JP6173636B1 - Ultrasonic inspection method and ultrasonic inspection apparatus - Google Patents

Abstract

To provide an ultrasonic inspection method capable of detecting the position and degree of a defect without arranging a probe at a position where a defect exists in a subject. An ultrasonic transmission probe 1 and a reception probe 2 are arranged on the same side with respect to the surface of the steel plate 4 in a steel plate 4 whose lower end portion is embedded in concrete 6 and in the same direction as each other. It is inclined at a certain downward position. The transmission probe 1 and the reception probe 2 are arranged with air interposed between the steel plate 4 and transmit and receive ultrasonic waves between the steel plate 4 and the air. The transmission probe 1 transmits a 400 kHz ultrasonic wave to propagate the plate wave to the steel plate 4, and the reflected wave of the ultrasonic wave reflected by the corroded portion 5 of the steel plate 4 is received by the reception probe 2. At the position where the presence of the corroded portion 5 is detected by the reflected wave of the plate wave, the transmitting probe 1 transmits an ultrasonic wave of 750 kHz to propagate the surface wave to the steel plate 4 and the ultrasonic wave reflected by the corroded portion 5 is transmitted. The reflected wave is received by the receiving probe 2, and the position and depth of the corroded portion 5 are detected based on the reflected wave of the surface wave. [Selection] Figure 1

Description

  The present invention relates to an ultrasonic inspection method and an ultrasonic inspection apparatus suitable for detecting, for example, corrosion occurring in a buried portion of a steel plate.

  Conventionally, in structures such as steel bridge piers, corrugated steel web girders, and lighting columns, where steel is in contact with concrete or the ground, rainwater is retained at the ground, where the steel is buried in the concrete or the ground. Corrosion is likely to occur. Nondestructive inspection is performed in order to evaluate the soundness of the ground part of such steel materials. Nondestructive inspections performed on the ground include eddy current inspection and ultrasonic inspection.

  In the eddy current flaw inspection, an eddy current is generated in a subject by a fluctuating magnetic field generated when an alternating current is applied to a coil, and a flaw is detected based on a change in the eddy current (see, for example, Patent Document 1). . The eddy current flaw inspection can be continuously performed in a non-contact manner without bringing the probe into contact with the steel material to be inspected.

  On the other hand, the ultrasonic inspection transmits ultrasonic waves to a subject and detects the presence or absence and position of damage based on the presence or absence and intensity of the transmitted wave or reflected wave. As a method of detecting damage to the ground part of the metal column based on the reflected wave of the ultrasonic wave, the intensity of the reflected wave of the ultrasonic wave transmitted from this probe is fixed to the ground part of the metal column. Is compared with the intensity of the reflected wave in a test piece prepared in advance, and there is a defect evaluation method for evaluating the presence and degree of corrosion at the ground (see, for example, Patent Document 2). In this defect evaluation method, the probe is fixed to the metal column via the contact medium, and the ultrasonic wave transmitted from the probe and propagating through the metal column is an SH wave.

JP 2000-310618 A JP 2013-160683 A

  However, since the eddy current flaw inspection needs to pass the probe to the position where the corroded portion exists, in order to detect the corrosion existing on the ground portion, the ground and concrete where the steel material is buried are removed. There is a need to. Therefore, there is a problem that the inspection takes time. Moreover, there is a problem that the strength of the structure is lowered by removing the concrete integrated with the steel material. Moreover, even if there is no abnormality in the inspection result, there is a problem that repair is required to recover the removed concrete. That is, even if the steel material is non-destructive, there is a problem that it is necessary to destroy a member that contacts the steel material. Even if the presence of corrosion can be detected by eddy current flaw detection, the depth of corrosion cannot be detected.

  In the defect evaluation method using ultrasonic waves, the probe is fixed to the metal column via the contact catalyst, so that the transmission direction of the ultrasonic waves is fixed. Therefore, in order to perform a wide range of flaw detection, it is necessary to repeat the fixing of the probe and the transmission and reception of ultrasonic waves in the target range, which is troublesome. In addition, the defect evaluation method using ultrasonic waves has a problem in that since the SH wave propagates to the metal column, the propagation speed of the ultrasonic waves is relatively slow, and it takes time to detect the defects.

  Therefore, an object of the present invention is to provide an ultrasonic inspection method capable of detecting the position and degree of a defect without arranging a probe at the position where the defect exists in the subject. It is another object of the present invention to provide an ultrasonic inspection method that does not require the probe to be fixed to the subject and that can quickly detect a wide range of defects in the subject with less effort.

In order to solve the above-described problem, the ultrasonic inspection method of the present invention includes a step of arranging an ultrasonic transmission probe and a reception probe on the same side of the surface of the subject so as to be inclined in the same direction. ,
A step of causing an ultrasonic wave of a first frequency to be incident on the subject from the transmission probe to the subject to generate a plate wave on the subject;
Receiving ultrasonic waves from the subject through the air with the receiving probe;
Determining the presence or absence of a defect in the subject based on the ultrasound received by the reception probe; and
When it is determined that the subject has a defect, a step of causing a ultrasonic wave of a second frequency to enter the subject from the transmission probe to the subject via air, and generating a surface wave on the subject;
Receiving ultrasonic waves from the subject through the air with the receiving probe;
And a step of detecting the position and / or depth of the defect of the subject based on the ultrasonic wave received by the reception probe.

