Heat treatment equipment

Abstract

To provide a heat treatment apparatus which has a structure that is unlikely to become complicated and can solve problems such as energy loss.SOLUTION: A heat treatment apparatus 10 comprises a treatment tank 11 which can at least execute cooling treatment to an object. The treatment tank 11 comprises: an inner wall 15 which surrounds an opening part 12; a heat insulation material 16 which is arranged at the outside of the inner wall 15; and an end face material 20 which forms an end face 20a around the opening part 12. A material of the end face material 20 has a thermal conductivity lower than that of the inner wall 15.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat treatment apparatus.

Background Art

[0002] In the field of metal heat treatment, for the purpose of preventing aging deformation in steel and improving wear resistance and hardness, sub-zero treatment is performed in which quenched steel is rapidly cooled to 0°C or lower (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In sub-zero treatment, the general cooling temperature is about -80°C. However, as ultra sub-zero treatment, the demand for cooling performance below -100°C is increasing, and requirements for -196°C to -120°C are also seen. In addition, there is also a requirement to perform a low-temperature tempering treatment in which heating is performed at about +200°C in combination with sub-zero treatment.

[0005] When sub-zero treatment and low-temperature tempering treatment are performed in separate apparatuses, it is necessary to provide two apparatuses in terms of cost and space, and labor for transferring the processed products is also generated. For this reason, it is desirable that a single heat treatment apparatus can handle temperatures from ultra sub-zero treatment to low-temperature tempering treatment (-196°C to +200°C).

[0006] To ensure the thermal insulation of the processing tank, insulation material may be filled into the walls of the tank. In addition, a gasket may be placed between the processing tank and the lid to ensure airtightness of the space in which the object to be processed is placed. In this case, the internal structure of the wall or the structure between the processing tank and the lid becomes complex, and if the temperature range that changes during heat treatment becomes wide, the effect of distortion of the structural material due to thermal contraction and thermal expansion becomes greater. Furthermore, if frost forms on the outside of the processing tank at low temperatures, or if the outside of the processing tank overheats at high temperatures, problems such as energy loss may occur.

[0007] This invention was proposed in view of the above-mentioned conventional circumstances, and aims to provide a heat treatment apparatus that is less complex in structure and can solve problems such as energy loss. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides the following means. [1] A heat treatment apparatus comprising a treatment tank capable of at least cooling an object, wherein the treatment tank comprises an inner wall surrounding an opening, an insulating material disposed on the outside of the inner wall, and an end face material forming the end face around the opening, wherein the material of the end face material has a lower thermal conductivity than the material of the inner wall. [2] The heat treatment apparatus according to [1], characterized in that the material of the end face material has a higher specific heat than the material of the inner wall. [3] The heat treatment apparatus according to [1] or [2], wherein the treatment tank comprises an outer wall covering the outside of the insulating material and a reinforcing member connecting the inner wall and the outer wall, and the material of the reinforcing member has a lower thermal conductivity than the material of the inner wall. [4] The heat treatment apparatus according to [3], characterized in that the material of the reinforcing material has a higher specific heat than the material of the inner wall. [5] The heat treatment apparatus according to any one of [1] to [4], wherein the heat treatment apparatus comprises a lid that faces the treatment tank and closes the opening, and a packing disposed between the lid and the end face material, and the position in which the packing contacts the end face material is such that the packing faces the insulating material or faces outward from the insulating material. [6] The heat treatment apparatus according to any one of [1] to [5], characterized in that the temperature inside the treatment tank is controlled within the range of -196°C to +200°C. [7] The heat treatment apparatus according to any one of [1] to [6], comprising a lid facing the treatment tank and closing the opening, and a packing disposed between the lid and the end face material, wherein the end face of the end face material facing the lid is flat, and the opposing surface of the lid facing the end face material is flat. [Effects of the Invention]

[0009] According to the heat treatment apparatus of the present invention, the structure is less likely to become complex, and problems such as energy loss can be solved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a longitudinal cross-sectional view showing an example of the heat treatment apparatus of this embodiment. [Figure 2] This is a perspective view showing the main parts of the heat treatment apparatus of this embodiment. [Figure 3] This is a perspective view showing the main components of a proportional heat treatment apparatus. [Figure 4] This is a cross-sectional view showing an example of the heat treatment apparatus of this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the drawings may schematically show key features for clarity. The number and dimensional ratios of each component may not be the same as in reality. Furthermore, the materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not necessarily limited to them. It can be implemented with appropriate modifications without changing the essence of the invention.

