JPH04283659A - Noncontact method and device for detecting abnormal adhesion of metal plate without any contact - Google Patents

Abstract

PURPOSE:To enable an abnormal adhesion of a metal plate with a compact and portable device by exciting the metal plate by the use of electromagnetic force, detecting a supersonic wave which is generated by vibration of the metal plate, and detecting abnormal adhesion of an adhesive which is included between the metal plate and other member surface without any contact. CONSTITUTION:A hollow electromagnetic coil 7 and a magnet 12, as needed, are provided on a surface of a metal plate 3, AC current is allowed to flow to this electromagnetic coil 7 intermittently, and eddy current is generated on a surface of the metal plate 3 by a magnetic field which is generated by the AC current. A vibration force is generated at the metal plate 3 due to interaction between a magnetic field due to the magnet 12 which is placed along with the eddy current and a magnetic field which is generated by superposing DC current to the electromagnetic coil 7. A sound wave which is generated by vibration which is propagated through the hollow electromagnetic coil 7 is absorbed by a sound resonator concentrating device 9 which is installed at the rear part of a coil and then vibration status of the metal plate 3 is detected, thus enabling the adhesion status to be discriminated.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a non-contact detection method and device for abnormal adhesion of metal plates, and more specifically, the present invention relates to a non-contact detection method and device for abnormal adhesion of metal plates, and more particularly, the invention relates to the adhesion of metal plates that are bonded to other parts with an adhesive interposed between them. The present invention relates to a method and device for detecting an abnormality without contact.

0002

[Prior Art] Conventionally, in order to detect the state of adhesion between metal plates and other members, a method has been used in which ultrasonic waves are applied to the object to be inspected, and the presence or absence of adhesion abnormalities is detected based on the reflection characteristics of the ultrasonic waves. However, with this method, it is not possible to make the ultrasonic sensor (oscillator and receiver) non-contact with the metal plate, and if the ultrasonic sensor cannot be applied directly to the object to be inspected, the sensor A method has been adopted in which a liquid is interposed between the metal plate and the metal plate.

However, when the object to be inspected has a complicated shape, is large, or moves at high speed, the above method is often not suitable for the inspection.

[0004] Here, it can be easily predicted that if an alternating magnetic field is applied to a ferromagnetic object to be inspected, the magnetic force and magnetostriction effect will cause the object to vibrate. However, in order to realistically give strong vibrations, a fairly strong magnetic field is required, which requires a strong electromagnet. However, an electromagnet with an iron core has a large impedance.
At high frequencies (20 kHz or higher), the device becomes large and requires a small number of turns to flow a large current, making it impractical and naturally unsuitable for portable use.

[0005] Furthermore, as a method of imparting vibrations to unmagnetized metals in general, electromagnetic ultrasound is a technique that uses the interaction between eddy currents and magnetic fields (Lorentz force) to generate relatively small but strong vibrations inside metals. However, it has never been used to detect such adhesion abnormalities.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned situation, the present invention aims to solve the problem by exciting a metal plate by electromagnetic force and detecting ultrasonic waves generated by the vibration of the metal plate. A non-contact detection method and device for abnormal adhesion of a metal plate, which is small and suitable for portable use, and which enables non-contact detection of abnormal adhesion of an adhesive interposed between the plate and another member surface. It is in the point of providing.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a hollow metal plate arranged on the surface of a ferromagnetic metal plate that is bonded to another member surface with an adhesive interposed therebetween. An alternating current is intermittently passed through the electromagnetic coil, and a vibration force is generated in the metal plate by the magnetic field generated by the alternating current and the resulting magnetostrictive effect on the metal plate, and the vibration propagates through the hollow electromagnetic coil. We have established a non-contact detection method for adhesion abnormalities in metal plates, which collects the generated sound waves with a sound collector installed behind the coil, detects the vibration status of the metal plates, and determines the adhesion status.

[0008] For general metal plates, including those that are not magnetized, a hollow electromagnetic coil and, if necessary, a magnet are installed, and an alternating current is intermittently passed through the electromagnetic coil, so that the magnetic field generated by the alternating current A metal plate in which an eddy current is generated on the surface of the metal plate, and a vibration force is generated in the metal plate by interaction with the eddy current and a magnetic field generated by a magnet placed side by side or with a magnetic field generated by superimposing a direct current on the electromagnetic coil. A non-contact detection method for adhesion abnormalities was established.

