JPH10227572A - Heat treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the control and prevention of generating uneven atmosphere surely by a method wherein a gas supplying passage, sending the same kind of gas as atmospheric gas into a heat treatment zone and the outside of the same, is provided in a gap between a hearth unit and a furnace main body. SOLUTION: In order to permit the elevation and rotation of the hearth unit 2 of a heat treatment furnace A, a predetermined gap 8 is formed between the furnace main body 1 and the hearth unit 2 while a gas supplying passage 10, supplying the same kind of gas as atmospheric gas is arranged in the gap 8 while forming the gas supplying passage 10 of a first gas supplying pipe 11 and a second gas supplying pipe 12. Respective gas supplying pipes are arranged while meandering and penetrating the lower part of the furnace main body 1 and being wound around the gap 8 so that the route of the same becomes long. In this case, a plurality of inner side gas sending ports 13, sending out the gas from the gap 8 toward the inside of a heat treatment zone 4, is formed at the upper surface side of an annular section 11a while a plurality of outer side gas sending ports 14, sending out the gas from the gap 8 toward the outside of the heat treatment zone 4, are formed at the lower surface side of the annular section 12a. On the other hand, an exhaust damper 19, discharging the gas with a predetermined rate to the outside of the system, is arranged at the lower outside of the heat treatment furnace A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat treatment furnace,
More specifically, the present invention relates to a heat treatment furnace used for heat-treating a ceramic molded body used for manufacturing a ceramic electronic component.

[0002]

2. Description of the Related Art One of the heat treatment furnaces used in the process of manufacturing ceramic electronic parts and the like is, for example, a heat treatment furnace as shown in FIG. This heat treatment furnace C has a furnace body 51 having an open bottom surface.
And a hearth section (table) 52 movably arranged on the bottom side of the furnace body 51 and a heat treatment zone 54 formed by the furnace body 51 and the hearth section 52. A heater 55 made of SiC or the like, an atmosphere gas supply path 56 disposed around the furnace body 51, and a heat treatment zone 54.
A gas exhaust path 57 is provided for exhausting combustion gas generated in the chamber, unconsumed atmosphere gas, and the like.
FIG. 5 shows that the object to be heat-treated
And accommodated in the heat treatment zone 54.

[0005] The heat treatment using the heat treatment furnace C is usually performed by the following method.

[0004] First, a box 53 containing an object to be heat-treated is placed on the hearth section 52 which has been lowered, and the hearth section 52 is raised to house the box 53 in the heat treatment zone 54. Then, an atmosphere gas is supplied from the atmosphere gas supply path 56, and the heater 55 is energized to generate heat, thereby raising the temperature in the heat treatment zone 54, and performing degreasing (binder removal) and main firing under a predetermined atmosphere. Then, after cooling to a predetermined temperature, the hearth 52 is lowered, and the object to be heat-treated housed therein together with the casing 53 is taken out.

[0005] In the conventional heat treatment furnace C, the combustion gas and the like are exhausted from the gas exhaust path 57 and the atmosphere gas supply path 5 disposed around the furnace body 51.
Heat treatment zone 5 by supplying the atmosphere gas from
Although the atmosphere in 4 is kept at a predetermined atmosphere,
It is difficult to make the furnace atmosphere uniform up to a position near the hearth section 52 below the heat treatment zone 54, and the atmosphere may be biased.

In some cases, it is necessary to switch the atmosphere in the furnace from an oxidizing atmosphere to a reducing atmosphere or from a reducing atmosphere to an oxidizing atmosphere during the firing step. In the vicinity of the hearth section 52 below the zone 54, the atmosphere gas may not be sufficiently replaced, and it may not be possible to switch to the desired atmosphere.

In the conventional heat treatment furnace C,
Since a predetermined gap 58 is formed between the furnace body 51 and the hearth 52 to enable the furnace hearth 52 to move up and down, the gas, binder decomposition gas, and the like that have entered the gap 58 are cooled. Tar content (ie, residual carbon content)
Again enters the heat treatment zone 54 and disturbs the atmosphere.

