JP2004284843A - Apparatus and method of forming plate glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forming plate glass which satisfies various characteristics such as heat resistance against high temperature required for manufacturing over a long time and a method of manufacturing the plate glass in the apparatus for forming the plate glass by an overflow-down-draw system and the method of manufacturing the plate glass using the apparatus. <P>SOLUTION: The plate glass forming apparatus is provided with a molten glass flow rate control structure 10 having a trough-shaped molten glass supply channel 12 having an opened upper part on the top part and both side walls 13 the outside surface part of which has a wedge-shaped cross section to be close downward and the plate glass is formed by supplying the molten glass from one end of the glass supply channel 12 to overflow from the top part of both side walls and flow down along both side walls 13. Both side surfaces of the flow rate control structure 10 in the longitudinal direction are opposed inclined surfaces to be close downward at least at the lower part and the inclined surfaces 10a and 10b are supported to be pressed to the center direction from the side by each supporting body 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an overflow down-draw type sheet glass manufacturing apparatus and a sheet glass forming method using the apparatus.
[0002]
[Prior art]
Many methods for forming a glass sheet have been devised and practiced. One of the currently used sheet glass forming methods is an overflow down draw method. This method is used as a method for producing a sheet glass having high smoothness because the surface of a formed sheet glass corresponds to a free-melting surface during melting. Conventionally, in this method, a sheet glass is formed using a forming apparatus as shown in FIG.
[0003]
That is, the molten glass is continuously supplied from the glass melting furnace to the uniform distribution groove having a tub-like shape in which the upper part of the flow control structure is opened by the refractory supply pipe. Then, the molten glass overflows from the tops of both side walls of the flow rate control structure, flows down along the outer surfaces of both side walls, and joins at the lower end of the control structure having a substantially wedge-shaped cross section to form one sheet glass molded body. It is to get. Regarding this method, there are Patent Documents 1 and 2 that disclose methods for improving the warpage and distortion of a sheet glass, and Patent Document 3 is also disclosed as a method for adjusting the thickness of a molded product.
[0004]
However, with regard to flat glass having high-precision surface properties, demand for electronic glass such as liquid crystal display devices and next-generation display devices, and optical-related components such as imaging devices for which such flat glass is used is increasing. Accordingly, there is a tendency that large-sized sheet glass is required, and accordingly, the necessity of a sheet glass satisfying dimensions and surface accuracy which are difficult to form with a conventional manufacturing apparatus and manufacturing method has been increased. In order to cope with this, the manufacturing method and the manufacturing apparatus have been drastically reviewed, and research has been conducted to satisfy the demand and to enable the manufacture of a flat glass product having higher quality than ever before. Among them, a particular problem arises from the fact that the above-described flow rate control structure does not assume the formation of a large sheet glass.
[0005]
In order to enable efficient mass production, equipment that can be produced over a long period of time is necessary. However, as a factor that largely affects future production, the short life of the flow control structure is regarded as important. I have. Specifically, when the flow control structure is used for a long period of time, the load of the molten glass itself, the weight of the flow control structure, and the stress applied from the roller that pulls the sheet glass continue to be applied over time, resulting in a flow control structure. Cracks occur in the center of the lower end, or deformation beyond the allowable range occurs. This makes it impossible to produce a sheet glass having high-precision dimensions.
[0006]
Therefore, in order to improve this problem, in Patent Document 4, as shown in FIG. 4, in order to structurally strengthen the lower central portion of the apparatus, a hole 25 through which a support member is inserted inside the constituent material of the flow control structure is used. An invention is disclosed in which a problem can be solved by using a structure capable of withstanding a large load applied to a stress concentration portion below the device, such as the lower end 23 of the flow rate adjusting structure, such as the lower end 23 of the flow control structure.
