JP2000040580A - Induction heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely raise temperature of a heating material and to prevent over heating by controlling voltage or conveying speed of a high frequency inverter device based on each data of size of the heating material, the number of the heating materials, and target temperature, until the temperature of the heating material reaches the specified value during the initial heating period soon after operation start. SOLUTION: A heating chamber is divided into heating sections A-E from an inlet 21a to an outlet 25, and corresponding heating coils 21-25 induction-heat a heating material 14 with voltage generated in high frequency inverter devices 31-35. The size of the heating material 14, the number of heating material per minute, and heating temperature are inputted from an input device 16 and stored in a memory of a control device 15, and by inputting by only the number M, data on the heating material is taken out. The control device 15 controls voltage generating in the inverter device of each heating coil so as to become the specified temperature based on the conveying speed material to the next process, data in the memory, and measured temperature. Operation conditions are automatically set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating device used for forging metal.

[0002]

2. Description of the Related Art FIG. 5 schematically shows a circuit configuration of an induction heating apparatus disclosed in Japanese Patent Publication No. 57-23988. In FIG. 5, reference numeral 1 denotes a heating coil, which heats the material to be heated by passing the material through the inside. 2 is a capacitor for improving the power factor of the heating coil, 3
Is a high-frequency inverter device for supplying high-frequency power for induction heating to the heating coil 1, 4 is a transformer for a power supply, and 10 and 11
Is a resistor for setting the voltage generated by the high-frequency inverter device 3, and 12 and 13 are relay contacts.

[0003] This induction heating device (hereinafter referred to as induction heating device)
The operation of is described below. Before the operation of the induction heating device is started, the heating coil 1 is in a state where there is no material to be heated (not shown, but usually a round bar steel material is used). When an operation command is issued to the induction heating device, a transfer command is issued to a not-shown transfer mechanism (constituted by a roller mechanism) for the material to be heated, and at the same time, the high-frequency inverter device 3 starts operating to generate a voltage. . Here, the conveying speed of the material to be heated is set at a value according to the processing tact of the forging press machine, which is a post-process of the induction heating device. It is set at a value corresponding to the input power required to raise the temperature.

[0004] Here, the heating coil 1 is generally formed by forming a refractory such as refractory cement or a heat insulating material on the inner and outer surfaces of a spirally wound copper tube. When the operation of the induction heating device is started, the structure such as the refractory is at room temperature, but as the induction heating device starts operating and the material to be heated passes through the heating coil 1, the material to be heated is heated. The temperature of the refractory rises by receiving radiant heat from the refractory, and after a certain period of time, the temperature of the refractory becomes constant. In the induction heating device for forging, the material to be heated is heated to a temperature of 1200 to 1250 ° C. at the outlet 25 a of the heating coil, but the refractory of the heating coil 1 has a maximum of 700 near the outlet 25 a of the heating coil 1. The temperature is raised to about ° C.

The material to be heated radiates heat to the internal refractory as it passes through the heating coil 1. The higher the temperature of the refractory, that is, the smaller the temperature difference between the material to be heated and the refractory. The lower the radiant energy density becomes. Therefore, when the temperature of the refractory is low, such as when starting the operation of the induction heating device, the radiant energy density of the material to be heated increases.
Further, when the temperature of the refractory increases after a lapse of time from the start of operation of the induction heating device, the radiant energy density from the material to be heated decreases.

As described above, as the radiant energy density is higher, the material to be heated is deprived of heat energy by surrounding refractories and the like, and the radiation causes heat loss to the material to be heated. Therefore, even when a certain amount of electric power is supplied to the heating coil 1, the temperature of the material to be heated after heating is different between the start of the operation of the induction heating device and the steady period in which time has elapsed since the start of the operation. During a certain period from the start of the operation of the apparatus, the degree of temperature rise of the material to be heated decreases, and the temperature increases to a predetermined temperature, for example, 1200 to 1
Temperature may not rise to 250 ° C.

Here, in order to increase the power applied to the heating coil, the voltage applied to the heating coil, that is, the voltage generated by the high-frequency inverter device may be set high, and the power applied to the heating coil is reduced. For this purpose, the voltage applied to the heating coil, that is, the voltage generated by the high-frequency inverter device may be set low.

