JP4743665B2 - Sheet glass forming apparatus and sheet glass forming method - Google Patents

Description

  The present invention relates to a sheet glass forming apparatus, and more particularly to an overflow downdraw type sheet glass forming apparatus suitable for forming a sheet glass mounted on a liquid crystal display device.

  Various methods, such as a down draw method, a lead draw method, or a float method, are known as a method for forming a plate glass mounted on various image display devices. Among them, there is an overflow down draw method as a method for realizing high production efficiency. In general, an apparatus for forming a sheet glass by the overflow down draw method has a configuration as shown in FIGS. As shown in this figure, the overflow downdraw method sheet glass forming apparatus has a glass supply groove 1a in the shape of a bowl having an open top surface at the top. Then, the forming apparatus uses the two upper tops corresponding to the end walls of the glass supply groove 1a as the overflow weirs 1b of the molten glass G, and the two outer surfaces 1c of both side walls approach each other downward. The molded body 1 has an appearance similar to that of a cutting edge having a substantially wedge shape, and is terminated at the lower end 1d. The molten glass G is continuously supplied from the one end side of the glass supply groove 1a to the glass supply groove 1a by the molten glass supply pipe 2. Then, the molten glass G temporarily staying in the glass supply groove 1a overflows from the two ridge lines 1e at the top of the both side walls, and further has two outer surfaces having a substantially wedge shape sandwiched between the guides 1f on the both side walls. Since each of them flows down 1c and joins at the lower end 1d, the glass sheet P can be formed by stretching it downward. The plate glass P thus obtained has high smoothness because the surface thereof is in a state corresponding to a free melting surface at the time of melting, and as shown in FIG. 4C, the central region Pα and both end portions Pβ The thickness becomes a substantially uniform shape.

  The molded body 1 is configured so that the side wall top ridge lines 1e of the glass supply groove 1a are substantially linear over the entire length, and the molten glass G overflows evenly. However, this type of molded body 1 needs to be configured using a refractory having high corrosion resistance against the molten glass G in a high temperature state. For this reason, the molded body 1 is increased in weight, and is disposed so that only both ends of the molded body 1 are supported by the supporting refractory 3, and is continuously exposed to high temperature conditions for a long time during production. Therefore, while the molding apparatus is operated for a long time, a phenomenon occurs in which the gravity F gradually bends and deforms with time due to gravity F. This deformation phenomenon is generally referred to as creep deformation (or simply creep). In order to obtain a sheet glass product having a large area and a large sheet width (for example, 1000 × 1500 mm), a sheet glass P having a large effective width is formed. In such a case, it is necessary to increase the longitudinal dimension of the molded body 1 (for example, 1800 mm or more), and the amount of creep deformation tends to be further increased. For example, FIGS. 5A and 5B show the molded body 1 that has undergone creep deformation by operating the molding apparatus for a long time. When the molded body 1 undergoes creep deformation, both side walls of the glass supply groove 1a are shown. The top ridge line 1e also bends downward to form a large arcuate curved shape having a convex shape downward, and the overflow amount of the molten glass G overflowing from the ridge line 1e is large in the central region 1g in the longitudinal direction of the molded body 1, It decreases in both end regions 1h. As a result, as shown in FIG. 5C, the molded glass sheet P has a shape in which the thickness of the central portion Pα is thick, the thickness of the peripheral portion Pβ is thin, and the thickness is not uniform. .

  By the way, the plate glass used as a substrate mounted on a liquid crystal display or the like currently has a plate thickness dimension of 0.7 mm, but the required quality of the user for the plate thickness dimension accuracy is very strict. The accuracy is 0.7 ± 0.01 mm. For this reason, when the molded body 1 undergoes creep deformation as described above, the thickness of the plate glass P tends to be non-uniform, and as a result, the production yield at the time of forming the plate glass is significantly reduced.

  Therefore, as a method for solving such a problem, when the glass sheet P requiring such high accuracy is formed, the vicinity of the both end regions 1h of the molten glass is heated or cooled in the vicinity of the lower end 1d of the molded body 1. A method has been adopted, and adjustments have been made so that the thickness of the plate glass P becomes uniform. However, about the adjustment operation of the plate thickness of the plate glass P, not only the adjustment of such heating and cooling can not be sufficiently controlled, but when the molten glass flows down the outer surfaces 1c of the both side walls of the molded body 1, The flow becomes uneven, and as a result, the thickness of the peripheral portion Pβ of the plate glass P is likely to fluctuate. In an extreme case, the molten glass is molded without being sufficiently fused at the peripheral portion Pβ. As a result, there is a problem that the plate glass P is frequently cracked.

