JPWO2018101436A1 - Method of producing heat-treated metal sheet, and heat treatment apparatus - Google Patents

Abstract

After the process A which starts heating of the metal plate by induction heating and the process A, the temperature Y of the place X at the lowest temperature of the metal plate becomes the specific value Z based on the Curie temperature by the induction heating A method for producing a heat-treated metal sheet, comprising: a step B for heating the metal plate; and a step C for starting heating of the metal plate by light heating after the temperature Y reaches a specific value Z.

Description

  The present invention relates to a method of manufacturing a heat-treated metal plate, and a heat treatment apparatus.

  BACKGROUND ART In recent years, high-strength steel sheets having increased toughness by heat treatment have been used from the viewpoint of weight reduction of vehicles and improvement in safety at the time of collision. As a method of forming such a high strength steel plate, a forming method called hot pressing has been put to practical use. Hot pressing is a method of forming a steel plate while hardening it by pressing a steel plate heated to 900 ° C. to 1000 ° C. with a mold at normal temperature, and using this method, the steel plate strength can be enhanced. it can.

  As a method of heating a steel plate to a 900 ° C. to 1000 ° C. range, conventionally, electric heating (see, for example, Patent Document 1), induction heating (see, for example, Patent Document 2), light heating by infrared rays (see, for example, Patent Document 3) There is a method such as).

  The electric heating is a method of heating by Joule heat generated inside the work by attaching electrodes to both ends of a steel plate and applying a current between the electrodes.

  Induction heating is a method in which a high frequency current is caused to flow in a coil to generate a magnetic field to apply a magnetic flux to a steel plate, and heating is performed by Joule heat due to the eddy current generated inside the steel plate.

Japanese Patent Laid-Open No. 2002-18531 JP, 2005-122983, A JP, 2011-099567, A

  However, in principle, it is difficult to uniformly heat the entire steel plate without temperature unevenness in a heating method by electric current heating or induction heating. In particular, in recent years, the shapes of steel plates are various, and different-shaped steel plates (steel plates that are not rectangular plates) with partially acute-angled portions etc., or differential thick steel plates (for example, Tailored blanks, see JP 2013-184221 A). Uniform heat treatment to such a steel plate is even more difficult, and it is difficult to suppress temperature unevenness. For example, in the electric heating, if the cross-sectional area and the plate width of the steel plate between both electrodes are not constant, in principle, it can not be uniformly heated, and temperature unevenness occurs. Also, in induction heating, if there is a portion with a different thickness, such as a differential thickness steel plate, temperature rise is difficult in the thick part while temperature rise is easy in the thin part, so temperature unevenness due to temperature rise rate difference occurs Do. And if temperature nonuniformity occurs, the strength of the steel plate after hot pressing will vary, and the problem that a predetermined quality can not be obtained will arise. For example, there is a problem that a crack is generated at a partially heated portion, or a problem that hardening at a portion where heating is insufficient is not properly performed, resulting in a decrease in strength.

  On the other hand, in the light heating by infrared rays, it is possible to take measures to suppress the occurrence of temperature unevenness to some extent. For example, among a plurality of light heating lamps, the output of a lamp that heats a portion of the steel plate that easily heats up (for example, a portion with a small thickness in the case of a differential thickness steel plate) is weaker than other lamps. There is a method of controlling the output of each light heating lamp. Another example is a method of arranging a plurality of lamps in an arrangement suitable for the shape of a workpiece.

  The present inventors arrange a differential thick steel plate (a differential thick steel plate having a shape as shown in FIGS. 2A and 2B) having a portion with a thickness of 3.2 mm and a portion with a thickness of 1.6 mm in a plurality of matrixes. In the test which heats from normal temperature (25 ° C) to near 1000 ° C using a light heating lamp, examination which controls temperature nonuniformity has been performed until now. As a result, the temperature of the 3.2 mm thick portion is 900 ° C., assuming that the output of the lamp heating the 3.2 mm thick portion and the lamp heating the 1.6 mm thick portion is the same. While the temperature difference with the 1.6 mm thick part was about 230 ° C at the time of reaching the point, the output of the lamp heating the 1.6 mm thick part was 3.2 mm thick If the temperature of the 3.2 mm thick part reaches 900 ° C, the temperature difference with the 1.6 mm thick part is approximately 90 ° C when dropped in a specific manner than the lamp to be heated Has succeeded in suppressing.

  In the heat-treated metal sheet, it is desirable that the temperature unevenness be as small as possible. Moreover, in the metal plate heat-treated in recent years, the further improvement of a temperature nonuniformity is requested | required.

This invention is made in view of the subject mentioned above, The objective provides the manufacturing method of the heat-treated metal plate which can suppress more the temperature nonuniformity at the time of heating metal plates, such as a steel plate. It is to do.
Another object of the present invention is to provide a heat treatment apparatus capable of further suppressing temperature unevenness when heating a metal plate such as a steel plate.

  The present inventors diligently studied a method of further suppressing temperature unevenness. As a result, it is thought that it is possible to further suppress temperature unevenness when heating a metal plate such as a steel plate by adopting the following configuration, and the present invention has been completed.

