KR101401103B1 - Heat treatment furnace - Google Patents

Abstract

The present invention relates to a hot air type heat treating furnace comprising: furnace bodies (10)(110)(210) which respectively include storing spaces (11)(111)(211) isolated from the outside and to which high temperature gas for heat treatment is introduced; baskets (20)(120)(220) which are respectively accommodated in the storing spaces (11)(111)(211) and which respectively includes a plurality of shelves (21)(21′)(121)(121′)(221)(221′) which arranged in multiple stages in the form of a doughnut and on which articles (P) to be thermally treated are hold and passages (22)(122)(222) formed in the inner side thereof; axial-flow fans (30)(130)(230) which are respectively mounted on the upper sides of the storing spaces (11)(111)(211) to forcedly transfer the high temperature gas to the lower side of the passages (22)(122)(222) to generate hot air; hot air distribution parts (40)(140)(240) which are respectively mounted in the passages (22)(122)(222) of the baskets (20)(120)(220) to distribute the hot air to the shelves (21)(21′)(121)(121′)(221)(221′); and turn tables (50)(150)(150) for supporting the baskets (20)(120)(220) to be able to rotate.

Description

[0002] Heat treatment furnace [0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot air type heat treatment furnace, and more particularly, to a hot air type heat treatment furnace capable of heat treating a plurality of heat treated articles with uniform heat treatment quality.

The heat treatment method refers to a surface hardening heat treatment method in which only the surface of the object to be heat-treated is cured to obtain excellent wear resistance, endothelial property and corrosion resistance, and a general heat treatment method such as annealing, normalizing, quenching and tempering, isothermal transformation, Heat treatment method. This heat treatment process is performed by putting a heat treatment material made of a metal material, for example, an aluminum alloy, into a heat treatment furnace, and then performing three steps of temperature rise, heat treatment and cooling. At this time, the temperature elevation is a step of heating the object to be heat-treated at a predetermined heat-treatment temperature, and is maintained at a constant heat-treatment temperature for a predetermined time to impart the desired properties to the object to be heat-treated.

1 is a view for explaining a configuration of a conventional heat treatment furnace. As shown in FIG. 1, the heat treatment furnace in which the conventional heat treatment process is performed includes a furnace body 1 having a storage space 1a isolated from the outside, into which a high temperature gas for heat treatment flows; A basket (2) which is built in the storage space (1a) and in which a plurality of stationary shelves (2a) and (2a ') on which the objects to be heat treated (P) are placed are arranged in multiple stages; And a circulation fan 3 installed on the upper side of the storage space 1a for circulating the hot gas inside the storage space 1a. With this structure, the hot gas is circulated inside the furnace body 1 and passes from the lower side stationary shelf 2a to the upper side stationary shelf 2a ', and in this process, the stationary shelves 2a and 2a' The heat-treated product (P) which is immersed in the heat-treated product P is heat-treated.

In the above-described heat treatment furnace, since the hot gas circulated by the circulating fan 3 passes through the upper side shelf shelf 2a 'through the lower side shelf shelf 2a, There is a problem in that the rate of temperature increase of each of the heat-treated articles respectively mounted on the upper side stationary shelf 2a 'is different, and thus the heat treatment quality is not constant.

In addition, a heat treatment furnace having a gas circulation device is disclosed in Patent Document No. 10-2010-0081053 related to the prior art related to the heat treatment.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot air type heat treatment furnace capable of uniformizing the heat treatment quality of a plurality of heat-treated articles placed on a lower side mounting shelf and an upper side mounting shelf, do.

In order to achieve the above object, a hot air type heat treatment furnace according to the present invention comprises:
A furnace body 110 in which a storage space 111 isolated from the outside is formed and into which a hot gas for heat treatment flows; A plurality of mounting shelves 121 and 121 'in which the heat-treated product P is mounted are formed in a donut shape and are arranged in multiple stages and a passage 122 is formed in the interior of the storage space 111, A basket formed; An axial flow fan (130) installed on the upper side of the storage space (111) and feeding the hot gas to the lower side of the passage (122) to make hot air; A hot air distributor 140 installed in the passage 122 inside the basket and distributing the hot air to each of the stationary shelves 121 and 121 '; And a turntable (150) for rotatably supporting the basket. (115 ') formed on the inner circumferential surface of the storage space (111) of the furnace body (110) and having an inner diameter increasing from the lower side to the upper side; The expansion parts 115 and 115 'are formed in a stepped shape corresponding to the number of stages of the stationary shelves 121 and 121'.
In the present invention, the hot air distributor 40, 140, 240 includes an inner cylinder 41, 141, 241 located in the passage 22, 122, 222 of the basket, 142 ', 142', 242, 242 'formed on the sides of the inner cylinders 41, 141, 241 and directed toward each of the stationary shelves do. The sectional areas of the distribution holes 42, 142 and 242 at the positions corresponding to the lower side shelf shelves 21, 121 and 221 are the same as the upper shelf shelf 21 ' (142 '), (242') at the positions corresponding to the first and second openings (221 ', 221').

