JP3861099B1 - Heat treatment furnace - Google Patents

Abstract

A heat treatment furnace that gas-cools the entire object to be heat-treated as uniformly as possible is realized with a simple configuration.
A stirrer that sucks and discharges a cooling gas introduced into a gas cooling space, and a cooling gas discharged from the stirrer that guides the gas toward a heat treatment target W disposed in the gas cooling space. A heat treatment including one blowout duct 23 and a second blowout duct 24 that guides the cooling gas discharged from the same stirrer 3 and blows it toward the heat treatment object W from a direction different from that of the first blowout duct 23. A furnace was constructed.
[Selection] Figure 3

Description

  The present invention relates to a heat treatment furnace for quenching a heat treatment object.

For example, a vacuum heat treatment furnace (see the following patent document) is known as an apparatus for quenching a heat treatment object such as a mold. In this type of vacuum heat treatment furnace, the object to be heat treated is heated for a predetermined time in a state where the inside of the furnace is evacuated, and then a low-temperature cooling gas is introduced or the object to be heat treated is put into an oil bath for rapid cooling treatment. It is customary.
JP-A-10-183236

  In the heat treatment furnace as described above, when the heated object to be heat treated is gas-cooled, the cooling gas introduced into the inner chamber is circulated while being stirred by the stirrer. Generally, one stirrer, that is, a turbofan and a prime mover that drives the turbofan is provided. The rotationally driven turbofan sucks the cooling gas in the thrust direction and blows it in the radial direction. This cooling gas is blown out toward the heat treatment object from the side away from the fan, and then sucked into the fan again. Therefore, the heat treatment object continues to receive the unidirectional cooling gas wind flowing toward the fan.

  Under the situation where the heat treatment object is cooled by the unidirectional wind flow, a local difference occurs in the temperature drop of the heat treatment object. The temperature of the cooling gas blown out toward the heat treatment object gradually increases by taking the heat amount of the high temperature heat treatment object, so that the portion of the heat treatment object where the cooling gas first comes into contact with the raised cooling gas contacts There is a difference in the cooling effect from the part, and the cooling becomes non-uniform in the heat treatment object. As a result, a difference (distortion) in dimensional change, variation in hardness, variation in internal structure and crystal grain size occurs in the heat treatment target. The influence varies depending on the material and mass of the heat treatment object, but cannot be overlooked when heat treatment is performed by mounting a large object or a plurality of objects having different masses. In addition, when processing an object that must be cooled to a predetermined temperature in a short time, such as a specific tool steel, in a short time in minutes / seconds, a slowing of the local cooling rate may lead to a serious loss. .

  The present invention made in view of the above problems is intended to realize a heat treatment furnace that cools the entire object to be heat treated as uniformly as possible with a simple configuration.

In the present invention, a heat treatment furnace capable of heating an object to be heat-treated and then oil-cooling after gas-cooling, oil-cooling, or gas-cooling, and extending in the vertical direction for gas cooling in the upper region. And a cooling chamber provided with an oil tank for oil cooling in the lower region, and a heat treatment object is lifted and transferred to the gas cooling space, or a heat treatment object is lowered and transferred to the oil tank. A lift, a stirrer that sucks and discharges the cooling gas introduced into the gas cooling space, and a first blowout that blows the cooling gas discharged from the stirrer from below to the heat treatment target disposed in the gas cooling space A duct, and a second blowing duct that guides a cooling gas discharged from the same stirrer and blows the heat treatment object disposed in the gas cooling space from above. The blowout duct has a blowout portion for blowing the cooling gas upward, and the blowout portion is below the heat treatment target disposed in the gas cooling space in the vicinity of the transfer path when the heat treatment target is transferred by the lift. What can be displaced between the position which faces more and the position which opens a transfer path | route was comprised.

