Rotary heat treatment furnace

Abstract

To provide a rotary type heat treatment furnace having an excellent heat treatment effect.SOLUTION: A rotary type heat treatment furnace 100 includes: an approximately cylindrical furnace body 110; an accommodation rotating body 120 that has an approximately doughnut shape in plan view and in which heated object accommodation chambers 121 are provided in a plurality of stages SG equally divided in the circumferential direction and provided on an outer peripheral part to form a multistage shape; an inner cylinder part 130 having a vertical cylindrical hollow shape; a circulation fan 140 disposed above the inner cylinder part 130 and sending gas sucked from the lower side to the radial direction; and a heater 129. The accommodation chamber 121 is sent from a temperature rise zone 120a to a soaking zone 120b. An inner diameter of a furnace wall 111 of the furnace body 110 differs between the soaking zone 120b and the temperature rise zone 120a. The inner diameter Ra of the temperature rise zone 120a is set larger than the inner diameter Rb of the soaking zone 120b, and a flow passage cross sectional area from the upper side to the lower side of the temperature rise zone 120a is set larger than that from the upper side to the lower side of the soaking zone 120b.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotary heat treatment furnace that circulates hot air to heat-treat a workpiece such as an aluminum alloy.

Background Art

[0002] Conventionally, for example, as shown in FIGS. and, a hot air circulation type rotary heat treatment furnace 1 having a heating zone 20a and a soaking zone 20b is used to heat-treat a workpiece such as an aluminum alloy (see, for example, Patent Document 1). This rotary heat treatment furnace 1 includes a furnace body 10, a storage rotating body 20, an inner cylinder portion 30, a fan 40, a first hot air guide body 50, and a second hot air guide body 60.

[0003] The furnace body 10 has a substantially cylindrical shape, and is provided with a rotating device 24 for rotating the storage rotating body 20, an input device 25 for inputting a workpiece into the storage rotating body 20, and a take-out device 26 for taking out the workpiece from the storage rotating body 20. In addition, at the upper part of the furnace body , a gas burner 23 is provided at the upper end of the central space portion 20c, directly below the fan 40, for injecting flames and heating that portion. Further, at the bottom of the furnace body 10, a guide member 11 having a substantially mountain-shaped cross section for guiding hot air upward is provided.

[0004] The storage rotating body 20 is provided inside the furnace body 10 so as to rotate counterclockwise by the rotating device 24, has a substantially donut shape in plan view with a central space portion 20c, and a plurality of storage chambers 21 for storing workpieces along the circumferential direction are provided in multiple stages on its outer peripheral portion. The storage rotating body 20 forms a heating zone 20a composed of a plurality of storage chambers 21 provided in multiple stages, and a soaking zone 20b also composed of a plurality of storage chambers 21 provided in multiple stages. The inner cylinder portion 30 has a vertical, hollow cylindrical shape and is positioned in close proximity to the storage rotating body 20 in a non-contact manner, and is fixed concentrically in its central space 20c. A guide tube 31 is provided at the upper end of the inner cylinder portion 30 for guiding hot air to the fan 40.

[0005] The fan 40 is a single centrifugal fan positioned above the inner cylinder 30, configured to draw in hot air from below and expel it radially by centrifugal force. The hot air discharged radially is sent from top to bottom between the furnace body 10 and the inner cylinder 30 via the first and second hot air guides 50 and 60. The hot air that reaches the bottom of the inner cylinder 30 is then sent from bottom to top through the interior of the inner cylinder 30 by the suction force of the centrifugal fan 40 and returned to the centrifugal fan 40, thereby ensuring continuous circulation of the hot air.

[0006] With this type of rotary heat treatment furnace 1, the fan 40 is positioned above the inner cylinder 30 fixed to the central space 20c of the storage rotating body 20. Therefore, compared to, for example, a furnace where the fan 40 is positioned to the side, the installation area of ​​the rotary heat treatment furnace 1 can be reduced. Furthermore, since the fan 40 is a centrifugal fan and hot air is sent from above to below through the space between the furnace body 10 and the inner cylinder 30, the distance traveled to the workpiece stored in the storage unit 20 is shortened compared to, for example, a system that sends hot air from below to above. As a result, a temperature drop before the hot air reaches the workpiece can be prevented, and the object to be heated (workpiece) can be effectively heat-treated. Furthermore, since a first hot air guide body 50 is provided extending upward toward the heating zone 20a side formed on the storage rotating body 20 from the centrifugal fan 40, and a second hot air guide body 60 is provided extending upward toward the uniform zone 20b side, the effect of being able to reliably apply hot air to the workpiece can be obtained. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-8996 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, in the rotary heat treatment furnace 1 described in Patent Document 1, it is necessary to set up one first hot air guide body 50 and three second hot air guide bodies 60 in order to heat the hot air. On the other hand, the inventors came to the idea that it would be unnecessary to actively supply heat to the uniform zone 20b, and that it would suffice to simply keep the object to be heated (workpiece) warm, while conversely, it would be beneficial to actively supply heat to the heating zone 20a.

