Atmosphere replacement structure of heat treatment system and heat treatment furnace

Abstract

This heat treatment system comprises a first supply device, a first heat treatment furnace, a first recovery device, a second supply device, a second heat treatment furnace, and a second recovery device. The first heat treatment furnace comprises: a loading port disposed in the vicinity of the first supply device; an unloading port; a heat treatment unit; and a first conveying device for conveying saggars in a first direction directed from the loading port toward the unloading port of the first heat treatment furnace. The second heat treatment furnace comprises: a loading port disposed in the vicinity of the second supply device; an unloading port; a heat treatment unit; and a second conveying device for conveying saggars in a second direction, opposite to the first direction, from the loading port to the unloading port of the second heat treatment furnace. Each of the first heat treatment furnace and the second heat treatment furnace additionally includes an exchange unit which is disposed between the heat treatment unit and the unloading port, and which isolates the heat treatment unit from the outside of the unloading port. Each exchange unit is provided with openable and closeable doors, which are formed from a heat insulating material, between the exchange unit and the heat treatment unit and between the exchange unit and the unloading port.

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a technology for heat treating a workpiece. [Background technology]

[0002] A heat treatment furnace (for example, a roller hearth kiln or a pusher kiln) may be used to heat treat an object to be treated. In general, there is a demand for improved productivity and reduced use of atmospheric gas in a heat treatment furnace. For example, Patent Document 1 discloses a heat treatment system including a heat treatment furnace that transports an object to be treated in a forward direction and a heat treatment furnace that transports an object to be treated in a reverse direction. In the heat treatment system of Patent Document 1, the object to be treated is placed in a sagger and transported through the heat treatment furnace, and is heat treated while the sagger is transported through the heat treatment furnace. The sagger is repeatedly used for the heat treatment of the object to be treated. In the heat treatment system of Patent Document 1, the discharge port of the heat treatment furnace that transports the object to be treated in the forward direction is installed near the entrance of the heat treatment furnace that transports the object to be treated in the reverse direction, and the discharge port of the heat treatment furnace that transports the object to be treated in the reverse direction is installed near the entrance of the heat treatment furnace that transports the object to be treated in the forward direction. This allows the sagger to be transported into the next heat treatment furnace at a high temperature. This shortens the time required to heat the sagger and the length of the heat treatment furnace, thereby reducing the amount of atmospheric gas used in the heat treatment furnace. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-85367 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a replacement section is provided on the discharge side of a heat treatment furnace to replace the atmosphere between the inside of the heat treatment furnace (i.e., the heat treatment section where the workpiece is heat-treated) and the outside of the heat treatment furnace. The replacement section has openable and closable doors at the boundary with the heat treatment section and the boundary with the outside of the heat treatment furnace. When replacing the atmosphere in the replacement section, the replacement section needs to be well sealed by the door. However, in the heat treatment system of Patent Document 1, the saggers are carried into the next heat treatment furnace while still at a high temperature, so that the saggers are carried out of the heat treatment furnace at a high temperature. As a result, the temperature inside the replacement section also becomes high, making it difficult to ensure the sealing of the replacement section by the door.

[0005] This specification discloses a technique that allows the saggers to be removed from the heat treatment furnace while still hot. [Means for solving the problem]

[0006] In a first aspect of the technology disclosed in the present specification, a heat treatment system includes a first supply device, a first heat treatment furnace, a first recovery device, a second supply device, a second heat treatment furnace, and a second recovery device. The first supply device is disposed near the second recovery device and supplies the workpiece to a sagger transported from the second recovery device. The first heat treatment furnace is disposed near the first supply device and includes an inlet for transporting the sagger to which the workpiece has been supplied by the first supply device, an outlet for transporting the transported sagger, a heat treatment section disposed between the inlet and the outlet of the first heat treatment furnace and heat-treating the workpiece supplied to the sagger while the sagger is transported from the inlet to the outlet of the first heat treatment furnace, and a first transport device for transporting the sagger in a first direction from the inlet to the outlet of the first heat treatment furnace. The first recovery device is disposed near the discharge port of the first heat treatment furnace and recovers the workpieces heat-treated in the first heat treatment furnace from the saggers. The second supply device is disposed near the first recovery device and supplies new workpieces to the saggers from which the workpieces were recovered by the first recovery device. The second heat treatment furnace is disposed near the second supply device and includes an inlet for carrying in the saggers to which the workpieces have been supplied by the second supply device and an outlet for carrying out the carried-in saggers, a heat treatment section disposed between the inlet and outlet of the second heat treatment furnace and heat-treating the workpieces supplied to the saggers while the saggers are being transported from the inlet to the outlet of the second heat treatment furnace, and a second transport device for transporting the saggers from the inlet to the outlet of the second heat treatment furnace in a second direction opposite to the first direction. The second recovery device is disposed near the discharge port of the second heat treatment furnace and recovers the objects heat-treated in the second heat treatment furnace from the sagger. Each of the first heat treatment furnace and the second heat treatment furnace further includes a replacement unit disposed between the heat treatment section of the heat treatment furnace and the discharge port of the heat treatment furnace and isolating the heat treatment section of the heat treatment furnace from the outside of the discharge port of the heat treatment furnace. The replacement unit includes an openable door made of a heat insulating material between the heat treatment section of the heat treatment furnace and the discharge port of the heat treatment furnace.

[0007] In the above heat treatment system, doors made of a heat insulating material are provided at the entrance and exit of the replacement section. By forming the doors from a heat insulating material, the heat resistance of the doors can be ensured and thermal deformation of the doors can be suppressed. This allows the replacement section to isolate the heat treatment section from the outside of the furnace and ensure airtightness (sealability) of the heat treatment section. Therefore, the saggers can be transported to the replacement section at a high temperature, and the saggers can be transported to the outside of the heat treatment furnace at a high temperature.

[0008] The atmosphere replacement structure disclosed in this specification is a heat treatment furnace equipped with an inlet for carrying a sagger containing an object to be treated into the furnace, a heat treatment section for heat-treating the object to be treated that has been carried into the sagger from the inlet, an outlet for carrying out the sagger containing the object to be treated that has been heat-treated in the heat treatment section, and a first transport device for transporting the sagger from the inlet to the outlet, and maintains an atmosphere in the internal space of the heat treatment section. The atmosphere replacement structure includes a replacement chamber disposed between the heat treatment section and the outlet, a first door provided between the replacement chamber and the heat treatment section, and a second door provided between the replacement chamber and the outlet. Each of the first door and the second door is formed of a heat insulating material.

