Heat treatment container

Abstract

To provide a heat treatment container in which thermal shock can be relaxed, load resistance can be secured, and container cracking or the like can be suppressed.SOLUTION: A heat treatment container 1 is a box-shaped heat treatment container that comprises a planar bottom wall part 2 and side wall parts 3 erected from the bottom wall part 2, and stores a heat treatment object in a space surrounded with the bottom wall part 2 and the side wall parts 3, in which at least a part of the outer circumferential part of the bottom wall part 2 is provided with a projection part 4 projecting from the outermost peripheral edge of each side wall part 3 to the outside in plan view, and that is an integrally molded article in which the bottom wall part 2, the side wall parts 3 and the projection part 4 are integrally molded.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat treatment vessel, and more particularly to a heat treatment vessel that contains an object to be heat-treated, is transported in one direction within a continuous heating furnace, and is used to heat-treat the object to be heat-treated. [Background technology]

[0002] A continuous heating furnace is a heating furnace that continuously heat-treats objects while transporting them. A type of continuous heating furnace is one that heat-treats objects while transporting them by rotating multiple transport rollers. Such continuous heating furnaces are also called roller hearth kilns.

[0003] For example, roller hearth kilns use heat treatment containers to house heat treatment objects such as parts and powders and heat treat them at high temperatures. The roller hearth kiln is, for example, composed of a preheating section, a baking section, and a cooling section along its entire length, and multiple heat treatment containers are continuously transported in one direction. During transport, the heat treatment containers are aligned in the transport direction and in a direction perpendicular to the transport direction so that many products can be placed in the baking section to improve productivity, and the containers are transported in close contact with each other.

[0004] Conventionally, a technology disclosed in Patent Document 1 has been proposed to prevent damage caused by contact between heat treatment containers during transportation. The heat treatment container (sagger) described in Patent Document 1 is a sagger that contains lithium positive electrode material powder and is placed in a heat treatment furnace to heat treat the powder. This sagger is made of a nickel-based alloy, and when viewed from above, the size of the upper end of the sagger is smaller than the size of the bottom. This prevents the weaker upper ends of the saggers from coming into contact with each other during transportation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7277662 [Patent Document 2] Korean Patent Publication No. 10-2013-0117272 [Patent Document 3] Japanese Patent Publication No. 2023-82822 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, in heat treatment in a roller hearth kiln, the heat treatment containers are heated and then cooled while in close contact with each other. This can trap heat in the contacted areas, making it difficult for the heat treatment container and the workpiece to cool in the cooling area, leading to cracks due to thermal shock. As a result, this can cause transport problems, such as the heat treatment object leaking from the heat treatment container adhering to the transport rollers or broken pieces of the container getting caught between the transport rollers. Meanwhile, the heat treatment container is subjected to a large load (also known as line pressure) in the transport direction during transport, and it is therefore required to be strong enough to withstand this load.

[0007] In the above-mentioned Patent Document 1, damage caused by contact between heat treatment containers during transportation is considered, but the thermal shock and load resistance of the heat treatment containers themselves are not considered.

[0008] Furthermore, Patent Document 2 describes providing protrusions on the outer periphery of the containers to separate them, thereby facilitating the movement of gas within the continuous heating furnace, but does not consider load-bearing capacity, etc. Furthermore, Patent Document 3 describes an assembled sagger in which one bottom plate and multiple side plates are assembled into a box shape, but it is believed that there is room for improvement in terms of load-bearing capacity.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide a heat treatment container that can mitigate thermal shock, ensure load-bearing capacity, and prevent the container from cracking. [Means for solving the problem]

[0010] The heat treatment container of the present invention is a box-shaped heat treatment container comprising a plate-shaped bottom wall portion and a side wall portion erected from the bottom wall portion, and accommodating an object to be heat-treated in the space surrounded by the bottom wall portion and the side wall portion, characterized in that at least a portion of the outer periphery of the bottom wall portion has a protrusion portion that protrudes outward from the outermost peripheral edge of the side wall portion in a planar view, and that the bottom wall portion, the side wall portion, and the protrusion portion are integrally molded.

[0011] At the outer peripheral position where the protrusion is located, at least one of the connecting portions selected from the connecting portion between the upper end surface of the protrusion and the outer peripheral surface of the side wall portion, and the connecting portion between the inner peripheral surface of the side wall portion and the upper surface of the bottom wall portion has a thick portion.

