JP5424928B2 - 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 process, so the hollow portion side (the inner surface side of the formed body) of the formed body. Since the drying of the material becomes insufficient, there is a problem that cracks are generated in the vicinity of the surface on the hollow portion side.

  Here, FIG. 7 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. 7 is a long hollow ceramic member 5 having a square outer periphery 31 of a cross section perpendicular to the longitudinal direction and having a square hollow portion 32 penetrating in the longitudinal direction. is there. In FIG. 7, the four outer peripheral corner portions 33 of the long hollow ceramic member 5 are shown by hatching.

  In order to solve the problem that cracks occur in the vicinity of the surface on the hollow portion 32 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. Extrusion port is drilled on the back surface to discharge water vapor to the outside, and it prevents the water vapor from staying in the hollow part during heating and adversely affecting it. A method for producing a ceramic plate by drying and firing on a level line is disclosed. 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, since long ceramic members that have been demanded in recent years have become larger, and the thickness of the long hollow ceramic member that has been made hollow in order to reduce its weight has increased, Patent Document 1 The disclosed manufacturing method has a problem that when the molded body is dried, a difference occurs in the drying speed between the hollow portion side and the outer peripheral portion side, and the molded body is easily distorted. In particular, the outer peripheral corner portion 33 of the long hollow ceramic member 5 is difficult to dry because it is thicker in the diagonal direction than other portions, and is caused by the difference in drying speed between the hollow portion 32 side and the outer peripheral portion side. There was a problem that the outer peripheral corner portion 33 was cracked by the distortion of the molded body.

  The present invention has been devised in order to solve such a problem, and an object of the present invention is to provide a long hollow ceramic member capable of suppressing the occurrence of cracks at the outer peripheral corners of the long hollow ceramic member. It is to provide.

  The long hollow ceramic member of the present invention is a long hollow ceramic member having a hollow portion penetrating in the longitudinal direction, the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal, and the wall thickness is the outer corner portion. It is characterized by being thinner as it approaches.

  Further, the long hollow ceramic member of the present invention is preferably characterized in that, in the cross section, the outer side of the hollow portion facing each side of the outer periphery is arc-shaped.

In the long hollow ceramic member of the present invention, preferably, in the cross section, the maximum thickness of each of the portions corresponding to each side of the outer periphery is t ₀ and the minimum thickness is t ₁ . In this case, the value of t ₁ / t ₀ is 0.6 to 0.9.

  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, the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal, and the wall thickness is the outer periphery Since it becomes thinner as it gets closer to the corner, the drying on the hollow part side is promoted, the difference in the drying speed between the hollow part side and the outer peripheral side is reduced, and the distortion generated in the molded body is reduced. It is possible to suppress the occurrence of cracks at the corners.

  Further, according to the long hollow ceramic member of the present invention, in the cross section perpendicular to the longitudinal direction, when the side of the outer shape of the hollow portion facing each side of the outer periphery is an arc shape, the molded body is subjected to drying shrinkage. Since it can suppress that the stress which arises in a local is concentrated, it can suppress that a crack arises in an outer periphery corner | angular part.

Further, according to the long hollow ceramic member of the present invention, in the cross section perpendicular to the longitudinal direction, the maximum thickness of each of the portions corresponding to the respective sides of the outer periphery is t ₀ and the minimum thickness is t ₁ . Then, when the value of t ₁ / t ₀ is 0.6 to 0.9, drying near the center of the outer peripheral corner can be promoted more efficiently, so that the occurrence of cracks in the outer peripheral corner can be suppressed. it can.

An example of embodiment of the elongate hollow ceramic member of this invention is shown, (a) is a partially broken perspective view, (b) is sectional drawing of the elongate hollow ceramic member shown to (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 sectional drawing of the elongate hollow ceramic member shown to (a). is there. 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 sectional drawing of the elongate hollow ceramic member shown to (a). is there. (A) And (b) is sectional drawing which shows the example of the cross-sectional shape of the hollow part of the elongate hollow ceramic member of this invention, respectively. 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 sectional drawing of the elongate hollow ceramic member shown to (a). is there. 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 an 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 a cross-sectional view of the long hollow ceramic member shown in (a). It is.

The long hollow ceramic member 1 of the example shown in FIGS. 1 (a) and 1 (b) has an outer periphery of a cross section perpendicular to the longitudinal direction (hereinafter simply referred to as a cross section) having a quadrangular shape and a wall thickness at the outer corner. A hollow portion 11 in which each side of the outer shape is linearly inclined from the center is formed so as to become thinner as it gets closer. A dotted line 12 shown in FIG. 1B is an imaginary line showing the outer shape of the hollow portion 32 of the conventional long hollow ceramic member 5 having the same outer dimensions and the same wall thickness t ₀ as shown in FIG. is there.

