JPH0148504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic method for diagnosing the shape and position of a defect inside an object using ultrasonic waves.

Conventionally, as a device for diagnosing the inside of a measured object using ultrasonic waves, ultrasonic diagnostic measurement equipment or ultrasonic
CT (Computed Tomography) devices are known and are mainly used for medical purposes. By the way, defects can be diagnosed in ultrasound diagnostic equipment by detecting ultrasound echoes, and in ultrasound CT equipment by detecting the attenuation constant distribution and sound velocity distribution of transmitted ultrasound. Therefore, in these devices, ultrasonic waves with good straightness, that is, high frequencies (for example, /M
It is necessary to use ultrasonic waves (Hz or higher).

However, since high-frequency ultrasound has a short wavelength, it is highly attenuated within the object to be measured, and therefore requires high output power. Furthermore, if the object to be measured is a material with extremely high attenuation of ultrasonic waves, such as wood or plastic, an ultrasonic generator that can produce a higher output than metal would be required, making the device extremely expensive. However, the drawback was that it was difficult to spread to the general public.

On the other hand, relatively low frequency ultrasound (50KHz~100K
Hz), and do not place too much emphasis on the straightness of the ultrasonic wave, but instead use the propagation delay caused by the defect,
Although accuracy must be sacrificed to some extent, it is extremely advantageous economically as it does not require high output. There is a device that experimentally determines the relationship between this delay time and the length of the defective part in advance, and then estimates only the length of the defective part from an experimental formula by actually measuring the delay time. For example, Utsudo Tester WTD (Eisho Denshi Co., Ltd.),
Concrete testing machine (Ultrasonic Industries Co., Ltd.)}. However, the functions of these devices alone are insufficient.
It is difficult to visualize the defect on a cross section of the object because it is not possible to determine where and what shape the defect is in the part that cannot be seen from the surface of the object. The drawback is that it is difficult to provide effective information for taking measures such as repair or replacement, and there has been a strong desire for further improvements.

In view of the above circumstances, the present invention is capable of detecting both the shape and position of a defective part using relatively low-frequency ultrasound waves, and thus provides an ultrasonic diagnosis that makes it possible to visualize the defective part. This method provides a method in which a measurement cross section is set within an object to be measured, an ultrasonic wave is emitted from a point on the outer circumference of this measurement cross section toward the center point of the measurement cross section, and the emitted ultrasonic wave is transmitted to the received at another point on the outer circumference of the measurement cross section,
In the ultrasonic diagnostic method for detecting a defective part in the object to be measured based on the ultrasonic propagation time between transmission and reception, (a) setting a test section for a part of the object to be measured without a defect, and performing the test; a first step of obtaining a reference propagation time by measuring the ultrasonic propagation time from one point on the outer periphery of the cross section to another point on the outer periphery opposing the center point of the test cross section; (b) the measurement; Assuming a plurality of virtual lines that pass through the center point of the cross section, for each virtual line, the ultrasonic propagation time is measured from the first intersection point of the virtual line and the outer circumferential line of the measurement cross section to the second intersection point. (c) for each part of the measurement cross section divided by the virtual line, emitting ultrasonic waves from one end of the measurement cross-section outer circumferential line belonging to that part toward the center point of the measurement cross-section; By receiving this emitted ultrasonic wave at the other end of the measurement section outer circumferential line belonging to that part, the ultrasonic propagation passing through each divided part is measured, and from this measurement result and the reference propagation time, the defect (d) a third step of detecting the portion where the portion is present, and (d) a portion of the virtual line that is detected by the third step at both ends of the virtual line where the measurement result in the second step shows the largest value. Two points on the outer periphery of the measurement cross section are emitted from one end belonging to the section to be measured toward the center point of the measurement cross section, and the emitted ultrasonic waves are received at one end of the virtual line next to the virtual line. The fourth to measure the ultrasonic propagation time between
The method is characterized in that the position and shape of the defective portion are detected based on the measurement results in the second and fourth steps and the reference propagation time.