[0012] Figure 1 is a longitudinal cross-sectional view showing an example of the heat treatment apparatus 10 of this embodiment. Figure 2 is a perspective view showing the main parts of the heat treatment apparatus of this embodiment. Figure 3 is a perspective view showing the main parts of the proportional heat treatment apparatus. Figure 4 is a transverse cross-sectional view showing an example of the heat treatment apparatus 10 of this embodiment.

[0013] As shown in Figure 1, the heat treatment apparatus 10 of this embodiment includes a treatment tank 11 capable of at least cooling an object (not shown). The object is an object to be heat treated. The treatment tank 11 has an opening 12 for placing the object into the treatment tank 11 and an internal space 13 for housing the object in the treatment tank 11.

[0014] The processing tank 11 allows objects to be moved in and out of the internal space 13 through the opening 12. Furthermore, the processing tank 11 can heat-treat objects while they are contained within the internal space 13. The heat treatment preferably includes at least a cooling process, and may also include a heating process.

[0015] The processing tank 11 has walls 14 surrounding the internal space 13. In the illustrated example, the walls 14 include a side wall portion 14a located on the side closer to the opening 12 and a facing wall portion 14b located opposite the opening 12. If the opening 12 faces upward towards the processing tank 11, the facing wall portion 14b may be the bottom wall portion. If the opening 12 faces forward towards the processing tank 11, the facing wall portion 14b may be the back wall portion.

[0016] The shape of the processing tank 11 is not particularly limited, and examples include a prismatic shape, a cylindrical shape, etc. The shape of the opening 12 is not particularly limited, and may be a polygon such as a rectangle, or a curved figure such as a circle.

[0017] The wall 14 of the processing tank 11 has an inner wall 15 surrounding the opening 12 and a heat insulating material 16 disposed outside the inner wall 15. Further, the wall 14 in the illustrated example has an outer wall 17 outside the heat insulating material 16. In this case, the heat insulating material 16 is filled between the inner wall 15 and the outer wall 17. Specific examples of the heat insulating material 16 are not particularly limited, and examples include glass wool, rock wool, etc. Other materials may be used as long as they are materials excellent in heat resistance and cold resistance according to the use of the processing tank 11.

[0018] The inner wall 15 in the illustrated example includes an inner wall frame 15f and an inner wall plate 15p as shown in FIG. 2. Further, the outer wall 17 in the illustrated example includes an outer wall frame 17f and an outer wall plate 17p as shown in FIG. 2. In this case, the inner wall frame 15f and the outer wall frame 17f serve as a skeleton portion for maintaining the shape in which the processing tank 11 surrounds the internal space 13. Also, the inner wall plate 15p and the outer wall plate 17p are plate materials for making the processing tank 11 have a sealed structure for the internal space 13.

[0019] The structure of the wall 14 is not limited to the illustrated example, and various structures can be adopted. Examples of the materials of the inner wall 15 and the outer wall 17 include iron and iron alloys such as stainless steel (SUS304) and carbon steel. As the structural material of the wall 14, other materials may be used as long as they can withstand the temperature of the heat treatment. Also, when using a chemical such as a gas having reactivity during the heat treatment, a material that does not react with the chemical is preferable.

[0020] From the viewpoint of durability against low-temperature brittleness, it is preferable to use stainless steel such as SUS304 for at least the inner wall plate 15p. Since the heat treatment apparatus 10 is generally installed in a factory or the like, from the viewpoint of durability against the installation environment, it is also preferable to use stainless steel such as SUS304 for the outer wall plate 17p.

[0021] The inner wall frame 15f and outer wall frame 17f can be made of materials appropriate to the strength required for the skeletal structure, ease of processing such as cutting and welding, and cost. Iron and iron alloys other than stainless steel may also be used for the skeletal structure. By sealing both the inner and outer sides of the skeletal structure with the inner wall plate 15p and outer wall plate 17p, outside air is prevented from entering the interior of the wall 14, thereby suppressing moisture accumulation and condensation / freezing during cooling.

[0022] As shown in Figure 1, the heat treatment apparatus 10 of this embodiment includes an end face material 20 that constitutes the end face 20a around the opening 12. The material of the end face material 20 has a lower thermal conductivity than the material of the inner wall 15.