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In the present invention, the hot air sucking unit 260 (see FIG. 1) which surrounds the basket 220 and sucks hot air passing through each of the stationary shelves 221 and 221 'to flow toward the rear side of the axial fan 230 ). The hot air suction unit 260 includes an outer cylinder 261 that is spaced apart from the inner circumferential surface of the furnace body 210 while the basket 220 is being wrapped around the outer circumference of the furnace body 210, And includes a plurality of suction holes 262 and 262 'which face each of the stationary shelves 221 and 221'. The sectional area of the suction hole 262 at the position corresponding to the lower side shelf shelf 221 is smaller than the sectional area of the suction hole 262 'at the position corresponding to the upper side shelf shelf 221'.

According to the present invention, in order to correct the unevenness of the air volume due to the pressure difference of the hot air at a position close to the axial flow fan and at a distant position, a hot air distributor having a plurality of distribution holes formed in a lower cross- , So that the amount of hot air blown to the lower side rack and the upper side rack can be made constant. Further, the inner circumferential surface of the storage space of the furnace body is formed with an expanded portion whose inner diameter becomes wider from the lower side to the upper side, so that the air volume of the hot air via the lower side mounting shelf and the upper side mounting shelf can be made constant. In addition, a hot air suction unit having a plurality of suction holes formed in a lower cross-sectional area from the lower side to the upper side is adopted, so that the air volume of the hot air sucked after passing through the lower side mounting shelf and the upper side mounting shelf can be made constant. Accordingly, the rate of temperature rise of the heat-treated article placed on each of the lower and upper-side stationary shelves can be made constant, and the heat treatment quality can be made even more uniform.

1 is a view for explaining a configuration of a conventional heat treatment furnace,
2 is a view for explaining the configuration of the first embodiment of the hot air type heat treatment furnace according to the present invention,
FIG. 3 is an exploded perspective view of a hot air distributing portion provided in the baskets inner passage of FIG. 2;
4 is a view for explaining the configuration of the second embodiment of the hot air type heat treatment furnace according to the present invention,
5 is a view for explaining the configuration of the third embodiment of the hot air type heat treatment furnace according to the present invention,
FIG. 6 is an exploded perspective view of a hot-air suction unit installed to enclose the basket shown in FIG. 5;

Hereinafter, a hot air type heat treatment furnace according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a view for explaining a configuration of a first embodiment of the hot air type heat treatment furnace according to the present invention, and FIG. 3 is an exploded perspective view of a hot air distributing part provided in the inside passage of the basket shown in FIG.

As shown in the drawings, the first embodiment of the hot air type heat treatment furnace according to the present invention includes a furnace main body 10 having a storage space 11 isolated from the outside, into which a hot gas for heat treatment flows; A plurality of stationary shelves 21 and 21 'which are embedded in the storage space 11 and in which the heat-treated product P is placed are formed in a donut shape and arranged in multiple stages, and a passage 22 is formed inside A basket (20); An axial flow fan (30) installed on the upper side of the storage space (11) and feeding hot gas to the lower side of the passage (22) to make hot air; A hot air distributor 40 installed in the passage 22 inside the basket 20 and distributing hot air to each of the shelves 21 and 21 '; And a turntable (50) for rotatably supporting the basket (30).

And a nozzle 12 connected to a burner (not shown) for supplying a high-temperature gas is formed on the upper edge side of the accommodating space 11. As shown in FIG. An entrance (not shown) is formed in a side portion of the furnace body 10 so as to allow the material P to be heat-treated to enter and exit.

