JP5419664B2 - Long hollow ceramic member - Google Patents

Description

  The present invention relates to a large, long, hollow ceramic member used in a liquid crystal or semiconductor manufacturing apparatus or a precision measuring apparatus.

  In recent years, with the increase in size of liquid crystal or semiconductor manufacturing apparatuses or precision measuring apparatuses, structural parts made of ceramics used in these apparatuses, such as support members for substrates, have also been increased in size. A long ceramic member having a length exceeding 1 m may be used for the enlarged support member. Since such a large long ceramic member is heavy, it is difficult to handle, and the apparatus assembled with the long ceramic member is also difficult to convey and move due to its weight. The weight is reduced by forming a hollow portion that is continuous in the longitudinal direction at the center of the tube to form a hollow shape.

  Conventionally, an extrusion molding method has been used as a molding method for obtaining a long hollow ceramic member exceeding 1 m. The extrusion molding method is a method of continuously molding a molded body having a specific cross-sectional shape by extruding a clay, which is a molding raw material prepared in a clay shape, from a mold having a specific exit shape, This is a molding method capable of obtaining a rod-shaped or cylindrical long molded body. A long ceramic sintered body is obtained by drying and then firing the formed body obtained by this forming method. And if this long ceramic sintered compact is ground, a long ceramic member can be obtained.

  In such a long ceramic member, it is necessary not to cause cracks or bends during drying shrinkage in the drying process.

  In addition, in a long hollow ceramic member formed with a hollow portion for weight reduction, air in the hollow portion is retained in the drying step, so the vicinity of the hollow portion side of the formed body (the inner surface side of the formed body) ) Would be insufficiently dried, and there was a problem that cracks occurred in the vicinity of the surface on the hollow portion side.

  Here, FIG. 6 is a partially broken perspective view showing an example of a conventional long hollow ceramic member. The long hollow ceramic member 5 shown in FIG. 6 is a long hollow ceramic member 5 having a square outer periphery 61 of a cross section perpendicular to the longitudinal direction and a square hollow portion 62 penetrating in the longitudinal direction. In FIG. 6, the four corners 63 of the long hollow ceramic member 5 are shown hatched.

  In order to solve the problem that cracks occur in the vicinity of the surface on the hollow portion 62 side in such a long hollow ceramic member 5, Patent Document 1 discloses that the extruded body remains continuous and moves at an extrusion speed. Of the extrusion molded body so that it passes through the atmosphere of the microwave and far-infrared heater inside, and in particular, in the hollow portion, dry air is fed in parallel to the extrusion direction and the water vapor in the hollow portion is exhausted to the outside. Exhaust port is drilled on the back surface to discharge water vapor to the outside, and the water vapor stays in the hollow part during heating to eliminate adverse effects, and extrudates are extruded more quickly to prevent deformation and cracking. A method is disclosed in which a molded body is dried more quickly on the same level of a straight line and fired to produce a ceramic plate. According to this, a number of exhaust ports are drilled in the back surface of the hollow portion of the extrusion molded body, and dry air or the like is supplied to the core built in the die of the extrusion molding machine to remove water vapor in the hollow portion of the extrusion molded body from the outside. By drying while evacuating, a long dry body without cracks can be obtained.

JP 63-218533 A

  However, long ceramic members that have been demanded in recent years have become larger in size, and the thickness of the long hollow ceramic member that has been hollowed in order to reduce the weight has also increased. In particular, the corner portion 63 of the long hollow ceramic member 5 is a portion that is thicker in the diagonal direction than other portions. Therefore, in the manufacturing method disclosed in Patent Document 1, the corner portion 63 is not dried. It was insufficient. Therefore, when drying progresses and the molded body shrinks by drying, there is a problem that cracks are generated in the corner portion 63 that is slow to dry, for example, near the center of the corner portion 63.

  The present invention has been devised in order to solve the problems of the prior art, and an object of the present invention is to provide a long hollow ceramic that can suppress the occurrence of cracks at the corners of the long hollow ceramic member. It is to provide a member.

The long hollow ceramic member of the present invention is a long hollow ceramic member having a hollow portion penetrating in the longitudinal direction, and the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal. and it is characterized in Rukoto such by firing after longitudinally through holes dried molded body established on the part.

  Further, in the above configuration, the long hollow ceramic member of the present invention has a cross section perpendicular to the longitudinal direction, and the through hole is on the shortest straight line drawn from the apex of the outer peripheral corner portion toward the outer shape of the hollow portion. It is characterized by being.