[0009] An excitation means is arranged close to the surface of the metal plate bonded to another member surface with an adhesive interposed therebetween to electromagnetically vibrate the metal plate in a non-contact manner; Adhesion of metal plates consisting of a sound collection means that collects sound waves generated from a metal plate subjected to vibration and converts them into electrical signals, and an output circuit that adjusts and outputs electrical signals based on the sound waves of the sound collection means. A non-contact detection device for abnormalities was constructed.

[0010] More specifically, an electromagnetic coil is wound around a hollow winding frame made of a non-metallic material, and a resonant ultrasonic microphone as a sound collector is installed inside the hollow frame integrally formed at the rear of the hollow frame. a probe that relatively scans the plate surface in a non-contact manner; a frequency-variable excitation power source that intermittently supplies the electromagnetic coil with an excitation current that is an alternating current or a superimposed alternating current and a direct current; and the resonant type It consists of an output circuit that removes the noise signal caused by the induction of the excitation current from the output electrical signal of the ultrasonic microphone and outputs only the true sound signal due to the ultrasonic waves generated from the excited metal plate, resonating the frequency of the excitation power source. A non-contact detection device for abnormal adhesion of metal plates is made by detecting the adhesion quality of metal plates that are adhered to each other with an adhesive interposed between the resonant frequency of a type ultrasonic microphone and other parts. Configured.

In this case, it is preferable to arrange a permanent magnet around the outer periphery of the electromagnetic coil of the probe in order to reduce the size and weight.

Furthermore, the output circuit is equipped with an alarm output that sounds when a sound wave signal of a certain voltage or higher is generated, so that detection can be performed immediately without taking one's eyes off the probe, and a control signal output is also attached to enable automatic bonding. It is now possible to control the line or change the bonding conditions.

[0013]

[Operation] The non-contact detection method and device for adhesion abnormality in metal plates of the present invention having the above-mentioned contents vibrates the metal plate by electromagnetic force, collects the ultrasonic waves generated by the vibrations, and Since the vibration state of the metal plate is detected and the adhesion state is determined based on this, in principle it can be performed without contact.

In order to give vibration to the ferromagnetic metal plate, an alternating current is intermittently passed through the electromagnetic coil wound around the non-metallic hollow winding frame of the probe, and the magnetic field generated by the alternating current and its In order to excite the metal plate by the magnetostrictive effect of the electromagnetic coil and to give vibration to general metal plates, including those that are not magnetized, a magnet is attached to the electromagnetic coil, and an alternating current is intermittently passed through the electromagnetic coil. Excitation is caused by the interaction (Lorentz force) between the eddy current generated on the surface of the metal plate by the magnetic field generated by the alternating current and the magnetic field generated by the magnet. Of course, even in the latter case, it is possible to apply even larger vibrations to the ferromagnetic metal plate. Here, the magnet may be a permanent magnet or an electromagnet generated by superimposing a direct current on an alternating current flowing through an electromagnetic coil. In this case, the frequency of the metal plate is made to substantially match the resonant frequency of the resonant ultrasonic microphone. When a metal plate is vibrated in this way, the amplitude of the vibration is small in the bonded area, while the amplitude of the vibration is large in the area where the adhesive is not present or has peeled off, and as a result, the amplitude of the vibration is large in the area with poor adhesion. Since a signal voltage with an amplitude is received, the quality of the adhesion is determined by detecting the signal. At this time, the electrical signal output from the resonant ultrasonic microphone contains a noise signal caused by the induction of the excitation current of the excitation power supply.
The output circuit removes this signal and outputs only the sound wave signal.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be further explained in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a simplified explanatory diagram showing the arrangement of a probe 1 and an object to be inspected 2 according to the present invention. The present invention detects an abnormality in the bonded part of an inspected object 2 in which two members are bonded together, and the inspected object 2 to which the present invention is applicable has a metal plate 3 at least on the surface side. , the metal plate 3 is bonded to the surface of another member 4 with an adhesive 5 interposed therebetween.

