JP7327759B2 - Probe and plate thickness measuring device - Google Patents

Description

The present invention relates to a probe and plate thickness measuring device.

A plate thickness measuring device for measuring the thickness of a metal plate such as a steel plate is known. For example, the plate thickness measuring device is based on the time from contacting the probe to the surface of the metal plate and transmitting ultrasonic waves in the direction of the back surface of the metal plate to detecting the ultrasonic waves reflected on the back surface, The thickness of the metal plate was measured (for example, Patent Document 1).

JP-A-2002-39732

A contact surface of the metal plate with which the probe contacts is sometimes provided with a coating layer for the purpose of protecting the metal plate. Such a coating layer absorbs and scatters ultrasonic waves due to aged deterioration and the like, and may attenuate ultrasonic waves propagating through the metal plate. In this case, it may be difficult for the plate thickness measuring device to measure the thickness of the metal plate having the deteriorated coating layer.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a probe for a plate thickness measuring apparatus that accurately measures the thickness of a metal plate having a deteriorated coating layer.

In a first aspect of the present invention, a probe used in a plate thickness measuring device for measuring the thickness of a metal plate, the contact surface contacting the first surface of the metal plate, and the contact surface an ultrasonic wave transmitted from the first transmitting transducer and reflected by the metal plate via the contact surface; a receiving unit having a first receiving transducer that receives sound waves; and a first isolating unit that blocks propagation of ultrasonic waves from the transmitting unit to the receiving unit, wherein the first receiving transducer Provided is a probe in which a center frequency of frequency characteristics for receiving ultrasonic waves is lower than a center frequency of frequency characteristics of ultrasonic waves generated by the first transmitting transducer.

The first isolation section may have a surface orthogonal to the contact surface between the transmission section and the reception section.

The metal plate has a coating layer formed on at least a part of the first surface, and the center frequency of the ultrasonic reception band of the first receiving transducer is the frequency generated by the first transmitting transducer. The frequency may be included in a frequency band in which the attenuation rate of the coating layer is 90% or less in the ultrasonic frequency band.

The transmitting section further includes a transmitting-side fixing section that fixes the first transmitting-side transducer, and the first transmitting-side transducer is fixed to the transmitting-side fixing section on the side opposite to the contact surface in the transmitting-side securing section. The transmission-side fixing surface is a region that includes a part of a second surface of the metal plate opposite to the first surface from which ultrasonic waves generated by the first transmission-side transducer are transmitted. It may have a curved surface with a curvature that converges to .

The receiving section further includes a receiving-side fixing section that fixes the first receiving-side transducer, and the first receiving-side transducer is fixed to the receiving-side fixing section on the opposite side of the receiving-side fixing section from the contact surface. The receiving-side fixing surface has a curved surface with a curvature that allows ultrasonic waves reflected and diffused from a part of the second surface of the metal plate to reach the first receiving-side transducer. You may

The transmitting-side fixed surface and the receiving-side fixed surface may be different curved surfaces of a common spherical surface centered on a predetermined common point.

The transmitting unit further includes a second transmitting transducer that transmits an ultrasonic wave toward the first surface of the metal plate, and the receiving unit transmits ultrasonic waves from the second transmitting transducer and transmits the ultrasonic wave to the first surface of the metal plate. It may further include a second receiving transducer for receiving the ultrasonic waves reflected by the first surface of the plate.

The center frequency of the frequency characteristics of the ultrasonic waves emitted by the second transmitting transducer may match the center frequency of the ultrasonic reception band of the second receiving transducer.

The contact surface is circular, and at least a part of the transmitting section, the receiving section, and the first separating section integrally has a cylindrical shape extending in a direction perpendicular to the contact surface, Inside the cylinder, a first region in which the first transmitting transducer and the first receiving transducer transmit and receive ultrasonic waves is a region where the second transmitting transducer and the second receiving transducer transmit and receive ultrasonic waves. may be provided on the outer peripheral side of the second area, unlike the second area that transmits and receives the .

Between the first region and the second region, a second isolating portion that blocks propagation of ultrasonic waves is provided. It may be part.

The transmission section may have a first recess in a part of the transmission-side fixing surface, and the second transmission-side transducer may be provided on a bottom surface of the first recess.

The receiving section may have a second recess in a part of the receiving-side fixed surface, and the second receiving-side transducer may be provided on a bottom surface of the second recess.

In a second aspect of the present invention, there is provided a plate thickness measuring device for measuring the thickness of a metal plate, comprising the probe of the first aspect, and the transmitting section of the probe generating ultrasonic waves. A signal supply unit that supplies a drive signal for causing a signal to be obtained, a signal acquisition unit that acquires an ultrasonic signal received by the reception unit of the probe, and a thickness of the metal plate based on the ultrasonic signal. A plate thickness measuring device is provided, comprising a calculator for calculating

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to measure accurately the thickness of the metal plate which has the coating layer which deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the outline|summary of the plate|board thickness measuring apparatus 10 which concerns on this embodiment. 1 shows a first example of propagation characteristics of a metal plate 20 having a coating layer according to this embodiment. A second example of the propagation characteristics of the metal plate 20 having the coating layer according to this embodiment is shown. A first configuration example of the probe 30 according to this embodiment is shown together with the metal plate 20 . An example of the figure seen from the contact surface 130 side of the probe 30 of the first configuration example is shown. A second configuration example of the probe 30 according to this embodiment is shown together with the metal plate 20 . An example of the figure seen from the contact surface 130 side of the probe 30 of a 2nd structural example is shown. 4 shows a conceptual diagram of a signal waveform of an ultrasonic signal acquired from a probe 30 by a signal acquisition unit 50 according to the present embodiment. FIG.

