JP5574454B2 - Manufacturing method of glass substrate - Google Patents

Description

  The present invention relates to a glass substrate manufacturing method for manufacturing a glass substrate.

  As a glass substrate used for a flat panel display (hereinafter referred to as “FPD”) such as a liquid crystal display or a plasma display, a thin glass plate having a thickness of, for example, 0.5 to 0.7 mm is used. For example, the FPD glass substrate has a size of 300 × 400 mm in the first generation, but has a size of 2850 × 3050 mm in the tenth generation.

  In order to manufacture such a large size glass substrate for FPD, an overflow down draw method is often used. In the overflow downdraw method, a step of forming a sheet glass (plate glass) below the formed body by causing the molten glass to overflow (overflow) from the upper part of the formed body in a forming furnace, and the sheet glass is gradually cooled in the slow cooling furnace. A cooling step. The slow cooling furnace draws the sheet glass between a pair of rollers and conveys it downward to stretch it to a desired thickness, and then slowly cools the sheet glass. Thereafter, the sheet glass is cut into a predetermined size to be a glass plate and stored.

  A method for producing a glass substrate using such an overflow downdraw method is disclosed in Patent Document 1. FIG. 8 is a partial cross-sectional front view of the glass plate manufacturing apparatus disclosed in Patent Document 1. As shown in FIG. In the molding furnace 1, the glass sheet 8 is formed below the molded body 2 by overflowing the molten glass 3 from the upper part of the molded body 2, and provided in the vicinity of the side edges 8 a and 8 b of the molded sheet glass 8. The sheet glass 8 is conveyed downward by a plurality of stages of rollers 5a, 5b, 6a, 6b, 7a, 7b,..., And gradually cooled in this process. The rollers, for example, rollers 5a and 5b, are fixed to one ends (tip portions) of the roller shafts 9a and 9b, respectively, and the roller shafts 9a and 9b are supported by the bearings 10a and 10b. The other ends (rear ends) of the roller shafts 9a and 9b are connected to the motors 12a and 12b.

  In such a glass substrate manufacturing method using the overflow downdraw method, the temperature in the vicinity of the roller that conveys the sheet glass is maintained at a relatively high state (600 ° C. or higher at a high point). In general, because the roller shaft is made of metal, the risk of deformation increases because the strength decreases as the temperature rises.If the shaft is bent, the roll surface mounted near the tip of the shaft with the rotation of the shaft will feed the glass substrate. Periodic fluctuations occur, causing a thickness deviation or warpage in the longitudinal (tensile) direction. Patent Document 1 discloses that in order to prevent such deformation of the roller shaft, for example, the shaft is hollow and the roller shaft is cooled by flowing a cooling gas into the hollow space. In this case, it is disclosed that the hole is closed at the end of the shaft so that the cooling gas does not blow out around the sheet glass.

Japanese Patent No. 3093000

  When the roller shaft is cooled by flowing a cooling gas into the roller shaft disclosed in Patent Document 1, for example, as shown in FIG. 9, the roller 20 sandwiching the glass at the outer periphery is closed at one end. The inner pipe 22 is inserted into the closed end of the roller shaft 21, the inner pipe 22 having both ends opened from the uncovered shaft end, and a cooling gas is supplied from the rear end of the inner pipe 22. Let it flow. The gas ejected from the front end of the inner pipe 22 toward the front end of the hollow portion of the roller shaft 21 hits the inner wall surface blocking the hollow shaft, and then passes through the inside of the roller shaft 21 outside the inner pipe 22 from the vicinity of the rear end. A general method is to discharge the gas to the outside. 9A is a partial sectional front view, and FIG. 9B is a side view. The broken line arrows in FIG. 9A indicate the above-described gas flow.