That is, the method for producing a heat-treated metal sheet according to the present invention
Process A which starts heating of the metal plate by induction heating,
A step B of heating the metal plate by the induction heating until the temperature Y of the lowest temperature portion X of the metal plate becomes a specific value Z based on the Curie temperature after the step A;
And C. starting the heating of the metal plate by light heating after the temperature Y reaches the specific value Z.

The Curie temperature is a temperature (for example, around 770 ° C. for iron) at which the magnetism of the magnetic substance is lost above the temperature.
According to the above configuration, after the heating of the metal plate by induction heating is started, the temperature Y of the place X at the lowest temperature of the metal plate is a specific value Z based on the Curie temperature (e.g. The heating of the metal plate by the induction heating is performed until the temperature reaches 5 ° C.) (step B).
The portion of the metal plate which is likely to be heated reaches the Curie temperature earlier than the portion X which is difficult to be heated. Here, the portion X which is difficult to be heated is formed, for example, in a region of low magnetic flux density in the induction heating device. However, when the Curie temperature is reached, the magnetism is lost, so induction heating does not further heat it. Therefore, even if induction heating is continuously performed, the temperature does not largely change from the Curie temperature. Therefore, induction heating is performed until the temperature Y of the portion X reaches the specific value Z, but the easily heated portion is maintained near the Curie temperature, and the temperature does not substantially rise. On the other hand, the portion X is also heated to the specific value Z by induction heating while the portion that is likely to be heated is maintained without raising the temperature near the Curie temperature.
As a result, when the temperature Y of the place X reaches the specific value Z, the temperature difference between the place which is most likely to be heated and the place (the place X) which is most difficult to heat is the difference between the Curie temperature and the specific value Z It becomes degree. For example, in the case of a steel plate, when the easily heated portion reaches a specific value Z (for example, a temperature 5 ° C. lower than the Curie temperature: 765 ° C.), the other portions have the Curie temperature (770 ° C.) Therefore, at the time when the temperature reaches around the Curie temperature (around 770 ° C.), the temperature deviation (the temperature difference between the place with the lowest temperature and the place with the highest temperature) over the entire steel plate is the Curie temperature and the specific value Z (In this example, about 5 ° C.).
Then, at this timing, that is, at the timing when the temperature Y reaches the specific value Z, heating of the metal plate by light heating is started (step C). Thereby, light heating is started from around the Curie temperature. Since the light heating is started after the temperature deviation is reduced near the Curie temperature, the temperature deviation at the time when the desired temperature (for example, 1000 ° C.) is reached can be reduced. That is, at the specific value Z (around 770 ° C.), there is almost no temperature non-uniformity, and the temperature rise from that point to the desired temperature (eg, 1000 ° C.) (eg, 1000 ° C.-770 ° C. = 230 ° C. rise) Because of this, temperature unevenness is unlikely to occur.
According to the present inventors, the temperature of the 3.2 mm thick portion is 900 in the test using the above-described difference thick steel plate having the 3.2 mm thick portion and the 1.6 mm thick portion. The temperature difference with the portion of 1.6 mm in thickness at the time when the temperature is reached can be suppressed to about 40 ° C.
As mentioned above, according to the said structure, even if it is a metal plate of what kind of shape, such as a metal plate (a metal plate which is not a rectangular plate shape) and a metal plate which has a part from which thickness differs, temperature unevenness at the time of heating Can be further suppressed.
Although the heating rate decreases, the power is increased on the power supply side, a transverse heating device is used as the induction heating device, the frequency of the current flowing through the induction coil is increased, and the number of turns of the induction coil is increased. It is possible to heat above the Curie temperature by induction heating by measures such as However, in the present invention, the configuration is not such that the temperature is heated to the Curie temperature or more by induction heating, and the temperature is not increased further around the Curie temperature. For example, there is a configuration in which heating above the Curie temperature is limited by the device configuration of the induction heating device, the setting of the frequency of the current flowing through the induction coil, the setting of the heating condition of the induction heating, and the like. Specifically, a device without a function or control capable of changing power or frequency necessary for heating above the Curie point or a device with a normal induction coil without using a transverse device etc. may be mentioned. . Thereby, temperature nonuniformity suppression becomes possible in the Curie temperature vicinity. Also, there is an advantage that the apparatus can be made simpler than the apparatus conventionally used for heating a metal plate.

  In the above-mentioned configuration, the step C may be a step of starting heating of the metal plate by light heating after a predetermined period has elapsed from the step A.

  For example, when heating metal plates of the same material and shape with a line or the like, as long as the induction heating conditions are the same, the temperature Y of the portion X after the induction heating is started in each induction heating step is the specific value Z The period until becoming is approximately the same. Therefore, for example, if the time from when induction heating is started using a sensor to when the temperature Y at the point X reaches the specific value Z is measured in advance, induction is performed when heating is actually performed using a line or the like. The timing at which the temperature Y becomes the specific value Z can be grasped by measuring only the elapsed period from the start of heating. Therefore, if the timing to start the step C, that is, the elapsed time from the step A (the predetermined period) is determined based on the elapsed period measured in advance, the temperature of the metal plate is detected Even without measurement, it is possible to start heating by light heating at an appropriate timing.

In the above configuration, the process B includes a process B-1 of monitoring the temperature Y of the place X during the process B,
The step C may be a step of starting heating of the metal plate by light heating after the monitored temperature Y becomes the specific value Z.