  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, and the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal, and the wall thickness is the outer periphery. It is important that it gets thinner as it gets closer to the corner.

According to the long hollow ceramic member 1 of the present example, the outer periphery of the cross section perpendicular to the longitudinal direction is a polygonal shape, and the thickness becomes thinner as it approaches the outer peripheral corner portion. The drying is promoted to reduce the difference in drying speed between the hollow portion 11 side and the outer peripheral side, and the distortion generated in the molded body is reduced. Therefore, it is possible to suppress the occurrence of cracks in the outer peripheral corner portion. Further, since the thickness in the diagonal direction of the outer peripheral corner is thinner than the conventional long hollow ceramic member having the same thickness as the maximum thickness t ₀ of the long hollow ceramic member 1 of this example, This is more effective because the corners are easy to dry. Furthermore, in the case of a long hollow ceramic member that is simply reduced in thickness, deformation such as distortion or twist may occur in the molded body due to shrinkage during drying or firing of the molded body, In the long hollow ceramic member 1 of the present example, the outer periphery of the cross section perpendicular to the longitudinal direction is a polygonal shape, and the wall thickness becomes thinner as it approaches the outer peripheral corner. The thickness near the center is thicker than the periphery of the outer corner, and it is thought that the thickness near the center works as an adjustment part that disperses the stress generated when the molded product shrinks. It is possible to suppress deformation such as distortion and twist in the molded body due to the shrinkage.

  Next, FIG. 2 shows another example of the embodiment of the long hollow ceramic member of the present invention. In FIG. 2, the same reference numerals are used to denote the same parts as those in the example shown in FIG. 1.

  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 the long hollow ceramic member shown in (a). FIG.

The long hollow ceramic member 2 of the example shown in FIG. 2 has a hollow portion 11 formed so that the outer periphery of the cross section is a quadrangle, and the thickness is reduced stepwise as the thickness approaches the outer peripheral corner. Yes. In FIG. 2 (b) shows the width of the maximum thickness _{t 0} the width of _W 1, 2 stage the width of _W 2, 3 stage as _{W 3.} The dotted line 12 shown in FIG. 2 (b), in the example shown in FIG. 7, the thickness and outer dimensions are the same is a virtual showing the outer shape of the hollow portion 32 of a conventional long hollow ceramic member 5 of t ₀ Is a line.

As described above, in the case of the long hollow ceramic member 2 of the example shown in FIG. 2, as described for the long hollow ceramic member 1 of the example shown in FIG. Since it is a polygonal shape and the thickness is reduced as it approaches the outer peripheral corner, drying on the hollow part 11 side is promoted, and the difference in the drying speed between the hollow part 11 side and the outer peripheral side is reduced, Since distortion generated in the molded body is reduced, it is possible to suppress the occurrence of cracks in the outer peripheral corners. In addition, the diagonal thickness of the outer peripheral corner is thinner than that of the conventional long hollow ceramic member having the same thickness as the maximum thickness t ₀ of the long hollow ceramic member 1 of the present example. This is more effective because the part is easily dried. Furthermore, in the case of a long hollow ceramic member that is simply reduced in thickness, deformation such as distortion or twist may occur in the molded body due to shrinkage during drying or firing of the molded body, In the long hollow ceramic member 2 of this example, the outer periphery of the cross section perpendicular to the longitudinal direction has a polygonal shape, and the wall thickness becomes thinner as it approaches the outer peripheral corner. The thickness near the center is thicker than the periphery of the outer corner, and it is thought that the thickness near the center acts as an adjustment part that disperses the stress generated when the compact shrinks. Thus, deformation such as distortion and twisting can be suppressed in the molded body.

  Although the example of embodiment of the elongate hollow ceramic member of this invention was shown in FIG. 1 and FIG. 2, this invention is not limited to these. As long as it does not deviate from the gist of the present invention, the shape of the outer peripheral portion in the cross section can be changed as appropriate. For example, from the triangular shape, the quadrangular shape, the pentagonal shape, the hexagonal shape, the heptagonal shape, and the octagonal shape, It goes without saying that the shape of the outer peripheral portion can be changed as appropriate, or a change such as so-called chamfering can be performed to take the corner of the outer peripheral corner portion.

