JP4308703B2 - Method for firing ceramic molded body - Google Patents

Description

  The present invention relates to a method for firing a ceramic molded body.

As a method for firing this type of ceramic molded body, a sheath (bamboo mortar) on which the ceramic molded body is disposed is prepared, the sheath on which the ceramic molded body is disposed is introduced into a firing furnace, the ceramic molded body is fired, and the ceramic fired body is fired. What obtains a knot is known (see, for example, Patent Document 1).
JP-A-8-128789

  It is an object of the present invention to provide a method for firing a ceramic molded body that can suppress defective firing and variation in characteristics and improve yield.

  As a result of intensive studies on a method for firing a ceramic molded body capable of suppressing firing defects and characteristic variations, the present inventors have newly found the following facts.

  In the manufacturing method described in Patent Document 1, it has been newly found out that firing defects and characteristic variations occur due to the arrangement position of the ceramic molded body in the sheath. That is, depending on the arrangement position, the surroundings of the ceramic molded body cannot be adjusted to a desired firing atmosphere, or the combustion components generated from the ceramic molded body cannot be discharged smoothly from the sheath. Defects and characteristic variations will occur.

  Based on such research results, the method for firing a ceramic molded body according to the present invention provides a sheath having a molded body arrangement region in which a plurality of ceramic molded bodies are arranged, and a plurality of ceramic molded bodies are arranged in the sheath molded body arrangement region. And a step of firing a plurality of ceramic compacts arranged in the sheath compact placement region in a predetermined firing atmosphere. In the step of placing the ceramic compact, the compact placement region The ceramic molded body is not disposed in a predetermined region in the above.

  In the method for firing a ceramic molded body according to the present invention, since the ceramic molded body is not disposed in a predetermined region in the molded body arrangement region, firing defects and variation in characteristics are suppressed, and yield is improved. Can be made.

  Moreover, it is preferable that the predetermined area includes the central portion of the molded body arrangement area. The central part of the region where the ceramic molded body is arranged tends to be less likely to be adjusted to a desired firing atmosphere and the combustion components are less likely to be discharged than the peripheral part of the central part. Therefore, by not arranging the ceramic molded body at the center of the molded body arrangement region, it is possible to effectively suppress the occurrence of defective firing and characteristic variations.

  Further, in the step of firing the ceramic molded body, a gas constituting a predetermined firing atmosphere flows into the sheath, and the predetermined area is upstream of the center of the molded body arrangement area in the gas inflow direction. Preferably it is located. The region on the downstream side in the gas inflow direction from the central portion of the molded body arrangement region tends not to be adjusted to a desired firing atmosphere, and combustion components tend not to be discharged. Therefore, by not arranging the ceramic molded body on the upstream side in the gas inflow direction from the central portion of the molded body arrangement region, gas is supplied to the region on the downstream side in the gas inflow direction from the central portion of the molded body arrangement region. It becomes easy, and generation | occurrence | production of the baking defect and characteristic dispersion | variation can be suppressed effectively.

  Further, in the step of firing the ceramic molded body, a gas constituting a predetermined firing atmosphere flows into the sheath, and the predetermined area is downstream of the center of the molded body arrangement area in the gas inflow direction. Preferably it is located. By not arranging the ceramic molded body on the downstream side in the gas inflow direction from the central portion of the molded body arrangement region, it is possible to effectively suppress the occurrence of firing defects and characteristic variations.

  Further, in the step of firing the ceramic molded body, the ceramic molded body is fired while conveying the sheath, and the predetermined region is preferably located on the front side of the sheath in the conveying direction with respect to the central portion of the molded body arrangement region. . When firing the ceramic molded body while conveying the sheath, the area on the rear side of the sheath in the conveying direction from the center of the molded body arrangement area tends to be difficult to adjust to the desired firing atmosphere, and the combustion component is It tends to be difficult to discharge. Therefore, by not placing the ceramic molded body on the front side in the sheath conveyance direction from the center portion of the molded body arrangement region, a predetermined firing atmosphere is provided in the region on the rear side in the sheath transportation direction from the center portion of the molded body arrangement region. It becomes easy to supply the constituent gas, and it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  Further, in the step of firing the ceramic molded body, the ceramic molded body is fired while conveying the sheath, and the predetermined region may be located on the rear side in the sheath conveying direction from the central portion of the molded body arrangement region. preferable. By not arranging the ceramic molded body behind the sheath in the conveyance direction from the center of the molded body arrangement region, it is possible to effectively suppress the occurrence of firing defects and characteristic variations.

