JP2019148424A - Steel sheet magnetic transformation rate measuring device - Google Patents

Abstract

To provide a steel sheet magnetic transformation rate measuring device suitable for measuring the magnetic transformation rate of a steel sheet in an annealing furnace.SOLUTION: A steel sheet magnetic transformation rate measuring device for measuring a magnetic transformation rate of a steel sheet in an annealing furnace, includes: a drive coil that emits radio waves by means of an alternating electrical signal passed through the coil; and a reception coil that receives radio waves emitted by the drive coil and reflected by the steel sheet. The drive coil is constituted of an air-core coil having a path traversing the steel sheet in the width direction, and is arranged so that the normal line of a coil surface of the drive coil is along the longitudinal direction of the steel sheet. The reception coil is constituted of an air-core coil, and a coil surface of the reception coil is arranged along the steel sheet surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for measuring the magnetic transformation rate of a steel plate in an annealing furnace, and more particularly to an apparatus for measuring the magnetic transformation rate of a steel plate in a continuous annealing furnace.

  In order to make a steel plate have high strength and high workability, cooling is performed in a state where the structure of the steel plate is in a specific austenite phase (γ phase) and ferrite phase (α phase) ratio. It is useful to grasp the ratio of each phase at the cooling start point in order to appropriately build the characteristics of the steel sheet. As a method for grasping the ratio of each phase, a method using a magnetic detector, that is, a device for measuring a magnetic transformation rate (magnetic transformation rate measuring device) is known (Patent Documents 1 and 2). The magnetic transformation rate measuring device is composed of a drive coil that generates a magnetic field and a detection coil that measures the magnetic field transmitted through the steel plate (Patent Document 1) or a detection coil that measures the magnetic field reflected by the steel plate (Patent Document 2). Yes.

JP-A-56-82443 JP 59-188508 A

  Measuring the phase ratio of the steel, that is, the transformation rate, is beneficial in hot rolling as described in the prior art, and is also important in the annealing process of high-strength cold-rolled steel sheets. Even in such an annealing process, it is considered that the same method as the conventional technique can be applied as a method for measuring the transformation rate.

  However, in the method as disclosed in Patent Document 1, an exciting coil wound around a magnetic pole composed of a U-shaped iron core and a magnetic flux detector are arranged with a steel plate interposed therebetween, and the exciting coil and the magnetic flux detector There was a problem that the distance had to be reduced. Therefore, when applying the method as disclosed in Patent Document 1 to a steel plate in an annealing furnace, an excitation coil and a detector in the vicinity of the steel plate in an annealing furnace that performs annealing at a high temperature up to about 900 ° C. Therefore, it is difficult to stably install the measuring apparatus in the furnace over a long period of time.

  Also, when the steel sheet is transported many times in the vertical direction by a transport roll like a vertical annealing furnace, the measuring device is placed in the middle of the furnace height in order to reduce the magnetic influence of the transport roll. In order to support a measuring device having a heavy iron core in a high-temperature furnace, a method such as Patent Document 2 requires a member having a large cross-sectional area, and heating and cooling of the annealing furnace is required. In addition to hindering, it is necessary to install a measuring device in an annealing furnace that performs annealing at a high temperature, and it is necessary to cool the device, and it is difficult to stably install the measuring device in the furnace for a long period of time. there were.

  In addition, since any of the above measuring devices is small, a partial transformation rate in the width direction of the steel plate is measured, and the transformation rate over the entire width of the steel plate is not measured. And in order to measure the transformation rate over the entire width of the steel sheet using the above measuring device, it is necessary to install a large number of measuring devices side by side in the plate width direction. However, it was impossible because it was heavy and difficult to fix.

This invention is made | formed in view of the said situation, and it aims at providing the magnetic transformation rate measuring apparatus of the steel plate suitable for measuring the magnetic transformation rate of the steel plate in an annealing furnace.
Hereinafter, the steel sheet magnetic transformation rate measuring device of the present invention is also simply referred to as “magnetic transformation rate measuring device”.

  In order to solve the above-mentioned problems, the present invention is configured such that a drive coil having a path traversing the steel sheet in the width direction is formed of an air-core coil, and the normal line of the coil surface (circular surface) is along the longitudinal direction of the steel sheet The receiving coil is made of an air-core coil, and the receiving coil is made of a steel plate so that the receiving coil can receive radio waves reflected by the steel plate by emitting an electric wave by an AC electric signal flowing through the driving coil. It is arranged along the surface. In the present specification, the “steel plate surface” means a surface including the plate width and the longitudinal direction (that is, a surface that is not a side surface) in the steel plate surface.