  Moreover, in the elongate hollow ceramic member of this invention, it is preferable in the cross section that the edge | side of the external shape of the hollow part facing each edge | side of an outer periphery is an arc shape.

  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 the long hollow ceramic member shown in (a). FIG.

The long hollow ceramic member 3 of the example shown in FIG. 3 has a rectangular outer periphery in cross section, and a side of the outer shape facing each side of the outer periphery so that the thickness becomes thinner as it approaches the outer peripheral corner. An arc-shaped hollow portion 11 is formed. The dotted line 12 shown in FIG. 3 (b), in the example shown in FIG. 7, the thickness and outer dimensions are the same is a virtual showing the outer shape of the hollow portion 32 of a conventional long hollow ceramic member 5 of t ₀ Is a line.

Thus, in the case of the long hollow ceramic member 3 of the example shown in FIG. 3, as described for the long hollow ceramic member 1 shown in FIG. 1, the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal. Since the wall thickness becomes thinner as it approaches the outer peripheral corner, drying on the hollow portion 11 side is promoted, and the difference in drying speed between the hollow portion 11 side and the outer peripheral side is reduced, and the molded body This reduces the distortion that occurs. In addition, since the outer side of the hollow portion 11 facing each side of the outer periphery has an arc shape, it is possible to suppress stress generated during drying shrinkage from concentrating on the local portion, so that cracks are generated in the outer peripheral corners. Generation | occurrence | production can further be suppressed.

  In addition, since the outer side of the hollow portion 11 facing each side of the outer periphery is an arc shape, the stress generated when the molded body is dried or contracted during firing is dispersed. It is possible to suppress deformation such as distortion and twist in the molded body due to shrinkage during firing.

  Further, in the long hollow ceramic member of the present invention, when the angle formed by each side of the outer shape of the hollow portion 11 intersects an acute angle (for example, the long hollow ceramic member 1 and the long hollow ceramic member 3). Since when a long hollow ceramic member is used as a support member, bending stress tends to concentrate around the corners formed by each side of the outer shape of the hollow portion 11 due to its own weight or the weight of the load. Preferably, both ends of each side of the outer shape are formed so as to be parallel to the opposite outer peripheral sides, or so-called chamfering is performed to take the corner of the outer shape of the hollow portion 11.

  FIG. 4 shows the shape of the outer periphery and the hollow part in the example of the embodiment of the long hollow ceramic member of the present invention whose thickness becomes thinner as it approaches the outer peripheral corner, (a) shows the hollow part It is sectional drawing of two examples in the case where it forms so that the both ends of each side of 11 external shapes may become parallel to the outer peripheral side which faces, (b) is the case where what is called chamfering which takes the corner of the external shape of a hollow part It is sectional drawing of these two examples.

FIG. 4A is a cross-sectional view showing the long hollow ceramic members A ₁ and A ₂ of an example in which the outer periphery of the cross section is a quadrangle and the thickness becomes thinner as it approaches the outer peripheral corner. is there.

In the case of the long hollow ceramic member A1 of the _first example shown in FIG. 4 (a), each outer shape has a quadrangular outer periphery and becomes thinner as the wall becomes closer to the outer peripheral corner. A hollow portion 11 whose side is linearly inclined from the center is formed. Further, both end portions of each side of the outer shape of the hollow portion 11 are formed so as to be parallel to opposite outer peripheral sides.

Further, in the case of the long hollow ceramic member A2 of the _second example shown in FIG. 4A, the outer periphery has a quadrangular shape, and the outer periphery is thinned so that the wall thickness becomes closer to the outer peripheral corner. A hollow portion 11 having an arc-shaped side opposite to each side is formed. Further, both end portions of each side of the outer shape of the hollow portion 11 are formed so as to be parallel to opposite outer peripheral sides.

In the case of the long hollow ceramic member B ₁ of the first example shown in FIG. 4B, each outer shape has a quadrangular outer periphery and becomes thinner as the wall becomes closer to the outer peripheral corner. A hollow portion 11 whose side is linearly inclined from the center is formed. Also, so-called chamfering is performed to take the corners of the outer shape of the hollow portion 11.

As described above, in the case of the long hollow ceramic members A ₁ , A ₂ , B ₁ and B _{2 in} the example shown in FIG. 4, both ends of each side of the outer shape of the hollow portion 11 are connected to opposite outer peripheral sides. Because it is formed so as to be parallel, or because it is so-called chamfering that takes the corner of the outer shape of the hollow part 11, when bending stress occurs, it concentrates around the corner formed by each side of the outer shape of the hollow part 11 Bending stress can be dispersed.