  Also, in the step of preparing a plurality of sheaths and firing the ceramic molded body, a plurality of sheaths are stacked in multiple stages, and a predetermined region of the sheath located on the upper side among the plurality of sheaths is located on the lower side. It is preferable that the width is set wider than the predetermined area. When multiple sheaths are stacked in multiple stages, the predetermined area of the molded body placement region in the lower sheath is adjusted to the desired firing atmosphere as compared to the predetermined area of the molded body placement region in the upper sheath The combustion component tends to be difficult to be discharged. Accordingly, by setting the predetermined region of the sheath positioned on the upper side wider than the predetermined region of the sheath positioned on the lower side, the gas constituting the predetermined firing atmosphere in the predetermined region of the sheath positioned on the lower side It becomes easy to supply, and generation | occurrence | production of the baking defect and characteristic dispersion | variation can be suppressed effectively.

  Also, in the step of preparing a plurality of sheaths and firing the ceramic molded body, a plurality of sheaths are stacked in multiple stages, and a predetermined region of the sheath located on the lower side of the plurality of sheaths is located on the upper side. It is preferable that the width is set wider than the predetermined area. By setting the predetermined region of the sheath positioned on the lower side wider than the predetermined region of the sheath positioned on the upper side, it is possible to effectively suppress the occurrence of firing defects and characteristic variations.

  In addition, the sheath is bottomless and has a frame part. In the step of arranging the ceramic molded body, the ceramic molded body is held by a member supported by the frame part to hold the ceramic molded body. It is preferable to arrange in the molded body arrangement region.

  Moreover, it is preferable that the through hole is formed in the ceramic molded body.

  Moreover, it is preferable that the ceramic molded body has a through-hole, and the ceramic sintered body obtained by sintering the ceramic molded body is a voltage-dependent nonlinear resistor ceramic.

  ADVANTAGE OF THE INVENTION According to this invention, the firing method of the ceramic molded body which can suppress a firing defect and characteristic variation and can improve a yield can be provided.

  Hereinafter, with reference to an accompanying drawing, a suitable embodiment of a firing method of a ceramic fabrication object concerning the present invention is 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.

  In the present embodiment, the present invention is applied to a method for manufacturing a voltage-dependent nonlinear resistor ceramic, that is, a ceramic used for a varistor (hereinafter referred to as a varistor ceramic). 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 is molded (molding step: S101). In the molding step S101, the raw material powder is processed in the order of mixing, calcination, pulverization, molding, and binder removal to obtain a ceramic molded body 1 in which the through holes 3 are formed (see FIGS. 2A and 2B). . Fig.2 (a) is a top view which shows a ceramic molded body, FIG.2 (b) is a side view which shows a ceramic molded body.

  As the raw material powder, a compound powder of each element constituting the varistor porcelain is usually used. As the raw material powder, an oxide or a compound that becomes an oxide by firing, such as a carbonate or a hydroxide, can be used. The raw material powder is weighed so that the final composition becomes a desired composition, and mixed (for example, wet mixing). Next, after dehydration, it is dried and pre-baked for about 2 to 4 hours at about 1080 to 1250 ° C. 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 through-hole 3 are circular in plan view.

  Next, as shown in FIGS. 3 to 5, the ceramic molded body 1 is passed through the rod R and aligned in a skewered manner (bar piercing step: S103). FIG. 3 is a plan view showing the sheath. FIG. 4 is a front sectional view showing a sheath. FIG. 5 is a side sectional view showing the sheath. 3 to 5 illustrate a state in which the sheath 10 supports the rod R on which the ceramic molded body 1 is arranged.

