Intermittent heat treatment furnace

Abstract

The technical problem of the present invention is to suppress variations in temperature distribution in a furnace. This intermittent heat treatment furnace is provided with: a hearth; a furnace wall having a side wall and a top wall provided so as to surround the hearth, the furnace wall forming a furnace chamber inside together with the hearth; a plurality of gas supply pipes which are provided with openings in the furnace chamber and supply gas to the furnace chamber through the side walls; a heater for heating the furnace chamber; a hollow cylindrical first exhaust pipe inserted in the center of the furnace chamber in the vertical direction from the hearth or the ceiling wall to the furnace chamber when the furnace chamber is viewed from above; a second exhaust pipe having a larger diameter than the first exhaust pipe, the first exhaust pipe being inserted through the inside thereof, and being shorter than the insertion length of the first exhaust pipe into the furnace chamber; and a third exhaust pipe having a larger diameter than the second exhaust pipe, through which the first exhaust pipe and the second exhaust pipe are inserted, and which is shorter than the insertion length of the second exhaust pipe into the furnace chamber.

Description

Technical Field

[0001] The present disclosure relates to a batch-type heat treatment furnace for heat treatment processes and the like. Background Art

[0002] In the manufacturing processes of various products such as ceramic electronic components, a heat treatment furnace for heat-treating components and semi-finished products is used. As the heat treatment furnace, a batch-type heat treatment furnace and a continuous-type heat treatment furnace can be cited. The batch-type heat treatment furnace can be applied to, for example, a case where the number of workpieces to be heat-treated under the same conditions is small, or a case where workpieces divided into multiple groups need to be heat-treated under different multiple conditions.

[0003] On the other hand, due to the high precision of electronic components to be heat-treated and the improvement of required performance in recent years, there is an expectation to more strictly manage treatment conditions such as temperature, pressure, and atmosphere during heat treatment. In order to strictly manage the heat treatment conditions in a batch-type heat treatment furnace or the like, it is effective to suppress the deviation of the temperature distribution in the furnace. As an existing technique for suppressing the deviation of the temperature distribution in the furnace of a batch-type heat treatment furnace, for example, when gas is supplied from a gas supply pipe into the furnace, the gas ejected from the gas supply pipe is heated by the heat of a heater and dispersed in the furnace (see Patent Document 1 and the like).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 4385213 Specification Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the existing batch-type heat treatment furnace, there is a problem that the deviation of the temperature distribution in the furnace cannot be sufficiently suppressed due to the deviation of the position of the gas discharge port in the furnace or the like.

[0009] Technical Solution for Solving the Problem

[0010] In order to solve the above problems, the present disclosure provides a batch-type heat treatment furnace having:

[0011] A furnace floor;

[0012] A furnace wall having side walls and a top wall provided to surround the furnace floor, and forming a furnace chamber inside together with the furnace floor;

[0013] A plurality of gas supply pipes having openings in the furnace chamber and supplying gas to the furnace chamber via the side walls;

[0014] A heater for heating the furnace chamber;

[0015] A first exhaust pipe in a hollow cylindrical shape, which is inserted into the center of the furnace chamber when viewed from above the furnace chamber in the vertical direction from the furnace bed or the top wall;

[0016] A second exhaust pipe, which has a larger diameter than the first exhaust pipe, the first exhaust pipe is inserted through its interior, and has a shorter insertion length into the furnace chamber than the first exhaust pipe; and

[0017] A third exhaust pipe, which has a larger diameter than the second exhaust pipe, the first exhaust pipe and the second exhaust pipe are inserted through its interior, and has a shorter insertion length into the furnace chamber than the second exhaust pipe.

[0018] In the batch-type heat treatment furnace of the present disclosure, the exhaust gas flow path composed of the first to third exhaust pipes is arranged in the center of the furnace chamber in the vertical direction. In such a batch-type heat treatment furnace, the gas supplied from the side wall to the furnace chamber is guided to the exhaust gas flow path and discharged from openings respectively arranged at three different heights in the center of the furnace chamber. The batch-type heat treatment furnace of the present disclosure can reduce the deviation of the temperature distribution in the furnace chamber by reducing the deviation of the position of the inlet of the exhaust gas flow path and forming a uniform flow of the gas in the furnace chamber from the supply port to the opening of the exhaust gas flow path.

[0019] In addition, for example, it may also be that the plurality of supply pipes include at least two supply pipes having equal distances from the openings of the respective supply pipes to a first opening, and the first opening is an in-furnace opening of a first exhaust gas flow path formed inside the first exhaust pipe,

[0020] It may also be that the plurality of supply pipes include at least two supply pipes having equal distances from the openings of the respective supply pipes to a second opening, and the second opening is an in-furnace opening of a second exhaust gas flow path formed between the first exhaust pipe and the second exhaust pipe,

[0021] It may also be that the plurality of supply pipes include at least two supply pipes having equal distances from the openings of the respective supply pipes to a third opening, and the third opening is an in-furnace opening of a third exhaust gas flow path formed between the second exhaust pipe and the third exhaust pipe.

[0022] In such a batch-type heat treatment furnace, since there are at least two supply pipes having the same distance from the first to third openings of the first to third exhaust gas flow paths to the first to third openings of the first to third exhaust gas flow paths, the deviation of the residence time of the gas in the furnace caused by the position in the furnace can be reduced.

[0023] In addition, for example, it may also be that the furnace bed rotates about a main rotation axis extending in the vertical direction,

[0024] Alternatively, the central axis of the exhaust pipe, which is the central axis of the first exhaust pipe, the second exhaust pipe, and the third exhaust pipe, may be substantially aligned with the extension line of the main rotation axis.

[0025] By rotating the hearth on which workpieces or the like are placed, particularly, it is possible to reduce the deviation of heat treatment conditions caused by the different positions of the workpieces in the rotation direction. In addition, in such an intermittent heat treatment furnace, when centrifugal force is applied to the gas due to the rotation of workpieces or the like, the in-furnace openings of the discharge flow path are arranged at three different heights, and smooth discharge of the gas is also achieved.

[0026] Alternatively, for example, the hearth may have: a sub-hearth that revolves around the main rotation axis and rotates around a sub-rotation axis that is parallel to the main rotation axis and at a predetermined distance from the main rotation axis.

[0027] Such an intermittent heat treatment furnace can particularly reduce the deviation of heat treatment conditions caused by the different distances of the workpieces from the side wall or the central part of the furnace chamber.

[0028] Alternatively, for example, a plurality of carriers may be stacked in the vertical direction on the hearth in a substantially horizontal posture.