  Next, an example in which a plurality of hollow portions 11 are provided in the long hollow ceramic member of the present invention and a ceramic portion between the hollow portions 11 is used as a reinforcing portion will be described.

  FIG. 5 shows an example of an embodiment of the long hollow ceramic member of the present invention, (a) is a partially broken perspective view, and (b) is a cross section of the long hollow ceramic member shown in (a). FIG.

The long hollow ceramic member 4 of the example shown in FIGS. 5 (a) and 5 (b) is provided with two hollow portions 11 in the cross section, the outer periphery is rectangular, and the wall thickness is the outer peripheral corner portion and The hollow portion 11 is formed so as to become thinner as it becomes closer to the reinforcing portion 13 made of a ceramic portion between the two hollow portions 11. A dotted line 12 shown in FIG. 5B is an imaginary line showing the external shape of the hollow portion 32 of the conventional long hollow ceramic member 5 having the same external dimensions and the thickness t ₀ shown in FIG. is there.

  As in this example, the long hollow ceramic member is provided with a plurality of hollow portions 11 in cross section, and the ceramic portion between the hollow portion 11 and the hollow portion 11 serves as the reinforcing portion 13, and in the longitudinal direction. A long hollow ceramic member 4 with enhanced bending strength can be obtained.

Thus, the long hollow ceramic member 4 of the present example provided with the plurality of hollow portions 11 is formed with the hollow portion 11 so that the thickness thereof becomes thinner as it approaches the outer peripheral corner portion and the reinforcing portion 13. Yes. If the hollow part 11 is formed in this way, drying on the hollow part 11 side is promoted, the difference in drying speed between the hollow part 11 side and the outer peripheral side is reduced, and distortion generated in the molded body is reduced. It can suppress that a crack arises in a part. In addition, the diagonal thickness of the outer peripheral corner becomes thinner compared to the conventional long hollow ceramic member having the same thickness as the maximum thickness t ₀ of the long hollow ceramic member 4 of the present example. This is more effective because the part is easily dried. Furthermore, in the case of a long hollow ceramic member that is simply reduced in thickness, the molded body may be deformed, such as strain or twist, due to shrinkage during drying or firing of the molded body. The long hollow ceramic member 4 of the present example has a polygonal outer periphery in a cross section perpendicular to the longitudinal direction, and the hollow portion 11 has a thickness that becomes thinner as it approaches the outer peripheral corner portion and the reinforcing portion 13. Therefore, the vicinity of the center between adjacent outer peripheral corners and the vicinity of the center between the outer peripheral corner and the reinforcing portion 13 are thicker than the outer peripheral corner, and the thickness near the center is the molded body. It is considered that it acts as an adjusting portion that disperses the stress generated when the shrinkage occurs, and deformation such as distortion and twisting can be suppressed due to shrinkage during drying or firing of the shaped body.

Moreover, in the cross-section shown in FIGS. 1 to 5, the long hollow ceramic member of the present invention has a maximum thickness of each thickness of a portion corresponding to each side of the outer periphery as t ₀ and a minimum thickness as t ₁ . when _the value of t 1 / _{t 0} is preferably a 0.6 to 0.9.

The inventor promotes drying of the hollow hollow ceramic members 1 to 4, A ₁ , A ₂ , B ₁ and B ₂ on the hollow portion 11 side to dry the hollow portion 11 side and the outer peripheral side. In order to reduce the difference in speed and suppress the occurrence of cracks in the outer peripheral corners, the maximum thickness of each of the portions corresponding to the respective sides of the outer periphery in the cross section is set to t ₀ , and the minimum thickness is set to t when a _1, the value of t 1 / _{t 0} is found that may be a 0.6 to 0.9.

In the cross section, when the maximum thickness of each thickness of the portion corresponding to each side of the outer periphery is t ₀ and the minimum thickness is t ₁ , if the value of t ₁ / t ₀ is in the range of 0.6 to 0.9, By optimizing the evaporation rate of solvent components such as moisture near the hollow portion 11 from the long hollow ceramic members 1 to 4, A ₁ , A ₂ , B ₁ and B ₂ molded bodies, Can be more effectively suppressed from occurring.

