JP2017187290A - Nondestructive inspection device for steel material and nondestructive inspection method for steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device and an inspection method which evaluate the situation of corrosion or damage of a steel material using sound waves by a nondestructive, noncontact and high spatial resolution.SOLUTION: A nondestructive inspection device 100 includes: a sound wave generation section 10 which irradiates a steel material 90 in a matrix 80 selected from a group of cement paste, mortar and concrete, with sound wave pulses; a sound wave medium 30 which is provided between the matrix and the sound wave generation section; and an electromagnetic signal reception section 20 which receives an electromagnetic signal generated from the steel material by the sound wave pulses. In addition, in the nondestructive inspection device, the electromagnetic signal is separated in time from electromagnetic noise by arranging the sound wave generation section so that a time when sound wave pulses propagate a distance between the sound wave generation section and the steel material is made longer than a duration time for the electromagnetic noise generated from the sound wave generation section, and a contact surface between the sound wave generation section and a sound wave medium is inclined to the interface so that an interface echo between the sound wave medium and the matrix does not return to the sound wave generation section.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a nondestructive inspection device for steel and a nondestructive inspection method for steel.

  Many social infrastructures built during the period of high economic growth in Japan decades ago are approaching their design life. For example, many bridges completed in the 1970s are approaching the design life of 50 years. Further, even in the case of a reinforced concrete (hereinafter also referred to as “RC”) structure, which has been considered to have a long life compared to steel, the problem of deterioration has become apparent. For example, the risk of falling surface concrete due to corrosion expansion of rebars is already a reality. Therefore, it can be said that it is an urgent task in modern society to quickly grasp such social infrastructure structure or material deterioration and take countermeasures.

  As one specific example, an RC structure is taken up. Although it is an RC structure that has been said to be maintenance-free, the reinforcing bars inside the concrete can be deteriorated due to corrosion such as salt damage even if the concrete is not cracked or peeled off. Further, not only corrosion but also a case where the reinforcing bar is damaged due to stress concentration due to some cause. However, the conventional evaluation of the corrosion of the steel material disposed inside the concrete had to rely on an indirect investigation of changes in the appearance of the concrete such as cracks, delamination, abrasion, or the presence of erosion. For this reason, it is not only in the industrial world but also in society to quickly realize a non-destructive and highly accurate inspection device or inspection method even when the appearance change is not visually recognized, difficult to visually recognize, or does not appear. There is a strong demand for the whole.

  Note that Patent Document 1 and Non-Patent Documents 1 and 2 disclose a measurement method and apparatus related to a general magnetic material. However, in a situation where the object to be measured (steel material) is embedded in a solid material (matrix) that is different from the object, such as steel arranged inside a matrix typified by concrete, the object to be measured However, there is no disclosure or suggestion of a measuring apparatus and a measuring method for measuring only the measurement with high accuracy.

International Publication No. WO2007 / 055057 Pamphlet

Hisato Yamada et al., `` Magnetic Sensing via Ultrasonic Excitation '', Review of Scientific Instruments, 2013, 84, 044903, pp1-5 Hisato Yamada et al., `` Magnetic hysteresis and magnetic flux patterns measured by acoustically stimulated electromagnetic response in a steel plate '', Japanese Journal of Applied Physics, 2015, 54, 086601, pp1-4

  Needless to say, the maintenance and maintenance of social infrastructure requires an enormous amount of budget and time. Therefore, in order to maintain and repair various infrastructures within a limited budget and time, it will not be possible to carry out repairs after the confirmation of cracks or debonding. It is desirable to perform maintenance and repair.

  However, as described above, there is no means to measure or evaluate the corrosion or damage of steel materials represented by iron in a non-destructive manner, that is, directly, without cracks and peeling. It was.

  As shown in Patent Document 1 and Non-Patent Documents 1 and 2, some of the inventors of the present application have already created a nondestructive measurement method using an acoustically induced electromagnetic signal (also referred to as “acoustically induced electromagnetic wave”). However, it has been found that it is difficult to realize highly accurate measurement even if the measuring device or method using the acoustically induced electromagnetic signal is directly applied to a steel material having an RC structure.