  The long hollow ceramic member of the present invention is characterized in that, in each of the above-described configurations, the shape of the through hole in the cross section is a circular shape.

According to the long hollow ceramic member of the present invention, it is a long hollow ceramic member having a hollow portion penetrating in the longitudinal direction, and the outer periphery of the cross section perpendicular to the longitudinal direction is a polygonal shape. from Rukoto such by firing after longitudinally through holes dried molded body established on the corners, it is possible to prevent the cracks in the corners.

  Further, according to the long hollow ceramic member of the present invention, when the through hole is on the shortest straight line drawn from the apex of the outer peripheral corner portion toward the outer shape of the hollow portion in the cross section perpendicular to the longitudinal direction, The drying of the part can be promoted more efficiently.

  Further, according to the long hollow ceramic member of the present invention, when the shape of the through hole in the cross section is a circular shape, the stress concentration around the through hole is reduced compared to the case where the shape of the through hole is a non-circular shape. Can be reduced.

An example of embodiment of the elongate hollow ceramic member of this invention is shown, (a) is a partially broken perspective view, (b) is an enlarged view of the part enclosed with the broken line in (a). The other example of embodiment of the elongate hollow ceramic member of this invention is shown, (a) is a partially broken perspective view, (b) is an enlarged view of the part enclosed with the broken line in (a). . The other example of embodiment of the elongate hollow ceramic member of this invention is shown, (a) is a partially broken perspective view, (b) is an enlarged view of the part enclosed with the broken line in (a). . The other example of embodiment of the elongate hollow ceramic member of this invention is shown, (a) is a partially broken perspective view, (b) is an enlarged view of the part enclosed with the broken line in (a). . It is a schematic sectional drawing which shows the example of the extruder for obtaining the elongate hollow ceramic member of this invention. It is a partially broken perspective view which shows the example of the conventional elongate hollow ceramic member.

  Hereinafter, an example of an embodiment of a long hollow ceramic member of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of an embodiment of a long hollow ceramic member of the present invention, (a) is a partially broken perspective view, and (b) is an enlarged view of a portion surrounded by a broken line in (a). is there.

  The long hollow ceramic member 1 of the example shown in FIGS. 1A and 1B has a quadrangular outer periphery of a cross section (hereinafter simply referred to as a cross section) perpendicular to the longitudinal direction, Each of the through holes 12 extends in the longitudinal direction. The outer shape of the through hole 12 in the cross section (hereinafter simply referred to as a cross sectional shape) is circular.

  The long hollow ceramic member of the present invention is a long hollow ceramic member 1 having a hollow portion 11 penetrating in the longitudinal direction, the outer periphery of the cross section being a polygonal shape, and the longitudinal direction of the outer peripheral corner portion in the cross section. It is important that the through-holes 12 are provided.

  According to the long hollow ceramic member 1 of this example, since the through hole 12 extending in the longitudinal direction is provided at the outer peripheral corner, the solvent component such as moisture inside the molded body at the outer peripheral corner from the through hole 12. Can easily evaporate, and it is possible to suppress cracks in the outer peripheral corners during drying. In addition, since heat is easily transmitted from the through hole 12 to the entire outer peripheral corner portion even during firing, it is possible to suppress the occurrence of cracks in the outer peripheral corner portion even during the firing step. Further, unlike cracks where the location, size, and shape cannot be specified, the through-hole 12 has the advantage that the position, size, and shape of the through-hole 12 can be arbitrarily changed according to the use of the long hollow ceramic member. There is.

  Next, FIGS. 2 to 4 show other examples of the embodiment of the long hollow ceramic member of the present invention. In addition, when showing the site | part common to the example shown in FIG. 1, it shows using the same referential mark.

  FIG. 2 shows another example of the embodiment of the long hollow ceramic member of the present invention, (a) is a partially broken perspective view, and (b) is an enlarged view of a part surrounded by a broken line in (a). FIG. The long hollow ceramic member 2 of the example shown in FIG. 2 has a triangular outer periphery in cross section, and three outer peripheral corners are provided with through holes 12 extending in the longitudinal direction.

  FIG. 3 shows another example of the embodiment of the long hollow ceramic member of the present invention, (a) is a partially broken perspective view, and (b) is an enlarged view of a part surrounded by a broken line in (a). FIG. The long hollow ceramic member 3 of the example shown in FIG. 3 has a pentagonal outer periphery in cross section, and five outer peripheral corners are provided with through holes 12 extending in the longitudinal direction.