[0009] Therefore, the object of the present invention is to provide a rotary heat treatment furnace with even better heat treatment performance. [Means for solving the problem]

[0010] To achieve the above objective, the rotary heat treatment furnace (100) of the present invention comprises a substantially cylindrical furnace body (110) and A storage rotating body (120) is provided to be rotatably mounted inside the furnace body (110), and has a central space (120c) and is roughly donut-shaped in plan view, with multiple stages (SG) evenly divided along the circumferential direction on the outer circumference and arranged in multiple upper and lower stages, each of which is provided with a storage chamber (121) for storing the object to be heated (workpiece). A vertical cylindrical hollow inner cylinder portion (130) is fixed to the central space portion (120c) of the retractable rotating body (120) in a non-contact state, A circulating fan (140) is positioned above the inner cylinder (130) and blows air drawn in from below in the radial direction, The furnace body (110) is provided with a heating device (129) for heating the gas inside, The storage chamber (121) on the stage (SG) provided on the storage rotating body (120) is sent from the heating zone (120a) formed along the circumferential direction to the soaking zone (120b), where there are more stages (SG) than in the heating zone (120a). A rotary heat treatment furnace (100) is provided in which gas blown radially via the circulation fan (140) is sent from top to bottom through the furnace body (110) and the storage rotating body (120), circulated by passing it back through the inside of the inner cylinder (130) from bottom to top, and the gas is heated via the heating device (129) during the circulation process, The inner diameter of the furnace wall (111) of the furnace body (110) differs between the soaking zone (120b) and the heating zone (120a), with the inner diameter (Ra) of the heating zone (120a) being larger than the inner diameter (Rb) of the soaking zone (120b), thereby making the cross-sectional area of ​​the flow path from above to below the heating zone (120a) larger than the cross-sectional area of ​​the flow path from above to below the soaking zone (120b).

[0011] Furthermore, the present invention is characterized in that in the soaking zone (120b), a cover body (128) extending vertically is provided between the furnace wall (111) of the furnace body (110) and the cover body (128), allowing gas blown radially via the circulation fan (140) to pass between the furnace wall (111) of the furnace body (110) and the cover body (128), but preventing it from entering the storage chamber (121).

[0012] Furthermore, the present invention is characterized in that a hole is made in a part of the cover body (128) to allow some of the gas to enter the storage chamber (121).

[0013] Note that the gas is not limited to air; other atmospheric gases may also be used.

[0014] Here, the symbols in parentheses indicate the corresponding elements or items shown in the drawings and the embodiments for carrying out the invention described later. [Effects of the Invention]

[0015] According to the rotary heat treatment furnace of the present invention, since the circulation fan is positioned above the inner cylinder fixed in the central space of the storage rotating body, the installation area of ​​the rotary heat treatment furnace can be reduced. Then, regarding the inner diameter of the furnace wall of the furnace body, the inner diameter of the heating-up zone is made larger than the inner diameter of the soaking zone, and the cross-sectional area of the flow path from the upper part to the lower part of the heating-up zone is made larger than the cross-sectional area of the flow path from the upper part to the lower part of the soaking zone. Therefore, the amount of hot air (heated gas) sent to the heating-up zone side can be increased, and heat can be efficiently applied to the workpiece. In this way, by simply changing the shape of the furnace wall, the amount of hot air sent to the heating-up zone side can be easily increased as compared with the amount of hot air sent to the soaking zone side.

[0016] Also, according to the present invention, in the soaking zone, a cover body extending vertically is provided between the furnace wall of the furnace body, and a gas blown radially through a circulation fan is passed between the furnace wall of the furnace body and the cover body so as not to enter the storage chamber. Therefore, unlike the heating-up zone, hot air is not actively supplied, and only heat insulation is surely performed by compensating for the amount of heat dissipated from the furnace wall.

