transmission-side ultrasonic transducer 111 in a plan view so as to be within twice the thickness D of the housing 111a. I have.
That is, the transmission-side ultrasonic transducer 111 is configured such that the transmission-side wedge member is configured such that the cable 113 projects toward a region above a line connecting the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer 121 in plan view. 112. Further, the receiving-side ultrasonic transducer 121 is attached to the receiving-side wedge member 122 such that the cable 123 protrudes toward a region below the line segment in plan view.

When bending the cables 113 and 123 of the ultrasonic transducers 111 and 121, it is necessary to secure a curvature radius R of a certain degree or more in order to avoid problems such as disconnection. Therefore, for example, when flaw detection is performed in a narrow place, the cables 113 and 123 may interfere with the surroundings.
For example, as shown in FIG. 14A, the cable 113 of the transmission-side ultrasonic transducer 111 projects in a direction opposite to the direction in which the reception-side ultrasonic transducer 121 exists when viewed from the transmission-side ultrasonic transducer 111. Similarly, it is assumed that the cable 123 of the receiving-side ultrasonic transducer 121 is projected from the receiving-side ultrasonic transducer 121 in a direction opposite to the direction in which the transmitting-side ultrasonic transducer 111 exists. In this case, the two cables 113 and 123 are connected to the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer at a position apart from the intermediate position C between the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer 121 in plan view. From the transducer 121, it will each protrude in the direction away from the intermediate position C.

On the other hand, in the flaw detector 100 according to some of the above-described embodiments, as shown in FIG. 14B, the two cables 113 and 123 are connected to the ultrasonic transducers 111 and 121 on the other side in plan view. The casings 111a and 121a are arranged so as to pass near the side faces thereof. In this case, the two cables 113 and 123 are connected to the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer at a position apart from the intermediate position C between the transmission-side ultrasonic transducer 111 and the reception-side ultrasonic transducer 121 in plan view. From the transducer 121, it will each project toward the direction approaching the intermediate position C. Therefore, when the cables 113 and 123 are bent at a certain radius of curvature R, the distance in which the two cables 113 and 123 overhang in the direction in which the transmitting probe 110 and the receiving probe 120 are arranged in plan view. When the two cables 113 and 123 protrude in the direction away from the ultrasonic transducers 111 and 121 on the other side as described above, the two cables 113 and 123 are connected to the transmission probe 110 and the reception probe E2. The distance can be shorter than the distance E1 that extends along the direction in which the side probes 120 are arranged.
Therefore, compared with the case where the two cables 113 and 123 project away from the ultrasonic transducers 111 and 121 on the other side as described above, the cables 113 and 123 are less likely to interfere with the surroundings.

When each of the transmitting-side ultrasonic transducer 111 and the receiving-side ultrasonic transducer 121 has a prism-shaped housing 111a, 121a, the transmitting-side ultrasonic transducer 111 includes the transmitting-side probe 110 and the receiving-side probe. The distance L between the cable 113 of the transmitting-side ultrasonic transducer 111 and the side surface of the housing 121a of the receiving-side ultrasonic transducer 121 is, for example, the length of one side of a rectangular cross section of the housing 121a in a plan view of the tentacle 120. Is preferably attached to the transmission-side wedge member 112 so as to be within twice as large as
Similarly, in a plan view, the reception-side ultrasonic transducer 121 has a rectangular section of the housing 111a in which the distance L between the cable 123 of the reception-side ultrasonic transducer 121 and the side surface of the housing 111a of the transmission-side ultrasonic transducer 111 is different. Is attached to the reception-side wedge member 122 such that the length of one side of the cable 123 is not more than twice and the cable 123 of the transmission-side ultrasonic transducer 111 does not overlap in a plan view. Good.

