KR101346939B1 - Method and apparatus of making glass substrate - Google Patents

Abstract

The manufacturing method of a glass plate includes the melting process of melt | dissolving a glass raw material, and obtaining a molten glass, the shaping process of supplying the said molten glass to the molded object provided in the shaping | molding furnace, shape | molding a glass ribbon, and making the flow of the said glass ribbon, A slow cooling step of pulling the glass ribbon with a roller provided in the slow cooling furnace to cool the inside of the slow cooling furnace, a glass ribbon cutting step of cutting the cooled glass ribbon in a glass ribbon cutting space, and the cut of the cut glass ribbon. An ear cutting process which cuts the ear part formed in the both ends of the width direction in an ear cutting space. At least one air pressure of the glass ribbon cutting space and the ear cutting space is adjusted so that the air pressure of the glass ribbon cutting space increases with respect to the air pressure of the ear cutting space.

Description

Glass plate manufacturing method and glass plate manufacturing apparatus {METHOD AND APPARATUS OF MAKING GLASS SUBSTRATE}

TECHNICAL FIELD This invention relates to the manufacturing method of a glass plate by a down-draw method, and a glass plate manufacturing apparatus.

Conventionally, the down draw method is used as a shaping | molding method of the glass substrate used for flat panel displays, such as a liquid crystal display, for example. About the down draw method, it is described in following patent document 1, for example.

In addition, in Patent Document 2, in the method of manufacturing a glass plate by the down draw method, in order to reduce the plane deformation of the glass plate, the air pressure in the furnace outside atmosphere (the furnace outside space) of the molding furnace and / or the slow cooling furnace is described. The technique which suppresses the temperature fluctuation in a slow cooling furnace by pressurizing and reducing the rising airflow which generate | occur | produces along a glass ribbon in a slow cooling furnace is disclosed.

Japanese Patent Application Publication No. 2009-196879 Japanese Patent Application Publication No. 2009-173525

By the way, the glass plate manufactured is required to improve the surface quality according to the request of high definition of a liquid crystal display, and therefore, it is necessary to suppress deterioration of surface quality in the manufacturing process of a glass plate. In the manufacturing process of a glass plate, after a glass ribbon is shape | molded by molten glass, a glass ribbon is annealed.

Generally, the glass ribbon after cooling is cut | disconnected to a desired size in the glass ribbon cutting chamber arrange | positioned under the slow cooling furnace, and a glass plate is produced. Moreover, the ear | edge part which has thickness larger than the center part of the width direction of a glass plate is formed in the both ends of the width direction of a glass plate. This ear | edge part is cut | disconnected in an ear | edge cutting chamber, after a glass plate is conveyed to the ear | edge cutting chamber which adjoinably adjoins a glass ribbon cutting chamber. At this time, as described in Patent Literature 2, when an air flow rising from the cutting chamber into the slow cooling furnace occurs, the air flow contains particles of glass introduced into the glass ribbon cutting chamber from the cutting chamber. Particles may flow into the slow cooling furnace and adhere to glass ribbons flowing through the slow cooling furnace. When the glass ribbon is annealed in a state where the particles of glass are attached to the surface of the glass ribbon, bubbles or minute projections are formed on the surface of the glass ribbon by the particles of the glass, so that the surface quality of the glass plate formed after the cooling process deteriorates. There is a concern.

Therefore, an object of this invention is to provide the manufacturing method of the glass plate which suppresses deterioration of the surface quality of a glass plate when manufacturing a glass plate by a downdraw method.

1st aspect of this invention is a manufacturing method of the glass plate by the down-draw method,

A dissolution step of melting the glass raw material to obtain a molten glass;

A molding step of molding the glass ribbon by supplying the molten glass to a molded body provided in the molding furnace;

A slow cooling step of pulling the glass ribbon with a roller provided in the slow cooling furnace to cool the inside of the slow cooling furnace;

A glass ribbon cutting step of cutting the cooled glass ribbon in a glass ribbon cutting space;

And an ear cutting step of cutting the ear portions formed at both ends in the width direction of the cut glass ribbon in the ear cutting space.

So that the air pressure of the glass ribbon cutting space is increased with respect to the air pressure of the ear cutting space,

At least one air pressure of the glass ribbon cutting space and the ear cutting space is adjusted.

