JP2007197303A - Method for forming refractory molded product for being mounted in plate glass molding apparatus and refractory molded product, and method for molding plate glass and plate glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a refractory molded product for being mounted in a plate glass molding apparatus that is used for a long period of time and molded highly precisely even when it has complicated shape and a refractory molded body, and a method for molding plate glass by an apparatus in which this refractory molded product is mounted and plate glass obtained by this method. <P>SOLUTION: The method for molding a refractory molded product 10 for being mounted in a plate glass molding apparatus is provided in which there is, by casting, fabricated the refractory molded product 10 having, on its top portion, a trough-shaped molten glass-supplying groove 10a of which the upper portion is opened, both sidewall top edges 10b as an overflow weir, and both sidewall external surfaces 10c terminated at a lower end 10d so as to have a cross sectional surface of substantially wedge shape, wherein the refractory molded product 10 for being mounted in a plate glass molding apparatus has a dimension of 1,500 mm or more in the long length direction of the refractory molded product 10. The method for molding a glass plate comprises supplying alkali-free glass into the refractory molded product 10, and adjusting heating and cooling conditions or the like so that the thickness dimension of the plate glass becomes a predetermined thickness of 0.7 mm or less, thereby molding the plate glass. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet glass forming apparatus, and more particularly to a sheet glass forming apparatus according to an overflow down draw method used for forming a sheet glass mounted on a liquid crystal display device or the like and a formed sheet glass.

  Various methods and apparatuses for forming plate glass of a predetermined size from molten glass in a high temperature state are known. Among them, an apparatus for forming a sheet glass by a method generally referred to as an overflow downdraw method is a glass supply groove 1a having an open upper surface in a bowl shape as illustrated in FIGS. 2 (A) and 2 (B). At the top. This device is similar to a cutting edge having a substantially wedge shape, with the two top portions corresponding to the end walls of the glass supply groove 1a being overflow weirs 1b and the two outer surfaces 1c of both side walls approaching each other downward. The molded body 1 having the appearance as described above and terminated at the lower end 1d is provided. The molten glass G melted and adjusted so as to be in a homogeneous state at a high temperature is continuously supplied from the one end side of the glass supply groove 1a into the glass supply groove 1a through the molten glass supply pipe 2. Then, after temporarily staying in the glass supply groove 1a, the molten glass overflows from the two ridge lines 1e on the tops of both side walls, and further on the two outer surfaces 1c having a substantially wedge shape sandwiched between the guides 1f on both side walls. It flows down along and merges at the lower end 1d. And by using suitably the heat resistant roller (illustration omitted) etc. which were arrange | positioned further below this lower end 1d, the molten glass G is continuously extended further below, and the plate glass P is shape | molded. The plate glass P obtained in this way has high smoothness because the surface of the molded glass does not directly contact the surface of the refractory or the like at the time of melting and molding, and is in a state corresponding to a free melting surface. As shown in FIG. 2C, the plate thickness dimension of the central region Pα and both end portions Pβ is substantially uniform.

  The outer shape of the molded body 1 is such that the side wall top ridge line 1e of the glass supply groove 1a is substantially linear over the entire length, and the molten glass G overflows from both sides of the ridge line 1e evenly, that is, overflows. Has been. However, this type of molded body 1 needs to be made of a refractory having high corrosion resistance to the molten glass G in a high temperature state, and its weight increases when constructed using a material suitable for it. . For this reason, both ends in the longitudinal direction of the molded body 1 are supported by the supporting refractory 3 from below, but during continuous production of sheet glass, it will continue to be exposed to high temperature conditions for a long period of time. Since the molded body's own weight is supported only by the supporting refractory 3 that is in contact with both ends of the molded body while operating for a long period of time, the molded body during that period as shown in FIGS. 3 (A) and 3 (B) The downward self-weight component F is always applied, and a deformation phenomenon called creep (also referred to as creep deformation or thermal deformation) occurs in which the molded body is gradually bent downward and deformed. When this deformation phenomenon occurs, as shown in FIG. 3C, the amount of overflow glass in the molten glass central region 1g becomes larger than the amount of overflow glass in the molten glass both end region 1h. The plate thickness dimension becomes larger than both end portions Pβ. In order to avoid this, the molding temperature is changed, but there is a balance with other conditions, and there is a limit to the control. This deformation phenomenon is particularly large when a sheet glass P having a large effective width is formed for the purpose of obtaining a sheet glass product having a large area (for example, 1000 × 1500 mm). ), The amount of creep deformation tends to be larger.

Since such creep deformation greatly affects the forming accuracy of the surface of the plate glass, various inventions for suppressing creep deformation have been made so far. Patent Document 1 proposes an apparatus for forming a sheet glass P that suppresses creep deformation of the molded body 1 by forming a through hole in the length direction of the molded body 1 and inserting a support member into the through hole. Moreover, in patent document 2, the shape of the side surface in the both ends of the longitudinal direction of a molded object becomes the inclined surface made to mutually approach toward the downward direction, and it is possible to press-support from a support refractory to a molded object center direction. A shaped body shape with the following structure was presented. Patent Document 3 also discloses an invention that makes creep deformation difficult by setting the ratio between the total length and height of the molded body 1 within a predetermined range. Further, in Patent Document 4, the overflow amount of the molten glass G can be easily achieved by forming the top ridges 1e on both side walls of the overflow weir in advance so as to bend downward in the start end region and / or the end region in the flow direction of the molten glass. An invention that can be adjusted to have been disclosed. As for the quality of the sheet glass produced by using such a sheet glass forming apparatus, Patent Document 5 discloses that the surface waviness of the light-transmitting surface is 0.05 μm or less and the surface roughness is 5 mm or less. Yes.
JP-A-11-246230 JP 2004-284843 A JP 2004-315286 A JP 2004-315287 A JP 2006-137431 A

  However, the inventions made so far are not sufficient to obtain a refractory molded article that makes it easy to continue producing plate glass having a large area over a long period of time. For example, although the method disclosed in Patent Document 1 is an effective method, in order to form a through-hole in the longitudinal direction of the refractory molded article, the refractory molded article once formed and fired is used to make holes. There is a problem that a cutting process must be performed, and a great amount of labor and cost are required for the cutting process. There is also a risk that fine scratches and cracks may occur on the inner surface of the hole subjected to the cutting process. Further, in the configuration as in Patent Document 2, a great load continues to be applied to the refractory material that supports the refractory molded body, and a configuration that reduces the load is also necessary. Further, although Patent Publication 3 and Patent Publication 4 have a certain effect, further improvement is necessary to maintain a stable state for a longer period of time. Moreover, in order to realize the surface accuracy as disclosed in Patent Document 5, it is necessary to realize higher quality from the beginning of the production, assuming that the glass quality deteriorates with time in the production period over a long period of time. Therefore, further improvement is necessary in order to produce a higher-quality plate glass by extending the stable production period longer than before.

