JP2006036573A - Sheath for ceramic burning, and method for burning ceramic molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheath for ceramic burning into which atmospheric gas can sufficiently be made to flow during the burning of ceramic molded bodies, and to provide a method of burning the ceramic molded body. <P>SOLUTION: The sheath 10 is provided with a bottom plate 31 having 4 sides and a pair of side walls 33 and 33 which are erected along only opposed two sides among the above 4 sides, and a rod R through which the ring-like ceramic molded bodies 1 are placed is bridged and supported on the side walls 33 and 33. In order to position the bridged rods R, a plurality of recesses 40 are provided on the respective side walls 33. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ceramic firing sheath used when firing a ring-shaped ceramic molded body, and a method for firing a ceramic molded body using the ceramic firing sheath.

2. Description of the Related Art Conventionally, as a sheath (bamboo mortar) used when firing a ring-shaped ceramic molded body, one having a rectangular frame portion that supports a rod on which the ceramic molded body is arranged is known (for example, Patent Documents). 1). The sheath described in Patent Document 1 includes a frame portion that extends in parallel to the rod to be supported and a frame portion that extends in the vertical direction. Further, by providing a convex portion at the center of the frame portion extending in parallel with the supporting rod, the strength of the frame portion is increased, and the mechanical strength capable of withstanding the weight of the ceramic molded body to be loaded is maintained.
JP 2002-343609 A

  Usually, a ring-shaped ceramic molded body is fired by introducing sheaths in which the ceramic molded bodies are arranged in multiple stages into a firing furnace and exposing to a gas constituting a firing atmosphere (hereinafter referred to as atmosphere gas). Has been.

  By the way, in recent years, there is a high demand for miniaturization of ceramic electronic components, and the number of ring-shaped ceramic molded bodies used for electronic components is increasing. In the downsized ring-shaped ceramic molded body, since the inner diameter of the ring is small, it is difficult for atmospheric gas to flow into the inside of the ring in a state where the ring is disposed in the sheath during firing. In order to sufficiently expose the atmosphere of the ring-shaped ceramic molded body to the inside of the ring, it is necessary to sufficiently flow the atmosphere gas into the sheath.

  However, the sheath described in Patent Document 1 described above has a small opening area when the sheaths are stacked in multiple stages due to the convex portions provided in the frame portion of the sheath. For this reason, in order to use this sheath for firing such a small ring-shaped ceramic molded body, the inflow of the atmospheric gas into the interior is not sufficient. Therefore, if this sheath is used for firing a small ring-shaped ceramic molded body, the ceramic molded body is fired in a state where the inside of the ring is not sufficiently exposed to the atmospheric gas, and as a result, the fired ceramic molded body ( There is a risk of firing failure in the ceramic sintered body.

  The present invention has been made in order to solve the above-mentioned problems, and at the time of firing a ceramic molded body, a sheath for ceramic firing that can sufficiently flow an atmospheric gas into the inside of the sheath, and firing of the ceramic molded body It aims to provide a method.

  In order to solve the above problems, the ceramic firing sheath of the present invention is a ceramic firing sheath for firing a ring-shaped ceramic molded body, and is opposed to a plate-like bottom portion having four sides and the four sides. A pair of side wall portions for bridging the rods that are erected on the bottom so as to be along only two sides and for arranging the ring-shaped ceramic molded body, and each side wall portion includes a plurality of side walls for positioning the rods. A recess is formed.

  In this ceramic firing sheath, side walls are provided on two opposite sides of the bottom having four sides, on which a rod for arranging the ceramic molded body is bridged. Since these side walls are erected so as to extend along only two opposite sides at the bottom, this sheath has a large opening area when stacked in multiple stages, and the supplied atmospheric gas is smoothly inside the sheath. Flow into.