Under these circumstances, in Patent Document 1, a through-hole is formed in the length direction of the molded body 1 and a supporting member is inserted into the through-hole, thereby forming a sheet glass molding apparatus that suppresses creep deformation of the molded body 1. was suggested. Further, Patent Document 2 discloses an invention that makes creep deformation difficult by setting the ratio of the total length and height of the molded body 1 within a predetermined range. Furthermore, in patent document 3, the overflow amount of molten glass is easily adjusted by forming the top ridge lines of both side walls of the overflow weir in advance so as to bend downward in the start end region and / or end region in the flow direction of the molten glass. An invention that could be done was also disclosed.
JP-A-11-246230 JP 2004-315286 A JP 2004-315287 A

  However, the inventions made so far are not sufficient. For example, to obtain a thin plate with a larger area in a highly homogeneous state, or to increase the manufacturing index from the viewpoint of improving manufacturing efficiency, it can withstand the load of mass production by realizing a higher glass forming speed. However, there is a problem that technical accumulation for producing a large area of thin glass with high homogeneity is not sufficient, and it is impossible to meet various requirements.

  The present inventor, as a plate glass manufacturing apparatus capable of mass production over a long period of time without impairing the molding quality of a large area of sheet glass for such a situation, a plate glass molding apparatus Sheet glass forming equipment that can improve the forming ability of glass plates and maintain stable plate thickness forming dimensions over a long period of time, especially overflow down draw method suitable for forming plate glass mounted on liquid crystal display devices It is an object of the present invention to provide a sheet glass forming apparatus and a sheet glass forming method using the sheet glass forming apparatus.

That is, the sheet glass forming apparatus of the present invention has a bowl-shaped molten glass supply groove having an opening at the top, the tops of both side walls of the glass supply groove are used as overflow weirs, and the outer surface portions of both side walls are cross-sectioned. The outer surface of both side walls are made to approach each other downward so that the outer surfaces of the both side walls are close to each other so as to be substantially wedge-shaped and have a hollow portion in a cross section perpendicular to the longitudinal direction of the molded body. A sheet glass forming apparatus that continuously supplies from one end of the glass supply groove, overflows from the top ridge line of both side walls, flows down along the outer surface of both side walls, and joins at a substantially wedge-shaped lower end to form a sheet glass. For the unit cross-sectional portion whose thickness is the unit length in the scale direction, the section modulus Zh of the molded body having a cavity in the cross section, the molded body mass Wh of the unit cross-section having a cavity in the cross section, and the molding before forming the cavity in the cross section Body break Coefficient Z0, and the molded mass W0 of the unit cross section of the front cavity formed in cross section, have a unit cross section become (Wh / W0) <(Zh / Z0), (Wh / W0) <(Zh / unit cross section which becomes Z0), characterized in that to have a 30% or more the length of the molded body length longitudinal direction

Here, there is a bowl-shaped molten glass supply groove having an opening at the top, the tops of both side walls of the glass supply groove are used as overflow weirs, and the outer surface of both side walls are arranged on both sides so that the cross section is substantially wedge-shaped. It has a molded body with the outer surfaces of the walls facing each other downward and terminated at the lower end, and has a cavity in a cross section perpendicular to the longitudinal direction of the molded body, and the molten glass is continuously formed from one end of the glass supply groove. Is a sheet glass forming apparatus for forming a sheet glass by causing it to overflow from the top ridge lines of both side walls, flow down along the outer surface of both side walls, and merge at a substantially wedge-shaped lower end, wherein the unit length in the longitudinal direction of the formed body is the thickness. For the unit cross section, the section modulus Zh of the molded body having the cavity in the cross section, the molded body mass Wh of the unit cross section having the cavity in the cross section, the section modulus Z0 of the molded body before forming the cavity in the cross section, Before forming the cavity Position and the molding mass W0 of the cross section, (Wh / W0) <have a (Zh / Z0) become unit cross section, is to become a unit cross section (Wh / W0) <(Zh / Z0), molding Having a length dimension of 30% or more in the body length direction is as follows. That is, by using a long shaped molded body having a substantially wedge-shaped cross-section configured such that the molten glass overflows the top of both upper end walls and flows down along the outer surface portions of both side walls. A unit perpendicular to the longitudinal direction of the molded body having a unit length as a thickness with respect to the longitudinal direction of the molded body perpendicular to the outer surface of the both side walls where the molten glass flows down with respect to the molded body configured to mold the sheet glass below the body. For the cross section, the mass corresponding to the unit cross section of the molded body before and after forming the cavity in the cross section is W0, Wh, and the section modulus of the unit cross section of the molded body before and after forming the cavity in the cross section of the molded body is If Z0 and Zh are set, the ratio of the mass of the unit cross section after forming the cavity in the cross section perpendicular to the longitudinal direction of the molded body, compared to before forming the cavity in the cross section perpendicular to the longitudinal direction of the molded body In the unit cross section It represents that there is a small unit cross section than the ratio of the section modulus after formation on section modulus of the front of the molded body to form a cavity in the cross section perpendicular to the molding body length longitudinal direction of are. A unit cross-sectional portion satisfying (Wh / W0) <(Zh / Z0) has a length dimension of 30% or more in the longitudinal direction of the molded body. Here, what is called a unit cross section may be any thickness dimension that is sufficiently short relative to the entire length of the molded body, for example, 0.1 mm, 1 mm, 1 cm, 2 cm, 3 cm, 5 cm, or 10 cm. Is preferred.

