heat treatment furnace

Abstract

To suppress generation of uneven heating in a vertical direction at the inside of plural objects to be treated stacked in the vertical direction.SOLUTION: A heat treatment furnace comprises: a furnace body provided with a carry-in port, a carry-out port, and a heat treatment space with a heating-up space and a holding space heat-treating objects to be treated; a conveyance plate on which the plural objects to be treated can be placed in a state of being stacked in a vertical direction; a pusher pushing the conveyance plate from the carry-in port toward the carry-out port in the furnace body in a front direction; and plural heaters extending in the vertical direction and arranged in a row in the front direction at the inside of the heat treatment space. Each of the plural heaters is provided with a heat generation part. The positions in the vertical direction of the heat generation parts in the plural heaters change from the heater located closest to the side of the carry-in port toward the heater located closest to the side of the carry-out port.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a heat treatment furnace. [Background technology]

[0002] Patent Document 1 discloses a heat treatment furnace for heat treating a workpiece. The heat treatment furnace includes a furnace body with an inlet and an outlet, and multiple heaters arranged in a line in the front direction inside the furnace body from the inlet to the outlet. Each of the multiple heaters extends vertically. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-162245 Summary of the Invention [Problem to be solved by the invention]

[0004] In a heat treatment furnace such as that described in Patent Document 1, multiple workpieces are stacked vertically and heat treated by multiple heaters. As a result, uneven heating in the vertical direction can occur among the multiple workpieces stacked vertically.

[0005] This specification discloses a technique that can prevent uneven heating in the vertical direction from occurring within a plurality of workpieces stacked vertically. [Means for solving the problem]

[0006] In a first aspect of the technology disclosed in this specification, a heat treatment furnace includes a furnace body having an inlet, an outlet, and a heat treatment space having a temperature-raising space and a holding space for heat-treating the workpieces, a conveying plate on which multiple workpieces can be placed in a vertically stacked state, a pusher that presses the conveying plate forward from the inlet to the outlet of the furnace body, and multiple heaters extending in the vertical direction and arranged side by side in the forward direction within the heat treatment space. Each of the multiple heaters has a heat-generating portion that generates heat. The positions of the heat-generating portions of the multiple heaters in the vertical direction change from the heater located closest to the inlet to the heater located closest to the outlet.

[0007] According to the above configuration, the vertical positions of the heat generating parts of the multiple heaters change inside the furnace body. This makes it possible to prevent a specific workpiece from being overheated among the multiple workpieces stacked vertically. This makes it possible to prevent uneven heating in the vertical direction among the multiple workpieces stacked vertically. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic cross-sectional view of the heat treatment furnace of the first embodiment. [Figure 2] 2 is a schematic cross-sectional view of the heat treatment furnace taken along line II-II in FIG. 1. [Figure 3] 3 is a side view of a plurality of objects to be processed placed on a transfer plate in the first embodiment. FIG. [Figure 4] FIG. 2 is a cross-sectional view of the vertical heater and the guide rail portion of the first embodiment. [Figure 5] FIG. 2 is a schematic cross-sectional view of a heat treatment furnace near a heat treatment space in the first embodiment. [Figure 6] FIG. 2 is a top view of multiple lower heaters of the first embodiment. [Figure 7] FIG. 2 is a schematic cross-sectional view of the heat treatment furnace near the lower heater in the first embodiment. [Figure 8] FIG. 10 is a schematic cross-sectional view of a heat treatment furnace near a heat treatment space in a second embodiment. [Figure 9] FIG. 11 is a schematic cross-sectional view of a heat treatment furnace near a heat treatment space in a third embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view of a heat treatment furnace near a heat treatment space in a fourth embodiment. [Figure 11] FIG. 10 is a top view of multiple lower heaters of the fifth embodiment. [Figure 12] FIG. 13 is a schematic diagram of a lower heater according to a sixth embodiment.

[0009] The main features of the embodiments described below are listed below. Note that the technical elements described below are independent technical elements that exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0010] In a second aspect of the technology disclosed herein, in the first aspect, the forward direction is perpendicular to the up-down direction. The transport plates are arranged side by side in a left-right direction perpendicular to the up-down direction and the forward direction, and are transported from the inlet to the outlet by being pressed by the pusher. The heaters include a plurality of first heaters arranged between adjacent transport plates in the left-right direction, a plurality of second heaters arranged between the right ends of the transport plates arranged side by side in the left-right direction and the furnace body and arranged side by side in the forward direction, and a plurality of third heaters arranged between the left ends of the transport plates arranged side by side in the left-right direction and the furnace body and arranged side by side in the forward direction. In the temperature-raising space, the heat generation amount of the first heater is greater than the heat generation amount of the second heater and the heat generation amount of the third heater. According to the above configuration, the first heater is arranged between adjacent workpieces in the left-right direction. Therefore, the first heater heats both the workpiece to the right of the first heater and the workpiece to the left of the first heater. Furthermore, the second heater is adjacent only to the rightmost workpiece. Therefore, the second heater heats only the rightmost workpiece. Furthermore, the third heater is adjacent only to the leftmost workpiece. Therefore, the third heater heats only the leftmost workpiece. For example, when the heat generation amount of the first heater is smaller than the heat generation amount of the second heater and the third heater, respectively, the workpieces to the right and left of the first heater are less likely to be heated than the workpieces to the left and right. This causes uneven heating in the left-right direction among multiple workpieces lined up in the left-right direction. According to the above configuration, the heat generation amount of the first heater is greater than the heat generation amount of the second heater and the third heater, respectively, thereby preventing uneven heating in the left-right direction among multiple workpieces lined up in the left-right direction.

[0011] In a third aspect of the technology disclosed in the present specification, the heat generation amount of the first heater in the second aspect is 1.3 times or more and 2.7 times or less the heat generation amount of the second heater. The heat generation amount of the second heater is approximately the same as the heat generation amount of the third heater. With the above configuration, it is possible to further suppress the occurrence of heating unevenness in the left-right direction among multiple workpieces lined up in the left-right direction.

[0012] In a fourth aspect of the technology disclosed in this specification, in any one of the first to third aspects, the forward direction is perpendicular to the vertical direction. The furnace body includes a ceiling wall into which the heater is inserted in the vertical direction and a vibration-retaining portion that receives the lower end of the heater. According to the above configuration, since the lower end of the heater is received in the vibration-retaining portion, deformation of the heater in the horizontal direction due to long-term use can be suppressed. This suppresses contact of the heater with the workpiece.

[0013] In a fifth aspect of the technology disclosed in this specification, in the fourth aspect described above, the furnace body further includes a guide rail portion that guides the conveying plate in the forward direction. The anti-vibration portion is formed on an upper surface of the guide rail portion. With the above configuration, the heater and the conveying plate are reliably separated and an increase in the number of parts can be suppressed.