In the cross sections of the long hollow ceramic members 1 to 4, A ₁ , A ₂ , B ₁ and B ₂ of each example shown in FIGS. 1 to 5, the maximum thickness of each of the portions corresponding to each side of the outer periphery When the thickness is t ₀ and the minimum thickness is t ₁ , if the value of t ₁ / t ₀ is less than 0.6, the difference between the maximum thickness t ₀ and the minimum thickness t ₁ is relative in the cross section. In the vicinity of the hollow portion 11 side, the difference in the drying speed is relatively large between the vicinity of the outer peripheral corner and the center between the adjacent outer peripheral corners, so that the molded body is likely to be distorted, and the outer periphery There exists a tendency for the effect which suppresses that a crack arises in a corner | angular part to reduce.

In addition, in the cross sections of the long hollow ceramic members 1 to 4, A ₁ , A ₂ , B _1, and B ₂ of each example shown in FIGS. 1 to 5, each thickness of the portion corresponding to each side of the outer periphery When the maximum thickness of t is t ₀ and the minimum thickness is t ₁ , if the value of t ₁ / t ₀ exceeds 0.9, the maximum thickness t of each thickness of the portion corresponding to each side of the outer periphery in the cross section The difference between ₀ and the minimum thickness t ₁ is relatively small, and the difference between the drying speeds near the hollow portion 11 side and the outer peripheral side is not relatively small. Tend to decrease.

  Further, in the long hollow ceramic member of the present invention, the molded body dries and shrinks when the thickness change between the side of the hollow portion facing each side of the contracted outer periphery is symmetrical. This is preferable because the distortion generated sometimes is small.

The long hollow ceramic member of the present invention has a length L shown in FIGS. 1 to 5 of 0.5, in order to meet the demand for long, high strength and light weight required for the enlargement of structural parts. m is greater than or equal to m, the maximum thickness t ₀ for maintaining the strength with the hollow portion 11 is 10 mm or greater and 40 mm or less, and the minimum thickness t ₁ is 6 mm or greater and 36 mm or less.

  Moreover, oxide ceramics such as alumina and zirconia, or non-oxide ceramics such as silicon nitride and silicon carbide can be applied to the ceramic used for the long hollow ceramic member of the present invention. 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 certain alumina ceramics.

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

  FIG. 6 is a schematic cross-sectional view showing an example of an extruder for obtaining a long hollow ceramic member of the present invention.

  A screw type extrusion molding machine 20 shown in FIG. 6 includes a pug mill portion 21 having a kneaded clay inlet 22 and a pug screw 23 for kneading the kneaded clay, and a vacuum chamber 24 for evacuating and discharging bubbles in the kneaded clay. The auger part 25 having an auger screw 26 for extruding the clay, a clay rectification part 28 and a clay shearing part 29 each having a plurality of rectifying springs that divide the clay are provided in a specific shape. It is composed of an extrusion mold part 27 to be molded.

  Although not shown, one of the pug screw 23 and the auger screw 26 is connected and fixed to a bearing, and is connected to a power source. Furthermore, a vacuum pump (not shown) for evacuating the inside of the vacuum chamber 24 is connected.

  In the method for producing a long hollow ceramic member of the present invention using this extrusion molding machine 20, 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. Extrusion molding was performed using a screw-type extruder 20 having a clay rectification unit 28 provided with a radial shape and a clay shearing unit 29 for obtaining a long hollow molded body, and the obtained long The hollow molded body is fired. Since the outer peripheral shape of the clay shearing portion 29 on the outlet side of the clay corresponds to the outer shape of the hollow portion 11, the hollow portion 11 can be changed by changing the outer peripheral shape of the clay shearing portion 29 on the outlet side of the clay. It is possible to arbitrarily change the shape of the outer shape.

  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) If it is 0.1% by mass or less, the soda component (N
There is little concern that a ₂ O) will scatter and contaminate the inside of the firing furnace, and it is still preferable. 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 composed of an alumina raw material, a binder, and a solvent are weighed and mixed, and then kneaded using a universal mixer or a three-roller. 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 22 of the extrusion molding machine 20. The introduced clay is kneaded by the rotation of the pag screw 23 and is pushed out to the vacuum chamber 24 through the gap between the pag screw 23 and the inner wall of the pag mill part 21. The forming raw material extruded into the vacuum chamber 24 has its internal bubbles discharged by a vacuum pump connected to the vacuum chamber 24. Thereafter, the auger screw 26 is rotated and pushed out through the gap between the auger screw 26 and the auger part 25 in the direction of the extrusion mold part 27.

