JPS61210946A - Device for inspecting interior of piping - Google Patents

Abstract

PURPOSE:To reduce the influence of irregular reflection due to unevenness in piping and to grasp properly the corrosion of the piping interior and attachment of sludges by scanning a ultrasonic wave radiated from a transducer in the axis direction of piping and adding available signal data in an adder circuit. CONSTITUTION:The transducer 6 has plural vibrators 8 arrayed in the prescribed length so as to follow the axis direction of the piping 2, and plural aggrigated vibrators 8 comprise respective blocks 10a-10c. They are sequentially excited, and a ultrasonic beam is scanned in the axis direction of the piping. Then the available echo signal data is added in the adder circuit 22, which is set to picture data corresponding to cross sectional images of one line. Thus the number of samples in the axis direction of the piping increases, and in addition mutual interference becomes less. The data includes that on situation in the axis direction of the piping, whereby an effective echo signal can be obtained even if the irregular reflection arises due to the unevenness in he piping interior.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a pipe internal inspection device for non-destructively inspecting the interior of the pipe for corrosion, sludge adhesion, etc. from the outside of the pipe.

(b) Conventional technology and its problems If the inside of a water supply pipe or air-conditioning pipe is clogged with sludge, etc., water cannot be supplied or heating or cooling cannot be performed. It would be convenient if it could be inspected non-destructively and easily.

Conventionally, there is an ultrasonic thickness gauge as a device for inspecting the inside of piping. In this ultrasonic thickness gauge, ultrasonic waves are emitted from the thickness gauge while the ultrasonic thickness gauge is in contact with the pipe, the level change of the ultrasonic echo is compared with a comparator, and the level change is measured by a frequency counter. etc. to measure the stiffness of the piping. However, with this device, the inside of the pipe can only be seen one-dimensionally, and the state of corrosion and sludge adhesion cannot be displayed two-dimensionally as a tomographic image, making it difficult to accurately grasp the situation inside the pipe. is difficult.

There are other inspection devices that use radiation such as X-rays, but with these devices the entire inspection device is large and is dangerous to handle, so it is difficult to easily inspect the inside of the piping. It is unsuitable if you want to perform an inspection.

Therefore, the present inventors applied a transducer that transmits and receives ultrasonic waves, and provided a pipe internal inspection device that displays the internal state of the pipe as a tomographic image based on the echo signal obtained by the transducer (for example, Patent application No. 59-23579
No. 2). According to this piping internal inspection device, the internal situation of the piping is displayed two-dimensionally, so it has become possible to observe the internal situation of the piping non-destructively.

However, if the inside of the pipe is uneven due to deposits such as sludge, the ultrasonic waves emitted from the transducer will be diffusely reflected by the unevenness, and this diffusely reflected echo will be received by the transducer. For this reason, the echo signal output from the transducer includes echoes from diffuse reflections as well as echoes from the sludge and rust attached to the piping and its interior. For this reason,
Echo signals caused by diffused reflection act as noise, making it difficult to effectively detect echo signals from piping and sludge adhering to the interior of the piping, which is originally necessary.

The present invention solves these conventional problems, and even when irregularities inside the piping cause diffused reflection, the influence is reduced.
The purpose is to make it possible to effectively obtain the necessary echo signals so as to accurately grasp the state of corrosion and sludge adhesion inside the piping.

(C) Means for Solving the Problems In order to achieve the above-mentioned object, the present invention uses a transducer equipped with a plurality of vibrators arranged in an array along a predetermined length along the axial direction of the piping. , an adding circuit that adds up echo signal data obtained by sequentially exciting each block composed of a plurality of the transducers of the transducer, and scans the ultrasonic waves along the axial direction of the pipe. The echo signal data obtained by the adding circuit is added to obtain image data corresponding to one line of the tomographic image.

(d) Examples Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 is a block diagram of a pipe internal inspection apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 indicates a pipe internal inspection device, 2 indicates a pipe to be measured, 4 indicates sludge adhering to the inside of the pipe 2, and 5 indicates water flowing within the pipe 2. A transducer 6 transmits ultrasonic waves into the interior of the pipe 2 and receives ultrasonic echoes reflected from inside the pipe W2.

This transducer 6 includes a plurality of vibrators 8 arranged in an array at a predetermined length along the axial direction of the pipe 2 (the Y direction in FIG. 1), and a plurality of vibrators 8 are assembled together. Each block (three blocks in this example) 10a to 10c is constructed in this manner. 12 is a multiplexer that selects and switches the transducer 8 of the transducer 6 for each block 10a-10c in order to linearly scan the ultrasonic beam along the axial direction of the pipe 2; 14 is a multiplexer that excites the transducer 6; 16 is an amplifier circuit that amplifies the echo signal output from the wave transmitting/receiving circuit 14. This amplifier circuit 16 has both logarithmic amplification characteristics and a DGC function whose gain can be varied over time. 18 is an amplifier circuit! 6 is a D/A converter that digitizes the amplified echo signal; 20 is a D/A converter 18;
This is a data memory that stores digitized echo signals.

22 is an addition circuit that adds the echo signal data for l scanning of the ultrasonic beam read out from the data memory 20;
4 is a D/A converter that converts the echo signal data added by the adding circuit 22 into analog, and 26 is a display device that displays the echo signal data converted into analog by the D/A converter 24 as an image. Further, 28 is a control circuit that controls each of the above-mentioned parts.

Next, the operation of each part when inspecting the inside of the pipe 2 by applying this pipe internal inspection device 1 will be explained.

