JP2018181789A - Induction heating apparatus and induction heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform induction heating upon a material to be heated to a target temperature regardless of a kind or a composition of the material to be heated and regardless of influences of a transfer device or the like on a line where the material to be heated is transferred.SOLUTION: An induction heating device 1 is configured to perform induction heating upon a steel plate H being transferred on a line by an induction heating part 10 including an induction coil and an AC power source which outputs power to the induction coil. The induction heating device comprises: a temperature measurement part 11 which is provided at a position at an upstream side of the induction heating part 10 on the line and measures a temperature of the steel plate H being transferred; a physical property value measurement part 12 which is provided at a position at the upstream side of the induction heating part 10 on the line and measures physical quantities relating to physical property values of the steel plate H being transferred; and a control part 14 which determines an output condition of power from the AC power source to the induction coil based on at least measurement results in the temperature measurement part 11 and the physical property value measurement part 12.SELECTED DRAWING: Figure 1

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an induction heating apparatus and an induction heating method for induction heating a material to be heated such as steel during conveyance on a production line.

  In the current iron and steel industry, there are many types of steel sold because there are many needs, and although some orders are produced collectively, it is common to produce steel plates of a plurality of steel types in one production line. In such a production line, heat treatment is performed, and as a heating method for heat treatment, a heating method by induction heating, which has a higher heating efficiency than a heating method by a high temperature gas, may be used. In the heating method by induction heating, an induction current is generated in a steel plate as a material to be heated by an induction coil supplied with electric power from an AC power supply, and the steel plate is heated by the induction current.

  In Patent Document 1, an induction coil for induction heating a metal pipe to be heated as a material to be heated, a thickness detector for detecting the thickness of the metal pipe to be heated, and induction according to the output of the thickness detector An induction heating device is disclosed which comprises control means for controlling the power supplied to the coil.

  Patent Document 2 shows an induction heating method in which an induction coil is excited by an AC power supply to inductively heat a metal material, and the temperature distribution on the surface of the metal material before induction heating is measured, and the measurement result is set in advance. A method is disclosed for determining the frequency of an alternating current source based on a target temperature.

  Patent Document 3 discloses a switch for outputting AC power to an induction coil, and a frequency setting unit for setting an output frequency according to at least one of permeability, resistivity, and plate thickness of a conductive plate to be induction heated, ie, a metal material. There is disclosed an induction heating device comprising: a gate control device which controls the switch operation of the switch based on the output frequency set by the frequency setting unit. In the induction heating apparatus of Patent Document 3, the frequency setting unit acquires the permeability, resistivity, thickness and frequency of the metal material, and acquires permeability, resistivity, thickness and frequency of the metal. Are associated with each other and the table registered in advance is set, and the frequency corresponding to the acquired attribute information is set.

  Patent Document 4 calculates the coil position which is the relative position of the coil of the induction heating portion with respect to the metal material and maximizes the induction heating efficiency, using the physical property value of the metal material to be heated. An induction heating apparatus is disclosed that has an arithmetic processing unit that calculates a power correction amount that corrects an insufficient amount according to the induction heating efficiency of the power supply amount to the coil using the calculated value and the physical property value of the metal material. . In the induction heating apparatus of Patent Document 4, the physical property values of the metal material to be heated are held and managed by the process computer, and the arithmetic processing unit calculates the physical properties of the metal material from the process computer when calculating the power correction amount. Get the value.

JP-A-53-36048 JP, 2008-159572, A JP, 2011-216502, A JP 2014-175082 A

  By the way, in induction heating, physical property values such as permeability and electrical resistivity of the material to be heated affect the temperature rise amount at induction heating, so considering these physical property values, the AC power supply to the induction coil It is necessary to control the power output. As a method of controlling the above-mentioned output and obtaining an appropriate amount of temperature rise in consideration of physical property values, there is a method disclosed in the above-mentioned Patent Document 3. That is, it is a method of setting the frequency of AC power to be output to the induction coil using a table, ie, a database, in which the permeability, resistivity, plate thickness, frequency and frequency of the material to be heated are mutually associated and registered in advance. .

However, the physical property values of materials to be heated such as steel being transported on the production line are not constant. These physical property values are temperature dependent, and the temperature of the material to be heated immediately before entering the induction heating device on the production line is not necessarily constant. For example, in hot-dip galvanizing of a steel plate as a material to be heated, gas is sprayed from a gas wiping nozzle onto a steel plate after passing a zinc bath to adjust the amount of plating, and then the steel plate is induction heated, but the steel plate can be pulled up from the zinc bath It is difficult to completely control the speed and the blowing amount of gas, and the temperature of the steel sheet immediately before entering the induction heating device changes depending on the speed and the blowing amount.
Furthermore, the types of materials to be heated, for example, the types of steels and alloys, are very large at present, and the alloy compositions vary within the same standard.