In the basket 20, a plurality of stationary shelves 21 and 21 'are arranged in multiple stages to form a donut shape as a whole, and a passage 22 is formed inside the center. The basket 20 is implemented by connecting a plurality of frame bars three-dimensionally in the circumferential direction, the horizontal direction and the vertical direction so that the hot wind can pass therethrough. A heat-treated product P made of a metal material such as aluminum is deposited on the stationary shelves 21 and 21 '.

In the present embodiment, for ease of explanation, the lower side rack is denoted by reference numeral 21 and the upper side rack is denoted by reference numeral 21 '.

The axial flow fan (30) is installed on the upper side of the basket passage (22) from the inside of the furnace body (10) to make hot gas flow downwardly of the passageway (22). At this time, since the inside of the main body 10 maintains the heat treatment temperature of 600 ° C or more, the motor M for rotating the axial flow fan 30 is installed outside the furnace body 10.

The hot air distribution portion 40 distributes the hot air flowing to the lower side of the basket passage 22 by the axial flow fan 30 to each of the stationary shelves 21 and 21 'arranged in a multi-stage form in the form of a donut. The hot air distribution portion 40 includes an inner cylinder 41 which is located in the passageway 22 of the basket and which is closed at the bottom side and a stationary shelf 21 and 21 'which are formed at the side of the inner cylinder 41, And a plurality of distribution holes 42 and 42 'facing each other. At this time, the shapes of the distribution holes 42 and 42 'may be various shapes such as a circle, an ellipse, or a rectangle. In the drawings of the present embodiment, the shapes of the distribution holes 42 and 42'

In this embodiment, a distributing hole formed at a position corresponding to the lower side mounting shelf 21 is indicated by reference numeral 42 and a distributing hole formed at a position corresponding to the upper side mounting shelf 21 ' And is denoted by reference numeral 42 '.

With this structure, a high pressure is formed inside the inner cylinder 41 by the hot air pressure-fed downward by the axial flow fan 30, so that the hot air is supplied to the plurality of distribution holes 42 (I.e., radial direction) of a plurality of multi-stage stationary shelves 21, 21 ' That is, in the conventional heat treatment furnace, the hot wind passes through the lower side stationary shelf and passes through the upper side stationary shelf. In contrast, in the present invention, the hot wind distributor 40 is provided with the hot shelves 21 and 21 ' Is directly applied to the side.

3, the sectional area of the distribution hole 42 at the position corresponding to the lower side mounting shelf 21 is smaller than the sectional area of the distribution hole 42 'at the position corresponding to the upper side accommodation shelf 21' Lt; / RTI >

The axial flow fan 30 forms a downward flow of hot air in the hot air distributor 40 so that the pressure of the hot air at a position near the axial flow fan 30 in the hot air distributor 40 is at a far ). Therefore, if the cross sectional areas of the plurality of distribution holes formed in the hot air distribution portion 40 are all the same, the amount of the hot air discharged through the distribution holes located near the axial flow fan 30 can be reduced, Is larger than the air flow rate of the hot air discharged through the distribution hole. Accordingly, the heating rate of the heat-treated article P placed on the lower side stationary shelf 21 and the upper side stationary shelf 21 'may be different and the heat treatment quality is not uniform.

The cross sectional area of the distribution hole 42 corresponding to the lower side stationary shelf 21 is set to be larger than the cross sectional area of the lower side stationary shelf 21 in order to correct the unevenness of the air volume due to the pressure difference of the hot air at a position close to the axial flow fan 30, Sectional area of the distribution hole 42 'corresponding to the side-by-side shelf 21', and consequently the air volume of the hot air applied to the lower side accommodation shelf 21 and the upper side accommodation shelf 21 ' You can do it. Therefore, the rate of temperature rise of the heat-treated article P, which is respectively fixed to the lower and upper-side stationary shelves 21, 21 ', can be made constant, and the heat treatment quality can be made uniform.

The turntable 50 rotates the basket 20 during the heat treatment, or rotates the basket 20 to place or discharge the object to be heat-treated on the shelf. The motor for rotating the turntable 50 is also installed outside the furnace body 10. Since such a turntable is well known in the art, further detailed description is omitted.

Thus, in the first embodiment of the hot air type heat treatment furnace, A plurality of distribution holes 42 and 42 'having a larger cross-sectional area from the lower side to the upper side are formed in order to correct the unevenness of the air volume due to the pressure difference of hot air at a position close to the axial flow fan 30 and at a distant position A hot air distribution portion 40 is employed. Thus, the amount of the hot air to be applied to the lower-side stationary shelf 21 and the upper-side stationary shelf 21 'can be made constant, and the heat treatment can be performed on the lower and upper-side stationary shelves 21, The rate of temperature rise of the water P can be made constant and the quality of the heat treatment can be made uniform.

