JPH055171A - Heat treatment apparatus - Google Patents

Abstract

PURPOSE:To efficiently execute one series work, in which a material to be treated is cooled after carburizing and successively, this is quenched after carbonitriding, without accompanying with any energy loss. CONSTITUTION:This heat treatment apparatus provides a temp. raising chamber 18, carburizing chamber 20, cooling chamber 22, temp. re-raising chamber and nitriding chamber dividedly formed by partitioning one series continuous furnace 10 with open/close doors 14 and a shifting means for shifting the material to be treated along the above one series of continuous furnace 10 in order. in the cooling chamber 22, gas cooling means for cooling by blowing gas for cooling to the material to be treated, is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus, and more particularly to a heat treatment apparatus having a heat treatment zone for heat treating an object to be processed in an atmosphere gas.

[0002]

2. Description of the Related Art As a heat treatment apparatus as described above, as shown in Japanese Utility Model Laid-Open No. 62-118167, an object to be treated such as a steel member is held at a high temperature in a carburizing gas atmosphere and then quenched. A heat treatment apparatus is known, and the heat treatment apparatus is composed of a gas carburizing section consisting of a heating zone, a carburizing zone and a diffusion zone which are sequentially formed, a quenching zone for cooling by a cooling pipe and a quenching zone having a quenching tank. And a quenching section.

In the meantime, as the heat treatment, in the case where carbonitriding treatment is required in which the carburized object is further heated in a nitriding gas atmosphere for the purpose of improving the hardenability of the object and then quenched. However, carbonitriding cannot be performed with the above heat treatment apparatus.

Therefore, when carbonitriding the object to be treated, as shown in JP-A-63-210287, the object to be treated is carburized so as to have a predetermined carbon potential in the carburizing furnace. After heating in a volatile gas atmosphere and then cooling, the object to be processed was placed in a nitriding furnace and heated in a nitriding gas atmosphere in which a predetermined carbon potential and nitrogen potential were obtained and then quenched.

The heat treatment cycle in this case is as shown in FIGS. That is, as shown in FIG. 17, first, the object to be treated is heated to about 800 to 900 ° C., then held in a carburizing furnace at a temperature of about 900 ° C. to 950 ° C. for carburization, and then the object to be treated is The processed material is cooled in a carburizing furnace and carried out of the furnace when the temperature reaches about 350 ° C. Next, as shown in FIG.
After reheating to 0 ° C. and holding at that temperature for soaking, the temperature is lowered to about 820 to 840 ° C., and thereafter, the temperature is maintained at about 820 to 840 in a nitriding furnace for carbonitriding. The object to be treated is quenched.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
-210287, as shown in the publication,
The method of carburizing in the carburizing furnace and then cooling in the furnace or outside the furnace, then heating the object to be processed again, carbonitriding it in the nitriding furnace, and then quenching, has a low work efficiency and a large energy loss. There's a problem.

Further, in the method of carburizing the object to be treated in the carburizing furnace and then quenching, and then carbonitriding the object to be treated in the nitriding furnace and then quenching again, the work efficiency is improved, but by performing the quenching twice. There is a problem that the object to be processed is thermally deformed.

On the other hand, in the method of cooling an object to be processed with a cooling pipe as shown in Japanese Utility Model Publication No. 62-118167, the object to be processed cannot be cooled uniformly and rapidly. Considering that the cooling zone in the apparatus has a structure in which the object to be processed is cooled by the cooling gas.

That is, the heat treatment apparatus considered by the present inventors includes a heat treatment zone for heat treating an object to be treated in an atmosphere gas, and a cooling zone for cooling the object to be heat treated in the heat treating zone with a cooling gas. The heat treatment zone and the cooling zone are in communication with each other through the opening / closing door.

However, when the open / close door is opened and the object to be processed heated in the heat treatment zone is transferred to the cooling zone, the pressure in the cooling zone rises due to the radiant heat generated by the high temperature object to be processed. For this reason, the cooling gas introduced into the cooling zone flows into the heat treatment zone, so that the concentration of the atmospheric gas in the heat treatment zone changes and the quality of the object to be treated is adversely affected.

When the cooling of the object to be processed is started after the transfer of the object to be processed to the cooling zone is completed and the opening / closing door is closed, the pressure in the cooling zone decreases as the temperature of the object to be processed decreases. Therefore, the problem that the atmospheric gas in the heat treatment zone penetrates into the cooling zone through a small gap around the opening / closing door and deteriorates the quality of the object to be treated, and the outside air, that is, O ₂ is the wall portion of the cooling zone. small gap flows into the cooling zone through, or cause explosion, or O ₂
However, there is also a problem in that the slag penetrates into the joint of the object to be treated and causes quality deterioration due to decarburization.

A first object of the present invention is to efficiently carry out a series of operations of carburizing the object to be processed, cooling it, then carbonitriding the object to be processed, and then quenching it, and to perform the series of operations with energy. It should be done without loss.

A second object of the present invention is to provide a heat treatment apparatus provided with a heat treatment zone for heat treating an object to be treated in an atmosphere gas and a cooling zone for cooling the object to be treated with a cooling gas. The object is to allow the object to be processed to be cooled uniformly and rapidly without degrading the quality.

[0014]

In order to achieve the first object, the invention according to claim 1 divides a series of passages by opening and closing doors in order to form a carburizing zone, a cooling zone and a nitriding zone. It is a thing.

Specifically, the solution means devised by the invention of claim 1 is provided with a carburizing zone, a cooling zone, and a nitriding zone which are sequentially formed by partitioning a series of passages by opening and closing doors, and the object to be treated. Is provided along with the series of passages, and a forced cooling means for cooling the object to be processed is provided in the cooling zone.

According to a second aspect of the present invention, in order to cool the object to be treated uniformly and rapidly, the forced cooling means in claim 1 is gas cooling means for blowing a cooling gas to the object to be cooled. Is.

In order to achieve the second object, claim 3
In the invention, the pressure in the cooling zone is adjusted so that the pressure in the cooling zone becomes equal to the pressure in the heat treatment zone.

Specifically, the means for solving the problems according to the third aspect of the invention is to provide a heat treatment zone for heat-treating an object to be treated in an atmosphere gas, and a cooling for cooling the object to be heat-treated in the heat treatment zone with a cooling gas. And a heat treatment zone and a cooling zone are in communication with each other via a door.
The cooling zone is provided with pressure adjusting means for adjusting the pressure inside the cooling zone.

In order to achieve the second object, the invention according to claim 4
The invention of, provides a muffle that surrounds the space between the openings of the cooling gas blowing duct and the cooling gas recovery duct, and guides the cooling gas blown out from the cooling gas blowing duct to the object to be processed. is there.