  The mass of the unit cross-section before forming the cavity is filled with the same density of structural material having the same composition as the material of the unit cross-section constituting the molded body in the cavity after the formation of the cavity. Is calculated by numerical calculation. Here, the filling state of the surface of the molded body in the hollow portion can be calculated by filling the surface of the hollow portion with a flat surface even in the case of an open-type hollow portion. It is. The section modulus is calculated according to the same interpretation. Therefore, when the calculation for the cavity is performed, the calculation based on the fact that the other material is filled before the cavity is formed is not performed. However, if any coating material or filling material is filled after the cavity is formed, it affects the mass and section modulus after the cavity is formed. It is necessary to perform calculations that take into account.

  The number of cavities in the molded body according to the present invention is not necessarily one, but a plurality of cavities may be provided if it is preferable to distribute the cavities evenly in terms of weight balance and the like. The hollow portion may have any cross-sectional shape, but it is preferable to avoid a shape having an acute angle portion that causes local stress concentration. Moreover, the cross-sectional shape perpendicular to the long direction of the formed body of the hollow portion may be one in which the cross-sectional area continuously changes from the surface of the formed body to the depth direction, or the cross-sectional shape continuously changes. In addition, if processing is possible, the discontinuous cross-sectional shape is not prevented at all. In addition, surface processing that intentionally changes the surface area of the inner surface of the cavity, such as blasting, corrosion processing with a specific agent such as acid, alkali, and cutting, can also be performed. It is also possible to coat a heat-resistant ceramic coat, platinum or other platinum group noble metal foil. In addition, by applying a coating resistant to a specific medium in the cavity, it is possible to take a measure so that the inner surface of the cavity does not deteriorate over time.

  As a method of forming the cavity, it can be formed by cutting the fired product when producing a molded body, or by creating a mold that becomes a cavity at the time of casting by previously casting a location that becomes a cavity. it can. Similarly, even in cast molding, a cavity processing portion is formed with a fragile material that is easier to cut so that it does not become a cavity at the beginning, so that cutting after firing is facilitated. Treatment can also be performed. Moreover, the part which forms a cavity part is comprised with the material weak with respect to a chemical | medical agent chemically, and can also be removed by chemical | medical agent processing. Furthermore, it is also possible to previously form a portion where the cavity is formed with an organic material or the like that can be burned off during firing.

  Moreover, about the cavity part of the molded object which concerns on this invention, the cavity part completely closed | closed may be sufficient even if it is an open state cavity part. As a method of constructing the closed cavity, it can be realized by forming the open cavity once and then closing it by refilling the open end of the cavity with the same material as the molded body or another material. it can. Alternatively, a plurality of partial molded bodies are individually formed in advance, and after forming a hollow portion in the partial molded body, each partial molded body is joined, heated, fired, and sintered by a procedure such as sintering. It is also possible to provide a hollow portion. Here, the hollow portion in the open state corresponds to a hole, a groove, a location where a local depression is formed, or the like. About the depth of a hole, a groove | channel, and a local hollow, the thing which turns out that the hole, the groove | channel, and the hollow were formed intentionally from the external shape of the well-known plate glass shaping | molding apparatus is meant.

  Various methods can be used as a method of forming the hole, groove, or depression. For example, in the method of forming holes, holes having a predetermined shape can be formed before firing, and holes, grooves, and depressions may be formed after firing. If the holes are formed after firing, means such as chemical erosion can be employed in addition to drilling. In addition, for example, for depressions, a mold or a press mold in which depressions are formed when various molding methods such as casting and press molding are adopted in advance, or a molded body formed by firing, sintering, casting, or the like. It can be formed by polishing and cutting the surface. Also, for example, for the groove, if a shape that forms a groove is adopted as a die shape when performing pultrusion molding or extrusion molding, and further, a roller shape at the time of rolling forming that forms a groove is adopted. Good. When forming holes, grooves, or dents after firing, use a molding method that makes it easy to identify the locations where holes, grooves, or dents are to be formed, or marks the depressions on the surface of the fired product in advance. May be.