[0017] It is also possible to make a part of the cover body have holes so that a part of the gas enters the storage chamber. According to this, more precise temperature control can be performed.

Brief Description of Drawings

[0018] [Figure 1] It is a schematic plan view showing a rotary heat treatment furnace according to an embodiment of the present invention. [Figure 2] It is a schematic front cross-sectional view of the rotary heat treatment furnace shown in FIG. 1. [Figure 3] It is a perspective view showing a main part of the rotary heat treatment furnace shown in FIG. 1. [Figure 4] It is a schematic plan cross-sectional view showing the rotary heat treatment furnace shown in FIG. 1. [Figure 5] It is a schematic plan cross-sectional view showing a rotary heat treatment furnace according to a conventional example. [Figure 6] It is a schematic front cross-sectional view of the rotary heat treatment furnace shown in FIG. 5. [Figure 7] It is a schematic plan cross-sectional view showing another rotary heat treatment furnace according to an embodiment of the present invention. [Modes for carrying out the invention]

[0019] An embodiment of the rotary heat treatment furnace of the present invention will be described with reference to Figures 1 to 4. Figure 1 shows a schematic plan cross-section of the rotary heat treatment furnace, Figure 2 shows a schematic front cross-section of the rotary heat treatment furnace, Figure 3 shows the main part of the rotary heat treatment furnace, and Figure 4 shows a schematic plan cross-section of the rotary heat treatment furnace.

[0020] The rotary heat treatment furnace 100 according to this embodiment comprises a furnace body 110, a storage rotating body 120, an inner cylinder 130, and a fan 140.

[0021] The furnace body 110 is roughly cylindrical and is fixed to the floor of the heat treatment facility. The furnace body 110 is fitted with a rotating device 124 for rotating the storage rotating body 120, a loading device 125 for loading the workpiece into the storage rotating body 120, and a removal device 126 for removing the workpiece from the storage rotating body 120. Furthermore, multiple heating heaters 129 are provided at the top of the furnace body 110 as a heating device that heats the gas inside the furnace (in this case, air) to produce hot air. In this embodiment, air is heated to produce hot air which is then circulated inside the furnace, but other atmospheric gases can be used as the gas, not just air.

[0022] The storage rotating body 120 is installed inside the furnace body 110 so as to rotate clockwise (right-handed in Figure 1) by a rotating device 124, and has a roughly donut shape in plan view with a central space 120c. Furthermore, as shown in Figure 4, multiple stages SG (in this case, nine) are formed on the outer circumference of the storage rotating body 120, evenly spaced along the circumferential direction, and storage chambers 121 for storing the workpieces to be heated are provided in multiple stages SG, as shown in Figure 2, and each stage SG is provided with a storage chamber 121 for storing the workpieces to be heated. Although not particularly limited, in this case, one storage chamber 121 is provided in each stage SG.

[0023] In the circumferential direction of the storage rotating body 120, a heating zone 120a and a soaking zone 120b are formed along the circumferential direction. The heating zone 120a rapidly heats the workpieces to be heated when they are fed in from the feeding device 125, while the soaking zone 120b maintains the temperature of the heated workpieces. The number of stages SG in the soaking zone 120b is greater than the number of stages SG in the heating zone 120a, and the area occupied by the soaking zone 120b is larger than the area occupied by the heating zone 120a. The storage chamber 121 on the stage SG provided on the storage rotating body 120 is sent to the heating zone 120a formed along the circumferential direction as the storage rotating body 120 rotates, and then sent to the soaking zone 120b.

[0024] As described above, the furnace body 110 is roughly cylindrical, but as shown in Figures 1 to 4, the inner diameter of the furnace wall 111 of the furnace body 110 differs between the soaking zone 120b and the heating zone 120a. The inner diameter Ra of the heating zone 120a is made larger than the inner diameter Rb of the soaking zone 120b, so that the cross-sectional area of ​​the flow path from the top to the bottom of the heating zone 120a is larger than the cross-sectional area of ​​the flow path from the top to the bottom of the soaking zone 120b.

[0025] In this embodiment, when the storage rotating body 120 is divided into nine equally spaced stages SG in the circumferential direction, two of these (2 / 9) are included in the heating zone 120a, and the remaining seven (7 / 9) are included in the soaking zone 20b. Furthermore, one of the stages SG in the upstream half of the heating zone 120a is designated as the first heating zone 120a1, and one of the stages SG in the downstream half is designated as the second heating zone 120a2. These proportions are not limited. A feeding device 125 is located upstream of the first heating zone 120a1, and a removal device 126 is located downstream of the soaking zone 120b.