<Configuration example of plate thickness measuring device 10>
FIG. 1 is a diagram for explaining an outline of a plate thickness measuring device 10 according to this embodiment. FIG. 1(a) is a functional configuration diagram of the plate thickness measuring device 10. FIG. FIG. 1(b) is a schematic cross-sectional view of a metal plate 20 whose thickness is to be measured by the plate thickness measuring device 10. As shown in FIG. The plate thickness measuring device 10 nondestructively measures the thickness of the metal plate 20 using ultrasonic waves. The metal plate 20 is a plate made of metal, and is, for example, a steel plate such as general structural rolled steel. In this embodiment, the thickness of the metal plate 20 measured by the plate thickness measuring device 10 is the distance between the first surface 21 of the metal plate 20 and the second surface 22 opposite to the first surface 21. . A coating layer 23 is formed on at least a portion of the first surface 21 of the metal plate 20 . The coating layer 23 is provided for purposes such as protection of the metal plate. The plate thickness measuring apparatus 10 includes a probe 30 , a signal supply section 40 , a signal acquisition section 50 , a calculation section 60 and a display section 70 .

The probe 30 is in contact with the metal plate 20 to be measured, transmits ultrasonic waves, and receives reflected waves of the transmitted ultrasonic waves. The probe 30 has a transmitter 110 , a receiver 120 and a contact surface 130 . The transmission unit 110 transmits ultrasonic waves to the metal plate 20 according to a drive signal supplied from the outside. The receiving part 120 receives the ultrasonic waves reflected by the second surface 22 opposite to the first surface 21 of the metal plate 20 . The contact surface 130 is a surface that contacts the first surface 21 of the metal plate 20 when measuring the thickness of the metal plate 20 . A more detailed description of such a probe 30 will be given later.

The signal supply unit 40 supplies a drive signal for generating ultrasonic waves to the transmission unit 110 of the probe 30 . The signal supply unit 40 supplies, for example, a predetermined pulse drive signal such as a spike wave or a rectangular wave. The signal supply unit 40 supplies a drive signal of about one to several wavelengths. As a result, the ultrasonic waves transmitted by the transmitter 110 have a certain amount of bandwidth. For example, it is desirable that the ultrasonic wave has a bandwidth of about 1/2 or more of the value of the center frequency. The signal supply unit 40 supplies the transmission unit 110 with a driving signal for generating such ultrasonic waves.

The signal acquisition unit 50 acquires ultrasonic signals received by the reception unit 120 of the probe 30 . The signal acquisition unit 50 acquires a temporal change in the output signal output by the reception unit 120 as an ultrasonic signal. For example, the signal acquisition unit 50 stores the acquired ultrasound signals in a storage unit or the like.

The calculator 60 calculates the thickness of the metal plate 20 based on the ultrasonic signal. For example, the calculation unit 60 calculates the thickness of the metal plate 20 based on the difference between the timings of detecting the ultrasonic waves reflected by the first surface 21 and the ultrasonic waves reflected by the second surface 22 of the metal plate 20. Calculate Calculation of the thickness by the calculation unit 60 is based on a known method, so the description is omitted here. The calculation unit 60 stores, for example, the calculated thickness of the metal plate 20 in the storage unit or the like. Further, the calculation unit 60 may store the calculation results in an external database or the like.

The display unit 70 displays the calculated thickness of the metal plate 20 as a measurement result. In addition, the display unit 70 may display the time waveform and/or frequency characteristics of the ultrasonic signal. Further, the display unit 70 may display a plurality of different positions on the metal plate 20 and the thickness measurement results at the plurality of positions in association with each other.

The plate thickness measuring apparatus 10 described above calculates the thickness of the metal plate 20 based on the time for the ultrasonic wave to propagate through the metal plate 20 . Here, if the coating layer 23 provided on the metal plate 20 is in a normal state, ultrasonic waves of about several MHz can be propagated as described below.

<Propagation characteristics of metal plate 20 having normal coating layer 23>
FIG. 2 shows a first example of propagation characteristics of the metal plate 20 having the coating layer 23 according to this embodiment. FIG. 2 shows an example of propagation characteristics when the coating layer 23 is normal. In FIG. 2, the horizontal axis indicates the frequency of the ultrasonic wave, and the vertical axis indicates the transmittance of the ultrasonic wave. The propagation characteristics shown in FIG. 2 are obtained by Fourier-transforming the waveform on the time axis of the ultrasonic waves reflected from the second surface 22 of the metal plate 20 detected by the thickness measuring device 10 into characteristics on the frequency axis. is an example.