[0007]
[Patent Document 1]
JP-A-2001-31434 (pages 2 to 4, FIG. 1)
[Patent Document 2]
Japanese Patent Application Laid-Open No. 2001-106539 (Pages 2 to 3, FIG. 1)
[Patent Document 3]
JP-A-9-110443 (pages 2 to 6, FIG. 1)
[Patent Document 4]
JP-A-11-246230 (pages 2 to 5, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, even in the case of adopting the flow control structure adopting the above-mentioned solution, various factors that are difficult to predict overlap, so that the structural response, that is, the creep deformation resistance, is not taken for a long time at a high temperature. Insufficient strength or the like causes a problem that the flow control structure has a substantially wedge-shaped cross-section near the center of the lower end in the longitudinal direction. Therefore, as a countermeasure against this, an attempt was made to avoid this problem by curving the center of the lower end of the flow control structure upward to some extent in advance.
[0009]
That is, it has a cross-section of the flow control structure that has a substantially wedge-shaped lower end constituted only by a curve having no linearity, and has an upwardly concave shape that is 0.3 to 2 times the creep deformation dimension generated at the lower end center portion. This realizes a sheet glass forming apparatus that is pressed and supported from both sides in the longitudinal direction. As a result, although improvements were made for a certain period of time, the improvements were not as good as initially expected. When adjusting the thickness of the glass sheet, the lower end of the flow rate control structure is curved from the beginning, so that restrictions such as the size of the glass sheet that can be formed occur. The improvement of surface waviness and the like has become a constraint to achieve higher surface dimensional accuracy. Furthermore, in addition to that, the production flow rate accompanying the increase in the size of the sheet glass has further increased, and as a result, the large amount of sheet glass with high dimensional accuracy can be produced over a long period of time only by the measures that have been taken so far. In some cases, the situation was inadequate.
[0010]
Therefore, we reviewed the overall structure and materials of the sheet glass forming apparatus and conducted various investigations on the more effective apparatus structure. The present inventor has proposed a fire-resistant glass sheet manufacturing apparatus and a manufacturing method using the apparatus, which can manufacture large-sized sheet glass for a longer period of time and satisfy various properties such as high-temperature heat resistance and high-temperature strength. And invented here.
[0011]
[Means for Solving the Problems]
That is, the plate glass forming apparatus of the present invention has a trough-shaped molten glass supply groove with an open top at the top, the tops of both side walls of the glass supply groove as overflow weirs, and the outer surfaces of both side walls have a substantially wedge-shaped cross section. A molten glass flow control structure is provided that is approached downward so that the molten glass flows continuously from one end of the glass supply groove, overflows from the top of both side walls, and flows down along the outer surfaces of both side walls. In the fire-resistant sheet glass manufacturing apparatus for forming a single glass sheet joined at the substantially wedge-shaped lower end, at least lower portions of the side surfaces at both ends in the longitudinal direction of the flow rate control structure are approached downward. The inclined surfaces are opposed to each other, and the opposed inclined surfaces are pressed and supported by respective supports toward the center from the sides.
[0012]
Here, the side surfaces at both ends in the longitudinal direction of the flow rate control structure are at least the lower surfaces thereof are opposed inclined surfaces approaching downward, and the opposed inclined surfaces are side-by-side by respective supports. The term “pressed and supported toward the center” means that the molten glass overflows and flows down, and the cross-section of the flow control structure has a substantially wedge shape. Part of the lower half is an inclined surface, which means that the inclined surface is continuously supported while being pressed from the side and from below.
[0013]
The phrase “a part of the lower half is an inclined surface” means that at least a part of the lower half of the side surface is an inclined surface. The inclined surface does not necessarily have to be a flat surface, and there is no problem even if it is a curved surface or a curved surface. However, the inclined surface is required to have a shape that can be continuously supported by being pressed from the side and below, that is, it must have a shape that can be supported, so that the flow control structure cannot be supported from below for a long period of time. It cannot be adopted if the shape is appropriate.
[0014]
Further, the inclined surface may have the same inclination angle on both side surfaces, or may have different inclination angles as needed. Further, the shapes of the inclined surfaces may be different from each other or may be the same. The material of the inclined surface is not particularly limited as long as it has a desired function.
