JP4280981B2 - Cooling gas air path switching device for vacuum heat treatment furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling gas air path switching device for a vacuum heat treatment furnace.
[0002]
[Prior art]
The vacuum heat treatment furnace is a heat treatment furnace that heats the product to be treated by refilling with an inert gas after decompressing the inside. The vacuum heat treatment furnace is a heat treatment that does not cause coloration due to moisture because the moisture in the furnace and the processed product after gasification is reduced in pressure after reheating and refilling with inert gas etc. can be completely removed. (Referred to as “bright heat treatment”).
[0003]
The gas-cooled vacuum heat treatment furnace has various advantages such as bright heat treatment, no decarburization and carburization, less deformation, and a good working environment. However, the initial gas-cooled vacuum heat treatment furnace has a disadvantage that the cooling rate is insufficient because it is a vacuum cooling type. Therefore, in order to increase the cooling rate, a high-speed circulating gas cooling system has been put into practical use.
[0004]
FIG. 7 is a configuration diagram of the high-speed circulating gas cooling furnace disclosed in Non-Patent Document 1. In this figure, 50 is a heat insulating material, 51 is a heater, 52 is an effective working area, 53 is a furnace body and a water cooling jacket, 54 is a heat exchanger, 55 is a turbo fan, 56 is a motor for a fan, 57 is a cooling door, 58 Is a hearth, 59 is a gas distributor, and 60 is a damper for switching the air path of the cooling gas.
[0005]
In addition, as shown in FIG. 8, the “gas circulation cooling promotion method in a vacuum furnace” of Patent Document 1 includes a heating chamber 66 surrounded by a heat insulating wall 67 in an airtight vacuum vessel 61 and is disposed in the heating chamber. The heated object 64 is heated in vacuum by the heater 62, and the cooler 62 and the fan 63 are provided in the vacuum vessel 61, and the non-oxidizing gas supplied into the vacuum vessel is cooled by the cooler 62. In a vacuum furnace in which gas is circulated into the heating chamber 66 through openings 68 and 69 provided on the opposing heat insulating wall 67 surface of the heating chamber 66 by the rotation of the fan 63 to forcibly circulate and cool the object to be heated 64. The heat-resistant cylindrical hood 65 formed in a divergent shape surrounds the object to be heated 64 placed in the heating chamber 66 at an appropriate interval, and both ends thereof are relative to the openings 68 and 69. Do And sea urchin disposed is obtained so as to circulate the non-oxidizing gas into the heating chamber 66. In this figure, reference numeral 70 denotes a damper for switching the air path of the cooling gas.
[0006]
[Non-Patent Document 1]
Katsuhiro Yamazaki, Vacuum heat treatment of metal materials (2), Heat treatment No.30, No.2, April 1990 [Patent Document 1]
Japanese Patent Laid-Open No. 5-230528
[Problems to be solved by the invention]
In the high-speed circulating gas cooling furnace described in Non-Patent Document 1 and Patent Document 1 described above, a damper device is normally used as a mechanism for switching an upward and downward air path. However, when the upper and lower damper devices are air path switching mechanisms, there are the following problems.
(1) The damper device has a large load fluctuation due to wind pressure passing at a high speed depending on its opening / closing position. Therefore, in the case of high-pressure gas, it is difficult to move smoothly due to the influence of wind pressure in the damper system.
(2) In the damper device, the opening / closing angle and the opening area are not proportional. Therefore, when switching between the upper and lower drive devices, it is difficult to balance the opening area, the difference between the opening area of the suction port and the discharge port, or the variation becomes large, the amount of cooling gas varies, Stable gas cooling is difficult.
(3) There are a plurality of damper devices at the top and bottom, a plurality of drive devices are required, and the structure becomes complicated.
(4) The opening area is limited by the damper device up and down and is smaller than the furnace body area.
[0008]
The present invention has been developed to solve the above-described problems. In other words, the object of the present invention is to be able to smoothly switch the air path without being affected by the wind pressure, to prevent fluctuations in the opening area and differences in the opening area between the suction port and the discharge port, and stable gas cooling is possible. An object of the present invention is to provide a cooling gas air path switching device for a vacuum heat treatment furnace that has a simple structure, can be switched by a single drive device, and can secure a large opening area.
