Firing tool

Abstract

To suppress uneven firing in firing a large number of subjects to be fired simultaneously.SOLUTION: A firing tool 1 comprises a lower frame 10, a fireproof mesh 20, and an upper frame 30. Then, the lower frame 10 comprises: an outer frame 11 being an outer shape of the lower frame 10; a lower rib 12 which crosslinks the outer frame 11; gas passing holes 13 surrounded by the outer frame 11 and the lower rib 12; and a projection 14 projecting upward from the lower rib 12. Then, an opening part 21 for allowing the projection 14 to be inserted into the fireproof mesh 20 is provided, and the projection 14 is projected upward from a top face of the fireproof mesh 20 via the opening part 21. Furthermore, the upper frame 30 is equipped with an upper outer frame 32 opposing the outer frame 11 with the fireproof mesh 20 laid between. According to such a constitution, a subject to be fired is prevented from being mounted on a support area SA above the outer frame 11 and the lower rib 12, and uneven firing in firing a large number of subjects to be fired simultaneously can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed herein relates to a firing jig. [Background technology]

[0002] In recent years, electronic components such as multilayer ceramic capacitors (MLCCs) have been miniaturized to the order of 0.1 mm. 2 ~1000cm 2 The small electronic components are placed on the top surface of a tray-shaped firing jig about the same size and fired. In firing these small electronic components, first, a large number of firing targets (electronic components before firing) are placed on the top surface of the firing jig. Then, the piled-up firing targets are leveled and made flat. This results in hundreds to tens of thousands of firing targets being distributed on the top surface of the firing jig. The firing jig is then placed inside a firing furnace and fired. This allows a large number of electronic components to be produced simultaneously.

[0003] This firing jig for electronic component production includes, for example, a frame with gas passage holes and a refractory mesh placed above the frame. In a firing jig with such a configuration, a large number of firing objects are distributed on the upper surface of the refractory mesh. When this firing jig is used, high-temperature gas during firing passes through the gas passage holes and the refractory mesh, allowing the firing objects on the refractory mesh to be efficiently heated. An example of such a firing jig is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-48950 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a large number of firing objects are fired simultaneously using the firing jig described above, uneven firing can occur, resulting in some of the objects being poorly fired. In this case, re-firing or sorting of defective products is required, which can significantly reduce manufacturing efficiency. The technology disclosed herein has been made to solve the above-mentioned problem, and aims to provide a technology that can suppress uneven firing when a large number of firing objects are fired simultaneously. [Means for solving the problem]

[0006] The inventors conducted extensive experiments and studies into the causes of uneven firing among multiple firing targets, and as a result, have discovered the following. In the firing jig with the above configuration, a large amount of weight is applied to the thin refractory mesh because multiple firing targets are placed on top of the refractory mesh. Furthermore, the firing jig is exposed to a high-temperature environment during use, which tends to reduce its rigidity. These factors can lead to the refractory mesh sinking during firing. For this reason, the frame of a typical firing jig includes an outer frame that defines the frame's shape and beam-like members (ribs) that bridge the outer frame. The outer frame and ribs support the refractory mesh from below. However, the outer frame and ribs block the flow of high-temperature gas in the areas above the outer frame and ribs. Furthermore, because heat is likely to accumulate in the outer frame and ribs, the firing targets placed above the outer frame and ribs are slow to cool. As a result, differences in heating efficiency occur between the areas above the outer frame and ribs and other areas. Furthermore, in mass production where several hundred or more objects are fired simultaneously, it is difficult to distribute the objects so as to avoid the areas above the outer frame and ribs. For this reason, when a large number of objects are fired simultaneously using conventional firing jigs, unevenness in the firing result is likely to occur.

[0007] The firing jig disclosed herein was developed based on the above findings. This firing jig includes a tray-shaped lower frame, a refractory mesh disposed above the lower frame, and an upper frame disposed above the refractory mesh. The lower frame of this firing jig includes an outer frame that defines the outer shape of the lower frame, lower ribs bridging the outer frame, gas passage holes surrounded by the outer frame and the lower ribs, and protrusions protruding upward from the lower ribs. In the firing jig disclosed herein, the refractory mesh has openings through which the protrusions can be inserted, and the protrusions protrude above the upper surface of the refractory mesh through the openings. The upper frame also includes an upper outer frame that faces the outer frame across the refractory mesh.

