JP5266695B2 - Method and apparatus for detecting magnetic property fluctuation site of grain-oriented electrical steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting a magnetic characteristic fluctuation portion of a magnetic material for detecting a local fluctuation portion of a magnetic characteristic, capable of reducing highly accurately a dead zone of a magnetic material edge, even if the magnetic material is moving relatively to a detection device, and a device. <P>SOLUTION: In this detection method of the magnetic characteristic fluctuation portion of the magnetic material for detecting the local fluctuation portion of the magnetic characteristic in the prescribed direction of the magnetic material by applying AC magnetic flux, the AC magnetic flux is applied to a direction orthogonal to the prescribed direction, and a magnetic field generated by interaction between the AC magnetic flux and the magnetic material is measured. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention provides a magnetic material for detecting a local variation portion of a magnetic property in a predetermined direction, for example, a moving direction or a rolling direction, when a magnetic material such as an electromagnetic steel sheet is moving relative to a detection device. The present invention relates to a method and an apparatus for detecting a magnetic characteristic fluctuation site.

  Electromagnetic characteristics such as magnetic permeability, iron loss, and electrical conductivity of metal materials, or a non-contact measurement of an amount correlated with the electromagnetic characteristics are used for various purposes. For example, in paragraph [0015] of Patent Document 1, large primary coils and secondary coils for measuring iron loss are installed in an electromagnetic steel strip production line, and steel is used by using AC magnetic flux through steel plates. An example of measuring the average iron loss in the width direction is mentioned.

  Further, in Patent Document 2, an AC magnetic flux is applied to a measurement object (steel), and a magnetic field generated by the interaction between the magnetic flux and the measurement object is measured, whereby the conductivity and permeability depend on the temperature of the measurement object. It describes how to measure change and ultimately temperature.

  There are various types of sensors for performing such measurement, and among them, a sensor having a U-shaped core is one of the common ones.

The reason why U-shaped cores are generally used is because magnetic flux flows mainly between the legs of the ferromagnetic core. (1) The range in which the magnetic flux flows can be limited to the local part of the subject. And (2) the direction in which the magnetic flux flows can be limited, and the electromagnetic characteristics in a specific direction of an anisotropic material can be measured. An application example is disclosed in Patent Document 3, for example. That is, since the magnetic properties change with carburizing, an exciting coil and a detecting coil are wound around a U-shaped ferromagnetic core, the leg is made to face the object to be measured, and the carburizing depth is obtained from the output of the sensor. Is.
Japanese Patent No. 2519615 JP-A-53-20986 JP 2004-279055 A

  For example, in the case of FIG. 6 showing a state of measurement by a magnetic sensor having a U-shaped core, a predetermined direction of the magnetic material (a direction in which magnetic characteristics are to be evaluated or a direction to be used as a reference when evaluating, For example, in the case of measuring quantitatively magnetic characteristics (iron loss, magnetic permeability, etc.) relating to the rolling direction in Fig. 6. Hereinafter, the rolling direction will be described as an example. It is necessary to apply a magnetic flux mainly in the predetermined direction (the rolling direction of the steel plate and the moving direction of the steel plate 1).

  Therefore, since the magnetic flux flows between both leg portions of the sensor 6 (here, only the core is shown and the coil portion is omitted), the both leg portions are arranged along the rolling direction so that the magnetic flux is in the rolling direction. To do. However, in this case, although the magnetic flux 11 mainly flows in the rolling direction but also expands in the width direction (see FIG. 6), when the sensor 6 approaches the vicinity of the steel plate width edge 10, the magnetic flux or eddy current is generated due to the presence of the edge. Is greatly disturbed. As a result, since the output signal of the sensor 6 is disturbed, measurement becomes difficult, and a dead zone occurs in the vicinity of the edge.

