JPH063330A - Magnetizing device for magnetic particle inspection - Google Patents

Abstract

PURPOSE:To suppress the excessive heat generation of an interpole magnetizing coil so that the title device can continuously perform sensitive measurement for a long time by providing a repulsing coil which generates magnetic fluxes in the direction opposite to that of leakage magnetic fluxes between two magnetic poles of the interpole magnetizing coil between the two magnetic poles. CONSTITUTION:A repulsing coil 10 is provided between two magnetic poles 2A and 2B of an interpole magnetizing coil 2. The coil 10 is constituted by connecting windings 2a and 2b in series to each other in the opposite directions so that the direction of magnetic fluxes 11 generated by the coil 10 can become opposite to the direction of leakage magnetic fluxes 9 between the magnetic poles 2A and 2B of the coil 2. Therefore, the heat generation caused by the interlinkage between the magnetic fluxes 9 and coils 2a and 2b can be prevented by reducing the amount of magnetic fluxes 9 between the poles 2a and 2B by using the magnetic fluxes 11 generated by the coil 10. In addition, since the reduced amount of the magnetic fluxes 9 is added to magnetic fluxes 8 which magnetize the upper side face 2 of a bar steel material 1, both side faces of the material 1 can be inspected for flaws with high sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetizing device for magnetic particle flaw detection for detecting surface flaws of a steel material (for example, square billet) in a running state.

[0002]

2. Description of the Related Art There is an interpole method as a magnetization direction in which surface flaws (for example, seam-shaped flaws) extending in the longitudinal direction (axial direction) of a steel material are subjected to magnetic particle flaw detection in the running state of the steel material. FIG. 5 is an example of a magnetizing device for magnetic particle flaw detection by the inter-pole method, in which 1 is an upper side 2 while being moved in the axial direction by a conveying roller.
A bar steel material having a square cross section whose surface is flaw-detected, 2 is an inter-electrode magnetizing coil that magnetizes the bar steel material 1 in a horizontal direction that is perpendicular to the axial direction of the bar steel material 1, 3 is a magnetic powder sprayer, 4 is a magnetic powder liquid, 5 Is a conveying V roller for moving the bar steel 1, and 6 is a traveling direction of the bar steel 1.

This magnetizing apparatus for magnetic particle flaw detection is intended to simultaneously detect the upper two side surfaces of the steel strip 1 having a square cross section during conveyance, and the surface flaws in the axial direction of the steel strip 1 are stripped by the interpolar magnetizing coil 2. It is detected by an alternating magnetic flux perpendicular to the steel material direction.

Further, there is a magnetizing device for magnetic particle flaw detection disclosed in Japanese Patent Application Laid-Open No. 2-42353 for the purpose of improving flaw detection performance at both lateral corners of a steel bar. As shown in FIG. 6, this is a semi-conductive material that covers two side surfaces of the steel strip 1 to be flaw-detected and is close to the three corners of the steel strip 1 connected to the two side surfaces. It is characterized in that a cylinder 7 is provided.

As a result, each corner of the steel strip 1 is covered with the semi-cylinder 7, which is a conductor having an area in a plane perpendicular to the line connecting the center of the cross section of the steel strip 1 and the corner. Half cylinder 7
The alternating magnetic flux in the direction of the line connecting the cross-sectional center and the corner of the steel strip 1 is canceled by the eddy current generated at. Thus
Since the alternating magnetic flux component in the direction perpendicular to the corner surface is suppressed, excessive magnetic powder adsorption at the corner is eliminated, and flaw detection performance can be improved.

[0006]

However, the above magnetizing device for magnetic particle flaw detection has the following problems. That is, in order to detect a surface flaw having a shallow depth and a short length, it is necessary to increase the magnetizing force of the inter-electrode magnetizing coil to increase the leakage flux from the surface flaw. When it is increased, the heat generated by the inter-electrode magnetizing coil is increased, and flaw detection cannot be performed continuously.