[0009] In the above atmosphere replacement structure, a first door made of a heat insulating material is provided at the entrance of the replacement chamber, and a second door made of a heat insulating material is provided at the exit of the replacement chamber, so that the same effects as those of the above heat treatment system can be achieved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a top view showing a schematic configuration of a heat treatment system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a first heat treatment furnace, and is a vertical cross-sectional view of the heat treatment furnace taken along a plane parallel to the transport direction of the workpiece. [Diagram 3] 3 is a cross-sectional view taken along line III-III in FIG. 2 . [Figure 4] FIG. 2 is a block diagram showing the configuration of a control system for a first heat treatment furnace. [Diagram 5]FIG. 4 is a side view showing a schematic configuration of an unloading-side atmosphere replacement structure provided on the unloading side of the thermal processing section; [Figure 6] FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] 4A and 4B are side views showing the configuration of a pressing device, in which (a) shows a state in which the pressing device is pressing the door, and (b) shows a state in which the pressing device is not pressing the door. [Figure 9] FIG. 4 is a front view showing the configuration of the door, the chain and the shaft.

[0011] The main features of the embodiments described below are listed below. Note that the technical elements described below are independent technical elements that exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0012] In a second aspect of the technology disclosed in the present specification, in the first aspect, each of the first heat treatment furnace and the second heat treatment furnace may further include a contact surface arranged between at least one of the doors arranged in the replacement unit and the heat treatment unit, which contacts the entire outer periphery of the door when the door is closed, and a pressing device arranged outside the replacement unit and pressing the door against the contact surface when the door is closed. With this configuration, the pressing device can seal between the door and the heat treatment unit. Therefore, the airtightness of the heat treatment unit by the door can be improved, and the atmosphere of the heat treatment unit can be maintained.

[0013] In a third aspect of the technology disclosed in the present specification, in the second aspect, the contact surface may include a seal portion that seals between the door and the contact surface. The seal portion may be formed of a fiber-based seal material. With this configuration, the heat resistance of the seal portion can be ensured.

[0014] In a fourth aspect of the technology disclosed in this specification, in the second or third aspect, the pressing device may include a pressing part capable of contacting the door, a cylinder arranged on the outlet side of the pressing part and pressing the pressing part, and a connecting part connecting the pressing part and the cylinder. The pressing part and the connecting part may be formed of a heat-resistant material. With this configuration, the cylinder can be installed at a position away from the door, which becomes hot, by connecting the cylinder and the pressing part via the connecting part. This makes it possible to suppress the occurrence of thermal effects on the cylinder.

[0015] In a fifth aspect of the technology disclosed in the present specification, in the fourth aspect, the pressing portion may be made of a ceramic material. The pressing portion abuts against the door, which becomes hot. By making the pressing portion from ceramic, the heat resistance of the pressing portion can be improved.

[0016] In a sixth aspect of the technique disclosed in the present specification, in the fourth or fifth aspect, each of the first heat treatment furnace and the second heat treatment furnace may further include a chain connected to an upper end of at least one of the doors arranged in the replacement section and supporting the door. With this configuration, the door is freely suspended by the chain. This ensures sealing when the door is pressed by the pressing device even if the door is thermally deformed.

[0017] In a seventh aspect of the technique disclosed in the present specification, in the sixth aspect, each of the first heat treatment furnace and the second heat treatment furnace may further include a shaft that rotates in a first direction to wind up the chain and rotates in a second direction opposite to the first direction to wind down the chain, and a drive device that rotates the shaft. The shaft may be disposed above the chain such that its axis is horizontal and perpendicular to the conveying direction. The door may move upward by winding up the chain on the shaft, and move downward by winding down the chain on the shaft. According to this configuration, the shaft that winds up and winds down the chain is disposed with its axis horizontal and perpendicular to the conveying direction (sideways). Then, one end of the chain is connected to the door, and the other end of the chain is connected to the shaft disposed outside the replacement unit. Therefore, when the door is open, the space inside the heat treatment unit communicates with the space outside the replacement unit (heat treatment furnace) through the space in which the chain is disposed. In order to ensure airtightness of the heat treatment unit, it is preferable to seal the space in which the chain is disposed from the space outside the replacement unit. By adopting a configuration in which the chain is wound up by a shaft, the shaft, which is the driving part, only rotates around its axis, so the area of ​​the part that needs to be sealed can be reduced. On the other hand, if a configuration different from the above is adopted, for example, in which the chain is moved up and down by a cylinder, the cylinder, which is the driving part, needs a stroke length according to the dimensions of the door, and the area of ​​the part that needs to be sealed becomes larger. Therefore, with the above configuration, the area of ​​the part that needs to be sealed can be reduced.

[0018] In an eighth aspect of the technology disclosed in the present specification, in the seventh aspect, the door may be configured to be opened by moving it downward. The upper part of the door is easily affected by heat. By moving the door downward to open it, the door is less likely to be affected by heat when it is open.

[0019] In the ninth aspect of the technique disclosed in the present specification, in the first aspect described above, each of the first heat treatment furnace and the second heat treatment furnace may further include a loading side replacement part that is arranged between the heat treatment part of the heat treatment furnace and the entrance of the heat treatment furnace and isolates the heat treatment part of the heat treatment furnace from the outside of the entrance of the heat treatment furnace. The loading side replacement part may include an openable and closable door made of a heat insulating material between the heat treatment part of the heat treatment furnace and the entrance of the heat treatment furnace. According to this configuration, in addition to the unloading side of the heat treatment furnace, a replacement part is also provided on the loading side of the heat treatment furnace. As a result, the replacement part is provided on both the loading side and the unloading side of the heat treatment furnace, and the heat treatment part and the outside of the heat treatment furnace can be isolated by the replacement part on both the loading side and the unloading side of the heat treatment furnace. In addition, since the loading side replacement part also has a door made of a heat insulating material at the entrance and the exit, the heat resistance of the door is ensured and thermal deformation of the door is suppressed. Therefore, the high-temperature saggers can be transported from the outside to the carry-in replacement section, and the high-temperature saggers transported to the carry-in replacement section can be carried into the heat treatment furnace. EXAMPLES

[0020] The heat treatment system 1 of this embodiment will be described with reference to the drawings. As shown in FIG. 1, the heat treatment system 1 includes a first supply device 80a, a first heat treatment furnace 10a, a first recovery device 82a, a second supply device 80b, a second heat treatment furnace 10b, and a second recovery device 82b. The heat treatment system 1 heat-treats the object to be treated housed in a sagger 2 (see FIG. 2). In this embodiment, the object to be treated housed in the sagger 2 is a powder of a lithium-ion battery positive electrode material. In the heat treatment system 1 of this embodiment, the sagger 2 is configured to circulate between the first supply device 80a, the first heat treatment furnace 10a, the first recovery device 82a, the second supply device 80b, the second heat treatment furnace 10b, and the second recovery device 82b. The object to be treated is heat-treated while the sagger 2 is transported in the first heat treatment furnace 10a or the second heat treatment furnace 10b.