  From the above viewpoint, the present invention is a refractory molded body mounted on a sheet glass forming apparatus used in a high temperature state for a long period of time, and has a complicated configuration shape that easily suppresses creep deformation of the molded body. In addition, a method for forming a refractory molded body for mounting on a sheet glass forming apparatus that can form the shape accurately and easily and does not require a large amount of post-processing, and a long sheet glass forming apparatus obtained by this forming method. It is an object of the present invention to provide a mounting refractory molded body, a sheet glass forming method using a sheet glass forming apparatus on which the refractory molded body is mounted, and a sheet glass obtained by the sheet glass forming method.

  That is, the method for forming a refractory molded body according to the present invention is characterized in that a refractory molded body used for molding a sheet glass by an overflow down draw method is manufactured by casting.

  In the method for molding a refractory molded article of the present invention, the refractory molded article has a refractory molded article used for the overflow downdraw method, that is, a bowl-shaped molten glass supply groove having an open top, A molded body in which the tops of both side walls of the glass supply groove are overflow weirs, and the outer surfaces of both side walls are close to each other with the outer surfaces facing downward so that the cross-section is substantially wedge-shaped. A glass forming apparatus for forming glass sheet by continuously supplying molten glass from one end of the glass supply groove, overflowing from the top edge of both side walls, flowing down along the outer surface of both side walls, and joining at the substantially wedge-shaped lower end It is to be mounted on.

  In the method for molding a refractory molded body of the present invention, casting may be performed by any method, any device may be used, and the material to be cast is also cast. There is no limitation. That is, in the case of the casting method, even in the case of so-called electroforming that is cast after being heated from 1900 ° C. to 2500 ° C. in a high-temperature heating furnace such as an arc furnace, water different from the material to be cast is used. Or an organic material or the like as a solvent, and only the solvent used after casting is removed by various means such as drying and adsorption to obtain a state composed of a material to be cast, and a molded body is obtained by firing. It may be a thing. Moreover, a decompression device, a pressurization device, a stirring device, a vibration device, an ultrasonic generator, or the like can be used as needed during casting.

  In any case, it may be a casting method capable of obtaining a dense molded body and achieving high fire resistance, casting time and temperature, laying time and temperature, redox of casting material, acid basicity A preferable condition can be selected by selecting an optimum one for various conditions such as the type and amount of the additive at the time of casting.

  In addition to the above, the molding method of the refractory molded body of the present invention is preferable if the casting is mud casting, because even a complicated shape can be easily molded.

  Here, that the casting is mud casting means that a refractory for mounting on a sheet glass forming apparatus is formed by a so-called slip casting method.

  The slurry used for casting is adjusted by adjusting the concentration and pH of the slurry, the type and concentration of additives, the temperature of the slurry, etc., and degassed in advance so as not to cause unnecessary aggregation or bubbles during casting. It can adjust through processes, such as stirring.

  Moreover, various media, such as organic solvents, such as water and alcohol, can be used as a solvent used in order to comprise the slurry used for slurry casting. Furthermore, various trace additives may be used to adjust the properties of the mud. For example, a dispersing agent, viscosity adjusting agent, pH adjusting agent, antifreezing agent, antioxidant, surface coating agent or defoaming agent can be used as appropriate.

  The frame (or also referred to as a mold) into which mud is cast by the method for forming a refractory molded body of the present invention may be made of any material. Also, the thickness and structure of the frame are not particularly limited. For example, a gypsum frame that absorbs the solvent with time may be used as the frame, and other porous materials and water-absorbing materials may be used. Furthermore, a mechanism for compensating for expansion and contraction of the frame can be provided at a predetermined location. Furthermore, it is possible to apply a coating agent that acts as a protective coating to prevent surface cracks, cracks, surface scratches, etc. of the molded body when the frame is removed from the inner surface of the frame body. It is also possible to adjust the absorption and the aggregation of the cast material to an appropriate state.

  In addition, in order to realize a complex uneven shape on the surface of the final refractory molded body in advance, the frame body can have a surface shape according to the shape of the shape, and is provided with a predetermined surface shape that is repeated, or Arbitrary numbers of protrusions and depressions having predetermined dimensions can be provided at arbitrary locations.

  In addition to the above, the method for molding a refractory molded body according to the present invention is not limited to the above, and if the molding is performed so that a through hole is formed in the longitudinal direction of the refractory molded body, A hole having a smooth surface can be formed without requiring labor and time for drilling.

  Here, cast molding so that the through-hole is formed in the longitudinal direction of the refractory molded body is configured such that the through-hole is formed after casting the structure inside the cast frame body during casting molding. Thus, a molded body having holes is obtained.

  The number, position, size, and shape of the through holes formed in the refractory molded body are not particularly limited. In addition, the through hole does not necessarily have to be formed immediately after casting, and a through hole having a smaller diameter than that of the final shape is formed in a configuration in which the through hole is formed. Easy processing after casting, such as making a through hole easy by using a simple frame or by embedding a material that is easy to process at the position where the through hole is formed, such as a resin material or wood in advance. It is also possible to form a through-hole by processing the molded body before firing in a certain state into a through-hole having a final dimension by a predetermined tool, a cutting device, a drilling device, or the like. In addition, the material embedded in the position where the through hole is formed is heated and burned to form a through hole, and the material is corroded and weakened by spraying, applying, or injecting an acid or alkali chemical. Through holes can be easily formed. And these various methods do not perform only one, You may combine several methods.