The present invention is intended to solve the above problems, and obtains a magnetizing device for magnetic particle flaw detection, which suppresses excessive heat generation of the magnetizing coil between poles and is capable of conducting flaw detection continuously for a long time with high sensitivity. The purpose is to

[0008]

A magnetizing device for magnetic particle flaw detection according to the present invention has a structure in which two adjacent square bar steel members are provided by a magnet coil between poles.
In a magnetizing device for magnetic particle flaw detection, in which a surface is magnetized in the width direction at the same time to detect a surface flaw, a direction opposite to a direction of a leakage magnetic flux which is short-circuited between two magnetic poles of the inter-pole magnetizing coil. It is characterized in that a coil (hereinafter, referred to as a repulsion coil) for generating the magnetic flux is provided.

[0009]

[Operation] The heat generation of the inter-pole magnetizing coil is considered to be due to the hysteresis loss of the magnetic flux in the magnetic poles and the interlinkage of the leakage magnetic flux between the magnetic poles with the excitation winding. Will also increase. FIG. 7 is a diagram showing the state of heat generation due to the leakage magnetic flux. In addition to the magnetic flux 8 directed to the upper two surfaces of the steel strip 1 to be flaw-detected, the leakage magnetic flux 9 is also present between the two magnetic poles 2A and 2B of the inter-pole magnetizing coil 2. The magnetic flux 9 passes through the windings 2a and 2b respectively wound around the magnetic poles 2A and 2B to generate heat. In particular, the winding portion 2a 'close to the ends of the magnetic poles 2A and 2B. , 2b 'has large heat generation.

On the other hand, the magnetic poles 2A and 2B of the inter-pole magnetizing coil 2
If the distance between the magnetic poles is increased, the magnetic resistance between the magnetic poles is increased, and the above-mentioned magnetic flux leakage between magnetic poles and the heat generation due to the interlinkage of the winding can be prevented. Since it is not possible to do so, the detection performance deteriorates. That is, the magnetic flux perpendicular to the surface is larger than the magnetic flux parallel to the surface effective for flaw detection on the upper two surfaces of the steel strip 1, and the magnetic powder is excessively adsorbed on the surface of the steel strip 1, so that the surface flaw is sensitively detected. It cannot be detected.

In the present invention, a rectangular or ring-shaped repulsion coil whose winding length direction is wound between the magnetic poles is provided between the two magnetic poles of the inter-pole magnetizing coil, and the leakage magnetic flux between the magnetic poles is repulsed. Reduce the magnetic flux generated by the coil,
By preventing the heat generation of the magnetizing coil due to the interlinkage of the leakage magnetic flux to the magnetic pole winding, and by further effectively reducing the leakage magnetic flux between the magnetic poles on the two sides of the bar steel to be flaw-detected, the detection performance can be improved. We are trying to improve.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a magnetizing device for magnetic particle flaw detection according to the present invention, and 10 is two magnetic poles 2 of an inter-pole magnetizing coil 2.
It is a repulsion coil provided between A and 2B. The repulsion coil 10 is provided in the middle of the magnetic poles 2A and 2B of the inter-pole magnetizing coil 2, and the winding direction is the windings 2a and 2 of the magnetic poles 2A and 2B.
The winding length direction is perpendicular to b, the winding length direction is between the magnetic poles 2A and 2B, and the number of turns is about one half of the windings 2a and 2b.
The size of the repulsion coil 10 in the height direction is determined by the magnetic poles 2A and 2B.
The size in the direction between the magnetic poles 2A and 2B from the upper end to about the middle of the height of the magnetic pole 2 is about half the distance between the magnetic poles.

As shown in FIG. 2, the repulsion coil 10 is connected in series with the windings 2a and 2b, and the winding direction of the repulsion coil is opposite to that of the windings 2a and 2b.
The direction of the magnetic flux 9 leaking between A and 2B is opposite to the direction of the magnetic flux 11 generated by the repulsion coil 10.