[0021] First, the first supply device 80a and the second supply device 80b will be described. The first supply device 80a is disposed between the second recovery device 82b and the first heat treatment furnace 10a (specifically, the entrance 20a of the first heat treatment furnace 10a). The first supply device 80a supplies new objects to be treated to the empty sagger 2 from which the objects to be treated have been recovered by the second recovery device 82b. The second supply device 80b is disposed between the first recovery device 82a and the second heat treatment furnace 10b (specifically, the entrance 20b of the second heat treatment furnace 10b). The second supply device 80b supplies new objects to the empty sagger 2 from which the objects to be treated have been recovered by the first recovery device 82a. The first supply device 80a and the second supply device 80b have the same configuration. Therefore, the first supply device 80a will be described below.

[0022] The first supply device 80a is a device that supplies the object to be treated (i.e., powder) into the sagger 2. The first supply device 80a may be configured to supply powder into the sagger 2, and the specific structure is not particularly limited. For example, the first supply device 80a includes a supply unit and a leveling unit. The supply unit is configured to supply powder into the inside of the sagger 2. Specifically, the supply unit includes a supply port that drops powder from above the sagger 2 into the inside of the sagger 2. The supply port is arranged so as to be located above the center of the sagger 2 when the sagger 2 is arranged in the supply unit. The supply unit includes a positioning device, and the positioning device positions the sagger 2 transported to the supply unit so as to be located below the supply port. The contact surface of the positioning device with the sagger 2 is formed of a ceramic material. This ensures the heat resistance of the positioning device, and the high-temperature sagger 2 can be positioned in the supply unit. The supply unit may be provided with multiple supply ports. The supply unit supplies powder into the sack 2 by dropping the powder from above, so that when the supply unit supplies powder to the sack 2, the upper surface of the powder in the sack 2 rises at a position below the supply port. The leveling unit levels the powder supplied into the sack 2 by the supply unit. Specifically, the leveling unit is configured to level the upper surface of the powder by pressing the upper surface of the powder in the sack 2 with the side of a flat plate. By leveling the upper surface of the powder with the leveling unit, the upper surface of the powder contained in the sack 2 becomes approximately horizontal. In addition, the supply device 80a is provided with a heat insulating material for blocking heat on a member (frame, etc.) located above the sack 2. This allows the supply device 80a to ensure heat resistance against the high-temperature sack 2, and to supply powder to the high-temperature sack 2.

[0023] Next, the first heat treatment furnace 10a and the second heat treatment furnace 10b will be described. The first heat treatment furnace 10a and the second heat treatment furnace 10b heat-treat the object in the sagger 2.

[0024] 2 to 4, the first heat treatment furnace 10a includes a heat treatment section 12, an entrance atmosphere replacement structure 40, an exit atmosphere replacement structure 42, a transport device (24, 26), and a control device 28. The first heat treatment furnace 10a heat-treats the workpiece contained in the sagger 2 while the sagger 2 is transported through the heat treatment section 12 by the transport device (24, 26).

[0025] The thermal processing section 12 has an outer shape of a substantially rectangular parallelepiped, and is surrounded by a ceiling wall 14a, a bottom wall 14b, side walls 14c and 14d, and two doors 48, which will be described later. As shown in FIG. 2, the ceiling wall 14a is arranged parallel to the bottom wall 14b (i.e., parallel to the XY plane). As shown in FIG. 3, the side walls 14c and 14d are arranged parallel to the conveying direction and perpendicular to the ceiling wall 14a and the bottom wall 14b (i.e., parallel to the XZ plane). As shown in FIG. 2, the entrance of the thermal processing section 12 is separated from the entrance-side atmosphere replacement structure 40 by one of the two doors 48, and the exit of the thermal processing section 12 is separated from the exit-side atmosphere replacement structure 42 by the other door 48. A plurality of heaters 16a and 16b and a plurality of conveying rollers 24 are arranged in the thermal processing section 12. The heaters 16a are disposed above the transport rollers 24 at a predetermined interval in the transport direction, and the heaters 16b are disposed below the transport rollers 24 at a predetermined interval in the transport direction. When the heaters 16a and 16b generate heat, the space 18 in the heat treatment unit 12 is heated and the workpiece contained in the sagger 2 is heated.

[0026] The carry-in side atmosphere replacement structure 40 is provided adjacent to the carry-in side of the thermal processing section 12, and the unloading side atmosphere replacement structure 42 is provided adjacent to the unloading side of the thermal processing section 12. The configurations of the carry-in side atmosphere replacement structure 40 and the unloading side atmosphere replacement structure 42 will be described in detail later.

[0027] The transport device (24, 26) includes a plurality of transport rollers 24 and a roller drive device 26. The transport rollers 24 transport the sagger 2. The transport device (24, 26) transports the sagger 2 from the entrance 20a of the first heat treatment furnace 10a into the entrance atmosphere replacement structure 40, and then transports it through the entrance atmosphere replacement structure 40 into the heat treatment section 12. The transport device (24, 26) then transports the sagger 2 from the heat treatment section 12 into the exit atmosphere replacement structure 42, and then transports it through the exit atmosphere replacement structure 42 to the outside from the exit 22a of the first heat treatment furnace 10a. In the first heat treatment furnace 10a, the transport device (24, 26) transports the sagger 2 in the +X direction.

[0028] The conveying roller 24 is cylindrical, and its axis extends in a direction perpendicular to the conveying direction (i.e., in the Y direction). All of the conveying rollers 24 have the same diameter, and are arranged at equal intervals at a constant pitch in the conveying direction. The conveying rollers 24 are supported rotatably about their axes, and rotate when a driving force from a roller driving device 26 is transmitted to the conveying rollers 24. The roller driving device 26 is a driving device (e.g., a motor) that drives the conveying rollers 24. The roller driving device 26 is connected to the conveying rollers 24 via a power transmission mechanism. When the driving force from the roller driving device 26 is transmitted to the conveying rollers 24 via the power transmission mechanism (e.g., a mechanism using a sprocket and a chain), the conveying rollers 24 rotate.