[0012] The protrusion has a shape in which its upper and lower ends are positioned within the thickness range of the bottom wall.

[0013] The heat treatment container is characterized by being a molded article made of a heat-resistant inorganic material.

[0014] The bottom wall portion is rectangular, the side wall portion is a rectangular side wall portion erected from the four sides of the bottom wall portion, and the length of the protrusion portion is 1 / 4 or more of the length of the side of the bottom wall portion on which the protrusion portion is located.

[0015] The protrusion has a convex portion provided on the upper end surface of the protrusion.

[0016] The object to be heat-treated is a lithium-ion battery material.

[0017] The heat treatment vessel is characterized in that it is used in a roller hearth kiln. [Effects of the Invention]

[0018] The heat treatment container of the present invention is box-shaped and includes a plate-shaped bottom wall and side wall. At least a portion of the outer periphery of the bottom wall has a protrusion that protrudes outward from the outermost periphery of the side wall in a plan view. This creates a gap between the side wall of adjacent containers during transport, for example, in a continuous heating furnace, reducing heat accumulation and thermal shock, thereby preventing container cracking. Furthermore, because the protrusion is located on the outer periphery of the bottom wall, the bottom wall, which bears the heaviest load, can bear the load, preventing container cracking. Furthermore, the protrusion blocks powder and broken pieces of the container caused by overflowing heat treatment objects, preventing them from entering or adhering to equipment below the container (e.g., conveying rollers). Furthermore, because the heat treatment container is a single-piece molded product consisting of all components, there is no risk of cracking at the joints, as occurs when side wall sections are molded and joined separately, as in Patent Document 3, and manufacturing costs can also be reduced.

[0019] When a load is received by the protrusions and applied to the lower part of the container, including the protrusions and bottom wall, by providing thick sections at each connecting section where the side walls rise, it is possible to prevent cracks from occurring at these sections. Furthermore, when transporting heat treatment containers, particularly in the case of a roller hearth kiln, the heat treatment containers may tilt rather than stand upright, and even if the side walls of adjacent containers come into contact with each other due to this tilt, cracks in the side walls (particularly at the rising sections of the side walls) can be prevented.

[0020] Since the upper and lower ends of the protrusion are located within the thickness range of the bottom wall, when the protrusion receives a load, the load from the protrusion is applied to the bottom wall, and no direct load is applied from the protrusion to the side wall, thereby preventing cracks in the side wall.

[0021] In a rectangular heat treatment container, if the length of the protrusion is at least a certain level, a gap can be stably maintained between the side walls of adjacent containers.

[0022] The protrusion on the upper end surface of the protrusion allows powder caused by overflow of the heat treatment object and broken fragments of the container to be retained between the protrusion and the side wall, preventing leakage or falling below the container.

[0023] Even when a material that easily accelerates deterioration of the heat treatment container is used as the heat treatment object, or when a lithium positive electrode material is used and the container deteriorates (becomes embrittled) due to penetration of the material, the specified protrusions make it easier to maintain thermal shock resistance and crack strength. In addition, the lithium positive electrode material can be prevented from adhering to the conveying rollers of a roller hearth kiln, thereby preventing deterioration of the rollers of the roller hearth kiln. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a plan view showing a schematic configuration of a continuous heating furnace to which an example of a heat treatment container of the present invention is applied. [Figure 2] FIG. 2 is a perspective view showing an example of the heat treatment container of FIG. [Figure 3] 2A and 2B are a plan view and a cross-sectional view of the heat treatment container of FIG. 1. [Figure 4] FIG. 10 is an enlarged cross-sectional view showing another example of a heat treatment container. [Figure 5] 2 is a schematic view showing an example of pressure molding for producing the heat treatment container of FIG. 1. FIG. [Figure 6] 1 is a schematic diagram for explaining the effects of the heat treatment container of the present invention. FIG. [Figure 7] FIG. 10 is a plan view showing the positional relationship between another example of a heat treatment container of the present invention and another adjacent heat treatment container. [Figure 8] FIG. 10 is a plan view showing the positional relationship between another example of a heat treatment container of the present invention and another adjacent heat treatment container. [Figure 9] FIG. 4 is a cross-sectional view of another example of a heat treatment container according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Fig. 1 is a plan view showing the schematic configuration of a continuous heating furnace to which an example of a heat treatment container of the present invention is applied. The heat treatment furnace 51 is a roller hearth kiln having a plurality of conveying rollers 52. The conveying rollers 52 are cylindrical rollers arranged in parallel and at equal intervals within the heat treatment furnace 51, and are made of a sintered body of a heat-resistant inorganic material such as Al2O3 or SiC. In the heat treatment furnace 51, the conveying rollers 52 are each synchronously driven to rotate by a drive device (not shown).