  In other words, the cooling gas discharged from the stirrer is blown from a plurality of directions through the blowout ducts, so that the cooling effect given to the heat treatment object is made uniform. With such a configuration, the problem of local differences in the temperature drop of the heat treatment object can be effectively solved, and distortion of the heat treatment object and variations in metallurgical effects can be reduced or avoided. It is also a feature of the present invention that it is not necessary to equip a heat treatment furnace with a plurality of stirrers. In order to uniformly cool the entire object to be heat-treated, it may be possible to provide a plurality of stirrers in different orientations, but the structure of the heat treatment furnace that is most frequently used in practice, that is, a cooling oil tank below the gas cooling space. It is impossible to provide a stirrer in pairs above and below the gas cooling space in the arrangement structure. To avoid the interference of multiple agitators with other components of the heat treatment furnace, such as the oil tank and the transfer mechanism of the heat treatment object, it is essential to increase the size of the heat treatment furnace and occupy it as the construction cost increases. Increases space. In addition to the increase in the size of the heat treatment furnace, the transfer distance when the heat treatment object is transferred from the heating space to the gas cooling space is extended, and the time lag until the cooling after heating is increased, which is the purpose. There is also the possibility of causing intrinsic problems in the metallurgical effect. Such inconvenience does not occur in the present invention.

  In order to sufficiently achieve the intended purpose of uniformly cooling the entire object to be heat treated, the first blowing duct and the second blowing duct are provided in two substantially opposite directions, and heat treatment is performed therefrom. The cooling gas is blown out toward the object.

  Further, a reflux duct for introducing the cooling gas blown toward the heat treatment object into a direction crossing the blowing direction of the cooling gas by the first blowing duct and the second blowing duct and leading to the stirrer If it has, it can contribute to uniform cooling of the whole heat processing target object by smooth circulation of the cooling gas in the gas cooling space.

  In order to appropriately divert the cooling gas discharged from the stirrer to the first blowout duct and the second blowout duct, the fan of the stirrer sucks the cooling gas from a predetermined direction and blows the air around the fan. The cooling gas flowing into each of the first blowout duct and the second blowout duct is divided by dividing the periphery into a plurality of sections.

  Further, when the first blowing duct has a blowing portion in the vicinity of the transfer path when transferring the heat treatment object to the gas cooling space, and the cooling gas is blown out substantially parallel to the transfer path, Since the blow-out part can interfere with the transfer path by interfering with the transfer path, it is preferable that the blow-out part is movable so as to be retracted to a position that does not interfere with the transfer path.

  ADVANTAGE OF THE INVENTION According to this invention, the heat processing furnace which can carry out gas cooling of the whole heat processing target object uniformly can be implement | achieved by simple structure.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, for convenience of explanation, the side on which the carry-in / out entrance 212 for carrying in / out the heat treatment object W is defined as the front.

  The heat treatment furnace of the present embodiment heats the heat treatment object W in a vacuum or a reduced-pressure atmosphere of atmospheric pressure or less, and then transfers it to the gas cooling space 20 to perform gas cooling treatment. This is a vacuum heat treatment furnace that can be put into the oil tank 22 and can be cooled with oil, and can also be put into the oil tank 22 immediately after heating depending on the type of heat treatment object W and the purpose of heat treatment. As shown in FIG. 1, this heat treatment furnace is a two-chamber type having a heating chamber 1 for heating the heat treatment object W and a cooling chamber 2 for cooling the heat treatment object W heated in the heating chamber 1. A heat insulating body 12 and a heater 14, a vacuum exhaust system 4 and the like are provided on the heating chamber 1 side, and a cooling gas introduction system 5, a stirrer 3, an oil tank 22 and the like are provided on the cooling chamber 2 side.

  Specifically, a heat insulating body 12 having a substantially box shape is disposed in a furnace body 11 serving as an outer shell of the heating chamber 1, and a heater 14 is installed on the inner periphery thereof to heat the heat treatment object W. A space 15 is constructed. A heat insulating lid 13 that can be opened and closed is provided on the cooling chamber 2 side of the heat insulating main body 12. The heat insulating body 12 and the heat insulating lid 13 are made of, for example, graphite felt or the like as a material. The evacuation system 4 is formed by connecting, for example, a diffusion pump, a mechanical booster pump, an oil rotary vacuum pump, or the like in series, and is connected to the furnace body 11 so that connection / disconnection can be switched through a valve.