Therefore, it is difficult to construct an accurate and sufficient database to obtain an appropriate temperature rise, and there is a limit in the induction heating method disclosed in Patent Document 3.
Further, the induction heating method disclosed in Patent Document 4 uses the physical property value of the metal material as in the method disclosed in Patent Document 3. Then, in the induction heating method disclosed in Patent Document 4, as in the method disclosed in Patent Document 3, in order to appropriately raise the temperature, it is necessary to hold a sufficient amount and accurate physical property value of the metal material. Yes, this is difficult.
Patent documents 1 and 2 disclose controlling the power supplied to the induction coil based on the temperature of the metal material, but do not disclose or suggest the above problems.

  The present invention has been made in view of such a point, and regardless of the type and composition of the material to be heated, and regardless of the influence of the conveying device on the line for conveying the material to be heated, the material to be heated An object of the present invention is to provide an induction heating apparatus and an induction heating method capable of induction heating to a target temperature.

  In order to achieve the above object, the present invention is an induction heating apparatus for induction heating a material to be heated on a line by an induction heating unit having an induction coil and an AC power supply outputting an electric power to the induction coil. A temperature measuring unit provided on the upstream side of the induction heating unit in the line for measuring the temperature of the material to be heated, and a position on the upstream side of the induction heating unit in the line And from the alternating current power source to the induction coil based on the measurement results of at least the temperature measurement unit and the physical value measurement unit for measuring the physical quantity related to the physical value of the material to be heated during transportation. And a control unit that determines an output condition of the power of

  A steel plate information acquisition unit that acquires information on at least the dimensions of the material to be heated is provided, and the control unit calculates the physical property value from the physical quantity measured by the physical property value measurement unit, and the measurement result by the temperature measurement unit The output condition may be determined based on the calculated physical property value and the dimension of the material to be heated acquired by the steel plate information acquisition unit.

  The physical property value measurement unit has an inspection coil disposed on the line, and calculates, as the physical quantity, an inductance of the test coil when the material to be heated is conveyed in the physical property value measurement unit. The physical quantity of or the inductance may be measured.

  The physical property value measurement unit may include an inspection coil disposed on the line and having the same shape as the induction coil.

  The control unit further includes another temperature measurement unit provided downstream of the induction heating unit in the line and measuring the temperature of the material to be heated during conveyance after induction heating by the induction heating unit. The output condition may be corrected based on the measurement result of another temperature measurement unit.

  The present invention according to another aspect is an induction heating method for induction heating a material to be heated being conveyed on a line by an induction heating unit having an induction coil and an AC power supply that outputs electric power to the induction coil, Temperature measurement step of measuring the temperature of the material to be heated during conveyance on the line upstream of the induction heating portion; and physical property values of the material to be heating during conveyance on the line upstream of the induction heating portion Step of determining an output condition of power from the AC power supply to the induction coil based on at least a physical property value measuring step of measuring a physical quantity related to at least the temperature measuring step and a measurement result of the physical value measuring step. And is characterized.

  At least the steel plate information acquisition step of acquiring information on the dimensions of the material to be heated, the output condition determination step calculates the physical property value from the physical amount measured in the physical property value measurement step, and the temperature measurement step The output condition may be determined based on the measurement result, the calculated physical property value, and the dimension of the material to be heated acquired in the steel plate information acquiring step.

  The physical property value measurement step is a physical quantity or a physical quantity for calculating an inductance of the test coil when the material to be heated is conveyed in the physical property value measurement unit having the test coil disposed on the line as the physical quantity. The inductance may be measured.

  In the physical property value measuring step, the physical quantity may be measured using an inspection coil having the same shape as the induction coil disposed on the line.

  The induction heating method includes another temperature measurement step of measuring the temperature of the material to be heated after induction heating by the induction heating unit being transported on the line downstream of the induction heating unit, and another temperature measurement The method may further include a correction step of correcting the output condition based on the measurement result in the step.

  According to the present invention, the material to be heated can be induction heated to the target temperature regardless of the type or composition of the material to be heated, and regardless of the influence of the conveying device on the line for conveying the material to be heated. . Further, according to the present invention, even after the type of the material to be heated which is the material to be heated is changed, the material to be heated can be inductively heated to the target temperature.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline of a continuous hot dip galvanization apparatus provided with the induction heating apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the outline of the induction heating part of FIG. It is a figure which shows the outline of the physical-property value measurement part of FIG. It is a figure explaining the method to acquire a physical-property value based on the measurement result in the physical-property value measurement part of FIG. It is a figure which shows the outline of the induction heating apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the induction heating result of an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and the drawings, components having substantially the same functional configuration will be assigned the same reference numerals and redundant description will be omitted.