  Further, the sheath for ceramic firing of the present invention is provided at the bottom so as to extend in parallel with the side wall, and it is possible to bridge a rod for arranging a ring-shaped ceramic molded body between the side wall and the rod. There may be further provided a support wall portion in which a plurality of recesses for positioning is formed. According to this sheath, a bar shorter than the distance between the side wall portions can be used.

  Moreover, it is preferable that the bottom part is provided with the through-hole which penetrates the said bottom part in the thickness direction. According to such a ceramic firing sheath, when the sheaths are stacked in multiple stages, the atmosphere gas flowing into the stacked sheaths flows between the sheaths adjacent to each other in the stacking direction, so that the atmosphere gas flows into the sheath. Becomes even smoother.

  Further, the firing method of the ceramic molded body of the present invention is a firing method for firing a ring-shaped ceramic molded body, a rod for arranging the ring-shaped ceramic molded body, and a plate-like bottom portion having four sides. And a pair of side wall portions for bridging a rod that is erected on the bottom portion so as to extend along only two opposite sides of the four sides, and to dispose the ring-shaped ceramic molded body, A ceramic firing sheath having a plurality of recesses for positioning the rod is prepared, a ring-shaped ceramic molded body is arranged on the rod, and the rod is placed between the side walls of the ceramic firing sheath. A step of delivering and arranging and a step of supplying a gas constituting the firing atmosphere to the sheath along the direction in which the rods are arranged to fire the ring-shaped ceramic molded body.

  In this method of firing a ceramic molded body, a sheath is used in which a side wall portion is erected along only two opposing sides of a bottom portion having four sides. The ring-shaped ceramic molded body is disposed on a rod, and the rod is arranged so as to span between the side wall portions facing each other. Since the side wall portion of the sheath is erected so as to extend along only two opposing sides at the bottom portion of the sheath, the atmospheric gas supplied along the direction in which the bars are arranged smoothly flows into the sheath. Thus, the atmosphere gas sufficiently flows into the ceramic firing sheath, so that firing failure of the ceramic molded body is suppressed.

  Further, the firing method of the ceramic molded body of the present invention is a firing method for firing a ring-shaped ceramic molded body, a rod for arranging the ring-shaped ceramic molded body, and a plate-like bottom portion having four sides. And a pair of side wall portions for bridging a rod that is erected on the bottom portion so as to extend along only two opposite sides of the four sides, and to dispose the ring-shaped ceramic molded body, A ceramic firing sheath having a plurality of recesses for positioning the rod is prepared, a ring-shaped ceramic molded body is arranged on the rod, and the rod is placed between the side walls of the ceramic firing sheath. And a step of supplying the gas constituting the firing atmosphere to the sheath from the direction intersecting the bottom, and firing the ring-shaped ceramic molded body.

  In this method of firing a ceramic molded body, a sheath is used in which a side wall portion is erected along only two opposing sides of a bottom portion having four sides. The ring-shaped ceramic molded body is disposed on a rod, and the rod is arranged so as to span between the side wall portions facing each other. Since the side wall portion of the sheath is erected so as to extend along only two opposing sides in the bottom portion, the atmospheric gas supplied from the direction intersecting the bottom portion of the sheath smoothly flows into the sheath. Thus, the atmosphere gas sufficiently flows into the ceramic firing sheath, so that firing failure of the ceramic molded body is suppressed.

  According to the ceramic firing sheath and the ceramic firing method of the present invention, the atmosphere gas can sufficiently flow into the sheath when firing the ring-shaped ceramic molded body.

  Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a ceramic firing sheath and a method for firing a ceramic molded body according to the present invention will be described in detail. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
In the present embodiment, the present invention is applied to a method for manufacturing a porcelain (hereinafter referred to as a varistor porcelain) using a varistor. FIG. 1 is a flowchart for explaining the manufacturing process of the varistor ceramic according to the present embodiment. In addition, about a well-known manufacturing process, description is simplified.