  According to the above configuration, since the ultrasonic transmission probe and the reception probe are arranged on the same side of the surface of the subject and inclined in the same direction, the ultrasonic wave transmitted from the transmission probe is arranged. Can be detected based on the reflected wave reflected by the defect. Therefore, the defect of the subject can be detected without arranging the probe at the position where the defect of the subject exists. In addition, according to the present invention, since the transmission probe and the reception probe are arranged with air interposed between the subject and the probe, the conventional defect evaluation in which the probe is fixed to the subject with a contact catalyst. Compared to the method, it is possible to greatly reduce the labor of arranging the transmitting probe and the receiving probe. Further, a plate wave is propagated to the surface of the subject, and the presence or absence of a defect is determined based on the ultrasonic wave from the subject. When it is determined that there is a defect, an ultrasonic wave is transmitted from the transmission probe to propagate a surface wave to the subject, and the position and / or depth of the defect is detected based on the ultrasonic wave from the subject. Thus, the position and / or depth of the defect can be detected more quickly and efficiently than when the surface wave is generated at all positions to detect the defect. Here, the first frequency is a frequency for generating a plate wave in the subject, and is determined based on the plate thickness of the subject and the incident angle of the ultrasonic wave. The second frequency is a frequency that causes the subject to generate a surface wave, and is determined based on the incident angle of the ultrasonic wave.

  In an ultrasonic inspection method according to an embodiment, the subject has a contact portion in contact with another material, and a defect generated in the contact portion is detected.

  According to the above-described embodiment, it is possible to detect a defect existing in the propagation direction of the ultrasonic wave by using the transmission probe and the reception probe which are arranged on the same side of the surface of the subject and inclined in the same direction. Therefore, a defect in the contact portion can be detected by the transmission probe and the reception probe arranged in a portion other than the contact portion of the subject. In other words, non-destructive detection of the defect of the subject in a position where it cannot be directly observed due to the presence of another material by using a transmitting probe and a receiving probe arranged in a portion other than the contact portion. can do.

  In the ultrasonic inspection method according to one embodiment, the first frequency is 300 to 500 kHz, and the second frequency is 600 to 1000 kHz.

  According to the above embodiment, a plate wave can be formed on the subject with ultrasonic waves having a frequency of 300 to 500 kHz, and a surface wave can be formed on the subject with ultrasonic waves having a frequency of 600 to 1000 kHz. In particular, the first frequency for forming the plate wave is preferably 400 kHz, and the second frequency for forming the surface wave is preferably 750 kHz.

  The ultrasonic inspection method of one embodiment collects reception results of a reception probe when a plate wave is generated in a test body in which a simulated defect is formed in substantially the same material as the subject in advance, By comparing the reception result of the specimen with the reception result of the reception probe when a plate wave is generated in the subject, the presence or absence of the defect of the subject is estimated.

  According to the above-described embodiment, a test body in which a simulated defect is formed in substantially the same material as an object to be inspected is prepared in advance, and reception of a reception probe when a plate wave is generated in the test body is received. Collect the results. As the reception result of the test body, for example, the ultrasonic amplitude, peak value, and sound pressure distribution related to the coordinates set on the test body can be adopted. Compare the reception result of this specimen with the reception result of the reception probe when a plate wave is generated in the subject, and estimate the presence or absence of the specimen defect based on the presence or absence of the simulated defect in the specimen. can do.

  The ultrasonic inspection method of one embodiment collects reception results of a reception probe when a surface wave is generated in a test body in which a simulated defect is formed in substantially the same material as the subject in advance, By comparing the reception result of the specimen and the reception result of the reception probe when the surface wave is generated in the subject, the position and / or depth of the defect of the subject is estimated.

  According to the above-described embodiment, a test body in which a simulated defect is formed in substantially the same material as the subject to be inspected is prepared in advance, and reception of the reception probe when a surface wave is generated in the test body is received. Collect the results. As the reception result of the test body, for example, the ultrasonic amplitude, peak value, and sound pressure distribution related to the coordinates set on the test body can be adopted. The reception result of this specimen is compared with the reception result of the reception probe when the surface wave is generated in the subject, and based on the position and / or depth of the simulated defect of the specimen, The position and / or depth of the defect can be estimated.

  In one embodiment of the ultrasonic inspection method, the transmission probe and the reception probe are viewed along the main surface of the subject from the normal direction of the main surface, and the ultrasonic wave of the transmission probe is observed. The ultrasonic waves are transmitted and received sequentially at a plurality of locations in the middle of the movement.