The furnace shell 11 communicates with a housing 21 that is an outer shell of the cooling chamber 2. The boundary between the furnace body 11 and the housing 21 is separated by a partition door 211 that operates integrally with the heat insulating lid 13. The housing 21 is expanded in the vertical direction, a cooling gas introduction system 5 for introducing a low-temperature cooling gas into the upper region, a stirrer 3 for stirring and circulating the introduced cooling gas, and ducts 23, 24 and 25 for introducing the cooling gas. , 26, a heat exchanger 27 for cooling the cooling gas is provided, and the gas cooling space 20 is constructed. The cooling gas introduction system 5 feeds an inert gas such as N ₂ that rapidly cools a heated object from a gas cylinder, and is connected to the housing 21 so that connection / disconnection can be switched via a valve. The stirrer 3 includes a turbo fan 31 that sucks and discharges cooling gas and a prime mover (motor or engine) 32 that rotationally drives the turbo fan 31, and is disposed at the upper end of the housing 21. The prime mover 32 is outside the housing 21, and its drive shaft penetrates into the housing 21 and is connected to the fan 31. A rotary vacuum seal is applied to a portion where the drive shaft of the prime mover 32 penetrates the housing 21. In addition, a loading / unloading port 212 for loading / unloading the heat treatment object W is provided below the gas cooling space 20 and at substantially the same height as the heating space 15 in the heating chamber 1. The carry-in / out entrance 212 is sealed by a door 212 that opens and closes. In addition, an oil tank 22 for storing quenching oil is disposed in the lower region of the housing 21. Oil tank 22 is oil-quenched immediately after heating when oil cooling is necessary after gas cooling due to metallurgical characteristics, or when it is desired to shorten the time for cooling to a temperature at which heat treatment object W is large and can be carried out after gas cooling. Use it when you want to. However, if the furnace is dedicated to the gas quenching process, the oil tank 22 is not essential.

  The outline of the quenching process by the heat treatment furnace of the present embodiment will be described. After the heat treatment object W is carried into the heating space 15 of the heating chamber 1 from the carry-in / out entrance 212, the vacuum exhaust system 4 is operated to move the inside of the furnace. The pressure is reduced, the heat insulating lid 13 and the partition door 211 of the heat insulating main body 12 are closed, and the heat treatment object W is heated by the heater 14. When the heating is completed, the heat insulating lid 13 and the partition door 211 are opened, and the heat treatment object W is taken out and cooled in the cooling chamber 2. At this time, gas cooling or oil cooling can be selected. When gas-cooling the heat treatment target object W, the motor 32 is started and the fan 31 is rotated when heating is completed. Since the inside of the furnace is in a vacuum or a reduced pressure state, the fan 31 reaches the required number of revolutions in a very short time (usually within 50 seconds). After the heat treatment object W is taken out of the heating chamber 1, the heat insulating lid 13 and the partition door 211 are closed, and the heat treatment object W is lifted by the lift 214 and transferred to the gas cooling space 20. When the heat treatment object W reaches the gas cooling space 20, the cooling gas is introduced and filled into the cooling chamber 2 through the cooling gas introduction system 5, and this is stirred and circulated to cool the heat treatment object W. The pressure of the cooling gas is 0.02 MPa or less if the cooling chamber 2 is a first type pressure vessel, and 0.1 MPa or less if it is certified as a high pressure vessel. When the cooling is completed, the cooling gas is exhausted to lower the internal pressure of the cooling chamber 2 to the atmospheric pressure, and the lift 214 is driven to lower the heat treatment object W to the vicinity of the carry-in / out port 212. Needless to say, when oil-cooling the heat treatment object W, the heat treatment object W is put into the oil tank 22.