  For example, for a special object to be measured such as a steel material arranged inside a matrix such as concrete, it is necessary to consider the difference in the situation, material, etc. of the special object to be measured. Therefore, the present inventor conducted intensive research and analysis, and, as a result of repeated trial and error, found a characteristic device and method that considered the situation in which the object to be measured was embedded in a different solid material. As a result, it has been found that it is possible to realize a non-destructive and highly accurate inspection apparatus or inspection method that avoids the generation of various noises that may occur due to the presence of the matrix or that does not affect the reception of the signal to be measured. The above-mentioned knowledge obtained by the inventors of the present application, for example, does not appear in the appearance in the deterioration process of the RC structure, but is directly applied to the steel material at a time called “advanced phase” in which corrosion of the steel material inside the matrix is progressing. Measurement can be realized nondestructively. The present invention was created based on the above viewpoint.

  One non-destructive inspection apparatus for a steel material according to the present invention includes a sound wave generator that irradiates a steel material provided in at least one matrix selected from the group of cement paste, mortar, and concrete with a sound wave pulse, A sound wave medium provided at a position sandwiched between the matrix and the sound wave generation unit during irradiation of the sound wave pulse, an electromagnetic signal reception unit that receives an electromagnetic signal generated from the steel material by the sound wave pulse, and Is provided. In addition, this non-destructive inspection apparatus is such that the time during which the sound wave pulse propagates through the distance between the sound wave generator and the steel material is longer than the duration of electromagnetic noise generated from the sound wave generator. As described above, the electromagnetic wave receiving unit is disposed away from the steel material via the matrix and the acoustic wave medium, so that the electromagnetic signal receiving unit is temporally separated from the electromagnetic noise. The sound wave generation unit is configured to receive an electromagnetic signal and prevent the interface echo formed by the reflection of the sound wave pulse at the interface between the sound wave medium and the matrix from returning to the sound wave generation unit. The contact surface with the sonic medium is inclined with respect to the aforementioned interface.

  According to this nondestructive inspection apparatus, the object to be measured (steel material) is embedded in a solid material (matrix) that is different from the object to be measured like the steel material arranged inside the matrix. However, the electromagnetic signal (measurement target signal) generated from the steel material can be measured with high accuracy. In particular, since the contact surface between the sound wave generation unit and the sound wave medium is inclined with respect to the interface between the sound wave medium and the matrix, the interface echo returns to the sound wave generation unit. Generation of electromagnetic noise can be avoided. Therefore, if there is a thickness (distance) of the sonic medium enough to temporally separate electromagnetic noise generated when a sound wave pulse is generated from the sound wave generation unit, or a distance from the sound wave generation unit to the steel material to be measured Therefore, the measurement target signal can be acquired with high accuracy. This greatly increases the degree of freedom of the inspection environment in this nondestructive inspection apparatus. In addition, the matrix and the matrix so that the time during which the sound wave pulse propagates the distance between the sound wave generating unit and the steel material to be measured is longer than the duration of the electromagnetic noise generated from the sound wave generating unit. Since the sound wave generating part is arranged away from the steel material via the sound wave medium, the electromagnetic signal from the steel material can be acquired with higher accuracy.

  Note that the term “electromagnetic noise” in the present application refers to the “electromagnetic noise” disclosed in Japanese Patent No. 4919967, which has already been patented by some of the inventors of the present application, and the “electromagnetic noise” in the present application. "Technical term" used to more clearly distinguish it from "signal").

  Moreover, the nondestructive inspection method for one steel material of the present invention is a method in which a steel material provided in an interior of at least one matrix selected from the group of cement paste, mortar, and concrete from a sound wave generating unit, It is formed by a sound wave generation step of irradiating a sound wave pulse with the sound wave medium provided at a position sandwiched between the sound wave generation unit and reflection of the sound wave pulse at the interface between the sound wave medium and the matrix. So that the contact surface between the sound wave generator and the sound medium is inclined with respect to the interface so that the interface echo does not return to the sound wave generator. Receiving an electromagnetic signal generated from the steel material. In addition, in this nondestructive inspection method, the distance between the sound wave generation unit and the steel material is set longer than the duration of electromagnetic noise generated from the sound wave generation unit. As a result, the electromagnetic signal is temporally separated from the electromagnetic noise.