[0026] The inner cylinder portion 130 has a vertical cylindrical hollow shape and is positioned in close proximity to the storage rotating body 120 in a non-contact manner, and is fixed concentrically to its central space portion 120c. The inner cylinder portion 130 is installed suspended from above, and an opening (not shown) is provided on the side in the heating zone 120a section. This opening can also be omitted. Furthermore, the lower side is shaped like a mortar, with the diameter decreasing towards the bottom.

[0027] The fan 140 is positioned above the inner cylinder 130 and consists of a single circulation fan. This circulation fan 140 is configured to draw in air from below and distribute it evenly in the radial direction. The air distributed evenly in the radial direction is heated by multiple heating elements 129 to become hot air.

[0028] Furthermore, as shown in Figures 1 and 3, three partition guides, specifically the first partition guide 201, the second partition guide 202, and the third partition guide 203, which receive hot air blown radially via the circulation fan 140, are provided at the top of the furnace body 110 without protruding outward from the storage rotating body 120 located below them.

[0029] As shown in Figures 1 and 3, the first partition guide 201 curves and extends from the soaking zone 120b toward the heating zone 120a in the direction of rotation of the storage rotating body 120 (clockwise in this embodiment), receives radial air blown from the circulation fan 140, and directs it from the soaking zone 120b side toward the heating zone 120a side. More specifically, the first partition guide 201 extends in a spiral curve that gradually increases in radius of curvature when viewed from above, that is, gradually widens, from the starting end P1 on the outer circumference of the circulation fan 140 in the heat soaking zone 120b to the ending end P2 on the outer circumference of the storage rotating body 120, which is the starting position of the heating zone 120a (first heating zone 120a1). A small gap is provided at the starting end P1 of the first partition guide 201 so that it does not come into contact with the outer circumference of the circulation fan 140. Similarly, a small gap is provided at the ending end P2 of the first partition guide 201 so that it does not come into contact with the outer circumference of the storage rotating body 120.

[0030] The starting position P1 of the first partition guide 201 is set such that, by providing the first partition guide 201, the amount of air flowing into the heating zone 120a is at least 1.2 times that of when the first partition guide 201 is not provided. In other words, by providing the first partition guide 201, the amount of air flowing into the heating zone 120a is set to be at least 1.2 times the amount MB (total amount MA × 2 / 9) that is distributed in proportion to the proportion of the heating zone 120a that the total amount MA uniformly blown radially from the circulation fan 140. Furthermore, the degree of curvature of the first partition guide 201 is set considering temperature control in the heat distribution zone 120b.

[0031] In this embodiment, as shown in Figure 1, the starting end P1 of the first partition guide 201 is positioned such that a reference line C passing from the end P2 of the first partition guide 201 through the center of the storage rotating body 120 intersects the outer circumference of the circulation fan 140 on the heat soaking zone 120b side (closer to the end P2) in the opposite direction to the rotation direction (counterclockwise in this embodiment).

[0032] As a result, the heating zone 120a receives, in addition to the amount MB of hot air originally sent directly from the circulation fan 140, that is, the total amount MA uniformly blown radially from the circulation fan 140, distributed according to the proportion of the heating zone 120a (total amount MA × 2 / 9), the amount MC of hot air blown from the circulation fan 140 towards the soaking zone 120b, which is sent to the heating zone 120a via the first partition guide 201. In this embodiment, as described above, the starting point P1 of the first partition guide 201 is located significantly in the opposite direction to the rotation direction (counterclockwise in this embodiment) than the position PC where the reference line C intersects the outer circumference of the circulation fan 140. Therefore, the amount of hot air MC flowing from the soaking zone 120b to the heating zone 120a via the first partition guide 201 is more than twice the amount MB distributed to the heating zone 120a. In the heating zone 120a, the amount of hot air MC sent from the soaking zone 120b is added to the amount MB of hot air originally sent directly radially from the circulation fan 140. As a result, if the amount MB distributed from the circulation fan 140 to the heating zone 120a is taken as 1, then more than three times that amount of hot air is sent to the heating zone 120a.

[0033] The second partition guide 202 is located between the end position PE of the heating zone 120a and the adjacent soaking zone 120b.

