JPS61169758A - Continuous non-destructive ultrasonic inspection device for sheet joint - Google Patents

Abstract

PURPOSE:To enable continuous high-speed inspection of adhesivity of a joint, by arranging a pair of ultrasonic probes adapted to move in contact with the surface of a sheet at a joint keeping a fixed space, an ultrasonic wave transmitting means, a receiving means and a notifying means. CONSTITUTION:A ultrasonic wave is made incident into a sheet repeatedly at a fixed cycle from a probe 1a. The reflected wave of the incident ultrasonic wave is caught with one probe 1b, the detection signal is outputted into a receiving amplification circuit 11 and further, amplified vertically with a video amplifier 12 to be a vertical way control signal for an oscilloscope 14. A repetition signal is amplified from a transmitting circuit 10 through a time-base amplifier 13 to be outputted as horizontal way control signal for the oscilloscope 14. The received signal amplified from a video amplifier 12 is outputted into a selector circuit 16 via a time gate through a gate circuit 15 and an alarm buzzer 17 is driven by a signal from the selector circuit 16. A continuous rolling inspection is done over surface of a sheet 4 at the joint of rubber or plastic sheets 4 and 5.

Description

[Detailed Description of the Invention] Drama l! BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for non-destructively inspecting the adhesive state of bonded joints of rubber or plastic sheets using ultrasonic waves.

[Natsuko l For civil engineering (e.g. reservoirs, industrial waste, golf courses, etc.)
In some cases, rubber sheets or plastic sheets are spread over the entire surface of the inner surface to prevent water leakage in buildings (e.g., water storage tanks on rooftops, rooftop roofings, garden parks, etc.).

At this time, sheets of a predetermined size are laid down in a form that is pasted together, and the joint is made by overlapping several sheet ends and bonding them together using an adhesive or heat fusion.

If even a part of the bonded joint is not completely bonded, the water stop function will not be achieved, so it is necessary to inspect all bonded parts to see if the bond is complete for quality assurance purposes.

In the past, it was only possible to judge by visual inspection, or to rely on human intuition and experience, such as inserting a screwdriver etc. between the sheets of the joint and judging the state of adhesion based on the degree of penetration, but in recent years ultrasonic waves have been used to determine the adhesion state. Testing methods have also been implemented.

In this ultrasonic inspection method, an ultrasonic probe for both transmitting and receiving functions is fixedly contacted on the sheet surface of the sheet joint, and ultrasonic waves are applied to detect the intensity of reflected waves from the contact interface or the bottom surface of F-E. The adhesion condition was estimated by

However, this conventional ultrasonic testing method can only inspect the adhesion state in a localized area by placing the probe in fixed contact with a part of the surface of the bonded sheet; In order to inspect the adhesion state, it was necessary to appropriately shift the position of the probe and perform the inspection several times.

As a result, the testing speed is extremely slow and the testing accuracy varies depending on the person conducting the test, resulting in the drawback that accurate testing can only be performed by experienced and qualified personnel.

The present invention has been made in view of the above, and an object thereof is to provide an ultrasonic continuous inspection device that can continuously inspect the adhesion state of a joint at high speed while moving a probe. It is in.

That's it. The configuration of the present invention will be explained based on FIG.

When inspecting the adhesion state of the bonded joint of sheets AI and A2 of rubber or plastic, etc., B1 and B2 are a pair of ultrasonic probes that are moved in contact with the surface of sheet A1 at the sheet joint part. Probe Bl, 82
The interval is kept constant.

C is a transmitting means for transmitting ultrasonic waves using one ultrasound probe B1 as a transmitter, and D is a transmission means for transmitting ultrasound using the other ultrasound probe B2.
This is a receiving means that detects reflected ultrasonic waves by using the receiver as a receiver.

E is a notification means for notifying the state or abnormality of the reflected wave.

According to the present invention, a pair of ultrasonic probes 81° B2 are moved while being in contact with the surface of the sheet ^1 at the sheet joining part based on the above configuration, and ultrasonic waves are emitted from one of the ultrasonic probes B1. is incident on the joint, and the reflected waves from the contact interface of both sheets or the bottom surface of the deeper sheet A2 are transmitted to the other ultrasonic probe B2.
By notifying the operator of the state or abnormality of the reflected wave using the notification means E, the bonding state can be continuously inspected over the entire surface of the joint.

1) 1) The embodiments according to the present invention illustrated in FIG. 2 and subsequent figures will be described.

As shown in FIG. 2, the ultrasonic probe used in this example has a roller 2 made of rubber or plastic pivoted at the tip of the ultrasonic probe 1, and a piezoelectric material inside the roller 2. A transmitting (receiving) transmitter 3 is built-in.

The transmitter (receiver) element 3 generates ultrasonic waves by receiving pulse signals, and outputs electrical pulse signals by receiving ultrasonic waves.

Therefore, it is possible to make the ultrasonic wave enter the object to be inspected while rolling the O-ra 2 at the tip of the ultrasonic probe 1 into contact with the surface of the object to be inspected, and to capture the reflected waves.