The probe 1 has an electromagnetic coil 7 wound around a hollow frame 6 made of a non-metallic material such as synthetic resin such as Bakelite or polyacetate, and an ultrasonic sound collector 9 inside the hollow frame 8 behind the hollow frame 6. It has been decorated. The hollow winding frame 6 and the hollow frame 8 are integrally formed, and the center hole 10 of the hollow winding frame 6
A cavity 11 in the hollow frame 8 to which the sound collector 9 is mounted communicates with each other so that the ultrasonic waves generated by the metal plate 3 can propagate. The dimensions of this probe 1 are appropriately set depending on the size of the object to be inspected 2 and the detection accuracy, but in this example, the diameter of the hollow winding frame 6 is 6 mm, the length is 8 mm, and the diameter of the center hole 10 is 4 mm. , the hollow frame 8 has a diameter of 20 mm,
The length is 20 mm and the diameter of the cavity 11 is 10 mm. Moreover, the electromagnetic coil 7 has a wire diameter of 0.
3 mm, and the number of turns is 40. A resonant ultrasonic microphone (ceramic sensor) as a sound collector 9 is placed 4 mm behind the electromagnetic coil 7. This resonant ultrasonic microphone had resonance characteristics in the ultrasonic range of 20 kHz or higher. The vibration of the metal plate 3 will be stronger if the tip of the electromagnetic coil 7 is as close as possible to the object 2 to be inspected (without contacting it), but if the distance between the tip and the metal plate 3 is about 1 mm, the vibration will be strong enough. vibration can be obtained. On the other hand, the sound collector 9 is
It can be detected with sufficient strength even from a distance of 10 to 15 mm. A sound collector 9 installed in the center hole 10 of the hollow winding frame 6 and the cavity 11 of the hollow frame 8 communicating with the center hole 10 is a sound collecting means.

Furthermore, in order to further strengthen the vibration of the ferromagnetic metal plate 3, a general metal plate 3 that is not magnetized is used.
An electromagnetic coil 7 and a magnet 12 are also provided in order to apply vibrations. The outer periphery of the electromagnetic coil 7 is suitable for its position, and it is desirable that it be integrated with the probe 1. In this case, even if a permanent magnet is placed around the outer circumference of the electromagnetic coil 7,
It is also possible to generate a constant magnetic field by superimposing a direct current on an alternating current flowing through the electromagnetic coil 7 to excite the metal plate 3. Furthermore, if the object to be inspected 2 is plate-shaped, it may be arranged on the opposite side of the electromagnetic coil 7, that is, on the back side of the object to be inspected 2, and the most effective method and arrangement may be used. .

When an alternating current is intermittently passed through the electromagnetic coil 7 in the arrangement shown in FIG. 1, a fluctuating magnetic field is generated in the vertical direction of the metal plate 3, and this magnetic field causes an eddy current to flow on the surface of the metal plate 3. The interaction between this eddy current and the magnetic field parallel to the surface of the metal plate 3 generated by the magnet 12 generates a Lorentz force in the perpendicular direction on the metal plate 3, and the direction of the eddy current is reversed by reversal of the fluctuating magnetic field generated by the electromagnetic coil 7. However, as a result, the direction of the Lorentz force is also reversed, and as a result, vibration is imparted to the metal plate 3. In addition, when the metal plate 3 is a ferromagnetic material, when an alternating current is intermittently passed through the electromagnetic coil 7, the metal plate 3 is magnetized in the perpendicular direction to produce magnetostriction, and the reversal of the alternating current causes magnetostriction. The direction of the magnetic field is reversed, the metal plate 3 is temporarily demagnetized and almost no magnetostriction is present, and then the metal plate 3 is magnetized in the opposite direction and magnetostriction is generated again. By repeating this process, vertical vibration is applied to the metal plate 3. in this case,
By arranging the magnet 12 in parallel with the electromagnetic coil 7, it is possible to increase the vibration.

The excitation power source 13 that supplies excitation current to the electromagnetic coil 7 also includes an oscillator 14 as shown in FIG.
, an intermittent controller 15 and a current amplifier 16, and an oscillator 1
4 oscillates at a frequency of 20 to 100 kHz,
The intermittent controller 15 is 5, 10, 15, 20, 25, 30,
It is possible to control switching of the output (wave number) every 100 wave cycles, and the current amplifier 16 amplifies the current to a sufficient magnitude and supplies the electromagnetic coil 7 with an alternating current. In addition, in order to superimpose a DC current on this AC current, a voltage Vp is divided into the AC signal generated by the oscillator 14 using a potentiometer 17 and then passed through a load resistor 18 to an intermittent controller 15.
A DC superimposed device 19 is attached to supply a DC signal to the DC signal. In this way, among the excitation currents supplied to the electromagnetic coil 7, a variable magnetic field is generated by the alternating current, and a constant magnetic field is generated by the direct current. The excitation current from the excitation power source 13 and the electromagnetic coil 7 wound around the hollow winding frame 6 are excitation means.