At this time, as a 1st preferable aspect, at least one air pressure of the said glass ribbon cutting space and the said ear cutting space is adjusted so that the difference between the air pressure of the said glass ribbon cutting space and the air pressure of the said ear cutting space may be 40 Pa or less.

Moreover, as a 2nd preferable aspect, when the internal space of the said molding furnace in which the said molded object was installed, and the internal space of the said slow cooling furnace in which the said roller was installed as a furnace internal space, the air pressure of the said glass ribbon cutting space is The air pressure of the glass ribbon cutting space is adjusted so as to be lower with respect to air pressure.

Moreover, as a 3rd preferable aspect, in the said slow cooling process,

In the center portion of the width direction of the glass ribbon, the tension acts on the flow direction of the glass ribbon,

At least in the temperature range where the temperature of the center part of the width direction of the said glass ribbon becomes the temperature which subtracted 200 degreeC from the strain point temperature of glass from the temperature which added 150 degreeC to the temperature of the cooling point of glass,

Temperature control is performed so that the cooling rate of the center part of the width direction of the said glass ribbon becomes faster than the cooling rate of the both ends of the said width direction.

As a 4th preferable aspect, in the area | region where the temperature of the center part of the width direction of the said glass ribbon is more than the softening point temperature of glass, the temperature of the said center part is lower than the temperature of the center part which both ends of the width direction of the said glass ribbon pinched | interposed at the both ends. Control the temperature of the glass ribbon to be uniform,

In the center part of the width direction of the glass ribbon, in the area where the temperature of the center part of the glass ribbon is lower than the softening point temperature of the glass and above the strain point temperature of the glass so that the tension in the flow direction of the glass ribbon acts, the width direction of the glass ribbon The temperature of the glass ribbon is controlled such that the temperature of the temperature distribution of is lowered from the central portion toward the both ends,

The temperature of the glass ribbon is controlled so that the temperature gradient between the both ends and the center portion in the width direction of the glass ribbon disappears in the temperature range where the temperature of the center portion of the glass ribbon becomes the strain point temperature of the glass.

As a 5th preferable aspect, in the area | region of the width direction of the said glass ribbon, the temperature of the said glass ribbon in the area | region below the strain point temperature of glass so that the temperature of the said center part of the glass ribbon may act so that the tension | tensile_strength of a flow direction of a glass ribbon may act. The temperature of the glass ribbon is controlled so that the temperature of the distribution is lowered from both ends toward the center portion.

In addition to each of the first to fifth preferred forms, a composite form combining at least two or more of the first to fifth preferred forms may also be applied to the method for producing a glass plate of the first aspect.

The 2nd aspect of this invention is a manufacturing apparatus of the glass plate by the down-draw method,

A melting tank for melting a glass raw material to obtain a molten glass,

A molding furnace for supplying the molten glass to a molded body provided in the molding furnace to form a glass ribbon;

A slow cooling furnace which pulls the said glass ribbon with the roller provided in the slow cooling furnace, and cools in the said slow cooling furnace,

A glass ribbon cutting device for cutting the cooled glass ribbon in a glass ribbon cutting space;

An ear cutting device which cuts the ear | edge part formed in the both ends of the width direction of the said glass ribbon cut | disconnected in an ear | edge cutting space,

Adjusting means for adjusting the air pressure of at least one of the glass ribbon cutting space and the ear cutting space so that the air pressure of the glass ribbon cutting space increases with respect to the air pressure of the ear cutting space.

As a sixth preferred form,

The adjusting means,

In the glass ribbon cutting space and the ear cutting space, a pressure sensor for measuring the pressure of air pressure, a blower for sending air from the atmosphere into the glass ribbon cutting space and the ear cutting space, and the gas ribbon cutting space and the ear cutting space At least one of the dust collectors which collect and collect the air inside and a control apparatus which adjusts the said apparatus according to the measurement result of the said pressure sensor are included.

As a 7th preferable aspect, when the internal space of the said molding furnace in which the said molded object was installed, and the internal space of the slow cooling furnace in which the said roller was installed as a furnace internal space, at least among the said blower and dust collector provided in the said glass ribbon cutting space. One adjusts the air pressure of the said glass ribbon cutting space so that the air pressure of the said glass ribbon cutting space may become low with respect to the air pressure of the said furnace interior space by adjusting the introduction of air from the atmosphere and air suction of the said cutting space. .

