JP2021004774A - Electrode for magnetic powder flaw detection device - Google Patents

Abstract

To prevent the damage on an inspection object and an electrode due to the spark generated on an electrode contact surface in the magnetic powder flaw detection inspection with the axial conduction method, and prevent the unevenness in the detection sensitivity generated near an end surface of the inspection object in the magnetic powder flaw detection inspection with the combined magnetization of the coil method and the axial conduction method.SOLUTION: There is provided an electrode for a magnetic powder flaw detection device in which a contact part with an inspection object has a recess in a tapered shape at a prescribed angle in the magnetic powder flaw detection device for magnetizing the inspection object with the axial conduction method. There is provided the electrode for the magnetic powder flaw detection device in which the contact part with the inspection object is made of iron and has the recess in the tapered shape at the prescribed angle in the magnetic powder flaw detection device for performing magnetization with the combined magnetization with the alternating-current or half-wave rectification of the coil method and the axial conduction method. The recess in the tapered shape has the cone shape or the inverted quadrangular pyramid shape.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode for a magnetic particle flaw detector, and more particularly to an electrode in a magnetic particle flaw detection inspection in which an object to be inspected is energized or a magnetic field is applied to perform flaw detection using magnetic powder.

The magnetic particle flaw detection test is applied to the flaw detection inspection of the surface of steel materials such as billets and objects to be inspected such as automobile parts, and is standardized in JIS-Z-2320. In the magnetic particle inspection test, a magnetic powder dispersion liquid containing magnetic powder, that is, a magnetic powder liquid is applied to the surface of the object to be inspected, and a magnetic field is applied to the object to be inspected or an electric current is applied to magnetize the object to be inspected. When there is a scratch such as a crack on the surface of the magnetized object to be inspected, magnetic flux leaks from the scratch, so that a magnetic powder instruction pattern is formed by the leaked magnetic flux. Then, the defect is inspected by observing this magnetic particle instruction pattern. In the magnetic particle inspection, a fluorescent magnetic particle inspection using a fluorescent magnetic powder containing a phosphor is also known in order to improve the flaw detection accuracy.

In the axial energization method of magnetic particle inspection, an electric current is passed through the object to be inspected to generate a magnetic field perpendicular to the direction of energization to magnetize the object to be inspected. With this inspection method, scratches in the direction perpendicular to the magnetic field can be detected, and the sensitivity to scratches in the axial direction is good.

In the combined magnetization of the coil method and the axial energization method by alternating current or half-wave rectification, a current is passed through the object to be inspected, and at the same time, a magnetic field is applied in the axial direction from the outside, and scratches in all directions are detected by the combined rotating magnetic field. Can do things.

In Patent Document 1, when a long square columnar steel material is inspected by the axial energization method, a notch is provided so as to avoid the label on a steel piece having a product management label on the end face in the longitudinal direction. The electrode is disclosed. Moreover, the electrode is made of copper of a good electric body.

Japanese Unexamined Patent Publication No. 2006-322748

Patent Document 1 discloses an electrode inclined with respect to an end face of an object to be inspected in order to improve electrical contact in the axial energization method. However, here, the object to be inspected is a square columnar object, and the columnar object to be inspected is not considered. Further, the magnetization method is only the axial conduction method, and the composite magnetization by the coil method or the like is not considered.

The end face of the object to be inspected, which is an industrial product, may not be a completely smooth surface due to the finishing accuracy of the surface and marking. In addition, the object to be inspected may be transported diagonally to the electrode by automatic transport or the like. In that case, when magnetizing by the axial energization method, the object to be inspected and the electrode come into contact with each other at one point or in a small area, and sparks may occur when energized. Further, a difference in current density near the end face of the object to be inspected occurs, and the detection force in the circumferential direction becomes uneven.
Further, when the contact portion made of copper is magnetized by the combined magnetic field of the coil method and the axial energization method, a magnetic pole is generated near the end face of the object to be inspected due to the influence of the coil magnetization. As a result, there is a problem that a pseudo pattern is generated near the end face of the object to be inspected and the detection force in the circumferential direction is lowered.