  First, the ceramic molded body 1 shown in FIGS. 2A and 2B is produced (molding step: S101). In the molding step S101, the raw material powder is processed in the order of mixing, calcination, pulverization, and molding to obtain the ceramic molded body 1 in which the holes 3 are formed.

  As the raw material powder, a powder of a compound containing each element constituting the varistor porcelain is usually used. As this raw material powder, an oxide or a compound that becomes an oxide by firing (for example, carbonate, hydroxide, etc.) is used. First, the raw material powder is weighed to have a desired composition and mixed (for example, wet mixing). Next, after dehydration, it is dried and pre-baked at about 1080 to 1250 ° C. for about 2 to 4 hours. Next, after pulverizing the temporarily fired product, an organic binder is added, and water, a pH adjuster, a moisturizing agent, and the like are further added and mixed. Next, the mixture is molded into a ring shape and subjected to a binder removal treatment. The outer peripheral shape of the ceramic molded body 1 and the shape of the hole 3 are circular in plan view. This ceramic molded body 1 is a varistor porcelain material used for a varistor that is smaller than the conventional one, and is formed with an outer diameter of 9 mm and an inner diameter of 6 mm.

  Next, a rod R is prepared. Then, as shown in FIG. 3, the ceramic molded body 1 is passed through the rod R and aligned in a skewered manner (bar piercing step: S103). The rod R has a circular cross section, and the diameter of the rod R is set smaller than the inner diameter of the ceramic molded body 1 (that is, the diameter of the hole 3). Here, the diameter of the rod R is set to 4 mm.

  At least one end of the rod R is formed in a conical shape (tapered shape). In the stick sticking step S103, the ceramic molded body 1 is passed through the stick R from the end side formed in a conical shape. Thereby, a predetermined number of ceramic molded bodies 1 are arranged on the rod R. As the material of the rod R, a material having heat resistance and fire resistance, for example, alumina, mullite, zirconia, or the like is used.

  Next, the sheath 10 is prepared, and the ceramic molded body 1 is disposed on the sheath 10 (sheath filling step: S105). As shown in FIG. 4, the sheath 10 includes a bottom plate (bottom portion) 31 and a pair of parallel side wall portions 33 and 33 erected on the bottom plate 31. The bottom plate 31 has a rectangular shape having four sides, and is provided with a plurality of through-holes 37 having a circular cross section penetrating in the thickness direction. The side wall 33 is erected along only two opposite sides of the four sides of the bottom plate 31. That is, no side wall is provided at a position along the other two sides of the bottom plate 31. The side wall portions 33 and 33 are formed at the same height from the bottom plate 31.

  A plurality of recesses 40 are formed at equal intervals on the upper surface 35 of the side wall 33. Each recess 40 is a groove having a substantially V-shaped longitudinal section. The concave portions 40, 40 are provided at positions facing the side wall portions 33, 33 so as to form a pair, and are arranged in a direction in which the side wall portions 33, 33 extend. The rod R on which the ceramic molded body 1 is arranged is bridged between the side wall portions 33 and 33 and supported by the side wall portions 33 and 33. At this time, both ends of the spanned rod R are positioned by engaging with the recesses 40, 40 that are paired with the side walls 33, 33. The depth of each recess 40 or the thickness in the vertical direction of the side wall 33 at the position where the recess 40 is formed is determined in the state where the rod R on which the ceramic molded body 1 is disposed is positioned in the recess 40. It is set so that the ceramic molded body 1 disposed on the upper surface 35 does not come into contact with the bottom plate 31 and does not protrude from the upper surface 35. In other words, the depth of each recess 40 is set so that the ceramic molded body 1 is within the thickness range in the vertical direction of the side wall 33. The intervals at which the concave portions 40 are arranged are set so that the ceramic molded bodies 1 arranged on the adjacent rods R are not in contact with each other when the rod R on which the ceramic molded bodies 1 are arranged is positioned in the concave portion 40. The outer diameter of the ceramic molded body 1 is set larger.