  However, in the cantilevered roller shaft, the greatest stress is applied near the base on the support end side, so when cooling the roller shaft that becomes high temperature, the portion that needs the most cooling is also there. Then, the cooling gas is first supplied to the tip of the roller shaft 21 and direct heat exchange with the inner wall of the shaft is started, so that the tip of the roller shaft 21 is cooled most effectively. . In this configuration, when the amount of gas flow is adjusted in order to cool the root of the roller shaft 21 to a predetermined temperature or less, the tip temperature of the roller shaft 21 will be lower than the periphery of the root in the furnace. .

  By the way, the molten glass overflowed from the molded body is subjected to the above-described slow cooling so that warpage and distortion do not increase more than necessary, that is, satisfy the quality requirements of customers. Specifically, the temperature profile in the width direction of the sheet glass is designed in advance along the flow direction, and strict temperature management is performed using a cooling device or a heater so that the sheet glass has the designed temperature profile. It is carried out. However, in the slow cooling process, when the tip of the roller shaft 21 of the roller 20 that conveys the sheet glass is excessively cooled as described above, the tip surface of the roller shaft 21 is not particularly insulated from the inside of the furnace. In addition, the sheet glass in the vicinity is excessively cooled, or although it has a certain degree of heat insulation performance, the low temperature roll axis takes away the heat of the glass that the roll surface contacts through the roll material more than necessary, The balance of the temperature profile is lost, and a previously designed temperature profile cannot be reproduced. As a result, the warp and distortion of the manufactured glass substrate tends to increase.

  Therefore, the present invention has an object to provide a glass substrate manufacturing method capable of accurately reproducing a designed temperature profile and thereby suppressing deterioration of flatness (warping amount) and distortion of the glass substrate. And

  In order to maintain the straightness required for the roller shaft even when used in a high-temperature furnace for a long period of time in the slow cooling process and accurately reproduce the temperature profile designed for the glass, The inventors came up with the invention of the configuration.

(Invention of Configuration 1)
A method for producing a glass substrate, in which molten glass is overflowed from a molded body to form a continuous sheet glass, and the sheet glass is sandwiched by a roller and conveyed downward, wherein warpage and distortion of the glass substrate are reduced. Therefore, the temperature profile in the width direction of the sheet glass formed when the sheet glass flowing down from the molded body is slowly cooled while being pulled downward by the roller is controlled to a predetermined setting along the flow direction. In addition, the glass substrate manufacturing method is characterized in that the roller shaft is cooled so that the straightness of the roller shaft supporting the roller is maintained and the influence on the temperature profile of the sheet glass is suppressed. Here, “the straightness of the roller shaft is maintained” means that the straightness is within a predetermined standard value.

(Invention of Configuration 2)
The temperature of the roller shaft is controlled so that the temperature of the tip surface of the roller shaft on the side where the roller is mounted is not at least lower than the side surface portion in the furnace near the shaft support portion. It is a manufacturing method of the glass substrate of the structure 1 to do.

(Invention of Configuration 3).
The roller shaft has a hollow structure in which a tip end on the side where the roller is mounted is closed, and an inner pipe smaller in diameter than the inner diameter of the roller shaft having a plurality of opening holes on the side surface is inserted into the roller shaft hollow portion. By supplying the cooling medium from the rear end of the inner pipe, the cooling medium ejected from the plurality of holes is applied to the wall surface in a direction perpendicular to the wall surface, thereby efficiently cooling the roller shaft from the inner surface of the hollow section over a wide area. And it is a manufacturing method of the glass substrate of the structure 2 characterized by controlling the temperature of this roller axis | shaft to the arbitrary temperature distributions different in the longitudinal direction.

(Invention of Configuration 4)
The glass substrate manufacturing method according to Configuration 3, wherein a portion of the roller shaft at a base side from a roller mounting portion where the roller shaft is exposed in a slow cooling furnace is covered with a heat insulating material.
(Invention of Configuration 5)
Any one of the constitutions 1 to 4, wherein a temperature distribution is given to the sheet glass along the width direction of the sheet glass by using a heat source provided along the width direction of the sheet glass, and the sheet glass is gradually cooled. A method for producing a glass substrate according to claim 1.