[0029] As shown in Fig. 3, in this embodiment, a plurality of saggers 2 are stacked vertically on the conveying roller 24, and are placed and conveyed in a state where a plurality of saggers 2 are lined up in a direction perpendicular to the conveying direction (Y direction in Fig. 3). The conveying device (24, 26) is configured to align the plurality of saggers 2 lined up in the Y direction when conveying the saggers 2 from the entrance atmosphere replacement structure 40 into the heat treating section 12, and convey the plurality of saggers 2 lined up in the Y direction into the heat treating section 12 at the same time. Similarly, the conveying device (24, 26) is configured to align the plurality of saggers 2 lined up in the Y direction when conveying the saggers 2 from the heat treating section 12 to the exit atmosphere replacement structure 42, and convey the plurality of saggers 2 lined up in the Y direction to the exit atmosphere replacement structure 42 at the same time. The configuration in which the conveying device (24, 26) aligns the plurality of saggers 2 lined up in the Y direction will be described in detail later.

[0030] The control device 28 is configured by, for example, a computer equipped with a CPU, a ROM, and a RAM. As shown in Fig. 4, the control device 28 is connected to the heaters 16a, 16b, the roller driving device 26, the door pressing device 56 (described later), and the door lifting device 74 (described later), and controls the heaters 16a, 16b, the roller driving device 26, the door pressing device 56, and the door lifting device 74.

[0031] As shown in FIG. 1, the second heat treatment furnace 10b is arranged in parallel to the first heat treatment furnace 10a with a gap in the Y direction. The second heat treatment furnace 10b is arranged so that the direction in which the saggers 2 are transported is opposite to that of the first heat treatment furnace 10a. That is, the entrance 20b of the second heat treatment furnace 10b is arranged near the exit 22a of the first heat treatment furnace 10a, and the exit 22b of the second heat treatment furnace 10b is arranged near the entrance 20a of the first heat treatment furnace 10a. As a result, the transport direction of the saggers 2 in the first heat treatment furnace 10a (direction from the -X direction to the +X direction) and the transport direction of the saggers 2 in the second heat treatment furnace 10b (direction from the +X direction to the -X direction) are opposite to each other. As described above, the second heat treatment furnace 10b has substantially the same configuration as the first heat treatment furnace 10a, and therefore a detailed description of the configuration is omitted.

[0032] Next, the first recovery device 82a and the second recovery device 82b will be described. The first recovery device 82a is disposed between the first heat treatment furnace 10a (specifically, the discharge port 22a of the first heat treatment furnace 10a) and the second supply device 80b. The first recovery device 82a recovers the workpiece heat-treated in the first heat treatment furnace 10a from the sagger 2. The second recovery device 82b is disposed between the second heat treatment furnace 10b (specifically, the discharge port 22b of the second heat treatment furnace 10b) and the first supply device 80a. The second recovery device 82b recovers the workpiece heat-treated in the second heat treatment furnace 10b from the sagger 2. The first recovery device 82a and the second recovery device 82b have the same configuration. Therefore, the first recovery device 82a will be described below.

[0033] The first recovery device 82a is a device that recovers the object to be treated (i.e., powder) that has been heat-treated in the first heat treatment furnace 10a from the sagger 2. The first recovery device 82a may be configured to recover the powder from the sagger 2, and the specific structure is not particularly limited. For example, the first recovery device 82a includes an inversion recovery section that recovers the object by inverting the sagger 2 in the vertical direction, and an air recovery section that peels off the object to be treated (in this embodiment, powder) that is attached to the surface of the sagger 2 with air and recovers it. The inversion recovery section moves the powder in the sagger 2 to a recovery container by inverting the sagger 2 in the vertical direction. As a result, almost all of the powder contained in the sagger 2 moves to the recovery container. The inversion recovery section includes a handling section for inverting the sagger 2, and the handling section is formed of a ceramic material. The handling section comes into contact with the sagger 2. By forming the handling part from a ceramic material, the heat resistance of the handling part can be ensured, and the handling part can grasp the high-temperature sagger 2. After that, the inverting and collecting part inverts the sagger 2 again in the up-down direction to return it to its original orientation. The air collecting part is used after the powder in the sagger 2 is collected by the inverting and collecting part. The air collecting part sucks air and the like in the sagger 2 while blowing air onto the inner surface of the sagger 2. By blowing air onto the inner surface of the sagger 2, the powder adhering to the inner surface of the sagger 2 is peeled off from the inner surface. When the air and the like in the sagger 2 are sucked while blowing air onto the inner surface of the sagger 2, the powder peeled off from the inner surface of the sagger 2 is sucked together with the air and the like. As a result, the powder remaining on the inner surface of the sagger 2 is collected, and the collection rate of the powder increases. In the above example, the first collecting device 82a is equipped with an air collecting part, but is not limited to such a configuration. For example, the powder remaining on the inner surface of the sagger 2 may be peeled off and collected by a rotating brush.

[0034] As described above, the saggers 2 are transported in a circulating manner between the first supply device 80a, the first heat treatment furnace 10a, the first recovery device 82a, the second supply device 80b, the second heat treatment furnace 10b, and the second recovery device 82b. Between the first supply device 80a, the first heat treatment furnace 10a, the first recovery device 82a, the second supply device 80b, the second heat treatment furnace 10b, and the second recovery device 82b, roller conveyors are respectively arranged to transport the saggers 2. Note that as long as the saggers 2 can be transported in a circulating manner between the first supply device 80a, the first heat treatment furnace 10a, the first recovery device 82a, the second supply device 80b, the second heat treatment furnace 10b, and the second recovery device 82b, a transport device other than the roller conveyor (for example, a belt conveyor, etc.) may be used.

[0035] In this embodiment, the first heat treatment furnace 10a and the second heat treatment furnace 10b are installed so that the conveying direction of the saggers 2 in the first heat treatment furnace 10a and the conveying direction of the saggers 2 in the second heat treatment furnace 10b are opposite to each other. That is, the distance between the discharge port 22a of the first heat treatment furnace 10a and the inlet 20b of the second heat treatment furnace 10b is short, and the distance between the discharge port 22b of the second heat treatment furnace 10b and the inlet 20a of the first heat treatment furnace 10a is also short. This allows the saggers 2 used for heat treatment in the first heat treatment furnace 10a to be carried into the second heat treatment furnace 10b while still at a high temperature. Similarly, the saggers 2 used for heat treatment in the second heat treatment furnace 10b can also be carried into the first heat treatment furnace 10a while still at a high temperature. Therefore, the time required to heat the saggers 2 in the heat treatment furnaces 10a and 10b can be shortened, and the length of the heat treatment section 12 of the first heat treatment furnace 10a and the second heat treatment furnace 10b can be shortened, and the energy required to heat the object to be treated can be reduced. In addition, since the saggers 2 are carried out from the first heat treatment furnace 10a and the second heat treatment furnace 10b at a high temperature, there is no need to provide a cooling section on the carrying-out side of the heat treatment section 12 of the first heat treatment furnace 10a and the second heat treatment furnace 10b, or even if a cooling section is provided, there is no need to cool the saggers 2 to a low temperature, so the length of the cooling section can be shortened. For example, in a conventional heat treatment furnace, the saggers 2 are cooled to about 200 degrees before being carried out from the heat treatment furnace, but in the heat treatment system 1 of this embodiment, the saggers 2 can be carried out from the first heat treatment furnace 10a and the second heat treatment furnace 10b only if they are cooled to 400 degrees. In this way, the lengths of the first heat treatment furnace 10a and the second heat treatment furnace 10b can be shortened, and therefore the amount of atmospheric gas used in the first heat treatment furnace 10a and the second heat treatment furnace 10b can be reduced.

