JPH0580035A - Ultrasonic flaw detector for civil engineering construction - Google Patents

Abstract

PURPOSE:To facilitate accurate judgment with efficient measuring work by enabling the obtaining of a section image of an object to be inspected continuously concerning an ultrasonic flaw detector of a civil engineering construction for non-destructive inspection of internal condition of the civil engineering construction such as asphalt paved road or the like. CONSTITUTION:A tire probe 5 with ultrasonic probes 1 and 2 for transmitting and receiving is made to run over an inspection surface 4 of an object 3 to be inspected to display an image based on a brightness signal corresponding to a receiving level according to a vertical sweep signal corresponding to a propagation speed and a horizontal sweep signal corresponding to a running range of a tire on a screen. The previous images displayed on a CRT display device 16 are stored and the previous images are shown on the CRT display device 16 together with an image obtained in real time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector for civil engineering structures for nondestructive inspection of the internal condition of civil engineering structures such as asphalt pavements.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic flaw detector for performing nondestructive inspection after construction of an asphalt pavement or the like has a transmitting ultrasonic probe 1 of a type that directly contacts an inspection object 3 as shown in FIG. And the ultrasonic probe 2 for reception are used, and an acoustic coupling material 24 such as water, glycerin, or spindle oil is interposed between the surface 4 to be inspected and the ultrasonic probes 1 and 2, and the transmitter 20 The ultrasonic wave reception waveform obtained from the receiver 21 by the transmission operation is observed and read by the oscilloscope 23 to estimate the internal state of whether or not there is a defect such as a cavity.

[0003]

However, in such a conventional ultrasonic flaw detector for civil engineering buildings, considerable experience and skill are required to read defects such as cavities from the received waveform. It is necessary, and in order to fully capture the internal state, it is necessary to change the measurement points many times at the location where defects are considered to exist and observe the waveform at multiple points,
Each time the measurement point is changed, it is necessary to apply an acoustic coupling material and re-install the ultrasonic probe, which requires a lot of time for measurement.

Further, since the range that can be inspected at one measuring point is relatively narrow, it is impossible to inspect all the construction roads, and it is necessary to narrow down the measuring points to inspect, and the reliability of the inspection is not always required. There was a problem that it was not guaranteed. The present invention has been made in view of the above-mentioned conventional problems, and civil engineering and construction in which a tomographic image of an inspection object can be continuously obtained and measurement work can be efficiently performed and accurate determination can be easily performed. An object is to provide an ultrasonic flaw detector for an object.

[0005]

In order to achieve this object, an ultrasonic flaw detector for civil engineering buildings according to the present invention comprises a tire probe in which a transmitting / receiving ultrasonic probe is arranged downward in a liquid medium. A transmitting circuit unit that drives the transmitting ultrasonic probe at a constant cycle by a low-frequency transmitting signal to transmit an ultrasonic wave to an inspection target; and a receiving level of a receiving signal of the receiving probe. , A vertical sweep circuit that generates a vertical sweep signal at a sweep speed based on the propagation speed of ultrasonic waves in the object in synchronization with the transmission operation, and a rotation speed of the tire probe. A rotation speed detector for detecting
A mileage calculation circuit that calculates a mileage from the rotation speed detected by the rotation speed detector, a horizontal sweep circuit that determines the sweep position on the horizontal axis of the CRT screen according to the mileage calculated by the mileage calculation circuit, and a reception circuit A CRT display device for displaying an image based on a luminance signal from the display unit on the screen based on the vertical sweep signal and the horizontal sweep signal, and a past image displayed on the CRT display device are stored. And an image storage device for displaying the image of 1. on a CRT display device.

Here, the tire probe improves the distance resolution by a two-probe method provided with two ultrasonic probes for transmission and ultrasonic probes for reception.

[0007]

According to the ultrasonic flaw detector for civil engineering buildings of the present invention having such a configuration, when the tire probe is run on the road surface of an asphalt pavement road to be inspected, for example, On the CRT screen, a tomographic image of the inspection object with the travel distance on the horizontal axis is continuously displayed, the internal state can be easily understood from this tomographic image, and defects such as cavities can be reliably found. ..

[0008]

FIG. 1 is a block diagram of an embodiment showing one embodiment of the present invention. In FIG. 1, reference numeral 5 denotes a tire probe in which a transmitting ultrasonic probe 1 and a receiving ultrasonic probe 2 are arranged side by side inside a tire 25 made of urethane rubber or the like. The tire 25 is filled with water, for example, as a liquid medium.

