JPH01112104A - Method for measuring ultrasonic wave propagation time and ultrasonic probe - Google Patents

Abstract

PURPOSE:To hold the contact medium interposition gap between a body to be measured and a surface to be measured constant and to improve measurement accuracy by providing a probe holding means between the body to be measured and the ultrasonic probe. CONSTITUTION:The probe holding jig 10 is provided between the body 11 to be measured and ultrasonic probe 12. The probe holding jig 10 is formed by providing a frame body 1 with an opening part 15 which is larger than the diameter of the probe 12 and extending plural wire materials 16 in the opening part in a tensed state. The probe holding jig 10 is mounted on the body 11 to be measured which is coated with a contact medium 13 and pressed with constant pressing force. Consequently, when the probe 12 is pressed against the body 11 to be measured, the contact medium which is as thick as the wire materials is interposed between the probe 12 and body 11 to be measured, so variance in ultrasonic wave propagation time is reducible and the measurement accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic propagation time measuring method and an ultrasonic probe.

[Prior Art] Generally, the time it takes for ultrasonic waves emitted from an ultrasonic probe to the surface to be measured of an object to be measured to reach the probe again after being reflected from the bottom surface of the object to be measured ( By measuring the ultrasound propagation time (ultrasonic wave propagation time), the thickness, sound wave propagation velocity, stress, etc. of the object to be measured can be measured.

The ultrasonic waves used in the above ultrasonic probe are mainly longitudinal waves or transverse waves of IMHz to several tens of MHz. In this ultrasonic probe, a special couplant is interposed between the surface to be measured and the probe in order to improve the efficiency of ultrasonic waves entering the object to be measured. There is. That is, for longitudinal waves, relatively low-viscosity couplants such as water, machine oil, and glycerin are used, and for transverse waves, high-viscosity couplants such as silicone grease and honey are used.

FIG. 12 is a schematic diagram showing a conventional ultrasonic propagation time measurement method, where ▪ is an object to be measured, 2 is an ultrasonic probe, and 3 is a couplant.

[Problems to be Solved by the Invention] However, the conventional ultrasonic propagation time measurement method ignores the influence of the thickness of the couplant on the measurement results, and according to the experimental results of the present inventor, the following problems occur. There is a point.

That is, a shear wave couplant is applied thinly to the surface of a steel plate as the object to be measured, a 5 MHz transverse wave probe is placed on the surface of the steel plate, and a 2 kg weight is placed on the probe. The time from the emission of ultrasonic waves by the tentacle to the reception of the waves reflected from the back surface (the time for propagation through the steel plate) was measured. Fig. 13 was obtained as a result of investigating the relationship between the elapsed time after the probe was set on the surface of the steel plate and the transverse wave propagation time. A-
E is the result of repeated investigations of different cases.

According to FIG. 13, although the transverse wave propagation time becomes constant after a certain elapsed time in each case, it is recognized that the measurement values vary widely among the cases and the reproducibility is poor. This is thought to be due to the following reasons.

(2) As the viscosity of the couplant increases, the coating thickness of the couplant between the contact and the object to be measured increases, resulting in a larger measurement error.

(2) The viscosity of the couplant changes due to temperature changes, which causes the coating thickness of the couplant to change, resulting in measurement errors.

■Differences in the pressing force of the probe change the thickness of the couplant, resulting in measurement errors.

The present invention stabilizes the thickness of the couplant and increases the ultrasonic propagation time even when the push/pull force of the probe changes or temperature changes and when using any kind of couplant. The purpose is to enable measurement with accuracy.

The ultrasonic probe according to the present invention is seated on an object to be measured in a state protruding from the probe surface of the probe body, and is located between the measuring surface of the object and the contact surface of the ultrasonic probe. The probe body is provided with a seating portion that maintains a constant couplant interposition gap, and a communication portion is formed in the seating portion for communicating the couplant interposition gap contact with an external region. It is something.

[Means for Solving the Problems] The ultrasonic propagation time measuring method according to the present invention provides a probe holding means between the object to be measured and the ultrasonic probe, and The couplant intervening gap between the probe and the probe surface of the ultrasonic probe is kept constant by the presence of the probe holding means.