  The rod R has a circular cross-sectional shape when cut by a plane orthogonal to the central axis direction. The outer diameter of the rod R is smaller than the inner diameter of the through hole 3 of the ceramic molded body 1. 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. As a result, a predetermined number of ceramic molded bodies 1 are arranged on the rod R and held. As the material of the rod R, a material having heat resistance (fire resistance), for example, alumina, mullite, zirconia, or the like is used.

  Next, a plurality of ceramic molded bodies 1 are arranged on the sheath 10 (pod filling step: S105). In the sheath filling step S105, first, a sheath 10 is prepared (see FIGS. 3 to 5). The sheath 10 has a rectangular frame portion 11 and is bottomless. The frame portion 11 includes two portions 11a and 11b that face each other when viewed in the X-axis direction, and two portions 11c and 11d that face each other when viewed in the Y-axis direction. The sheath 10 supports both ends of the rod R on which the ceramic molded body 1 is held by the two opposing portions 11 a and 11 b of the frame portion 11.

  On the upper surface of the sheath 10, when the sheaths 10 are stacked, a raised portion 13 that engages with the sheath 10 located on the upper side and prevents lateral displacement is formed. On the lower surface of the sheath 10, a stepped portion 15 is formed at a position corresponding to the raised portion 13. The step-down portion 15 is formed so as to be drawn from the lower surface of the sheath 10 to the upper surface side. When the sheath 10 is stacked, the raised portion 13 of the frame portion 11 of the sheath 10 positioned on the lower side is engaged with the stepped-down portion 15. An inner region surrounded by the frame portion 11 (each portion 11a to 11d) becomes a molded body arrangement region 17 in which a plurality of ceramic molded bodies 1 are arranged. As the material of the sheath 10, a material having heat resistance (fire resistance), for example, alumina, mullite, zirconia, or the like is used.

  When the sheath 10 is prepared, a plurality of rods R holding the ceramic molded body 1 are bridged over two opposing portions 11a and 11b of the sheath 10 and supported at the corresponding portions 11a and 11b at both ends of the rod R, respectively. And arranged in parallel (see FIGS. 3 to 5). At this time, in order to prevent the ceramic molded body 1 from being arranged in the central portion 17a of the molded body arrangement region 17, a plurality (in the present embodiment, two in the central portion) of the two portions 11a and 11b facing the sheath 10 are arranged. ) Do not bridge the rod R. In the present embodiment, a plurality of rods R are not spanned, but only one rod R may be spanned. Moreover, you may use the sheath 10 in which the recessed part 15 is not formed in the said center part so that the rod R cannot be hold | maintained in the center part of the two parts 11a and 11b which the sheath 10 opposes. As a result, a plurality of ceramic molded bodies 1 are packed and a predetermined area including the central portion 17a of the molded body arrangement area 17 in the molded body arrangement area 17 (in the present embodiment, the central portion of the molded body arrangement area 17). The region extending to two opposing portions 11a and 11b of the sheath 10 including 17a, that is, the central region as viewed in the direction orthogonal to the rod R held by the sheath 10) 17b is arranged.

  In the two opposing portions 11a and 11b of the frame portion 11, a plurality of concave portions 19 are provided so that the rods R are positioned substantially parallel to each other and orthogonal to the two portions 11a and 11b. It is formed at intervals. Each recess 19 is a groove having a substantially V-shaped longitudinal section. The depth of the concave portion 19 (the thickness in the vertical direction of the frame portion 11 at the position where the concave portion 19 is formed) is held by the rod R while the rod R holding the ceramic molded body 1 is supported by the frame portion 11. The formed ceramic molded body 1 is set so as not to protrude from the sheath 10, that is, the ceramic molded body 1 falls within the range of the thickness in the vertical direction of the sheath 10. When the rod R holding the ceramic molded body 1 is supported by the frame portion 11, the interval between the recesses 19 is outside the ceramic molded body 1 so that the ceramic molded bodies 1 held by the adjacent rods R do not contact each other. It is set larger than the diameter.