  Therefore, in this embodiment, as shown in FIGS. 2 to 4, the cooling gas discharged from the stirrer 3 is guided by the first blowing duct 23 and the second blowing duct 24 and is arranged in the gas cooling space 20. The heat treatment object W is blown out from a plurality of directions. Specifically, the rotationally driven turbo fan 31 sucks the cooling gas from the thrust direction, that is, from below, and blows it in the radial direction, that is, the horizontal direction. The first blowout duct 23 and the second blowout duct 24 are opened around the fan 31 so as to swallow the cooling gas blown by the fan 31. In other words, the periphery of the fan 31 is divided into four areas, front, rear, left, and right, by the openings 231, 241 of the blowout ducts 23, 24. The cooling gas that flows is divided and flows into the second outlet duct 24.

  The 1st blowing duct 23 bears the role which blows off cooling gas with respect to the heat processing target object W from the downward direction. The first blowing duct 23 is bent downward from the opening 231 facing the left and right of the fan 31 and extends so as to wrap around the gas cooling space 20 along the left and right outer walls of the housing 21. The blowing part 232 which approaches is protruded inward. A plurality of nozzles 234 are provided on the upper surface of the blowing part 232, and the cooling gas flowing into the first blowing duct 23 is finally blown upward from the nozzle 234. Incidentally, it is possible to adjust the blowing position of the cooling gas by attaching a cap to some of the plurality of nozzles 234. In addition, since the blowing part 232 of the 1st blowing duct 23 interferes with the transfer path | route at the time of transferring the heat processing target object W to the gas cooling space 20 with the lift 214, at the time of transfer of the heat processing target object W, it does not become a hindrance to transfer. Must be retracted to position. Therefore, the blowing part 232 is configured to be movable. In the present embodiment, the base end side of the blowing part 232 is pivotally supported around the horizontal axis 233, and when the heat treatment object W is transferred, the tip side is turned downward to make the blowing part 232 substantially vertical. The posture can be taken and the transfer path can be opened. Then, after the heat treatment object W is transferred to the gas cooling space 20, the tip end side is rotated upward to bring the blowing part 232 into a substantially horizontal posture again so that the heat treatment object W faces from below. The rotation of the blowing part 232 is caused by the actuator 215.

  The 2nd blowing duct 24 bears the role which blows off cooling gas with respect to the heat processing target object W from upper direction. The second blowing duct 24 bends downward from the opening 241 facing the front and rear of the fan 31, and further extends the blowing part 242 that covers the gas cooling space 20 in the front-rear direction. . A plurality of nozzles 243 are also provided on the lower surface of the blowing part 242, and the cooling gas flowing into the second blowing duct 24 is finally blown downward from the nozzle 243.

  The cooling gas blown out from the upper and lower blowing portions 232 and 242 toward the heat treatment object W is sucked into the stirrer 3 again via the first reflux duct 25 or the second reflux duct 26. In the present embodiment, the recirculation ducts 25 and 26 allow the cooling gas to flow in a plurality of directions intersecting the blowing direction.

  The first reflux duct 25 plays a role of flowing the cooling gas blown from the top and bottom in the gas cooling space 20 to the right. The first reflux duct 25 closes the right side of the gas cooling space 20 and forms a reflux path having a substantially inverted L shape in front sectional view. A gas inlet 252 through which cooling gas flows is formed in a partition wall 251 that faces the gas cooling space 20 and separates the gas cooling space 20 and the first reflux duct 25. In the illustrated example, a plurality of gas inlets 252 are bored intermittently in the front-rear and top-bottom directions. In addition, the opening size of the gas inlet 252 near the periphery is set smaller than the opening size of the gas inlet 252 near the center. Further, a heat exchanger 27 (a cooling pipe or a fin thereof) is disposed substantially along the partition 251 in the front-rear direction and the upper-lower direction. In the illustrated example, the heat exchanger 27 is accommodated in the reflux ducts 25 and 26.