[0026] 1, a plurality of heat treatment containers 1 containing objects to be heat-treated T are placed on conveying rollers 52, and are continuously conveyed in a conveying direction F by the rotation of the conveying rollers 52. Then, in the firing section of the heat treatment furnace 51, the objects to be heat-treated T in the heat treatment containers 1 are heat-treated at a predetermined temperature, for example, in an inert gas atmosphere.

[0027] The heat treatment object T is, for example, a battery material for a lithium ion battery, a solar cell, a fuel cell, or the like, and more specifically, a lithium positive electrode material for a lithium ion battery (such as lithium cobalt oxide). In addition, a negative electrode material (carbon) for a lithium ion battery, an alumina substrate, a thermistor, or the like is also heat treated as the heat treatment object T. The heat treatment object T is in the form of, for example, powder or pellet. The lithium positive electrode material and negative electrode material for a lithium ion battery are sometimes collectively referred to as lithium ion battery material.

[0028] 1, in the heat treatment furnace 51, multiple heat treatment containers 1 are aligned in the transport direction F and in a direction perpendicular to the transport direction, and are transported with the containers in close contact with each other front to back and left to right. In FIG. 1, the heat treatment containers 1 are aligned in four rows in the transport direction F and three rows in the direction perpendicular to the transport direction. By aligning them in this manner, the multiple heat treatment containers 1 are heated uniformly, reducing temperature variations between the containers during heat treatment.

[0029] On the other hand, if the containers are in close contact with each other, the heat treatment container 1 may not cool easily in the cooling section of the heat treatment furnace 51, and cracks may occur due to thermal shock. As a countermeasure against this, the heat treatment container 1 according to the present invention is provided with predetermined protrusions 4. The heat treatment container 1 will be described with reference to FIGS. 2 and 3.

[0030] Fig. 2 is a perspective view of the heat treatment container, and Fig. 3 is a plan view and a cross-sectional view of the heat treatment container. As shown in Fig. 2, the heat treatment container 1 comprises a plate-shaped bottom wall 2 and a side wall 3 extending upright from the bottom wall 2. As shown in Fig. 1, an object to be heat-treated is accommodated in the space surrounded by the bottom wall 2 and the side wall 3. The heat treatment container 1 has a box-like shape with an open top.

[0031] The heat treatment vessel 1 has protrusions 4 that protrude outward from the outermost peripheral edge of the side wall 3 in a plan view on at least a part of the outer periphery of the bottom wall 2. In the heat treatment vessel 1, the protrusions 4 are formed around the entire outer periphery of the bottom wall 2, and the outer periphery of the bottom wall 2 is made slightly larger by the protrusions 4. In this case, the length L of the protrusions 4 is b is the length L of the side of the bottom wall 2 where the protrusion 4 is located a (See Figure 3) b >L a ) In addition, the length L of the protrusion 4 here b is the length parallel to the length of the side of the bottom wall 2, and if the protrusion is divided in the length direction, it refers to the total length of each divided part (see, for example, Figure 8). By having these protrusions 4, the heat treatment container 1 can form a gap between the side wall parts 3 of adjacent containers.

[0032] FIG. 3(a) shows a plan view. As shown in FIG. 3(a), in the heat treatment vessel 1, the bottom wall 2 is rectangular, and the side wall 3 is a rectangular side wall portion erected from the four sides of the bottom wall 2. The side portions 3A, 3B, 3C, and 3D constituting the side wall 3 have the same thickness w and height and are connected to each other at locations corresponding to the corners of the rectangle. In FIG. 3(a), the inner circumferential surfaces of the side portions (e.g., 3A and 3B) are connected by a curved surface having a predetermined radius of curvature r. The radius of curvature r is not particularly limited, but is set, for example, to be larger than the thickness w at the upper end of each side portion. Note that in FIG. 3(a), the outer circumferential surfaces of the side portions (e.g., 3A and 3B) are connected by an inclined plane inclined with respect to the extension direction of each side portion, but may also be connected by a curved surface.