  4A and 4B show another example of the embodiment of the long hollow ceramic member of the present invention. FIG. 4A is a partially broken perspective view, and FIG. 4B is an enlarged view of a portion surrounded by a broken line in FIG. FIG. The long hollow ceramic member 4 of the example shown in FIG. 4 has a hollow portion 11 having a square outer periphery and a circular outer shape. Then, through holes 12 extending in the longitudinal direction are provided in the four outer peripheral corners of the long hollow ceramic member 4.

  As described above, the long hollow ceramic members 2 to 4 of the example shown in FIGS. 2 to 4 are the same as the long hollow ceramic members 1 of the example shown in FIG. Since the outer peripheral corners 2 to 4 are provided with through-holes 12 extending in the longitudinal direction, solvent components such as moisture in the outer peripheral corners easily evaporate from the through-holes 12 and cracks are formed in the outer peripheral corners during drying. Can be suppressed. In addition, since heat is easily transmitted from the through hole 12 to the entire outer peripheral corner portion even during firing, it is possible to suppress the occurrence of cracks in the outer peripheral corner portion even during the firing step.

  Further, in the long hollow ceramic member of the present invention, it is preferable that the through hole 12 is on the shortest straight line drawn from the apex of the outer peripheral corner portion toward the outer shape of the hollow portion 11 in the cross section. In the case of the long hollow ceramic members 1 to 4 whose outer periphery of the cross section is a polygonal shape, the thickness is thicker in the diagonal direction than other parts, so in the cross section, from the apex of the outer peripheral corner to the outer shape of the hollow part 11 The portion on the shortest straight line drawn is less likely to evaporate moisture than other portions. Therefore, if the through holes 12 are provided on this straight line, evaporation of solvent components such as moisture at the outer peripheral corners from the molded body of the long hollow ceramic members 1 to 4 can be promoted, so that cracks are generated at the outer peripheral corners. Generation | occurrence | production can be suppressed effectively.

  In the long hollow ceramic member of the present invention, the through hole 12 preferably has a circular cross-sectional shape. When the cross-sectional shape of the through-hole 12 is a polygonal shape like the long hollow ceramic members 1 to 4, if a load such as bending stress or tensile stress is applied to the long hollow ceramic members 1 to 4, Stress tends to concentrate on the corner, but when the through-hole 12 is circular, stress is not concentrated on the corner as in the polygonal shape, so the stress concentration around the through-hole 12 is relatively small.

  Further, in the long hollow ceramic member of the present invention, the diameter D (hereinafter simply referred to as the diameter D of the through hole 12) when the through hole 12 is circular is the outer diameter of the hollow portion 11 and the outer peripheral corner portion. It is preferably 1/7 or more and 1/4 or less of the shortest distance from the apex. When the cross-sectional shape of the through hole 12 is a polygon, the diameter D of the circumscribed circle of the polygonal cross-sectional shape is not less than 1/7 of the shortest distance between the outer shape of the hollow portion 11 and the vertex of the outer peripheral corner. The through hole 12 may be formed so as to be as follows. That is, in order to efficiently evaporate solvent components such as moisture at the outer peripheral corners from the molded body of the long hollow ceramic members 1 to 4, the diameter D of the through hole 12 is such that the outer shape and the outer periphery of the hollow portion 11 in the cross section. What is necessary is just 1/7 or more and 1/4 or less of the shortest distance with the vertex of a corner | angular part. If the diameter D of the through-hole 12 is in such a range, the evaporation rate of the solvent component such as moisture at the outer peripheral corner from the molded body of the long hollow ceramic members 1 to 4 is optimized, and the outer peripheral corner It is preferable because cracks can be more effectively suppressed.

  When the diameter D of the through-hole 12 provided in the outer peripheral corner portion of each of the long hollow ceramic members 1 to 4 is less than 1/7 of the shortest distance between the outer shape of the hollow portion 11 and the apex of the outer peripheral corner portion in the cross section. Since the through hole 12 has a relatively small diameter, solvent components such as moisture at the outer peripheral corners that evaporate from the through hole 12 are relatively reduced, and the effect of suppressing the occurrence of cracks tends to decrease. is there. Moreover, when the diameter D of the through-hole 12 provided in the outer peripheral corner | angular part of the long hollow ceramic members 1-4 becomes larger than 1/4 of the shortest distance of the external shape of the hollow part 11 in a cross section, and the vertex of an outer peripheral corner | angular part. Since the through-hole 12 has a relatively large diameter, the thickness between the through-hole 12 and the outer periphery is relatively thin, and the thick-walled portion is warped or twisted, or is a long hollow ceramic. There exists a tendency for the intensity | strength of a member to fall.