From FIG. 2, it can be seen that the metal plate 20 having a normal coating layer 23 can propagate ultrasonic waves of about several MHz. Therefore, the plate thickness measuring device 10 can measure the thickness of the metal plate 20 based on the reflected ultrasonic waves. The plate thickness measuring apparatus 10 can measure the thickness of the metal plate 20 with higher accuracy by increasing the frequency of the ultrasonic waves used. Therefore, it is desirable that the frequency of the ultrasonic waves used by the plate thickness measuring apparatus 10 is a higher frequency within a band in which the metal plate 20 to be measured has a high transmittance of ultrasonic waves.

Therefore, conventionally, for example, ultrasonic waves with a center frequency of about 5 MHz are used in order to measure the thickness of the metal plate 20 with an error of about ±0.1 mm. In this case, the transmitting section 110 and the receiving section 120 of the probe 30 are each provided with a vibrator having a natural vibration frequency of approximately 5 MHz. However, if the coating layer 23 deteriorates, the propagation characteristics of the metal plate 20 may change significantly.

<Propagation characteristics of metal plate 20 having deteriorated coating layer 23>
FIG. 3 shows a second example of propagation characteristics of the metal plate 20 having the coating layer 23 according to this embodiment. FIG. 3 shows an example of propagation characteristics when the coating layer 23 has deteriorated due to aged deterioration or the like. In FIG. 3, as in FIG. 2, the horizontal axis indicates the frequency of the ultrasonic wave, and the vertical axis indicates the transmittance of the ultrasonic wave. As shown in FIG. 3, deterioration of the coating layer 23 deteriorates the propagation characteristics of ultrasonic waves. For example, it can be seen that the propagation characteristics in the high frequency range of 3 MHz or higher are degraded. In this case, the plate thickness measuring apparatus 10 using ultrasonic waves with a center frequency of about 5 MHz cannot detect the reflected ultrasonic waves, and cannot measure the thickness of the metal plate 20 .

Measurement of the thickness of the metal plate 20 may be performed, for example, for the purpose of maintenance and inspection of the metal plate 20 after it is formed as a structure. As an example, when the metal plate 20 is formed as an oil tank or the like, the second surface 22 of the metal plate 20 opposite to the coating layer 23 and in contact with the oil may corrode. As such corrosion progresses, the thickness of at least a portion of the metal plate 20 becomes thinner, so the degree of corrosion can be confirmed by measuring the thickness of the metal plate 20 with the plate thickness measuring device 10. can.

Therefore, after the metal plate 20 is formed as an oil tank or the like, the thickness of the metal plate 20 can be periodically measured from the first surface 21 side of the coating layer 23 side, and the oil tank can be easily maintained and inspected. A plate thickness measuring device 10 has been desired. However, when the coating layer 23 deteriorates over time, the propagation characteristics of ultrasonic waves deteriorate as shown in FIG. was becoming difficult.

Therefore, the plate thickness measuring apparatus 10 according to the present embodiment adjusts the frequency characteristics of the oscillator of the transmitter 110 and the oscillator of the receiver 120 so as to correspond to the damping characteristics of the coating layer 23, respectively. To accurately measure the thickness of a metal plate 20 whose 23 is deteriorated. Next, the probe 30 provided in the plate thickness measuring apparatus 10 will be described.

<First Configuration Example of Probe 30>
FIG. 4 shows a first configuration example of the probe 30 according to this embodiment together with the metal plate 20 . FIG. 4 shows an example in which the probe 30 is in contact with the metal plate 20 to measure the thickness of the metal plate 20 . Moreover, FIG. 5 shows an example of a view of the probe 30 of the first configuration example viewed from the contact surface 130 side. In FIGS. 4 and 5, two orthogonal directions are shown as X-axis, Y-axis and Z-axis. The probe 30 of the first configuration example includes a transmission section 110 , a reception section 120 , a contact surface 130 , a first isolation section 140 , a housing section 150 and an electrode section 160 . As described with reference to FIG. 1, the transmitter 110 transmits ultrasonic waves and the receiver 120 receives ultrasonic waves.

The transmitting section 110 has a first transmitting transducer 112 and a transmitting fixed section 114 . The first transmitting transducer 112 transmits ultrasonic waves toward the metal plate 20 via the contact surface 130 . The first transmitting transducer 112 generates ultrasonic waves according to the electrical signal input from the signal supplying section 40 . The first transmitting transducer 112 is, for example, a piezoelectric transducer such as a piezoelectric element. The first transmitting transducer 112 is preferably a composite piezoelectric transducer.

The transmission-side fixing section 114 fixes the first transmission-side transducer 112 . The transmitter fixing portion 114 includes a first facing surface 115 and a transmitter fixing surface 116 . The first facing surface 115 is a surface facing the metal plate 20 and forms part of the contact surface 130 . The transmission-side fixing surface 116 is a surface provided on the opposite side of the contact surface 130 . The first transmitting transducer 112 is provided, for example, on the transmitting fixed surface 116 and transmits ultrasonic waves to the metal plate 20 via the first opposing surface 115 .