First, as shown in FIG. 2, the transducer 6 is brought into contact with one location on the outer wall of the pipe 2. As shown in FIG. In this state, the control circuit 2
When a selection signal is given to the multiplexer 12 from 8,
Multiplexer 12 is switched to select one block, eg 10a. Next, the control circuit 28
When a control signal is given to the wave transmitting/receiving circuit 14, the wave transmitting/receiving circuit 14 outputs a drive pulse in response. This drive pulse is applied via the multiplexer 12 to each transducer 8 in the selected block 10a of the transducer 6. As a result, each vibrator 8 in the block 10a is excited simultaneously, and an ultrasonic beam is radiated into the pipe 2.

The ultrasonic beam radiated into the interior of the pipe 2 is reflected by the difference in impedance at the interface between the pipe material, the sludge 4 adhering to the pipe 2, and the water 5. This ultrasonic echo is received by all the transducers 8 of the transducer 6. Then, from the transducer 6, as shown in FIG.
As shown in , an echo signal corresponding to the received ultrasonic echo is output. The echo signal output from the transducer 6 is sent to the wave transmitting/receiving circuit 14 via the multiplexer 12, where it is amplified and detected. The echo signal that has passed through the wave transmitting/receiving circuit 14 is sent to the next stage amplifier circuit 16. The amplifier circuit 16 amplifies the echo signal while controlling the gain of the echo signal over time, and outputs the amplified echo signal to the A/D converter 18 . The echo signal data digitized by the A/D converter 18 is sent to the data memory 20 at the next stage. At this time, the control circuit 28 specifies the write address of the data memory 20, so that the echo signal obtained by exciting one block loa of the transducer 6 is stored in the data memory 20.

Subsequently, the control circuit 28 provides a selection signal to the multiplexer 12 to switch the multiplexer 12 to select the next block IOb of the transducer 6. Then, in the same manner as above, a drive pulse is applied to each vibrator 8 of the selected block tab to excite the vibrator 8, and the distribution IFZ
An echo signal based on the ultrasound echo reflected from within is stored in the data memory 20. Further, in the same manner as described above, the next block 10c of the transducer 6 is selected by the control circuit 28, and the obtained echo signal is stored in the data memory 20. In this way, the blocks 10a to 10c of the transducer 6 are sequentially selected and the transducer 8 is
When excited, the ultrasonic beam is scanned along the axial direction of the pipe 2. Then, echo signal data (data of each echo signal of (a) to (C) in FIG. 3) accompanying the scanning of the ultrasonic beam is sequentially stored in the data memory 20.

By performing the above operations while sequentially moving the transducer 6 at predetermined distance intervals along the circumferential direction of the outer wall of the pipe 2 (direction of arrow R in FIG. 2), an echo signal is generated all around the arrangement 2. Data is stored in data memory 2G.

When the data memory 20 has accumulated - data, the control circuit 28 selects data corresponding to one scan of the ultrasonic beam along the axial direction of the pipe 2 from among the echo signal data stored in the data memory 20. (For example, in this example, the third
All the echo signal data ((a) to (C) in the figure) are sequentially read out as one unit and sent to the adder circuit 22 at the next stage. The adding circuit 22 adds the echo signal data for one scan of the ultrasound beam read from the data memory 2G while aligning the time axis. Therefore, the echo signal data obtained by addition has a signal waveform as shown in FIG. The echo signal data added by the adding circuit 22 is converted into analog data by a D/A converter 24 and then output to a display 26. As a result, the display 26 displays the tomographic image of distribution w2. In this case, the value obtained by adding the echo signal data obtained by scanning the ultrasonic beam along the axial direction of the pipe 2 corresponds to the in part for monitoring the tomographic image. In other words, since each line of the tomographic image includes data on the situation in the axial direction, an effective echo signal can be obtained even if scattering occurs due to unevenness inside the pipe.

(F) Effects As described above, according to the present invention, the ultrasonic waves emitted from the transducer are scanned along the axial direction of the piping, and the echo signal data obtained thereby are added in the adding circuit. The number of directional samples increases, and mutual interference decreases. Furthermore, the data corresponding to each line of the tomographic image includes data on the axial situation of the pipe. Therefore, even if the interior of the pipe is severely uneven and causes diffused reflection, the influence is reduced and an effective echo signal can be obtained. Therefore, by displaying the obtained echo signal data as a tomographic image on a display, it becomes possible to grasp the corrosion and sludge adhesion conditions inside the pipe more accurately than before.

[Brief explanation of drawings]

゛The drawings show embodiments of the present invention. Fig. 1 is a block diagram of the pipe internal inspection device of the present invention, and Fig. 2 shows a method of operating a transducer when the same device is applied to inspect the inside of a pipe. 3 is a waveform diagram of a drive pulse for exciting the transducer and an echo signal obtained by excitation, and FIG. 4 is a waveform diagram of a signal obtained by adding the echo signals of FIG. 3. l... Piping internal inspection device, 2... Piping, 4... Sludge, 6... Transducer, 8... Vibrator,
22...Addition circuit. Figure 3 Figure 4

Claims (1)

[Claims] (1) A transducer equipped with a plurality of transducers arranged in an array in a predetermined length along the axial direction of the piping, and each block composed of the plurality of transducers of this transducer is sequentially excited. The adder circuit adds the echo signal data obtained by scanning the ultrasonic beam along the axial direction of the pipe, and adds the echo signal data obtained by scanning the ultrasonic beam along the axial direction of the pipe to obtain one line of the tomographic image. A piping internal inspection device characterized by image data corresponding to .