  In the above example, the through-hole 12 has a circular cross-sectional shape. However, the through-hole 12 may have a polygonal shape such as a triangular shape, a quadrangular shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, or an octagonal shape. It may be a shape. In addition, when the cross-sectional shape of the through-hole 12 is a polygonal shape, stress is concentrated on the corners of the through-hole 12 when an external force is generated in the long hollow ceramic members 1 to 4, so that the cross-sectional shape It is preferable to have a shape with a radius of curvature at the corner.

  Examples of the embodiment of the long hollow ceramic member of the present invention have been shown in FIGS. 1 to 4 so far, but the present invention is not limited to this and is within the scope not departing from the gist of the present invention. For example, the shape of the outer periphery in the cross section is hexagonal, heptagonal, or octagonal, so-called chamfering that takes the corners of the outer peripheral corners, or changes or improvements such as providing a plurality of hollow portions. It goes without saying that it can be done.

  Further, in the long hollow ceramic member of the present invention, the through holes provided in the outer peripheral corners do not necessarily have to be provided in all the outer peripheral corners. It is sufficient to provide more than one.

  Note that the long hollow ceramic member of the present invention has a length L shown in FIGS. The thickness t for maintaining the strength by having a hollow portion 11 is 10 mm or more and 40 mm or less.

  Moreover, as ceramics used for the long hollow ceramic member of the present invention, oxide ceramics such as alumina and zirconia, or non-oxide ceramics such as silicon nitride and silicon carbide can be applied. In particular, it has good corrosion resistance against chemicals and corrosive gases used in liquid crystal and semiconductor manufacturing processes and precision measurement, and has moderate mechanical strength and is inexpensive compared to other ceramic materials. It is preferable to use some alumina ceramics.

  Next, the manufacturing method of the elongate hollow ceramic member of this invention is demonstrated.

  FIG. 5 is a schematic cross-sectional view showing an example of an extruder for obtaining a long hollow ceramic member of the present invention.

  The screw-type extrusion molding machine 50 shown in FIG. 5 includes a pug mill portion 51 having a kneaded clay inlet 52 and a pug screw 53 for kneading the kneaded clay, and a vacuum chamber 54 for evacuating and discharging bubbles in the kneaded clay. The auger part 55 having an auger screw 56 for extruding the clay, a clay rectification part 58 provided with a plurality of rectifying springs to divide the clay, and a clay shearing part 89 are provided to make the clay into a specific shape. It is composed of an extrusion mold part 57 to be molded.

  Although not shown, one of the pug screw 53 and the auger screw 56 is connected and fixed to a bearing, and is connected to a power source. Further, a vacuum pump (not shown) for evacuating the inside of the vacuum chamber 54 is connected.

  In the manufacturing method of the long hollow ceramic member of the present invention using this extrusion molding machine 50, a ceramic material mainly composed of an alumina raw material, a binder and a solvent are mixed to form a clay, and this clay is converted into a plurality of rectifiers. A long length obtained by extrusion molding using a screw-type extruder 50 having a clay rectification portion 58 provided with a radial shape and a clay shearing portion 59 for obtaining a long hollow molded body. The hollow molded body is fired.

  Next, the detail of the manufacturing method of the elongate hollow ceramic member of this invention is demonstrated.

First, as the alumina raw material, a commercially available α-alumina raw material that is widely used as an industrial product, preferably having a purity of 99.5% or more and an average particle diameter of 1 μm to 3 μm, and a soda component (Na ₂ O) as long as 0.1 wt% or less, and soda component (Na 2 _O) less worry of polluting the firing furnace scatters upon firing still preferred. Here, the average particle diameter of the alumina raw material represents a 50% particle diameter D ₅₀ measured by a laser diffraction particle size distribution measuring method. As the sintering aid, for example, magnesia (MgO), silica (SiO ₂ ), calcia (CaO) or the like is used. The total amount of addition of the sintering aid may be 5% by mass or less so that the alumina purity of the alumina sintered body is 95% by mass or more in order to increase the rigidity of the sintered body. The alumina raw material and the sintering aid may be mixed with a solvent such as water to form a slurry and granulated into granules by a spray drying method (spray drying).