  Next, the molded body of the long hollow ceramic member obtained by extrusion molding is put in a dryer, and dried by raising the temperature gradually from 20 ° C. near room temperature to near 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 hollow portion 11 is provided so that the thickness of the long hollow ceramic members 1 to 3, A ₁ , A ₂ , B ₁ and B ₂ becomes thinner as they approach the outer peripheral corner portion. In the case of the long hollow ceramic member 4, the hollow portion 11 is provided so that the wall thickness becomes thinner as it becomes closer to the reinforcing portion 13 made of the ceramic portion between the outer peripheral corner portion and the two hollow portions. Preferably, in the cross section, when the maximum thickness of each part corresponding to each side of the outer periphery is t ₀ and the minimum thickness is t ₁ , the value of t ₁ / t ₀ is 0.6 to 0.9. Thus, in the drying process of the molded body of the long hollow ceramic member, the drying on the hollow portion 11 side is promoted, the difference in the drying speed between the hollow portion 11 side and the outer peripheral side is reduced, and the distortion generated in the molded body is reduced. So suppress the occurrence of cracks at the outer corners Long hollow ceramic member _1-4, it is possible to obtain the A _1, A 2, _{B 1} and _{B 2.}

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

  Whether 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 due to drying shrinkage of the outer peripheral corners of the long hollow ceramic member. A test was conducted to confirm whether this was the case. Hereinafter, details and results of the test will be described.

Example 1
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.

Using the produced clay, extrusion molding is performed by an extruder 20 shown in FIG. 6, and the shape of the long hollow ceramic member 1 of the example shown in FIG. 1 has a maximum thickness t ₀ of 10 mm and a minimum thickness t _1. 30 compacts P of the example, which is a long hollow ceramic member of the present invention, having a length of 7 mm, a length L of 1 m, a width of 85 mm, and a height of 85 mm were produced. The hollow portion 11 was provided so that the thickness between the adjacent outer peripheral corners became the maximum thickness t _{0 of the} wall thickness, and the thickness became thinner as it became closer to the outer peripheral corner. Further, the molded body P was gradually heated from 20 ° C. to near 80 ° C. and dried. Further, the conventional long hollow ceramic shown in FIG. 7 having the same outer peripheral shape as the long hollow ceramic member 1, with a thickness of 10 mm, a length L of 1 m, a width of 85 mm, and a height of 85 mm. Thirty comparative examples of the molded body O to be the member 5 were produced and dried under the same conditions. Thereafter, 20 pieces were randomly selected from the produced compacts P and O, respectively, and the number of products with no cracks at the outer peripheral corners was determined as the number of good products, and the number of good products was confirmed. For confirmation, each molded body P and molded body O were 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 P of the example of the present invention had more non-defective products than the molded product O of the comparative example having the same dimensions.

  Further, the remaining dried formed body P and formed body O are fired at a temperature of 1600 ° C. using a firing furnace in an air atmosphere to produce a sintered body, and similarly to the formed body P and the formed body O. The number of non-defective products was confirmed by cutting a plurality of locations perpendicular to the longitudinal direction.

  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.

  A similar test was also performed on the long hollow ceramic members 2 and 3 of the example shown in FIGS.

Extrusion molding is performed by using the produced clay by the extruder 20 shown in FIG. 6, and the shape of the long hollow ceramic member 2 in the example shown in FIG. 2 has a maximum thickness t ₀ of 10 mm and a minimum thickness t _1. Are 30 mm, L is 1 m, W is 85 mm, and the height is 85 mm. 30 formed bodies Q of the present invention, which are long hollow ceramic members of the present invention, are formed. And dried under the same conditions. The center between adjacent outer peripheral corners is the maximum thickness t _0, and the hollow portion 11 is provided so that the thickness decreases stepwise by 1 mm as it approaches the outer peripheral corner. Further, the width W ₁ of the maximum thickness t ₀ is 20 mm, the second-stage width W ₂ is 30 mm, and the third-stage width W ₃ is 40 mm.

Then, using the clay prepared, subjected to extrusion molding by extrusion molding machine 20 shown in FIG. 6, in the form of elongated hollow ceramic member 3 of the embodiment shown in FIG. 3, the maximum thickness t ₀ is 10 mm, minimum thickness t ₁ is 7 mm, a length L was produced 30 present the molded body R of the embodiment comprising an elongated hollow ceramic member of the present invention to 1 m, width of 85 mm, a height was dimension of 85 mm. In addition, the side of the outer shape facing each side of the outer periphery is an arc-shaped hollow so that the center of the adjacent outer peripheral corners becomes the maximum thickness t _{0 of} the wall thickness and becomes thinner as the wall becomes closer to the outer corner. Part 11 was provided.