  According to the embodiment, the transmission probe and the reception probe are viewed along the main surface of the subject from the normal direction of the main surface, and the transmission direction of the ultrasonic waves of the transmission probe is The main surface of the subject can be scanned by moving in a direction perpendicular to each other and sequentially transmitting and receiving ultrasonic waves at a plurality of locations in the middle of movement. Therefore, the examination of the subject can be performed efficiently. In particular, the presence or absence of a defect can be detected quickly and efficiently by propagating a plate wave to the subject for scanning. Here, when viewed from the normal direction of the main surface, the transmission direction of the ultrasonic waves of the transmission probe is the vertical direction, and the direction of moving the transmission probe and the reception probe is the horizontal direction. preferable. Further, the main surface of the subject is the surface of the plate when the subject is a flat plate, and the surface formed including the peaks of the corrugated plate when the subject is a corrugated plate. .

An ultrasonic inspection apparatus of the present invention is an ultrasonic inspection apparatus for executing the ultrasonic inspection method,
A transmission probe holder for holding the transmission probe in an adjustable and interchangeable manner with respect to the subject; and
A receiving probe holder for holding the receiving probe in an adjustable and interchangeable manner with respect to the subject; and
A transmission probe driving unit that drives the transmission probe so as to selectively generate a plate wave and a surface wave in the subject;
A casing to which the transmission probe holder and the reception probe holder are attached;
A moving unit that moves the casing in a direction perpendicular to the ultrasonic transmission direction of the transmission probe as viewed from the normal direction of the main surface along the main surface of the subject. It is said.

  According to the embodiment, the transmission probe is held by the transmission probe holder so that the inclination angle with respect to the subject can be adjusted and exchanged. In addition, the reception probe is held by the reception probe holder so that the inclination angle with respect to the subject can be adjusted and exchanged. The angle of the transmission probe held by the transmission probe holder is set to a predetermined angle, and a plate wave and a surface wave are selectively generated in the subject by the transmission probe driving unit. By driving the transmission probe, it is possible to selectively generate a plate wave and a surface on the subject according to conditions such as the thickness of the subject. Further, the transmission probe holder and the receiving probe holder attached to the casing are attached to the transmission probe as viewed from the normal direction of the main surface along the main surface of the subject by the moving unit. The main surface of the subject can be scanned by moving the child in a direction perpendicular to the transmission direction of the ultrasonic waves. Therefore, the examination of the subject can be performed efficiently. In particular, the presence or absence of defects can be detected quickly and efficiently by generating a plate wave and scanning the subject. Here, when viewed from the normal direction of the main surface, the transmission direction of the ultrasonic waves of the transmission probe is the vertical direction, and the direction of moving the transmission probe and the reception probe is the horizontal direction. preferable. Further, the main surface of the subject is the surface of the plate when the subject is a flat plate, and the surface formed including the peaks of the corrugated plate when the subject is a corrugated plate. .

It is a schematic diagram explaining the ultrasonic inspection method of embodiment of this invention. It is a side view which shows the ultrasonic inspection apparatus of embodiment. It is a rear view which shows the ultrasonic inspection apparatus of embodiment. It is sectional drawing which shows the transmission probe holding body and reception probe holding body with which an ultrasonic inspection apparatus is provided. It is a block diagram which shows the ultrasonic inspection apparatus of embodiment. It is a figure which shows a mode that a test object is test | inspected with an ultrasonic inspection apparatus. It is an image which shows distribution of the crest value of an ultrasonic wave when a surface wave is generated in a subject. It is sectional drawing which shows a test body. It is a front view which shows a test body. It is an image which shows distribution of the crest value of an ultrasonic wave when generating a surface wave in a test object.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram for explaining an ultrasonic inspection method according to an embodiment of the present invention. As the ultrasonic inspection method of the embodiment, in the case where the position and depth of the corrosion 5 generated in the embedded portion including the subsurface portion is detected in a nondestructive manner with respect to the steel plate 4 as the subject in which the lower end portion is embedded in the concrete 6 Will be described.

  In the ultrasonic inspection method of the present embodiment, the ultrasonic transmission probe 1 and the reception probe 2 are arranged at a predetermined height from the surface of the concrete 6 of the steel plate 4. The transmission probe 1 and the reception probe 2 are arranged on the same side with respect to the surface of the steel plate 4, and are inclined downward in the same direction. The transmission probe 1 and the reception probe 2 are arranged with air interposed between the steel plate 4 and ultrasonic waves between the transmission probe 1 and the reception probe 2 and the steel plate 4 via the air. Send and receive. The transmission probe 1 and the reception probe 2 perform so-called airborne ultrasonic flaw detection in which flaw detection is performed with ultrasonic waves transmitted and received between the steel plate 4 and air. The transmission probe 1 receives the drive signal and transmits an ultrasonic wave of a burst wave formed by a rectangular wave having a predetermined frequency as indicated by a symbol A.

  The receiving probe 2 receives the reflected wave of the ultrasonic wave reflected by the end of the steel plate 4 and the reflected wave of the ultrasonic wave reflected by the corroded part 5 as a defect of the steel plate 4 as indicated by reference numeral B. Since the transmission probe 1 and the reception probe 2 are arranged in the same direction with respect to the steel plate 4, the steel plate 4 is located more than the arrangement position of the transmission probe 1 and the reception probe 2 of the steel plate 4. It is possible to detect the corroded portion 5 located in the extending direction of the base plate based on the reflected wave from the corroded portion 5. Even if the corroded portion 5 of the steel plate 4 exists in the concrete 6, the corroded portion 5 can be detected without any problem by the reflected wave of the ultrasonic wave traveling in the extending direction of the steel plate 4 from the transmission probe 1.