[0029] In such an intermittent heat treatment furnace, since the gas supplied from near the side wall can smoothly flow through the gaps between the carriers and the workpieces to the opening of the exhaust flow path, it is possible to suppress the deviation of the temperature conditions of the respective workpieces arranged in the furnace chamber.

[0030] Alternatively, for example, the first exhaust pipe, the second exhaust pipe, and the third exhaust pipe may be inserted into the furnace chamber from the top wall.

[0031] Alternatively, the heater may be arranged in the vertical direction along the side wall.

[0032] Alternatively, the lower end position of the heater may be closer to the first opening than the second opening. The first opening is the in-furnace opening of the first exhaust flow path formed inside the first exhaust pipe, and the second opening is the in-furnace opening of the second exhaust flow path formed between the first exhaust pipe and the second exhaust pipe.

[0033] The upper end position of the heater may be closer to the third opening than the second opening. The third opening is the in-furnace opening of the third exhaust flow path formed between the second exhaust pipe and the third exhaust pipe.

[0034] Such a heater extends over a large range in the vertical direction of the furnace chamber, can heat the gas flowing in the furnace chamber more uniformly, and can effectively reduce the temperature deviation in the furnace chamber.

[0035] Alternatively, the first exhaust pipe, the second exhaust pipe, and the third exhaust pipe may be inserted into the furnace chamber from the top wall.

[0036] Alternatively, the plurality of gas supply pipes may include: a first gas supply pipe having an opening closer to the first opening than the second opening and the third opening, where the first opening is the furnace interior opening of the first exhaust gas flow path formed inside the first exhaust pipe, the second opening is the furnace interior opening of the second exhaust gas flow path formed between the first exhaust pipe and the second exhaust pipe, and the third opening is the furnace interior opening of the third exhaust gas flow path formed between the second exhaust pipe and the third exhaust pipe; and a second gas supply pipe having an opening closer to the second opening than the first opening and the third opening.

[0037] In this batch-type heat treatment furnace, by corresponding to the differences in the heights of the first to third openings and evenly arranging the first gas supply pipe and the second gas supply pipe, the difference in the distance of the gas from the gas supply port to the exhaust port is reduced, and the deviation of the temperature and atmosphere in the furnace chamber can be reduced.

[0038] In addition, for example, it may also be provided with: a pair of exhaust gas flow rate adjustment blocks that can close at least a part of the fourth opening, the fifth opening, and at least a part of the sixth opening, and form a variable-width gap therebetween across the exhaust pipe central axis that is the central axis of the first exhaust pipe, the second exhaust pipe, and the third exhaust pipe, where the fourth opening is the furnace outer opening of the first exhaust gas flow path formed inside the first exhaust pipe, the fifth opening is the furnace outer opening of the second exhaust gas flow path formed between the first exhaust pipe and the second exhaust pipe, and the sixth opening is the furnace outer opening of the third exhaust gas flow path formed between the second exhaust pipe and the third exhaust pipe.

[0039] This batch-type heat treatment furnace with exhaust gas flow rate adjustment blocks can evenly adjust the discharge amounts of the first to third exhaust gas flow paths with a simple structure, suppress the deviation of the temperature and atmosphere in the furnace chamber, and appropriately adjust the pressure of the furnace chamber, etc. Description of the Drawings

[0040] Figure 1 It is a conceptual diagram showing a batch-type heat treatment furnace according to the first embodiment of the present disclosure.

[0041] Figure 2 It shows Figure 1 a conceptual diagram of the gas flow in the batch-type heat treatment furnace shown.

[0042] Figure 3 It is a conceptual diagram showing a batch-type heat treatment furnace according to the second embodiment of the present disclosure.

[0043] Figure 4It is a conceptual diagram of a batch-type heat treatment furnace showing the third embodiment of the present disclosure.

[0044] Figure 5 It is a conceptual diagram showing the flow of gas in a batch-type heat treatment furnace of the fourth embodiment of the present disclosure.

[0045] Figure 6 It is a conceptual diagram showing the flow of gas in a batch-type heat treatment furnace of the fifth embodiment of the present disclosure.

[0046] Figure 7 It is a schematic view showing the state of the peripheral part of the exhaust gas flow rate adjustment block in the batch-type heat treatment furnace viewed from above Figure 6 as shown.

[0047] Figure 8 It is a conceptual diagram showing Figure 7 the variable-width slit of the exhaust gas flow rate adjustment block shown.

[0048] Explanation of reference numerals

[0049] 10, 110, 210, 410... Batch-type heat treatment furnace

[0050] 12, 112, 212... Hearth

[0051] 14, 15, 214, 215... Sub-hearth

[0052] 16... Furnace wall

[0053] 17... Side wall

[0054] 18... Top wall

[0055] 20... Furnace chamber

[0056] 21... Central part

[0057] D1... Vertical direction

[0058] 24... Heater

[0059] 24a... Upper end

[0060] 24b... Lower end

[0061] 30... Multiple gas supply pipes

[0062] 31a, 31b... First gas supply pipe

[0063] 32a, 32b... Second gas supply pipe

[0064] 33a, 33b... Third gas supply pipe

[0065] 31aa, 33ba, 32aa, 32ba, 33aa, 33ba... Openings

[0066] 51…The first exhaust pipe

[0067] 52…The second exhaust pipe

[0068] 53…The third exhaust pipe

[0069] L1, L2, L3…Insertion length

[0070] 61…The first exhaust gas flow path

[0071] 61a…The first opening

[0072] 61b…The fourth opening

[0073] 62…The second exhaust gas flow path

[0074] 62a…The second opening

[0075] 62b…The fifth opening

[0076] 63…The third exhaust gas flow path

[0077] 63a…The third opening

[0078] 63b…The sixth opening

[0079] 82…Vehicle

[0080] C1…Main rotation axis

[0081] 113…Main hearth

[0082] 113a…Central position

[0083] C4…Exhaust pipe central axis

[0084] 191, 292…Arrow

[0085] C2…Auxiliary rotation axis

[0086] C3…Auxiliary rotation axis

[0087] 411…Furnace main body part

[0088] 419…Holding frame

[0089] 455…Holding rod

[0090] 470…Exhaust gas volume adjustment mechanism

[0091] 471, 472…Exhaust gas flow adjustment blocks

[0092] 471a, 472a…Opposite surfaces

[0093] 471a, 472b…Concavities and convexities

[0094] 473…Gap

[0095] 495…Exhaust chamber Detailed implementation manners

[0096] First Embodiment

[0097] Figure 1 is a conceptual diagram showing the batch-type heat treatment furnace 10 of the first implementation manner of the present disclosure. The batch-type heat treatment furnace 10 includes a furnace bed 12, furnace walls 16, etc. The furnace wall 16 includes a side wall 17 and a top wall 18 that are arranged to surround the furnace bed 12. Together with the furnace bed 12, the furnace wall 16 forms a furnace chamber 20 inside. Figure 1 The shown furnace wall 16 has a generally cylindrical outer shape that is open at the bottom, and the furnace bed 12 is arranged to block the bottom opening of the furnace wall 16.