Next, the ceramic molded body 1 is fired in the firing furnace 20 (firing step: S107). As shown in FIG. 6, 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. In the firing furnace 20, the firing atmosphere is a reducing atmosphere, and the gas constituting the reducing atmosphere (for example, a mixed gas of N ₂ and H ₂ ) is transported in the sheath 10 (in the direction of arrow A in FIG. 6). Flows in the opposite direction (the direction of arrow B in FIG. 6).

  In the firing step S107, as shown in FIG. 6, the sheaths 10 in which the plurality of ceramic molded bodies 1 are sheathed in the sheath filling step S105 are stacked in multiple stages (for example, three stages) and placed on the base plate 25. Then, the sheath 10 is conveyed into the firing furnace 20 by pushing the base plate 25 with the pusher 27. Thereby, the ceramic molded body 1 is reduced and fired while being held by the rod R, and a varistor ceramic as a ceramic sintered body is obtained. The sheath 10 is placed on the base plate 25 so that the central axis direction of the rod R held by the sheath 10 is substantially parallel to the transport direction.

  A lid 29 is placed on the uppermost sheath 10. A gap having a predetermined interval is formed between the lid 29 and the uppermost sheath 10. Further, a gap having a predetermined interval is also formed between the sheath 10 and the sheath 10. A gas constituting the reducing atmosphere flows into the sheath 10 from the front side in the transport direction through the gap. Usually, in the firing furnace 20, the space above the stacked sheaths 10 is wide, and the flow rate and flow velocity of gas in this space are large. Therefore, the gas mainly flows into the sheath 10 through a gap close to the space (for example, a gap between the lid 29 and the uppermost sheath 10). Since the sheath 10 is bottomless, the gas flowing into the sheath 10 circulates in the space defined by the stacked sheaths 10. And the gas containing the combustion component which generate | occur | produced from the ceramic molded object 1 is mainly discharged | emitted from the conveyance direction rear side of the several sheaths 10 piled up.

  By the way, when a plurality of ceramic molded bodies 1 are arranged in the whole of the molded body arrangement region 17 of the sheath 10, the ceramic molded body 1 arranged in the central portion 17 a of the molded body arrangement region 17 is more than the ceramic molded body 1. However, since the gas flow is inhibited by the ceramic molded body 1 arranged on the upstream side in the gas inflow direction, it is difficult to sufficiently supply the gas. Further, since it is difficult to sufficiently supply the gas, the combustion component generated from the ceramic molded body 1 arranged in the central portion 17a of the molded body arrangement region 17 is difficult to be discharged. For this reason, the ceramic molded body 1 arranged in the central portion 17a of the molded body arrangement region 17 cannot be fired in a desired reducing atmosphere, and the fired ceramic molded body 1 has poor firing and variation in characteristics. End up.

  In the firing furnace 20, sheaths 10 stacked in multiple stages are continuously arranged in the transport direction. For this reason, the sheath 10 located on the front side in the transport direction (upstream side in the gas flow direction in the firing furnace 20) obstructs, and in particular, the direction perpendicular to the transport direction and the stacking direction of the sheaths 10 It is difficult for gas to flow into the central region in the left-right direction).

  However, in this embodiment, as shown in FIG. 7, since the ceramic molded body 1 is not disposed in the predetermined region 17 b including the central portion 17 a of the molded body placement region 17 of the sheath 10, firing is performed. The occurrence of defects and characteristic variations can be suppressed. FIG. 7 is a schematic diagram for explaining an arrangement state of the ceramic molded body 1. In FIG. 7, for the sake of explanation, the area where the ceramic molded body 1 is actually arranged in the molded body arrangement area 17 is hatched.

  Next, the fired ceramic molded body 1 (varistor porcelain) is taken out from the sheath 10 (pod opening step: S109). In the sheath opening step S109, the rod R is removed from the sheath 10 while being kept substantially horizontal. Although the fired ceramic molded body 1 is held on the rod R, a force that compresses between the adjacent ceramic molded bodies 1 does not work at the time of firing, and therefore the ceramic molded body 1 held on the rod R. Do not adhere to each other. The ring-shaped varistor porcelain may be transferred to the next step while being held by the rod R.