Here, when the inspection object 3 is a civil engineering building structure such as a road or a wall surface of a building, since the attenuation and scattering of ultrasonic waves is large, it is necessary to use a low frequency in the range of 20 KHz to 100 KHz, for example. .. For example, the used frequency f
Assuming that f = 30 KHz, the speed of sound propagating through the inspection object 3 is about 3000 m / s, and the wavelength is about 10 cm.

Therefore, in the one-probe method in which transmission and reception are performed by one ultrasonic probe, at least 10 cm corresponding to the wavelength is used.
A certain amount of dead zone (uninspectable area) occurs. Therefore, in the present invention, in order to avoid the occurrence of this dead zone, the two-probe method using the transmitting ultrasonic probe 1 and the receiving ultrasonic probe 2 is adopted. A trigger circuit 7 and a transmission circuit 8 are provided as a transmission circuit unit for the transmission ultrasonic probe 1. The trigger circuit 7 receives the timing control by the control circuit 6 and outputs a transmission trigger signal to the transmission circuit 8 at constant measurement intervals. When receiving the trigger signal, the transmission circuit 8 creates a transmission pulse having a fixed time width, and supplies the transmission ultrasonic probe 1 with a transmission signal which is amplitude-modulated with the use frequency f = 30 KHz.

The reception signal based on the ultrasonic echo from the receiving ultrasonic probe 2 provided in the tire probe 5 is received by the receiving circuit 9.
Is supplied to the signal processing circuit 10 after being subjected to signal amplification, noise removal filtering, and the like. Of course, the received signal to the receiving circuit 9 is gated by the signal that gives the transmission timing from the control circuit 6, and only the received signal obtained during the gate effective period is output.

The signal processing circuit 10 performs predetermined signal processing on the received signal so that distance resolution can be obtained even at a position within a transmission wavelength of 10 cm. That is, the depth or thickness of the inspection object 4 to be inspected is often about 5 to 10 cm, which is about the same as the wavelength used for ultrasonic waves. Therefore, a distance resolution equal to or less than the used wavelength is required. The received signal that has been subjected to the processing for increasing the distance resolution in the signal processing circuit 10 is given to the luminance modulation circuit 11, converted into a luminance signal according to the received level, and supplied to the CRT display device 16.

The trigger signal from the trigger circuit 7 is supplied to the vertical sweep circuit 12 to set the vertical sweep cycle.
The vertical sweep circuit 12 outputs to the CRT display device 16 a vertical sweep signal having a sweep speed determined by the speed of sound of ultrasonic waves propagating in the inspection object 3 at about 3000 m / s. Furthermore, a tire rotation speed detector 13 that detects the rotation speed of the tire 25 as the tire probe 5 travels is provided. The detected rotation speed of the tire rotation speed detector 13 is given to the mileage calculation circuit 14,
Since the diameter of the tire 25 is fixed, the traveling distance is calculated using the tire rotation speed.

The tire rotation speed detector 13 and the traveling distance calculation circuit 14 receive the initial reset signal supplied from the control circuit 6 at the start of measurement, and are in the initial state of detected rotation speed = 0 and traveling distance = 0. The travel distance calculated by the travel distance calculation circuit 14 is supplied to the horizontal sweep circuit 15. The horizontal sweep circuit 15 is a CRT according to the traveling distance of the tire probe 5.
A horizontal sweep signal that specifies the horizontal position of the display device as the display position is output.

In the CRT display device 16, the modulation signal as ultrasonic echo data output from the brightness modulation circuit 11 at each measurement cycle by the control circuit 6 is set to a horizontal traveling distance determined by the horizontal sweep signal from the horizontal sweep circuit 15. At a corresponding position, one line of image is displayed by a vertical sweep line in accordance with vertical scanning by the vertical sweep signal from the vertical sweep circuit 12.

Image storage device 1 for CRT display device 16
8, the image data swept in the past is sequentially stored in the image storage device 18, and the past image data before the current traveling position, that is, the horizontal position is read from the image storage device 18 and displayed on the CRT display device 16. By doing so, it is possible to display continuous tomographic images as the tire probe 5 travels.

