JP2005272152A - Method for producing bottomed tubular ceramic body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a bottomed tubular ceramic body 1 in high productivity and yield by which the occurrence of cracks caused by biting at the time of firing and insufficient dewaxing of a binder is prevented and also the occurrence of falling-down or reaction is prevented. <P>SOLUTION: In a method for firing a bottomed tubular ceramic formed body 1a having a curved bottom face 8 while allowing an opening face 2 to direct downward, the opening face 2 of the formed body 1a is mounted on a supporting table 3 having at least one communication hole 3a communicating with the outside, and a firing tool 9 constituted of a column support part 4 having the same coefficient of thermal expansion as that of the formed body 1a, and a bottom supporting part 5 being provided at the tip end of the column support part 4 and having a curved face for supporting the bottom face 8 of the formed body 1a is arranged in a vertically standing condition in the tube of the formed body 1a. At this time, the firing tool 9 is arranged so that it is apart from the formed body 1a within a low temperature region of the firing temperature, and the bottom supporting part 5 is brought into contact with the bottom face 8 of the formed body 1a when the shrinkage of the formed body 1a is completed at a high temperature region. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for firing a bottomed tubular ceramic body using a firing jig.

  A bottomed tubular ceramic body 1 having a bottom at one end and an opening at the other end as shown in a perspective view of FIG. 6A and a cross-sectional view of FIG. It is used as a protective tube.

  Since such a bottomed tubular ceramic body 1 is long and thin, and easily deforms, a method of firing using a firing jig has been used when firing the molded body. .

  For example, as shown in FIG. 4A, a support base 33 is placed on a base 6, the opening surface 2 of the molded body 1a is set to the support base 33 side, and a sintered body 1b that becomes a bottomed tubular ceramic body 1 inside thereof. A tubular core material 34 having a larger coefficient of thermal expansion is disposed, and the molded body 1a is placed with a gap so as to cover the core material 34, and then fired.

  At this time, at the stage where the molded body 1a is arranged before firing, the support portion 35 of the core member 34 located on the bottom surface side of the molded body 1a does not contact the molded body 1a, and is contracted by the molded body 1a in the firing stage. As shown in FIG. 4B, it abuts on the support portion 35 of the core member 34. When the sintering proceeds due to the shrinkage of the molded body 1a, the opening surface 2 is lifted away from the support base 33, and the sintered body 1b is supported by the support portion 35 of the core material 34 in the high temperature region. At this stage, the core material 34 having a large thermal expansion coefficient shrinks, and a gap 37 is formed between the bottomed tubular ceramic body 1 and the sintered body 1b, and the sintered body 1b is removed from the core material 34 to remove the sintered body 1b. It has been proposed to obtain (see Patent Document 1).

  Further, as shown in FIG. 5 (a), with the opening surface 2 of the molded body 1a of the bottomed tubular ceramic body 1 as the support base 33 side, the thermal expansion coefficient is larger than that of the sintered body 1b that becomes the bottomed tubular ceramic body 1. A core material 34 made of a ceramic molded body is disposed inside, and similarly, a core material 34 made of a metal having a larger thermal expansion coefficient than the sintered body 1b to be the bottomed tubular ceramic body 1 is disposed inside, and a firing stage thereof. In step 1, the molded body 1 a contracts, and at least a part of the inner surface thereof is inscribed in the core material 34 in the high temperature range and is corrected. It has been proposed that a gap 37 is formed between the bottomed tubular ceramic body 1 and the sintered body 1b, and the sintered body 1b is obtained by removing the sintered body 1b from the core material 34 (Patent Document 2, 3).

By firing using such a firing jig, it is possible to produce a bottomed tubular ceramic body 1 having excellent dimensional accuracy by reducing warpage and roundness failure generated during firing.
JP 2000-86351 A JP 2000-86352 A JP 2000-86355 A

  However, in the firing method using the firing jig as shown in FIGS. 4 and 5, when the molded body 1 a comes into contact with the support portion 35 of the core member 34 due to the contraction of the molded body 1 a in the high temperature range. Further, since the opening surface 2 is lifted from the support base 33, there is a problem that a tensile stress acts on the bottom surface of the molded body 1a and a crack is easily generated.

  Moreover, the opening surface 2 of the molded body 1a is disposed on the smooth support base 33, and the binder as a molding aid volatilizes into a gas at the initial stage of the firing stage. This gas is converted into the interior of the molded body 1a. Therefore, there is a problem that cracks are easily generated in the molded body 1a due to insufficient degreasing of the binder.

  Furthermore, in the method of correcting and shrinking the shrinkage of the molded body 1a with the core material 34, since the biting into the core material 34 is not constant, sometimes it is strongly corrected and the biting is strong, and the gap 37 is eliminated. There is a possibility that the core material 34 may not come off from the occurrence of cracks or the molded body 1a.

  Further, when the core material 34 is made of a ceramic molded body, the strength of the core material 34 is low, so that the weight of the molded body 1a of the bottomed tubular ceramic body 1 cannot be suppressed, and collapse easily occurs. When the ceramic molded body comprising the material 34 and the molded body 1a of the bottomed tubular ceramic body 1 are in contact with each other, they are sintered while contracting each other. There was a problem.

  Furthermore, when the metal core material 34 is used, there is a problem that it reacts with the molded body 1a of the bottomed tubular ceramic body 1 in addition to the above problems. For example, when the core material 34 is made of platinum, a platinum-rhodium alloy, a heat-base heat-resistant alloy, a nickel-base heat-resistant alloy, or a cobalt-base heat-resistant alloy, it melts at a high temperature and a reaction with ceramics occurs. In general, it is known that these metals are not allowed to enter the furnace because they may elute into the firing furnace and damage the furnace.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent cracking due to biting during firing and insufficient degreasing of the binder in the manufacturing method of the bottomed tubular ceramic body 1, An object of the present invention is to provide a method for producing a bottomed tubular ceramic body with good productivity and yield by preventing the occurrence of reaction.

  In view of the above problems, the method for producing a bottomed tubular ceramic body of the present invention is a method of firing a bottomed tubular molded body having a curved bottom surface and made of ceramics with the opening surface facing downward. The opening surface of the molded body is placed on a support base having a communication hole communicating with at least one outside, and a strut portion having the same thermal expansion coefficient as the molded body and the strut are placed in a tube of the molded body. A firing jig comprising a bottom surface supporting portion having a curved surface for supporting the bottom surface of the molded body at the tip of the section is vertically erected, and the firing jig and the molded body are separated in a low temperature range of the firing temperature. When the shrinkage of the molded body is completed in the high temperature range, the bottom surface supporting portion and the bottom surface of the molded body are in contact with each other.

  In addition, the bottom surface support portion includes a curved tip surface and a tapered portion that is continuous with the tip surface and is inclined toward the outer periphery.

  Further, the supporting column and the bottom support in the firing jig have a divided structure.

  According to the method for producing a bottomed tubular ceramic body of the present invention, the opening surface of the molded body is placed on a support base having a communication hole communicating with at least one outside, and the molded body is placed in the tube of the molded body. And a supporting jig having the same thermal expansion coefficient and a bottom supporting part having a curved surface for supporting the bottom surface of the molded body at the tip of the supporting part. When the firing jig and the molded body are separated from each other in the region, and the shrinkage of the molded body is completed in the high temperature region, the bottom support portion and the bottom surface of the molded body come into contact with each other. Since the lack of degreasing can be eliminated and the firing jig can be prevented from biting into the molded body due to fluctuations in the shrinkage rate, the occurrence of cracks can be reduced and a bottomed tubular ceramic body with high dimensional accuracy can be obtained.

  In addition, since the bottom surface support portion includes a curved front end surface and a tapered portion that is continuous with the front end surface and is inclined to the outer peripheral side, the biting due to the contraction of the bottom surface support portion in contact with the molded body is further suppressed. Therefore, the generation of cracks due to biting can be more effectively prevented, and the firing jig can be easily removed.

  Furthermore, since the strut portion and the bottom support portion in the firing jig have a split structure, the height can be adjusted in accordance with the fluctuation of the shrinkage rate of the molded body that becomes the bottomed tubular ceramic body, so that the biting is performed. A bottomed tubular ceramic body with high dimensional accuracy can be obtained while suppressing deformation and preventing deformation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. A method for producing a bottomed tubular ceramic body 1 of the present invention will be described.

  First, a molding aid is added to and mixed with a powder made of a ceramic raw material such as silicon nitride, alumina, silicon carbide, etc., for example, to have a metal core bar that simulates the shape of the inner diameter of the bottomed tubular ceramic body 1 A rubber mold for wet isostatic pressing is filled, and a molding pressure of about 100 MPa is applied thereto for molding.

  As shown in the sectional view of FIG. 1A, the obtained molded body is cut into an outer shape and a length direction to form a molded body 1a of a bottomed tubular ceramic body 1 having a curved bottom surface 9. Processed.

  Here, the bottomed tubular ceramic body 1 includes, for example, a sintered body 1b having an outer diameter of φ100 to 300 mm, a length of 500 to 1500 mm, and a thickness of 10 to 20 mm, and is used as a heat-resistant component. Therefore, it is usually manufactured from a material having thermal shock resistance and high strength characteristics such as silicon nitride ceramics.

  Next, the obtained molded body 1a is fired. The production method of the present invention is characterized by firing using a firing jig 9 as shown in FIG. 1 during firing.

  First, as shown in FIG. 1A, a molded body 1a to be a bottomed tubular ceramic body 1 is placed on a support base 3 placed on a base 6 with its opening surface 2 facing downward. Put.

  As shown in FIG. 2, the support 3 is formed of a molded body having the same material as the bottomed tubular ceramic body 1, and contraction similar to that of the molded body 1 a of the bottomed tubular ceramic body 1 occurs. Thus, it is possible to obtain a sintered body 1b that maintains good roundness in the radial direction of the opening surface 2 and has little deformation.

  Further, the shape is preferably the same as that of the molded body 1a and preferably has a diameter and a surface on which the opening surface 2 can be mounted sufficiently stably, and a seat for mounting the molded body 1a more stably. It is preferable that the feeding part 10 is provided. Furthermore, it is preferable that the outer diameter of the support base 3 is about 30 to 100 mm larger than the bottomed tubular ceramic body 1, and the thickness may be about 10 to 30 mm.

  Furthermore, since it has the communicating hole 3a which consists of a groove | channel and a through-hole which communicate with at least 1 exterior, when a binder comes out as gas from the molded object 1a in a baking step, it acts as the discharge port of the gas The lack of degreasing can be eliminated, and the occurrence of cracks due to the lack of degreasing can be prevented. When the molded body 1a is circular, a plurality of the communication holes 3a are preferably formed at equal intervals, and the binder gas can be discharged to the outside sufficiently to effectively prevent the occurrence of cracks due to insufficient degreasing.

  The communication hole 3a may be manufactured as a groove that performs the same function as the hole, and it is necessary to provide at least one place, preferably two to four, and the width of the groove is about 10 to 30 mm and the depth. Is preferably about 5 to 10 mm deeper than the counterbore 10 on which the molded body 1a is placed.

  Also, a bottom support 5 having a support 4 having the same thermal expansion coefficient as that of the compact 1a and a curved surface for supporting the bottom 8 of the compact 1a at the tip of the support 4 in the tube of the compact 1a. A firing jig 9 consisting of

  The support column 4 and the bottom support 5 that form the firing jig 9 are fired by forming a ceramic sintered body having the same thermal expansion coefficient as that of the sintered body 1b to be the bottomed tubular ceramic body 1. The sintered body that has come into contact with the bottom surface support portion 5 due to the shrinkage at the time can be supported by coming into contact even during the subsequent temperature decrease, and more preferably, the same as the bottomed tubular ceramic body 1. Material.

The same thermal expansion coefficient means a material whose difference from the thermal expansion coefficient of the molded body 1a is about 1.5 × 10 ^{−6 or} less, and a material having a larger difference in thermal expansion coefficient. In this case, even after the shrinkage is completed, deformation is likely to occur during temperature reduction in the firing stage, and warping may occur. On the other hand, in a member having a small coefficient of thermal expansion, the opening surface 2 of the bottomed tubular ceramic body 1 may be lifted up and may cause cracks.

  Further, the firing jig 9 and the molded body 1a are separated from each other in the low temperature range of the firing temperature, and the shrinkage of the molded body 1a is completed in the high temperature range, whereby the bottom support portion 5 and the bottom surface 8 of the molded body 1a It is important that the abut.

  Regarding the calculation method of the size of the firing jig 9 for contacting in this way, the shrinkage rate of how much shrinkage from the size of the molded body 1a is obtained in advance by pre-baking using other members, and the shrinkage rate is This can be achieved by calculating the target size of the sintered body, and making the height of the inner diameter of the sintered body 1b of the bottomed tubular ceramic body 1 obtained thereby equal to the height of the firing jig 9. When such a firing jig 9 is placed and fired inside the bottomed tubular ceramic body 1, the heat transfer efficiency is increased. There is a tendency for shrinkage to increase. Therefore, if the height of the column part 4 and the bottom surface support part 5 is calculated from the normal shrinkage rate obtained above and manufactured, it is always necessary even if the contact amount is not taken into consideration, such as setting it to be smaller. You can touch.

  Here, the temperature change in the firing step and the shrinkage change of the molded body 1a will be described. First, the temperature rises and the compact 1a continues to shrink until it reaches the sintering temperature of the compact 1a. For example, when the molded body 1a is made of silicon nitride ceramic and the shrinkage rate is 18%, the densification by crystallization proceeds with shrinkage until the sintering temperature reaches 1700 ° C., and becomes silicon nitride ceramic. Up to about 1000 ° C. includes a degreasing step in which the molding aid volatilizes and gasifies, and thereafter the crystallization starts after exceeding 1000 ° C., and the shrinkage is particularly increased in this latter stage.

And the shrinkage | contraction of the molded object 1a is completed and it becomes the sintered compact 1b, and as shown in FIG.1 (b), the bottom face support part 5 and the bottom face 8 of the molded object 1a are like the expanded sectional view shown in FIG. Abut.

  Even in this state, it is important that the sintered body 1 b is in contact with the support 3. Next, as the temperature is lowered, the sintered body 1b and the firing jig 9 are slightly contracted, and the firing is finished in a state where they are in contact with each other even at room temperature.

  Thus, the bottomed tubular shape obtained by combining the thermal expansion coefficient when the molded body 1a is fired into the sintered body 1b with the firing jig 9 including the support column part 4 and the bottom surface support part 5 is obtained. Since the length direction of the ceramic body 1 is supported at the end stage of sintering, it is possible to prevent cracks from occurring on the bottom surface 8 by avoiding contact at the contraction stage where the strength is weak. In addition, since the weak molded body 1a does not come into contact with the molded body 1a in the low temperature range, which is the initial stage of firing, the generation of cracks due to contact can be prevented. Furthermore, when the molded body 1a completes contraction in the high temperature region, when the bottom surface support portion 5 and the bottom surface 8 of the molded body 1a come into contact with each other, the sintering is almost completed, so the strength is increased. Therefore, cracks do not occur even if they come into contact.

  Further, as shown in FIG. 3, the bottom surface support portion 5 includes a curved front end surface 12 that supports the bottom surface 8, and therefore it is possible to prevent concentrated stress from being generated on the bottom surface 8. The generation of cracks can be prevented. Moreover, since a part of the bottom surface 8 is supported by the front end surface 12, it is possible to prevent collapse and deformation, and since the biting with the bottom surface support portion 5 is small, the post portion 4 and the bottom surface support portion 5 after firing. Can be easily extracted. The front end surface 12 of the bottom surface support portion 5 is preferably a curved surface that matches the curved surface inside the bottom surface 8 of the molded body 1a after firing, and may be slightly smaller than this.

  Further, as shown in FIG. 3, the bottom surface support portion 5 preferably includes a curved tip surface 12 and a tapered portion 11 that is continuous with the tip surface 12 and is inclined toward the outer periphery.

  As a result, it is possible to further suppress the biting due to the contraction of the bottom surface support portion 5 that comes into contact with the molded body 1a, and to prevent the occurrence of cracks due to the biting and the firing jig 9 from being detached from the bottomed tubular ceramic body 1. .

  As shown in FIG. 3, the bottom surface support portion 5 has a curved surface with a radius close to the inner diameter of the molded body 1a so as to abut on the bottom surface 8 of the molded body 1a. It has the taper part 11 continuously. For example, since the inner diameter of the bottomed tubular ceramic body 1 after firing is φ135 mm, the radius of curvature of the bottom surface supporting portion 5 is 67.5 mm, and the taper is 10 ° or more on the side surface continuous to the curved distal end surface 12. By providing the portion 11, it is possible to prevent cracks due to stress from occurring on the bottom surface 8 of the molded body 1 a due to surface contact, and to easily remove the bottom surface support portion 5 when biting occurs due to contraction. .

  The tapered portion 11 preferably has an inclination angle of 5 ° to 15 °. If the angle is less than 5 °, the inner peripheral surface of the molded body 1a may enter the inner peripheral side from the bottom support portion 5 and may not come out. In addition, when the angle exceeds 15 °, the area of the curved tip surface 12 becomes small, and when the taper portion 11 comes into contact with the sintered body 1b when contracted from the molded body 1a to the sintered body 1b, the bottomed tubular ceramic body 1 The bottom 8 is not a beautiful curved surface.

Further, if the surface is coated with boron nitride or the like so that the bottom surface support portion 5 does not react or weld with the molded body 1a, the bottom surface support portion 5 can be easily removed.

  Moreover, it is preferable to make the support | pillar part 4 and the bottom face support part 5 in the said baking jig 9 into a division | segmentation structure.

  Accordingly, the height can be adjusted in accordance with the fluctuation of the shrinkage rate of the molded body 1a, so that the biting can be suppressed and the deformation of the bottomed tubular ceramic body 1 can be prevented.

  Further, by making the outer diameter of the support column part 4 smaller than the outer diameter of the bottom support part 5, there is sufficient space 7 between the bottomed tubular ceramic body 1 and the support column part 4, and the bottom surface is not bitten. Even if the support portion 5 is bitten by dividing the support portion 5 into a support structure, it can be easily taken out later. This is because the ceramics do not shrink inside the outer diameter of the bottom surface support 5. For example, the outer diameter of the support column 4 is 110 mm, and the molded body 1 is engaged with the contracted support column 4 by shrinking the bottomed tubular ceramic body 1 to be smaller than 135 mm, which is the outer diameter after sintering. Therefore, it is possible to easily remove the support column 4 after firing.

Similarly, the column portion 4 can be coated with boron nitride or the like on its surface to suppress reaction with the molded body 1.

  In addition, by preparing in advance a structure in which the support column 4 is divided in the length direction and formed from a number of materials having different thermal expansion coefficients, for example, the support column 4 is combined with a low thermal expansion material such as cordierite and alumina. By adjusting the mutual length, it is possible to match the thermal expansion coefficient of silicon nitride or silicon carbide, so that the molded body 1a of various materials can be fired.

  Further, the firing method using the firing jig 9 can be used effectively when firing the molded body 1a containing 10% or more of the binder, has a large shrinkage rate during firing, and generates a large amount of gas. Even so, since the support 3 is provided with the communication hole 3a, this gas can be discharged to the outside.

  Next, examples of the present invention will be described.

  Here, an experiment was conducted by the following method.

  First, the bottomed tubular ceramic body is made of silicon nitride ceramic, the length is 1337 mm, the outer diameter of the cylindrical portion is 180 mm, the inner diameter is 157 mm, the outer diameter of the opening surface is 205 mm, the wall thickness is 12 mm, and the curvature inside the bottom surface A molded body having a radius of 78.5 mm was prepared.

  Since the shrinkage ratio obtained by the preforming was 17.6%, the dimensions of the sintered body were obtained from this, and the length was 1102 mm, the outer diameter of the cylindrical portion was 148.3 mm, the inner diameter was 129.3 mm, the opening surface The bottomed tubular ceramic body has an outer diameter of 168.9 mm and a thickness of 10 mm.

  Here, the height of the inner surface portion of the sintered body that becomes the bottomed tubular ceramic body is 1092 mm, which is a dimension obtained by subtracting the thickness from the length.

  As comparative examples, samples 1 to 4 were evaluated for molded bodies of the conventional firing method. Sample 1 of the comparative example was manufactured by a firing method as shown in FIG. 5 using a molded body made of silicon nitride ceramics of the same material as a core material. The length of the core material was 1300 mm, the diameter was 156.0 mm, the inner diameter of the molded body was 1.0 mm smaller, and the radius of curvature inside the bottom surface was 78.0 mm.

  Sample 2 which is a comparative example is a sintered body of alumina ceramic having a large thermal expansion coefficient as a core material by the same firing method, and sample 3 of the comparative example is sintered of cordierite ceramic having a small thermal expansion coefficient. The sample 4 of the comparative example was made of a sintered body of silicon nitride ceramic, and the samples 2 to 4 were made of a bottomed tubular ceramic body with a core material length of 1200 mm and an outer diameter of 129.9 mm. It was made 0.5% larger than the diameter after firing, and the radius of curvature inside the bottom surface was 65.0 mm.

  Each support was coated with boron nitride on its surface.

  As another comparative example, Sample 5 is the same firing method as the sample shown in the present invention as shown in FIG. 1 below, but the support base is not provided with a communication hole.

  Further, as examples of the present invention, Samples 6 to 12 were fired by the firing method as shown in FIG.

  First, a molded body having a length of 1337 mm, an outer diameter of a cylindrical portion of 180 mm, an inner diameter of 157 mm, an outer diameter of an opening surface of 205 mm, and a thickness of 12 mm was prepared using silicon nitride ceramics as a molded body.

  Then, as shown in FIG. 1, the opening surface of the molded body is placed on a support base having an outer diameter of 250 mm having four communication holes, a thickness of 20 mm, a countersink portion diameter of 206 mm, and a depth of 10 mm. And a firing jig comprising a bottom surface support portion having a curved surface having a radius of curvature as shown in Table 1 for supporting the bottom surface of the molded body, as shown in Table 1, in the tube of the molded body. Standing vertically.

  The length of the firing jig was 1102 mm by adding the length of 1092 mm of the inner surface of the sintered body of the bottomed tubular ceramic body and the thickness of the countersink portion of the support base to 10 mm.

  And various baking methods were evaluated. The evaluation items were roundness of the bottomed tubular ceramic body, warpage in the longitudinal direction, occurrence of cracks, and the degree of omission of the firing jig. Roundness is 45 ° near the open surface of the outer shape, at the center and at the top. The amount of deformation was determined by measuring each of the four locations for each, and the warpage was measured by measuring the dimension of the portion having the largest gap with the surface plate by slowly rotating the diameter portion on the surface plate. In addition, the crack was visually checked by color-checking the sintered body, and the firing jig was evaluated with respect to the degree of removal by applying vibration to those which were difficult to come off.

  As a comprehensive judgment, if the crack is generated and the firing jig cannot be removed, it is ×, the roundness is 5 mm or more, the warpage is 4 mm or more, Δ, the roundness is less than 5 mm, and the warpage is less than 4 mm. Was marked as ○.

The evaluation results are shown in Table 1.

  From the results shown in Table 1, in Sample 1 which is a conventional firing method, the core material and the molded body partially contacted each other at the shrinkage stage by firing, and sticking occurred, and this core material could not be pulled out. In Samples 2 to 4, the core material cannot be removed except for the alumina ceramic having a large thermal expansion coefficient of Sample 2, and the bottom portion of the core and its cylindrical side surface are cracked firmly by correction. It was.

  Moreover, although it is the baking method of FIG. 1, the sample 5 which did not provide the communicating hole in the support stand had large baking deformation, and the crack considered to be a degreasing defect has been confirmed.

  Moreover, all the samples 6-12 which are the Examples of this invention did not generate | occur | produce a crack in a sintered compact, and it was possible to remove a baking jig.

  Samples 9 and 10 were manufactured such that the outer diameter of the bottom support portion was 2 mm smaller than the size after firing the bottomed tubular ceramic body, and 5 ° to 10 ° on the curved outer peripheral portion. The taper was provided in a good state with little deformation and warping of the diameter. Samples 11 and 12 have a bottom support portion whose outer diameter matches the size after firing the bottomed tubular ceramic body, and has a taper of 15 ° and 20 ° on the curved outer peripheral portion thereof, The deformation of the diameter was small up to 15 °, but the deformation of the diameter increased slightly at 20 °. Further, Samples 10 to 12 were manufactured by dividing the column portion and the bottom surface support portion. In particular, Sample 11 had the best results with both roundness and warpage being small.

It is sectional drawing which shows the manufacturing method of the bottomed tubular ceramic body of this invention, (a) is sectional drawing which shows the state which set the baking jig, (b) is sectional drawing after baking. It is a perspective view which shows the support stand used for the manufacturing method of the bottomed tubular ceramic body of this invention. It is an expanded sectional view of the bottom face part just after sintering of the bottomed tubular ceramic body of the present invention. It is sectional drawing which shows the manufacturing method of the conventional bottomed tubular ceramic body, (a) is sectional drawing which shows the state which set the baking jig, (b) is sectional drawing after baking. It is sectional drawing which shows the manufacturing method of the conventional bottomed tubular ceramic body, (a) is sectional drawing which shows the state which set the baking jig, (b) is sectional drawing after baking. (A) is a perspective view which shows a bottomed tubular ceramic body, (b) is the sectional drawing.

Explanation of symbols

1: Bottomed tubular ceramic body 1a: Molded body 1b: Sintered body 2: Opening surface 3: Support base 3a: Communication hole 4: Strut part 5: Bottom support part 6: Base 7: Space 8: Bottom face 9: Firing Jig 10: Countersink part 11: Tapered part 12: Curved tip surface 33: Support base 34: Core material 35: Support part 37: Clearance

Claims (3)

A method of firing a bottomed tubular shaped body made of ceramics having a curved bottom surface with its opening surface facing downward, wherein the opening surface of the shaped body communicates with at least one outside. A bottom surface which is placed on a support base having a hole, and has a column having the same thermal expansion coefficient as that of the molded body and a curved surface for supporting the bottom surface of the molded body at the tip of the column in the tube of the molded body When the firing jig comprising the support portion is erected vertically, the firing jig and the molded body are separated from each other in the low temperature range of the firing temperature, and the shrinkage of the molded body is completed in the high temperature range, A method for producing a bottomed tubular ceramic body, characterized in that the bottom surface supporting portion and the bottom surface of the molded body abut. 2. The method for producing a bottomed tubular ceramic body according to claim 1, wherein the bottom surface support portion includes a curved tip surface and a tapered portion that is continuous with the tip surface and is inclined toward the outer periphery. The method for producing a bottomed tubular ceramic body according to claim 1 or 2, wherein the supporting column and the bottom support in the firing jig have a divided structure.

Images