[0008] In the firing jig having the above configuration, the protrusions on the lower rib protrude above the upper surface of the refractory mesh. This prevents the firing objects from being placed in the area above the lower rib when multiple firing objects are distributed on the refractory mesh. In addition, in the firing jig having the above configuration, the upper outer frame of the upper frame is disposed on top of the outer frame of the lower frame. This prevents the firing objects from being placed in the area above the outer frame. As a result, most of the firing objects can be fired in the area above the gas passage holes, thereby suppressing uneven firing when multiple firing objects are fired simultaneously. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a firing jig according to a first embodiment. [Figure 2] FIG. 2 is a plan view of the firing jig according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] FIG. 4 is a side view of the firing jig according to the first embodiment. [Figure 5] FIG. 5 is a plan view of the lower frame of the firing jig shown in FIG. [Figure 6] FIG. 6 is a plan view of the refractory mesh of the firing jig shown in FIG. [Figure 7] FIG. 7 is a plan view of the upper frame of the firing jig shown in FIG. [Figure 8] FIG. 8 is a side view of a stack of the firing jigs shown in FIG. [Figure 9] FIG. 9 is a plan view of a firing jig for comparison. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the technology disclosed herein are described below. Matters necessary for implementation other than those specifically mentioned in this specification (e.g., the manufacturing method of the firing jig and the firing conditions for the fired object) can be understood based on the technical content taught by this specification and the general technical common sense of a person skilled in the art. In other words, the technology disclosed herein can be implemented based on the matters disclosed in this specification and the general technical common sense of this field. In this specification, the expression "A to B" indicating a range means A or more and B or less.

[0011] First Embodiment A first embodiment of the firing jig disclosed herein will be described below with reference to FIGS. 1 to 8. FIG. 1 is a perspective view of the firing jig according to the first embodiment. FIG. 2 is a plan view of the firing jig according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 4 is a side view of the firing jig according to the first embodiment. FIG. 5 is a plan view of the lower frame of the firing jig shown in FIG. 2. FIG. 6 is a plan view of the refractory mesh of the firing jig shown in FIG. 2. FIG. 7 is a plan view of the upper frame of the firing jig shown in FIG. 2. FIG. 8 is a side view of a stack of firing jigs shown in FIG. 4. In the drawings, the symbols X, Y, and Z represent the width, depth, and height directions, respectively. Furthermore, the symbols L, R, F, Rr, U, and D represent the left, right, front, rear, top, and bottom, respectively.

[0012] As shown in FIGS. 1 to 4, the firing jig 1 according to this embodiment includes a tray-shaped lower frame 10, a refractory mesh 20 disposed above the lower frame 10, and an upper frame 30 disposed above the refractory mesh 20. In a firing process for electronic components using this firing jig 1, first, a large number of firing targets (electronic components before firing) are supplied to the upper surface 20a of the refractory mesh 20. The piled-up firing targets are then smoothed and flattened. As a result, hundreds to tens of thousands of firing targets are dispersed and disposed on the upper surface 20a of the refractory mesh 20. The firing jig 1 is then placed in a firing furnace and fired. This allows a large number of electronic components to be produced simultaneously. The specific configuration of the firing jig 1 will be described below.

[0013] (1) Lower frame As described above, the lower frame 10 is a tray-shaped frame. The material of the lower frame 10 need only have fire resistance sufficient to withstand the firing process, and any conventionally known fire-resistant material can be used without particular limitation. Examples of such fire-resistant materials include ceramic materials (typically fire-resistant materials specified in JIS R2001) such as alumina (Al2O3), silica (SiO2), zirconia (ZrO2), magnesia (MgO), calcia (CaO), silicon carbide (SiC), and mullite (3Al2O3·2SiO2). Metallic or alloy materials with melting points higher than the firing temperature can also be used for the lower frame 10. Examples of such metallic materials include nickel (Ni), titanium (Ti), tungsten (W), and molybdenum (Mo). Alloys containing the above metals can also be used as alloy materials.

[0014] The lower frame 10 according to this embodiment includes an outer frame 11, lower ribs 12, gas passage holes 13, and protrusions 14. Furthermore, the lower frame 10 includes support columns 16. The detailed structure of the lower frame 10 will be described below with reference to FIG. 5.

[0015] (1-1) Outer frame The outer frame 11 is a part that forms the outer shape of the lower frame 10. The outer frame 11 shown in FIG. 5 is a frame body that has a rectangular planar shape. This rectangular outer frame 11 is formed by interconnecting four frame bodies, namely, a first frame body 11a to a fourth frame body 11d. Specifically, on the left side L in FIG. 5, a first frame body 11a extending along the depth direction Y is formed. On the other hand, on the right side R, a second frame body 11b extending along the depth direction Y to face the first frame body 11a is formed. On the front side F in FIG. 5, a third frame body 11c extending along the width direction X is formed. On the other hand, on the rear side Rr, a fourth frame body 11d extending along the width direction X to face the third frame body 11c is formed. The front end F of the first frame body 11a is connected to the left end L of the third frame body 11c. Meanwhile, the rear Rr end of the first frame 11a is connected to the left L end of the fourth frame 11d. The front F end of the second frame 11b is connected to the right R end of the third frame 11c. Meanwhile, the rear Rr end of the second frame 11b is connected to the right R end of the fourth frame 11d. This forms a rectangular outer frame 11 in plan view. However, the planar shape of the outer frame is not limited to the rectangle shown in FIG. 5. For example, the firing jig disclosed herein can also employ a polygonal outer frame or annular outer frame.