  In the sheath 10, a region sandwiched between the side surfaces 33, 33, the plane including the upper surface 35, and the bottom plate 31 is a molded body arrangement region 39 in which the plurality of ceramic molded bodies 1 are arranged. As the material of the sheath 10, a material having heat resistance and fire resistance, for example, alumina, mullite, zirconia, or the like is used. In addition, since the ceramic molded body 1 is a molded body that is a lighter varistor porcelain that is smaller than the conventional one, the ceramic molded body 1 is lighter than the conventional one. For this reason, the sheath 10 can sufficiently withstand the loading of the ceramic molded body 1 even if the side walls of the two sides are omitted. By omitting these two side wall portions, the sheath 10 does not have a side wall portion that overlaps the molded body arrangement region 39 when viewed from the direction in which the side wall portions 33 and 33 extend.

  After the sheath 10 is prepared, as shown in FIGS. 5 and 6, a plurality of rods R on which the ceramic molded body 1 is disposed are bridged between the opposing side wall portions 33 and 33. Each spanned rod R is positioned by engaging both ends with the corresponding recesses 40, 40. The plurality of rods R are arranged substantially parallel to the direction in which the recesses 40, 40 are arranged, that is, the direction in which the side walls 33, 33 extend. As a result, the plurality of ceramic molded bodies 1 are packed and the ceramic molded body 1 is arranged in the molded body arrangement region 39 of the sheath 10. At this time, as shown in FIG. 5, the ceramic molded body 1 is supported in a state of being suspended from the rod R in the molded body arrangement region 39, and arranged in the arrangement direction of the rod R (that is, parallel to the bottom plate 31 and to the rod R). It is positioned so as not to be shielded by the sheath 10 when viewed from the vertical direction.

Next, the ceramic molded body 1 is fired in the firing furnace 20 (firing step: S107). Firing of the ceramic molded body 1 is performed in a reducing atmosphere. As shown in FIG. 7, the firing furnace 20 has an inlet portion 21 at one end and an outlet portion 23 at the other end, and has a tunnel shape. The inside of the firing furnace 20 is a reducing atmosphere, and the gas constituting the reducing atmosphere (for example, a mixed gas of N ₂ and H ₂ ) is opposite to the conveying direction of the sheath 10 (the direction of arrow A in FIG. 7). It flows in the direction (the direction of arrow B in FIG. 7).

  In the firing step S107, as shown in FIG. 7, the sheaths 10 after the sheath filling step S105 are stacked in multiple stages (here, 5 stages) and placed on the base plate 25, and the base plate 25 is pushed by the pusher 27 to thereby support the sheath. 10 is conveyed into the firing furnace 20. Thereby, the ceramic molded body 1 is reduced and fired in a state of being disposed on the rod R, and a varistor porcelain is obtained. The sheath 10 is placed on the base plate 25 so as to be conveyed with the arrangement direction of the rods R as the front-rear direction. As described above, the sheath 10 is conveyed through the firing furnace 20, so that the gas constituting the reducing atmosphere in the firing furnace 20 (hereinafter referred to as reducing atmosphere gas) sheaths along the arrangement direction of the rods R. 10 molded body arrangement regions 39 are supplied.

  As shown in FIG. 8, in the firing step S <b> 107, the lid 29 is placed on the uppermost sheath 10. Specifically, the lid 29 is placed on the upper surface 35 of the side wall portion 33. At this time, an opening G1 corresponding to the width of the bottom plate 31 and the height of the side wall 33 is formed between the lid 29 and the bottom plate 31 of the uppermost sheath 10 on the front side and the rear side in the transport direction. Become. Further, between the sheaths 10 and 10 adjacent in the stacking direction, an opening G2 corresponding to the width of the bottom plate 31 and the height of the side wall portion 33 is formed on the front side and the rear side in the transport direction. As described above, the stacked sheaths 10 have a large opening area when viewed from the direction in which the reducing atmosphere gas flows, and the reducing atmosphere gas can be easily transferred to the molded body arrangement region 39 inside the sheath 10 by the large opening area. You can go in and out.