[0009]
[Means for Solving the Problems]
According to the present invention, the apparatus includes a cooling chamber that surrounds a cooling region in which an object to be processed is placed, and a gas cooling circulation device that cools and circulates gas passing through the cooling chamber, and pressurizes the heated object to be processed. A cooling gas air path switching device for a vacuum heat treatment furnace that cools with a circulating gas, and is driven to rotate along a fixed partition plate that partitions between the cooling chamber and the gas cooling circulation device, and the surface of the fixed partition plate The fixed partition plate has an opening penetrating almost the entire surface, and the rotary partition plate has a suction opening and a discharge opening partially communicating with the suction port and the discharge port of the gas cooling circulation device. Thus, there is provided a cooling gas air path switching device for a vacuum heat treatment furnace, wherein the direction of the gas passing through the cooling chamber is alternately switched.
[0010]
According to the above-described configuration of the present invention, the direction of the gas passing through the cooling chamber is alternately changed only by rotationally driving the rotating partition plate along the surface of the fixed partition plate that partitions the cooling chamber and the gas cooling circulation device. Since the switching is performed by the rotation drive in which the rotating partition plate moves vertically with respect to the flow direction, the air path can be smoothly switched even if it is a high-pressure gas (a gas body having a high density) hardly affected by the wind pressure.
In addition, since the rotary partition plate has a suction opening and a discharge opening partially communicating with the suction port and the discharge port of the gas cooling and circulation device, fluctuations in the opening area and a difference in the opening area between the suction port and the discharge port are unlikely to occur. Stable gas cooling is possible. In addition, the structure is simple and can be switched by a single driving device, and a large opening area can be secured.
[0011]
According to a first preferred embodiment of the present invention, the cooling chamber has a gas flow path that passes through the inside in the vertical direction, and when the gas flows downward in the cooling chamber, the suction opening is below the cooling chamber. And the discharge opening communicates only above the cooling chamber, and when the gas flows upward in the cooling chamber, the suction opening communicates only above the cooling chamber and the discharge opening communicates only below the cooling chamber. The opening position is set so as to.
[0012]
With this configuration, out of the furnace body area A partitioning between the cooling chamber and the gas cooling circulation device, ½ is used as the suction port and the discharge port of the gas cooling circulation device, and among the suction port and the discharge port, 1 By setting / 2 each downward and upward, the suction opening and the discharge opening can be set to about ¼ of the furnace body area A. Therefore, the air passage area can be increased compared to the conventional case, the gas passage flow rate can be reduced, and the pressure loss can be reduced.
Also, between the fixed partition plate and the gas cooling circulation device, the entire inner surface communicates with the suction port of the gas cooling circulation device, and the entire outer surface communicates with the discharge port of the gas cooling circulation device. By taking a sufficient gap, it is possible to wrap around the opposite surface even if only one side is open, and the entire heat exchanger can be used effectively.
[0013]
According to a second preferred embodiment of the present invention, when the gas flows in the vertical direction in the cooling chamber, the suction opening selectively communicates only with the lower side or only the upper side of the cooling chamber, and the discharge opening has the upper side of the cooling chamber. When the gas flows horizontally in the cooling chamber, the suction opening selectively communicates with only one side of the cooling chamber and the discharge opening is opposite to the cooling chamber. The opening position is set so as to selectively communicate with only one side.
[0014]
With this configuration, the direction of the gas passing through the cooling chamber can be freely adjusted in the vertical and horizontal directions by simply rotating the rotating partition plate along the surface of the fixed partition plate that partitions the cooling chamber and the gas cooling circulation device. You can switch to
[0015]
The gas cooling / circulating device includes a cooling fan that is installed adjacent to the cooling chamber and sucks and pressurizes the gas that has passed through the cooling chamber, and a heat exchanger that indirectly cools the gas discharged from the cooling fan.
[0016]
With this configuration, between the fixed partition plate and the gas cooling circulation device, the entire inner surface communicates with the suction port of the gas cooling circulation device, and the entire outer surface communicates with the discharge port of the gas cooling circulation device. By taking a sufficient clearance between the suction ports, even if only one side is open, it is possible to wrap around the opposite side, and the entire heat exchanger can be used effectively.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.