  As described above, according to the present embodiment, since the ceramic molded body 1 is not disposed in the predetermined region 17b in the molded body placement region 17, the firing failure of the ceramic molded body 1 or the obtained varistor porcelain. The occurrence of the characteristic variation is suppressed, and the yield can be improved.

  Subsequently, a modified example of the method for manufacturing the varistor ceramic according to the present embodiment will be described with reference to FIGS. 8-18 is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. In FIG. 8 to FIG. 18, the area where the ceramic molded body 1 is actually arranged in the molded body arrangement area 17 is hatched for explanation.

  Since the modification described below is different from the above-described embodiment only in the sheath filling step S105, only the sheath filling step S105 will be described.

  As described above, it is difficult for gas to be sufficiently supplied to the ceramic molded body 1 arranged in the central portion 17a of the molded body arrangement region 17, and combustion components generated from the ceramic fired body are difficult to be discharged. Therefore, the center portion 17a of the molded body arrangement region 17 may be a predetermined region 17b in which the ceramic molded body 1 is not arranged as shown in FIG.

  When a plurality of ceramic molded bodies 1 are arranged over the entire molded body arrangement region 17 of the sheath 10, the region on the downstream side in the gas inflow direction from the central portion 17a of the molded body arrangement region 17 is more than the central portion 17a. Since the gas flow is hindered by the ceramic molded body 1 arranged on the upstream side in the gas inflow direction, it tends to be difficult to adjust to a desired firing atmosphere (reducing atmosphere), and the combustion component tends not to be discharged. is there. Therefore, as shown in FIG. 9, the predetermined region 17 b where the ceramic molded body 1 is not disposed is located upstream of the gas inflow direction (the arrow B direction in FIG. 9) from the central portion 17 a of the molded body disposed region 17. It may be located. By not arranging the ceramic molded body 1 on the upstream side in the gas inflow direction with respect to the central portion 17a of the molded body arrangement region 17, it is reduced to the region on the downstream side in the gas inflow direction with respect to the central portion 17a of the molded body arrangement region 17. It becomes easy to supply the gas constituting the atmosphere, and it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  Further, as shown in FIG. 10, the predetermined region 17 b where the ceramic molded body 1 is not disposed is arranged downstream of the gas inflow direction (arrow B direction in FIG. 10) from the central portion 17 a of the molded body disposed region 17. It may be located. Even if the ceramic molded body 1 is not disposed downstream of the central portion 17a of the molded body arrangement region 17 in the gas inflow direction, it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  When a plurality of ceramic molded bodies 1 are arranged in the whole of the molded body arrangement area 17 of the sheath 10, similarly, the area on the rear side in the conveying direction of the sheath 10 from the central portion 17 a of the molded body arrangement area 17 is the center. Since the gas flow is hindered by the ceramic molded body 1 arranged on the front side in the conveying direction of the sheath 10 from the portion 17a, it tends to be difficult to adjust to a desired firing atmosphere, and the combustion component tends not to be discharged. is there. Therefore, as shown in FIG. 11, the predetermined region 17 b in which the ceramic molded body 1 is not arranged is positioned in front of the sheath 10 in the conveyance direction (in the direction of arrow A in FIG. 11) with respect to the central portion 17 a of the molded body arrangement region 17. You may let them. By not placing the ceramic molded body 1 on the front side in the conveying direction of the sheath 10 relative to the central portion 17a of the molded body arrangement region 17, the region on the rear side in the conveying direction of the sheath 10 relative to the central portion 17a of the molded body arranging region 17 It becomes easy to supply the gas constituting the reducing atmosphere, and it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  Further, as shown in FIG. 12, the predetermined region 17b where the ceramic molded body 1 is not arranged is located behind the center portion 17a of the molded body arrangement region 17 in the conveying direction of the sheath 10 (the direction of arrow A in FIG. 12). It may be located. By not arranging the ceramic molded body 1 behind the sheath 10 in the conveying direction from the central portion 17a of the molded body arrangement region 17, it is possible to effectively suppress the occurrence of firing defects and characteristic variations.