[0016] The thickness t1 of the outer frame 11 is preferably 1 mm or more, more preferably 2.5 mm or more, even more preferably 5 mm or more, and particularly preferably 7.5 mm or more. This ensures sufficient strength of the lower frame 10. On the other hand, as the thickness t1 of the outer frame 11 increases, the area of ​​the gas passage holes 13 in a plan view becomes smaller, which tends to reduce firing efficiency. Furthermore, as the thickness t1 of the outer frame 11 increases, the heat capacity of the outer frame 11 increases, making it difficult to cool the firing target. From these perspectives, the thickness of the outer frame 11 is preferably 20 mm or less, more preferably 17.5 mm or less, even more preferably 15 mm or less, and particularly preferably 12.5 mm or less.

[0017] (1-2) Lower rib The lower ribs 12 are members that bridge the outer frame 11. Specifically, the lower ribs 12 are beam-shaped members that connect the first to fourth frame bodies 11a to 11d, which are opposed to each other with a predetermined gap between them. For example, the lower frame 10 shown in FIG. 5 includes a first lower rib 12a and a second lower rib 12b. The first lower rib 12a extends along the width direction X to bridge the first frame body 11a and the second frame body 11b. The second lower rib 12b extends along the depth direction Y to bridge the third frame body 11c and the fourth frame body 11d. The first lower rib 12a and the second lower rib 12b intersect at the center of the lower frame 10. In the following description, the portion where the first lower rib 12a and the second lower rib 12b intersect is referred to as an "intersection region CA."

[0018] As shown in Figs. 1 to 3, the lower ribs 12 in this embodiment support the refractory mesh 20 from below D. As will be described in detail later, in the firing jig 1 according to this embodiment, the refractory mesh 20 is placed on the frame 10. The refractory mesh 20 is supported by the outer frame 11 of the frame 10 and the lower ribs 12. This prevents the refractory mesh 20 from being deformed by the weight of the object to be fired. For ease of explanation, the region in which the refractory mesh 20 is supported by the outer frame 11 and the lower ribs 12 (i.e., the region U above the outer frame 11 and the lower ribs 12) will be referred to as the "support region SA" below.

[0019] The thickness t2 of the lower rib 12 is preferably 1 mm or more, more preferably 2.5 mm or more, even more preferably 5 mm or more, and particularly preferably 7.5 mm or more. This ensures a sufficient width for the support area SA, thereby more preferably preventing deformation of the refractory mesh 20. On the other hand, the thickness of the lower rib 12 is preferably 20 mm or less, more preferably 17.5 mm or less, even more preferably 15 mm or less, and particularly preferably 12.5 mm or less. This ensures a sufficient area for the gas passage holes 13 in a plan view, improving firing efficiency.

[0020] As described above, the lower frame 10 shown in FIG. 5 is provided with a first lower rib 12a and a second lower rib 12b. However, the number of lower ribs does not limit the technology disclosed herein. The number of lower ribs can be increased or decreased as appropriate, taking into consideration the relationship between suppression of deformation of the refractory mesh and firing efficiency. Specifically, increasing the number of lower ribs makes it easier to suppress deformation of the refractory mesh, but reduces firing efficiency due to a decrease in the area of ​​the gas passage holes. On the other hand, decreasing the number of lower ribs improves firing efficiency, but makes it easier for deformation of the refractory mesh to occur. From this perspective, the number of lower ribs formed on the lower frame is preferably 1 to 10 (more preferably 1 to 6, and particularly preferably 1 to 4).

[0021] (1-3) Gas passage hole The gas passage hole 13 is an opening surrounded by the outer frame 11 and the lower rib 12. As shown in FIG. 3, the gas passage hole 13 penetrates the lower frame 10. In the firing jig 1 according to this embodiment, as shown in FIG. 3, high-temperature gas G flows in the height direction Z through the gas passage hole 13 and the refractory mesh 20. Some firing objects generate gases due to evaporation of moisture and organic components during firing. By providing the gas passage hole 13 and the refractory mesh 20 in the firing jig 1, such gases can be easily exhausted during firing. This allows the firing object placed on the upper surface 20a of the refractory mesh 20 to be heated efficiently.