[0018]
FIG. 1 is an overall configuration diagram of a vacuum heat treatment furnace including a cooling gas air path switching device according to a first embodiment of the present invention. In this figure, this vacuum heat treatment furnace is a multi-chamber heat treatment furnace provided with a vacuum heating furnace 10, a gas cooling furnace 20, and a moving device 30.
The vacuum heating furnace 10 has a function of heating the workpiece 1 under reduced pressure. The gas cooling furnace 20 has a function of cooling the heated workpiece 1 with the pressurized circulating gas 2. The moving device 30 has a function of moving the workpiece 1 between the vacuum heating furnace 10 and the gas cooling furnace 20.
[0019]
The vacuum heating furnace 10 includes a vacuum vessel 11 in which the inside is evacuated, a heating chamber 12 that houses the article 1 to be processed, a front door 13 for taking the article 1 into and out of the heating chamber, heating It comprises a rear door 14 that closes an opening for moving the object to be processed 1 in the room, a mounting table 15 on which the object 1 to be processed can be horizontally moved back and forth, a heater 16 for heating the object 1 to be processed, and the like. With this configuration, the inside of the vacuum vessel 11 can be decompressed to a vacuum, and the workpiece 1 can be heated to a predetermined temperature by the heater 16.
[0020]
The moving device 30 includes a conveying rod 32 that horizontally moves the article 1 to be processed between the vacuum heating furnace 10 and the gas cooling furnace 20, a rear door elevating device 33 that elevates and lowers the rear door 14, and a front door 13. A front door lifting / lowering device 34 that opens and closes and opens / closes and an intermediate door lifting / lowering device 34 that lifts and lowers and opens / closes the intermediate heat insulating door 21a of the gas cooling furnace 20 are provided. In this example, the transport bar 32 is a rack and pinion drive, the rear door lifting device 33 is a linear cylinder, and the front door lifting device 34 and the intermediate door lifting device 34 are hoisting machines. However, the present invention is not limited to this, The drive mechanism may be used. With this configuration, the article 1 to be processed is moved horizontally between the vacuum heating furnace 10 and the gas cooling furnace 20 by the transfer rod 32 with the rear door 14, the front door 13 and the intermediate heat insulating door 21a opened. Can do.
[0021]
2 is a partially enlarged view of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. As shown in FIGS. 1 to 3, the gas cooling furnace 20 includes a vacuum vessel 21, a cooling chamber 22, a gas cooling circulation device 24, a cooling gas air path switching device 40, and a rectifier 28.
The vacuum vessel 21 accommodates an intermediate heat insulating door 21 a provided to face the front door 13 of the vacuum heating furnace 10, a cylindrical vessel body 21 b that accommodates the article 1 to be processed, and a gas cooling and circulation device 24. It consists of a circulation part 21c, a clutch ring 21e that can be opened and closed in an airtight manner, and a clamp 21d. With this configuration, the workpiece 1 can be stored directly in the container body 21b by opening the clutch ring 21e and retracting the circulation part 21c to the right in FIG. 1 from the container body 21b. Further, the intermediate heat insulating door 21a and the circulating portion 21c are hermetically connected to the container body portion 21b by the clutch ring 21e and the clamp 21d, and a pressurized cooling gas (argon, helium, nitrogen, etc.) is supplied to the inside. Pressurized gas can be used for cooling.
[0022]
The cooling chamber 22 is provided adjacent to the vacuum heating furnace 10 in the central portion of the container body portion 21b. The vacuum heating furnace side of the cooling chamber 22 is partitioned by an intermediate heat insulating door 21a, and the gas cooling circulation device and both side surfaces are partitioned by airtight heat insulating walls 22a and 22b. The cooling chamber 22 is open at the upper and lower ends, and forms a gas flow path having a constant cross section in the vertical direction inside thereof. The inside of the cooling chamber 22 is a cooling region, and the article to be processed 1 is a small metal part such as a moving blade, a stationary blade, or a bolt of a jet engine, and is accommodated in a tray or a basket. And rests on a mounting table 23 having air permeability.
The mounting table 23 is installed at the same height as the mounting table 15 of the vacuum heating furnace 10 and can freely move on the built-in roller. Further, as shown in FIG. 3, a horizontal partition plate 22 c is provided between the container body 21 b and the heat insulating wall 22 b to partition the gas located above and below the cooling chamber 22 in an airtight manner.