As a result, the magnetic pole 2 of the inter-pole magnetizing coil 2
The magnetic flux 9 leaking between A and 2B is reduced by the magnetic flux 11 generated by the repulsion coil 10, and the winding 2 of the leakage magnetic flux 9 is reduced.
It is possible to prevent heat generation due to interlinkage to a and 2b.
Further, since the decrease of the magnetic flux 9 leaking between the magnetic poles 2A and 2B is added to the magnetic flux 8 that magnetizes the upper two side surfaces of the steel strip 1,
The upper two side surfaces of the steel strip 1 can be detected with high sensitivity.

FIG. 3 shows the effect of preventing heat generation of the magnetizing device of the present invention in comparison with the conventional magnetizing device. In the magnetizing device, the portion that generates a large amount of heat is the A portion, but the magnetization intensity is 2
The heat generation of the part A of the magnetizing device of the present invention at about 10,000 AT is reduced by about 30% as compared with the part A of the conventional magnetizing device, which shows a great effect. Generally, the temperature of the magnetizing device can be used within about 80 ° C., and the magnetizing device of the present invention enables continuous flaw detection.

FIG. 4 shows the effect of the magnetizing device of the present invention for improving the magnetizing force of a steel strip, in comparison with a conventional magnetizing device.
The magnetizing device of the present invention has a magnetic field of about 3 as compared with the conventional magnetizing device.
The magnetizing force can be improved by 0%, which can lead to the sophistication of surface flaw inspection. As a countermeasure against heat generation by the magnetizing device for magnetic particle flaw detection, it is needless to say that external cooling with air or the like is also used as needed.

[0017]

As described above, according to the present invention, since it is possible to prevent the magnetizing device for magnetic particle flaw detection from generating heat and improve the magnetizing force, it is possible to realize high-performance flaw detection of a bar steel continuously for a long period of time, which is industrially possible. It is extremely beneficial.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a magnetizing device for magnetic particle flaw detection according to the present invention.

FIG. 2 is a diagram showing a winding connection in the present invention.

FIG. 3 is a diagram showing an effect by the implementation of the present invention, and a diagram showing a heat generation prevention state of the magnetizing device.

FIG. 4 is a diagram showing an exciting magnetizing force of a steel strip.

FIG. 5 is a view showing a conventional magnetizing device for magnetic particle flaw detection, showing a general magnetizing device by a gap method.

FIG. 6 is a diagram showing a conventional magnetizing device with improved detection performance for lateral corner portions of a steel bar material.

FIG. 7 is a diagram showing the principle of heat generation of the magnetizing device.

[Explanation of symbols]

 1-steel material 2A, 2B Magnetic poles 2a, 2b Winding 3 Magnetic powder liquid disperser 4 Magnetic powder liquid 5 V roller for transportation 6 Travel direction of 6-steel material 7 Semi-cylinder 8 Magnetic flux for magnetizing upper 2 surfaces of 8-steel material 9 Magnetic flux leakage between magnetic pole 10 Repulsion coil 11 Magnetic flux generated by repulsion coil

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryoetsu Yamada 12 Nakamachi, Muroran City, Hokkaido Nittetsu Hokkaido Control System Co., Ltd. (72) Inventor Shigeyuki Nitta 12 Nakamachi, Muroran City, Hokkaido Nittatsu Hokkaido Control System Co., Ltd.

Claims (1)

[Claims] 1. A magnetizing device for magnetic particle flaw detection in which two adjacent surfaces of a rectangular steel strip are magnetized in the width direction at the same time by an interpolar magnetizing coil to detect surface flaws, and between the two magnetic poles of the interpolar magnetizing coil. 1. A magnetizing device for magnetic particle flaw detection, further comprising: a coil for generating a magnetic flux in a direction opposite to a direction of a leakage magnetic flux generated between the magnetic poles in a short circuit.