WO2007086173A1 - Gas atmosphere heat treating apparatus and method - Google Patents

Abstract

It is intended to inhibit the penetration of oxygen at the time of carrying of treatment object in an apparatus and realize rapid elimination of any penetrated oxygen to thereby efficiently carry out the operation of heat treatment of treatment object. There is provided a gas atmosphere heat treating apparatus comprising an inlet gas replacing compartment, a thermal reduction compartment, a cooling compartment and an outlet compartment, wherein in the inlet gas replacing compartment, temperature control is made by temperature control means so as to ensure a temperature which is not higher than the temperature at which any oxygen having penetrated in transfer passage reacts with a metal part to thereby cause oxidation discoloration but not lower than the temperature at which water produced from any penetrated oxygen and hydrogen gas contained in first and second reducing atmosphere gases becomes steam, and wherein in the vicinity of carry-in aperture of the inlet gas replacing compartment, first and second moving doors are disposed with a given spacing, and wherein the second moving door closes the transfer passage with an interstice left upside, and wherein between the first and second doors, there is disposed a vent for discharging steam together with reducing atmosphere gas outside the apparatus, and wherein inside the first moving door, there is disposed inert gas emission means.

Description

 Specification

 Gas atmosphere heat treatment apparatus and method

 Technical field

 [0001] The present invention relates to a gas atmosphere heat treatment apparatus and a gas atmosphere heat treatment method for heat treating a metal part.

 Background art

 [0002] As a method for forming a metal part, there is a so-called hide mouth forming. The principle is that the outside of the metal pipe or metal plate is pressed with a metal mold and a strong water pressure is applied from the inside, so that the noise and plate are expanded and deformed freely. The metal parts thus formed must be relieved of stress during pressing, and for this purpose, the metal is recrystallized by heat treatment.

 As the gas atmosphere heat treatment apparatus for this heat treatment, for example, a heat-resistant metal mesh belt conveyor is provided in a heat-resistant metal mattle tube, and a heating device is disposed outside the pine-full tube. In some cases, a heat insulating material is provided so as to surround the pine tube and an atmosphere gas is supplied to make the muffle tube non-oxidized.

 [0003] In such a conventional gas atmosphere heat treatment apparatus, since the mesh belt conveyor is provided in the pine full cylinder, the mesh belt must be frequently replaced due to deterioration due to heat. There is a disadvantage that the operation of the heat treatment apparatus must be stopped. In the conventional heat treatment furnace, a heating device is provided outside the pine full cylinder to improve the hermeticity in the pine full cylinder and efficiently create a non-acidic soot state. There was a drawback of getting worse.

 [0004] In order to solve the above problems, a roller hearth type heat treatment apparatus in which a heating device such as an electric heater and a driving roller are provided inside the furnace body has been proposed.

For example, in the roller hearth type vacuum furnace described in Patent Document 1, a charging chamber, a heating chamber, a carburizing diffusion chamber, a cooling / holding chamber, a quenching chamber, and an extraction chamber are sequentially arranged up to the loading loca unloading port, In the transfer passage formed so as to be continuous with the plurality of chambers, an iron alloy as a processing object is provided. Transport rollers for transporting gold parts are provided, and the space between each chamber is cut by a vacuum seal door. In this roller hearth type vacuum furnace, in order to carry iron alloy parts from the charging chamber into the heating chamber, the vacuum seal door between the chambers is opened. At this time, outside air containing oxygen is relatively contained in the heating chamber. It seems to invade in a large amount, but this device and method for removing the outside air are described.

 [0005] Also, Patent Documents 2 to 4 describe the force hearth heat treatment furnace described in Patent Documents 2 to 4, which prevents oxygen from entering or invades when an object to be processed is carried from the carry-in entrance of the heat treatment furnace into the transfer passage. There is no description of the device or method for removing the outside air.

 For example, in order to brightly anneal a metal material such as stainless steel in a reducing atmosphere, when hydrogen is used as the atmosphere gas, it reacts with the hydrogen gas when the oxygen entering from the carry-in port reaches a predetermined level or more. There is a disadvantage that the risk of explosion increases. In addition, if the metal material that is the object to be processed reacts with oxygen that has entered from the carry-in port and causes acid discoloration in a heat treatment furnace at a predetermined temperature or higher, a relatively long time is required for the heat reduction process. However, there is also a problem that productivity decreases.

 [0006] Further, with reference to Patent Document 3, in the roller hearth type heat treatment apparatus, the end of the driving roller provided in the furnace protrudes from the furnace side wall force, and this force prevents the outside air from entering. In order to prevent leakage of the furnace atmosphere, the protruding end of the driving roller is covered with a gas purge type seal cover outside the furnace body side wall, and nitrogen gas is injected into the seal cover.

However, considering the fact that wiring such as a heater for heating and bearings for driving rollers are arranged in the seal cover and their heat-resistant temperature is about 120 ° C, a relatively large amount is contained in the seal cover. It is necessary to cool by sending nitrogen gas. When a relatively large amount of nitrogen gas is sent for cooling, it is considered that nitrogen gas flows into the furnace from the inside of the seal cover, and it is very difficult to adjust the atmospheric fluctuation in the furnace. When brightly annealing a metal material such as stainless steel in an atmosphere, the furnace temperature of the gas atmosphere heat treatment apparatus rises to about 1000 ° C, so nitrogen gas for gas purging is used for cooling in the seal cover. A relatively large amount in the seal cover It is necessary to send in. However, it is not preferable for the bright annealing process that a large amount of nitrogen gas flows into the furnace at this time as well, so the atmospheric pressure inside the furnace is adjusted to satisfy these conditions. It becomes very difficult to do.

 [0007] Further, in the roller hearth type continuous furnace of Patent Document 4, a gas purge chamber is provided outside the side wall of the furnace body from which the end of each drive roller protrudes, and the atmospheric gas supplied from the lower side of the gas purge chamber However, after passing around the ends of the drive rollers, the upper force is discharged, and openings are formed in the wall surface of the gas purge chamber, and the ends of the drive rollers protrude from the openings to the outside.

 In other words, the device of Patent Document 4 is based on the premise that outside air enters the gas purge chamber from the gap between each drive roller end and the wall surface opening, and the intruding outside air is a downward force in the gas purge chamber. It is intended to be eliminated by the atmospheric gas flowing upward. For this reason, when hydrogen is used as the atmospheric gas, there is a disadvantage that the hydrogen gas flowing in from the furnace in the gas purge chamber reacts with the air (oxygen) that has entered from the roller penetrating part and explodes. .

 Patent Document 1: JP 2003-14376 PR

 Patent Document 2: JP-A-7-90352

 Patent Document 3: Japanese Unexamined Patent Publication No. 2000-55564

 Patent Document 4: JP-A-6-94370

 Disclosure of the invention

 Problems to be solved by the invention

 [0008] The present invention is intended to solve the above-described conventional problems, and suppresses the intrusion of outside air containing oxygen when an object to be processed is carried into the apparatus, and reduces the invading oxygen. It is an object of the present invention to provide an apparatus and a method that can be quickly eliminated and can efficiently perform a heat treatment process of an object to be processed.