  In the ultrasonic inspection method of the present embodiment, two types of ultrasonic waves, a plate wave and a surface wave, are propagated through the steel plate 4 to detect the position and depth of the corroded portion 5. First, an ultrasonic wave is transmitted from the transmission probe 1 to the steel plate 4 to generate a plate wave, and the reflected wave of this plate wave is received by the reception probe 2, and based on the reception result of the reception probe 2. The presence or absence of defects in the steel plate 4 is detected. The plate wave is a guide wave that propagates through a flat plate or rod-like material, and is an ultrasonic wave that is propagated by superimposing a plurality of modes. The plate wave can be generated in the steel plate 4 by adjusting the incident angle of the ultrasonic wave and the frequency to a predetermined value according to the plate thickness of the steel plate 4. The frequency which produces | generates a plate wave on the steel plate 4 is the 1st frequency of this invention. The first frequency transmitted by the transmission probe 1 is preferably 300 to 500 kHz, and particularly preferably 400 kHz. The transmission probe 1 transmits ultrasonic waves in a direction inclined downward in a side view of the steel plate 4, thereby generating a plate wave that travels vertically downward on the steel plate 4. When the plate wave is propagated to the steel plate 4, the reception probe 2 receives the reflected wave reflected by the corroded portion 5 and the reflected wave reflected by the lower end of the steel plate 4. Due to the difference in transmission time between the reflected wave from the corroded portion 5 and the reflected wave at the lower end of the steel plate 4, defects such as the corroded portion 5 present on the transmission probe 1 side from the lower end of the steel plate 4 can be detected. .

  When the presence of a defect is detected by a plate wave, a surface wave is advanced to the steel plate 4 at the position where the defect is detected, and the position and depth of the defect are detected. That is, the plate wave transmission probe 1 is replaced with a surface wave transmission probe 1 and the plate wave reception probe 2 is replaced with a surface wave reception probe 2. An ultrasonic wave is generated from the exchanged surface wave transmission probe 1 to the steel plate 4 to generate a surface wave, and the reflected wave of the surface wave is received by the reception probe 2 and received by the reception probe 2. Based on the result, the position and depth of the defect in the steel plate 4 are detected. Surface waves are ultrasonic waves that propagate through the surface of the subject, and detect the position and depth of defects more accurately than plate waves based on the reflected waves reflected by the defects present on the surface on the propagation side. can do. The surface wave can be generated on the steel plate 4 by adjusting the incident angle and frequency of the ultrasonic wave to predetermined values. The frequency at which the surface wave is generated on the steel plate 4 is the second frequency of the present invention. The second frequency transmitted by the transmission probe 1 is preferably 600 to 1000 kHz, and particularly preferably 750 kHz.

  In the ultrasonic inspection method of the present embodiment, the steel plate 4 is subjected to a primary inspection using a plate wave, and the details of the defect are detected by performing a secondary inspection using a surface wave at a position where a defect is detected in the primary inspection. The primary inspection is a process of detecting the presence or absence of defects below the incident position by propagating the ultrasonic wave vertically downward from the ultrasonic wave incident position of the steel plate 4 in the horizontal direction of the transmitting probe 1 and the receiving probe 2. The steel plate 4 is scanned by repeating alternately with the movement to. That is, the step of transmitting and receiving the ultrasonic wave plate in the vertical direction and the step of moving the transmission probe 1 and the reception probe 2 in the horizontal direction perpendicular to the transmission direction of the ultrasonic wave are repeated. 4 scans are performed. Since the plate wave is reflected by both a defect present on the front side surface where the transmission probe 1 of the steel plate 4 is present and a defect present on the back side surface, if scanning is performed on the front side surface of the steel plate 4, a defect on both sides is detected. Can be detected. On the other hand, the surface wave can only detect defects on one surface of the steel plate 4, but if it is limited to the position where the defects were detected by the plate wave by the primary inspection, both the front side surface and the back side surface by the surface wave by the secondary inspection. Even if the inspection is performed, the position and depth of the defect can be detected with less effort than inspecting all the front and back surfaces with surface waves.

  In addition, since the secondary inspection is performed only at the position where the defect is detected in the primary inspection after the primary inspection by the plate wave, the entire steel plate 4 is inspected by the plate wave having a relatively high propagation speed. Therefore, the limited portion is inspected with a surface wave having a relatively low propagation velocity. Therefore, it is possible to perform inspection with the same accuracy as when all the surfaces are inspected in a shorter time than when all the surfaces are inspected.

