JPH0823487B2 - Ultrasonic probe for plate thickness measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ultrasonic probe for plate thickness measurement capable of measuring the true plate thickness of a coated steel plate or the like from a coating film. (Hereinafter, abbreviated as “ultrasonic probe”).

[Prior Art] There are various types of ultrasonic probes for measuring the plate thickness of a steel plate or the like, and one shown in Fig. 4 is known as one of them.

The illustrated ultrasonic probe 1 is generally called a split type, and is provided with a cylindrical case 3 having at one end an opening end portion which is in close contact with the surface of the DUT 2 is formed. Three
An ultrasonic wave transmitting member 4 and a ultrasonic wave receiving member 5 made of a piezoelectric element or the like are arranged in parallel on the opposite side of the opening end. The transmitting member 4 and the receiving member 5 are arranged symmetrically with respect to each other at an appropriate angle θ in the direction of closing the transmitting / receiving surface, and when the transmitting member 4 emits an ultrasonic pulse, The sound wave pulse is reflected by the DUT 2,
The reflected wave is received by the receiving member 5. Further, in order to prevent the ultrasonic pulse from the transmitting member 4 from directly propagating to the receiving member 5, an acoustic partition plate 6 is attached between the transmitting member 4 and the receiving member 5, and the center of the case 3 is attached. It extends along a line to the open end. Furthermore, the transmitting / receiving member 4,
The case 3 between the opening 5 and the opening end is filled with a delay material 7, and in order to absorb the resonance of the transmitting / receiving members 4 and 5 to transmit / receive a short pulse, the transmitting member 4 and the receiving member. A damper 8 is attached to the back side of the member 5.

Next, a method of measuring the plate thickness using the ultrasonic probe 1 will be described.

First, in order to improve the propagation of ultrasonic waves, the DUT 2
A contact medium such as glycerin is applied to the surface of the ultrasonic probe 1, the end face of the ultrasonic probe 1 is brought into close contact with the DUT 2, and the ultrasonic pulse is transmitted from the transmitting member 4. Part of this ultrasonic pulse is reflected by the surface of the DUT 2, and this surface reflected wave is received by the receiving member 5. The other ultrasonic pulses travel through the DUT 2, are reflected by the bottom surface of the DUT 2, and the bottom surface reflected wave is also received by the receiving member 5.

Thus, theoretically, the time from the transmission of the ultrasonic pulse to the reception of the surface reflected wave and the time to the reception of the bottom reflected wave are obtained, and these times and the DUT 2 are measured.
The plate thickness of the DUT 2 is calculated from the propagation velocity of the ultrasonic wave at.

However, this ultrasonic probe 1 has the acoustic partition plate 6
Has a structure that extends to the opening end of the case 3 and contacts the DUT 2, the surface reflected wave received by the receiving member 5 is extremely small, and it is very difficult to detect this. . Therefore, in the actual thickness measurement, the propagation time of the ultrasonic wave from the transmitting member 4 to the opening end of the case 3 is obtained in advance, and twice the propagation time is treated as the surface reflected wave reception time. .

[Problems to be Solved by the Invention] In the conventional ultrasonic probe as described above, when the plate thickness is measured from the coating film when the surface of the object to be measured is coated, the measured value Was included up to the thickness of the coating film, and the true plate thickness could not be measured. In such a case, conventionally, there has been a problem that it takes time and labor to remove the coating film in advance by sandblasting, a grinder or the like before the measurement.

Also, depending on the time from receiving the boundary surface reflected wave reflected by the boundary surface between the coating film and the DUT to receiving the bottom surface reflected wave, the plate thickness of the DUT remains with the coating film. Although the method of measurement has been considered from the past, in the above ultrasonic probe, the reception level of the boundary surface reflected wave is low due to the presence of the acoustic partition plate, and the received signal of the boundary surface reflected wave can be reliably extracted. Therefore, it was difficult to put it into practical use.