[0015]
The magnitude of the inclination angle is preferably greater than 0 ° and less than 60 ° with respect to the vertical. More preferably, the angle is set to 45 ° or less. If the angle is larger than 60 °, the width of the sheet glass that can be formed is smaller than the size of the main body of the apparatus. Also, it is necessary to perform fine adjustment when pressing from the side in the longitudinal direction of the flow rate adjusting structure. The pressure should be set to 45 ° or less so that the pressure can be easily adjusted and the glass can be stably formed. More preferably, this angle is greater than 0 ° and less than or equal to 35 °. However, as the angle approaches 0 °, it becomes necessary to further increase the pressure value applied from the longitudinal direction, so that the structural strength and the life of the material constituting the flow rate control structure, and the heat resistance, etc. There is a need to select a shape.
[0016]
Further, the height of the inclined surface portion with respect to the height of the entire side surface portion in the longitudinal direction of the flow control structure needs to be in a range of 10% or more. If this value is lower than 10%, the force cannot be applied to the flow regulating structure. That is, as a result of applying a strong stress only to the lower end portion of the flow control structure, the possibility of occurrence of breakage or defects such as peeling or cracking of the lower end portion increases. And this value is more preferably 15% or more.
[0017]
Further, in the sheet glass forming apparatus of the present invention, in addition to the above, the density of the flow control structure is 3 g / cm 3. ³ Above, and Young's modulus is 9.8 × 10 ¹⁰ It is not less than Pa.
[0018]
Here, the density of the flow control structure is 3.0 g / cm. ³ Above, and Young's modulus is 9.8 × 10 ¹⁰ When it is Pa or more, the density of the material constituting the flow control structure is 3.0 or more, and this material has a Young's modulus of 9.8 × 10 ¹⁰ It means that it is necessary to have a property of Pa or more.
[0019]
Here, the flow control structure does not necessarily have to be a single constituent material, and may be made of a plurality of constituent materials. When the flow control structure is composed of two or more kinds of constituent materials, the flow control structure is intended for a structural material constituting 50% or more of a longitudinal central cross-sectional area of the flow control structure. In the case where the lower end central portion of the flow control structure is formed of two or more types of materials, it is sufficient that the value of the arithmetic average value of each constituent material satisfies the above-described values of density and Young's modulus.
[0020]
And, the density of the flow control structure means the bulk density of the material constituting the structure, and the higher the bulk density, the fewer structural defects and the like, and as a result, in a long-term high temperature state It can be a flow rate control structure that can withstand the use of. Therefore, the density of the flow control structure is at least 3.0 g / cm. ³ Or more, more preferably 3.4 g / cm ³ That is all. Further, when the flow control structure is used at a high temperature of 1500 ° C. or more, 3.6 g / cm ³ It is better to be 3.8 g / cm or more in order to more reliably maintain stable strength and the like. ³ It is preferable that it is above. However, if the density of the flow rate control structure is too large, its own weight becomes heavy, and it may become difficult to support the structure. ³ Should be:
[0021]
Furthermore, the Young's modulus of the flow control structure is a coefficient of longitudinal elasticity of the material constituting the structure, similarly to the density, that is, a coefficient representing the degree of material deformation in the direction perpendicular to the direction in which the stress is applied. The larger the value is, the smaller the amount of deformation of the material corresponding to the same stress is applied. As for the flow rate control structure, the smaller the value of the Young's modulus, the higher the rate at which the amount of distortion generated in the structure by the glass flow rate increases, and it becomes difficult to smoothly adjust the thickness of the sheet glass to be formed. In some cases, the alignment with the lower end holding member of the structure may be impaired, which may shorten the life of the flow control structure itself. Therefore, the larger the Young's modulus of the flow regulating structure, the better.
