JPH0566543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for non-destructive testing of bonded surfaces, and more particularly to a method for non-destructive testing of bonded surfaces that utilizes fluctuations in the magnetic field of the bonded surfaces.

[Prior Art] As a method for non-destructively inspecting joint surfaces between members, a method using ultrasonic waves or X-rays can be considered. Acoustic acquisition (AE)
The AE method, which performs non-destructive inspection by detecting , is also being applied to non-destructive inspection of bonded surfaces. Furthermore, an eddy current flaw detection method (electromagnetic induction flaw detection method) is also known as a non-destructive testing method for metal materials.

[Problems to be Solved by the Invention] However, with the above method, although it is possible to detect defects inside a certain member, it is not easy to determine the quality of the joint surfaces between two or more members. It wasn't. For example, in the pulse echo method in which ultrasonic waves are applied to the surface from a direction perpendicular to the surface, since the joint surface is the boundary between different objects, large reflections occur regardless of the quality of the joint, making accurate inspection difficult. Further, even if X-rays are used instead of ultrasonic waves, the gap caused by poor bonding is very thin, so the difference in X-ray transmission between a good bond and a defective bond is small, making it still difficult to conduct an accurate inspection.

In addition, the AE method detects the elastic waves released when the energy stored in the form of strain is released when a solid undergoes plastic deformation or phase transformation. However, it cannot be applied to the inspection of joint surfaces under normal conditions without plastic deformation or phase transition.
The scope of use is narrow.

Further, although the conventional eddy current flaw detection method is suitable for detecting flaws inside or on the surface of a metal member, it is not suitable for determining the quality of the joint between the joint surfaces of two or more members.

[Means for Solving the Problems] The present invention utilizes the phenomenon in which the magnetic field formed on the joint surface is disturbed by mechanical high-frequency vibrations applied to the joint surface to determine the quality of the joint surface. In a method for non-destructive testing of joint surfaces between members, a non-annular iron core coil having a primary excitation coil and a secondary inspection coil is connected so that both ends of the iron core can be detected. It is arranged so as to be located on both sides of the joint surface to be inspected of one member, and conducts high-frequency current to the excitation primary coil and detects the secondary voltage or secondary current in the detection secondary coil. While doing so, mechanical high-frequency vibration is applied to the other member to vibrate the joint surface, and a secondary voltage or a secondary voltage generated by this vibration is generated.
The present invention provides a non-destructive inspection method for bonded surfaces, which is characterized in that the bonded surfaces are inspected by detecting changes in current.

First, the principle of the present invention will be explained in the first part showing an example.
The following description will be made with reference to FIGS.

In FIGS. 1 and 2, reference numeral 1 denotes a joint surface between members A and B, which consists of a well-joined portion 2 and a poorly joined portion 3. 4 is an iron core coil, which includes an iron core 5, a primary coil 6 for excitation, and a 2 coil for detection.
It has a secondary coil 7. The iron core 5 is arranged so as to cross the member A, and when a current is passed through the primary coil 6 using a high frequency AC power source 8, a magnetic circuit passing through the joint surface of the iron core 5 and the member B is formed, and the member B A magnetic field is formed at the junction surface of the

This magnetic field generates an eddy current I on the joint surface of member B in a direction perpendicular to the plane of the paper.

In this state, when mechanical high-frequency vibration is applied to member A using a vibrator or vibrator 9, this vibration is transmitted to the joint surface 1, and the electrons, which are charged particles, existing near the joint surface are accelerated ( That is, the force F) acts, and the electrons move based on this high-frequency vibration, producing a current with a different component from the eddy current. Due to this newly generated current, a new magnetic field (secondary magnetic field H') is additionally formed, thereby causing a disturbance in the magnetic field at the bonding surface. When the magnetic field at the joint surface is thus disturbed, the magnetic flux within the iron core 5 is also disturbed, and the voltage or current induced in the detection secondary coil 7 is also changed.

Therefore, in the part 2 of the bonding surface 1 where the bonding condition is good, vibrations are well transmitted from member A to member B, and the force acting on the electrons, which are charged particles, becomes large, and therefore the degree of disturbance of the magnetic field becomes large. Nari, 2
Changes in the secondary voltage or secondary current become large. On the other hand, in the portion 3 where the joint condition is poor, the member A
Since the vibrations transmitted to member B are reduced and the force acting on the electrons is also reduced, disturbances in the magnetic field are reduced and changes in the secondary voltage or secondary current are also reduced.