[0008] The binder decomposition gas generated at the time of degreasing has a higher specific gravity than air, and not only accumulates near the hearth, but also flows into a gap 58 between the furnace body 51 and the hearth 52 and passes therethrough. In the meantime, the temperature drops and tars. Then, a part of the tar component is vaporized again and enters the heat treatment zone 54 as described above, and the remaining tar component is accumulated in the gap 58 and its surroundings, generating odor, deteriorating the function of the heat insulating material, electric leakage, etc. There is a problem that causes.

[0009] Here, as a conventional heat treatment furnace,
Although the description has been given of the heat treatment furnace in which the hearth part can be moved up and down as an example, the heat treatment furnace (hearth rotary heat treatment furnace) in which the hearth part can be moved up and down and rotated is also widely used. This also applies to this hearth rotary heat treatment furnace.

The present invention has been made to solve the above problems, and can maintain the atmosphere in the heat treatment zone uniformly, can reliably switch the atmosphere, and cause tar decomposition of binder decomposition gas and the like. It is an object of the present invention to provide a heat treatment furnace capable of preventing generation of an unpleasant odor, deterioration of the function of a heat insulating material, and leakage.

[0011]

In order to achieve the above object, a heat treatment furnace according to the present invention performs a heat treatment of an object to be heat-treated together with a hearth portion on which the object to be heat-treated is placed, and the furnace floor portion. A furnace body for forming a heat treatment zone to be heated, a heater for raising the temperature of the heat treatment zone to a predetermined temperature, an atmosphere gas supply path for supplying an atmosphere gas into the heat treatment zone, A gas supply path for supplying a gas of the same type as the atmospheric gas to the gap in the furnace body and blowing the gas toward the inside and outside of the heat treatment zone is provided.

A gas of the same kind as the atmospheric gas is supplied from the gas supply passage into a gap between the hearth and the furnace body, and the gas is blown toward the inside and outside of the heat treatment zone. Airflow is generated in the vicinity and in the gap between the hearth and the furnace body, and binder decomposition gas and the like accumulates in the vicinity of the hearth in the heat treatment zone, and the atmosphere becomes non-uniform. It is possible to suppress or prevent the failure to be performed. Also,
A gas of the same type as the atmospheric gas is supplied to the vicinity of the hearth and the gap between the hearth and the furnace body, and a portion of the binder decomposition gas entering the gap is supplied to the heat treatment zone by the gas blown out to the inside of the heat treatment zone. While being returned, the binder decomposition gas that has entered the depth of the gap is driven out of the system by the gas blown out of the heat treatment zone, thereby preventing the binder decomposition gas from becoming tar and accumulating to prevent odor. It is possible to reliably suppress and prevent the occurrence, the deterioration of the function of the heat insulating material, and the occurrence of electric leakage. In the present invention, the gas of the same kind as the atmospheric gas is a broad concept including the same gas as the atmospheric gas and a gas having substantially the same composition.

Further, in the heat treatment furnace according to the present invention, the gas supply passage has a first gas supply pipe having an internal gas outlet for blowing gas from the gap toward the inside of the heat treatment zone; A second gas supply pipe having an outer gas outlet for blowing gas toward the outer side. Gas supply path,
In the case where the first gas supply pipe having the inner gas outlet and the second gas supply pipe having the outer gas outlet are provided, the heat treatment zone is connected to the first gas supply pipe and the second gas supply pipe. Gas can be reliably blown out toward the inside and outside of the furnace, and binder decomposition gas and gas before replacement accumulate in the vicinity of the hearth and in the gap between the furnace body and the hearth. Can be efficiently prevented from occurring. Therefore, the atmosphere in the heat treatment zone can be made uniform, the atmosphere in the heat treatment zone can be reliably switched, and the generation of malodor caused by tarification (liquefaction) of binder decomposition gas and the like can be prevented. It is possible to suppress or prevent the deterioration of the function of the heat insulating material and the occurrence of electric leakage.

Further, in the heat treatment furnace according to the present invention, the gas supply passage may include an internal gas outlet for blowing the gas toward the inside of the heat treatment zone through a single gas supply pipe; And an external gas outlet for blowing the gas toward the outside. By arranging both the internal gas outlet and the external gas outlet in one gas supply pipe, it becomes possible to simplify the configuration of the gas supply path and reduce the size of the equipment, Equipment costs can be reduced.