[0022]
Therefore, the Young's modulus of this flow control structure is at least 9.8 × 10 ¹⁰ It is better to be Pa or more, more preferably 10.8 × 10 ¹⁰ It is better that the material has Pa or more. Then, the flow control structure is continuously maintained in a temperature range of 1000 ° C. or more for 6 months or more, and has a density of 2.3 g / cm 3. ³ When used to form the above molten glass, the flow control structure is 11.8 × 10 ¹⁰ It is better to have a Young's modulus of Pa or more, more preferably 12.7 × 10 ¹⁰ It is better to be Pa or more.
[0023]
Further, as the material used for the flow rate control structure of the present invention, depending on the glass material to be melted, a plurality of materials can be appropriately selected as needed. Such a material is not particularly limited as long as it satisfies the desired properties, but specific examples include, as fired refractories, silica refractories, clay refractories, high alumina refractories, and silicon carbide. Refractories, chrome refractories, magnesia refractories, dolomite refractories, sillimanite refractories, cyanide alumina refractories, mullite refractories, zirconia refractories, alundum refractories, unfired refractories Brick, silicon carbide graphite refractories, high alumina refractories, castable refractories, plastic refractories, refractory mortars, etc. can be used as refractories, fused quartz refractories, various fiber boards, irregular types Refractory fiber materials and heat-resistant noble metals such as platinum can also be used by selecting the place of use, and a plurality of materials can be used in combination.
[0024]
Further, the sheet glass forming apparatus of the present invention is characterized in that, in addition to the contents described above, the longitudinal dimension of the flow rate control structure is 2.0 m or more.
[0025]
Here, the dimension in the longitudinal direction of the flow control structure is 2.0 m or more when the length in the longitudinal direction of the flow control structure forming a part of the sheet glass forming apparatus of the present invention is 2.0 m or more. It means there is. Here, the length in the longitudinal direction refers to the length of only the flow control structure. In other words, it does not include the glass supply pipe portion, but means the length from the joint of the glass supply groove and the glass supply pipe to the end face on the opposite side.
[0026]
The sheet glass forming apparatus of the present invention is an apparatus for producing a large sheet glass as described above. Specifically, the sheet glass has a thickness of 0.5 to 1.5 mm, and the sheet glass has a width of 2 to 4 m. And a density of 2.2 to 2.6 g / cm ³ Considering the strength and the aging durability of the flow control structure required to overflow and mold the glass sheet, the width dimension of the glass supply groove of the flow control structure, that is, the thickness It is preferable that the length in the longitudinal direction is not more than 18 times the corresponding length.
[0027]
In other words, if the length in the longitudinal direction is more than 18 times the length corresponding to the thickness of the flow rate control structure, the structure itself is likely to bend in the longitudinal direction, resulting in a long term of 6 months or more. It is more likely that production will be difficult to achieve. The ratio of the length in the longitudinal direction to the length corresponding to the thickness of the flow control structure is determined by fixing the length and fixing the length in the longitudinal direction when the length is increased. In both cases where the thickness is reduced and when both the thickness and the longitudinal length are changed, the ratio of the longitudinal length to the length corresponding to the thickness of the flow control structure is 18%. It is preferably at most twice. Furthermore, in order for the flow control structure to be able to maintain a more stable strength over a long period, it is preferable that the length in the longitudinal direction is 16 times or less the length corresponding to the thickness of the flow control structure. Good.
[0028]
Further, the method for forming a glass sheet of the present invention has a trough-shaped molten glass supply groove with an open top at the top, the tops of both side walls of the glass supply groove as overflow weirs, and the outer surfaces of both side walls have a substantially cross-section. A molten glass flow rate control structure that is approached downward so as to form a wedge is provided, and molten glass is continuously supplied from one end of a glass supply groove to overflow from both side wall tops, and along the outer surfaces of both side walls. In a sheet glass forming method of forming a glass sheet by using a fire-resistant glass sheet manufacturing apparatus for forming a single glass sheet that is caused to flow down and merge at a substantially wedge-shaped lower end, the flow rate control structure has two ends in the longitudinal direction. A certain side surface, at least a lower part of which is an opposed inclined surface approaching downward, and a plate formed by pressing the opposed inclined surface toward the center by each support from the side toward the center. Using the lath forming device, characterized in that shaping the glass plate.