First Embodiment
FIG. 1 is a schematic view of a continuous hot-dip galvanizing apparatus provided with an induction heating device according to a first embodiment of the present invention.
The continuous galvanizing apparatus 100 of FIG. 1 performs galvanization on a steel plate H, heats the steel plate H to which the galvanization is attached by the induction heating device 1, and alloyizes the galvanized steel layer of the steel plate H The weldability, corrosion resistance, pressability and the like of the steel plate H are improved. The details will be described below.

Continuous galvanizing apparatus 100 is provided on a production line of hot-dip galvanized steel sheet, and hot-dip galvanizing bath 2, gas wiping nozzle 3, damping device 4, induction heating apparatus 1, and upper roll 5 are along the production line. Are arranged in this order from the upstream side to the downstream side.
In the continuous galvanizing apparatus 100, the steel sheet H is conveyed on the production line, annealed in a not-shown annealing furnace, and then passed through a duct-like snout 6 provided to prevent oxidation by the open air. It is introduced into the hot dip galvanizing bath 2.
The steel sheet H introduced into the hot-dip galvanizing bath 2 is turned upward by the sink roll 2a provided in the bath 2 and the warp is corrected by the support roll 2b, and then it is pulled out from the hot-dip galvanizing bath 2. Be
Then, in the hot-dip galvanized steel sheet H, the wiping gas is sprayed from both sides of the gas wiping nozzle 3 to adjust the plating adhesion amount.

The steel plate H whose plating adhesion amount has been adjusted passes through the vibration control device 4 that suppresses the vibration of the steel plate H. The damping device 4 may have a function of defining the angle of the steel plate H with respect to the induction heating device 1 in addition to the function of suppressing the vibration of the steel plate H.
As a method for suppressing the vibration by the vibration damping device 4 and for defining the angle, a method in which a high temperature gas (for example, 450 ° C. or more) is sprayed to the end of the steel plate H can be considered. In addition, a method using a pinch force of an electromagnetic force may be used.

After passing through the damping device 4, the steel plate H is heated by the induction heating device 1 and heated up to, for example, 550 ± 10 ° C., and the hot-dip galvanized layer of the steel plate H is between the steel plate H and the upper roll 5. Is alloyed. Details of the induction heating device 1 will be described later.
The steel sheet H in which the hot-dip galvanized layer is alloyed is cooled by a cooling device (not shown), and the sheet passing direction is changed by the upper roll 5.

Subsequently, the details of the induction heating device 1 will be described.
The induction heating apparatus 1 induction-heats the steel plate H as the heating target material being conveyed on the production line (hereinafter referred to as a line) by the induction heating unit 10, and the position of the line on the upstream side of the induction heating unit 10 The temperature measurement unit 11 and the physical property value measurement unit 12 are provided. Although the temperature measurement unit 11 is disposed on the upstream side of the physical property value measurement unit 12 in the example of the figure, the positions of the temperature measurement unit 11 and the physical property value measurement unit 12 may be reversed.

FIG. 2 is a schematic view of the induction heating unit 10.
The induction heating unit 10 has an induction coil 10a and an AC power supply 10b, as shown in the figure.
The induction coil 10a is made of a conductor such as copper, is provided so as to be wound around the steel plate H being transported, and is connected to an AC power supply 10b.
The AC power supply 10b supplies / outputs power to the induction coil 10a.

  In the induction heating unit 10, a magnetic flux M1 substantially parallel to the plate surface of the steel plate H is generated by the induction coil 10a, and the magnetic flux M1 intensively penetrates the surface layer close to the induction coil of the cross section orthogonal to the sheet passing direction of the steel plate H. Do. The magnetic flux M1 generates an induced current which circulates in a cross section orthogonal to the passing direction of the steel plate H, and the steel sheet H is heated by the induced current. That is, the induction heating unit 10 heats the steel plate H by induction heating of a parallel magnetic flux (LF) method.

It returns to the explanation of FIG.
The temperature measuring unit 11 is a position on the upstream side of the induction heating unit 10 in the line, and at a position between the damping device 4 and the induction heating unit 10, that is, a position just before the induction heating unit 10, Measure the temperature. The temperature measurement unit 11 is, for example, a contact-type temperature sensor such as an infrared temperature sensor.

  The physical property value measuring unit 12 is a position on the upstream side of the induction heating unit 10 in the line, and is a position between the damping device 4 and the induction heating unit 10, that is, a position just before the induction heating unit 10 Measure the physical quantity related to the physical property value of. The physical property values of the steel plate H are, for example, the permeability and the electrical resistivity of the steel plate H.