[0098] The furnace bed 12 includes a generally disk-shaped main furnace bed 13 that blocks the bottom opening of the furnace wall 16, and sub-furnace beds 14 and 15 provided on the main furnace bed 13. In Figure 1 , only two sub-furnace beds 14 and 15 are shown, but the furnace bed 12 has two other sub-furnace beds in addition to the two sub-furnace beds 14 and 15, and has a total of four sub-furnace beds 14 and 15. The four sub-furnace beds 14 and 15 are arranged at a prescribed interval (every 90 degrees in the implementation manner) substantially equally spaced so as to surround the central position 13a of the main furnace bed 13 when viewed from above. The distances between the center positions 13a of each sub-furnace bed 14 and 15 and the main furnace bed 13 are substantially the same.

[0099] However, the furnace bed 12 included in the batch-type heat treatment furnace 10 is not limited to Figure 1 the furnace bed having the main furnace bed 13 and the sub-furnace beds 14 and 15 as shown, for example, it may also be a furnace bed having only the main furnace bed 13. In addition, regarding the number and arrangement of the sub-furnace beds 14 and 15 included in the furnace bed 12, Figure 1 what is shown is only an example and is not limited to the example shown in the implementation manner.

[0100] As Figure 1 shown, a plurality of carriers (also called saggers) 82 are provided on the furnace bed 12 and stacked in a substantially horizontal posture in the vertical direction D1. The carriers 82 are arranged on the furnace bed 12 in a state of being stacked on each sub-furnace bed 14 and 15. A placement portion for placing the workpiece, which is the object of heat treatment of the batch-type heat treatment furnace 10, is formed on the carrier 82. As Figure 1 shown, by stacking and arranging a plurality of carriers 82 for each sub-furnace bed 14 and 15, a plurality of workpieces can be arranged in the furnace chamber 20 while appropriately separating the workpieces from each other and suppressing the deviation of the heat treatment conditions of each workpiece.

[0101] Examples of the material of the carrier 82 include ceramics containing alumina, magnesia, zirconia, etc., which are chemically stable even at high temperatures, but there is no particular limitation. The hearth 12 and the furnace wall 16 can also be made of materials with excellent fire resistance and heat insulation properties such as ceramics, for example.

[0102] As Figure 1 As shown in the figure, the batch heat treatment furnace 10 has a plurality of gas supply pipes 30, a heater 24, a first exhaust pipe 51, a second exhaust pipe 52, a third exhaust pipe 53, etc. The heater 24 is arranged to surround the central portion 21 of the furnace chamber 20 along the side wall 17 and heats the furnace chamber 20.

[0103] As Figure 1 As shown in the figure, the heater 24 is arranged along the side wall 17 in the vertical direction D1, and the upper end 24a of the heater 24 is at the same height as the carrier 82 stacked on the hearth 12 or higher than the height of the carrier 82. In addition, the lower end 24b of the heater 24 is at the same height as the installation surface of the carrier 82 on each sub-hearth 14, 15 or lower than the installation surface of the carrier 82. Such an arrangement of the heater 24 is preferable from the viewpoint of suppressing temperature deviation in the furnace chamber 20, particularly in the area where the workpiece is arranged.

[0104] The heater 24 is not particularly limited, and examples thereof include heaters having metal heating elements such as Ni-Cr series, Fe-Cr-Al series, molybdenum, tungsten, etc., or non-metal heating elements such as silicon carbide, graphite, zirconia, etc.

[0105] As Figure 1 As shown in the figure, the batch heat treatment furnace 10 has a plurality of gas supply pipes 30. The plurality of gas supply pipes 30 have openings in the furnace chamber 20 and supply gas to the furnace chamber 20 via the side wall 17. As Figure 1 As shown in the figure, the plurality of gas supply pipes 30 are composed of a first gas supply pipe 31a, 31b, a second gas supply pipe 32a, 32b, and a third gas supply pipe 33a, 33b. The openings 31aa, 31ba of the first gas supply pipe 31a, 31b, the openings 32aa, 32ba of the second gas supply pipe 32a, 32b, and the openings 33aa, 33ba of the third gas supply pipe 33a, 33b are arranged closer to the side wall 17 than the carrier 82 and the sub-hearths 14, 15. The first gas supply pipe 31a, 31b, the second gas supply pipe 32a, 32b, and the third gas supply pipe 33a, 33b discharge gas into the furnace chamber 20 from their respective openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba.

[0106] The positions of the first gas supply pipes 31a and 31b at the openings 31aa and 31ba in the vertical direction D1 of the furnace chamber 20 are different from the openings 32aa, 32ba of the second gas supply pipes 32a and 32b and the openings 33aa, 33ba of the third gas supply pipes 33a and 33b. That is, for the first gas supply pipes 31a and 31b, their openings 31aa and 31ba are arranged in the furnace chamber 20 at a lower position than the other openings 32aa, 32ba, 33aa, 33ba.

[0107] On the other hand, Figure 1 the opening 31aa of the first gas supply pipe 31a facing the Figure 1 right side and the opening 31ba of the first gas supply pipe 31b facing the

[0108] left side are in the same position in the vertical direction D1 of the furnace chamber 20. However, the directions of the opening 31aa of the first gas supply pipe 31a and the opening 31ba of the first gas supply pipe 31b with respect to the central portion 21 of the furnace chamber 20 are different. More specifically, the opening 31aa of the first gas supply pipe 31a and the opening 31ba of the first gas supply pipe 31b are symmetrically arranged with respect to the central portion 21 of the furnace chamber 20.

[0109] On the other hand, Figure 1 the opening 32aa of the second gas supply pipe 32a facing the Figure 1 right side and the opening 32ba of the second gas supply pipe 32b facing the

[0110] In addition, the positions of the third gas supply pipes 33a and 33b in the vertical direction D1 of the openings 33aa and 33ba in the furnace chamber 20 are different from those of the openings 31aa, 31ba, 32aa, and 32ba of the first gas supply pipes 31a and 31b and the second gas supply pipes 32a and 32b. That is, for the third gas supply pipes 33a and 33b, their openings 33aa and 33ba are arranged in the furnace chamber 20 above the other openings 31aa, 31ba, 32aa, and 32ba.