Further, in the heat treatment furnace of the present invention, the outer gas outlet and the inner gas outlet have a diameter of 0.2 mm.
１．０1.0 mm. The size of the outer gas outlet and the inner gas outlet is set to 0.
By setting the range of 2 to 1.0 mm, it is possible to blow out gas at a predetermined force from a gap between the furnace main body and the hearth while preventing clogging due to tar components and the like. It can be more effective.

Further, the heat treatment furnace of the present invention is characterized in that the hearth is driven to rotate. In a heat treatment furnace in which the hearth is driven to rotate, it is necessary to form a sufficient gap between the furnace body and the hearth.
In particular, the various problems described above are likely to occur, but by applying the present invention to a rotary hearth type heat treatment furnace, the heat treatment zone can be reliably set to a desired atmosphere,
It is possible to suppress and prevent the generation of offensive odor, the deterioration of the function of the heat insulating material, and the occurrence of electric leakage due to tar formation of the binder decomposition gas and the like.

Further, in the heat treatment furnace of the present invention, the gas supply path is meandered and penetrated in the furnace main body and is guided to the gap, so that the path is lengthened to increase the preheating time of the gas passing through the inside. It is characterized by having made it. By guiding the gas supply path to the gap by meandering and penetrating the inside of the furnace main body, the path becomes long, and the gas passing through the inside is sufficiently preheated, so that the temperature of the heat treatment zone may be lowered. Therefore, the above-described effects of the present invention can be reliably achieved.

Further, the heat treatment furnace of the present invention is characterized in that a discharge mechanism for discharging a gas blown from the gas supply path toward the outside of the heat treatment zone at a predetermined rate to the outside of the system is provided. I have. By providing a discharge mechanism for discharging the gas blown out from the gas supply path toward the outside of the heat treatment zone at a predetermined rate to the outside of the system, the gas blown out from the first gas supply pipe can return to the heat treatment zone. It is possible to reliably discharge the binder decomposed gas and the gas remaining in the hearth portion before the replacement, and prevent the gas from remaining in the furnace, thereby making the present invention more effective.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is a front view showing a heat treatment furnace according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. The heat treatment furnace (hearth rotary heat treatment furnace) A of this embodiment includes a furnace body 1 having an open bottom surface, and a furnace body 1.
A furnace floor (table) 2 arranged to be able to move up and down and rotatable, and a heat treatment zone 4 formed by a furnace main body 1 and a furnace floor 2 on the bottom side of the furnace. , An atmosphere gas supply pipe 6 inserted into the heat treatment zone 4 from the upper part of the furnace main body 1, and a gas exhaust for exhausting a combustion gas generated in the heat treatment zone 4, an unconsumed atmosphere gas, and the like. The apparatus is provided with a path 7 and a rotation driving means (electric motor) 9 for driving the hearth 2 to rotate. FIG. 1 shows that the object to be heat-treated
And accommodated in the heat treatment zone 4.

In the heat treatment furnace A, a predetermined gap 8 is formed between the furnace main body 1 and the hearth 2 in order to enable the hearth 2 to move up and down and rotate.
A gas supply path 10 for supplying a gas of the same type as the atmospheric gas is provided in the gap 8. In this embodiment, the gas supply path 10 is connected to the first gas supply pipe 11 and the second gas supply pipe 11.
It is formed from a gas supply pipe 12.

Each of the first gas supply pipe 11 and the second gas supply pipe 12 has a lengthened path.
It is arranged so as to meander through the lower part of the furnace body 1 and to go around the gap 8.

On the upper surface side of the annular portion 11a which goes around the gap 8 of the first gas supply pipe 11, a plurality of internal gas outlets 13 for blowing gas from the gap 8 toward the inside of the heat treatment zone 4 are provided. On the lower surface side of the annular portion 12a that goes around the gap 8 of the second gas supply pipe 12, a plurality of outside gas blowers that blow gas from the gap 8 toward the outside of the heat treatment zone 4 are formed. An outlet 14 is formed.

