JPS607227B2 - Electromagnetic non-destructive flaw detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-destructive flaw detection device that non-destructively detects flaws in metal materials by applying electromagnetic phenomena.

Generally, a method of detecting flaws that occur in metal materials by applying electromagnetic phenomena is to pass a current through the metal material being inspected and detect the disturbance of the current caused by the presence of flaws as a change in the impedance of the detection coil. Eddy current depth wound method,
Or the magnetic deep flaw method, which applies a magnetic field to the metal material being inspected (limited to magnetic materials) and detects the loss of magnetic flux from the flawed part caused by the presence of flaws, especially automatically. There are several methods for detecting deep scratches, such as using a magnetically sensitive element to remove wax from the scratched area, and directly converting magnetic flux into an electrical signal.Each method is adapted to the shape of the material to be inspected, the manufacturing process, etc., and is widely used. This is where I am.

However, recent demands for improved flaw detection ability and flaw detection efficiency (speed) are shifting from the perspective of 100% precision inspection to increasingly sophisticated ones in order to improve the quality and reliability of various metal materials. In order to improve the hot water detection ability, efforts have been made to miniaturize the detection end and to speed up and stabilize deep damage signal processing circuits, each depending on the purpose.

However, miniaturization of the detection end and flaw detection efficiency are usually contradictory conditions, and this can be resolved by making the detection end more accurate and high-speed tracking scanning of the material to be inspected or by increasing the speed of the deep flaw signal processing circuit. must be addressed.

This invention was made in consideration of the above, and the basic Z principle combines the eddy current deep flaw method and the magnetic flaw detection method.
The present invention aims to provide a completely new electromagnetic flaw detection method and device that simultaneously improves flaw detection ability and flaw detection efficiency.

That is, in the vicinity of the detection coil through which high-frequency current is passed, a magnetic core is placed at one point or multiple points on the magnetic field line of the magnetic field generated by the coil, and the magnetic core is placed on the equimagnetic potential line of the detection coil to the detection coil. Exercise against the
The state of eddy currents that occur in the inspected material directly under each magnetic core and the flux of magnetic flux from the scratched part of the inspected material,
The basic idea is to efficiently convert the state as a change in the impedance of the detection coil by each magnetic core, and to cause deep damage by detecting the change in impedance of the detection coil. next,
The deep wound method and apparatus of the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1 is a plan view of a circular detection coil, which is a main part of the present invention, and FIG. 2 is a side view thereof.

In FIGS. 1 and 2, 1 is a circular detection coil, 2
,, 22 to 28 are near the inner wall of the detection coil,
A plurality of cylindrical magnetic cores 3 arranged on the same circle C as the center of the detection coil each represent a metal body that is a material to be inspected.
The detection coil 1 is held by a fixed part 4 via a holding part 5. The magnetic cores 2, 22 to 28 are rotated about the center lines 1, 1' on a circular orbit C concentric with the center of the detection coil 1. However, the rotation mechanism is not shown in FIG. When a high frequency current is passed through the detection coil 1 in such a state, the magnetic field created by the detection coil 1 causes
The magnetic cores 2, 22, 28 are magnetized and the magnetic cores 2, 22, 28 are magnetized.
The magnetic flux density within 2 to 28 increases in proportion to its magnetic permeability, and the magnetic flux density locally becomes high only in the portion immediately below each magnetic core on the surface of the material to be inspected 3.

Since the magnetic cores 2, 22 to 28 are not arranged at the center of the detection coil 1 as described above, the direction of the magnetic flux on the surface of the material to be inspected 3 directly below each magnetic core is determined by the direction of the magnetic flux on the surface of the material to be inspected 3. It has both vertical and horizontal components.

Among these magnetic fluxes, the vertical component of the magnetic flux induces a local eddy current in a portion of the material 3 to be inspected immediately below the magnetic core 2 . On the other hand, the magnetic flux of the horizontal component results in generation of magnetic flux due to flaws existing on the surface or under the surface of the material 3 to be inspected. However, since the magnetic core 2 is rotating on a circular orbit C that is on the same zero circle as the center of the circular detection coil 1, if a scratch occurs directly below it, the impedance of the detection coil will change due to the disturbance of the eddy current. Scratches can be detected by inducing a change in the impedance of the detection coil due to change, slowing, and linkage with magnetic flux, and detecting this change in impedance.

In the above phenomenon, the magnetic core 2 rotates and scans on the circular orbit C, that is, on the equimagnetic potential lines of the circular detection coil 1.
No matter at what point during the circular motion a scratch arrives, the electromagnetic influence on the detection coil 1 is the same, that is, the deep scratch operation is performed with the same sensitivity.

Needless to say, all of the magnetic cores 2, 22 to 28 operate in the same manner as described above, and the efficiency of deep scratches is significantly improved by a plurality of magnetic cores. 0 As explained above,
The present invention provides a deep flaw method in which the range of motion of the magnetic core relative to the detection coil is the flaw detection range by simply bringing a detection coil having a magnetic core that moves on equipotential lines close to a material to be inspected, and also provides a method for detecting deep flaws by simply bringing a detection coil having a magnetic core that moves on equimagnetic potential lines close to a material to be inspected. The object of the present invention is to provide a flaw detection method that can detect flaws in a wide range with high efficiency by relatively scanning and deeply flawing the material to be inspected.