The receiving section 120 has a first receiving transducer 122 and a receiving fixing section 124 . The first receiving transducer 122 receives the ultrasonic waves transmitted from the first transmitting transducer 112 and reflected by the metal plate via the contact surface 130 . The first receiving transducer 122 generates an electrical signal corresponding to the received ultrasonic wave and supplies the electrical signal to the signal acquiring section 50 . The first receiving transducer 122 is, for example, a piezoelectric transducer such as a piezoelectric element, like the first transmitting transducer 112 . The first receiving transducer 122 is preferably a composite piezoelectric transducer.

The receiving side fixing section 124 fixes the first receiving side transducer 122 . The receiving side fixing portion 124 includes a second facing surface 125 and a receiving side fixing surface 126 . The second facing surface 125 faces the metal plate 20 and forms part of the contact surface 130 . The receiving side fixing surface 126 is a surface provided on the side opposite to the contact surface 130 . The first receiving transducer 122 is provided, for example, on the receiving fixed surface 126 and receives ultrasonic waves reflected from the metal plate 20 via the second opposing surface 125 .

The contact surface 130 contacts the first surface 21 of the metal plate 20 . The contact surface 130 is a flat surface formed by the first facing surface 115 of the transmitting side fixed portion 114 and the second facing surface 125 of the receiving side fixed portion 124 .

The first isolator 140 blocks propagation of ultrasonic waves from the transmitter 110 to the receiver 120 . The first isolation part 140 has a surface orthogonal to the contact surface 130 between the transmission part 110 and the reception part 120 . The first isolation section 140 is, for example, a plate-like member sandwiched between the transmission section 110 and the reception section 120 . The first isolation part 140 has, for example, a material containing air such as cork.

At least a part of the transmitting section 110, the receiving section 120, and the first isolating section 140 described above is, for example, integrally formed. In addition, at least a part of transmitting section 110 , receiving section 120 , and first isolating section 140 has, as an example, a cylindrical shape extending in a direction perpendicular to contact surface 130 . In this case, the contact surface 130 is of circular design.

The accommodation unit 150 accommodates at least part of the transmission unit 110 , the reception unit 120 and the first isolation unit 140 . At least part of the accommodating part 150 is formed in a cylindrical shape, covers at least part of the transmitting part 110, the receiving part 120, and the first isolating part 140, and exposes the contact surface 130 to the outside.

The electrode portion 160 is provided on the surface of the housing portion 150 opposite to the contact surface 130 and exchanges electrical signals with the outside. The electrode section 160 has, for example, a transmitter electrode 162 and a receiver electrode 164 . The transmitter electrode 162 is electrically connected to the first transmitter transducer 112 . The transmission side electrode 162 is electrically connected to the signal supply section 40 , receives the drive signal supplied from the signal supply section 40 and transmits it to the first reception side transducer 122 . The receiving electrode 164 is electrically connected to the first receiving transducer 122 . The receiving electrode 164 is electrically connected to the signal acquiring section 50 and transmits the ultrasonic signal output from the first receiving transducer 122 to the signal acquiring section 50 .

In the probe 30 of this embodiment described above, the frequency characteristics of the first transmitting transducer 112 and the first receiving transducer 122 are adjusted to measure the thickness of the metal plate 20 having the deteriorated coating layer 23. It is For example, the center frequency of the ultrasonic reception band of the first receiving transducer 122 has an attenuation rate of 90% or less in the coating layer 23 in the frequency band of the ultrasonic waves generated by the first transmitting transducer 112. It is a frequency included in the frequency band that becomes

As an example, when the coating layer 23 deteriorates as shown in FIG. 3, the band in which the attenuation rate of the coating layer 23 is 90% or less is the band from approximately 0.1 MHz to approximately 3.2 MHz. In other words, most of the ultrasonic waves with frequencies above approximately 3.2 MHz do not reach the first receiving transducer 122 . Therefore, the natural frequency of the first reception-side transducer 122 is set in a range from approximately 0.1 MHz to approximately 3.2 MHz.

Preferably, the center frequency of the ultrasonic wave reception band of the first receiving transducer 122 is a frequency included in the frequency band in which the attenuation rate of the coating layer 23 is 70% or less. In this case, the band in which the attenuation factor of the coating layer 23 is 70% or less is the band from approximately 0.3 MHz to approximately 2.75 MHz. More preferably, the center frequency of the ultrasonic reception band of the first receiving transducer 122 is a frequency included in the frequency band in which the attenuation rate of the coating layer 23 is 50% or less. In this case, the band in which the attenuation factor of the coating layer 23 is 50% or less is the band from approximately 0.5 MHz to approximately 2.5 MHz.

Within such a band range, the center of the reception band of the first reception transducer 122 is set so that the higher frequency of the ultrasonic waves transmitted by the coating layer 23 can be detected in order to prevent the measurement accuracy from deteriorating. It is desirable to preset the frequency. For example, the natural frequency of the first receiving transducer 122 is set in advance so that, of the ultrasonic waves transmitted through the coating layer 23, ultrasonic waves of approximately 3.2 MHz or less can be detected.