Therefore, an object of the present invention is to eliminate such problems.

[Means for Solving the Problems] In order to achieve the above object, the ultrasonic probe for plate thickness measurement according to the present invention includes a transmitting member for emitting an ultrasonic pulse and the transmitting member. A receiving member arranged in parallel with the transmitting member so as to receive a reflected wave of the ultrasonic pulse from the object to be measured, and the transmitting member so that the ultrasonic pulse does not directly propagate from the transmitting member to the receiving member, and An acoustic partition plate provided between the receiving members, and is disposed adjacent to the transmitting surface of the transmitting member and the receiving surface of the receiving member, and between the transmitting member and the receiving member and the DUT during measurement. And a case for holding the transmitting member, the receiving member, the acoustic partition plate and the delay member, and the ultrasonic pulse emitted from the transmitting member is reflected by the surface of the object to be measured. Receiving the wave It is characterized in that a gap is formed between the free end of the acoustic partition plate and the end face of the delay member so that the member can receive the signal.

[Operation] In the ultrasonic probe according to the present invention described above, a gap is formed between the acoustic partition plate and the object to be measured, and in addition to the bottom surface reflected wave, the surface reflected wave and the object to be measured are coated. In that case, the reflected wave at the boundary surface between the coating film and the object to be measured can be received at a high level, and the true plate thickness can be obtained from these received signals.

Other objects, features and advantages of the present invention will be apparent from the following detailed description in conjunction with the accompanying drawings.

[Embodiment] FIG. 1 of the drawings shows an embodiment of an ultrasonic probe according to the present invention, in which the same or corresponding portions as those of the conventional configuration are designated by the same reference numerals.

As shown in the drawing, the ultrasonic probe 10 of this embodiment is of a split type, and similarly to the conventional configuration, a cylindrical case 3 having an open end formed at one end and a cylindrical case 3 arranged inside and at the other end side by side. The ultrasonic wave transmitting member 4 and the receiving member 5 and the acoustic partition plate 11 installed between the transmitting member 4 and the receiving member 5 are mainly configured. In addition, the delay member 7 is disposed inside the case 3 and the transmission member 4
Is arranged adjacent to the transmitting surface of and the receiving surface of the receiving member 5,
The end surface is aligned with the opening surface of the case 3. Furthermore,
The damper 8 is attached to the back side of the transmitting / receiving members 4, 5.

According to the present invention, the acoustic partition plate 11 is shorter than that of the conventional configuration shown in FIG. A gap (13) is formed between it and the coating film (14). The size of the gap 13 is appropriately set so that the reflected wave at the surface of the coating film 14 and the boundary surface between the coating film 14 and the object 12 to be measured is transmitted to the receiving member 5 at a high level.

Next, a case will be described in which the plate thickness of the coated object to be measured is automatically measured using the ultrasonic probe according to the present invention having the above-described configuration.