  If the process B-1 which monitors the temperature Y of the said location X is provided during the said process B, the timing from which the said temperature Y turns into the said specific value Z can be grasped | ascertained reliably. As a result, heating of the metal plate by light heating can be reliably started after the temperature Y reaches the specific value Z. For example, in the case of heating a plurality of metal plates different in material or shape (in the case of heating a large number of types of metal plates little by little), the method is more effective.

The heat treatment apparatus according to the present invention is
An induction heating coil for heating the metal plate by induction heating;
And a light source for light heating the metal plate,
The induction heating coil has a heating space in which a metal plate can be installed.
The light source includes a light emitting unit that emits light.
The light emitting unit is disposed inside the induction heating coil.

  According to the said heat processing apparatus, it can use suitably for the manufacturing method of the said heat treated metal plate.

In the heat treatment apparatus of the above configuration,
The light emitting unit includes a light emitting surface elongated in one direction,
It is preferable that the light emitting unit is disposed such that the longitudinal direction of the light emitting unit and the axial direction of the induction heating coil are in the same direction.

  The metal plate to be subjected to the heat treatment is usually rectangular or the like, and often has a shape that is elongated in one direction compared to the other direction. Therefore, the light emitting unit includes a light emitting surface elongated in one direction, and the light emitting unit is disposed such that the longitudinal direction of the light emitting unit and the axial direction of the induction heating coil are in the same direction. It is suitable for heating of a long-shaped metal plate.

In the heat treatment apparatus of the above configuration,
The light source has a sealing portion at an end of the light emitting portion,
The sealing portion is preferably disposed outside the induction heating coil.

  Usually, both ends of the light emitting portion of the light source are often sealed via a metal foil. When the metal foil is heated, there is a concern that a crack or the like may occur in the sealing portion. Then, if the said sealing part is arrange | positioned so that it may become the exterior of the said induction heating coil, it can suppress that a sealing part (metal foil) is heated by an induction heating coil.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the heat-treated metal plate which can suppress the temperature nonuniformity at the time of heating a metal plate more can be provided.
Furthermore, according to the present invention, it is possible to provide a heat treatment apparatus capable of further suppressing temperature unevenness when heating a metal plate.

It is a schematic diagram for demonstrating the manufacturing method of the heat-treated metal plate which concerns on this embodiment. It is a front view of the steel plate shown in FIG. It is a top view of the steel plate shown in FIG. It is a schematic diagram which shows an example of a heat processing apparatus. It is a flow chart which shows control flow (1) of heat treatment performed with heat treatment equipment. It is a flowchart which shows the control flow (2) of the heat processing performed with a heat processing apparatus. It is a flow chart which shows control flow (3) of heat treatment performed with heat treatment equipment.

  The method for producing a heat-treated metal plate and the heat treatment apparatus according to the present embodiment will be described below with reference to the drawings.

  FIG. 1: is a schematic diagram for demonstrating the manufacturing method of the heat-treated metal plate which concerns on this embodiment. FIG. 2A is a front view of the steel plate shown in FIG. FIG. 2B is a plan view of the steel plate shown in FIG. In the present embodiment, as an example, the case where the differential thickness steel plate (the Curie temperature is around 770 ° C.) is heated from normal temperature (25 ° C.) to 1000 ° C. in about 60 seconds will be described. Although the case of heating from normal temperature (25 ° C.) to 1000 ° C. in approximately 60 seconds is described in this embodiment, the present invention is not limited to 60 seconds and can be set as appropriate.

The method for producing a heat-treated metal plate according to the present embodiment is
Step A of starting heating of the differential thickness steel plate 20 (hereinafter, also simply referred to as “steel plate 20”) by induction heating,
Process B in which the steel plate 20 is heated by the induction heating until the temperature Y of the place X at the lowest temperature of the steel plate 20 becomes a specific value Z based on the Curie temperature after the process A;
After the temperature Y reaches the specific value Z, at least a step C of starting heating of the steel plate 20 by light heating.

  In the method of manufacturing a heat-treated metal plate according to the present embodiment, first, the steel plate 20 is disposed inside the coil 12. The steel plate 20 corresponds to the metal plate of the present invention. The coil 12 corresponds to the induction heating coil of the present invention.

  In the present embodiment, the steel plate 20 has a long plate shape, and has a thick rectangular plate-like portion 22 and a thin rectangular plate-like portion 24.

  The shape of the coil 12 is not particularly limited, and may be appropriately selected according to the size of the steel plate 20 or the like. For example, as shown in FIG. 1, the shape of the coil 12 may be circularly wound in a side view, may be elliptically wound, or may be rectangularly wound.

  The length of the coil 12 is preferably longer than the long side of the steel plate 20. The entire steel plate 20 can be disposed inside the coil 12, and it becomes easy to heat up uniformly.

  After the steel plate 20 is disposed inside the coil 12, heating of the steel plate 20 by induction heating is started (step A). The coil 12 is connected to a power supply (not shown). In step A, application of an alternating voltage for flowing a predetermined high frequency current to the coil 12 is started.

  The AC voltage may be determined in consideration of the time for raising the temperature to a desired temperature (in the present embodiment, 1000 ° C.). As in the present embodiment, when the temperature of the steel plate 20 is raised to 1000 ° C. in 60 seconds, the frequency or voltage is set so that the temperature Y of the portion X becomes the specific value Z in 45 seconds, as an example. You should decide.