  According to this nondestructive inspection method, the object to be measured (steel material) is embedded in a solid material (matrix) that is different from the object to be measured like the steel material arranged inside the matrix described above. However, the electromagnetic signal (measurement target signal) generated from the steel material can be measured with high accuracy. In particular, since the contact surface between the sound wave generation unit and the sound wave medium is inclined with respect to the interface between the sound wave medium and the matrix, the interface echo returns to the sound wave generation unit. Generation of electromagnetic noise can be avoided. Therefore, if there is a thickness (distance) of the sonic medium enough to temporally separate electromagnetic noise generated when a sound wave pulse is generated from the sound wave generation unit, or a distance from the sound wave generation unit to the steel material to be measured Therefore, the measurement target signal can be acquired with high accuracy. This significantly increases the degree of freedom of the inspection environment in this nondestructive inspection method. In addition, by making the time during which the sound wave pulse propagates the distance between the sound wave generating unit and the steel material to be measured longer than the duration of electromagnetic noise generated from the sound wave generating unit, The electromagnetic signal can be acquired with higher accuracy.

  By the way, in this application, "matrix" means at least one kind selected from the group of cement paste, mortar, and concrete. Moreover, the “steel material” in the present application means at least one selected from the group of iron, steel, and cast iron. In addition, “steel” in the present application includes stainless steel. Further, “inspection” in the present application includes the meaning of “measurement”.

  According to one nondestructive inspection apparatus or one nondestructive inspection method of the present invention, the object to be measured (steel material) is a solid material (matrix) that is different from the object to be measured, such as a steel material arranged inside the matrix. Even in a situation where it is embedded, an electromagnetic signal (measurement target signal) generated from the steel material can be measured with high accuracy while avoiding the influence of electromagnetic noise. In addition, according to the nondestructive inspection apparatus or the nondestructive inspection method, the degree of freedom of the inspection environment is significantly increased.

It is a schematic diagram which shows the structural example of the nondestructive inspection apparatus of steel materials of 1st Embodiment. FIG. 1B is a partially enlarged view of FIG. 1A. It is a graph which shows an example of the inspection result of the steel materials using the nondestructive inspection device of steel materials of a 1st embodiment. It is a schematic diagram which shows the structural example of the nondestructive inspection apparatus of steel materials as a comparative example. It is a graph which shows an example of the inspection result of the steel materials using the nondestructive inspection apparatus of the steel materials as a comparative example. It is a schematic diagram which shows the structural example of the nondestructive inspection apparatus of steel materials of 2nd Embodiment. It is a schematic diagram which shows the structural example of the nondestructive inspection apparatus in other embodiment.

  As an embodiment of the present invention, a nondestructive inspection device and a nondestructive inspection method will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, elements of the present embodiment are not necessarily described with each other kept to scale. Further, some symbols may be omitted to make each drawing easier to see.

<First Embodiment>
1. Configuration of Nondestructive Inspection Apparatus 100 and Example of Nondestructive Inspection Method The nondestructive inspection apparatus 100 and the nondestructive inspection method of this embodiment will be described. FIG. 1A is a schematic side view showing a configuration example of a steel material nondestructive inspection apparatus 100 of the present embodiment. FIG. 1B is a partially enlarged view of FIG. 1A. In the present embodiment, a steel material 90 having a substantially circular cross section and a columnar shape, which is an object to be measured, is provided in a direction orthogonal to the paper surface of FIG. In addition, a desired pulse is given by a pulse generator (for example, a commercially available pulse generator) 12 of the present embodiment. In addition, an amplification circuit 22 that amplifies the electromagnetic signal received by the electromagnetic signal receiving unit 20 is provided. In addition, for example, in order to synchronize the pulse generator 12 and the commercially available oscilloscope 50, the pulse generator 12 and the oscilloscope 50 are connected. In the present embodiment, a commercially available computer 60 is connected to the nondestructive inspection apparatus 100 to control sound waves (irradiation time, waveform, irradiation intensity, pulse width, etc.) and receive by the electromagnetic signal receiving unit 20. Analysis and display of the electromagnetic signal is performed.

In FIG. 1A, A (A ₁ and A ₂ ) indicates a sound wave pulse emitted from the sound wave generator 10. A ₁ represents a sound wave pulse propagating in the sound medium 30, and A ₂ represents a sound wave pulse propagating in the matrix 80. In addition, E ₁ indicates a reflected wave (interface echo) in which the sound wave pulse irradiated from the sound wave generator 10 is reflected on the interface between the sound wave medium 30 and the matrix 80.

Further, S in FIG. 1A indicates an electromagnetic signal (measurement target signal) generated from the steel material 90 by the sound wave pulse emitted from the sound wave generator 10. Note that the sound velocity of the sound wave (A ₁ ) propagating in the sound wave medium 30 is represented by V ₁ , and the sound velocity of the sound wave (A ₂ ) propagating in the matrix 80 is represented by V ₂ .

