JPH0618501A - Ultrasonic member - Google Patents

Abstract

PURPOSE:To stably measure a surface with high accuracy even when the surface is highly rough by mounting a gel sheet formed of a high polymer gel-like elastic substance on a holder and propagating ultrasonic waves to an object to be inspected through the gel sheet. CONSTITUTION:The title member 30 houses a gel sheet 1 formed of a high polymer gel-like elastic substance in a holder 2 and secures the sheet 1 with a lid 3. Nondestructive inspections are performed or the solidified state of asphalt is measured while the sheet 1 is pressed against an asphalt-paved road 40, etc., and ultrasonic waves are propagated to the road 40 through the sheet 1. The acoustic characteristic of the sheet 1 shows values close to those of water with respect to the acoustic velocity and acoustic impedance and a low damping factor. Since the sheet l is flexible, the coupling member can be stuck to the surface of the road 40 even when the surface is highly rough. Therefore, the propagation loss of the ultrasonic waves can be reduced and the measurement sensitivity of the member can be improved remarkably. In addition, since the sheet 1 has high stability and a shape maintaining property, the sheet 1 can be repeatedly used for surfaces to be inspected even when the surfaces are highly rough and high durability is obtained from the sheet 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ultrasonic cup used for nondestructive inspection of civil engineering structures such as asphalt pavement and concrete pavement using ultrasonic waves, and measurement of the solidification state of asphalt. Regarding the ring member.

[0002]

2. Description of the Related Art Conventionally, when measuring the physical properties of a material to be inspected using ultrasonic waves, for example, when measuring the solidification status of asphalt with an asphalt solidification status monitoring device, it is sent to the road surface after the completion of asphalt pavement The trust ultrasonic transducer and the receiving ultrasonic transducer are arranged at a predetermined interval, and the ultrasonic wave emitted from the transmitting ultrasonic transducer propagates through the asphalt pavement and reaches the receiving ultrasonic transducer. The level V of the received wave is measured, and when the shoulder characteristic appears on the characteristic curve determined by the propagation time t and the received wave level V, it is determined that the asphalt has reached the solidified state of the traffic openness, It is arranged to display traffic opening (Japanese Patent Laid-Open No. 3-180757).

[0003]

However, in the conventional asphalt solidification state monitoring device, in order to improve the measurement accuracy, the transmitting ultrasonic transducer and the receiving ultrasonic transducer are still in a softened state at a high temperature. By directly abutting on the asphalt pavement surface in Fig. 1 and applying a slight load to each transducer, the contact surface between each transducer and the asphalt pavement surface is made dense.

As a result, there is a problem in that each transducer sinks into the softened asphalt pavement due to its weight, and marks are left on each transducer when the asphalt pavement solidifies. Also, if the weight of the transducer is reduced so that no trace of the transducer is left on the asphalt pavement surface, the contact between each transducer and the pavement surface will become rough and the measurement sensitivity will fluctuate unstablely.
There is a problem that the measurement accuracy is reduced.

Therefore, the inventor of the present application, as a coupling member interposed between the ultrasonic transducer and the paved road surface, as shown in FIG. 5, has clay 51 sealed with a heat-resistant polymer sheet 50. Is proposed (Japanese Patent Application No. 3-18836). However, if the coupling member in which the clay 51 is sealed with the polymer sheet 50 is pressed against a surface having large irregularities such as an asphalt pavement road surface, the polymer sheet 50 may be scratched or have holes.

When the polymer sheet 50 has a hole as described above, the asphalt paving surface immediately after construction has a high temperature, so that the water retained in the clay 51 inside is rapidly evaporated from the hole of the sheet. There are problems that the clay does not solidify, the viscoelastic properties of the clay change, the clay does not function as a coupling member, and the measured data fluctuates.

Further, since the polymer sheet 50 has holes and is easily broken, it is difficult to reuse the coupling member many times. The present invention has been made in view of such problems, even asphalt or concrete pavement with a rough uneven surface, etc., can be measured with high sensitivity and stability, pressed against the uneven surface It is an object of the present invention to provide a highly durable ultrasonic coupling member that can be reused many times without being damaged.

[0008]

First, the present invention is directed to an ultrasonic transducer for transmitting or receiving ultrasonic waves and an ultrasonic coupling member interposed between an inspection object such as an asphalt pavement having a rough surface. To do. In the present invention as such an ultrasonic coupling member, a gel sheet formed of a polymeric gel elastic body is attached to a holder, and ultrasonic waves are propagated between the gel sheet and the inspection object. It is characterized by

Here, segmented polyurethane gel is used as the polymer gel-state elastic body forming the gel sheet of the ultrasonic coupling member.

[0010]

According to the ultrasonic coupling member of the present invention having such a structure, since the gel sheet formed of the polymer gel-like elastic body having flexibility equivalent to that of the living body is pressed against the inspection surface, the asphalt pavement is paved. Even on rough inspection surfaces of civil engineering and construction structures such as road surfaces and concrete paved road surfaces, the flexibility of the gel sheet allows a familiar state of close contact with the inspection surface, which can significantly improve measurement sensitivity and improve reception sensitivity. It can stabilize and improve the measurement accuracy.