  For this reason, in the firing furnace 20, the reducing atmosphere gas smoothly flows into the sheath 10 through the openings G <b> 1 and G <b> 2 on the transport direction front side. In the firing furnace 20, the space above the stacked sheaths 10 is wide, and the flow rate and flow rate of the reducing atmosphere gas in this space are large. Therefore, the reducing atmosphere gas flowing from the openings G1 and G2 close to the space. There are especially many.

  Since the through holes 37 are formed in the bottom plate 31 of the sheath 10, the molded body arrangement regions 39 adjacent to the sheath 10 in the stacking direction are connected via the through holes 37. For this reason, the reducing atmosphere gas that has flowed into the sheath 10 flows in the stacking direction in the inner space defined by the stacked sheaths 10 while passing through the through-hole 37. And the reducing atmosphere gas containing the combustion component which generate | occur | produced from the ceramic molded object 1 is discharged | emitted smoothly from opening G1, G2 located in the conveyance direction rear side.

  In this way, in the firing step S107, sufficient reducing atmosphere gas is distributed over the molded body arrangement region 39 inside the sheath 10. For this reason, even if the hole 3 of the ceramic molded body 1 is small, the reducing atmosphere gas sufficiently flows into the inside of the ring of the ceramic molded body 1 (inside the hole 3). The ceramic molded body 1 is fired while being sufficiently exposed to the reducing atmosphere gas to the inside of the ring, and a ceramic sintered body (varistor porcelain) is obtained.

  Next, the obtained ceramic sintered body is taken out from the sheath 10 (pod opening step: S108). In the sheath opening step S108, the rod R is removed from the sheath 10 while being kept substantially horizontal. In addition, you may transfer a ring-shaped ceramic sintered compact to the next process in the state distribute | arranged to the stick | rod R. FIG.

  As described above, according to the firing method described above, in the firing step S107, the reducing atmosphere gas smoothly enters and exits the molded body placement region 39 inside the sheath 10, thereby providing a sufficient reducing atmosphere in the molded body placement region 39. Gas goes around. As a result, since the ceramic molded body 1 is fired while being sufficiently exposed to the reducing atmosphere gas, firing failure of the ceramic molded body 1 is suppressed. Further, since the through holes 37 are provided in the bottom plate 31 of the sheath 10, the reducing atmosphere gas easily flows between the sheaths 10 in the stacking direction. This also facilitates the flow of reducing atmosphere gas entering and exiting the openings G1 and G2. In addition, since the ceramic molded body 1 disposed in each part of the molded body arrangement region 39 of each sheath 10 is exposed to the reducing atmosphere gas without unevenness, the variation in the firing state of each ceramic molded body 1 is reduced, Variation in characteristics of the obtained varistor ceramic is suppressed.

(Second Embodiment)
Next, a second embodiment of the ceramic firing sheath and the ceramic molded body firing method according to the present invention will be described. In the first embodiment described above, the flow of the reducing atmosphere gas is generated in the firing furnace 20 in the direction opposite to the direction in which the sheath 10 is transported (arrow B in FIG. 7). The flow of the atmospheric gas is generated vertically downward (arrow C in FIG. 7). As a result, the reducing atmosphere gas in the firing furnace 20 is supplied from the direction orthogonal to the bottom plate 31 of the sheath 10 (that is, the direction orthogonal to the rod R) to the molded body arrangement region 39.

  In the firing step S <b> 107, the sheath 10 is stacked and placed on the base plate 25, but the lid 29 is not placed on the uppermost sheath 10. As a result, the reducing atmosphere gas easily flows into the molded body arrangement region 39 of the uppermost sheath 10.