The nondestructive inspection apparatus 100 of this embodiment includes at least the configurations shown in the following (1-1) to (1-4).
(1-1) A sound wave generator 10 that emits a sound wave pulse toward the steel material 90 to be measured.
(1-2) A sonic medium 30 provided at a position sandwiched between at least one matrix 80 selected from the group of cement paste, mortar, and concrete and the sound wave generation unit 10 at least when irradiated with a sound wave pulse.
(1-3) Configuration in which the contact surface between the sound wave generation unit 10 and the sound wave medium 30 is inclined with respect to the interface between the sound wave medium 30 and the matrix 80 (1-4) Generated from the steel material 90 by irradiation with sound wave pulses Electromagnetic signal receiving unit 20 for receiving electromagnetic signals

Moreover, the nondestructive inspection method of this embodiment includes at least the steps shown in the following (2-1) to (2-2).
(2-1) A sound wave medium 30 is provided in a position sandwiched between the matrix 80 and the sound wave generation unit 10 toward the steel material 90 to be measured provided in the matrix 80. Sound wave generation step of irradiating pulse (2-2) The interface echo formed by reflection of the sound wave pulse irradiated in the sound wave generation step at the interface between the sound wave medium 30 and the matrix 80 does not return to the sound wave generation unit 10. As described above, in the state where the contact surface between the sound wave generator 10 and the sound wave medium 30 is inclined with respect to the interface, the electromagnetic signal receiving step of receiving the electromagnetic signal generated from the steel material 90 by the sound wave pulse

  The sound wave generation unit 10 in the above-described nondestructive inspection method can be rephrased as a sound wave generation source.

Further, regarding the nondestructive inspection apparatus 100 and the nondestructive inspection method of the present embodiment, in addition to the above-described configurations or processes, the duration of electromagnetic noise (t ₁₎ generated when a sound wave pulse is generated from the sound wave generator 10. ) And the time (t ₂ ) during which the sound wave pulses (A ₁ and A _{2 in} FIG. 1A) propagate the distance from the sound wave generator 10 to the steel material 90 satisfy the following expression (1).

  From the viewpoint of acquiring the electromagnetic signal from the steel material 90 with high accuracy by the electromagnetic signal receiving unit 20, it is necessary to obtain the distance from the sound wave generating unit 10 to the steel material 90 in order to satisfy the above formula (1). Accordingly, in the present embodiment, the sonic medium 30 having a distance through which the sonic pulse propagates to satisfy the expression (1) is provided.

  The sound wave emitted from the sound wave generation unit 10 is reflected at the interface and can return to the sound wave generation unit 10 as an interface echo. In order to prevent the interface echo from reaching the sound wave generator 10 directly when the sound wave has a finite thickness corresponding to the diameter of the vibration surface (“D” in FIG. 1B) and propagates in parallel, It is preferable to satisfy the following formula (2). In equation (2), the angle formed by the contact surface between the sound wave generator 10 and the sound wave medium 30 and the interface between the sound wave medium 30 and the matrix 80 is θ (“θ” in FIG. 1B), and the interface L is the distance from the upper end of the vibration surface of the sound wave generator 10 (the portion of the vibration surface furthest away from the interface in FIG. 1B).

According to the nondestructive inspection apparatus 100 of the present embodiment, the contact surface between the sound wave generation unit 10 and the sound wave medium 30 is inclined with respect to the interface between the sound wave medium 30 and the matrix 80, and thus the interface echo E ₁ is generated. In other words, the sound wave generator 10 does not return directly. In addition to causing this action, the presence of the sonic medium 30 satisfying the above-described expression (1) is temporally separated from “tailing” electromagnetic noise described later, and the influence of the interface echo E ₁ is also avoided. Therefore, the measurement target signal (electromagnetic signal) from the steel material 90 can be measured with high accuracy.