[0023]
The gas cooling circulation device 24 is installed adjacent to the cooling chamber 22 and sucks and pressurizes the gas that has passed through the cooling chamber 22, and a heat exchanger 25 that indirectly cools the gas discharged from the cooling fan. It consists of. The cooling fan 24a is rotationally driven by a cooling fan motor 24b attached to the circulation part 21c of the vacuum vessel 21, and sucks gas from the central part and discharges it from the outer peripheral part. The heat exchanger 25 is, for example, a cooling fin tube that is water-cooled inside. With this configuration, the circulating gas discharged from the outer peripheral portion can be cooled by the heat exchanger 25, and the gas passing through the cooling chamber 22 in the vertical direction can be cooled and circulated.
[0024]
The rectifier 28 is provided above and below the upper and lower ends of the cooling chamber 22, and has a function of making the velocity distribution of the gas passing through the cooling chamber 22 uniform.
[0025]
In addition, the high-speed circulating gas-cooled vacuum heat treatment furnace of the present invention is provided with auxiliary distribution mechanisms 29 (for example, blow-in plates) that guide the direction of gas flow flowing in and out of the cooling chamber above and below the cooling chamber 22. Even when the area is large, the direction of the gas flow toward a plurality of locations is optimized to improve the flow uniformity.
[0026]
FIG. 4 is an enlarged view of a portion B in FIG. As shown in this figure, the cooling gas air path switching device 40 of the present invention comprises a fixed partition plate 42, a rotary partition plate 44, and a rotary drive device 46.
The fixed partition plate 42 partitions between the cooling chamber 22 and the gas cooling circulation device 24 and blocks the space therebetween. In this example, the rotary partition plate 44 is rotationally driven along the surface of the fixed partition plate 42 by the rotary drive device 46 coaxially with the cooling fan 24a. In this example, the rotation driving device 46 is a rack and a pinion, and the rotation partition plate 44 is rotated 1/2 times so that the top and bottom are reversed. A pneumatic or hydraulic cylinder or the like can be used for linear movement of the rack. Further, the present invention is not limited to this configuration, and other known driving devices can also be used.
[0027]
A bearing box 43 containing a bearing 43 a is provided at the center of the fixed partition plate 42. The bearing box 43 is supported from the circulating portion 21c of the vacuum vessel 21 by a support frame 43b. The rotary partition plate 44 has a rotary shaft 45 with a key rotating around the center, and the rotary shaft 45 is supported coaxially with the cooling fan 24a by a bearing 43a. A compression spring 47 is sandwiched in a compressed state between the shaft end portion (left end and support plate 45a in the figure) of the rotation shaft 45 and the rotation partition plate 44, and always urges the rotation partition plate 44 toward the rotation partition plate 44. In addition, the gap between them is reduced. For this reason, if it adds, a function will improve.
A sealing material 48 is attached to the end face of the horizontal partition plate 22c and the end face of the fixed partition plate 42 to seal the gap between the rotary partition plate 44 and the rotary partition plate 44. Yes. The seal material 48 is made of, for example, lead brass, graphite, or the like with less friction, reducing leakage and smoothing movement.
[0028]
FIG. 5 is a cross-sectional view taken along the line CC of FIG. In this figure, (A) is a sectional view taken along the line CC, that is, a front view of the rotating partition plate 44, and (B) is a sectional view from which the rotating partition plate 44 is removed, that is, a front view of the fixed partition plate 42. is there.
[0029]
The fixed partition plate 42 has an opening 42a penetrating substantially the entire surface. That is, in this example, it is composed of an elongated radiating portion 42b extending in the radial direction at the same position as the support frame 43b, and a thin ring-shaped circular portion 42c at the outermost periphery, the central portion, and the intermediate portion. In addition, the bearing box 43 mentioned above is attached to the center circular part 42c in this figure. Note that the position of the opening 42a is not limited to this example, and is preferably set as wide as possible.
[0030]
The rotary partition plate 44 has a suction opening 44a and a discharge opening 44b partially communicating with the suction port and the discharge port of the gas cooling circulation device.