The first gas supply pipe 11 and the second gas supply pipe 12 are made of a pipe made of a material such as Inconel or stainless steel having an outer diameter of 6 to 10 mm and which does not soften or deform at the operating temperature of the furnace. In addition, the inner gas outlet 13 and the outer gas outlet 14 are
a are formed at a predetermined pitch in the circumferential direction, and have a diameter of 0.2 to 1.0 mm. Further, the first gas supply pipe 11 has a gas supply amount adjustment and a first gas supply pipe 11.
A solenoid valve 15 and a flow meter 16 for opening and closing the gas supply unit are provided, and a solenoid valve 17 for adjusting the gas supply amount and opening and closing the second gas supply tube 12 is provided in the second gas supply pipe 12.
And a flow meter 18.

A second gas supply pipe 12 is provided on the outer periphery of the lower part of the heat treatment furnace A formed by the furnace body 1 and the hearth 2.
A discharge mechanism (exhaust damper) 19 for discharging a gas blown out of the system toward the outside of the heat treatment zone 4 at a predetermined rate is provided.

Next, a method for performing a heat treatment using the heat treatment furnace A will be described. First, a box 3 containing an object to be heat-treated is placed on the hearth 2 which has been lowered, and the hearth 2 is raised to house the box 3 in the heat treatment zone 4. Then, the hearth 2 is rotated to supply the atmosphere gas from the atmosphere gas supply pipe 6 and the first gas supply pipe 11
While supplying the same gas as the atmospheric gas from the second gas supply pipe 12 to the gap 8 between the furnace main body 1 and the hearth 2, the heater 5 is energized to generate heat, thereby raising the temperature inside the heat treatment zone 4, (Debinder) with a temperature profile of
And main firing is performed. In addition, the first gas supply pipe 11 and the second
The gas supply pipe 12 meanders inside the furnace main body 1 and
To the hearth 2 and the path is long,
Since it is sufficiently preheated and supplied to the gap 8, degreasing and main firing are performed reliably according to a predetermined temperature profile. After cooling to a predetermined temperature, the hearth 2 is lowered, and the object to be heat-treated is taken out together with the casing 3.

In the above-described steps of degreasing and main baking, the first gas supply pipe 1 is inserted into the gap 8 between the furnace body 1 and the hearth 2.
Since the same gas as the atmospheric gas is supplied from the first and second gas supply pipes 12, even if the binder decomposition gas (a gas containing a component that liquefies and becomes tar when cooled) flowing into the gap 8 flows in the degreasing step. Before being tarred, the gas is blown upward from the internal gas outlet 13 of the first gas supply pipe 11 and returned to the heat treatment zone 4.
The remaining part of the binder decomposition gas flowing from the gap 8 to the lower part of the hearth 2 is below the outside gas outlet 14 of the second gas supply pipe 12 to such an extent that the binder decomposition gas in the gap 8 is not involved. Is discharged out of the system at a predetermined rate through the exhaust damper 19, so that the gas accumulated below the hearth 2 is reliably replaced, and the deposition of tar components is prevented. Therefore, the atmosphere in the heat treatment zone 4 can be made uniform, and the gas in the heat treatment zone 4 can be reliably switched by replacing the gas before switching (before the replacement), which tends to stay in the hearth during the atmosphere switching. In addition, it is possible to suppress and prevent the generation of offensive odor, the deterioration of the function of the heat insulating material, and the occurrence of electric leakage due to tarification (liquefaction) of the binder decomposition gas and the like.

[Embodiment 2] FIG. 3 is a front sectional view showing a heat treatment furnace (hearth rotary heat treatment furnace) B according to another embodiment of the present invention, and FIG. 4 is a sectional view taken along line IV-IV of FIG. is there. The heat treatment furnace B of this embodiment includes a gas supply path 20 including a single gas supply pipe 21 having heat resistance, such as Inconel or stainless steel. And, in this gas supply path 20,
On the upper surface side of the annular portion 21a disposed in the gap 8 between the furnace body 1 and the hearth 2, an internal gas outlet 23 for blowing gas toward the inside of the heat treatment zone 4 is formed. By forming an external gas outlet 24 for blowing gas toward the outside of the heat treatment zone 4 on the side, the gas can be blown out to the inside and outside of the heat treatment zone 4 with one gas supply pipe 21. It is formed so that it can be.