  In the above configuration, the drive coil preferably has a substantially rectangular circuit path. Moreover, it is preferable to arrange | position a drive coil and a receiving coil apart from the length of the short side of a drive coil.

  In the above configuration, the receiving coil is preferably arranged on the traveling direction side of the steel sheet or on the opposite side of the traveling direction with reference to a line segment connecting the centers of the two short sides of the driving coil.

  In the above configuration, the receiving coil is preferably arranged in the vicinity of the steel plate.

  Further, the distance between the receiving coil and the steel plate should be within 100 mm, and the drive coil should preferably be such that the signal of the receiving coil becomes small in a specific reference state such as a state where there is no steel plate or a non-magnetic steel plate. You may arrange | position with an inclination angle so that a signal may become zero.

  Moreover, in the said structure, it is preferable that a receiving coil is movable to the board width direction of a steel plate. A plurality of receiving coils may be arranged in the plate width direction of the steel plate so that the magnetic transformation rate distribution in the plate width direction can be measured.

  In the above configuration, the signal of the receiving coil can be separated into phase components, and the electrical resistivity can be measured together with the magnetic transformation rate of the steel sheet.

That is, the present invention has the following configuration.
[1] A steel sheet magnetic transformation rate measuring device for measuring a magnetic transformation rate of a steel plate in an annealing furnace,
A drive coil that emits radio waves by an alternating electrical signal flowing through the coil;
A receiving coil for receiving a radio wave reflected by a steel plate, the radio wave emitted by the drive coil; and
The drive coil is composed of an air-core coil having a path that crosses the steel plate in the width direction, and the normal line of the coil surface of the drive coil is arranged along the longitudinal direction of the steel plate,
An apparatus for measuring a magnetic transformation rate of a steel sheet, wherein the receiving coil is constituted by an air-core coil, and the coil surface of the receiving coil is arranged along the steel sheet surface.
[2] The steel sheet magnetic transformation rate measuring apparatus according to [1], wherein the drive coil has a substantially rectangular circuit path.
[3] The steel sheet magnetic transformation rate measuring apparatus according to [2], wherein the receiving coil and the driving coil are arranged apart from each other by a length of a short side of the driving coil.
[4] The receiving coil is arranged on the traveling direction side of the steel sheet or on the opposite side of the traveling direction with reference to a line segment connecting the centers of the two short sides of the driving coil, [2] or [3 ] The magnetic transformation rate measuring apparatus of the steel plate as described in any one of Claims 1-3.
[5] The steel sheet magnetic transformation rate measuring apparatus according to any one of [1] to [4], wherein the distance between the receiving coil and the steel sheet is within 100 mm.
[6] The distance between the receiving coil and the steel plate is within 100 mm,
The receiving coil is arranged such that the coil surface of the driving coil is inclined with respect to the vertical surface of the steel plate so that a signal other than the radio wave reflected by the steel plate received by the receiving coil becomes small. 1]-[5] The steel sheet magnetic transformation rate measuring device.
[7] The steel sheet magnetic transformation rate measuring device according to any one of [1] to [6], wherein the receiving coil is movable in a plate width direction of the steel plate.
[8] The steel sheet magnetic transformation rate measuring device according to any one of [1] to [7], wherein a plurality of receiving coils are arranged in a plate width direction of the steel plate.
[9] The magnetic transformation rate measurement of the steel sheet according to any one of [1] to [8], wherein the driving coil and the receiving coil are arranged at a midway position in the height direction of the vertical annealing furnace. apparatus.
[10] The steel sheet according to any one of [1] to [9], wherein the magnetic transformation rate of the steel sheet is measured by comparing a signal received by the receiving coil with a reference signal measured in advance. Magnetic transformation rate measuring device.
[11] The magnetic field of the steel sheet according to any one of [1] to [10], wherein the signal received by the receiving coil is separated into phase components and the electrical resistivity is measured together with the magnetic transformation rate of the steel sheet. Transformation rate measuring device.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic fluctuation rate measuring apparatus of the steel plate suitable for measuring the magnetic fluctuation rate of the steel plate in an annealing furnace can be provided.