[0033] Figure 3(b) shows a cross-sectional view taken along line XX. As shown in Figure 3(b), the inner peripheral surface 3b of the side wall 3 is gently inclined so that the opening end opens. That is, the opening angle between the inner peripheral surface 3b and the upper surface 2a of the bottom wall 2 is larger than a right angle, and is a slight opening angle of about 1 to 3 degrees relative to the right angle. However, the opening angle between the inner peripheral surface 3b and the upper surface 2a of the bottom wall 2 is not limited to the above angle and may be a right angle.

[0034] On the other hand, the outer peripheral surface 3a of the side wall 3 extends perpendicular to the upper end surface 4a of the protrusion 4. The angle between this outer peripheral surface 3a and the upper end surface 4a of the protrusion 4 may be smaller than a right angle, so that the thickness of the side wall 3 decreases toward the upper end. If the opening angle of the outer peripheral surface 3a of the side wall 3 is larger than 90°, there is a risk that the side wall 3 will become an undercut portion when the heat treatment container 1 is removed from the mold after pressure molding, as shown in FIG. 5 described later.

[0035] As shown in FIG. 3(b), in the heat treatment vessel 1, the protrusions 4 protrude so as to extend the bottom wall 2 toward the outer periphery. In this case, the protrusions 4 protrude so as to expand at least a part of the outer periphery of the bottom wall 2 with a uniform thickness. The length of the protrusions 4 protruding outward from the outermost periphery of the side wall 3 (L in FIG. 3(b)) is c) is, for example, 10% to 120%, 10% to 80%, 10% to 50%, or 20% to 50% of the thickness of the side wall portion 3, and specifically, for example, is about 1 mm to 20 mm. a In FIG. 3(b), the upper surface 2a of the bottom wall 2 and the upper end surface 4a of the protrusion 4 are in the same plane, and the lower surface 2b of the bottom wall 2 and the lower end surface 4b of the protrusion 4 are in the same plane (in this case, flush). b is the thickness t of the bottom wall 2 a is equal to

[0036] The relationship between the protrusions 4 and the bottom wall 2 may be as shown in Fig. 4. Fig. 4 shows a partially enlarged view equivalent to the cross-sectional view of Fig. 3(b) as another example of a heat treatment vessel. In this example, the protrusions 4 are also arranged such that their upper and lower ends are spaced apart from the thickness t of the bottom wall 2. a In this case, the thickness t of the protrusion 4 is b is the thickness t of the bottom wall 2 a It is smaller than.

[0037] In FIG. 3 , a large load is applied to the heat treatment container 1 in the direction of transport during transport through a continuous heating furnace. This load is also called line pressure. The inventors analyzed the load applied to a heat treatment container during transport using a typical heat treatment container without protrusions. They found that the containers abutted strongly against each other, particularly at the bottom wall portions, which are the lower portions of the container sides, and that a large load was applied at these locations. Therefore, by providing protrusions 4, which serve to form gaps between the containers, on the outer periphery of the bottom wall portion 2, the line pressure is applied to the bottom wall portion 2, where the load is most intense. This prevents cracking of the container due to the load while still forming a gap.

[0038] As shown in FIG. 3, the heat treatment vessel 1 has upper and lower end faces 4a and 4b of the protrusion 4, each of which has a thickness t aThe protrusions 4 are positioned within the range, and when line pressure is applied to the protrusions 4, the load from the protrusions 4 is applied to the bottom wall 2, and no direct load is applied from the protrusions 4 to the side wall 3, so cracks in the side wall 3 can be suppressed.

[0039] Furthermore, the heat treatment vessel 1 preferably has a thick portion P at the connection between the inner peripheral surface 3b of the side wall 3 and the upper surface 2a of the bottom wall 2 at the outer peripheral position where the protrusion 4 is located. This thick portion P is formed by a curved surface having a predetermined curvature radius, and the thickness t of the bottom wall 2 a and is thicker than the thickness w of the side wall 3. When line pressure is applied to the protrusions 4 and a load is applied to the lower part of the container, including the protrusions 4 and the bottom wall 2, by providing the thick portion P at this connecting portion, which is the rising point of the side wall 3, damage that would originate from this point can be prevented. Furthermore, when the heat treatment container 1 is transported, particularly in the case of a roller hearth kiln, the heat treatment container 1 may tilt rather than stand upright. Even if the side walls 3 of adjacent containers come into contact due to this tilt, damage to the side wall 3 (particularly the rising points of the side wall 3) can be prevented. The thickness of the thick portion is, for example, 1% to 50%, 3% to 50%, 5% to 50%, 1% to 30%, 3% to 30%, or 5% to 30% of the original thickness of the bottom wall 2 or the side wall 3 at the thickest point. The thick portion may have an arc shape, which is a curved surface having a predetermined radius of curvature relative to the connecting portion (corner), or may have an inclined plane shape or a stepped shape, as described below.