An embodiment of the method according to the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of a diagnostic device to which the method according to the present invention is applied. In this figure, 1 is an ultrasonic transmitting/receiving section, 2a and 2b are a transmitting probe and a receiving probe each using a normal Langivin type transducer. The probe 3 is a digital display that displays the ultrasonic propagation time until the ultrasonic wave emitted from the transmitting probe 2a is received by the receiving probe 2b; 4 is the ultrasonic wave described above; A digital display that displays the value of the ratio between the propagation time and a reference propagation time that will be described later, 5 an image display that displays the shape and position of the defective part in the object to be measured, 6 a minicomputer, and 7 a power supply. It is a device. Note that liquid crystal displays are used for the digital displays 3 and 4 and the image display 5.

Next, the diagnosis method using this ultrasonic diagnostic device,
An example of detecting a corroded part (defective part) of a wooden telephone pole will be explained.

(1) Measuring the reference propagation time The reference propagation time is the ultrasonic propagation time in a normal part of the utility pole (the part without defects), and in this example, the ultrasonic propagation time passing through the diameter of the utility pole is the reference propagation time. It's time. The measurement of this reference propagation time is performed as follows. That is, a test cross section is set at a relatively upper part of the utility pole, and the transmitting probe 2a is brought into contact with a point on the outer periphery of the test cross section so that the ultrasonic wave is radiated toward the center point of the test cross section, A receiving probe 2 is placed at a position opposite to this transmitting probe 2a through the center of the test section.
b, and these probes 2a, 2
Measure the ultrasonic propagation time between b. This measurement result is set in the minicomputer 6. The reason why this measurement is performed at a relatively upper portion of the utility pole is that the base of the utility pole is usually corroded, and the upper portion is rarely corroded.

(2) Measurement of propagation time ratio at diametrically opposed positions of utility poles FIG. 2 is a diagram showing a hypothetical measurement cross section 10 obtained by cutting a utility pole horizontally, and the symbol H in this figure is a corroded part. In addition, this corroded part H
was created artificially for the purpose of experiment. In addition, in this figure, straight lines l ₀ , l ₁ ... l ₇ are straight lines (virtual lines) that pass through the center point Q of the measurement section 10, and form an angle of 225° with the adjacent straight lines. .

In the measurement of item (2), first, the transmitting probe 2a and the receiving probe 2b are brought into contact with points P ₀ and P′ ₀ shown in the figure, respectively, and ultrasonic waves are generated between points P ₀ and P′ ₀ . The propagation time is measured, and then the ultrasonic propagation times between P ₁ and P′ ₁ , between P ₂ and P′ ₂ , and between P ₇ and _{P 7} ′ are sequentially measured. Next, the ratio (%) between each measurement result and the reference propagation time described above is calculated. In this case, the straight line l ₀ ,
If l ₁ ... has not passed through the corroded part H (for example, straight lines l ₂ , l _3, etc.), the propagation time ratio will be 100%,
On the other hand, when passing through the corroded part H (for example,
straight line l ₀ , l ₇ ), the propagation time ratio becomes a value exceeding 100%. Next, the length of the corroded part H is calculated from the value of the propagation time ratio exceeding 100%.

The length of this corroded part H is calculated as follows. That is, sliced wood with corroded parts of various sizes artificially prepared in advance is prepared, and these sliced pieces of wood are used to calculate the degree of corrosion (the ratio of the diameter to the diametrical length of the corroded part) and the propagation time ratio. Obtain a corrosion degree curve that shows the relationship. Then, the length of the corroded part H is calculated based on this corrosion degree curve. FIG. 3 is a diagram showing an example of a corrosion degree curve, in which the vertical axis represents the propagation time ratio and the horizontal axis represents the corrosion degree. For example, when the propagation time ratio is 200%,
A corrosion degree of 17% was obtained, and as a result, the length of the corroded part H was calculated as (diameter of utility pole) x 0.17.