Since the gel sheet has a high restoring property, it can be repeatedly used without being damaged or broken even when it is pressed against a rough uneven surface.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a measuring probe used in a monitoring device for a solidified state of asphalt using an ultrasonic coupling member of the present invention. In FIG. 1, reference numeral 4 denotes a frame body of the measurement probe, which has weights 27 installed at both ends of the lower portion.
By 28, it is installed so as not to move on the surface of the asphalt pavement 40 to be measured.

The frame 4 is provided with a transmitting ultrasonic transducer 5 and a receiving ultrasonic transducer 6, which are supported so as to be perpendicular to the surface of the asphalt pavement 4. Here, the transmitting ultrasonic transducer 5
Has a sandwich structure in which two piezoelectric vibrators 7 and 8 are sandwiched between cylindrical duralumin blocks 9 and 10. Similarly, in the ultrasonic transducer 6 for reception, the piezoelectric vibrators 11 and 12 are provided on the circular duralumin block 13,
It has a sandwich structure sandwiched by 14.

The pressing force of the transmitting ultrasonic transducer 5 against the surface of the asphalt pavement 40 is the pressure contact rod 15 of the transducer provided on the upper part of the frame 4 and the coil spring 2.
It is performed by 0. That is, the pressure contact rod 15 is slidably provided on the frame body 4, and the tip of the transducer pressure contact rod 15 is received by the springs 16 and 17 and the acoustic isolators 18 and 19 by the spring load of the coil spring 20 inserted in the lower side.
The transmitting ultrasonic transducer 5 is pushed via the. The pressing force of the transmitting ultrasonic transducer 5 can be adjusted by changing the repulsive force of the coil spring 20.

Similarly, for the receiving ultrasonic transducer 6, the transducer pressure contact rod 21 and the coil spring 26 are also included.
Is provided, and the tip of the transducer pressure contact rod 21 is pressed by the coil spring 26 via the receiving pans 22 and 23 and the acoustic isolators 24 and 25. The coupling member 30a of the present invention is supported at the lower end of the transmitting ultrasonic transducer 5 by the holder receiving portions 31 and 32 with the leaf springs 34 and 35 interposed therebetween, and the asphalt pavement 40 is supported through the coupling member 30a. The transmitting ultrasonic transducer 5 is pressed against the surface.

Similarly, the receiving ultrasonic transducer 6
As for the coupling member 3 of the present invention, the leaf springs 36 and 37 are inserted at the lower ends and the holder receiving portions 32 and 33 are used.
0b is mounted, and the receiving ultrasonic transducer 6 is pressed against the surface of the asphalt pavement 40 via the coupling member 30b. FIG. 2 is a configuration diagram of an embodiment of the present invention in which the coupling members 30a and 30b used in the measurement probe of FIG. 1 are taken out and shown as the coupling member 30.

In FIG. 2, the coupling member 30 of the present invention accommodates the gel sheet 1 formed of a polymer gel elastic body in a holder 2 constituted by a rectangular frame member, and a lid 3
It is held by wearing. That is, as is clear from FIG. 3 showing the AA cross section of FIG. 2, the holder 2 is a box-shaped member having an open bottom with a brim for supporting the periphery thereof, and a rectangular gel sheet inside. 1 is stored, and a lid 3 is attached to and supported by the upper opening.

Here, the coupling member 30 shown in FIGS. 2 and 3 is a square having sides of about several centimeters, and the thickness D of the gel sheet 1 housed inside is about D = 5 mm. Here, the gel sheet 1 will be described in detail as follows. The gel sheet 1 is made of a polymer gel which is a one-component gel having the meaning that the gel-forming substance and the solvent are essentially chemically bonded. As such a polymer gel, for example, a polymer gel-like elastic body disclosed in JP-A-1-304109 can be used. A segmented polyurethane gel is used as an example of the polymer gel used in the gel sheet 1 of the present invention. A wide variety of segmented polyurethane gels can be obtained by changing the respective types and ratios of the isocyanate component and the polyol component, and the composition of the segment, and the segmented polyurethane gel of the segmented polyurethane used for the gel sheet 1 of the ultrasonic coupling member is Useful compositions include:

[0019]

[Chemical 1]

In the segmented polyurethane gel having this composition, the polyol is a block type prepolymer and the isocyanate is a Dernknob type prepolymer. Both of these are OH
-NCO = 1.35 was added, and the catalyst was di-butyl-Sn.
-Add a small amount of Zira Plate, thoroughly stir after degassing in vacuum and pour into a mold, degas again and stir at 60 ° C for 10
By reacting for a time, the gel sheet 1 shown in FIGS. 2 and 3 can be obtained. The gel sheet 1 thus obtained is a homogeneous transparent body, becomes an extremely flexible viscoelastic body, and has adhesiveness, so that it can be pressed against the surface of the ultrasonic transducer without using an adhesive. Can be attached.