  As described above, the gas mainly flows into the sheath 10 from a gap close to the space above the stacked sheath 10 (for example, a gap between the lid 29 and the uppermost sheath 10). For this reason, when the sheath 10 in which the plurality of ceramic molded bodies 1 are arranged in the entire molded body arrangement region 17 is stacked in multiple stages, the ceramic molded body 1 arranged in the molded body arrangement region 17 of the sheath 10 located on the lower side. In addition, since the gas flow is inhibited by the ceramic molded body 1 disposed in the molded body placement region 17 of the sheath 10 located on the upper side, it is difficult to sufficiently supply the gas.

  Therefore, as shown in FIGS. 13A to 13D, FIGS. 14A to 14D, and FIGS. 15A to 15D, the ceramic molded body 1 in the sheath 10 located on the upper side. The predetermined region 17b where no ceramics are disposed may be set wider than the predetermined region 17b where the ceramic molded body 1 in the sheath 10 located on the lower side is not disposed. By setting the predetermined region 17b of the sheath 10 positioned on the upper side wider than the predetermined region 17b of the sheath 10 positioned on the lower side, a reducing atmosphere is provided to the predetermined region 17b of the sheath 10 positioned on the lower side. It becomes easy to supply the gas which comprises. As a result, it is possible to effectively suppress the occurrence of defective firing and characteristic variations.

  Moreover, as shown in FIGS. 16A to 16D, FIGS. 17A to 17D, and FIGS. 18A to 18D, the ceramic molded body in the sheath 10 positioned on the lower side. The predetermined region 17b where 1 is not disposed may be set wider than the predetermined region 17b where the ceramic molded body 1 in the sheath 10 located on the upper side is not disposed. Even in this case, it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  14 (b), 14 (c), 17 (c), and 17 (d), the ceramic inflow body 1 is in a gas inflow direction from the central portion 17a of the formed body arrangement region 17 (FIG. 14). And in FIG. 17, it is not arranged upstream (in the direction of arrow B). Without being limited thereto, as shown in FIG. 10, the ceramic molded body 1 may not be disposed downstream of the central portion 17 a of the molded body arrangement region 17 in the gas inflow direction.

  15 (b), 15 (c), 18 (c), and 18 (d), the ceramic molded body 1 is transported in the sheath 10 more than the center portion 17a of the molded body arrangement region 17. (The arrow A direction in FIGS. 15 and 18) It is not arranged on the front side. Without being limited thereto, as shown in FIG. 12, the ceramic molded body 1 may not be disposed behind the sheath 10 in the conveying direction with respect to the central portion 17 a of the molded body arrangement region 17.

  Moreover, in FIGS. 13-18, the area of the predetermined | prescribed area | region 17b which does not arrange | position the ceramic molded object 1 differs for every stacked sheath 10. FIG. However, it is not necessary to vary the width of the predetermined region 17b for every sheath 10. For example, in FIG. 13A, the predetermined region 17 b in the upper sheath 10 and the predetermined region 17 b in the interrupted sheath 10 may be set to the same size and wider than the lower sheath 10. Similarly, for example, in FIG. 16A, the predetermined area 17b in the lower pod 10 and the predetermined area 17b in the interruption pod 10 may be set to the same size and wider than the upper pod 10.

  As mentioned above, although the invention made | formed by this inventor etc. was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment. For example, the shapes of the ceramic molded body 1 (through hole 3) and the sheath 10 are not limited to those described above. Moreover, the shape and size of the predetermined region 17b where the molded body arrangement region 17 and the ceramic molded body 1 are not arranged are not limited to those described above. Further, the number of stages in which the sheaths 10 are stacked is not limited to the above.