(3) Measurement of propagation time ratio at 90° position In the measurement of item (2) above, it is not possible to specify where the corroded part H is located on the straight lines l ₀ , l ₁ . Therefore, in the measurement of this item (3),
Is _the corroded area H located in the first quadrant defined by the straight line P ₀ Q and _the straight line P ₄ Q?
is in the second quadrant divided by
Whether it is in the third quadrant defined by P _{' 0} Q and straight line P' ₄ Q, or in the fourth quadrant defined by straight line P' ₄ Q and straight line P ₀ Q. To detect. That is, first, the transmitting probe 2a is placed at point _P0 so that the ultrasonic wave is radiated toward the center point Q.
Also, the receiving probe 2b is brought into contact with the point P ₄ and the ultrasonic propagation time between the points P ₀ and _{P 4} is measured. Next, the propagation time ratio is determined by dividing this measurement result by the reference propagation time. Similarly, between points P ₄ - P' ₀ , points P' ₀ - P' ₄ and points P' ₄ - P ₀
Measure the propagation time ratio between In this case, the propagation time ratio is 92% in the second and third quadrants where there is no corroded area H, and the propagation time ratio exceeds 92% in the first and fourth quadrants where there is corroded area H. Become. In other words, the transmission time ratio exceeds 92%. That is, the presence or absence of a corroded portion can be determined based on whether the transmission time ratio exceeds 92%. Note that the value of 92% can be obtained by pre-measuring areas with no corroded parts.

(4) Measurement of propagation time ratio at 22.5° position In the measurement of item (4), the distance t (Figure 2) of the corroded part H from the outer circumferential surface of the utility pole is measured. That is, first, straight lines l ₀ , l _{1 ,} . . . corresponding to the maximum of the measured values obtained by the measurement in item (2) above are detected. In the example shown in FIG. 2, straight line _l7 is detected. Next, as mentioned above
A point P' ₇ is obtained where the straight line l ₇ intersects with the outer circumferential line of the measurement section 10 within the quadrants (first and fourth quadrants) detected by the measurement in item (3). Then this point
The transmitting probe 2a is brought into contact with _P'7 so that the ultrasonic waves are radiated toward the center point Q, and the receiving probe 2b is brought into contact with the point _P0 or _P'6 adjacent to point _P'7 .
(22.5° position) and measure the ultrasonic propagation time between points P' ₇ and P ₀ or between points P' ₇ and P' ₆ . Next, the propagation time ratio is determined by dividing this measurement result by the reference propagation time. Then, the distance t is calculated from this propagation time ratio as follows. In other words, the distance t from the outer circumferential surface of the corroded area is determined by cutting the wood into rounds with various corroded areas in advance.
A characteristic curve showing the relationship between the propagation time ratio between the 22.5° positions is obtained. Then, the distance t is obtained based on this characteristic curve. FIG. 4 is a diagram showing an example of this characteristic curve, in which the vertical axis represents the propagation time ratio and the horizontal axis represents the distance t from the outer peripheral surface. For example, when the propagation time ratio is 60%, the distance t=
10mm is obtained. In addition, if the wooden pillar is normal,
The propagation time ratio between 22.5° positions is approximately 30%.

(5) Determination of the shape and position of the corroded part Through each of the above processes, the line segment f ₁ ~ shown in Figure 2 is determined.
The length of f ₅ and the distance t are calculated. Therefore,
With the length between the midpoint R and the center point Q of the line segment f ₁ as the radius, draw a circle centered on the center point Q, and the midpoints of each line segment f ₁ to f ₅ are on the circumference of this circle. as line segment f ₁
The position of ~ _f5 (the position on the straight lines _l7 , _l0 ...) is determined, and the shape of the corroded part is determined as the envelope of these line segments. In addition, when corroded parts occur along the outer periphery of wooden telephone poles, trees, etc., highly accurate approximation is possible by the method described above.

Figure 5 shows that the second
The position and shape of the corroded part H shown in the figure are determined, and the corroded part H is imaged based on the determination results.As is clear from the figure, the image H' is the corroded part H.
shows good agreement. Furthermore, Fig. 6 is a cross-sectional view of a wooden pole in which a corroded part _H1 has actually occurred, and Fig. 7 is an image obtained by detecting the corroded part _H1 of the wooden pole shown in Fig. 6 by the method described above. This figure also shows that the image H′ ₁ matches well with the corroded part H ₁ .
Thus, the method described above can be fully used for detecting actual corroded parts.