  In the ultrasonic inspection method of the present embodiment, the transmitting probe 1 and the receiving probe 2 are arranged with air interposed between the steel plate 4 and the probe is attached to the steel plate 4 with a contact catalyst. There is no need to fix. Therefore, a step of propagating ultrasonic waves from the transmission probe 1 in the vertical direction and receiving a reflected wave by the reception probe 2, and a step of moving the transmission probe 1 and the reception probe 2 in the horizontal direction. Repeating can be performed with little effort. As a result, the steel plate 4 can be easily scanned by the transmission probe 1 and the reception probe 2.

  FIG. 2 is a side view illustrating the ultrasonic inspection apparatus according to the embodiment, and FIG. 3 is a front view illustrating the ultrasonic inspection apparatus according to the embodiment. The ultrasonic inspection apparatus of the present embodiment is for carrying out the ultrasonic inspection method. The ultrasonic inspection apparatus 10 includes a transmission probe 1 that transmits ultrasonic waves, a reception probe 2 that receives ultrasonic waves, a casing 11 that houses the transmission probe 1 and the reception probe 2, and A wheel 12 provided at the lower end of the casing 11, a handle 13 for applying a force for moving the casing 11, and a level 15 for displaying the attitude of the casing 11 are provided. Further, a fixed portion 21 fixed to the steel plate 4 as a subject by magnetic force, a rail 20 supported by the fixed portion 21, and a guided portion guided along the rail 20 while being fitted to the rail 20. And a link 17 that connects the guided portion 18 and the upper portion of the casing 11. The link 17 connects the guided portion 18 and the casing 11 so that the casing 11 can swing in a plane perpendicular to the rail 20. The rail 20, the guided portion 18 and the wheel 12 constitute a moving portion of the present invention.

FIG. 4 is a cross-sectional view showing the transmission probe 1 and the reception probe 2 housed in the casing 11 and a holding body for holding the transmission probe 1 and the reception probe 2. This holding body serves as both a transmission probe holding body and a receiving probe holding body. The holding body includes a holding frame 25 that accommodates the transmission probe 1 and the receiving probe 2 so that ultrasonic waves can be transmitted and received, and the transmission probe 1 and the receiving probe that are provided in the holding frame 25. There is a shielding wall 26 that shields ultrasonic waves between the two. The holding frame 25 is connected to an opening provided in the casing 11 of the ultrasonic inspection apparatus 10, and an opening through which an ultrasonic wave transmitted and received by the transmission probe 1 and the reception probe 2 passes, and is transmitted to the opening. It has a storage chamber for storing the probe 1 and the reception probe 2. Screw holes for fixing the transmission probe 1 and the reception probe 2 are provided on the sides of the holding frame 25. Two screw holes are provided on the side surface corresponding to each of the transmission probe 1 and the reception probe 2, and the position of the screw to be inserted is adjusted in one of the two screw holes. It is formed in a possible long hole. By adjusting the position of the screw inserted through the long hole and screwing and fastening to the transmission probe 1 and the reception probe 2, respectively, the inclination angle of the transmission probe 1 and the reception probe 2 can be adjusted. It is adjustable. Thereby, the emission angle θ _{1 of the} ultrasonic wave from the transmission probe ₁ with respect to the horizontal direction and the incident angle θ _{2 of the} ultrasonic wave to the reception probe 2 with respect to the horizontal direction can be adjusted. A shielding wall 26 is provided between a portion in the holding frame 25 that accommodates the transmission probe 1 and a portion that accommodates the reception probe 2, so that ultrasonic waves transmitted from the transmission probe 1 are received. Direct transmission to the probe 2 is prevented.

  FIG. 5 is a block diagram illustrating the ultrasonic inspection apparatus according to the embodiment. The ultrasonic inspection apparatus 10 includes a signal generator 31 that generates a rectangular wave burst signal for driving the transmission probe 1, a processing device 32 that controls the signal generator 31, and a transmission probe 1 that transmits the signal. An input unit 33 is provided for receiving an input for setting an ultrasonic wave to be received from an operator. The signal generator 31 and the processing device 32 constitute a transmission probe driving unit that drives the transmission probe 1. The transmission probe driving unit configured to include the signal generation unit 31 and the processing device 32 can drive both the transmission probe 1 that generates a plate wave and the transmission probe 1 that generates a surface wave. Is formed. In other words, the setting is performed by exchanging the transmission probe 1 so that the plate wave and the surface wave can be selectively transmitted. Corresponding to the exchange of the transmission probe 1, the reception probe 2 is also exchanged for a plate wave and a surface wave, so that a plate wave and a surface wave can be selectively received. In addition, an amplifier 34 that amplifies the ultrasonic waves received by the reception probe 2 and an A / D converter 35 that digitizes the reception signals of the amplified ultrasonic waves are provided. The ultrasonic reception signal digitized by the A / D converter 35 is stored in the storage device 37 by the processing device 32. The ultrasonic reception signal stored in the storage device 37 is read into a computer in which an analysis program is installed, analyzed, and an analysis result image such as a peak value distribution is output to the display device.