  Further, in the present invention, a filler is formed by casting so that a structural material that improves the strength is embedded in advance in the cavity of the through hole formed in the refractory molded body, and then casted during firing. The refractory molded body may be configured so as to be firmly bonded to a structural material for improving the strength. Moreover, as such a structural material, if a metal material, ceramics, or a composite material of a plurality of materials is used, it can be firmly bonded to a refractory molded body around the structural material. Any material may be used. Further, the shape, number, and size of the structural material are not particularly limited as long as they exhibit desired performance.

  In addition to the above, the molding method of the refractory molded body of the present invention is related to the present invention of various ceramic members, refractory materials, etc. as long as it includes a casting molding process, a drying process, a firing process, and an appearance inspection process. Since it can shape | mold by applying the technique utilized in order to obtain a molded article with a dimension smaller than this, it is preferable.

  Here, the casting molding process is a process of casting a material to be cast into a mold, the drying process is a process of drying the cast material under predetermined conditions, and the firing process is a process for drying a dried product. It is a step of firing in a high temperature state of 1500 ° C. or higher, and the appearance inspection step is a step of inspecting the appearance surface of the fired product for various defects.

  For the molding process of casting the material to be cast into the mold, it is important to make the casting speed appropriate to minimize entrainment bubbles during casting. It is also possible to remove the fine bubbles that will be present in the casting body by adopting the method of using. Further, if necessary, one or more defoaming operations such as addition of an antifoaming agent, blowing of water vapor, stirring and vibration can be employed.

  As for the casting method, even if one or many casting nozzles are inserted from the top of the mold body and used to fill mud, filling is performed from the side of the mold body or from the bottom of the mold body. It is also possible to fill in from these plural parts simultaneously or sequentially.

  In addition, when adjusting the mud to be cast according to the present invention, the slurry prepared by mixing a plurality of additives and aggregates is not immediately filled, but is held for a certain period of time, and the aggregates are sufficient for the medium. It is preferable to perform the filling operation after being familiarized. This is the same as the case of adjusting the ceramic glaze, and there is a problem that various defects are likely to occur in the molded article when the filling operation is performed in a state where the aggregate is not familiar with the medium.

  As for the drying process of drying the cast product under predetermined conditions, the temperature and humidity in the drying atmosphere are maintained and controlled at predetermined conditions, or the gas is forcibly sprayed onto the surface of the object to be dried, or It can also be dried by placing the object to be dried in a room where the temperature conditions for circulating the gas are adjusted, and apply a chemical that absorbs the medium used during casting to the surface of the object to be dried. Alternatively, it is possible to employ a method such as coating. When a gas having a predetermined temperature is used, an atmospheric gas that easily reacts with the medium can be mixed in the gas, and various gases can be appropriately mixed and adjusted to a predetermined concentration. It is also possible to promote drying by applying centrifugal force or gravity during drying. Furthermore, a predetermined portion where high-speed drying can be realized at the time of drying in the material to be dried is specified by a drying simulation program of the material to be dried by FEM (finite element method), BEM (boundary element method), etc. It is also possible to adopt a design for making holes. When such a method is adopted, casting is performed in a state where a fibrous material such as an organic material is wired inside the casting frame body used when casting is performed in advance, and the fiber is formed when casting is completed. The material may be drawn and dried, and the dried vacancies may be filled with a refractory powder material by injection filling.

  In addition, since uniform drying is performed in the drying process, by using a large microwave heating apparatus, a portion or the like that tends to be slow in drying speed can be dried at high speed. By using such a heating method in combination with other heating methods, it is possible to suppress the inconvenience that only local drying is performed when the refractory molded body is dried, and the occurrence of fine cracks caused by uneven drying. It becomes possible to do.

  About the baking process which bakes a dried product in the high temperature state of 1500 degreeC or more, what to heat the to-be-heated material which is a dried product by what kind of heating method may be used. In other words, the firing device, firing temperature, firing time, firing atmosphere, heating method, and method of placing the object to be fired are such that uniform heating can be performed and defects such as cracking and peeling are not likely to occur on the surface of the molded body during firing. There is no particular limitation as long as optimal firing can be performed with respect to cost, time, and the like.

  As for the appearance inspection process for investigating the presence or absence of various defects on the appearance surface of the fired product, visual inspection, ultrasonic inspection, use of a magnifying glass, reflected sound or reflected light test, water applied to the surface of the molded body, etc. Various test methods such as a method for observing the dry state of the medium can be used in combination as necessary.

  In addition, the molding method of the refractory molded body according to the present invention, when it is difficult to realize a shape having the required accuracy only by casting, the surface of the molded body before drying taken out from the mold body after casting is obtained by an appropriate means. It is possible to make the surface state into an appropriate state by processing. As a processing method, a desired well-known method can be used alone or in combination. As such a processing method, for example, cutting, sandblasting, cutting, polishing, drilling, or the like can be employed singly or in plural as necessary. In particular, the shape of both sides of the molded body, such as the ridges on both side walls of the refractory molded body, greatly influences the dimensions and surface properties of the glass sheet and the amount of distortion when molding the glass sheet. It is important to make it form.

  In addition to the above, the molding method of the refractory molded body of the present invention, if part of the cross-sectional shape of the through-hole is any one of a substantially polygonal shape, a substantially elliptical shape and a combination of both, Various types of inserts can be disposed in the through-holes, and accordingly, usable materials can be selected from a wide range of materials.

  Here, a part of the cross-sectional shape of the through-hole is made of any one of a substantially polygonal shape, a substantially elliptical shape, and a combination of both, the shape of the cross-section perpendicular to the hole penetrating the refractory molded body, This indicates that the shape is partially a polygonal shape or a shape similar to a polygonal shape, an elliptical shape or a shape similar to an elliptical shape, or a combination thereof.

  In addition to the above, the cross-sectional shape of the through hole is more preferably free from a portion having an acute angle of less than 90 degrees. This is because, if such an acute-angled portion is in the cross-sectional shape of the through hole, there is a risk that stress applied to the refractory molded body from the outside is concentrated locally.

  The refractory molded body of the present invention is formed by any of the molding methods described above, and has a longitudinal dimension of 1500 mm or more.

  Here, the longitudinal dimension of the refractory molded body means the overall length dimension of the refractory molded body in the longitudinal direction.

  When the dimension in the longitudinal direction of the refractory molded body is 1500 mm or more, it is possible to form a plate glass for a large area liquid crystal substrate, and to suppress the molding cost of the plate glass by increasing the area of one master plate glass. Is preferable.