FIG. 3 is a diagram schematically showing the physical property value measurement unit 12.
As shown in FIG. 3, the physical property value measurement unit 12 includes an inspection coil 12 a and an AC power supply 12 b.
The inspection coil 12a is made of a conductor such as copper, is provided so as to be wound around the steel plate H being transported, and is connected to an AC power supply 12b.
The AC power supply 12b supplies / outputs power to the coil 12a.

The physical property value measuring unit 12 applies an exciting current to the inspection coil 12a from the AC power supply 12b to generate a magnetic flux M2 substantially parallel to the plate surface of the steel plate H passing through the physical property value measuring unit 12, that is, the inspection coil 12a. , The induction current is applied to the steel plate H. The property value measurement unit 12, as a physical quantity relating to physical properties of the steel sheet H, the voltage V applied to the test coil 12a upon applying an induced current, the current I ₁ and voltage V and the current I ₁ flowing through the test coil 12a The phase difference θ is measured. These measurement results are transmitted from the physical property value measurement unit 12 to the control unit 14 (see FIG. 1) described later.
Since the physical property value measurement unit 12 is not intended to inductively heat the steel plate H, the power supplied from the AC power supply 12 b is greater than the power supplied from the AC power supply 10 b of the induction heating unit 10. It is preferable to make it smaller.

It returns to the explanation of FIG. 1 again.
The induction heating apparatus 1 further includes a steel plate information acquisition unit 13 and a control unit 14.
The control unit 14 is, for example, a computer and has a program storage unit (not shown). The program storage unit stores a program for executing the induction heating process in the induction heating device 1. The program is stored in a computer readable storage medium such as a computer readable hard disk (HD), a flexible disk (FD), a compact disk (CD), a magneto optical disk (MO), and a memory card. And may be installed in the control unit 14 from the storage medium. Details of the control unit 14 will be described later.

  The steel plate information acquiring unit 13 acquires physical property values such as specific heat of the steel plate H to be heated, dimensions, and the like, and, for example, from an input device (for example, a mouse, a keyboard, a touch panel, etc.) to a computer configuring the control unit 14 Configured The dimension of the steel plate H is, for example, the thickness or width of the steel plate H, and is input by the user via the input device. Moreover, the steel plate information acquisition part 13 may acquire the information from a database through a communication line instead of inputting from a user via an input device. Information related to physical property values such as specific heat of the steel plate H and dimensions and the like acquired by the steel plate information acquisition unit 13 is transmitted to the control unit 14. The physical property values acquired by the steel plate information acquiring unit 13 are the steel type dependency, the density or the specific heat having a small temperature dependency.

  In addition, the induction heating device 1 includes another temperature measurement unit 15 at a position downstream of the induction heating unit 10 in the line. The temperature measurement unit 15 measures the temperature of the steel sheet H after induction heating during conveyance at a position between the induction heating unit 10 and the upper roll 5, that is, a position immediately after the induction heating unit 10. The temperature measurement unit 15 is, for example, a contactless temperature sensor such as an infrared temperature sensor, and in the present embodiment, to check whether the temperature of the steel sheet H after induction heating has reached a predetermined value. Used for

  Subsequently, the control unit 14 will be described with reference to FIGS. 1 and 3 and FIG. 4. FIG. 4 is a diagram for explaining a method in which the control unit 14 acquires physical property values based on the measurement results in the physical property value measurement unit 12 as described later.

  The control unit 14 controls each part of the induction heating device 1, in particular, the induction heating unit 10. The control unit 14 is based on the measurement results of the temperature measurement unit 11 and the physical property value measurement unit 12 and the acquisition result of the steel plate information acquisition unit 13, from the AC power supply 10 b of the induction heating unit 10 to the induction coil 10 a. Determine the power output conditions.

Specifically, for example, the control unit 14 first calculates the inductance L ₁ of the inspection coil 12 a when the steel plate H is transported in the physical property value measurement unit 12 based on the physical quantity measured by the physical property value measurement unit 12. Do. More specifically, the physical quantity measured by the physical property value measurement unit 12 means the voltage V applied to the inspection coil 12a when the induced current is generated in the steel plate H in the physical property value measurement unit, and the current I ₁ flowing through the inspection coil 12a. and the phase difference θ of the voltage V and the current I _1, the inductance L ₁ of the test coil 12a is calculated from the following equation (1). Here, f ₁ is the frequency of the AC power supply 12 b.
L ₁ = V * sin θ / 2π * f ₁ I ₁ (1)