[0036] Here, the carry-in atmosphere replacement structure 40 and the unloading atmosphere replacement structure 42 will be described. As described above, the first heat treatment furnace 10a and the second heat treatment furnace 10b have the same configuration except that the first heat treatment furnace 10a and the second heat treatment furnace 10b are installed so that the conveying directions of the saggers 2 are opposite to each other. Hereinafter, the carry-in atmosphere replacement structure 40 and the unloading atmosphere replacement structure 42 of the first heat treatment furnace 10a will be described. The carry-in atmosphere replacement structure 40 is provided between the carry-in entrance 20a and the heat treatment section 12 of the first heat treatment furnace 10a, and the unloading atmosphere replacement structure 42 is provided between the heat treatment section 12 and the unloading exit 22a of the first heat treatment furnace 10a. The carry-in atmosphere replacement structure 40 and the unloading atmosphere replacement structure 42 are used to maintain the atmosphere in the internal space of the heat treatment section 12.

[0037] As described above, in the heat treatment system 1 of this embodiment, the sagger 2 used for heat treatment in one of the two heat treatment furnaces 10a, 10b is carried into the other heat treatment furnace 10b, 10a while still at a high temperature. For this reason, the entrances 20a, 20b of the heat treatment furnaces 10a, 10b must have a configuration capable of carrying in the sagger 2 in a high temperature state, and the exits 22a, 22b of the heat treatment furnaces 10a, 10b must have a configuration capable of carrying out the sagger 2 in a high temperature state. For this reason, the entrance atmosphere replacement structure 40 has a configuration capable of carrying in the sagger 2 in a high temperature state into the heat treatment unit 12, and the exit atmosphere replacement structure 42 has a configuration capable of carrying out the sagger 2 in a high temperature state from the heat treatment unit 12. The entrance atmosphere replacement structure 40 and the exit atmosphere replacement structure 42 have substantially the same configuration. Therefore, the following will describe in detail the unloading-side atmosphere replacement structure 42 provided on the unloading port 22a side of the first heat treatment furnace 10a.

[0038] As shown in FIG. 5, the unloading-side atmosphere replacement structure 42 includes a replacement chamber 44, a heat treatment-side seal structure 46, and an exterior-side seal structure 47.

[0039] The replacement chamber 44 is disposed adjacent to the heat treatment section 12 on the downstream side of the heat treatment section 12. A door 48a is provided between the replacement chamber 44 and the heat treatment section 12, and a door 48b is provided between the replacement chamber 44 and the discharge port 22a. The doors 48a and 48b can be opened and closed, and are configured to seal between the replacement chamber 44 and the heat treatment section 12 and between the replacement chamber 44 and the discharge port 22a when closed. The configuration of the doors 48a and 48b to seal between the replacement chamber 44 and the heat treatment section 12 and between the replacement chamber 44 and the discharge port 22a will be described in detail later. The replacement chamber 44 is provided with a transport roller 24. The sagger 2 is transported from the heat treatment section 12 to the replacement chamber 44 by the transport roller 24. The replacement chamber 44 is provided with an air inlet, and the same gas as the atmospheric gas supplied to the heat treatment section 12 is supplied from the air inlet. In the replacement chamber 44, the atmosphere is replaced between the inside of the heat treatment section 12 and the outside of the first heat treatment furnace 10a. By providing the replacement chamber 44, it is possible to prevent air from the outside of the first heat treatment furnace 10a from entering the heat treatment section 12, and also to prevent the atmospheric gas in the heat treatment section 12 from flowing out to the outside of the first heat treatment furnace 10a.

[0040] Here, the transportation of the sagger 2 in the replacement chamber 44 will be described. The transport roller 24 arranged near the replacement chamber 44 of the heat treatment unit 12 is driven by a roller drive unit 26 (hereinafter referred to as roller drive unit 26b) different from the roller drive unit 26 (hereinafter referred to as roller drive unit 26a) that drives the other transport rollers 24 in the heat treatment unit 12. The transport roller 24 arranged in the replacement chamber 44 is driven by a roller drive unit 26 (hereinafter referred to as roller drive unit 26c) different from the roller drive units 26a, 26b that drive the transport rollers 24 in the heat treatment unit 12. Furthermore, a transport roller 24 is also arranged outside the replacement chamber 44 (i.e., outside the first heat treatment furnace 10a), and the transport roller 24 arranged outside the replacement chamber 44 is driven by a roller drive unit 26 (hereinafter referred to as roller drive unit 26d) different from the roller drive units 26a, 26b, 26c. The roller driving devices 26a and 26d drive the respective transport rollers 24 so that the transport rollers 24 rotate at approximately the same speed. The roller driving devices 26b and 26c are configured to change the rotation speed of the transport rollers 24 by adjusting the output.

[0041] A mechanism for aligning the multiple saggers 2 lined up in the Y direction is provided near the replacement chamber 44 of the heat treatment unit 12. Specifically, a stopper (not shown) is provided near the boundary between the heat treatment unit 12 and the replacement chamber 44. The stopper is configured to be movable in the vertical direction. When the stopper is positioned at the top, it protrudes upward from the conveying rollers 24 and abuts against the side surfaces of the multiple saggers 2 in the conveying direction, and when the stopper is retracted downward, it is accommodated below the conveying rollers 24. By positioning the stopper at the top, the multiple saggers 2 lined up in the Y direction are aligned.

[0042] The saggers 2 are transported in the heat treatment unit 12 by the transport rollers 24 connected to the roller drive unit 26a, and are transported by the transport rollers 24 connected to the roller drive unit 26b in the vicinity of the replacement chamber 44. At this time, the stopper is located above the transport rollers 24, the door 48a is in a closed state, and the door 48b is also in a closed state. When the saggers 2 are transported to the vicinity of the boundary with the replacement chamber 44, the stopper aligns the multiple saggers 2 lined up in the Y direction. A sensor is provided near the stopper, and when all the saggers 2 lined up in the Y direction are detected by the sensor, the door 48a is opened. Then, when the door 48a is opened, the output of the roller drive units 26b and 26c is increased and the stopper is moved downward. At this time, the roller drive units 26b and 26c drive each of the transport rollers 24 so that the transport rollers 24 rotate at approximately the same speed. By increasing the output of the roller drive devices 26b and 26c, the roller drive devices 26b and 26c rotate at high speed. Then, the sagger 2 is carried into the replacement chamber 44 at high speed by the conveying roller 24 connected to the roller drive device 26b, and in the replacement chamber 44, it is conveyed at high speed by the conveying roller 24 connected to the roller drive device 26c. When the sagger 2 is conveyed to a predetermined position in the replacement chamber 44, the roller drive devices 26b and 26c stop the rotation of the conveying roller 24. Then, the sagger 2 stops at a predetermined position in the replacement chamber 44. Then, the door 48a is closed. As a result, the sagger 2 is accommodated in the replacement chamber 44, and the two doors 48a and 48b are closed. Then, after a set predetermined time has elapsed, the door 48b is opened, and the conveying roller 24 in the replacement chamber 44 is rotated by the roller drive device 26c. At this time, the roller driving devices 26c and 26d drive the respective conveying rollers 24 so that the conveying rollers 24 rotate at approximately the same speed. Then, the sagger 2 is carried out to the outside of the replacement chamber 44 (i.e., the outside of the first heat treatment furnace 10a) by the conveying rollers 24 in the replacement chamber 44, and is further carried completely to the outside of the replacement chamber 44 by the conveying rollers 24 connected to the roller driving device 26d.

[0043] Next, the heat treatment section side seal structure 46 and the external side seal structure 47 will be described. The heat treatment section side seal structure 46 is provided between the replacement chamber 44 and the heat treatment section 12, and has a configuration for sealing between the replacement chamber 44 and the heat treatment section 12. The external side seal structure 47 is provided between the replacement chamber 44 and the outside of the first heat treatment furnace 10a, and has a configuration for sealing between the replacement chamber 44 and the outside of the first heat treatment furnace 10a. The heat treatment section side seal structure 46 and the external side seal structure 47 have the same configuration. Therefore, the heat treatment section side seal structure 46 will be described in detail below.

[0044] As shown in FIGS. 5 to 9, the heat treatment section side seal structure 46 includes a door 48a (hereinafter simply referred to as “door 48”), a door pressing device 56, a chain 70, a shaft 72, and a door lifting device 74.

[0045] The door 48 is disposed between the replacement chamber 44 and the heat treatment section 12. As shown in FIG. 6, the door 48 is in the form of a substantially rectangular plate, and is larger than the inner surface of the heat treatment section 12 when the heat treatment section 12 is cut in a direction perpendicular to the conveying direction (see FIG. 5). A chain suspending section 50 (described in detail later) is connected to the upper part of the door 48. A chain 70 (described in detail later) is connected to the chain suspending section 50. The door 48 is connected to the chain 70 via the chain suspending section 50. The door 48 is configured to be movable in the vertical direction by the chain 70. When the door 48 is positioned upward, the door 48 is disposed between the heat treatment section 12 and the replacement chamber 44, and blocks the gap between the heat treatment section 12 and the replacement chamber 44. That is, when the door 48 is positioned upward, the door 48 is in a closed state. On the other hand, when the door 48 moves downward, the door 48 is positioned below the conveying rollers 24, and the heat treatment section 12 and the replacement chamber 44 communicate with each other. That is, when the door 48 is in the lower position, the door 48 is in the open state.

[0046] The door 48 is made of a cement-based or calcium silicate plate-shaped insulating material. As described above, the first heat treatment furnace 10a carries out the sagger 2 while the sagger 2 is still in a high temperature state. Therefore, the atmospheric temperature of the heat treatment section 12 is high even near the boundary with the replacement chamber 44. When the door 48 is closed, it is exposed to the space of the heat treatment section 12. By making the door 48 of a cement-based or calcium silicate plate-shaped insulating material, the heat resistance of the door 48 can be ensured, and thermal deformation of the door 48 can be suppressed.

[0047] As shown in Fig. 6 and Fig. 7, the door 48 is provided with a seal structure 52. The seal structure 52 is disposed on the surface of the door 48 facing the thermal treatment unit 12, and is disposed so as to coincide with the end face of the thermal treatment unit 12 facing the replacement chamber 44 when the door 48 is disposed between the thermal treatment unit 12 and the replacement chamber 44 (when the door 48 is closed). That is, the seal structure 52 is disposed in the circumferential direction along the end face of the thermal treatment unit 12 on the unloading side. A frame (not shown) is disposed in the circumferential direction along the end face on the unloading side of the thermal treatment unit 12, and the seal structure 52 is disposed so as to abut against the frame. That is, the surface of the seal structure 52 facing the thermal treatment unit 12 has an abutment surface that abuts against the frame.

[0048] The seal structure 52 includes a seal portion 53 and a holding member 54. The seal portion 53 is formed of one part that is continuous in the circumferential direction. The seal portion 53 is disposed over the entire circumferential direction of the seal structure 52. The seal portion 53 is also formed of a fiber-based seal member. The holding member 54 is fixed to the door 48 and disposed along the seal portion 53. Specifically, the holding member 54 is disposed on the surface of the door 48 on the heat treatment unit 12 side so as to sandwich the seal portion 53. The holding member 54 holds the seal portion 53. In this embodiment, the holding member 54 is formed of a plurality of parts that are divided in the circumferential direction. The holding member 54 may be formed of one part that is continuous in the circumferential direction. The seal portion 53 can seal between the heat treatment unit 12 and the door 48 when the door 48 is closed. The heat resistance of the seal portion 53 can be ensured by forming the seal portion 53 from a fiber-based seal material. In this embodiment, a space is provided inside a frame (not shown) provided on an end face of the heat treatment section 12, and a cooling medium is accommodated in the space. By accommodating a cooling medium (e.g., air, water, etc.) in the frame, the frame can be cooled, and thus the door 48 can be cooled. Note that, although the seal structure 52 is provided on the door 48 in this embodiment, the seal structure may be provided on the surface of the frame provided on the end face of the heat treatment section 12 that faces the door 48.

[0049] The door pressing device 56 is disposed above the replacement chamber 44, and presses the door 48 toward the heat treatment section 12 when the door 48 is closed. As shown in Fig. 5, the door pressing device 56 is disposed at two locations, near the upper end and the lower end of the door 48, and presses the upper end and the lower end of the door 48. As shown in Figs. 8(a) and 8(b), the door pressing device 56 includes a pressing portion 58, a cylinder 60, and a connecting structure 62 that connects the pressing portion 58 and the cylinder 60.

[0050] The pressing portion 58 is cylindrical and is disposed so that its axis coincides with the conveying direction. The pressing portion 58 is disposed near the door 48. The pressing portion 58 is formed of a ceramic material. The cylinder 60 is connected to the pressing portion 58 via a connecting structure 62. The cylinder 60 is disposed on the same straight line as the axis of the pressing portion 58, and is disposed at a position (+X direction) farther from the door 48 than the pressing portion 58. The cylinder 60 presses the pressing portion 58 toward the door 48 via the connecting structure 62. As shown in FIG. 8(a), when the cylinder 60 presses the pressing portion 58 when the door 48 is in the closed position, the pressing portion 58 abuts against the surface of the door 48 on the side opposite to the heat treatment portion 12 side (the surface on the replacement chamber 44 side in the heat treatment portion side seal structure 46). By pressing the door 48 toward the heat treatment portion 12 side with the pressing portion 58, the sealing property of the seal portion 53 can be improved. The pressing portion 58 also abuts against the door 48. As described above, the door 48 becomes hot when closed. By forming the pressing portion 58 from a ceramic material, the heat resistance of the pressing portion 58 can be ensured. In this embodiment, the entire pressing portion 58 is formed from a ceramic material, but the present invention is not limited to this configuration. It is sufficient that the pressing portion 58, especially the tip portion 58a, has high heat resistance, and only the tip portion 58a may be formed from a ceramic material.

[0051] The connecting structure 62 includes a bush 64, a joint 66, and a seal portion 68. The bush 64 is attached to the wall surface of the replacement chamber 44, and the end of the pressing portion 58 on the cylinder 60 side is slidably inserted into the bush 64. The bush 64 is made of a heat-resistant material. The joint 66 is disposed between the pressing portion 58 and the cylinder 60. In this embodiment, the joint 66 is a floating joint. The gap between the bush 64 and the pressing portion 58 is sealed by the seal portion 68. The seal portion 68 is made of a fiber-based seal material. In the connecting structure 62, the bush 64 and the seal portion 68 are disposed in a position close to the pressing portion 58, i.e., in a position relatively close to the door 48. For this reason, the bush 64 and the seal portion 68 are likely to become hot. By forming the bush 64 and the seal portion 68 from a heat-resistant material, the heat resistance of the bush 64 and the seal portion 68 can be ensured. On the other hand, since the cylinder 60 is connected to the retaining portion 58 via the connecting structure 62, it is disposed at a position relatively far from the retaining portion 58, i.e., the door 48. By disposing the cylinder 60 via the connecting structure 62, it is possible to suppress the occurrence of thermal effects on the cylinder 60.

[0052] The chain 70 is used to open and close the door 48. As shown in FIG. 9, the chain 70 is disposed in the chain suspension part 50. The chain suspension part 50 is disposed on the upper part of the door 48 and on the ceiling wall of the replacement chamber 44. Specifically, two chain suspension parts 50 are disposed on the ceiling wall of the replacement chamber 44. The two chain suspension parts 50 are disposed on the upper part of the door 48, one of which is disposed near the end of the door 48 in the +Y direction, and the other is disposed near the end of the door 48 in the -Y direction. The chain suspension part 50 extends upward from the ceiling wall of the replacement chamber 44. The chain suspension part 50 is provided with a hole 50a extending in the vertical direction and a through hole 50b extending parallel to the upper surface of the door 48 (i.e., in the Y direction). The lower end of the hole 50a opens into the interior of the replacement chamber 44, and the upper end of the hole 50a communicates with the through hole 50b. The chain 70 is disposed in the hole 50a. The through hole 50b is provided near the upper end of the chain suspending part 50. The shaft 72 passes through the through hole 50b. A seal part 76 is disposed in the through hole 50b, and the seal part 76 seals the gap between the shaft 72 and the chain suspending part 50. This prevents the inside of the replacement chamber 44 from communicating with the outside of the replacement chamber 44 via the hole 50a and the through hole 50b.

[0053] The chain 70 has a lower end connected to the door 48 and an upper end connected to the shaft 72. Specifically, a sprocket is installed on the shaft 72 at a connection portion with the chain 70, and the chain 70 is connected to the sprocket. The shaft 72 has both ends passing through the through holes 50b of the two chain hanging parts 50, respectively, and a central portion is disposed above the door 48. The shaft 72 is disposed above the door 48 along the upper surface of the door 48. The shaft 72 is supported so as to be rotatable around its axis, and rotates when a driving force of a door lifting device 74 is transmitted to the shaft 72. The door lifting device 74 is a driving device (e.g., a motor) that drives the shaft 72. The door lifting device 74 is connected to the shaft 72 via a power transmission mechanism. When the driving force of the door lifting device 74 is transmitted to the shaft 72 via a power transmission mechanism (e.g., a mechanism using a sprocket and a chain), the shaft 72 rotates. The door lifting device 74 can rotate the shaft 72 in both directions (forward and reverse directions) by adjusting the output. Hereinafter, one of the rotation directions of the shaft 72 will be referred to as the "first direction" and the opposite rotation direction will be referred to as the "second direction."

[0054] When the shaft 72 is rotated in the first direction, the chain 70 connected to the shaft 72 is wound around the sprocket of the shaft 72. That is, when the shaft 72 is rotated in the first direction, the shaft 72 winds up the chain 70. The lower end of the chain 70 is connected to the door 48. Therefore, when the shaft 72 winds up the chain 70, the door 48 moves upward. On the other hand, when the shaft 72 is rotated in the second direction, the chain 70 that was wound around the sprocket of the shaft 72 moves downward. That is, when the shaft 72 is rotated in the second direction, the shaft 72 winds down the chain 70. When the shaft 72 winds down the chain 70, the door 48 moves downward.

[0055] As described above, the door 48 moves in the vertical direction by the chain 70. That is, the door 48 is held in a freely suspended state by the chain 70. Also, as described above, the joint 66 of the door pressing device 56 is a floating joint. The door 48 is made of a ceramic material, so that heat resistance is ensured, but there is a possibility that it may be slightly thermally deformed by exposure to high temperatures. For example, when the door 48 slides to open and close, if the door 48 is thermally deformed and distorted, a part of the seal portion 53 provided in the seal structure 52 may not contact the end of the heat treatment portion 12, and the sealing performance of the seal portion 53 may be reduced. In this embodiment, the door 48 is suspended by the chain 70, and a floating joint is used for the door pressing device 56. Therefore, even if the door 48 is thermally deformed, the entire seal portion 53 can be brought into contact with the end of the heat treatment portion 12 by pressing with the door pressing device 56. Therefore, the sealing performance of the seal portion 53 (i.e., the door 48) can be ensured.