  The refractory molded body of the present invention can be used with any material. Of course, since it is an apparatus for forming sheet glass, it must be a material having a heat resistance of 1500 ° C. or higher, more preferably a heat resistance of 1800 ° C. or higher, and more preferably 2000 ° C. or higher. It has the heat resistance of. Moreover, the material which comprises a molded object does not need to be 1 type, multiple types may be sufficient and it may consist of a combination of a several member.

  For example, a fired refractory excellent in heat resistance and high-temperature strength, a non-fired refractory, an amorphous refractory, etc. are suitable as the material of the molded body. Further examples of this material include silica refractories, clay refractories, high alumina refractories, silicon carbide refractories, chrome refractories, magnesia refractories, sillimanite refractories, dolomite refractories, and alumina nitride refractories. Refractories, zirconia refractories, zircon refractories, mullite refractories, fused quartz refractories, synthetic quartz refractories and the like can be used. In addition, various fiber boards and irregular refractory fiber materials can be used as appropriate, and alloys having a platinum group element as a main component, for example, heat-resistant noble metals such as platinum alloys can be used as necessary. . These molded body constituent materials can be used as long as they can sufficiently realize the functions of the molded body, whether used alone or in a plurality of types.

However, among the above, some examples of the most preferable materials to be applied to the refractory molded body of the present invention are exemplified, for example, zirconia refractories and zircon refractories, and contain 40% by mass or more as ZrO _2. It is preferable that Further in addition to the zirconia refractory, it may be used refractory containing 95 wt% of Al ₂ O ₃ from 5 wt%. Furthermore the SiO ₂ may be used those containing 98 wt% to 50 wt%.

Moreover, about the refractory molded object of this invention, it is possible to contain various additives with a various form. For example, SiO ₂ , Al ₂ O ₃ , MgO, Cr ₂ O ₃ , ZrO ₂ , B ₂ O ₃ , MgO, ZnO, CaO, BaO, La ₂ O ₃ , WO ₂ can be added as components that can be added. TiO ₂ , HfO ₂ , TaO ₂ , BeO, Y ₂ O ₃ or P ₂ O ₅ . Of course, in addition to this, it may be added to give desired performance. For example, C, Pt, Rh, Os, Ir, Pd, Ru, Y, Sc, or W may be intentionally added as an element component, but other elements may be used. For platinum and platinum alloys, which are heat-resistant noble metals, the surface of the refractory molded body of the present invention can be coated in a thin film or sprayed state.

In addition to the above, the refractory molded body of the present invention has an average linear expansion coefficient of 2.5 × 10 ⁻⁶ / ° C. to 8.5 × 10 ⁻⁶ / in a temperature range of 30 ° C. to 1400 ° C. If it is in the range of ° C., a plate glass having a high dimensional accuracy can be formed without causing a large dimensional variation even in a high temperature state.

Here, the average linear expansion coefficient of the refractory molded body is 2.5 × in the temperature range of 30 ° C. to 1400 ° C.
The range of 10 ⁻⁶ / ° C. to 8.5 × 10 ⁻⁶ / ° C. means that the coefficient of linear expansion accompanying the temperature increase from 30 ° C. to 1400 ° C. is 2.5 × 10 ^−6. It means that it becomes a value from 8.5 ° C. to 8.5 × 10 ⁻⁶ / ° C.

The average linear expansion coefficient of the refractory molded body in the temperature range of 30 ° C. to 1400 ° C. is 2.5 ×.
When the temperature is lower than 10 ⁻⁶ / ° C., various properties such as the strength and workability of the surface suitable for constituting the molded body may be hindered. Further, if the average linear expansion coefficient of the refractory molded body in the temperature range of 30 ° C. to 1400 ° C. is larger than 8.5 × 10 ⁻⁶ / ° C., the molded body is likely to be distorted at high temperatures due to the temperature distribution of the molded body. As a result, there is a possibility of causing variation in the thickness of the thin glass to be formed, surface waviness and the like, which is not preferable.

  As a method of measuring the average linear expansion coefficient of a refractory molded body, use a measuring device having a heating heat source from 30 ° C. to 1400 ° C. using an expansion coefficient measuring device calibrated with a reference material such as ASTM. It can be specified by measuring a sample piece cut into a rod shape by the above.

  Since the refractory molded article of the present invention has sufficient thermal shock resistance against a sudden temperature change during heating and cooling if its apparent porosity is in the range of 8% to 30%, stable high temperature operation is possible. Become.

  The fact that the apparent porosity of the refractory molded article is in the range of 8% to 30% means that the apparent porosity measured by the Archimedes method in a room temperature environment is in the range of 8% to 30%. .

  When the apparent porosity of the refractory molded body is less than 8%, the spalling property against a rapid change in temperature is deteriorated and heat cracking is likely to occur, and when the apparent porosity is greater than 30%, the strength as a refractory material is reduced. Therefore, it is not preferable.

  As a method of measuring the apparent porosity of the refractory molded body, the mass of the dried sample, the mass of the saturated sample in water, and the mass of the saturated sample in air are measured by a measurement method according to JIS R2205 (1992). Can be calculated.

  The refractory molded body of the present invention can be used by being fixed in a state where a member supporting the molded body is inserted into the through-hole, as long as the cast molded body has a through hole. A plurality of heat-resistant materials, insulating materials, or lightweight structural materials such as ceramic fibers can be filled. Furthermore, it is possible to prevent the durability of the support member from being impaired by causing the support member to be heated more than necessary by circulating a specific fluid medium in the cavity as necessary. As a fluid medium, a gas having poor reactivity such as helium, argon, nitrogen, carbon dioxide, or the like, or conversely, inside the cavity of the support member is oxidized atmosphere such as oxygen, water vapor, air, hydrogen, carbon monoxide, etc. By using a reducing atmosphere, it is possible to cover structural defects on the cavity surface with the reaction layer. The fluid medium that has been preheated to a predetermined temperature can be fluidized, and the medium once fluidized can be recovered and reused.

  The refractory molded body for mounting on a sheet glass forming apparatus of the present invention is used when forming a thin glass by being mounted on a sheet glass forming apparatus. However, a sheet glass that requires such a refractory molded body is used. The molding apparatus, that is, the overflow downdraw molding apparatus is not limited to the liquid crystal glass sheet, and can be applied to the molding of thin glass sheets for various applications without limiting the applications. For example, it can be used for a cover glass for a solid-state imaging device, a plate glass for field emission, a cover glass for EL, a glass for optical filter, and the like.