[0009] Further, the present invention suppresses the intrusion of outside air containing oxygen from the carry-in port of the object to be processed, and in addition to quickly removing the invading oxygen, a driving roller and a heating means outside the furnace body side wall It is possible to prevent the intrusion of outside air from the seal cover that covers the end of the furnace, suppress leakage of the furnace atmosphere, and adjust the atmosphere fluctuations in the furnace relatively easily. It is an object of the present invention to provide a gas atmosphere heat treatment apparatus capable of thermally treating an object.

 Means for solving the problem

 [0010] The above-described problems of the present invention are solved by the following means.

 [0011] (1) Carrying-in loca A plurality of sections are provided up to the unloading outlet, and a drive roller is arranged in parallel in the plurality of sections to form a transfer path for metal parts. The first and second reducing atmosphere gases are supplied so as to be higher, and the first and second reducing atmosphere gases contain hydrogen gas, and are heat treatment apparatuses that heat-treat while moving metal parts with a driving roller. An inlet gas replacement section for removing oxygen that has entered the apparatus from the carry-in entrance with the metal parts, and a furnace body for heating the metal parts that have passed through the inlet gas replacement section. A heating / reduction section provided with a heating means, a cooling section for cooling the metal parts that have passed through the heating / reduction section with a cooling gas, and outside air when the cooled metal parts are taken out of the unloader apparatus. Intrude into An outlet section for preventing the temperature, and the inlet gas replacement section is at a temperature lower than a temperature at which the metal parts react with the metal parts and react with the metal parts by the temperature control means to cause oxidation discoloration. In addition, the water generated by the invading oxygen and the hydrogen gas contained in the first and second reducing atmosphere gases is controlled to a temperature higher than the temperature at which the water turns into water vapor, and is near the inlet of the inlet gas replacement section The first movable door for shutting out the outside air is provided so that it can be opened and closed, and the second movable door is provided inside the first movable door with an interval at which metal parts can be stopped. The second movable door closes the transfer passage leaving a gap of a predetermined cross-sectional area upward, and the water vapor is passed between the first door and the second door and the reducing atmosphere gas. In addition, an exhaust port is provided for discharging to the outside of the device. Gas atmosphere heat treatment apparatus, wherein a means for spraying an inert gas curtain to the metal component provided on the inside of the door.

 [0012] (2) The gas atmosphere heat treatment apparatus according to (1), wherein means for spraying a flame on a metal part in a curtain shape is provided outside the first movable door.

[0013] (3) The heating reduction section is provided with means for supplying a first reducing atmosphere gas to the transfer passage, and the furnace body of the heating reduction section is provided with the heating means and the drive roller. A casing that covers the gap between the mounting locations is airtightly provided outside the furnace body, and the internal pressure of the casing is higher than that outside the device and inside the transfer passage to prevent outside air from entering the furnace body and to cool the inside of the casing. Therefore, means for supplying the second atmospheric gas into the casing is provided, and the second atmospheric gas is supplied into the furnace body through the gap, and the first reducing atmosphere supplied into the furnace body is provided. Means for controlling the mixing ratio of the gas and the second atmospheric gas to a desired range are provided, and a pipe body through which the cooling water passes and a means for detecting the temperature in the casing are provided in the casing to detect the temperature. The gas atmosphere heat treatment apparatus as set forth in (1), wherein a means for controlling the flow rate of the cooling water is provided so as to receive data from the means and control the inside of the casing to a predetermined temperature or lower.

[0014] (4) The means for supplying the first reducing atmosphere gas includes a nozzle oriented toward the upstream side of the transfer passage and means for supplying hydrogen gas under pressure to the nozzle. The gas atmosphere according to (3), wherein the means for supplying the second atmospheric gas into the casing includes a nozzle provided in a lower portion of the casing, and means for supplying nitrogen gas under pressure to the nozzle. Heat treatment equipment.

(5) A nozzle that passes through a gap between the heating unit and the driving roller and that discharges hydrogen gas flowing into the casing inside the casing to the outside of the casing is provided in an upper portion of the casing. The gas atmosphere heat treatment apparatus according to (3), wherein a combustion means for burning the hydrogen gas is provided at an outer end portion.

[0016] (6) In the exit section, a third movable door and a fourth movable door are provided so as to be openable and closable at intervals where the metal parts can be stopped in the vicinity of the carry-out port. The compartment formed by the movable door is provided with an exhaust port that discharges the outside air that has flowed into the chamber,

 The gas atmosphere heat treatment apparatus according to (1), wherein a means for spraying an inert gas on a metal part in a curtain shape is provided inside the fourth movable door.

 [0017] (7) The gas atmosphere heat treatment apparatus according to (6), wherein means for spraying a flame on the metal part in a curtain shape is provided outside the fourth movable door.

[0018] (8) The exhaust port of the inlet gas replacement section and the outlet section is provided with combustion means for burning hydrogen gas contained in the exhausted gas. gas Atmospheric heat treatment equipment.

 (9) A metal part transfer passage is continuously formed from the carry-in port to the carry-out port, and the carry-in port and the carry-out port are formed to be openable and closable in order to suppress the intrusion of outside air into the transfer passage. A reducing atmosphere gas containing hydrogen gas is supplied so that the internal pressure is higher than the outside of the apparatus, a heating means is provided in a predetermined area of the transfer passage, and a gas atmosphere with an exhaust port near the carry-in entrance In this method, heat treatment is performed while the parts are transferred in the transfer passage, and when the metal inlet is opened and the metal parts are transferred into the transfer passage, the metal parts are treated in order to suppress oxygen from entering the transfer passage. Included in the reducing atmosphere gas is a process of loading metal parts that closes the inlet after metal parts are carried into the transfer passage while spraying inert gas in the form of a curtain, and oxygen that has entered the transfer passage. With hydrogen gas By passing the metal parts through the transfer passage set in the first temperature range that is higher than the temperature at which the generated water turns into water vapor and lower than the temperature at which the invading oxygen and metal parts react and oxidize and discolor. The inlet gas replacement process and the inlet gas replacement process are completed, in which the oxygen that has entered the carry-in loca device with the metal parts is converted into water vapor and the water vapor is discharged from the exhaust port near the carry-in port together with the reducing atmosphere gas. The metal parts that have been heated and reduced are transferred to a predetermined area where the heating means are provided, and the metal parts are heat-treated in a second temperature range higher than the first temperature range. The parts are further transferred and cooled by blowing cooling gas on the metal parts while passing through the transfer path set in the third temperature range lower than the second temperature range, and the water is sprayed. Oxidative discoloration Without cooling, the cooling process to cool to the temperature, and the metal parts that have been cooled are transferred, and the metal parts are transported out of the apparatus from the outlet while preventing the outside air from entering the apparatus. A gas atmosphere heat treatment method for metal parts, which is characterized.

 [0020] (10) The gas atmosphere heat treatment method for metal parts according to (9), wherein the reducing atmosphere gas is a mixture of hydrogen gas and nitrogen gas in a ratio of approximately 4 to 85:96 to 15 .