Specifically, the means for solving the problems according to the invention of claim 4 is a heat treatment zone for heat-treating an object to be treated in an atmosphere gas, and cooling for cooling the object to be heat-treated in the heat treatment zone with a cooling gas. And a heat treatment zone and a cooling zone are in communication with each other via a door.
The cooling zone is a cooling gas blow-out duct for blowing a cooling gas to the object to be processed provided at a position facing the object set position in the cooling zone, and a cooling gas blown to the object to be processed. A cooling gas recovery duct for recovering gas, and a fixed wall member provided on the fixed wall surface of the cooling zone so as to surround the space between the cooling gas blowing duct and the openings of the cooling gas recovery duct, and A muffle configured by a movable wall member provided on the opening / closing door.

According to the fifth aspect of the present invention, the radiant heat from the muffle is applied to the peripheral portion of the object to be processed, which has a small flow resistance of the cooling gas and is easily cooled, and the object to be processed has a large flow resistance of the cooling gas and is hard to be cooled. In order to balance with the center,
The fixed wall member and the movable wall member of claim 4 are constituted by a heat reflection plate.

In order to achieve the second object, the sixth aspect of the present invention is provided.
In the invention, the cooling gas blowing duct has an inner / outer multi-cylinder structure to blow the cooling gas flowing by rectification to the object to be processed, and the cooling gas recovery duct has an inner / outer multi-cylinder structure and the inner cylinder thereof. The suction force of the cooling gas recovery duct is made to act strongly on the central portion of the object to be processed by projecting the gas toward the object to be processed from the outer cylinder.

Specifically, the means for solving the problems according to the sixth aspect of the invention is to provide a heat treatment zone for heat-treating an object to be treated in an atmosphere gas, and a cooling for cooling the object to be heat-treated in the heat treatment zone with a cooling gas. The zone and the cooling zone are sprayed on a cooling gas blowing duct for spraying a cooling gas to the object to be processed and the object to be processed which are provided at positions facing each other with the object to be processed set position in the cooling zone. Equipped with a cooling gas recovery duct for recovering the cooling gas
These cooling gas blowing ducts and cooling gas recovery ducts each have an internal / external multi-cylinder structure, and the cooling gas recovery ducts are configured such that their inner cylinders project more toward the object than the outer cylinders. is there.

[0024]

According to the structure of the invention of claim 1, a carburizing zone, a cooling zone and a nitriding zone in which a series of passages are divided by opening and closing doors, and a transfer means for sequentially transferring the object to be treated along the series of passages. Therefore, in the case of carbonitriding an object to be treated, if the temperature of the object carburized in the carburizing zone drops to a desired temperature, the object is carbonitrided in the nitriding zone without being carried out of the furnace. it can. Further, since the cooling zone is provided with the forced cooling means, the time required for cooling the object to be processed can be saved.

According to the configuration of the second aspect of the present invention, in the cooling zone, the object to be processed can be cooled by spraying a cooling gas, so that the object to be processed is uniformly and rapidly cooled.

According to the third aspect of the present invention, since the pressure adjusting means for adjusting the pressure of the cooling zone is provided in the cooling zone, the pressure of the cooling zone can be adjusted to be equal to the pressure of the heating zone. .. Therefore, the pressure difference between the heating zone and the cooling zone can be eliminated,
Since the atmospheric gas does not flow from the heating zone to the cooling zone and the cooling gas in the cooling zone does not flow into the heating zone, the concentration of the atmospheric gas in the heating zone does not change. Further, since the pressure drop in the cooling zone can be prevented, the outside air, that is, O ₂ does not flow into the cooling zone.

According to the structure of the invention of claim 4, a fixed wall member provided on the fixed wall surface of the cooling zone so as to surround the space between the openings of the cooling gas blowing duct and the cooling gas recovery duct and the opening and closing. Since the muffle is constituted by the movable wall member provided on the door, the cooling gas blown out from the cooling gas blowing duct is regulated by the muffle and flows toward the object to be processed.

Further, since the opening / closing door is provided between the cooling zone and the heat treatment zone, the wall surface of the cooling zone itself is uneven, but the space between the cooling gas blowing duct and the cooling gas recovery duct is a muffle. Since it is surrounded by, the space around which the cooling gas flows is flat.

Furthermore, since the movable wall member is provided on the opening / closing door and moves together with the opening / closing door, it does not interfere with the transfer of the object to be processed from the heat treatment zone to the cooling zone.

According to the fifth aspect of the invention, the fixed wall member and the movable wall member are formed of heat reflecting plates, so that the peripheral portion of the object to be processed, which has a small flow resistance of the cooling gas and is easily cooled, is separated from the heat reflecting plate. Because the cooling rate slows down due to radiant heat,
The balance with the central portion of the object to be processed, which has a large flow resistance of the cooling gas and is hard to be cooled, is maintained.

According to the structure of the invention of claim 6, the cooling gas blow-out duct is constructed in the inner and outer multi-cylinder structure.
Since the cooling gas blown out from the cooling gas blowing duct is straightened and blown straight onto the object to be treated, the flow velocity of the cooling gas blown to each part of the object to be treated becomes substantially uniform.

Further, since the cooling gas recovery duct is constructed in the inner-outer multi-cylinder structure, and the inner tube thereof is projected to the object side from the outer tube, the inside of the cooling gas recovery duct is formed. The cylinder is closer to the object to be treated than the outer cylinder, and the suction force acting on the central portion of the treatment object is stronger than the suction force acting on the peripheral portion of the treatment object. Therefore, originally, the cooling gas flowing through the central portion of the object to be processed has a large flow resistance, so the flow velocity is slow, but as described above, the suction force of the cooling gas recovery duct is Since it has a strong effect on the cooling gas flowing therethrough, the cooling gas has a substantially uniform flow velocity in the central portion and the peripheral portion of the object to be treated.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic plan structure of a left side portion of a heat treatment apparatus A according to an embodiment of the present invention, and FIG. 2 shows a schematic plan structure of a right side portion of the heat treatment apparatus A. Inside a tunnel type continuous furnace 10 having a series of passages extending in the left-right direction, pallets 1 loaded with objects to be treated
2 is sequentially transferred from the left side to the right side by a power roller which will be described later as a transfer means.