  Further, the section modulus is uniquely determined by the shape of the cross section perpendicular to the longitudinal direction of the molded body, and specifically, the section 2 relating to the axis passing through the centroid of the cross section perpendicular to the longitudinal direction of the molded body. The section modulus is obtained by dividing the next moment by the maximum distance from the axis to the periphery of the section perpendicular to the longitudinal direction of the compact. The centroid is the position where the cross-sectional primary moment with respect to an arbitrary axis passing through one point becomes 0. The cross-sectional secondary moment subdivides the cross section perpendicular to the longitudinal direction of the compact into a small area, The value obtained by multiplying the square of the distance is added to the total cross-sectional area.

  It is clear that the weight of the molded body should be reduced in order to prevent the occurrence of creep that occurs at a high temperature for the molded body. The strength is weakened. In addition, reducing the section modulus decreases the strength, but even if the section coefficient is decreased, the unit section portion that satisfies the above-described condition of (Wh / W0) <(Zh / Z0). As long as there is, the present inventors have found that it is possible to realize high creep resistance in addition to weight reduction. That is, for a molded body having a unit thickness in the longitudinal direction of the molded body, if there is a portion formed such that the ratio of reduction in section modulus is smaller than the ratio of mass reduction by forming a cavity In other words, if the mass reduction is larger than the reduction of the section modulus, the durability of the molded body over time when kept at a high temperature, that is, the drooping of the central part of the molded body The deformation can be reduced.

  Further, in addition to the above, the sheet glass forming apparatus of the present invention has a unit cross-section of (Wh / W0) <(Zh / Z0) having a length dimension of 30% or more in the long direction of the formed body. This is preferable because the strength of the molded body can be further stabilized.

  Here, the unit cross-sectional portion satisfying (Wh / W0) <(Zh / Z0) has a length dimension of 30% or more in the long direction of the formed body, as described above, of the unit thickness in the long direction of the formed body. For the molded body, the portion formed such that the ratio of reduction in section modulus is smaller than the ratio of mass reduction by forming cavities is the length of the entire length in the longitudinal direction of the molded body. It means that the length is 30% or more.

  When the length is 30% or more, a greater effect can be realized for both weight reduction and creep resistance. Here, the length of 30% or more is not necessarily continuous, and there are discontinuous unit cross sections where (Wh / W0) <(Zh / Z0), that is, in a plurality of portions. It may exist in a separated state.

  Moreover, about this invention, about the unit cross-section part which satisfy | fills the conditions which have the relationship of said (Wh / W0) <(Zh / Z0), the elongate direction of a molded object perpendicular | vertical to the both-sides wall outer surface where molten glass flows down On the other hand, the length of the portion satisfying the relationship of (Wh / W0) <(Zh / Z0) is more preferably 40% or more so that the effect of the present invention is clearly exhibited.

  Further, the position of the unit cross-section portion satisfying the above condition (Wh / W0) <(Zh / Z0) with respect to the longitudinal direction of the molded body includes the position of the center of gravity of the molded body. Preferably, it is formed, and more preferably includes a position of the center of gravity, and further includes a portion having a dimension length of 10% or more in the longitudinal direction.

  In the sheet glass forming apparatus of the present invention, in addition to the above, the hollow portion is preferably formed by a hole in the formed body.

  Here, the fact that the hollow portion is due to the hole in the molded body corresponds to the case where the hollow portion in the above-described open state is constituted by the hole. Here, the hole is an opening having a depth larger from the surface of the molded body than the diameter of a circle having an area corresponding to the shape of the opening end of the opening as viewed from the surface of the molded body. The opening having a depth smaller than the radius of a circle having an area corresponding to the shape of the opening end of the opening viewed from the surface of the surface is a groove or a depression.

  The hollow portion of the molded body according to the present invention may be a through hole whose both ends are open or may be a closed hole where one end is not open, i.e., does not penetrate. There is no problem even if the shape is linear, curved or bent. In addition, the shape of the closed portion is not particularly limited with respect to the closed hole, but since the stress tends to concentrate on the closed portion when an external force is applied, it can sufficiently withstand even if there is stress concentration. It is preferable to have a configuration that can be used. That is, it is better to withstand the stress concentration with respect to the surface roughness and the overall shape of the inner surface of the closed portion.

  In addition to the above, the sheet glass forming apparatus of the present invention includes a range from 10% to 90% of the total length in the long direction of the formed body starting from one side of the formed body where the hollow portion supplies molten glass. It is preferable to form in this way.

  Here, when the cavity is formed so as to include a range from 10% to 90% with respect to the total length in the longitudinal direction of the molded body starting from one side of the molded body that supplies the molten glass, at least of the cavity The position means that if the total length in the longitudinal direction of the molded body is 100 when measuring from one side of the molded body as a starting point, the position is within the range of positions from 10 to 90 of them. Is.