  In the present invention, in order to easily measure the magnetic transformation rate of the steel sheet in the annealing furnace, the driving coil (excitation coil) and the receiving coil are air-core coils that do not use an iron core, and the driving coil extends in the width direction of the steel sheet. Since the crossing path is provided, the magnetic fluctuation rate measuring device can be easily installed in the annealing furnace.

  The drive coil has a normal to the coil surface of the drive coil along the longitudinal direction of the steel plate, and the receive coil has the coil surface of the receive coil along the steel plate surface so that the drive coil and the receive coil Since the coil surfaces are substantially orthogonal to each other, the reflected signal from the steel plate can be measured clearly.

  FIG. 6 is a reference diagram showing the state of magnetization of the steel sheet produced by the drive coil. If the drive coil has a normal line of the drive coil substantially perpendicular to the steel plate surface (the coil surface of the drive coil is substantially parallel to the steel plate), magnetization of the steel plate is generated by the thickness of the steel plate. However, in the present invention, as described above, the drive coil is arranged so that the normal line of the drive coil is along the longitudinal direction of the steel plate, whereby the steel plate can be magnetized over a long distance in the longitudinal direction of the steel plate. As a result, the volume in which the steel plate is magnetized can be increased, and the magnetic flux generated by the steel plate can be increased, which is generated in the receiving coil, rather than arranging the drive coil so that the normal line of the drive coil is substantially perpendicular to the steel plate surface. Therefore, even if the receiving coil is formed of an air-core coil, the receiving sensitivity can be satisfied. In addition, since the steel plate is magnetized over a long distance in the longitudinal direction of the steel plate, a peak of reflection intensity is generated away from the drive coil (occurs at a location where the S-pole and N-pole equivalent portions in the steel plate are separated). And the drive coil can be separated from each other, and radio waves can be prevented from being mixed directly from the drive coil to the receiving coil.

  The drive coil has a normal to the coil surface of the drive coil along the longitudinal direction of the steel plate, and the receive coil has the coil surface of the receive coil along the steel plate surface so that the drive coil and the receive coil Since the coil surfaces are arranged so as to be substantially orthogonal to each other, the magnetic flux generated by the steel plate can be increased and the receiving sensitivity of the receiving coil can be increased. Even if the driving coil and the receiving coil are constituted by air-core coils, the receiving sensitivity can be increased. Can be met.

  In particular, the receiving coil is an extension of the direction of the steel sheet in the direction of travel of the steel sheet or the opposite side of the direction of travel with respect to the line connecting the centers of the two short sides of the drive coil (the extension of the steel sheet in the center of the short side of the drive coil wound in a substantially rectangular shape By placing the coil surface of the drive coil and the coil surface of the receiving coil substantially orthogonal to each other, the unnecessary signal generated by the radio wave of the drive coil is reduced (preferably, the unnecessary signal is set to zero). The signal from the steel plate can be measured clearly. Here, on the basis of a line connecting the centers of the two short sides of the drive coil, the receiving coil is on the steel sheet conveying direction extension line at the short side center of the drive coil with respect to the traveling direction side of the steel plate or the opposite side of the traveling direction. The position error may be allowed within a range in which the signal from the steel plate can be clearly measured, without being limited to the position where it is strictly arranged.

  By making the position of the receiving coil distant from the driving coil, the receiving coil can be placed in a place where the reflected radio wave from the steel plate caused by the electromagnetic waves of the driving coil is strong, and a strong signal can be measured. In addition, the unnecessary signal generated by the drive coil is reduced when the receiving coil is separated from the drive coil, and the receiver coil can be moved closer to the steel plate where the reflected radio wave is strong, so that the unnecessary signal generated by the drive coil is reduced. Signals with strong reflected radio waves can be measured while reducing the effect.

  Moreover, when the receiving coil is brought close to the steel plate, an unnecessary signal generated by the driving coil in the receiving coil is reduced by slightly tilting the coil surface of the driving coil from the vertical surface of the steel plate (direction perpendicular to the steel plate) ( Preferably, the unwanted signal can be zero). If the receiving coil is brought close to the steel plate, the signal change due to the magnetization of the steel plate can be clearly measured, and the function as a magnetic transformation rate measuring device can be further enhanced.