As shown in FIG. 3, the transmission-side ultrasonic transducer 111 includes a cable 113 from the housing 111 a of the transmission-side ultrasonic transducer 111 in a plan view of the transmission-side probe 110 and the reception-side probe 120. The transmitting side wedge member 112 may be attached to the transmitting side wedge member 112 such that the angle difference θc between the projecting direction and the direction in which the transmitting side probe 110 and the receiving side probe 120 are arranged is within 45 degrees.
Similarly, as shown in FIG. 3, the receiving-side ultrasonic transducer 121 includes, in plan view, the direction in which the cable 123 projects from the housing 121 a of the receiving-side ultrasonic transducer 121, the transmitting-side probe 110, and the receiving-side ultrasonic transducer 121. It may be attached to the receiving-side wedge member 122 such that the angle difference θc from the direction in which the probes 120 are arranged is within 45 degrees.

(About ultrasonic flaw detection method)
Hereinafter, an ultrasonic flaw detection method using the flaw detection apparatus 100 according to some embodiments described above will be described.
In the following description, an example in which the inspection object is the rotor disk 1 of the turbine will be described, but the inspection object in the present invention is not limited to the rotor disk 1 of the turbine.
FIG. 15 is a flowchart illustrating a procedure of a process in the ultrasonic flaw detection method according to some embodiments. The ultrasonic flaw detection method according to some embodiments includes a preliminary flaw detection step S1, a position adjustment step S3, an arrangement step S5, and a flaw detection step S7.

(Preliminary flaw detection step S1)
The preliminary flaw detection step S1 is a step in which preliminary ultrasonic flaw detection is performed prior to the execution of the flaw detection step S7 in order to grasp the outline of the position of the cracks 20 and the distribution state of the cracks 20 in the rotor disk 1. In the preliminary flaw detection step S1, for example, a simple flaw detection device that does not include the main body frame 150 and the guide roller 180 in the flaw detection device 100 described above is used, and the operator uses the transmission probe 110 and the reception side By appropriately scanning the probe 120 on the disk surface 2 of the rotor disk 1 or the like, the outline of the position of the cracks 20 and the distribution state of the cracks 20 on the rotor disk 1 is grasped.

(Position adjustment step S3)
The position adjustment step S3 is a step of adjusting the positions of the transmission-side probe 110 and the reception-side probe 120 in a direction orthogonal to the extending direction of the blade groove 5 before performing the flaw detection step S7.
In a flaw detection step S7 described below, ultrasonic flaw detection is performed using the flaw detection device 100 according to some embodiments while guiding the guide roller 180 in the guide direction. Therefore, the position of the crack 20 extending in the same direction as the extending direction of the blade groove 5 and the position of the transmitting probe 110 and the receiving probe 120 are orthogonal to the extending direction of the blade groove 5. , The crack 20 becomes more difficult to detect as the displacement increases.

Therefore, in the position adjusting step S3, the approximate position of the crack 20 in the direction orthogonal to the extending direction of the blade groove 5 is grasped by preliminary flaw detection in the preliminary flaw detection step S1, and then adjusted to that position. The distance between the blade groove 5 and the transmission-side probe 110 and the reception-side probe 120 is adjusted. Specifically, in the position adjustment step S3, the flaw detection according to some embodiments is performed based on the positions of the cracks 20 and the distribution state of the cracks 20 in the rotor disk 1, which have been outlined by performing the preliminary flaw detection step S1. By adjusting the adjusting section 160 of the device 100, the position in the width direction of the holding section 140 in the main body frame 150 is adjusted.
After adjusting the distance between the blade groove 5 and the transmission-side probe 110 and the reception-side probe 120 in the position adjustment step S3, the transmission-side probe 110 and the reception-side probe are determined in a flaw detection step S7 described later. By performing the ultrasonic flaw detection while moving the contactor 120 along the extending direction of the blade groove 5, it is possible to improve the detection accuracy of the crack 20 which is likely to be generated near the blade groove 5.

  Note that the preliminary flaw detection step S1 may omit the preliminary flaw detection step S1 and the position adjustment step S3 depending on the type and size of the flaw detection target, how cracks peculiar to the flaw detection target are formed, and the like. .

