Firing tool
The firing jig with a lower and upper frame configuration addresses uneven firing issues by using upper ribs to prevent objects from being placed over ribs, ensuring uniform heating and efficient gas flow, thus enhancing manufacturing efficiency.
Patent Information
- Application Number
- JP2024053007
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-28
- Publication Date
- 2025-10-09
- Estimated Expiration
- 2044-03-28
AI Technical Summary
Conventional firing jigs for small electronic components like multilayer ceramic capacitors (MLCCs) experience uneven firing when multiple objects are fired simultaneously, leading to inefficiencies due to refractory mesh deformation and uneven heating, which requires re-firing or sorting of defective products.
A firing jig design with a tray-shaped lower frame, refractory mesh, and an upper frame featuring upper ribs that face lower ribs, preventing objects from being placed over ribs and ensuring uniform heating by maintaining gas flow through gas passage holes.
The design effectively suppresses uneven firing by ensuring uniform heating of multiple objects, improving manufacturing efficiency and reducing defects by maintaining gas flow and preventing mesh deformation.
Smart Images
Figure 2025151524000001_ABST
Abstract
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 firing jigs with the above-described configuration, a large number of firing targets are placed on top of the refractory mesh, placing a heavy weight on the thin 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 is formed with beam-like members (ribs) that support the refractory mesh from below. However, the ribs block the flow of high-temperature gas in the area above the ribs. Furthermore, because heat is likely to accumulate in the ribs, firing targets placed above the lower ribs are slow to cool. As a result, differences in heating efficiency occur between the area above the ribs and other areas. Furthermore, in mass production, where hundreds or more firing targets are fired simultaneously, it is difficult to distribute the firing targets to avoid the area above the ribs. For this reason, when a large number of objects are simultaneously fired using a conventional firing jig, uneven firing is likely to occur in the resulting fired product.
[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 that bridge the outer frame, and gas passage holes surrounded by the outer frame and the lower ribs. The upper frame of the firing jig disclosed herein includes upper ribs that face the lower ribs across the refractory mesh.
[0008] In the firing jig with the above configuration, the upper ribs of the upper frame are placed on top of the lower ribs of the lower frame. This prevents the firing objects from being placed in the area above the lower ribs when they are distributed on the refractory mesh. As a result, most of the firing objects can be fired in the area above the gas passage holes, preventing uneven firing when firing multiple objects 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 upper frame of the firing jig shown in FIG. [Figure 7] FIG. 7 is a side view of a stack of the firing jigs shown in FIG. [Figure 8] FIG. 8 is a plan view of the firing jig according to the second embodiment. [Figure 9] FIG. 9 is a plan view of a firing jig according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view taken along the line XX in FIG. [Figure 11] FIG. 11 is a cross-sectional view of a firing jig according to the fourth embodiment. [Figure 12] FIG. 12 is a plan view of the upper frame of the firing jig in the fourth embodiment. [Figure 13] FIG. 13 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 7. 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 upper frame of the firing jig shown in FIG. 2. FIG. 7 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 leveled and flattened. This results in hundreds to tens of thousands of firing targets being 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, and gas passage holes 13. Furthermore, the lower frame 10 includes protrusions 15 and 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. This prevents deformation of the refractory mesh 20. Specifically, as described above, in firing small electronic components, the objects to be fired are supplied onto the firing jig 1 (on the upper surface 20a of the refractory mesh 20). When this occurs, if hundreds to tens of thousands of objects to be fired are supplied between the outer frames 11 of the lower frame 10 (typically in the center of the refractory mesh 20), a large weight is applied to the thin refractory mesh. Furthermore, since the firing jig is exposed to a high-temperature environment during use, its rigidity is likely to decrease. This may cause the refractory mesh 20 to sink during firing. However, if the lower ribs 12 support the refractory mesh 20 from below D, deformation of the refractory mesh 20 can be suppressed. For ease of explanation, the region where the fire-resistant mesh 20 is supported by the lower rib 12 (that is, the region U above the lower rib 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 Next, the firing jig 1 according to this embodiment is equipped with a protrusion 15. This protrusion 15 protrudes upward U from the outer frame 11 of the lower frame 10. The protrusion 15 can prevent the firing object from being placed above U on the outer frame 11. This can more effectively prevent the occurrence of firing unevenness. The protrusion 15 can also prevent the firing object from falling off the upper surface 20a of the refractory mesh 20 while the firing jig 1 is being transported, for example.