4 is a view for explaining a configuration of a second embodiment of the hot air type heat treatment furnace according to the present invention.

As shown in the drawing, the second embodiment of the hot air type heat treatment furnace according to the present invention includes a furnace body 110 into which a storage space 111 isolated from the outside is formed, into which a hot gas for heat treatment flows; A plurality of mounting shelves 121 and 121 'in which the heat-treated product P is mounted are formed in a donut shape and arranged in multiple stages, and a passage 122 is formed in the inside thereof A basket (120); An axial flow fan 130 installed on the upper side of the storage space 111 for feeding hot gas to the lower side of the passage 122 to make hot air; A hot air distributor 140 installed in the passageway 122 inside the basket 120 for distributing the hot air to each of the shelves 121 and 121 ' And a turntable (150) for rotatably supporting the basket (130).

A nozzle 112 connected to a burner (not shown) for supplying a high-temperature gas is formed on the upper edge side of the storage space 111, and a heat- An entrance (not shown) for entering and exiting is formed.

In the basket 120, a plurality of stationary shelves 121 and 121 'are arranged in multiple stages to form a donut shape as a whole, and a passage 122 is formed inside the center.

The axial flow fan 130 is installed on the upper side of the basecut passage 122 from the inside of the furnace body 110 to make the hot gas flow into the downward side of the passage 122.

The hot air distribution section 140 distributes the hot air flowing to the lower side of the basket passage 122 by the axial flow fan 130 to each of the stationary shelves 121 and 121 'arranged in multiple stages in a donut shape. The hot air distribution unit 140 includes an inner cylinder 141 positioned at the passage 122 of the basket and hermetically closed on the bottom side and a fixed shelf 121 and 121 'formed at the side of the inner cylinder 141, And a plurality of distribution holes 142 (142 ') facing each other.

The turntable 150 rotates the basket 20 during the heat treatment, or rotates the basket 120 to place or discharge the object to be latched on the shelf.

The basket 120, the axial fan 130, the hot air distributor 140 and the turntable 150 are installed in the basket 20, the axial flow fan 30, the hot air distributor 40 And the turntable 50, detailed description thereof will be omitted.

The second embodiment of the hot air type heat treatment furnace is similar to the first embodiment. The quality of the heat treatment of the heat-treated product P placed on the plurality of stationary shelves 121 and 121 'can be more uniform. For this purpose, the inner circumferential surface of the storage space 111 of the furnace body 110 is formed with an expanding portion 115 or 115 'whose inner diameter becomes wider from the lower side toward the upper side. In the present embodiment, the expansion parts 115 and 115 'are formed in a stepped shape corresponding to the number of stages of the stationary shelves 121 and 121' when viewed from the side, The inner diameter of the bending portion 115 is smaller than the inner diameter of the bending portion 115 'corresponding to the upper side placing rack 121'.

The upper and lower side sound pressures on the outside of the basket 20 are equal to each other so that the air volume of the hot air passing through the side of the lower side accommodation shelf 121 and the side of the upper side accommodation shelf 121 ' Should be. On the other hand, in order to circulate the hot air passing through the side of the basket 20 to the rear side of the axial fan 130, the pressure at a position far from the axial fan 130 must be higher than the pressure at the near position. Therefore, in order to allow the hot air to flow from the outside of the basket 120 to the rear side of the axial fan 130 while the air volume of the hot air passing through the lower side and the upper side of the basket 120 is the same, (115) formed on the inner circumferential surface of the cylindrical body (111) to have a larger inner diameter from the lower side to the upper side.

In order to correct the unevenness of the air volume due to the pressure difference between the hot air at the position far from the axial fan 130 and the hot air at the position near the axial fan 130, The inner diameter of the expansion portion 115 corresponding to the upper side shelf 121 'is made smaller than the inner diameter of the expansion portion 115' corresponding to the upper side storage shelf 121 '. The air flow amount of the hot air passing through the lower side placing shelf 121 and the upper side placing shelf 121 'can be made constant, and thus the lower and upper side placing shelves 121 and 121' The rate of temperature rise of the heat-treated article P can be made constant, and the quality of the heat treatment can be made uniform.