This ultrasonic probe 10 is attached by bringing the end face of the delay member 7 into close contact with the surface of the coating film 14 coated with the contact medium, as in the conventional case. Further, an appropriate plate thickness measuring device 20 for automatic plate thickness measurement is connected to the ultrasonic probe 10. This thickness gauge
In FIG. 20, reference numeral 21 is an ultrasonic pulse generator, which is connected to the transmitting member 4 of the ultrasonic probe 10 and can transmit ultrasonic pulses from the transmitting member 4 at a constant cycle. Part of the ultrasonic pulse emitted from the transmitting member 4 is
The receiving member 5 is reflected by the surface of the coating film 14 and passes through the gap 13.
Received by. The receiving member 5 is connected to the signal selector 22 of the plate thickness measuring instrument 20, and the received signal from the receiving member 5 is passed through the signal selector 22, the surface reflected wave amplifier 23 and the waveform shaping circuit 24 to obtain the signal a (second Comparison circuit as figure (a))
Entered in 25. Further, a part of the ultrasonic pulse that has passed through the coating film 14 on the object to be measured 12 is reflected at the boundary surface between the coating film 14 and the object to be measured 12. The signal from the receiving member 5 that has received this boundary surface reflected wave is sent to the boundary surface reflected wave amplifier 26 and the waveform shaping circuit 27 by the signal selector 22, and is then output as the signal b (FIG. 2 (b)) to the comparison circuit. Entered in 25. The code
28 is an automatic gain control, which functions to loop the signal waveform of the boundary surface reflected wave until it is amplified to a sufficient magnitude. In the comparison circuit 25, the signal that comes in with a time delay is output (FIG. 2 (c)) and input to the flip-flop circuit 29. The bottom surface reflected wave from the bottom surface of the DUT 12 is also received by the receiving member 5, the signal passes from the signal selector 22 to the bottom surface reflected wave amplifier 30, and is sufficiently amplified by the auto gain control 31 and then the waveform shaping circuit. 32
After that, it enters the flip-flop circuit 29 as a signal d (FIG. 2 (d)). Signal e from flip-flop circuit 29
The waveform of is as shown in FIG. Further, the watch pulse generator 33 generates a watch pulse f (FIG. 2 (f)) having a constant cycle, and the output signal e of the flip-flop circuit 29 and the output signal f from the watch pulse generator 33 are pulsed. It is input to the gate circuit 34. The pulse gate circuit 34 outputs the common part of the input signal, and as can be understood from FIG. 2 (g), the difference between the reception time of the boundary surface reflected wave and the bottom surface reflected wave, that is, the DUT. A signal g representing a value corresponding to twice the propagation time of the ultrasonic pulse at 12 is output. Further, this signal g is sent to the counting circuit 35 and digitized, and is processed by the microcomputer 36 together with data such as the propagation velocity of ultrasonic waves in the measured object 12 and the measured value is displayed on the measured value display section 37. Twelve true thickness measurements are displayed.

As can be understood from the schematic cross-sectional view of the ultrasonic probe 10 in FIG. 1, the surface reflected wave is reflected by the receiving member 5 and again,
The receiving member 5 may reflect this second surface reflected wave on the surface of the coating film 14. Now, the thickness of the delay material 7 is h, the propagation velocity of the ultrasonic wave in the delay material 7 is C ₁ , the thickness of the coating film 14 is tp,
If the plate thickness of the object to be measured 12 is t and the propagation speeds of the ultrasonic waves in the object to be measured 12 and the coating film 14 are C ₂ and Cp, the second surface reflected wave is received after the ultrasonic pulse is transmitted. It takes 4 hours
/ C ₁ and the time until the bottom reflected wave is received is 2h / C ₁
+ 2tp / Cp + 2t / C ₂ , but depending on the size of h, t, tp, C ₁ , C ₂ , and Cp, as shown in FIG. Received pulse of surface reflected wave S ₂
May appear. In such a case, since the plate thickness measuring instrument 20 described above determines that the second surface reflected wave is the bottom surface reflected wave, an incorrect measurement value is displayed. In order to prevent this, it is necessary to receive the second surface reflected wave after receiving the bottom surface reflected wave. That is, in FIG. 3, if the time from the transmission pulse T to the reception pulse S ₂ of the second surface reflected wave becomes longer than the time from the transmission pulse T of the ultrasonic wave to the reception pulse B of the bottom surface reflected wave. Since it is good, the thickness h of the delay material 7 should satisfy the relationship of h> C ₁ (tp / Cp + t / C ₂ ). In FIG. 3, S ₁ is the received pulse of the first surface reflected wave, and ▲ S ^′ ₁ ▼ and ▲ S ^′ ₂ ▼ are the first waves of the boundary surface reflected wave between the coating film 14 and the DUT 12. And the second wave.

Further, even if the measured object is not coated, for example, in the plate thickness measuring instrument 20 of FIG. 1, the input path to the boundary surface reflected wave amplifier 26 is blocked and the surface reflected wave amplifier 23 is used. The output of the waveform shaping circuit 24 is fed to the flip-flop circuit 29.
If the configuration is changed so that it is directly connected to, the plate thickness can be automatically measured.