The ultrasonic probe according to the present invention is seated on an object to be measured in a state that protrudes from the probe surface of the probe body, and is located between the measuring surface of the object and the contact surface of the ultrasonic probe. The probe body is provided with a seating portion that maintains a constant couplant interposition gap, and a communication portion that communicates the couplant interposition gap with an external area is formed in the seating portion. be.

[Function] According to the ultrasonic propagation time measuring method according to the present invention, the couplant interposed gap between the measurement surface of the object to be measured and the probe surface of the wave probe of the ultrasonic probe contacts. The thickness of the couplant remains constant due to the presence of the probe holding means, so the thickness of the couplant remains constant even when the pushing force of the probe changes, when there are temperature changes, and when using any type of couplant. , ultrasonic propagation time can be measured with high precision.

According to the ultrasonic probe according to the present invention, when a certain pressing force is applied to the probe and the seating portion is seated on the object to be measured, the measurement surface of the object to be measured and the ultrasonic probe are The couplant interposition gap between the sample and the probe surface is kept constant. At this time, the surplus of the couplant previously loaded in the couplant interposition gap is pushed out from the communication part of the seating part to the external area, and becomes the same constant thickness as the couplant interposition gap. In the present invention, if the size of the couplant interposed gap is known, the ultrasonic propagation time can be corrected by the thickness of the couplant interposed gap, and the ultrasonic propagation time can be determined with high precision. can be measured. In other words, the thickness of the couplant can be kept constant and the ultrasonic propagation time can be measured with high precision even when the pressing force of the probe changes or the temperature changes, and even when using any type of couplant. can.

[Example] Fig. 1 is a schematic diagram showing a first embodiment of the present invention, Fig. 2 is a plan view showing a probe holding jig, and Fig. 3 is a plane along line m-m in Fig. 2. 4 are diagrams showing the relationship between the elapsed time after contact with the probe according to the present invention and the transverse wave propagation time.

In FIG. 1, 10 is a probe holding jig, 11 is an object to be measured, 12 is an ultrasonic probe, and 13 is a couplant.

In the probe holding jig 10, an opening 15 larger than the diameter of the probe 12 is provided in a plate frame 14, and a plurality of wire members 16 are tensioned in this opening 15. The wire members 16 are stretched in a grid pattern at intervals of a fraction to a tenth of the diameter of the probe 12.

The probe holding jig 10 is placed on the object to be measured 11 coated with the couplant 13, and the probe 12 is placed on the two-legged probe holding jig 10 and is pressed with a certain amount of pressure. Pressed with pressure. The probe holding jig 10 is attached to a surface to be measured 11 of an object to be measured 11.
The couplant interposition gap between A and the probe surface 12A of the probe 12 is maintained at the same value as the wire diameter of the wire material 16. Note that when the ultrasonic probe 12 is pushed by the object to be measured 11 via the probe holding jig 10, there is a wire between the probe 12 and the object to be measured. A layer of couplant of the same thickness as the wire diameter is interposed.

Here, the pressing force applied to the ultrasonic probe 12 varies depending on the viscosity of the couplant;
The pressing force may be about 2 kg or more.

The material of the wire material 16 is preferably one that is sufficiently hard, has good wear resistance, and has high tensile strength. The cross-sectional shape of the wire material 16 is preferably circular. If the wire diameter of the wire material 16 is too large, the thickness of the couplant increases and the attenuation of ultrasonic waves by the couplant increases, so it is preferable that the wire diameter of the wire material 16 be as small as possible. The number of wire members 16 to be installed is required to be at least two directly under the probe surface 12A of the probe 12, and it is preferable that an excessive increase in the number of wire members reduces the incidence efficiency of the ultrasonic waves to the object to be measured 11. do not have.

- The measurement results of the ultrasonic propagation time using the probe holding jig 10 described in F need to be corrected based on the wire diameter of the wire material 16. That is, the measured value is based on the thickness of the object to be measured 11 and the wire material 16.
Since the propagation time corresponds to the sum of the wire diameter, it is necessary to subtract the wire diameter equivalent from the measured value.