  Furthermore, by dividing the signal generated by the reflected radio wave from the steel plate in the receiving coil into a signal synchronized with the signal of the drive coil and a signal shifted by 90 ° phase, together with the magnetic transformation rate (magnetization and transformation rate) of the steel plate It becomes possible to measure the electrical resistivity of each steel sheet.

It is an external view which shows one Embodiment of the magnetic transformation rate measuring apparatus of this invention. It is an enlarged view which expands and shows the area | region where the drive coil and receiving coil of the magnetic transformation rate measuring apparatus of FIG. 1 are arrange | positioned. It is a side view (longitudinal cut part end view) of the magnetic transformation rate measuring apparatus of FIG. It is a side view (longitudinal cut part end view) showing an example of other embodiments of the magnetic transformation rate measuring device of the present invention. It is a side view (longitudinal cut part end view) showing an example of other embodiments of the magnetic transformation rate measuring device of the present invention. It is a reference figure which shows the mode of the magnetization of the steel plate produced by a drive coil.

  Below, an example of preferable embodiment of this invention is demonstrated. In addition, this invention is not limited to the following embodiment.

  In one embodiment of the present invention, the driving coil and the receiving coil are air core coils wound with a heat-resistant electric wire that does not use an iron core, the driving coil is passed through a ceramic pipe or the like, and the receiving coil is a ceramic pipe. Etc. to install in the furnace. Thereby, it can be made extremely excellent in durability.

  Further, the drive coil has a circumferential surface in a direction perpendicular to the steel plate surface. As a result, the direction of the magnetic field generated by the drive coil is made parallel to the steel plate at the center of the drive coil surface, so that the magnetic flux (radio waves) generated by the drive coil that penetrates the receive coil is reduced and generated in the receive coil. Unnecessary signals from the drive coil are reduced, and the reflected signal from the steel plate becomes clear.

  In particular, the receiving coil is arranged on the traveling direction side of the steel sheet or on the opposite side of the traveling direction (near the extension line in the plate conveyance direction at the short side center of the driving coil) with reference to the line connecting the centers of the two short sides of the driving coil. By doing so, the radio wave (magnetic flux) emitted from the drive coil is orthogonal to the surface of the receiving coil, and unnecessary signals generated by the radio wave of the drive coil become zero, and the signal from the steel plate can be measured clearly. .

  By arranging the receiving coil at a position away from the drive coil, the receiving coil can be placed in a place where the radio wave (magnetic line) reflected from the steel plate is strong, and the signal of the reflected radio wave from the steel plate can be measured clearly. Become.

  Moreover, since the signal (noise) generated in the receiving coil by the driving coil is reduced by arranging the receiving coil away from the driving coil, the receiving coil is arranged close to the steel plate and the reflected radio wave signal from the steel plate is received. By making a large measurement, it becomes possible to clearly measure the signal of the reflected radio wave while reducing the relative intensity of noise.

  When the receiving coil is close to the steel plate, the signal due to the reflected radio wave from the steel plate is large, but when the receiving coil is close to the steel plate, the magnetic flux generated from the driving coil if the coil surface of the driving coil is perpendicular to the steel plate surface (Radio waves) generate a signal in the receiving coil, resulting in measurement disturbance. However, by arranging the coil surface of the drive coil slightly inclined from the vertical plane of the steel plate, the disturbance signal of the receiving coil can be reduced (preferably zero), and only the signal due to the reflected radio wave from the steel plate can be measured. It becomes like this. Moreover, the signal by the reflected electromagnetic wave from a steel plate becomes larger by bringing a receiving coil close to a steel plate.

  The signal generated by the reflected radio wave from the steel plate to the receiving coil includes the influence of electrical resistance along with the magnetization of the steel plate. The signal of the receiving coil is 90 ° out of phase with the signal synchronized with the signal of the driving coil. The electrical resistivity of the steel sheet can be measured together with the magnetization and transformation rate of the steel sheet.

  Hereinafter, an example of a more specific embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

  FIG. 1 is an external view showing an embodiment (first embodiment) of a steel sheet magnetic transformation rate measuring apparatus according to the present invention, and FIG. 2 shows an area where the drive coil and the receiving coil are arranged. It is the enlarged view shown expanded.

  As shown in FIG. 1, the steel plate 1 is annealed by an annealing furnace (continuous vertical annealing furnace) 2. The steel plate 1 is annealed with a sufficient staying time in the furnace by changing the direction with the roll 3 for passing plates installed in the furnace.