In this embodiment, the center frequency of the ultrasonic reception band of the first receiving transducer 122 is set to about 2 MHz. Also, the bandwidth of the ultrasonic reception band of the first receiving transducer 122 may be about 2 MHz or more. As described above, by setting the center frequency of the frequency characteristics of the first receiving transducer 122 for receiving ultrasonic waves to be lower than the center frequency of the frequency characteristics of the ultrasonic waves generated by the first transmitting transducer 112, The ultrasonic wave reception efficiency of the probe 30 can be improved.

In addition, since the high-frequency component of the ultrasonic waves generated by the first transmitting transducer 112 is attenuated by the coating layer 23, the frequency characteristics of the first transmitting transducer 112 are also reduced to low frequencies within the range allowed by the measurement accuracy. You can shift to the side. For example, when measuring the thickness of the metal plate 20 with an error of about ±0.1 mm, the center frequency of the frequency characteristics of the ultrasonic waves generated by the first transmitting transducer 112 is set to about 3.5 MHz.

In this way, even if the coating layer 23 deteriorates and attenuates the high frequency components of the ultrasonic waves, among the ultrasonic waves transmitted by the transmission unit 110, the ultrasonic waves in the frequency band that can be propagated within a range where the measurement accuracy does not decrease are increased. By increasing the distance, the propagation efficiency of ultrasonic waves of the probe 30 can be improved. Therefore, the plate thickness measuring apparatus 10 using such a probe 30 can accurately measure the thickness of the metal plate 20 regardless of the deterioration state of the coating layer 23 .

In the probe 30 according to the present embodiment described above, an example in which the frequency characteristics of the first transmitting transducer 112 and the first receiving transducer 122 are adjusted to improve the ultrasonic wave detection efficiency has been described. is not limited to In the probe 30, the shapes of the first transmitting transducer 112 and the first receiving transducer 122 may be adjusted to improve the ultrasonic wave detection efficiency.

In this case, as shown in FIG. 4, the transmission-side fixing surface 116 of the transmission-side fixing portion 114 transmits the ultrasonic waves generated by the first transmission-side transducer 112 to the side opposite to the first surface 21 of the metal plate 20 . It is provided so as to have a curved surface with curvature that converges on a region that includes a portion of the second surface 22 . For example, the transmitter fixed surface 116 has a curved surface that is part of a sphere centered at a predetermined point. As a result, the first transmitting transducer 112 is formed along the curved surface of the transmitting fixed surface 116 and has a curved surface similar to the curved surface of the transmitting fixed surface 116 .

Ultrasonic waves generated by the first transmitting transducer 112 having such a curved surface are concentrated in a region including part of the second surface 22 of the metal plate 20 . Therefore, the intensity of the ultrasonic waves reflected by a part of the second surface 22 of the metal plate 20 can be increased, and the first receiving transducer 122 detects such ultrasonic waves, thereby The detection efficiency of the side vibrator 122 can be improved.

Alternatively or additionally, the shape of the receiver fixing portion 124 may be adjusted as shown in FIG. In this case, the receiving fixing surface 126 is provided to have a curved surface with a curvature that allows ultrasonic waves reflected and diffused from a portion of the second surface 22 of the metal plate 20 to reach the first receiving transducer 122. ing. For example, the receiving fixed surface 126 has a curved surface that is part of a sphere centered at a predetermined point.

As a result, the first receiving-side transducer 122 is formed along the curved surface of the receiving-side fixing surface 126 and has a curved surface similar to the curved surface of the receiving-side fixing surface 126 . Therefore, the first receiving transducer 122 can efficiently collect the ultrasonic waves reflected and diffused from the second surface 22 of the metal plate 20, thereby improving the detection efficiency.

In addition, when the transmitting side fixing surface 116 and the receiving side fixing surface 126 each have a curved surface, the transmitting side fixing surface 116 and the receiving side fixing surface 126 have a common spherical surface centered on a predetermined common point. It is desirable that they are curved surfaces with different parts. Thereby, the reflected light of the ultrasonic waves generated by the first transmitting transducer 112 and concentrated on a part of the second surface 22 can be efficiently received by the first receiving transducer 122 .

In the probe 30 according to the present embodiment described above, an example in which each of the transmitter 110 and the receiver 120 has one transducer has been described, but the present invention is not limited to this. Transmitting section 110 and/or receiving section 120 may have a plurality of transducers. For example, the transmitter 110 and/or the receiver 120 may have a plurality of transducers corresponding to ultrasonic waves reflected by the first surface 21 and the second surface 22 of the metal plate 20, respectively. An example in which the transmitting unit 110 and the receiving unit 120 each have two transducers corresponding to the ultrasonic waves reflected by the first surface 21 and the second surface 22 of the metal plate 20 will be described below.

<Second Configuration Example of Probe 30>
FIG. 6 shows a second configuration example of the probe 30 according to this embodiment together with the metal plate 20 . FIG. 7 shows an example of a view of the probe 30 of the second configuration example viewed from the contact surface 130 side. In FIGS. 6 and 7, two orthogonal directions are shown as X-axis, Y-axis and Z-axis. In the probe 30 of the second configuration example, the same reference numerals are assigned to the operations that are substantially the same as those of the probe 30 of the first configuration example according to the present embodiment shown in FIG. 4, and description thereof is omitted. . In the probe 30 of the second configuration example, the transmitting section 110 further has a second transmitting transducer 212 and the receiving section 120 further has a second receiving transducer 222 . Also, the probe 30 further includes a second isolation section 250 .