[0111] On the other hand, Figure 1 the opening 33aa of the third gas supply pipe 33a facing the right side and Figure 1 the opening 33ba of the third gas supply pipe 33b facing the left side are in the same position in the vertical direction D1 of the furnace chamber 20. However, the directions of the opening 33aa of the third gas supply pipe 33a and the opening 33ba of the third gas supply pipe 33b with respect to the central portion 21 of the furnace chamber 20 are different. More specifically, the opening 33aa of the third gas supply pipe 33a and the opening 33ba of the third gas supply pipe 33b are symmetrically arranged with the central portion 21 of the furnace chamber 20 in between.

[0112] The gas supplied from the plurality of gas supply pipes 30 to the furnace chamber 20 is not particularly limited, and examples include inert gases such as nitrogen and helium, reducing gases such as hydrogen, or air.

[0113] As Figure 1 shown, the batch-type heat treatment furnace 10 has: a first exhaust pipe 51, a second exhaust pipe 52, and a third exhaust pipe 53 inserted into the furnace chamber 20 from the top wall 18. The first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53 are inserted in the vertical direction D1 in such a manner as to pass through the central portion 21 of the furnace chamber 20 when viewed from above. The first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53 are hollow cylindrical, and more specifically, they are bottomless cylindrical shapes. However, the shapes of the first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53 are not limited to the cylindrical shape, and may also be polygonal cylindrical shapes or other hollow cylindrical shapes.

[0114] The first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53 are arranged in a nested manner in the radial direction with their central axes aligned. As will be described later, the exhaust gas flow paths of the batch-type heat treatment furnace 10, namely the first exhaust gas flow path 61, the second exhaust gas flow path 62, and the third exhaust gas flow path 63, are formed by these first to third exhaust pipes 51 to 53. Figure 2 is a conceptual diagram showing Figure 1 the flow of gas in the batch-type heat treatment furnace 10 shown in Figure 2 . In Figure 1 , the furnace bed 12 and the carrier 82 shown in

[0115] AsFigure 2 As shown, the diameter of the first exhaust pipe 51 is the smallest among the first to third exhaust pipes 51 to 53 and is arranged at the innermost side. In addition, the first exhaust pipe 51 is the longest among the first to third exhaust pipes 51 to 53, and the insertion length L1 of the first exhaust pipe 51 into the furnace chamber 20 is longer than the insertion length L2 of the second exhaust pipe 52 into the furnace chamber 20 and the insertion length L3 of the third exhaust pipe 53 into the furnace chamber 20.

[0116] The second exhaust pipe 52 has a larger diameter than the first exhaust pipe 51 and a smaller diameter than the third exhaust pipe 53. The first exhaust pipe 51 is inserted through the inside of the second exhaust pipe 52. The second exhaust pipe 52 has a shorter insertion length into the furnace chamber 20 than the first exhaust pipe 51. As Figure 2 shown, the insertion length L2 of the second exhaust pipe 52 into the furnace chamber 20 is shorter than the insertion length L1 of the first exhaust pipe 51 into the furnace chamber 20 and longer than the insertion length L3 of the third exhaust pipe 53 into the furnace chamber 20.

[0117] The third exhaust pipe 53 has a larger diameter than the first exhaust pipe 51 and the second exhaust pipe 52. The first exhaust pipe 51 and the second exhaust pipe 52 are inserted through the inside of the third exhaust pipe 53. The third exhaust pipe 53 has a shorter insertion length into the furnace chamber 20 than the second exhaust pipe 52. As Figure 2 shown, the insertion length L3 of the third exhaust pipe 53 into the furnace chamber 20 is shorter than the insertion length L1 of the first exhaust pipe 51 into the furnace chamber 20 and the insertion length L2 of the second exhaust pipe 52 into the furnace chamber 20.

[0118] As Figure 2 shown, an exhaust gas flow path of the batch type heat treatment furnace 10 is formed by the exhaust pipes having a three-layer structure composed of the first to third exhaust pipes 51 to 53. That is, a first exhaust gas flow path 61 is formed inside the first exhaust pipe 51, and the furnace interior opening of the first exhaust gas flow path 61, i.e., the first opening 61a, is located lower than the furnace interior opening of the second exhaust gas flow path 62, i.e., the second opening 62a, which is another flow path, and the furnace interior opening of the third exhaust gas flow path 63, i.e., the third opening 63a.

[0119] The opening shape of the first opening 61a is circular (for example, refer to Figure 8 ), and it is arranged at the central portion 21 of the furnace chamber 20 when viewed from above. Therefore, the distance from the opening 31aa of the first gas supply pipe 31a to the first opening 61a is equal to the distance from the opening 31ba of the first gas supply pipe 31b to the first opening 61a. The same applies to the opening 32aa of the second gas supply pipe 32a and the opening 32ba of the second gas supply pipe 32b, and the opening 33aa of the third gas supply pipe 33a and the opening 33ba of the third gas supply pipe 33b. The distances to the first opening 61a are equal.

[0120] In addition, as Figure 2As shown, a second exhaust gas flow path 62 is formed between the first exhaust pipe 51 and the second exhaust pipe 52. The furnace interior opening of the second exhaust gas flow path 62, i.e., the second opening 62a, is located above the first opening 61a of the first exhaust gas flow path 61 and below the third opening 63a of the third exhaust gas flow path 63.

[0121] The opening shape of the second opening 62a is a circular ring (for example, refer to Figure 8 ), and it is arranged at the central part 21 of the furnace chamber 20 when viewed from above. Therefore, the distance from the opening 31aa of the first gas supply pipe 31a to the second opening 62a is equal to the distance from the opening 31ba of the first gas supply pipe 31b to the second opening 62a. The same applies to the opening 32aa of the second gas supply pipe 32a and the opening 32ba of the second gas supply pipe 32b, and the opening 33aa of the third gas supply pipe 33a and the opening 33ba of the third gas supply pipe 33b. The distances to the second opening 62a are equal.

[0122] In addition, as Figure 2 shown, a third exhaust gas flow path 63 is formed between the second exhaust pipe 52 and the third exhaust pipe 53. The furnace interior opening of the third exhaust gas flow path 63, i.e., the third opening 63a, is located above the first opening 61a of the first exhaust gas flow path 61 and the second opening 62a of the second exhaust gas flow path 62.

[0123] The opening shape of the third opening 63a is a circular ring (for example, refer to Figure 8 ), and it is arranged at the central part 21 of the furnace chamber 20 when viewed from above. Therefore, the distance from the opening 31aa of the first gas supply pipe 31a to the third opening 63a is equal to the distance from the opening 31ba of the first gas supply pipe 31b to the third opening 63a. The same applies to the opening 32aa of the second gas supply pipe 32a and the opening 32ba of the second gas supply pipe 32b, and the opening 33aa of the third gas supply pipe 33a and the opening 33ba of the third gas supply pipe 33b. The distances to the third opening 63a are equal.