Therefore, an object of the present invention is to prevent sparks generated on the electrode contact surface when performing a magnetic particle flaw detection inspection by the axial energization method, reduce damage to the object to be inspected and the electrode, and further combine the coil method and the axial energization method. An object of the present invention is to eliminate unevenness generated near the end face of the object to be inspected during magnetization and improve the detection sensitivity.

In order to solve the above problems, the present invention presents a magnetic powder flaw detector that magnetizes an object to be inspected by using an axial energization method.
The contact portion with the object to be inspected is characterized in that it has a shape in which a tapered recess is formed at a predetermined angle.

Further, in a magnetic powder flaw detector that magnetizes the object to be inspected by combined magnetization by AC or half-wave rectification by the coil method and the axial energization method.
The contact portion with the object to be inspected is made of iron and has a shape in which a tapered recess is formed at a predetermined angle.

Further, the tapered recess is characterized in that it has a mortar shape.

Further, the tapered recess is characterized in that it has an inverted quadrangular pyramid shape.

Further, the predetermined angle is 25 degrees or more and 45 degrees or less.

According to the present invention, in the magnetic powder flaw detector that magnetizes the object to be inspected by using the axial energization method, the contact portion with the object to be inspected has a shape in which a tapered recess is formed at a predetermined angle. The contact portion with the inspected object makes good contact, the generation of sparks is suppressed, and the inspected object can be magnetized uniformly.

Further, according to the present invention, in a magnetic powder flaw detector that magnetizes an object to be inspected by combined magnetization by alternating current or half-wave rectification by the coil method and the axial energization method.
Since the contact part with the object to be inspected is made of iron and has a shape with a tapered dent at a predetermined angle, the contact part with the object to be inspected makes good contact, suppresses the generation of sparks, and further, is inspected. The magnetic field does not concentrate on the end of contact with the object, and the object to be inspected can be magnetized uniformly.

Further, according to the present invention, since the tapered dent is mortar-shaped, the contact portion makes good contact with the columnar object to be inspected, suppresses the generation of sparks, and is uniformly inspected. It can magnetize things.

Further, according to the present invention, since the tapered dent has an inverted quadrangular pyramid shape, the contact portion makes good contact with the prismatic object to be inspected, suppresses the generation of sparks, and is uniform. The object to be inspected can be magnetized.

Further, according to the present invention, since the predetermined angle is 25 degrees or more and 45 degrees or less, the inspected object and the contact portion come into good contact with each other, the generation of sparks is suppressed, and the inspected object is magnetized uniformly. It becomes possible.

The contact portion of the magnetic particle flaw detector according to the present embodiment and the object to be inspected. It is a perspective view of the contact part of the magnetic particle inspection device which concerns on this embodiment. (A) An object to be inspected whose end face is slanted with the contact portion of a conventional magnetic particle flaw detector. (B) The contact portion of the magnetic particle flaw detector according to the present embodiment and the inspected object having an oblique end face. (A) The contact portion of the conventional magnetic particle flaw detector and the inclined object to be inspected. (B) The contact portion of the magnetic particle flaw detector according to the present embodiment and the inclined object to be inspected. It is a perspective view of the contact part of the magnetic particle inspection device which concerns on another embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an iron contact portion 1 for a magnetic particle flaw detector according to the present embodiment and an inspected object 2 made of a ferromagnetic material such as iron. The contact portion 1 is formed in a tapered shape and is in contact with the object 2 to be inspected at two or more contact points. A perspective view is shown in FIG. The contact portion 1 has a mortar-shaped recess. By using the contact portion 1 having such a shape in the magnetic particle flaw detector, it is possible to stably hold the object 2 to be inspected and to make contact at two or more points, so that a stable current can flow, and further, it is made of iron. Therefore, magnetic poles cannot be formed at both ends of the object 2 to be inspected, and a magnetic field can be stably applied.

The contact portions 1 are paired, and the inspected object 2 is fixed so as to be sandwiched from the left and right sides of the inspected object 2. The contact portion 1 is larger than the object 2 to be inspected. With such a configuration, the contact portion 1 can securely fix the object 2 to be inspected, can flow a stable current, and can stably apply a magnetic field, and has good accuracy. Magnetic particle flaw detection inspection can be performed.