[0021] (11) In the metal part carrying-in process, after the flame is sprayed on the metal part in a curtain shape, the metal part is carried into the transfer passage while the inert gas is sprayed on the metal part in a curtain shape. The method for heat treating a metal part in a gas atmosphere as described in (9) above. The invention's effect

 [0022] In the gas atmosphere heat treatment apparatus according to (1), the first movable door for blocking outside air is provided near the carry-in entrance of the inlet gas replacement section, and the inertness is provided inside the first movable door. Since means for spraying gas in the form of a curtain is provided, oxygen contained in the outside air entering the carry-in locus transfer path can be suppressed.

 In addition, in the inlet gas replacement section, the internal pressure of the transfer passage is higher than the outside of the apparatus due to the reducing atmosphere gas, and is below the temperature at which oxygen and metal parts react and oxidize, and above the temperature at which water turns into water vapor. Since it is controlled, the oxygen contained in the outside air that has entered the inlet gas replacement section reacts with the hydrogen contained in the reducing atmosphere gas to become water, which becomes water vapor, and this water vapor becomes the reducing atmosphere gas. At the same time, it passes through the gap above the second movable door, and the exhaust port force is also discharged out of the apparatus.

 Therefore, in the gas atmosphere heat treatment apparatus described in (1) above, oxygen and water are completely eliminated in the inlet gas replacement section, or oxygen and moisture flowing into the heating and reduction section are suppressed to a very small amount. In addition, the oxidation of metal parts in the gas atmosphere heat treatment equipment is minimized, and the heat treatment time can be significantly shortened compared to conventional roller hearth type continuous furnaces.

 [0023] In the gas atmosphere heat treatment apparatus described in (2) above, when the first upper and lower opening / closing shutter is opened and the metal part is carried into the transfer passage, the nozzle force flame is jetted out in a curtain shape so that all of the transfer passage is formed. By forming a frame curtain that covers the cross section, and burning hydrogen contained in the reducing atmosphere gas, oxygen around the metal parts reacts with hydrogen to suppress oxygen entering the furnace.

 [0024] In the gas atmosphere heat treatment apparatus according to (3), a sub chamber is provided to cover the gap between the furnace wall and the heating means and the drive roller, and the second atmosphere gas is added to the sub chamber. By supplying the pressure, it is possible to prevent outside air from entering the furnace body through the sub chamber, and to effectively create an oxygen-free atmosphere in the furnace body.

The second atmospheric gas cools the sub-chamber and prevents thermal deterioration of the electrical wiring etc. in the sub-chamber. At the same time, the second atmospheric gas is introduced into the furnace body through the gap between the furnace walls and It is mixed in a desired ratio in the furnace. Keep this desired mixing ratio Since the flow rate of the second atmospheric gas is controlled, it is difficult to sufficiently cool the sub chamber with only the second atmospheric gas. However, by providing a pipe body through which the cooling water passes in the sub chamber. It becomes possible to control the sub-chamber to a desired temperature or lower. Since the pipe body through which the cooling water passes cools the sub chamber together with the second atmospheric gas, the pipe body through which the cooling water passes can have a relatively simple configuration.

 [0025] In the gas atmosphere heat treatment apparatus described in (4) above, by using nitrogen gas as the second atmosphere gas, it is possible to prevent both outside air intrusion and cooling in the sub chamber, and furthermore, in the furnace body. Then, a reducing atmosphere is formed by mixing with hydrogen gas, which is the first atmosphere gas.

 [0026] In the gas atmosphere heat treatment apparatus according to (5), since the nozzle is provided in the upper part of the casing and the combustion means for burning hydrogen gas is provided at the outer end of the nozzle, the furnace internal force also penetrates into the casing. The discharged hydrogen gas can be discharged and burned.

 That is, the sub-chamber covered with the casing is pressurized and supplied with the second reducing atmosphere gas, and the internal pressure of the sub-chamber is set higher than that in the furnace, and the second reducing atmosphere gas is heated and driven. It passes through the gap between the roller installation points and flows into the furnace from the sub chamber. Thus, even when the internal pressure of the sub chamber is set higher than the internal pressure of the furnace body, when hydrogen is contained in the reducing atmosphere gas in the furnace body, due to the high permeability that is a characteristic of hydrogen gas, Hydrogen gas permeates into the sub chamber from the furnace, and this hydrogen gas stays in the upper space of the sub chamber. There is a concern that if this hydrogen gas exceeds the specified volume and oxygen accidentally flows, it will explode.

 However, if a nozzle is provided in the upper part of the sub chamber of the gas atmosphere heat treatment apparatus, it is possible to eliminate the nozzle force of the hydrogen gas remaining in the upper space of the sub chamber, and the hydrogen gas is placed outside the nozzle. Combustion treatment with this will prevent the explosion of hydrogen gas in the sub chamber.

[0027] In the gas atmosphere heat treatment apparatus according to (6), the third movable door and the fourth movable door are provided in the outlet section so as to be openable and closable, and the inert gas is sprayed onto the metal part in a curtain shape. Since the means is provided on the inner side of the fourth movable door, oxygen contained in the outside air entering the carry-out locuser transfer passage can be suppressed. In addition, since the compartment formed between the third movable door and the fourth movable door provided in the exit section is provided with an exhaust port, when the third movable door is opened, The reducing atmosphere gas flows into the compartment, and the outside air that has entered the compartment can be discharged out of the exhaust outlet.

 [0028] In the gas atmosphere heat treatment apparatus described in (7) above, when the metal part is carried out of the transfer passage, a flame is blown out in a curtain shape to form a frame curtain covering the entire cross section of the transfer passage. By burning hydrogen contained in the atmospheric gas, oxygen that is about to enter the apparatus reacts with hydrogen, and oxygen can be prevented from entering the apparatus.

 [0029] In the gas atmosphere heat treatment apparatus according to (8), even when hydrogen gas is contained in the gas discharged from the exhaust port in the inlet gas replacement section and the outlet section, this hydrogen gas is removed from the exhaust port. Combustion treatment can be performed on the outside.

 [0030] In the gas atmosphere heat treatment method according to (9), the metal part is carried into the transfer passage from the carry-in locuser while spraying an inert gas on the metal part in the form of a curtain in the carry-in process. The amount of oxygen entering from the mouth can be suppressed to an extremely small amount. Also, in the inlet gas replacement process, the internal pressure of the transfer passage is made higher than the outside of the apparatus by the reducing atmosphere gas, and the temperature inside the transfer passage is below the temperature at which oxygen and metal parts react and oxidize and discolor, and above the temperature at which water changes to water vapor. Therefore, the oxygen contained in the outside air that has entered from the carry-in inlet reacts with the hydrogen contained in the reducing atmosphere gas to become water, which becomes water vapor, and this water vapor is combined with the reducing atmosphere gas. Exhaust port power Can be discharged out of the device. Therefore, the power to completely eliminate oxygen and water in the inlet gas replacement process, or the amount of oxygen and water flowing into the calothermal reduction process is extremely low! As a result, the heat treatment time in the heat reduction process can be significantly reduced.