[0029]
Here, the side surfaces at both ends in the longitudinal direction of the flow rate control structure are at least lower portions of the inclined surfaces facing each other approaching downward, and the opposed inclined surfaces are laterally supported by each support. Forming a glass sheet using a sheet glass forming apparatus that is pressed and supported toward the center is a position that supports both the flow control structure that forms the molten glass into the sheet glass and the molten glass that flows into the flow control structure. Is a portion including at least a part of the lower half of the two side surfaces located on the longitudinal direction side of the flow control structure, and the molten glass is continuously supplied from one end of the glass supply groove in a state where the two portions are supported. This means that it is a forming method in which the glass sheet is supplied, overflows from the tops of both side walls, flows down along the outer surfaces of both side walls, and forms one glass plate joined at the substantially wedge-shaped lower end.
[0030]
Further, the glass material to which the present invention can be applied is not particularly limited, but preferred examples thereof include a plate glass used for an information display such as LCD, PDP, and FED, and a solid material such as CCD and CMOS. Flat glass used as a cover glass for imaging devices, flat glass used as a window for laser diodes, flat glass used for optical filters, flat glass for recording information on magnetic disks such as hard disks and optical disks, substrate glass for sensors, thin-film solar cells It can be used as an apparatus for manufacturing a flat glass such as a substrate glass for which high surface precision is required.
[0031]
[Action]
As described above, the sheet glass forming apparatus of the present invention has a trough-shaped molten glass supply groove with an open top at the top, the top of both side walls of the glass supply groove as an overflow weir, and the outer surface of both side walls has a cross section. A molten glass flow rate control structure is provided which is approached downward so as to be substantially wedge-shaped, and the molten glass is continuously supplied from one end of the glass supply groove to overflow from both side wall tops, and to extend along both side wall outer surfaces. In a refractory sheet glass manufacturing apparatus for forming a single glass sheet joined at the lower end of a substantially wedge-shaped shape, at least lower portions of the side surfaces at both ends in the longitudinal direction of the flow rate control structure approach downward. Because the opposed inclined surfaces are pressed and supported toward the center by the respective support members from the sides, the center of the lowermost end of the flow control structure is deformed. Without cracking or, it is capable of performing the production of thin glass having a long-term stable dimensional quality at a high temperature.
[0032]
Further, in the sheet glass forming apparatus of the present invention, the flow rate control structure has a density of 3 g / cm. ³ Above, and Young's modulus is 9.8 × 10 ¹⁰ Since it is Pa or more, it satisfies the basic structural characteristics that enable continuous production of thin glass with high dimensional accuracy while flowing down the molten glass for a long time.
[0033]
In addition, in the sheet glass forming apparatus of the present invention, since the longitudinal dimension of the flow rate control structure is 2.0 m or more, a large thin sheet glass can be efficiently formed without impairing the surface quality due to uneven thickness or surface undulation. This enables high-speed production.
[0034]
Further, the method for producing a sheet glass of the present invention has a trough-shaped molten glass supply groove with an open top at the top, the tops of both side walls of the glass supply groove are overflow weirs, and the outer surfaces of both side walls have a substantially cross-sectional shape. A molten glass flow rate control structure that is approached downward so as to form a wedge is provided, and molten glass is continuously supplied from one end of a glass supply groove to overflow from both side wall tops, and along the outer surfaces of both side walls. In a sheet glass forming method of forming a glass sheet by using a fire-resistant glass sheet manufacturing apparatus for forming a single glass sheet that is caused to flow down and merge at a substantially wedge-shaped lower end, the flow rate control structure has two ends in the longitudinal direction. A certain side surface has at least a lower portion formed as an opposed inclined surface approaching downward, and the opposed inclined surface is pressed and supported toward the center by each support from the side. It is not necessary to change the temperature conditions, etc. to maintain the dimensional accuracy of the sheet glass, and to expand and supplement the facilities and equipment, thereby improving the yield rate of sheet glass with high accuracy dimensions. It is a possible and efficient molding method.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an example of the actual form of the sheet glass manufacturing apparatus of the present invention will be described below.