The continuous furnace 10 has a plurality of opening / closing doors 14 which can be opened and closed.
The continuous furnace 10 is sequentially partitioned from the left by a degreasing chamber 16, a heating chamber 18, a carburizing chamber 20 as a carburizing zone and a heat treatment zone, a cooling chamber 22 as a cooling zone, and a reheating chamber 24. , Greenhouse 26 as nitriding zone
The nitriding chamber 28 and the extraction vestibule 30 are partitioned and formed. In this case, a double door 14 is provided between the cooling chamber 22 and the reheating chamber 24 in order to enhance the sealing property between the two chambers. Further, a salt bath 32 is arranged on the right side of the continuous furnace 10 adjacent to the continuous furnace 10.

The degreasing chamber 16 is a degreasing process, that is, a zone for removing oil adhering to the surface of the object to be treated. In the degreasing process, the oil adhering to the object to be treated is evaporated during the heat treatment. Is carried out in order to prevent the desired heat treatment, for example, carburizing treatment from being not properly performed by contaminating the atmospheric gas. Then, in order to perform the degreasing treatment by heating the object to be treated, the degreasing chamber 16 has an electrotube 34 as a heater for raising the room temperature to about 700 to 800 ° C., a stirring fan 36 for stirring the heated air, and The degreasing chamber 16
The thermocouple 38 as a temperature sensor for detecting the room temperature is provided.

The temperature raising chamber 18 is a zone for preheating the degreased object to be treated, and the temperature raising chamber 18 is an electrotube for raising the room temperature to about 900 to 950 ° C. to heat the object to be treated. 34. An acid carburizing gas (hereinafter referred to as an acid carburizing gas) which is a metamorphic gas (a mixed gas of air and C ₄ H ₁₀ ) obtained by an in-furnace metamorphic method in order to prevent oxidation and decarburization of an object to be treated. .) For introducing an acid carburizing gas, a sample tube 42 having a built-in O ₂ sensor for detecting the oxygen concentration in the temperature raising chamber 18 for sampling an atmospheric gas, a stirring fan 36 and a thermocouple similar to the above. 38 are provided respectively.

The carburizing chamber 20 is a zone for carburizing, that is, for diffusing and permeating C (carbon) on the surface of the object to be treated, and for carburizing, the room temperature of the carburizing chamber 20 is about 900 ° C. to 95 ° C.
An electrotube 34 for raising the temperature to 0 ° C., an acid carburizing gas introducing section 40B for introducing an acid carburizing gas for diffusing and permeating C into the surface of the object to be treated, a stirring fan 36 similar to the above.
A thermocouple 38 and a sample tube 42 are provided respectively.

The cooling chamber 22 is a zone for forcibly cooling the carburized object, and the cooling chamber 22 introduces an acid carburizing gas into the cooling chamber 22 as shown in FIG. 3 and described below. An acid carburizing gas supply means 44, a gas cooling means 46 as a forced cooling means for spraying a cooling gas to the object to be cooled, and a pressure adjusting means 48 for adjusting the pressure in the cooling chamber 22 are respectively provided.

The acid carburizing gas supply means 44 includes a pressurized air supply device 44a for supplying excess air and C ₄ which is a raw material gas.
Butane supply device 44b for supplying H ₁₀ , excess air and C
Mixing valve 44 that mixes with ₄ H ₁₀ to produce acid carburizing gas
c and O ₂ in the acid carburizing gas are burnt to generate O ₂ in the cooling chamber 2.
2, a ring burner 44d for preventing invasion into 2, a flow rate adjusting valve 44e for adjusting the flow rate of the acid carburizing gas, and a pressure rise in the cooling chamber 22 is prevented by releasing the cooling gas in the cooling chamber 22 to the outside. And a pressure reducing valve 44f.

As described above, the heat treatment apparatus A includes the cooling chamber 22.
Further, since the acid carburizing gas supply means 44 is provided, it is possible to prevent oxidation and decarburization of the object to be processed when cooling the object to be processed.

The gas cooling means 46 includes a nitrogen supply device 46a for supplying N ₂ gas as a cooling gas, a cooling gas blow-out duct 46b for blowing the cooling gas onto the object to be processed, and a gas to be sprayed onto the object to be processed. The cooling gas recovery duct 46c for recovering the cooling gas thus collected, the cooling gas circulation path 46d having a circulation pump 46p and a bypass path 46q through which the cooling gas circulates, and the recovered high temperature cooling gas. A heat exchanger 46e for cooling, a refrigerant supply device 46f for supplying a refrigerant to the heat exchanger 46e, a refrigerant circulation path 46g for circulating the refrigerant between the refrigerant supply apparatus 46f and the heat exchanger 46e, and a refrigerant circulation path 46g. And a bypass passage 46h formed of a plurality of passages having different diameters for adjusting the flow rate of the refrigerant.

As described above, the heat treatment apparatus A includes the cooling chamber 22.
Since the gas cooling means 46 is provided in the above, the cooling rate in the case of the conventional furnace cooling is usually 6 ° C./minute, whereas the cooling rate can be improved to about 108 to 30 ° C./minute. Since it takes about 4 to 11 minutes to cool the processed product from about 900 to 950 ° C. to about 500 ° C., cooling after carburization can be efficiently performed.

Further, since the object to be treated is rapidly cooled after carburizing, it is not necessary to quench the object to be treated after carburizing, so that thermal deformation of the object to be treated which occurs when quenching the object to be treated after carburizing is prevented. You can also do it.

The pressure adjusting means 48 is the above-mentioned pressure reducing valve 44f.
And a pressing means 50 described below.

The timing for operating the pressure reducing valve 44f may be set to a time from immediately after the object to be processed is transferred to the cooling chamber 22 until a predetermined time elapses, or a pressure sensor may be provided in the cooling chamber 22. May be provided and set based on the signal from the pressure sensor.

The pressurizing means 50 is an endothermic shift gas supply device 50a for supplying an endothermic shift gas as a carburizing gas.
The endothermic shift gas introducing passage 50b for introducing the endothermic shift gas into the cooling chamber 22, the booster 50c interposed in the endothermic shift gas introducing passage 50b for pressurizing the endothermic shift gas, and the endothermic shift gas introducing passage 50b are circulated. A flow control valve 50d for adjusting the flow rate of the endothermic shift gas, a pressure tank 50e for storing the pressurized endothermic shift gas, a relief valve 50f for preventing the pressure in the pressure tank 50e from exceeding a predetermined pressure, The pressure tank 50e includes a pressure sensor 50g that detects the pressure of the pressure tank 50e, a pressure meter 50h that displays the pressure of the pressure tank 50e, and an O ₂ sensor 50i that detects the oxygen concentration in the pressure tank 50e. The pressure of the cooling chamber 22 can be increased by supplying the endothermic-type shift gas therein to the cooling chamber 22.