[0023] In the example shown in Figure 2, there is a gap between the inner wall 15 and the outer wall 17 at the position of the end face material 20. For example, when the inner wall 15, such as the inner wall frame 15f or inner wall plate 15p, is made of metal, resin can be used as the material for the end face material 20. If the thermal conductivity depends on temperature, the thermal conductivity at around room temperature, such as 20-25°C, may be compared.

[0024] In the proportional relationship shown in Figure 3, the material of the end face material 18 that constitutes the end face of the wall 14 is a material having the same thermal conductivity as the inner wall 15. For example, when the inner wall frame 15f and the inner wall plate 15p are made of metal, metal can be used as the material for the end face material 18 in the proportional relationship. Note that in Figures 2 and 3, the illustration of the insulation material 16 that is filled between the inner wall 15 and the outer wall 17 is omitted.

[0025] When cooling is performed in the processing tank 11, the inner wall 15 is also cooled. Conversely, when heating is performed in the processing tank 11, the inner wall 15 is also heated. In the proportional end face material 18, due to its high thermal conductivity, heat transfer from the inner wall 15 to the outside through the end face material 18 is likely to occur. During cooling, cold and heat are easily transferred from the inside to the outside (and heat from the outside to the inside), causing the temperature of the end face material 18 to decrease easily. Conversely, during heating, heat is easily transferred from the inside to the outside, causing the temperature of the end face material 18 to increase easily.

[0026] In the heat treatment apparatus 10 of this embodiment, the inner wall 15 and the outer wall 17 are thermally separated by the end face material 20 and the heat insulating material 16, which have low thermal conductivity. Therefore, heat conduction between the inner wall 15 and the outer wall 17 can be suppressed. Even when the inside of the treatment tank 11 is undergoing cooling treatment, the effects of temperature drops in the outer wall 17, such as frost formation, can be suppressed. Similarly, even when the inside of the treatment tank 11 is undergoing heating treatment, the effects of temperature increases in the outer wall 17, such as overheating, can be suppressed. In the same case, if the wall 14 of the treatment tank 11 has an external structure different from the outer wall 17 in the illustrated example on the outside of the heat insulating material 16, heat conduction between the inner wall 15 and the external structure of the treatment tank 11 can be suppressed, and frost formation, overheating, etc., can be suppressed.

[0027] It is preferable that the material of the end face material 20 has a higher specific heat than the material of the inner wall 15. By having a higher specific heat of the end face material 20 than that of the inner wall 15, even if the temperature of the inner wall 15 changes due to the effects of heat treatment, the temperature change of the end face material 20 can be suppressed. If the specific heat is temperature-dependent, the specific heat at around room temperature, such as 20-25°C, may be compared.

[0028] Specific examples of the end face material 20 include thermosetting resins such as bakelite (phenolic resin). The resin may be impregnated into a fibrous substrate such as paper, cloth, or glass. Other materials may be used as long as they have excellent heat resistance and cold resistance suitable for the application of the processing tank 11, and fillers may be blended into the resin.

[0029] The end face material 20 described above allows for maintaining a small temperature difference between the end face material 20 and the outer wall 17 for a longer period. This also suppresses heat conduction between the outer wall 17 and the end face material 20. For example, even if the outer wall 17 is made of a material with high thermal conductivity and low specific heat, such as metal, heat conduction between the inner wall 15 and the outer wall 17 can be effectively suppressed. The same applies when the wall 14 of the processing tank 11 has an external structure different from the outer wall 17 in the illustrated example on the outside of the insulation material 16.

[0030] As shown in Figure 1, the heat treatment apparatus 10 of this embodiment includes a reinforcing member 21 that connects the inner wall 15 and the outer wall 17. The material of the reinforcing member 21 is preferably a material with a lower thermal conductivity than the material of the inner wall 15. For example, when the inner wall 15 is made of metal, resin can be used as the material for the reinforcing member 21. If the thermal conductivity depends on temperature, the thermal conductivity at around room temperature, such as 20-25°C, may be compared.

[0031] Similar to the end face material 20 described above, the reinforcing material 21 is also a member that connects the inner wall 15 and the outer wall 17. Because the reinforcing material 21 is made of a material with a lower thermal conductivity than the material of the inner wall 15, the inner wall 15 and the outer wall 17 are thermally separated by the end face material 20, the reinforcing material 21, and the insulating material 16, which have low thermal conductivity. As a result, heat conduction between the inner wall 15 and the outer wall 17 can be suppressed.