  Thereafter, 20 samples were randomly selected from the produced molded product Q and molded product R, and the number of products with no cracks at the outer peripheral corners was determined as the number of good products, and the number of good products was confirmed. For confirmation, each molded body Y 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 examined visually.

  As a result, the molded product Q and the molded product R of the example of the present invention had more non-defective products than the molded product O of the comparative example having the same dimensions.

  Further, the remaining dried formed body Q and formed body R are fired at a temperature of 1600 ° C. using a firing furnace in an air atmosphere to produce a sintered body, and similarly to the formed body P and the formed body O. The number of non-defective products was confirmed by cutting a plurality of locations perpendicular to the longitudinal direction.

  As a result, the long hollow ceramic member 2 of the example of the present invention had a higher number of non-defective products than the long hollow ceramic member of the comparative example having the same dimensions.

  Further, when the number of good products of the molded product P, the molded product Q, and the molded product R of the example was compared, the molded product R had the highest number of good products.

  From this result, the long hollow ceramic member of the present invention is a long hollow ceramic member having a hollow portion penetrating in the longitudinal direction, the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal, and thick It has been found that cracks can be suppressed in the outer peripheral corners if the thickness of the outer peripheral corners becomes thinner.

  In addition, the long hollow ceramic member of the present invention can further suppress the occurrence of cracks at the outer peripheral corner when the outer side of the hollow part facing each side of the outer periphery has an arc shape in the cross section. I understood.

(Example 2)
Next, a test was conducted to check whether the shape of the outer shape of the hollow portion 11 of the long hollow ceramic member affects the strength against bending stress of the long hollow ceramic member.

Using the clay prepared in Example 1, the molded body P has the same dimensions as the molded body P, and is parallel to the outer peripheral side facing the 5 mm portion from both ends of each side of the outer shape of the hollow portion 11. ₁ was produced, and five sintered bodies P1 of the example were produced under the same drying and firing conditions as in Example ₁ .

Further, the same size as molded body P, taking the corners of the outer shape of the hollow portion 11, to prepare a molded body P ₂ remembering a curved surface of radius of curvature 2 mm, dried in the same manner as in Example 1, carried out at the firing conditions Example of the sintered body P ₂ were prepared five.

Further, the same size as molded body R, and a molded body R ₁ to 5mm portion from among ends of both end portions of each side of the outer shape of the hollow portion 11 are parallel to the outer peripheral sides facing, as in Example 1 drying, the sintered body R ₁ of example were produced five in firing conditions.

Further, the same size as molded body R, taking the corners of the outer shape of the hollow portion 11, to prepare a molded body R ₂ remembering a curved surface of radius of curvature 2 mm, dried in the same manner as in Example 1, carried out at the firing conditions Example of the sintered body R ₂ to prepare five.

  Then, in the same manner as in Example 1, five sintered bodies P and five sintered bodies R as comparative examples of the molded body P and the molded body R were produced.

Next, the sintered body P ₁ , the sintered body P ₂ , the sintered body R ₁ , and the sintered body R _{2 of} the produced examples were obtained using a large bending tester (BMH203 manufactured by Kinomiya Seisakusho Co., Ltd.) The sintered body P and the sintered body R of the comparative example are fixed so that a load perpendicular to the outer peripheral surface is applied, and a three-point bending strength (hereinafter referred to as strength) is measured five times. The strength of the sintered body was used.

As a result, the sintered bodies of the sintered bodies P ₁ , P ₂ , R ₁ , and R ₂ of the example were larger than the strengths of the sintered body P and the sintered body R of the comparative example.

  From this result, the long hollow ceramic member of the present invention is formed so that both end portions of each side of the outer shape of the hollow portion 11 are parallel to the opposite outer peripheral sides, or the outer shape of the hollow portion 11 Since the so-called chamfering is performed, the bending stress concentrated around the corners formed by each side of the outer shape of the hollow part 11 can be dispersed and bending strength can be strengthened. It was.

(Example 3)
Next, a test was conducted to confirm whether the maximum thickness t ₀ and the minimum thickness t ₁ of the long hollow ceramic member of the present invention have an effect on cracks occurring at the outer peripheral corners.

Using the clay produced in Example 1, extrusion molding is performed by the extruder 20 shown in FIG. 6, and the shape of the long hollow ceramic member 1 of the example shown in FIG. Is 85 mm, the height is 85 mm, the maximum thickness t ₀ is 10 mm, and the minimum thickness t ₀ is changed to the values shown in Table 1, respectively. 20 pieces of 1 to 6 were produced. The hollow portion 11 was provided so that the thickness between the adjacent outer peripheral corners became the maximum thickness t _{0 of the} wall thickness, and the thickness became thinner as it became closer to the outer peripheral corner.