In the ultrasonic probe 10 of the above-described embodiment, the opening surface of the case 3 and the end surface of the delay member 7 are coincident with each other. However, as shown in FIG. Sound wave probe
The delay member 7 may be projected from the end of the case 3 of 10 '. Further, as shown in FIG. 6, a delay member 7'of the same kind is formed on the end face of the delay member 7 of the conventional ultrasonic probe 1 '.
Ultrasonic probe composed by bonding and integrating
The 10 ″ also has the same effect as the two ultrasonic probes 10 and 10 ′.

[Effects of the Invention] As described above, according to the present invention, it is possible to receive surface reflected waves at a detectable level, and, in the case of an object to be measured that has been coated, Since it is possible to receive reflected waves at the interface with the DUT at a high level,
It is possible to suppress the occurrence of an error in the amplification process of the received signal, and to measure the true plate thickness of the object to be measured based on the reception time of each reflected wave. Therefore, it is not necessary to obtain the propagation time of the ultrasonic wave from the transmitting member to the opening end in advance, and the work such as peeling off the coating film on the object to be measured becomes unnecessary, and the measurement of the plate thickness can be simplified. It is possible to achieve such effects.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an ultrasonic probe according to the present invention and a plate thickness measuring instrument connected thereto, and FIG. 2 is a waveform explanatory view showing waveforms of respective output signals in FIG. FIG. 3 is an explanatory diagram of transmission / reception pulses from the transmission of an ultrasonic pulse to the reception of the first and second surface reflected waves and the bottom surface reflected wave,
FIG. 4 is a schematic explanatory view showing a conventional ultrasonic probe, and FIGS. 5 and 6 are schematic explanatory views showing another embodiment of the present invention. In the figure, 1,10,10 ′, 10 ″ …… Ultrasonic probe 2,12 …… Measurement object, 3 …… Case 4 …… Transmission member, 5 …… Reception member 6,11 …… Acoustic partition Plate, 13 ... Gap 14 ... Paint film, 20 ... Plate thickness measuring instrument

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Yokoyama 3-50, Mizuho-cho, Sugawara, Kakamigahara-shi, Gifu 2 (72) Inventor Satoshi Oda 1261-12-408 Wada, Tama-shi, Tokyo (72) Inventor Miura Shuichi 1-48-4 Higashikasai, Edogawa-ku, Tokyo (72) Inventor Osamu Takahashi 4-15-23 Fujimi, Urayasu-shi, Chiba (56) Reference JP-A-61-228307 (JP, A) 123660 (JP, U) Actually opened Sho 53-93155 (JP, U) Japanese Patent Sho 46-33312 (JP, B1)

Claims (1)

[Claims] 1. A transmitting member for emitting an ultrasonic wave pulse, and a receiving member arranged in parallel with the transmitting member so as to receive a reflected wave of an ultrasonic pulse emitted from the transmitting member by a measured object. An acoustic partition plate provided between the transmitting member and the receiving member so that an ultrasonic pulse does not directly propagate from the transmitting member to the receiving member; and a transmitting surface of the transmitting member and a receiving surface of the receiving member. A delay member interposed between the transmitting member and the receiving member and the object to be measured when arranged, and a case that holds the transmitting member, the receiving member, the acoustic partition plate and the delay member, The acoustic partition plate is slightly protruded downward from the inside of the top of the case with a length required to isolate and support the transmitting member and the receiving member. The free end of the protruding acoustic partition plate is separated from the end face of the delay member with a sufficient distance so that the receiving member can reliably receive the reflected wave of the ultrasonic pulse generated by the surface of the measured object. An ultrasonic probe for plate thickness measurement, characterized in that a sufficiently large gap is formed between the free end and the end face so that the plate thickness of the object to be measured can be measured from above the coating film.