JP2003043018A - Elastic wave inputting device for nondesttructive inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic wave inputting device that can easily and stably input elastic waves to various faces of an object to be inspected. SOLUTION: This elastic wave inputting device 1 which is used at the time of nondestructively inspecting a concrete structure for defects by the impact echo method is constituted to shoot a flying object 6 toward the surface of the object to be inspected from a nozzle 5 by utilizing compressed air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic wave input device, and in particular, it can be suitably used for nondestructively inspecting defects inside or on the back surface of a concrete structure by an impact echo method. The present invention relates to an elastic wave input device for destructive inspection.

[0002]

2. Description of the Related Art For example, P by the post tension method
In the C structure, a reinforcing material such as a steel wire or a steel rod is inserted into the hole of the concrete structure which has been solidified in the state where the hole is previously formed, and tension is applied to the reinforcing material, By filling with grout and solidifying it, a compressive force is applied to the entire structure to improve the strength.

However, it is a difficult task to sufficiently fill the grout around the reinforcing material, and there are cases in which the grout is unexpectedly insufficiently filled. In such a case, P
Since the strength of the C structure at the time of the initial design cannot be obtained and inconvenience also occurs from the viewpoint of corrosion prevention of the reinforcing material, it becomes necessary to non-destructively inspect the grout filling state in the structure after construction.

As a method of nondestructively inspecting defects such as cavities present in such a concrete structure, the impact echo method has hitherto attracted attention. The impact echo method is a method of inputting an elastic wave to an inspection object such as a concrete structure and inspecting the presence or absence of defects such as cavities from the response waveform thereof, for example, due to grout filling failure in a PC structure. When an elastic wave is input to the PC structure in the presence of a cavity, vibration of a specific frequency in the elastic wave is reflected at the interface between the concrete and the cavity in the PC structure, and the response waveform is spectrally analyzed. The inspection method focuses on the fact that the reflected vibration of the specific frequency appears as a peak in the spectrum showing the relationship between the frequency and the amplitude obtained as a result.

Here, as the method of inputting the elastic wave to the object to be inspected in the impact echo method, there are conventionally known two methods, an impact hammer method and a steel ball dropping method. The impact hammer method is a method in which an impact hammer is used to strike the surface of an object to be inspected by the force of a person to apply an impact to input an elastic wave. On the other hand, the steel ball dropping method is a method in which a steel ball is allowed to freely fall from a certain height on the surface of an object to be inspected and an elastic wave is input.

[0006]

However, in the above-mentioned impact hammer method, since the impact hammer is a manual work of striking the surface of the object to be inspected by the force of the person, the striking force by the operator is inevitable and constant. It was a difficult method to input the elastic wave of the above into the inspection object.

Further, in the above-mentioned steel ball dropping method, since the steel ball is freely dropped, it can be used only for an object to be inspected on a horizontal surface, and for dropping the steel ball above it. Since a certain work space is also required, there is a problem that the inspection object to which the elastic wave can be input is considerably limited by this method.

Further, since any of the above-mentioned methods is a method of manually inputting an elastic wave to the inspection object,
It is necessary that the operator can easily face the inspection object and the operator can safely input the elastic wave. However, it is necessary for the operator to enter the inspection object. It may be a narrow tunnel that cannot be covered, or it may be a place where it is difficult to secure work safety such as a high-rise building or bridge pier, and it is difficult for such workers to input elastic waves for inspection. There was a problem that an object cannot be inspected by the impact echo method.

The present invention has been made in view of various problems of the above-described conventional elastic wave input method, and an object thereof is to stabilize the elastic wave to an inspection object such as a concrete structure. On the other hand, to provide an elastic wave input device for nondestructive inspection capable of easily inputting elastic waves from various aspects, and capable of inputting elastic waves even to an inspection target for which it is difficult for an operator to input elastic waves. is there.

[0010]

In order to achieve the above object, the present invention as set forth in claim 1, is an elastic wave input used for nondestructively inspecting a defect such as a concrete structure by an impact echo method. The elastic wave input device has a structure in which a flying object is flown from a nozzle toward the surface of an inspection object by using compressed air. According to the present invention, since the projectile has a structure of flying by using compressed air, unlike the impact hammer method in which a hammer is hit manually, a stable elastic wave of an object to be inspected is generated. Input becomes possible. Further, unlike the steel ball dropping method using free fall, it becomes possible to easily input elastic waves to the surface of the inspection object at various angles.