[0022] In this embodiment, four gas passage holes 13 having a rectangular planar shape are formed (see FIGS. 2 and 5). Specifically, a first gas passage hole 13a is formed in the upper left (left L and rear Rr) of the lower frame 10 shown in FIG. 5. This first gas passage hole 13a is an opening surrounded by the first frame body 11a, the fourth frame body 11d, the first lower rib 12a, and the second lower rib 12b. Furthermore, a second gas passage hole 13b is formed in the upper right (right R and rear Rr) in FIG. 5. This second gas passage hole 13b is an opening surrounded by the second frame body 11b, the fourth frame body 11d, the first lower rib 12a, and the second lower rib 12b. Next, a third gas passage hole 13c is formed in the lower left (left L and front F) in FIG. 5. The third gas passage hole 13c is an opening surrounded by the first frame body 11a, the third frame body 11c, the first lower rib 12a, and the second lower rib 12b. A fourth gas passage hole 13d is formed in the lower right (right R and front F) in Fig. 5. The fourth gas passage hole 13d is an opening surrounded by the second frame body 11b, the third frame body 11c, the first lower rib 12a, and the second lower rib 12b.

[0023] The total area of ​​the gas passage holes 13 (the total area of ​​the first gas passage hole 13a to the fourth gas passage hole 13d) is 50 cm 2 More than 75cm is preferable. 2 More than 100cm is preferable. 2 More than 125cm is more preferable. 2 The above is particularly preferable. This ensures a sufficient flow path for high-temperature gas, further improving the firing efficiency. On the other hand, the total area of ​​the gas passage holes 13 is 800 cm 2 Less than 775cm is preferable. 2 Less than 750cm is preferable. 2 Less than 725cm is more preferable. 2 The following is particularly preferable, as this can ensure sufficient strength of the lower frame 10. The areas of the first gas passing hole 13a to the fourth gas passing hole 13d may be the same or different.

[0024] (1-4) Protrusion 1 and 3, the lower frame 10 in this embodiment has protrusions 14 that protrude upward U from the lower ribs 12. These protrusions 14 prevent objects to be baked from being placed on the support area SA above the lower ribs 12. This prevents uneven baking when multiple objects to be baked are baked simultaneously. The detailed function of these protrusions 14 will be described later.

[0025] In this embodiment, the protrusions 14 are wall-shaped protrusions that extend continuously along the extension direction of the lower ribs 12 (see FIGS. 1, 2, and 5). Specifically, two protrusions 14 extending along the width direction X are formed on the first lower rib 12a extending in the width direction X. Furthermore, two protrusions 14 extending along the depth direction Y are formed on the second lower rib 12b extending in the depth direction Y. These wall-shaped protrusions 14 can more effectively prevent the baking object from being placed on the support area SA.

[0026] The thickness t3 of the protrusions 14 (see FIG. 5) is preferably 50% or more of the thickness t2 of the lower rib 12 described above, more preferably 55% or more, even more preferably 60% or more, and particularly preferably 65% ​​or more. This makes it possible to effectively prevent the object to be fired from being placed on the support area SA. On the other hand, if the protrusions 14 are too thick, it becomes difficult to place the refractory mesh 20 above the lower rib 12. From this perspective, the thickness t3 of the protrusions 14 is preferably 90% or less of the thickness t2 of the lower rib 12, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less.

[0027] It is preferable that the protrusions 14 are not formed in the portions where the lower ribs 12 intersect (intersection regions CA in FIG. 2). This more effectively prevents deformation of the refractory mesh 20 due to the weight of the object to be fired. Specifically, in the firing jig 1 according to this embodiment, openings 21 must be formed in the refractory mesh 20 in order for the protrusions 14 to protrude above the upper surface 20a of the refractory mesh 20 (see FIG. 3). In this case, if protrusions are formed in the intersection regions CA in FIG. 2, cross-shaped openings must be formed to divide the center of the refractory mesh. If the object to be fired is placed on the refractory mesh having such cross-shaped openings, the weight of the object to be fired may cause the refractory mesh to sink in each of the first gas passage holes 13a to fourth gas passage holes 13d in FIG. 2. From this perspective, it is preferable that the protrusions 14 are not formed in the intersection regions CA.