  As the binder, methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB) and the like generally used for extrusion molding clays are used. The total amount of binder added can be determined by adding 2 parts by weight or more and 8 parts by weight or less in solid content to 100 parts by weight of ceramic material containing alumina raw material and sintering aid. Good shape retention. Furthermore, as a lubricant, wax, glycerin, stearic acid or the like may be appropriately added in an amount of 1 part by mass or more and 8 parts by mass or less in terms of solid content. Further, water is preferable as the solvent, and ion-exchanged water is particularly preferable because the amount of impurities is small. Then, a ceramic material containing a sintering aid mainly containing an alumina raw material, a binder, and a solvent are weighed and mixed, and kneaded using a universal mixer, a three-roll mill, or the like. By this kneading, the surface of the ceramic material made of the alumina raw material and the sintering aid is uniformly wrapped with a binder and a solvent, and a plastic clay is obtained.

  Next, this clay is introduced from the clay inlet 52 of the extrusion molding machine 50. The introduced clay is kneaded by the rotation of the pag screw 53 and pushed out to the vacuum chamber 54 through the gap between the pag screw 53 and the inner wall of the pag mill 51. The forming raw material extruded into the vacuum chamber 54 has its internal bubbles discharged by a vacuum pump connected to the vacuum chamber 54. Thereafter, the auger screw 56 is rotated and pushed out through the gap between the auger screw 56 and the auger part 55 in the direction of the extrusion mold part 57.

  The extrusion die portion 57 is provided with a core (not shown) corresponding to the cross-sectional shape of the opening portion of the through hole 12 at a position corresponding to the outer peripheral corner portion in the long hollow ceramic member of the present invention. Yes. Through the core provided in the extrusion mold portion 57, the through hole 12 can be provided in the outer peripheral corner portion of the long hollow molded body.

  Next, the long hollow ceramic member molded body obtained by extrusion molding is put into a dryer, and dried by raising the temperature gradually from 20 ° C. near room temperature to about 80 ° C. in an air atmosphere. Thereafter, firing is performed at a firing temperature of 1550 ° C. or higher and 1650 ° C. or lower using a firing furnace in an air atmosphere according to the purity of the alumina raw material and the type of sintering aid.

  Finally, a long hollow ceramic member is obtained by finishing the obtained sintered body so as to have a desired dimension.

  By the manufacturing method as described above, the through holes 12 extending in the longitudinal direction are provided at the outer peripheral corners of the long hollow ceramic members 1 to 4. Preferably, the through holes 12 are provided in the long hollow ceramic members 1 to 4. In the drying process of the formed body of the long hollow ceramic members 1 to 4, the diameter D of the hollow portion 11 is set to 1/7 or more and 1/4 or less of the shortest distance between the outer shape of the hollow portion 11 and the apex of the outer peripheral corner portion. Solvent components such as moisture evaporate from the through-holes 12 installed in the corners, drying of the outer corners accelerates, and cracks in the outer corners due to drying shrinkage of the long hollow ceramic member formed during drying Thus, it is possible to obtain long hollow ceramic members 1 to 4 that can suppress the occurrence of the above.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

  The long hollow ceramic member of the present invention and the conventional long hollow ceramic member are manufactured using the same manufacturing process, and cracks are caused by drying shrinkage near the center of the outer peripheral corner of the long hollow ceramic member. A test was conducted to confirm whether or not Hereinafter, details and results of the test will be described.

First, the total amount of sintering aid including 96% by mass of low-soda α-alumina material having a purity of 99.8% alumina raw material and 0.05% by mass soda component (Na ₂ O), and magnesia, calcia and silica 4 parts by mass to 100 parts by mass, and 100 parts by mass of the mixed ceramic material, 4 parts by mass of methyl cellulose for binder, 2 parts by mass of polyvinyl alcohol, and 2 parts by mass of wax for lubricant And 14 parts by mass of ion-exchanged water were weighed and mixed, and further kneaded by a three-roll mill to obtain a clay for extrusion molding.

Example 1
Using the produced clay, extrusion molding is performed by an extruder 50 shown in FIG. 5, and the shape of the long hollow ceramic member 1 of the example shown in FIG. 1 is 10 mm in thickness t, 1 m in length L, The outer dimensions are 65 mm in width and 65 mm in height, and in the cross section, the hollow part 11 is formed in a quadrangular shape having sides parallel to the outer periphery of the long hollow ceramic member 1, and the through hole 12 Thirty compacts X of the example having a diameter D of 3 mm were prepared. Further, the compact X was gradually heated from 20 ° C. to near 80 ° C. and dried. In addition, 30 shaped bodies Y of Comparative Example, which are the same external dimensions as the long hollow ceramic member 1 and do not have the through holes 12, and become conventional long hollow ceramic members, were produced and dried under the same conditions. Thereafter, 20 pieces were randomly selected from the produced compacts X and Y, respectively, and the number of non-cracked parts at the outer peripheral corners was determined as the number of non-defective products. For confirmation, each of the compacts X and Y was cut at a plurality of locations perpendicular to the longitudinal direction, and the presence or absence of cracks at the outer peripheral corners was examined visually.