[0124] One ends of the first to third exhaust pipes 51 to 53 are located in the furnace chamber 20, but the other ends of the first to third exhaust pipes 51 to 53 are led out of the furnace chamber 20 above the top wall 18. The furnace exterior openings of the first exhaust gas flow path 61, i.e., the fourth opening 61b, the furnace exterior openings of the second exhaust gas flow path 62, i.e., the fifth opening 62b, and the furnace exterior openings of the third exhaust gas flow path 63, i.e., the sixth opening 63b, are aligned in the vertical direction D1 and arranged in a concentric circle shape.

[0125] Figure 2 The thick arrows shown indicate the flow of gas in the furnace chamber 20. As Figure 2As shown, in the batch heat treatment furnace 10, gas is discharged from the first opening 61a, the second opening 62a, and the third opening 63a, which are arranged at different heights, at the central portion 21 of the furnace chamber 20. In such a batch heat treatment furnace 10, it is possible to reduce the deviation in the positions of the first to third openings 61a, 62a, 63a, which are the inlets of the exhaust gas flow path, in the furnace chamber 20. In addition, the deviation in the distances from the supply ports of the gas into the furnace, i.e., the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba, to the inlets of the nearest exhaust gas flow path, i.e., the first to third openings 61a, 62a, 63a, is small. Further, when the furnace chamber 20 is viewed from above, by dispersedly arranging the supply ports of the gas, i.e., the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba, along the side wall 17 and concentrating the inlets of the exhaust gas flow path, i.e., the first to third openings 61a, 62a, 63a, at the central portion 21 of the furnace chamber 20, it is possible to form a uniform gas flow from the gas supply port to the discharge port throughout the furnace chamber 20.

[0126] Thus, in the batch heat treatment furnace 10, it is possible to generate a gas flow with good uniformity from the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba of the plurality of gas supply pipes 30 arranged near the side wall 17 toward the first to third openings 61a, 62a, 63a in the furnace chamber 20, and prevent the deviation of the temperature distribution and the deviation of the gas components caused by the position.

[0127] In addition, among the plurality of gas supply pipes 30 of the batch heat treatment furnace 10, there are included at least two gas supply pipes in which the distances from the openings of the respective gas supply pipes to the first opening 61a are equal, such as the first gas supply pipe 31a and the first gas supply pipe 31b, the second gas supply pipe 32a and the second gas supply pipe 32b, and the third gas supply pipe 33a and the third gas supply pipe 33b. The same applies to the second opening 62a and the third opening 63a. Thus, by dispersedly arranging the openings of the gas supply pipes, the batch heat treatment furnace 10 can reduce the deviation of the temperature distribution and the deviation of the gas components caused by the position in the circumferential direction surrounding the central portion 21 of the furnace chamber 20.

[0128] In addition, the plurality of gas supply pipes 30 of the batch-type heat treatment furnace 10 include: first gas supply pipes 31a and 31b having an opening closer to the first opening 61a of the first exhaust gas flow path 61 than the second opening 62a of the second exhaust gas flow path 62 and the third opening 63a of the third exhaust gas flow path 63, and second gas supply pipes 32a and 32b having an opening closer to the second opening 62a of the second exhaust gas flow path 62 than the first opening 61a of the first exhaust gas flow path 61 and the third opening 63a of the third exhaust gas flow path 63. In this batch-type heat treatment furnace 10, by arranging the openings of the first gas supply pipes 31a and 31b and the second gas supply pipes 32a and 32b evenly according to the different heights of the first to third openings 61a, 62a, and 63a, the deviation of the distance of the gas from the supply port to the discharge port can be reduced, the uneven discharge of the gas can be reduced, and the deviation of the temperature and atmosphere in the furnace chamber 20 can be reduced.

[0129] In addition, in the batch-type heat treatment furnace 10, the position of the lower end 24b of the heater 24 is closer to the first opening 61a of the first exhaust gas flow path 61 than the second opening 62a of the second exhaust gas flow path 62, and the position of the upper end 24a of the heater 24 is closer to the third opening 63a of the third exhaust gas flow path 63 than the second opening 62a of the second exhaust gas flow path 62. This heater 24 can extend over a large range in the vertical direction D1 of the furnace chamber 20 and heat the gas flowing in the furnace chamber 20 more evenly. Therefore, the batch-type heat treatment furnace 10 can effectively reduce the temperature deviation in the furnace chamber 20.

[0130] Second Embodiment

[0131] Figure 3 is a conceptual diagram showing the batch-type heat treatment furnace 110 of the second embodiment. In Figure 3 In the batch-type heat treatment furnace 110 shown, the furnace bed 112 rotates (self-rotates) about the main rotation axis C1 extending in the vertical direction as shown by the arrow 191, which is different from the batch-type heat treatment furnace 10 shown in Figure 1 Except for the furnace bed 112, the structures of the batch-type heat treatment furnace 110 are the same as those of the batch-type heat treatment furnace 10. The description of the batch-type heat treatment furnace 110 focuses on the differences from the batch-type heat treatment furnace 10, and the same reference numerals are used for the common points with the batch-type heat treatment furnace 10, and the description is omitted.

[0132] In Figure 3In the illustrated batch-type heat treatment furnace 110, the main rotation axis C1 around which the furnace bed 112 rotates passes through the central position 113a of the main furnace bed 113. In addition, the central axis of the first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53, i.e., the exhaust pipe central axis C4, is substantially aligned with the extension line of the main rotation axis C1. The furnace bed 112, for example, transmits a rotational force from a motor (not shown) or the like to the main furnace bed 113, and the main furnace bed 113 rotates, so that the entire furnace bed 112 including the sub-furnace beds 14 and 15 rotates.

[0133] In such a batch-type heat treatment furnace 110, by rotating the furnace bed 112 on which workpieces or the like are placed, for example, even if there are deviations in the temperature distribution around the exhaust pipe central axis C4 and the main rotation axis C1 in the furnace chamber 20, it is possible to suppress deviations in the heat treatment conditions of each workpiece. In addition, in the batch-type heat treatment furnace 110, when centrifugal force is applied to the gas in the furnace chamber 20 by the rotation of the carrier 82 and the workpieces or the like, the in-furnace openings of the discharge flow path are arranged at three different heights, and smooth discharge of the gas is also achieved. In addition to this, the batch-type heat treatment furnace 110 achieves the same effects as the batch-type heat treatment furnace 10 with respect to the common points with the batch-type heat treatment furnace 10.