Therefore, by detecting the change in voltage or current in the secondary coil 7 caused by applying vibration to the member A, it is possible to detect the quality of the joint surface.

To detect changes in secondary voltage or current, detect the secondary voltage or secondary current in a static state with no vibrations applied to member A, and the secondary voltage or secondary current in a vibrating state with vibrations applied to member A. Specifically, the following method is used. In the following description, changes in the secondary current will be described, but it is clear that changes in the secondary voltage may also be detected.

(a) Compare the deviations (phase lead or lag) of the phase of the secondary current in a stationary state and the phase of the secondary current in an oscillating state, without determining the deviation from the phase of the primary current.

(b) Compare the maximum value of the secondary current in the static state and the maximum value of the secondary current in the vibration state with the maximum value of the primary current, find the difference, and calculate the difference between them.
Compare the difference with the next current.

(c) Determine the degree of disturbance of the secondary current waveform in the static state and the secondary current waveform in the vibration state from the primary current waveform, and compare them.

Note that two or more of the methods A to C may be combined. In addition, methods A to C are just examples,
Other comparison methods may also be used.

[Operation] Using an iron core coil having a primary coil for excitation and a secondary coil for detection, a magnetic flux is passed through the joining surface of one joining member, and a mechanical high frequency is applied to the joining surface of this one member through the other member. When vibration is applied, a change in the secondary voltage or secondary current appears depending on the quality of the bond between the bonding surfaces. For that purpose, these two
By detecting changes in voltage or current, it is possible to conduct a non-destructive inspection of the joint surface.

[Embodiment] FIG. 1 is a sectional view showing an embodiment of the present invention as described above. In this embodiment, the core coils 4 include a plurality of U-shaped coils installed in parallel via an electromagnetic shielding material 10, as shown in FIG. 3, and each core 5, 5... Primary coils 6, 6 for excitation and 2 for detection respectively.
Next coils 7, 7... are wound. 6
a and 7a each indicate a lead wire.

FIG. 4 is a block diagram showing the configuration of an apparatus for carrying out the method of the present invention. 11 is a high frequency power source, and a plurality of excitation coils 6 are connected to its output side. Further, the same number of secondary coils 7 for detection are provided opposite to the primary coils 6 for excitation. In FIG. 4, the excitation coil 6 and the detection secondary coil 7 are respectively numbered from 1 to n via a hyphen from the top of the figure. In addition, in order to clarify the effect of the present invention,
The bonding surface 1 is schematically illustrated.

The secondary voltages or secondary currents output from the detection secondary coils 7-1 to 7-n are input to the differential amplifier 13 via the scanner 12. Further, the same voltage or current as the output of the high frequency power source 11 can also be input to the differential amplifier 13. 14 is an oscillator whose oscillation output is transmitted to the high frequency vibrator 9 via an amplifier 15. A computer 16 inputs the output value of the differential amplifier 13, stores necessary information and performs calculations, and also controls the entire inspection apparatus. 17 is a stepping motor provided in a rotating device (not shown) that rotatably supports the iron core coil 4, and rotates the iron core coil 4 around its central axis C (see Figs. 1 to 3). It can be rotated by a predetermined angle.

Note that the scanner 12 has a detection secondary coil 7-1.
~7-n output values are selected sequentially and the differential amplifier 1 is
This is a scanning device for inputting data to the computer.

Next, the operation of the above device will be explained using an example in which a current is detected as a secondary side output.

First, the high frequency power source 11 is turned on to generate a magnetic flux passing through the joint surface of the member B. Next, Sukiyana 1
2, the detection secondary coils 7-1 to 7-
The n secondary currents are sequentially input to the differential amplifier 13. The differential amplifier 13 compares each secondary current with the output current of the high frequency power supply 11, and
-1, 7-2, . . . 7-n, the _comparison values of the secondary current and the primary current are respectively x ₁ , x ₂ . ) The results x ₁ , x _{2 .} . . x _o are output to the computer 16. Computer 16 temporarily stores this information. Next, the oscillator 13 is activated, and its output is amplified by the amplifier 14 and transmitted to the vibrator 9, thereby imparting vibration to the member A. The vibration applied to member A is transmitted to member B through joint surface 1.
This causes a disturbance in the magnetic field at the bonding surface of member B, and a secondary current is generated.