  The glass sheet forming method of the present invention supplies alkali-free glass heated to 1000 ° C. or higher into the refractory molded body, and is heated and cooled under conditions such that the thickness dimension is 0.7 mm or less, the downdraw speed, and A sheet glass is formed by adjusting the sheet glass forming width.

  Here, the alkali-free glass heated to 1000 ° C. or higher is supplied into the refractory molded body, and the heating and cooling conditions, the downdraw speed, and the sheet glass forming width are adjusted so that the thickness dimension is 0.7 mm or less. Forming a sheet glass by doing this is as follows. In other words, the shape of the refractory molded body manufactured by casting forming a predetermined shape by casting a slurry prepared in advance into a mold, and forming a desired refractory molded body through drying and firing, and having an open top. A molten glass that is heated to a temperature of at least 1000 ° C. in a molten glass supply groove and continuously supplies alkali-free glass having an appropriate viscosity in a homogeneous state to overflow both side walls of the refractory molded body. Flowing down along the side wall surface of the refractory molded body, the cross-sectional shape of the refractory molded body having a wedge shape is combined at the bottom of the wedge-shaped apex of the bottom of the refractory molded body to form one molten glass ribbon, and further a heating element, The thickness of 0.7mm is adjusted while finely adjusting the heating / cooling conditions, downdraw speed, and sheet glass forming width by the interlocking action of various auxiliary equipment such as edge rollers. It represents shaping the glass sheet as a predetermined dimension of the bottom.

  About thickness dimension, if it is 0.7 mm or less, it can be set as plate | board thickness of various dimensions according to a use. For example, in addition to 0.7 mm, the plate thickness is 0.69 mm, 0.68 mm, 0.67 mm, 0.66 mm, 0.65 mm, 0.64 mm, 0.62 mm, 0.60 mm, 0.55 mm, 0 Various dimensions such as .50 mm, 0.40 mm, and 0.30 mm can be used.

  Regarding the method of adjusting the heating and cooling conditions, the downdraw speed, and the sheet glass forming width, the temperature of the molten glass to be formed is grasped by measurement with a thermocouple or optical measurement, and the temperature of the molten glass is determined from the measured temperature of the molten glass. Since the viscosity becomes clear, it is possible to achieve a plate glass with a plate thickness of 0.70 mm or less while realizing a desired sheet glass forming width by appropriately adjusting the speed of the disk roll for drawing corresponding to the viscosity of the molten glass. It becomes.

  In order to make heating and cooling conditions appropriate, various heating sources can be used properly. It may be a heating by a planar heating element or a local spot heating source. The kind of the heating element to be used may be any as long as it can realize a desired performance without deteriorating the plate glass and its peripheral equipment.

  The sheet glass forming method of the present invention adjusts the forming conditions so that the sheet glass width in which the variation in the sheet thickness dimension in the sheet glass width direction is within ± 0.1 mm is 70% or more of the sheet glass forming width. If it exists, since it can shape | mold the glass plate of the quality with high efficiency, it becomes possible to reduce manufacturing cost.

  Here, adjusting the molding conditions so that the plate glass width in which the variation of the plate thickness dimension in the plate glass width direction is within ± 0.1 mm is 70% or more of the plate glass forming width is as follows. . That is, when forming a sheet glass corresponding to the length of the formed body with the formed body of the present invention having a lengthwise dimension of 1500 mm or more, between the translucent surfaces facing each other in the width direction of the sheet glass perpendicular to the sheet drawing direction. When measuring the variation of the plate thickness of the plate glass corresponding to the interval of, if the range that is formed so that the plate thickness is within the range of ± 0.1 mm with respect to the reference value, the width dimension of the plate glass is 100, It indicates that the adjustment is made to be in a range corresponding to 70 or more.

  Any method for measuring the variation of the plate thickness of the plate glass can be adopted as long as it can perform measurement with an accuracy of 0.1 mm or more at a sufficiently high speed. . For example, a measurement system using a solid-state imaging device, an imaging tube, or the like using a laser measuring instrument can be employed.

  As a method of adjusting the molding conditions so that the plate glass width in which the variation of the plate thickness dimension in the plate glass width direction is within ± 0.1 mm is 70% or more with respect to the plate glass forming width, the temperature of the molten glass as described above is used. In addition to the measurement, it can be optimized by finely adjusting the arrangement position of the disk roll used for forming, the position of the edge roll, the downdraw speed, and the cooling condition of the plate glass.

  The state in which the variation of the sheet thickness dimension in the sheet glass width direction is within ± 0.1 mm is 70% or more of the sheet glass forming width, for example, if the formed sheet glass has a width dimension of 2000 mm, This means that the plate glass width at which the variation of the plate thickness dimension is within ± 0.1 mm is 1400 mm or more.

  About the plate glass width in which the variation of the plate thickness dimension in the plate glass width direction is within ± 0.1 mm, the higher the ratio, the higher the molding efficiency, and more preferably 70% or more. Yes, more preferably 70% or more, more preferably 80% or more, still more preferably 80% or more, most preferably 80% or more.

  Further, since the plate glass of the present invention is formed by the plate glass molded body of the present invention, in addition to the above, the surface of the cast molded body is finely adjusted to any optimum shape. Therefore, it is possible to shorten the period for adjusting the plate width and thickness of the plate glass by changing various manufacturing conditions from the start of plate forming, and therefore, it cannot be used for products that are excessively formed during manufacturing. The amount of the formed glass is suppressed. And various surface properties, such as surface roughness and a wave | undulation of the plate glass shape | molded in this way, become a quality thing compared with the former from the beginning of manufacture.

  The plate glass of the present invention is formed by the above plate glass forming method, and the magnitude of the strain on the one side glass sheet translucent surface is a value within ± 10% of the magnitude of the strain on the other side glass sheet translucent surface. It is characterized by.