[0008] Therefore, the conventional method of operating the induction heating device has been performed as follows. First, at the start of operation of the induction heating device, in FIG. 5, in order to increase the power supplied to the heating coil 1, the relay contact 12 is closed and the relay contact 13 is opened to set the reference value of the voltage set in the high-frequency inverter device 3. To enable the resistor 10.
Since the voltage set value of the resistor 10 is set higher than the voltage reference value of the resistor 11, the high-frequency inverter device 3
Occurs, and the electric power supplied to the heating coil 1 increases.

On the other hand, as the material to be heated passes through the heating coil, the temperature of the refractory of the heating coil 1 rises,
Since it is necessary to reduce the electric power supplied to the heating coil 1, the voltage generated by the high-frequency inverter device 3 is reduced. Therefore, the relay contact 12 is opened, the relay contact 13 is closed, and the resistor 11 is enabled. The voltage reference value of the resistor 11 is set lower than the voltage reference value of the resistor 10, and lowers the voltage commanded to the high-frequency inverter device 3.

In this manner, the power supplied to the heating coil 1 at the start of the operation of the induction heating device and the power supplied to the heating coil 1 at the time of the steady operation are changed according to the voltage generated by the high-frequency inverter 3. . Thereby, the temperature difference of the refractory of the heating coil 1 at the start of the operation of the induction heating device is compensated, and the temperature of the material to be heated is maintained as constant as possible. The relay contacts 12 and 13 are controlled by a control circuit composed of a relay. Normally, when the material to be heated reaches the outlet 25a of the heating coil 1, the relay contacts 12 and 13 are opened and the relay contacts 13 are closed. , The power supply path is switched.

[0011]

As described above, in the conventional induction heating apparatus, when the operation of the induction heating apparatus is started, the voltage generated by the high-frequency inverter is temporarily increased to provide the heating coil. While the temperature of the material to be heated can be raised to a predetermined temperature in a state where the temperature of the refractory is low, there are the following problems.

Generally, in one induction heating device,
The material to be heated of several sizes (diameter and length) is heat-treated, but the processing speed, that is, the processing tact or the transport speed varies depending on the type (size, etc.) of each material to be heated. is there. Therefore, the voltage generated by the high-frequency inverter device 3 at the start of the operation of the induction heating device needs to be set to an appropriate value according to the type of the material to be heated.
Since the conventional induction heating device does not have a function of adjusting the generated voltage of the high-frequency inverter device 3 according to the type of the material to be heated, the operator manually adjusts the generated voltage at the start of the operation of the induction heating device. There was a problem that it was necessary to set.

Further, with the recent increase in size of forging presses,
The size of the induction heating device is also increasing, and the number of induction heating devices having three to five high-frequency inverter devices is increasing. In such an embodiment, when the operation of the induction heating apparatus is started, a plurality of high-frequency waves are generated depending on the type (size, etc.) of the material to be heated at that time, the number of pieces processed per unit time, and the heating temperature. In the inverter device, there is a problem that it is difficult to select each voltage set value to an optimum value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the voltage setting of the high-frequency inverter at the start of operation depends on the type of the material to be heated in the induction heating device, the heating conditions, and the like. It is another object of the present invention to provide an induction heating apparatus that automatically sets operating conditions such as a transfer speed of a transfer mechanism.

[0015]

An induction heating device according to the present invention is divided into a plurality of sections along a conveying path of a material to be heated, and a heating coil for inductively heating the material to be heated from a normal temperature to a predetermined temperature; A high-frequency inverter for supplying high-frequency power to each of the heating coils, voltage setting means for setting a voltage generated by the high-frequency inverter, speed setting means for setting a conveying speed of the material to be heated, and a conveying distance of the material to be heated Distance detecting means for detecting the temperature of the material to be heated, and temperature detecting means for detecting the temperature of the material to be heated. And a controller for controlling the voltage or the conveying speed of the high-frequency inverter until the temperature of the heating material reaches a predetermined temperature.