[0034] The third partition guide 203 divides the heating zone 120a, splitting it into the first heating zone 120a1 (upstream half) and the second heating zone 120a2 (downstream half). The inner tip of the third partition guide 202 is provided with a gap between it and the outer circumference of the circulation fan 140, so that the air (hot air) flowing from the soaking zone 120b to the heating zone 120a is sent not only to the first heating zone 120a1 but also to the second heating zone 120a2 of the heating zone 120a. In this example, a third partition guide 203 is provided to divide the heating zone 120a into two sections. However, it is also possible to omit the third partition guide 203, that is, to not divide the heating zone 120a into two sections. Conversely, multiple third partition guides 203 may be provided to divide the heating zone 120a into multiple zones, allowing for finer temperature control of each zone.

[0035] Furthermore, as shown in Figure 2, in particular in the heating zone 120a, guides 127 are provided on the outside of each of the multi-tiered storage chambers 121 arranged vertically, to divide the flow of hot air and draw hot air into the storage chambers 121. By adjusting the amount of hot air sent to each of the upper and lower storage chambers 121 via the guides 127, the temperature difference between the heated objects (workpieces) in the storage chambers 121 located vertically can be reduced.

[0036] Furthermore, in the soaking zone 120b, a vertically extending cover body 128 is provided between the furnace body 110 and the furnace walls 111 to prevent hot air from entering the storage chamber 121 from the outside of each stage. By providing the cover body 128, the distance T between the soaking zone 120b and the furnace walls 111 is narrower compared to the heating zone 120a. By narrowing the distance T in this way, the furnace body 110 can be made more compact overall. It is also possible to make holes in a part of the cover body 128 to allow some of the hot air to enter the storage chamber 121.

[0037] The rotary heat treatment furnace 100 configured in this way can be used as follows. First, the storage rotating body 120 is rotated clockwise by a rotating device 124, such as a swivel drive device consisting of a motor, and at the same time, a circulation fan 140 is driven to draw in air from below and send it out uniformly in the radial direction.

[0038] The air blown radially is heated by multiple heating elements 129 to become hot air, which is then sent to the heating zone 120a and the soaking zone 120b. At this time, by providing a first partition guide 201 that curves and extends from the soaking zone 120b toward the heating zone 120a, the radial air (hot air) blown into the soaking zone 120b from the circulation fan 140 flows from the soaking zone 120b side toward the heating zone 120a side, thereby concentrating the heat from the hot air into the heating zone 120a. The hot air sent to the heating zone 120a is divided by guides 127 provided on the upper and lower levels and sent to the storage chambers 121 located above and below it. This makes it possible to efficiently increase the heating rate of the object to be heated (workpiece) in the storage chamber 121 provided in the heating zone 120a. After that, the hot air is sent from above downwards through the space between the furnace wall 111 of the furnace body 110 and the heating zone 120a, from the lower end of the central space 120c toward its upper end, and then sucked back into the circulation fan 140 from below and circulated again. Furthermore, since an opening is provided on the side of the inner cylinder 130 in the heating zone 120a, some of the hot air sent to the storage chamber 121 is guided into the inner cylinder 130 through the opening.

[0039] In particular, regarding the inner diameter of the furnace wall 111 of the furnace body 110, the inner diameter Ra of the heating zone 120a is made larger than the inner diameter Rb of the soaking zone 120b, and the cross-sectional area of ​​the flow path from the top to the bottom of the heating zone 120a is made larger than the cross-sectional area of ​​the flow path from the top to the bottom of the soaking zone 120b. As a result of this increase, the amount of hot air sent to the heating zone 120a side increases, and heat can be applied to the object to be heated (workpiece) more efficiently.

[0040] In contrast, in the uniform heating zone 120b, there is no need to supply heat to the workpiece; it is sufficient to simply keep the workpiece warm. Therefore, the hot air sent to the uniform heating zone 120b and not to the heating zone 120a is sent from above downwards between the furnace wall 111 of the furnace body 110 and the cover body 128 located outside the uniform heating zone 120b, and is sent from the lower end to the upper end of the central space 120c, where it is again sucked up from below by the circulation fan 140 and circulated. Since the uniform heating zone 120b is provided with a cover body 128, the hot air is not directly supplied to the workpiece in the uniform heating zone 120b; the workpiece is only supplied with heat radiated from the furnace wall 111.

