WO2025203159A1 - Heat treatment equipment - Google Patents

Abstract

Heat treatment equipment for heat treating a metal strip comprises: a first heating part and a second heating part each configured to heat the metal strip by a heating means that does not include an induction heating device; a first furnace body part that houses the first heating part; a second furnace body part that houses the second heating part; and an induction heating part that includes an induction heating device for heating the metal strip. The first heating part, the induction heating part, and the second heating part are arranged in this order in the transport direction of the metal strip, and a bypass passage for guiding gas inside the second furnace body part to the inside of the first furnace body part by bypassing the induction heating part is provided.

Description

Heat Treatment Equipment

This disclosure relates to heat treatment equipment.

Induction heating devices are sometimes used as a heating method in heat treatment equipment.

Patent Document 1 describes how, in continuous annealing equipment, a gas burner or electric heater is used in combination with an induction heating device to uniformly heat a steel strip in the longitudinal direction to an annealing temperature that exceeds the Curie point.

Patent No. 5135534

When using an induction heating device to increase the heating capacity of a continuous annealing furnace (heat treatment equipment) that includes a preheating zone and a heating zone, for example, it is easiest to install the induction heating device on the inlet side of the preheating zone (i.e., upstream of the continuous annealing furnace). However, by installing the induction heating device between the preheating zone and the heating zone, the temperature of the metal strip in the preheating zone is lower than when the induction heating device is installed upstream of the preheating zone, and the temperature difference between the metal strip and the furnace gas temperature is greater. This increases the amount of heat exchange between the two, and is thought to improve the heating efficiency of the continuous annealing furnace. However, in this case, high-temperature gas from the heating zone can flow into the preheating zone via the location where the induction heating device is installed, exposing the induction heating device to high-temperature gas and increasing the risk of damage to the induction heating device due to high temperatures.

In light of the above circumstances, at least one embodiment of the present invention aims to provide heat treatment equipment that can efficiently heat metal strips while reducing the risk of damage to the induction heating device.

At least one embodiment of the heat treatment equipment of the present invention includes:
1. A heat treatment facility for heat treating a metal strip, comprising:
a first heating section and a second heating section each configured to heat the metal strip with a heating means not including an induction heating device;
a first furnace body that accommodates the first heating unit;
a second furnace body that accommodates the second heating unit;
an induction heating unit including an induction heating device for heating the metal strip;
Equipped with
the first heating section, the induction heating section, and the second heating section are arranged in this order in a conveying direction of the metal strip,
A bypass passage is provided for guiding the gas inside the second furnace body to the inside of the first furnace body, bypassing the induction heating section.

At least one embodiment of the present invention provides heat treatment equipment that can efficiently heat metal strips while reducing the risk of damage to the induction heating device.

1 is a schematic diagram of a heat treatment facility according to an embodiment. 1 is a schematic diagram of a heat treatment facility according to an embodiment. FIG. 2 is a schematic diagram of an induction heating unit according to one embodiment.

Several embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

FIGS. 1 and 2 are schematic diagrams of heat treatment equipment according to one embodiment. As shown in FIGS. 1 and 2, the heat treatment equipment 1 is equipment for heat treating a metal strip S, and includes a first heating section 6 and a second heating section 8 for heating the metal strip S. The second heating section 8 is provided downstream of the first heating section 6 in the transport direction of the metal strip S. As shown in FIG. 2, the heat treatment equipment 1 may also include a cooling section 30 located downstream of the second heating section 8 in the transport direction of the metal strip S. The cooling section 30 may include, for example, a cooling nozzle 32 configured to spray a cooling fluid onto the metal strip S.

In some embodiments, the heat treatment equipment 1 may be a continuous annealing equipment for continuously annealing the metal strip S, comprising a first heating section 6 constituting a preheating zone, a second heating section 8 constituting a heating zone, and a cooling section 30 constituting a cooling zone. The heat treatment equipment 1 as a continuous annealing equipment may further comprise a soaking zone 28 (see Figure 2) provided between the heating zone (second heating section 8) and the cooling zone (cooling section 30) in the transport direction of the metal strip S, an overaging zone (not shown) provided downstream of the cooling zone, etc.