When a current is passed through the object 2 to be inspected by the shaft energization method, the contact portion 1 becomes an electrode. Further, when a magnetic field is applied to the object 2 to be inspected by the coil method, the contact portion 1 becomes a magnetic pole. Further, there is also a method in which the axial energization method and the coil method are performed at the same time, alternating current is applied, and composite magnetization is used.
The invention of this patent is a contact portion used in these methods, but the names are generically referred to as "electrode for magnetic particle flaw detector".

In the axial energization method, an electric current is passed through the object 2 to be inspected to generate a magnetic field in the circumferential direction to magnetize the object 2 to be inspected. The current flowing through the object 2 to be inspected is 50 to 5000 A, which is a large current. The voltage is 5 to 20 V, and this current is passed for 3 to 10 seconds. Therefore, when the electrical contact between the contact portion 1 and the object to be inspected 2 is poor, or when there is a point contact, a spark cannot be obtained and an accurate magnetic particle instruction pattern cannot be obtained.
In the coil method, a magnetic field generated from the outside is applied to the object 2 to be inspected in the axial direction. The magnetic field generated by the external coil is 0.5 to 2 Tesla. In this coil method, it is desirable that the contact portion 1 and the object to be inspected 2 come into good contact with each other, and at the same time, the contact portion 1 is made of iron. In the case of copper, the electrical conductivity is good, but since it is not a ferromagnet, the end portion of the object 2 to be inspected becomes a magnetic pole, and an accurate magnetic particle indication pattern cannot be obtained in the vicinity of the end portion. Since the contact portion 1 is made of iron, a good magnetic circuit is formed between the contact portion 1 and the external coil, and the detection accuracy near the end portion of the object to be inspected 2 is improved.

When the object 2 to be inspected has a cylindrical shape, the contact portion 1 preferably has a mortar shape as shown in FIG. The angle of the recess of the contact portion 1 is represented by θ in FIG. 1, and is preferably 5 degrees or more and 60 degrees or less, and more preferably 25 degrees or more and 45 degrees or less.

When the angle of the recess of the contact portion 1 is less than 25 degrees, the object 2 to be inspected does not slip in the electrode when the crimping pressure is weak, and the object 2 to be inspected does not move to a position where a plurality of points are in contact with each other. Further, if this angle exceeds 45 degrees, the contact portion 1 becomes longer than necessary, resulting in poor usability.

The conventional contact portion has a flat plate shape as shown in FIG. 3 (A). The end face of the object 12 to be inspected in FIG. 3A is not parallel to the contact portion 11. Therefore, the contact becomes a point contact, and a gap 13 is formed between the object to be inspected 12 and the contact portion 11. When an electric current is passed through this, sparks may occur and damage the object to be inspected 12 and the contact portion 11. In addition, an accurate magnetic particle instruction pattern cannot be obtained.
On the other hand, as shown in FIG. 3B, the contact portion 1 of the present invention is recessed in a mortar shape, so that the contact portion 1 can be moved up and down even if the end surface of the object 2 to be inspected is slanted. It is possible to make good contact with. The contact between the contact portion 1 and the object to be inspected 2 is a line contact or a contact of two or more points.

Further, FIG. 4 shows a case where the object to be inspected is slanted. FIG. 4A is a conventional example, in which a gap 13 is formed between the object to be inspected 12 and the contact portion 11, and the contact is a point contact.
On the other hand, as shown in FIG. 4B, the contact portion 1 of the present invention is recessed in a mortar shape, so even if the object 2 to be inspected is slanted, it is sufficient to move the contact portion 1 up and down. It becomes possible to contact with.

The shape of the object to be inspected may be prismatic. In this case, the concave shape may be an inverted quadrangular pyramid as shown in FIG. If the contact portion of this shape is used, the contact between the object to be inspected and the contact portion becomes linear, the generation of sparks is suppressed in the axial energization method, and the composite magnetization by the alternating current of the coil method and the axial energization method The magnetic particle flaw detection inspection can be performed well.

As a method of magnetizing the object to be inspected, there is a composite magnetization by alternating current of the coil method and the axial energization method. The magnetic particle inspection can detect scratches in a direction perpendicular to the direction of the applied magnetic field. The coil method is a method of generating a magnetic field in the axial direction of the object to be inspected, and the axial energization method generates a magnetic field in the direction perpendicular to this. Furthermore, in the combined magnetization by alternating current, by synthesizing the magnetic fields by the two methods, it is possible to generate a magnetic field whose directionality rotates, and it becomes possible to detect scratches in all directions by the rotating magnetic field.