Further, the control device includes storage means for storing and holding the generated voltage and the transport speed of the high-frequency inverter device during the initial heating period corresponding to various types of materials to be heated. The voltage or the transfer speed of the high-frequency inverter is controlled according to the type of the material to be heated.

Further, the control device is characterized by comprising a calculating means for calculating a voltage generated by the high-frequency inverter device and a conveying speed during the initial heating period based on each data of the material to be heated.

Further, the control device terminates the initial heating period when detecting that the transport distance of the material to be heated has reached a predetermined value.

Further, a timer for setting the initial heating period to an arbitrary time is provided.

Further, the control device terminates the initial heating period when detecting that the temperature of the material to be heated detected by the temperature detecting means has reached a predetermined value.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram schematically showing a circuit configuration of an induction heating device according to Embodiment 1 of the present invention. In FIG. 1, 15 is a control device, 1
6 is a data input device for the material to be heated 14, 21 to 2.
5 is a heating coil, 31 to 35 are high frequency inverter devices,
41 to 45 are voltage setting devices as voltage setting means for setting voltages generated by the high frequency inverter devices 31 to 35;
7 is a roller mechanism for transporting the material to be heated 14, 18 is a motor for driving the roller mechanism 17, 19 is a speed command device as speed setting means for giving a speed command to the motor 18, and 20 is the temperature of the material 14 to be heated. A temperature detector 26 detects a rotation amount of the roller mechanism 17 and detects a conveyance distance of the material 14 to be heated based on the rotation amount. is there.

In FIG. 1, the heating section has an inlet 21
from A to the exit 25a is divided into five A to E,
High-frequency inverter devices 31 to 35 are connected to the heating coils 21 to 25, respectively. Here, the voltage generated by the high-frequency inverter devices 31 to 35, that is, the voltage applied to the heating coils 21 to 25 is the same as in the related art, when the temperature of the refractory of the heating coil is low, In order to compensate for the decrease in the temperature of the material to be heated 14, the voltage at the start of operation of the induction heating device needs to be set higher than the steady voltage.

That is, the high frequency inverter devices 31 to 3
The voltage generated by 5 is divided into a voltage at the start of operation of the induction heating device (hereinafter, referred to as an initial voltage) and a voltage during a steady operation of the induction heating device (hereinafter, referred to as a steady voltage). Hereinafter, a period during which the high-frequency inverter devices 31 to 35 are generating the initial voltage is referred to as an initial heating period, and a period during which the steady-state voltage is generated is referred to as a steady heating period (see FIG. 2). In the control device 15 as a voltage setting means, two systems of an initial voltage and a steady voltage are provided as voltage setting values for instructing the high frequency inverter devices 31 to 35.

Next, the operation of the induction heating device will be described. First, a data input device 16 for the material to be heated 14
An external diameter D (mm) and a length L (mm) are input as the size of the material 14 to be heated by a keyboard (in the figure). Further, as the number of processed materials 14 to be heated, the number of processed materials per unit time R (the number of processed materials per minute, unit (spm))
The heating temperature T (° C.) is input as the target temperature.

In this way, the material to be heated (outer diameter D,
The length L, the number of treatments R, and the heating temperature T) are assigned.
Therefore, before the operation is started, each piece of the heated material data is stored in the control device 1 in accordance with the number M representing the type of the heated material 14.
If it is registered in the memory within 5, the heated material data corresponding to the type of the heated material 14 can be extracted from the memory of the control device 15 only by setting the number M.

Here, the tact that the material to be heated is discharged from the induction heating device during the operation of the induction heating device needs to be adjusted to the processing tact of the press device, which is a process to be performed later. The speed needs to be a speed that matches the processing tact of the press device. Therefore, the transport speed S of the material to be heated 14 is calculated by the following equation. S = L × R / 60 (mm / s)

The steady voltages V11 to V15 are set at a predetermined temperature (about 1200 to 12) at the outlet 25a of the induction heating device during the steady heating period of the induction heating device.
A value M that indicates the type of the material to be heated 14 uses a value experimentally predetermined so as to increase the temperature to 50 ° C.).
Are registered in the memory in the control device 15.