  One means for avoiding this is to reduce the range in the rolling direction in which the magnetic flux flows, and to reduce the bulge of the magnetic flux in the width direction. For this purpose, the distance between the legs of the U-shaped core sensor may be reduced. However, when targeting magnetic characteristics at a frequency lower than the relative movement speed of the steel strip relative to the sensor, it is difficult to evaluate the magnetic characteristics in the vicinity of the origin of the BH curve such as iron loss. When it is necessary to increase the size, this method has the following problems.

[Problem 1]
When it is necessary to measure magnetic characteristics at a low frequency when the sensor and the steel plate move relative to each other in the rolling direction, the alternating magnetic flux is looped in the BH curve while the sensor moves through each measurement site. It is necessary that the number of cycles for repeating the above is several cycles or more.

  For example, if the existing range of magnetic flux in the rolling direction (measurement target range) is a [m] and the relative moving speed of the steel sheet is v [m / s], the frequency of AC magnetic flux below v / a [Hz] In other words, the magnetic flux is deviated from the measurement range in the middle of the AC magnetic flux cycle (BH loop), and the magnetic characteristics of the frequency determined by the excitation frequency cannot be measured accurately. Therefore, in order to measure accurately, it is necessary to sufficiently lengthen the magnetic flux existence range (measurement target range) for a given moving speed and frequency.

  On the other hand, as already mentioned, in order to reduce the dead zone of the edge, there is a restriction that it is necessary to reduce the existing range of the magnetic flux. However, it becomes difficult in some cases.

[Problem 2]
When it is necessary to increase the amplitude of the exciting magnetic flux, it is basically necessary to (1) increase the current flowing through the exciting coil and (2) increase the number of turns of the exciting coil. With regard to the former (1), if the resistance of the coil itself is large, it is difficult for current to flow and heat is easily generated, so a coil with a large wire diameter is used.

  Further, regarding the latter (2), when the number of turns is increased, the space for winding the coil becomes large in terms of both the wire diameter and the number of turns. This generally leads to an increase in the size of the sensor, but this conflicts with the restriction that the sensor needs to be made small in order to reduce the edge dead zone, so it is necessary to select an appropriate specification that satisfies both restrictions Depending on the situation.

  The present invention has been made in view of such problems, and even when a magnetic material such as an electromagnetic steel plate is moved relative to a detection device, the edge portion of the magnetic material is highly accurate. To provide a method and an apparatus for detecting a magnetic property variation part of a magnetic material, which can detect a local variation part of a magnetic property in a predetermined direction (for example, a moving direction, a rolling direction, etc.) capable of reducing the dead zone of the magnetic material. With the goal.

The above problems are solved by the following means.
[1] A method for detecting magnetic properties change site-oriented electrical steel sheet to be detected by applying an AC magnetic flux to local variations sites of the magnetic characteristics for the rolling direction of the grain-oriented electrical steel sheet,
AC magnetic flux of the magnetic domain wall moving region is applied in a substantially perpendicular direction relative to the rolling direction, the magnetic properties of grain-oriented electrical steel sheet and measuring the magnetic field caused by the interaction of the AC magnetic flux and the grain-oriented electrical steel sheet Detection method of the fluctuation part.

[2] A method for detecting magnetic properties change site-oriented electrical steel sheet to be detected by applying an AC magnetic flux to local variations sites of the magnetic characteristics for the rolling direction of the grain-oriented electrical steel sheet,
The leg portions of the U-shaped core sensor around which the exciting coil and the detection coil are wound are arranged in a direction substantially orthogonal to the rolling direction , and the leg end portions of the core sensor are opposed to the directional electrical steel sheet . A method for detecting a magnetic property variation portion of a directional electrical steel sheet , wherein an alternating magnetic field in a domain wall motion region is applied to the directional electrical steel sheet by an excitation coil, and the generated magnetic field is measured by a detection coil.