  As shown in FIG. 1, the magnetic transformation rate measuring apparatus according to this embodiment includes a drive coil 4, a power source 9 for supplying an alternating current to the drive coil 4, a receiving coil 6, and a signal received by the receiving coil 6. A voltmeter 10 for measurement is provided.

  The drive coil 4 is composed of an air-core coil. In the present embodiment, the drive coil 4 is configured through a ceramic pipe 5 that penetrates a heat-resistant electric wire in the furnace width direction of the annealing furnace 2, and is fixed to a midway position in the height direction of the annealing furnace 2.

  The drive coil 4 is configured such that a conducting wire is wound in a substantially rectangular shape and has a substantially rectangular circuit path. Here, the “substantially rectangular” means a shape having a pair of opposing short sides and a pair of long sides, and includes a rectangle, a shape with rounded corners, and a shape in which a part of the side is curved. . And the drive coil 4 is arrange | positioned so that the long side may cross the steel plate 1 in the width direction.

  As shown in FIG. 2, the drive coil 4 is arranged so that the normal line N of the coil surface 4 a of the drive coil 4 is along the longitudinal direction of the steel plate 1. In addition, although it is preferable that the drive coil 4 is arrange | positioned so that the said normal line N may become parallel to the longitudinal direction of the steel plate 1, it is not necessarily limited to this. The drive coil 4 has a normal line N inclined from the longitudinal direction of the steel plate 1 so as to reduce a signal other than the reflected radio wave from the steel plate 1 received by the receiving coil 6, for example, as in an embodiment described later. (The coil surface 4a of the drive coil 4 may be disposed at an angle from the vertical surface of the steel plate). At this time, for example, the normal line N has an inclination angle of −25 ° to + 25 °, preferably −10 ° to + 10 ° from the longitudinal direction of the steel plate 1 (the coil surface 4a of the drive coil 4 from the vertical surface of the steel plate). Can be placed.

  The reception coil 6 is formed of an air-core coil, and is disposed at a position where the radio wave emitted from the drive coil 4 can be received by the steel plate. As shown in FIG. 1, in the present embodiment, the receiving coil 6 is configured by rotating a ceramic projection provided at the tip of a ceramic pipe 7 whose rear end protrudes from the furnace body of the annealing furnace 2. Is fixed at a position above. The ceramic pipe 7 can be moved in the furnace width direction of the annealing furnace 2 by an arbitrary receiving coil moving means 8 so that the magnetic transformation rate can be measured by changing the measuring position of the receiving coil 6 in the plate width direction of the steel sheet 1. Has been. In the present invention, as described above, the drive coil 4 and the reception coil 6 are constituted by an air-core coil in which a heat-resistant electric wire is wound without using an iron core, so that it is lighter than a conventional iron-core coil and has a side wall of the furnace. It is easier to install than conventional coils with iron cores that are fixed from the ceiling using steel frames, etc., and can be easily installed in the middle of the furnace height direction.

  As shown in FIG. 2, the receiving coil 6 is disposed such that the coil surface 6a of the receiving coil 6 is along the steel plate surface. The receiving coil 6 is preferably disposed so that the coil surface 6a is parallel to the steel plate surface from the viewpoint that the reception intensity of the reflected radio wave from the steel plate 1 can be increased, but is not necessarily limited thereto. The receiving coil 6 may be disposed with an inclination within a range in which a signal of a reflected radio wave from the steel plate 1 can be detected. For example, the coil surface 6a of the receiving coil 6 can be disposed with an inclination angle of −25 ° to + 25 °, preferably −10 ° to + 10 ° from the steel plate surface.

  The drive coil 4 emits radio waves by an AC electrical signal supplied from the power source 9. The receiving coil 6 receives a radio wave (reflected radio wave) reflected by the steel plate 1 from a radio wave generated by the drive coil 4. Then, the signal generated in the receiving coil 6 by the reception is measured by the voltmeter 10.

  The magnetic transformation rate of the steel sheet 1 is obtained by measuring a signal in an equilibrium magnetization of the steel sheet 1 at a constant temperature in advance, and using that signal as a reference signal, the ratio of the signal generated in the receiving coil 6 and the reference signal A transformed ratio of 1 can be calculated.