(Invention of Configuration 6)
6. The glass substrate manufacturing method according to claim 1, wherein the temperature of the sheet glass sandwiched between the rollers is 600 ° C. to 1100 ° C. 6.

  According to the present invention, in the slow cooling process, the roller shaft supporting the roller for conveying the sheet glass is cooled so that the straightness of the roller shaft is maintained at a necessary level for a long time, and the temperature profile in the width direction of the sheet glass By controlling the temperature of the roller shaft so as not to affect the temperature, the intended (designed) temperature profile can be accurately reproduced, and the flatness (warping amount) and distortion of the glass substrate can be suppressed. It is possible to provide a method for manufacturing a glass substrate that can be used.

It is a figure which shows an example of the flow of the manufacturing method of the glass substrate of this invention. It is a figure which shows typically an example of the apparatus which performs the melting process thru | or cutting process in this invention. FIG. 3 is a schematic side view of the molding apparatus shown in FIG. 2. It is a figure explaining the heater unit used for control of the temperature profile in this invention. It is a figure explaining the several temperature profile in this invention. It is a partial section front view showing a 1st embodiment of a cooling method of a roller axis in the present invention. It is a fragmentary sectional front view which shows 2nd Embodiment of the cooling method of the roller shaft in this invention. It is a partial cross section front view of the manufacturing apparatus of the glass plate currently disclosed by patent document 1. FIG. (A) is the fragmentary sectional front view which shows the cooling method of the conventional roller shaft, (b) is the side view.

Hereinafter, embodiments of the present invention will be described in detail.
(Overall overview of glass substrate manufacturing method)
FIG. 1 is a diagram showing a flow of a glass substrate manufacturing method according to an embodiment of the present invention.
The glass substrate manufacturing method includes a melting step (ST1), a clarification step (ST2), a homogenization step (ST3), a supply step (ST4), a forming step (ST5), a cooling step (ST6), Cutting step (ST7). Moreover, the manufacturing method of a glass substrate has other processes, such as a grinding process, a grinding | polishing process, a washing | cleaning process, an inspection process, and a packing process. The plurality of glass plates stacked in the packing process are transported to a supplier (customer) as a delivery destination.

  FIG. 2 is a diagram schematically showing an apparatus for performing the melting step (ST1) to the cutting step (ST7). As shown in FIG. 2, the apparatus mainly includes a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300. The melting apparatus 100 includes a melting tank 101, a clarification tank 102, a stirring tank 103, a first pipe 104, a second pipe 105, and a third pipe 106. The molding apparatus 200 will be described later.

In the melting step (ST1), molten glass MG is obtained by melting the glass raw material supplied into the melting tank 101 by heating with a flame and an electric heater (not shown). The clarification step (ST2) is performed in the clarification tank 102, and oxygen contained in the molten glass MG is heated by heating the molten glass MG in the clarification tank 102 supplied from the melting tank 101 through the first pipe 104. Or SO ₂ bubbles grow by the oxidation-reduction reaction of the clarifying agent and float on the liquid surface and are released, or gas components in the bubbles are absorbed into the molten glass MG, and the bubbles disappear.
In the homogenization step (ST3), the glass component is homogenized by stirring the molten glass MG in the stirring tank 103 supplied from the clarification tank 102 through the second pipe 105 using the stirrer 103a.
In the supply step (ST4), the molten glass MG is supplied from the stirring vessel 103 to the molding apparatus 200 through the third pipe 106.

In the molding apparatus 200, a molding process (ST5) and a cooling process (ST6) are performed.
In the forming step (ST5), the molten glass MG is formed into a sheet glass SG (see FIG. 3) to make a flow of the sheet glass SG. In the present embodiment, an overflow down draw method using a molded body 210 described later is used. In this case, the flow direction (Z direction in the figure) of the sheet glass SG is vertically downward. In the cooling step (ST6), the sheet glass SG that is formed and flows has a desired thickness, and is cooled so that warpage and distortion due to cooling do not occur.
In the cutting step (ST7), the sheet glass SG supplied from the forming apparatus 200 is cut into a predetermined length in the cutting apparatus 300, whereby a plate-like glass substrate G is obtained.
Then, after grinding and polishing of the end face of the glass substrate G, the glass substrate G is cleaned, and further, the presence or absence of abnormal defects such as bubbles and striae is inspected, and then the glass that has passed the inspection. The substrate G is packed as a final product.