As described above, the heat treatment apparatus A includes the cooling chamber 22.
Since the pressure adjusting means 48 including the pressure reducing valve 44f and the pressurizing means 50 is provided in the above, the high temperature object to be processed may be transferred from the carburizing chamber 20 to the cooling chamber 22 and the pressure in the cooling chamber 22 may increase. When there is, the pressure reducing valve 44f can be operated to prevent the pressure in the cooling chamber 22 from rising.
Therefore, the cooling gas in the cooling chamber 22 flows into the carburizing chamber 20 and the concentration of the carburizing gas in the carburizing chamber 20 changes,
It is possible to prevent a situation in which the object to be processed is adversely affected. Further, the temperature of the object to be processed in the cooling chamber 22 decreases,
When there is a possibility that the pressure of 2 will become low, the pressurizing means 50 can be operated to prevent the pressure of the cooling chamber 22 from decreasing. Therefore, a carburizing gas flows into the cooling chamber 22 from the carburizing chamber 20 or O ₂ flows into the cooling chamber 22 from the outside, which may adversely affect the object to be processed or cause the cooling chamber 22 to explode. The situation can be prevented. In this case, the timing for actuating the pressurizing means 50 may be set to a time from immediately after the object to be processed is transferred to the cooling chamber 22 and the opening / closing door 14 is closed until a predetermined time elapses, A pressure sensor may be provided in the cooling chamber 22 and may be set based on a signal from the pressure sensor.

FIG. 4 shows a pressure adjusting means 52 as a modified example of the pressure adjusting means 48.
Reference numeral 2 is used to cool an acid carburizing gas for carburizing as a cooling gas.

As shown in the figure, the pressure adjusting means 52 is
The cooling gas blow-out duct 46b and the cooling gas recovery duct 46c are connected to each other, and a circulation duct 52a for circulating the acid carburizing gas is provided, and the blower 52b and the acid carburizing gas cooling are provided in the middle of the circulation duct 52a. Heat exchanger 52
c is provided. The acid carburized gas recovered from the cooling gas recovery duct 46c is used as the heat exchanger 5 for cooling the acid carburized gas.
After being cooled by 2c, it is blown onto the object to be treated B in the cooling chamber 22 from the cooling gas blowing duct 46b. Also,
As shown in the figure, the pressure adjusting means 52 includes an acid carburizing gas discharge vent 52e having a vent valve 52d, a first pressure switch 52f provided in the cooling chamber 22, and a reserve tank 52g for storing the acid carburizing gas. , Circulation duct 5
Communication pipe 52 for communicating 2a with the reserve tank 52g
h, a first pressure switch 52i provided in the reserve tank 52g, an acid carburizing gas introducing pipe 52l for introducing the acid carburizing gas into the reserve tank 52g, which has an acid carburizing gas supply valve 52j and a booster pump 52k. I have it. In the middle of the communication pipe 52h, a large diameter large amount gas supply passage 52n having a large amount gas supply valve 52m and a small diameter small amount gas supply passage 52p having a small amount gas supply valve 52o are provided.
It branches to and.

The setting of the first pressure switch 52f will be described below with reference to FIG. That is, the first pressure switch 52f opens the vent valve 52d when the pressure in the cooling chamber 22 rises and reaches a high positive pressure level (L1), and the pressure in the cooling chamber 22 falls. , Vent valve 52 when negative pressure falls to low level (L3)
While closing d, the large amount gas supply valve 52n is opened, and the cooling chamber 2
When the pressure in 2 reaches the intermediate level (L2) of the positive pressure lower than the high level (L1) from the negative pressure, the large amount gas supply valve 5
2n is closed, the small amount gas supply valve 52o is opened when the state is higher than the intermediate level (L2) and lower, and the small amount gas supply valve 52o is opened when the state is lower than the intermediate level (L2) and higher. 52o is closed.

The second pressure switch 52i opens the acid carburizing gas supply valve 52j when the pressure in the reserve tank 52g is reduced, and opens the acid carburizing gas when the pressure in the reserve tank 52g is accumulating. It is set to close the supply valve 52j.

The pressure fluctuation in the cooling chamber 22 and the operation of the pressure adjusting means 52 will be described below. Note that FIG. 6 shows the flow rate of the acid carburizing gas supplied to the cooling chamber 22.

Before the object B to be carburized in the carburizing chamber 20 is carried into the cooling chamber 22, there is a predetermined amount of acid carburizing gas in the cooling chamber 22, and the pressure in the cooling chamber 22 is It is kept at the middle level (L2). Then, when the opening / closing door 14 between the carburizing chamber 20 and the cooling chamber 22 is opened and the object to be treated B is carried into the cooling chamber 22 from the carburizing chamber 20, the atmospheric gas in the cooling chamber 22 is heated. The pressure in the cooling chamber 22 rises sharply and exceeds the high level (L3). Then, the first pressure switch 52f operates and the vent valve 52d is opened, so that the pressure in the cooling chamber 22 decreases.

Next, when the opening / closing door 14 is closed, the inside of the cooling chamber 22 is cooled, so that the pressure in the cooling chamber 22 is reduced to a negative pressure, and is lowered to the low level (L3). Then, the vent valve 52 is opened by the first pressure switch 52f.
d is closed and the large amount gas supply valve 52m is opened. Since a large amount of acid carburizing gas is rapidly supplied from the reserve tank 52g to the cooling chamber 22, the cooling chamber 22
The pressure inside recovers. When the pressure in the cooling chamber 22 is restored to the intermediate level (L2), the first pressure switch 52f closes the large amount gas supply valve 52m.

Next, as the object B to be processed in the cooling chamber 22 is cooled, the pressure in the cooling chamber 22 decreases again, and when the pressure becomes lower than the intermediate level (L2), the first pressure switch A small amount gas supply valve 52o is opened by 52f, and a small amount of acid carburizing gas is supplied from the reserve tank 52g into the cooling chamber 22. Then, when the pressure in the cooling chamber 22 reaches the intermediate level (L2), the small amount gas supply valve 52o is closed by the first pressure switch 52f. After that, cooling room 2
When the pressure in 2 fluctuates above and below the intermediate level (L2),
The opening and closing of the small amount gas supply valve 52o is intermittently repeated by the first pressure switch 52f, whereby the pressure in the cooling chamber 22 is kept substantially constant.

On the other hand, from the reserve tank 52g to the cooling chamber 2
When a large amount of acid carburizing gas is supplied to 2, the inside of the reserve tank 52g is in a depressurized state. Then, the acid carburizing gas supply valve 52j is opened by the second pressure switch 52i, and the step-up pump 52k is driven to reserve the reserve tank 52.
Acid carburizing gas is supplied into g. Then, when the inside of the reserve tank 52g reaches a predetermined pressure accumulation state, the acid carburizing gas supply valve 52j is closed, the boost pump 52k is stopped, and the supply of the acid carburizing gas to the reserve tank 52g is stopped. In this way, the inside of the reserve tank 52g is always kept in a pressure accumulation state.