[0032] Furthermore, it is preferable that the material of the reinforcing material 21 has a higher specific heat than the material of the inner wall 15. By having a higher specific heat than the inner wall 15, even if the inner wall 15 experiences a temperature change due to heat treatment, the temperature change of the reinforcing material 21 can be suppressed. If the specific heat is temperature-dependent, the specific heat at around room temperature, such as 20-25°C, may be compared.

[0033] Specific examples of the reinforcing material 21 include thermosetting resins such as bakelite (phenolic resin). The resin may be impregnated into a fibrous substrate such as paper, cloth, or glass. Other materials may be used as long as they have excellent heat resistance and cold resistance suitable for the application of the processing tank 11, and fillers may be blended into the resin. The material of the reinforcing material 21 may be the same as or different from the material of the end face material 20.

[0034] The reinforcing material 21 described above allows for maintaining a small temperature difference between the reinforcing material 21 and the outer wall 17 for a longer period of time. This also suppresses heat conduction between the outer wall 17 and the reinforcing material 21. For example, even if the outer wall 17 is made of a material with high thermal conductivity and low specific heat, such as metal, heat conduction between the inner wall 15 and the outer wall 17 can be effectively suppressed.

[0035] In the processing tank 11, it is preferable that the end face material 20 is arranged so that the entire end face 20a of the wall 14 surrounding the opening 12 is composed of the end face material 20, extending around the entire circumference of the opening 12. In the illustrated example, the end face material 20 is positioned on the end face where the side wall portion 14a is furthest from the opposing wall portion 14b, so that the opening area of ​​the opening 12 is approximately equal to the cross-sectional area of ​​the internal space 13. Although not specifically shown, if a wall portion extends parallel to the opposing wall portion 14b from the end face of the side wall portion 14a on the same plane as the opening 12, it is also possible to arrange the end face material 20 on that extended wall portion. In this case, the opening area of ​​the opening 12 can be set to be smaller than the cross-sectional area of ​​the internal space 13.

[0036] The arrangement of the reinforcing material 21 in the processing tank 11 can be appropriately set in a part of the gap filled with the heat insulating material 16. For example, between the opening 12 of the processing tank 11 and the opposing wall 14b, the reinforcing material 21 may be placed in two locations, near the opening 12 and near the opposing wall 14b, as shown in Figure 1. In the side wall 14a surrounding the internal space 13 of the processing tank 11, the reinforcing material 21 may be placed in one or more locations on each surface of the wall 14, as shown in Figure 4.

[0037] The heat treatment apparatus 10 of this embodiment may include a lid 22 that faces the treatment tank 11 and closes the opening 12, as shown in Figure 1. The outer circumference of the lid 22 is positioned facing the end face 20a of the end face material 20. Preferably, the heat treatment apparatus 10 includes a packing 23 positioned between the lid 22 and the end face material 20.

[0038] When the inner wall 15 undergoes a temperature change during heat treatment, the end face material 20 in contact with the inner wall 15 also experiences a certain degree of temperature change. Furthermore, if the components of the wall 14, such as the inner wall 15, undergo thermal contraction or expansion, the airtightness of the heat treatment apparatus 10 may decrease due to the effects of strain. By placing a packing 23 between the end face material 20 and the lid 22, the effects of strain can be absorbed and mitigated.

[0039] The material of the packing 23 is not particularly limited, but examples include soft synthetic resins, rubber such as silicone, and elastomers. The cross-sectional shape of the packing 23 is not particularly limited, but hollow packings such as P-type, D-type, and tomoe-type (a-type) are preferred.

[0040] To airtightly seal the opening 12 using the lid 22, the packing 23 must be evenly and tightly fitted to the end face 20a around the opening 12. By using the end face material 20 described above, even if temperature changes occur in the inner wall 15 during heat treatment, temperature changes in the outer wall 17 can be suppressed. Therefore, the effect of distortion of the structural material due to thermal contraction and thermal expansion associated with temperature changes is reduced, and the deterioration of the airtightness of the heat treatment apparatus 10 in the lid 22 can be suppressed.

[0041] The packing 23 can also be fixed to the end face 20a side of the processing tank 11, but it is preferable to fix the packing 23 to the lid 22. Examples of fixing members for fixing the packing 23 to the lid 22 or the processing tank 11 include bolts.