  As a result, the molded product X of the example of the present invention had more non-defective products than the molded product Y of the comparative example having the same dimensions.

  Further, the remaining dried molded body X and molded body Y were fired at a temperature of 1600 ° C. using a firing furnace in an air atmosphere to produce a sintered body. The number of non-defective products was confirmed by cutting a plurality of parts vertically.

  As a result, the long hollow ceramic member 1 of the example of the present invention had more non-defective products than the long hollow ceramic member of the comparative example having the same dimensions.

  Moreover, when the same test was performed on the shapes of the long hollow ceramic members 2 to 4 in the examples shown in FIGS. 2 to 4, the results were the same, and the long hollow shapes of the examples of the present invention were used for both the drying step and the firing step. The number of non-defective products was higher in the ceramic member than in the comparative example. In the shape of the long hollow ceramic member 4, the hollow portion 11 was formed so that the outer shape of the cross section was inscribed in a quadrangle parallel to each side of the outer periphery.

(Example 2)
Next, using the same manufacturing process as in Example 1, it is confirmed whether or not the position of the through hole 12 of the long hollow ceramic members 1 to 4 of the present invention has an influence on the cracks generated in the outer peripheral corners. The test was conducted.

The shape of the long hollow ceramic member 1 in the example shown in FIG. 1 is such that the thickness t is 10 mm, the length L is 1 m, the width is 65 mm, and the height is 65 mm. Is formed in a quadrangular shape having sides parallel to the outer periphery of the long hollow ceramic member 1, the diameter D of the through hole 12 is 2 mm, and hollow from the center of the cross section of the through hole 12 and the apex of the outer peripheral corner. the molded body a ₀ which is the shortest straight line midpoint equal drawn towards the outer parts 11 to produce thirty. Further, similarly, the position of the center of the through-hole 12 is the shortest straight line drawn from the vertex of the outer peripheral corner toward the outer shape of the hollow portion 11, and the direction from the midpoint of this straight line to the vertex of the outer peripheral corner The molded body A ₁ is equal to the point shifted by ₁ mm, the molded body A ₂ is equal to the point shifted by 2 mm, and the molded body A ₃ is equal to the point shifted by 1 mm in the direction of the hollow portion 11, and is equal to the point shifted by 2 mm. the molded body a ₄ were prepared 30 present, respectively. Further, the center position of the through-hole 12 is shifted from the midpoint of the shortest straight line drawn from the apex of the outer peripheral corner portion toward the outer shape of the hollow portion 11 in the horizontal direction by 1 mm toward the latest outer peripheral side. Equal molded body B ₁ , molded body B ₂ equal to the point shifted by 2 mm, molded body B ₃ equal to the point shifted by 1 mm in the opposite direction, molded body B ₄ equal to the point shifted by 2 mm, vertically Formed body C ₁ equal to the point shifted 1 mm toward the outer peripheral side, formed body C ₂ equal to the point shifted 2 mm, formed body C ₃ equal to the point shifted 1 mm in the opposite direction, shifted 2 mm the molded body C ₄ becomes equal to the point were were prepared by 30 present the same manner, respectively. Then, the molded products A _{0 to} A ₄ , B _{1 to} B ₄ and C _{1 to} C ₄ were gradually heated from 20 ° C. to near 80 ° C. and dried, and randomly selected 20 pieces respectively. The number of non-defective products was confirmed. For confirmation, each molded body A _{0 to} A ₄ , B _{1 to} B ₄ and C _{1 to} C ₄ was cut at a plurality of positions perpendicular to the longitudinal direction, and the presence or absence of cracks at the outer peripheral corners was visually examined.

As a result, the number of non-defective products of the molded products A _{0 to} A ₄ was larger than other molded products. In particular, good number of the compact A ₀ was the most common. Further, in the compacts B _{1 to} B ₄ and C _{1 to} C ₄ , B ₁ , B ₃ , C ₁ and C ₃ had a relatively large number of non-defective products.