  The glass substrate G manufactured in the present embodiment is suitably used for, for example, a glass substrate for liquid crystal display, a glass substrate for organic EL display, and a cover glass. In addition, the glass substrate can also be used as a display for a portable terminal device, a cover glass for a housing, a touch panel plate, a glass substrate for a solar cell, or a cover glass. Particularly, it is suitable for a glass substrate for a liquid crystal display using a polysilicon TFT.

Moreover, the thickness of the glass substrate G is 0.1 mm-1.5 mm, for example. Preferably it is 0.1-1.2 mm, More preferably, it is 0.3-1.0 mm, More preferably, it is 0.3-0.8 mm, Most preferably, it is 0.3-0.5 mm.
Furthermore, the length of the glass substrate G in the width direction is, for example, 500 mm to 3500 mm, preferably 1000 mm to 3500 mm, and more preferably 2000 mm to 3500 mm. On the other hand, the length of the glass substrate G in the vertical direction is, for example, 500 mm to 3500 mm, preferably 1000 mm to 3500 mm, and more preferably 2000 mm to 3500 mm.

(Composition of glass substrate)
As the glass used for the glass substrate G, for example, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, soda lime glass, alkali silicate glass, alkali aluminosilicate glass, alkali aluminogermanate glass, or the like can be used. The glass applicable to the present invention is not limited to the above.

The glass composition of the glass substrate G can mention the following, for example. The content rate display of the composition shown below is mass%.
SiO ₂ : 50 to 70%,
Al ₂ O ₃ : 0 to 25%,
B ₂ O ₃ : 1 to 15%
MgO: 0 to 10%,
CaO: 0 to 20%,
SrO: 0 to 20%,
BaO: 0 to 10%,
RO: 5 to 30% (where R is the total amount of Mg, Ca, Sr and Ba),
It is preferable that it is an alkali free glass containing.

In the present embodiment, alkali-free glass is used, but the glass substrate G may be alkali-containing glass containing a trace amount of alkali metal. When an alkali metal is contained, the total of R ′ ₂ O is 0.10% or more and 0.5% or less, preferably 0.20% or more and 0.5% or less (where R ′ is selected from Li, Na, and K) It is preferable that the glass substrate G contains at least one kind. Of course, the total of R ′ ₂ O may be less than 0.10%. In order to facilitate melting of the glass, the content of iron oxide in the glass is 0.01 to 0.2% (preferably 0.01 to 0.08%) from the viewpoint of reducing the specific resistance. More preferably. Moreover, it is more preferable that the content of tin oxide added as a fining agent is 0.01 to 1% (preferably 0.01 to 0.5%).

(Description of molding equipment)
FIG. 3 is a side view showing the configuration of the glass substrate G forming apparatus 200.
The molding apparatus 200 includes a molding furnace 201 that performs a molding process (ST5) and a slow cooling furnace 202 that performs a cooling process (ST6).

  In the cooling step (ST6) performed in this embodiment, in order to reduce warpage and distortion of the glass substrate G, the width direction of the sheet glass SG formed in the forming step (ST5) (horizontal in the forming apparatus 200 shown in FIG. 2). Using the heater unit provided along the direction), the sheet glass SG is subjected to a slow cooling process for cooling while giving a temperature distribution along the width direction of the sheet glass SG.

  The forming furnace 201 and the slow cooling furnace 202 are configured to be surrounded by a furnace wall made of a refractory material such as a refractory brick, a refractory heat insulating brick, or a fiber-based heat insulating material. The forming furnace 201 is provided vertically above the slow cooling furnace 202. In the furnace internal space surrounded by the furnace walls of the forming furnace 201 and the slow cooling furnace 202, a plurality of transports including a molded body 210, an atmosphere partition member 220, a cooling roller 230, a cooling unit 240, and transport rollers 250a to 250c. A roller and a plurality of temperature adjusting devices are provided.

As shown in FIG. 2, the formed body 210 forms molten glass MG flowing from the melting apparatus 100 through the third pipe 106 into a sheet glass SG. Thereby, the flow of the sheet glass SG in the vertically lower direction is created in the forming apparatus 200. The molded body 210 is a long and narrow structure made of firebrick or the like, and has a wedge-shaped cross section as shown in FIG. A groove 212 serving as a flow path for guiding the molten glass MG is provided in the upper part of the molded body 210. The groove 212 is connected to the third pipe 106 at a supply port provided in the molded body 210, and the molten glass MG flowing through the third pipe 106 flows along the groove 212. The depth of the groove 212 is shallower toward the downstream side of the flow of the molten glass MG, so that the molten glass MG overflows vertically downward from the groove 212.
The molten glass MG overflowing from the groove 212 flows down along the side walls on both sides of the molded body 210. The molten glass MG that has flowed through the side walls merges at the lower end 213 (shown in FIG. 3) of the molded body 210 to form one sheet glass SG. The sheet glass SG flows in the Z direction, which is the flow direction of the sheet glass SG shown in FIG. The temperature of the sheet glass SG immediately below the lower end 213 of the molded body 210 is a temperature corresponding to a viscosity of 10 ^5.7 to 10 ^7.5 poise (for example, 1000 to 1130 ° C.).

  An atmosphere partition member 220 is provided near the lower portion of the lower end 213 of the molded body 210. The atmosphere partition member 220 is a pair of plate-like heat insulating members, and is provided on both sides in the thickness direction of the sheet glass SG so as to sandwich the sheet glass SG from both sides in the thickness direction (X direction in the drawing). Yes. A gap is provided between the sheet glass SG and the atmosphere partition member 220 to such an extent that the atmosphere partition member 220 does not contact the sheet glass SG. The atmosphere partition member 220 partitions the internal space of the molding furnace 201, thereby blocking heat transfer between the furnace internal space above the atmosphere partition member 220 and the furnace internal space below.

An air-cooled cooling roller 230 is provided below the atmosphere partition member 220. As shown in FIG. 3, the cooling roller 230 is provided on both sides in the thickness direction of the sheet glass SG so as to sandwich the sheet glass SG from both sides in the thickness direction. In addition, it is preferable to cool the cooling roller 230 until the temperature of the width direction both ends of the sheet glass SG falls to the temperature (for example, 900 degrees C or less) corresponded to the viscosity of about 10 < ⁹ > .0 poise or more.

  A cooling unit 240 is provided below the atmosphere partition member 220. The cooling unit 240 is composed of a plurality of cooling devices.

  A temperature adjusting device is provided in a region sandwiched between the top plate 202a and the top plate 202b below the top plate 202a. In this region, conveyance rollers 250a are provided on both sides in the thickness direction of the sheet glass SG. Furthermore, in this region, heater units 270 as heat sources are provided on both sides in the thickness direction of the sheet glass SG as a temperature adjusting device. The heater unit 270 includes a plurality of heaters provided along the width direction of the sheet glass so as to control the temperature profile in the width direction. Each heater can adjust the heating amount.

  A temperature adjusting device using another heater unit 270 is further provided in a region sandwiched between a top plate (not shown) adjacent to the bottom of the top plate 20b and the top plate 202b.

FIG. 4 is a diagram for explaining the heater unit 270. In FIG. 4, the conveyance roller 250a is not shown.
The heater unit 270 is divided into five heaters 270a to 270e along the width direction of the sheet glass SG, and each of the heaters 270a to 270e generates heat. The heaters 270a to 270e include a heat source such as a chromium-based heating wire, for example. The heating amount of each of the five heaters 270a to 270e is configured to be individually adjustable.