Note that the heat treatment equipment in some embodiments is not limited to annealing equipment. For example, in some embodiments, the heat treatment equipment may include a heat treatment furnace for performing heat treatments other than annealing, such as quenching, tempering, and normalizing.

The heat treatment equipment 1 includes a furnace body 2 that houses a first heating section 6, a second heating section 8, and/or a cooling section 30. The furnace body 2 shown in Figures 1 and 2 includes a first furnace body section 2a that houses the first heating section 6, and a second furnace body section 2b that houses the second heating section 8.

A plurality of transport rolls 4 for transporting the metal strip S may be provided inside the furnace body 2.

The heat treatment equipment 1 may include, for example, a horizontal furnace in which the metal strip S is transported horizontally in the first heating section 6 and the second heating section 8 as shown in Figure 1, or may include, for example, a vertical furnace in which the metal strip S is transported vertically in the first heating section 6 and the second heating section 8 as shown in Figure 2.

In some embodiments, the first heating section 6 and the second heating section 8 are each configured to heat the metal strip S using heating means that do not include an induction heating device.

The first heating section 6 may be configured to heat the metal strip S using the heat of the atmospheric gas inside the first furnace body section 2a. For example, the first heating section 6 may be configured to heat the metal strip S by convection heating using the atmospheric gas inside the first furnace body section 2a. Alternatively, the first heating section 6 may be configured to heat the metal strip S by spraying a fluid (gas, etc.) heated outside the furnace body 2 onto the metal strip S using a nozzle or the like provided inside the first furnace body section 2a.

The second heating section 8 may be configured to heat the metal strip S heated by the first heating section 6 to a temperature higher than the sheet temperature at the outlet of the first heating section 6. In some embodiments, the second heating section 8 may include a heating device 16 (see Figures 1 and 2) for heating the metal strip S.

In one embodiment, the second heating section 8 may be configured to burn fuel and heat the metal strip using the heat generated by the combustion of the fuel.

For example, the second heating section 8 may include, as the heating device 16, a burner configured to combust fuel and direct the flame generated by the combustion of the fuel toward the metal strip S. In other words, the second heating section 8 may be a direct-fire furnace configured to directly heat the metal strip S with the burner flame. In this case, the combustion gas generated in the second heating section 8 may be introduced into the first furnace body section 2a and used as atmospheric gas in the first heating section 6 to heat the metal strip S.

Alternatively, the second heating section 8 may include a radiant tube as the heating device 16, configured to be supplied with combustion gas generated by the combustion of fuel. In this case, gas heated by heat exchange with the combustion exhaust gas discharged to the outside from the radiant tube may be supplied to the first heating section 6 as a heating fluid.

Furthermore, as shown in FIG. 1, the first furnace body section 2a may be provided with an exhaust duct 20 for discharging atmospheric gas from the first heating section 6.

In some embodiments, as shown in Figures 1 and 2, for example, the heat treatment equipment 1 includes an induction heating section 10 including an induction heating device 12 for heating the metal strip S. The induction heating section 10 is provided between the first heating section 6 and the second heating section 8 in the transport direction of the metal strip S (i.e., downstream of the first heating section 6 and upstream of the second heating section 8). The induction heating section 10 may be housed in the third furnace body section 2c that constitutes the furnace body 2. Here, the first heating section 6 and the second heating section 8 may be able to communicate with each other via the induction heating section 10.

The heat treatment equipment 1 also includes a bypass passage 14 for directing gas inside the second furnace body 2b into the first furnace body 2a, bypassing the induction heating section 10. In the exemplary embodiment shown in FIGS. 1 and 2, the bypass passage 14 includes a duct provided on the outside of the first furnace body 2a and the second furnace body 2b. The duct may have opposite ends connected to the first furnace body 2a and the second furnace body 2b, respectively.

FIG. 3 is a schematic diagram of an induction heating unit 10 according to one embodiment. As shown in FIG. 3, the induction heating device 12 includes a coil 36 for generating magnetic flux. The coil 36 of the induction heating device 12 may be configured to generate magnetic flux along an in-plane direction of the metal strip S (e.g., the longitudinal direction of the metal strip S), or may be configured to generate magnetic flux along an out-of-plane direction of the metal strip S (e.g., a direction perpendicular to the surface of the metal strip S).

