JPH045005Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an auxiliary yoke that is detachably attached to the end face of a magnetic pole of an interpolar magnetic particle flaw detector.

Conventional technology and its problems In pole-to-pole magnetic particle inspection, the ends of both magnetic poles of an electromagnet are brought into contact with the object to be inspected, and magnetic flux is directly applied to the object to be inspected from both magnetic poles to magnetize it. This method detects defects on and near the surface of ferromagnetic materials by observing the indicator pattern (magnetic particle pattern) of magnetic particles scattered on the surface of the material, and is often used in non-destructive inspection of welded parts of large structures. has been done. When performing pole-to-pole magnetic particle flaw detection, the strength of the magnetic field in the flaw detection section is important, and the degree of closeness between the magnetic poles and the object to be inspected becomes an issue. If the degree of adhesion between the magnetic poles and the object to be inspected is poor, a gap will be created between them, and as this gap increases, the magnetic flux acting on the magnetic poles will increase, and the magnetic flux applied to the object to be inspected will decrease. As a result, the magnetic field in the flaw detection section becomes weak, making proper inspection impossible.

FIGS. 4 and 5 show an example of a conventional interpolar magnetic particle flaw detector 1. FIG. 2 is a U-shaped magnetic pole core constituting the electromagnet, and 3 is its magnetizing coil. iron core 2
is mounted inside a U-shaped plastic case 4, with magnetic poles 5 at both ends protruding outside the end surface of the case 4. 6 is a power cable, 7 is a switch box, and 8 is a magnetization energization switch.

As shown in detail in FIG. 6, the end surface 5a of the magnetic pole 5
A first hole 9 is formed in the side surface 5b, and a first hole 9 is formed in the first side surface 5b.
A second hole 10 is formed that reaches the middle of the hole 9. Further, a screw hole 11 penetrating through the side surface 4a of the case 4 is formed in the form of an extension of the second hole 10, and a butterfly screw 12 is screwed into the screw hole 11 from the outside. As a result, a triangular yoke 13 or a universal yoke (not shown) is detachably attached to the end surface 5a of the magnetic pole 5 as an auxiliary yoke. A mounting rod 14 is screwed and fixed to the mounting surface 13a of the triangular yoke 13, and by inserting this rod 14 into the first hole 9 of the magnetic pole 5 and tightening it with the thumbscrew 12, the triangular yoke 13 is attached to the magnetic pole. 5 is fixed to the end surface 5a of 5. The universal yoke is also installed in a similar manner.

Figure 2 shows a steel main pipe 15 and a plurality of steel branch pipes 16a, 16b, 16 that are subject to interpolar magnetic particle inspection.
Welding part 1 of c, 16d, 16e, 16f, 16g
7, and FIG. 3 shows a part of it in detail. In this case, since the surface of each pipe 15, 16a to 16g is a curved surface, the intersection angle between the main pipe 15 and the branch pipes 16a to 16g is not constant and changes depending on the location.

When such a welded portion 17 is inspected using the flaw detector 1 described above, a triangular yoke 13 or a universal yoke is attached to the end face of the magnetic pole 5. When using the triangular yoke 13, if it is fixed to the magnetic pole 5, the yoke 13 can only be brought into close contact with the object to be inspected at a specific crossing angle. For this reason, it is necessary to rotate the yoke 13 to change the orientation each time the intersection angle of the object to be inspected changes, but each time, the thumbscrew 12 must be loosened and tightened again, making the operation very troublesome and Efficiency decreases. When using a universal yoke, by changing the angle of the universal joint part, it is possible to increase the degree of adhesion even if the intersection angle changes, but magnetic flux leaks at the universal joint part and is thrown into the object to be inspected. There is a problem that the magnetic flux decreases.

The purpose of this invention was to solve the above problems by creating a pole-to-pole type magnetic particle flaw detector that can always apply a strong magnetic field to the flaw detection area even when the intersection angle of the object to be inspected changes, and that is extremely easy to operate. The aim is to provide an auxiliary yoke.

Means for Solving the Problem The auxiliary yoke of the pole-to-pole type magnetic particle flaw detector according to this invention is an auxiliary yoke that is detachably attached to the end face of the magnetic pole of the pole-to-pole type magnetic particle flaw detector. Two inclined surfaces with different angles are formed between the surface and the flat surfaces at both ends perpendicular to these, and are rotatably attached to the end surface of the magnetic pole and pressed against the end surface of the magnetic pole by a spring. It is something that exists.

Embodiment FIG. 1 shows an auxiliary yoke 21 attached to an interpolar magnetic particle flaw detector 20.

A screw hole 2 is provided in the end surface 5a of the magnetic pole 5 of the flaw detector 20.
2 is formed. The remaining parts of the flaw detector 20 are the same as those of the flaw detector 1 described above, and the same parts are given the same reference numerals.