The sheet roller SG is cooled by the cooling roller 230, the cooling unit 240, and the heater unit 270 so as to have a temperature distribution corresponding to a temperature profile designed in advance, for example, as follows. FIG. 5 is a diagram illustrating a plurality of temperature profiles in the present invention.
In the viscous region, for example, the first temperature profile P1 is designed. In the viscoelastic region, for example, a second temperature profile P2, a third temperature profile P3, and a fourth temperature profile P4 are designed.
The first temperature profile P1 is a temperature profile in which the end portion in the width direction of the sheet glass is lower than the temperature of the central region sandwiched between the end portions, and the temperature of the central region is uniform. With the first temperature profile P1, it is possible to make the thickness of the sheet glass uniform while suppressing shrinkage in the width direction.

  The second temperature profile P2 is a temperature profile in which the temperature in the width direction of the sheet glass gradually decreases from the central portion toward the end portion. Similarly to the second temperature profile P2, the third temperature profile P3 is a temperature profile in which the temperature in the width direction of the sheet glass gradually decreases from the central portion toward the end portion, but the temperature gradient is higher than that of the second temperature profile P2. Has been reduced. The fourth temperature profile P4 is a temperature profile in which the temperature gradient between the end portion and the center portion in the width direction of the sheet glass is further reduced and becomes substantially uniform in the temperature region near the glass strain point. Warpage and distortion (residual stress) can be reduced by the second temperature profile P2, the third temperature profile P3, and the fourth temperature profile P4. In addition, the center area | region of sheet glass is an area | region including the part of the object which makes plate | board thickness uniform, and the edge part of sheet glass is an area | region including the part of the object cut | disconnected after manufacture.

  As described above, the molten glass overflowed from the formed body is subjected to the above-described slow cooling step so that warpage and strain do not exceed allowable values. In this slow cooling step, as described above, the temperature profile in the width direction of the sheet glass is designed in advance along the flow direction so that the warp and strain do not exceed the allowable values, and the sheet glass is designed. Strict temperature management is performed using a cooling device, a heater, or the like so as to obtain a temperature profile. However, in the slow cooling process, if the tip of the roller that conveys the sheet glass is excessively cooled, the sheet glass in the vicinity thereof cannot reproduce the temperature profile designed in advance due to the cooling effect. As a result, warpage and distortion exceeding the allowable value are generated in the manufactured glass substrate.

  Therefore, in the present invention, the roller shaft is cooled so that the straightness of the roller shaft supporting the roller is maintained at a necessary level for a long time, and the influence on the designed temperature profile is minimized. It is characterized by controlling the temperature of the roller shaft. Hereinafter, a description will be given based on the embodiment.

[First Embodiment]
FIG. 6 is a partial sectional front view showing a first embodiment of a roller shaft cooling method according to the present invention.
The roller 30 shown here corresponds to the transport rollers 250a to 250c in the molding apparatus 200 shown in FIG. 3, and in this embodiment, the roller 30 is cantilevered. Therefore, in the slow cooling furnace of the forming apparatus, the roller 30 contacts the sheet glass surface flowing from above and conveys the sheet glass downward.

  The roller shaft 31 that supports the roller 30 is formed in a hollow structure, and the roller 30 is fixed to the tip portion thereof. Usually, the roller 30 is made of hardened inorganic fibers, and the roller shaft 31 is made of, for example, martensitic stainless steel having excellent heat resistance and high hardness. In the present embodiment, the same material is used. Further, the tip end portion having a smaller diameter than the hole inner diameter of the roller shaft 31 is closed, the rear end portion is opened, and a plurality of openings (small holes) 32a1, 32a2, 32b1, 32b2,. , 32f2 is inserted into the hollow portion of the roller shaft 31. Then, by supplying the cooling medium from the rear end portion of the inner pipe 32, the cooling medium is ejected from the opening on the side surface of the inner pipe 32 toward the inside of the roller shaft 31. In this case, the cooling medium may be gas or liquid. However, since the liquid has a large heat capacity, it takes heat excessively and lowers the shaft temperature too much, so a gas is more preferable. In addition, the broken line arrow in FIG. 6 has shown the flow of the above-mentioned cooling medium.