[ 3 ] An apparatus for detecting a magnetic property variation part of a directional electromagnetic steel sheet for detecting a local variation part of the magnetic property related to the rolling direction of the grain-oriented electrical steel sheet by applying an alternating magnetic flux in the domain wall motion region,
A U-shaped core sensor around which an excitation coil and a detection coil are wound;
An AC power source for supplying an AC current of a predetermined frequency to the excitation coil;
A lock-in amplifier that amplifies the induced voltage signal detected by the detection coil; and
A signal processing device that performs signal processing on the signal amplified by the lock-in amplifier to obtain a final measurement value,
Oriented electromagnetic characterized by arranging the legs of the core sensor such that said to be aligned in a direction substantially perpendicular to the rolling direction, and the opposing leg end of the core sensor relative to oriented electrical steel sheet A device for detecting the magnetic property fluctuation part of a steel sheet

  According to the present invention, even when a magnetic material such as an electromagnetic steel plate, which has been difficult until now, moves relatively with respect to the detection device, the dead band of the width edge of the magnetic material can be reduced with high accuracy. It has become possible. In addition, this makes it possible to manage the amount of local magnetic property fluctuation in a wide range, especially in steel continuous production lines where it is necessary to manage the magnetic properties by reducing the edge dead zone. It can greatly contribute to the production of high-quality electrical steel sheets with homogeneous magnetic properties.

  In the present invention, in order to solve the above problems, the inventors have found that magnetic materials can be detected from magnetic property fluctuations in a direction orthogonal to a direction in which magnetic characteristic fluctuations are to be evaluated and a reference direction for evaluation. used. For example, in the case of a steel plate, “rolling direction magnetic property variation can be detected from width direction magnetic property variation”. Here, measuring the magnetic characteristics in the width direction means that magnetic flux is applied in the width direction, but the sensor arrangement and configuration that realizes such magnetization in the width direction conflicts with the above-mentioned problems. The present inventors have found that the situation that it is very difficult to select the specifications of a measuring device that satisfies a plurality of constraint conditions is greatly eased, and have arrived at the present invention.

  Hereinafter, the present invention will be specifically described with reference to the drawings. FIG. 3 is a diagram showing a basic configuration of a U-shaped core sensor used in the present invention. In the figure, 2 is a detection coil (secondary coil), 3 is an excitation coil (primary coil), 4 is a metal object (magnetic material), 5 is a U-shaped ferromagnetic core, 6 is a magnetic sensor, and 7 is an alternating current. A power source, 8 is a lock-in amplifier, and 9 is a signal processing device.

  First, the operation will be described with reference to FIG. Two legs of the U-shaped ferromagnetic core 5 are arranged to face the metal subject 4. A detection coil 2 and an excitation coil 3 are wound around a U-shaped ferromagnetic core 5. An alternating current having a predetermined frequency is passed through the exciting coil 3 by an alternating current power source 7, thereby generating an alternating magnetic flux. The generated AC magnetic flux mainly flows along the U-shaped ferromagnetic core 5, flows out of the core from one end of the core leg facing the metal object 4, and flows into the other core leg. Returning again, it flows along the U-shaped ferromagnetic core 5 again and becomes a loop returning to the exciting coil 3. A detection coil 2 is installed in the middle of the loop to detect an induced voltage signal due to an alternating magnetic flux.

  The induced voltage signal is amplified by the lock-in amplifier 8 and then subjected to an appropriate signal processing such as a calibration curve process corresponding to the amount finally obtained by the signal processing device 9 to obtain a measurement value as a sensor system. become. The magnetic flux that flows from one core leg to the outside of the core passes through the air and reaches the other leg. However, a certain proportion of the magnetic flux flows through the gap between the core 5 and the metal object 4 through the metal. It enters the inside of the subject 4, passes through the surface layer portion thereof, and again goes to the other core leg through the gap between the core 5 and the metal subject 4.

  When the AC magnetic flux passes through the inside (surface layer portion) of the metal specimen 4, it is affected by the electromagnetic characteristics (permeability, conductivity, shape, loss, etc.) of the metal specimen 4 due to the eddy current effect and the like. The amplitude, phase, and waveform of the AC magnetic flux change. By detecting this change, it is possible to obtain various quantities (crystal grain size, temperature, etc.) correlated with the electromagnetic characteristics of the metal specimen 4, and thus the electromagnetic characteristics, using a calibration curve or the like.