In the pressure adjusting means 52, the communication pipe 52h is branched to provide the large amount gas supply passage 52n and the small amount gas supply passage 52p, but instead of this, the large amount gas supply passages 52n and 52n independent from each other are provided. A small amount gas supply path 52p may be provided.

As shown in FIG. 2 again, the reheating chamber 24 is
This is a zone in which the object to be treated is heated again in order to form a solid solution of the metal structure in the austenite structure.
Is an electrotube 34 that raises the room temperature to approximately 850 to 870 ° C., an acid carburizing gas introducing section 40C and an endothermic conversion gas introducing section 54 for preventing oxidation and decarburization of the object to be treated.
C, a stirring fan 36 similar to the above, a thermocouple 38, and a sample tube 42 are provided.

The greenhouse 26 is a zone for appropriately carbonitriding the object heated in the reheating chamber 24, so that the temperature of the object is lowered to about 820 to 840 ° C. Similar to the reheating chamber 24, is equipped with an electrotube 34, a stirring fan 36, a thermocouple 38, an acid carburizing gas introducing section 40D, a sample tube 42, and an endothermic conversion gas introducing section 54D.

Further, an ammonia supply means 56D for supplying NH ₃ for obtaining a nitriding gas is connected to the greenhouse 26, and the ammonia supply means 56D is connected to NH ₃
And an ammonia supply device 56a for supplying NH ₃ , an ammonia introduction path 56b for introducing NH ₃ into the greenhouse 26, and a bypass path 56c having a plurality of different diameters for adjusting the amount of NH ₃ flowing through the ammonia introduction path 56b. It consists of

In this way, in the interior of the greenhouse 26, ammonia supplying means is provided for the acid carburizing gas introduced from the acid carburizing gas introducing section 40D and / or the endothermic converting gas introduced from the endothermic converting gas introducing section 54D. N introduced from 56D
Since H ₃ gas is added to generate carbonitriding gas,
The inside of the descending greenhouse 26 becomes a carbonitriding gas atmosphere. Therefore, the object to be treated is carbonitrided in the process of lowering the temperature of the object to be treated in the greenhouse 26 to about 820 to 840 ° C.

The object to be treated, which has been heated to about 850 to 870 ° C. in the reheating chamber 24, is heated to about 820 to 840 ° C. in the descending greenhouse 26.
The reason why the temperature is lowered to about 850 to 870 ° C. is that the metal structure of the object to be treated does not form a solid solution with the austenite structure, while NH ₃ added for carbonitriding is about 820 to 84.
This is because it decomposes moderately into [N] and H ₂ at 0 ° C.

In the nitriding chamber 28, the object whose temperature has been lowered in the greenhouse 26 is heated to about 82 in a carbonitriding gas atmosphere similar to the above.
This is a zone for full-scale carbonitriding of the object to be treated by maintaining it at a temperature of 0 to 840 ° C.
Is an electro tube 34 for raising the room temperature to about 820 to 840 ° C., a stirring fan 36 similar to the reheating chamber 24,
The thermocouple 38, the acid carburizing gas introduction part 40E, the sample tube 42, the endothermic modified gas introduction part 54E, and the ammonia supply means 56E are provided, respectively.

The extraction vestibule 30 transfers the nitriding object from the continuous furnace 10 to the salt bath 32. Therefore, when the opening / closing door 14 on the right side of the nitriding chamber 28, that is, the salt bath 32 side is opened, the nitriding chamber 28 is opened. It is a zone for preventing the pressure and temperature from decreasing, and is provided with an electrotube 34 and a thermocouple 38 similar to the above.

The salt bath 32 is for hardening the carburized object by salt quenching and has a well-known structure.

A first bypass passage 58 having a passage opening / closing valve 58a is provided between the reheating chamber 24 and the greenhouse 26 so that the chambers can communicate with each other. In order to communicate both chambers with 28, the flow path opening / closing valve 6
0a is provided between the second bypass passage 60 and the nitriding chamber 28 and the extraction vestibule 30 so that both chambers communicate with each other.
Two are provided. The reheating chamber 24 includes the reheating chamber 2
In order to discharge the carburizing gas in 4 to the outside,
4a is provided with a reheating chamber gas discharge path 64, and the greenhouse 26 is provided with a passage opening / closing valve 66a for discharging the carbonitriding gas in the greenhouse 26 to the outside. A gas discharge path 66 is provided, and the extraction vestible 30 is provided with an extraction vestible gas discharge path 68 provided with a flow path opening / closing valve 68a for discharging the carbonitriding gas in the extraction vestible 30 to the outside. ..

FIG. 6 shows a heat treatment cycle when carbonitriding is performed using the present heat treatment apparatus A. As described above, the object to be treated is heated to about 800 to 900 ° C. in the temperature raising chamber 18 and then heated. After being transferred to the carburizing chamber 20, being held in the carburizing chamber 20 at about 900 to 950 ° C. for carburizing, and then being transferred to the cooling chamber 22 and being cooled to about 300 to 500 ° C. in the cooling chamber 22, The reheating chamber 2 is transferred to the reheating chamber 24
4 is heated to about 870 ° C., then transferred to the descending greenhouse 26, cooled to about 820 to 840 ° C. in the descending greenhouse 26, and then transferred to the nitriding chamber 28, and about 820 to 8 in the nitriding chamber 28.
It is held at 40 ° C. for carbonitriding, and then transferred to the salt tank 32 through the extraction vestibule 30 and the salt tank 3
Quenched at 2.

As described above, the heat treatment apparatus A includes the temperature raising zone, the carburizing zone, the cooling zone, the reheating zone and the nitriding zone, which are formed by sequentially partitioning a series of passages by opening and closing doors.
Since it has a transfer means for sequentially transferring the object to be processed,
Since the object carburized in the carburizing zone can be carbonitrided in the nitriding zone without being carried out of the furnace, the carbonitriding work can be efficiently performed. Further, since the cooling zone is provided between the carburizing zone and the re-heating zone, when the temperature of the object to be treated falls to the desired temperature, the object to be treated can be immediately heated in the re-heating chamber, thus eliminating energy loss. .. Furthermore, since the forced cooling means is provided in the cooling zone, the time required for cooling the object to be processed can be saved, so the work efficiency of the carbonitriding process is improved. Therefore, the present heat treatment apparatus A can efficiently perform a series of carbonitriding treatments without energy loss.