  If the annealing furnace 2 is operated in a steady state, the steel plate temperature at the position where the magnetic transformation rate measuring device is installed is known in advance, so that the steel plate 1 is obtained from the measurement result of the magnetic transformation rate measuring device. The magnetic transformation rate is known.

  In order to measure the magnetic transformation rate of the steel plate 1 under various annealing conditions, a thermometer 11 for measuring the temperature of the steel plate 1 may be provided (FIG. 1).

  Since the annealing conditions determine the material of the product, measuring the magnetic transformation rate of the steel sheet in the annealing furnace makes it possible to appropriately control the furnace temperature and the sheet passing speed of the steel sheet 1, and the yield of the steel sheet 1 Useful for improvement.

  Further, the annealing furnace 2 is provided with an in-furnace cooling device (not shown), and has a function of producing a high-strength steel sheet by bringing the steel sheet into a non-equilibrium transformation state by cooling, and the magnetic transformation rate of the steel sheet in the furnace. It is also necessary to manufacture high-strength steel sheets.

  Next, detailed configurations of the drive coil 4 and the reception coil 6 will be described with reference to FIG. FIG. 3 is a side view of the magnetic transformation rate measuring apparatus of FIG. 1 (vertical cut end face view).

  The drive coil 4 of the magnetic transformation rate measuring apparatus of this embodiment is a coil that circulates in a direction perpendicular to the steel plate 1 (horizontal), has a short side Hd, and is separated from the steel plate 1 by H in the horizontal direction. The receiving coil 6 is arranged at a position that is perpendicular to the center of the short side Hd of the driving coil 4 and is L away from the traveling direction side of the steel plate or the opposite side of the traveling direction. The receiving coil 6 has a length Lc and a width W (see FIG. 2).

  As shown in FIG. 3, it is preferable that the coil surface 4a of the drive coil 4 and the coil surface 6a of the receiving coil 6 are substantially orthogonal. In the present embodiment, the receiving coil 6 is disposed above a line segment T (see FIG. 2) connecting the centers of the two short sides of the driving coil 4. However, it is not limited to this arrangement, for example, as in the embodiment described later, in consideration of the distance between the receiving coil 6 and the steel plate 1, the influence of unnecessary radio waves from the driving coil 4 received by the receiving coil 6, The angle formed by the two can be adjusted appropriately.

  As shown in FIG. 3, when an alternating current is supplied from the power source 9 to the drive coil 4, a radio wave 102 is generated in the direction of the magnetic force lines 100 generated by the drive coil 4. Radio waves are also radiated to the upper part of FIG.

  When the radio wave reaches the steel plate 1, electricity flows through the steel plate 1 according to the magnetism and electrical resistance of the steel plate 1 to generate a magnetic flux 101, and the reflected radio wave from the steel plate 1 travels in the direction of the magnetic flux 101. When this radio wave crosses the receiving coil 6, a voltage is generated. The signal due to this voltage changes depending on the electromagnetic state of the steel sheet 1, and if the magnetic transformation rate (ferrite ratio) at the steel sheet temperature is large, the signal is large, and if it is small, the signal is small. Signal) and the like, the magnetic transformation rate of the steel sheet 1 can be known.

  FIG. 4 is a side view (vertical cut end view) showing another embodiment (second embodiment) of the present invention. However, the description of the receiving pipe fixing ceramic pipe 7 and the like is omitted.

  In the present embodiment, the distance Hc between the steel plate 1 and the receiving coil 6 is reduced so that the reflected radio wave from the steel plate 1 can be measured more strongly.

  FIG. 5 is a side view (vertical cut portion end view) showing another embodiment (third embodiment) of the present invention. However, the description of the receiving pipe fixing ceramic pipe 7 and the like is omitted.

  When a radio wave from the drive coil 4 enters the reception coil 6, a noise signal is generated. However, in this embodiment, the drive coil 4 is tilted, and the traveling direction of the radio wave emitted from the coil surface 6 a of the reception coil 6 and the drive coil 4. Are made parallel to eliminate radio waves and noise from the drive coil 4 penetrating the receiving coil 6 (coil surface 6a).

  As shown in FIG. 5, in this embodiment, the coil surface 4a of the drive coil 4 is disposed with an inclination angle θ from the vertical surface (horizontal direction) of the steel plate. As described above, the range of θ can be −25 ° to + 25 °, preferably −10 ° to + 10 °.