[0036]
(Embodiment 1) FIG. 1 is a plan view of a flow control structure 10 which is a sheet glass forming apparatus of the present invention. The molten glass homogenized by a feeder or the like of a glass melting furnace flows from the molten glass supply pipe 11 into the glass supply groove 12 of the flow rate control structure 10. Then, the molten glass overflowing from the tops on both sides of the glass supply groove 12 flows down along both side surfaces 13 of the flow control structure 10 and joins at the lower end 18 of the flow control structure 10 to form one sheet of glass. Molded. The flow control structure 10 of the present invention is supported by the trapezoidal members 14 from the inclined surfaces 10a and 10b at both ends in the longitudinal direction, and the trapezoidal members 14 are interposed in the longitudinal direction through the heat-resistant plate members 15. One side is held by a pawl member 16 and the other side in the longitudinal direction is pressed and supported by a pressurizing device 17 such as an air cylinder.
[0037]
The pressurizing device 17 withstands the load caused by the weight of the flow control structure 10 itself and the molten glass, and corrects, based on the measurement, fluctuations caused by displacement of the flow control structure 10 due to minute creep and expansion due to temperature conditions. The heat-resistant plate member 15 is designed so as to be capable of being heat-resistant, but is not particularly limited as long as it is heat-resistant. Here, a plate made of a heat-resistant metal material is used.
[0038]
In addition, the angle α of the inclined surfaces 10a, 10b of the flow control structure 10, which is in contact with the trapezoidal member 14 supporting the both end inclined surfaces 10a, 10b in the longitudinal direction of the flow control structure 10, is perpendicular to the vertical. There is no problem if it is larger than 0 ° and 45 ° or less, but here it is 16 ° with respect to the vertical. The height of the inclined surfaces 10a and 10b with respect to the height of the entire side surface portion in the longitudinal direction of the flow rate control structure 10 does not cause any problem as long as it is in a range of 10% or more, but is 60% here.
[0039]
(Embodiment 2) Next, an investigation conducted by the inventor using a model device will be described. In the investigation conducted here, the effect was confirmed by changing the shape such as the inclination angle α of the inclined surfaces on both sides in the longitudinal direction of the flow control structure. That is, made of zircon refractory (density 4.0 g / cm ³ , Young's modulus 14.2 × 10 ¹⁰ A shape model of 1/10 size of the sheet glass forming apparatus of Pa) is manufactured and held for 8 months in an air atmosphere at a high temperature of 1200 ° C., and no abnormality such as deformation from the initial shape is observed. A comparative survey was conducted on the The result will be described with reference to FIG. The four types of flow control structures 10 shown in FIGS. 2A to 2D were used for the test, and FIG. 2A shows the flow control structure 10 of the present invention, in which the flow control structure 10 was used. The inclination angle α of the longitudinally inclined surfaces 10a and 10b is 18 °. (B) is also a flow control structure 10 of the present invention, in which the inclination angle α of the inclined surfaces 10a and 10b on both sides in the longitudinal direction of the flow control structure 10 is set to 54 ° which is larger than 45 °. (C) investigated as a comparative example is one in which the inclination angle α of both sides in the longitudinal direction of this flow control structure is set to 0 °. Further, with respect to (D) of the comparative example, the inclination angle α of both sides in the longitudinal direction of the flow control structure is 18 ° as in (A), but the height H of the entire side surface in the longitudinal direction of the flow control structure is increased. The height L of this inclined surface with respect to is 8.2%.
[0040]
In the investigation, a refractory of 500 kg was placed on top of the flow control structure using an indirectly heated electric resistance furnace, and was held in a state where the load was also applied from the longitudinal direction of the structure while continuously applying a load. By examining the changes observed, it was assessed whether it had a sufficient function with respect to long-term durability. As a result, regarding the sample (A), the shape and appearance of the flow control structure taken out of the electric furnace after 8 months were examined, and it was found that no problem was observed.