In the heat treatment equipment 1 according to the embodiment described above, the induction heating device 12 is provided between the first heating section 6 and the second heating section 8. This reduces the sheet temperature in the first heating section 6 compared to when the induction heating device 12 is provided upstream of the first heating section 6 in the transport direction of the metal strip S. This increases the temperature difference between the atmospheric gas in the first heating section 6 and the metal strip S, thereby increasing the amount of heat exchange between the two. This allows the metal strip S to be heated efficiently. Furthermore, in the heat treatment equipment 1 described above, high-temperature gas (combustion gas or atmospheric gas) from the second heating section 8 can be introduced to the first heating section 6 via a bypass passage 14 that bypasses the induction heating section 10. This allows the metal strip S to be heated in the first heating section 6 using the high-temperature gas from the second heating section 8 while reducing the amount of high-temperature gas flowing from the second heating section 8 into the induction heating section 10. Therefore, the heat treatment equipment 1 described above allows the metal strip S to be heated efficiently while protecting the induction heating device 12 from high temperatures and reducing the risk of damage.

In addition, when the metal strip S is heated in the second heating section 8 using a burner that emits a flame toward the metal strip S, the combustion gas generated by the combustion of fuel in the second heating section 8 (inside the second furnace body section 2b) is led to the first heating section 6 (inside the first furnace body section 2a) via the bypass passage 14. In addition, when the metal strip S is heated using a radiant tube in the second heating section, the atmospheric gas inside the second furnace body section 2b is led to the first heating section 6 (inside the first furnace body section 2a) via the bypass passage 14.

If the second heating section 8 is a direct-fire furnace that heats the metal strip S using a burner that emits a flame toward the metal strip S, the first heating section 6 may include an afterburner 18 (see Figure 1) for burning fuel contained in the gas inside the first furnace body section 2a. The first heating section 6 may also be configured to heat the metal strip S using the heat generated by the combustion of fuel in the afterburner 18.

Generally, when heating the metal strip S using a burner, excess fuel relative to the air (or oxygen) may be supplied to the burner to suppress oxidation of the metal strip S. Even when such excess fuel is supplied to the burner in the second heating section 8, the temperature of the metal strip S in the first heating section 6 is kept relatively low by providing the induction heating section 10 between the first heating section 6 and the second heating section 8, as described above. Therefore, even if the excess fuel contained in the combustion gas from the second heating section 8 in the first heating section 6 is burned in an afterburner 18 or the like and used as a heat source, oxidation of the metal strip S in the first heating section 6 can be suppressed.

In some embodiments, the heat treatment equipment 1 includes a sealing device 22 provided at least between the first heating section 6 and the induction heating section 10 or between the induction heating section 10 and the second heating section 8 in the transport direction of the metal strip S, and configured to prevent gas from flowing into the induction heating section 10 from inside the first furnace body section 2a or the second furnace body section 2b. In the exemplary embodiment shown in Figures 1 and 2, a sealing device 22 is provided between the first heating section 6 and the induction heating section 10 and between the induction heating section 10 and the second heating section 8.

In this way, by providing a sealing device 22 at least between the first heating section 6 and the induction heating section 10, or between the induction heating section 10 and the second heating section 8, it is possible to more effectively prevent high-temperature gas from the second heating section 8 (gas flowing directly from the second heating section 8 into the induction heating section 10, or gas led from the second heating section 8 into the first furnace body section 2a via the bypass passage 14) from flowing into the induction heating section 10. This further reduces the risk of damage to the induction heating device 12 due to high-temperature gas.

For example, as shown in FIG. 3, the sealing device 22 may include a sealing member 23 that faces the surface of the metal strip S. In one embodiment, the sealing member 23 may include a sealing roll that is capable of contacting the surface of the metal strip S and rotating as the metal strip S is transported. In one embodiment, the sealing member 23 may include a plate-shaped or box-shaped gate member that has a flat opposing surface that faces the surface of the metal strip S. In the exemplary embodiment shown in FIG. 3, the sealing device 22 includes a pair of sealing rolls (sealing members 23) that are respectively provided to face both sides of the metal strip S.