Figure 8 shows an artificially created "S" K in a cast aluminum alloy cylinder. Indicated by ′. As is clear from this figure, the method described above can effectively detect defects even in the case of metal materials.

In the above embodiment, only the distance t from _the point _P'7 to the corroded part H is measured in the process _{(4 ) ;} ,P′ ₅
The distance to each corroded part H may be measured in each step, and the shape and position of the corroded part H may be determined from the measurement results.

Furthermore, the reference propagation time in the above-described embodiments is not limited to the propagation time of the diameter of a wooden pole or the like. For example, if the propagation time per unit length of the object to be measured is known, this value may be set in advance using a digital switch or the like. In this case, of course, it is necessary to perform arithmetic processing within the device.

As described above, according to the present invention, both the position and shape of a defective portion can be detected using relatively low-frequency ultrasound, and as a result, imaging can be performed. Therefore, there is an advantage that repairs, replacements, etc. can be carried out accurately after a defective part is discovered. Furthermore, according to the present invention, relatively low-frequency ultrasound can be used, which provides the advantage that the diagnostic device can be constructed easily and at low cost. As a result of the above, the method according to the present invention can be applied to wooden telephone poles, trees,
It is extremely effective in detecting corroded parts of house pillars, etc., and detecting "scraps" in castings.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a diagnostic device to which the method according to the present invention is applied, and FIGS. 2 to 4 are diagrams for explaining the diagnostic method using the same diagnostic device.
Figure 2 is a diagram showing the measurement cross section 10 set on a wooden utility pole and a model corroded part H in the pole, Figure 3 is a diagram showing the relationship between corrosion degree and propagation time ratio, and Figure 4 is a diagram showing the corroded part and measurement A diagram showing the relationship between the distance t from the outer periphery of the cross section and the propagation time ratio.
Fig. 6 is a cross-sectional view of a wooden pole where a corroded part H ₁ has actually occurred, and Fig. 7 shows a corroded part H ₁ of the same wooden pole. The first
Figure 8 shows an image created using the apparatus shown in Figure 8. FIG. 4 is a diagram showing an image K' when converted into a digitized image. 1...Ultrasonic transmitter/receiver section, 2a...Transmission probe, 2b
...Receiving probe, 5...Image display, 6...Mini computer, 10...Measurement cross section.

Claims (1)

[Claims] 1. A measurement cross section is set within the object to be measured, an ultrasonic wave is emitted from a point on the outer circumference of the measurement cross section toward the center point of the measurement cross section, and the emitted ultrasonic wave is transmitted to the received at another point on the outer circumference of the measurement cross section,
In the ultrasonic diagnostic method for detecting a defective part in the object to be measured based on the ultrasonic propagation time between transmission and reception, (a) setting a test section for a part of the object to be measured without a defect, and performing the test; a first step of obtaining a reference propagation time by measuring the ultrasonic propagation time from one point on the outer periphery of the cross section to another point on the outer periphery opposing the center point of the test cross section; (b) the measurement; Assuming a plurality of virtual lines that pass through the center point of the cross section, for each virtual line, the ultrasonic propagation time is measured from the first intersection point of the virtual line and the outer circumferential line of the measurement cross section to the second intersection point. (c) for each part of the measurement cross section divided by the virtual line, emitting ultrasonic waves from one end of the measurement cross-section outer circumferential line belonging to that part toward the center point of the measurement cross-section; By receiving this emitted ultrasonic wave at the other end of the measurement section outer circumferential line belonging to that part, the ultrasonic propagation passing through each divided part is measured, and from this measurement result and the reference propagation time, the defect (d) a third step of detecting the portion where the portion is present, and (d) a portion of the virtual line that is detected by the third step at both ends of the virtual line where the measurement result in the second step shows the largest value. Two points on the outer periphery of the measurement cross section are emitted from one end belonging to the section to be measured toward the center point of the measurement cross section, and the emitted ultrasonic waves are received at one end of the virtual line next to the virtual line. The fourth measuring the ultrasonic propagation time between
An ultrasonic diagnostic method comprising the steps of: detecting the position and shape of the defective portion based on the measurement results in the second and fourth steps and the reference propagation time.