  According to the present embodiment, the tip of the inner pipe 32 is closed, and the cooling medium that has flowed into the inner pipe 32 enters the roller shaft 31 exclusively from the plurality of holes provided in the side surface of the inner pipe 32. In order to eject, the cooling medium does not cool the tip end surface of the roller shaft 31 and its surroundings very much, and the inner surface of the roller shaft 31 that needs to be cooled over the entire length inside the furnace and the hole position and hole By arbitrarily changing the diameter, it is possible to cool by changing the degree of cooling depending on the place. When the influence on the glass near the roller tip is suppressed, the designed temperature profile can be accurately reproduced, and the flatness and distortion of the glass substrate can be suppressed. That is, according to the present embodiment, the roller shaft 32 that supports the roller 30 is creep-deformed by heat in the atmosphere, so that the straightness does not exceed a predetermined standard value and the temperature profile of the sheet glass is set. The roller shaft 31 can be effectively cooled so that the influence exerted is minimized.

  In the present embodiment, the size, position, number, and the like of the opening provided on the side surface of the inner pipe 32 are not limited to those shown in FIG. From the viewpoint of effectively cooling the roller shaft 31 with a minimum air volume according to the magnitude of the bending moment in the longitudinal direction, the size, position, number, etc. of the opening can be arbitrarily set.

[Second Embodiment]
FIG. 7 is a partial sectional front view showing a second embodiment of the roller shaft cooling method according to the present invention.
As shown in FIG. 7, the present embodiment is characterized in that the exposed portion of the exposed roller shaft 31 is covered with a heat insulating material 33 in the first embodiment (FIG. 6). is there.

By covering the exposed exposed portion of the roller shaft 31 with the heat insulating material 33, the influence of the high temperature state (600 ° C. or higher) of the atmosphere received by the roller shaft 31 is reduced, so that the cooling of the roller shaft 31 is more effective. Therefore, the supply amount of the cooling medium can be greatly reduced.
Examples of the method of covering with the heat insulating material 33 include a method of covering the roller shaft 31 that exposes a cylindrical heat insulating cover filled with a heat insulating material on the inside to insulate it. The heat insulating material 33 naturally needs to have heat resistance at that temperature.

  According to the present embodiment, the amount of air necessary to keep the roller shaft at the required low temperature can be reduced, and therefore the glass close to the roller tip is less likely to be selectively (excessively) cooled than the conventional configuration, and the temperature is low. Since the metal roller shaft is not exposed in the furnace, it is less likely to be affected by the temperature profile of the sheet glass, so that the flatness and distortion of the glass substrate can be prevented. That is, according to the present embodiment, the roller shaft 32 supporting the roller 30 is creep-deformed by heat in the atmosphere and the straightness does not exceed a predetermined standard value, and the influence on the temperature profile of the sheet glass is further increased. The roller shaft 31 can be cooled so as to be suppressed.

Hereinafter, the present invention will be described more specifically with reference to examples.
The glass substrate was manufactured using the manufacturing apparatus of this embodiment for implementing the manufacturing method of the glass substrate of this invention. The roller shaft of the above-described transport roller was cooled by the method shown in FIG. Moreover, the glass raw material was prepared so that it might become the following compositions.
SiO ₂ 61%,
Al ₂ O ₃ 17%,
B ₂ O ₃ 11%,
CaO 6%,
SrO 3%,
BaO 1%