[0014] In a sixth aspect of the technology disclosed herein, in the fourth or fifth aspect described above, the inner width of the anti-vibration portion in the left-right direction perpendicular to the up-down direction and the forward direction is 1.1 times or more and 2 times or less than the width of the heater. In a configuration in which the inner width of the anti-vibration portion is less than 1.1 times the width of the heater, the heater may be pressed against the anti-vibration portion when the heater thermally expands, resulting in damage to the heater. Furthermore, in a configuration in which the inner width of the anti-vibration portion is more than twice the width of the heater, the lower end of the heater may come off the anti-vibration portion when the heater warps in the left-right direction. This configuration can prevent damage to the heater when it thermally expands, and can also prevent the lower end of the heater from coming off the anti-vibration portion when the heater warps in the left-right direction.

[0015] In a seventh aspect of the technology disclosed in this specification, in any one of the first to sixth aspects, the heat treatment furnace further includes a protective member covering the heater. This configuration can prevent substances generated by the heat treatment of the workpiece from coming into contact with the heater, thereby extending the life of the heater.

[0016] In an eighth aspect of the technology disclosed herein, in any one of the first to seventh aspects, the heat treatment furnace further includes a spacer disposed between the conveying plate and the workpiece. In a configuration in which the workpiece is placed directly on the conveying plate, the underside of the workpiece in contact with the conveying plate is difficult to heat. With the above configuration, the underside of the workpiece on the conveying plate can be heated.

[0017] In a ninth aspect of the technology disclosed herein, in any one of the first to eighth aspects, the front direction is perpendicular to the up-down direction. The furnace body has a left side wall and a right side wall that face each other in a left-right direction perpendicular to the up-down direction and the front direction. The heat treatment furnace further includes a plurality of fourth heaters arranged side by side in the front direction below the conveying plate and penetrating the right side wall to extend from the right side wall to the left side wall inside the furnace body, and a plurality of fifth heaters arranged side by side in the front direction below the conveying plate and penetrating the left side wall to extend from the left side wall to the right side wall inside the furnace body. The tips of the fourth heaters and the fifth heaters are spaced apart from each other in the left-right direction. A facing region is defined between the tips of the fourth heaters and the fifth heaters in the left-right direction. The positions of the plurality of facing regions in the left-right direction vary between the facing region located closest to the inlet and the facing region located closest to the outlet. In a configuration in which the left-right positions of the multiple facing areas are constant between the facing area closest to the inlet and the facing area closest to the outlet, the left-right position of the space directly above the facing areas is always constant. This makes it easy for uneven heating of the workpiece to occur. In the above configuration, the left-right position of the space directly above the facing areas changes between the facing area closest to the inlet and the facing area closest to the outlet. This makes it possible to suppress uneven heating of the workpiece.

[0018] In a tenth aspect of the technology disclosed in this specification, in the ninth aspect described above, the fourth heater has a heat-generating portion and a non-heat-generating portion extending in the left-right direction. The fifth heater has a heat-generating portion and a non-heat-generating portion extending in the left-right direction. The fourth heaters adjacent to each other in the front direction have different positions of the non-heat-generating portion of the fourth heater in the left-right direction. The fifth heaters adjacent to each other in the front direction have different positions of the non-heat-generating portion of the fifth heater in the left-right direction. The fourth heater and the fifth heater adjacent to each other in the front direction have the non-heat-generating portion of the fourth heater arranged facing the heat-generating portion of the fourth heater or the heat-generating portion of the fifth heater in the front direction, and the non-heat-generating portion of the fifth heater arranged facing the heat-generating portion of the fourth heater or the heat-generating portion of the fifth heater in the front direction. This configuration can prevent uneven heating in the left-right direction from occurring among multiple workpieces lined up in the left-right direction.

[0019] In an eleventh aspect of the technology disclosed herein, in the ninth or tenth aspect, the forward direction is perpendicular to the up-down direction. The conveying device further includes a plurality of guide rails arranged between the plurality of conveying plates arranged side by side in the left-right direction, and guiding the conveying plates in the forward direction. Each of the plurality of guide rails extends in the forward direction. The plurality of guide rails are arranged above the plurality of fourth heaters and the plurality of fifth heaters, spaced apart in the left-right direction. Each of the plurality of facing regions is arranged in a position overlapping the guide rails in the up-down direction. According to the above configuration, the guide rails are arranged directly above the facing region (the region defined between the tip of the fourth heater and the tip of the fifth heater), and no workpiece is arranged directly above the facing region. This prevents uneven heating of the workpiece.

[0020] In a twelfth aspect of the technology disclosed in the present specification, in the eleventh aspect, the two facing regions adjacent to each other in the forward direction are positioned at different positions in the left-right direction. With the above configuration, it is possible to further suppress uneven heating of the workpiece.

[0021] In a thirteenth aspect of the technology disclosed in the present specification, in any one of the ninth to twelfth aspects, the heat treatment furnace further includes a support that supports the tip of the fourth heater and the tip of the fifth heater from below. This configuration makes it possible to prevent the fourth heater and the fifth heater from deforming so that the positions of the tips of the fourth heater and the fifth heater sag.

[0022] (First Example) The heat treatment furnace 10 of the first embodiment shown in FIG. 1 heat-treats a workpiece 2. The workpiece 2 includes a sagger 4 and a workpiece body (not shown). The sagger 4 has a roughly rectangular box shape. The workpiece body is housed in the sagger 4. The workpiece body may be, for example, a raw material for a ceramic capacitor or a positive electrode material and a negative electrode material for a lithium-ion battery. Hereinafter, the longitudinal direction of the heat treatment furnace 10 will be referred to as the front-to-rear direction, the direction perpendicular to the front-to-rear direction will be referred to as the left-to-right direction, and the direction perpendicular to the front-to-rear direction and the left-to-right direction will be referred to as the up-down direction.

[0023] The heat treatment furnace 10 includes a furnace body 12, a hearth 14, a conveying plate 16, a plurality of spacers 18, a pusher 20, conveying rollers 22, a plurality of vertical heaters 24, a plurality of upper heaters 26, and a plurality of lower heaters 28.

[0024] The furnace body 12 is a thermally insulated structure having a generally rectangular parallelepiped shape extending in the front-to-rear direction. The furnace body 12 includes a ceiling wall 30, a bottom wall 32, a furnace inlet wall 34, a furnace outlet wall 36, a right side wall 38, and a left side wall 40. The ceiling wall 30, the bottom wall 32, the furnace inlet wall 34, the furnace outlet wall 36, the right side wall 38, and the left side wall 40 define an internal space 42 of the furnace body 12. The ceiling wall 30 and the bottom wall 32 extend in the front-to-rear direction. The ceiling wall 30 is located above the bottom wall 32. The furnace inlet wall 34 is connected to the rear ends of the ceiling wall 30 and the bottom wall 32. The furnace inlet wall 34 has a loading port 34a penetrating the furnace inlet wall 34 in the front-to-rear direction. The internal space 42 is in communication with the outside of the furnace body 12 via the loading port 34a. The furnace outlet wall 36 is connected to the front end of the ceiling wall 30 and the front end of the bottom wall 32. The furnace outlet wall 36 has an outlet 36a penetrating the furnace outlet wall 36 in the front-rear direction. The internal space 42 is in communication with the outside of the furnace body 12 via the outlet 36a. The outlet 36a faces the inlet 34a in the front-rear direction. As shown in FIG. 2, the right side wall 38 and the left side wall 40 are spaced apart in the left-right direction. The right side wall 38 faces the left side wall 40 in the left-right direction. The right side wall 38 and the left side wall 40 are connected to the ceiling wall 30, the bottom wall 32, the furnace inlet wall 34 (see FIG. 1), and the furnace outlet wall 36 (see FIG. 1).