In the cooling step of the gas atmosphere heat treatment method, the heated metal part is first cooled with a cooling gas in a reducing atmosphere gas, and even if water is applied to the metal part, the temperature does not cause oxidation discoloration. For example, since it is cooled to about 270 ° C. or less, it becomes possible to cool the metal parts with water after the cooling step using the cooling gas. For example, if a metal part is cooled with water following the cooling process, the metal part can be cooled to about 100 ° C. or less without causing any problems such as oxidative discoloration or crystal structure. And metal parts cooled to below 100 ° C are much easier to handle and can be handled by workers.

 [0031] In the gas atmosphere heat treatment method described in (10) above, since the mixing ratio of hydrogen gas and nitrogen gas is approximately 4 to 85: 96 to 15, a sufficient reducing atmosphere in the furnace is formed. It enables bright annealing of metals.

 [0032] In the gas atmosphere heat treatment method described in (11) above, since the flame is sprayed onto the metal part in a curtain before the inert gas is sprayed onto the metal part in a curtain shape, the transfer passage Since the outside air force can be shut off and oxygen is burned, the prevention of oxygen from entering the transfer path is further promoted.

 Brief Description of Drawings

FIG. 1 is a cross-sectional view when one embodiment of the present invention is cut in a line direction.

 FIG. 2 is an enlarged cross-sectional view of a part of FIG.

 FIG. 3 is an enlarged cross-sectional view of a portion continuing from FIG. 2 in the apparatus of FIG.

 4 is an enlarged cross-sectional view of a portion continuing from FIG. 3 in the apparatus of FIG.

 5 is a cross-sectional view of one sub chamber in FIG.

 FIG. 6 is a cross-sectional view of the other subchamber in FIG.

 Explanation of symbols

[0034] 10 Gas atmosphere heat treatment device

 11 Loading compartment

 12 Inlet gas replacement section

 13 Heating / reduction section

 14 Cooling compartment

 15 Exit compartment

 16 Unloading compartment

 18a, 18b Drive roller

19 Metal parts 20 Electric heater

 21 Furnace

 22, 23 Casing

 24, 25 畐 IJ room

 26 nozzles

 29 First open / close shutter (first movable door)

 30 Nitrogen gas ejection nozzle

 31 Second up / down shutter (second movable door)

 31c Clearance

 32a Exhaust port

 32b burner

 28 nozzles

 40 Finned cooling pipe

 41 nozzles

 49 Third open / close shutter (third movable door)

 50a Exhaust port

 50b burner

 51 Nitrogen gas injection nozzle

 52 Fourth open / close shutter (fourth movable door)

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

 In the following embodiments, examples of the gas atmosphere heat treatment apparatus and method include an apparatus and method for bright annealing of metal parts, but the gas atmosphere heat treatment of the present invention is not limited to this.

In the embodiment of FIG. 1, the gas atmosphere heat treatment apparatus 10 is provided with an inlet gas replacement section 12, a heating / reduction section 13, a cooling section 14 and an outlet section 15 in succession, and this gas atmosphere heat treatment apparatus 10 Before and after 10, a loading section 11 and a loading section 16 are provided as ancillary facilities. Figure 2 is an enlarged view of the loading compartment 11 and the inlet gas replacement compartment 12. FIG. 3 is an enlarged view of the heating / reducing section 13 and the cooling section 14, and FIG. 4 is an enlarged view of the outlet section 15 and the unloading section 16.

 A plurality of drive rollers 18a and 18b are continuously arranged in the entire section from the carry-in section 11 to the carry-out section 16, and these drive rollers 18a and 18b are driven to rotate, and the metal that is the object to be processed The component 19 is put in a container such as a tray and placed on the driving rollers 18a and 18b, and is conveyed from the loading section 11 to the unloading section 16 in the right direction in FIG. In the heating / reduction section 13, a ceramic roller having high heat resistance is adopted as the drive roller 18b, and a plurality of electric heaters 20 for directly heating the metal parts 19 are provided in the furnace body 21, and the electric heater 20 and the drive roller 18b are attached to the furnace body 21 by covering the outer power of the furnace body with the casings 22 and 23, respectively. In the heating / reduction section 13, the first reducing atmosphere gas (hydrogen gas) is ejected upstream from the nozzle 26 provided at the downstream end of the heating / reducing section 13, and the second reducing atmosphere. Gas (nitrogen gas) is introduced through the sub chambers 24 and 25, and these hydrogen gas and nitrogen gas are mixed in a desired ratio to form a reducing atmosphere. This reducing atmosphere gas is pressurized so that the internal pressure of the gas atmosphere heat treatment apparatus 10 is higher than the outside! RU

 In the gas atmosphere heat treatment apparatus 10, an inert gas can be used as the first and second reducing atmosphere gases. For example, when bright annealing is performed on a metal part, the first and second reducing atmosphere gases are used. As described above, hydrogen gas and nitrogen gas are used as the reducing atmosphere gas.

 [0036] Next, each section will be described in more detail.

 In the loading section 11 of FIG. 2, the metal part 19 placed in a container such as a tray is placed on the conveyor device 27 to stand by, and the metal part 19 to be processed passes through the swing shirt 30. It is controlled to be sent to the inlet gas replacement section 12 at the time.

[0037] The inlet gas replacement section 12 prevents outside air from entering the furnace, and replaces it with reducing atmosphere gas so that air and moisture in the metal part 19 are not brought into the heating / reducing section 13. The temperature control means described later is controlled to a temperature not lower than the temperature at which water turns into water vapor and not higher than a temperature at which oxygen and metal parts react to cause acid discoloration. This temperature control range can be, for example, about 100 to 300 ° C. In the inlet gas replacement section 12, a plurality of driving rollers 18a are arranged in parallel in the passage 12a. The nozzle 28 of the frame curtain forming device, the first up / down shutter 29, the nitrogen gas ejection nozzle 30, the second up / down shutter 31, an exhaust port 32a and a swing shutter 33 are arranged.

 Here, the frame curtain forming device is a force that can be selectively provided rather than the essential configuration. In this frame curtain forming device, the nozzle 28 is provided outside the upper and lower open / close shirt 29, When the first top / bottom shutter 29 is opened and the metal part 19 is carried into the transfer passage 12a, a flame is blown out from the nozzle 28 in a tense manner to form a frame curtain covering the entire cross section of the transfer passage 12a. By burning the hydrogen contained in the reducing atmosphere gas through the flame curtain, the oxygen that tries to enter the device together with the metal parts 19 reacts with the hydrogen to suppress the intrusion of oxygen into the device. It is out.

 Next, the first vertical opening / closing shutter 29 has a telescopic cylinder 29a provided below and a shutter 29b moved up and down by the telescopic cylinder 29a, and lifts the shutter 29b so that there is no gap in the transfer passage 12a. It closes and shuts off the outside air force in the transfer passage 12a.