  According to such a configuration, the signal of the reflected radio wave from the steel plate 1 can be greatly measured by arranging the receiving coil 6 close to the steel plate 1 while reducing the influence of unnecessary radio waves from the drive coil 4. The reflected radio signal can be clearly measured.

  Table 1 shows the configuration of the magnetic transformation rate measuring device of the present invention and the signal (noise signal ratio) obtained by this configuration. In addition, the magnetic transformation rate measuring apparatus of this invention is not limited to the following invention examples.

  When the drive coil 4 emits a radio wave as in the present invention, the radio wave directly enters the reception coil 6 and the signal becomes noise to reduce the measurement accuracy. The voltage signal Vd and the reflected wave signal Vc from the steel plate are divided into the ratio Vd ÷ Vc, and the ratio of noise to signal is used as a performance index. The smaller the noise signal ratio, the greater the required signal Vc from the steel sheet, and the better the characteristics.

  In Table 1, the magnetic variation rate measuring apparatus of Invention Example 1 shows the number of turns of the H, Hd, Hc, Lc, L, W, drive coil, and receiver coil in Table 1 in the first embodiment. It is a value shown.

  Moreover, in Table 1, the magnetic fluctuation rate measuring device of Conventional Example 1 is the magnetic transformation rate measuring device shown in FIG. In addition, the magnetic variation rate measuring apparatus of Conventional Example 1 was installed at the same position as the position where the magnetic variation rate measuring apparatus of Invention Example 1 was installed.

  As a result, in Conventional Example 1, the weight of the magnetic transformation rate measuring device and the high temperature inside the furnace were affected, and the support was bent slightly in two weeks, and the measurement could not be maintained due to water leakage from the cooling water piping. On the other hand, the magnetic transformation rate measuring apparatus of Invention Example 1 did not cause a problem even after 3 months.

  Further, the magnetic transformation rate measuring device of Conventional Example 1 has a large occupied volume of heat insulating material and cooling pipes and can only be installed at one central portion of the plate width. However, the magnetic transformation rate measuring device of Invention Example 1 receives in the plate width direction. By moving the coil, the magnetic transformation rate over the entire width of the steel sheet 1 could be measured.

  Product yield was 85% in the production of the high-strength steel sheet before the magnetic transformation rate measuring device of Invention Example 1 was provided, but the magnetic transformation rate was measured by installing the magnetic transformation rate measuring device of Invention Example 1, By controlling the annealing temperature setting and the sheet feeding speed, the product yield was 99%.

  In the present invention, since the receiving coil is light, a plurality of receiving coils may be installed in the width direction of the steel sheet, and the distribution of the magnetic transformation rate in the width direction of the steel sheet may be measured simultaneously.

  In Table 1, in the magnetic transformation rate measuring device of Invention Example 2, the distance L between the driving coil 4 and the receiving coil 6 is set to 300 mm.

  As shown in FIG. 6, the peak of the reflected radio wave is generated in the distance along the magnetization of the steel plate. However, if the distance between the drive coil 4 and the receiving coil 6 becomes too large, the peak of the reflected radio wave from the steel plate passes. . Therefore, since the radio wave from the drive coil 4 becomes weak and the reflected radio wave becomes small, the noise signal ratio is slightly increased, but the magnetic transformation rate can be measured sufficiently.

  In Table 1, Invention Examples 3 and 4 are obtained by making L smaller than Invention Example 1 and bringing the drive coil 4 and the reception coil 6 closer to each other. When the distance between the drive coil 4 and the reception coil 6 becomes short, the noise signal from the drive coil 4 tends to increase. This is presumably because the receiving coil 6 was installed near the peak of the reflected radio wave and the magnitude of the reflected radio wave was not sufficient. The spatial spread (attenuation) of the reflected wave is dependent on the positional relationship between the drive coil 4 and the steel plate 1, and as the Hd increases, the peak of the reflected radio wave tends to occur further away. L ÷ Hd is an appropriate dimension index. L ÷ Hd is preferably 1 or more. That is, the distance L between the receiving coil 6 and the driving coil 4 is preferably equal to or longer than the length of the short side Hd of the driving coil 4.