[0025] As shown in Figure 1, the furnace body 12 further includes a plurality of partition walls 44. The partition walls 44 are aligned in the front-to-rear direction. The partition walls 44 extend downward from the ceiling wall 30. The partition walls 44 divide the internal space 42 into a plurality of spaces.

[0026] The internal space 42 includes a heat treatment space 48 and a cooling space 50. The heat treatment space 48 is defined by the ceiling wall 30, the bottom wall 32, the furnace inlet wall 34, the right side wall 38 (see FIG. 2), the left side wall 40 (see FIG. 2), and a partition wall 44 located at the boundary between the cooling space 50. The heat treatment space 48 is located at the rear of the furnace body 12. The heat treatment space 48 is further divided into multiple spaces 52 by the partition wall 44. A plurality of vertical heaters 24, a plurality of upper heaters 26, and a plurality of lower heaters 28 are disposed in the heat treatment space 48. When the vertical heaters 24, the plurality of upper heaters 26, and the plurality of lower heaters 28 generate heat, the heat treatment space 48 is heated. As a result, the workpiece 2 in the heat treatment space 48 is heated.

[0027] The cooling space 50 is located in the front of the furnace body 12. The cooling space 50 is defined by the ceiling wall 30, the bottom wall 32, the furnace outlet wall 36, the right side wall 38, the left side wall 40, and a partition wall 44 located at the boundary between the heat treatment space 48. The cooling space 50 is divided into multiple spaces by the partition walls 44. Cooling pipes (not shown) are located in the cooling space 50. The cooling space 50 is cooled by water or air passing through the cooling pipes. This cools the workpiece 2 in the cooling space 50.

[0028] The hearth 14 is disposed in the heat treatment space 48. The hearth 14 is made of ceramics. The hearth 14 includes a plurality of mounting portions 54 and a plurality of guide rail portions 56.

[0029] The mounting portion 54 has a substantially rectangular parallelepiped shape. The mounting portion 54 extends in the front-rear direction. As shown in FIG. 2, the multiple mounting portions 54 are arranged side by side in the left-right direction. The upper surfaces 54a of the mounting portions 54 are arranged so as to be perpendicular to the up-down direction, that is, so as to be located on a plane along the left-right direction and the front-rear direction. The upper surfaces 54a of the multiple mounting portions 54 are located on the same plane.

[0030] The guide rail portion 56 has a substantially rectangular parallelepiped shape. The guide rail portion 56 extends in the front-rear direction. The multiple guide rail portions 56 are arranged spaced apart in the left-right direction. The upper surfaces 56a of the guide rail portions 56 are arranged so as to be perpendicular to the up-down direction, i.e., so as to be located on a plane along the left-right direction and the front-rear direction. The upper surfaces 56a of the multiple guide rail portions 56 are located on the same plane. The upper surfaces 56a of the guide rail portions 56 are arranged slightly above the upper surface 54a of the mounting portion 54. The side surfaces of the guide rail portions 56 are arranged so as to be perpendicular to the left-right direction, i.e., so as to be located on a plane along the front-rear direction and the up-down direction.

[0031] The conveying plate 16 has a flat plate shape. The conveying plate 16 is made of ceramics. A plurality of workpieces 2 can be placed on the upper surface 16a of the conveying plate 16. A plurality of workpieces 2 (six in this embodiment) are stacked vertically. The plurality of workpieces 2 are also arranged in multiple rows in the left-right direction on one conveying plate 16 (two rows in this embodiment). In a modified example, the plurality of workpieces 2 may be arranged in multiple rows in the front-rear direction on the upper surface 16a of one conveying plate 16.

[0032] The conveying plate 16 is disposed on the upper surface 54a of the mounting portion 54. The conveying plate 16 is supported by the mounting portion 54. A plurality of (two in this embodiment) conveying plates 16 are disposed between adjacent guide rail portions 56 in the left-right direction. The guide rail portion 56 is disposed between two conveying plates 16 arranged side by side in the left-right direction. The total width of the two conveying plates 16 in the left-right direction is slightly smaller than the distance between the adjacent guide rail portions 56 in the left-right direction. The conveying plate 16 is pushed by the pusher 20 (see FIG. 1 ) to move forward within the internal space 42 of the furnace body 12. As the conveying plate 16 moves within the heat treatment space 48, the workpiece 2 is heat-treated. As the conveying plate 16 moves within the cooling space 50, the workpiece 2 is cooled. The conveying plate 16 slides on the upper surface 54a of the mounting portion 54 while being guided forward by the guide rail portions 56.

[0033] As shown in Fig. 3, the spacer 18 has a substantially rectangular parallelepiped shape. A plurality of spacers 18 (two in this embodiment) are arranged between the conveying plate 16 and the workpiece 2. The spacer 18 is made of ceramics. The spacer 18 separates the lower surface of the workpiece 2 located at the bottom of the six workpieces 2 stacked vertically from the conveying plate 16. This prevents the lowermost workpiece 2 from heating or cooling more slowly than the other workpieces 2.

[0034] As shown in FIG. 1 , the pusher 20 is disposed outside the furnace body 12 near the inlet 34a. The pusher 20 is configured to push the conveying plates 16 forward. In this embodiment, the pusher 20 simultaneously pushes six conveying plates 16 arranged in the left-right direction forward. As a result, the six conveying plates 16 move from the inlet 34a into the internal space 42, and the multiple conveying plates 16 in the internal space 42 are pushed forward by the movement of the six conveying plates 16. As the pusher 20 repeatedly pushes the conveying plates 16, the conveying plates 16 are transported from the inlet 34a into the internal space 42, pass through the heat treatment space 48 and the cooling space 50 in that order, and are then transported outside the furnace body 12 through the outlet 36a. In a modified example, multiple pushers 20 may be disposed outside the furnace body 12 near the inlet 34a. The number of conveying plates 16 pressed by each pusher 20 may be one or more (for example, two). Note that the configuration of the pusher 20 is well known, so a detailed description of the configuration will be omitted.