  Next, a case where the ultrasonic inspection apparatus 10 having the above configuration is used to inspect the ground portion of the steel plate 4 whose lower end is embedded in the concrete 6 will be described. First, as shown in FIG. 6, the rail 20 is fixed to the surface which is the main surface of the steel plate 4 by the fixing portion 21. The rail 20 is fixed so as to be parallel to the surface of the concrete 6. Subsequently, the transmission probe 1 for generating a plate wave is attached to the holding frame 25 in order to perform a primary inspection. At this time, the mounting angle of the transmission probe 1 is adjusted based on the thickness of the steel plate 4 and the frequency of ultrasonic waves to be transmitted. Further, the reception probe 2 is attached to the holding frame 25, and the attachment angle is adjusted. Subsequently, the frequency transmitted by the transmission probe 1 is input and set by the input unit 33. In the case of the primary inspection, the transmission frequency is set to 400 kHz, for example.

  When the preparation for the primary inspection is thus completed, the guided portion 18 of the ultrasonic inspection apparatus 10 is fitted to the rail 20, and the ultrasonic inspection apparatus 10 is disposed on one end side of the rail 20. Subsequently, the start of the primary inspection is input to the input unit 33, and the operator holds the handle 13 and moves the ultrasonic inspection apparatus 10 along the rail 20. The operator checks the level 15 and moves the ultrasonic inspection apparatus 10 while holding the casing 11 horizontally. As indicated by an arrow D, the moving direction of the ultrasonic inspection apparatus 10 is perpendicular to the direction of the arrow A1, which is the ultrasonic transmission direction of the transmission probe 1 viewed from the normal direction of the surface of the steel plate 4. Direction. When the start of the primary inspection is input to the input unit 33, a drive signal is output from the signal generation unit 31 to the transmission probe 1 under the control of the processing device 32, and the transmission probe 1 is set to 400 kHz according to this. Transmits ultrasonic waves of burst waves consisting of rectangular waves. The ultrasonic wave transmitted from the transmission probe 1 is input to the steel plate 4 at a predetermined inclination angle, and the plate wave propagates to the steel plate 4. A reflected wave reflected by the lower end of the steel plate 4 or a defect is received by the reception probe 2, amplified by the amplifier 34, converted into a digital signal by the A / D converter 35, and stored in the storage device 37. Is done. The reception signal of the reception probe 2 is stored in association with the position information of the ultrasonic inspection apparatus 10. The position information of the ultrasonic inspection apparatus 10 is specified by the number of rotations of the wheel 12, the position detection information of the guided portion 18, and the like. The main surface of the steel plate 4 is scanned by repeatedly transmitting the ultrasonic wave of the transmission probe 1 and receiving the reflected wave of the reception probe 2 while moving the ultrasonic inspection apparatus 10 along the rail 20. To do. When the ultrasonic inspection apparatus 10 reaches the other end of the rail 20, the operator ends the movement of the ultrasonic inspection apparatus 10 by the handle 13 and inputs the end of the primary inspection through the input unit 33.

  When the primary inspection is completed, the reception signal of the reception probe 2 is read from the storage device 37 to the computer, and the reception signal is analyzed by the computer to detect the presence or absence of corrosion as a defect. FIG. 7 is an image showing an inspection result by the primary inspection. FIG. 7 is an image showing the distribution of the peak values of ultrasonic waves received in the scanning range of the steel plate 4 by color tone. The peak value of the received ultrasonic wave is represented by the ratio (%) to the peak value of the transmitted ultrasonic wave, and the ratio value of the peak value corresponding to the color tone is described as a legend at the top of FIG. ing. In FIG. 7, the horizontal axis is the horizontal position of the steel plate 4, the origin is one end of the rail 20, and the horizontal end of the steel plate 4 in FIG. 6 is shown. The vertical axis is the vertical position of the steel plate 4, and the origin indicates the lower end of the steel plate 4. According to the crest value distribution, there is a portion in which the crest value of the received wave with respect to the transmitted wave is 50% or more in the range of about 50 mm to 150 mm from the lower end of the steel plate 4, thereby presuming the presence of corrosion of the steel plate 4. The

  The detection of defects using reflected waves of plate waves has a relatively low position and depth detection accuracy, so that the position and depth of defects can be identified with high accuracy in the areas where thickness reduction is detected in the primary inspection. Second inspection by surface wave. First, the transmission probe 1 and the reception probe 2 for generating surface waves are attached to the holding frame 25, and the attachment angle of the transmission probe 1 is based on the thickness of the steel plate 4 and the frequency of ultrasonic waves to be transmitted. Adjust. Subsequently, the frequency transmitted by the transmission probe 1 is set to a value that generates a surface wave on the steel plate 4 by the input unit 33. For example, the transmission frequency is set to 750 kHz. And the range where the reduction | decrease in the thickness of the steel plate 4 was detected is set as an object range of a secondary inspection.