[0028] 1 and 3, the protrusions 14 are tapered, narrowing toward the upper end. This more effectively prevents firing defects. Specifically, when the firing objects are supplied to the upper surface 20a of the refractory mesh 20, several hundred of the firing objects are dropped from above U of the firing jig 1. If some of the firing objects land on the protrusions 14, firing defects are more likely to occur. In response to this, tapering the protrusions 14 can prevent the firing objects from landing on the protrusions 14. Furthermore, when the firing objects falling from above U come into contact with the side of the tapered protrusions 14, the firing objects are reflected toward the area above the gas passage holes 13. Therefore, the tapered protrusions 14 also contribute to preventing the firing objects from being placed on the support area SA.

[0029] (1-5) Support Furthermore, the lower frame 10 in this embodiment is provided with four support columns 16 that protrude upward U from the outer frame 11 (see FIGS. 1, 2, and 5). As shown in FIG. 8, firing jigs 1 equipped with the support columns 16 can be easily stacked along the height direction Z. This further improves the manufacturing efficiency of electronic components per unit area. Note that the height of the support columns 16 is preferably greater than the height of the protrusions 14. This allows a gap S through which high-temperature gas can flow to be generated between the upper firing jig 1 and the lower firing jig 1. As a result, a decrease in firing efficiency in the lower firing jig 1 can be suppressed.

[0030] The support pillars need only have a configuration that allows multiple firing jigs to be stacked, and are not limited to the configuration shown in Figures 1, 2, and 5. For example, in the firing jig 1 shown in Figures 1, 2, and 5, four support pillars 16 protrude upward U from the outer frame 11. However, the support pillars may protrude not from the outer frame but from the lower ribs. Even in this case, multiple firing jigs can be stacked. Furthermore, the number of support pillars is not limited to four. As long as the number of support pillars is three or more, multiple firing jigs can be stacked. However, considering stability during stacking, the number of support pillars is preferably four or more.

[0031] (2) Fireproof mesh Next, the refractory mesh 20 is placed above the lower frame 10. This refractory mesh 20 is a plate-shaped porous body. This allows high-temperature gases to pass through during firing. The object to be fired is distributed over the upper surface 20a of this refractory mesh 20. The high-temperature gases during firing pass through the gas passage holes 13 of the lower frame 10 and the refractory mesh 20, and are supplied to the object to be fired on the refractory mesh 20. This allows the object to be heated efficiently.

[0032] The material of the refractory mesh 20 need only have sufficient fire resistance to withstand the firing process. For example, the refractory mesh 20 can be made of metal materials such as nickel (Ni), titanium (Ti), tungsten (W), and molybdenum (Mo). Alloys containing these metals can also be used. These metal materials (or alloy materials) have excellent fire resistance and high thermal conductivity, allowing the object to be fired on the refractory mesh 20 to be heated more efficiently. The refractory mesh 20 can also be made of ceramics (typically refractory materials specified in JIS R2001), such as alumina (Al2O3), silica (SiO2), zirconia (ZrO2), magnesia (MgO), calcia (CaO), silicon carbide (SiC), and mullite (3Al2O3·2SiO2). Considering the balance between heat resistance and thermal conductivity, a nickel refractory mesh 20 is particularly preferred. The refractory mesh 20 may be modified depending on the composition of the object to be fired. For example, when the object to be fired contains a conductive paste made of Ni, it is more preferable to use a refractory mesh 20 made of nickel, which can prevent impurities from the refractory mesh 20 from being mixed into the object to be fired.

[0033] Furthermore, it is preferable to appropriately adjust the average pore diameter of the refractory mesh 20 depending on the size of the object to be fired. For example, in recent years, small electronic components on the order of 0.1 mm have been developed. In response to this, the average pore diameter of the refractory mesh 20 is preferably 500 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less. In this case, the lower limit of the average pore diameter of the refractory mesh 20 is preferably 25 μm or more, more preferably 50 μm or less, and particularly preferably 75 μm or less. This improves the gas permeability of the refractory mesh 20, thereby further improving heating efficiency. However, the average pore diameter of the refractory mesh 20 is not limited to the above-mentioned numerical range. For example, when firing large electronic components on the order of 1 mm, the average pore diameter of the refractory mesh 20 can be set to 200 μm or more (preferably 500 μm or more, more preferably 1000 μm or more).