As an 8th preferable aspect, in the inner space of the said slow cooling furnace,

In the center portion of the width direction of the glass ribbon, the tension acts in the flow direction of the glass ribbon,

At least in the temperature range where the temperature of the center part of the width direction of the said glass ribbon becomes the temperature which subtracted 200 degreeC from the strain point temperature of glass from the temperature which added 150 degreeC to the temperature of the cooling point of glass,

The temperature control unit which controls temperature so that the cooling rate of the center part of the width direction of the said glass ribbon becomes faster than the cooling rate of the both ends of the said width direction is provided.

As a ninth preferred aspect, a cooling unit is provided in an inner space of the forming furnace, and a temperature adjusting unit is provided in an inner space of the slow cooling furnace.

At least one of the cooling unit and the temperature adjusting unit

The glass ribbon such that the temperature of the central portion in the width direction of the glass ribbon is lower than the temperature of the central portion sandwiched between the both ends of the width direction of the glass ribbon at both ends of the softening point temperature of the glass, and the temperature of the central portion becomes uniform. To control the temperature of the

In the center part of the width direction of the glass ribbon, in the area where the temperature of the center part of the glass ribbon is lower than the softening point temperature of the glass and above the strain point temperature of the glass so that the tension in the flow direction of the glass ribbon acts, the width direction of the glass ribbon Controlling the temperature of the glass ribbon so that the temperature distribution of is lowered from the center toward both ends,

The temperature of the glass ribbon is controlled so that the temperature gradient between the both ends and the center portion in the width direction of the glass ribbon disappears in the temperature range where the temperature of the center portion of the glass ribbon becomes the strain point temperature of the glass.

As a tenth preferred aspect, a temperature adjusting unit is provided in an internal space of the slow cooling furnace,

The temperature adjustment unit,

In the center portion of the width direction of the glass ribbon, in the region where the temperature of the center portion of the glass ribbon is less than the strain point temperature of the glass so that the tension in the flow direction of the glass ribbon acts, the temperature of the temperature distribution of the glass ribbon is at both ends. The temperature of the glass ribbon is controlled so as to be lowered toward the central portion.

In addition to each of the sixth to tenth preferred forms, the composite form combining at least two or more of the sixth to tenth preferred forms may also be applied to the apparatus for producing a glass plate of the second aspect.

According to the manufacturing method of the glass plate of the said aspect, and the manufacturing apparatus of a glass plate, deterioration of the surface quality of a glass plate can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the flow of the manufacturing method of the glass plate which is this embodiment.
It is a figure which shows typically the apparatus which performs the dissolution process-the ear cutting process of this embodiment.
3 is a schematic side view of a molding apparatus for a glass plate in the present embodiment.
4 is a schematic front view of a molding apparatus for a glass plate in the present embodiment.
5 is a schematic diagram of a control system for controlling the amount of air sent by the blower used in the present embodiment.

Hereinafter, the manufacturing method of the glass plate of this invention, and the manufacturing apparatus of a glass plate are demonstrated. 1 is a diagram illustrating a flow of a manufacturing method of a glass plate according to the present embodiment.

Hereinafter, each phrase described in this specification is defined as follows.

The center portion of the sheet glass refers to the center of the width direction of the sheet glass among the widths of the sheet glass in the width direction.

The end portion of the sheet glass refers to a range within 100 mm from the edge of the sheet glass in the width direction.

Strain point temperature means the temperature of the glass plate whose log (eta) is 14.5, when glass viscosity is (eta).

The cooling point temperature refers to the temperature of the glass having a log η of 13.

The softening point temperature refers to the glass temperature with log η of 7.6.

The glass transition point temperature refers to the temperature of the glass when the supercooled liquid changes to the glass state.

(Full summary of the manufacturing method of the glass plate)

The manufacturing method of a glass plate is a melting process (ST1), a clarification process (ST2), a homogenization process (ST3), a supply process (ST4), a molding process (ST5), a slow cooling process (ST6), a glass ribbon It mainly has a cutting process ST7 and an ear cutting process ST8. In addition, the some glass plate which has a grinding process, a grinding process, a washing process, an inspection process, a packaging process, etc., and was laminated by the packaging process is conveyed to the supplier of a delivery destination.