  In the present embodiment, the steel plate 20 is disposed inside the coil 12, but in the present invention, the arrangement position of the metal plate is not limited to this example. It may be a place where induction heating can be performed by the coil 12. For example, the metal plate may be disposed outside the coil (for example, below the coil 12).

  After the heating of the steel plate 20 by induction heating is started (after the step A), the induction heating is performed until the temperature Y of the place X at the lowest temperature of the steel plate 20 becomes the specific value Z based on the Curie temperature The steel plate 20 is heated according to (step B).

The specific value Z is preferably as close as possible to the Curie temperature from the viewpoint of suppressing temperature unevenness. However, in general, in induction heating, the temperature rise rate decreases as it approaches the Curie temperature. Therefore, when the specific value Z is set to a temperature that is as close as possible to the Curie temperature, the timing at which optical heating is started is delayed, and the time (tact time) to reach a desired temperature (1000 ° C. in this embodiment) Will be longer. Then, it is preferable to determine in consideration of temperature nonuniformity suppression and shortening of tact time. From the above point of view, the specific value Z may be determined, for example, within a temperature range of about ± 40 ° C. than the Curie temperature, or within a temperature range of about ± 20 ° C., It may be determined within a temperature range of about 10 ° C.
The judgment as to whether or not the metal plate has reached the Curie temperature can be derived from the heating time until the temperature is saturated or the saturation temperature, by heating the target metal plate only by induction heating.
In addition, the judgment as to whether the temperature Y at the location X of the metal plate has reached the specific value Z based on the Curie temperature may be, for example, heating of each region after induction heating is started for the metal plate to be treated The relationship between the heating time until the temperature saturates and the temperature can be determined, and the heating time can be managed. At this time, the temperature measurement may be performed using a contact thermometer (thermocouple or other contact thermometer) or a non-contact thermometer (for example, a radiation thermometer, a fiber-type radiation thermometer, a pyrometer, a multicolor detector) A thermometer etc. can be used. The Curie temperature can be estimated from the saturation of the temperature by induction heating in any case. Also, as a matter of course, it is also possible to derive the temperature from the correlation between the measurement results based on the measurement results of the contact thermometer and the measurement results of the non-contact thermometer.

During the step B, the voltage and the frequency started to be applied in the step A may be changed or may not be changed, but are preferably not changed. If the voltage and the frequency started to be applied in step A are not changed during step B, the apparatus for induction heating can be simplified.
In addition, during the step B, heating (for example, light heating) different from induction heating may be performed during part of the period of the step B in parallel with induction heating. The separate heating is intended to assist the heating. However, when the other heating is performed, the temperature Y ends before reaching the specific value Z. If the other heating is continuously performed even after the temperature Y reaches the specific value Z, it is impossible to obtain the temperature unevenness suppressing effect in the vicinity of the Curie temperature.

During the step B, the temperature Y at the point X is monitored by a non-contact or contact temperature sensor (step B-1). The monitoring of the temperature Y at the location X may be continuously performed during the process B, and after the start of the process B, it is expected that the temperature near the Curie temperature is expected to reach 30 seconds, for example, 30 seconds. You may start with a second).
During the step B, the temperature Y of the portion X may be monitored using a thermoviewer. Specifically, temperature calibration may be performed in advance, and the value of a specific part of the temperature distribution observed by the thermoviewer may be monitored as the temperature Y of the portion X.

The lowest temperature portion X of the steel plate 20 is formed in a region of low magnetic flux density in induction heating. For example, the low magnetic flux density region in the present embodiment is formed in the end region of the induction heating coil in the axial direction (the left-right direction in FIG. 1, ie, the direction perpendicular to the annular surface formed by the lines constituting the coil). Cheap. Although the magnetic flux density is high inside the induction heating coil, the magnetic flux density is relatively low in the end region of the coil, and the steel plate located in the region has a low temperature rise rate and a low temperature at the time of heating. is there. About which part of the steel plate 20 is to be the place with the lowest temperature (the part X), it is desirable to conduct the same test as in the process B in advance and monitor and determine the temperature of the entire steel plate 20.
In the present embodiment, the lowest temperature portion X of the steel plate 20 is located in the end region of the induction heating coil in the coil axial direction where the magnetic flux density is low, as shown in FIG. It is the left end.

Thereafter, after the temperature Y monitored in the step B-1 becomes the specific value Z, heating of the metal plate by light heating is started (step C).
Note that "start of heating" in the step C refers to the start of light heating which is performed for the first time after the temperature Y reaches the specific value Z. For example, when light heating is performed in parallel with induction heating during step B, the light heating is completed by the time step B is completed (until the temperature Y reaches the specific value Z). Therefore, even if the light heating is performed in parallel with the induction heating during the process B, the first light heating after the temperature Y becomes the specific value Z corresponds to the “heating of the process C”. It corresponds to "the start of". That is, the "start of heating" of step C includes the case of resuming the light heating ended before the end of step B.
Moreover, the light heating in process C is light heating of the whole metal plate. Therefore, the light heating of only a part of the metal plate does not correspond to the light heating in the step C.