(Arrangement step S5)
The disposing step S5 includes: a transmitting-side probe 110 configured such that a longitudinal ultrasonic wave propagates through a flaw detection target object at a fixed refraction angle θ of 30 degrees or more and 45 degrees or less; This is a step of arranging the receiving probe 120 that receives the ultrasonic waves from the flaw detection member 110 along the extending direction of the groove formed in the flaw detection target member.
That is, in the arrangement step S5, the flaw detector 100 according to some of the above-described embodiments is set so that the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged is along the extending direction of the blade groove 5. Deploy.

In the arrangement step S5, the transmitting-side probe 110 and the receiving-side probe 110 are configured so that longitudinal ultrasonic waves propagate through the flaw detection target object at a fixed refraction angle θ of 30 degrees or more and 40 degrees or less. The probe 120 may be arranged along the extending direction of the groove formed in the flaw detection target member.
As described above, when the direction in which the transmission-side probe 110 and the reception-side probe 120 are aligned and the direction in which the crack 20 extends coincide with each other, the refraction angle θ more suitable for the detection of the crack 20 is determined. , 30 ° or more and 40 ° or less. Therefore, the transmitting-side probe 110 and the receiving-side probe 120 configured so that longitudinal ultrasonic waves propagate in the flaw detection target object at a fixed refraction angle θ of 30 degrees or more and 40 degrees or less. By arranging along the extending direction of the groove formed in the flaw detection target member, an ultrasonic flaw detection method more suitable for detecting the crack 20 extending in the same direction as the extending direction of the groove of the flaw detection target member is provided. .

In the disposing step S5, as shown in FIGS. 1 and 10 to 12, the transmitting probe 110 and the receiving probe 120 are disposed on the disk surface 2 along the extending direction of the blade groove 5. Good.
In this way, by disposing the transmitting-side probe 110 and the receiving-side probe 120 on the disk surface 2 along the extending direction of the blade groove 5, as shown in FIG. Even if it is difficult to dispose the transmitting probe 110 and the receiving probe 120 along the direction intersecting the direction, the transmitting probe 110 and the receiving probe 120 are disc-shaped. It can be placed on surface 2. Further, in a flaw detection step S7 described later, a crack 20 extending in a direction in which the transmission probe 110 and the reception probe 120 are arranged can be detected, so that the crack 20 extends in the same direction as the extending direction of the blade groove 5. Crack 20 can be detected. Accordingly, there is a case where the arrangement of the probes 110 and 120 is restricted and the transmission-side probe 110 and the reception-side probe 120 cannot be arranged along the direction intersecting with the extending direction of the blade groove 5. Also, the crack 20 extending in the same direction as the extending direction of the blade groove 5 can be detected by ultrasonic testing using the TOFD method.

As shown in FIG. 16, the rotor disk 1 has a disk surface 2 oriented in a direction parallel to a rotation axis (not shown) of the rotor disk 1, and a conical surface 3 formed radially outside the disk surface 2. In the arrangement step S5, the transmitting probe 110 and the receiving probe 120 may be arranged on the conical surface 3 along the extending direction of the blade groove 5 in the arrangement step S5. FIG. 16 is a cross-sectional view of the vicinity of the outer peripheral portion of the rotor disk 1 having the conical surface 3 as viewed from the circumferential direction of the rotor disk 1.
As described above, by disposing the transmitting-side probe 110 and the receiving-side probe 120 on the conical surface 3 along the extending direction of the blade groove 5, the extending direction of the blade groove 5 is Even when it is difficult to dispose the transmitting probe 110 and the receiving probe 120 along the intersecting direction, the transmitting probe 110 and the receiving probe 120 are connected to the conical surface. 3 can be arranged. Further, in a flaw detection step S7 described later, a crack 20 extending in a direction in which the transmission probe 110 and the reception probe 120 are arranged can be detected, so that the crack 20 extends in the same direction as the extending direction of the blade groove 5. Crack 20 can be detected. Accordingly, there is a case where the arrangement of the probes 110 and 120 is restricted and the transmission-side probe 110 and the reception-side probe 120 cannot be arranged along the direction intersecting with the extending direction of the blade groove 5. Also, the crack 20 extending in the same direction as the extending direction of the blade groove 5 can be detected by ultrasonic testing using the TOFD method.