The output circuit 20 that collects the ultrasonic waves generated by the vibration of the metal plate 3, adjusts the output electric signal generated from the sound collector 9, and outputs a desired signal is as shown in FIG. It consists of a front-stage amplifier 21, an excitation wave remover 22, a wave detector 23, and a rear-stage amplifier 24. After the output electrical signal of the sound collector 9 is amplified by the preamplifier 21, when an intermittent excitation current is passed through the electromagnetic coil 7, the induction generates a voltage wave in the sound collector 9 that is the same as the current wave, reducing detection sensitivity. In order to prevent this, the induced voltage is removed from the signal voltage only when current is supplied through the excitation wave remover 22 controlled by the output of the intermittent controller 15 to extract only the true sound signal, and then the wave detector 23 to be introduced. This detector 23 performs envelope detection to detect the strength of vibration of the metal plate 3. The detection signal is amplified by a post-stage amplifier 24, and the vibration intensity is outputted from an analog output terminal 25 to a recorder (not shown). On the other hand,
When the strength exceeds a certain limit, an alarm output is output that sounds an alarm through a comparator 26 connected to the detector 23 to indicate the presence of an abnormality of adhesion such as a part with no adhesive or a part that has peeled off. 27 and a control signal output 28 for controlling the automated bonding line. Here, the comparison voltage Vref which determines the threshold voltage of the comparator 26 is determined by dividing the voltage Vs by a potentiometer 29.

FIG. 3 shows a probe 1 for detecting abnormal adhesion of a ferromagnetic metal plate 3, in which the inner diameter of the electromagnetic coil 7 is approximately 6 m.
It belongs to m. FIG. 4 shows how the probe 1 is used to detect adhesion abnormalities in the hat-shaped sample 30. This sample 30 consists of two hat-shaped members 31, 31.
The flanges 32, 32 on both sides are bonded to each other with an adhesive 5 interposed therebetween. Then, the probe 1 is brought close to the surface of the flange 32 of one hat-shaped member 31 with its electromagnetic coil 7 in a non-contact state and moved along the flange 32, or the probe 1 is fixed and the sample 30 is moved. An example of detecting adhesion abnormalities is shown.

In this manner, the probe 1 and the object to be inspected 2 are scanned relative to each other, and when the probe 1 passes through a portion where an abnormal adhesion portion F as shown in FIG. 1 exists, the metal plate 3 ( The vibration of the flange 32) suddenly increases compared to the normal bonded part N, and as a result, the intensity of the ultrasonic waves generated from the metal plate 3 increases significantly, and the ultrasonic waves are collected by the sound collector 9. The output circuit 20 outputs only a sound wave signal, and the abnormal adhesion portion F is detected using the various methods described above.

The present invention is not limited to the above-described embodiments, but, for example, the center hole 10 and cavity 11 of the probe 1 may be filled with a material that transmits ultrasonic waves to further improve the efficiency of collecting ultrasonic waves. Alternatively, when inspecting an object 2 to be inspected in which the gap into which the probe 1 is inserted is small, it is also possible to make the hollow winding frame 6 longer so that sufficient sound can be collected.

[0025]

[Effects of the Invention] According to the non-contact detection method and device for adhesion abnormality in metal plates of the present invention as described above, vibration is applied to the metal plate by electromagnetic force, and the ultrasonic waves generated thereby are collected. Since it detects adhesion abnormalities, it can be essentially non-contact. In addition, since the electromagnetic coil that excites the metal plate is wound around a hollow winding frame, it is possible to reduce the impedance, thereby increasing the number of turns and generating a large magnetic field with a small current, resulting in power savings. This allows the device to be made smaller and more portable. Since it receives sound in the ultrasonic range, it is less affected by noise in the sonic range and can perform detection with a good S/N ratio.