Further, the remaining dried formed bodies A _{0 to} A ₄ , B _{1 to} B ₄ and C _{1 to} C ₄ were fired at a temperature of 1600 ° C. using a firing furnace in an air atmosphere to produce a sintered body. and moldings _{a 0 ~A 4, B 1 ~B} 4 and _C 1 -C ₄ similarly to a plurality of locations along a surface perpendicular to a longitudinal direction, to confirm the good number.

As a result, the number of non-defective products of the compacts A _{0 to} A ₄ was larger than that of other sintered bodies.

  Moreover, when the same test was performed on the shapes of the long hollow ceramic members 2 to 4 in the examples shown in FIGS. 2 to 4, the results were the same, and the through holes 12 were from the top of the outer peripheral corners in both the drying step and the firing step. The long hollow ceramic members 2 to 4 on the shortest straight line drawn toward the outer shape of the hollow portion 11 had a higher number of non-defective products than the other examples. In the shape of the long hollow ceramic member 4, the hollow portion 11 was formed so that the outer shape of the cross section was inscribed in a quadrangle parallel to each side of the outer periphery.

  From the above results, the through-hole 12 is preferably on the shortest straight line drawn from the apex of the outer peripheral corner to the outer shape of the hollow portion 11 in the cross section, and further, the center of the through-hole 12 and the outer peripheral corner It has been found that the closer to the midpoint of the shortest straight line drawn from the apex toward the outer shape of the hollow portion 11, the more effectively the occurrence of cracks in the outer peripheral corner can be suppressed.

(Example 3)
Next, using the same manufacturing process as in Example 1, the size of the through holes 12 of the long hollow ceramic members 1 to 4 of the present invention affects the cracks generated at the corners of the outer peripheral corners. A test to confirm whether or not

By the same manufacturing process as in Example 1, the shape of the long hollow ceramic members 1 to 4 shown in FIGS. 1 to 4 is 10 mm, the thickness t is 10 mm, the external dimension is 1 m in length L, the width is 65 mm, and high. Is an outer dimension of 65 mm, and in its cross section, the hollow portion 11 is formed in a quadrangular shape having an outer shape parallel to the outer periphery of the long hollow ceramic member 1 (the shape of the long hollow ceramic member 4). The hollow portion 11 is formed so that the outer shape of the cross section is inscribed in a quadrangle parallel to each side of the outer periphery), and the diameter D of the through-hole 12 is such that the outer shape of the hollow portion 11 and the apex of the outer peripheral corner portion in the cross section are Nos. 1/8, 1/7, 1/6, 1/5, 1/4, and 1/3 of the shortest distance of No. 20 pieces of 1 to 6 were produced. In addition, compact No. In all of Nos. 1 to 6, the through hole 12 was provided so that the center in the cross section of the through hole 12 and the midpoint of the shortest straight line drawn from the apex of the outer peripheral corner toward the outer shape of the hollow portion 11 were equal. The value of the diameter D of the through hole 12 was obtained by rounding down the third decimal place. Then, a molded body No. 1 which is a conventional long hollow ceramic member having the same external dimensions and no through-hole 12 is used. 20 pieces of 7 were produced. Then, the formed compact No. 1 to 7 were gradually heated from 20 ° C. to near 80 ° C. and dried, and the number of good products was confirmed. The results are shown in Table 1. In addition, although there was no crack in the corner part, the thing in which the thickness part between the through-hole 12 and the outer periphery generate | occur | produced the curvature and the twist was set as the inferior goods. G in Table 1 indicates the relationship between the diameter D (unit: mm) of the through hole 12 and the shortest distance (unit: mm) between the outer shape of the hollow portion and the apex of the outer peripheral corner in the cross section. It is a value when expressed by equation (1).
Diameter D = the shortest distance between the outer shape of the hollow portion and the apex of the outer peripheral corner in the cross section × G (1)

  As can be seen from the results shown in Table 1, compact No. Nos. 1 to 6 are molded bodies having no through holes 12. Compared to 7, there were more non-defective products.

  In addition, the molded product No. In the case where the diameter D of the through-hole 12 is 2/7 or less, and is 20 or less 1/4 of the shortest distance between the outer shape of the hollow portion 11 and the apex of the outer peripheral corner in the cross section, 20 pieces were produced. Molded body No. Of the 2-5, 90% or more of the molded products were non-defective products. In the molded body provided with the through holes 12 having a diameter D outside this range, the number of non-defective products was not 90% or more of the produced 20 molded bodies.