  The second reflux duct 26 plays a role of flowing the cooling gas blown from the top and bottom in the gas cooling space 20 to the left. The second reflux duct 26 is opposed to the first reflux duct 25 and forms a reflux path having a substantially inverted L shape in front sectional view while closing the left side of the gas cooling space 20. A partition wall 261 facing the gas cooling space 20 and separating the gas cooling space 20 and the second reflux duct 26 is provided with a plurality of gas inlets 262 intermittently in the front and rear and upper and lower sides, and close to the periphery. The opening size of the gas inlet 262 is set to be smaller than the opening size of the gas inlet 262 near the center. Further, the heat exchanger 27 is disposed along the partition wall 262 in the front-rear direction and the upper-lower direction.

  The first reflux duct 25 and the second reflux duct 26 are connected to each other at the upper end. The pipeline connecting both the reflux ducts 25 and 26 is located immediately below the fan 31 and immediately above the blowing portion of the second blowing duct 24 and opens toward the fan 31 of the stirrer 3 in the middle thereof. The cooling gas that has flowed into the reflux ducts 25 and 26 through the gas inlets 252 and 262 rises in the reflux ducts 25 and 26 while being cooled by the heat exchanger 27, and is a pipe line that connects both the reflux ducts 25 and 26. Is sucked into the fan 31.

  In addition to the above, in the present embodiment, the first adjustment mechanism 28 for adjusting the amount of the cooling gas sucked into the stirrer 3 via the first reflux duct 25 and the second reflux duct 26 are used. And a second adjusting mechanism 29 for adjusting the amount of the cooling gas sucked into the stirrer 3. The first adjusting mechanism 28 opens and closes the gas inlet 252 formed in the partition wall 251 on the first reflux duct 25 side by the shutter 281. The shutter 281 is a plate-like body having a plurality of through holes 282 formed corresponding to the gas inlets 252 and is supported so as to be movable substantially in parallel with the partition 251. In the present embodiment, the shutter 281 can be moved up and down, and the vertical movement is caused by the actuator 283. As shown in FIG. 5, when the shutter 281 is raised and the through hole 282 is positioned at the open position where it overlaps the gas inlet 252 of the partition wall 251, the gas inlet 252 is opened and the cooling gas is supplied to the first reflux. It can freely flow into the duct 25. On the other hand, as shown in FIG. 6, if the shutter 281 is lowered and the through hole 282 is positioned at the closed position deviating from the gas inlet 251, the gas inlet 252 is closed, and the first cooling gas is supplied. Inflow to the reflux duct 25 is suppressed. It is also possible to increase or decrease the amount of cooling gas flowing into the first reflux duct 25 by controlling the height position of the shutter 281 and adjusting the degree of overlap between the through hole 282 and the gas inlet 252. It is.

  The second adjustment mechanism 29 opens and closes the gas inlet 262 formed in the partition wall on the second reflux duct 26 side by the shutter 291. The second adjustment mechanism 29 has the same configuration as the first adjustment mechanism 28. That is, a plurality of through holes 292 corresponding to the gas flow ports 262 are formed in the shutter 291 so that the shutter 291 can be moved up and down substantially parallel to the partition wall 261 between the open position and the closed position. The vertical movement of the shutter 291 is caused by the actuator 293.

  In addition, the actuators 283 and 293 that drive the shutters 281 and 291 of the adjustment mechanisms 28 and 29 are individually controlled by a programmable controller (not shown). As a result, whether the cooling gas blown from the upper and lower blowing portions 232, 242 is caused to flow into the first reflux duct 25, the second reflux duct 26, or how much is to be introduced. Program control is possible. For example, when the heat treatment object W having a larger heat capacity in the right part than in the left part is cooled, the gas inlet 252 of the first reflux duct 25 is opened wide and the gas inlet 262 of the second reflux duct 26 is throttled. Or it obstruct | occludes and it cools by applying a lot of cooling gas to the right side part of the heat processing target object W. FIG. Alternatively, program control is performed so that the gas inlet 252 of the first reflux duct 25 and the gas inlet 262 of the second reflux duct 26 are alternately opened and closed in a predetermined time cycle. The time for opening the gas inlet 252 is set longer, the time for opening the gas inlet 262 of the second reflux duct 26 is set shorter, and the time for applying the cooling gas to the right portion of the heat treatment object W is set longer.