Next, the initial voltages V01 to V05 are values obtained by multiplying the steady voltages V11 to V15 by coefficients (K1 to K5 shown in FIG. 3). The coefficients K1 to K5 are experimentally determined and set at values of 1.01 to 1.05. A value obtained by subtracting 1.0 from the values of the coefficients K1 to K5 is used to compensate for a decrease in the temperature of the material to be heated 14 due to the temperature of the refractory of the heating coils 21 to 25 at the start of operation of the induction heating device. It corresponds to the voltage difference.

Since the radiant energy density of the material to be heated 14 is generally proportional to the fourth power of the surface temperature (absolute temperature) of the material to be heated 14, in a section where the temperature of the material to be heated 14 is low,
The radiant energy density from the material to be heated 14 decreases,
The coefficients K1 to K5 may be low values. On the other hand, in the section where the temperature of the material to be heated is high, the radiant energy density from the material to be heated increases, so that the coefficients K1 to K5 may be low. Therefore, in general, K1 ≦ K2 ≦ K3 ≦ K4 ≦ K
5 holds.

The heat loss due to the radiation of the heat energy of the material 14 to be heated in the heating coils 21 to 25
4, the temperature is substantially constant irrespective of the transport speed of the material 14 to be heated. Exit 2 of the conveyance path of the induction heating device
In 5a, in order to obtain a constant heating temperature as the temperature of the material 14 to be heated, the electric power supplied to the heating coils 21 to 25 is reduced when the conveying speed of the material 14 to be heated is low. Therefore, when the conveying speed of the material to be heated 14 is low, the ratio of the heat loss of the material to be heated 14 to the electric power supplied to the heating coils 21 to 25 becomes large. It is necessary to increase the ratio. Conversely, when the conveying speed of the material to be heated 14 is high, the ratio of the heat loss of the material to be heated 14 to the electric power supplied to the heating coils 21 to 25 becomes small. It is necessary to reduce the ratio of the initial voltage to the voltage.

Further, depending on the value of the conveying speed of the material to be heated,
It is also possible to determine the coefficients K1 to K5 of the initial voltage in advance. The initial voltage coefficients K1 to K5 are experimentally determined in consideration of the above conditions, and are stored in the memory in the control device 15 corresponding to the number M of the material to be heated 14.

Next, the actual operation procedure of the induction heating device will be described. The stored steady voltages V11 to V15 and initial coefficients K1 to K5 corresponding to the number M of the material to be heated 14 are extracted, and the initial voltage V01 is calculated by the following equation.
To V05 are calculated. V01 = K1 × V11 V02 = K2 × V12 V03
= K3 × V13 V04 = K4 × V14 V05 = K5
× V15

Next, when the operation of the induction heating device is started,
The motor 18 rotates at the command speed S through the speed command device 19 and drives the roller mechanism 17 to rotate. Roller mechanism 17
Transports the material to be heated 14 to the heating coil 21. Also,
At the same time, the initial voltage V01 is instructed to the high frequency inverter device 31 in section A through the voltage setting device 41, the initial voltage is applied to the heating coil 21, and the initial high frequency power is supplied.

Similarly, the material to be heated 14 is
25 (that is, as the vehicle travels along the transport path), the initial voltage V02 is supplied to the high-frequency inverter devices 32-35 in the BE section through the voltage setting devices 42-45.
To V05. In this way, at the start of operation of the induction heating device, an initial voltage higher than the steady voltage is applied to the heating coils 21 to 25, and even when the temperature of the refractory of the heating coils 21 to 25 is low, the temperature of the material to be heated 14 is reduced. It can be raised to a predetermined value.

The point in time when the voltage changes from the initial voltage to the steady voltage, that is, the end point of the initial heating period, is determined when the tip of the material to be heated 14 reaches the outlet 25 a of the heating coil 25. In this case, the rotation detection mechanism 2 of the roller mechanism 17
In step 6, the number of rotations of the roller is detected, and the controller 15 calculates the transport distance of the material to be heated 14 based on the number of rotations of the roller, and determines the point in time when the material to be heated 14 reaches the outlet 25a of the heating coil 25. .