The second transmitting transducer 212 transmits ultrasonic waves toward the first surface 21 of the metal plate 20 . The second transmitter transducer 212 generates ultrasonic waves in response to the electrical signal input from the signal supply unit 40, similarly to the first transmitter transducer 112. FIG. The second transmitting transducer 212 is, for example, a piezoelectric transducer such as a piezoelectric element. The second transmitter transducer 212 is fixed to the transmitter fixing section 114 .

The second receiving transducer 222 receives the ultrasonic waves transmitted from the second transmitting transducer 212 and reflected by the first surface 21 of the metal plate 20 . Similarly to the first receiving transducer 122 , the second receiving transducer 222 generates an electrical signal corresponding to the received ultrasonic wave and supplies the electrical signal to the signal acquisition unit 50 . The second receiving transducer 222 is, for example, a piezoelectric transducer such as a piezoelectric element, like the second transmitting transducer 212 . The second receiving transducer 222 is fixed to the receiving fixing section 124 .

The probe 30 of the second configuration example has, for example, a contact surface 130 formed in a circular shape similarly to the probe 30 of the first configuration example. At least part of the transmitting section 110 , the receiving section 120 , and the first separating section 140 integrally has a cylindrical shape extending in a direction orthogonal to the contact surface 130 . Here, inside the cylinder, a region in which the first transmitting transducer 112 and the first receiving transducer 122 transmit and receive ultrasonic waves is defined as a first region 230, and the second transmitting transducer 212 and the second receiving transducer A second region 240 is defined as a region in which the transducer 222 transmits and receives ultrasonic waves. In this case, it is preferable that the first area 230 and the second area 240 are different from each other without overlapping.

For example, the first region 230 is provided on the outer peripheral side of the second region 240 . In this case, the first region 230 and the second region 240 are formed concentrically in a cross section substantially parallel to the XY plane of the first region 230 and the second region 240 . The second region 240 is formed inside the first region 230 inside the cylinder, and is formed so that the region becomes smaller as it approaches the contact surface 130 . That is, the boundary between the first region 230 and the second region 240 has the shape of a portion of a cone.

A second isolation portion 250 is provided between the first region 230 and the second region 240 to block the propagation of ultrasonic waves. The second isolation part 250 is made of the same material as the first isolation part 140, for example. Also, the second isolation part 250 is, for example, a part of a cone whose central axis is the central axis of a cylinder formed by at least part of the transmission part 110 , the reception part 120 and the first isolation part 140 . By providing such a second isolation part 250, the ultrasonic waves transmitted and received in the first region 230 and the ultrasonic waves transmitted and received in the second region 240 are isolated, and interference occurs inside the probe 30. can be prevented.

In the probe 30 of the second configuration example, the first receiving transducer 122 receives the ultrasonic waves reflected by the second surface 22 of the metal plate 20 among the ultrasonic waves generated by the first transmitting transducer 112. do. Among the ultrasonic waves generated by the second transmitting transducer 212 , the ultrasonic waves reflected by the first surface 21 of the metal plate 20 are received by the second receiving transducer 222 . As described above, since the probe 30 has a plurality of transducers corresponding to the reflecting surfaces of the metal plate 20, the transducers are arranged corresponding to the respective reflecting surfaces to generate ultrasonic waves. Detection efficiency can be improved respectively.

For example, the frequency characteristics of the first transmitting transducer 112 and the first receiving transducer 122 are adjusted according to the coating layer of the metal plate 20 as described above. On the other hand, the center frequency of the frequency characteristics of the ultrasonic waves emitted by the second transmitting transducer 212 and the center frequency of the ultrasonic reception band of the second receiving transducer 222 may be matched.

Since the ultrasonic waves transmitted and received in the second region 240 are reflected by the first surface 21 of the metal plate 20, there is no absorption and scattering inside the metal plate 20, and compared to the ultrasonic waves transmitted and received in the first region 230, the signal Level loss is small. Therefore, the detection efficiency of ultrasonic waves transmitted and received in the second area 240 may be lower than the detection efficiency of ultrasonic waves transmitted and received in the first area 230 . In this case, the center frequency of the ultrasonic waves transmitted and received in the second region 240 may be a band with a lower transmittance than the center frequency of the ultrasonic waves transmitted and received in the first region 230 .

For example, the center frequency of the ultrasonic waves transmitted and received in the second region 240 is made higher than the center frequency of the ultrasonic waves transmitted and received in the first region 230 . As an example, when measuring the thickness of the metal plate 20 with an error of about ±0.1 mm, the center frequency of the ultrasonic waves transmitted and received in the first region 230 is set to 2 MHz, and the ultrasonic waves generated by the second transmitting transducer 212 are The center frequency of the frequency characteristics of is about 3.5 MHz. The center frequency of the ultrasonic wave reception band of the second receiving transducer 222 is set to about 3.5 MHz. As a result, compared to the peak value of the ultrasonic wave detection signal transmitted and received in the first region 230, the peak value of the ultrasonic wave detection signal transmitted and received in the second region 240 can be made equal to or less than the peak value. Separation of detected signals can be facilitated.