Then, the control unit 14 calculates the magnetic permeability μ of the steel sheet H from the calculated inductance L _1. The relationship between the inductance L of the inspection coil 12a and the relative magnetic permeability can be expressed by the relational expression f (x) in FIG. 4 and, for example, the control unit 14 calculates the steel plate from the relational expression f (x) and the inductance calculated above. The relative permeability of H is calculated, and the permeability μ of the steel plate H is calculated from the relative permeability.
The horizontal axis in FIG. 4 indicates the relative permeability, and the vertical axis indicates the inductance L of the inspection coil 12a, and the relational expression f (x) approximates the result of the following simulation by a logarithmic function. That is, the thickness and width of the steel plate H are 1 mm and 500 mm, respectively, the number of turns of the inspection coil 12a, the height of the opening and the width of the opening are 5 turns, 60 mm and 580 mm, respectively, and the excitation current is 10 A The inductance L of the inspection coil 12a is calculated by simulation assuming that the frequency of the AC power supply 12b is 1 kHz and the relative permeability of the steel plate H is 10, 100, 1000, and the calculation result is approximated by a logarithmic function Thus, the relational expression f (x) can be obtained.

Further, the control unit 14 calculates the electrical resistivity _{e e} of the steel plate H from the calculated inductance L. Since the electrical resistivity _{e e} can be calculated from the inductance L in the same manner as the magnetic permeability μ, the description of the calculation method is omitted. Incidentally, the resistance _{R 1} of the test coil 12a advance calculated from _{R 1 = V * cosθ / I} 1, may calculate the electrical resistivity [rho _e of the steel sheet H from the resistance _{R 1} of the test coil 12a.

Then, the control unit 14 calculates the magnetic permeability μ and the electrical resistivity _{e e of} the steel plate H, the temperature T _{m of the} steel plate H measured by the temperature measurement unit 11, the preset target temperature T _t, and the steel plate Based on the dimensions (thickness t and width W) of the steel plate H acquired by the information acquisition unit 13, the output condition of power from the AC power supply 10b of the induction heating unit 10 to the induction coil 10a is determined. In the following example, the above-mentioned output condition is determined using the mass density _{m m} of the steel plate H acquired by the steel plate information acquisition unit 13 and the specific heat c. The output condition is, for example, a current _{I 2} supplied to the frequency _{f 2} and the induction coil 10a of the power. If the permeability μ is large, decides to higher as the frequency f _2, to determine the larger as the current I _2, when the electric resistivity [rho _e is large, decides to higher as the frequency f _2, the current I Decide to be large as ₂ . Specifically, assuming that the electrical resistance of the induction coil 10a itself is sufficiently small, let L be the length of the induction coil 10a in the longitudinal direction of the steel plate, and v be the line speed. ) To determine the target input power P.
ΔT = T _t −T _m equation (2)
P = W * t * v * ρ _m * c * ΔT formula (3)

Then, the current _{I 2} supplied to the frequency _{f 2} and the induction coil 10a can be calculated from, for example, the following equation (4) to (7). In the following equation, n is the number of turns of the induction coil 10a, and L 'is the inductance of the induction coil 10a obtained by simulation.
f ₂ > 4 * ρ _e / (π * t ² * μ) formula (4)
I ₂ = (P * ((R ² + (2π * f * L ′) ² )) ^1/2 / (2π * f * L ′) Formula (5)
R = (n ² * ρ _e * W / δ) / l formula (6)
δ = (ρ _e / (π * f * μ)) ^1/2 Equation (7)

In the above description, it was assumed that the electrical resistance of the induction coil 10a itself was sufficiently small, but also in cases other than this assumption, the influence of the physical property values and dimensions of the passing steel plate H on input power P was clarified by simulation. if a manner, operating parameters, i.e., it is possible to determine the optimum as the current I ₂ supplied to the frequency f ₂ and the induction coil 10a of the electric power supplied to the induction coil 10a.

  The control unit 14 transmits the determined output condition to the AC power supply 10 b of the induction heating unit 10. The AC power supply 10b supplies power to the induction coil 10a based on the output condition.

  Therefore, the induction heating device 1 induction-heats the steel plate H to the target temperature by the induction coil 10a regardless of the type and composition of the steel plate H and without the influence of the conveyance device on the line for conveying the steel plate H. be able to.

  Some existing induction heating devices measure the temperature after induction heating and feedback control the output conditions of the power to the induction coil based on the temperature. In this existing induction heating device, the temperature of the material to be heated is The temperature can not be raised to the target temperature immediately after the type change. On the other hand, in the induction heating device 1 of the present embodiment, the steel plate H can be heated to the target temperature even immediately after the type of the steel plate H changes.

Second Embodiment
The induction heating device 1 according to the present embodiment is not shown, but unlike the induction heating device according to the first embodiment, the inspection coil 12 a (see FIG. 3) of the physical property value measurement unit 12 is the induction heating unit 10. The same shape as that of the induction coil 10a of FIG.
In the induction heating apparatus 1 according to the present embodiment, for example, the control unit 14 first performs the steel plate H in the physical property value measurement unit 12 based on the physical quantity measured by the physical property value measurement unit 12 as in the first embodiment. Calculating the inductance L of the inspection coil 12a when it is transported.