  In order to make the present invention more effective, it is possible to reduce the weight of the center of the molded body when the cavity portion is closer to the center in the longitudinal direction of the molded body. Therefore, the above range is more preferably from 10% to 80%, more preferably from 20% to 80%, and even more preferably from 20% to 70%. It is to do.

  In addition to the above, the plate glass molding apparatus of the present invention is preferably filled with a heat-resistant material having a density lower than that of the molded body in the cavity.

  Here, filling the cavity with a heat-resistant material having a density lower than that of the molded body means that the cavity of the molded body is filled with a heat-resistant material having a mass per unit volume smaller than that of the material constituting the molded body. Represents. The density here does not represent the density at a high temperature at which the molded body is heated, but represents the density at room temperature, that is, 25 ° C. Measurement of the density at high temperature is not easy, and since the density at normal temperature is effective as a guide, the density at normal temperature is used in the present invention.

  If it is a material with a low density, it will not specifically limit about the form. That is, in addition to the lump, it may be in the form of powder, flakes, granules, fibers, paste, cloth or string. Moreover, it is not necessary to use one material, and a mixture of a plurality of materials may be used. For the mixture of a plurality of materials, the mixing method is not limited. Further, for filling, there is no need to completely fill, and a form having many voids may be used. Further, the filling method is not particularly limited. In addition, the word “filling” is used here, but it does not simply indicate a method that depends on the method of filling the material to be filled, but intentionally leaves a material different from the molded body in the cavity. Even if it is a form, it corresponds to the specific to-be-filled object which concerns on this invention.

  The density can be measured by a generally known method. For example, a method such as Archimedes method can be adopted.

  The heat-resistant material does not need to have the same heat resistance as the molded body, and does not need to have the high temperature resistance as the molded body. However, there is no problem as long as it does not cause a problem such as weakening the strength of the molded body by easily chemically reacting with the material constituting the molded body at a high temperature.

  In addition to the above, the plate glass forming apparatus of the present invention is preferably filled with a porous material in the cavity.

  Here, filling the hollow portion with a porous material means that the material filled in the hollow portion is a material having a large number of fine pores.

  As for the porous material, there is no problem if it is made of, for example, porous ceramics or a heat-resistant alloy material. The porosity of the porous material is not particularly limited. However, if it is a porous material, since it will have structural strength even in a high temperature state that is suitable for molding molten glass, it is preferable because the strength of the molded body can be stabilized. And the porous material here does not prevent the presence of a filler having another form.

  Further, the molded body according to the sheet glass forming apparatus of the present invention can be used in combination with other reinforcing methods employed to reinforce the sheet glass forming apparatus. It does not interfere with other effective means such as changes.

  As the refractory constituting the molded body to be mounted on the sheet glass molding apparatus of the present invention, a fired refractory excellent in heat resistance and high temperature strength, a non-fired refractory, an amorphous refractory, and the like are suitable. More specifically, silica refractories, clay refractories, high alumina refractories, silicon carbide refractories, chrome refractories, magnesia refractories, magnesia refractories, dolomite refractories, sillimanite refractories, Cyanide alumina refractories, mullite refractories, zirconia refractories, cordierite refractories, castable refractories, plastic refractories and the like can be used. In addition to these refractories, it is possible to use fused quartz refractories, synthetic quartz refractories, various fiber boards, and amorphous refractory fiber materials, and alloys containing platinum group elements as main components, such as platinum alloys. Heat-resistant noble metals such as can be used. 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.

  The plate glass forming method of the present invention is characterized in that a plate glass for mounting a liquid crystal display device is formed using the plate glass forming apparatus described above.

  Here, forming the plate glass for mounting a liquid crystal display device using the above-described plate glass forming apparatus is to employ the plate glass forming apparatus of the present invention as a forming method used in the step of forming the plate glass. By adopting these molding methods, it is meant to produce a plate glass for mounting a liquid crystal display device with good surface accuracy.

  The plate glass for mounting a liquid crystal display device represents, for example, a plate glass used as a substrate glass for a liquid crystal on which a thin film transistor (Thin Film Transistor, abbreviated TFT) is mounted. If it is a TFT system, it does not relate to the difference in members such as amorphous silicon and polysilicon.

  Any material can be used as the material for the plate glass formed in the present invention, but glass material such as borosilicate glass, non-alkali glass, and aluminosilicate glass or silicon is contained in an amount of 80% by mass or more. A high silicate glass material is suitable for forming by this apparatus. Borosilicate glass is an oxide glass mainly composed of boron and silicon, and alkali-free glass contains substantially no alkali metal element, that is, sodium, potassium, lithium, which are alkali metal elements in the glass composition. Such an element is a glass material with an oxide conversion of 0.1% by mass or less, and the aluminosilicate glass is an oxide glass material mainly composed of aluminum and silicon.