When the thickness of the metal plate 20 is reduced, the detection timing of the ultrasonic waves transmitted and received in the first region 230 (referred to as the first timing) and the detection timing of the ultrasonic waves transmitted and received in the second region 240 (referred to as the second timing) ) becomes small, and separation of the detection signal may become difficult. Therefore, in order to add an offset to the difference between the first timing and the second timing, the arrangement of the plurality of vibrators may be varied in the direction perpendicular to the contact surface 130 .

In this case, as shown in FIG. 6, the transmitting section 110 has a first concave portion 118 in a part of the transmitting side fixing surface 116, and a second transmitting transducer 212 is provided on the bottom surface of the first concave portion 118. there is That is, the second transmitter transducer 212 is formed at a position closer to the contact surface 130 than the first transmitter transducer 112 is. Therefore, the ultrasonic waves generated by the second transmitting transducer 212 reach the metal plate 20 faster than the ultrasonic waves generated by the first transmitting transducer 112, so that the first timing and the second timing can increase the difference between

Similarly, the receiving section 120 may have a second concave portion 128 in a portion of the receiving side fixing surface 126 and the second receiving side transducer 222 may be provided on the bottom surface of the second concave portion 128 . That is, the second receiving transducer 222 is formed closer to the contact surface 130 than the first receiving transducer 122 . Therefore, even if the ultrasonic waves are simultaneously transmitted from the metal plate 20 , the timing at which the ultrasonic waves reach the second receiving transducer 222 is higher than the timing at which the ultrasonic waves reach the first receiving transducer 122 . becomes faster, the difference between the first timing and the second timing can be increased. The detection timing of such ultrasonic signals will be described below.

<Concept of signal waveform>
FIG. 8 shows a conceptual diagram of the signal waveform of the ultrasonic signal acquired from the probe 30 by the signal acquisition unit 50 according to this embodiment. The horizontal axis of FIG. 8 indicates time, and the vertical axis indicates signal level. In FIG. 8, time _t0 indicates the timing at which the first transmitting transducer 112 and the second transmitting transducer 212 generate ultrasonic waves. In this case, for example, drive signals from the signal supply unit 40 are supplied to the first transmission transducer 112 and the second transmission transducer 212 at substantially the same timing.

FIG. 8 shows an example in which signals S, I, and B with peak signal levels are detected at time t ₁ , time t ₂ , and time t _{3 ,} respectively. A signal S represents a signal received by the second receiving transducer 222 after the ultrasonic wave transmitted from the second transmitting transducer 212 is reflected by the surface of the coating layer 23 of the metal plate 20 . Thus, the ultrasonic waves reflected by the surface of the coating layer 23 closest to the contact surface 130 of the probe 30 are detected the earliest.

A signal I indicates a signal received by the second receiving transducer 222 after the ultrasonic wave transmitted from the second transmitting transducer 212 is reflected by the first surface 21 of the metal plate 20 . A signal B indicates a signal received by the first receiving transducer 122 after the ultrasonic wave transmitted from the first transmitting transducer 112 is reflected by the second surface 22 of the metal plate 20 . Then, the time T between the time t ₂ (second timing) at which the signal I is detected and the time t ₃ (first timing) at which the signal B is detected is the time that the ultrasonic wave travels back and forth on the metal plate 20. Equivalent to. Therefore, the calculator 60 can calculate the thickness of the metal plate 20 based on the incident angle, velocity, time T, etc. of the ultrasonic waves, for example.

Note that the position where the second transmitting transducer 212 and/or the second receiving transducer 222 are provided is closer to the position where the first transmitting transducer 112 and the first receiving transducer 122 are arranged. When approaching the contact surface 130 side, an offset time proportional to the approaching distance is added to the time T. FIG. In this case, since the time intervals between the detection of the signals I and B are widened, the two signals are separated and the peak values can be easily determined. In this case, it goes without saying that the calculator 60 calculates the thickness of the metal plate 20 by subtracting the offset time.

As in the above example, the plate thickness measuring apparatus 10 can measure the thickness of the metal plate 20 by transmitting ultrasonic waves to the metal plate 20 substantially simultaneously from the first transmitting transducer 112 and the second transmitting transducer 212 . can be calculated. In this case, for example, the signal supply unit 40, the signal acquisition unit 50, and the calculation unit 60 combine the parts used in the conventional plate thickness measuring device with the probe 30 according to the present embodiment, It can be operated as the plate thickness measuring device 10 of the embodiment. That is, it is possible to measure the thickness of the metal plate 20 with the deteriorated coating layer 23 simply by exchanging the probe 30, thereby reducing costs and labor.