  Molded by the plate glass molding method described above, and the magnitude of the strain on the one side glass transparent surface is within ± 10% of the magnitude of the strain on the other side glass transparent surface is as follows: It is. That is, supplying alkali-free glass heated to 1000 ° C. or higher into the refractory molded body of the present invention, and adjusting the heating / cooling conditions, downdraw speed and plate glass forming width so that the thickness dimension is 0.7 mm or less. With respect to two transmission surfaces of a plate glass formed by solidifying from molten glass under a predetermined cooling condition by a forming method for forming a plate glass according to It means that the magnitude of the strain generated when the other plate glass surface facing the surface is cooled is between 90 and 110.

  The magnitude of the strain on the surface of the plate glass can be measured by using a measuring instrument such as a polarizing microscope or a surface stress meter.

  In order to set the magnitude of distortion on the one side of the glass sheet translucent surface to a value within ± 10% of the magnitude of distortion on the other side of the glass sheet translucent surface, In addition to the conditions, it is necessary to make the amount of molten glass overflowing from both side surfaces of the molded body the same when molding plate glass. This is because if the properties of strain on both surfaces exceed ± 10%, the durability of various performances such as strength may be hindered when used for a long time in various applications. However, even if the shape of both side surfaces of the molded body is made symmetrical depending on conditions such as the installation location of the molded body, the same amount of molten glass may not easily overflow. Even in such a case, in the sheet glass formed by using the refractory molded body mounted on the sheet glass forming apparatus of the present invention, the shape of both side surfaces such as the side wall top ridge lines of the molded body is changed to that of the molded body. It is easy to correct such a slight deviation of the overflow amount by finely adjusting and correcting in advance before firing.

  The plate glass of the present invention can be appropriately selected from those whose materials are suitable for the application, among which alkali-free glass, borosilicate glass, and aluminosilicate glass. High melting point glass such as alkaline earth alumina silicate glass is particularly preferred.

  Further, the plate glass of the present invention is a thin plate glass mounted on a liquid crystal display device, as long as it is used as a cover glass for electronic component packages or an impact-resistant window plate glass for building materials, If it is used as an impact-resistant window plate material as a building material application, it becomes possible to supply plate glass products of various sizes and forms according to the customer's request.

  Here, the thin glass mounted on the liquid crystal display device, the cover glass for the electronic component package or the shock-resistant window glass for the building material is mounted on the liquid crystal display and used as an image display member on the front surface of the liquid crystal display device. Sheet glass for structural parts that protects the element as a cover glass for solid-state image sensors such as CCDs and CMOSs, and for structural members that utilize its translucency, and has impact resistance, building materials and construction It shows that it is used also as a plate glass structure utilized as a window material for lighting of an object.

  (1) As described above, the method for molding a refractory molded body according to the present invention is a complicated process because a refractory molded body used for molding a sheet glass by an overflow down draw method is manufactured by casting. From a structure having a simple shape to a simple structure portion, it is possible to mold in almost the same procedure, and even when a complicated surface shape is required, the labor required for molding can be reduced to a minimum.

  (2) Further, the molding method of the refractory molded body of the present invention has been conventionally performed at the time of casting production of other materials and applications, that is, moldings of ceramics, metal materials, etc., if casting is mud casting. It is possible to apply the method and technique to a refractory molded body having a large volume.

  (3) Furthermore, if the molding method of the refractory molded body of the present invention is cast-molded so that a through-hole is formed in the longitudinal direction of the refractory molded body, the molded body can be reduced in weight and function. This makes it possible to cope with various types of processing, and contributes greatly to the continuous molding of thin glass sheets for liquid crystals having superior surface quality and shape quality.

  (4) Moreover, if the shaping | molding method of the refractory molded object of this invention consists of a casting molding process, a drying process, a baking process, and an external appearance inspection process, it is the processing process of the baking molded object required after the baking process. Since it is possible to omit a part, it is possible to realize labor saving in terms of equipment, cost, and the like.

  (5) Further, in the molding method of the refractory molded body of the present invention, if a part of the cross-sectional shape of the through-hole is made of any one of a substantially polygonal shape, a substantially elliptical shape, and a combination of both, Depending on the material, dimensions, etc. of the molded body, it is possible to apply a through hole having an optimum shape in accordance with strength and required functions.

  (6) Further, the refractory molded body of the present invention has a long dimension of a molded body formed by any one of the above-described molding methods of 1500 mm or more, so that the next generation and beyond of large plate glass can be molded. It becomes possible to deal with a refractory molded body that can be carried out continuously for a period of time.

(7) Moreover, the refractory molded article of the present invention has an average linear expansion coefficient of 2.5 × 10 ⁻⁶ / ° C. to 8.5 × 10 ⁻⁶ / in a temperature range of 30 ° C. to 1400 ° C. If the temperature is within the range of ° C., it is possible to reliably form a plate glass having a high precision surface state with high precision by forming in a high temperature state.

  (8) In the method for forming a glass sheet of the present invention, the alkali-free glass heated to 1000 ° C. or higher is supplied into the refractory molded body, and the heating and cooling conditions are reduced so that the thickness dimension is 0.7 mm or less. Since the glass sheet is formed by adjusting the draw speed and the glass sheet forming width, the glass sheet having high molding dimensional accuracy utilizing the surface accuracy of the molded body peculiar to the refractory molded article of the present invention can be smoothly and long-term. It is possible to produce a plate glass of stable quality with high molding efficiency.

  (9) Highly efficient if the molding conditions are adjusted so that the plate glass width is within ± 0.1 mm and the plate glass width is 70% or more of the plate glass forming width. It is possible to reduce the manufacturing cost, and to allocate the remaining capacity obtained by the reduction to the improvement of manufacturing conditions to a higher quality and new capital investment. This makes it possible to diversify manufacturing varieties and respond to new products.

  (10) The plate glass of the present invention is formed by the plate glass forming method described above, and the value of the strain on one side of the glass plate translucent surface is a value within ± 10% of the size of the strain on the plate glass translucent surface on the other side. Therefore, when used in various applications, long-term stable mechanical performance can be realized, and in particular, high reliability can be obtained with little damage due to distortion.

  (11) If the plate glass of the present invention is used as a thin plate glass mounted on a liquid crystal display device, a cover glass for an electronic component package or an impact-resistant window plate glass for building materials, high surface shape accuracy is required. Since the glass sheet has a quality suitable for the glass sheet to be produced, it can exhibit satisfactory performance in each application.