According to a second aspect of the present invention, the elastic wave input device is provided with a sensor for recording a response waveform from an object to be inspected when an elastic wave is input. According to the present invention, the apparatus can record the response waveform from the inspection target together with the input of the elastic wave to the inspection target.

Further, according to the present invention as set forth in claim 3, the elastic wave input device is installed so as to be movable at a predetermined distance from the surface of the inspection object, and the surface of the inspection object is remotely operated. It has a structure to fly the flying object toward. According to the present invention, an elastic wave can be input even for a narrow inspection object that a worker cannot enter, or for an inspection object for which it is difficult to ensure the safety of work by the operator, and the impact echo method is used. Non-destructive inspection becomes possible.

According to a fourth aspect of the present invention, the elastic wave input device is provided with a pressurizing tank for storing compressed air, and a firing pressure adjusting device for adjusting the pressure of the compressed air supplied from the pressurizing tank. And a firing valve for injecting compressed air whose pressure is regulated by the firing pressure regulator into the nozzle, and a projectile loaded in the nozzle. According to the present invention, it can be easily carried or installed so as to be movable at a predetermined distance from the surface of the inspection object, and can be efficiently applied to various inspection objects by the impact echo method. Non-destructive inspection becomes possible.

In the present invention, the flying body is made of aluminum or titanium, the flying body is cylindrical, and the diameter-to-length ratio is 1: 1.5. ˜1: 4, and further, making the tip of the cylindrical flying body a conical shape of 95 ° to 175 ° both includes a wide band frequency and stabilizes elastic waves of large energy. This is a preferable mode for inputting to the inspection object.

Further, by forming a plurality of recessed lines parallel to the axis of the nozzle on the inner peripheral surface of the nozzle for flying the flying object, it is possible to fly the flying object without rotating the flying object, and to inspect Is a preferable mode for inputting a more stable elastic wave.

The inspection object referred to in the present invention is as follows.
Examples include civil engineering concrete structures such as tunnels and bridge piers, architectural concrete structures such as buildings, and tiled structures.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the elastic wave input device according to the present invention described above will be described below in detail with reference to the drawings.

First, FIG. 1 is a side view showing the whole of an elastic wave input device 1 according to a first embodiment of the present invention. In FIG. 1, 2 is a pressurizing tank for storing compressed air, and 3 is firing. The pressure regulator 4 is a firing valve and a grip. Reference numeral 5 is a nozzle, and 6 is a flying body showing a state of being projected from the nozzle. Reference numeral 7 denotes a hose connecting between the firing pressure regulator and the firing valve, and the hose 7 is connected to the firing pressure regulator 3 via a connection cover 7a.

The pressurizing tank 2 can be freely connected to a compressor (neither is shown) via a connecting cover.
Compressed air is stored inside by connecting to a compressor, and at the time of work, it is removed from the compressor and the elastic wave input device 1 shown in FIG.

The firing pressure adjuster 3 has a known structure in which the air flow rate is adjusted by adjusting the throttle of the valve. For example, an air carrier manufactured by Yamada Co., which is commercially available as a set with the pressurizing tank 2. ATC-99S can be used,
With such a firing pressure adjuster 3, for example, a firing pressure of 2.0M
Adjust to about Pa.

The firing valve and the grip 4 are also
A known structure may be used, and for example, an Air duster gun K601 manufactured by Kinki Co. may be used.

As shown in FIGS. 2 (a) and 2 (b), the nozzle 5 is a straight tubular cylinder having a plurality of recessed ridges 8 formed on its inner peripheral surface and parallel to the axis, and has an inner diameter. Is designed to be slightly larger (for example, about 1 mm) than the diameter of the flying body 6, and the length is designed to be about 15 to 40 cm from the viewpoint of portability, workability, and straightness of the flying body. .

In order to input an elastic wave having a high frequency and a large energy to the inspection object, the flying body 6 should be made of a material having a small specific gravity and a high elastic coefficient. It is preferably made of, for example, aluminum or titanium.