  Further, since the bottom plate 31 of the sheath 10 is provided with the through hole 37, the molded body arrangement regions 39 of the sheath 10 adjacent to each other in the stacking direction are connected via the through hole 37. Therefore, the reducing atmosphere gas that has flowed into the uppermost sheath 10 flows one after another to the lower sheath 10 while passing through the through-hole 37, and reaches all the molded body arrangement regions 39 of all the sheaths 10. And the reducing atmosphere gas containing the combustion component which generate | occur | produced from the ceramic molded body 1 is discharged | emitted from opening G1, G2. In this manner, since sufficient reducing atmosphere gas is distributed to the molded body arrangement regions 39 of the sheaths 10, the same effects as those of the first embodiment can be obtained also in the firing method of the present embodiment.

  The present invention is not limited to the embodiment described above. The sheaths according to the present invention may be sheaths 10B, 10C, 10D as shown in FIGS. As shown in FIG. 9, the sheath 10 </ b> B includes a bottom plate 31 and side wall portions 33 and 33, and the bottom plate 31 is not provided with a through hole. As shown in FIG. 10, the bottom plate 31 of the sheath 10C is provided with one through hole 37C that penetrates the bottom plate 31 in the thickness direction. The through-hole 37 </ b> C is formed in a rectangular shape slightly smaller than the bottom plate 31 in the central portion of the bottom plate 31. This sheath 10C is preferable in that the atmosphere gas flows in the stacking direction more smoothly in the firing step, and the atmosphere gas flowing into and out of the sheath 10C becomes smoother.

  As shown in FIG. 11, the sheath 10D includes a bottom plate 31, a pair of side wall portions 33a and 33b erected along two sides of the bottom plate 31, and a support wall portion 34a extending in parallel with the side wall portions 33a and 33b. , 34b. Concave portions 40 are formed in the support wall portions 34a and 34b at equal intervals so as to correspond to the grooves formed in the side wall portions 33a and 33b. A plurality of rods R can be bridged and supported between the side wall 33a and the support wall 34a, and both ends of the spanned rod R are respectively connected to the recess 40 and the support wall of the side wall 33a. It engages with the recess 40 of 34a. Similarly, a plurality of rods R can be bridged and supported between the side wall portion 33b and the support wall portion 34b, and both ends of the bridged rod R are respectively recessed portions 40 of the side wall portion 33b. And the recess 40 of the support wall 34b.

  According to this sheath 10D, a rod shorter than the distance between the side wall portions 33a and 33b can be used. By shortening the rod, the rod can withstand the weight of the ceramic compact even if the rod diameter is reduced. Therefore, the diameter of the rod can be reduced, and the gap between the rod and the inside of the ring of the ceramic molded body can be set large. As a result, the atmospheric gas can flow more smoothly into the ring of the ceramic molded body, and the firing failure of the ceramic molded body can be further suppressed.

  Moreover, in the said embodiment, although the ceramic molded object 1 arrange | positioned to the said sheath 10 is baked, conveying the sheath 10, it is not restricted to this, A ceramic molded object is baked without conveying a sheath. May be. Further, the flow of the reducing atmosphere gas is generated in the firing furnace 20, but if the inside of the firing furnace 20 is a reducing atmosphere, the flow of the reducing atmosphere gas is not necessarily generated.

  Further, when the sheaths 10 stacked on the base plate 25 are placed, they may be placed without any gap in the transport direction (that is, so that the end portions of the sheaths adjacent in the transport direction are in contact with each other). By such placement, the placement efficiency of the sheath 10 on the base plate 25 can be improved, and the ceramic molded body 1 can be efficiently introduced into the firing furnace 20. Since the stacked sheaths 10 are formed with large openings G1 and G2 when viewed from the transport direction, sufficient atmosphere gas flows into the molded body arrangement region 39 even if such placement is performed. In addition, stacking the sheaths 10 is not essential, and the number of stages to be stacked is not limited to the above.