These ultrasonic probes 1 are placed in parallel between two rollers in the narrow direction with a spacing of 2 to 3 feet apart and fixed together, and a rubber or plastic sheet is attached as shown in Fig. 3. 4.5, the surface of the sheet 4 is rolled over and continuously inspected.

One of the pair of probes 1a is used as an ultrasonic transmitter, and the other probe 1b is used as a reflected wave receiver.

As shown in FIG. 4, the ultrasonic waves incident from the probe 1a are reflected at the joint interface between the sheets 4 and 5 or the bottom surface of the sheet 5, and the reflected waves are detected by the probe 1b.

At that time, if the adhesion of the joint is perfect, the ultrasonic transmittance at the joint interface will be improved, so the reflected wave 1 from the interface will be weakened, and conversely, the reflected wave from the bottom of the sheet 5 will be weaker. ■2 becomes stronger. In particular, when sheets of the same material are heat-sealed, the reflected wave (1) from the bonding interface disappears when the bonding is complete.

Furthermore, if the adhesion at the joint is incomplete, an air layer will be included in the gap between the sheets 4 and 5, which will significantly reduce the ultrasonic transmittance and intensify the reflected waves 1 from the joint interface. Reflected waves from the bottom of 5! 2 weakens.

Therefore, in order to know the adhesion state of the bonded portion, it is sufficient to monitor either the reflected wave (1) from the bonding interface or the reflected wave (2) from the bottom surface of the sheet 5 and observe changes in the intensity.

It is also possible to determine the adhesion state by detecting the intensities of both reflected waves 11 and 12 and calculating the ratio by 5.

In this embodiment, changes in the intensity of the reflected wave (2) from the bottom surface of the sheet 5 are monitored.

FIG. 5 shows the monitoring mechanism in block diagram form, and will be explained based on this figure.

A transmitting circuit 10 is connected to the transmitting probe 1a that is in contact with the surface of the sheet 4, and a pulse for generating ultrasonic waves is output from the transmitting circuit 10 as a repeated signal of 5KH2. Ultrasonic waves (05~IMH
z) is repeatedly input into the sheet at a constant period.

The reflected wave of the incident ultrasonic wave is captured by the other probe 1b, and its detection signal is output to the reception amplifier circuit 11, and is further vertically amplified by the video amplifier 12 and used as a vertical control signal for the oscilloscope 14. Ru.

The repeated signal from the oscillator circuit 10 is amplified via a time-base amplifier 13 and outputted as a signal Wa in the horizontal direction of the oscilloscope 14.

Therefore, the intensity of the received reflected waves of a constant period can be viewed on a cathode ray tube as an appropriate pulse signal wave.

Further, the amplified reception signal from the video amplifier 12 is passed through a gate circuit 15 and a time gate to the selector circuit 1.
6, and the alarm buzzer 11 is driven by the signal from the selector circuit 16.

Depending on the thickness of the sheet to be inspected here, the reflected wave 1
1 and ■2 may appear very close to each other, and the separation between the two may be difficult. Therefore, the wavelength λ of the ultrasonic wave used should be twice or more than the thickness 1 of the sheet to reduce the wavelength of the waves. The reflected wave (1) from the joint interface is weakened by interference, so that only the reflected wave (2) from the bottom surface of the sheet 5 can be easily separated and detected.

Let us now examine the state of adhesion when two rubber sheets each having a thickness of 1.5 mm are bonded together by heat fusion as shown in FIG.

The wavelength of the ultrasonic waves to be used is 3.7 #I because it is more than twice the thickness of the sheet, which is 1.5 m. Since the sound velocity inside the rubber sheet is approximately 1850 yyt/sec, the frequency exceeds 0.5 MHz. We will use sound waves.

FIGS. 6 and 7 schematically show reflected waves that appear on the cathode ray tube when testing is performed with such settings.

Figure 6 shows the incident wave IO when the sheet joints are well bonded.
A group of strong reflected waves I2 from the bottom surface of the sheet 5 are observed after a short interval (about 3 μs).

In addition, Figure 7 shows a case where the adhesion of the sheet joint is insufficient, and a group of reflected waves appear immediately after the incident wave TO, but this is the reflected wave r1 from the bonded interface with poor adhesion. If the condition is good, the reflected wave I2 from the bottom surface of the sheet 5 should not be observed during time period A, but the reflected wave I2 does not appear.

Therefore, by monitoring the state of the reflected waves appearing on the cathode ray tube, it is possible to inspect the adhesion state of the sheet joint.

In addition, in this embodiment, the warning buzzer 17 is used to detect adhesion defects.
It is possible to detect the minute.