FIG. 5 is a view for explaining the configuration of a third embodiment of a hot air type heat treatment furnace according to the present invention, and FIG. 6 is an exploded perspective view of a hot air suction part provided to enclose the basket shown in FIG.

As shown in the drawing, the third embodiment of the hot-air type heat treatment furnace according to the present invention includes a furnace body 210 into which a storage space 211 isolated from the outside is formed and into which a hot gas for heat treatment flows; A plurality of shelf shelves 221 and 221 'in which the objects P to be heat-treated are accommodated are formed in a donut shape and arranged in multiple stages, and a passage 222 is formed inside A basket (220); An axial flow fan 230 installed on the upper side of the accommodating space 211 to pressurize the hot gas to the lower side of the path 222 to make hot air; A hot air distributor 240 installed in the passage 222 inside the basket 220 and distributing hot air to each of the shelves 221 and 221 '; A turntable 250 rotatably supporting the basket 230; And a hot air sucking unit 260 installed to enclose the basket 220 and sucking the hot air passing through each of the stationary shelves 221 and 221 'and flowing the hot air flowing toward the rear side of the axial fan 230 do.

Here, the basket 220, the axial flow fan 230, and the turntable 250 having the furnace body 210, the shelf shelves 221 and 221 'and the passageway 222 formed with the storage space 211, 1, the basket 20, the axial flow fan 30, and the turntable 50 having the furnace body 10, the shelf shelves 21 and 21 'and the passages 22 formed with the storage space 11, Since the structure is substantially similar, this detailed description is omitted.

The third embodiment of the hot-air type heat treatment furnace is for heat-treating the heat-treated product P having a complicated geometrical structure. When the heat-treated article P has a complicated geometric structure, the hot air discharged in one direction does not flow to a specific portion of the article P to be heat-treated according to the geometrical structure, and thus the heat-treatment quality may not be uniform. In order to prevent such a phenomenon, the second embodiment of the hot air type heat treatment furnace employs a hot air suction unit 260 for sucking hot air from the outside of the basket 220 and will be described in detail as follows.

The hot air distribution part 240 distributes the hot air flowing to the lower side of the basket port 222 by the axial flow fan 230 to each of the stationary shelves 221 and 221 'arranged in a multi-stage configuration in the form of a donut. The hot air distribution part 240 includes an inner cylinder 241 located at the passage 222 of the basket and hermetically closed at the bottom side and a stationary shelf 221 and 221 'formed at the side of the inner cylinder 241, And a plurality of distribution holes 242 and 242 'facing each other. And the sectional area of the dispensing hole 242 at the position corresponding to the lower side placing shelf 221 is larger than the sectional area of the dispensing hole 242 'at the position corresponding to the upper side placing shelf 221'. Since the hot air distribution portion 240 is similar to the operation of the hot air distribution portion 340 in the first embodiment, a detailed description thereof will be omitted.

The hot air suction unit 260 includes an outer cylinder 261 disposed to be spaced apart from the inner circumferential surface of the furnace body 210 while the basket 220 is wrapped around the furnace body, And a ring plate 263 connecting the upper end of the outer cylinder 261 and the upper end of the inner cylinder 241 of the hot air distribution portion 240 to each other through a plurality of suction holes 262 ' . At this time, the shapes of the suction holes 262 and 262 'may be various shapes such as a circle, an ellipse, or a rectangle, and they are shown in a circular shape in the drawings of the present embodiment.

The hot air sucking unit 260 forms a duct connected to the rear of the axial fan 230 between the furnace body 211 and the basket 220 so that hot air, (230). At this time, the ring plate 263 has a structure inclined to one side, so that the hot air smoothly flows to the rear side of the axial fan 230.

On the other hand, the cross-sectional area of the suction hole 262 at the position corresponding to the lower-side stationary shelf 321 is larger than the cross-sectional area of the suction hole 262 'at the position corresponding to the upper-side stationary shelf 221'.

The pressure of the hot air sucked at a position near the axial fan 230 is lower than the pressure of the hot air sucked at a remote position so that the hot air sucked in the hot air suction unit 260 flows to the axial fan 230. Therefore, if the cross-sectional areas of the plurality of suction holes formed in the hot air suction portion 260 are all the same, the amount of the hot air sucked through the suction hole located near the axial fan 230 can be reduced, Is smaller than that of the hot air sucked through the suction hole. In this case, the heating rate of the heat-treated product P placed on the lower side setting rack 221 and the upper side setting rack 221 'may differ, and the heat treatment quality is not uniform.

