JPH11160291A - Release detector and method for detecting release - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and effectively detect a release state of a damping material. SOLUTION: The release detector comprises an ultrasonic vibrator 10 brought into contact with a material 10 to be measured and coated on its surface plate 20a with a damping material 20b to generate an ultrasonic wave in response to an applied voltage and to convert a sound wave reflected from the material 20 into an electric signal, a constant-voltage power source 14 for applying a predetermined voltage to the vibrator 10, an ammeter 12 for measuring a current flowing to the vibrator 10, and an analyzer 16 for calculating an acoustic impedance based on a voltage value applied to the vibrator 10 via the power source 14 and a current value measured by the ammeter 12 and deciding presence or absence of a release of the material 20b based on the impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peeling detecting apparatus and method for detecting a peeling state for controlling the quality of a damping material for vibration and noise reduction.

[0002]

2. Description of the Related Art With respect to a damping material applied to a metal or the like to reduce vibration and noise, a peeling state of the damping material is detected for construction of the damping material or quality control. There is a need. Conventionally, in order to detect the peeling state of the damping material applied to a metal or the like, the actually applied damping material was peeled off and observed visually to determine the presence or absence of peeling.

[0003]

As described above, as a conventional method for detecting the peeling state of the vibration damping material, a method of peeling off the actually applied vibration damping material has been adopted. For this reason, a great burden is imposed on the inspector, and in some inspectors, oversight of peeling may occur.

The present invention has been made in view of the above-described circumstances, and has as its object to provide a peeling detecting device capable of easily and reliably detecting the peeling state of a vibration damping material. .

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a method in which a medium to which a vibration damping material is applied is brought into contact with a medium to generate an ultrasonic wave in accordance with an applied voltage and reflect the ultrasonic wave from the medium to be measured. A vibrator for converting an incoming sound wave into an electric signal, a power supply for applying a predetermined voltage to the vibrator, an ammeter for measuring a current flowing through the vibrator, and an electric power applied to the vibrator by the power supply And an analyzer that calculates acoustic impedance based on the voltage value to be measured and the current value measured by the ammeter and determines whether the vibration damping material has peeled off based on the acoustic impedance. It is characterized by.

[0006] Further, a diameter of a contact surface of the vibrator with the object to be measured is larger than a wavelength of an ultrasonic wave transmitted to the object to be measured. Further, the angular frequency of a voltage applied by the power supply to the device under test is represented by k1H = n
π (where, k1: 2π / λ (wavelength of ultrasonic wave), H: thickness of the medium, n: integer, π: pi).

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a peeling detection device according to the present embodiment. As shown in FIG. 1, the peeling detection apparatus according to the present embodiment includes an ultrasonic transducer 10, an ammeter 12, a constant voltage power supply 14, and an analyzer 16.

The ultrasonic vibrator 10 is used for measuring the acoustic impedance of the device 20 to be measured, and has a surface plate 20a made of metal or the like and a vibration damping material 20b applied to the surface of the device 20 to be measured. Installed in Ultrasonic transducer 1
Numeral 0 generates an ultrasonic wave in accordance with a voltage applied while being in contact with the surface of the device under test 20, transmits the ultrasonic wave to the device under test 20, and converts the reflected sound wave into an electric signal.

The ammeter 12 measures the current flowing through the ultrasonic vibrator 10, and the measured value is read by the analyzer 16. The constant voltage power supply 14 applies a voltage to the ultrasonic vibrator 10 to measure the acoustic impedance of the device under test 20, and the voltage value is read by the analyzer 16.

The analyzer 16 determines the electric terminal admittance of the ultrasonic vibrator 10 and the sound on the surface of the device under test 20 based on the current value measured by the ammeter 12 and the voltage value of the constant voltage power supply 14. The impedance is calculated to determine whether or not the damping material 20b has peeled off.

Next, the operation of the analyzer 16 for detecting the separation of the damping material 20b based on the acoustic impedance will be described. The analyzer 16 reads the current value i measured by the ammeter 12 and the voltage value v of the constant voltage power supply 14, and based on the current value i and the voltage value v, the following equation (1)
Is used to calculate the electrical terminal admittance Yf of the ultrasonic transducer 10.

[0012]

(Equation 1) The electric terminal admittance Yf of the ultrasonic transducer 10
Is represented by the following equation (2).

[0013]

(Equation 2)

Here, ω is the angular frequency of the AC voltage generated by the constant voltage power supply 14, Cd is the braking capacity of the ultrasonic oscillator 10, A is the force coefficient of the ultrasonic oscillator 10, j is the imaginary unit, Z is
Is the mechanical load impedance of the ultrasonic transducer 10.

The braking capacity Cd is determined by the ultrasonic vibrator 10
The capacitance and the force coefficient A when the distortion of the piezoelectric material used for zero is set to 0, the force generated when a unit voltage is applied to the ultrasonic vibrator 10, or the unit speed for the ultrasonic vibrator 10 The applied current and the mechanical load impedance Z are reaction forces when the ultrasonic vibrator 10 is given a unit speed.