  Next, taking an electromagnetic steel sheet as an example, an example in which a magnetic property variation part in the rolling direction of the steel plate has a correlation with a width direction magnetic property variation will be described. The magnetic properties of the steel sheet are affected by crystal grains, magnetic domain size, crystal grain orientation, components, precipitates, strain, and the like.

  In the case where the magnetic characteristics change due to some circumstances with respect to the rolling direction, some fluctuations may also occur with respect to the width direction magnetic characteristics in view of the properties of the influence parameters listed above.

  FIG. 2 is a diagram showing an example in which the rolling direction magnetic property fluctuation in the grain-oriented electrical steel sheet affects the width direction magnetic property. Of the two plots, the white squares indicate the magnetic properties in the width direction when the magnetic properties in the rolling direction are normal, and the other black circles indicate that the magnetic properties in the rolling direction vary from the normal levels. The magnetic characteristics in the width direction are shown in the region where

  Although it can be seen that there is a difference between the two as a whole, it can be seen that there is a large difference especially in the range where H is 300 [A / m] or less. By utilizing such a correlation, it is possible to know the fluctuation part of the magnetic property in the rolling direction by measuring the magnetic property in the width direction. In general, the so-called domain wall motion region is preferable for the width direction excitation, and in the example of FIG. 2, 50 to 300 [A / m] is desirable.

  Next, how to measure a plurality of conflicting constraints existing in the case of magnetization in the rolling direction when the magnetic properties in the width direction are measured will be described.

  Measuring magnetic characteristics in the width direction means applying magnetic flux in the width direction, which means that when using a sensor with a U-shaped core, both legs are arranged side by side in the width direction. means. FIG. 1 is a diagram showing the positional relationship between a U-shaped core and a steel strip according to the present invention.

  Similar to the case where the legs of the U-shaped core are arranged in the rolling direction, the magnetic flux flowing between the legs of the U-shaped core flows mainly in the direction of alignment of the legs, but is still perpendicular to the direction of alignment of the legs. Ingredients exist.

  However, in such an arrangement in which both legs are arranged in the width direction, the size in the rolling direction of the core and the bulging range of the “bulging component” are not so much related, and the “bulging component” is not in the width edge direction. Since it does not swell, it is not directly related to the size of the edge dead zone. Therefore, the strong correlation between the constraint condition determined from the excitation frequency and the moving speed of the steel strip and the edge dead zone shown in Problem 1 of [Problem to be Solved by the Invention] can be eliminated.

  In addition, since there is no direct relationship between the “bulging component” itself and the edge dead zone, it is possible to eliminate the strong correlation between the increase in the size of the sensor when strongly excited and the “bulging” range, which has been raised to Problem 2.

  In addition, although the said description demonstrated the grain-oriented electrical steel plate as a measuring object, it is not limited to it, If it is a magnetic material, it can measure similarly. Moreover, although the example which measures the magnetic characteristic with respect to a rolling direction was demonstrated, it is not limited to a rolling direction in particular, When a magnetic material moves, it is good also as a moving direction and is applicable to the direction which wants to evaluate a magnetic characteristic. .

  In the production line of grain-oriented electrical steel sheets (line passing speed 1m / s), due to local abnormalities in the crystal direction, the distribution in the width direction of the parts that are worse than the standard values in terms of electromagnetic quality such as permeability and iron loss. An example in which is measured over the entire length of a steel strip having a width of 1000 mm will be described below.

  FIG. 4 is a diagram showing the positional relationship between the U-shaped core and the steel strip in the present embodiment. The magnetic sensor 6 is arranged in an array in the width direction of the steel strip 1 in order to measure the abnormal portion distribution in the entire width direction.