[0035] The plurality of conveying rollers 22 are arranged in the cooling space 50. The conveying rollers 22 are made of, for example, a metal material or ceramics. The plurality of conveying rollers 22 are arranged at intervals in the front-to-rear direction. Both ends of the conveying rollers 22 are rotatably supported by the right side wall 38 and the left side wall 40. When the conveying plate 16 is pressed forward by the pusher 20, the plurality of conveying rollers 22 rotate due to friction acting between the conveying plate 16. The conveying plate 16 moves forward over the plurality of conveying rollers 22 within the cooling space 50.

[0036] The plurality of vertical heaters 24 are arranged in the heat treatment space 48. As shown in FIGS. 1 and 2 , the plurality of vertical heaters 24 includes a plurality of first vertical heaters 60, a plurality of second vertical heaters 62, and a plurality of third vertical heaters 64.

[0037] As shown in FIG. 1 , the first vertical heater 60 extends in the up-down direction. The first vertical heaters 60 are spaced apart in the front-rear direction. As shown in FIG. 2 , the first vertical heaters 60 are spaced apart in the left-right direction. In this embodiment, two first vertical heaters 60 are arranged along the left-right direction. The first vertical heater 60 is arranged between adjacent workpieces 2 in the left-right direction. Workpieces 2 are arranged on both the right and left sides of the first vertical heater 60. Two rows of workpieces 2 aligned in the left-right direction are arranged between the two first vertical heaters 60. In a modified example, only one row of workpieces 2 may be arranged between the two first vertical heaters 60. In the left-right direction, the first vertical heater 60 is arranged between two adjacent transport plates 16 in the left-right direction. The first vertical heater 60 is arranged above the guide rail portion 56. The first vertical heater 60 is inserted into the ceiling wall 30 in the up-down direction.

[0038] As shown in FIG. 4, a vibration prevention portion 68 is formed on the upper surface 56a of the guide rail portion 56. The vibration prevention portion 68 is recessed downward from the upper surface 56a. The vibration prevention portion 68 extends in the front-rear direction on the upper surface 56a. The lower end of the first vertical heater 60 is received in the vibration prevention portion 68. In the left-right direction, the width W1 of the first vertical heater 60 is smaller than the inner width W2 of the vibration prevention portion 68. The inner width W2 is, for example, 1.1 times or more, preferably 1.2 times or more, and more preferably 1.3 times or more of the width W1. Furthermore, W1 is, for example, 2.0 times or less, preferably 1.9 times or less, and more preferably 1.8 times or less of the inner width W2. These configurations can prevent the first vertical heater 60 from being pressed against the guide rail portion 56 within the anti-sway portion 68 when the first vertical heater 60 thermally expands, and can also prevent the first vertical heater 60 from coming off the anti-sway portion 68 when the first vertical heater 60 deforms and warps in the left-right direction. The inner width W2 is, for example, 1.1 to 2.0 times the width W1, preferably 1.2 to 1.9 times the width W1, and more preferably 1.3 to 1.8 times the width W1.

[0039] The heat treatment furnace 10 further includes a protective member 70, which covers the outer surface of the first vertical heater 60. The protective member 70 is coated on the outer surface of the first vertical heater 60. The protective member 70 is made of, for example, alumina or mullite. The protective member 70 prevents substances generated from the workpiece 2 during heat treatment from coming into contact with the first vertical heater 60. This prevents deterioration of the first vertical heater 60, thereby extending the life of the first vertical heater 60. The width of the protective member 70 in the left-right direction is approximately the same as the width W1 of the first vertical heater 60. Note that the thickness of the protective member 70 is exaggerated in FIG. 4 . In a modified example, the protective member 70 may be a protective tube that covers the outer surface of the first vertical heater 60 while being spaced apart from the outer surface of the first vertical heater 60. In this configuration, the width of the protection member 70 is approximately the same as the width W1, and the width of the first vertical heater 60 is smaller than the width W1.

[0040] As shown in FIG. 5, the first vertical heater 60 includes a first heat-generating portion 60a and a first non-heat-generating portion 60b. In FIG. 5, the first heat-generating portion 60a is illustrated with dotted hatching, and the first non-heat-generating portion 60b is illustrated with white. When power is supplied to the first vertical heater 60, the first heat-generating portion 60a generates heat. The resistance per unit length of the first non-heat-generating portion 60b is much smaller than the resistance per unit length of the first heat-generating portion 60a and is slightly greater than zero. Therefore, the heat generation per unit length of the first non-heat-generating portion 60b is much smaller than the heat generation per unit length of the first heat-generating portion 60a. Therefore, the first vertical heater 60 is configured to generate heat in the first heat-generating portion 60a.

[0041] The first heat-generating portion 60a and the first non-heat-generating portion 60b extend in the vertical direction. In the first vertical heater 60, the first heat-generating portion 60a extends upward from the bottom end of the first vertical heater 60 to a predetermined position, and the first non-heat-generating portion 60b extends upward from a predetermined position to the top end of the first vertical heater 60. The first non-heat-generating portion 60b is disposed above the first heat-generating portion 60a.

[0042] The vertical length of the first heating section 60a increases from the first vertical heater 60 located closest to the loading entrance 34a toward the first vertical heater 60 located closest to the unloading exit 36a. Therefore, the position of the top end of the first heating section 60a (the vertical center position of the first heating section 60a) increases from the first vertical heater 60 located closest to the loading entrance 34a toward the first vertical heater 60 located closest to the unloading exit 36a. Furthermore, the vertical lengths of the first heating sections 60a of the multiple first vertical heaters 60 arranged in the same space 52 are approximately the same. The temperature of the heat treatment space 48 increases from the loading entrance 34a toward the front and then remains constant. Hereinafter, the space within the heat treatment space 48 where the temperature of the heat treatment space 48 increases is referred to as the temperature-raising space 72, and the space where the temperature of the heat treatment space 48 is constant is referred to as the holding space 74. In this embodiment, nine first vertical heaters 60 are arranged in the temperature rising space 72 in the front-rear direction, and the other first vertical heaters 60 are arranged in the holding space 74.

[0043] As shown in FIG. 2 , the second vertical heater 62 extends in the up-down direction. The second vertical heaters 62 are spaced apart in the front-rear direction. The number of the second vertical heaters 62 is the same as the number of the first vertical heaters 60 arranged in the front-rear direction. In the left-right direction, the second vertical heater 62 is arranged between the right side wall 38 and the right end of the conveying plate 16 adjacent to the right side wall 38. Workpieces 2 are arranged only to the left of the second vertical heater 62. The second vertical heater 62 is also arranged in a row with two first vertical heaters 60 in the left-right direction. Two rows of workpieces 2 are arranged in the left-right direction between the second vertical heater 62 and the first vertical heater 60. In a modified example, only one row of workpieces 2 may be arranged between the second vertical heater 62 and the first vertical heater 60. The second vertical heater 62 is disposed above the guide rail portion 56. The second vertical heater 62 is inserted into the ceiling wall 30 in the vertical direction.

[0044] 4, the lower end of the second vertical heater 62 is received in a vibration prevention portion 68. The left-right width W3 of the second vertical heater 62 is approximately the same as the left-right width W1 of the first vertical heater 60. The outer surface of the second vertical heater 62 is covered with a protective member 70.