That is, the amplified reflected wave signal from the video amplifier 12 is temporally filtered by the gate circuit 15, and the seventh
Time period A shown in the figure (reflected wave I2 from the bottom of the sheet 5
The selector circuit 16 identifies whether or not the intensity of the reflected waves in the same time period is below a certain set value, and if it exceeds the set value. If there is no strong reflected wave (2), it is determined that the sheet joint is defective in adhesion, and a signal can be sent to the alarm buzzer 17 to drive the alarm buzzer 11 to issue a warning.

In this embodiment, it takes 10 to 15 seconds to inspect the length of the sheet joint 1m.

An example of inspecting this same object using a conventional ultrasonic inspection method is shown below.

Wet the sheet surface at the sheet joint with coupling liquid,
On top of that, a vertical ultrasonic probe for both transmitting and receiving was installed and monitored with an oscilloscope.

The inspection was carried out at 20 points every 5a for each TrL of the sheet joint.

This conventional method cannot be inspected continuously and must be inspected spot by point, so a total of 20
It took 5 minutes to inspect the spot.

In the embodiment according to the present invention, even if it takes a long time, it is only 15 seconds, which is a large difference, and especially when the inspection area is large, the time difference becomes considerable.

As described above, according to this embodiment, the labor of the operator is significantly reduced.

In addition, in this example, the inspection is carried out continuously, so the
It is also more accurate than conventional spot inspections performed at J intervals.

In addition, continuous testing was carried out using the roll type probe used in this example for both transmitting and receiving, but the results showed that regardless of the adhesive state of the sheet, strong noise appeared following the incident wave, making testing impossible. In the end, it was not possible to perform continuous testing using the probe alone for both transmitting and receiving purposes.

Next, we will explain another example in which a coupling liquid is used to improve the adhesion between the probe and the sheet surface, and a frequency detector is used to remove erroneous signals caused by using the coupling liquid. do.

As shown in Fig. 8, by applying coupling liquid 20 on the sheet surface and placing the ultrasonic probe 1 on top of it, the adhesiveness between the ultrasonic probe 1 and the sheet surface is improved and excess noise is eliminated. However, in reality, the ultrasonic waves are transmitted through the liquid pool between the two probes 1a and Ib and are detected as interference signals.

Therefore, as shown in FIG. 9, a frequency detector 21 is inserted between the receiving amplifier circuit 11 and the video amplifier 12, and the amplified signal of the signal detected by the probe 1b is passed through the frequency detector 21 to generate the interference signal. This is an attempt to remove the .

The frequency detector 21 has a bandwidth of 2 to 5 Hz and changes the center frequency from 200 KHz to 750 KHz while looking at the cathode ray tube.
KHz and adjust it so that the interference signal due to the liquid pool disappears.

FIGS. 10 and 11 schematically show reflected waves appearing on the cathode ray tube when testing is performed with such settings.

FIG. 10 shows the case where the adhesion state of the sheet joints is good, and FIG. 11 shows the case where it is insufficient, and the difference is more clearly seen than in the previous example.

Note that when the frequency detector 21 is used, it is useful for making the detection signal visible even when there is no particularly strong interfering signal and improving the sensitivity of the detection signal.

The present invention allows continuous inspection of the adhesion state of sheet joints, greatly reduces the time required for inspection, and reduces the labor of the operator.

In addition, compared to the conventional method in which sheet joints are inspected spot-wise, the inspection can be performed continuously, resulting in higher accuracy, and even inexperienced personnel can perform the inspection work easily.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a diagram showing a roller-type ultrasonic probe, Fig. 3 is a diagram showing an inspection method using the ultrasonic probe in this embodiment, and Fig. 4 is a diagram showing the inspection method using the ultrasonic probe in this embodiment. FIG. 5 is a schematic block diagram of the device of this embodiment. FIGS. 6 and 7 are diagrams showing the reflected waves of this embodiment. FIG. 8 is a diagram showing the transmission path of ultrasonic waves. A diagram showing the transmission path of ultrasonic waves when a coupling liquid is applied, FIG. 9 is a schematic block diagram of the device of another embodiment, and FIGS. 10 and 11 show the state of reflected waves in the same embodiment. It is a diagram. 1...Ultrasonic probe, 2...Roller, 3...Emission (
Receiving) signal element, 4, 5... sheet, 10... transmitting circuit, 11... receiving amplifier circuit, 12...
...Video amplifier, 13...Time base amplifier, 14...
・Oscilloscope, 15... Gate circuit, 16...
Selector circuit, 17...Alarm buzzer, 20...Coupling liquid, 21...-Frequency detector.

Claims (1)

[Claims] A pair of ultrasonic probes is moved in contact with the surface of the sheet where sheets of rubber or plastic are bonded together at a fixed interval, and one of the ultrasonic probes is used as a transmitter to emit ultrasonic waves. It is equipped with a transmitting means, a receiving means for detecting ultrasonic reflected waves using the other ultrasonic probe as a receiver, and a notifying means for notifying the state or abnormality of the reflected waves, and continuously monitors the adhesion state of the sheet joint. An ultrasonic continuous non-destructive testing device for sheet joints, characterized in that it is capable of non-destructive testing of sheet joints.