(Flaw detection step S7)
The flaw detection step S7 is a step of performing ultrasonic flaw detection by the TOFD method using the transmission-side probe 110 and the reception-side probe 120 arranged along the extending direction of the blade groove 5.
Then, in the flaw detection step S7, the crack 20 extending along the direction in which the transmitting probe 110 and the receiving probe 120 are arranged is detected.

As described above, as a result of intensive studies by the inventors, in the ultrasonic flaw detection by the TOFD method, the direction in which the transmitting probe 110 and the receiving probe 120 are aligned and the extending direction of the crack 20 match. It was found that the crack 20 could be detected even when the crack was present. In addition, as a result of the inventor's intensive studies, when the direction in which the transmitting probe 110 and the receiving probe 120 are aligned and the extending direction of the crack 20 match, the detection of the crack 20 is performed. It has been found that a suitable incident angle of the ultrasonic wave in the flaw detection target, that is, a refraction angle θ is not less than 30 degrees and not more than 45 degrees.
In that regard, in the ultrasonic flaw detection method according to some of the above-described embodiments, the ultrasonic wave of the longitudinal wave propagates in the flaw detection target at a fixed refraction angle θ of 30 degrees or more and 45 degrees or less. The transmission-side probe 110 and the reception-side probe 120 are arranged along the direction in which the groove of the flaw detection target member extends, and ultrasonic flaw detection by the TOFD method is performed. Thereby, the crack 20 extending in the direction in which the transmitting probe 110 and the receiving probe 120 are arranged, that is, the crack 20 extending in the same direction as the extending direction of the groove of the flaw detection target member is detected. be able to. Therefore, even when the arrangement of the probes 110 and 120 is restricted and the transmission-side probe 110 and the reception-side probe 120 cannot be arranged along the direction intersecting the extending direction of the groove, The crack 20 extending in the same direction as the extending direction of the groove can be detected by ultrasonic testing using the TOFD method.

  In the ultrasonic flaw detection methods according to some embodiments described above, as shown in FIGS. 5 and 10, the wedges extend along the direction in which the transmission-side probe 110 and the reception-side probe 120 are arranged. A planar crack 20 extending in a direction perpendicular to the surfaces 112a and 122a of the members 112 and 122 facing the inspection target member can be detected.

In the flaw detection step S7, ultrasonic flaw detection by the TOFD method is performed while moving the transmission-side probe 110 and the reception-side probe 120 arranged along the direction in which the blade groove 5 extends, along the direction in which the blade groove 5 extends. Is carried out.
That is, in the flaw detection step S7, as shown in, for example, FIGS. 1 and 16, the guide roller is arranged in a state where the transmission probe 110 and the reception probe 120 are arranged along the extending direction of the blade groove 5. By 180, ultrasonic flaw detection by the TOFD method is performed while moving the transmission-side probe 110 and the reception-side probe 120 along the extending direction of the blade groove 5.
By moving the transmission-side probe 110 and the reception-side probe 120 along the extending direction of the blade groove 5, scanning can be performed along the extending direction of the blade groove 5, which is generated near the blade groove 5. The crack 20 having a high possibility can be efficiently detected.

  In addition, in the flaw detection step S7, if a place where it is necessary to carry out flaw detection in more detail is found from the result of the ultrasonic flaw detection by the TOFD method obtained by scanning the rotor disk 1 along the circumferential direction, , A more detailed ultrasonic flaw detection may be performed. When the operator performs detailed ultrasonic flaw detection for the place, it is possible to grasp details such as the position of the crack 20 and the distribution state of the crack 20 at the place. In this case, for example, a simple flaw detector that does not include the main body frame 150, the guide roller 180, and the like in the flaw detector 100 used in the above-described preliminary flaw detection step S1 may be used.