As an example of the former serious injury mentioned above, the head of a ball joint or the head of a bolt is not rotated and scanned.
It also enables highly efficient zero-depth flaw detection in less than 1 second per flaw, and an example of the latter is the detection of deep flaws in flat metal bodies, such as the surface of thick plates and billets, or flat springs. This is especially effective. In addition, in the embodiment of the present invention, an example was given in which a magnetic core is rotated in the same circular shape inside a circular coil that is easy to manufacture and practical, but for example, a magnetic core is rotated along the long axis of a rectangular coil. Another possibility is to vibrate the
Other designs should be made appropriately depending on the purpose of flaw detection.

Furthermore, as another embodiment of the present invention, when a plurality of magnetic cores are arranged near the detection coil, the shape of the tip thereof is configured in a plurality of types corresponding to the various types of defects to be detected, and the shape of the tip of the magnetic core is configured to correspond to the various types of defects to be detected. The present invention provides a method for efficiently detecting the following at once. In this invention, as described above, the magnetic core is arranged on the equipotential line near the detection coil, and is moved relative to the detection coil on the equipotential line, so that the detection coil is attached to the material to be inspected. We have established a deep damage method that allows the movement range of the magnetic core to become a deep damage range simply by bringing it close to each other.

By the way, a deep flaw apparatus for carrying out the flaw detection method provided by the present invention is as shown in FIG.

That is, reference numeral 6 denotes a detection coil holding stand on which the circular detection coil 1 is placed so as to correspond to the deep flaw surface of the deeply flawed material 3, and is remounted on the flaw-detected material 3 via an roller or the like. The purpose of providing the rollers is to enable the entire table to be moved relative to the material 3 to be inspected. Reference numeral 8 denotes a support frame provided on this holding table 6, which supports the motor 7 with its output shaft 7' aligned with the center of the detection coil.

A magnetic core holding frame 9 is fixed to the output shaft 7' of the motor 7 and holds all the magnetic cores 2, 22 to 28 at its outer peripheral end.

Therefore, due to the rotation of motor 7, each magnetic core 2, , 22 to 2
8 moves on a circular orbit concentric with the detection coil 1 (circular movement). In other words, deep scratches can be made over a wide range by the relative movement of both the braces and the material to be inspected while the core rotates with respect to the detection coil. By making the detection coil circular, a rotation drive mechanism such as a motor can rotate each magnetic core (only one magnetic core may be used), and a flaw detection device can be realized with a simple configuration. The characteristics of the flaw detection method and device provided by the present invention are as described above, but are not limited to the above and illustrated examples. First, regarding the material to be inspected, it is not affected by the shape or size of the material to be inspected, and the range of application is wide, from deep flaws on parts to flaw detection on materials. , the shape of the magnetic core, the speed and range of motion of the magnetic core, etc. can be appropriately designed. Furthermore, it would be advantageous to cause the magnetic core to move at a constant velocity, such as a uniform circular motion, because it would facilitate frequency analysis of the defect signal, regardless of the scanning speed when scanning and making deep scratches on the inspected material. As described in detail above, in this invention, a magnetic core is placed near the detection coil under special conditions and is moved. In addition to the principle, the defect detection sensitivity is not lowered at all compared to the conventional electromagnetic deep flaw method using only one detection coil, and a wide range of flaws can be detected at the same time.

The flaw detection method according to the present invention is most suitable for detecting deep flaws in flat metal bodies, and at the same time has a remarkable flaw detection effect for deep flaws in parts having curved surfaces. The flaw detection device embodying this can also be simplified in structure and fully meet the demands of the industry.
Overall, this invention guarantees a revolutionary improvement in deep wound technology.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the detection mechanism which is the main part of the present invention, and is a plan view showing the arrangement relationship between the circular detection coil and the magnetic core, and the circular motion trajectory of the magnetic core on the same D circle. FIG. 2 is a side view showing the positional relationship between the detection mechanism shown in FIG. 1 and the material to be inspected, and FIG. 3 is a diagram showing the configuration of a specific apparatus. 1...Detection coil, 2,, 22-28...Magnetic core, 3...
... Material to be inspected, 6... Detection coil holding stand, 7...
...Motor, 9...Magnetic core holding frame. Hair clove illustration 2nd figure 3rd figure

Claims (1)

[Claims] 1. In the vicinity of a detection coil installed close to the material to be inspected, magnetic cores are arranged at one point excluding its geometric center or at multiple points on equimagnetic potential lines including that one point. Defects in the material to be inspected are detected by detecting changes in the impedance of the detection coil that includes this magnetic core, which is caused by moving this magnetic core relative to the coil on equipotential lines of the detection coil. An electromagnetic non-destructive flaw detection method characterized by: 2. Claim 1, characterized in that the tip shapes of the magnetic cores arranged at multiple points on the equimagnetic potential lines of the detection coil are configured in a plurality of types to detect a plurality of types of defects.
Electromagnetic non-destructive flaw detection method described in section. 3. In the vicinity of the detection coil installed close to the material to be inspected, a magnetic core is placed at one point excluding its geometric center or at multiple points on equipotential lines including that one point, and this magnetic core is The detection coil is moved relative to the detection coil on equipotential lines of the detection coil, and both the detection coil and the magnetic core are moved and scanned relative to the material to be inspected. An electromagnetic non-destructive flaw detection method characterized by scanning a wide range of a material to be inspected by detecting changes in the impedance of a detection coil. 4. A circular detection coil installed corresponding to the flaw detection surface of the material to be inspected, a magnetic core placed at one point excluding the center or at multiple points on a concentric circle including that one point, and this magnetic core used for the detection described above. and a rotational drive mechanism that rotates the detection coil on a circular orbit concentric with the coil, and detects defects in the inspected material by detecting changes in impedance of the detection coil. An electromagnetic non-destructive flaw detection device characterized by: