JP4287786B2 - Sheath for ceramic firing and method for firing ceramic molded body - Google Patents

Description

  The present invention relates to a ceramic firing sheath and a method for firing a ceramic molded body using the ceramic firing sheath.

Forming an opening for placing the ceramic molded body as a sheath (slag) used when firing a ceramic molded body, particularly a ceramic molded body (for example, a ring-shaped ceramic molded body) in which through holes are formed. The thing provided with the frame part to perform is known (for example, refer patent document 1). In the sheath described in Patent Document 1, the ceramic molded body is disposed in the opening by supporting the rod on which the ceramic molded body is disposed in the frame portion.
JP 2002-343609 A

  It is an object of the present invention to provide a ceramic firing sheath suitable for a ceramic molded body in which a through hole having a small inner diameter is formed, and a method for firing the ceramic molded body.

  As a result of intensive studies on a sheath for ceramic firing suitable for a ceramic molded body having a through hole having a small inner diameter, the present inventors have newly found the following facts.

  The rod used for firing the ceramic molded body is usually repeatedly used and exposed to a high temperature each time. That is, the rod is repeatedly exposed to a high temperature in a state where a load (stress load) is received from the ceramic molded body disposed on the rod. For this reason, the elastic modulus or strength of the rod decreases, creep occurs, and the rod deforms. When the rod is deformed, the ceramic molded bodies arranged on the rod are easily brought into contact with each other. If adjacent ceramic molded bodies are in contact with each other, the contacted portions are not sufficiently fired, resulting in firing failure (appearance failure) and characteristic variations.

  By the way, in recent years, there is a strong demand for downsizing and thinning of electronic components used in electronic devices, and in order to obtain a ceramic sintered body used for electronic components such as voltage-dependent nonlinear resistors (hereinafter referred to as varistors). It is also necessary to make the ceramic molded body small and thin. When the ceramic molded body is reduced in size, the inner diameter of the through hole formed in the ceramic molded body is also reduced, so that the outer diameter of the rod needs to be reduced in accordance with the through hole. There is also a demand to set the inner diameter of the through hole to 3 mm or less, for example. For this reason, an outer diameter becomes thin compared with the length, and it becomes easier to deform | transform a stick | rod.

  By exchanging the rod with a new one before creep occurs, it is possible to suppress the occurrence of defective firing and variation in characteristics. However, if the rods are frequently replaced, the manufacturing cost increases. If the amount of creep deformation of the rod can be reduced and the life of the rod can be extended, even if a ceramic molded body with a through hole with a small inner diameter is fired, firing defects and characteristic variations are suppressed, and yield is reduced. It can be improved and the manufacturing cost can be reduced.

  Based on such research results, the ceramic firing sheath according to the present invention is connected to the frame part forming the opening for arranging the ceramic molded body and the mutually opposing parts in the frame part, and the part to divide the opening And a connecting portion extending between the two.

  In the ceramic firing sheath according to the present invention, the connecting portion extends between the opposing portions of the frame portion so as to divide the opening. The length of the rod used for firing the ceramic molded body is the length that can be bridged between the connecting portion and the portion of the frame portion facing the connecting portion, that is, between the connecting portion and the portion of the frame portion facing the connecting portion. The length may correspond to the distance between the two, and may be shorter than the length of a rod conventionally used (the length corresponding to the distance between the portions of the frame portion facing the connecting portion). Therefore, even when the outer diameter of the rod is small, the rod length can be shortened, so that the amount of creep deformation of the rod is reduced, and the life of the rod can be extended. As a result, the rod replacement frequency can be reduced and the manufacturing cost can be reduced. Moreover, since the amount of creep deformation is small, it is possible to suppress firing in a state where adjacent ceramic molded bodies are in contact with each other. As a result, even when a ceramic molded body having a through hole with a small inner diameter is fired, the occurrence of defective firing and variation in characteristics is suppressed, and the yield can be improved.

  Moreover, it is preferable that a connection part is removable from a frame part. When the connecting portion is removed from the frame portion, it is possible to support a rod having a length corresponding to the interval between the portions facing the connecting portion in the frame portion. Both a rod having a length corresponding to the interval between the portions facing the connecting portion in the frame portion, and a rod having a length corresponding to the interval between the connecting portion and the portion facing the connecting portion in the frame portion It is possible to realize a sheath that can cope with the above.

  Moreover, it is preferable that the convex part for positioning a connection part is formed in the part to which a connection part is connected. In this case, the convex portion prevents the connecting portion from being displaced, and the rod can be prevented from being detached from the frame portion or the connecting portion.

  Moreover, it is preferable that a connection part has a 1st part mounted in each part to which a connection part is connected, and a 2nd part located in opening. In this case, a connecting part that can be easily attached to and detached from the frame part can be realized.

  Moreover, the convex part is formed in the 2nd part of a connection part, and it is preferable that the top of the said convex part is located in the same height as a 1st part. In this case, the mechanical strength of the connecting portion can be increased.

  Moreover, it is preferable that the recessed part is formed in at least one of the part facing the connection part in a frame part, and a connection part. In this case, the rod can be positioned by the recess.

  The frame portion includes a first upper surface and a second upper surface located at a position lower than the first upper surface and facing the connecting portion in the frame portion, and the connecting portion includes the frame portion. It is preferable to include a first upper surface located at the same height as the first upper surface and a second upper surface located at the same height as the second upper surface of the frame portion. In this case, when the ceramic molded bodies are fired in the stacked sheaths, a frame of a sheath in which a gas constituting the firing atmosphere (hereinafter referred to as an atmosphere gas) is positioned on the upper side of two adjacent sheaths. Through the gap formed between the lower surface of the portion and the second upper surface of the pod frame portion located on the lower side, the air flows well into the stacked pods. Moreover, the combustion component generated from the ceramic molded body is smoothly discharged from the sheath through the gap. Moreover, the atmospheric gas that has flowed into the stacked sheaths is formed between the lower surface of the frame portion of the sheath positioned on the upper side of the two adjacent sheaths and the second upper surface of the coupling portion of the sheath positioned on the lower side. It will pass through the gaps formed between them, and the connection portion will be inhibited from inhibiting the flow of atmospheric gas (including combustion components generated from the ceramic molded body) in the sheath. As a result, it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  Moreover, it is preferable that the recessed part is formed in the mutually corresponding position in the 2nd upper surface of a frame part, and the 2nd upper surface of a connection part. In this case, the rod can be positioned by the recess.

  In addition, a convex portion is formed on the second upper surface of the frame portion and the second upper surface of the connecting portion, and the top of the convex portion is preferably located at the same height as the first upper surface. . In this case, when the sheaths are stacked, the sheath positioned on the upper side can be supported by the convex portion formed on the second upper surface of the frame portion. Moreover, the mechanical strength of the said connection part can be raised by forming a convex part in the 2nd upper surface of a connection part.

  Moreover, it is preferable that the connection part is formed with an opening penetrating the connection part. In this case, when the ceramic molded body is fired in the stacked sheaths, the atmospheric gas flowing into the stacked sheaths passes through the openings. As a result, it is possible to suppress the occurrence of defective firing and variation in characteristics by suppressing the connection portion from inhibiting the flow of atmospheric gas (including combustion components generated from the ceramic molded body) in the sheath. it can.

  Moreover, it is preferable to provide multiple connection parts. In this case, it is possible to support a rod having a shorter length. As a result, the amount of creep deformation of the rod becomes extremely small, and the life of the rod can be further extended.

  The method for firing a ceramic molded body according to the present invention includes a frame part that forms an opening for arranging the ceramic molded body, and a connection that is connected to mutually opposing parts of the frame part and extends between the parts so as to divide the opening. A ceramic firing sheath provided with a portion, a rod, a ceramic molded body having a through-hole formed therein is passed through the rod, and the ceramic molded body is disposed on the rod. And a step of supporting the formed rod on a region of the frame portion facing the connecting portion and the connecting portion, and arranging the ceramic molded body in the opening, and firing the ceramic molded body arranged in the opening. It is characterized by that.

  In the method for firing a ceramic molded body according to the present invention, the rod on which the ceramic molded body is disposed is supported by the frame portion and the connecting portion. For this reason, the length of the rod used corresponds to the length that can be bridged between the connecting portion and the portion of the frame portion that faces the connecting portion, that is, the distance between the connecting portion and the portion of the frame portion that faces the connecting portion. The length may be shorter, and may be shorter than the length of a conventionally used rod (the length corresponding to the interval between the portions facing the connecting portion in the frame portion). Therefore, even when the outer diameter of the rod is small, the rod length can be shortened, so that the amount of creep deformation of the rod is reduced, and the life of the rod can be extended. As a result, the rod replacement frequency can be reduced and the manufacturing cost can be reduced. Moreover, since the amount of creep deformation is small, it is possible to suppress firing in a state where adjacent ceramic molded bodies are in contact with each other. As a result, even when a ceramic molded body having a through hole with a small inner diameter is fired, the occurrence of defective firing and variation in characteristics is suppressed, and the yield can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the sheath for ceramic baking suitable for the ceramic molded body in which the through-hole with a small internal diameter was formed, and the baking method of a ceramic molded body can be provided.

  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.

  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 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. The outer peripheral shape of the ceramic molded body 1 and the shape of the through-hole 3 are circular in plan view.

  Next, the ceramic molded body 1 is passed through the stick R and aligned in a skewered manner (stick sticking step: S103). 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. For example, when the outer diameter of the ceramic molded body 1 is 4 mm and the inner diameter is 3 mm, the outer diameter of the rod R can be set to 2 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 (see FIG. 3). 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. 4 to 11). FIG. 4 is an exploded perspective view showing the sheath. FIG. 5 is a plan view showing the frame portion, and FIG. 6 is a bottom view showing the frame portion. 7 is a cross-sectional view taken along line VII-VII in FIG. 5, and FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a plan view showing the connecting portion. 10 is a cross-sectional view taken along line XX in FIG. 9, and FIG. 11 is a cross-sectional view taken along line XI-XI in FIG.

  The sheath 10 includes a rectangular frame portion 11 and a connecting portion 13 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 frame part 11 forms an opening 15 by the four parts 11a to 11d. The connecting portion 13 is connected to two portions 11c and 11d facing each other in the frame portion 11, and extends between the two portions 11c and 11d so as to divide the opening 15. As a material of the frame part 11 and the connection part 13, a material having heat resistance (fire resistance), for example, alumina, mullite, zirconia, or the like is used.

  The frame portion 11 includes a first upper surface 30 positioned at the four corners of the frame portion 11, a second upper surface 32 positioned at portions 11 a and 11 b facing the connecting portion 13 in the frame portion 11, and a connecting portion in the frame portion 11. 13 and a third upper surface 34 located in the portions 11c and 11d to which the 13 is connected. The second upper surface 32 and the third upper surface 34 are at a position lower than the first upper surface 30. The first upper surface 30 comes into contact with the lower surface 36 of the sheath 10 located on the upper side when the sheaths 10 are stacked in multiple stages. Note that the second upper surface 32 and the third upper surface 34 are not necessarily located at the same height.

  A plurality of concave portions 40 are formed at equal intervals on the second upper surface 32 of each of the portions 11a and 11b facing the connecting portion 13. Each recess 40 is a groove having a substantially V-shaped longitudinal section. The depth of the concave portion 40 (the thickness in the vertical direction of the frame portion 11 at the position where the concave portion 40 is formed) is a state in which the rod R provided with the ceramic molded body 1 is supported by the frame portion 11 as described later. It is set so that the ceramic molded body 1 arranged on the rod R does not protrude from the sheath 10 (frame portion 11), that is, the ceramic molded body 1 falls within the range of the thickness of the sheath 10 in the vertical direction. The interval between the recesses 40 is set so that the ceramic molded bodies 1 arranged on the adjacent rods R do not come into contact with each other when the rod R on which the ceramic molded body 1 is arranged is supported by the frame portion 11. It is set larger than the outer diameter of the body 1.

  A plurality of convex portions 42 are formed at predetermined intervals on the second upper surface 32 of the portions 11 a and 11 b facing the connecting portion 13. Each convex portion 42 has a substantially trapezoidal longitudinal cross-sectional shape and is a portion formed so as to protrude from the second upper surface 32. The tops of the convex portions 42 are located at the same height as the first upper surface 30 located at the four corners of the frame portion 11. Therefore, the convex part 42 contacts the lower surface 36 of the sheath 10 positioned on the upper side when the sheaths 10 are stacked in multiple stages.

  A pair of convex portions 44 are formed at a predetermined interval on the third upper surface 34 of each of the portions 11c and 11d to which the connecting portion 13 is connected. Each convex portion 44 has a substantially trapezoidal longitudinal cross-sectional shape, and is a portion formed so as to protrude from the third upper surface 34. The interval between the convex portions 44 is set slightly larger than the width of the connecting portion 13 (the length in the extending direction of the portions 11c and 11d to which the connecting portion 13 is connected). The tops of the convex portions 44 are located at the same height as the first upper surface 30 located at the four corners of the frame portion 11. Therefore, like the convex part 42, the convex part 44 contacts the lower surface 36 of the sheath 10 positioned on the upper side when the sheaths 10 are stacked in multiple stages.

  On the first upper surface 30 of the frame portion 11, when the sheath 10 is stacked, a raised portion 46 that engages with the sheath 10 located on the upper side and prevents lateral displacement is formed. Stepped portions 48 are formed at positions corresponding to the raised portions 46 at the four corners of the lower surface 36 of the sheath 10. The step-down portion 48 is formed so as to be drawn from the lower surface 36 toward the first upper surface 30 side. When the sheath 10 is stacked, the raised portion 46 of the frame portion 11 of the sheath 10 is engaged with the stepped-down portion 48.

  The connecting portion 13 is removable from the frame portion 11, and a first portion 13 a placed on each of the portions 11 c and 11 d to which the connecting portion 13 is connected and a second portion 13 b located in the opening 15. And have. The connecting portion 13 is connected to the respective portions 11c and 11d of the frame portion 11 by placing each first portion 13a between the convex portions 44 formed on the corresponding portions 11c and 11d of the frame portion 11. Will be. Since the first portion 13a of the connecting portion 13 is sandwiched by the convex portion 44 in the direction in which the portions 11c and 11d of the frame portion 11 extend, the first portion 13a is positioned without shifting in the direction.

  The connecting portion 13 includes a first upper surface 50 located on the first portion 13a and a second upper surface 52 located on the second portion 13b. The first upper surface 50 of the first portion 13 a is located at the same height as the first upper surface 30 of the frame portion 11. Therefore, the first upper surface 50 of the first portion 13a comes into contact with the lower surface 36 of the sheath 10 positioned on the upper side when the sheath 10 is stacked in multiple stages. The second upper surface 52 of the second portion 13 b is at a position lower than the first upper surface 50. The second upper surface 52 of the second portion 13 b is located at the same height as the second upper surface 32 of the frame portion 11.

  A plurality of recesses 60 are formed at equal intervals on the second upper surface 52 of the connecting portion 13. Each recess 60 is a groove having a substantially V-shaped longitudinal section. The depth of the concave portion 60 (the thickness in the vertical direction of the connecting portion 13 at the position where the concave portion 60 is formed) is a state where the connecting portion 13 supports the rod R on which the ceramic molded body 1 is arranged, as will be described later. It is set so that the ceramic molded body 1 disposed on the rod R does not protrude from the sheath 10 (the connecting portion 13), that is, the ceramic molded body 1 falls within the range of the thickness of the sheath 10 in the vertical direction. The interval between the recesses 60 is the same as the interval between the recesses 40. When the rod R on which the ceramic molded body 1 is disposed is supported by the connecting portion 13, the ceramic molded bodies 1 disposed on the adjacent rods R are mutually connected. It is set larger than the outer diameter of the ceramic molded body 1 so as not to come into contact with the ceramic molded body 1. The recess 40 formed on the second upper surface 32 and the recess 60 formed on the second upper surface 52 are positioned at positions where the rods R are substantially parallel to each other and perpendicular to the two portions 11a and 11b. As shown, they are associated with each other.

  A plurality of convex portions 62 are formed at predetermined intervals on the second upper surface 52 of the connecting portion 13. Each convex portion 62 has a substantially trapezoidal vertical cross-sectional shape, and is a portion formed so as to protrude from the second upper surface 52. The top of the convex portion 62 is located at the same height as the first upper surface 30 of the frame portion 11 and the first upper surface 50 of the first portion 13a.

  In a state where the connecting portion 13 is connected to the frame portion 11, an inner region surrounded by the frame portion 11 (the respective portions 11 a to 11 d) and the connecting portion 13 is a formed body arrangement region 17 in which the ceramic formed body 1 is disposed. Become. Thus, the sheath 10 has a plurality (two in the present embodiment) of the molded body arrangement regions 17 (see FIG. 12). The sheath 10 supports both ends of the rod R on which the ceramic molded body 1 is disposed by the portions 11 a and 11 b of the frame portion 11 and the second portion 13 b of the connecting portion 13.

  When the sheath 10 is prepared, the plurality of rods R on which the ceramic molded body 1 is arranged are bridged over the opposite portions 11a and 11b of the frame portion 11 of the sheath 10 and the second portion 13b of the connecting portion 13 to form the rod R. Are arranged so as to be supported by the corresponding portions 11a, 11b, and 13b, respectively, and arranged substantially in parallel (see FIGS. 12 and 13). Each rod R is positioned by the recesses 40 and 60. As a result, the plurality of ceramic molded bodies 1 are packed and disposed in the opening 15 of the frame portion 11, that is, the molded body arrangement region 17 of the sheath 10. FIG. 12 is a plan view showing the sheath, and FIG. 13 is a side sectional view showing the sheath. 12 and 13 depict a state in which the sheath 10 supports the rod R on which the ceramic molded body 1 is arranged.

  As can be seen from FIGS. 12 and 13, the length of the rod R is set to a length corresponding to the distance between the connecting portion 13 and the portions 11 a and 11 b of the frame portion 11 facing the connecting portion 13. . A plurality of the rods R (two in the present embodiment) are arranged in the central axis direction of the rod R.

Next, the ceramic molded body 1 is fired in the firing furnace 20 (firing step: S107). As shown in FIG. 14, 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. 14). Flows in the opposite direction (the direction of arrow B in FIG. 14).

  In the firing step S107, as shown in FIG. 14, 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, five 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 in a state of being disposed on 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 disposed on the sheath 10 is substantially parallel to the transport direction.

  A lid 29 is placed on the uppermost sheath 10. Specifically, the lid 29 is placed on the raised portion 46 of the frame portion 11. At this time, as shown in FIG. 15A, the height difference between the first upper surface 30 and the second upper surface 32 (between the lid 29 and the portions 11 a and 11 b of the frame portion 11 ( A gap having an interval corresponding to the height of the convex portion 42 and the height of the raised portion 46 is formed. Further, between the lid 29 and the portions 11c and 11d of the frame portion 11, as shown in FIG. 15B, the height difference between the first upper surface 30 and the third upper surface 34 (convex) A gap having a distance corresponding to the height of the portion 44 and the height of the raised portion 46 is formed.

  Between the sheath 10 and the sheath 10, that is, between the portions 11a and 11b of the frame portion 11 positioned on the upper side and the portions 11a and 11b of the frame portion 11 positioned on the lower side, as shown in FIG. As shown, a gap having an interval corresponding to the difference in height between the first upper surface 30 and the second upper surface 32 (height of the convex portion 42) is formed. Also, as shown in FIG. 16B, the first portion 11c, 11d of the frame portion 11 located on the upper side and the portions 11c, 11d of the frame portion 11 located on the lower side are A gap having a distance corresponding to the height difference between the upper surface 30 and the third upper surface 34 (height of the convex portion 44) is formed.

  A gas constituting the reducing atmosphere (hereinafter referred to as reducing atmosphere gas) flows into the stacked 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 rate of the reducing atmosphere gas in this space are large. Therefore, the reducing atmosphere gas mainly flows into the sheath 10 from 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 reducing atmosphere gas that has flowed into the sheath 10 circulates in the space defined by the plurality of stacked sheaths 10. And the reducing atmosphere gas containing the combustion component which generate | occur | produced from the ceramic molded object 1 is mainly discharged | emitted from the gap | interval located in the conveyance direction rear side of the several sheaths 10 piled up.

  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. The fired ceramic molded body 1 is arranged on the rod R. However, since the pressing force does not work between the adjacent ceramic molded bodies 1 at the time of firing, the ceramic molded body 1 arranged on the rod R. Do not adhere to each other. The ring-shaped varistor porcelain may be transferred to the next step while being arranged on the rod R.

  As described above, in the present embodiment, the connecting portion 13 extends between the two portions 11 a and 11 b facing each other in the frame portion 11 so as to divide the opening 15. The length of the rod R used for firing the ceramic molded body 1 is a length that can be bridged between the connecting portion 13 and the portions 11a and 11b facing the connecting portion 13 in the frame portion 11, that is, the connecting portion 13 and the frame portion. 11 may have a length corresponding to the distance between each of the portions 11a and 11b facing the connecting portion 13 and the length of a rod conventionally used (the portions 11a and 11a facing the connecting portion 13 in the frame portion 11). 11b), which is shorter than the length corresponding to the interval between 11b. Therefore, even when the outer diameter of the rod R is small, the length of the rod R can be shortened, so that the amount of creep deformation of the rod R is reduced and the life of the rod R can be extended. As a result, the replacement frequency of the rod R can be reduced and the manufacturing cost of the varistor porcelain can be reduced.

  Moreover, since the creep deformation amount of the rod R is small, it is possible to suppress firing in a state where the adjacent ceramic molded body 1 is in contact. As a result, even when the ceramic molded body 1 in which the through-hole 3 having a small inner diameter is formed is fired, the occurrence of firing failure (appearance failure) and variation in characteristics are suppressed, and the yield can be improved.

  In the present embodiment, the connecting portion 13 can be detached from the frame portion 11. When the connecting portion 13 is removed from the frame portion 11, it is possible to support the rod R having a length corresponding to the interval between the portions 11a and 11b of the frame portion 11 facing the connecting portion 13. The rod R having a length corresponding to the interval between the portions 11 a and 11 b facing the connecting portion 13 in the frame portion 11, and the portions 11 a and 11 b facing the connecting portion 13 in the connecting portion 13 and the frame portion 11. It is possible to realize the sheath 11 that can correspond to both of the rods R having a length corresponding to the distance between them.

  Moreover, in this embodiment, the convex part 44 for positioning the connection part 13 is formed in each part 11a, 11b to which the connection part 13 is connected. The convex portion 44 prevents the connecting portion 13 from being displaced, and the rod R can be prevented from being detached from the frame portion 11 or the connecting portion 13.

  Moreover, in this embodiment, the connection part 13 has the 1st part 13a mounted in each part 11a, 11b to which the said connection part 13 is connected, the 2nd part 13b located in the opening 15, have. Thereby, the connection part 13 which can be easily attached or detached with respect to the frame part 11 is realizable.

  Moreover, in this embodiment, the convex part 62 is formed in the 2nd part 13b of the connection part 13, and the top of the said convex part 62 is located in the same height as the 1st part 13a. Yes. Thereby, the mechanical strength of the connecting portion 13 can be increased.

  Further, in the present embodiment, the frame part 11 is located at the first upper surface 30 located at the four corners of the frame part 11, and is positioned lower than the first upper surface 30 and faces the connecting part 13 in the frame part 11. 2nd upper surface 32 located in each part 11c and 11d. The connecting portion 13 includes a first upper surface 50 located at the same height as the first upper surface 30 of the frame portion 11 and a second upper surface located at the same height as the second upper surface 32 of the frame portion 11. 52. Accordingly, when the ceramic molded body 1 is fired in the stacked sheaths 10, the reducing atmosphere gas is disposed on the upper side of the two adjacent sheaths 10, and the lower surface 36 of the frame portion 11 of the sheath 10 and the lower Through the gap formed with the second upper surface 32 of the frame portion 11 of the sheath 10 positioned on the side, the sheath 10 flows well into the stacked sheath 10. Further, combustion components generated from the ceramic molded body 1 are smoothly discharged from the sheath 10 through the gap. In addition, the reducing atmosphere gas that has flowed into the stacked sheath 10 is connected to the lower surface 36 of the frame portion 11 of the sheath 10 that is located on the upper side of the two adjacent sheaths 10 and the sheath 10 that is located on the lower side. It will pass through the gap formed between the second upper surface 52 of the part 13 and the connecting part 13 inhibits the flow of reducing atmosphere gas (including combustion components generated from the ceramic molded body 1) in the sheath. Will be suppressed. As a result, it is possible to effectively suppress the occurrence of defective firing and variation in characteristics.

  In the present embodiment, the second upper surface 32 of the frame portion 11 and the second upper surface 52 of the connecting portion 13 are formed with recesses 40 and 60 at positions corresponding to each other. In this case, the rod R can be positioned by the recesses 40 and 60, and the rod R does not move and the ceramic molded body 1 does not contact when the sheath 10 is conveyed.

  Further, in the present embodiment, a convex portion 42 is formed on the second upper surface 32 of the frame portion 11, and the top of the convex portion 42 is located at the same height as the first upper surface 30. . In this case, when the sheaths 10 are stacked, the sheaths 10 (frame portions 11) located on the upper side can be supported by the convex portions 42 formed on the second upper surface 32 of the frame portions 11.

  As a modification of the present embodiment, as shown in FIGS. 17 to 19, an opening 64 that penetrates the connecting portion 13 may be formed in the connecting portion 13. In this case, when firing the ceramic molded body 1 in the stacked sheath 10, the reducing atmosphere gas that has flowed into the stacked sheath 10 passes through the opening 64. Thereby, it is possible to suppress the occurrence of defective firing and variation in characteristics by suppressing the connection portion 13 from inhibiting the flow of reducing atmosphere gas (including combustion components generated from the ceramic molded body 1) in the sheath 10. Can be suppressed.

  As another modification of the present embodiment, the sheath 10 may include a plurality of connecting portions 13 as illustrated in FIGS. 20 and 21. In this case, since the rod R having a shorter length can be supported, the amount of creep deformation of the rod R becomes extremely small, and the life of the rod R can be further extended.

  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 and the like of the ceramic molded body 1 (through hole 3) and the sheath 10 (frame portion 11 and connecting portion 13) are not limited to those described above.

  In the present embodiment, the frame portion 11 and the connecting portion 13 are separated from each other, and the connecting portion 13 can be detached from the frame portion 11. However, the present invention is not limited to this, and the connecting portion 13 is integrated with the frame portion 11. It may be formed. Further, it is not always necessary to form the convex portion 62 in the connecting portion 13.

  Moreover, in this embodiment, the recessed parts 40 and 60 are formed in the parts 11a and 11b which oppose the connection part 13 in the frame part 11, and the 2nd part 13b of the connection part 13, respectively. However, the present invention is not limited to this, and it is only necessary that a recess is formed in at least one of the portions 11 a and 11 b facing the connecting portion 13 in the frame portion 11 and the second portion 13 b of the connecting portion 13.