  Hereinafter, a method for forming a refractory molded body for mounting on a sheet glass forming apparatus of the present invention and a refractory molded body obtained by the molding method will be specifically described based on examples.

  FIG. 1 is an explanatory view of a refractory molded body for mounting on a sheet glass forming apparatus according to the present invention. FIG. 1A is a perspective view of the molded body, and FIG. 1B is a cross-sectional view of the molded body with respect to the through hole position.

1A is a ZrO ₂ —SiO ₂ refractory having a resistance to molten glass G (density 3.5 to 4.2 g / cm ³ , Young's modulus). 11 × 10 ¹⁰ to 15 × 10 ¹⁰ Pa). The average coefficient of linear expansion of up to 1400 ° C. from 30 ° C. of the refractory shaped body is a 4.6 × 10 -6 ^/ ℃, an appropriate linear expansion coefficient as the refractory molded body forming the glass sheet. Furthermore, the apparent porosity of this refractory molded body is 11%, which is an appropriate value for imparting thermal shock resistance. And this molded object 10 is the shape which the upper surface opened, and has the bowl-shaped molten glass supply groove | channel 10a which the outline perpendicular | vertical to the elongate direction exhibits a substantially V shape in the top part, This glass The top of both end walls of the supply groove 10a is made into two overflow weirs 10b, and the two outer surfaces 10c of both end walls are made to approach each other downward and terminate in the lower part 10d. The external dimensions of 10 are 2000 mm in length, 800 mm in height, and 280 mm in width.

  The molded body 10 has a through hole 20 as shown in FIG. 1B in the longitudinal direction of the molded body. The cross-section of the through-hole 20 is the largest through-hole opening on one side of the molded body 10 and has a substantially rectangular shape with a horizontal dimension of 80 mm and a vertical dimension of 130 mm. The difference of the unevenness maximum value of the surface roughness is 3 mm or less. Further, the four corners of the cross-section of the through-hole 20 are rounded surfaces having a radius of 10 mm, and have a shape that does not become an acute angle. The through hole 20 is gently inclined from the one side opening end to the other side opening end in the longitudinal direction of the molded body, and the opening size of the other side through hole 20 is 75 mm in horizontal dimension and 125 mm in vertical dimension. It has become. The gentle slope is provided when a support member such as a support rod (not shown) that supports the molded body 10 is inserted into the through-hole 20 and inserted through the opening end on one side. In particular, it is intended to enhance the fixability of the support bar when the support bar is fixed at a predetermined position inserted into the molded body 10. The support member is fixed to the molded body 10 by being inclined only on the support member insertion side. Of course, if such advantages in construction are excluded, there is no problem in use even if the inclined surface is not provided.

  A support member made of high-density silicon carbide (SiC) refractory is inserted into the through-hole 20 from one open end of the through-hole 20, and the molded body 10 is held by the support member 30. Both ends of the support member are fixed and held by a supporting refractory material.

  Next, details of the molding method of the present invention will be specifically described below with respect to the process of molding the refractory molded body 10.

First, a predetermined amount of each raw material powder having a predetermined particle size, which becomes a ZrO ₂ —SiO ₂ refractory molded body 10 by firing, is added a predetermined amount of additives such as water, a dispersant, and a pH adjuster, A slurry having a solid-liquid ratio of 85% by weight or more is prepared and held for 90 hours with the viscosity and temperature adjusted. By setting the sleep time in this way, the interfacial electric double layer in the slurry around each raw material particle constituting the slurry is in a stabilized state, and it is stabilized by preventing agglomeration and the like that cause a decrease in homogeneity. It is assumed that

  On the other hand, the frame used for casting the molded body is molded using a gypsum material. About this gypsum-made frame, it manufactures in the state which divided | segmented the several partial frame (or it is also called a formwork) previously, and combines one another, and comprises one frame. A through-hole is formed by using a column-shaped gypsum body at the location of the through-hole. In this way, a frame body having a size of 2000 mm × 600 mm × 900 mm is prepared, and the slurry stabilized in the homogeneous state described above is continuously filled therein using a pressure casting apparatus. Thus, the casting process of the cast molded body is completed.

  When the filling is completed, the frame body is left as it is for 48 hours for dehydration treatment, and then the frame body is removed from the molded body still containing sufficient moisture and dried in a humidity control environment. Drying is performed by blowing indirect heating air with humidity-controlled air preheated to a predetermined temperature by a far-infrared heating device at a predetermined flow rate to a plurality of predetermined locations set from a drying simulation on the surface of the object to be dried. In order to know the dry state of the surface of the dried product as needed, the color of the surface of the molded product being dried is monitored and measured so that the molded product is not excessively dried. It is necessary to be careful because excessively drying locally may cause defects such as peeling or cracking of the surface of the molded body.

  After the initial drying step is completed, the molded body is held in a humidity-controlled room until the total water content in the molded body decreases to a predetermined value. The dried molded body thus obtained is placed in a batch type electric firing furnace and fired at 1500 ° C. in an air firing atmosphere. In order to prevent the shape of the through hole from being deformed during firing, heating is performed in a state in which a support member prepared in advance by a porous body for holding the through hole is placed in the through hole and the through hole is supported from the inside. As for the firing temperature, the temperature in the through-hole and the outer surface temperature of the molded body are measured by thermocouple measurement so that the temperature conditions are as uniform as possible.

  The fired refractory molded body thus fired is cooled to room temperature in an annealing furnace (also referred to as a slow cooling furnace), and then scratches that interfere with the molding of the sheet glass on the surface of the refractory molded body by visual inspection by a skilled worker. Carefully investigate whether any cracks are found. This investigation is particularly detailed for the parts that are in direct contact with the molten glass. If necessary, a magnifying glass or the like is also used. Thereafter, the fine irregularities and the like on the surface of the molded body are finely adjusted by local polishing or sand blasting, and a refractory molded body that can be finally mounted on a sheet glass forming apparatus is obtained.

  The refractory molded body obtained by the molding method of the present invention as described above is mounted on a sheet glass molding apparatus, and the alkali-free sheet glass for mounting a liquid crystal display device is overflowed with a rigid support rod inserted into the through hole. When it was molded by the downdraw method, it was found that a plate glass having a stable surface quality over a long period of time could be produced.

  Next, the procedure for molding the plate glass of the present invention with the refractory molded body of the present invention and the obtained plate glass will be described.