  According to the present embodiment, the stirrer 3 that sucks and discharges the cooling gas introduced into the gas cooling space 20, and the heat treatment object W arranged in the gas cooling space 20 by guiding the cooling gas discharged by the stirrer 3. A first blowing duct 23 to be blown out and a second blowing duct 24 to guide the cooling gas discharged from the same stirrer 3 and blow out toward the heat treatment object W from a direction different from the first blowing duct 23. Cooling given to the heat treatment object W by constituting the heat treatment furnace provided and blowing the cooling gas discharged from the stirrer 3 from each of the blow ducts 23 and 24 from a plurality of directions (especially, substantially opposite to each other). Since the effect is made uniform, it is possible to effectively eliminate the problem of local differences in the temperature drop of the heat treatment object W, and to obtain a uniform metallurgical effect and to reduce the distortion of the heat treatment object W. It can be avoided. Moreover, it is not necessary to equip the heat treatment furnace with a plurality of agitators 3.

  Further, the cooling gas blown toward the heat treatment object W is caused to flow into the stirrer 3 by flowing in the direction intersecting the cooling gas blowing direction by the first blowing duct 23 and the second blowing duct 24. The recirculation ducts 25 and 26 to be guided are provided, and the circulation of the cooling gas in the gas cooling space 20 can be facilitated to contribute to uniform cooling of the entire heat treatment object W.

  The fan 31 of the stirrer 3 sucks the cooling gas from a predetermined direction and blows it around the fan 31. By dividing the periphery of the fan 31 into a plurality of sections, the first blowing duct 23 and the second blowing duct 24 are used. The cooling gas that flows into each of these is divided, and the cooling gas discharged by the stirrer 3 can be divided appropriately.

  The first blowing duct 23 has a blowing portion in the vicinity of the transfer path when the heat treatment object W is transferred to the gas cooling space 20, and blows out the cooling gas substantially parallel to the transfer path. Therefore, it is made movable so that it can be retreated to a position where it does not interfere with the transfer path so that the blowout part does not interfere with the transfer path due to interference with the transfer path.

  The present invention is not limited to the embodiment described in detail above. For example, in the above-described embodiment, the shutters 281 and 291 in each of the adjustment mechanisms 28 and 29 are each formed as a single plate. However, as illustrated in FIG. It is conceivable that it can be driven independently (by 293). In the illustrated example, for convenience, three shutters 281 (291) are arranged in the front-rear direction, and each can be moved up and down independently. If such a structure is employ | adopted, the several gas inflow port 252 (262) can be opened and closed separately. That is, a large amount of the cooling gas blown from the upper and lower blowing portions 232 and 242 toward the heat treatment target W is allowed to flow into the front gas inlet 252 (262) or the rear gas inlet 252 (262). It is possible to control whether the gas flows into the intermediate gas inlet 252 (262). As a result, the flow of the cooling gas can be freely controlled, and the specific part of the heat treatment target W is intensively cooled, or the part of the heat treatment target W is cooled evenly by changing the flow path of the cooling gas every moment. Can be easily performed.

  In the said embodiment, although the heat exchanger 27 was arrange | positioned in the reflux ducts 25 and 26, arrangement | positioning of the heat exchanger 27 can be changed arbitrarily. The heat exchanger 27 may be disposed outside the reflux ducts 25 and 26, or may be disposed within the blowout ducts 23 and 24.

  In particular, the present invention is not prevented from being applied to a one-chamber heat treatment furnace in which the heating chamber and the cooling chamber are not separated, in other words, the heating space is directly used as the gas cooling space.