The present invention is not limited to the above-described embodiment, and includes a form in which the above-described embodiment is modified and a form in which these forms are appropriately combined.
For example, the transmitting-side ultrasonic transducer 111 and the receiving-side ultrasonic transducer 121 according to some embodiments described above are single-transducer transducers, but may be double-transducer transducers. When the transmission-side ultrasonic transducer 111 is a two-transducer transducer, the transmission-side ultrasonic transducer 111 may be used only for transmitting ultrasonic waves, or may be used for transmitting and receiving ultrasonic waves. Similarly, when the receiving-side ultrasonic transducer 121 is a two-transducer transducer, the receiving-side ultrasonic transducer 121 may be used only for receiving ultrasonic waves or may be used for transmitting and receiving ultrasonic waves.

  In some embodiments described above, the main body frame 150 rotatably holds the four guide rollers 180. However, the main body frame 150 only needs to rotatably hold at least two guide rollers 180. That is, the flaw detection apparatus 100 may be configured so that the transmission-side probe 110 and the reception-side probe 120 are guided in the rolling direction of the guide roller 180 by at least two guide rollers 180.

  In some embodiments described above, the flaw detection apparatus 100 is configured so that the attitude of the holding unit 140 can take an attitude at an arbitrary angular position between the first attitude and the second attitude. May be changed to at least the first posture and the second posture.

  In the above description of the ultrasonic flaw detection method, the case where the flaw detection target is the rotor disk 1 of the turbine is described as an example, but the present invention is not limited to this. For example, the present invention does not have to have the blade groove 5 extending in the circumferential direction like the rotor disk 1, and may apply the present invention to ultrasonic inspection of a member having a groove extending linearly. . Further, the present invention may be applied to ultrasonic inspection of a member having no groove.

REFERENCE SIGNS LIST 1 rotor disk 2 disk surface 3 conical surface 5 blade groove 20 crack 100 flaw detector 102 controller 110 transmitter probe 111 transmitter ultrasonic transducer 111a housing 112 transmitter wedge member 113 cable 120 receiver probe 121 reception Side ultrasonic transducer 121a case 122 receiving side wedge member 123 cable 140 holding unit 150 body frame 160 adjusting unit 170 attitude changing unit 180 guide roller

(1) The ultrasonic testing method according to at least one embodiment of the present invention includes:
A transmitting probe configured so that a longitudinal ultrasonic wave propagates inside a flaw detection object at a fixed refraction angle of 30 degrees or more and 45 degrees or less, and receives an ultrasonic wave from the transmitting probe. placing the receiving side probe, along the extending direction of the grooves formed in the flaw detection object which,
Performing ultrasonic flaw detection by the TOFD method by the transmission-side probe and the reception-side probe arranged along the extending direction of the groove;
Is provided.

As described above, as a result of the inventor's intensive study, in the ultrasonic flaw detection by the TOFD method, the case where the direction in which the transmitting probe and the receiving probe are aligned and the direction in which the crack extends coincides with each other. However, it was found that a crack could be detected. Further, as a result of intensive studies by the inventors, when the direction in which the transmission-side probe and the reception-side probe are aligned and the direction in which the crack extends coincide with each other, a flaw detection method suitable for crack detection is used. It has been found that the incident angle of the ultrasonic wave in the object, that is, the refraction angle is 30 degrees or more and 45 degrees or less.
In this regard, in the method (1), the transmitting probe configured to transmit the longitudinal ultrasonic wave through the flaw detection target at a fixed refraction angle of 30 degrees or more and 45 degrees or less, The side probe is arranged along the direction in which the groove of the flaw detection target extends, and ultrasonic flaw detection by the TOFD method is performed. This makes it possible to detect a crack extending in the direction in which the transmitting probe and the receiving probe are arranged, that is, a crack extending in the same direction as the direction in which the groove of the flaw detection target extends. Therefore, even when there is a restriction on the arrangement of the probe and the transmission-side probe and the reception-side probe cannot be arranged along the direction intersecting the extending direction of the groove, the extending direction of the groove The crack extending in the same direction as the above can be detected by ultrasonic testing using the TOFD method.