The sealing member 23 may be configured to be driven in a direction perpendicular to the surface of the metal strip S. For example, a sealing member 23 (see Figure 1 or Figure 3) installed in a portion where the metal strip S is transported horizontally may be configured to be driven in an up-down direction (or vertical direction). Furthermore, a sealing member 23 (see Figure 2) installed in a portion where the metal strip S is transported vertically (or vertically) may be configured to be driven in a horizontal direction.

Furthermore, the sealing device 22 may include a drive unit (e.g., a motor or a fluid pressure cylinder) for driving the sealing member 23 as described above.

In the above-described embodiment, the sealing member 23, which is provided facing the surface of the metal strip S, can move in a direction perpendicular to the surface. Therefore, for example, by moving the sealing member 23 to increase the distance between the surface of the metal strip S and the sealing member 23, the metal strip S can be passed smoothly through the location where the sealing member 23 is installed, or by adjusting the position of the sealing member 23 according to the thickness of the metal strip S, the size of the gap between the metal strip S and the sealing member 23 can be maintained appropriately.

In some embodiments, as shown in Figures 1 to 3, the heat treatment equipment 1 includes a low-temperature gas supply unit 24 for supplying gas that is lower in temperature than the gas (combustion gas or atmospheric gas) inside the second furnace body unit 2b to the induction heating unit 10. As shown in Figure 3, the low-temperature gas supply unit 24 may include a supply pipe 24a provided between a low-temperature gas storage unit (such as a gas tank) (not shown) and the induction heating unit 10, and a supply valve 24b provided on the supply pipe 24a.

The above-mentioned low-temperature gas may contain a reducing gas such as hydrogen or an inert gas such as nitrogen. Furthermore, if the impact of oxidation of the metal strip S is small or there is no concern about oxidation (for example, if the metal strip S is stainless steel), the low-temperature gas may be a gas other than the above-mentioned reducing gas or inert gas (for example, air).

In the above-described embodiment, the low-temperature gas supply unit 24 can supply gas to the induction heating unit 10 that is lower in temperature than the gas inside the second furnace body 2b, thereby more effectively protecting the induction heating unit 10 from high temperatures. This further reduces the risk of damage to the induction heating unit 10.

In some embodiments, as shown in Figures 1 to 3, for example, the heat treatment equipment 1 may include a low-temperature gas discharge section 26 for discharging gas (including low-temperature gas) from within the induction heating section 10 to that section of the furnace body 2. As shown in Figure 3, the low-temperature gas discharge section 26 may include an exhaust pipe 26a for discharging gas from within the induction heating section 10 to the outside, and an exhaust valve 26b provided on the exhaust pipe 26a.

In this way, by providing the low-temperature gas exhaust section 26, the low-temperature gas supplied to the induction heating section 10 can be exhausted to the outside of the furnace body 2, thereby preventing the low-temperature gas in the induction heating section 10 from flowing into the first heating section 6 or second heating section 8 via the sealing device 22. This prevents a decrease in the heating efficiency of the metal strip S in the heat treatment equipment 1.

In some embodiments, as shown in FIG. 3, for example, the induction heating device 12 may include a thermal insulator 38 disposed between the coil 36 and the metal strip S.

In this way, by providing the insulating material 38 between the coil 36 of the induction heating device 12 and the metal strip S, the heat of the high-temperature gas that may flow into the induction heating unit 10 is less likely to be transferred to the coil 36. This makes it possible to more effectively protect the induction heating unit 10 from high temperatures, further reducing the risk of damage to the induction heating device 12.

In some embodiments, as shown in FIG. 3, for example, the induction heating device 12 may include an airtight material 40 inside the furnace body 2 that separates the space through which the metal strip S passes from the space in which the coil 36 is provided, and prevents furnace gas from entering the space in which the coil 36 is provided. The airtight material 40 may include a sheet made of a resin such as silicone or Teflon (registered trademark). The airtight material 40 may be provided so as to surround the coil 36. The airtight material 40 may be fixed to the furnace body 2 with bolts.