[0025] Specifically, the protrusions 15 are wall-like protrusions that extend continuously along the extension direction of the outer frame 11. For example, the first frame body 11a and the second frame body 11b extend along the depth direction Y. Protrusions 15 extending along the depth direction Y are formed on the first frame body 11a and the second frame body 11b. Furthermore, the third frame body 11c and the fourth frame body 11d extend along the width direction X. Protrusions 15 extending along the width direction X are formed on the third frame body 11c and the fourth frame body 11d. In this embodiment, the outer peripheral edge of the firing jig 1 is surrounded by these wall-like protrusions 15. This makes it possible to prevent the firing target from being placed in the region above U of the outer frame 11 and also prevents the firing target from falling from above the firing jig 1.
[0026] Furthermore, it is preferable that the protrusions 15 are tapered protrusions that become thinner toward the upper end. This can more effectively prevent the occurrence of firing defects. Furthermore, the protrusions 15 may be formed at the intersection of the outer frame 11 and the lower rib 12. For example, the first frame 11a shown in FIG. 2 has two protrusions 15 that extend in the extension direction of the first frame 11a (depth direction Y). However, it is also possible for one protrusion 15 to extend in the depth direction Y over the entire area of the first frame 11a. Even when such a configuration is adopted, the occurrence of firing defects can be prevented.
[0027] The thickness t4 of the protrusions 15 (see FIG. 5) is preferably 50% or more of the thickness t1 of the outer frame 11, more preferably 55% or more, even more preferably 60% or more, and particularly preferably 65% or more. This more preferably prevents the object to be fired from being placed in the region U above the outer frame 11. On the other hand, if the protrusions 15 are too thick compared to the outer frame 11, it becomes difficult to place the refractory mesh 20 on the outer frame 11. From this perspective, the thickness t4 of the protrusions 15 is preferably 90% or less of the thickness t1 of the outer frame 11, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less.
[0028] (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. 7, 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 upper frame 30, which will be described later. 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.
[0029] 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 from the lower ribs as long as they do not interfere with the upper frame described below. 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.
[0030] (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.
[0031] 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.
[0032] 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).
[0033] 2, first notches 22 are formed on the outer peripheral edge of the refractory mesh 20. Specifically, in the firing jig 1 according to this embodiment, the first notches 22 are formed on each outer peripheral edge of the refractory mesh 20 so that the protrusions 15 on the outer frame 11 do not interfere with the refractory mesh 20. The protrusions 15 can protrude above the upper surface 20a of the refractory mesh 20 via these first notches 22 (see FIG. 3). This prevents the object to be fired from being placed in the area above the outer frame 11. Furthermore, second notches 23 are formed on the four corners of the refractory mesh 20 in this embodiment. This prevents interference between the refractory mesh 20 and the support posts 16.
[0034] (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.
[0035] As shown in Fig. 6, the upper frame 30 in this embodiment is a frame body that has a cross shape in a plan view. As shown in Fig. 3, the upper frame 30 has upper ribs 32 that face the lower ribs 12 across the fireproof mesh 20. The upper ribs 32 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 the upper ribs 32 will be described later.
[0036] In this embodiment, the upper ribs 32 extend continuously in the extension direction of the lower ribs 12 (see FIGS. 1, 2, and 5). Specifically, a first upper rib 32a extending along the width direction X is placed on top of a first lower rib 12a extending in the width direction X. Furthermore, a second upper rib 32b extending along the depth direction Y is placed on top of a second lower rib 12b extending in the depth direction Y. The first upper rib 32a and the second upper rib 32b intersect to form a cross-shaped upper frame 30. The upper frame 30 provided with this upper rib 32 can more effectively prevent a baking object from being placed on the support area SA.