  Each sensor had a leg size of 20 mm and a rolling direction size of 100 mm. The distance between the steel strip and the lower surface of the sensor (lift-off) was 5 mm, and the excitation frequency was 50 Hz. At that time, a two-row staggered arrangement was adopted so that there were no sites that could not be measured in the width direction. The distance in the rolling direction between sensors placed in different rows and close to each other was set to 100 mm so as not to interfere. The output of the detection coil of the sensor is connected to a lock-in amplifier and subjected to synchronous detection. Using the lock-in amplifier output, it was determined whether the site was healthy or abnormal based on a predetermined threshold value.

  FIG. 5 is a diagram illustrating an example of a measurement result in the present example. From the figure, it can be seen that the edge dead zone is also small (20 mm or less), and the abnormal part width direction distribution is measured. In this example, the same sensor specifications were used. However, if there is a part where detailed (high spatial resolution) detection is desired, specifications such as partially reducing the size between the legs (size) Measurement conditions) may be changed. In the present embodiment, the case where the wire is moving at a line passing speed of 1 m / s is described. However, the present invention is naturally applicable even when the steel strip is stopped.

It is a figure which shows the positional relationship of the U-shaped core which concerns on this invention, and a steel strip. It is a figure which shows the example in which the rolling direction magnetic characteristic fluctuation | variation in a grain-oriented electrical steel sheet affects the width direction magnetic characteristic. It is a figure which shows the basic composition of the U-shaped core sensor used by this invention. It is a figure which shows the positional relationship of the U-shaped core and steel strip in a present Example. It is a figure which shows an example of the measurement result in a present Example. It is a figure which shows typically a mode that it measures with a sensor with a U-shaped core.

Explanation of symbols

1 Electrical steel sheet (steel strip)
2 Detection coil (secondary coil)
3 Excitation coil (primary coil)
DESCRIPTION OF SYMBOLS 4 Metal object 5 U-shaped ferromagnetic core 6 Magnetic sensor 7 AC power supply 8 Lock-in amplifier 9 Signal processing device 10 Steel strip width direction edge 11 Magnetic flux

Claims (3)

A method for detecting a magnetic property variation part of a grain- oriented electrical steel sheet by detecting a local variation part of a magnetic property related to a rolling direction of the grain-oriented electrical steel sheet by applying an alternating magnetic flux,
AC magnetic flux of the magnetic domain wall moving region is applied in a substantially perpendicular direction relative to the rolling direction, the magnetic properties of grain-oriented electrical steel sheet and measuring the magnetic field caused by the interaction of the AC magnetic flux and the grain-oriented electrical steel sheet Detection method of the fluctuation part. A method for detecting a magnetic property variation part of a grain- oriented electrical steel sheet by detecting a local variation part of a magnetic property related to a rolling direction of the grain-oriented electrical steel sheet by applying an alternating magnetic flux,
The leg portions of the U-shaped core sensor around which the exciting coil and the detection coil are wound are arranged in a direction substantially orthogonal to the rolling direction , and the leg end portions of the core sensor are opposed to the directional electrical steel sheet . A method for detecting a magnetic property variation portion of a directional electrical steel sheet , wherein an alternating magnetic field in a domain wall motion region is applied to the directional electrical steel sheet by an excitation coil, and the generated magnetic field is measured by a detection coil. An apparatus for detecting a magnetic property variation part of a grain- oriented electrical steel sheet for detecting a local variation part of a magnetic property related to a rolling direction of the grain-oriented electrical steel sheet by applying an alternating magnetic flux in a domain wall moving region,
A U-shaped core sensor around which an excitation coil and a detection coil are wound;
An AC power source for supplying an AC current of a predetermined frequency to the excitation coil;
A lock-in amplifier that amplifies the induced voltage signal detected by the detection coil; and
A signal processing device that performs signal processing on the signal amplified by the lock-in amplifier to obtain a final measurement value,
Oriented electromagnetic characterized by arranging the legs of the core sensor such that said to be aligned in a direction substantially perpendicular to the rolling direction, and the opposing leg end of the core sensor relative to oriented electrical steel sheet A device for detecting the magnetic property fluctuation part of a steel sheet .

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