By providing the above-mentioned airtight material 40, the possibility of the coil 36 being exposed to high-temperature gas can be reduced, thereby more effectively protecting the induction heating unit 10 from high temperatures.

In annealing furnaces that include a preheating zone and a heating zone, it is possible to install an induction heating device upstream of the preheating zone (i.e., on the entry side of the annealing furnace) to strengthen heating capacity. In this case, the preheating zone may need to be reduced due to restrictions on the overall equipment length of the annealing furnace. In such cases, a self-heat recovery burner may be used in the heating zone (direct fire zone) as a heat recovery means to replace the preheating zone. A self-heat recovery burner is a burner equipped with a heat exchanger for exchanging heat between the combustion gases generated by the burner and the fuel or air being combusted in the burner, and uses the heat of the combustion gases to preheat the fuel or air.

The contents described in each of the above embodiments can be understood, for example, as follows:

[1] At least one embodiment of the heat treatment equipment (1) of the present invention comprises:
A heat treatment facility for heat treating a metal strip (S),
a first heating section (6) and a second heating section (8), each configured to heat the metal strip with a heating means not including an induction heating device;
A first furnace body (2a) that accommodates the first heating section;
A second furnace body (2b) that accommodates the second heating section;
an induction heating unit (10) including an induction heating device (12) for heating the metal strip;
Equipped with
the first heating section, the induction heating section, and the second heating section are arranged in this order in a conveying direction of the metal strip,
A bypass passage (14) is provided for guiding the gas inside the second furnace body to the inside of the first furnace body, bypassing the induction heating section.

In the above configuration [1], an induction heating device is provided between the first heating section and the second heating section. This means that the strip temperature in the first heating section is lower than when the induction heating device is provided upstream of the first heating section in the metal strip transport direction. This increases the temperature difference between the atmospheric gas in the first heating section and the metal strip, resulting in a greater amount of heat exchange between the two, allowing the metal strip to be heated efficiently. Furthermore, in the above configuration [1], high-temperature gas (combustion gas or atmospheric gas) from the second heating section can be guided to the first heating section via a bypass passage that bypasses the induction heating section. This means that the high-temperature gas flowing from the second heating section into the induction heating section can be reduced, while the high-temperature gas from the second heating section can be used to heat the metal strip in the first heating section. Therefore, with the above configuration [1], the metal strip can be efficiently heated while protecting the induction heating device from high temperatures and reducing the risk of damage.

[2] In some embodiments, in the configuration of [1] above,
the second heating unit is configured to combust fuel and heat the metal strip using heat generated by the combustion of the fuel;
The first heating section is configured to heat the metal strip by convection heating using atmospheric gas inside the first furnace body section.

The configuration of [2] above is a heat treatment system including a first heating section that heats the metal strip by convection heating using atmospheric gas, and a second heating section that heats the metal strip using heat generated by fuel combustion. As described in [1] above, the metal strip can be efficiently heated, and the metal strip can be heated in the first heating section using high-temperature gas from the second heating section while reducing the amount of high-temperature gas passing through the induction heating device. Therefore, the configuration of [2] above allows the metal strip to be efficiently heated while protecting the induction heating device from high temperatures and reducing the risk of damage.

[3] In some embodiments, in the configuration of [2] above,
the second heating unit includes a burner configured to combust the fuel and emit a flame generated by the combustion of the fuel toward the metal strip;
The combustion gas generated by the combustion of the fuel in the second heating section is guided into the inside of the first furnace body section through the bypass passage.

According to the configuration [3] above, the second heating section includes a burner that emits a flame toward the metal strip. Therefore, the high-temperature combustion gas generated by the combustion of fuel in the burner is guided to the first heating section via a bypass passage. This allows the metal strip to be effectively heated by convection heating using atmospheric gas containing the combustion gas in the first heating section, while also reducing the amount of high-temperature combustion gas passing through the induction heating device. Therefore, according to the configuration [3] above, the metal strip can be efficiently heated while protecting the induction heating device from high temperatures and reducing the risk of damage.

