JP2010111886A - Heat treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a heating apparatus is upsized as a whole and is made high in cost since a plurality of power units are provided conventionally in the heating apparatus for heating a material to be heated with a plurality of heating methods. <P>SOLUTION: The heat treatment apparatus 1 for the materials 2 to be heated is provided with: a preheating part 11 for heating the material 2 to be heated to a predetermined pre-heating temperature Ta by an electric heating which performs the heating by flowing the electric current through the material 2 to be heated; a heating part 12 for heating the material 2 to be heated to a predetermined heating temperature Tb by a high frequency induction heating which performs the heating by inserting the material 2 to be heated into the inside of a high frequency coil 22, to which the electric power is fed, after preheating the material 2 to be heated in the pre-heating part 11; a power unit 14 capable feeding the electric power to the pre-heating part 11 and the heating part 12; and a switch 15 for switching a power feeding destination from the power unit 14 into the pre-heating part 11 or the heating part 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat treatment method and apparatus for heating an object to be heated by energization heating and high frequency induction heating.

  Conventionally, as a method of heating an object to be heated such as a billet, which is an object to be subjected to a heat treatment such as annealing or quenching, it is made by inserting the object to be heated inside a high-frequency coil. High-frequency induction heating, combustion heating that heats the object to be heated by a combustion flame such as a burner, resistance heating that heats the object to be heated by a heating element such as a heater that generates heat by passing an electric current, and current to the object to be heated Various heating methods such as energization heating that heats by flowing are known.

As shown in FIG. 4, the heating methods have different characteristics.
In other words, high-frequency induction heating has a high heating rate and can rapidly heat the object to be heated, and also has high uniform heating properties and can uniformly heat the object to be heated. It is characterized by low energy efficiency.
Combustion heating is characterized by excellent uniform heating properties and high energy efficiency, but has a low heating rate and takes a long time to heat an object to be heated.
In addition, resistance heating is also excellent in uniform heatability and high energy efficiency, but has a feature that it takes a long time to heat an object to be heated because the heating rate is low.
Furthermore, the electric heating is characterized by high energy efficiency and high heating speed, but low uniform heating property, and it takes time to heat the object to be heated to a uniform temperature as a whole. .

As described above, each heating method has various characteristics. For example, high-frequency induction heating has a high heating rate, so it is preferable when heating an object to be heated rapidly. Is disadvantageous to other heating methods.
Therefore, for example, when heating an object to be heated such as a billet made of a magnetic material, heating is performed by high-frequency induction heating in the temperature range until the temperature of the object to be heated reaches the Curie point. In a temperature range exceeding the point, heating of an object to be heated is performed by combining a plurality of heating methods such as using combustion heating.
When heating an object to be heated by combining high-frequency induction heating and combustion heating, combustion heating is more energy efficient, so it is possible to improve energy efficiency compared to heating only by high-frequency induction heating It is.
When heating by high frequency induction heating, heating at a temperature below the Curie point is slightly more energy efficient than heating at a temperature above the Curie point, but is still highly energy efficient compared to other heating methods. However, since the temperature range from room temperature to the Curie point where heating is performed by high frequency induction heating is larger than the temperature range from the Curie point to the target heating temperature, high frequency induction is performed as described above. Even when heating and combustion heating are combined, the overall ratio of heating by high-frequency induction heating is large, and it cannot be said that the energy efficiency is sufficiently improved.
In addition, since combustion heating is high in energy efficiency but low in heating rate, it is difficult to sufficiently satisfy the demand for rapidly heating an object to be heated.

Therefore, in order to further improve the energy efficiency and increase the heating rate, a heating method is performed in which an object to be heated is preheated to a predetermined temperature by electric heating and then heated to a target heating temperature by high frequency induction heating. Yes.
In this case, since electric heating is high in energy efficiency and high in heating rate, by setting the preheating temperature close to the target heating temperature, the object to be heated can be rapidly heated to near the target heating temperature with high energy efficiency. it can.
In addition, after preheating, the object to be heated is heated quickly and uniformly to the target heating temperature by high frequency induction heating, but the temperature rise by high frequency induction heating is not so large, so less energy is consumed, Therefore, it is possible to heat the object to be heated at high energy efficiency.
That is, as shown in FIG. 4, the heating method in which the object to be heated is preheated by electric heating and then heated to the target heating temperature by high frequency induction heating has high characteristics of energy efficiency, heating rate, and uniform heating property. It has the characteristics.
In addition, the heating method which heats a to-be-heated material by high frequency induction heating after heating by an electrical heating is described in patent document 1, for example.
JP 2007-324209 A