[0034] The refractory mesh 20 also has openings 21 through which the protrusions 14 of the lower frame 10 are inserted. As a result, the protrusions 14 of the lower frame 10 protrude upward through the openings 21 above the upper surface 20a of the refractory mesh 20 (see FIG. 3). This prevents a target to be fired from being placed on the support area SA above the lower rib 12. Specifically, two elongated first openings 21a extending along the width direction X are formed in the center of the refractory mesh 20 in the depth direction Y as shown in FIG. 6. The protrusions 14 on the first lower rib 12a are inserted into each of the two first openings 21a (see FIG. 2). Furthermore, two elongated second openings 21b extending along the depth direction Y are formed in the center of the refractory mesh 20 in the width direction X. The protrusions 14 on the second lower rib 12b are inserted into each of the two second openings 21b. In this way, by inserting the protrusions 14 into the openings 21 of the fireproof mesh 20, the protrusions 14 can be made to protrude above the upper surface 20a of the fireproof mesh 20. Furthermore, this configuration can prevent the fireproof mesh 20 from shifting in position in the planar directions (the width direction X and the depth direction Y). Furthermore, in this embodiment, notches 23 are formed in the four corners of the fireproof mesh 20. This can prevent interference between the fireproof mesh 20 and the support posts 16.

[0035] (3) Upper frame As shown in FIGS. 1 to 4, the firing jig 1 according to this embodiment includes an upper frame 30 disposed above a refractory mesh 20. The material of the upper frame 30 can be the same refractory material as that of the lower frame 10, without any particular restrictions. That is, the upper frame 30 can be made of ceramic materials such as alumina, silica, zirconia, magnesia, calcia, silicon carbide, and mullite. The upper frame 30 can also be made of metal materials such as nickel, titanium, tungsten, and molybdenum. The material of the upper frame 30 may be the same as or different from that of the lower frame 10.

[0036] As shown in Fig. 7, the upper frame 30 in this embodiment includes an upper outer frame 32, which is a ring-shaped frame body having a substantially rectangular outer shape. As shown in Fig. 3, the upper outer frame 32 of the upper frame 30 faces the outer frame 11 of the lower frame 10, sandwiching the refractory mesh 20 therebetween. This prevents the object to be fired from being placed above the outer frame 11. This more effectively prevents uneven firing. The upper outer frame 32 also prevents the object to be fired from falling off the upper surface 20a of the refractory mesh 20 while the firing jig 1 is being transported.

[0037] The upper outer frame 32 in this embodiment includes a plurality of upper frame members 32a to 32d that extend linearly along the extension direction of the outer frame 11. Specifically, as shown in FIG. 2, a first upper frame member 32a extending along the depth direction Y is disposed above a first frame member 11a that extends along the depth direction Y. Similarly, a second upper frame member 32b extending along the depth direction Y is disposed above a second frame member 11b that extends along the depth direction Y. Meanwhile, a third upper frame member 32c extending along the width direction X is disposed above a third frame member 11c that extends along the width direction X. Similarly, a fourth upper frame member 32d extending along the width direction X is disposed above a fourth frame member 11d that extends along the width direction X.

[0038] The first to fourth upper outer frames 32a to 32d are connected by connecting members 34a to 34d. Specifically, the rear end 32a1 of the first upper outer frame 32a and the left end 32d1 of the fourth upper outer frame 32d are connected by the first connecting member 34a. Next, the right end 32d2 of the fourth upper outer frame 32d and the rear end 32b1 of the second upper outer frame 32b are connected by the second connecting member 34b. Next, the front end 32d2 of the second upper outer frame 32b and the right end 32c1 of the third upper outer frame 32c are connected by the third connecting member 34c. Finally, the left end 32c2 of the third upper outer frame 32c and the front end 32a2 of the first upper outer frame 32a are connected by the fourth connecting member 34d. Each of the first to fourth connecting members 34a to 34d is formed at an angle so as not to interfere with the support posts 16 of the lower frame 10. Furthermore, the upper outer frame 32 and the connecting members 34 are preferably tapered members that become thinner toward the upper ends. This more effectively prevents poor firing caused by the object to be fired being placed on the upper outer frame 32 or the connecting members 34.

[0039] The thickness t4 of the upper outer frame 32 (see FIG. 7) is preferably 50% or more of the thickness t1 of the outer frame 11 (see FIG. 5), more preferably 55% or more, even more preferably 60% or more, and particularly preferably 65% ​​or more. This ensures sufficient strength for the upper outer frame 32. On the other hand, if the upper outer frame 32 is too thick, the heat capacity of the upper outer frame 32 increases, making it difficult to cool the object to be fired. From this perspective, the thickness t4 of the upper outer frame 32 is preferably 100% or less of the thickness t1 of the outer frame 11, more preferably 90% or less, even more preferably 80% or less, and particularly preferably 70% or less.

[0040] (4) Effects of the First Embodiment As described above, the firing jig 1 according to this embodiment has the protrusions 14 that protrude upward U from the lower rib 12. The protrusions 14 protrude above the upper surface 20a of the refractory mesh 20 through the openings 21. Furthermore, the upper frame 30 according to this embodiment has an upper outer frame 32 that faces the outer frame 11 across the refractory mesh 20. This makes it possible to suppress firing unevenness when firing multiple firing objects simultaneously. This will be explained in detail below in comparison with the prior art.