[0045] As shown in FIG. 5, the second vertical heater 62 includes a second heat-generating portion 62a and a second non-heat-generating portion 62b. When power is supplied to the second vertical heater 62, the second heat-generating portion 62a generates heat. The resistance per unit length of the second non-heat-generating portion 62b is much smaller than the resistance per unit length of the second heat-generating portion 62a and is slightly greater than zero. Therefore, the amount of heat generated per unit length of the second non-heat-generating portion 62b is much smaller than the amount of heat generated per unit length of the second heat-generating portion 62a. Therefore, the second vertical heater 62 is configured to generate heat in the second heat-generating portion 62a.

[0046] In the first vertical heater 60 and the second vertical heater 62 arranged in the left-right direction, the vertical length of the second heat generating portion 62a is approximately the same as the vertical length of the first heat generating portion 60a, and the positions of the lower and upper ends of the second heat generating portion 62a are approximately the same as the positions of the lower and upper ends of the first heat generating portion 60a, respectively. Furthermore, the resistance per unit length of the first heat generating portion 60a is greater than the resistance per unit length of the second heat generating portion 62a. Therefore, the heat generation per unit length of the first heat generating portion 60a is greater than the heat generation per unit length of the second heat generating portion 62a. Because the vertical length of the first heat generating portion 60a is approximately the same as the vertical length of the second heat generating portion 62a, the heat generation per unit length of the first vertical heater 60a is greater than the heat generation per unit length of the second vertical heater 62a. For example, the heat generation amount of the first vertical heater 60 is 1.3 times or more, preferably 1.5 times or more, and more preferably 1.7 times or more, that of the second vertical heater 62. Furthermore, for example, the heat generation amount of the first vertical heater 60 is 2.7 times or less, preferably 2.5 times or less, and more preferably 2.1 times or less, that of the second vertical heater 62. With this configuration, it is possible to prevent uneven heating in the left-right direction among multiple workpieces 2 arranged in the left-right direction. The heat generation amount of the first vertical heater 60 is, for example, 1.3 times or more and 2.7 times or less, preferably 1.5 times or more and 2.5 times or less, and more preferably 1.7 times or more and 2.1 times or less, that of the second vertical heater 62.

[0047] As shown in FIG. 2 , the third vertical heater 64 extends in the up-down direction. The multiple third vertical heaters 64 are spaced apart in the front-rear direction. The number of the multiple third vertical heaters 64 is the same as the number of the multiple second vertical heaters 62. In the left-right direction, the third vertical heater 64 is disposed between the left side wall 40 and the left end of the conveying plate 16 adjacent to the left side wall 40. The third vertical heater 64 is also aligned in a row with the two first vertical heaters 60 in the left-right direction. The two first vertical heaters 60, the second vertical heater 62, and the third vertical heater 64 are aligned in a row in the left-right direction. Two rows of workpieces 2 aligned in the left-right direction are disposed between the third vertical heater 64 and the first vertical heater 60. In a modified example, only one row of workpieces 2 may be disposed between the third vertical heater 64 and the first vertical heater 60. The third vertical heater 64 is disposed above the guide rail portion 56. The third vertical heater 64 is inserted into the ceiling wall 30 of the furnace body 12 in the vertical direction.

[0048] 4, the lower end of the third vertical heater 64 is received in a vibration prevention portion 68. The left-right width W4 of the third vertical heater 64 is approximately the same as the left-right width W1 of the first vertical heater 60. The outer surface of the third vertical heater 64 is covered with a protective member 70.

[0049] As shown in FIG. 5, the third vertical heater 64 includes a third heat-generating portion 64a and a third non-heat-generating portion 64b. When power is supplied to the third vertical heater 64, the third heat-generating portion 64a generates heat. The resistance per unit length of the third non-heat-generating portion 64b is much smaller than the resistance per unit length of the third heat-generating portion 64a and is slightly greater than zero. Therefore, the amount of heat generated per unit length of the third non-heat-generating portion 64b is much smaller than the amount of heat generated per unit length of the third heat-generating portion 64a. Therefore, the third vertical heater 64 is configured to generate heat in the third heat-generating portion 64a.

[0050] In the first vertical heater 60 and the third vertical heater 64, which are aligned in the left-right direction, the vertical length of the third heat generating portion 64a is approximately the same as the vertical length of the first heat generating portion 60a, and the positions of the lower and upper ends of the third heat generating portion 64a are approximately the same as the positions of the lower and upper ends of the first heat generating portion 60a, respectively. Furthermore, the resistance per unit length of the third heat generating portion 64a is approximately the same as the resistance per unit length of the second heat generating portion 62a. Therefore, the heat generation amount per unit length of the third heat generating portion 64a is approximately the same as the heat generation amount per unit length of the second heat generating portion 62a. Because the vertical length of the third heat generating portion 64a is approximately the same as the vertical length of the second heat generating portion 62a, the heat generation amount of the third vertical heater 64 is approximately the same as the heat generation amount of the second vertical heater 62a. Furthermore, the heat generation amount per unit length of the first heating element 60a is greater than the heat generation amount per unit length of the third heating element 64a. Because the vertical length of the first heating element 60a is substantially the same as the vertical length of the third heating element 64a, the heat generation amount of the first vertical heater 60 is greater than the heat generation amount of the third vertical heater 64. For example, the heat generation amount of the first vertical heater 60 is 1.3 times or more, preferably 1.5 times or more, and more preferably 1.7 times or more, the heat generation amount of the third vertical heater 64. For example, the heat generation amount of the first vertical heater 60 is 2.7 times or less, preferably 2.5 times or less, and more preferably 2.1 times or less, the heat generation amount of the third vertical heater 64. These configurations can prevent uneven heating in the horizontal direction among multiple workpieces 2 arranged in the horizontal direction. The heat generation amount of the first vertical heater 60 is, for example, 1.3 times or more and 2.7 times or less, preferably 1.5 times or more and 2.5 times or less, and more preferably 1.7 times or more and 2.1 times or less, that of the third vertical heater 64.

[0051] As shown in FIG. 2, multiple upper heaters 26 are arranged in the heat treatment space 48. The upper heaters 26 extend in the left-right direction. The upper heaters 26 are inserted in the left-right direction into the ceiling wall 30. As shown in FIG. 5, the multiple upper heaters 26 are arranged at intervals in the front-to-rear direction. The upper heaters 26 are arranged above the uppermost workpiece 2 among the multiple workpieces 2 stacked in the vertical direction. The upper heaters 26 generate heat to heat-treat the workpieces 2 from above.

[0052] As shown in FIG. 2, the plurality of lower heaters 28 are arranged in the heat treatment space 48. The plurality of lower heaters 28 are arranged below the transfer plate 16 and the guide rail portion 56. As shown in FIG. 6, the plurality of lower heaters 28 are arranged at intervals in the front-rear direction. The lower heaters 28 extend in the left-right direction. The plurality of lower heaters 28 include a plurality of first lower heaters 78 and a plurality of second lower heaters 80.