The electric terminal admittance Yf can be obtained from the current value i and the voltage value v when the AC voltage generated by the constant voltage power supply 14 has a certain angular frequency ω, based on the above equation (1). Further, the values of the braking capacity Cd and the force coefficient A are known.

Therefore, from these known values, the above (2)
The mechanical load impedance Z can be calculated based on the equation. The mechanical load impedance Z is
It is represented by the following equation (3).

[0018]

(Equation 3)

Here, Zo is the internal mechanical impedance of the ultrasonic vibrator 10, Zs is the surface acoustic impedance of the DUT 20, and S is the area of the contact surface of the ultrasonic vibrator 10 with the DUT 20.

Here, the internal mechanical impedance Zo and the area S are known, and the mechanical load impedance Z is
Since the values are calculated based on the equation (2), the surface acoustic impedance Zs of the device under test 20 can be calculated from these values.

The analyzer 16 compares the surface acoustic impedance Zs obtained when the vibration damping material 20b is not peeled off, and the surface acoustic impedance Zs calculated beforehand with the surface acoustic impedance Zs calculated based on the equation (3). The presence or absence of peeling is determined by comparing with the surface acoustic impedance Zs when the vibration material 20b is not peeled. That is, from the surface acoustic impedance Zs, it can be determined whether the medium on the back surface of the front plate 20a is air or any other medium (damping material 20b).

When the vibration damping material 20b is not peeled off,
And the surface acoustic impedance Zs at the time of peeling is obtained as follows. The surface acoustic impedance Zs of the device under test 20 is, as shown in FIG.
Is adhered without peeling from the surface plate 20a,
The following equation (4) can be derived by solving a one-dimensional wave equation relating to a longitudinal wave in the thickness direction of the DUT 20.

[0023]

(Equation 4)

Here, Z1 is the specific acoustic impedance of the surface plate 20a, Z2 is the specific acoustic impedance of the damping material 20b, and H is the thickness of the surface plate 20a. Also, k1 =
(Ω / C1) = (2π / λ), where C1 is the longitudinal wave velocity in the surface plate 20a.

The specific acoustic impedances Z1, Z2
Is the sound pressure / particle velocity ratio of a sound wave in an infinite medium, and if the density of the medium is ρ and the sound velocity is c, it is ρc. The longitudinal wave velocity C1 is a propagation velocity of a longitudinal wave in an infinite medium.

In particular, for equation (4), k1H = nπ
In the case of (n is an integer), Zs = Z2. In deriving the equation (4), as shown in FIG. 3, the attenuation of the ultrasonic wave in the damping material 20b is large, and the influence of the reflected wave from the back surface of the damping material 20b can be neglected. I assume.

On the other hand, as shown in FIG. 4, when the damping material 20b separates from the surface plate 20a and there is an air layer, the surface acoustic impedance Zs of the device under test 20 is sufficiently smaller than the acoustic impedance of air Z1. Since it is small, it can be derived as in the following equation (5) by finding the limit where Z2 is changed to 0 in equation (4).

[0028]

(Equation 5)

In particular, for equation (5), k1H = nπ
In the case of (n is an integer), Zs = 0. Therefore, by measuring the surface acoustic impedance Zs of the device under test 20, it is possible to detect the separation of the damping material 20b. In particular, by adjusting the angular frequency of the constant voltage power supply 14 to k1H = nπ, as described above, as shown in FIG.
When there is no peeling of b, Zs = Z2, and as shown in FIG. 4, when there is peeling of the vibration damping material 20b, Zs = 0, so that the determination becomes easier.

As shown in FIG. 5, the ultrasonic transducer 10 used in the peeling detector has a diameter d (contact surface is circular) of a contact surface with the object 20 as shown in FIG.
It is configured to be sufficiently larger than the wavelength λ of the ultrasonic wave therein. Here, at least (πd
/ Λ)> 2 (π is a circle ratio). The larger the diameter d, the better.

If the diameter d of the contact surface of the ultrasonic vibrator 10 is made larger than the wavelength λ, the influence of the diffusion of the ultrasonic wave is reduced and can be neglected, and the above-described equations (4) and (5) are used. Can be established.

In the peeling detecting device, the peeled area can be determined by moving the ultrasonic transducer 10 in the area to be inspected on the surface of the measured object 20.
In this way, the DUT 2 can be measured using the ultrasonic vibrator 10.
By inspecting the surface of No. 0, the analyzer 16 can determine whether the vibration damping material 20b has peeled off from the surface plate 20a. Therefore, there is no need to perform an operation of actually peeling off and confirming the vibration damping material 20b, and the work load on the inspector is greatly reduced. In addition, the inspector does not need to make a visual determination, and the analyzer 16 determines whether or not the vibration damping material 20b has peeled, so that an erroneous inspection result such as overlooking the peeled portion can be avoided.