As described above, when an object to be heated is preheated to a predetermined temperature by electric heating, and then heated to a target heating temperature by high frequency induction heating, an electric heating apparatus that performs electric heating and high frequency induction heating that performs high frequency induction heating Although the apparatus is used, the energization heating device is provided with a power supply device that supplies power to an object to be heated, and the high-frequency induction heating device is provided with a power supply device that supplies power to a high-frequency coil. Yes.
As described above, a heating apparatus that heats an object to be heated by a plurality of heating methods includes a plurality of power supply apparatuses such as a power supply apparatus for energization heating and a power supply apparatus for high frequency induction heating. The overall size of the device has increased and the cost has increased.

  Therefore, in the present invention, using a heating device that is reduced in size and configured at low cost, preheating by current heating and heating to a target heating temperature by high frequency induction heating are performed on the object to be heated, and the object to be heated is heated. It is an object of the present invention to provide a heat treatment method and apparatus capable of heating an object at high speed with high energy efficiency.

The heat treatment method and apparatus for solving the above problems have the following characteristics.
That is, according to a first aspect of the present invention, there is provided a heat treatment method for an object to be heated, wherein the object to be heated is subjected to predetermined heating by energization heating in which power is supplied from a power supply device and current is supplied to the object to be heated. A preheating step for heating to a preheating temperature, and after the preheating step, the object to be heated is predetermined by high frequency induction heating in which the object to be heated is inserted into a high frequency coil supplied with power from a power supply device. A heating step of heating to a heating temperature, and switching power supply destinations from a common power supply device between power supply for energization heating in the preheating step and power supply for high-frequency induction heating in the heating step. Do.

  In addition, according to a heat treatment apparatus for an object to be heated according to claim 2, a preheating unit that heats the object to be heated to a predetermined preheating temperature by energization heating that heats the object to be heated by passing an electric current. And after preheating the object to be heated in the preheating unit, the object to be heated is heated to a predetermined heating temperature by high frequency induction heating in which the object to be heated is inserted into a high frequency coil supplied with power. A heating unit for heating, a power supply device that enables power supply to the preheating unit and the heating unit, and a switching tool that switches a power supply destination from the power supply device to the preheating unit and the heating unit.

  According to the present invention, even in a heat treatment apparatus that heats an object to be heated by a plurality of heating methods, the object to be heated can be heated only with a single power supply device. In addition, it is possible to reduce the size and to configure at a low cost.

  Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

The heat treatment apparatus 1 shown in FIG. 1 heats the object to be heated 2 to a predetermined preheating temperature by energization heating that heats the object to be heated 2 by applying an electric current to the object to be heated. A heating device that heats the object to be heated 2 to a predetermined heating temperature by high-frequency induction heating in which the object to be heated 2 is inserted and heated inside a high-frequency coil 22 that is supplied with power, A preheating unit 11 that heats the object to be heated 2 to a predetermined preheating temperature by the energization heating, and after the object to be heated 2 is preheated by the preheating part 11, the object to be heated 2 is predetermined by the high frequency induction heating. A heating unit 12 that heats to a heating temperature, a conveyance path 13 that conveys the object to be heated 2, a power supply device 14 that supplies power to the preheating unit 11 and the heating unit 12, and a power supply destination from the power supply device 14 Preheat And a changeover switch 15 for switching on and 11 and the heating portion 12.
Moreover, the said heat processing apparatus 1 is used in order to heat this to-be-heated material 2, for example, when performing heat processing, such as annealing and hardening with respect to the to-be-heated material 2. FIG.

As the object 2 to be heated, for example, a billet made of a magnetic material formed in a cylindrical shape is used. As a material which comprises the to-be-heated material 2, specifically, materials, such as iron, nickel, a ferrite, are used, for example.
Electrodes 2a and 2b are formed at both ends of the object to be heated 2, respectively.

The preheating unit 11 heats the object to be heated 2 to a predetermined preheating temperature by passing an electric current through the object to be heated 2 disposed in the preheating part 11. In the preheating part 11, The preheating part power supply lines 16 and 16 connected to the power supply device 14 are connected to the electrodes 2a and 2b of the object to be heated 2, respectively.
By supplying power from the power supply device 14 to the object to be heated 2 through the preheating part power supply lines 16 and 16 connected to the electrodes 2a and 2b, an alternating current can be supplied to the object to be heated 2. It has become.
By supplying an alternating current to the object to be heated 2, the object to be heated 2 generates heat due to its own electrical resistance and is heated by this.