Therefore, the scanner 12 is operated in synchronization with the oscillator 14, and the output values of the detection secondary coils 7-1 to 7-n are sequentially input to the differential amplifier 13. The differential amplifier 13 compares the output current of the high-frequency power supply 11 and the detected value from this secondary detection coil, and converts these comparison values into y ₁ , y ₂ , . . .
y _o . ) The comparison results y ₁ , y _{2 .} . . y _o are output to the computer 16.

The computer 16 calculates the comparison values x ₁ , x ₂ , x ₃ in a stationary state in which the vibrator 9 is not operating.
. . . x _o and the newly read comparison values y ₁ , y ₂ , y ₃ . . . y _o in the vibration state are compared, respectively.

As mentioned above, the disturbance of the magnetic field is large in areas where the bonding surface is good, and therefore the secondary current induced by the magnetic flux passing through that area is detected2.
The change in the output value of the next coil becomes large.

FIG. 5 is a projected diagram showing the change in secondary current when a magnetic flux is formed in the direction of arrow H and vibration is applied to member A. As shown by curve 20 in FIG. The degree of disturbance of the secondary current induced by the magnetic flux passing through the good part 2 of the junction is large;
Disturbances in the secondary current induced by the magnetic flux passing through the defective joint location 3 are small.

When all the comparisons of the output values of the secondary coils in one magnetic field direction are completed in this way, the computer 16 outputs a signal to the stepping motor 17 to rotate the iron core 4 by a predetermined angle, and performs the same procedure as described above. Measure the fluctuation in the output value of the secondary coil. Repeat this operation until the iron core coil 4 is rotated 180 degrees from the initial position. All of the comparison results are stored in the computer 16, and after the measurement is completed, the bonding state in the planar direction (two-dimensional direction) of the bonding surfaces can be determined by tomography.

In this way, a rapid non-destructive inspection of the joint surface can be performed.

In the above embodiment, the iron core 5 is U-shaped, but in short, it can be any type of iron core that can form a magnetic flux that passes from one side of the joint surface of the members to the other side. It is clear that other core shapes, for example C-shaped cores, may also be used.

[Results] As detailed above, the non-destructive testing method of the present invention utilizes fluctuations in the magnetic field along the joint surfaces of parts, and can accurately and accurately determine the quality of the joint at the joint surfaces. Can be detected quickly.
Furthermore, the method of the present invention can be applied to any joint surface that can allow magnetic flux to pass through the joint surface and transmit mechanical high-frequency vibrations to the joint surface, regardless of the material of the member. .

[Brief explanation of the drawing]

1 and 2 are cross-sectional views for explaining the embodiment method of the present invention, FIG. 3 is a perspective view of the iron core coil, and FIG.
The figure is a block diagram of an apparatus for carrying out the method of the present invention, and FIG. 5 is a perspective view showing an example of a joint surface and an example of data analysis results. 1... Joint surface, 4... Iron core coil, 6... Primary coil for excitation, 7... Secondary coil for detection, 9...
vibrator.

Claims (1)

[Scope of Claims] 1. In a method for non-destructive testing of joint surfaces between members, a non-annular iron core coil having a primary coil for excitation and a secondary coil for inspection is provided such that both ends of the iron core are connected to one member. It is arranged so as to be located on both sides of the joint surface to be inspected, and while supplying high-frequency current to the excitation primary coil and detecting the secondary voltage or secondary current in the detection secondary coil, A mechanical high-frequency vibration is applied to the member to vibrate the joint surface, and the secondary voltage or secondary voltage generated by this vibration is
A method for non-destructive inspection of bonded surfaces, characterized by inspecting the bonded surfaces by detecting changes in current. 2. The inspection is performed by energizing the excitation primary coil, detecting with the detection secondary coil, and applying mechanical high-frequency vibration while rotating the iron core coil relative to the joint surface. A method for non-destructive inspection of a joint surface according to claim 1. 3. The iron core coil according to claim 1 or 2, wherein the iron core coil has a U-shaped iron core coil, and the iron core is arranged so as to cross the joint surface. Non-destructive testing method for joint surfaces. 4. The method for non-destructive inspection of a bonded surface according to any one of claims 1 to 3, characterized in that a plurality of the iron core coils are installed in parallel.