Further, the produced clay is extruded by the extruder 20 shown in FIG. 6, and the shape of the long hollow ceramic member 2 in the example shown in FIG. 2 has a length L of 1 m and a width of 85 mm. , The height is 85 mm, the maximum thickness t ₀ is 10 mm, and the minimum thickness t ₀ is changed to the values shown in Table 1, respectively. 20 pieces of 1 to 6 were produced. The center between adjacent outer peripheral corners is the maximum thickness t _0, and the hollow portion 11 is provided so that the thickness is evenly reduced stepwise as the outer peripheral corner is approached. Further, the width W ₁ of the maximum thickness t ₀ was 10 mm, the second-stage width W ₂ was 20 mm, and the third-stage width W ₃ was 30 mm.

Further, using the prepared clay, extrusion molding is performed by the extruder 20 shown in FIG. 6, and the shape of the long hollow ceramic member 3 of the example shown in FIG. 3 has a length L of 1 m and a width of 85 mm. , The height is 85 mm, the maximum thickness t ₀ is 10 mm, and the minimum thickness t ₀ is changed to the values shown in Table 1, respectively. 20 pieces of 1 to 6 were produced. In addition, the side of the outer shape facing each side of the outer periphery is an arc-shaped hollow so that the center of the adjacent outer peripheral corners becomes the maximum thickness t _{0 of} the wall thickness and becomes thinner as the wall becomes closer to the outer corner. Part 11 was provided.

  Then, using the prepared clay, extrusion molding is performed by the extruder 20 shown in FIG. 6, and the thickness is 10 mm, the length L is 1 m, the width is 85 mm, and the height is 85 mm, as shown in FIG. The molded body No. 1 of the comparative example that becomes the conventional long hollow ceramic member 5. 20 pieces of 7 were produced.

  Next, the produced 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. For confirmation, each molded body No. 1-7 were cut | disconnected several places perpendicularly | vertically to the longitudinal direction, and the presence or absence of the crack of an outer periphery corner | angular part was investigated visually. In addition, even if there were no cracks in the outer peripheral corners, the molded body in which deformation such as distortion or twist occurred due to shrinkage during drying was counted as a defective product.

  The results are shown in Table 1.

  As can be seen from the results shown in Table 1, in any case of the shape of the long hollow ceramic members 1 to 3 of the example shown in FIGS. Nos. 1 to 6 are compacts No. 1 and No. 2 which are conventional long hollow ceramic members. Compared to 7, there were more non-defective products.

In any case of the shape of the long hollow ceramic members 1 to 3 in the example shown in FIGS. In the case of a molded body in which the value of t ₁ / t ₀ is 0.6 to 0.9 when the maximum thickness is ₆ and the minimum thickness is t ₁ , Among them, 80% or more of the molded products were non-defective products. Among the molded products having a value of t ₁ / t ₀ outside this range, none of the 20 molded products produced had a good product count of 80% or more.

As a result, among the long hollow ceramic members of the present invention, the long hollow ceramic member whose outer periphery of the cross section perpendicular to the longitudinal direction has a polygonal shape and whose thickness becomes thinner as it approaches the outer peripheral corner. Then, it is preferable that the value of t ₁ / t ₀ is 0.6 to 0.9, where t ₀ is the maximum thickness of the portion corresponding to each side of the outer periphery, and t ₁ is the minimum thickness. I understood that.

_{1~4, A 1, A 2,} B 1, B 2: elongated hollow ceramic member
11: Hollow part
13: reinforcing portion L: length t of the long hollow ceramic member _0: maximum thickness t _1: Minimum Thickness

Claims (3)

It is a long hollow ceramic member having a hollow portion penetrating in the longitudinal direction, the outer periphery of the cross section perpendicular to the longitudinal direction is polygonal, and the thickness becomes thinner as it approaches the outer corner portion A long hollow ceramic member. 2. The long hollow ceramic member according to claim 1, wherein, in the cross section, the outer side of the hollow portion facing each side of the outer periphery has an arc shape. In the cross section, when the maximum thickness of each of the portions corresponding to the respective sides of the outer periphery is t ₀ and the minimum thickness is t ₁ , the value of t ₁ / t ₀ is 0.6-0. 9. The long hollow ceramic member according to claim 1, wherein the long hollow ceramic member is 9.

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