FIG. 8 shows the above-mentioned plan structure of the cooling chamber 22, FIG. 9 shows the vertical sectional front structure of the cooling chamber 22, and FIG. 10 shows the cross-sectional side structure of the cooling chamber 22, respectively. After being placed on the power roller 70, transferred to the carburizing chamber 20 via the decarburizing chamber 16 and the temperature raising chamber 18, the carburizing chamber 20 is carburized, and then transferred from the left side to the right side in FIG. It is set at the center of the.

The above-mentioned cooling gas blowing duct 46b is
It is provided below the object to be processed B set in the cooling chamber 22, specifically, directly below the power roller 70. The cooling gas blow-out duct 46b is arranged concentrically and is constituted by a five-fold cylinder having a long track-shaped cross section in the direction orthogonal to the transfer direction. The lower part of the outer peripheral wall of the outer cylinder 46i hangs down while being depressed in a truncated cone shape, and the cooling gas circulation that connects the cooling gas blowout duct 46b and the cooling gas recovery duct 46c at the lower end of the outer cylinder 46i. It communicates with the duct 78. In addition, each upper end surface of the quintuple cylinder is formed flush with each other, while each lower end surface of the five-fold cylinder is an outer cylinder
It is configured to gradually project downward from i to the inner cylinder 46j.

In this way, the cooling gas blowing duct 46
Since the lower surface of b is configured so as to sequentially project downward from the outer cylinder 46i to the inner cylinder 46j, that is, to the upstream side of the cooling gas, the inner cylinder 46j introduces the cooling gas in a rectified state and in a large amount. Therefore, the inner cylinder 46j can blow the cooling gas having a higher flow velocity than the outer cylinder 46i, that is, a large amount of the cooling gas to the object B to be processed. Therefore, originally, the cooling gas flowing through the inside of the object to be processed B has a large resistance, so that the flow velocity becomes slow, but the object to be processed B is rapidly cooled by the cooling gas blowing duct 46b having the above structure. In addition, since each part of the object to be processed B is cooled uniformly, the object to be processed B is unlikely to be deformed.

FIG. 11 shows the cooling gas blowing duct 46b.
Shows the relationship between the cross-sectional shape of and the flow velocity of the cooling gas,
The flow velocity of the cooling gas blown from the central portion of the cooling gas blowing duct 46b is the same as that of the cooling gas blown from the peripheral portion in both the transfer direction of the workpiece B and the direction orthogonal to the transfer direction. It is shown that it is faster than the flow velocity of.

The cooling gas recovery duct 46c is provided above the object B set in the cooling chamber 22, specifically near the ceiling of the cooling chamber 22, and is connected to the cooling gas blowing duct 46b. It is opposed to the object B to be processed and communicates with the cooling gas circulation duct 78 via the ceiling plate 46k. Cooling gas recovery duct 46c
Are arranged concentrically in the inner and outer directions and are constituted by triple cylinders having a track-shaped cross section that is long in the direction orthogonal to the transfer direction. The outer cylinder 46l to the inner cylinder 46m.
It is configured so as to project in the vertical direction in succession.
The outer diameter of the cooling gas recovery duct 46c is slightly smaller than the outer diameter of the cooling gas blowing duct 46b.

Thus, the cooling gas recovery duct 46c
Since the lower surface of the cooling gas recovery duct 46c is configured to project downward from the outer cylinder 46l to the inner cylinder 46m, the cooling gas recovery duct 46c is closer to the object B to be processed. The suction force for the cooling gas flowing inside the object B is stronger than the suction force for the cooling gas flowing outside the object B. Therefore, originally, the cooling gas flowing through the inside of the object to be processed B has a large flow resistance and thus has a low flow rate, but in the heat treatment apparatus A,
Since the suction force of the cooling gas recovery duct 46c strongly acts on the cooling gas flowing through the inside of the object to be processed B, the cooling performance for the object to be processed B becomes substantially equal inside and outside the object to be processed B. ..

Further, since the upper surface of the cooling gas recovery duct 46c is constructed so as to sequentially project upward from the outer cylinder 46l to the inner cylinder 46m, the inside of the cooling gas recovery duct 46c is sucked toward the inside. Since the force is strong, the cooling gas flowing through the inside of the object to be processed B can be more strongly sucked.

As shown in FIGS. 8 and 10, the cooling chamber 22
A fixed wall member 80 made of a heat reflection plate is arranged between the power roller 70 and the ceiling plate 46k on both sides in the transfer direction of the object to be processed B and outside the cooling gas blowing duct 46b. There is. The fixed wall member 80 is provided in the cooling chamber 22.
The inner wall surface 22a is supported by the wall surface 22a.

Further, as shown in FIGS. 8 and 9, the opening / closing door 1 is provided at both front and rear ends in the transfer direction in the cooling chamber 22.
4 is supported by a hydraulic cylinder 82 so as to be vertically movable. Inside the opening / closing door 14 and outside the cooling gas blowing duct 46b, the power roller 70 and the ceiling plate 46 are provided.
A movable wall member 84 made of a heat reflection plate is disposed between the movable wall member 84 and k. The movable wall member 84 is supported by the opening / closing door 14 inside the inner surface of the opening / closing door 14. The heat reflecting plates forming the fixed wall member 80 and the movable wall member 84 are preferably made of a material having a high heat reflectance and a small heat capacity, such as a stainless steel plate.

When the fixed wall member 80 and the movable wall member 84 are formed of heat reflecting plates in this way, the peripheral edge of the object to be processed B, which has a low resistance of the cooling gas and is easily cooled, is cooled at a cooling rate by the radiant heat from the heat reflecting plate. Therefore, the balance with the central portion of the object to be processed B, which has a large flow resistance of the cooling gas and is hard to be cooled, is maintained. As a result, the object to be treated B is cooled uniformly, so that a high quality product can be obtained.

The fixed wall member 80 and the movable wall member 84 described above.
Thus, a muffle that surrounds between the opening of the cooling gas blowing duct 46b and the opening of the cooling gas recovery duct 46c is formed. The muffle has an inner peripheral shape slightly larger than the outer peripheral shape of the cooling gas blowout duct 46b, and has a height slightly lower than the dimension between the power roller 70 and the ceiling plate 46k.

When the opening / closing door 14 is moved downward,
The power roller 70a positioned below the power roller 70a is configured to rotate inward so as not to interfere with the opening / closing door 14.