  When the preparation for the secondary inspection is thus completed, the ultrasonic inspection apparatus 10 is fitted to the rail 20, and the ultrasonic inspection apparatus 10 is disposed at a position where the reduction in the thickness of the steel plate 4 is detected in the primary inspection. Subsequently, the start of the secondary inspection is input to the input unit 33, and the operator holds the handle 13 and moves the ultrasonic inspection apparatus 10 along the rail 20. When the start of the secondary inspection is input, a control signal is output from the signal generator 31 to the transmission probe 1 under the control of the processing device 32, and the transmission probe 1 responds to the rectangular wave of 750 kHz accordingly. Sends burst wave ultrasound. The ultrasonic wave transmitted from the transmission probe 1 is input to the steel plate 4 at a predetermined inclination angle, and the surface wave propagates to the steel plate 4. The surface wave propagating to the steel plate 4 is reflected by the lower end of the steel plate 4 and the corroded portion, and this reflected wave is received by the receiving probe 2. The reflected wave received by the reception probe 2 is amplified by the amplifier 34, converted into a digital signal by the A / D converter 35, and stored in the storage device 37. The reception signal of the reception probe 2 is stored in association with the position information of the ultrasonic inspection apparatus 10. When the processing device 32 detects the passage of the target range of the secondary inspection based on the position information, the transmission of the ultrasonic wave from the transmission probe 1 is stopped and the secondary inspection is ended. The ultrasonic wave may be stopped by an operator's operation.

  When the secondary inspection is completed, the reception signal of the reception probe 2 is read from the storage device 37 to the computer, and the reception signal is analyzed by the computer to detect the position and depth of corrosion as a defect. As in the primary inspection, the result of the secondary inspection is preferably shown as an image representing the distribution of the peak values of the ultrasonic waves received by the receiving probe 2 in color tone. By the secondary inspection using the surface wave, the position and depth of corrosion of the steel plate 4 can be accurately detected.

  In the secondary inspection using the surface wave, when no defect is detected in the received signal obtained by arranging the transmission probe 1 and the reception probe 2 on one surface of the steel plate 4, the transmission probe is disposed on the other surface. The child 1 and the receiving probe 2 are arranged to obtain a received signal. This is because the plate wave is transmitted through the entire steel plate 4 so that a defect on both sides can be detected. However, since the surface wave is transmitted through only one surface of the steel plate 4, the transmission probe 1 is applied to the surface where the defect exists. This is because it is necessary to dispose the reception probe 2 and propagate the ultrasonic waves.

  In the ultrasonic inspection method of the present embodiment, the received signal from the reception probe 2 indicates the peak value of the reflected wave, and the presence / absence, position, and depth of a defect are detected based on the distribution of the peak value. . In order to detect the presence / absence, position, and depth of a defect based on the reception result of the reception probe 2 as described above, the reception result is calibrated using a test specimen in advance. FIG. 8 is a cross-sectional view showing the test body, and FIG. 9 is a front view showing the test body. The test body 40 is formed of a rectangular steel plate, and a circular concave portion 41 having a diameter H simulating corrosion is formed at the center of the lower portion in a front view. The recess 41 has an arcuate contour having a maximum depth d as shown in the sectional view. The concave portion 41 having an arc-shaped cross section is set so that the reflection form of the ultrasonic wave is close to the corroded portion by simulating the corrosion in which the cross section of the boundary with the healthy portion forms a gentle angle. Through holes 42 are provided on both sides below the recess 41, and the through holes 42 simulate through corrosion.

  FIG. 10 is a diagram illustrating a reception result of the reception probe 2 when the test body 40 is inspected by the ultrasonic inspection apparatus 10. This reception result is an image showing the distribution of the peak values of the reflected waves received by the reception probe 2 in the scanning range of the test body 40 in the same manner as in FIG. As in FIG. 7, the ratio of the crest value corresponding to the color tone is shown as a legend at the top of FIG. The scanning of the test body 40 was performed by moving the ultrasonic inspection apparatus 10 in the horizontal direction to the upper part of the test body 40 while transmitting the ultrasonic wave toward the lower inclined direction by the transmission probe 1. In FIG. 10, the horizontal axis represents the horizontal position of the test body 40, and the origin represents the left end in the horizontal direction. The vertical axis represents the vertical position of the test body 40, and the origin is set to the position where the ultrasonic wave is incident on the test body 40. The lower end of the vertical axis corresponds to the lower end of the test body 40. As shown in the reception result of FIG. 10, according to the peak value distribution of the reception result, about 110 mm to 175 mm downward from the ultrasonic incident position of the test body 40 and 160 mm to 190 mm from the left end of the test body 40. In the range, there is a high peak value region 51 corresponding to the recess 41 where the peak value of the received wave is 50% of the transmitted wave. Thereby, it turns out that the increase in the crest value corresponds to the decrease in the thickness of the depth d. In the reception result of FIG. 10, 52 is an increasing region of the peak value corresponding to the reflected wave at the lower end of the test body 40, and 53 is an increasing region of the peak value corresponding to the reflected wave at the through hole.

  As described above, the ultrasonic inspection method according to the present embodiment calibrates the reception result of the reception probe 2 with the test body 40 that simulates corrosion as a defect, so that the position and depth of corrosion are good. Can be detected with high accuracy.

  In the above embodiment, the operator grips the handle 13 and moves the ultrasonic inspection apparatus 10. However, the ultrasonic inspection apparatus 10 is provided with a drive device that drives the wheels 12, and the processing device 32 controls the drive device. The wheels 12 may be driven to move the ultrasonic inspection apparatus 10.