[0037] The thickness t3 of the upper rib 32 (see FIG. 6) is preferably 65% or more of the thickness t2 of the lower rib 12 (see FIG. 5), more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. This effectively prevents the baking object from being placed on the support area SA. On the other hand, if the upper rib 32 is too thick, the area in which the baking object can be placed becomes smaller, which causes a decrease in baking efficiency. From this perspective, the thickness t3 of the upper rib 32 is preferably 130% or less of the thickness t2 of the lower rib 12, more preferably 120% or less, even more preferably 110% or less, and particularly preferably 100% or less.
[0038] 1 and 3, the upper rib 32 is a tapered rib that narrows 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 firing objects are dropped from the upper U of the firing jig 1. If some of the firing objects land on the upper rib 32, firing defects are more likely to occur. In response to this, tapering the upper rib 32 prevents the firing objects from landing on the upper rib 32. Furthermore, when the firing objects falling from the upper U come into contact with the side surface of the tapered upper rib 32, the firing objects are reflected toward the area above the gas passage holes 13. Therefore, the tapered upper rib 32 also contributes to preventing the firing objects from being placed on the support area SA.
[0039] (4) Effects of the First Embodiment As described above, the upper frame 30 of the firing jig 1 according to this embodiment is provided with upper ribs 32 that face the lower ribs 12 across the refractory mesh 20. This makes it possible to prevent firing unevenness when firing multiple objects at the same time. This will be explained in detail below in comparison with the prior art.
[0040] FIG. 13 is a plan view of a comparative firing jig. The firing jig 100 shown in FIG. 13 includes a tray-shaped frame 110 and a refractory mesh 120 disposed above the frame 110. The firing jig 100 shown in FIG. 13 also includes ribs (lower 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. Since the refractory mesh 120 is supported by the ribs 114, deformation of the refractory mesh 120 due to the weight of the firing targets can be prevented. However, in the support area SA of the firing jig 100 configured as described above, the ribs 114 block the flow of high-temperature gas in the height direction (the direction perpendicular to the plane of FIG. 13 ). Furthermore, in the support area 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 ribs 144. As a result, baking unevenness is likely to occur between the gas passage holes 116 and the support area SA.
[0041] 1 to 3, in the firing jig 1 according to this embodiment, the upper ribs 32 of the upper frame 30 are disposed on the lower ribs 12 of the lower frame 10. Therefore, when a large number of firing objects are distributed on the upper surface 20a of the refractory mesh 20, the firing objects are less likely to be placed on the support areas SA on the lower ribs 12. As a result, most of the firing objects can be heated above the gas passage holes 13. As a result, the various problems described above can be solved, and uneven firing can be suppressed when a large number of firing objects are fired simultaneously.
[0042] Furthermore, in the firing jig 1 according to this embodiment, protrusions 15 protrude from the outer frame 11. The protrusions 15 protrude above the upper surface 20a of the refractory mesh 20 via the second cutouts 23, above U. This prevents the firing objects from being placed on the outer frame 11. As a result, the number of firing objects heated above the gas passage holes 13 further increases, making it possible to further uniform the heating efficiency for the multiple firing objects.
[0043] 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] <Second embodiment> FIG. 8 is a plan view of a firing jig according to a second embodiment. In the first embodiment described above, protrusions 15 protruded from the outer frame 11 of the lower frame 10 (see FIGS. 1 to 3). However, the protrusions on the lower frame are not an essential component of the firing jig disclosed herein. Specifically, in the firing jig 1A according to the second embodiment, no protrusions are formed on the outer frame 11 of the lower frame 10 (see FIG. 8). Even with this configuration, firing unevenness can be sufficiently suppressed when multiple firing objects are fired simultaneously. Specifically, in a typical firing process, the objects are placed in a distributed manner around the center of the firing jig to prevent them from falling off the firing jig. Therefore, when using a typical firing jig, the objects are rarely placed on the outer peripheral edge of the refractory mesh 20 (i.e., above the outer frame 11, U). Therefore, poor firing due to the interruption of high-temperature gas is most likely to occur in the support area SA on the lower rib 12 located in the center of the firing jig 1A. For this reason, if the upper rib 32 of the upper frame 30 is placed on the lower rib 12, the occurrence of uneven firing can be sufficiently suppressed.