[0033]

As described above in detail, according to the present invention, an ultrasonic wave is generated in accordance with an applied voltage while being brought into contact with an object to be measured having a damping material applied to a medium. A transducer that converts sound waves reflected from the vibrator into an electric signal, a power supply that applies a predetermined voltage to the vibrator, an ammeter that measures the current flowing through the vibrator, and a power supply that applies a voltage to the vibrator And an analyzer that calculates the acoustic impedance based on the voltage value to be measured and the current value measured by the ammeter and determines whether or not the damping material has peeled off based on the acoustic impedance. It is not necessary to perform an operation of checking the peeling state by peeling off the damping material, and it is possible to easily and reliably detect the peeling state of the damping material.

Further, since the diameter of the contact surface of the transducer with the object to be measured is larger than the wavelength of the ultrasonic wave transmitted to the object to be measured, the influence of the diffusion of the ultrasonic wave in the medium is ignored. As a result, the acoustic impedance can be calculated.

The angular frequency of the voltage applied from the power supply to the object to be measured is represented by k1H = nπ (where k1: 2π /
λ (wavelength of ultrasonic wave), H: thickness of medium, n: integer, π:
By satisfying the relationship of (pi), the value of the acoustic impedance when the damping material is separated from the medium and when the damping material is in close contact with the medium is simplified, It is possible to easily determine whether or not the vibration damping material has peeled off by comparing this value with the value of the detected acoustic impedance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a peeling detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a vibration damping material 20b is in close contact with a front plate 20a without being separated therefrom.

FIG. 3 is an object to be measured 20 (surface plate 20a, vibration damping material 20b)
FIG. 6 is a diagram for explaining how ultrasonic waves are attenuated in FIG.

FIG. 4 is a diagram showing a state in which a damping material 20b has been peeled off from a surface plate 20a and an air layer is present.

FIG. 5 is a diagram for explaining the relationship between the diameter d of the ultrasonic transducer 10 and the wavelength λ of the ultrasonic wave.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultrasonic vibrator 12 Ammeter 14 Constant voltage power supply 16 Analyzer 20 DUT 20a Surface plate 20b Damping material

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[Procedure amendment]

[Submission date] February 23, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a method in which a medium to which a vibration damping material is applied is brought into contact with a medium to generate an ultrasonic wave in accordance with an applied voltage and reflect the ultrasonic wave from the medium to be measured. It comes a vibrator for converting an ultrasonic wave to an electrical signal, a power source for applying a predetermined voltage to the oscillator, and an ammeter for measuring a current flowing in the vibrator, with respect to the vibrator by the power supply Calculated acoustic impedance based on the applied voltage value and the current value measured by the ammeter,
An analyzer for determining whether the vibration damping material has peeled off based on the acoustic impedance.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

The ultrasonic vibrator 10 is used for measuring the acoustic impedance of the device 20 to be measured, and has a surface plate 20a made of metal or the like and a vibration damping material 20b applied to the surface of the device 20 to be measured. Installed in Ultrasonic transducer 1
0, by generating ultrasonic waves in response to the applied voltage in a state of being in contact with the surface of the object 20, and transmitted to the DUT 20, and converts the ultrasound coming reflected electrical signal.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Further, the angular frequency ω of the voltage applied from the power supply to the device under test is expressed as ωH / C1 = nπ (where C1:
By satisfying the relationship of longitudinal wave velocity in the medium, H: thickness of the medium, n: integer, π: pi, the damping material is separated from the medium, and Since the value of the acoustic impedance in the case where the medium is in close contact with the medium is simplified, it is possible to easily determine whether or not the vibration damping material has peeled off by comparing this value with the value of the detected acoustic impedance. .

Claims (4)

[Claims] 1. A method in which a medium to which a vibration damping material is applied is brought into contact with a medium to generate ultrasonic waves according to an applied voltage, and converts sound waves reflected from the object into electric signals. A vibrator; a power supply for applying a predetermined voltage to the vibrator; an ammeter for measuring a current flowing through the vibrator; a voltage value applied to the vibrator by the power supply; An analyzer that calculates acoustic impedance based on a current value measured by a meter and determines whether the vibration damping material has peeled based on the acoustic impedance. 2. The separation detecting apparatus according to claim 1, wherein a diameter of a contact surface of the vibrator with the object to be measured is larger than a wavelength of an ultrasonic wave transmitted to the object to be measured. 3. An angular frequency of a voltage applied by the power supply to the device under test is represented by k1H = nπ (where k1: 2).
π / λ (wavelength of ultrasonic wave), H: thickness of medium, n: integer,
2. The peeling detecting device according to claim 1, wherein a relationship of (π: pi) is satisfied. 4. An ultrasonic wave is generated by applying a predetermined voltage from a power source to a vibrator in contact with an object to be measured having a damping material applied to a medium, and the generated ultrasonic wave A sound wave reflected from the device under test is converted into an electric signal by the vibrator, and an acoustic impedance is calculated based on a voltage value applied to the vibrator and a current value flowing through the vibrator. A method for detecting peeling, wherein the presence or absence of peeling of the vibration damping material is determined based on impedance.