[0041]
On the other hand, although the sample (B) is a sample in which the inclination angle α is larger than 45 °, when the sample is taken out of the electric furnace, a state in which one of the longitudinal directions of the flow rate control structure 10 slightly rises from the initially set position. The weak point is that if this shape is adopted in actual production, there is a high possibility that problems such as the need to take detailed measures such as adjusting the pressing force from the longitudinal direction over time will occur are high. Was done. Therefore, it has been found that the sample (B) can be adopted as the present invention, but more preferably, the inclination angle α should be set to 45 ° or less like the sample (A). The sample (C) is a sample having an inclination angle α of 0 °, but after eight months, the inspection at the lower end 18 of the flow rate control structure 10 showed a distortion, indicating that the sample was used for a long time. It was confirmed that it was unbearable. Further, as for the sample (C), cracks were observed on the side surface of the flow rate control structure 10 by observing the sample after 8 months. From this, since the height L of this inclined surface is 8.2% and less than 10% with respect to the height H of the entire lengthwise side portion of the flow control structure, structurally excessive load is applied. As a result, it was presumed that the crack C was formed by the shear stress acting on the zircon refractory constituting the flow control structure in the lateral direction.
[0042]
As described above, the flow rate control structure of the present invention can withstand the storage conditions for 8 months, but the other samples (C) and (D) are unreasonable structures. Was confirmed.
[0043]
(Example 3) Based on the above results, the evaluation of the structure in an actual melting furnace and the performance evaluation of the formed thin glass were further performed. In this investigation, thin glass of alkali-free glass was formed using molten glass melted in an actual melting chamber, and a comparative investigation on its performance was carried out. In the investigation, the flow rate control structure 10 having a structure as shown in FIG. 2A was employed, and a sheet glass was formed on a trial basis for about 12 months.
[0044]
As a result, by using the flat glass forming apparatus of the present invention including the flow rate adjusting structure 10, it is possible to realize the forming of the thin glass with no hindrance to the dimensional accuracy such as undulation and uneven thickness for about 12 months. The non-defective rate during this test period was improved by 3% from the conventional rate.
[0045]
Further, when the properties and dimensions of the lower end portion of the apparatus were investigated for the flow rate control structure 10 after the production of the sheet glass, the central position of the lower end section 18 of the apparatus was creep-deformed 0.1 mm below the original dimensions. There were no abnormalities such as cracks. On the other hand, when using a sheet glass forming apparatus having a conventional shape, when the sheet glass is manufactured under the same conditions, the center position of the lower end of the apparatus has a deformation amount of 15 to 20 mm. The problem of increasing the size was recognized, and cracks also occurred at the tip of the lower end. As described above, it has been found that by adopting the sheet glass manufacturing apparatus of the present invention and performing the shaping, the sheet glass forming quality is improved, and it becomes possible to manufacture sheet glass having stable dimensional accuracy over a long period of time.
[0046]
【The invention's effect】
As described above, the flat glass forming apparatus of the present invention can produce thin glass having stable dimensional quality for a long period of time at a high temperature without deforming or breaking the center of the lowermost end of the flow control structure. It is possible to reliably form large-sized thin glass corresponding to large-sized display devices, and to market flat glass with high-precision surfaces that can be mounted on high-performance display devices. Supplying abundantly will greatly contribute to the further development of the information industry.
[0047]
Furthermore, since the sheet glass forming apparatus of the present invention satisfies the basic structural characteristics that enable continuous production of thin sheet glass with high dimensional accuracy while flowing down molten glass for a long time, In addition, it is a device suitable for producing high-quality thin glass having high chemical durability and the like, and in which structural defects and the like are not allowed. The thin glass manufactured by this device has a wide range of applications. It will be possible to pioneer.