The pitch of the inner gas outlets 23 is set so that the amount of gas blown from the inner gas outlets 23 is greater than the amount of gas blown from the outer gas outlets 24. The pitch is smaller than the arrangement pitch of the gas outlets 24. Further, the gas supply path 20 is provided with an electromagnetic valve 25 for adjusting the gas supply amount and opening and closing the gas supply path 20.
And a flow meter 26 are provided. On the side opposite to the side on which the solenoid valve 25 and the flow meter 26 are provided, the annular portion 21 is provided.
An end support joint 27 (FIG. 4) and a support end 28 (FIG. 4) for holding a are provided, and the support end 28 is sealed.

The other configuration is the same as that of the first embodiment, and the description is omitted. 3 and 4, the same reference numerals are given to the same or corresponding portions as those of the heat treatment furnace A shown in FIGS.

Also in the heat treatment furnace B of this embodiment, the inner gas outlet 23 on the upper surface side of the gas supply path 20 and the outer gas outlet 24 on the lower surface side of the gas supply path 20 allow the gas to flow between the furnace body 1 and the hearth 2. Since the same gas as the atmospheric gas is supplied to the gap 8 at a predetermined ratio, the same effect as that of the first embodiment can be obtained.

Further, in the heat treatment furnace B of this embodiment, since the gas supply path 20 is formed by a single gas supply pipe 21, the structure of the apparatus can be simplified to reduce the size of the equipment and reduce the production cost. It becomes possible to plan.

In the first and second embodiments, a case has been described in which a part of the gas supply pipe constituting the gas supply path (the part provided in the gap between the furnace body and the hearth) is annular. There is no particular limitation on the shape of the gas supply pipe constituting the gas supply path, and various shapes capable of supplying gas to the gap between the furnace body and the hearth can be used.
Further, the shapes, arrangement positions, arrangement pitches, and the like of the internal gas and the external gas outlet provided in the gas supply path are not limited to the above-described embodiment, and may be variously configured. Is possible.

In the first and second embodiments, the case where the SiC heater is used as the heater has been described. However, the type of the heater is not particularly limited, and other various heaters can be used.

The present invention is not limited to the above-mentioned embodiment in other respects. The type of heat treatment furnace such as debinding or main firing, continuous furnace or batch furnace, furnace body and furnace Regarding the specific shape and structure of the floor, the location of the atmosphere gas supply path and the gas exhaust path, the mechanism for raising and lowering and rotating the furnace floor, etc., various applications and modifications within the scope of the invention It is possible to add

[0036]

As described above, in the heat treatment furnace of the present invention, the same kind of gas as the atmospheric gas is supplied from the gas supply passage to the gap between the furnace floor and the furnace body. In addition, it is possible to reliably suppress the situation where the binder decomposition gas or the like accumulates in the gap between the furnace floor and the furnace main body and the atmosphere becomes non-uniform or it becomes difficult to switch the atmosphere gas.
Can be prevented.

Further, a gas of the same type as the atmospheric gas is supplied to the vicinity of the hearth and the gap between the hearth and the furnace body, and a part of the binder decomposition gas that has entered the gap is blown into the inside of the heat treatment zone. As the gas is returned to the heat treatment zone by the gas and the binder decomposition gas that has entered the depth of the gap is expelled out of the system by the gas blown to the outside of the heat treatment zone, the binder decomposition gas is converted to tar and accumulates. Thus, generation of offensive odor, deterioration of the function of the heat insulating material, generation of electric leakage, and the like can be reliably suppressed and prevented.

[0038] The gas supply path may include a first gas supply pipe having an internal gas outlet for blowing gas toward the inside of the heat treatment zone, and an external gas supply pipe for blowing gas toward the outside of the heat treatment zone. In the case where the gas supply path is provided with a second gas supply pipe having an outlet, the gas supply path includes a first gas supply pipe having an inner gas outlet, and a second gas supply pipe having an outer gas outlet. In the case of having a configuration, the gas is surely blown out from the first gas supply pipe and the second gas supply pipe toward the inside and outside of the heat treatment zone, and the vicinity of the hearth, the furnace body and the hearth It is possible to efficiently prevent the decomposed atmosphere from accumulating in the gap with the binder decomposition gas and the like. Therefore, the atmosphere in the heat treatment zone can be made uniform, and the atmosphere in the heat treatment zone can be reliably switched. It is possible to suppress or prevent the deterioration of the function and the occurrence of the electric leakage.