In the first embodiment of FIG. 5, the cooling chamber 22 has a gas flow path that passes through the inside in the vertical direction, and when the gas flows downward in the cooling chamber 22, the suction opening 44 a is only below the cooling chamber. When the gas flows upward in the cooling chamber 44, the suction opening 44a communicates only above the cooling chamber, and the discharge opening 44b communicates with the cooling chamber. The opening position is set so as to communicate only with the lower part.
In this example, the suction opening 44a has a substantially ½ circular shape, and the discharge opening 44b has a substantially ½ fan shape, which are provided on opposite sides of the horizontal axis (the aforementioned horizontal partition plate 22c). Yes.
[0031]
With this configuration, out of the furnace body area A partitioning between the cooling chamber 22 and the gas cooling circulation device 24, 1/2 is used as the suction port and the discharge port of the gas cooling circulation device, and further, out of the suction port and the discharge port. , 1/2 each downward and upward, the suction opening 44a and the discharge opening 44b can be set to about 1/4 of the furnace body area A. Therefore, the air passage area can be increased, the gas flow velocity can be reduced, and the pressure loss can be reduced.
Further, between the fixed partition plate 42 and the gas cooling circulation device 24, the entire inner surface communicates with the suction port of the gas cooling circulation device, and the entire outer surface communicates with the discharge port of the gas cooling circulation device. By taking a sufficient clearance between the suction ports, even if only one side is open, it is possible to wrap around the opposite side, and the entire heat exchanger can be used effectively.
[0032]
According to the above-described configuration of the present invention, the direction of the gas passing through the cooling chamber is alternated only by rotationally driving the rotating partition plate along the surface of the fixed partition plate that partitions the cooling chamber and the gas cooling circulation device. Therefore, even if it is a high-pressure gas (a high-density gas body), the air path can be smoothly switched without being affected by the wind pressure. .
In addition, since the rotary partition plate has a suction opening and a discharge opening partially communicating with the suction port and the discharge port of the gas cooling and circulation device, fluctuations in the opening area and a difference in the opening area between the suction port and the discharge port are unlikely to occur. Stable gas cooling is possible. In addition, the structure is simple and can be switched by a single driving device, and a large opening area can be secured.
In addition, although embodiment was shown about the gas flow of an upstream / downstream so far, it can also be set as the switching mechanism of a right-and-left flow by rotating a rotation partition plate 90 degrees and attaching the rectifier of a cooling chamber to a side surface (left and right). it can.
[0033]
FIG. 6 is a cross-sectional view similar to FIG. 5 showing the second embodiment of the present invention. In this figure, (A) is a sectional view taken along the line CC, that is, a front view of the rotating partition plate 44, and (B) is a sectional view from which the rotating partition plate 44 is removed, that is, a front view of the fixed partition plate 42. is there.
This second embodiment can handle both when the gas flows in the cooling chamber in the vertical direction (upstream and downstream) and when the gas flows in the cooling chamber in the horizontal direction (horizontal flow).
That is, in this example, the suction opening 44a has a substantially ¼ circular shape, and the discharge opening 44b has a substantially ¼ fan shape, which are provided on opposite sides of the horizontal axis (the aforementioned horizontal partition plate 22c). Yes.
[0034]
In the second embodiment, when the gas flows in the vertical direction in the cooling chamber 22, the suction opening 44a selectively communicates only with the lower side or only the upper side of the cooling chamber 22 and the discharge opening 44b, as in FIG. Are selectively communicated only with the upper or lower side of the cooling chamber. As shown in FIG. 6A, when the gas flows in the cooling chamber 22 in the horizontal direction, the suction opening 44a is selectively communicated with only one side of the cooling chamber, and the discharge opening 44b is cooled. The opening position is set so as to selectively communicate with only one side opposite to the chamber.
[0035]
With this configuration, the direction of the gas passing through the cooling chamber can be freely adjusted in the vertical and horizontal directions by simply rotating the rotating partition plate along the surface of the fixed partition plate that partitions the cooling chamber and the gas cooling circulation device. You can switch to
[0036]
In addition, this invention is not limited to the Example mentioned above, Of course, it can change freely, unless it deviates from the summary of this invention. For example, the present invention is not limited to an apparatus in which a heating chamber and a cooling chamber are separated, and can be used in a single chamber furnace that can perform heating and cooling in one chamber.