  Here, the example of the sound wave generation unit 10 in the present embodiment is a vibrator (typically, an ultrasonic vibrator). In addition, a function generator may be employed instead of the pulse generator 12 in FIG. 1A. Moreover, although the example of the electromagnetic signal receiver 20 in FIG. 1A is a coil, the electromagnetic signal receiver 20 is not limited to a coil. For example, instead of a coil, an antenna that captures electromagnetic waves or a sensor that is sensitive to electromagnetic waves (for example, a magnetic sensor) may be employed. The sonic medium 30 is not limited as long as it is a member that satisfies the above-described formula (1). The material of the sonic medium 30 is a material in which the sound wave attenuation is small and the acoustic impedance of the matrix 80 is approximately the same. The use of a material having the same level as the acoustic impedance is because reflection of sound waves (sound wave pulses) can be suppressed. From the viewpoint described above, it is a preferable aspect that the material of the sonic medium 30 is the same type as that of the matrix 80. Examples of other materials are glass, acrylic, other resins or plastics. In order to facilitate the propagation of the sound wave (sound wave pulse) in the matrix 80, a sound wave pulse having a relatively low frequency (for example, 50 Hz to 1 MHz, more preferably 50 kHz to 500 kHz) is employed. Is preferred.

  It should be noted that the steel material 90 to be measured is present in the matrix 80 described above and is not visually recognized from the outside by the matrix 80 because there is no crack, peeling, abrasion or erosion. However, it is one of the advantages of the nondestructive inspection apparatus 100 that the state of the steel material 90 can be measured nondestructively.

  The object to be measured of the present embodiment is a steel material 90 provided inside at least one matrix selected from the group consisting of cement paste, mortar, and concrete. In this embodiment, even if the ratio of components (for example, water, cement, aggregate, sand (gravel), etc.) that can be contained in cement paste, mortar, or concrete varies, It is one of the advantages of the nondestructive inspection apparatus 100 that the form and the effect are not substantially impaired.

2. Example of Inspection Result by Nondestructive Inspection Apparatus 100 Next, an inspection result by the nondestructive inspection apparatus 100 will be described. In FIG. 2, an example of the test result of the steel material 90 using the nondestructive inspection apparatus 100 of this embodiment is shown. The upper part of FIG. 2 is a waveform observed by the sound wave generation unit 10 and represents the persistence of vibration of the vibrator at the time of sound wave generation and the interface echo that has returned to the sound wave generation unit after a plurality of reflections. The lower part of FIG. 2 is a waveform including a measurement target signal (electromagnetic signal) observed by the electromagnetic signal receiving unit 20.

  Moreover, in order to contrast with the nondestructive inspection apparatus 100 of this embodiment, the example of the test result of the steel material 90 using the nondestructive inspection apparatus 900 as a comparative example is shown. FIG. 3 is a schematic diagram illustrating a configuration example of the nondestructive inspection apparatus 900. Moreover, FIG. 4 is a graph which shows an example of the test result of the steel material 90 using the nondestructive inspection apparatus 900 as a comparative example.

The difference between the nondestructive inspection 900 as a comparative example and the nondestructive inspection apparatus 100 of the present embodiment is only the acoustic medium. In the present embodiment, the contact surface between the sound wave generator 10 and the sound wave medium 30 is inclined and forms 30 ° with respect to the interface with the matrix 80 (angle θ in FIG. 1B). The sound wave medium 930 as a comparative example has a cylindrical shape, and the contact surface between the sound wave generator 10 and the sound wave medium 930 is not inclined with respect to the interface between the sound wave medium 930 and the matrix 80. The maximum height or the maximum thickness (L _{0 in} FIG. 1A) of the acoustic medium 30 of the present embodiment is about 55 mm, and the maximum height (L _{1 in} FIG. 3) of the acoustic medium 930 of the comparative example is about 40 mm. It is.

In both of the present embodiment and the comparative example, the material of the sonic media 30 and 930 and the matrix 80 is mortar. The distance from the surface of the matrix 80 to the steel material 90 (FIG. 1A and FIG. 3D) is 42 mm. In the present embodiment, the distance from the sound wave generator 10 to the steel material 90 is about 96 mm. On the other hand, in the comparative example, the distance from the sound wave generator 10 to the steel material 90 is about 82 mm. Moreover, in any of this embodiment and the comparative example, the material of the steel material 90 is columnar iron (so-called rebar), and the diameter is 16 mm. The sound velocity V ₂ in the mortar that is the matrix 80 is considered to be about 4000 m / sec.

  In the example of FIGS. 2 and 4, a sound wave having a relatively low frequency (500 kHz) is employed to facilitate the propagation of the sound wave (sound wave pulse) in the matrix 80.