FIG. 2: is a figure which shows typically the apparatus which performs melt | dissolution process (ST1)-ear cutting process (ST8). As shown in FIG. 2, the apparatus mainly includes a melting apparatus 200, a molding apparatus 300, a glass ribbon cutting apparatus 400, and an ear cutting apparatus 500. The dissolution apparatus 200 has a dissolution tank 201, a clarification tank 202, a stirring tank 203, a first pipe 204, and a second pipe 205. The molding apparatus 300 will be described later.

In the melting step (ST1), a molten glass is obtained by heating and dissolving the glass raw material supplied into the dissolution tank 201. The clarification process ST2 is mainly performed in the clarification tank 202, and reduces the bubble contained in a molten glass. In homogenization process ST3, the glass component is homogenized by stirring molten glass in the stirring tank 203 supplied through the 1st piping 204 using a star. In supply process ST4, a molten glass is supplied to the shaping | molding apparatus 300 via the 2nd piping 205. FIG.

In the shaping | molding apparatus 300, shaping | molding process ST5 and slow cooling process ST6 are performed.

In the molding step ST5, the molten glass is molded into the glass ribbon G (see FIG. 3) to make the flow of the glass ribbon G. In this embodiment, the overflow down draw method using the molded object 310 mentioned later is used. In the slow cooling process ST6, cooling is performed so that plane deformation does not occur and heat shrinkage does not increase.

In the glass ribbon cutting process ST7, in the glass ribbon cutting device 400, the glass ribbon G supplied from the shaping | molding apparatus 300 is cut | disconnected to predetermined length, and plate-shaped glass plate G1 (FIG. 3).

In the ear cutting step ST8, the ear cutting device 500 cuts the ear parts G2 (see FIG. 3) formed at both ends in the width direction of the glass plate G1. Here, the ear portion G2 is formed at both ends in the width direction of the glass ribbon G in the molding step ST5 and the slow cooling step ST6, and the cooling roller 330 and the conveying rollers 350a to 350h described later and It includes the part in contact. In addition, the thickness of the ear | edge part G2 is larger than the thickness of the center part of the width direction of the glass ribbon G. As shown in FIG.

In addition, the glass plate G1 after an ear | edge cutting process is cut | disconnected to predetermined size, and the glass plate G1 of a desired size is produced.

(Explanation of the molding apparatus)

3 and 4 are diagrams mainly showing the configuration of the shaping apparatus 300 of the glass plate, FIG. 3 mainly shows a schematic side view of the shaping apparatus 300, and FIG. 4 schematically shows the shaping apparatus 300. The front view is shown.

The glass plate shape | molded by the shaping | molding apparatus 300 is used suitably for the glass substrate for liquid crystal displays, the glass substrate for organic electroluminescent displays, and a cover glass, for example. In addition, the glass plate shape | molded by the shaping | molding apparatus 300 can be used also as a cover glass for display and housings, such as a portable terminal apparatus, a touch panel board, a glass substrate of a solar cell, and a cover glass. In particular, it is suitable for the glass substrate for liquid crystal displays using LTPS (Low Temperature Poly Silicon) -TFT.

The shaping furnace 40 which performs shaping | molding process ST5 and the slow cooling furnace 50 which performs slow cooling process ST6 are comprised by the furnace wall comprised of refractory materials, such as a fire brick, a fire resistant heat insulating brick, or a fiber type heat insulating material. The forming furnace 40 is provided perpendicularly upward with respect to the slow cooling furnace 50. The molding furnace 40 and the slow cooling furnace 50 are referred to as a furnace 30. In the furnace interior space enclosed by the furnace wall of the furnace 30, the molded object 310, the atmosphere partition member 320, the cooling roller 330, the cooling unit 340, the conveying rollers 350a-350h, Pressure sensors 355 and 360a to 360c (see Fig. 4) are provided.

As shown in FIG. 2, the molded body 310 displays a molten glass (shown by reference numeral MG in FIG. 3 and FIG. 4) flowing from the dissolution apparatus 200 through the second pipe 205. The glass ribbon G Molding). Thereby, in the shaping | molding apparatus 300, the flow of the glass ribbon G of the perpendicular | vertical downward is made. The molded body 310 is an elongated structure composed of refractory bricks or the like, and has a wedge shape in cross section as shown in FIG. At the top of the molded body 310, a groove 312 serving as a flow path for inducing molten glass is provided. The molten glass which flowed out from the groove 312 flows down on both sides of the molded body 310 vertically. The molten glass which flowed through the side wall joins at the lower end 313 of the molded object 310 shown in FIG. 3, and one glass ribbon G is shape | molded. As a result, the glass ribbon G flows toward the slow cooling path 50.