[0045] Furthermore, in the firing jig 1 according to the first embodiment, the support pillars 16 protruding upward U from the lower frame 10 are formed (see FIGS. 1 to 3). However, these support pillars are not an essential component of the firing jig disclosed herein. Specifically, in the firing jig 1A shown in FIG. 8, no support pillars are formed on the lower frame 10. However, in the firing jig 1A shown in FIG. 8, other firing jigs can be stacked on the upper frame 30. Even when such a configuration is adopted, the firing efficiency per unit area can be improved.
[0046] <Third embodiment> FIG. 9 is a plan view of a firing jig according to a third embodiment. FIG. 10 is a cross-sectional view taken along the arrow XX in FIG. 9. As described above, in the first embodiment, the protrusions 15 are formed on the outer frame 11 to prevent firing defects in the area above the outer frame 11 (see FIGS. 1 to 3). However, firing defects in the area above the outer frame 11 can also be prevented by a configuration other than the protrusions 15. For example, as shown in FIG. 9, in a firing jig 1B according to the third embodiment, a damming portion 24 is provided on the outer peripheral edge portion 20b of the refractory mesh 20, the damming portion 24 being higher than the height of the central portion 20c of the refractory mesh 20. As shown in FIG. 10, the damming portion 24 is a portion formed by folding the outer peripheral edge portion 20b of the refractory mesh 20. The damming portion 24 having such a configuration prevents a firing target from being placed in the area above the outer frame 11, thereby preventing firing defects in the area above the outer frame 11 without providing a protrusion on the lower frame.
[0047] Furthermore, the upper frame 30 in this embodiment is configured so as not to interfere with the damming portions 24 of the fire-resistant mesh 20. Specifically, the first upper rib 32a in the first and second embodiments extends from the left end to the right end of the lower frame 10 along the width direction X (see FIGS. 2 and 8). The second upper rib 32b extends from the upper end to the lower end of the lower frame 10 along the depth direction Y. On the other hand, as shown in FIG. 9, in the third embodiment, the lengths of the first upper rib 32a and the second upper rib 32b are specified so that the upper frame 30 is accommodated inside the damming portions 24 of the fire-resistant mesh 20. This allows the upper frame 30 to be easily positioned on the upper surface 20a of the fire-resistant mesh 20.
[0048] <Fourth embodiment> FIG. 11 is a cross-sectional view of a firing jig according to a fourth embodiment. In the firing jig 1C shown in FIG. 11, a blocking portion 24 is formed by bending the outer peripheral edge portion 20b of the refractory mesh 20 upward in a U direction. The blocking portion 24 having such a configuration can prevent a firing target from being placed in the area above the outer frame 11, thereby suppressing firing defects in that area. The blocking portion 24 in this embodiment, in which the refractory mesh 20 is bent upward in a U direction, can easily ensure the height of the blocking portion 24, thereby more effectively suppressing firing defects in the area above the outer frame 11. However, considering the strength of the blocking portion 24, it is preferable to form the blocking portion 24 by folding the refractory mesh 20 as shown in FIG. 10.
[0049] <Fifth embodiment> Fig. 12 is a plan view of the upper frame in the fifth embodiment. The upper frame 30 shown in Fig. 12 includes, in addition to the upper ribs 32 described above, a rectangular upper outer frame 34 that surrounds the upper ribs 32. This upper outer frame 34 faces the outer frame 11 of the lower frame 10, with the fireproof mesh 20 sandwiched between them. When the upper frame 30 including this upper outer frame 34 is used, it is possible to prevent the object to be fired from being placed in the area above the outer frame 11, just as in the case where the protrusions 15 (see Fig. 2) are used. Note that the dimensions of the upper outer frame 34 can be determined using the dimensions of the protrusions 15 described above, and therefore a repeated explanation will be omitted.
[0050] <Other embodiments> Although not shown, the firing jig disclosed herein may adopt configurations other than those of the first to fifth embodiments. For example, in the first to fifth embodiments, the first upper rib 32a and the second upper rib 32b are connected to form a single upper frame 30. However, the number of upper frames placed on the refractory mesh is not particularly limited. For example, an upper frame having an upper rib facing the first lower rib 12a in FIG. 5 and an upper frame having an upper rib facing the second lower rib 12b may be separately manufactured, and each upper frame may be placed on the metal mesh. Even when such a configuration is adopted, it is possible to sufficiently prevent the firing object from being placed on the support area.