  In the present embodiment, the light heating lamp 14 is disposed inside the coil 12. More specifically, the lamp 14 is disposed inside the coil 12 so as to be located above the steel plate 20. Therefore, after induction heating, light heating can be performed without moving the steel plate 20. The lamp 14 corresponds to the light source of the present invention.

  The lamp 14 is not particularly limited as long as the steel plate 20 can be heated by light. As such a lamp 14, a lamp emitting light in the infrared or near infrared region can be suitably used, and among them, a halogen heater lamp is preferable.

  The shape, number, arrangement, output and the like of the lamps 14 may be determined in consideration of the time for raising the temperature to a desired temperature (1000 ° C. in the present embodiment). As in the present embodiment, when the temperature of the steel plate 20 is raised to 1000 ° C. in 60 seconds, and the start of the process C is 45 seconds after the process A, the steel plate 20 is 770 in the remaining 15 seconds. What can be heated to around 1000 ° C. from around ° C. may be employed.

  The induction heating may be ended simultaneously with the start of the step C, or may be ended after a certain period of time (for example, 1 to 5 seconds) has elapsed after the start of the step C. In addition, for the purpose of preheating and the like, induction heating may be performed until the end of light heating by dropping the power after the start of step C. Basically, the heating after the Curie temperature may be ended simultaneously with the start of the step C because it is taken over to the light heating. However, immediately after the lamp 14 is lit, sufficient heating may not be performed. Therefore, induction heating may be performed in parallel until the heating is sufficiently performed after the lamp 14 is turned on.

  After the step C, the heating by the lamp 14 is finished at the timing when the steel plate 20 is heated to around 1000 ° C. The timing to finish the heating may be, for example, when a predetermined period has elapsed, similarly to the timing of the start of the process C, the temperature of the steel plate 20 is monitored and the temperature monitored is predetermined. It may be when the value (for example, 1000 ° C.) is reached. The location to be monitored may be determined as appropriate, but examples include the most difficult to heat up portion of the metal plate or the most easy to heat up portion of the metal plate.

  Thereafter, the steel plate 20 is formed into a desired shape by hot pressing or the like.

  By the above, the heat treated steel plate 20 can be manufactured. In the steel plate 20 obtained in this manner, temperature unevenness during heat treatment is suppressed, so generation of cracks due to overheating is suppressed. Moreover, hardening of the location of insufficient heating is not performed well, and a reduction in strength is suppressed.

The manufacturing method of the heat-treated metal plate mentioned above can be implemented by the control part 16 which is not shown in figure. Specifically, the control unit 16 is a drive signal for driving the coil 12 at a predetermined timing (for example, an operation by a worker, reception of a signal that detects that the steel plate 20 is disposed at a predetermined position, and the like). Are sent to the power supply of the coil 12. Thereby, the heating of the steel plate 20 is started. Thereafter, the control unit 16 drives the temperature sensor by transmitting a measurement start signal or the like to the temperature sensor, and continues to receive information of the measured temperature (temperature information) in real time. Furthermore, the control unit 16 continues to determine whether the temperature Y has reached the specific value Z, based on the received temperature information. Then, when it is determined that the temperature Y has become the specific value Z, the control unit 16 transmits a command signal to light the lamp 14 to a driving device (not shown) of the lamp 14 to start light heating. Do. The temperature sensor may be always driven, and the control unit 16 may be configured to receive temperature information at a necessary timing without transmitting a drive signal.
The control unit 16 includes, for example, at least a CPU and a memory, and the CPU performs the control by reading and executing a program stored in the memory.

  The method of manufacturing the heat-treated metal sheet described above can also be performed without using the control unit 16. For example, a person such as a worker operates a power supply device for induction heating to start heating by induction heating. Thereafter, the worker measures the temperature Y in real time using a temperature sensor, and at the timing when the measured value reaches the specific value Z, the worker operates the driving device of the lamp 14 to start optical heating. May be

In the embodiment described above, the case where the temperature Y of the portion X is monitored during the process B and heating of the steel plate 20 by light heating is started after the monitored temperature Y becomes the specific value Z explained. However, in the present invention, the timing of starting heating of the metal plate by light heating is not limited to this example.
For example, the heating of the metal plate by light heating may be started after a predetermined period of time has elapsed from the step A. When the steel plate 20 of the same material and shape is heated by a line or the like, as long as the induction heating conditions are the same, the temperature Y at the point X becomes the specific value Z after induction heating is started in each induction heating process. The period up to is almost the same. Therefore, the time from when induction heating is started using a sensor or the like until the temperature Y of the portion X becomes the specific value Z is measured in advance. And when actually heating by a line etc., the timing which the said temperature Y becomes the said specific value Z can be grasped | ascertained only by measuring the elapsed period from the induction heating start. Therefore, if the timing to start the step C, that is, the elapsed time from the step A (the predetermined period) is determined based on the elapsed period measured in advance, the temperature of the metal plate is detected Even without measurement, it is possible to start heating by light heating at an appropriate timing. For example, if the measurement result using a sensor or the like is 45 seconds, the process C may be started after 45 seconds from the process A.