It is to be noted that, not only the control processing as described above, but also the conveyance distance of the material to be heated 14 is calculated from the time when the material reaches the outlet 25a of the heating coil 25, and it is determined that the material to be heated 14 has been conveyed by a certain distance. It is also possible to detect and shift from the initial voltage to the steady voltage. When such a control process is performed, when all the refractories of the heating coils 21 to 25 have not risen to a steady temperature at the time when the tip of the material to be heated 14 reaches the outlet 25a of the heating coil 25, the initial state is determined. There is an advantage that a heating period can be added.

As described above, when the initial heating period is further added from the time when the tip of the material to be heated 14 reaches the outlet 25a of the heating coil 25, the initial voltage is not the same value but is gradually increased to the steady voltage. Generally, a method of approaching is adopted. In this method, as shown in FIG.
At the beginning of the initial heating period, the initial voltage coefficients K1 to K5 and the initial voltages V01 to V05 are set as described above.
The initial voltage coefficient is lowered when the tip of the material to be heated 14 reaches the outlet 25a of the heating coil 25.

For example, when the value of the coefficient K5 is 1.06, the rate of decrease of the coefficient is reduced, and K5 is set to a value of about 1.04 or 1.02. By performing such a setting, when the temperature of the refractory of the heating coil gradually increases, the danger caused by excessively increasing the temperature of the material to be heated 14 due to an excessively high initial voltage can be eliminated. As shown in FIG. 4, if the voltage applied to the high-frequency inverter devices 31 to 35 is increased stepwise after the end of the initial heating period, the material 14 to be heated can be more efficiently heated.

Embodiment 2 In the first embodiment, the case where the voltage applied to the heating coils 21 to 25 is changed as a method of compensating the temperature of the material to be heated 14 at the start of the operation of the induction heating device is described. In the second embodiment, the applied voltage is changed. Instead, the case where the conveying speed of the material to be heated 14 is changed will be described.

FIG. 2 is a characteristic diagram conceptually showing the operation of the induction heating apparatus according to Embodiment 2 of the present invention. Note that the induction heating device itself is the same as that of the first embodiment (FIG. 1). In order to raise the temperature of the material to be heated 14 when the temperature of the refractory of the heating coil is low at the start of the operation of the induction heating device, in FIG. The energy input to the material to be heated 14 during the passage from to the outlet 25a of the heating coil 25 may be increased.

As means for that purpose, in the first embodiment, the applied voltage applied to the heating coils 21 to 25 is increased. However, if the transport speed is reduced without changing the applied voltage, the transport path of the material 14 to be heated can be reduced. The passage time becomes longer and the heating coil 2
Even if the input power to the heating coils 21 to 25 is constant, that is, the applied voltage supplied from the high-frequency inverter devices 31 to 35 to the heating coils 21 to 25 is constant, the energy input to the material to be heated 14 can be increased.

Hereinafter, the control device 15 according to the second embodiment will be described.
Will be described. As described in the first embodiment, with respect to the calculated transport speed S (steady speed), S0
Calculate the speed (initial speed) at the start of operation of the induction heating device by the formula: KS × S. The coefficient KS is about 0.9
It is a value between 0 and 0.99, and is determined in advance to a value obtained from an experiment or the like. When the operation of the induction heating device is started, the motor 18 is driven at the initial speed S0.

When the tip of the material to be heated 14 reaches the outlet 25a of the heating coil 25, a steady speed S is instructed to the speed command device 19, and the material to be heated 14 is conveyed at a conveying speed suitable for the press device. If the tip of the heated material 14 reaches the outlet 25a of the heating coil 25, it is necessary to carry the material at the steady speed S. The heating period ends.

Embodiment 3 FIG. In the second embodiment, the case where the conveyance distance of the material to be heated 14 is detected as a method of determining the initial heating period at the start of the operation of the induction heating device has been described. The case where the measurement is performed will be described. In the third embodiment, the timer in the control device 15 is counted from the time when the tip of the material to be heated 14 reaches the outlet 25a of the heating coil 25,
The initial heating period is ended when a certain period of time has passed, and the voltage shifts from the initial voltage to the steady voltage.