[0041] In this way, by making the inner diameter Ra of the heating zone 120a of the furnace wall 111 of the furnace body 110 larger than the inner diameter Rb of the soaking zone 120b, and by making the flow path cross-sectional area from the top to the bottom of the heating zone 120a larger than the flow path cross-sectional area from the top to the bottom of the soaking zone 120b, and by providing the first partition guide 201, the hot air sent to the soaking zone 120b side is sent to the heating zone 120a side, a rotary heat treatment furnace 100 with excellent heat treatment effect can be easily obtained.

[0042] Furthermore, if the furnace body 110 is configured such that the inner diameter Ra of the heating zone 120a is larger than the inner diameter Rb of the soaking zone 120b, and the cross-sectional area of ​​the flow path from the top to the bottom of the heating zone 120a is larger than the cross-sectional area of ​​the flow path from the top to the bottom of the soaking zone 120b, then any structure that sends hot air from the soaking zone 120b to the heating zone 120a, or collects more hot air in the heating zone 120a than in the soaking zone 120b, can be easily applied.

[0043] For example, the configuration of the furnace body 10 of the rotary heat treatment furnace 1 shown in the conventional example (Figure 6) may be modified as shown in Figure 7, by making the inner diameter Ra' of the heating zone 20a larger than the inner diameter Rb' of the homogenizing zone 20b, and making the flow path cross-sectional area from the top to the bottom of the heating zone 20a larger than the flow path cross-sectional area from the top to the bottom of the homogenizing zone 20b, thereby increasing the amount of hot air sent to the heating zone 20a. [Explanation of Symbols]

[0044] 1. Rotary heat treatment furnace 10 Furnace body 11 Guide member 20 Storage Rotating Body 20a Heating zone 20b Average Tropical 20c Central space 21 Storage Room 23 Gas Burner 24 Rotating device 25 Dosing device 26. Extraction device 30 Inner cylinder 31 Guide tube 40 Fan (Centrifugal Fan) 50 First hot air guide 60 Second hot air guide 100 rotary heat treatment furnaces 110 Furnace body 111 Furnace wall 120 Storage Rotating Body 120a heating zone 120a1 First heating zone 120a2 Second Temperature Increase Zone 120b Heating Zone 120c central space 121 Storage Room 124 Rotating device 125 Feeding device 126 Extraction device 127 Guide 128 Cover Body 129 Heating heater (heating device) 130 Inner cylinder 140 Fan (Circulating Fan) 201 First partition guide 202 Second Divider Guide 203 Third partition guide Ra heating zone inner diameter Rb Inner diameter of the heating zone Ra' Inner diameter of the heating zone Rb' Inner diameter of the humus

Claims

1. A roughly cylindrical furnace body, A storage rotating body is provided which is rotatably mounted inside the furnace body, has a central space and is roughly donut-shaped in plan view, and has multiple stages evenly divided along the circumferential direction and arranged in multiple vertical stages, each of which is provided with a storage chamber for storing the object to be heated. A vertical, hollow cylindrical inner cylinder is fixed to the central space of the storage rotating body in a non-contact manner, A circulating fan is positioned above the inner cylinder and blows air drawn in from below in the radial direction. A heating device is provided inside the furnace body to heat the gas inside, The storage chambers on the stages provided on the storage rotating body are sent from the heating zone formed along the circumferential direction by the rotation of the storage rotating body to the soaking zone, where there are more stages than in the heating zone. A rotary heat treatment furnace is provided in which gas blown radially via the circulation fan is sent from top to bottom through the space between the furnace body and the storage rotating body, circulated by passing it back through the inside of the inner cylinder from bottom to top, and the gas is heated via the heating device during this circulation, A rotary heat treatment furnace characterized in that the inner diameter of the furnace wall of the furnace body differs between the soaking zone and the heating zone, with the inner diameter of the heating zone being larger than that of the soaking zone, and the cross-sectional area of ​​the flow path from above to below the heating zone being larger than that of the flow path from above to below the soaking zone.

2. The rotary heat treatment furnace according to claim 1, characterized in that in the soaking zone, a cover body extending vertically is provided between the furnace wall of the furnace body and the cover body, allowing gas blown radially via the circulation fan to pass between the furnace wall of the furnace body and the cover body, but preventing it from entering the storage chamber.

3. The rotary heat treatment furnace according to claim 2, characterized in that a hole is made in a part of the cover body to allow some of the gas to enter the storage chamber.

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