First, a plurality of glass raw materials are weighed so as to have a predetermined composition and mixed uniformly to prepare a glass raw material mixing batch. Here, in order to form a non-alkali glass plate glass having a thickness dimension of 0.7 mm mounted on a liquid crystal display device, the non-alkali glass composition is SiO ₂ 60% when expressed in terms of mass% in terms of oxide. And Al ₂ O ₃ 15%, B ₂ O ₃ 10%, and RO (R = Mg + Ca + Sr + Ba + Zn) 15%. The density of this glass is 2.49 g / cm ³ . In addition, the glass is designed to have a strain point of 660 ° C. and a temperature corresponding to a high temperature viscosity of 10 ^2.5 dPa · s of 1570 ° C.

  Next, this raw material mixing batch is continuously charged into a melting tank of a glass melting furnace by a glass raw material charging machine and heated to a high temperature of 1500 ° C. or higher to cause a vitrification reaction to obtain a molten glass in a coarse melting state. Thereafter, a physical homogenization operation such as stirring and bubbling is performed on the molten glass in a roughly molten state to obtain a homogeneous molten glass G. In the glass supply groove 10a formed at the top of the refractory molded body 10 formed by the mud casting of the present invention having a long dimension of 2000 mm while the molten glass G is heated to 1000 ° C. or more. Supply continuously to one end.

  Next, the molten glass G overflows from both side wall top ridges 10e of the molded body, flows down along both side walls of the refractory molded body 10, and is combined with each other at the wedge-shaped lower ends of the refractory molded body 10 to form one piece. It becomes a ribbon of molten glass G. The ribbon of the molten glass G is rapidly cooled by the atmospheric environment around the molded body to become a solid, and finally becomes a plate glass.

  Here, the temperature of the molten glass before becoming a solid body is continuously measured by a thermocouple, and the viscosity value of the molten glass is determined from the measurement result. And from this measurement result, it is possible to adjust the drawing speed by the disk roll and to set the heating / cooling conditions by the heating element, and to change the position of the edge roll. The thickness dimension of the plate glass after cooling is adjusted within 0.7 ± 0.1 mm. As a result of such adjustment, the plate glass width in which the variation of the plate thickness dimension in the plate glass width direction is within ± 0.1 mm is 80% or more with respect to the plate glass forming width.

  The 0.7 mm-thick plate glass thus obtained is cut out by a cutting device having a diamond wheel in order to measure the distortion of its cross section to obtain a strain measurement sample piece. Next, when measuring the magnitude of distortion of both light-transmitting surfaces at room temperature with a polarizing microscope having a Babinet Soleil compensator in a state of being immersed in a preliminarily adjusted immersion liquid to have a refractive index comparable to that of plate glass, The magnitude of the distortion of the light transmitting surface of one plate glass is within ± 3% of the magnitude of the distortion of the light transmitting surface of the other plate glass, which proves to have the performance as the plate glass of the present invention.

  As described above, the plate glass obtained by the plate glass forming method of the present invention has high performance, and it is clear that the plate glass has performance necessary for mounting on a liquid crystal display device.

It is explanatory drawing of the refractory molded object of this invention, (A) is a perspective view, (B) represents sectional drawing of a through-hole part. It is explanatory drawing at the time of manufacture of the conventional plate glass shaping | molding apparatus, (A) is a top view, (B) is sectional drawing of the XX plane of (A) figure, (C) is YY of (A) figure. A plane sectional view is shown. It is explanatory drawing of the manufacture late stage of the conventional plate glass shaping | molding apparatus, (A) is a top view, (B) is sectional drawing of the XX plane of (A) figure, (C) is YY of (A) figure. A plane sectional view is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 Refractory molded object 1a, 10a Molten glass supply groove | channel 1b, 10b Overflow weir 1c, 10c Both-side wall outer surface 1d, 10d Lower end 1e, 10e Both-side wall top edge 1f Both-side wall guide 1g Molten glass center area | region 1h Molten glass both ends Area 2 Molten glass supply pipe 3 Support refractory 20 Through-hole F Gravity G Molten glass P Plate glass Pα Center part of plate glass Pβ Peripheral part of plate glass

Claims (11)

  A method for producing a refractory molded article, comprising producing a refractory molded article used for molding a sheet glass by an overflow down draw method by casting.   2. The method for forming a refractory molded body according to claim 1, wherein the casting is mud casting.   The method for molding a refractory molded body according to claim 1 or 2, wherein the refractory molded body is cast and formed so that a through-hole is formed in a longitudinal direction of the refractory molded body.   The method for forming a refractory molded body according to any one of claims 1 to 3, comprising a casting process, a drying process, a firing process, and an appearance inspection process.   4. The method for forming a refractory molded body according to claim 3, wherein a part of the cross-sectional shape of the through-hole is formed of any one of a substantially polygonal shape, a substantially elliptical shape, and a combination of both.   A refractory molded article formed by the molding method according to any one of claims 1 to 5 and having a longitudinal dimension of 1500 mm or more. The average linear expansion coefficient of the refractory molded body is in the range of 2.5 × 10 ⁻⁶ / ° C. to 8.5 × 10 ⁻⁶ / ° C. in the temperature range of 30 ° C. to 1400 ° C. 6. A refractory molded article according to 6.   The alkali-free glass heated to 1000 ° C or higher is supplied into the refractory molded body according to claim 6 or 7, and the heating and cooling conditions, the downdraw speed and the plate glass are adjusted so that the thickness dimension is 0.7 mm or less. A method for forming a sheet glass, comprising forming a sheet glass by adjusting a forming width.   The plate glass according to claim 8, wherein the forming conditions are adjusted so that the plate glass width in which the variation of the plate thickness dimension in the plate glass width direction is within ± 0.1 mm is 70% or more of the plate glass forming width. Molding method.   It is shape | molded by the plate glass shaping | molding method of Claim 8 or Claim 9, and the magnitude | size of the distortion of the plate glass translucent surface of one side is the value within +/- 10% of the magnitude | size of the distortion of the plate glass translucent surface of the other side. A sheet glass characterized by being.   11. The plate glass according to claim 10, wherein the plate glass is used as a thin plate glass mounted on a liquid crystal display device, a cover glass for an electronic component package, or an impact-resistant window plate glass for building materials.

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