[0041] FIG. 9 is a plan view of a comparative firing jig. The firing jig 100 shown in FIG. 9 includes a tray-shaped frame 110 and a refractory mesh 120 disposed above the frame 110. The firing jig 100 shown in FIG. 9 also includes ribs 114 bridging the outer frame 112 of the frame 110. In a firing process using this firing jig 100, multiple firing targets are distributed on the upper surface of the refractory mesh 120. At this time, the refractory mesh 120 is supported by the outer frame 112 and the ribs 114. This prevents deformation of the refractory mesh 120 due to the weight of the firing targets. However, in the support area SA of the firing jig 100 configured as such, the outer frame 112 and the ribs 114 block the flow of high-temperature gas in the height direction (the direction perpendicular to the plane of FIG. 9 ). Furthermore, in these support areas SA, it becomes difficult for gas generated from the firing targets to be exhausted. Furthermore, the baking object placed on the support area SA is slow to cool because heat is likely to accumulate in the outer frame 112 and the ribs 144. As a result, baking unevenness is likely to occur between the gas passage holes 116 and the support area SA.

[0042] On the other hand, as shown in FIGS. 1 to 3 , in the firing jig 1 according to this embodiment, protrusions 14 protrude from the lower rib 12. These protrusions 14 protrude upward through the openings 21 above the upper surface 20a of the refractory mesh 20. Therefore, when multiple firing targets are distributed across the upper surface 20a of the refractory mesh 20, the targets are less likely to be placed on the support area SA on the lower rib 12. Furthermore, the upper frame 30 of the firing jig 1 according to this embodiment includes an upper outer frame 32 that faces the outer frame 11 across the refractory mesh 20. This also prevents the targets from being placed on the outer frame 11. As a result, most of the targets can be heated above the gas passage holes 13. This solves various issues associated with firing targets above the outer frame 11 or the lower rib 12, thereby reducing uneven firing when multiple targets are fired simultaneously.

[0043] <Other embodiments> The first embodiment of the firing jig disclosed herein has been described above. However, the technology disclosed herein is not limited to the above-described embodiment. Other embodiments of the technology disclosed herein will be described below.

[0044] For example, in the firing jig 1 according to the first embodiment, a support 16 was formed that protruded upward U from the lower frame 10 (see FIGS. 1 to 3). However, this support is not an essential component of the firing jig disclosed herein. For example, when multiple firing jigs are stacked, other firing jigs can be placed on the protrusions of the lower frame or the upper outer frame of the upper frame. Even when such a configuration is adopted, the firing efficiency per unit area can be improved.

[0045] Furthermore, the protrusions 14 in the first embodiment are wall-like protrusions that extend continuously along the extension direction of the lower ribs 12. However, the protrusions are not limited to wall-like protrusions. For example, columnar protrusions may be scattered along the extension direction of the lower ribs. Even when such a configuration is adopted, it is possible to sufficiently prevent the baking object from being placed on the support area.

[0046] Specifically, when the total area of ​​the upper surface of the lower rib is taken as 100%, the area of ​​the protrusion formation region should be 15% or more (more preferably 20% or more, even more preferably 25% or more, and particularly preferably 30% or more). This sufficiently prevents the object to be baked from being placed on the support region. On the other hand, from the viewpoint of preventing uneven baking, the upper limit of the area of ​​the protrusion formation region is not particularly limited and may be 100%. However, considering the decrease in strength of the fire-resistant mesh due to an increase in the area of ​​the openings, the upper limit of the area of ​​the protrusion formation region is preferably 55% or less, more preferably 50% or less, even more preferably 45% or less, and particularly preferably 40% or less.

[0047] As shown in FIG. 7, the upper frame 30 in the first embodiment includes multiple linear upper frame members 32a-32d and connecting members 34a-34d connecting the upper frame members 32a-32d. However, the upper frame is not limited to the above configuration, as long as it includes an upper outer frame facing the outer frame with a fireproof mesh sandwiched between them. For example, the upper frame facing the first frame member 11a, the upper frame facing the second frame member 11b, the upper frame facing the third frame member 11c, and the upper frame facing the fourth frame member 11d in FIG. 5 may be separately fabricated and placed on a metal mesh. Even with this configuration, it is possible to prevent the baking object from being placed on the outer frame of the lower frame. However, considering the ease of installation of the upper frame, it is preferable to use a single upper frame 30 connected by connecting members 34a, as in the first embodiment.