Then, the control unit 14, induces an inductance L calculated from the target temperature T _t like set in advance and the temperature T _m of a measured steel sheet H in the temperature measuring unit 11, from the AC power supply 10b of the induction heating section 10 coil determining the supply current _{I 2} to the power of the frequency _{f 2} and the induction coils 10a to 10a. Specifically, to determine the frequency f ₂ and current I ₂ as the target temperature T _m is reached with the inductance L of the test coils 12a coincides with the inductance L ₂ of the induction coil 10a. More specifically, the frequency f ₂ can be calculated for example from the above equation (4), the current I ₂ supplied to the induction coil 10a can be calculated from equation (8) below, for example. In addition, R 'in the following Formula (8) is a resistance value measured by the test coil 12a of the same dimension as the induction coil 10a.
I = (P / R ') ^1/2 ... Formula (8)

  Since the control unit 14 transmits the determined output condition to the AC power supply 10b of the induction heating unit 10, and the AC power supply 10b supplies power to the induction coil 10a based on the output condition, the induction heating device 1 of this embodiment Even if the steel sheet H is present, the steel sheet H can be inductively heated to a target temperature by the induction coil 10a regardless of the type, composition, and the like of the steel sheet H. Moreover, in the induction heating apparatus 1 of this embodiment, the amount of calculations in the control unit 14 can be reduced as compared with that of the first embodiment.

The frequency f ₂ of the power supplied to the induction coil 10a from the AC power supply 10b of the induction heating section 10 may be determined as follows. That is, inspect the resistance R'measure of test coils 12a while changing the frequency f ₁ of the AC power supply 12b with the coils 12a, the frequency f ₁ of those lowest is obtained as a resistance R'the property value measurement unit 12 it may be the frequency _{f 2} power supplied to the induction coil 10a and.

Third Embodiment
FIG. 5 is a schematic view of an induction heating apparatus according to a third embodiment of the present invention.
The induction heating apparatus 1 of FIG. 5 is different from that of the first embodiment, and the control unit 14 determines the AC power supply 10 b of the induction heating unit 10 determined by the control unit 14 based on the measurement result of the temperature measurement unit 15. The output condition of the power to be supplied is corrected, in other words, the measurement result of the temperature measurement unit 15 is fed back to the above output condition.

Since the control unit 14 transmits the corrected output condition to the AC power supply 10b of the induction heating unit 10, and the AC power supply 10b supplies power to the induction coil 10a based on the output condition, the induction heating device 1 of this embodiment Even if the steel sheet H is present, the steel sheet H can be inductively heated to a target temperature by the induction coil 10a regardless of the type, composition, and the like of the steel sheet H. Moreover, in the induction heating device 1 of the present embodiment, since the supplied power can be corrected according to the heating result, the steel plate H can be induction heated to the target temperature more reliably.
The feedback control as in this embodiment can also be applied to a configuration in which the shapes of the inspection coil and the induction coil are the same as in the second embodiment.

(Another example of induction heating unit)
In the above example, the induction heating unit is of the LF type in which a magnetic flux substantially parallel to the plate surface of the steel plate is generated by the induction coil and the steel sheet is heated by the induction current generated in the steel plate by the magnetic flux. The induction heating unit is not limited to this example, and a TF (vertical magnetic flux) method of generating a magnetic flux which is substantially perpendicular to the plate surface of the steel plate by the induction coil and penetrates the steel plate and heats the steel plate by the induction current generated in the steel plate by the magnetic flux. It may be

(Another example of inspection coil of physical property value measurement unit)
In the above example, the detection coil of the physical property value measurement unit is an LF type that generates a magnetic flux substantially parallel to the plate surface of the steel plate passing through the physical property value measurement unit when an excitation current is supplied to the coil. . However, the inspection coil is not limited to this example, but a TF type that generates a magnetic flux that is substantially perpendicular to the plate surface of the steel plate passing through the physical property value measurement part and penetrates the steel plate when exciting current is supplied to the coil. The coil may be any coil that generates a magnetic flux when an excitation current is supplied and generates an induced current in a steel plate passing through the physical property value measurement unit.
In the second embodiment, when the TF heating type is employed as the induction heating portion, the TF type measuring coil of the physical property value measuring portion has the same shape as the induction coil of the induction heating portion. The thing is adopted.