In the vicinity of the lower end 313 of the molded body 310, an atmosphere partition member 320 is provided. The atmosphere partition member 320 is a pair of plate-shaped heat insulation members, and is comprised so that the glass ribbon G may be clamped from both sides of the thickness direction. That is, the clearance gap is provided in the atmosphere partition member 320 so that it may not contact with glass ribbon G. As shown in FIG. The atmosphere partition member 320 partitions the inner space of the molding furnace, thereby blocking the movement of heat between the furnace interior space above the atmosphere partition member 320 and the furnace interior space below.

The cooling roller 330 is provided below the atmosphere partition member 320. The cooling roller 330 contacts the surface of the glass ribbon G near the both ends of the width direction of the glass ribbon G, and pulls the glass ribbon G downward to draw the glass ribbon G having a desired thickness. At the same time, the vicinity of both ends of the glass ribbon G is cooled. A cooling unit 340 is provided below the cooling roller 330. The cooling unit 340 cools the glass ribbon G passed through the cooling roller 330. The cooling unit 340 has an air amount adjustment part, for example, and the air amount for air-cooling both ends of a glass ribbon is adjustable by the control apparatus 600 mentioned later. In addition, the drive of the cooling roller 330 can be adjusted via the motor which is not shown in figure.

Below the cooling unit 340, conveying rollers 350a to 350h are provided at predetermined intervals to pull the glass ribbon G downward. The space below the cooling unit 340 serves as the furnace interior space of the slow cooling furnace 50. The conveyance rollers 350a to 350h are all adjustable via a motor not shown.

The pressure sensor 355 which measures the atmospheric pressure of the furnace internal space is provided in the furnace internal space of the shaping furnace 40. The pressure sensor 355 is provided at the same position as the molded body 310 in the height direction (vertical upper direction). The height direction refers to the left direction of the ground in FIG. 3 and the upper direction of the ground in FIG. 4. Since glass ribbon G flows vertically downward from the molded object 310, the flow direction of glass ribbon G is a direction opposite to a height direction. Pressure sensors 360a to 360c are provided in the furnace internal space of the slow cooling furnace 50.

Moreover, in the furnace interior space of the shaping | molding furnace 40, the temperature adjustment units 370a-370c which arrange | positioned the some heating source along the width direction of the glass ribbon G are provided along the glass ribbon G. As shown in FIG. The heating temperature of each heating source of the temperature adjusting units 370a to 370c is adjustable.

On the other hand, in the outer side of the furnace wall of the shaping | molding furnace 40, the space partitioned by the partition of the building B with respect to an atmospheric pressure atmosphere by the partition, ie furnace outer spaces S1, S2, S3a-S3c, is provided. Each of these spaces is partitioned by the bottom surfaces 411, 412, 413a to 413c in the height direction. That is, the shaping | molding apparatus 300 is installed in the building B which has several floor, and the furnace exterior space (partial space) S1, S2, S3a-S3c divided into several by the floor surface is installed in each floor. It is. Further, below the furnace outer space S3c, a space S4 (glass ribbon cutting space) partitioned by a wall on the floor 414 is provided. In addition, a space S5 (early cut space) partitioned by a wall on the floor 414 is provided adjacent to the space S4 on the side of the space S4. The furnace walls are not provided in the spaces S4 and S5. The air pressure in these spaces is adjusted by the blowers 421, 422, 423a, 423b, 423c, 424, and 425 mentioned later, respectively.

The furnace outer space S1 is a space vertically above the position in the height direction of the formed body 310 and the furnace outer space S1 is provided with a pressure sensor 415 for measuring the atmospheric pressure of the furnace outer space.

The furnace outer space S2 is a space provided on the bottom surface 412, and the molded body 310 is disposed in the furnace inner space corresponding to the space. In addition, a pressure sensor 416 for measuring the air pressure in the furnace outer space S2 is provided in the furnace outer space S2. In the furnace interior space enclosed by the furnace wall, the pressure sensor 355 which measures the atmospheric pressure of the furnace interior space is provided in the same position of the height direction of the pressure sensor 416.