  In addition to the liquid crystal display device, the thin glass having the glass material as described above is, for example, a solid-state imaging device cover glass represented by CMOS or CCD, a field emission plate glass, a plasma display plate glass, an EL cover glass, It is suitable for use as glass for optical filters such as bandpass filters and glass for glass substrates for chip-on-glass applications.

  In addition, the sheet glass forming apparatus of the present invention has a large appearance having a width of 1500 mm or more and an arbitrary length dimension, and also forms a sheet glass having a thin shape with a sheet thickness dimension of 3.0 mm or less. Is preferred.

  The molded body mounted on the sheet glass forming apparatus of the present invention divides the outer shape of the virtual molded body mounted on the sheet glass forming apparatus and the shape dimension inside the cavity based on the virtual division number of the three-dimensional shape of the molded body. It has a subroutine program, configures a numerical calculation program using the compact dimensions and the mass of the compact constituent material as parameters, and calculates the compact dimensions based on the calculation of the section modulus and the divided mass by the program. Can be determined.

  Here, there is a subroutine program that divides the outer shape of the virtual molded body mounted on the plate glass molding apparatus and the shape dimension inside the cavity based on the virtual division number of the three-dimensional shape of the molded body. The numerical calculation program is configured using the mass of the body component material as a parameter, and the optimal molding size is calculated based on the section modulus and the result of calculation of the divided mass by the program. The molded shape is divided into cross-section portions having unit thickness dimensions, the cross-section modulus and mass for each unit cross-section portion are calculated, and the above-described predetermined relationship is established between the cross-section modulus and mass. This means that the optimum outer shape of the molded body is calculated.

(1) As described above, the sheet glass forming apparatus of the present invention has a bowl-shaped molten glass supply groove having an open top at the top, and the tops of both side walls of the glass supply groove serve as overflow weirs. The outer surface of the wall is provided with a molded body in which the outer surfaces of both side walls approach each other downwards so that the cross section is substantially wedge-shaped and is terminated at the lower end, and the cavity is formed in a cross section perpendicular to the longitudinal direction of the molded body. A glass sheet forming apparatus for continuously supplying molten glass from one end of the glass supply groove, overflowing from both side wall top ridge lines, flowing down along the outer surface of both side walls, and joining together at a substantially wedge-shaped lower end; And about the unit cross-section part whose thickness is the unit length in the long direction of the compact, the section modulus Zh of the compact having a cavity in the cross section, the compact mass Wh of the unit cross-section having a cavity in the cross section and the cross section Before forming the cavity Section modulus of features Z0, and the molded mass W0 of the unit cross section of the front cavity formed in cross section, have a unit cross section become (Wh / W0) <(Zh / Z0), (Wh / W0) < Since the unit cross-section portion (Zh / Z0) has a length dimension of 30% or more in the longitudinal direction of the molded body, it is exposed to a high temperature necessary for molding molten glass into a sheet glass for a long time. Even if it exists, it consists of a molded object which can implement | achieve sufficiently high creep resistance, and it becomes possible to stabilize the surface quality of the plate glass shape | molded over a long time.

(2) Moreover, the shaping | molding apparatus of the plate glass of this invention includes the range from 10% to 90% with respect to the full length of a molded object elongate direction from the one side of the molded object which a cavity part supplies molten glass. If it forms in this way, the weight of a molded object can be made lightweight, the burden which keeps a molded object at high temperature can be reduced, and it becomes possible to improve the creep property of the molded object at high temperature further.

  (3) Further, in the sheet glass forming apparatus of the present invention, if the hollow portion is formed by a hole in the formed body, not only the above-described performance related to creep resistance but also the formed body becomes light. When the molding apparatus is configured, the molded body can be easily handled, and the burden on the other support structure over time can be reduced.

  (4) Furthermore, the sheet glass molding apparatus of the present invention can effectively reduce the weight of the molded body if the hollow portion is filled with a heat-resistant material having a density lower than that of the molded body. It is possible to efficiently suppress a decrease in the structural strength of the.

  (5) The plate glass molding apparatus of the present invention can prevent local stress concentration from occurring on the cavity surface if the cavity is filled with a porous material. It has the effect of suppressing weakening of structural strength caused by the surface.

  (6) Since the plate glass forming method of the present invention forms a plate glass for mounting a liquid crystal display device using the plate glass forming apparatus described above, the plate glass required for the plate glass mounted on the liquid crystal display device is used. The appearance surface quality can be continuously realized over a long period of time, and the management of the production facility can be saved and efficient molding can be performed.

  The plate glass shaping | molding apparatus of this invention and the plate glass shaping | molding method which uses a plate glass shaping | molding apparatus are demonstrated based on an Example below.