(Another example of output from physical property measurement unit to control unit)
In the above example, information on the current flowing to the inspection coil of the physical property value measurement unit is transmitted from the physical property value measurement unit to the control unit, and the control unit calculates the inductance of the inspection coil based on the received information. The output condition of the AC power supply of the induction heating device was determined. The present invention is not limited to this example, and after the physical property value measurement unit calculates / measures the inductance, information on the inductance is transmitted from the physical property value measurement unit to the control unit, and the control unit determines the above output condition based on the inductance. It is also good.

(Another application example of the induction heating device according to each embodiment)
In the above example, the induction heating apparatus according to each embodiment is applied to an apparatus that performs induction heating for manufacturing an alloyed galvanized steel sheet. The steel plate thickness of the alloyed galvanized steel sheet is usually a thin plate of less than 3 mm. However, the induction heating apparatus according to each embodiment may be applied to an apparatus which performs induction heating for heat treatment of a steel plate having a thickness other than that, for example, a thick plate having a thickness of 6 mm or more. Examples of heat treatment for thick plates include hardening and tempering. Moreover, although the induction heating apparatus which concerns on the above each embodiment is applied to the apparatus which induction-heats steel plates, ie, plate-like steel materials, even if applied to the apparatus which induction-heats rod-like steel materials and linear steel materials Good. Furthermore, although the induction heating apparatus which concerns on the above each embodiment is applied to the apparatus which induction-heats strip-like steel materials continuously as strip-like, the cylindrical metal coil which wound up strip-like steel materials cylindrically is used. It may be applied to an apparatus for induction heating on a line. Moreover, the material to be heated of the induction heating device according to each embodiment is not limited to the steel material, and may be another metal material, and not limited to the metal material as long as it has high conductivity. For example, carbon may be used.

The result of induction heating various steel plates using the induction heating device 1 according to the first embodiment is shown in FIG. In addition, below, with steel type A, C: 0.005%, Si: 0.01%, Mn: 0.46%, P: 0.016%, S: 0.005% in mass% And, the balance consists of Fe and unavoidable impurities, and with steel type B, C: 0.03%, Si: 0.02%, Mn: 0.18%, P: 0:% by mass. The content is 012%, S: 0.005%, and the balance is Fe and unavoidable impurities. With respect to steel type C, C: 0.23%, Si: 0.11%, by mass%. Mn: 0.63%, P: 0.034%, S: 0.034%, and the balance consists of Fe and unavoidable impurities. Moreover, the actual temperature in the following description is an average value of the temperature of the steel plate after heating when continuously heating a steel plate having a length of 10 m at a passing speed of 50 m / min, and T _m is the temperature before induction heating It is.

The steel plates of Examples 1 to 3 have a thickness of 0.5 mm, a width of 1800 mm, and a target temperature _Tt of 600 ° C. in common, but have different steel types from steel types A, B, and C.
In Examples 4 and 5, the steel type is steel type A, and the target temperature _Tt is 600 ° C., which is the same as in Example 1. However, the dimensions are different from Example 1. In Example 4, the thickness 0.2 mm × The width was 1000 mm, and in Example 5, the thickness was 1.0 mm × width 900 mm.
In Examples 6 and 7, the steel type is steel type A and the dimension is 0.5 mm thick × 1800 in width, which is the same as in Example 1. However, the target temperature _Tt is different from Example 1, and 700 ° C. in Example 6. In Example 7, it was 800.degree.
Example 8 steel grade, dimensions, the target temperature is same as in Example 1, the temperature T _m of a steel sheet prior to induction heating is different from the first embodiment.

In Comparative Examples 1 to 3, the temperature measurement unit on the downstream side of the induction heating unit 10 is not provided with the conventional method, that is, the physical property value measurement unit 12 such as the induction heating device 1 according to the first embodiment. The induction heating was performed by the method of feedback control based on the measurement result in 15. Moreover, although the steel plates of Comparative Examples 1 to 3 have a thickness of 0.5 mm, a width of 1800 mm, and a target temperature _Tt of 600 ° C. in common, the steel types are different from Steel Type A, Steel Type B, and Steel Type C, respectively.

  As shown in FIG. 6, in Comparative Examples 1 to 3, the difference between the actual temperature and the target temperature was about 15 ° C. regardless of the steel type, and the target temperature could not be achieved by the method of the comparative example. On the other hand, in Examples 1 to 3, the difference between the actual temperature and the target temperature was 1 ° C. regardless of the steel type, and the target temperature could be achieved. That is, in the induction heating device 1 of the first embodiment, the steel plate can be induction heated to the target temperature immediately after induction heating regardless of the steel type.

  In Examples 1, 4 and 5, the difference between the actual temperature and the target temperature was 1 ° C. regardless of the dimensions, and the target temperature could be achieved. That is, in the induction heating device 1 of the first embodiment, the steel plate can be induction heated to the target temperature immediately after induction heating regardless of the dimensions.