The shape of the flying body 6 is shown in FIG.
The ratio of the diameter D to the length L shown in (a) and (b) is 1: 1.
It is formed in a substantially columnar shape with a diameter of 5 to 1: 4 and a conical tip of 95 to 175 degrees.

This is because the ratio of diameter D to length L is 1: 1.5.
This is because when the flying object is less than the length, it cannot fly stably in the nozzle 5 and the input of the elastic wave is not stable. On the contrary, when the flying object is longer than 1: 4, The reason is that the deformation of the flying object is large at the time of collision with the surface of the inspection object, and the characteristic value of the material of the flying object itself appears largely.

If the angle of the tip of the flying object exceeds 175 degrees, that is, if it is close to a plane, the contact area between the flying object and the surface of the object to be inspected will change due to a slight difference in the incident angle, and the stability will be stable. I cannot input the elastic wave. On the contrary, when the tip is an acute angle less than 95 degrees, a part of the surface of the inspection object is destroyed at the time of collision, and there is a fear that a plastic wave is input. The diameter of the flying object is preferably about 8 mm.

In the elastic wave input device 1, if necessary, the tip of the nozzle 5 and the surface of the object to be inspected for inputting the elastic wave have a constant distance, and the axis of the nozzle 5 is elastic. It is possible to provide a jig 9 that can be installed so as to form a constant angle with respect to the surface of the inspection object that inputs waves.

The jig 9 is, for example, as shown in FIG.
As shown in (b), a base portion 11 mounted and fixed to the outer peripheral portion of the nozzle 5 via a cushioning material 10, and the base portion 11
From the two legs 12 and 12 and shock-absorbing materials 13 and 13 attached to the ends of the legs 12, respectively. By abutting on the surface of the inspection object A to be input via the cushioning material 13, a constant distance X is provided between the tip of the nozzle 5 and the surface of the inspection object A to which the elastic wave is input, and Nozzle 5
It can be installed such that the axis of is at a constant angle Y with respect to the surface of the inspection object A into which the elastic wave is input.

If necessary, the elastic wave input device 1 may be provided with a cover 14 that catches the projectile 6 that has jumped out from the tip of the nozzle 5 and has collided with the surface of the inspection object.

The cover 14 is, for example, as shown in FIG.
As shown in (b), it is composed of a transparent synthetic resin cylindrical case 15 that covers the vicinity of the tip of the nozzle 5 and a bottom plate 16 that closes the bottom of the cylindrical case 15, and projects from the tip of the nozzle 5. It is assumed that the projectile 6 after colliding with the surface of the inspection object is received. The cover 14 is
A fixed distance is provided between the tip of the nozzle 5 and the surface of the inspection object to which the elastic wave is input, and the axis of the nozzle 5 is at a constant angle with respect to the surface of the inspection object to which the elastic wave is input. It can also be used as the jig 9 that can be installed in the above. In this case, a cushioning material is attached to the tip of the cylindrical case 15 that constitutes the cover 14, and the cylindrical case 15 is brought into contact with the surface of the inspection object A that receives an elastic wave through the cushioning material. A constant distance is provided between the tip of the nozzle 5 and the surface of the inspection object A that inputs the elastic wave, and the axis of the nozzle 5 is constant with respect to the surface of the inspection object A that inputs the elastic wave. It can be installed so that it becomes the angle of.

Further, the elastic wave input device 1 can be equipped with a sensor 17 for recording a response waveform from an object to be inspected when an elastic wave is input by colliding the flying body 6.

When a contact type accelerometer 18 is used as the sensor 17, for example, as shown in FIGS. 4 (a) and 4 (b), the surface of the inspection object A of the jig 9 is touched. It suffices if the accelerometer 18 is embedded in the cushioning material 13 in contact therewith, and
When a non-contact type laser displacement meter 19 is used as the sensor 17, if the laser displacement meter 19 is attached to the base 11 of the jig 9 as shown in FIGS. 4 (a) and 4 (b), for example. good. The sensor 17 (18, 19) includes an amplifier for amplifying a weak electric signal, an A / D converter for converting an analog signal into a digital signal, and a waveform recording device for recording a waveform as a digital signal (both are (Not shown).