6, in order to correct the unevenness of the air volume due to the pressure difference of the hot air sucked at a position close to the axial flow fan 230 and a position far away from the axial fan 230, Sectional area of the suction hole 262 is made smaller than the sectional area of the suction hole 262 'corresponding to the upper side shelf shelf 221', and consequently the lower shelf shelf 321 and the upper side shelf shelf 321 ' It is possible to make the air volume of the hot air sucked in after being passed through. Therefore, the rate of temperature rise of the heat-treated article P, which is respectively fixed to the lower and upper-side stationary shelves 221 and 221 ', can be made constant, and the heat treatment quality can be made uniform.

Thus, in the third embodiment of the hot air type heat treatment furnace, In order to correct the unevenness in the amount of air sucked due to the difference in the position of the hot air distribution unit 240 described in the first embodiment and the difference between the position close to the axial flow fan 230 and the hot air at a distant position, And a hot air suction unit 260 having a plurality of suction holes 262 and 262 'having a larger cross-sectional area is formed. Accordingly, the amount of the hot air sucked after passing through the lower-side stationary shelf 221 and the upper-side stationary shelf 221 'can be made constant, and thereby the lower and upper-side stationary shelves 221 and 221' The rate of temperature rise of the immobilized object P to be heat-treated can be made constant and the quality of the heat treatment can be made even more uniform.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

10, 110, 210, ...,
20, 120, 220 ... basket
21, 21 ', 121, 121', 221, 221 '... rack
30, 130, 230, ... Axial flow fan
40, 140, 240 ... hot air distribution portion
41, 141, 241 ... inner cylinder
42, 42 ', 142, 142', 242, 242 '
50, 150, 250 ... turntable
115, 115 '... expansion portion
260 ... hot air suction part 261 ... outer cylinder
262, 162 '... suction hole 263 ... ring plate

Claims (7)

A furnace body 110 in which a storage space 111 isolated from the outside is formed and into which a hot gas for heat treatment flows; A plurality of mounting shelves 121 and 121 'in which the heat-treated product P is mounted are formed in a donut shape and are arranged in multiple stages and a passage 122 is formed in the interior of the storage space 111 A basket formed; An axial flow fan (130) installed on the upper side of the storage space (111) and feeding the hot gas to the lower side of the passage (122) to make hot air; A hot air distributor 140 installed in the passage 122 inside the basket and distributing the hot air to each of the stationary shelves 121 and 121 '; And a turntable (150) for rotatably supporting the basket.
(115 ') formed on the inner circumferential surface of the storage space (111) of the furnace body (110) and having an inner diameter increasing from the lower side to the upper side;
Wherein the expansion parts 115 and 115 'are formed in a stepped shape corresponding to the number of stages of the stationary shelves 121 and 121'. The hot air distribution system according to claim 1, wherein the hot air distribution unit (40) (140) (240)
141 and 141 located at the passages 22, 122 and 222 of the basket, and an inner cylinder 41, 141 and 241 located at the sides of the inner cylinder 41, 141 and 241, And a plurality of distribution holes (42), (42 '), (142), (142'), (242) and (242 ') facing each other. 3. The method of claim 2,
The sectional areas of the distribution holes 42, 142 and 242 at positions corresponding to the lower side stationary shelves 21, 121 and 221 are the same as those of the upper side stationary shelves 21 ', 121' Is greater than the cross-sectional area of the distribution hole (42 ') (142'), (242 ') at a position corresponding to the position of the heat exchanger. delete The method according to claim 1,
And a hot air suction unit 260 installed to enclose the basket 220 and sucking hot air passing through each of the stationary shelves 221 and 221 'to flow toward the rear side of the axial fan 230, Wherein the heat treatment furnace is a hot-air heat treatment furnace. 6. The apparatus of claim 5, wherein the hot air inlet (260)
An outer cylinder 261 disposed so as to be spaced apart from the inner circumferential surface of the furnace body 210 in a state where the basket 220 is wrapped around the shelves 221 and 221 ' And a plurality of suction holes (262) (262 ') facing the suction holes (262). The method according to claim 6,
Sectional area of the suction hole 262 at a position corresponding to the lower shelf shelf 221 is smaller than a sectional area of the suction hole 262 'at a position corresponding to the upper shelf shelf 221' Heat treatment furnace with hot air.

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