The heating unit 12 is configured by arranging a high-frequency coil 22 inside a heating furnace 21, and both ends 22 a and 22 b of the high-frequency coil 22 are supplied with power for a heating unit connected to the power supply device 14. Lines 17 and 17 are connected to each other.
The high frequency coil 22 is made of a metal material such as a copper material, for example.
In the heating unit 12, the power from the power supply device 14 is supplied to the high frequency coil 22 through the heating unit power supply lines 17 and 17 with the article 2 to be heated inserted inside the high frequency coil 22. By supplying an alternating current, the object to be heated 2 is heated by high frequency induction.

The power supply device 14 generates and outputs a predetermined AC voltage using the AC signal generated in the transmission circuit 14a, and the output AC voltage is to be heated 2 disposed in the preheating unit 11, In addition, it can be applied to the high-frequency coil 22 of the heating unit 12.
The change-over switch 15 can selectively switch the application destination of the AC voltage output from the power supply device 14 to either the preheating unit 11 or the heating unit 12.
That is, the changeover switch 15 has a function of selectively switching the power supply destination from the power supply device 14 between the preheating unit 11 and the heating unit 12.

In the heat treatment apparatus 1 configured as described above, the heat treatment for the article to be heated 2 is performed as follows.
First, the object to be heated 2 is arranged in the preheating part 11, and the power supply lines 16 and 16 for the preheating part are connected to the electrodes 2 a and 2 b of the object to be heated 2.
In addition, arrangement | positioning to the preheating part 11 of the to-be-heated material 2 is performed by conveying the to-be-heated material 2 from the other part to the preheating part 11 by the said conveyance path 13, for example.

Next, the changeover switch 15 is switched so that the power supply destination from the power supply device 14 is the preheating unit 11, and the power supply from the power supply device 14 is supplied to the heated object 2 to which the power supply lines 16 and 16 are connected. The heated object 2 is heated by energization heating.
As shown in FIG. 2, the electric heating is performed until the object to be heated 2 reaches a predetermined preheating temperature Ta. When the object to be heated 2 reaches the preheating temperature Ta, the power supply 14 supplies power to the object to be heated 2. The power supply lines 16 and 16 are removed from the object to be heated 2, and the object to be heated 2 is conveyed to the heating unit 12 through the conveyance path 13.

In addition, as shown in FIG. 3, since heat escapes from the electrodes 2a and 2b connected to the power supply lines 16 and 16 at both ends of the object to be heated 2 that is energized and heated by the preheating unit 11, the energization is performed. The heated article 2 to be heated is heated non-uniformly such that the central part is at a high temperature and both end parts are at a lower temperature than the central part.
In addition, when the object to be heated 2 is formed in a shape in which the cross-sectional area between the electrodes 2a and 2b differs depending on the location, the current density of the flowing current differs depending on the cross-sectional area of the object 2 to be heated. The thing 2 will be heated unevenly.

After the energization heating to the object to be heated 2 is finished, while the object to be heated 2 is conveyed from the preheating part 11 to the heating part 12, the object to be heated 2 is not heated, so the temperature gradually increases from the preheating temperature Ta. descend.
In this case, in the object to be heated 2, the heat of the central part, which is relatively high, moves to both ends where the temperature is relatively low, and the temperature in the object to be heated 2 is made uniform. Progresses.

When the object to be heated 2 is conveyed to the heating unit 12 and inserted into the high frequency coil 22 of the heating unit 12, the changeover switch 15 is set so that the power supply destination from the power supply device 14 becomes the heating unit 12. And an AC voltage is applied to the high-frequency coil 22 from the power supply device 14 through the heating part power supply lines 17 and 17.
As a result, an alternating current flows through the object to be heated 2, an alternating current flows through the high frequency coil 22, a magnetic field is generated, and an eddy current in a direction that cancels the generated magnetic field in the heated object 2 inserted into the high frequency coil 22. Flows. As the eddy current flows, the object to be heated 2 generates heat due to the electric resistance of the object to be heated 2 and is heated.

In this way, the object to be heated 2 is subjected to high-frequency induction heating in the heating unit 12 and heated to the target heating temperature Tb.
Since high-frequency induction heating has a high heating rate and high uniform heating property, the object to be heated 2 can be quickly heated to the heating temperature Tb, and the temperature in the object to be heated 2 that has been made uniform to some extent at the time of conveyance can be made even more uniform. Heating is possible.