  In Table 1, the magnetic fluctuation rate measuring device of Invention Example 5 shows H, Hd, Hc, Lc, L, W, the number of turns of the driving coil, and the number of turns of the receiving coil in Table 2 in the second embodiment. It is a value shown. That is, in the invention example 5, the distance Hc between the steel plate 1 and the receiving coil 6 is set to 100 mm, and the steel plate 1 and the receiving coil 6 are arranged close to each other. With this configuration, the signal of the reflected radio wave from the steel plate 1 can be measured largely, and the noise signal ratio is sufficiently small to have the same performance as the inventive examples 1 and 2.

  In Table 1, the magnetic variation rate measuring apparatus of Invention Example 6 shows H, Hd, Hc, Lc, L, W, the number of turns of the driving coil, and the number of turns of the receiving coil in Table 3 in the third embodiment. In this example, the coil surface 4a of the drive coil 4 is disposed with an inclination angle of 11 ° from the vertical surface (horizontal direction) of the steel plate. With this configuration, the signal of the reflected radio wave from the steel plate 1 can be measured largely, and the noise signal ratio can be further reduced from the invention example 5.

  In addition, when the magnetic transformation rate measurement device of Invention Examples 2 to 6 was installed at the same position as the magnetic variation rate measurement device of Invention Example 1, the magnetic transformation rate measurement device of Invention Examples 2 to 6 was the same as that of Invention Example 1. Similar to the rate measuring device, the measurement could be maintained even after 3 months from installation.

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Annealing furnace 3 Roller for rolling plate 4 Drive coil 5 Ceramic pipe 6 for fixing a drive coil Reception coil 7 Ceramic pipe for fixing a reception coil 8 Reception coil moving means 9 Power source 10 Voltmeter 11 Thermometer 100 Magnetic flux generated by a drive coil ( Magnetic field lines)
101 Magnetic flux generated by a steel plate (line of magnetic force)
102 radio wave

Claims (11)

A steel sheet magnetic transformation rate measuring device for measuring a magnetic transformation rate of a steel plate in an annealing furnace,
A drive coil that emits radio waves by an alternating electrical signal flowing through the coil;
A receiving coil for receiving a radio wave reflected by a steel plate, the radio wave emitted by the drive coil; and
The drive coil is composed of an air-core coil having a path that crosses the steel plate in the width direction, and the normal line of the coil surface of the drive coil is arranged along the longitudinal direction of the steel plate,
An apparatus for measuring a magnetic transformation rate of a steel sheet, wherein the receiving coil is constituted by an air-core coil, and the coil surface of the receiving coil is arranged along the steel sheet surface. The apparatus according to claim 1, wherein the drive coil has a substantially rectangular circuit path. The apparatus for measuring a magnetic transformation rate of a steel sheet according to claim 2, wherein the receiving coil and the driving coil are arranged apart from each other by at least the length of the short side of the driving coil. The steel sheet according to claim 2 or 3, wherein the receiving coil is arranged on the traveling direction side of the steel sheet or on the opposite side of the traveling direction with reference to a line segment connecting the centers of two short sides of the driving coil. Magnetic transformation rate measuring device. The apparatus for measuring a magnetic transformation rate of a steel sheet according to any one of claims 1 to 4, wherein a distance between the receiving coil and the steel sheet is within 100 mm. The distance between the receiving coil and the steel plate is within 100 mm,
The drive coil is arranged with an inclination angle from a vertical plane of the steel plate so that a signal other than the radio wave reflected by the steel plate received by the receiving coil becomes small. Item 6. An apparatus for measuring a magnetic transformation rate of a steel sheet according to any one of Items 1 to 5. The apparatus for measuring a magnetic transformation rate of a steel sheet according to any one of claims 1 to 6, wherein the receiving coil is movable in the sheet width direction of the steel sheet. The apparatus for measuring a magnetic transformation rate of a steel sheet according to any one of claims 1 to 7, wherein a plurality of receiving coils are arranged in a plate width direction of the steel sheet. The apparatus for measuring a magnetic transformation rate of a steel sheet according to any one of claims 1 to 8, wherein the driving coil and the receiving coil are arranged at a midway position in the height direction of the vertical annealing furnace. The magnetic transformation rate measurement of a steel plate according to any one of claims 1 to 9, wherein the magnetic transformation rate of the steel plate is measured by comparing a signal received by the receiving coil with a reference signal measured in advance. apparatus. The magnetic transformation rate measurement of a steel plate according to any one of claims 1 to 10, wherein the signal received by the receiving coil is separated into phase components and the electrical resistivity of the steel plate is measured together with the magnetic transformation rate of the steel plate. apparatus.

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