  Other specific configurations of the respective parts are not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The side sectional view showing the outline of the heat treatment furnace of one embodiment of the present invention. The principal part perspective view which shows the blowing duct and the recirculation | reflux duct. The principal part front sectional drawing which shows a blowing duct and a reflux duct. The principal part sectional side view which shows the blowing duct and the reflux duct. The figure explaining operation | movement of an adjustment mechanism. The figure explaining operation | movement of an adjustment mechanism. The figure explaining operation | movement of an adjustment mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Gas cooling space 23 ... 1st blowing duct 24 ... 2nd blowing duct 25 ... 1st reflux duct 26 ... 2nd reflux duct 28 ... 1st adjustment mechanism 29 ... 2nd adjustment mechanism 3 ... Stirrer

Claims (4)

A heat treatment furnace that heats an object to be heat treated, and then can perform gas cooling treatment, oil cooling treatment, or oil cooling treatment after gas cooling treatment,
A cooling chamber that extends in the vertical direction, has a gas cooling space for gas cooling in its upper region, and has an oil tank for oil cooling in its lower region;
A lift that lifts the heat treatment object and transfers it to the gas cooling space, or lowers the heat treatment object and transfers it to the oil tank;
A stirrer that sucks and discharges the cooling gas introduced into the gas cooling space;
A first blowing duct that guides the cooling gas discharged from the stirrer and blows it from below with respect to the heat treatment object disposed in the gas cooling space;
A second blowing duct that guides the cooling gas discharged from the same stirrer and blows out the heat treatment object disposed in the gas cooling space from above;
The first blowout duct has a blowout portion that blows the cooling gas upward,
The blowout portion can be displaced between a position facing the heat treatment object arranged in the gas cooling space from below and a position opening the transfer path in the vicinity of the transfer path when the heat treatment object is transferred by the lift. configured and,
In addition, a reflux duct for introducing the cooling gas blown toward the heat treatment object into the stirrer by flowing in the direction intersecting the blowing direction of the cooling gas by the first blowing duct and the second blowing duct. In addition,
A plurality of gas inlets through which the cooling gas flows from the gas cooling space into the reflux duct faces the gas cooling space, separates the gas cooling space and the reflux duct, and the first blowout duct and the second blowout duct. Perforated only in the partition wall facing the direction intersecting with the cooling gas blowing direction by
The plurality of gas inlets drilled in the partition wall are set so that the opening size is closer to the periphery but the opening size is closer to the center, and these are individually opened and closed by a plurality of shutters.
A heat treatment furnace characterized by that . The heat treatment furnace according to claim 1, wherein the blow-out portion is pivotally supported around a horizontal axis. The stirrer is provided at the upper end of the cooling chamber, and has a fan that sucks cooling gas from a predetermined direction and blows it around.
The cooling gas flowing into each of the first blowing duct and the second blowing duct is divided into a plurality of sections around the fan,
The first blowing duct is bent downward from an opening facing the left and right of the fan, extends downward so as to go around the gas cooling space, and projects the blowing part inward at the lower end thereof. The cooling gas is blown upward from the blowing part,
The second blowout duct is bent downward from the opening facing the front and rear of the fan, and further extends the blowout portion in the front-rear direction so as to cover the upper part of the gas cooling space from the blowout portion. The heat treatment furnace according to claim 1 or 2, wherein the cooling gas is blown downward. The stirrer includes a fan that sucks and discharges a cooling gas and a prime mover that rotationally drives the fan.
The prime mover is outside the housing of the cooling chamber, the drive shaft penetrates into the housing and is connected to the fan,
When gas-cooling the object to be heat-treated, start the prime mover in a stage where the furnace is in a vacuum or reduced pressure state, rotate the fan to reach the required number of revolutions, take out the object to be heat-treated from the heating chamber, and then enter the gas cooling space. The heat treatment furnace according to claim 1, 2 or 3 , wherein after being transferred to the heat treatment object, a cooling gas is introduced and filled in the cooling chamber, and this is stirred and circulated to cool the heat treatment object.

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