Hereinafter, specific implementation results of the first example will be explained. The opening of the probe holding jig 10 is 30mm x 30m.
m, and wire members 16 made of tungsten wire with a wire diameter of 50 gm were stretched in the opening 15 in a lattice shape at intervals of 3 mm. A transverse wave couplant was applied thinly on a steel plate with a thickness of 13rn11, and the probe holding jig 10 was placed on top of this. The ultrasonic propagation time was measured with the probe 12 cut off and pressed against the probe 12 with a 2 kg weight.

FIG. 4 is a diagram showing the relationship between the elapsed time immediately after pushing and pulling the probe 12 and the ultrasonic propagation time. The elapsed time until the propagation time stabilized was 3 to 15 minutes using the conventional method.
2 minutes, compared to 2 minutes by the method of the present invention. In addition, the results of repeated measurement of propagation time show that the dispersion (standard deviation n = 10) of the conventional method was 0.03 h seconds, but the dispersion of the method of the present invention was 0.0011. 2 seconds, and an improvement in measurement accuracy was observed.

FIG. 5 is a schematic diagram showing a second embodiment of the present invention, and FIG. 6 is a bottom end view showing a probe holding jig.

The probe holding jig 20 of this embodiment has a cylindrical shape and is detachably mounted around the ultrasound probe 12, and the lower end surface of the jig 20 is the probe surface of the probe 12. 12A by a certain length, and has a slit 20A on the outer periphery of its lower end surface.
It is equipped with

7 is a perspective view showing a third embodiment of the present invention, FIG. 8 is a sectional view of FIG. 7, and FIG. 9 is a side view showing the state of use of FIG. 3.

The ultrasonic probe 30 of this embodiment has a cylindrical housing (
The lower end portion of the probe body 31 is a seating portion 32 that protrudes from the probe surface 3OA and is seated on the surface to be measured 11A of the object to be measured 11. The seating portion 32 maintains a constant interposition gap for the couplant 33 (see FIG. 9) between the surface to be measured 11A of the object to be measured 11 and the probe surface 3OA of the probe body 31.

At this time, the seating portion 32 is provided with a concave communication portion 34 that communicates the couplant interposed gap with the external region. 35 is a piezoelectric element. Note that the communication portion 34 may be of any type as long as it can discharge excess couplant in the couplant interposed gap to the outside area, and its shape is not limited to a rectangular shape.

Here, the ultrasonic probe 30 described in item 1 has a protrusion length of the seating portion 32 from the probe surface 30A of 10071 m or less, a depth of the concave communication portion 34 of 100Ii, a width of 111 or more, and a width of the concave communication portion 34. It is best to set the distance between 1 and 8 mm. Further, the narrower the couplant interposed gap formed by the ultrasonic probe 32, the smaller the attenuation of the ultrasonic waves and the better the measurement accuracy, and is preferably set to 5 lm to 50 lm.

According to the above-mentioned ultrasonic probe 30, a couplant is applied thinly to the surface to be measured lIA of the object to be measured 11, and the ultrasonic probe 30 is placed on top of the couplant, and the probe 30 is pressed with a certain amount of pressure. The object to be measured 1 is
The couplant interposition gap between the surface to be measured 11A of the probe 1 and the probe surface 30A of the probe 30 is kept constant. At this time, the surplus of the couplant previously loaded in the couplant interposition gap is pushed out from the concave communication part 34 of the seating part 32 to the external area, and the couplant is pushed out to the outside area to a uniform thickness that is the same as that of the couplant interposition gap. becomes. Note that if the couplant intervening gap is known, the ultrasonic propagation time can be corrected by the thickness of the couplant intervening gap, and the ultrasonic propagation time can be measured with high accuracy.