[0040] The thickened portion may be provided at the connecting portion between the upper end of the protrusion 4 and the outer peripheral surface 3a of the side wall 3. For example, in FIG. 4, thickened portions are provided at both the connecting portions on the inner and outer peripheral sides, which are the rising portions of the side wall 3. The thickened portion on the outer peripheral side is formed by an inclined plane that connects the upper end of the protrusion 4 and the outer peripheral surface 3a of the side wall 3. This inclined plane is inclined with respect to the horizontal plane, and the inclination angle α is, for example, 30° to 60°, and may be more than 45°.

[0041] The heat treatment vessel 1 described above is an integrally molded product in which the bottom wall 2, side wall 3, and protrusions 4 are integrally molded. The material of the heat treatment vessel 1 is not particularly limited, but it is preferably formed from a heat-resistant inorganic material. Examples of heat-resistant inorganic materials include mullite-cordierite, mullite, cordierite, alumina, spinel, SiC, and aluminum titanate. The heat treatment vessel 1 is preferably formed by casting or pressure molding using a heat-resistant inorganic material.

[0042] For example, Fig. 5 shows an example of pressure molding for producing the heat treatment container of Fig. 1. Fig. 5 shows the case of uniaxial pressing, in which the mold comprises a die 5 and a pair of punches (lower punch 6 and upper punch 7) fitted into the upper and lower openings of the die 5. A raw material powder 8 containing the heat-resistant inorganic material described above is filled into the cavity formed by the die 5 and the lower punch 6, and then the upper punch 7 is lowered to compress the raw material powder 8, thereby forming a compression-molded body. Then, the upper punch 7 is raised, and the lower punch 6 is also raised, to eject the compression-molded body from the cavity.

[0043] The pressure molding method is not particularly limited, and cold isostatic pressing, hot isostatic pressing, or the like may be employed.

[0044] The resulting compression-molded body is then fed into a sintering furnace and sintered to obtain the heat treatment container of the present invention. Note that the sintering conditions are appropriately set.

[0045] Next, Figure 6 is a schematic diagram illustrating the effects of the heat treatment container described above. This figure shows heat treatment containers being transported in multiple rows in a continuous heating furnace, with gaps formed between the containers indicated in gray. As shown in Figure 6, adjacent heat treatment containers on the left, right, front, and rear abut against each other via protrusions protruding from the outer periphery of their bottom walls, forming gaps between their side walls. The gaps formed are along the transport direction F and along a direction perpendicular to the transport direction F, and these intersect. The formation of these gaps creates airflow around the containers, and the heat dissipation effect of this airflow reduces thermal shock in the heat treatment containers. As a result, cracking of the containers can be prevented.

[0046] Furthermore, the heat treatment vessel 1 shown in FIG. 6 has protrusions 4 around the entire periphery of the bottom wall, which prevent powder from overflowing from the heat treatment object, broken pieces of the vessel, and other particles from entering or adhering to the conveying rollers installed below the heat treatment vessel 1. For example, in a continuous heating furnace, if the conveying rollers become contaminated, cleaning work is required. Stopping the operation of the continuous heating furnace during cleaning work reduces productivity and increases the workload, but the protrusions 4 can effectively prevent these problems.

[0047] Other examples of the heat treatment container of the present invention will be described below with reference to FIGS.

[0048] FIG. 7 is a plan view showing the positional relationship with other adjacent heat treatment containers. Heat treatment containers 11A and 11B have the same configuration. Heat treatment container 11A includes a plate-shaped bottom wall 12 and a side wall 13 extending vertically from bottom wall 12. In this heat treatment container 11A, protrusions are not formed around the entire outer periphery of bottom wall 12, but are formed on a portion of the outer periphery of bottom wall 12. Specifically, protrusions 14A and 14B are provided at two locations around a pair of diagonally opposite corners of rectangular bottom wall 12. Protrusion 14A is formed on the outer periphery of bottom wall 12, extending from the center of side 13A to the center of side 13D, passing through the corner. Protrusion 14B is formed on the outer periphery of bottom wall 12, extending from the center of side 13B to the center of side 13C, passing through the corner. In plan view, each of the protrusions 14A and 14B is formed in an L-shape.