  In Examples 1, 6, and 7, the difference between the actual temperature and the target temperature was 1 ° C. regardless of the target temperature, and the target temperature could be achieved. That is, in the induction heating device 1 of the first embodiment, the steel plate can be induction heated to the target temperature immediately after induction heating, regardless of the target temperature.

  In Examples 1 and 8, the difference between the actual temperature and the target temperature was 1 ° C., regardless of the temperature before induction heating, that is, the amount of temperature increase to the target temperature, and the target temperature could be achieved. That is, in the induction heating device 1 of the first embodiment, the steel plate can be induction heated to the target temperature immediately after induction heating, regardless of the temperature before induction heating.

  INDUSTRIAL APPLICABILITY The present invention is useful for the technique etc. for induction heating steel materials being transported in a production line, and particularly useful for the technique etc. for alloying the galvanized layer of hot-dip galvanized steel sheet by induction heating.

DESCRIPTION OF SYMBOLS 1 ... Induction heating apparatus 10 ... Induction heating part 10a ... Induction coil 10b ... AC power supply 11 ... Temperature measurement part 12 ... Physical property value measurement part 12a ... Inspection coil 12b ... AC power supply 13 ... Steel plate information acquisition part 14 ... Control part 15 ... Temperature part Measurement unit 100 ... Continuous galvanizing device

Claims (10)

An induction heating apparatus for induction heating a material to be heated being conveyed on a line by an induction heating unit having an induction coil and an AC power supply that outputs electric power to the induction coil,
A temperature measurement unit provided at a position on the upstream side of the induction heating unit in the line and measuring the temperature of the material to be heated during transport;
A physical property value measurement unit provided at a position on the upstream side of the induction heating unit in the line and measuring a physical quantity related to the physical property value of the material to be heated during transport;
A control unit configured to determine an output condition of power from the AC power supply to the induction coil based on measurement results of at least the temperature measurement unit and the physical property value measurement unit. A steel plate information acquisition unit for acquiring information on at least the dimensions of the material to be heated;
The control unit calculates the physical property value from the physical quantity measured by the physical property value measurement unit, and the measurement result by the temperature measurement unit, the calculated physical property value, and the heated object acquired by the steel plate information acquisition unit The induction heating apparatus according to claim 1, wherein the output condition is determined based on a size of a material.   The physical property value measurement unit has an inspection coil disposed on the line, and calculates, as the physical quantity, an inductance of the test coil when the material to be heated is conveyed in the physical property value measurement unit. The induction heating apparatus according to claim 1 or 2, wherein the physical quantity of or the inductance is measured.   The induction heating apparatus according to any one of claims 1 to 3, wherein the physical property value measuring unit has an inspection coil which is disposed on the line and has the same shape as the induction coil. Another temperature measuring unit provided downstream of the induction heating unit in the line and measuring the temperature of the material to be heated during conveyance after induction heating by the induction heating unit,
The induction heating apparatus according to any one of claims 1 to 4, wherein the control unit corrects the output condition based on a measurement result of the another temperature measurement unit. An induction heating method for induction heating a material to be heated being conveyed on a line by an induction heating unit having an induction coil and an AC power supply that outputs electric power to the induction coil,
A temperature measurement step of measuring the temperature of the material to be heated during conveyance on the line upstream of the induction heating unit;
A physical property value measuring step of measuring a physical quantity related to a physical property value of the material to be heated during conveyance on the line upstream of the induction heating unit;
An induction condition determining step of determining an output condition of power from the alternating current power source to the induction coil based on measurement results at least in the temperature measurement step and the physical property value measurement step. Method. Including a steel plate information acquiring step of acquiring at least information on the dimensions of the material to be heated;
The output condition determination step calculates the physical property value from the physical quantity measured in the physical property value measurement step, and the measurement result in the temperature measurement step, the calculated physical property value, and the information acquired in the steel plate information acquisition step The induction heating method according to claim 6, wherein the output condition is determined based on the dimensions of the material to be heated.   The physical property value measurement step is a physical quantity or a physical quantity for calculating an inductance of the test coil when the material to be heated is conveyed in the physical property value measurement unit having the test coil disposed on the line as the physical quantity. The induction heating method according to claim 6, wherein the inductance is measured.   The physical property value is measured in the physical property value measuring step using an inspection coil having the same shape as the induction coil disposed on the line, according to any one of claims 6 to 8. Induction heating method. Another temperature measurement step of measuring the temperature of the material to be heated after induction heating by the induction heating unit being conveyed on the line downstream of the induction heating unit;
The induction heating method according to any one of claims 6 to 9, further comprising: a correction step of correcting the output condition based on a measurement result in the another temperature measurement step.

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