[0056] In addition, by winding up and down the chain 70 by the shaft 72, the through hole 50b provided in the chain hanging part 50 for passing the shaft 72 can be made smaller. Therefore, the area in which the seal part 76 is arranged can be made smaller. For example, when the chain is moved in the vertical direction by a cylinder or the like, a guide part in the vertical direction is provided in the chain hanging part, and it becomes necessary to seal the guide part. In this case, the guide part needs to have a length according to the vertical dimension of the door 48, and it is necessary to seal a relatively wide range in the vertical direction. In this embodiment, by winding up and down the chain 70 by the shaft 72, the range to be sealed can be made smaller.

[0057] Points to note regarding the heat treatment system 1 described in the embodiment will be described below. The replacement chamber 44 in the embodiment is an example of a "replacement unit", the door pressing device 56 is an example of a "pressing device", the connecting structure 62 is an example of a "connection unit", and the door lifting device 74 is an example of a "driving device".

[0058] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility.

Claims

1. A heat treatment system including a first supply device, a first heat treatment furnace, a first recovery device, a second supply device, a second heat treatment furnace, and a second recovery device, The first supply device is disposed near the second recovery device and supplies the material to a sagger transported from the second recovery device; The first heat treatment furnace is an inlet disposed near the first supply device and through which the sagger to which the material to be treated has been supplied by the first supply device is carried; an outlet for carrying out the carried-in sagger; a heat treatment section disposed between an inlet and an outlet of the first heat treatment furnace, for heat-treating the workpiece supplied to the sagger while the sagger is being transported from the inlet to the outlet of the first heat treatment furnace; a first conveying device that conveys the sagger in a first direction from an entrance to an exit of the first heat treatment furnace, the first recovery device is disposed near an outlet of the first heat treatment furnace and recovers the workpiece that has been heat-treated in the first heat treatment furnace from the sagger; the second supply device is disposed near the first recovery device and supplies new material to the sagger in which the material has been recovered by the first recovery device; The second heat treatment furnace is an inlet disposed near the second supply device and through which the sagger to which the material to be treated has been supplied by the second supply device is carried; an outlet for carrying out the carried-in sagger; a heat treatment section disposed between an inlet and an outlet of the second heat treatment furnace, for heat-treating the workpiece supplied to the sagger while the sagger is being transported from the inlet to the outlet of the second heat treatment furnace; a second conveying device that conveys the sagger in a second direction opposite to the first direction from an entrance to an exit of the second heat treatment furnace, the second recovery device is disposed near an outlet of the second heat treatment furnace and recovers the workpiece that has been heat-treated in the second heat treatment furnace from the sagger; Each of the first heat treatment furnace and the second heat treatment furnace further includes a replacement unit disposed between a heat treatment unit of the heat treatment furnace and an unloading port of the heat treatment furnace, and isolating the heat treatment unit of the heat treatment furnace from an outside of the unloading port of the heat treatment furnace; the replacement unit includes an openable / closable door formed of a heat insulating material between a heat treatment unit of the heat treatment furnace and an outlet of the heat treatment furnace, Each of the first heat treatment furnace and the second heat treatment furnace is a contact surface that is disposed between at least one of the doors disposed in the replacement section and the heat treatment section and that contacts an entire outer periphery of the door when the door is closed; A pressing device is disposed outside the replacement unit and presses the door toward the abutment surface when the door is closed, The pressing device is A pressing portion capable of contacting the door; a cylinder disposed closer to the discharge port than the pressing unit and pressing the pressing unit; A connecting portion that connects the pressing portion and the cylinder, The pressing portion and the connecting portion are formed of a heat-resistant material, A heat treatment system, wherein the pressing portion, the connecting portion and the cylinder are arranged in a straight line.

2. A heat treatment system as described in claim 1, wherein the holding portion, the connecting portion and the cylinder are arranged perpendicular to the contact surface.

3. A heat treatment system as described in claim 1, wherein the connecting portion is attached to a wall surface of the replacement portion and is sealed between the connecting portion and the wall surface.

4. The contact surface includes a seal portion that seals between the door and the contact surface, The thermal processing system of claim 1 , wherein the seal is formed of a fiber-based seal material.

5. The heat treatment system of claim 1 , wherein the retainer is made of a ceramic material.

6. 2. The heat treatment system of claim 1, wherein each of the first heat treatment furnace and the second heat treatment furnace further includes a chain connected to an upper end of at least one of the doors disposed in the replacement section and supporting the door.

7. Each of the first heat treatment furnace and the second heat treatment furnace is a shaft that rotates in a third direction to wind up the chain and rotates in a fourth direction opposite to the third direction to wind down the chain; and a drive unit for rotating the shaft, The shaft is disposed above the chain such that its axis is horizontal and perpendicular to the conveying direction, 7. The thermal treatment system of claim 6, wherein the door moves upward by winding the chain up on the shaft and moves downward by winding the chain down on the shaft.

8. The thermal treatment system of claim 7 , wherein the door is configured to be opened by moving it downwardly.

9. Each of the first heat treatment furnace and the second heat treatment furnace further includes an entry-side replacement unit that is disposed between a heat treatment unit of the heat treatment furnace and an entry port of the heat treatment furnace and isolates the heat treatment unit of the heat treatment furnace from an outside of the entry port of the heat treatment furnace; 2 . The heat treatment system according to claim 1 , wherein the loading side replacement section includes openable and closable doors formed of a heat insulating material between the heat treatment section of the heat treatment furnace and a loading entrance of the heat treatment furnace.

10. an entrance for carrying the sagger containing the material to be treated into the furnace; a heat treatment section for heat-treating the workpiece supplied to the sagger brought in through the carry-in port; a discharge port for discharging the sagger to which the workpiece that has been heat-treated in the heat treatment section has been supplied, out of the furnace; a transport device that transports the sagger from the inlet to the outlet, and an atmosphere replacement structure that maintains an atmosphere in an internal space of the heat treatment section in the heat treatment furnace, A replacement chamber disposed between the heat treatment section and the discharge port; a first door provided between the replacement chamber and the heat treatment section; A second door provided between the replacement chamber and the discharge port; a contact surface that is disposed between at least one of the first door and the second door and a heat treatment section and that contacts an entire outer periphery of the at least one door when the at least one door is closed; a pressing device disposed outside the replacement chamber and pressing the at least one door against the abutment surface in a closed state of the at least one door, each of the first door and the second door is formed of a thermal insulating material; The pressing device is A pressing portion capable of contacting the at least one door; a cylinder disposed closer to the discharge port than the pressing unit and pressing the pressing unit; A connecting portion that connects the pressing portion and the cylinder, The pressing portion and the connecting portion are formed of a heat-resistant material, An atmosphere replacement structure, wherein the pressing portion, the connecting portion, and the cylinder are arranged in a straight line.

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