As described above, the cooling gas blown out from the cooling gas blow-out duct 46b is regulated by the fixed wall member 80 and the movable wall member 84 forming the muffle and straightly flows into the cooling gas recovery duct 46c. Therefore, the cooling gas efficiently cools the object to be processed B. Further, the opening / closing doors 14 are provided at the front and rear ends of the cooling chamber 22 in the transfer direction, and the wall surface of the cooling chamber 22 is uneven, but the space through which the cooling gas flows is flat due to the above-mentioned muffle. The flow velocity of the cooling gas is not affected by the presence of the opening / closing door 14.

12 to 14 show a gas cooling means 86 as a modification of the above-described gas cooling means 46 provided in the cooling chamber 22. The gas cooling means 86 includes a temperature adjusting means 88 described later. I have it.

FIG. 12 shows a cutting front structure of the cooling chamber 22 provided with the gas cooling means 86. The opening / closing door 14, the movable wall member 84, the cooling gas blowout duct 46b, the cooling gas recovery duct 46c and the cooling door are shown. The basic functions of the gas circulation duct 78 are similar to those described above.

FIG. 13 shows the entire gas cooling means 86,
The first cylinder 46j is provided inside the cooling gas outlet duct 46b.
Temperature sensor 86a, a second temperature sensor 86b is provided in the cylinder 46m inside the cooling gas recovery duct 46c, and a cooling blower 86c is provided in the cooling gas circulation duct 78. The cooling gas circulation duct 78 is provided downstream of the circulation blower 86c and has a first flow rate control valve 86d.
It branches into a circulation duct 86e and a second circulation duct 86g having a second flow rate control valve 86f, and the first circulation duct 86e is equipped with a gas cooler 86h in the middle thereof.

The temperature adjusting means 88 receives the temperature signals from the first and second temperature sensors 86a and 86b and controls the first and second flow rate adjusting valves 86d and 86f.
The control contents are as shown below.

Opening / closing door 1 between the carburizing chamber 20 and the cooling chamber 22
4 is opened and the object to be processed B is carried into the cooling chamber 22, the temperature of the object to be processed B is high and the temperature of the cooling gas in the cooling gas circulation duct 78 is low, so the first temperature sensor 86a. Is low, and the temperature detected by the second temperature sensor 86b is high. Therefore, in this state, the temperature adjusting means 88 closes the first flow rate adjusting valve 86d and opens the second flow rate adjusting valve 86f, so that the cooling gas is supplied to the second circulation duct 8.
Supply from 6 g only. In this state, the peripheral edge of the object to be processed B is cooled by thermal radiation, and the central part of the object to be processed B is cooled by thermal radiation and convection.

Next, when the object B to be processed is cooled to some extent, the temperatures detected by the first and second temperature sensors 86a and 86b increase. In this state, the temperature adjusting means 88 opens the first and second flow rate adjusting valves 86d and 86f and supplies the cooling gas from the first and second circulation ducts 86e and 86g. As described above, the cooling efficiency is improved by adjusting the temperature of the cooling gas according to the temperature detected by the first temperature sensor 86a.

In FIG. 15, by cooling the object B to be carburized in the carburizing chamber 20 in the cooling chamber 22, the amount of the spherical carbide formed on the surface of the object B to be treated is adjusted to an appropriate amount. In the case, the relationship between the processing time and the temperature of the object to be processed B is shown. It is preferable to adjust the total cooling time (T3) so that the cooling speed is rapid during the first cooling time (T1) and the cooling rate is slow during the second cooling time (T2). By doing so, as shown in FIG. 19, the processing time (T) required for cooling can be greatly shortened as compared with the case of the conventional method (shown by a chain double-dashed line).

[0090]

According to the heat treatment apparatus of the first aspect of the present invention, there are provided a carburizing zone, a cooling zone and a nitriding zone in which a series of passages are sequentially divided by opening and closing doors, and a transfer means for sequentially transferring the object to be treated. Since it is provided, the object carburized in the carburizing zone can be carbonitrided in the nitriding zone without being carried out of the furnace, so that the carbonitriding work can be efficiently performed. Further, since the cooling zone is provided between the carburizing zone and the nitriding zone, when the temperature of the object to be treated decreases to the desired temperature, the object to be treated can be carbonitrided immediately in the nitriding zone, so that energy loss is eliminated. Furthermore, since the forced cooling means is provided in the cooling zone, the time required for cooling the object to be processed can be saved, so the work efficiency of the carbonitriding process is improved.

Therefore, according to the invention of claim 1, a series of carbonitriding operations can be efficiently performed without causing energy loss.

According to the heat treatment apparatus of the second aspect of the present invention, the object to be treated can be cooled by spraying the cooling gas, so that the object to be treated can be cooled uniformly and rapidly. The quality of the product is improved and the work efficiency is improved.

According to the heat treatment apparatus of the third aspect of the present invention, since the pressure adjusting means for adjusting the pressure of the cooling zone is provided in the cooling zone, the outflow of the atmospheric gas from the heating zone to the cooling zone and the cooling zone to the heating zone. Since it is possible to prevent the cooling gas from flowing into the chamber, that is, to prevent a change in the concentration of the atmospheric gas in the heating zone, the object to be processed can be cooled uniformly and rapidly, and the quality of the object to be processed can be improved.

Since the pressure drop in the cooling zone can be prevented, the explosion caused by the inflow of O ₂ can be prevented.

According to the heat treatment apparatus of the fourth aspect of the present invention, the fixed wall provided on the fixed wall surface of the cooling zone so as to surround the space between the openings of the cooling gas blowing duct and the cooling gas recovery duct. Since it is provided with a muffle constituted by a member and a movable wall member provided on the opening / closing door, the cooling gas blown out from the cooling gas blowing duct is regulated by the muffle and flows toward the object to be processed, The cooling efficiency for the object to be processed is improved. In addition, since the space between the cooling gas blowout duct and the cooling gas recovery duct is surrounded by the muffle, the space around the space through which the cooling gas flows is flat despite the opening / closing door. However, since the flow of the cooling gas is smooth, the cooling efficiency for the object to be processed is good.

Therefore, according to the fourth aspect of the present invention, the object to be processed can be cooled uniformly and rapidly without degrading the quality of the object to be processed.

Further, since the movable wall member is provided on the opening / closing door, it does not interfere with the transfer of the object to be processed from the heat treatment zone to the cooling zone.

According to the heat treatment apparatus of the fifth aspect of the present invention, since the fixed wall member and the movable wall member are each constituted by a heat reflection plate, the flow resistance of the cooling gas is small and the outer periphery of the object to be processed is easily cooled. Since the cooling rate of the part is slowed by the radiant heat from the heat reflection plate, the flow resistance of the cooling gas is large and the balance with the central part of the object that is difficult to cool is maintained, further improving the quality of the object. Can be made

According to the heat treatment apparatus of the sixth aspect of the present invention, the cooling gas recovery duct has an inner / outer multi-cylinder structure, and the inner cylinder is projected toward the object to be processed from the outer cylinder. Since the suction force of the recovery duct strongly acts on the cooling gas flowing through the central part of the object to be processed, the flow velocity of the cooling gas becomes substantially equal in the central part and the peripheral part of the object to be processed, The article located in the central portion and the article located in the peripheral portion can be cooled substantially evenly.