[0134] Third Embodiment

[0135] Figure 4 It is a conceptual diagram showing the batch-type heat treatment furnace 210 of the third embodiment. Figure 4 In the illustrated batch-type heat treatment furnace 210, the sub-furnace beds 214 and 215 in the furnace bed 212 rotate about the sub-rotation axes C2 and C3 as rotation axes as shown by the arrow 292, Figure 3 which is different from the batch-type heat treatment furnace 110 shown, but the structure other than the part where the sub-furnace beds 214 and 215 rotate is the same as that of the batch-type heat treatment furnace 110. The description of the batch-type heat treatment furnace 210 focuses on the differences from the batch-type heat treatment furnace 110, and the same reference numerals are given to the common points with the batch-type heat treatment furnace 110 and the description is omitted.

[0136] In Figure 4 the illustrated batch-type heat treatment furnace 210, the entire furnace bed 212 rotates (self-rotates) about the main rotation axis C1 extending in the vertical direction, Figure 3 similarly to the furnace bed 112 shown. The main rotation axis C1 passes through the central position 113a of the main furnace bed 113. In addition, the central axis of the first exhaust pipe 51, the second exhaust pipe 52, and the third exhaust pipe 53, i.e., the exhaust pipe central axis C4, is substantially aligned with the extension line of the main rotation axis C1.

[0137] As Figure 4As shown by arrow 292, the sub-hearth 214 rotates about a sub-rotating shaft C2 that is parallel to the main rotating shaft C1 and is at a specified distance from the main rotating shaft C1. In addition, the sub-hearth 215 rotates about a sub-rotating shaft C3 that is parallel to the main rotating shaft C1 and is at a specified distance from the main rotating shaft C1. Furthermore, the distance from the main rotating shaft C1 to the sub-rotating shaft C2 and the distance from the main rotating shaft C1 to the sub-rotating shaft C3 are substantially the same.

[0138] In Figure 4 In the batch-type heat treatment furnace 210 shown, the sub-hearths 214 and 215 and the setter 82 placed on the sub-hearths 214 and 215 revolve about the main rotating shaft C1 and rotate about the sub-rotating shafts C2 and C3 as their own rotating shafts. Such a batch-type heat treatment furnace 210 can particularly reduce the deviation of heat treatment conditions caused by the different distances of the workpieces from the side wall 17 or the central part 21 of the furnace chamber 20. In addition, for the common points with the batch-type heat treatment furnace 110, the batch-type heat treatment furnace 210 achieves the same effects as the batch-type heat treatment furnace 110.

[0139] Fourth Embodiment

[0140] Figure 5 is a conceptual diagram showing the flow of gas in the batch-type heat treatment furnace 310 of the fourth embodiment. The batch-type heat treatment furnace 310 is different from the batch-type heat treatment furnace 10 in that the first to third exhaust pipes 351, 352, and 353 are inserted into the furnace chamber from the furnace bed 312, but is the same as the batch-type heat treatment furnace 10 in other points. The description of the batch-type heat treatment furnace 310 focuses on the differences from the batch-type heat treatment furnace 10, and the same reference numerals are used for the common points with the batch-type heat treatment furnace 10, and the description is omitted. Figure 2 As shown in

[0141] As Figure 5 shown, the batch-type heat treatment furnace 310 has: a first exhaust pipe 351, a second exhaust pipe 352, and a third exhaust pipe 353 that are inserted into the furnace chamber 320 from the furnace bed 312. The first exhaust pipe 351, the second exhaust pipe 352, and the third exhaust pipe 353 are inserted in the vertical direction D1 in such a way as to pass through the central part 321 of the furnace chamber 320 when viewed from above the furnace chamber 320. The first exhaust pipe 351, the second exhaust pipe 352, and the third exhaust pipe 353 are arranged in a nested manner in the radial direction with their central axes aligned, in the same way as the first to third exhaust pipes 51, 52, and 53 shown in Figure 2

[0142] As Figure 5 ​As shown, the diameter of the first exhaust pipe 351 is the smallest among the first to third exhaust pipes 351 to 353 and is arranged at the innermost side. In addition, the insertion length L1 of the first exhaust pipe 351 into the furnace chamber 320 is the longest among the first to third exhaust pipes 351 to 353.

[0143] The second exhaust pipe 352 has a larger diameter than the first exhaust pipe 351 and a smaller diameter than the third exhaust pipe 353. The first exhaust pipe 351 passes through the inside of the second exhaust pipe 352. The insertion length L2 of the second exhaust pipe 352 into the furnace chamber 320 is shorter than the insertion length L1 of the first exhaust pipe 351 into the furnace chamber 320 and longer than the insertion length L3 of the third exhaust pipe 353 into the furnace chamber 320.

[0144] The diameter of the third exhaust pipe 353 is larger than that of the first exhaust pipe 351 and the second exhaust pipe 352. The first exhaust pipe 351 and the second exhaust pipe 352 pass through the inside of the third exhaust pipe 353. The insertion length L3 of the third exhaust pipe 353 into the furnace chamber 320 is the shortest among the first to third exhaust pipes 351 to 353.

[0145] As Figure 5 shown, in the batch type heat treatment furnace 310, similar to Figure 2 the batch type heat treatment furnace 10 shown, an exhaust gas flow path of the batch type heat treatment furnace 310 is formed by an exhaust pipe having a three-layer structure composed of the first to third exhaust pipes 351 to 353. That is, a first exhaust gas flow path 361 is formed inside the first exhaust pipe 351, and a furnace interior opening of the first exhaust gas flow path 361, i.e., a first opening 361a, is located above the furnace interior opening of the second exhaust gas flow path 362, i.e., a second opening 362a, and the furnace interior opening of the third exhaust gas flow path 363, i.e., a third opening 363a.

[0146] The second exhaust gas flow path 362 is formed between the first exhaust pipe 351 and the second exhaust pipe 352. The furnace interior opening of the second exhaust gas flow path 362, i.e., the second opening 362a, is located below the first opening 361a of the first exhaust gas flow path 361 and above the third opening 363a of the third exhaust gas flow path 363.

[0147] The third exhaust gas flow path 363 is formed between the second exhaust pipe 352 and the third exhaust pipe 353. The furnace interior opening of the third exhaust gas flow path 363, i.e., the third opening 363a, is located below the first opening 361a of the first exhaust gas flow path 361 and the second opening 362a of the second exhaust gas flow path 362.

[0148] One end portions of the first to third exhaust pipes 351 to 353 are located in the furnace chamber 320, but the other end portions of the first to third exhaust pipes 351 to 353 are led out to the outside of the furnace chamber 320 below the furnace floor 312.