 The nitrogen gas ejection nozzle 30 is provided upstream of the first upper / lower opening / closing shutter 29 in order to eject nitrogen gas as an inert gas. Here, the nitrogen gas is directed toward the metal part 19 in a single force. A curtain of nitrogen gas that blows out and covers the entire cross section of the transfer passage 12a is formed, thereby obtaining the effect of suppressing the outside air intrusion when the shutter 29b is opened. The nitrogen gas ejection nozzle 30 is continuously operated when the shutter 29b is open, and suppresses the amount of oxygen contained in the outside air entering the carry-in locus transfer path. For example, when the amount of oxygen is suppressed to a volume ratio of 4% or less with respect to the reducing atmosphere gas in the transfer passage by the nitrogen gas blown out from the nitrogen gas injection nozzle 30 in the curtain shape, Explosion when reacting with hydrogen gas can be prevented.

Next, the second vertical opening / closing shutter 31 has a telescopic cylinder 31a provided below, and a shutter 31b moved up and down by the telescopic cylinder 31a. When lifted by the telescopic cylinder 31a, the gap 31c having a predetermined cross-sectional area is closed above the transfer passage 12a. The shutter 31b is provided on the downstream side of the first upper / lower opening / closing shutter 29 with an interval at which the metal part 19 placed in a container such as a tray can be stopped.

 Between the first up / down shutter 29 and the second up / down shutter 31, an exhaust port 32a that is always open is provided at the ceiling of the transfer path 12a, and a burner 32b is attached to the outside of the exhaust port 32a. It is done.

 The swing shutter 33 is pivotably suspended from the ceiling of the transfer passage 12a, and the lower end extends to the drive roller 18a. When the metal part 19 placed in the tray is transferred, the swing shutter 33 is pushed and opened by the tray. Is done.

 In the inlet gas replacement section 12, an explosion-proof device 35 is provided at a position relatively close to the heating / reducing section 13. The explosion-proof device 35 has a lid 35b airtightly provided at the opening of a pipe body 35a that allows the transfer passage 12a to communicate with the outside, and the lid 35b is automatically operated when an internal pressure exceeding a predetermined value is generated in the transfer passage 12a. It is provided with such a strength that it can be removed. That is, when a relatively large amount of oxygen enters the transfer passage 12a, the oxygen concentration becomes high, reacts with hydrogen gas to cause an explosion, and a relatively large internal pressure is generated in the transfer passage 12a, the lid 35b Is to release the internal pressure. An explosion-proof device 35 having the same configuration is also provided in the outlet section 15 as shown in FIG.

 The heating / reduction section 13 is a section where the metal part 19 is heated and passed in a reducing atmosphere, and for example, heat treatment such as bright annealing is performed on the metal part 19. Each of the floors is made of a heat-resistant material, and an oxygen concentration measuring tube 36 is inserted through an inlet 21b formed narrower than the inside of the furnace body 21a. The oxygen concentration is monitored. When this oxygen concentration is high, the supply of the first atmospheric gas (hydrogen gas) is stopped.

In the heating / reduction section 13, a ceramic roller having high heat resistance is employed as the driving roller 18b. The electric heater 20 is disposed above and below the plurality of driving rollers 18b in the furnace body 21, and both ends of the electric heater 20 and the driving roller 18b are inserted through the side wall 21c and attached to the mounting portion. A gap is created. This mounting location is shown in Figs. 5 and 6. As shown in Fig. 5, the outer force of the side wall 21c is also covered with the casings 22 and 23, and the sub chambers 24 and 25 are formed.

 [0040] In the plurality of electric heaters 20, the radiation temperature gradually increases from the upstream side toward the downstream side in the furnace body, reaches the maximum temperature at a predetermined position in the latter half, and reaches the downstream furnace outlet from this position. The temperature is set to be different for each of the multiple units so that the radiation temperature gradually decreases toward the target, and a temperature sensor (not shown) is placed in the tray that transports the metal parts 19 when the device is initially set. The temperature is measured and initialized by the measured data. A temperature sensor (not shown) is provided on the ceiling inside the furnace body 21a, and the temperature of the reducing atmosphere gas in the heating / reducing section 13 is monitored.

 The reducing atmosphere gas heated by the electric heater 20 in the heating / reducing section 13 flows into the inlet gas replacement section 12, and is equal to the temperature of a predetermined number of electric heaters 20 provided upstream in the furnace body. At the same time, the temperature range of the inlet gas replacement section 12 is substantially set. Therefore, the temperature control of the reducing atmosphere gas in the inlet gas replacement section 12 is performed by receiving data from a temperature sensor (not shown) provided in the inlet gas replacement section 12 and the temperature sensor, and in the heating / reduction section 13. This is performed by a device (not shown) for controlling the temperature of a predetermined number of electric heaters 20 on the upstream side.

 In the sub chamber 24, the electric wiring 20 a is connected to one end of the electric heater 20, a driving force transmission device 37 including a rotating shaft and gears is attached to one end of the driving roller 18 b, and the motor 38 is disposed outside the sub chamber 24. Is installed. A rotational force is transmitted from the motor 38 to the driving force transmission device 37 via the chain 39a, the gear 39b, and the rotating shaft 39c, and the driving roller 18b is driven to rotate. The rotating shaft 39c is provided at two locations so as to penetrate inside and outside of the casing 22, and the penetration location is hermetically closed by a sealed bearing.

[0041] In the sub chambers 24 and 25, a finned cooling pipe 40 is extended, and a nozzle 41 for supplying a second atmospheric gas (nitrogen gas) is connected to the lower side of the casings 22 and 23. The The nozzle 41 is connected to a pipe (not shown) extending from a device (not shown) for supplying a second atmospheric gas under pressure, and a supply amount of the second atmospheric gas is connected to the pipe leading to the nozzle 41. A flow meter (not shown) is provided to measure the flow rate. A nozzle 42 for discharging hydrogen gas is provided above the casings 22 and 23, and an adjustment valve 43a is provided in the middle of the nozzle 42. In addition, a burner 43 b is provided at the discharge port of the nozzle 42. The amount of hydrogen gas discharged from the nozzle 42 is adjusted by the adjusting valve 43a and burned by the burner 43b.

 The sub-chambers 24 and 25 are further provided with a temperature sensor (not shown), and the amount of cooling water sent to the finned cooling pipe 40 by a control device (not shown) that receives data from the temperature sensor. By adjusting the (flow rate), the sub-chambers 24 and 25 are controlled to have a temperature of 120 ° C or lower.

 In FIGS. 5 and 6, only one finned cooling pipe 40 is illustrated. The number of the cooling pipes 40 is set as necessary.