In the embodiment described above, the case where the metal plate of the present invention is a differential thick steel plate having portions with different thicknesses has been described. However, the shape of the metal plate of the present invention is not limited to this example, and the thickness may be uniform. Further, the shape in plan view may be rectangular, or may be an irregular shape in which a partially acute portion or the like is present. According to the configuration of the present invention, regardless of the shape of the metal plate, it is possible to suppress temperature unevenness at the time of heating.
It should be noted that, regardless of the shape of the metal plate, a heating test may be performed in advance to determine the temperature rising condition and determine the location of the most difficult-to-heat-up portion of the metal plate (that is, the location X). .

  Embodiment mentioned above demonstrated the case where the metal plate of this invention was a steel plate. That is, the case where the material of the metal plate of the present invention is steel (iron alloy containing carbon) has been described. However, the material of the metal plate in the present invention is not limited to a steel plate as long as it is made of a material having a Curie temperature. As another example of the material of the said metal plate, stainless steel, copper, aluminum etc. are mentioned, for example.

The method for producing the heat-treated metal sheet described above can be carried out by a heat treatment apparatus. For example, as one embodiment, it can be carried out by the heat treatment apparatus 10 shown in FIG.
That is, the heat treatment apparatus 10 according to the present embodiment is
A coil 12 for performing induction heating;
A lamp 14 for performing light heating;
And a control unit 16,
After the control unit 16 starts heating the steel plate 20 by the coil 12, the steel plate 20 by the coil 12 continues until the temperature Y at the lowest point X of the steel plate 20 becomes the specific value Z based on the Curie temperature. Heat the
After the temperature Y reaches the specific value Z, the heating of the steel plate 20 by the lamp 14 is started.

The heat treatment apparatus according to the present invention can have the following configuration.
(1) A heat treatment apparatus for heating a metal plate,
An induction heating unit for performing induction heating;
A light heating unit for performing light heating;
And a control unit,
After the control unit starts heating the metal plate by the induction heating unit, the induction is performed until the temperature Y of the place X at the lowest temperature of the metal plate becomes a specific value Z based on the Curie temperature. Heating the metal plate by heating;
A heat treatment apparatus characterized in that the heating of the metal plate by the light heating unit is started after the temperature Y becomes the specific value Z.

(2) The heat treatment apparatus according to (1) above,
The heat treatment apparatus, wherein the control unit starts heating the metal plate by the light heating unit after a predetermined period has elapsed since the heating of the metal plate by the induction heating unit is started.

(3) The heat treatment apparatus according to (1) above,
It has a sensor that monitors the temperature Y at the point X,
The said control part starts the heating of the said metal plate by the said optical heating part, after the temperature Y monitored by the said sensor becomes the said specific value Z, The heat processing apparatus characterized by the above-mentioned.

The induction heating unit is not particularly limited as long as the metal plate can be heated by supplying current to the metal plate using the principle of electromagnetic induction, and examples thereof include a coil 12 and the like.
The light heating unit is not particularly limited as long as the metal plate can be heated by light, and examples thereof include a lamp 14 and the like.
The control unit is not particularly limited as long as it has the function of performing the control, and, for example, the control unit 16 may be mentioned.
The sensor is not particularly limited as long as it can monitor the temperature Y of the lowest point X of the metal plate, and a conventionally known noncontact or contact temperature sensor can be mentioned.
The material of the metal plate is not particularly limited as long as it is made of a material having a Curie temperature. Further, the thickness of the metal plate may be uniform, or partially different portions may be present. Further, the shape in plan view may be rectangular, or may be an irregular shape in which a partially acute portion or the like is present.

  Hereinafter, a more detailed specific example of the heat treatment apparatus will be described.

  FIG. 3 is a schematic view showing an example of the heat treatment apparatus. As shown in FIG. 3, the heat treatment apparatus 110 includes an induction heating coil 112, a lamp 114, a transport unit 122, a mounting table 124, a lamp control unit 126 for controlling the operation of the lamp 114, and an induction heating coil. And an induction heating control unit 128 for controlling the operation of 112. The lamp 114 corresponds to the light source of the present invention.

  The lamp 114 includes a light emitting unit 116 that emits light, and a cap 118 provided at both ends of the light emitting unit 116. A sealing portion is accommodated in the base 118. Specifically, in the base 118, both end portions of the light emitting portion 116 are sealed by the sealing portion via the metal foil. Since a metal foil exists in the sealing portion, there is a concern that when the metal foil is heated, a crack or the like may be generated in the sealing portion. Therefore, in the present embodiment, the sealing portion is disposed outside the induction heating coil 112.

  The base 118 is preferably made of a nonmagnetic material such as ceramics. When the base 118 is made of a nonmagnetic material, the induction heating coil 112 can be prevented from being heated.

  The light emitting unit 116 includes a light emitting surface 117 which is long in one direction (left and right direction in FIG. 3). The light emitting unit 116 is disposed such that the longitudinal direction of the light emitting unit 116 and the axial direction of the induction heating coil 112 are in the same direction. The metal plate to be subjected to the heat treatment is usually rectangular or the like, and often has a shape that is elongated in one direction compared to the other direction. Therefore, in the present embodiment, since the longitudinal direction of the light emitting portion 116 and the axial direction of the induction heating coil 112 are arranged in the same direction, it is suitable for heating a long-shaped metal plate. There is.