FIG. 2 is an explanatory view showing the display operation of the CRT display device 16 in the embodiment of FIG. FIG. 2A shows a screen at the start of measurement, in which image data in the depth direction for one vertical line is displayed by the marker 30 indicating the current position. When time elapses after the tire probe 5 is run from the start of this measurement, the image data for one vertical line obtained in real time is sequentially stored in the image storage device 18, for example, as shown in FIG. When the position of the marker 30 indicating the position is reached, in addition to the real-time image indicated by the marker 30, the image storage device 1 stored up to that time is displayed.
The stored images from 8 are also displayed, and the continuous tomographic images make it easy to see that there are defects 32 such as cavities in the tomographic images.

In the actual inspection work, taking an asphalt pavement as an example, the ultrasonic flaw detector of the present invention equipped with the tire probe 5 is first pulled relatively quickly by an automobile or the like. The flaw detection work is performed at a high speed, a defect is found from the tomographic image obtained by this flaw detection work, and then a worker or the like slowly runs the tire probe 5 at a position where there is a possibility that there is a defect and the horizontal resolution is obtained. A high-accuracy tomographic image is acquired to confirm the existence of defects.

Therefore, in the horizontal sweep circuit 15 which produces a horizontal sweep signal for determining the horizontal sweep position in the CRT display device 16, the correspondence relationship between the horizontal sweep position and the traveling distance can be switched in multiple stages. In order to obtain a highly accurate tomographic image, the tire 25 of the tire probe 5 is
Water may be sprayed between the inspection surface 4 and the inspection surface 4 to form a water film to prevent the ultrasonic wave from being attenuated and to enhance the detection sensitivity.

Further, the polyurethane gel sheet already proposed by the inventors of the present application may be provided on the ground contact surface of the tire 25 to close the contact with the inspection surface 4 to enhance the detection sensitivity. Further, in addition to the CRT display device 16, a storage device such as a hard copy may be provided so that continuous tomographic images can be recorded on a recording sheet as inspection data. Of course, as the image storage device 18, other than the semiconductor memory, V
An appropriate image recording device such as TR can be used.

[0021]

As described above, according to the present invention, a tomographic image along the traveling direction can be continuously obtained by traveling of the tire probe, and by observing the tomographic image, defects such as cavities can be obtained. It is possible to immediately recognize the existence of the above, and to perform efficient nondestructive inspection of civil engineering and building structures without requiring skill and time for measurement.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory view of a tomographic image displayed on a CRT according to the present invention.

FIG. 3 is an explanatory view of a conventional device.

[Explanation of Codes] 1: Ultrasonic probe for transmission 2: Ultrasonic probe for reception 3: Inspection object 4: Inspection surface 5: Tire probe 6: Control circuit 7: Trigger circuit 8: Transmission circuit 9: Reception circuit 10: Signal processing circuit 11: Brightness modulation circuit 12: Vertical sweep circuit 13: Tire rotation speed detector 14: Running distance calculation circuit 15: Horizontal sweep circuit 16: CRT display device 18: Image storage device 30: Marker 32: Defect

Claims (2)

[Claims] 1. A tire probe in which a transmitting / receiving ultrasonic probe is disposed downward in a medium liquid, and an inspection by driving the transmitting ultrasonic probe at a constant cycle by a low-frequency transmission signal. A transmission circuit unit that transmits ultrasonic waves to the target object, a reception circuit unit that receives the reception signal of the reception probe and converts it into a luminance signal according to the reception level, and in the target object in synchronization with the transmission operation. A vertical sweep circuit that generates a vertical sweep signal at a sweep speed based on the propagation speed of ultrasonic waves, a rotation speed detector that detects the rotation speed of the tire probe, and a travel distance based on the detected rotation speed of the rotation speed detector. And a horizontal sweep circuit that determines a sweep position on the horizontal axis of the CRT screen according to the travel distance obtained by the travel distance calculation circuit, and an image based on a brightness signal from the reception circuit unit. For vertical and horizontal sweep signals CR to display on the screen based on
The T display device and the past image displayed on the CRT display device are stored, and the past image and the image obtained in real time are stored in the CR.
An ultrasonic flaw detector for civil engineering and building structures, comprising: an image storage device for displaying on a T display device. 2. An ultrasonic flaw detector for a civil engineering building structure, wherein the tire probe includes two transmitter ultrasonic probes and one receiving ultrasonic probe. Ultrasonic flaw detector for civil engineering structures.