Furthermore, when a metal strip is heated using a burner, an excess of fuel relative to the air (or oxygen) may be supplied to the burner to suppress oxidation of the metal strip. Even in such cases, in the configuration [3] above, by providing an induction heating section between the first heating section and the second heating section, the temperature of the metal strip in the first heating section is kept relatively low as described above. Therefore, even if the first heating section burns the excess fuel contained in the combustion gas from the second heating section and uses it as a heat source, oxidation of the metal strip in the first heating section can be suppressed.

[4] In some embodiments, in the configuration of [1] above,
the second heating section includes a radiant tube configured to heat the metal strip;
The first heating section is configured to heat the metal strip by convection heating using an atmospheric gas inside the first furnace body section,
The atmospheric gas inside the second furnace body is guided into the inside of the first furnace body through the bypass passage.

The configuration of [4] above is a heat treatment system including a first heating section that heats the metal strip by convection heating using atmospheric gas, and a second heating section that heats the metal strip using a radiant tube. As described in [1] above, the metal strip can be efficiently heated, and the metal strip can be heated in the first heating section using high-temperature gas from the second heating section while reducing the amount of high-temperature gas passing through the induction heating device. Therefore, the configuration of [4] above allows the metal strip to be efficiently heated while protecting the induction heating device from high temperatures and reducing the risk of damage.

[5] In some embodiments, in any of the configurations [1] to [4] above,
The bypass passage includes a duct provided outside the first furnace body and the second furnace body.

The configuration of [5] above allows a bypass passage that bypasses the induction heating section to be formed using a simple configuration including ducts provided on the outside of the first furnace body and the second furnace body. This allows the metal strip to be heated efficiently while protecting the induction heating device from high temperatures and reducing the risk of damage.

[6] In some embodiments, in any of the configurations [1] to [5] above,
The heat treatment equipment includes:
A sealing device (22) is provided at least between the first heating section and the induction heating section or between the induction heating section and the second heating section in the conveying direction of the metal strip, and is configured to suppress the inflow of gas inside the first furnace body section or the second furnace body section into the induction heating section.

In the configuration [6] above, a sealing device is provided at least between the first heating unit and the induction heating unit, or between the induction heating unit and the second heating unit, which more effectively prevents high-temperature gas from the second heating unit from flowing into the induction heating unit. This further reduces the risk of damage to the induction heating unit due to high-temperature gas.

[7] In some embodiments, in the configuration of [6] above,
The sealing device includes a sealing member (23) that is provided facing the surface of the metal strip and is configured to be driven along a direction perpendicular to the surface of the metal strip.

According to the configuration [7] above, the sealing member provided facing the surface of the metal strip can move in a direction perpendicular to the surface. Therefore, for example, by moving the sealing member to increase the distance between the surface of the metal strip and the sealing member, the metal strip can be threaded smoothly through the location where the sealing member is installed, or by adjusting the position of the sealing member according to the thickness of the metal strip, the size of the gap between the metal strip and the sealing member can be maintained appropriately.

[8] In some embodiments, in the configuration of [6] or [7] above,
The heat treatment equipment includes:
A low-temperature gas supply section (24) is provided for supplying gas at a lower temperature than the gas inside the second furnace body section to the induction heating section.

With the configuration [8] above, the low-temperature gas supply unit can supply gas to the induction heating unit that is lower in temperature than the gas inside the second furnace body, so the induction heating unit can be more effectively protected from high temperatures. This further reduces the risk of damage to the induction heating unit.

[9] In some embodiments, in any of the configurations [1] to [8] above,
The induction heating device is
a coil (36) for generating a magnetic flux;
a heat insulating material (38) provided between the coil and the metal strip;
Includes:

In the configuration [9] above, heat insulation is provided between the coil of the induction heating device and the metal band, making it difficult for heat from high-temperature gas that may flow into the induction heating section to be transferred to the coil. This makes it possible to more effectively protect the induction heating device from high temperatures and further reduce the risk of damage to the induction heating section.