In the elastic wave input device 1 according to the present invention constructed as described above, the pressure of the compressed air in the pressurizing tank 2 is adjusted by the firing pressure adjuster 3, and the firing valve 4 is pulled to cause the interior of the nozzle 5 to be retracted. The flying body 6 loaded in the nozzle 5 is jetted at a predetermined speed by the jetting pressure of the compressed air and collides with the surface of the inspection object A, so that a stable elastic wave can be easily generated at various angles. It can be entered for the inspection object. Further, in the elastic wave input device 1 provided with the jig 9, the flying body 6 can always be made to collide with the surface of the inspection object A at a constant distance and angle, and a more stable elastic wave input can be performed. Is possible. Also, cover 1
In the elastic wave input device 1 provided with 4, the flying body 6 after colliding with the surface of the inspection object A becomes easy, and the elastic wave input device has high safety. Further, the elastic wave input device 1 provided with the sensors 17 (18, 19) is a device capable of recording the response waveform from the inspection object together with the input of the elastic wave to the inspection object.

Next, an elastic wave input device 21 according to a second embodiment of the present invention will be described with reference to FIGS.

The elastic wave input device 21 according to the second embodiment is installed so as to be movable at a predetermined distance from the surface of the object to be inspected, and fly toward the surface of the object to be inspected by remote control. The structure is for flying the body, and the basic structure for flying the flying body from the nozzle toward the surface of the inspection object using compressed air is the same as that of the elastic wave input device 1 according to the first embodiment. .

That is, in FIGS. 5 and 6, 22 is a pressurizing tank for storing compressed air, 23 is a firing pressure regulator, and 24 is a firing valve (electromagnetic valve) which is opened / closed by remote control by wireless or wire. Reference numeral 25 is a nozzle, 26 is a flying body showing a state of jumping out of the nozzle, and 27 is a so-called magazine for continuously loading the flying body in the nozzle. Two
Reference numeral 8 denotes a hose connecting between the firing pressure regulator and the firing valve, and the hose 28 is connected to the firing pressure regulator 23 via a connection cover 28a. Further, 29 is a laser displacement type that records a response waveform from an inspection object when an elastic wave is input. The laser displacement type 29 includes an amplifier for amplifying a weak electric signal and an analog signal to a digital signal. A / D converter for conversion, and waveform recording device for recording the waveform as a digital signal (neither is shown)
Are connected.

The elastic wave input device 21 described above is used as a trolley 30.
The carriage 30 is integrally assembled on the top, and the carriage 30 is configured to be movable along a rail 31.

In the structure shown in FIG. 5, the rail 31 is fixed in the tunnel B by a plurality of U-shaped frame bodies 32 mounted so as to hang at appropriate positions on the upper inner wall surface of the tunnel B. It is configured so that the carriage 30 can move in the tunnel B at a position spaced apart from the upper wall of the tunnel B by a certain distance. Further, in the one shown in FIG. 6, the rail 31 is fixedly supported by a plurality of U-shaped frame bodies 32 attached to the vertical wall surface of the bridge pier C in a state of protruding laterally, The carriage 30 is configured to be able to move along the pier C at a position separated from the vertical wall surface of the pier C by a certain distance. The carriage 30 may be moved by itself by mounting a motor or the like, but a string is attached to the carriage 30 and the carriage 30 is pulled from a distance to move the carriage 30 to the rail 31.
You may move along.

The elastic wave input device 21 according to the present invention having the above-described structure has a narrow tunnel B which is difficult for a person to enter as shown in FIG. 5, and an operator as shown in FIG. With respect to the inspection object such as the bridge pier C whose safety is difficult to secure, the carriage 30 is moved along the rail 31 by a predetermined distance by pulling a string or traveling by itself, and every time the carriage 30 is moved by a predetermined distance. To open the firing valve (electromagnetic valve) 24 by remote control, to fly the projectile 26 from the nozzle 25 using the compressed air stored in the pressurization tank 22, and to collide the projectile 26 with the surface of the inspection object. By inputting an elastic wave by using the laser displacement meter 29 and recording the response waveform from the inspection object at that time,
Defects such as the cavity a existing behind the tunnel B and the unfilled grout part b existing inside the pier C can be easily inspected by the impact echo method.