  The light emitting unit 116 of the lamp 114 is installed inside the induction heating coil 112. In the present specification, the light emitting unit 116 is provided inside the induction heating coil 112 if at least a part of the light emitting unit 116 is provided inside the induction heating coil 112, and the light emitting unit It is not necessary for all of 116 to be installed inside the induction heating coil 112. Since the lamp 114 is disposed inside the induction heating coil 112, light heating can be performed without moving the metal plate 120 after induction heating.

  The mounting table 124 is installed movably in the axial direction in the induction heating coil 112. The movable in the axial direction of the mounting table 124 is driven by the transport unit 122. The metal plate 120 can be mounted on the mounting table 124. Therefore, after the metal plate 120 is mounted on the mounting table 124, the metal plate 120 can be moved to the inside of the induction heating coil 112 together with the mounting table 124, and heat treatment can be performed. Then, after the heat treatment, the metal plate 120 can be moved from the induction heating coil 112 to the outside together with the mounting table 124 by the transfer unit 122. That is, the induction heating coil 112 has a heating space in which the metal plate 120 can be installed. The mounting table 124 is desirably made of a nonmagnetic material such as ceramics. Further, the mounting table 124 may partially support the metal plate 120.

  Next, a control flow of heat treatment by the heat treatment apparatus 110 will be described. The control flow of heat treatment by the heat treatment apparatus 110 includes the following control flow (1), control flow (2), and control flow (3). The following will be described in order.

  FIG. 4 is a flowchart showing a control flow (1) of heat treatment performed by the heat treatment apparatus. The control flow (1) is executed by the control unit 130 (not shown) included in the heat treatment apparatus. In this control flow (1), it is determined that a predetermined start condition is satisfied (for example, that a signal indicating that there has been an operation input by a worker or that the metal plate 120 has been disposed at a predetermined position is received) It is executed triggered by).

  First, in step 10, the control unit 130 transmits an induction heating start signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating start signal drives the induction heating coil 112 to start induction heating of the metal plate. Thereafter, the process proceeds to step 12.

  In step 12, the control unit 130 monitors temperature information transmitted from a temperature detection unit (not shown) and checks whether temperature saturation has occurred. Specifically, based on the received temperature information, the control unit 130 continues to determine whether the temperature Y at the point X has reached the specific value Z and determines that the temperature Y has reached the specific value Z. , Shift the processing to step 14.

  In step 14, the control unit 130 transmits an induction heating stop signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating stop signal stops driving of the induction heating coil 112. Thereafter, the process proceeds to step 16.

  In step 16, the control unit 130 transmits a light heating start signal to the lamp control unit 126. The lamp control unit 126 receiving the light heating start signal drives the lamp 114 to start light heating of the metal plate. Thereafter, the process moves to step 18.

  In step 18, the control unit 130 monitors the temperature information transmitted from the temperature detection unit, and confirms whether the desired temperature has been reached. Specifically, based on the received temperature information, the control unit 130 continues to determine whether or not the desired temperature is reached, and when it is determined that the desired temperature is reached, the light heating stop signal is sent to the lamp control unit 126 Send. The lamp control unit 126 that has received the light heating stop signal stops the driving of the lamp 114, and ends the heating of the metal plate by the light heating. Thus, the control flow (1) is completed.

  FIG. 5 is a flowchart showing a control flow (2) of heat treatment performed by the heat treatment apparatus. The heat treatment apparatus 110 may be configured to perform the control flow (2) instead of the control flow (1). Similar to the control flow (1), the control flow (2) is executed by the control unit 130 (not shown) provided in the heat treatment apparatus. In the control flow (2), as in the control flow (1), a predetermined start condition is satisfied (for example, there is an operation input by a worker or that the metal plate 120 is disposed at a predetermined position) Is received upon reception of a signal that has detected.

  First, in step 20, the control unit 130 transmits an induction heating start signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating start signal drives the induction heating coil 112 to start induction heating of the metal plate. Thereafter, the process proceeds to step 22.

  At step 22, the control unit 130 maintains the heating of the induction heating until the desired time. Specifically, the control unit 130 measures an elapsed time from the transmission of the induction heating start signal, and continues to check whether a predetermined first elapsed time has elapsed. The control unit 130 shifts the process to step 24 when it is determined that the elapsed time since the transmission of the induction heating start signal has passed the first elapsed time.

  In step 24, the control unit 130 transmits an induction heating stop signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating stop signal stops driving of the induction heating coil 112. Thereafter, the process proceeds to step 26.

  In step 26, the control unit 130 transmits a light heating start signal to the lamp control unit 126. The lamp control unit 126 receiving the light heating start signal drives the lamp 114 to start light heating of the metal plate. Thereafter, the process proceeds to step 28.

  In step 28, the control unit 130 measures an elapsed time after transmitting the light heating start signal, and continues to check whether a predetermined second elapsed time has elapsed. The control unit 130 transmits a light heating stop signal to the lamp control unit 126 when it is determined that the elapsed time since the transmission of the light heating start signal has passed the second elapsed time. The lamp control unit 126 that has received the light heating stop signal stops the driving of the lamp 114, and ends the heating of the metal plate by the light heating. Thus, the control flow (2) is ended.