A bolt 23 is screwed into the screw hole 22 of the magnetic pole 5, and a cylindrical spacer 24 and a spring receiver 25 are interposed between the head 23a of the bolt 23 and the end surface 5a of the magnetic pole 5 from the magnetic pole 5 side. It is being A mounting surface 21 is provided between the mounting surface 21a of the auxiliary yoke 21 to the magnetic pole 5 and a flat surface 21b on the opposite side parallel to this.
A stepped hole 26 is formed which is narrower on the a side. The inner diameter of the small diameter portion 26a on the mounting surface 21a side of the stepped hole 26 is slightly larger than the outer diameter of the spacer 24, and the length thereof is shorter than the length of the spacer 24. Flat surface 21 of stepped hole 26
The inner diameter of the large diameter portion 26b on the b side is slightly larger than the outer diameter of the spring receiver 25. The small diameter portion 26a is slidably fitted on the outside of the spacer 24, and the head 23a of the bolt 23 is completely buried within the large diameter portion 26b. In addition, the stepped portion 26c of the stepped hole 26 and the spring receiver 2
A coil spring 27 is attached between the yoke 21 and the magnetic pole 5 to urge the yoke 21 toward the magnetic pole 5, so that a part of the mounting surface 21a is pressed against the end surface 5a of the magnetic pole 5, and the yoke 21 is fixed. . Flat surface 21b of yoke 21 and flat surfaces 21 at both ends perpendicular to this
c, 21d, two inclined surfaces 21e, 21
f is formed. These inclined surfaces 21e, 2
The angles formed by 1f and the flat surface 21b are different from each other,
For example, one inclined surface 21e has an angle of 45°, and the other inclined surface 21f has an angle of 30°. The remaining two surfaces not shown in FIG. 1 are flat surfaces that are perpendicular to the mounting surface 21a and the flat surfaces 21b, 21c, and 21d.

When inspecting the welded part 17 as described above with the flaw detector 20, as shown in FIG. 21e,2
1f is brought into close contact with the object to be inspected. At this time, you can easily rotate the yoke 21 by holding it in your hand.
is fixed to the magnetic pole 5 by a spring 27. Therefore, operation is extremely simple and inspection efficiency is improved.

It is also possible to inspect a portion other than the welded portion 17 as described above, such as a flat plate butt welded portion, with the auxiliary yoke 21 attached. In this way, since the magnetic pole 5 does not come into direct contact with the object to be inspected, wear and deformation are eliminated, and the flaw detector 2
The lifespan of will be extended.

Effects of the invention According to the auxiliary yoke of this invention, two inclined surfaces with different angles are formed between the flat surface parallel to the end surface of the magnetic pole and the flat surfaces at both ends perpendicular to this, and the end surface of the magnetic pole can freely rotate. Since the auxiliary yoke is attached to the object to be inspected, even if the intersection angle of the object to be inspected changes, the auxiliary yoke can always be brought into close contact with the object to be inspected, and the leakage magnetic field from this part can be reduced. Since the yoke is pressed against the end face of the magnetic pole by a spring and there is no part where magnetic flux leaks unlike the conventional universal yoke, a strong magnetic field can be applied to the flaw detection section. Also, since it is pressed against the end face of the magnetic pole by the spring,
This can be rotated with a simple operation, improving inspection efficiency. Furthermore, by attaching an auxiliary yoke, the magnetic poles do not come into direct contact with the object to be inspected, eliminating wear and deformation, and extending the life of the flaw detector.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the auxiliary yoke of an interpolar magnetic particle flaw detector showing an embodiment of this invention, Fig. 2 is a perspective view showing the welded parts of the main pipe and multiple branch pipes, and Fig. 3 is the
A perspective view showing the state of use by enlarging a part of the figure, No. 4
The figure is a side view showing an example of a conventional magnetic particle flaw detector, FIG. 5 is a side view taken along the line shown in FIG. 4, and FIG. 6 is a partially cutaway side view showing a conventional auxiliary yoke. 5... Magnetic pole, 5a... End face, 20... Interpolar magnetic particle flaw detector, 21... Auxiliary yoke, 21b, 21
c, 21d...flat surface, 21e, 21f...slanted surface, 27...spring.

Claims (1)

[Scope of utility model registration request] It is an auxiliary yoke that is detachably attached to the end face of the magnetic pole of a magnetic particle flaw detector, and has two inclined surfaces with different angles between a flat face parallel to the end face of the magnetic pole and flat faces at both ends perpendicular to this. is formed,
An auxiliary yoke for an interpolar magnetic particle flaw detector that is rotatably attached to the end face of a magnetic pole and is pressed against the end face of the magnetic pole by a spring.