(2) In some embodiments, in the method of the above (1), the step of arranging the transmission-side probe and the reception-side probe along the extending direction of the groove includes 30 degrees or more. The transmitting-side probe and the receiving-side probe, which are configured such that longitudinal ultrasonic waves propagate within the flaw detection target at the fixed refraction angle of 40 degrees or less, and the flaw detection target It is arranged along the extending direction of the groove formed in the object .

As a result of intensive studies by the inventors, when the direction in which the transmission-side probe and the reception-side probe are aligned and the direction in which the crack extends coincide with each other, a more suitable refraction angle is 30 degrees or more and 40 degrees or more. Degrees.
In this regard, the method (2) uses a transmitting probe configured so that longitudinal ultrasonic waves propagate through the flaw detection target at a fixed refraction angle of 30 degrees or more and 40 degrees or less. Thus, the ultrasonic flaw detection method is more suitable for detecting a crack extending in the same direction as the direction in which the groove of the flaw detection object extends.

As described above, the method (1) or (2) is suitable for detecting a crack extending in a direction in which the transmitting probe and the receiving probe are arranged. Therefore, according to the method (3), the crack extending in the direction in which the transmitting probe and the receiving probe are arranged, that is, extending in the same direction as the extending direction of the groove of the inspection object . Cracks can be detected by ultrasonic testing using the TOFD method.

(4) In some embodiments, in any one of the above methods (1) to (3),
The transmission-side probe has a wedge member,
In the step of performing ultrasonic testing by the TOFD method, as well as extending along a direction and the transmission-side probe and probe the receiving probe are aligned, opposed to the flaw detection object in the wedge member faces A planar crack extending in a direction perpendicular to the direction is detected.

As a result of intensive studies by the inventors, while extending along the direction in which the transmitting probe and the receiving probe are aligned, the wedge member extends in a direction orthogonal to the surface of the wedge member facing the inspection target . It has been found that a planar crack can be detected.
Therefore, according to the above method (4), the transmitting probe and the receiving probe extend in the direction in which the transmitting probe and the receiving probe are arranged, and extend in the direction orthogonal to the surface of the wedge member facing the inspection object . Can be detected.

Claims (13)