Furthermore, since the sound collector is a resonant ultrasonic microphone, it is possible to easily receive ultrasonic waves even when the apparatus is away from the metal plate. Furthermore, when a magnet is attached to the electromagnetic coil, it can be applied not only to ferromagnetic metal plates but also to metals in general that are not magnetized. When an intermittent excitation current is passed through the electromagnetic coil, the induction generates a voltage wave in the sound collector that is the same as the current wave, reducing detection sensitivity. By removing the induced voltage from the output signal voltage of the sound device,
This makes it possible to improve detection sensitivity.

[Brief explanation of the drawing]

[Fig. 1] A simplified cross-sectional view showing the probe of the present invention and an object to be inspected.

[Fig. 2] Block circuit diagram of a non-contact detection device for abnormal adhesion of metal plates according to the present invention.

[Figure 3] Simplified side view of the probe

[Figure 4] Simplified cross-sectional view showing the arrangement of hat-shaped samples for testing adhesion abnormalities

[Explanation of symbols]

1 probe
2 Object to be inspected 3 Metal plate
4 Other parts 5
glue
6 Hollow winding frame 7 Electromagnetic coil
8 Hollow frame 9 Sound collector 1
0 Center hole 11 Cavity
12 Magnet 13 Excitation power supply
14 Oscillator 15 Intermittent controller
16 Current amplifier 17 Potentiometer 18 Load resistor 19
DC superimposed device
20 Output circuit 21 Pre-stage amplifier
22 Excitation wave remover 2
3 Detector
24 Post-stage amplifier 25 Analog output terminal 26 Comparator

Claims (6)

[Claims] Claim 1: An alternating current is intermittently passed through a hollow electromagnetic coil disposed on a ferromagnetic metal plate surface that is bonded to another member surface with an adhesive interposed between them. The generated magnetic field and the resulting magnetostrictive effect on the metal plate create a vibration force on the metal plate, and the sound waves generated by the vibration propagated through the hollow electromagnetic coil are collected by a sound collector installed behind the coil. A non-contact detection method for abnormal adhesion of metal plates by detecting the vibration status of the metal plates and determining the adhesion status. 2. A hollow electromagnetic coil and, if necessary, a magnet are provided on a metal plate surface that is bonded to another member surface with an adhesive interposed therebetween, and an alternating current is intermittently applied to the electromagnetic coil. The magnetic field generated by the alternating current causes an eddy current to be generated on the surface of the metal plate, and the interaction with the eddy current and the magnetic field generated by a magnet placed in parallel or the magnetic field generated by superimposing a direct current on the electromagnetic coil causes the metal plate to A vibration force is generated and the sound waves generated by the vibration propagated through the hollow electromagnetic coil are collected by a sound collector installed behind the coil to detect the vibration status of the metal plate and determine the adhesion status. A non-contact detection method for abnormal adhesion of metal plates. 3. Excitation means for electromagnetically vibrating a metal plate in a non-contact manner by disposing it close to the surface of a metal plate that is bonded to the surface of another member with an adhesive interposed therebetween; and the excitation means. It is characterized by comprising a sound collection means that collects sound waves generated from a metal plate subjected to vibration and converts them into electrical signals, and an output circuit that adjusts and outputs an electrical signal based on the sound waves of the sound collection means. A non-contact detection device for abnormal adhesion of metal plates. Claim 4: An electromagnetic coil is wound around a hollow winding frame made of non-metallic material, and a resonant ultrasonic microphone as a sound collector is installed inside the hollow frame integrally formed at the rear of the hollow frame, so that the surface of the metal plate can be touched without contact. a probe configured to perform relative scanning; a frequency-variable excitation power source that intermittently supplies an excitation current of alternating current or a superimposed alternating current and direct current to the electromagnetic coil; and output electricity of the resonant ultrasonic microphone. It consists of an output circuit that removes the noise signal caused by the induction of the excitation current from the signal and outputs only the true sound wave signal due to the ultrasonic waves generated from the excited metal plate; 1. A non-contact detection device for abnormal adhesion of metal plates, characterized in that the device detects the adhesion quality of metal plates bonded to each other with an adhesive interposed between the surfaces of other members at substantially the same resonance frequency as the resonant frequency. 5. The non-contact detection device for abnormal adhesion of metal plates according to claim 4, wherein a permanent magnet is arranged around the outer periphery of the electromagnetic coil of the probe. 6. The non-contact detection device for adhesion abnormality of metal plates according to claim 4, further comprising an alarm output or a control signal output that is generated when a sound wave signal of a certain voltage or higher is generated in the output circuit.