  Further, in the above embodiment, the presence / absence, position and depth of a defect are detected based on the distribution of peak values as the reception result of the reception probe 2, but the presence / absence of the defect and position based on the distribution of amplitude and sound pressure. And the depth may be detected.

  Moreover, in the said embodiment, although the corrosion of the part covered with the concrete 6 of the steel plate 4 was detected as a test object, the corrosion of the part covered with the ground of the steel plate, or the defect of the part covered with the weld bead of the steel plate Can also be detected. Further, the subject may be a corrugated sheet, a cylindrical body, a box-shaped body, or the like other than the plate-shaped body such as the steel plate 4. When the object is a corrugated plate, the surface formed including the ridges of the corrugated plate is a main surface, and the transmission probe 1 and the reception probe of the ultrasonic inspection apparatus 10 are parallel to the main surface. The object may be scanned by moving 2.

DESCRIPTION OF SYMBOLS 1 Transmission probe 2 Reception probe 4 Steel plate 5 Corrosion part 6 Concrete 10 Ultrasonic inspection apparatus 11 Casing 12 Wheel 13 Handle 15 Level 17 Link 18 Guided part 20 Rail 21 Fixing part 25 Holding frame 26 Shielding wall 31 Signal Generation unit 32 Processing device 33 Input unit 34 Amplifier 35 A / D converter 37 Storage device

Claims (8)

A step of arranging an ultrasonic transmission probe and a reception probe on the same side of the surface of the subject and being inclined in the same direction;
A step of causing an ultrasonic wave of a first frequency to be incident on the subject from the transmission probe to the subject to generate a plate wave on the subject;
Receiving ultrasonic waves from the subject through the air with the receiving probe;
Determining the presence or absence of a defect in the subject based on the ultrasound received by the reception probe; and
When it is determined that the subject has a defect, a step of causing a ultrasonic wave of a second frequency to enter the subject from the transmission probe to the subject via air, and generating a surface wave on the subject;
Receiving ultrasonic waves from the subject through the air with the receiving probe;
And a step of detecting a position and / or depth of a defect of the subject based on an ultrasonic wave received by the reception probe. The ultrasonic inspection method according to claim 1,
An ultrasonic inspection method characterized in that the subject has a contact portion in contact with another material, and a defect generated in the contact portion is detected. The ultrasonic inspection method according to claim 1,
The ultrasonic inspection method, wherein the first frequency is 300 to 500 kHz, and the second frequency is 600 to 1000 kHz. The ultrasonic inspection method according to claim 1,
The reception results of the reception probe when a plate wave is generated in a test body in which a simulated defect is formed in substantially the same material as the object are collected in advance, and the reception result of the test object and the test object are collected. An ultrasonic inspection method, wherein the presence or absence of a defect in the subject is estimated by comparing a reception result of a reception probe when a plate wave is generated in the subject. The ultrasonic inspection method according to claim 1,
The reception results of the reception probe when a surface wave is generated in a test body in which a simulated defect is formed in substantially the same material as the subject are collected in advance, and the reception result of the test body and the test object are collected. An ultrasonic inspection method characterized in that the position and / or depth of a defect of the subject is estimated by comparing a reception result of a receiving probe when a surface wave is generated on the subject. The ultrasonic inspection method according to claim 1,
The transmission probe and the reception probe are moved along the main surface of the subject in a direction perpendicular to the ultrasonic transmission direction of the transmission probe as viewed from the normal direction of the main surface. An ultrasonic inspection method characterized by sequentially transmitting and receiving ultrasonic waves at a plurality of locations in the middle of movement. An ultrasonic inspection apparatus for inspecting the ground part of a subject ,
The transmission probe holds the adjustable capacity of the inclination angle with respect to the subject, transmitting probe holder to replaceably retain and transmit probe for transmitting probe and a surface wave for plate waves When,
The receiving probe holds the adjustable capacity of the inclination angle with respect to the subject, the receiving probe holder to replaceably retain and receiving probe for receiving probe and surface wave for plate waves When,
Both the plate wave transmission probe and the surface wave transmission probe can be driven, and a signal generator for generating a rectangular wave burst signal for driving the transmission probe is provided. a, a transmission probe driving unit for driving the transmission probe to selectively generate a plate wave and surface wave to the subject,
A casing to which the transmission probe holder and the reception probe holder are attached;
A moving unit that moves the casing in a direction perpendicular to the ultrasonic transmission direction of the transmission probe as viewed from the normal direction of the main surface along the main surface of the subject. Ultrasonic inspection equipment. The ultrasonic inspection apparatus according to claim 7,
The moving part is
Wheels provided at the lower end of the casing;
A fixed part fixed to the subject by magnetic force,
A rail supported by the fixed part;
A guided portion that is guided along the rail while being fitted to the rail;
A link connecting the guided part and the upper part of the casing so that the casing can swing in a plane perpendicular to the rail;
An ultrasonic inspection apparatus characterized by comprising:

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