First, in the example of the inspection result of the present embodiment (FIG. 2), since the distance from the sound wave generator 10 to the steel material (rebar) 90 is about 96 mm, the measurement target signal (electromagnetic signal) is a sound pulse. It is considered that the phenomenon occurs about 24 μs after the occurrence of. A part of the sound wave pulse emitted from the sound wave generation unit 10 is reflected at the interface between the sound wave medium 30 and the matrix 80, but the sound wave is inclined by 30 ° and satisfies the formula (2). It is considered that the interface echo) E ₁ does not reach the sound wave generator 10 directly.

  The waveform observed in the region X in the lower diagram of FIG. 2 (electromagnetic signal intensity) is the signal to be measured from the steel 90 because no interface echo is observed in the upper diagram of FIG. 2 (echo intensity) at the same time. Conceivable. Note that the waveform observed in the Z region is considered to be that the sound wave has returned to the sound wave generation unit 10 after being reflected a plurality of times at the interface between the sound wave medium 30 and the matrix 80 and the outer surface of the sound wave medium 30 itself. . However, since this interface echo is temporally separated from X, it does not affect the measurement of the signal to be measured.

  On the other hand, in the case of the comparative example (FIG. 4), since the distance from the sound wave generator 10 to the steel material 90 (rebar) is about 82 mm, the measurement target signal (electromagnetic signal) is about 21 μm after the sound wave pulse is generated. It is thought to occur after 2 seconds. On the other hand, it is considered that it takes about 20 μs for a part of the sound wave pulse irradiated from the sound wave generator 10 to be reflected by the interface between the sound medium 30 and the matrix 80 and return to the sound wave generator 10.

  Therefore, the waveform observed in the region X ′ in the lower diagram (electromagnetic signal intensity) of FIG. 4 is the electromagnetic noise generated by the interface echo (Y ′) returned directly to the sound wave generator 10 and the measurement target signal from the steel 90. Both are considered to be mixed.

  As described above, the nondestructive inspection apparatus 100 of the present embodiment prevents the interface echo from directly returning to the sound wave generator 10 and avoids the generation of electromagnetic noise that interferes with the measurement target signal. As a result, an electromagnetic signal from the steel material 90 that is a measurement target signal can be acquired with high accuracy. On the other hand, when the nondestructive inspection apparatus 900 as a comparative example is adopted, the sound wave generation unit 10 cannot avoid receiving the interface echo directly, and therefore, due to the influence of electromagnetic noise from the sound wave generation unit 10 caused by the echo. Thus, only the signal to be measured from the steel material 90 cannot be distinguished and observed. Since electromagnetic noise or electromagnetic signals are transmitted at the speed of light, the time at which they occur and the time observed at the receiving unit may be considered substantially simultaneous.

By the way, in both cases of FIG. 2 and FIG. 4, by providing the sonic mediums 30 and 930, the measurement target signals (electromagnetic signals) X and X ′ are generated when the sound wave pulse is generated from the sound wave generator 10. Electromagnetic noise, in other words, a state of decay with the passage of time is observed at the beginning of FIGS. 2 and 4. In other words, the electromagnetic noise is temporally separated from the electromagnetic noise. That is, between the sound wave generation unit 10 and the steel material 90 so that the measurement target signal (electromagnetic signal) is observed after the duration (t ₁ ) of electromagnetic noise generated when the sound wave pulse is generated from the sound wave generation unit 10. The distance is preferably set.

  When the non-destructive inspection apparatus 100 is adopted, the electromagnetic noise generated when the sound wave pulse is generated from the sound wave generation unit 10 is temporally separated as described above. If there is a thickness (distance) of the sonic medium 30 or a distance from the sound wave generator 10 to the steel material 90 that is the object to be measured, an electromagnetic signal that is the measurement object signal can be obtained with high accuracy. As a result, the degree of freedom in the inspection environment has been greatly increased.

  In addition, when the structure which excluded the sound wave medium 30 and 930 is employ | adopted among the structures of the nondestructive inspection apparatuses 100 and 900, the electromagnetic signal from the steel 90 will generate | occur | produce 11 microseconds after generation | occurrence | production of a sound wave pulse. However, as is apparent from FIGS. 2 and 4, the electromagnetic noise from the sound wave generation unit 10 continues at the time, so that the measurement target signal (electromagnetic signal) is generated by the sound wave pulse from the sound wave generation unit 10. It will be buried in the electromagnetic noise that sometimes occurs. Accordingly, the fact that the nondestructive inspection apparatuses 100 and 900 include the sonic mediums 30 and 930 can realize that the measurement target signal (electromagnetic signal) can be separated from the electromagnetic noise component with high accuracy and temporally. To contribute.