[0048] Furthermore, the protrusions 14 and the upper outer frame 32 in the first embodiment are tapered members that become thinner toward the upper end. However, the protrusions and the upper outer frame may protrude upward while maintaining a constant thickness. In this case, when several hundred firing objects are supplied from above the firing jig, there is a high possibility that the firing objects will be placed on the upper surface of the protrusions or the upper outer frame. However, by brushing off the firing objects that have rested on the protrusions or the upper outer frame before placing them in the firing furnace, firing defects on the protrusions or the upper outer frame can be prevented. However, from the perspective of reducing such work and improving production efficiency, it is preferable to form the tapered protrusions and the upper outer frame as in the first embodiment.

[0049] As shown in FIGS. 2 and 5, in the first embodiment, four gas passage holes 13 are formed in the lower frame 10. However, the number of gas passage holes does not limit the technology disclosed herein. Specifically, the number of gas passage holes can be adjusted by changing the number and shape of the lower ribs bridging the outer frame. Even in this case, it is sufficient to provide a protrusion above each lower rib and form an opening in the refractory mesh through which the protrusion can be inserted. This prevents the object to be baked from being placed above the lower ribs, thereby suppressing uneven baking when multiple objects to be baked are baked simultaneously.

[0050] While specific examples of the technology disclosed herein 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 alterations of the specific examples exemplified above.

[0051] The technology disclosed herein includes the following items 1 to 6. The following items 1 to 6 are not limited to the above-described embodiment.

[0052] [Item 1] a tray-shaped lower frame; a fire-resistant mesh disposed above the lower frame; an upper frame disposed above the fire-resistant mesh; It is equipped with The lower frame is an outer frame that defines the outer shape of the lower frame; a lower rib bridging the outer frame; a gas passage hole surrounded by the outer frame and the lower rib; a protrusion protruding upward from the lower rib; It is equipped with The fire-resistant mesh has an opening through which the protrusion is inserted, and the protrusion protrudes above an upper surface of the fire-resistant mesh through the opening. The upper frame is provided with an upper outer frame that faces the outer frame with the refractory mesh sandwiched therebetween.

[0053] [Item 2] Item 2. The firing jig according to item 1, wherein the protrusions are tapered protrusions that become thinner toward their upper ends.

[0054] [Item 3] 3. The firing jig according to item 1 or 2, wherein the protrusion extends continuously along the extension direction of the lower rib.

[0055] [Item 4] 4. The firing jig according to any one of items 1 to 3, wherein the protrusion is not formed at an intersection of the plurality of lower ribs.

[0056] [Item 5] the lower frame includes three or more support columns projecting upward from the outer frame and / or the lower rib; 5. The firing jig according to any one of items 1 to 4, wherein the height of the support posts is greater than the height of the protrusions.

[0057] [Item 6] The upper frame includes: a plurality of upper frame bodies extending linearly along the extension direction of the outer frame of the lower frame; a connecting member that connects each of the plurality of upper frame bodies; The firing jig according to any one of items 1 to 5, comprising: [Explanation of symbols]

[0058] 1: Firing jig 10: Lower frame 11: Outer frame 12: Lower rib 13: Gas passage hole 14: Protrusion 15:Second protrusion 16: Strut 20: Fireproof mesh 21: Opening 23: Notch 30: Upper frame 32: Upper outer frame 34: Connecting member

Claims

1. a tray-shaped lower frame; a fire-resistant mesh disposed above the lower frame; an upper frame disposed above the fireproof mesh; It is equipped with The lower frame is an outer frame that defines the outer shape of the lower frame; a lower rib bridging the outer frame; a gas passage hole surrounded by the outer frame and the lower rib; a protrusion protruding upward from the lower rib; It is equipped with The fire-resistant mesh has an opening through which the protrusion is inserted, and the protrusion protrudes above an upper surface of the fire-resistant mesh through the opening, The upper frame is provided with an upper outer frame that faces the outer frame with the refractory mesh sandwiched therebetween.

2. The firing jig according to claim 1 , wherein the protrusions are tapered protrusions that become thinner toward their upper ends.

3. The firing jig according to claim 1 , wherein the protrusion extends continuously along the extending direction of the lower rib.

4. The firing jig according to claim 1 , wherein the protrusion is not formed at an intersection of the plurality of lower ribs.

5. the lower frame includes three or more support columns projecting upward from the outer frame and / or the lower rib; The firing jig according to claim 1 , wherein the height of the support posts is greater than the height of the protrusions.

6. The upper frame includes: a plurality of upper frame bodies extending linearly along the extension direction of the outer frame of the lower frame; a connecting member that connects each of the plurality of upper frame bodies; The firing jig according to claim 1 , comprising:

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