  Moreover, in this embodiment, although the inside of the baking furnace 20 was made into the reducing atmosphere, it is not restricted to this. What is necessary is just to select suitably according to the material used for the ceramic molded object 1, and air atmosphere or an inert gas atmosphere etc. may be sufficient.

  The present invention is not limited to the above-described method for manufacturing a varistor ceramic, and the same effect can be obtained when applied to a method for manufacturing a dielectric ceramic, a piezoelectric ceramic, or a semiconductor ceramic.

It is a flowchart for demonstrating the manufacturing process of the varistor porcelain which concerns on this embodiment. (A) is a top view which shows a ceramic molded body, (b) is a side view which shows a ceramic molded body. It is a front view which shows the stick | rod of the state by which the some ceramic molded object was distribute | arranged. It is a perspective view which shows a sheath. It is a top view which shows the sheath which supports the stick | rod which has arrange | positioned the ceramic molded body. FIG. 6 is a cross-sectional view taken along VI-VI in FIG. 5. It is the schematic for demonstrating a baking furnace. It is the front view which looked at the 5-stage pods stacked from the arrangement direction of the bars. It is a perspective view which shows one modification of a sheath. It is a perspective view which shows one modification of a sheath. It is a perspective view which shows one modification of a sheath.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ceramic molded object, 10 ... Sheath (sheath for ceramic baking), 31 ... Bottom plate (bottom part), 33 ... Side wall part, 34a, 34b ... Support wall part, 37, 37B ... Through-hole, 39 ... Molded object arrangement | positioning area | region, 40 ... recess, R ... bar, S101 ... molding step, S103 ... bar sticking step, S105 ... pod filling step, S107 ... firing step, S108 ... pod opening step.

Claims (5)

A ceramic firing sheath for firing a ring-shaped ceramic molded body,
A plate-like bottom having four sides;
A pair of side walls for bridging a rod that is erected on the bottom so as to be along only two opposite sides of the four sides, and for arranging the ring-shaped ceramic molded body,
Each of the side wall portions is provided with a plurality of concave portions for positioning the rod, and the sheath is a ceramic firing sheath.   It is provided in the bottom part so as to extend in parallel with the side wall part, and it is possible to bridge a rod for arranging the ring-shaped ceramic molded body between the side wall part, and a plurality of positions for positioning the bar The sheath for ceramic firing according to claim 1, further comprising a support wall portion in which a recess is formed.   3. The ceramic firing sheath according to claim 1, wherein the bottom portion is provided with a through-hole penetrating the bottom portion in the thickness direction. A firing method for firing a ring-shaped ceramic molded body,
A rod for arranging the ring-shaped ceramic molded body;
A plate-like bottom portion having four sides, and a pair of side wall portions for spanning a rod that is erected on the bottom portion so as to extend along only two opposite sides of the four sides and that arranges the ring-shaped ceramic molded body. A plurality of recesses for positioning the rod are formed on each of the side wall portions, and a sheath for ceramic firing is prepared,
Arranging the ring-shaped ceramic molded body on the rod, and arranging the rod across the side wall portion of the ceramic firing sheath;
Supplying a gas constituting a firing atmosphere to the sheath along the direction in which the rods are arranged, and firing the ring-shaped ceramic formed body. . A firing method for firing a ring-shaped ceramic molded body,
A rod for arranging the ring-shaped ceramic molded body;
A plate-like bottom portion having four sides, and a pair of side wall portions for spanning a rod that is erected on the bottom portion so as to extend along only two opposite sides of the four sides and that arranges the ring-shaped ceramic molded body. A plurality of recesses for positioning the rod are formed on each of the side wall portions, and a sheath for ceramic firing is prepared,
Arranging the ring-shaped ceramic molded body on the rod, and arranging the rod across the side wall portion of the ceramic firing sheath;
Supplying a gas constituting a firing atmosphere to the sheath from a direction intersecting the bottom, and firing the ring-shaped ceramic formed body.

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