[0049] In the heat treatment container 11A, the length L of the protrusions 14A and 14B is b is at least half the length of the side of the bottom wall 12 on which the protrusions 14A and 14B are located.

[0050] 7, the heat treatment containers 11A and 11B are transported with their protrusions engaged with each other. Specifically, the protrusion 14B of the heat treatment container 11A is engaged in the transport direction F with the protrusion 14A protruding from another heat treatment container 11B adjacent to the heat treatment container 11A on one side in a direction intersecting the transport direction F. The protrusion 14A of the heat treatment container 11A is also engaged in the transport direction F with the protrusion protruding from another heat treatment container (not shown) adjacent to the other side.

[0051] In the heat treatment container 11A, the protrusions 14A and 14B also form gaps between the side walls of adjacent containers, thereby mitigating thermal shock. Furthermore, in the heat treatment container 11A, when the heat treatment container 11A and another heat treatment container 11B attempt to move relative to each other in the transport direction F, the protrusions 14A and 14B of the two containers engage with each other, restricting the relative movement of the heat treatment container 11A and the other heat treatment container 11B in the transport direction F, as shown in Figure 7, thereby suppressing variation in the movement of the heat treatment containers 11A and 11B.

[0052] 8 shows the positional relationship between another adjacent heat treatment container in yet another example. Heat treatment containers 21A and 21B have the same configuration. Heat treatment container 21A includes a plate-shaped bottom wall 22 and a side wall 23 extending upright from bottom wall 22. In this heat treatment container 21 as well, protrusions are formed on part of the outer periphery of bottom wall 22. Specifically, protrusions 24A to 24D are provided at four locations around each corner of rectangular bottom wall 22. For example, protrusion 24A is formed on the outer periphery of bottom wall 22, extending from a midpoint (approximately 1 / 4) of the side length of side 23A, past the corner, to a midpoint (approximately 1 / 4) of the side length of side 23D.

[0053] In the heat treatment container 21A, the length of the protrusion (L b1 and L b2 The total length of the protrusions is at least half the length of the side of the bottom wall 22 where the protrusions are located.

[0054] In the heat treatment container 21A, the protrusions 24A-24D also form gaps between the sidewalls of adjacent containers, thereby mitigating thermal shock. Furthermore, when the heat treatment container 21A is placed next to another heat treatment container 22A, a through gap 25 is formed that penetrates in a direction perpendicular to the bottom wall 22, i.e., in the up-down direction. In this case, in the heat treatment container 21A, in addition to the gaps formed between the sidewalls 23 in the front, back, left, and right directions, the through gap 25 is also formed in the up-down direction, which generates airflow in the through gap 25, thereby further mitigating thermal shock.

[0055] For example, in Fig. 8, the length of the through gap 25 can be adjusted by changing the length of the protrusion. The length of the protrusion is preferably at least ¼ of the length of the side of the bottom wall on which the protrusion is located. By ensuring that the length of the protrusion is at least a certain level, it becomes easier to stably form a gap between the side walls of adjacent containers.

[0056] FIG. 9 shows a cross-sectional view of yet another example of a heat treatment container according to the present invention. FIG. 9 shows a cross-sectional view of a heat treatment container 31. The heat treatment container 31 includes a plate-shaped bottom wall 32 and a side wall 33 extending upright from the bottom wall 32. The heat treatment container 31 has a protrusion 34 extending around the entire periphery of the bottom wall 32, protruding outward from the outermost edge of the side wall 33 in a plan view. This protrusion 34 extends further outward than the protrusion 4 in FIG. 3 above, and has a protrusion 35 extending upright from the upper end surface 34a of the protrusion 34. The heat treatment container 31 is an integrally molded product in which all parts, including the protrusion 35, are integrally molded.

[0057] The height of the convex portion 35 (based on the upper end surface 34a of the protrusion 34) is set smaller than the height of the side wall portion 33, for example, set to 1 / 2 or less.