[0053] The first lower heater 78 has a generally U-shape. The multiple first lower heaters 78 are arranged in a line in the front-to-rear direction. The first lower heaters 78 are inserted in the left-to-right direction into the right side wall 38. The first lower heater 78 extends leftward within the heat treatment space 48 from the right side wall 38 toward the left side wall 40. The first lower heater 78 includes one or more first lower heating portions 78a and one or more first lower non-heating portions 78b. In FIG. 6, the first lower heating portions 78a are illustrated with dotted hatching, and the first lower non-heating portions 78b are illustrated in white. In this embodiment, the total number of first lower heating portions 78a and first lower non-heating portions 78b in one first lower heater 78 is five or seven.

[0054] When power is supplied to the first lower heater 78, the first lower heat-generating portion 78a generates heat. Furthermore, the resistance per unit length of the first lower non-heat-generating portion 78bb is much smaller than the resistance per unit length of the first lower heat-generating portion 78a and is slightly greater than zero. Therefore, the amount of heat generated per unit length of the first lower non-heat-generating portion 78b is much smaller than the amount of heat generated per unit length of the first lower heat-generating portion 78a. Therefore, the first lower heater 78 is configured to generate heat at the first lower heat-generating portion 78a.

[0055] In one first lower heater 78, the first lower heat-generating portions 78a and the first lower non-heat-generating portions 78b are arranged alternately in the longitudinal direction of the first lower heater 78. In first lower heaters 78 adjacent to each other in the front-to-rear direction, the first lower heat-generating portions 78a and the first lower non-heat-generating portions 78b are arranged facing each other in the front-to-rear direction. In two first lower heaters 78 adjacent to each other in the front-to-rear direction, the left-to-right positions of the first lower heat-generating portions 78a are different, and the left-to-right positions of the first lower non-heat-generating portions 78b are different.

[0056] The second lower heater 80 has a substantially U-shape. The multiple second lower heaters 80 are arranged side by side in the front-to-rear direction. The second lower heaters 80 are inserted in the left side wall 40 in the left-to-right direction. The second lower heaters 80 extend rightward from the left side wall 40 toward the right side wall 38 within the heat treatment space 48. The second lower heaters 80 are arranged side by side in the left-to-right direction with the first lower heater 78. The right end (free end) of the second lower heater 80 faces and is spaced apart from the left end (free end) of the first lower heater 78 in the left-to-right direction. As a result, a facing region 84 is defined between the right end of the second lower heater 80 and the left end of the first lower heater 78. The left-to-right width of all facing regions 84 is substantially the same. The left-to-right positions of two facing regions 84 adjacent to each other in the front-to-rear direction are different.

[0057] The second lower heater 80 includes one or more second lower heat-generating portions 80a and one or more second lower non-heat-generating portions 80b. In this embodiment, the total number of second lower heat-generating portions 80a and second lower non-heat-generating portions 80b in one second lower heater 80 is five or seven. The second lower heater 80, in which the total number of second lower heat-generating portions 80a and second lower non-heat-generating portions 80b is five, is aligned in the left-right direction with the first lower heater 78, in which the total number of first lower heat-generating portions 78a and first lower non-heat-generating portions 78b is seven. In addition, the second lower heater 80, in which the total number of second lower heat-generating portions 80a and second lower non-heat-generating portions 80b is seven, is aligned in the left-right direction with the first lower heater 78, in which the total number of first lower heat-generating portions 78a and first lower non-heat-generating portions 78b is five.

[0058] When power is supplied to the second lower heater 80, the second lower heat-generating portion 80a generates heat. The resistance per unit length of the second lower non-heat-generating portion 80b is much smaller than the resistance per unit length of the second lower heat-generating portion 80a and is slightly greater than zero. Therefore, the amount of heat generated per unit length of the second lower non-heat-generating portion 80b is much smaller than the amount of heat generated per unit length of the second lower heat-generating portion 80a. Therefore, the second lower heater 80 is configured to generate heat at the second lower heat-generating portion 80a. Furthermore, the resistance per unit length of the second lower heat-generating portion 80a is approximately the same as the resistance per unit length of the first lower heat-generating portion 78a. Therefore, the amount of heat generated per unit length of the second lower heat-generating portion 80a is approximately the same as the amount of heat generated per unit length of the first lower heat-generating portion 78a.

[0059] In one second lower heater 80, the second lower heat-generating portions 80a and the second lower non-heat-generating portions 80b are arranged alternately in the longitudinal direction of the second lower heater 80. In second lower heaters 80 adjacent to each other in the front-to-rear direction, the second lower heat-generating portions 80a and the second lower non-heat-generating portions 80b are arranged facing each other in the front-to-rear direction. In two second lower heaters 80 adjacent to each other in the front-to-rear direction, the second lower heat-generating portions 80a are positioned differently in the left-to-right direction, and the second lower non-heat-generating portions 80b are positioned differently in the left-to-right direction.

[0060] The left-right positions of the multiple facing regions 84 vary between the facing region 84 closest to the loading entrance 34a and the facing region closest to the unloading exit 36a. The left-right positions of the facing regions 84 that are odd-numbered forward from the loading entrance 34a are in a first position, and the left-right positions of the facing regions 84 that are even-numbered forward from the loading entrance 34a are in a second position that is different from the first position. In other words, the facing regions 84 that are in the first position and the facing regions 84 that are in the second position are alternately lined up in the forward direction from the facing region 84 closest to the loading entrance 34a to the facing region 84 closest to the unloading exit 36a.

[0061] In two lower heaters 28 adjacent in the front-rear direction (i.e., the first lower heater 78 and the second lower heater 80), the entire first lower heat-generating portion 78a of the first lower heater 78 is arranged facing in the front-rear direction to the first lower non-heat-generating portion 78b of the other first lower heater 78, the second lower non-heat-generating portion 80b of the second lower heater 80, or the facing region 84. In addition, the entire second lower heat-generating portion 80a of the second lower heater 80 is arranged facing in the front-rear direction to the second lower non-heat-generating portion 80b of the other second lower heater 80, the first lower non-heat-generating portion 78b of the first lower heater 78, or the facing region 84. Therefore, in two lower heaters 28 adjacent in the front-rear direction, the first lower heat-generating portion 78a is not arranged facing in the front-rear direction to the second lower heat-generating portion 80a. This makes it possible to prevent uneven heating in the left-right direction caused by the lower heaters 28 between the lower heaters 28 closest to the carry-in entrance 34a and the lower heaters 28 closest to the carry-out exit 36a.