  By the way, according to the analysis of the present inventors at the present time, it is considered that the electromagnetic signal which is the measurement target signal shown in FIG. 2 reflects the electromagnetic and / or mechanical characteristics of the steel material 90. These pieces of information are considered to be effective indexes indicating whether the steel material 90 to be measured is healthy, deteriorated, or damaged.

  From the result of FIG. 2, according to the nondestructive inspection apparatus 100 of the present embodiment and the nondestructive inspection method of the present embodiment, the steel material 90 is temporarily embedded in the matrix 80 and from the outside. It has become clear that the state of the steel material 90 can be inspected directly and non-destructively even if it is invisible or difficult.

  In the example of FIG. 2, the matrix 80 is mortar, but the example of the matrix 80 is not limited to mortar. If the matrix 80 is at least one selected from the group consisting of cement paste, mortar, and concrete, a result similar to the result of FIG. 2 can be obtained.

<Second Embodiment>
By the way, in 1st Embodiment, the nondestructive inspection apparatus 100 provided with the electromagnetic signal receiving part 20 which receives the electromagnetic signal which arises when a sound wave pulse is irradiated with respect to the steel material 90 and the nondestructive inspection method are disclosed. However, the nondestructive inspection apparatus 200 and the nondestructive inspection method that further include an echo signal receiving unit 40 that can separately receive a steel echo to be described later are other modes that can be adopted.

  Specifically, the nondestructive inspection apparatus 200 and the nondestructive inspection method of this embodiment will be described. FIG. 5 is a schematic side view showing a configuration example of the steel material nondestructive inspection apparatus 200 according to the present embodiment, and shows another example of a nondestructive inspection method using the nondestructive inspection apparatus 200. In the present embodiment, the steel material 90 to be measured is provided in parallel to the paper surface of FIG.

In the nondestructive inspection apparatus 200 of the present embodiment, for example, a reflected wave (interface echo) E ₁ in which a sound pulse irradiated from the sound wave generator 10 is reflected on the interface between the sound medium 30 and the matrix 80, and the sound wave generator sound pulse emitted from the 10 reflected wave reflected on the steel 90 echo signal receiving unit 40 for receiving the (steel echo) E ₂ is provided as an object to be measured. Moreover, in this embodiment, the echo signal receiving process of receiving the echo signal by the echo signal receiving unit 40 can acquire information on the multi-faced steel material 90 such as grasping the position of the steel material 90 with high accuracy. It becomes possible.

Incidentally, in terms of avoiding as much as possible the surface echo E _1, the echo signal reception unit 40 disposed to primarily receive steel echo E ₂ is preferred because it does not generate electromagnetic noises due to the interface echo E _1.

  Further, the echo signal receiving unit 40 does not necessarily need to be fixedly disposed on the sonic medium 30. For example, it is a preferable aspect of the present embodiment that the echo signal receiving unit 40 can be detachably attached to the sound wave medium 30 by a moving mechanism including a known mechanism (not shown). More specifically, the attachment / detachment is realized by a moving mechanism that moves the echo signal receiving unit 40 away from the sound wave medium 30 by only a few millimeters, and the echo signal receiving unit 40 can be substantially disabled. When the echo signal receiving unit 40 is arranged so as to be detachable in such a manner, the above-described steel echo is acquired as necessary at a time different from the time when the electromagnetic signal from the steel 90 as the measurement target signal is received. Is possible.

  In addition, the configuration in which the echo signal receiving unit 40, which has already been described as a preferred aspect of the present embodiment, is detachably arranged with respect to the sound wave medium 30, receives an electromagnetic signal from the steel 90 that is a measurement target signal. Before or after the step of performing, the steel material echo formed by reflection of the sound wave pulse on the steel material 90 can be received as necessary, which is preferable.

<Other embodiment (1)>
FIG. 6 shows another example of a nondestructive inspection method using the nondestructive inspection apparatus 100 in the first embodiment.

  Also in this example, a steel material 90 having a substantially circular cross section and a columnar shape, which is an object to be measured, is provided in a direction orthogonal to the paper surface of FIG. Further, unlike the configuration of FIG. 1A in which the electromagnetic signal receiving unit 20 is on the same side as the sound wave irradiation surface, the electromagnetic signal receiving unit 20 is disposed near the end side wall of the matrix 80 in FIG. The matrix 80 in this example is concrete.