[0051] Furthermore, the upper rib 32 in the first to fifth embodiments is a tapered rib that narrows toward the upper end. However, the upper rib 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 upper rib. However, by brushing off the firing objects that have rested on the upper rib before placing them in the firing furnace, firing defects on the upper rib protrusions can be prevented. However, from the perspective of reducing such work and improving production efficiency, it is preferable to form a tapered upper rib, as in the first to fifth embodiments.
[0052] 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, an upper frame having upper ribs facing each of the lower ribs can be used. This prevents objects to be baked from being placed above the lower ribs, thereby suppressing uneven baking when multiple objects to be baked are baked simultaneously.
[0053] 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.
[0054] The technology disclosed herein includes the following items 1 to 9. The following items 1 to 9 are not limited to the above-described embodiment.
[0055] [Item 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; It is equipped with The upper frame is provided with upper ribs that face the lower ribs with the refractory mesh interposed therebetween.
[0056] [Item 2] Item 2. The firing jig according to item 1, wherein the upper rib is a tapered rib that narrows toward its upper end.
[0057] [Item 3] 3. The firing jig according to claim 1, wherein the upper rib extends continuously along the extension direction of the lower rib.
[0058] [Item 4] the lower frame further includes a protrusion protruding upward from the outer frame, 4. The firing jig according to any one of items 1 to 3, wherein the protrusions protrude above an upper surface of the refractory mesh through cutouts in the refractory mesh.
[0059] [Item 5] 4. The firing jig according to any one of items 1 to 3, wherein the upper frame is provided with a second upper rib facing the outer frame with the refractory mesh interposed therebetween.
[0060] [Item 6] the lower frame includes three or more support columns projecting upward from the outer frame and / or the lower rib; 6. The firing jig according to any one of items 1 to 5, wherein the height of the support columns is greater than the height of the upper frame.
[0061] [Item 7] 7. The firing jig according to any one of items 1 to 6, wherein a damming portion higher than the height of the center of the refractory mesh is provided on the outer peripheral edge of the refractory mesh.
[0062] [Item 8] 8. The firing jig according to item 7, wherein the blocking portion is a portion where the outer peripheral edge of the refractory mesh is folded over.
[0063] [Item 9] 8. The firing jig according to item 7, wherein the blocking portion is a portion where the outer peripheral edge of the refractory mesh is bent upward. [Explanation of symbols]
[0064] 1: Firing jig 10: Lower frame 11: Outer frame 12: Lower rib 13: Gas passage hole 14: 1st protrusion 15: Protrusion 16: Strut 20: Fireproof mesh 21: Opening 22: First notch 23: Second notch 24: Dam section 30: Upper frame 32: Upper rib
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; It is equipped with The upper frame is provided with upper ribs that face the lower ribs with the refractory mesh interposed therebetween.
2. 2. The firing jig according to claim 1, wherein the upper rib is a tapered rib that narrows toward its upper end.
3. The firing jig according to claim 1 , wherein the upper rib extends continuously in the direction in which the lower rib extends.
4. the lower frame further includes a protrusion protruding upward from the outer frame, The firing jig according to claim 1 , wherein the protrusions protrude above an upper surface of the refractory mesh through cutouts in the refractory mesh.
5. The firing jig according to claim 1 , wherein the upper frame is provided with a second upper rib that faces the outer frame with the refractory mesh interposed therebetween.
6. 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 columns is greater than the height of the upper frame.
7. 2. The firing jig according to claim 1, wherein a damming portion higher than a central portion of the refractory mesh is provided on an outer peripheral edge of the refractory mesh.
8. 8. The firing jig according to claim 7, wherein the blocking portion is a folded portion of the outer peripheral edge of the refractory mesh.
9. The firing jig according to claim 7 , wherein the blocking portion is a portion where an outer peripheral edge of the refractory mesh is bent upward.
Citation Information
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