[0042] The position where the packing 23 contacts the end face material 20 is preferably such that the packing 23 faces the insulation material 16 or faces outward from the insulation material 16. Compared to the case where the packing 23 faces the inner wall 15, the dimensions of the end face material 20 placed between the packing 23 and the inner wall 15 can be made larger. This makes it possible to suppress temperature changes in the packing 23 even if temperature changes occur in the inner wall 15 during heat treatment.

[0043] The end face 20a of the end face material 20 that faces the lid 22 is preferably flat. Similarly, the opposing surface 22a of the lid 22 that faces the end face material 20 is preferably flat. When the end face 20a and the opposing surface 22a are flat, the packing 23 can more easily absorb and mitigate the effects of strain compared to when there are grooves or other irregularities on the end face 20a and the opposing surface 22a, thereby suppressing the effects of strain due to temperature changes and the decrease in airtightness. In particular, when the cooling temperature is low, such as below -50°C, even if the packing 23 hardens at low temperatures and its flexibility decreases, it is easier to maintain airtightness between flat surfaces.

[0044] The internal temperature of the processing tank 11 can be controlled within a desired range as required for the heat treatment of the object. The cooling temperature is not particularly limited, but examples include -200°C or higher, -150°C or higher, -100°C or higher, -50°C or higher, etc. The heating temperature is not particularly limited, but examples include +200°C or lower, +150°C or lower, +100°C or lower, etc. The internal temperature of the processing tank 11 may be controlled within the range of -196°C to +200°C. This makes it possible to handle everything from ultra-subzero treatment to low-temperature tempering treatment with the same heat treatment apparatus 10.

[0045] According to the heat treatment apparatus 10 of this embodiment, temperature changes in the external structure of the treatment tank 11, such as the outer wall 17, can be suppressed, thereby reducing temperature drops during cooling and temperature increases during heating. The temperature of the external structure of the treatment tank 11 can be maintained at approximately the same level as room temperature without the need to heat the external structure of the treatment tank 11 during cooling or to dissipate heat from the external structure of the treatment tank 11 during heating. Since distortion of the external structure of the treatment tank 11 due to temperature changes is reduced, the airtightness of the heat treatment apparatus 10 can be ensured without complicating the structure or function of the heat treatment apparatus 10.

[0046] As for the internal structure of the lid 22, although not specifically shown in the figures, it is preferable that the inside of the lid 22 is filled with insulating material 16, similar to the walls 14 of the processing tank 11. The walls of the lid 22 may consist of an inner wall 15 and an outer wall 17. The inner wall 15 of the lid 22 may consist of an inner wall frame 15f and an inner wall plate 15p. The outer wall 17 of the lid 22 may consist of an outer wall frame 17f and an outer wall plate 17p.

[0047] Although not specifically shown, it is preferable that the lid 22 is connected to the processing tank 11 using hinges or the like. The entire opening 12 may be covered with a single lid 22, or multiple lids 22 may be combined to cover the opening 12. From the viewpoint of making the end face 20a of the processing tank 11 and the opposing surface 22a of the lid 22 flat, it is preferable that the structure connecting the processing tank 11 and the lid 22 be located on an external structure such as an outer wall 17. Although not specifically shown, the lid 22 may be provided separately from the processing tank 11 and detachably attached. It is also possible to close the internal space 13 by combining two processing tanks 11 so that their openings 12 face each other.

[0048] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. Modifications include adding, substituting, omitting, or otherwise changing the components in each embodiment. [Examples]

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples described later.

[0050] In the walls 14 of the processing tank 11, SUS304 stainless steel was used for the inner wall plate 15p and the outer wall plate 17p, and iron was used for the inner wall frame 15f and the outer wall frame 17f. Furthermore, 10 mm thick bakelite (phenol resin) was used for the end face material 20 and the reinforcing material 21, 160 mm thick rock wool was used for the insulation material 16, and silicone rubber was used for the packing material.

[0051] As shown in Figure 1, the reinforcing members 21 are placed in two locations on the two sides consisting of the left and right side walls 14a, which form a rectangle including the opening 12 of the processing tank 11 and the opposing wall portion 14b: near the opening 12 and near the opposing wall portion 14b.