Further, since the cooling gas blowing duct is constructed in the inner and outer multi-cylinder structure, the cooling gas blown from the cooling gas blowing duct is rectified and blown to the object to be treated, so that each part of the object to be treated is rectified. The flow rate of the cooling gas blown onto the substrate is substantially uniform, and each part of the object to be processed can be cooled substantially uniformly.

Therefore, according to the invention of claim 6, the object to be processed can be cooled uniformly and rapidly, and the quality of the object to be processed can be improved.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a left side portion of a heat treatment apparatus that is an embodiment of the present invention.

FIG. 2 is a schematic plan view of the right side portion of the heat treatment apparatus that is an embodiment of the present invention.

FIG. 3 is an overall configuration diagram of a cooling chamber in the heat treatment apparatus.

FIG. 4 is an overall configuration diagram of a pressure adjusting means according to a modified example provided in the cooling chamber.

FIG. 5 is a diagram showing changes in pressure in a cooling chamber provided with a pressure adjusting means according to the modified example.

FIG. 6 is a diagram showing changes in the flow rate of acid carburizing gas in the pressure adjusting device.

FIG. 7 is a heat treatment cycle diagram when heat treatment is performed using the heat treatment apparatus.

FIG. 8 is a plan view of a cooling chamber in the heat treatment apparatus.

FIG. 9 is a sectional front view of the cooling chamber.

FIG. 10 is a sectional side view of the cooling chamber.

FIG. 11 is a flow velocity measurement diagram of a cooling gas in the cooling chamber.

FIG. 12 is a sectional front view of a cooling chamber including a gas cooling unit according to a modified example.

FIG. 13 is an overall configuration diagram of a gas cooling unit according to a modification and a sectional side view of a cooling chamber including the gas cooling unit.

14 is a cross-sectional view taken along line I-I in FIG.

FIG. 15 is a diagram showing the relationship between the processing time and the temperature of the object to be processed by the gas cooling means according to the modified example.

FIG. 16 is a diagram comparing a processing time by a gas cooling means according to a modified example with a processing time by a conventional gas cooling means.

FIG. 17 is a heat treatment cycle diagram when a conventional heat treatment apparatus is used.

FIG. 18 is a heat treatment cycle diagram when a conventional heat treatment apparatus is used.

[Explanation of symbols]

 10 ... Continuous furnace 14 ... Opening / closing door 18 ... Temperature raising chamber 20 ... Carburizing chamber (carburizing zone, heat treatment zone) 22 ... Cooling chamber (cooling zone) 22a ... Fixed wall surface 24 ... Reheating chamber 28 ... Nitriding chamber (nitriding zone) 44 ... Acid carburizing gas supply means 44f ... Decompression means 46 ... Gas cooling means (forced cooling means) 46b ... Cooling gas blowout duct 46c ... Cooling gas recovery duct 46i ... Cooling gas blowout duct outer cylinder 46j ... Cooling gas blowout Inner tube of duct 46l ... Outer tube of cooling gas recovery duct 46m ... Inner tube of cooling gas recovery duct 48 ... Pressure adjusting means 52 ... Pressurizing means 70 ... Power roller (transfer means) 76 ... Fixed wall member 80 ... Movable wall member

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23C 8/34 8116-4K F27B 9/02 7308-4K 9/04 7308-4K (72) Inventor Hideo Shoga 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Katsukazu Nagai 3-3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture (72) Inventor Masayuki Suzawa Hiroshima Prefecture 3-1, Shinchi Fuchu-cho, Aki-gun Mazda Co., Ltd. (72) Takashi Yamaoka 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima (72) Inventor Hiroshi Nagahama 3 Shinchi, Fuchu-cho, Aki-gun No. 1 in Mazda Motor Corporation

Claims (1)

Claims: 1. A carburizing zone, a cooling zone, and a nitriding zone, which are partitioned and formed by sequentially partitioning a series of passages by opening and closing doors, are sequentially provided, and an object to be treated is provided along the series of passages. And a forced cooling means for cooling the object to be processed are provided in the cooling zone. 2. The heat treatment apparatus according to claim 1,
The heat treatment apparatus, wherein the forced cooling means is a gas cooling means that blows a cooling gas onto an object to be processed to cool it. 3. A heat treatment zone for heat-treating an object to be processed in an atmospheric gas, and a cooling zone for cooling the object to be heat-treated in the heat treatment zone with a cooling gas. These heat treatment zones and cooling zones are provided. A heat treatment apparatus, which is in communication with each other through an opening / closing door, and wherein the cooling zone is provided with pressure adjusting means for adjusting the pressure inside the cooling zone. 4. A heat treatment zone for heat-treating an object to be processed in an atmosphere gas, and a cooling zone for cooling the object to be heat-treated in the heat treatment zone with a cooling gas. These heat treatment zones and cooling zones are provided. The cooling zones are in communication with each other via an opening / closing door, and the cooling zone is a cooling gas for blowing a cooling gas to the objects to be treated which are respectively provided at positions facing each other across the object set position in the cooling zone. The cooling gas recovery duct for recovering the cooling gas sprayed on the blowout duct and the object to be processed, and the cooling so as to surround the space between the openings of the cooling gas discharge duct and the cooling gas recovery duct. A heat treatment apparatus comprising a fixed wall member provided on a fixed wall surface of the zone and a muffle configured by a movable wall member provided on the opening / closing door. Place 5. The heat treatment apparatus according to claim 4,
The heat treatment apparatus, wherein each of the fixed wall member and the movable wall member is composed of a heat reflection plate. 6. A heat treatment zone for heat-treating an object to be treated in an atmosphere gas, a cooling zone for cooling an object to be heat-treated in the heat treatment zone with a cooling gas, and the cooling zone includes an object to be treated in the cooling zone. A cooling gas blowout duct for blowing a cooling gas to the object to be treated and a cooling gas recovery duct for recovering the cooling gas blown to the object to be treated, which are provided at positions opposite to each other across the workpiece setting position. The cooling gas blowout duct and the cooling gas recovery duct are each configured as an inner / outer multi-cylinder structure, and the cooling gas recovery duct is configured such that the inner cylinder projects toward the object side more than the outer cylinder. Heat treatment apparatus characterized in that