  Moreover, in this embodiment, although the ceramic molded body 1 arrange | positioned in the said sheath 10 is baked, conveying the sheath 10, it is not restricted to this, The ceramic molded body 1 is conveyed without conveying the sheath 10. You may bake. Further, the sheath 10 may be transported into the firing furnace 20 without being stacked. Further, 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 conveyed. However, if the inside of the firing furnace 20 is a reducing atmosphere, the reducing atmosphere is not necessarily used. There is no need to generate a gas flow. Further, the number of stages in which the sheaths 10 are 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 side view which shows the stick | rod of the state by which the some ceramic molded object was distribute | arranged. It is a disassembled perspective view which shows a sheath. It is a top view which shows a frame part. It is a bottom view which shows a frame part. It is sectional drawing along the VII-VII line in FIG. It is sectional drawing along the VIII-VIII line in FIG. It is a top view which shows a connection part. It is sectional drawing along the XX line in FIG. It is sectional drawing along the XI-XI line in FIG. It is a top view which shows a sheath. It is sectional drawing which shows a sheath. It is the schematic for demonstrating a baking furnace. (A) And (b) is a side view which shows a sheath and a lid | cover. (A) And (b) is a side view which shows several stacked | stacked sheaths. It is a top view which shows one modification of a connection part. It is sectional drawing along the XVIII-XVIII line in FIG. It is sectional drawing along the XIX-XIX line in FIG. It is a top view which shows one modification of a sheath. It is a top view which shows one modification of a sheath.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic molded object, 3 ... Through-hole, 10 ... Saddle, 11 ... Frame part, 11a, 11b ... Part facing a connection part, 11c, 11d ... Part to which a connection part is connected, 13 ... Connection part, 13a ... 1st part, 13b ... 2nd part, 15 ... opening, 17 ... molded object arrangement | positioning area | region, 20 ... firing furnace, 30 ... 1st upper surface, 32 ... 2nd upper surface, 34 ... 3rd upper surface, 36 ... lower surface, 40 ... concave portion, 42, 44 ... convex portion, 50 ... first upper surface, 52 ... second upper surface, 60 ... concave portion, 62 ... convex portion, 64 ... opening, R ... rod, S101 ... molding step, S103 ... Sticking step, S105 ... Saddle filling step, S107 ... Sintering step, S109 ... Peeling step.

Claims (8)

A pair of first portions facing each other in a first direction and a pair of second portions facing each other in a second direction orthogonal to the first direction, the pair of first portions; A rectangular frame portion forming an opening for arranging a ceramic molded body in which a through hole is formed by the pair of second portions,
A coupling portion coupled to the pair of first portions in the frame portion and extending between the portions so as to divide the opening;
The connecting part is removable from the frame part,
A pair of first portions placed on and spaced in the first direction from each other that are opposed to the pair of first portion of said frame portion,
A pair of second portions that are located within the opening and that face the pair of second portions of the frame portion and face each other in the second direction ,
Wherein the connecting portion, an opening penetrating the connecting portion by the pair of the first portion and the pair of second portions of the connecting portion of the connecting portion is formed,
The pair of second portions of the frame portion and the pair of second portions of the connecting portion are positioned and supported by rods that are passed through the through holes of the ceramic molded body and on which the ceramic molded body is disposed. A sheath for firing ceramics, wherein a recess is formed . 2. The ceramic firing according to claim 1, wherein the pair of first portions of the frame portion to which the connecting portion is connected is formed with a convex portion for positioning the connecting portion. Saya. A convex portion is formed on each of the second portions of the connecting portion,
The sheath for ceramic firing according to claim 1, wherein a top of the convex portion is positioned at the same height as the first portion of the connecting portion. The frame is
A first upper surface located at four corners;
A second upper surface located at a position lower than the first upper surface and located in the second portion of the frame portion,
The connecting portion is
A first upper surface located at each of the first portions of the connecting portion and at the same height as the first upper surface of the frame portion;
The second upper surface located at each second portion of the connecting portion and at the same height as the second upper surface of the frame portion. Saddle for ceramic firing. 5. The sheath for ceramic firing according to claim 4 , wherein recesses are formed at positions corresponding to each other on the second upper surface of the frame portion and the second upper surface of the connecting portion. Convex portions are formed on the second upper surface of the frame portion and the second upper surface of the connecting portion,
5. The ceramic firing sheath according to claim 4 , wherein a top of the convex portion is located at the same height as the first upper surface.   The sheath for ceramic firing according to claim 1, comprising a plurality of the connecting portions. A sheath for firing ceramic according to claim 1;
Prepare a stick and
Passing a ceramic molded body having a through hole formed through the rod, and arranging the ceramic molded body on the rod; and
The rod on which the ceramic molded body is disposed is supported by the second portion of the frame portion and the second portion of the connecting portion, and the ceramic molded body is disposed in the opening of the frame body. And the process of
Firing the ceramic molded body disposed in the opening of the frame, and firing the ceramic molded body.

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