The furnace external spaces S3a to S3c are spaces provided below the furnace external space S2 in the order of the furnace external spaces S3a to S3c from the higher side in the height direction. The furnace outer spaces S3a to S3c are provided on the bottom surfaces 413a to 413c. Further, in each of the furnace external spaces S3a to S3c, pressure sensors 417a to 417c for measuring the air pressure in the furnace external spaces 3a to 3c are provided. In the furnace interior space enclosed by the furnace walls, pressure sensors 360a to 360c for measuring the air pressure in the furnace interior space are provided at the same position in the height direction of the pressure sensors 417a to 417c.

In addition, in this embodiment, although pressure sensors 355 and 360a-360c are provided in each position of a furnace internal space, the pressure sensor may be inserted in each position of a furnace internal space, and pressure measurement may be performed. In addition, the measuring method of the differential pressure between a furnace outer space and an furnace internal space is not specifically limited, As an example of the measuring method of a differential pressure, it can measure using a differential pressure meter. In addition, the differential pressure between each of the furnace external spaces S2, S3a to S3c, S4 and S5 can also be measured using a differential pressure gauge.

In each of the spaces S4 and S5, pressure sensors 418 and 419 for measuring the air pressure in the spaces S4 and S5 are provided. Moreover, the communication hole (not shown) which communicates with the spaces S4 and S5 in the wall 420 which partitions the spaces S4 and S5 in order to convey the glass plate G1 in space S4 to space S5 is shown. ) Is formed. That is, the spaces S4 and S5 can be vented through the communication hole.

The size of this communication hole is as small as possible in order to reduce the inflow amount of the particle | grains (cutting chips, dust, etc.) of the glass which generate | occur | produces at the time of cut | disconnecting the ear | edge part G2 in space S5 to space S4, For example, the main surface of glass plate G1 is formed in the size which can convey glass plate G1 to space S5 in the state along the conveyance direction from space S4 to space S5. It is preferable.

Moreover, when glass plate G1 is conveyed from space S4 to space S5 in the state fixed by the conveying apparatus (not shown), the part which is not contained in a product among glass plates G1, for example The glass plate G1 may be conveyed by holding both sides of the thickness direction of the glass plate G1 in the upper end part, the lower end part, or the four sides part of the main surface, etc. of the glass plate G1. In this case, since the part contained in a product of glass plate G1, for example, the center part of the main surface of glass plate G1, etc. is not hold | maintained by the conveying apparatus, from the space S5 to the space S4. When there is much air inflow amount, the said part may be wheeled by the air which flows into space S4 from space S5 at the time of conveyance of glass plate G1. On the other hand, in this embodiment, since the air pressure of space S4 and space S5 is adjusted as mentioned later, it is possible to prevent the air of space S5 from flowing into the air of space S4. . For this reason, even when glass plate G1 is conveyed in the state which only the part which is not contained in a product among glass plate G1 is hold | maintained, generation | occurrence | production of the curvature of glass plate G1 can be suppressed. Moreover, by using the said conveyance method, the structure of a conveying apparatus can be simplified, and the conveyance efficiency of glass plate G1 can be improved.

Moreover, outside of the partition partition which partitions each of furnace outer spaces S1, S2, S3a-S3c, space S4, and space S5, furnace outer spaces S1, S2, S3a-S3c, space S4. And blowers 421, 422, 423a, 423b, 423c, 424, and 425 are provided for each of the spaces S5. The air sent from the atmospheric pressure by each blower is supplied to each of the furnace external spaces S1, S2, S3a to S3c, the space S4, and the space S5 through the pipe. The quantity of air which each blower sends is determined by the drive signal from the drive unit 510 mentioned later, respectively.

5 is a schematic diagram of a control system for controlling the amount of air sent by the blowers 421, 422, 423a, 423b, 423c, 424, 425.

The control system includes pressure sensors 355 and 360a to 360c provided in the furnace inner space, pressure sensors 415 and 416 and 417a to 417c and 418 and 419 provided in the furnace outer space, and the control device 600. And a drive unit 610 and blowers 421, 422, 423a, 423b, 423c, 424, 425.