1A is a high-density zirconia refractory (density 4.0 g / cm ³ , Young's modulus 142 GPa), and its cross-sectional shape is open at the top as shown in FIG. 1B. In this state, a bowl-shaped molten glass supply groove 10a having a substantially V shape is provided at the top, and the tops of both end walls of the glass supply groove 10a serve as two overflow weirs 10b. Below the overflow weir 10b, the outer surfaces 10c of the two side walls are brought close to each other and finally terminated at the lower end 10d. The overall external dimensions of the molded body 10 are a total length dimension of 2500 mm, a height dimension of 700 mm, and a width dimension of 250 mm. This molded body has a cross-sectional area of 11 perpendicular to the longitudinal direction. 5 × 10 ⁴ mm ² . And inside the molded body 10, the cavity 10p about the cross section perpendicular | vertical to the elongate direction of the molded object 10 was obstruct | occluded by the length of 200 mm in the both ends in the state extended in the elongate direction of the molded object 10, respectively. It is formed in a state. And about the cross section perpendicular | vertical to a molded object elongate direction, the cross-sectional area of this cavity part is 15 * 10 < ³ > mm < ² >. That is, the length in the longitudinal direction of the cavity portion is 2100 mm, and the length dimension in the longitudinal direction is 1900 mm for a portion having a constant cross-sectional shape perpendicular to the longitudinal direction of the cavity portion, and the length of the compact is long. This corresponds to a length of 76% of the total length of the law.

  Here, as shown in FIG. 2, the unit cross-sections 11a1, 11a2,... 11aN (N is an arbitrary natural number) of the molded body 10 are divided into N so that the unit thickness is 1 cm. When the volume and section modulus of the virtual unit cross section 11 are sequentially calculated using a computer, the mass of the compact per unit cm (Wh) in the unit cross section 11 having the largest change rate of the cross section. Is 5.4 kg, and the ratio with respect to the mass (W0) of the compact before opening the cavity, that is, the value of Wh / W0 is 0.9. The ratio of the section modulus of the unit cross section 11, that is, the value of Zh / Z0 is 0.99, and it can be confirmed that the value is larger than the value of Wh / W0. It is designed to be configured.

  The dimension in the longitudinal direction of the molded body at a site satisfying (Wh / W0) <(Zh / Z0) is a length portion of 1100 mm at the center including the site corresponding to the center of gravity of the molded body, Its size is 44% of the total length.

  There are various methods for forming the cavity 10p of the molded body 10. Here, when the molded body before firing is cast by a casting method, an open cavity is formed at a predetermined position of the dried body. Then, the hollow portion is formed in a closed state by filling the same material as that of the molded body so as to close the open end.

  Next, an example of a method for forming a thin glass mounted on a liquid crystal display device by using a flat glass forming apparatus composed of the above-described molded body will be described.

  First, a glass raw material prepared in advance so as to have an alkali-free glass composition (Nippon Electric Glass Co., Ltd. glass OA-10 composition) in a glass melting tank (not shown) having a high-temperature heating facility of 1500 ° C. or higher. After melting and forming a homogeneous molten glass G by a glass refining process, the molten glass G is introduced into a molten glass supply groove 10 a formed in the molded body 10 by a molten glass supply pipe 20. Then, the molten glass G temporarily staying in the molten glass supply groove 10a overflows the two side wall top ridges 10e at the upper part of the molded body 10, and overflows to the outer surfaces 10c of the both side walls of the molded body. Along the lower end 10d of the molded body 10, and is continuously stretched by using a heat-resistant roller (not shown) provided below to form one sheet glass P. The Rukoto.

  When it is composed of a molded product that does not satisfy the relationship between the section modulus and unit sectional mass of the unit cross-section as in the past, the creep phenomenon due to high temperature use of the refractory constituting the molded product The outer dimensions of the molded body gradually changed, and the central portion of the ridge side wall top ridge line of the molded body hanged downward, resulting in an uneven thickness of the formed sheet glass. On the other hand, by using the sheet glass forming apparatus of the present invention, in the conventional molded body, the molded body 10 is used until the time when the central part of the ridge side wall top ridge line of the molded body exceeds the time when the drooping becomes clear is reached. However, a deformation phenomenon that causes a problem does not occur at all, and the period during which the molded body 10 is subjected to the normal forming of the plate glass P is extended, and the plate glass P having a stable quality can be formed over a long period of time. The formed plate glass P has no plate thickness difference between the central portion Pα of the plate glass and the peripheral portion Pβ of the plate glass, and has a plate thickness of 0.7 ± 0.01 mm and an effective width of about 2100 mm. There was no problem related to various dimensions such as meat, and the surface state of the plate glass was also good, and it was suitable as a plate glass used in applications mounted on TFT liquid crystal display devices.