As described above, according to the third embodiment of the present invention, the time of the initial heating period can be measured by the timer, so that the temperature of the material to be heated 14 can be reliably raised to a predetermined temperature. it can.

Embodiment 4 FIG. In the third embodiment, as a method of determining the initial heating period at the start of the operation of the induction heating device, the case where the transport distance of the material to be heated 14 is detected or the case where the time of the initial heating period is measured has been described. In a fourth embodiment, a case will be described in which the actual temperature of the material to be heated 14 is detected and the operation of the induction heating device is controlled based on the detected voltage.

In the fourth embodiment, the measured value of the temperature detector 20 for detecting the material to be heated 14 at the outlet 25a of the heating coil 25 is determined in the control device 15 and the time when the measured value reaches the predetermined temperature is determined. Ends the initial heating period, and shifts from the initial voltage to the steady voltage. In this control method, since the initial heating period can be determined based on the actual temperature of the material to be heated 14,
There is an advantage that the temperature of the material to be heated 14 can be confirmed to have risen to a predetermined temperature.

Embodiment 5 FIG. In the first to fourth embodiments, the initial voltage coefficients K1 to K5 and the initial speed coefficient KS are experimentally determined in advance, and the number M of the material 14 to be heated is determined.
In the fifth embodiment, the operation control of the induction heating device in the case where the operation is stored in the memory of the control device 15 has been described. In the fifth embodiment, the values of the coefficients K1 to K5 and KS are calculated, and based on the calculation result, A description will be given of a case in which the operation control is performed by the operation.

The following is an example of an equation for obtaining the initial voltage coefficients K1 to K5. Kn = 1 + G × Fn / S Here, n is an integer of 1 to 5, and the coefficient Kn is a coefficient K
1 to K5. S is the steady transport speed of the material to be heated 14, and the lower the transport speed is, the higher the initial voltage coefficient needs to be. Fn is a coefficient K1 to K
This is a constant corresponding to 5. As described above, the higher the temperature of the section, the higher the initial voltage coefficient needs to be. Therefore, F1 <F2 <F3 <F4 <F5 holds for each Fn. G is a coefficient based on the data of the material to be heated.
4 slightly varies depending on the outer diameter and the heating temperature, and is a value determined experimentally.

Next, an example of an equation for obtaining the initial speed coefficient will be shown. KS = 1−H / S S is the steady transport speed of the material to be heated 14, and the lower the transport speed is, the lower the initial speed coefficient needs to be. H is
This coefficient is based on the data of the material to be heated, and varies slightly depending on the outer diameter of the material to be heated 14 and the heating temperature, and is determined experimentally. In addition,
Since the value of the coefficient KS needs to be 1.0 or less, H ≦ S
Holds. The values of these coefficients K1 to K5 and KS are calculated and automatically set in the control device 15.

Embodiment 6 FIG. In the first to fifth embodiments, the number of sections is five (five high-frequency inverter devices).
However, in the induction heating device requiring a large amount of power, the number of high-frequency inverter devices may be six or more. Further, in an induction heating device requiring relatively small power, the number of high frequency inverter devices may be four or less, for example, one. The present invention can be implemented similarly to the first and second embodiments even when the number of high-frequency inverter devices is six or more or four or less.

[0052]

The induction heating apparatus according to the present invention is divided into a plurality of sections along the conveying path of the material to be heated, and a heating coil for inductively heating the material to be heated from room temperature to a predetermined temperature; High-frequency inverter for supplying high-frequency power to the power supply, voltage setting means for setting the voltage generated by the high-frequency inverter, speed setting means for setting the conveying speed of the material to be heated, and conveyance for detecting the conveying distance of the material to be heated. Distance detection means, temperature detection means for detecting the temperature of the material to be heated, and the temperature of the material to be heated during the initial heating period immediately after the start of operation, based on the data of the size of the material to be heated, the number of treatments, and the target temperature. And a control device for controlling the voltage or the conveying speed of the high-frequency inverter until the temperature reaches a predetermined temperature. The adverse effects caused can be eliminated.