[10] In some embodiments, in any of the configurations [1] to [9] above,
The heat treatment equipment includes:
A cooling section (30) is provided downstream of the second heating section in the transport direction of the metal strip, for cooling the metal strip.

According to the configuration [10] above, in a heat treatment facility (e.g., continuous annealing facility) in which a cooling unit (e.g., a cooling zone) is provided downstream of a first heating unit (e.g., a preheating zone) and a second heating unit (e.g., a heating zone), as described in [1] above, the metal strip can be efficiently heated and the amount of high-temperature gas flowing from the second heating unit into the induction heating unit can be reduced. Therefore, according to the configuration [10] above, the metal strip can be efficiently heated while protecting the induction heating device from high temperatures and reducing the risk of damage.

The above describes embodiments of the present invention, but the present invention is not limited to the above-described embodiments and also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions such as "identical,""equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained.
Furthermore, in this specification, the expressions "comprise,""include," or "have" a component are not exclusive expressions that exclude the presence of other components.

1 Heat treatment equipment 2 Furnace body 2a First furnace body section 2b Second furnace body section 2c Third furnace body section 4 Conveyor roll 6 First heating section 8 Second heating section 10 Induction heating section 12 Induction heating device 14 Bypass passage 16 Heating device 18 Afterburner 20 Exhaust duct 22 Sealing device 23 Sealing member 24 Low-temperature gas supply section 24a Supply pipe 24b Supply valve 26 Low-temperature gas discharge section 26a Discharge pipe 26b Discharge valve 28 Soaking zone 30 Cooling section 32 Cooling nozzle 36 Coil 38 Heat insulating material 40 Airtight material S Metal strip

Claims (10)

1. A heat treatment facility for heat treating a metal strip, comprising:
a first heating section and a second heating section each configured to heat the metal strip with a heating means not including an induction heating device;
a first furnace body that accommodates the first heating unit;
a second furnace body that accommodates the second heating unit;
an induction heating unit including an induction heating device for heating the metal strip;
Equipped with
the first heating section, the induction heating section, and the second heating section are arranged in this order in a conveying direction of the metal strip,
a bypass passage for guiding gas inside the second furnace body to the inside of the first furnace body, bypassing the induction heating section; the second heating unit is configured to combust fuel and heat the metal strip using heat generated by the combustion of the fuel;
The heat treatment facility according to claim 1 , wherein the first heating section is configured to heat the metal strip by convection heating using an atmospheric gas inside the first furnace body section. the second heating unit includes a burner configured to combust the fuel and emit a flame generated by the combustion of the fuel toward the metal strip;
3. The heat treatment facility according to claim 2, wherein combustion gas generated by combustion of the fuel in the second heating section is introduced into the inside of the first furnace body section through the bypass passage. the second heating section includes a radiant tube configured to heat the metal strip;
The first heating section is configured to heat the metal strip by convection heating using an atmospheric gas inside the first furnace body section,
2. The heat treatment facility according to claim 1, wherein the atmospheric gas in the second furnace body is introduced into the first furnace body through the bypass passage. The heat treatment facility according to claim 1 , wherein the bypass passage includes a duct provided outside the first furnace body and the second furnace body. 5. The heat treatment equipment according to claim 1, further comprising a sealing device provided at least between the first heating section and the induction heating section or between the induction heating section and the second heating section in the transport direction of the metal strip, the sealing device being configured to suppress gas from flowing inside the first furnace body section or the second furnace body section into the induction heating section. The heat treatment equipment according to claim 6 , wherein the sealing device includes a sealing member that is provided facing the surface of the metal strip and configured to be driven along a direction perpendicular to the surface of the metal strip. The heat treatment facility according to claim 6 , further comprising a low-temperature gas supply unit for supplying gas at a temperature lower than that of the gas inside the second furnace body unit to the induction heating unit. The induction heating device is
a coil for generating magnetic flux;
a heat insulating material provided between the coil and the metal strip;
The heat treatment facility according to any one of claims 1 to 4, comprising: The heat treatment facility according to claim 1 , further comprising a cooling section provided downstream of the second heating section in the transport direction of the metal strip, for cooling the metal strip.