When an internal gas outlet and an external gas outlet are provided in one gas supply pipe, the structure of the gas supply path is simplified and the size of the equipment is reduced. And equipment cost can be reduced.

When the size of the outer gas outlet and the inner gas outlet is in the range of 0.2 to 1.0 mm in diameter, the gas is discharged to a predetermined size while preventing clogging due to tar components and the like. It becomes possible to blow out with force, and the present invention can be made more effective.

Further, in the heat treatment furnace of the type in which the hearth is driven to rotate, the structure tends to cause problems such as bias of the atmospheric gas and accumulation of tar, but by applying the present invention, By solving these problems, it is possible to ensure that the heat treatment zone has a desired atmosphere, and at the same time, generate bad smells due to tarification of binder decomposition gas and the like, decrease the function of the heat insulating material, generate electric leakage, etc. Can be suppressed and prevented.

When the gas supply path is meandering and penetrating the inside of the furnace main body so as to be led to the gap between the furnace main body and the hearth, the path becomes long, and the gas passing through the inside is sufficient. Since the preheating is performed, the above-described effects can be reliably obtained without lowering the temperature of the heat treatment zone, and the present invention can be made more effective.

When a discharge mechanism is provided for discharging a gas blown from the gas supply path toward the outside of the heat treatment zone to the outside of the system at a predetermined rate, the gas containing tar and the like can be reliably discharged to the system. It is possible to discharge the gas to the outside so that the gas does not stay in the furnace, and the present invention can be made more effective.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a heat treatment furnace according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of the heat treatment furnace of FIG.

FIG. 3 is a front sectional view showing a heat treatment furnace according to another embodiment of the present invention.

FIG. 4 is a sectional view taken along line IV-IV of the heat treatment furnace of FIG.

FIG. 5 is a front sectional view showing a conventional heat treatment furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 2 Furnace floor part (table) 3 Box 4 Heat treatment zone 5 Heater 6 Atmospheric gas supply pipe 7 Gas exhaust path 8 Gap 9 Rotation drive means (electric motor) 10 Gas supply path 11 First gas supply pipe 11a Annular part 12 Second gas supply pipe 12a Annular part 13 Internal gas outlet 14 External gas outlet 15, 17 Solenoid valve 16, 18 Flow meter 19 Discharge mechanism (exhaust damper) 20 Gas supply path 21 Gas supply pipe 21a Annular part 23 Inside Side gas outlet 24 External gas outlet 25 Solenoid valve 26 Flow meter 27 End support joint 28 Support end A, B Heat treatment furnace

Claims (7)

[Claims] A furnace floor on which a heat treatment object is mounted, a furnace body forming a heat treatment zone in which heat treatment of the heat treatment object is performed together with the hearth portion, and a heat treatment zone raised to a predetermined temperature. A heater for heating, an atmosphere gas supply path for supplying an atmosphere gas into the heat treatment zone, a gas of the same type as the atmosphere gas is supplied to a gap between the furnace floor and the furnace body, and the heat treatment zone A gas supply path for blowing the gas toward the inside and outside of the heat treatment furnace. A first gas supply pipe having an inside gas outlet for blowing gas from the gap toward the inside of the heat treatment zone; and a gas supply pipe having an inside gas outlet for blowing gas toward the outside of the heat treatment zone. 2. The heat treatment furnace according to claim 1, further comprising a second gas supply pipe having an external gas outlet that blows out. 3. 3. The gas supply path is connected to one gas supply pipe.
An internal gas outlet that blows out the gas toward the inside of the heat treatment zone, and an external gas outlet that blows out the gas toward the outside of the heat treatment zone. The heat treatment furnace according to claim 1, wherein 4. The heat treatment furnace according to claim 2, wherein the size of the outer gas outlet and the inner gas outlet is in the range of 0.2 to 1.0 mm in diameter. 5. The heat treatment furnace according to claim 1, wherein the hearth is driven to rotate. 6. The gas supply path is meandering and penetrating inside the furnace main body and is guided to the gap, so that the path is lengthened to increase the preheating time of gas passing through the inside. The heat treatment furnace according to claim 1. 7. An exhaust system according to claim 1, further comprising a discharge mechanism for discharging a gas blown from the gas supply path toward the outside of the heat treatment zone out of the system at a predetermined rate. The heat treatment furnace according to any one of the above.