The control apparatus 600 measures the measurement result of the air pressure in the furnace internal space sent from each pressure sensor provided in the furnace internal space, and the air pressure in the furnace outside space sent from each pressure sensor provided in the furnace external space. Using the result, a control signal is generated to adjust the amount of air sent by each blower so that the difference in air pressure at the same position in the height direction in the furnace interior space and the exterior space of the furnace is adjusted to a set range. . The generated control signal is sent to the drive unit 610. In addition, the quantity of air sent by each blower may be adjusted so that the air pressure reference range may be included in the range of the said reference value, for example, previously setting the range of the air pressure reference value for each of the outside spaces of each furnace. .

The drive unit 610 generates a drive signal for individually adjusting the amount of air sent by the blower based on the control signal. The drive unit 610 sends a drive signal for each blower.

In addition, the control device 600 is electrically connected to the cooling unit 340, the temperature adjusting units 370a to 370c, the cooling roller 330, and the conveying rollers 350a to 350h via the drive unit 610. . The control device 600 controls the heating temperature of the cooling unit 340 via the drive unit 610, adjusts the heating temperature of the heating source of the temperature adjusting units 370a to c, and adjusts the heating temperature of the cooling roller 330. The drive and the temperature are adjusted, and the drive of the conveying rollers 350a to h can be adjusted.

Although the control apparatus 600 and the drive unit 610 automatically control the sending amount of air in this embodiment, an operator may adjust the sending amount of air in a manual. In addition, although this embodiment demonstrated the case where air pressure control is performed using a blower as an example of the air pressure control method, the air pressure control method is not limited only to this method. For example, pressure control may be performed using a dust collector (not shown) which collects dust by sucking particles of glass or the like generated at the time of cutting the glass. The dust collector is provided near each of the glass ribbon cutting device 400 in the space S4 and the ear cutting device 500 in the space S5, and sucks air in the space S4 and the space S5. It is comprised so that dust and the like of the glass contained in the air can be collected. Here, the air pressure of the space S4 and the space S5 can be controlled by controlling the suction amount of the air by the dust collector in each of the space S4 and the space S5. In addition, the atmospheric pressure control of space S4 and space S5 may be performed combining a blower and a dust collector.

Moreover, as a factor which degrades the surface quality of a glass plate, the particle | grains (glass cutting chips, dust, etc.) of glass adhering to a glass plate in the manufacturing process of a glass plate are mentioned. The glass ribbon after a slow cooling process is cut | disconnected to a desired size in the glass ribbon cutting chamber arrange | positioned under the slow cooling furnace, and a glass plate is formed. Moreover, the ear | edge part which has thickness larger than the center part of the width direction of the glass plate is formed in the both ends of the width direction of a glass plate. This ear | edge part is cut | disconnected in an ear | edge cutting chamber, after a glass plate is conveyed to the ear | edge cutting chamber which adjoinably adjoins a glass ribbon cutting chamber. Here, the particle | grains of the glass which generate | occur | produce when an ear | edge part is cut | disconnected in an ear | edge cutting chamber, and the particle of this glass may flow into the glass ribbon cutting chamber adjacent to an ear | edge cutting chamber.

For this reason, in this embodiment, the quantity of the air which blowers 424 and 425 send is adjusted in each space so that the air pressure of space S4 may become high with respect to the air pressure of space S5. When the air pressure in the space S4 is lower than the air pressure in the space S5, air may flow from the communication hole toward the space S4 from the space S5. At this time, since the air flowing into the space S4 includes particles of glass scattering in the space S5, when the air in the space S4 is moved toward the furnace inner space again located upward by the rising airflow. There is a fear that particles of glass may adhere to the glass ribbon G. By raising the air pressure in the space S4 to the air pressure in the space S5, the air in the space S5 including the glass particles can be prevented from entering the air in the space S4, so the space S4 Even when the air in the air is moved upward in the upward airflow, particles of the glass can be prevented from adhering to the glass ribbon G. For this reason, deterioration of the surface quality of glass plate G1 can be suppressed.

The difference in air pressure between the space S4 and the space S5 is more than 0 to 40 Pa, preferably 1 to 35 Pa, more preferably 2 to 30 Pa, still more preferably 3 to 25 Pa, 4 to 4 It is more preferable that it is 15 Pa. When the difference in the air pressure exceeds the above range, a large amount of air may flow from the communication hole toward the space S5 from the space S4. In this case, in the glass plate G1 conveyed from the space S4 to the space S5, vibration or warpage generate | occur | produce by the said air, and there exists a possibility that glass plate G1 may be damaged during conveyance. By adjusting the difference of atmospheric pressure to the said range, the vibration or curvature which generate | occur | produces in the glass plate G1 during conveyance can be suppressed. Therefore, since the number of glass plates G1 damaged during conveyance can be reduced, the manufacturing efficiency of glass plate G1 can be improved.