Further, the control device includes storage means for storing and holding the generated voltage and the transport speed of the high-frequency inverter device during the initial heating period corresponding to various types of materials to be heated. It controls the voltage or transfer speed of the high-frequency inverter device according to the type of material to be heated, so the data (outer diameter, length, number of processes, heating temperature) related to the material to be heated is controlled from the input device. Based on the input data, when the refractory temperature of the heating coil is low, the initial voltage at the start of operation of the induction heating device is set from a registered value, and a command is sent to the high-frequency inverter device of each section. Can be put out. Therefore, an optimal initial voltage can be set according to the diameter, length, number of treatments, and heating temperature of the material to be heated, and the temperature of the material to be heated can be raised to a predetermined temperature. When controlling the transport speed of the heated material, when the refractory temperature of the heating coil is low, the transport speed of the heated material is set to be low, and the energy input to the heated material during the initial heating period is reduced. In order to increase the size, the material to be heated can be raised to a predetermined temperature.

Further, the control device is provided with a calculating means for calculating the generated voltage and the conveying speed of the high-frequency inverter device during the initial heating period based on each data of the material to be heated. In addition, the temperature of the material to be heated can be increased efficiently.

Further, when the control device detects that the transport distance of the material to be heated has reached a predetermined value, the control device terminates the initial heating period.
The material to be heated can be efficiently heated.

Further, since a timer for setting the initial heating period to an arbitrary time is provided, the temperature of the material to be heated can be increased more reliably and efficiently.

Further, when the control device detects that the temperature of the material to be heated detected by the temperature detecting means has reached a predetermined value, the control device terminates the initial heating period. The material to be heated can be efficiently heated.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a circuit configuration of an induction heating device according to Embodiment 1 of the present invention.

FIG. 2 is a characteristic diagram conceptually showing operation contents of an induction heating device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a control circuit in a control device according to Embodiment 3 of the present invention.

FIG. 4 is a characteristic diagram conceptually showing operation contents of an induction heating device according to a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional induction heating device.

[Explanation of symbols]

15 control device, 19 speed command device (speed setting means), 20 temperature detector (temperature detecting means), 21 to 25
Heating coil, 26 rotation detection mechanism (transport distance detection means), 31 to 35 High frequency inverter device, 41 to 45
Voltage setting device (voltage setting means).

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhide Suetsugu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3K059 AA08 AB08 AB19 AB24 AB26 AC03 AC09 AC33 AC37 AC44 AC54 AC69 AD02 AD13 BD02 CD03

Claims (6)

[Claims] 1. A heating coil which is divided into a plurality of sections along a conveying path of a material to be heated and inductively heats the material to be heated from a normal temperature to a predetermined temperature, and supplies high-frequency power to each of the heating coils. A high-frequency inverter device; voltage setting means for setting a voltage generated by the high-frequency inverter device; speed setting means for setting the transport speed of the material to be heated; and transport distance detecting means for detecting a transport distance of the material to be heated. A temperature detecting means for detecting the temperature of the material to be heated, and a temperature of the material to be heated is determined during the initial heating period immediately after the start of operation based on the data of the size of the material to be heated, the number of treatments, and the target temperature. A control device that controls the voltage of the high-frequency inverter device or the transport speed until the temperature reaches a temperature. 2. The control device according to claim 1, further comprising a storage unit configured to store and hold a voltage generated by the high-frequency inverter device and the transport speed during the initial heating period corresponding to various types of materials to be heated. The induction heating device according to claim 1, wherein the voltage of the high-frequency inverter device or the transfer speed is controlled in accordance with the type of the material to be heated input to the device. 3. The control device according to claim 1, further comprising a calculating unit configured to calculate a voltage generated by the high-frequency inverter device and the transport speed during the initial heating period based on each data of the material to be heated. The induction heating device according to claim 1. 4. The induction heating apparatus according to claim 1, wherein the control device terminates the initial heating period when detecting that the transport distance of the material to be heated has reached a predetermined value. 5. The induction heating apparatus according to claim 1, further comprising a timer for setting the initial heating period to an arbitrary time. 6. The apparatus according to claim 1, wherein the control device terminates the initial heating period when detecting that the temperature of the material to be heated detected by the temperature detecting means has reached a predetermined value. An induction heating device as described.