  Even when the arrangement of each configuration of the nondestructive inspection apparatus 100 shown in FIG. 6 is adopted, by adopting the nondestructive inspection method of the first embodiment, a result similar to the result of FIG. Can be obtained. Therefore, in the nondestructive inspection apparatus 100, the position where the electromagnetic signal receiving unit 20 is arranged is not particularly limited.

<Other embodiment (2)>
By the way, in each above-mentioned embodiment, 30 degrees was shown as an example (angle (theta) of FIG. 1B) which the interface of the sound wave medium 30 and the matrix 80, and the contact surface of the sound wave generation part 10 and the sound wave medium 30 make. However, the angle is not limited to 30 °. The angle θ may be various angles of 0 ° <θ <90 °. However, from the viewpoint of suppressing attenuation during sound wave propagation and reducing the shape of the sound wave medium, the angle θ is 10 ° or more. It is preferable that the angle is 15 ° or more. Further, from the viewpoint of causing the sound wave pulse emitted from the sound wave generation unit 10 to reach the steel material 90 with high accuracy, the angle θ is preferably 45 ° or less, and more preferably 40 ° or less.

  The disclosure of each of the above-described embodiments is described for explaining the embodiments, and is not described for limiting the present invention. In addition, modifications within the scope of the present invention including other combinations of the embodiments are also included in the claims.

  The nondestructive inspection apparatus and nondestructive inspection method of the present invention are extremely useful in each industry or business that utilizes nondestructive inspection of current and future steel materials, particularly steel materials embedded in a matrix.

DESCRIPTION OF SYMBOLS 10 Sound wave generation part 12 Pulse generation part 20 Electromagnetic signal receiving part 22 Amplifying circuit 30 Sonic medium 40 Echo signal receiving part 50 Oscilloscope 60 Computer 80 Matrix 90 Steel material 100,200 Nondestructive inspection apparatus 900 Nondestructive inspection apparatus 930 as a comparative example Sonic medium as an example

Claims (6)

A sound wave generator for irradiating a steel material provided in at least one matrix selected from the group consisting of cement paste, mortar, and concrete;
A sound wave medium provided at a position sandwiched between the matrix and the sound wave generator when the sound wave pulse is irradiated;
An electromagnetic signal receiving unit that receives an electromagnetic signal generated from the steel material by the sound wave pulse,
The time during which the sound wave pulse propagates the distance between the sound wave generating unit and the steel material is longer than the duration of electromagnetic noise generated from the sound wave generating unit through the matrix and the sound wave medium. By disposing the sound wave generator away from the steel material, the electromagnetic signal receiver receives the electromagnetic signal temporally separated from the electromagnetic noise, and
The contact surface between the sound wave generator and the sound wave medium is such that the interface echo formed by reflection of the sound wave pulse at the interface between the sound wave medium and the matrix does not return to the sound wave generator. Inclined against the interface,
Non-destructive inspection equipment for steel materials. An echo signal receiving unit for further receiving a steel material echo formed by reflecting the sound wave pulse to the steel material;
The nondestructive inspection apparatus for steel materials according to claim 1. The echo signal receiving unit is detachably arranged with respect to the sound wave medium.
The nondestructive inspection apparatus for steel materials according to claim 2. From the sound wave generation unit, a steel medium provided in at least one matrix selected from the group consisting of cement paste, mortar, and concrete is provided with a sound wave medium at a position sandwiched between the matrix and the sound wave generation unit. A sound wave generation step of irradiating a sound wave pulse in the provided state;
The contact surface between the sound wave generator and the sound wave medium is such that the interface echo formed by reflection of the sound wave pulse at the interface between the sound wave medium and the matrix does not return to the sound wave generator. An electromagnetic signal receiving step of receiving an electromagnetic signal generated from the steel material by the sound wave pulse in a state inclined with respect to the interface, and a distance between the sound wave generator and the steel material, The electromagnetic signal is temporally separated from the electromagnetic noise by making the propagation time of the acoustic pulse longer than the duration of the electromagnetic noise generated from the acoustic wave generator,
Non-destructive inspection method for steel. An echo signal receiving step of receiving a steel material echo formed by reflecting the sound wave pulse to the steel material;
The nondestructive inspection method of the steel materials according to claim 4. Before or after the electromagnetic signal receiving step, further comprising an echo signal receiving step of receiving a steel material echo formed by reflecting the sound wave pulse to the steel material;
The nondestructive inspection method of the steel materials according to claim 4.

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