Alternatively, plate thickness measuring apparatus 10 may vary the timing at which first transmitting transducer 112 and second transmitting transducer 212 transmit ultrasonic waves to metal plate 20 . For example, the plate thickness measuring device 10 measures signal I and signal B independently. As a result, the detection error of the peak value of the signal level due to overlapping of the detection signals can be reduced, and the thickness of the thinner metal plate 20 can be accurately measured.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. be. For example, all or part of the device can be functionally or physically distributed and integrated in arbitrary units. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

10 Plate thickness measuring device 20 Metal plate 21 First surface 22 Second surface 23 Coating layer 30 Probe 40 Signal supply unit 50 Signal acquisition unit 60 Calculation unit 70 Display unit 110 Transmission unit 112 First transmission transducer 114 Transmission side Fixing portion 115 First opposing surface 116 Transmitting side fixing surface 118 First recess 120 Receiving portion 122 First receiving transducer 124 Receiving side fixing portion 125 Second opposing surface 126 Receiving side fixing surface 128 Second recess 130 Contact surface 140 1 Separating Part 150 Accommodating Part 160 Electrode Part 212 Second Transmitting Transducer 222 Second Receiving Transducer 230 First Region 240 Second Region 250 Second Separating Section

Claims (10)

A probe used in a plate thickness measuring device that measures the thickness of a metal plate,
a contact surface that contacts the first surface of the metal plate;
a transmitting unit having a first transmitting transducer that transmits ultrasonic waves toward the metal plate through the contact surface;
a first receiving transducer for receiving ultrasonic waves transmitted from the first transmitting transducer and reflected by a second surface of the metal plate opposite to the first surface via the contact surface; a receiver;
a first isolator that blocks propagation of ultrasonic waves from the transmitter to the receiver;
with
The transmitting unit further includes a second transmitting transducer that transmits ultrasonic waves toward the first surface of the metal plate,
The receiving unit further includes a second receiving transducer that receives ultrasonic waves transmitted from the second transmitting transducer and reflected by the first surface of the metal plate,
the contact surface is circular;
at least part of the transmitting section, the receiving section, and the first separating section integrally has a cylindrical shape extending in a direction orthogonal to the contact surface;
Inside the cylinder, a first region in which the first transmitting transducer and the first receiving transducer transmit and receive ultrasonic waves is a region where the second transmitting transducer and the second receiving transducer transmit and receive ultrasonic waves. Unlike the second area for transmitting and receiving, it is provided on the outer peripheral side than the second area,
A second isolator for blocking propagation of ultrasonic waves is provided between the first region and the second region,
The second isolation part has a shape of a part of a cone whose center axis is the center axis of the cylinder,
The center frequency of the frequency characteristics for receiving the ultrasonic waves of the first receiving transducer is lower than the center frequency of the frequency characteristics of the ultrasonic waves generated by the first transmitting transducer.
probe. The first isolation section has a surface orthogonal to the contact surface between the transmission section and the reception section.
The probe according to claim 1. The metal plate has a coating layer formed on at least part of the first surface,
The center frequency of the ultrasonic reception band of the first receiving transducer has an attenuation rate of 90% or less in the coating layer in the frequency band of the ultrasonic waves generated by the first transmitting transducer. is the frequency contained in the frequency band,
The probe according to claim 1 or 2. the transmission unit further includes a transmission-side fixing unit that fixes the first transmission-side transducer,
The first transmission transducer is provided on a transmission side fixing surface opposite to the contact surface of the transmission side fixing portion,
The transmission-side fixed surface has a curved surface with a curvature to gather the ultrasonic waves generated by the first transmission-side transducer in a region including a part of the second surface on the opposite side of the first surface of the metal plate. have
The probe according to any one of claims 1 to 3. the receiving unit further includes a receiving-side fixing unit that fixes the first receiving-side transducer,
The first receiving-side transducer is provided on a receiving-side fixing surface opposite to the contact surface of the receiving-side fixing portion,
The receiving-side fixed surface has a curved surface with a curvature that allows ultrasonic waves reflected and diffused from a portion of the second surface of the metal plate to reach the first receiving-side transducer,
The probe according to claim 4. 6. The probe according to claim 5, wherein said transmitting side fixed surface and said receiving side fixed surface are different curved surfaces of a common spherical surface centered on a predetermined common point. 7. The probe according to claim 5 , wherein the transmitting section has a first recess in a part of the transmitting side fixing surface, and the second transmitting vibrator is provided on a bottom surface of the first recess. Tentacles. 8. The receiving section according to any one of claims 5 to 7 , wherein the receiving section has a second recess in a portion of the receiving side fixing surface, and the second receiving transducer is provided on a bottom surface of the second recess. Probe as described in section. 9. The center frequency of the frequency characteristics of the ultrasonic waves emitted by the second transmitting transducer matches the center frequency of the ultrasonic reception band of the second receiving transducer. Probe as described in section . A plate thickness measuring device for measuring the thickness of a metal plate,
The probe according to any one of claims 1 to 9 ,
a signal supply unit that supplies a drive signal for generating ultrasonic waves to the transmission unit of the probe;
a signal acquisition unit that acquires an ultrasonic signal received by the receiving unit of the probe;
A plate thickness measuring device comprising: a calculation unit that calculates the thickness of the metal plate based on the ultrasonic signal.

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