  3A, 3B, 3C, and 3D with respect to other examples having a hollow portion that is different from the embodiment 1 with respect to the molded body constituting the sheet glass forming apparatus of the present invention. Shown in

  FIG. 3A shows a state in which three hollow portions 10q are laminated in a molded body having the same material as that of the first embodiment. FIG. 3B shows a cross section in the longitudinal direction of FIG. In order to construct such a molded body, a certain amount of molding technology is required. However, it is possible to place the cavity portions in the molded body in a distributed manner rather than having a large cavity, so the molded body is designed. At this stage, it is possible to predict the stress applied to the molded body in advance and determine the optimal condition by moving the cavity to the position where fine correction has been made according to the predicted value. Thus, a more preferable configuration state can be obtained.

  FIG. 3 (C) shows a case where two hollow portions 10r having a shape curved upward are formed in a molded body having the same material as that of the first embodiment. The curved hollow portion of the hollow portion 10r located below is filled with porous silicon carbide as the porous filling material 40.

  Each of the two molded bodies in FIG. 3 has a unit cross-sectional portion that satisfies the above-mentioned condition of (Wh / W0) <(Zh / Z0), and this molded body shape is used. When a model experiment was conducted, it was confirmed that good results having high durability could be obtained for any form. In the case of a molded body having a hollow portion having a complicated shape as shown in FIG. 3, a molded body divided into two in the longitudinal direction using two molds in advance is produced by casting, and both When the molded body is fired, it is possible to obtain the molded body by joining by sintering.

It is explanatory drawing of the plate glass shaping | molding apparatus of this invention, (A) is a top view, (B) is sectional drawing of the XX plane of (A) figure, (C) is the YY plane of (A) figure. A sectional view is shown. It is explanatory drawing regarding the unit cross-section part of plate glass. It is explanatory drawing of the other plate glass shaping | molding apparatus of this invention. (A) is a plan view, (B) is a central sectional view in the longitudinal direction of (A), (C) is another plan view, and (D) is a central sectional view in the longitudinal direction of (C). To express. 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 sectional view of a plane 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 sectional view of a plane is shown.

Explanation of symbols

1, 10, 50, 51 Molded body 11, 11a1, 11a2, 11a3, 11aN Unit cross section 1a, 10a Glass supply groove 1b, 10b Overflow weir 1c, 10c Outer surface of both side walls 1d, 10d Lower end 1e, 10e Both side wall top ridge lines 1f, 10f Both side wall guides 1g, 10g Molten glass central region 1h, 10h Molten glass both ends region 10p, 10q, 10r Cavity 2, 20 Molten glass supply pipe 3, 30 Support refractory 40 Filled heat resistant material G Molten glass F Gravity P Plate glass Pα Central part of plate glass Pβ Peripheral part of plate glass

Claims (6)

It has a bowl-shaped molten glass supply groove with an open top at the top, the top of both side walls of the glass supply groove is used as an overflow weir, and the outer surface of both side walls has a substantially wedge-shaped cross section at the outer surface of both side walls. Provided with molded bodies that are close to each other downward and terminated at the lower end, have a cavity in a cross section perpendicular to the longitudinal direction of the molded body, and continuously supply molten glass from one end of the glass supply groove Overflowing from both side wall top ridge lines, flowing down along the outer side surfaces of both side walls and joining at a substantially wedge-shaped lower end to form a sheet glass,
About the unit cross-section with the unit length in the long direction of the molded body as the thickness,
The section modulus Zh of the molded body having a cavity in the cross section, the molded body mass Wh of the unit section having the cavity in the section, the section coefficient Z0 of the molded body before forming the cavity in the section, and the unit before forming the cavity in the section a molded mass W0 of the cross section is, have a unit cross section become (Wh / W0) <(Zh / Z0),
(Wh / W0) <(Zh / Z0) become the unit cross section, forming apparatus of the glass sheet, characterized in that it have a 30% or more the length of the molded body length longitudinal direction. The hollow part is formed so as to include a range from 10% to 90% of the total length in the longitudinal direction of the molded body starting from one side of the molded body for supplying molten glass. 1. A glass sheet forming apparatus according to 1.   3. The plate glass forming apparatus according to claim 1, wherein the hollow portion is formed by a hole in the formed body.   The flat glass molding apparatus according to any one of claims 1 to 3, wherein the hollow portion is filled with a heat-resistant material having a density lower than that of the molded body.   The plate glass molding apparatus according to any one of claims 1 to 4, wherein the hollow portion is filled with a porous material.   A plate glass forming method comprising forming a plate glass for mounting a liquid crystal display device using the plate glass forming apparatus according to claim 1.

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