  In the present embodiment, the ceramic molded body 1 disposed on the sheath 10 is fired while the sheath 10 is conveyed. However, the present invention is not limited to this, and the ceramic molded body 1 is fired without conveying the sheath 10. May be. Further, the sheath 10 may be transported into the firing furnace 20 without being stacked. Moreover, although the flow of the gas constituting the reducing atmosphere in the firing furnace 20 is generated in the direction opposite to the direction in which the sheath 10 is conveyed, if the inside of the firing furnace 20 is a reducing atmosphere, it is not always necessary. There is no need to generate the gas flow.

  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.

  Further, in this embodiment, the ceramic molded body 1 is arranged on the sheath 10 by supporting the rod R holding the ceramic molded body 1 in which the through-hole 3 is formed with the sheath 10. As described above, the ceramic molded body 1 may be placed by being placed on the sheath 10.

  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 top view which shows a sheath. It is a front sectional view showing a sheath. It is a sectional side view showing a sheath. It is the schematic for demonstrating a baking furnace. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. It is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded body. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object. (A)-(d) is a schematic diagram for demonstrating the arrangement | positioning state of a ceramic molded object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic molded object, 3 ... Through-hole, 10 ... Saddle, 11 ... Frame part, 17 ... Molded object arrangement | positioning area | region, 17a ... Central part, 17b ... Predetermined area | region, 20 ... Firing furnace, R ... Rod, S101 ... Molding Step, S103 ... Sticking step, S105 ... Saddle filling step, S107 ... Sintering step, S109 ... Peeling step.

Claims (4)

Prepare a sheath that has a frame portion that surrounds a molded body arrangement region in which a plurality of ceramic molded bodies in which through-holes are formed are arranged, with a bottomless shape,
A plurality of ceramic molded bodies are arranged in the molded body arrangement region of the sheath by inserting a rod through the through-holes of the plurality of ceramic molded bodies and supporting both ends of the rod across the frame portion. And a process of
A plurality of the ceramic molded bodies are fired in a predetermined firing atmosphere while conveying the sheath in which the plurality of ceramic molded bodies are arranged in the molded body arrangement region in a direction parallel to the rod, and a ceramic sintered body And a step of obtaining
In the step of obtaining the ceramic sintered body, the gas constituting the predetermined firing atmosphere is caused to flow into the sheath from the front side in the sheath transport direction by flowing the gas in a direction opposite to the sheath transport direction. While firing a plurality of the ceramic molded body,
In the step of arranging the ceramic molded body, the predetermined region of the sheath including the entire central portion of the molded body arrangement region is arranged so as not to arrange the ceramic molded body in the central portion of the molded body arrangement region. A method for firing a ceramic molded body characterized by not spanning a rod . In the step of obtaining the ceramic sintered body, the gas constituting the predetermined firing atmosphere is caused to flow in a direction opposite to the conveying direction of the sheath in a state where a plurality of sheaths are stacked in multiple stages. While flowing into the sheath from the front side of the sheath conveying direction, firing the plurality of ceramic molded bodies,
When in the above step of placing the ceramic shaped body, without passing respectively over the rod in the predetermined region of the plurality of said sheath, said predetermined area of said sheath located above when stacked are stacked 2. The ceramic molded body according to claim 1, which includes the entire predetermined region of the sheath positioned on the lower side and is set wider than the predetermined region of the sheath positioned on the lower side. Firing method. In the step of obtaining the ceramic sintered body, the gas constituting the predetermined firing atmosphere is caused to flow in a direction opposite to the conveying direction of the sheath in a state where a plurality of sheaths are stacked in multiple stages. While flowing into the sheath from the front side of the sheath conveying direction, firing the plurality of ceramic molded bodies,
In the step of placing the ceramic molded body is not bridged to each said bar said in a predetermined region of a plurality of said sheath, said predetermined region of the sheath positioned on the lower side when the stack is piled 2. The ceramic molded body according to claim 1, wherein the ceramic molded body includes the entire predetermined region of the sheath that is sometimes located on the upper side and is set wider than the predetermined region of the sheath that is located on the upper side . Firing method. The ceramic sintered body obtained by firing the ceramic molded body is a voltage-dependent non-linear resistance ceramic, and the ceramic molded body according to any one of claims 1 to 3 . Firing method.

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