The magnetic particle inspection method is a non-destructive inspection method for detecting scratches and cracks opened on the surface of a ferromagnetic material such as a steel material. When a magnetic field is applied to a ferromagnetic material to be inspected, if there is a defect on the surface or inside of the object to be inspected that blocks the magnetic flux, magnetic poles appear at both ends of the defect and the magnetic flux leaks to the surface of the material. When a magnetic powder liquid composed of fluorescent magnetic powder to which a fluorescent substance is attached is applied, the magnetic powder is adsorbed by the leakage magnetic field corresponding to the scratched portion. Here, when ultraviolet rays are irradiated, the fluorescent substance of the magnetic powder adsorbed on the scratched portion emits light to form a fluorescent magnetic powder instruction pattern, and the scratched portion can be detected.

In the magnetic particle inspection method, first, the surface of a ferromagnetic material such as steel to be inspected is cleaned with a solvent or the like, and then dried. Next, the ferromagnet is magnetized by an electromagnet or the like. There are a continuous method in which magnetic powder is applied during magnetization and a residual method in which magnetic powder is detected after removing the magnetic field. There are two types of magnetic powder: a dry method in which magnetic powder is sprayed and sprinkled in the air, and a wet method in which water or an organic solvent is used. Sprinkle the magnetic powder with the fluorescent substance attached. There is a scratched part where the magnetic powder is sprinkled, and if there is a leaking magnetic field, the magnetic powder stays there. When irradiated with ultraviolet rays, the fluorescent substance attached to the magnetic powder emits light, and an indicated pattern of the scratched portion can be obtained. The scratched part is judged visually. Alternatively, it is imaged by an imaging device and automatically determined by a computer. Marking may be performed on the portion where a scratch is detected. In the case of automatic judgment by a computer, the scratched part can be confirmed efficiently by marking automatically.

The object to be inspected after the fluorescent magnetic particle inspection is subjected to post-treatment such as degaussing, cleaning, and rust prevention.

The electrode for a magnetic particle flaw detector of the present invention is a magnetic particle flaw detector that magnetizes an object to be inspected by using an axial energization method, in which a contact portion (electrode) with the object to be inspected has a tapered dent at a predetermined angle. It is an electrode for a magnetic particle flaw detector, which is characterized by having an attached shape. Furthermore, in a magnetic particle flaw detector that is magnetized by the combined magnetization of the coil method and the axial energization method, the contact part (contact part that is both a magnetic pole and an electrode) with the object to be inspected is made of iron and is tapered at a predetermined angle. It is an electrode for a magnetic particle flaw detector, which is characterized by having a dented shape. Further, the tapered recess is an electrode for a magnetic particle flaw detector characterized by having a mortar shape or an inverted quadrangular pyramid shape.

Next, the present invention will be specifically described with reference to examples, but these examples do not limit the present invention in any way.

(Example 1)
As Example 1 of the embodiment of the present invention, the contact portion 1 which is an electrode for an iron magnetic particle flaw detector shown in FIG. 1 was prepared. The diameter was 4 cm, the height was 1.5 cm, and the taper angle was θ = 30 degrees. The dent is mortar-shaped.
The object 2 to be inspected is a columnar iron rod having a diameter of 3 cm and a length of 35 cm. A scratch having a width of 50 μm, a length of 5 mm, and a depth of 0.3 mm was created on the object 2 to be inspected as an artificial scratch by a laser processing method. The scratches were created in the axial direction and the circumferential direction, respectively.

When the object 2 to be inspected was sandwiched between the two contact portions 1, it made linear (circular) contact in the circumferential direction. First, a magnetization test was performed by the axial energization method. An alternating current of 500 A was applied for 5 seconds. At this time, no sparks occurred. Next, a magnetization test by the coil method was performed. A magnetic field of 1 Tesla was applied in the axial direction of the object to be inspected by an external coil.