[0062] In two lower heaters 28 adjacent in the front-rear direction, the entire first lower non-heating portion 78b of the first lower heater 78 is arranged facing the first lower heat-generating portion 78a of the other first lower heater 78 or the second lower heat-generating portion 80a of the second lower heater 80 in the front-rear direction. Furthermore, the entire second lower non-heat-generating portion 80b of the second lower heater 80 is arranged facing the second lower heat-generating portion 80a of the other second lower heater 80 or the first lower heat-generating portion 78a of the first lower heater 78 in the front-rear direction. Furthermore, the entire opposing region 84 is arranged facing the first lower heat-generating portion 78a or the second lower heat-generating portion 80a in the front-rear direction. Therefore, in two lower heaters 28 adjacent in the front-rear direction, the first lower non-heat-generating portion 78b is not arranged facing the second lower non-heat-generating portion 80b or the opposing region 84 in the front-rear direction, and the second lower non-heat-generating portion 80b is not arranged facing the opposing region 84 in the front-rear direction. This makes it possible to prevent uneven heating in the left-right direction caused by the lower heaters 28 between the lower heaters 28 closest to the carry-in entrance 34a and the lower heaters 28 closest to the carry-out exit 36a.

[0063] As shown in FIG. 7 , the heat treatment furnace 10 further includes a support 86. The support 86 is disposed in the heat treatment space 48. The support 86 is supported by the bottom wall 32. The support 86 is disposed below the first lower heater 78, the second lower heater 80, and the facing region 84. The support 86 abuts the left end of the first lower heater 78 and the right end of the second lower heater 80 from below. The support 86 supports the left end of the first lower heater 78 and the right end of the second lower heater 80 from below. This prevents the first lower heater 78 and the second lower heater 80 from deforming, which would cause the left end of the first lower heater 78 and the right end of the second lower heater 80 to sag.

[0064] In the above embodiment, the vertical positions of the first heat generating portions 60a of the first vertical heaters 60 vary from the first vertical heater 60 located closest to the loading entrance 34a toward the first vertical heater 60 located closest to the unloading exit 36a. According to the above configuration, the vertical positions of the first heat generating portions 60a of the multiple first vertical heaters 60 vary within the furnace body 12. This makes it possible to prevent a specific workpiece 2 among the multiple workpieces 2 stacked vertically from being overheated. This makes it possible to prevent uneven heating in the vertical direction among the multiple workpieces 2 stacked vertically.

[0065] (Correspondence) The first vertical heater 60 is an example of a "first heater." The second vertical heater 62 is an example of a "second heater." The third vertical heater 64 is an example of a "third heater." The first lower heater 78 is an example of a "fourth heater." The second lower heater 80 is an example of a "fifth heater." The left end of the first lower heater 78 is an example of a "tip of the fourth heater." The right end of the second lower heater 80 is an example of a "tip of the fifth heater."

[0066] (Second Example) In the second embodiment, only the differences from the first embodiment will be described. As shown in Fig. 8, in the first vertical heaters 60 arranged in the same space 52, the vertical length of the first heat generating portion 60a increases as it moves forward from the entrance 34a. In the second vertical heaters 62 arranged in the same space 52, the vertical length of the second heat generating portion 62a increases as it moves forward from the entrance 34a. In the third vertical heaters 64 arranged in the same space 52, the vertical length of the third heat generating portion 64a increases as it moves forward from the entrance 34a.

[0067] (Third Example) In the third embodiment, only the differences from the first embodiment will be described. As shown in Fig. 9, in the multiple first vertical heaters 60, the vertical lengths of all of the first heat generating portions 60a are approximately the same. In the multiple first vertical heaters 60 arranged in the same space 52 divided by multiple partition walls 44 lined up in the forward direction, the vertical positions of the first heat generating portions 60a within the first vertical heaters 60 are approximately the same. In the multiple spaces 52, the vertical positions of the first heat generating portions 60a within the first vertical heaters 60 move upward from the space 52 closest to the inlet 34a to the space 52 closest to the outlet 36a.

[0068] The vertical configuration of the second heat generating portion 62a in the second vertical heater 62 is substantially the same as the vertical configuration of the first heat generating portion 60a in the first vertical heater 60. Moreover, the vertical configuration of the third heat generating portion 64a in the third vertical heater 64 is substantially the same as the vertical configuration of the first heat generating portion 60a in the first vertical heater 60. Therefore, detailed description of the second heat generating portion 62a and the third heat generating portion 64a will be omitted.

[0069] (Fourth Example) In the fourth embodiment, only the differences from the third embodiment will be described. As shown in Fig. 10, in the multiple spaces 52, the vertical position of the first heat generating unit 60a in the first vertical heater 60 moves downward from the space 52 closest to the loading entrance 34a toward the space 52 closest to the unloading exit 36a. In addition, in the multiple spaces 52, the vertical position of the second heat generating unit 62a in the second vertical heater 62 moves downward from the space 52 closest to the loading entrance 34a toward the space 52 closest to the unloading exit 36a. In addition, in the multiple spaces 52, the vertical position of the third heat generating unit 64a in the third vertical heater 64 moves downward from the space 52 closest to the loading entrance 34a toward the space 52 closest to the unloading exit 36a.

[0070] (Fifth Example) In the fifth embodiment, only the differences from the first embodiment will be described. As shown in FIG. 11 , the facing region 84 is disposed directly below the guide rail portion 56. Therefore, the facing region 84 overlaps the guide rail portion 56 in the vertical direction. The facing region 84 positioned odd-numbered forward from the carry-in entrance 34a overlaps one guide rail portion 56 in the vertical direction, while the facing region 84 positioned even-numbered forward from the carry-in entrance 34a overlaps another guide rail portion 56 in the vertical direction. For two facing regions 84 adjacent to each other in the front-rear direction, the guide rail portion 56 that overlaps one facing region 84 in the vertical direction is different from the guide rail portion 56 that overlaps the other facing region 84 in the vertical direction.

[0071] (Sixth Example) In the sixth embodiment, only the differences from the first embodiment will be described. As shown in FIG. 12, the first lower heater 78 and the second lower heater 80 have a spiral shape. The first lower heat-generating portion 78a of the first lower heater 78 extends in a spiral shape. The first lower heat-generating portion 78a extends in the left-right direction. When power is supplied to the first lower heater 78, the first lower heat-generating portion 78a generates heat. The first lower non-heat-generating portion 78b of the first lower heater 78 extends straight in the left-right direction. The configuration of the second lower heater 80 is substantially the same as the configuration of the first lower heater 78, so a detailed description of the second lower heater 80 will be omitted.

[0072] (Variation) In one embodiment, the lower heater 28 may be a single heater extending from the right side wall 38 to the left side wall 40. In this case, the lower heater 28 is inserted into both the right side wall 38 and the left side wall 40.

[0073] In the fifth embodiment, the first lower heater 78 may include only the first lower heat generating portion 78a, and the second lower heater 80 may include only the second lower heat generating portion 80a.