Further, the gel sheet 1 has a very good shape-restoring property and a shape-retaining property for keeping the shape, and even if the gel sheet 1 is deformed by being pressed against a highly uneven inspection surface such as an asphalt paved road surface
It can be restored to its original state when it is stopped, and can be used repeatedly due to its high shape-recovering property and shape-retaining property, and it has sufficient durability. On the other hand, the acoustic characteristics of the gel sheet 1 due to ultrasonic wave propagation are: density; 1.02 × 10 ³ kg / m ³ sound velocity; 1459 m / s acoustic impedance; 1.49 × 10 ⁶ kg / m ² /
s Attenuation rate: 0.65 dB / cm / MHz. That is, the acoustic properties of the gel sheet 1 are close to water in terms of sound velocity and acoustic impedance, and the attenuation rate is also relatively low.

FIG. 4 shows a coupling member 30a provided on the transmitting ultrasonic transducer 5 side shown in the embodiment of FIG.
The usage state of is shown enlarged. As shown in FIG. 4, the surface of the asphalt pavement 40 has an extremely rough surface state as compared with a metal surface on which ultrasonic flaw detection or the like is performed, and even if such a rough surface is formed, the cup of the present invention may be used. In the ring member 30a, the gel sheet 1 is interposed between the transmitting ultrasonic transducer 5 and the asphalt pavement 40, so that the surface of the asphalt pavement 40 is affected by the pressing force of the transmitting ultrasonic transducer 5 from above. The deformed state conforms to the concavities and convexities, and a well-adhered contact state can be obtained, and since there is almost no gap between the transducer end surface and the inspection surface, ultrasonic waves emitted from the transmitting ultrasonic transducer 5 are transmitted. It can propagate into the asphalt pavement 40 with little attenuation. Of course, on the receiving side, the ultrasonic waves propagated through the asphalt pavement 40 can be efficiently transmitted to the transducer side.

Further, the holder 2 of the coupling member 30a has leaf springs 34 and 35 on the holder receiving portions 31 and 32 side.
Since it is supported via the, the displacement of the gel sheet 1 with respect to the holder 2 when the ultrasonic transducer 5 for transmission is pressed is suppressed to a necessary minimum. This also applies to the receiving transducer 6 side. The measuring probe shown in FIG. 1 is used as a measuring probe of the method and apparatus for measuring the degree of solidification of an asphalt pavement disclosed in JP-A-3-180757 proposed by the inventor of the present invention. The present invention is not limited to this, and the same can be applied to nondestructive inspection using ultrasonic waves of civil engineering structures such as asphalt pavement roads and concrete pavement roads where surface irregularities are severe.

[0024]

As described above, according to the present invention, the coupling member having the gel sheet formed of the extremely flexible polymer gel-like elastic body is interposed between the ultrasonic transducer and the inspection surface. So, even if the inspection surface is a highly uneven surface such as asphalt pavement, the flexibility of the gel sheet provides a familiar state in which it closely adheres to the inspection surface, and since the void can be minimized, the propagation loss of ultrasonic waves is small, The measurement sensitivity can be significantly improved, and the stability can be improved because the same measurement conditions are always obtained even if the measurement location is changed.

Further, since the gel sheet used as the coupling member has high restoring property and shape-retaining property, it can be reused repeatedly even on an inspection surface having severe unevenness, and high durability can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the structure of a measuring probe used for monitoring solidification of asphalt pavement.

FIG. 2 is a structural diagram of an embodiment of a coupling member of the present invention.

3 is a sectional view taken along line AA of FIG.

FIG. 4 is an enlarged explanatory view of a portion pressed against the asphalt pavement in FIG.

FIG. 5 is an explanatory view of a coupling member already proposed by the inventor of the present application.

[Explanation of symbols]

 1: Gel sheet 2: Holder 3: Lid 4: Frame 5: Ultrasonic transducer for transmission 6: Ultrasonic transducer for receiver 7 :, 8, 11, 12: Piezoelectric vibrator 9, 10, 13, 14: Duralumin Blocks 15 and 21: Transducer pressure welding rods 16, 17, 22, 23: Receptacles 18, 19, 24, 25: Acoustic isolator 27, 28: Weights 30, 30a, 30b: Coupling members 31, 32, 33: Holder receiving portions 34, 35, 36, 37: leaf spring 40: asphalt pavement surface

Front Page Continuation (72) Inventor Keio Atsumi 2-16-46 Minami Kamata, Ota-ku, Tokyo Tokimec Co., Ltd.

Claims (2)

[Claims] 1. An ultrasonic coupling member to be interposed between a transmitting or receiving ultrasonic transducer and an object to be inspected such as an asphalt pavement having a rough surface, which is formed of a polymer gel elastic body in a holder. An ultrasonic coupling member, characterized in that the gel sheet is attached, and ultrasonic waves are propagated between the gel sheet and an object to be inspected. 2. The tire probe according to claim 1, wherein a segmented polyurethane gel is used as a polymer gel elastic body forming the gel sheet.