[0037]
【The invention's effect】
As described above, the cooling gas airflow switching device of the vacuum heat treatment furnace of the present invention can be smoothly switched without being affected by the wind pressure, and the opening area varies or the opening area difference between the suction port and the discharge port. Therefore, stable gas cooling is possible, the structure is simple, switching is possible with a single driving device, and a large opening area can be secured.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a vacuum heat treatment furnace provided with a cooling gas air path switching device according to a first embodiment of the present invention.
FIG. 2 is a partially enlarged view of FIG.
3 is a cross-sectional view taken along line AA in FIG.
4 is an enlarged view of a portion B in FIG. 2. FIG.
5 is a cross-sectional view taken along the line CC in FIG.
FIG. 6 is a cross-sectional view similar to FIG. 5 showing a second embodiment of the present invention.
7 is a configuration diagram of a high-speed circulating gas cooling furnace disclosed in Non-Patent Document 1. FIG.
FIG. 8 is a configuration diagram of “a gas circulation cooling promotion method in a vacuum furnace” disclosed in Patent Document 1;
[Explanation of symbols]
1 Product to be treated, 2 Circulating gas,
10 vacuum heating furnace, 11 vacuum vessel, 12 heating chamber,
13 front door, 14 rear door, 15 mounting table, 16 heater,
20 gas-cooled furnace, 21 vacuum vessel,
21a Intermediate heat insulation door, 21b Container body,
21c Circulation part, 21e Clutch ring, 21d Clamp 22 Cooling chamber, 22a, 22b Thermal insulation wall, 22c Horizontal partition plate,
24 gas cooling circulation device, 24a cooling fan,
24b cooling fan motor, 25 heat exchanger,
28 rectifiers, 29 auxiliary distribution mechanisms, 30 moving devices, 32 transport bars,
33 Rear door lifting device, 34 Front door lifting device,
34 Intermediate door lifting device,
40 Cooling gas air path switching device,
42 fixed partition plate, 42a opening,
43 bearing box, 43a bearing, 43b support frame,
44 rotating partition plate, 44a suction opening, 44b discharge opening,
45 rotation shaft, 46 rotation drive device (rack and pinion),
47 Compression spring, 48 Sealing material

Claims (4)

A cooling chamber that surrounds a cooling region in which the article to be treated is placed is provided, and a gas cooling circulation device that cools and circulates the gas passing through the cooling chamber, and cools the heated article to be treated with a pressurized circulation gas. A cooling gas air path switching device for a vacuum heat treatment furnace,
A fixed partition plate that partitions between the cooling chamber and the gas cooling circulation device, and a rotary partition plate that is driven to rotate along the surface of the fixed partition plate;
The fixed partition plate has an opening penetrating almost the entire surface, and the rotary partition plate has a suction opening and a discharge opening partially communicating with the suction port and the discharge port of the gas cooling circulation device, thereby passing through the cooling chamber. A cooling gas air path switching device for a vacuum heat treatment furnace, wherein the direction of the gas to be switched is switched alternately. The cooling chamber has a gas flow path passing through the inside in the vertical direction,
When the gas flows downward in the cooling chamber, the suction opening communicates only with the lower portion of the cooling chamber and the discharge opening communicates only with the upper portion of the cooling chamber,
The opening position is set such that when the gas flows upward in the cooling chamber, the suction opening communicates only with the upper portion of the cooling chamber and the discharge opening communicates only with the lower portion of the cooling chamber. Item 2. A cooling gas air path switching device for a vacuum heat treatment furnace according to Item 1. When the gas flows in the vertical direction in the cooling chamber, the suction opening selectively communicates only with the lower side or the upper side of the cooling chamber and the discharge opening selectively communicates only with the upper side or only the lower side of the cooling chamber,
When the gas flows in the cooling chamber in the horizontal direction, the suction opening is selectively communicated with only one side of the cooling chamber, and the discharge opening is selectively communicated with only one side opposite to the cooling chamber. 2. The cooling gas air path switching device for a vacuum heat treatment furnace according to claim 1, wherein the position is set. The gas cooling / circulating device comprises a cooling fan that is installed adjacent to the cooling chamber and sucks and pressurizes the gas that has passed through the cooling chamber, and a heat exchanger that indirectly cools the gas discharged from the cooling fan. The apparatus for switching a cooling gas air path of a vacuum heat treatment furnace according to claim 1.

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