JPS5844207B2 - Dead zone suppression method and device for magnetic flaw detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for suppressing leakage magnetic flux generated when using a magnetization device for magnetic flaw detection.

In general, a magnetization device used for magnetic flaw detection tests a core having a magnetized portion with a coil wound around it, which is brought into contact with or close to the surface of a material to be inspected, and conducts flaw detection of the material to be inspected while energizing the coil.

At this time, magnetic flux is distributed around the magnetized part (magnetic pole part), and as shown in FIG.

A magnetic flux distribution φ□ that permeates inside the test material 1, magnetic flux distribution φ2 that leaks from the magnetic pole 2 into the air, and magnetic flux φ□ that permeates the test material 1 leaks into the space of the defective part 3. Magnetic flux distribution φ3° However, when performing flaw detection using magnetic particles (not shown), due to the magnetic flux distribution φ3 leaking from the test material 1 and the defective portion 3 described above,
An aggregation pattern of magnetic particles (magnetic particle pattern) is obtained in the defective portion 3, and the defective portion 3 is detected.

However, in the above flaw detection, the following problems often occur depending on the strength of magnetization.

That is, the magnetic flux φ2 leaking into the air from the aforementioned magnetic pole 2
may be permeated by the magnetic flux φ3 leaking into the space of the defective part 3, causing magnetic disturbance, and as shown in Figure 2 A and B, an area A (dead zone area) where no flaws can be detected is generated. Therefore, the effective detection range B of the defective part 3 in the magnetization device decreases,
There is a problem that inspection efficiency deteriorates, and there is currently nothing to suppress this dead zone area A.Furthermore, in order to expand the effective detection range B, it is necessary to increase the size of the magnetization device itself, which causes the weight to increase. It had the disadvantage that it became a physical object and was inconvenient to handle.

The present invention has been made to solve the above-mentioned problems, and the present invention is directed to the magnetic flux φ2 leaking into the air from the magnetic poles of the magnetizing device.
The purpose is to provide a compact magnetization device that minimizes the spread of magnetization, expands the effective detection range B, and increases inspection efficiency. 1) In a magnetic flaw detection method in which a coil is wound around a core and current is applied to the coil to form a magnetic flux in the magnetic pole, and the magnetic flux is permeated into the material to be inspected to detect defects in the material to be inspected, the magnetic pole Either the leakage magnetic flux in the dead zone area generated from the part is passed through the ring-shaped or rectangular leakage magnetic flux suppressor, and then passed through the inside of the magnetic flux suppressor, or a part of the magnetic flux directly in the direction of the leakage magnetic flux suppressor is transferred to the test material. permeable to,
A method for suppressing a dead zone region for magnetic flaw detection, which is characterized by reducing leakage magnetic flux in a dead zone region, and in order to implement this method efficiently and easily, (2) winding a plurality of coils of endless core ice; In a magnetic flaw detection device in which a magnetic pole is formed between, a ring-shaped or rectangular magnetic flux suppressor made of a magnetic material, or a magnetic material and a conductive material is used on the inner periphery or the inner or outer periphery of the magnetization device for magnetic flaw detection. (3) a dead zone area suppression device for magnetic flaw detection, characterized in that it is provided with a tool;
A coil is wound around an end-shaped core, and at least one pair of ends l
A magnetizing device for magnetic flaw detection in which magnetic poles are formed, characterized in that a ring-shaped or rectangular magnetic flux suppressor made of a magnetic material, or a magnetic material and a conductive material is provided between the magnetic poles. A dead zone region suppressing device and (4) a magnetizing device for magnetic flaw detection in which a coil is wound around an end-shaped core and magnetic poles are formed at at least one pair of ends, in which a magnetic material or a magnetic material is provided around each of the magnetic poles. This device comprises a dead zone region suppressing device for magnetic flaw detection, characterized in that it is provided with a ring-shaped or rectangular magnetic flux suppressing device made of a conductive material and a conductive material.

Embodiments of the method and apparatus of the present invention will be described below with reference to the drawings.

Example 1 In Figure 3 A, B, and A, 11 is an endless core.

This endless core 11 is made of a ferromagnetic material or a conductive material.

12 is a coil.

A plurality of coils 12 are provided on the core 11 and are made of copper wire, aluminum wire, or the like.

13 is a magnetic pole part. This magnetic pole part 13 is connected to the coil 12.
is provided in between.

14 is a leakage magnetic flux suppressor.

The leakage magnetic flux suppressor 14 is formed into a ring shape or a rectangular shape to cover the core 11, and is made of a magnetic material or a magnetic material and a conductive material.

In this example, the leakage magnetic flux suppressor 14 is provided inside and outside the core 11 to further cover the upper part, but the present invention is not limited to this, and it may be applied only to the inside of the core 11 without covering the upper part.

Reference numeral 15 indicates a material to be inspected.