[0052] The position of the reinforcing member 21 near the opening 12 was selected so that the reinforcing member 21 could be fixed to the inner wall plate 15p and the outer wall plate 17p, within a range where the reinforcing member 21 does not come into contact with the end face material 20, as shown in Figure 2. The position of the reinforcing member 21 near the opposing wall portion 14b is not specifically shown, but similar to Figure 1, a position was selected within the range of the side wall portion 14a, at the point furthest from the opening 12, so that the reinforcing member 21 could be fixed to the inner wall plate 15p and the outer wall plate 17p. In the cross-sectional view shown in Figure 4, the arrangement of the reinforcing member 21 was such that each side of the four sides of the side wall portion 14a forming a rectangle around the internal space 13 was divided into three equal parts.

[0053] The method for attaching the reinforcing member 21 is as follows: With the opening 12 facing the upper side of the processing tank 11, the reinforcing member 21 is fixed to the inner wall frame 15f and the outer wall frame 17f with bolts while the inner wall frame 15f and the outer wall frame 17f are positioned to satisfy the following conditions (1) to (3).

[0054] (1) The height of the upper surface of the inner wall frame 15f and the height of the upper surface of the outer wall frame 17f are the same. (2) When viewed from above facing the opening 12, the clearance between the inner wall frame 15f and the outer wall frame 17f is uniform. (3) The reinforcing members 21 intersect perpendicularly with respect to the inner wall frame 15f and the outer wall frame 17f of the tank, and the reinforcing members 21 are positioned horizontally.

[0055] <Cooling Treatment Test> In the heat treatment apparatus 10 of the embodiment, after lowering the internal temperature of the treatment tank 11 to -150°C and maintaining the -150°C state for 1 hour, it was confirmed that airtightness could be ensured between the treatment tank 11 and the lid 22, and that the surface temperature of the outer wall 17 of the treatment tank 11 was about the same as room temperature, and that no frost was formed on the outer wall 17.

[0056] <Heat treatment test> In the heat treatment apparatus 10 of the embodiment, after raising the internal temperature of the treatment tank 11 to +200°C and maintaining the +200°C state for 1 hour, it was confirmed that the surface temperature of the outer wall 17 of the treatment tank 11 was about the same as room temperature, and that it was safe to touch with bare hands, confirming that the outer wall 17 was not overheated. [Explanation of symbols]

[0057] 10... Heat treatment apparatus, 11... Treatment tank, 12... Opening, 13... Internal space, 14... Wall, 14a... Side wall section, 14b... Opposing wall section, 15... Inner wall, 15f... Inner wall frame, 15p... Inner wall plate, 16... Insulation material, 17... Outer wall, 17f... Outer wall frame, 17p... Outer wall plate, 18... Ratioly proportional end face material, 19... Ratioly proportional reinforcing material, 20... End face material, 20a... End face, 21... Reinforcing material, 22... Lid, 22a... Opposing surface, 23... Packing.

Claims

1. A heat treatment apparatus comprising a treatment tank capable of at least cooling the object, The processing tank comprises an inner wall surrounding an opening, an insulating material disposed outside the inner wall, an end face material forming the end face around the opening, an outer wall covering the outside of the insulating material, and a reinforcing member connecting the inner wall and the outer wall. The material of the end face material is resin, and has a lower thermal conductivity than the material of the inner wall. A heat treatment apparatus characterized in that the material of the reinforcing material is resin and has a lower thermal conductivity than the material of the inner wall.

2. The heat treatment apparatus according to claim 1, characterized in that the material of the end face material has a higher specific heat than the material of the inner wall.

3. The heat treatment apparatus according to claim 1, characterized in that the material of the reinforcing material has a higher specific heat than the material of the inner wall.

4. The heat treatment apparatus according to claim 1, characterized in that the temperature inside the treatment tank is controlled within the range of -196°C to +200°C.

5. The heat treatment apparatus comprises a lid that faces the treatment tank and closes the opening, and a packing that is disposed between the lid and the end face material. The heat treatment apparatus according to any one of claims 1 to 4, characterized in that the position where the packing contacts the end face material is a position where the packing faces the heat insulating material or a position where it faces outward from the heat insulating material.

6. The heat treatment apparatus comprises a lid that faces the treatment tank and closes the opening, and a packing that is disposed between the lid and the end face material. The heat treatment apparatus according to any one of claims 1 to 4, characterized in that the end face of the end face material facing the lid is flat, and the opposing surface of the lid facing the end face material is flat.

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