  FIG. 6 is a flowchart showing a control flow (3) of heat treatment performed by the heat treatment apparatus. The heat treatment apparatus 110 may be configured to perform the control flow (3) instead of the control flows (1) and (2). The control flow (3) is executed by the control unit 130 (not shown) provided in the heat treatment apparatus, as in the case of the control flows (1) and (2). In the control flow (3), as in the control flows (1) and (2), a predetermined start condition is satisfied (for example, there is an operation input by a worker, or the metal plate 120 is at a predetermined position). It is executed triggered by the reception of a signal that detects the placement, etc.).

  First, in step 30, the control unit 130 transmits an induction heating start signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating start signal drives the induction heating coil 112 to start induction heating of the metal plate. Thereafter, the process proceeds to step 32.

  In step 32, the control unit 130 transmits a light heating start signal to the lamp control unit 126. The lamp control unit 126 receiving the light heating start signal drives the lamp 114 to start light heating of the metal plate. Thereafter, the process proceeds to step 34.

  In step 34, the control unit 130 determines whether or not the metal plate 120 has reached an arbitrary temperature based on, for example, temperature information from a temperature detection unit, an elapsed time since the start of the light heating, or the like. When it is determined that the set arbitrary temperature has been reached, a light heating stop signal is transmitted to the lamp control unit 126. The lamp control unit 126 that has received the light heating stop signal stops the driving of the lamp 114, and ends the heating of the metal plate by the light heating. Thereafter, the process proceeds to step 36. The arbitrary temperature set here is a temperature set before the temperature of a part of the metal plate 120 reaches the specific value Z. Thereby, the temperature rising rate until reaching the specific value Z can be increased.

  In step 36, the control unit 130 monitors the temperature information transmitted from the temperature detection unit (not shown) to check whether the temperature has become saturated. Specifically, based on the received temperature information, the control unit 130 continues to determine whether the temperature Y at the point X has reached the specific value Z and determines that the temperature Y has reached the specific value Z. , And move the process to step 38.

  In step 38, the control unit 130 transmits an induction heating stop signal to the induction heating control unit 128. The induction heating control unit 128 that has received the induction heating stop signal stops driving of the induction heating coil 112. Thereafter, the process proceeds to step 40.

  In step 40, the control unit 130 transmits a light heating start signal to the lamp control unit 126. The lamp control unit 126 receiving the light heating start signal drives the lamp 114 to start light heating of the metal plate. Thereafter, the process proceeds to step 42.

  In step 42, the control unit 130 monitors the temperature information transmitted from the temperature detection unit, and confirms whether the desired temperature has been reached. Specifically, based on the received temperature information, the control unit 130 continues to determine whether or not the desired temperature is reached, and when it is determined that the desired temperature is reached, the light heating stop signal is sent to the lamp control unit 126 Send. The lamp control unit 126 that has received the light heating stop signal stops the driving of the lamp 114, and ends the heating of the metal plate by the light heating. Thus, the control flow (3) is ended.

  The control flow (1), the control flow (2), and the control flow (3) of the heat treatment performed by the heat treatment apparatus 110 have been described above.

  In the above embodiment, the case where the lamp control unit 126 controls the driving of the lamp 114 and the induction heating control unit 128 controls the driving of the induction heating coil 112 has been described. That is, the case where the lamp 114 and the induction heating coil 112 are controlled by separate control units has been described. However, the heat treatment apparatus of the present invention is not limited to this example, and the lamp 114 and the induction heating coil 112 may be controlled by one control unit.

  In the above-described embodiment, the method of checking whether or not temperature saturation has occurred and the method of measuring various elapsed times are merely examples, and can be changed as appropriate.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the example mentioned above, It is possible in the range which satisfies the structure of this invention to make a design change suitably.

10, 110 heat treatment apparatus 12, 112 coil 14, 114 lamp 20 steel plate 22 thick rectangular plate-like portion 24 thick thin rectangular plate-like portion 116 light emitting portion 117 light emitting surface 118 base 126 lamp control portion 128 induction heating control portion

Claims (6)

Process A which starts heating of the metal plate by induction heating,
A step B of heating the metal plate by the induction heating until the temperature Y of the lowest temperature portion X of the metal plate becomes a specific value Z based on the Curie temperature after the step A;
And C. starting the heating of the metal plate by light heating after the temperature Y reaches the specific value Z. A method of manufacturing a heat-treated metal plate, comprising:   The method for manufacturing a heat-treated metal sheet according to claim 1, wherein the step C is a step of starting heating of the metal plate by light heating after a predetermined period of time has elapsed from the step A. The process B includes a process B-1 of monitoring the temperature Y of the place X during the process B,
The heat-treated metal according to claim 1, wherein the step C is a step of starting heating of the metal plate by light heating after the monitored temperature Y becomes the specific value Z. How to make a board. An induction heating coil for heating the metal plate by induction heating;
And a light source for light heating the metal plate,
The induction heating coil has a heating space in which a metal plate can be installed.
The light source includes a light emitting unit that emits light.
The heat treatment apparatus, wherein the light emitting unit is installed inside the induction heating coil. The light emitting unit includes a light emitting surface elongated in one direction,
5. The heat treatment apparatus according to claim 4, wherein the light emitting unit is disposed such that a longitudinal direction of the light emitting unit and an axial direction of the induction heating coil are in the same direction. The light source has a sealing portion at an end of the light emitting portion,
The heat treatment apparatus according to claim 4, wherein the sealing portion is disposed outside the induction heating coil.

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