According to the above-mentioned stealing method, first, the coil 12 is energized and the specimen 1 is
5 is magnetized, the magnetic flux distribution φ2 leaking from the magnetic pole 13 into the air is captured in the leakage magnetic flux suppressor 14, and the dead zone A becomes a narrow area as shown in Fig. 3 A, and the magnetic flux distribution φ2 leaking into the air from the magnetic pole 13 is Also, effects such as being formed more compactly due to the narrower dead zone area A were observed.

Embodiment 2 In the above-mentioned Embodiment 1, the case where the core 11 is endless has been described, but the core 11' having an end, for example, FIG.
B. When a ring-shaped leakage magnetic flux suppressor 14' is provided between the magnetic poles 13' of the gate-shaped core 11' as shown in (a) and the coil 12' is energized to magnetize the test material 15', Of the magnetic flux distribution φ2 leaking into the air from the magnetic pole 13',
The magnetic flux in the dead zone area A' is captured in the leakage magnetic flux suppressor 14', and the dead zone area A' is reduced to a range as shown in FIG. It was done.

Note that similar effects were obtained even when the leakage magnetic flux suppressor 14' was divided into small pieces and formed into scale-shaped rings.

Embodiment 3 A ring-shaped leakage magnetic flux suppressor 14' is provided at each of the magnetic poles 13' of the end-shaped core 11' of the above-described embodiment 2, for example, as shown in FIG. 5A, in the gate-shaped core 11'. When the test material 15' is magnetized by applying current to the magnetic pole 13', the magnetic flux in the dead zone area A' of the leakage magnetic flux distribution φ2 is transferred from the magnetic pole 13' to the air (of the leakage magnetic flux distribution φ2).
The dead zone region X was reduced to a range as shown in FIG. 5A, and the same effects as in Examples 1 and 2 described above were obtained.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the magnetic flux distribution during magnetic flaw detection, where A is the magnetic flux distribution permeating the material to be tested, B is the magnetic flux distribution leaking from the magnetic poles into the air, and B is the magnetic flux distribution passing through the material to be tested. This shows the magnetic flux distribution where the magnetic flux leaks into the space of the defective part. Figure 2 is a distribution state diagram showing the dead zone region leaking from the magnetic pole into the air in the magnetic flux distribution during magnetic flaw detection. show. FIG. 3 is an explanatory view showing an embodiment using an endless core, in which A is a schematic perspective view of a magnetizing device using the leakage magnetic flux suppressor of the present invention, B is a plan view of A, and A is a schematic perspective view of a magnetizing device using the leakage magnetic flux suppressor of the present invention, It is a XX sectional view. FIG. 4 is an explanatory view showing an embodiment in which an end core is used, in which A is a schematic perspective view of a magnetizing device using the leakage magnetic flux suppressor of the present invention, B is a plan view of FIG. FIG. 3 is a plan view showing another embodiment of the invention. FIG. 5 is an explanatory diagram showing another embodiment of the leakage magnetic flux suppressor using the end core shown in FIG. 4, and A is a schematic perspective view of a magnetization device using the leakage flux suppressor of the present invention; Figure A is a plan view of Figure A. 11: Core, 12: Coil, 13: Magnetic pole, 14: Leakage magnetic flux suppressor, 15: Test material, A: Dead zone area, B: Effective flaw detection range, φ□: Test material magnetic flux, φ2: Leakage from magnetic pole Magnetic flux, φ3: Leakage magnetic flux from defective part.

Claims (1)

[Claims] 1. A magnetic flaw detection method in which a coil is wound around a core, and by energizing the coil, a magnetic flux is generated in a magnetic pole, and the magnetic flux is permeated into the material to be inspected to detect defects in the material to be inspected. In this method, the leakage magnetic flux in the dead zone area generated from the magnetic pole is allowed to penetrate into a ring-shaped or square-shaped leakage magnetic flux suppressor, and then passed through the leakage magnetic flux suppressor, or one of the magnetic fluxes in the leakage magnetic flux suppressor is allowed to pass through the leakage magnetic flux suppressor. 1. A method for suppressing a dead zone region for magnetic flaw detection, characterized by transmitting a magnet through a material to be inspected to reduce leakage magnetic flux in the dead zone region. 2. In a magnetization device for magnetic flaw detection in which a plurality of coils are wound around an endless core and magnetic poles are formed between the coils, the inner circumference of the magnetization device for magnetic flaw detection is made of a magnetic material or a magnetic material and a conductive material. 1. A dead zone area suppression device for magnetic flaw detection, characterized in that a ring-shaped or square-shaped leakage magnetic flux suppression device is provided. 3. In a magnetization device for magnetic flaw detection in which a coil is wound around an end-shaped core and magnetic poles are formed at at least one pair of ends, a ring-shaped or A dead zone area suppressing device for magnetic flaw detection, characterized in that a rectangular magnetic flux suppressing device is provided. 4. In a magnetization device for magnetic flaw detection in which a coil is wound around an end-shaped core and magnetic poles are formed at at least one pair of ends, a ring made of a magnetic material or a magnetic material and a conductive material is provided around each of the magnetic poles. 1. A dead zone region suppression device for magnetic flaw detection, characterized in that a magnetic flux suppression device having a shape or a rectangular shape is provided.