[0048]
Further, the sheet glass forming apparatus of the present invention is capable of efficiently producing large-sized thin glass at high speed without deteriorating the surface quality due to uneven thickness or surface waviness, etc. By reducing the production cost of thin glass for display devices and realizing the necessary quantity of thin glass, it is possible to supply thin glass to fields that require thin glass for large display devices without delay. is there.
[0049]
In addition, the method for forming a glass sheet of the present invention includes a method of changing temperature conditions and the like, and expanding and augmenting additional equipment and devices to maintain dimensional accuracy of the glass sheet in response to creep deformation of the flow control structure. This is an efficient molding method that can improve the yield rate of sheet glass with high precision dimensions because it does not need to be dealt with, so alkali-free used in display device applications that require advanced performance such as surface precision It is particularly preferable as a method for forming a glass plate for liquid crystal using glass or the like.
[Brief description of the drawings]
FIG. 1 is a partial plan view of a flow control structure for a sheet glass forming apparatus of the present invention.
FIGS. 2A and 2B are explanatory views of a flow rate control structure of the sheet glass forming apparatus, wherein FIGS. 2A and 2B are plan views showing examples of the present invention, and FIGS. 2C and 2D are comparative examples of the present invention. FIG.
FIG. 3 is a perspective view of a conventional sheet glass forming apparatus.
FIG. 4 is a plan view of a conventional sheet glass forming apparatus.
[Explanation of symbols]
10 Flow control structure of glass sheet forming apparatus of the present invention
10a, 10b slope
11 Molten glass supply pipe
12 Glass supply groove of flow control structure
13 Side surface of flow control structure
14 Trapezoidal support members for flow control structures
15 Heat resistant plate members
16 Heat resistant pawl material
17 Pressurizing device
18, 23 Lower end of flow control structure
24 support base
25 Through hole
α Angle of inclination of the inclined surface on the longitudinal side of the flow control structure with respect to the vertical
H Height of flow control structure
L Height of the inclined side surface in the longitudinal direction of the flow control structure
C crack
G sheet glass

Claims (4)

A trough-shaped molten glass supply groove with an open top is provided at the top, the tops of both side walls of the glass supply groove are overflow weirs, and the outer surfaces of both side walls are approached downward so as to have a substantially wedge-shaped cross section. A molten glass flow control structure, the molten glass is continuously supplied from one end of the glass supply groove, overflows from the tops of the side walls, flows down along the outer surfaces of the side walls, and merges at a substantially wedge-shaped lower end. In a fire-resistant sheet glass manufacturing apparatus for forming a glass sheet,
The side surfaces at both ends in the longitudinal direction of the flow rate control structure are at least inclined surfaces facing each other with the lower portion approaching downward, and the opposed inclined surfaces are centered by the respective supports from the side. A sheet glass forming apparatus characterized by being pressed and supported toward each other. 2. The apparatus according to claim 1, wherein the flow rate control structure has a density of 3 g / cm ³ or more and a Young's modulus of 9.8 × 10 ¹⁰ Pa or more. 3. 3. The sheet glass forming apparatus according to claim 1, wherein the flow control structure has a longitudinal dimension of 2.0 m or more. A trough-shaped molten glass supply groove with an open top is provided at the top, the tops of both side walls of the glass supply groove are overflow weirs, and the outer surfaces of both side walls are approached downward so as to have a substantially wedge-shaped cross section. A molten glass flow control structure, the molten glass is continuously supplied from one end of the glass supply groove, overflows from the tops of the side walls, flows down along the outer surfaces of the side walls, and merges at a substantially wedge-shaped lower end. In a sheet glass forming method for forming a glass sheet using a fire-resistant glass sheet manufacturing apparatus for forming a glass sheet,
Both side surfaces in the longitudinal direction of the flow rate control structure have at least a lower portion formed as opposed inclined surfaces approaching downward, and the opposed inclined surfaces are directed toward the center from the sides by the respective supports. A method for forming a glass sheet, wherein a glass sheet is formed by using a glass sheet forming apparatus each of which is pressed and supported.

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