Although the embodiments of the elastic wave input device according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and within the scope of the technical idea of the present invention. Various modifications and changes are possible.

For example, in the elastic wave input devices according to the first and second embodiments, the structure in which the compressed air for flying the flying object is stored in the pressurizing tank has been described. It may be connected directly to the supply source by a long hose. Further, in the elastic wave input device according to the first embodiment in which the firing valve is manually operated, the device itself is provided with a mechanism for squeezing air by means such as bending like an air gun. Good as a thing.

[0042]

As described above, according to the present invention described in claim 1, the structure is such that the flying object is blown toward the surface of the object to be inspected by using compressed air. Unlike hammering by hand, it enables stable input of elastic waves to the inspection object, and unlike the steel ball dropping method that uses free fall, the surface of the inspection object at various angles In contrast, the elastic wave can be easily input.

Further, according to the present invention described in claim 2, there is an effect that it becomes an apparatus capable of recording the response waveform from the inspection object together with the input of the elastic wave to the inspection object.

Further, according to the present invention as set forth in claim 3, even for a narrow inspection object which a worker cannot enter, or an inspection object for which it is difficult to secure the safety of the work by the operator, An elastic wave can be input, and there is an effect that a nondestructive inspection can be performed by the impact echo method.

Further, according to the present invention described in claim 4, it can be easily carried or can be installed movably at a predetermined distance from the surface of the object to be inspected. There is an effect that non-destructive inspection can be performed on the inspection object by the impact echo method.

[Brief description of drawings]

FIG. 1 is a side view conceptually showing the whole acoustic wave input device according to a first embodiment of the invention.

FIG. 2 is a diagram showing in detail a nozzle portion of an elastic wave input device according to the present invention, in which (a) is a front view and (b) is a vertical sectional view.

3A and 3B are views showing a flying object that is flown by using the elastic wave input device according to the present invention, in which FIG. 3A is a front view and FIG. 3B is a side view.

4A and 4B are diagrams showing a structure in the vicinity of a nozzle tip portion of an elastic wave input device according to the present invention, in which FIG. 4A is a side view and FIG.
Is a front view.

FIG. 5 is a front view conceptually showing the entire elastic wave input device according to the second embodiment of the present invention.

FIG. 6 is a front view conceptually showing the entire acoustic wave input device according to another second embodiment of the present invention.

[Explanation of symbols]

1 Acoustic Wave Input Device 2 According to First Embodiment 2 Pressurized Tank 3 Firing Pressure Adjuster 4 Firing Valve and Grip 5 Nozzle 6 Flying Body 7 Hose 8 Recess 9 Formed on Inner Surface of Nozzle 9 Jig 14 Cover 17 Sensor 21 Elastic Wave Input Device 22 According to Second Embodiment 22 Pressurized Tank 23 Firing Pressure Adjuster 24 Firing Valve (Electromagnetic Valve) 25 Opened and Closed by Remote Control 25 Nozzle 26 Flying Body 27 Magazine 28 Hose 29 Laser Displacement Type 30 Cart 31 Rail 32 Frame supporting rails A, B, C Inspection target

Claims (4)

[Claims] 1. An elastic wave input device used for nondestructively inspecting a defect such as a concrete structure by an impact echo method, wherein the elastic wave input device uses compressed air from a nozzle for a flying object. An elastic wave input device for nondestructive inspection, characterized in that it is configured to fly toward the surface of the inspection object. 2. The nondestructive inspection according to claim 1, wherein the elastic wave input device is provided with a sensor for recording a response waveform from an inspection object when an elastic wave is input. Elastic wave input device. 3. The elastic wave input device is installed so as to be movable at a predetermined distance from the surface of the object to be inspected, and has a structure for flying a flying object toward the surface of the object to be inspected by remote control. The elastic wave input device for nondestructive inspection according to claim 1 or 2, characterized in that: 4. The elastic wave input device, wherein a pressurized tank for storing compressed air, a firing pressure adjuster for adjusting the pressure of compressed air supplied from the pressurized tank, and a pressure adjustment by the firing pressure adjuster. 4. The elastic wave for nondestructive inspection according to claim 1, 2 or 3, comprising a firing valve for injecting compressed compressed air into a nozzle and a projectile loaded in the nozzle. Input device.