  As a result, in the long hollow ceramic members 1 to 4 of the present invention, the diameter D of the through hole 12 is 1/7 or more of the shortest distance between the outer shape of the hollow portion 11 and the apex of the outer peripheral corner in the cross section. It has been found that the following is preferable.

Example 4
Next, for the long hollow ceramic members 1 to 4 of the present invention, samples in which the cross-sectional shapes of the through holes 12 provided in the outer peripheral corners are variously changed are manufactured by the same manufacturing method as in Example 1, and the effect is confirmed. A test was conducted.

  By the same manufacturing process as in Example 1, the shape of the long hollow ceramic member 1 of the example shown in FIG. 1 is obtained with the outer dimensions of the thickness t of 10 mm, the length L of 1 m, the width of 65 mm, and the height of 65 mm. In the cross section, the hollow portion 11 is formed in a quadrangular shape having a side parallel to the outer periphery of the long hollow ceramic member 1, and the diameter D of the through hole 12 is equal to the outer shape of the hollow portion 11 in the cross section. Five molded bodies O that were ¼ of the shortest distance from the apex of the outer peripheral corner were prepared. In the molded body O, the through hole 12 is provided so that the center of the cross section of the through hole 12 is equal to the midpoint of the shortest straight line drawn from the apex of the outer peripheral corner toward the outer shape of the hollow portion 11. . Then, five molded products P having the same shape as the molded product O and having the cross-sectional shape of the through hole 12 changed to a square shape were produced. The through hole 12 of the molded body P was formed so that the diameter D of the circumscribed circle of the outer shape in the cross section was ¼ of the shortest distance between the outer shape of the hollow portion 11 and the apex of the outer peripheral corner portion. In addition, five compacts Q having the same shape as the compact O and having curves with a curvature radius of 1.5 mm at four corners of the cross-sectional shape of the through-hole 12 were produced. Then, the formed compacts P to Q were gradually heated from 20 ° C. to near 80 ° C. and dried, and fired at a temperature of 1600 ° C. using a firing furnace in an air atmosphere to produce a sintered body.

  Then, using a large bending tester (BMH203 manufactured by Kinomiya Seisakusho Co., Ltd.), the produced sintered bodies P to Q are fixed so that a load perpendicular to the outer peripheral surface is applied, and three-point bending is performed. The strength (hereinafter referred to as strength) was measured 5 times, and the average value was taken as the strength of each sintered body.

  As a result, the sintered body of the molded body O provided with the through-holes 12 having a circular cross-sectional shape is compared with the strength of the sintered bodies of the molded bodies P and Q provided with the through-holes 12 having a square cross-sectional shape. It was big. In addition, the sintered body of the molded body Q provided with the quadrangular through-holes 12 whose cross-sectional shape has a radius of curvature at the corners has the quadrangular through-holes 12 whose cross-sectional shape does not have the radius of curvature at the corners. It was larger than the strength of the sintered body of the provided compact P.

  Moreover, when the same test was performed on the shapes of the long hollow ceramic members 2 to 4 in the examples shown in FIGS. 2 to 4, the result was the same, and the sintered body provided with a through-hole having a circular cross-sectional shape was the most. Next, a sintered body provided with a rectangular through-hole 12 having a high strength and a cross-sectional shape with a radius of curvature at the corner, and a rectangular through-hole 12 with a cross-sectional shape without a radius of curvature at the corner. The strength was higher in the order of the provided sintered bodies. In the shape of the long hollow ceramic member 4, the hollow portion 11 was formed so that the outer shape of the cross section was inscribed in a quadrangle parallel to each side of the outer periphery.

  From the above results, it was found that in the long hollow ceramic member of the present invention, the shape of the through hole in the cross section is preferably circular.

1-5: Long hollow ceramic member
11: Hollow part
12: Through hole D: Diameter of the through hole L: Length of the long hollow ceramic member t: Wall thickness

Claims (3)

A long hollow ceramic member having a hollow portion penetrating in a longitudinal direction, wherein an outer periphery of a cross section perpendicular to the longitudinal direction is polygonal, and in the cross section, a through hole is provided in the longitudinal direction at an outer peripheral corner portion long hollow ceramic member, characterized in Rukoto such by firing after the molded body is dried.   2. The long hollow ceramic according to claim 1, wherein in the cross section perpendicular to the longitudinal direction, the through hole is on a shortest straight line drawn from the apex of the outer peripheral corner portion toward the outer shape of the hollow portion. Element.   The long hollow ceramic member according to claim 1 or 2, wherein the shape of the through hole in the cross section is a circular shape.

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