For each of the manufactured glass substrates, one piece (8 pieces / day) was sampled every 3 hours over one week, and the flatness (warping amount) and distortion were measured for each of the 56 samples. The average value was calculated.
As a result, the flatness of the glass substrate manufactured by the glass substrate manufacturing apparatus of this embodiment was manufactured by a conventional glass substrate manufacturing apparatus that cools the roller shaft of the transport roller by the method shown in FIG. The flatness of the glass substrate was reduced by 5%. Further, the strain amount of the glass substrate manufactured by the glass substrate manufacturing apparatus of the present embodiment was reduced by 5% from the strain amount of the glass substrate manufactured by the conventional glass substrate manufacturing apparatus.
In addition, about flatness, it measured using the laser displacement meter. In addition, the amount of strain is measured by using a birefringence measuring device ABR-10A manufactured by UNIOPT, and the amount of birefringence is measured at a plurality of predetermined measurement positions. Adopted as.
From this, the effect of the manufacturing method of the glass substrate by this invention is clear.

  In the present embodiment, a heater unit including a plurality of heaters is used as a heat source. However, the heat source is not limited to a heater that is a heat source that radiates heat, and a high-temperature air blowing device that provides hot air toward the sheet glass SG is used as a sheet. A plurality of glass SGs may be provided in the width direction.

  As mentioned above, although the manufacturing method of the glass substrate of this invention was demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, you may make various improvement and a change. Of course.

30 Roller 31 Roller shaft 32 Inner pipes 32a1, 32a2,..., 32f1, 32f2 Opening 33 Heat insulating material 100 Melting device 101 Melting tank 102 Clarification tank 103 Stirring tank 104 First pipe 105 Second pipe 106 Third pipe 200 Molding Device 201 Molding furnace 202 Slow cooling furnace 202a, 202b Top plate 210 Molded body 212 Groove 213 Lower end 220 Atmosphere partition member 230 Cooling roller 240 Cooling unit 242 Central cooling unit 242 Cooling amount adjustment unit 244 End cooling units 250a to 250c Conveying roller 270 heater units 270a to 270e heater 300 cutting device

Claims (4)

A molten glass is overflowed from a molded body to form a continuous sheet glass, and a roller is a method for producing a glass substrate that sandwiches the sheet glass and conveys it downward,
In order to reduce warpage and distortion of the glass substrate, the sheet glass that has flowed down from the molded body is flown through a temperature profile in the width direction of the sheet glass that is formed when the sheet glass is slowly cooled while being pulled downward by the roller. Control to a predetermined setting along the direction,
Cooling the roller shaft so that the straightness of the roller shaft supporting the roller is maintained and the influence on the temperature profile of the sheet glass is suppressed ;
Controlling the temperature of the roller shaft so that the temperature of the roller shaft tip surface on the side on which the roller is mounted is not lower than at least the side surface portion in the furnace on the side close to the shaft support portion;
The roller shaft has a hollow structure in which a tip end on the side where the roller is mounted is closed, and an inner pipe smaller in diameter than the inner diameter of the roller shaft having a plurality of opening holes on the side surface is inserted into the roller shaft hollow portion. By supplying the cooling medium from the rear end of the inner pipe, the cooling medium ejected from the plurality of holes is applied to the wall surface in a direction perpendicular to the wall surface, thereby efficiently cooling the roller shaft from the inner surface of the hollow section over a wide area. And the temperature of this roller axis | shaft is controlled to arbitrary different temperature distribution in a longitudinal direction, The manufacturing method of the glass substrate characterized by the above-mentioned. Wherein the root side of the roller mounting portion of the roller shaft, a glass substrate manufacturing method according to claim 1, characterized in that covers a portion the roller shaft is exposed at lehr with a heat insulating material. Using a heat source which is provided along the width direction of the sheet glass, said sheet glass, said along the width direction of the sheet glass to claim 1 or 2, characterized in that annealing giving temperature distribution The manufacturing method of the glass substrate of description. The temperature of the said sheet glass pinched | interposed by the said roller is 600 to 1100 degreeC, The manufacturing method of the glass substrate as described in any one of the Claims 1 thru | or 3 characterized by the above-mentioned.

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