[0149] Figure 5The thick arrows shown indicate the flow of gas within the furnace chamber 320. As Figure 5 shown, in the batch-type heat treatment furnace 310, gas is discharged from the first opening 361a, the second opening 362a, and the third opening 363a, which are disposed at different heights, at the central portion 321 of the furnace chamber 320. In such a batch-type heat treatment furnace 310, similar to Figure 2 the batch-type heat treatment furnace 10 shown, the deviation in the positions of the first to third openings 361a, 362a, 363a, which are the inlets of the exhaust gas flow path, within the furnace chamber 320 can be reduced. In addition, the deviation in the distances from the supply ports of gas into the furnace, namely the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba, to the inlets of the nearest exhaust gas flow path, namely the first to third openings 361a, 362a, 363a, is small. Furthermore, when observing the furnace chamber 320 from above, by dispersedly arranging the supply ports of gas, namely the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba, along the side wall 17 and concentrating the inlets of the exhaust gas flow path, namely the first to third openings 361a, 362a, 363a, at the central portion 21 of the furnace chamber 320, a uniform gas flow from the gas supply port to the discharge port can be formed throughout the furnace chamber 320.

[0150] Thus, in the batch-type heat treatment furnace 310, a gas flow with good uniformity can be generated within the furnace chamber 320 from the openings 31aa, 31ba, 32aa, 32ba, 33aa, 33ba of the plurality of gas supply pipes 30 disposed near the side wall 17 towards the first to third openings 361a, 362a, 363a, preventing deviations in the temperature distribution or deviations in the gas composition caused by position. In addition to this, the batch-type heat treatment furnace 310 achieves the same effects as the batch-type heat treatment furnace 10 for the common points with the batch-type heat treatment furnace 10.

[0151] Fifth Embodiment

[0152] Figure 6 is a conceptual diagram showing the gas flow in the batch-type heat treatment furnace 410 of the fifth embodiment. The batch-type heat treatment furnace 410 is different from Figure 2 the batch-type heat treatment furnace 10 shown, etc., in that exhaust gas volume adjustment mechanisms 470 are provided at the openings outside the furnace of the first to third exhaust gas flow paths 61, 62, 63, namely the fourth to sixth openings 61b, 62b, 63b, but is the same as the batch-type heat treatment furnace 10 in other aspects. In the description of the batch-type heat treatment furnace 410, the differences from the batch-type heat treatment furnace 10 are centered on, and the common reference numerals are used for the common points with the batch-type heat treatment furnace 10 and the description is omitted.

[0153] As Figure 6As shown, the batch-type heat treatment furnace 410 is provided with an exhaust chamber 495 above the furnace main body 411. The gas discharged from the furnace chamber 20 via the first to third exhaust flow paths 61, 62, and 63 flows into the exhaust chamber 495. The exhaust chamber 495 communicates with, for example, a common exhaust flow path of the building in which the batch-type heat treatment furnace 410 is installed. In addition, the part of the batch-type heat treatment furnace 410 other than the exhaust volume adjustment mechanism 470 and the exhaust chamber 495, that is, the furnace main body 411, is the same as the Figure 1 and Figure 2 batch-type heat treatment furnace 10 shown.

[0154] The exhaust volume adjustment mechanism 470 of the batch-type heat treatment furnace 410 has a pair of exhaust flow adjustment blocks 471, 472 that form a variable-width slit 473 therebetween. Both the exhaust flow adjustment blocks 471, 472 can close at least a part of the fourth opening 61b of the first exhaust flow path 61, at least a part of the fifth opening 62b of the second exhaust flow path 62, and at least a part of the sixth opening 63b of the third exhaust flow path 63.

[0155] Figure 7 is a schematic view showing the state of the peripheral part of the exhaust flow adjustment blocks 471, 472 in the batch-type heat treatment furnace 410 shown when viewed from above. As shown in Figure 6 and Figure 6 and Figure 7 shown, the pair of exhaust flow adjustment blocks 471, 472 are each arranged to straddle the fourth to sixth openings 61b, 62b, 63b arranged in a concentric circle shape. In addition, when viewed from above, one of the pair of exhaust flow adjustment blocks 471, 472 is arranged on one side of the exhaust pipe central axis C4, and the other is arranged on the other side of the exhaust pipe central axis C4, and they are arranged substantially symmetrically with respect to the exhaust pipe central axis C4 that is also the center of the fourth opening 61b.

[0156] As shown in Figure 7 shown, the exhaust flow adjustment blocks 471, 472 are arranged so as to be able to slide in opposite directions via the guide member 475. By sliding the exhaust flow adjustment blocks 471, 472 along the guide member 475, the width of the slit 473 formed between the exhaust flow adjustment blocks 471, 472 is changed, and the discharge amount of the gas from the first to third exhaust flow paths 61 to 63 is adjusted.

[0157] Figure 8 is a conceptual diagram showing the state in which the width of the slit 473 between the exhaust flow adjustment blocks 471, 472 shown in Figure 7 has been changed. As shown in Figure 8As shown, unevennesses 471b and 472b are formed on opposite surfaces 471a and 472a of respective exhaust flow adjustment blocks 471 and 472. By forming the unevennesses 471b and 472b on the opposite surfaces 471a and 472a, the exhaust flow adjustment blocks 471 and 472 can maintain the ratio of the opening areas of the fourth to sixth openings 61b, 62b, and 63b within an appropriate range and adjust the discharge amount of the gas.

[0158] In addition, as Figure 7 and Figure 8 shown, the first to third exhaust pipes 51 to 53 are held relative to a holding frame 419 connected to the top wall 18 or the like by holding rods 455 that penetrate the first to third exhaust pipes 51 to 53 in a direction orthogonal to the central axis C4 of the exhaust pipes near the fourth to sixth openings 61b, 62b, and 63b. The shape of the unevennesses 471b and 472b formed on the opposite surfaces 471a and 472a of the exhaust flow adjustment blocks 471 and 472 may also be determined in consideration of the partial blockage of the fourth to sixth openings 61b, 62b, and 63b by the holding rods 455.

[0159] The batch-type heat treatment furnace 410 of the fifth embodiment can evenly adjust the discharge amounts from the first to third exhaust flow paths 61 to 63 with a simple structure, suppress the deviation of the temperature and atmosphere in the furnace chamber 20, and appropriately perform pressure adjustment of the furnace chamber and the like. In addition, the exhaust flow adjustment blocks 471 and 472 also exhibit the following effect, that is, by reducing the discharge flow rate of the gas, the combustion of coal or the like contained in the gas is promoted, thereby reducing the coal or the like contained in the discharged gas and preventing pollution of the common exhaust flow path of the building or the like. In addition, the material of the exhaust flow adjustment blocks 471 and 472 is not particularly limited, and from the viewpoints of heat resistance and adsorbability of coal or the like, it is preferably made of ceramics or the like. In addition to this, the batch-type heat treatment furnace 410 achieves the same effects as the batch-type heat treatment furnace 10 for the common points with the batch-type heat treatment furnace 10.