A fluorescent magnetic powder solution was applied to the object to be inspected. When irradiated with an ultraviolet black light, it was confirmed that fluorescent magnetic powder was accumulated in each of the scratches in the axial direction and the circumferential direction.

(Comparative Example 1)
As Comparative Example 1, the iron contact portion 11 shown in FIG. 3 (A) was prepared. It is a columnar and flat plate with a diameter of 4 cm and a height of 1 cm.
As the object to be inspected 12, a columnar iron rod similar to that in Example 1 was used.

When the object 12 to be inspected was sandwiched between the two contact portions 11, it was found that the gap 13 shown in FIG. 3A was formed. By the shaft energization method, when an electric current was applied, it sparked and a pseudo pattern was generated. Further, when a magnetic field was applied in the axial direction by the coil method, since the contact portion 11 was made of iron, no magnetic pole was generated at the end portion of the object to be inspected 12, but a pseudo pattern was formed due to the gap.

(Comparative Example 2)
As Comparative Example 2, a flat plate-shaped contact portion 11 having the same shape as that of Comparative Example 1 was made of copper. The object 12 to be inspected is the same as in Example 1 and Comparative Example 1.

When the object 12 to be inspected was sandwiched between the two contact portions 11, a gap 13 was formed as in Comparative Example 1. By the shaft energization method, when an electric current was applied, it sparked and a pseudo pattern was generated. Further, when a magnetic field was applied in the axial direction by the coil method, since the contact portion 11 was made of copper, a magnetic pole was generated at the end portion of the object to be inspected 12, and a pseudo pattern was formed.

(Result and summary)
As an electrode for a magnetic particle flaw detector, an iron mortar-shaped contact portion 1 was prepared as Example 1. Further, as Comparative Example 1, a flat plate-shaped contact portion 11 made of iron was prepared, and as Comparative Example 2, a flat plate-shaped contact portion 11 made of copper was prepared. As a result of performing magnetic particle flaw detection inspection by the axial energization method and the coil method using these electrodes, a magnetic field was satisfactorily applied to both of them in Example 1, and a clear magnetic particle instruction pattern was obtained. On the other hand, in Comparative Example 1, the shaft energization method sparked and a pseudo pattern was generated at the end. Further, in the coil method, since the contact portion 11 is made of iron, the end portion of the inspected object 12 does not become a magnetic pole, but since there is a gap between the contact portion 11 and the inspected object 12, a pseudo pattern is formed on the end portion. There has occurred. In Comparative Example 2, the shaft energization method sparked and a pseudo pattern was generated at the end. In the coil method, since the contact portion 11 is made of copper, the end portion of the object to be inspected 12 becomes a magnetic pole, and a pseudo pattern is generated at the end portion.

The electrode for a magnetic particle flaw detector of the present disclosure can be used for a magnetic particle flaw detection inspection by an axial energization method, a coil method, or a composite magnetization by both methods. Since the electrode is made of iron and is recessed in a mortar shape, it is particularly suitable when the object to be inspected is cylindrical. Further, for a prismatic object to be inspected, it is possible to prepare an iron electrode recessed in an inverted quadrangular pyramid shape.

1 Mortar-shaped contact part 11 Flat plate-shaped contact part 2, 12 Cylindrical object to be inspected 3 Inverted quadrangular pyramid-shaped contact part 13 Gap θ taper angle

Claims (5)

In a magnetic powder flaw detector that magnetizes the object to be inspected using the axial energization method,
An electrode for a magnetic particle flaw detector, characterized in that the contact portion with the object to be inspected has a shape in which a tapered recess is formed at a predetermined angle. In a magnetic powder flaw detector that magnetizes the object to be inspected by combined magnetization by AC or half-wave rectification by the coil method and the axial energization method.
An electrode for a magnetic particle flaw detector, characterized in that the contact portion with the object to be inspected is made of iron and has a shape having a tapered recess at a predetermined angle. The tapered recess is mortar-shaped.
The electrode for a magnetic particle flaw detector according to claim 1 or 2. The tapered recess is characterized by having an inverted quadrangular pyramid shape.
The electrode for a magnetic particle flaw detector according to claim 1 or 2. The predetermined angle is 25 degrees or more and 45 degrees or less.
The electrode for a magnetic particle flaw detector according to any one of claims 1 to 4.

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