 [0042] By increasing the internal pressure by pressurizing and supplying nitrogen gas into the sub chambers 24 and 25 via the pipe 41, outside air can be prevented from entering the furnace body 21 via the sub chambers 24 and 25. The

 The nitrogen gas cools the sub chambers 24 and 25 to prevent thermal deterioration of the electric wiring 20a and the driving force transmission device 37. On the other hand, the nitrogen gas is introduced into the furnace body 21a through the gap between the driving roller 18b and the electric heater 20 and the side wall 21c, and the sub-chambers 24 and 25 have the internal force. Since 21a is mixed in a desired ratio, a large amount of nitrogen gas cannot be supplied, and it is difficult to sufficiently cool the sub chambers 24 and 25 only with nitrogen gas. However, since the finned cooling pipes 40 are provided in the sub chambers 24 and 25, the sub chambers 24 and 25 can be controlled to a desired temperature or lower. Since the finned cooling tube 40 cools the sub chambers 24 and 25 together with the nitrogen gas, the finned cooling tube 40 itself can have a relatively simple configuration.

 [0043] The most downstream part of the heating and reducing section 13 is narrowly formed with a cross section smaller than the inside of the furnace body 21a, and a nozzle 26 directed to the upstream side of the transfer passage 21a is provided here. Is connected to a pipe (not shown) extending from a device (not shown) for pressurizing and supplying the first atmospheric gas (hydrogen gas). A first atmospheric gas (hydrogen gas) is ejected from the nozzle 26 in the upstream direction of the heating-reducing section 13. The pipe leading to the nozzle 23 is provided with a flow meter (not shown) for measuring the supply amount of hydrogen gas, and the control device (not shown) receives data from the flow meter, and the control device This controls the amount of hydrogen gas supplied from the nozzle 26.

Hydrogen gas is ejected from the nozzle 26 in the upstream direction of the heating / reducing section 13 and in the upstream direction. An air flow is created, and this air flow suppresses the flow of heat from the furnace body 21a to the cooling section 14. Further, the hydrogen gas supplied from the nozzle 26 is mixed with nitrogen gas introduced into the furnace body 2 la through the sub chambers 24 and 25 in the furnace body 21a to constitute a reducing atmosphere. The hydrogen gas reacts with this small amount of oxygen to form water (water vapor) even if oxygen is present in the furnace body 21a, creating an oxygen-free state in the furnace body 21a. Since the optimal mixing ratio of hydrogen gas and nitrogen gas in 21a varies depending on the workpiece, the volume ratio of hydrogen gas: nitrogen gas is controlled by a flow meter and a control device (not shown), respectively.

 For example, when the bright annealing treatment is performed by heating the metal part 19 in the furnace body 21a, the mixing ratio of nitrogen gas and hydrogen gas is controlled so that the hydrogen gas has a volume ratio of 60% or more. More preferably, it is necessary to control the volume ratio of hydrogen gas: nitrogen gas to be approximately 4 to 85:96 to 15. Such a volume ratio is controlled by a flow meter and a control device (not shown) of nitrogen gas and hydrogen gas.

 [0044] Next, in the cooling section 14, the apparatus is configured so that the metal component 19 can be rapidly cooled by the cooling gas, for example, to about 270 ° C or less. That is, in the cooling section 14, both side walls constituting the transfer passage 15a are formed by water-cooled walls, and the ceiling and the bottom surface are formed from a water-cooled tank in which water passes, and a plurality of drive rollers 18b are provided in the transfer passage 15a. Two cooling devices 44 are provided in parallel. The cooling device 44 includes a plurality of finned water cooling tubes 45 disposed above the driving roller 18b, a cooling fan 46 disposed above the water cooling tubes 45, and a motor 47 for driving the cooling fan 46. Are provided. The temperature of the cooling compartment 14 is monitored by a temperature sensor (not shown), the amount of cold water supplied to the finned water cooling pipe 45 is monitored by a monitoring system (not shown), and is controlled by a control device (not shown). Be controlled. When the cooling device 44 allows the metal part 19 to pass through the cooling section 14 while blowing the cooling gas, the metal part 19 is cooled to at least about 270 ° C. or less.

 [0045] Once the metal part 19 has passed through the cooling compartment 14, it then reaches the outlet compartment 15 shown in FIG.

The outlet compartment 15 is evacuated into the cooling compartment 14 when the cooled metal part 19 is removed. In this section, a plurality of driving rollers 18a are arranged in parallel in the passage 16a, and the swing shutter 48, the third upper / lower shutter 49, the exhaust port 50a, the burner toward the outlet 50b, a nitrogen gas ejection nozzle 51, a fourth upper / lower opening / closing shirt 52, and a nozzle 53 of a frame curtain forming apparatus are arranged.

 The third and fourth open / close shutters 49 and 52 have telescopic cylinders 49a and 52a provided below, and shutters 49b and 52b moved up and down by the contraction cylinders 49a and 52a. 52a is raised to block the transfer passage 15a without gaps, and the outside of the transfer passage 15a is shut off.

 The third vertical opening / closing shutter 49 and the fourth vertical opening / closing shutter 52 are provided at intervals near which the metal parts can be stopped near the exit, and are formed by the third and fourth vertical opening / closing shutters 49, 52. The outside air flowing into the compartment is discharged from the exhaust port 50a. The exhaust port 50a is always open, and a burner 50b is provided outside the exhaust port 50a. When hydrogen gas is contained in the gas discharged from the exhaust port 50a, the burner 50b burns.

 The nitrogen gas ejection nozzle 51 is provided on the upstream side of the fourth upper and lower opening / closing shutter 52. Here, the nitrogen gas is ejected in a curtain shape toward the metal part 19, and a nitrogen gas curtain covering the entire cross section of the transfer passage 15a is formed. Thus, the effect of suppressing the entry of outside air into the apparatus when the shutter 52b is opened is obtained.

 Here, the frame curtain forming device is a force that can be selectively provided rather than the essential configuration. In this frame curtain forming device, the nozzle 53 is provided outside the fourth upper / lower shutter 52. When the fourth top / bottom open / close shutter 52 is opened and the metal part 19 is carried out from the transfer passage 15a, a flame is blown out from the nozzle 53 in the form of a curtain to form a frame curtain covering the entire cross section of the transfer passage 15a, By burning hydrogen gas with this flame curtain, oxygen that tries to enter the device reacts with hydrogen to prevent oxygen from entering the device.

In FIG. 4, an unloading section 16 is provided following the exit section 15, and in this unloading section 16, the metal part 19 that has undergone the heat treatment process is taken out from the furnace of the exit section 15 and is transported to the next process. Conveyor device 54 is provided! Immediately before this conveyor device 54 Is provided with a hood 55, and a cold water nozzle 56 is attached to the lower side of the hood 55. In the conveyor device 54, a water collection container 57 is provided below the drive roller 18a, and a drain pipe 58 is connected to the water collection container 57.

 The metal part 19 that has exited the outlet section 15 has already been cooled to about 250 to 200 ° C or less, but in this unloading section 16, the metal part 19 is further poured into the metal part 19 by pouring cold water. For example, the component 19 is cooled to about 100 ° C or less. The cold water that has passed through the metal part 19 and the drive roller 18 a is drained from the water collection container 57 through the drain pipe 58.

 The metal part 19 has already been cooled to, for example, about 250 to 200 ° C. or less immediately before the cold water nozzle 56. Therefore, the metal part 19 can be cooled with water. That is, when the metal part 19 has a temperature of about 300 to 270 ° C. or more, there is a possibility of adverse effects such as oxidation discoloration and crystal structure, and cooling with water is not preferable.