Hereinafter, specific implementation results of the present invention will be explained. 1st
As shown in Figure 0 and Figure 11, the transverse wave probe (H2 at 5,
A probe holding jig 41 was attached to the outer periphery of the probe (diameter: inch) 40. The probe holding jig 41 is attached to the probe surface 4 of the probe 40.
The surface to be measured 11A of the object to be measured 11 in a state protruding from 0A
seated on the surface 11A of the object 11 to be measured and the probe 40.
A seating portion 42 is provided to maintain a constant couplant interposition gap between the probe surface 4OA and the probe surface 4OA. Here, the probe 40 has a concave communication portion 43 that communicates the couplant interposed gap with the external region.
is provided on the seating portion 42. Here, the probe 40 has a length that the protruding end surface of the seating portion 42 protrudes from the probe surface 4OA by 20
gm (see Figure 11). With this probe 40,
As a result of measuring the ultrasonic propagation time of a steel plate (thickness 18 mm), the standard deviation of repeated measurements (n = 10) was o, O
It was observed that the measurement accuracy was improved at tg seconds compared to 0.03 g seconds using the conventional method. Note that 44 is a piezoelectric element.

As described above, according to the ultrasonic propagation time measuring method and ultrasonic probe according to the present invention, the couplant interposition gap is kept constant and the following effects are achieved.

■Even if the viscosity of the couplant becomes very high, the coating thickness of the couplant remains constant, improving the measurement accuracy of ultrasonic propagation time.

■Even if the viscosity of the couplant changes due to temperature changes, the coating thickness of the couplant does not change, improving the measurement accuracy of ultrasonic propagation time.

(2) Even if the pressing force of the probe changes, the thickness of the couplant does not change, and the measurement accuracy of the ultrasonic propagation time improves.

■The time it takes for the probe measurement results to stabilize is shortened,
Measurement work efficiency is improved.

(2) The thickness of the couplant can be accurately determined by the size of the couplant interposition gap, and the ultrasonic propagation time can be corrected by the couplant thickness, improving the measurement accuracy of the ultrasonic propagation time.

[Effects of the Invention] As described above, according to the present invention, the thickness of the couplant can be adjusted even when the pressing force of the probe changes or when there is a temperature change, or when using any kind of couplant. constant,
Ultrasonic propagation time can be measured with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the first embodiment of the present invention, FIG. 2 is a plan view showing a probe holding jig, FIG. 3 is a plan view taken along the line ■-■ in FIG. 2, and FIG. The figure is a diagram showing the relationship between the elapsed time after contact with the probe according to the present invention and the transverse wave propagation time, FIG. 5 is a schematic diagram showing the second embodiment of the present invention, and FIG. FIG. 7 is a perspective view showing the third embodiment of the present invention, FIG. 8 is a cross-sectional view of FIG. 7, and FIG. 9 is a usage state of the third embodiment. 10 is a perspective view showing a specific embodiment of the present invention, FIG. 11 is a sectional view of FIG. 10, FIG. 12 is a schematic diagram showing a conventional example, and FIG. 13 is a probe in the conventional example. FIG. 4 is a diagram showing the relationship between the time elapsed since the child was probed and the transverse wave propagation time. io...Probe holding jig, 11...Object to be measured, 11A...Measurement surface, 12...Ultrasonic probe, 12A...Probe surface, 13...Contact Medium, 20... Probe holding jig, 30... Ultrasonic probe, 30A... Probe surface, 32... Seating portion, 33... Couple material, 34... Concave shape Communication portion, 40... Shear wave probe, 4OA... Probe surface, 41... Probe holding jig. Agent Patent Attorney Osamu Shiokawa 1 Figure 2 Figure 3 Figure 4 Elapsed time (min)

Claims (2)

[Claims] (1) A probe holding means is provided between the object to be measured and the ultrasonic probe, and a couplant interposed gap is provided between the surface of the object to be measured and the probe surface of the ultrasonic probe. An ultrasonic propagation time measuring method characterized in that: is kept constant by the presence of the probe holding means. (2) The probe body is seated on the object to be measured in a state that protrudes from the probe surface, and the couplant interposition gap between the measurement surface of the object and the contact surface of the ultrasonic probe is kept constant. 1. An ultrasonic probe characterized in that the probe body is provided with a seating portion that maintains the contact area, and a communication portion that communicates the couplant interposed gap with an external region is formed in the seating portion.