[0160] Examples

[0161] Hereinafter, the content of the present disclosure will be described in more detail using examples, but the technical scope of the present disclosure is not limited only to these examples.

[0162] As an example, a batch-type heat treatment furnace 210 (also referred to as a so-called PLK furnace) as shown in the third embodiment was prepared, and the temperatures different in the vertical direction D1 of the carrier 82 were measured, and the temperature distribution (temperature deviation) caused by the difference in the vertical direction D1 of the furnace chamber 20 was measured. In addition, as a comparative example, a batch-type heat treatment furnace different from the batch-type heat treatment furnace 210 only in that the exhaust flow path is composed only of Figure 3 the first exhaust pipe 51 and the third exhaust pipe 53 shown and does not have the second exhaust pipe 52 was prepared, and the same measurement was performed.

[0163] The batch-type heat treatment furnace 210 of the embodiment has less temperature variation caused by the difference in the vertical direction D1 compared to the batch-type heat treatment furnace of the comparative example, and a 20% reduction in temperature deviation is observed. It is confirmed that the deviation of the temperature distribution in the furnace can be suppressed by the structure of the batch-type heat treatment furnace 210 of the present disclosure.

[0164] As described above, the batch-type heat treatment furnace of the present disclosure has been described by way of examples, but the batch-type heat treatment furnace of the present disclosure is not limited to the above-described embodiments. Needless to say, the batch-type heat treatment furnace of the present disclosure also includes many other embodiments and modification examples. For example, the exhaust pipe of the batch-type heat treatment furnace may be a quadruple pipe structure or more, and the furnace inner opening of the exhaust gas flow path having a four-stage structure may be arranged at four or more different heights. In addition, from the viewpoint of forming a uniform air flow, it is more preferable that the number of stages in the height direction of the opening of the exhaust gas flow path is the same as the number of stages in the height direction of the opening of the supply pipe, or the number of stages in the height direction of the opening of the exhaust gas flow path is less than the number of stages in the height direction of the opening of the supply pipe.

Claims

1. An intermittent heat treatment furnace, comprising: Hearth; a furnace wall having side walls and a top wall arranged to surround the hearth and to form a furnace chamber therein together with the hearth; a plurality of gas supply pipes, which are provided with openings in the furnace chamber and supply gas to the furnace chamber through the side wall; A heater for heating the furnace chamber; A first hollow cylindrical exhaust pipe is inserted from the furnace bed or the ceiling into the furnace chamber in a vertical direction into a central portion of the furnace chamber when the furnace chamber is viewed from above; a second exhaust pipe having a larger diameter than the first exhaust pipe, the first exhaust pipe being inserted through the second exhaust pipe and having a shorter insertion length into the furnace chamber than the first exhaust pipe; as well as The third exhaust pipe has a larger diameter than the second exhaust pipe, the first exhaust pipe and the second exhaust pipe are inserted into the third exhaust pipe, and the insertion length of the third exhaust pipe into the furnace chamber is shorter than that of the second exhaust pipe.

2. The batch heat treatment furnace according to claim 1, wherein: The plurality of gas supply pipes include: at least two gas supply pipes having equal distances from openings of the gas supply pipes to a first opening, the first opening being an in-furnace opening of a first exhaust flow path formed inside the first exhaust pipe, The plurality of gas supply pipes include: at least two gas supply pipes having equal distances from openings of the gas supply pipes to a second opening, the second opening being an in-furnace opening of a second exhaust flow path formed between the first exhaust pipe and the second exhaust pipe, The plurality of gas supply pipes include at least two gas supply pipes having equal distances from openings of the gas supply pipes to a third opening, the third opening being an in-furnace opening of a third exhaust flow path formed between the second exhaust pipe and the third exhaust pipe.

3. The batch heat treatment furnace according to claim 1, wherein: The hearth rotates about a main rotation axis extending in the up-down direction as a rotation axis. The exhaust pipe central axis, which is the central axis of the first exhaust pipe, the second exhaust pipe, and the third exhaust pipe, substantially coincides with an extension line of the main rotation axis.

4. The batch heat treatment furnace according to claim 3, wherein: The hearth includes a sub-hearth that revolves around the main rotation axis as a rotation axis and rotates around a sub-rotation axis that is parallel to the main rotation axis and is a predetermined distance away from the main rotation axis as a rotation axis.

5. The batch heat treatment furnace according to claim 1, wherein: The hearth is provided with a plurality of carriers stacked in a vertical direction in a substantially horizontal posture.

6. The batch heat treatment furnace according to claim 1, wherein: The first exhaust pipe, the second exhaust pipe and the third exhaust pipe are inserted into the furnace chamber from the top wall. The heater is arranged in the vertical direction along the side wall, The lower end of the heater is located closer to the first opening than the second opening, the first opening is an in-furnace opening of a first exhaust flow path formed inside the first exhaust pipe, and the second opening is an in-furnace opening of a second exhaust flow path formed between the first exhaust pipe and the second exhaust pipe. The upper end of the heater is located closer to a third opening than the second opening. The third opening is an in-furnace opening of a third exhaust gas flow path formed between the second exhaust pipe and the third exhaust pipe.

7. The batch heat treatment furnace according to claim 1, wherein: The first exhaust pipe, the second exhaust pipe and the third exhaust pipe are inserted into the furnace chamber from the top wall. The plurality of gas supply pipes include: a first gas supply pipe having an opening closer to the first opening than the second opening and the third opening, the first opening being an in-furnace opening of a first exhaust flow path formed inside the first exhaust pipe, the second opening being an in-furnace opening of a second exhaust flow path formed between the first exhaust pipe and the second exhaust pipe, and the third opening being an in-furnace opening of a third exhaust flow path formed between the second exhaust pipe and the third exhaust pipe; and a second air supply pipe having an opening closer to the second opening than the first opening and the third opening.

8. The batch heat treatment furnace according to claim 1, wherein: It has: a pair of exhaust flow adjustment blocks, which can close at least a part of the fourth opening, the fifth opening, and at least a part of the sixth opening, and form a gap of variable width therebetween across the exhaust pipe center axis which is the center axis of the first exhaust pipe, the second exhaust pipe and the third exhaust pipe, the fourth opening being an opening outside the furnace of the first exhaust flow path formed inside the first exhaust pipe, the fifth opening being an opening outside the furnace of the second exhaust flow path formed between the first exhaust pipe and the second exhaust pipe, and the sixth opening being an opening outside the furnace of the third exhaust flow path formed between the second exhaust pipe and the third exhaust pipe.

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