A transmitting probe configured so that a longitudinal ultrasonic wave propagates inside a flaw detection object at a fixed refraction angle of 30 degrees or more and 45 degrees or less, and receives an ultrasonic wave from the transmitting probe. And a receiving probe to be disposed along the extending direction of the groove formed in the flaw detection target member,
Performing ultrasonic flaw detection by the TOFD method by the transmission-side probe and the reception-side probe arranged along the extending direction of the groove;
An ultrasonic flaw detection method comprising: In the step of disposing the transmitting probe and the receiving probe along the extending direction of the groove, the longitudinal ultrasonic waves are fixed at a fixed refraction angle of 30 degrees or more and 40 degrees or less. 2. The transmission-side probe and the reception-side probe that are configured to propagate in the flaw detection target are arranged along an extending direction of a groove formed in the flaw detection target member. 3. The ultrasonic inspection method according to 1. The ultrasonic wave according to claim 1, wherein in the step of performing the ultrasonic flaw detection by the TOFD method, a crack extending along a direction in which the transmission-side probe and the reception-side probe are arranged is detected. Flaw detection method. The transmission-side probe has a wedge member,
In the step of performing the ultrasonic flaw detection by the TOFD method, a surface extending along a direction in which the transmission-side probe and the reception-side probe are arranged, and a surface of the wedge member facing the flaw detection target member The ultrasonic flaw detection method according to any one of claims 1 to 3, wherein a planar crack extending in a direction perpendicular to the direction is detected. In the step of performing the ultrasonic flaw detection by the TOFD method, the TOFD is performed while moving the transmission-side probe and the reception-side probe arranged along the extending direction of the groove along the extending direction of the groove. The ultrasonic flaw detection method according to any one of claims 1 to 4, wherein the ultrasonic flaw detection is performed by a method. Prior to performing the step of performing ultrasonic testing by TOFD, further comprising the step of adjusting the positions of the transmitting probe and the receiving probe in a direction orthogonal to the extending direction of the groove. Item 6. The ultrasonic flaw detection method according to Item 5. The flaw detection target is a rotor disk of a turbine,
The groove is a blade groove of the rotor disk, extends in a circumferential direction of the rotor disk,
The rotor disk has a disk surface oriented in a direction parallel to a rotation axis of the rotor disk,
In the step of disposing the transmitting probe and the receiving probe along the extending direction of the groove, the transmitting probe and the receiving probe may be extended by extending the wing groove. The ultrasonic inspection method according to claim 1, wherein the ultrasonic inspection method is arranged on the disk surface along a direction. The flaw detection target is a rotor disk of a turbine,
The groove is a blade groove of the rotor disk, extends in a circumferential direction of the rotor disk,
The rotor disk has a disk surface facing in a direction parallel to the rotation axis of the rotor disk, and a conical surface formed radially outward from the disk surface,
In the step of disposing the transmitting probe and the receiving probe along the extending direction of the groove, the transmitting probe and the receiving probe may be extended by extending the wing groove. The ultrasonic flaw detection method according to claim 1, wherein the ultrasonic flaw detection method is arranged on the conical surface along a direction. A transmitting-side probe having a transmitting-side ultrasonic transducer and a transmitting-side wedge member configured to transmit a longitudinal ultrasonic wave through a flaw detection target object at a fixed refraction angle of 30 degrees or more and 45 degrees or less. When,
Receiving-side ultrasonic transducer, and a receiving-side probe having a receiving-side wedge member,
A holding unit that holds the transmission-side probe and the reception-side probe facing each other,
A control device for performing ultrasonic flaw detection by the TOFD method using the transmission-side probe and the reception-side probe,
Flaw detection device comprising: At least two guide rollers,
A main body frame to which the holding portion is attached so that the guide roller is rotatably held, and the transmission probe and the reception probe are arranged along a guide direction by the guide roller. ,
The flaw detector according to claim 9, further comprising: An adjusting unit for adjusting a position of the holding unit in the main body frame in a direction intersecting the guide direction;
The flaw detector according to claim 10, further comprising: A first posture in which the holding unit is attached to the main body frame such that a direction in which the transmission-side probe and the reception-side probe are arranged in the same direction as the guiding direction, and the transmission-side probe The attitude of the holding part is changed to at least two attitudes, that is, a second attitude in which the holding part is attached to the main body frame, such that a direction in which the sensor and the receiving side probe are arranged is a direction orthogonal to the guiding direction. The flaw detector according to claim 10, further comprising a posture changing unit that can perform the operation. Each of the transmission-side ultrasonic transducer and the reception-side ultrasonic transducer has a columnar housing, and includes a cable that projects radially outward from a side surface of the housing.
The transmission-side ultrasonic transducer, in a plan view of the transmission-side probe and the reception-side probe, between the cable of the transmission-side ultrasonic transducer and a side surface of the housing of the reception-side ultrasonic transducer. Attached to the transmission-side wedge member so that the distance is within twice the thickness of the housing,
The receiving-side ultrasonic transducer, in the plan view, the distance between the cable of the receiving-side ultrasonic transducer and the side surface of the housing of the transmitting-side ultrasonic transducer is not more than twice the thickness of the housing. The method according to any one of claims 9 to 12, wherein the cable is attached to the reception-side wedge member so that the cable does not overlap with the cable of the transmission-side ultrasonic transducer in the plan view. Flaw detector.

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