 [0047] In the gas atmosphere heat treatment apparatus 10, control by temperature data can be performed by a temperature sensor and a control device provided respectively. Other control can be performed by sequence control, and a plurality of control means and control devices can be configured by one PLC (Programmable Logic Controller). The PLC is a conventional device that uses a computer or a dedicated input device to express the control contents in advance in a program, writes it in memory, and executes the program sequentially to control the sequence. .

 [0048] Next, the gas atmosphere heat treatment method of the present invention will be described.

 C preparation process]

First, the gas atmosphere heat treatment apparatus 10 is operated, and each section is set to a predetermined condition. That is, the first force also closes the fourth up / down shutters 29, 31, 49, 52, operates the electric heater 20 in the heating / reduction section 13, and the inside of the transfer passage in the inlet gas replacement section 12 is 100 to 100, for example. Increase the temperature so that the reducing atmosphere gas at a predetermined position in the latter half of the furnace body in the heating / reducing section 13 is about 1000 ° C: L100 ° C. Further, the first reducing atmosphere gas (hydrogen gas) is pressurized and supplied from the nozzle 26 provided in the heating / reduction section 13 toward the upstream of the transfer passage, and the second reducing atmosphere gas (nitrogen gas) is sub-charged. Through chambers 24, 25 It introduce | transduces in the furnace body 21, and it controls so that the volume ratio of hydrogen gas: nitrogen gas in the furnace body 21 may be about 4 to 85: 96-15. At this time, the internal pressure of the inside of the transfer passage of the gas atmosphere heat treatment apparatus 10 is higher than that of the outside of the apparatus by the first and second reducing atmosphere gases.

[0049] [Metal parts loading process]

 When the gas atmosphere heat treatment apparatus 10 is set to the predetermined conditions by the preparation process, the first upper and lower opening / closing shirt 29 is opened while nitrogen gas is blown out from the nitrogen gas blowing nozzle 30 in the form of a curtain, and the metal part which is the object to be treated 19 is carried into the transfer passage. At this time, the second three upper and lower shutters 31, 49, 52 are closed. After the metal part 19 is carried into the transfer passage, the first up / down shutter 29 is closed and the nitrogen gas ejection nozzle 30 is stopped.

 Thus, by spraying the curtain-like nitrogen gas on the metal part 19 at the time of carrying in, the outside air force is shut off in the transfer passage, and oxygen around the metal part can be blown off. By carrying the metal part 19 into the transfer passage through the carry-in process as described above, oxygen entering the carry-in loca transfer passage can be suppressed. For example, it is desirable to suppress the oxygen entering the transfer passage to 4% or less by volume ratio with respect to the reducing atmosphere gas.

 Although not indispensable in the metal part carrying-in process, the frame curtain forming apparatus can be selectively operated as appropriate when the first up / down opening / closing shutter 29 is opened / closed. For example, if a flame is blown out from the nozzle 28 in the form of a curtain by a frame curtain forming device, the hydrogen gas contained in the reducing atmosphere gas is burned by the flame, and oxygen around the metal parts or oxygen that tries to enter the transfer passage Reacts with hydrogen to suppress oxygen entering the transfer passage.

[0050] [Inlet gas replacement process]

Next, with the first, third and fourth three upper / lower shutters 29, 49, 52 closed, the second upper / lower shutter 31 is opened, and after passing the metal part 19, the second The upper / lower shutter 31 is closed, and the metal part 19 is allowed to pass through the transfer passage of the inlet gas replacement section 12 set to, for example, about 100 to 300 ° C. In the inlet gas replacement section 12, the return atmosphere gas flows toward the exhaust outlet 32a upstream of the downstream force in the transfer passage. Reducing atmosphere in which the hydrogen gas contained in the original atmosphere gas turns into water by reacting with the metal part 19 and the oxygen that has entered the equipment, and this is turned into water, which turns into water vapor. Along with the gas, the gas passes through the gap 31 of the second upper / lower opening / closing shutter 31b and is discharged out of the apparatus through the exhaust port 32a. When hydrogen gas is contained in the exhaust gas, it is burned by a burner 32b provided outside the exhaust port 32a.

 In the inlet gas replacement step, oxygen that enters the transfer passage is suppressed, and oxygen that has entered is eliminated, so that the oxidation of the metal part 19 in the transfer passage is minimized.

[0051] [Heat reduction process]

 The metal part 19 that has been subjected to the inlet gas replacement process is further transferred by a driving roller, and passes through a heat reduction section 13 provided with an electric heater 20. The electric heater 20 in the heating and reducing section 13 gradually increases in temperature from the upstream side toward a predetermined position in the latter half of the furnace body 21, reaches a maximum temperature at a predetermined position in the latter half, and reaches downstream from here. The temperature is set to be different for each of the multiple furnaces so that the radiation temperature decreases toward the outlet of the furnace body 21. Therefore, while the metal parts are transferred from the upstream side to the predetermined position in the latter half of the furnace body 21 in the heat reduction section 13, the temperature of the metal parts gradually increases by about 300 ° C, and the heat treatment temperature. The temperature reaches approximately 1000 to 1080 ° C, and further, the temperature falls to approximately 700 to 900 ° C while being transferred to the outlet of the furnace body 21 on the downstream side.

 In the heat reduction process, the metal part 19 in which the acid and soot is minimized in the inlet gas replacement process is heat-treated, so that the heat treatment time is shortened compared to the conventional heat treatment method.

 [0052] [Cooling process]

 The metal parts that have been subjected to the heat reduction process are further transferred, and the metal that has been heated while passing through the transfer passage of the cooling section 14 that is set to about 50 ° C. Cool the parts with cooling gas and cool them down to about 270 ° C, which is a temperature range that does not cause oxidative discoloration even when water is sprayed.

[0053] [Unloading process]

In the unloading process, the metal parts for which the cooling process has been completed are transferred, and the first, second and fourth 3 With the three upper / lower shutters 29, 31, 52 closed, the third upper / lower shutter 49 was opened, and the metal part was passed through the compartment formed by the third and fourth upper / lower shutters 49, 52. Later, the third upper / lower shutter 49 is closed. At this time, because the internal pressure of the transfer path is higher than the outside of the apparatus due to the reducing atmosphere gas, when the third top / bottom opening / closing shutter 49 is opened, the reducing atmosphere gas is discharged to the outside through the exhaust port 50a. It is done. When hydrogen gas is contained in the exhaust gas, it is burned by a burner 50b provided outside the exhaust port 50a.

 Next, while the nitrogen gas is ejected from the nitrogen gas ejection nozzle 51 in the form of a curtain, the fourth upper / lower opening / closing shutter 52 is opened to carry the metal part out of the apparatus. At this time, the first to third upper and lower shutters 29, 31, 49 are closed. After the metal parts are carried out of the outlet section 15, the fourth top / bottom open / close shutter 52 is closed to stop the nitrogen gas.

 As described above, by carrying the metal part outside the outlet section 15, the heat treatment of the metal part in the reducing atmosphere gas is completed.