[0074] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of those objectives itself has technical utility. [Explanation of symbols]

[0075] 2: Processing object 10: Heat treatment furnace 12:Furnace body 14: Hearth part 16: Transfer plate 18: Spacer 20: Pusher 24: Vertical heater 28: Lower heater 30: Ceiling wall 34a: Loading entrance 36a: Exit 38: Right side wall 40: Left side wall 42: Interior space 48: Heat treatment space 52: Space 56: Guide rail part 56a:Top surface 60: First vertical heater 60a: First heating section 60b: First non-heating portion 62: Second vertical heater 62a: Second heating section 62b: Second non-heating portion 64: Third vertical heater 64a: Third heating section 64b: Third non-heating section 68: Vibration rest 70: Protective material 72: Heating space 74: Holding space 78: 1st lower heater 78a: First lower heating part 78b: First lower non-heating part 80: Second lower heater 80a: Second lower heating section 80b: Second lower non-heating portion 84:Opposing area 86:Support W1, W3, W4: Width W2:Inner width

Claims

1. a furnace body including a loading port, a loading port, and a heat treatment space including a temperature-raising space for heat-treating the object to be treated and a holding space; a conveying plate on which a plurality of the objects to be processed can be placed in a vertically stacked state; a pusher that pushes the conveying plate forward from the inlet of the furnace body toward the outlet; a plurality of heaters extending in the vertical direction and arranged in the front direction within the heat treatment space, Each of the plurality of heaters includes a heat generating portion that generates heat, the positions of the heat generating portions of the plurality of heaters in the vertical direction vary from the heater located closest to the entrance to the heater located closest to the exit, the forward direction is perpendicular to the up-down direction, The furnace body is a ceiling wall into which the heater is inserted in the vertical direction; and a vibration-retaining portion that receives the lower end of the heater.

2. The conveying plates are arranged side by side in a left-right direction perpendicular to the up-down direction and the forward direction, and are conveyed from the inlet to the outlet by being pressed by the pusher, The plurality of heaters include: a plurality of first heaters disposed between adjacent conveying plates in the left-right direction; A plurality of second heaters are arranged in the left-right direction between the right ends of the plurality of conveying plates arranged in the left-right direction and the furnace body, and are arranged in the front direction; a plurality of third heaters arranged in the front direction and disposed between the furnace body and left ends of the plurality of conveying plates arranged in the left-right direction, 2. The heat treatment furnace according to claim 1, wherein in the temperature rising space, a heat generation amount of the first heater is greater than a heat generation amount of the second heater and a heat generation amount of the third heater.

3. the heat generation amount of the first heater is 1.3 times or more and 2.7 times or less than the heat generation amount of the second heater, The heat treatment furnace according to claim 2 , wherein the heat generation amount of the second heater is substantially the same as the heat generation amount of the third heater.

4. The furnace body further includes a guide rail portion that guides the conveying plate in the forward direction, The heat treatment furnace according to claim 1 , wherein the vibration-preventing portion is formed on an upper surface of the guide rail portion.

5. 2. The heat treatment furnace according to claim 1, wherein an inner width of the vibration prevention portion in a left-right direction perpendicular to the up-down direction and the forward direction is 1.1 times or more and 2 times or less the width of the heater.

6. The heat treatment furnace according to claim 1 , further comprising a protective member covering the heater.

7. The heat treatment furnace according to claim 1 , further comprising a spacer disposed between the transfer plate and the workpiece.

8. The furnace body has a left wall and a right wall that face each other in a left-right direction perpendicular to the up-down direction and the forward direction, The heat treatment furnace is a plurality of fourth heaters arranged side by side in the front direction below the conveying plate, penetrating the right side wall and extending from the right side wall toward the left side wall inside the furnace body; a plurality of fifth heaters arranged in a row in the front direction below the conveying plate and penetrating the left side wall to extend from the left side wall to the right side wall inside the furnace body; a tip end of the fourth heater and a tip end of the fifth heater are opposed to and spaced apart in the left-right direction, an opposing region is defined between the tip of the fourth heater and the tip of the fifth heater in the left-right direction; 2. The heat treatment furnace according to claim 1, wherein the positions of the plurality of facing regions in the left-right direction vary between the facing region located closest to the inlet and the facing region located closest to the outlet.

9. the fourth heater includes a heat generating portion and a non-heat generating portion extending in the left-right direction, the fifth heater includes a heat generating portion and a non-heat generating portion extending in the left-right direction, The fourth heaters adjacent to each other in the front direction have non-heat generating portions different in position in the left-right direction, The fifth heaters adjacent to each other in the front direction have non-heat generating portions different in position in the left-right direction, In the fourth heater and the fifth heater adjacent to each other in the forward direction, the non-heat-generating portion of the fourth heater is disposed to face the heat-generating portion of the fourth heater or the heat-generating portion of the fifth heater in the front direction, The heat treatment furnace according to claim 8 , wherein the non-heat generating portion of the fifth heater is disposed facing the heat generating portion of the fourth heater or the heat generating portion of the fifth heater in the front direction.

10. The conveyor further includes a plurality of guide rail portions arranged between the plurality of conveying plates arranged side by side in the left-right direction, and guiding the conveying plates in the forward direction, Each of the plurality of guide rail portions extends in the forward direction, the plurality of guide rail portions are arranged above the plurality of fourth heaters and the plurality of fifth heaters and spaced apart from each other in the left-right direction, The heat treatment furnace according to claim 8 , wherein each of the plurality of facing regions is disposed at a position overlapping the guide rail portion in the vertical direction.

11. The heat treatment furnace according to claim 10 , wherein the two facing regions adjacent to each other in the forward direction are positioned at different positions in the left-right direction.

12. The heat treatment furnace according to claim 8 , further comprising a support that supports the tip of the fourth heater and the tip of the fifth heater from below.

13. A furnace body having an inlet, an outlet, and a heat treatment space having a temperature-raising space and a holding space for heat-treating the workpiece; a conveying plate on which a plurality of the objects to be processed can be placed in a vertically stacked state; a pusher that pushes the conveying plate forward from the inlet of the furnace body toward the outlet; a plurality of heaters extending in the vertical direction and arranged in the front direction within the heat treatment space, Each of the plurality of heaters includes a heat generating portion that generates heat, the positions of the heat generating portions of the plurality of heaters in the vertical direction vary from the heater located closest to the entrance to the heater located closest to the exit, the forward direction is perpendicular to the up-down direction, The furnace body has a left wall and a right wall facing each other in a left-right direction perpendicular to the up-down direction and the forward direction, The heat treatment furnace is a plurality of fourth heaters arranged side by side in the front direction below the conveying plate, penetrating the right side wall and extending from the right side wall toward the left side wall inside the furnace body; a plurality of fifth heaters arranged in a row in the front direction below the conveying plate and penetrating the left side wall to extend from the left side wall to the right side wall inside the furnace body; a tip end of the fourth heater and a tip end of the fifth heater are opposed to and spaced apart in the left-right direction, an opposing region is defined between the tip of the fourth heater and the tip of the fifth heater in the left-right direction; A heat treatment furnace, wherein the positions of the plurality of opposing regions in the left-right direction vary between the opposing region located closest to the inlet and the opposing region located closest to the outlet.

Images