[0058] As shown in Fig. 9, the protrusion 35 is spaced from the side wall 33 and is provided near the outer periphery of the protrusion 34. In Fig. 9, a part 34c (circled by a dotted line) of the protrusion 34 protrudes further outward from the outermost periphery of the protrusion 35 in a plan view. Note that the protrusion 34 may be formed so as to be flush with the outer periphery of the protrusion 35 without protruding in this manner. Even in this case, a sufficient gap is formed between the side wall 33 of adjacent containers, which helps to mitigate thermal shock.

[0059] By providing the convex portion 35 on the upper end surface 34a of the protrusion 34 in this way, the convex portion 35 serves as a protective wall to prevent the heat treatment object from leaking out, even if the heat treatment object suddenly boils and spills over the side wall portion 33. In other words, the heat treatment object is held between the convex portion 35 and the side wall portion 33, preventing it from leaking out or falling below the heat treatment container 31.

[0060] In the above embodiment, the shape of the convex portion is not limited to the shape shown in Fig. 9, as long as it can hold the object to be heat-treated spilling over the side wall portion between the side wall portion and the convex portion. For example, the convex portion may be inclined so that the height increases toward the outer periphery of the protrusion 34.

[0061] The heat treatment container of the present invention is not limited to the configurations explained in the drawings.

[0062] In the above, the protrusions are provided on the outer periphery of the rectangular bottom wall portion so as to protrude in each direction (specifically, four directions) of the edges that constitute the side wall portion, but the protrusions only need to be provided on at least a portion of the outer periphery of the bottom wall portion, and may also be provided so as to protrude in only one direction of the edges that constitute the side wall portion.

[0063] In addition, in the heat treatment container described above, the bottom wall portion is rectangular and the side wall portion is also rectangular to match, but this is not limited to this, and the shapes of the bottom wall portion and the side wall portion may be appropriately selected to make the heat treatment container circular, elliptical, or other polygonal in plan view. Even with such a shape, the effect of the present invention can be obtained by providing the predetermined protrusions. [Industrial Applicability]

[0064] The heat treatment vessel of the present invention can absorb thermal shock, ensure load resistance, and prevent the vessel from cracking, and therefore can be suitably used as a heat treatment vessel in, for example, a roller hearth kiln. [Explanation of symbols]

[0065] 1 Heat treatment container 2 Bottom wall 3 Side wall 4 Protrusion 5 Die 6 Upper punch 7. Lower Punch 8 Raw material powder 11A, 11B Heat treatment container 12 Bottom wall 13 Side wall 14A, 14B protrusion 21A, 21B Heat treatment container 22 Bottom wall 23 Side wall 24A, 24B, 24C, 24D protrusions 25 Through gap 31 Heat treatment container 32 Bottom wall 33 Side wall 34 Protrusion 35 Convex part 51 Continuous heating furnace 52 Conveyor roller

Claims

1. A box-shaped heat treatment container comprising a plate-shaped bottom wall portion and a side wall portion erected from the bottom wall portion, and accommodating an object to be heat-treated in a space surrounded by the bottom wall portion and the side wall portion, a protrusion that protrudes outward from the outermost peripheral edge of the side wall portion in a plan view on at least a part of the outer peripheral portion of the bottom wall portion; The heat treatment vessel is characterized in that the bottom wall portion, the side wall portion, and the protrusion portion are integrally molded.

2. The heat treatment container according to claim 1, characterized in that, at the outer peripheral position where the protrusion is located, there is a thick portion in at least one selected from the connecting portion between the upper end surface of the protrusion and the outer peripheral surface of the side wall portion, and the connecting portion between the inner peripheral surface of the side wall portion and the upper surface of the bottom wall portion.

3. 3. The heat treatment vessel according to claim 1, wherein the protrusion has an upper end surface and a lower end surface that are positioned within the thickness range of the bottom wall portion.

4. 3. The heat treatment vessel according to claim 1, wherein the heat treatment vessel is a molded article made of a heat-resistant inorganic material.

5. 3. The heat treatment vessel according to claim 1, wherein the protrusion has a convex portion provided on an upper end surface of the protrusion.

6. 3. The heat treatment vessel according to claim 1, wherein the object to be heat treated is a lithium ion battery material.

7. 3. The heat treatment vessel according to claim 1, wherein the heat treatment vessel is used in a roller hearth kiln.

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