 Although not essential in the metal part unloading process, the frame curtain forming apparatus can be selectively operated as needed when the fourth upper / lower opening / closing shutter 52 is opened / closed. For example, if a flame is blown out from the nozzle 53 in the form of a curtain using a frame curtain forming device, hydrogen gas contained in the reducing atmosphere gas burns, oxygen and hydrogen in the outside air react, and oxygen enters the transfer passage. Prevention is further promoted.

Claims

The scope of the claims  [1] Carry-in locus A plurality of compartments are provided up to the carry-out exit, and drive rollers are arranged in parallel in these compartments to form a metal part transfer path, so that the internal pressure is higher in the transfer path than outside the device. The first and second reducing atmosphere gases are supplied to the first and second reducing atmosphere gases, and the first and second reducing atmosphere gases contain hydrogen gas.  Carrying inlet force with metal parts An inlet gas replacement section for removing oxygen that has entered the apparatus, and a furnace body for heating the metal parts that have passed through the inlet gas replacement section, and heating means in the furnace body , A cooling section that cools metal parts that have passed through the heating / reduction section with a cooling gas, and outside air enters the apparatus when the cooled metal parts are taken out of the apparatus from the carry-out port. The inlet gas replacement section is a temperature at which the metal part reacts with the oxygen and the metal part reacting with the metal part by the temperature control means, and the temperature is changed by oxidation. The water generated by the invading oxygen and the hydrogen gas contained in the first and second reducing atmosphere gases is controlled to be higher than the temperature at which the water turns into water vapor.  In the vicinity of the inlet of the inlet gas replacement section, a first movable door for blocking outside air is provided so as to be openable and closable. Two movable doors are provided, and the second movable door closes the transfer passage leaving a gap of a predetermined cross-sectional area upward, and the water vapor is interposed between the first door and the second door. Is provided with an exhaust port that discharges the gas along with the reducing atmosphere gas,  A gas atmosphere heat treatment apparatus, characterized in that means for spraying an inert gas on a metal part in a curtain shape is provided inside the first movable door.  [2] The gas atmosphere heat treatment apparatus according to [1], wherein means for spraying a flame on the metal part in a curtain shape is provided outside the first movable door. [3] The heating reduction section is provided with means for supplying the first reducing atmosphere gas to the transfer passage, and a gap between the heating means and the drive roller is provided in the furnace body of the heating reduction section. A covering casing is provided in an airtight manner outside the furnace body, and the casing internal pressure is higher than that outside the apparatus and inside the transfer passage to prevent the outside air from entering the furnace body. Means for supplying a second atmosphere gas into the casing for cooling the inside of the sink is provided, and the second atmosphere gas is supplied into the furnace body through the gap, and is supplied into the furnace body. Means for controlling the mixing ratio of the first reducing atmosphere gas and the second atmosphere gas to a desired range,  The casing is provided with a pipe body through which cooling water passes and a means for detecting the temperature in the casing, and is cooled so as to receive data from the temperature detecting means and control the inside of the casing to a predetermined temperature or lower. The gas atmosphere heat treatment apparatus according to claim 1, further comprising means for controlling a flow rate of water.  [4] The means for supplying the first reducing atmosphere gas includes a nozzle directed toward the upstream of the transfer passage, and means for pressurizing and supplying hydrogen gas to the nozzle. 4. The gas atmosphere heat treatment apparatus according to claim 3, wherein the means for supplying the second atmospheric gas into the casing includes a nozzle provided in a lower portion of the casing and a means for supplying nitrogen gas under pressure to the nozzle. .  [5] A nozzle is provided in an upper part of the casing that passes through a gap between the heating means and the driving roller and that flows into the casing from the furnace body and out of the casing. The gas atmosphere heat treatment apparatus according to claim 3, wherein a combustion means for combusting the hydrogen gas is provided in the section.  [6] The exit section is provided with a third movable door and a fourth movable door that can be opened and closed at intervals near which the metal parts can be stopped in the vicinity of the carry-out exit. The compartment formed by the door is provided with an exhaust port that discharges the outside air that flows into the chamber to the outside of the device.  2. The gas atmosphere heat treatment apparatus according to claim 1, wherein means for spraying an inert gas on the metal part in a curtain shape is provided inside the fourth movable door. 7. The gas atmosphere heat treatment apparatus according to claim 6, wherein means for spraying a flame on the metal part in the form of a curtain is provided outside the fourth movable door. 8. The gas atmosphere heat treatment apparatus according to claim 6, wherein a combustion means for burning hydrogen gas contained in the discharged gas is provided at an exhaust port of the inlet gas replacement section and the outlet section. [9] A metal part transfer passage is continuously formed from the carry-in port to the carry-out port, and the carry-in port and carry-out port are formed to be openable and closable in order to suppress the intrusion of outside air into the transfer passage. In addition, a reducing atmosphere gas containing hydrogen gas is supplied so that the internal pressure becomes high, a heating means is provided in a predetermined area of the transfer path, and a metal part is formed by a gas atmosphere heat treatment apparatus having an exhaust port near the carry-in port The heat treatment is carried out while transporting in the transfer passage, and when the carry-in opening is opened and the metal part is carried into the transfer passage, the metal parts are treated in order to suppress oxygen entering from the carry-in entrance into the transfer passage. A metal part loading process in which the inert gas is sprayed in the form of a curtain and the metal part is carried into the transfer passage and then the inlet is closed;  Above the temperature at which the water generated by the oxygen that has entered the transfer passage and the hydrogen gas contained in the reducing atmosphere gas turns into water vapor, and below the temperature at which the invaded oxygen reacts with the metal parts and undergoes oxidation discoloration. By passing metal parts through a transfer passage set to a certain first temperature range, oxygen that has entered the carry-in loca device with the metal parts is converted into water vapor, and the water vapor is carried with the reducing atmosphere gas. An inlet gas replacement process for discharging from an exhaust port near the mouth;  A heat reduction process in which the metal part that has undergone the inlet gas replacement step is transferred to a predetermined area provided with a heating means, and the metal part is heat-treated in a second temperature range higher than the first temperature range;  The metal parts that have undergone the heat reduction process are further transferred and cooled by blowing a cooling gas onto the metal parts while passing through the transfer path set in the third temperature range lower than the second temperature range. In addition, a cooling process that cools to a temperature without causing acid discoloration even when water is applied, and  A metal part gas atmosphere heat treatment method characterized in that the metal part is transported out of the equipment while the cooling process is completed and the outside air is prevented from entering the equipment while the equipment is carried out. .  10. The gas atmosphere heat treatment method for metal parts according to claim 9, wherein the reducing atmosphere gas is a mixture of hydrogen gas and nitrogen gas in a ratio of approximately 4 to 85:96 to 15. [11] In the process of carrying in the metal part, flame was sprayed on the metal part in a curtain shape. 10. The gas atmosphere heat treatment method for a metal part according to claim 9, wherein the metal part is subsequently carried into the transfer passage while spraying an inert gas on the metal part in a curtain shape.