The preheating temperature Ta can be appropriately set to a desired temperature. For example, the preheating temperature Ta can be set to substantially the same temperature as the heating temperature Tb.
When the preheating temperature Ta is set to substantially the same temperature as the heating temperature Tb, the object to be heated 2 is reduced by an amount corresponding to the temperature that has decreased during the conveyance of the object to be heated 2 (strictly, during the conveyance and at the start of high frequency induction heating) If the object to be heated 2 is heated to the heating temperature Tb by heating by high frequency induction heating, the temperature increase width due to the high frequency induction heating of the object to be heated 2 can be reduced.

In this way, the object 2 is preheated to a preheating temperature Ta that is substantially the same temperature as the heating temperature Tb by energization heating with high energy efficiency, and the temperature increase width due to high frequency induction heating with low energy efficiency is reduced. Therefore, it is possible to heat the object to be heated 2 with high energy efficiency.
In addition, heating to the target heating temperature Tb after preheating is performed by high-frequency induction heating with a high heating rate and high uniform heating property, so that the object to be heated 2 preheated unevenly by energization heating can be rapidly and uniformly obtained. It is possible to heat.

The heating temperature Tb can be set to 1100 ° C., for example, and the preheating temperature Ta can be set to a temperature in the vicinity of 1100 ° C., which is substantially the same temperature as the heating temperature Tb.
In this case, the preheating temperature Ta does not have to be strictly set to the same temperature as the heating temperature Tb, and may be set to a slightly lower temperature or a higher temperature than the heating temperature Tb.

  In addition, when the heating temperature Tb of the object to be heated 2 is set to 1100 ° C., if the object to be heated 2 is heated to the heating temperature Tb only by high frequency heating, about 2.1 Kwh of power is consumed. When the object to be heated 2 is preheated by current heating as in the apparatus 1 and then heated to the heating temperature Tb by high frequency heating, the power consumption becomes about 1.1 Kwh, and the object 2 is heated. It can be seen that the object to be heated 2 can be heated with approximately half of the power consumed when only high-frequency heating is used.

Further, in the present heat treatment apparatus 1, the power supply from the power supply device 14 to the preheating unit 11 and the heating unit 12 can be selectively switched by the changeover switch 15, and the heated object 2 is energized in the preheating unit 11. When heating, the change-over switch 15 is switched so that the power supply destination from the power supply device 14 is the preheating unit 11, and then the power supply destination from the power supply device 14 is high-frequency induction heated in the heating unit 12. The changeover switch 15 is switched so as to become the heating unit 12.
Thereby, it is possible to perform both the energization heating in the preheating part 11 and the high frequency induction heating in the heating part 12 by one power supply device 14.
Therefore, even in the heat treatment apparatus 1 that heats the object to be heated 2 by a plurality of heating methods, the object to be heated 2 can be heated only by providing one power supply device 14. It becomes possible to reduce the overall size and to reduce the cost.

It is the schematic which shows a heat processing apparatus. It is a figure which shows a temperature profile when heating a to-be-heated material with a heat processing apparatus. It is a figure which shows the temperature distribution of the to-be-heated material heated by electrical heating. It is a figure which shows the characteristic of a some heating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 2 To-be-heated object 2a * 2b Electrode 11 Preheating part 12 Heating part 13 Conveyance path 14 Power supply device 14a Oscillator 15 Changeover switch 16 Power supply line for preheating parts 17 Power supply line for heating parts 21 Heating furnace 22 High frequency coil Ta Preheating temperature Tb Heating temperature

Claims (2)

A heat treatment method for an object to be heated,
A preheating step of heating the object to be heated to a predetermined preheating temperature by energization heating in which power is supplied by supplying power from a power supply device and flowing current to the object to be heated;
After the preheating step, a heating step of heating the heated object to a predetermined heating temperature by high-frequency induction heating in which the heated object is inserted into a high-frequency coil supplied with power from a power supply device and heated. Prepared,
Power supply for energization heating in the preheating step and power supply for high frequency induction heating in the heating step are performed by switching a power supply destination from a common power supply device.
The heat processing method characterized by the above-mentioned. A heat treatment apparatus for an object to be heated,
A preheating unit that heats the object to be heated to a predetermined preheating temperature by energization heating that heats the object by flowing an electric current;
After preheating the object to be heated in the preheating unit, the object to be heated is heated to a predetermined heating temperature by high frequency induction heating in which the object to be heated is inserted into a high frequency coil supplied with power and heated. A heating unit;
A power supply device capable of supplying power to the preheating unit and the heating unit;
A switching tool for switching a power supply destination from the power supply device to a preheating part and a heating part,
The heat processing apparatus characterized by the above-mentioned.

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