In addition, the amount of air sent by each blower is adjusted so that the air pressure in the furnace outer spaces S2 and S3a to S3c is lowered with respect to the air pressure in the furnace inner space at the same position in the height direction. do.

The difference in air pressure between the furnace inner space and the furnace outer space S2 of the forming furnace 40 is more than 0 to 40 Pa, preferably 4 to 35 Pa, more preferably 8 to 30 Pa, more preferably 10 to More preferably, it is 27 Pa, and it is more preferable that it is 10-25 Pa. When the difference in the air pressure exceeds the above range, a large amount of air may flow out of the furnace wall gap from the furnace internal space toward the furnace external space S2, thereby increasing the rise of air in the furnace internal space. On the other hand, when the difference of the atmospheric pressure is less than the above range, air may flow from the furnace wall space toward the furnace interior space from the furnace exterior space S2, and there is a fear that temperature fluctuations in the furnace interior space occur. By adjusting the difference of the atmospheric pressure to the above range, it is possible to prevent the low-temperature air from flowing into the furnace interior space of the forming furnace 40 from the furnace exterior space S2. For this reason, temperature fluctuations in the furnace internal space can be suppressed. That is, only the part which contacted the air which flowed in the shaping | molding furnace 40 among the molten glass or the glass ribbon G can be prevented from being quenched. For example, when molten glass and glass ribbon G are locally quenched in the shaping | molding furnace 40, the viscosity of the quenched part will become high and glass ribbon G will be conveyed to a roller downstream of a conveyance path | route. When it increases, the part which the viscosity became high cannot fully be extended, and the problem of causing the deviation of the plate thickness of a glass plate arises. In response to this problem, by adjusting the range of the atmospheric pressure to the above range, the variation in the cooling rate and further the variation in the plate thickness of the glass ribbon G can be suppressed.

On the other hand, the air pressure difference between the furnace inner space of the slow cooling furnace 50 and the furnace outer spaces S3a to S3c is more than 0 to 40 Pa, preferably 2 to 35 Pa, more preferably 2 to 25 Pa. , 3 to 23 Pa is more preferable, and it is more preferable that it is 5 to 20 Pa. When the difference in air pressure exceeds the above range, a large amount of air may flow out of the furnace wall from the furnace interior space toward the furnace exterior spaces S3a to S3c, thereby increasing the rise of air in the furnace interior space. Let's do it. On the other hand, when the difference in the atmospheric pressure is less than the above range, air may flow from the furnace wall space toward the furnace interior space from the furnace exterior spaces S3a to S3c, and the temperature distribution of the furnace interior space changes. By adjusting the difference in air pressure within the above range, it is possible to prevent the inflow of low-temperature air from the furnace outer spaces S3a to S3c into the furnace inner space of the slow cooling furnace 50, thereby suppressing temperature variations in the furnace inner space. have. Thereby, the deviation of the deformation | transformation, curvature, and heat shrinkage of the glass ribbon G can be suppressed.

Hereinafter, the problem caused by the temperature variation of the furnace internal space will be described in detail. In the slow cooling furnace 50, in order to suppress the curvature of the glass ribbon G, etc., the temperature profile of the width direction of the glass ribbon G is controlled. Specifically, in the conveyance area | region where the temperature of the center part of the width direction of glass ribbon G becomes more than (slow cooling point temperature +5 degreeC) in the conveyance area | region of glass ribbon G, the width direction of glass ribbon G of The temperature of the glass ribbon G is controlled so that temperature may become high from the both ends to the center part of the width direction. In addition, in the conveyance area | region where the temperature of the center part of the width direction of glass ribbon G becomes more than (slow cooling point temperature +5 degreeC), as the glass ribbon G is conveyed downstream, the width of glass ribbon G is The temperature of the glass ribbon G is controlled so that the temperature difference between the center part of a direction and the both ends of a width direction may become small. By controlling the temperature profile in this way, since a tensile stress (tension) can always be applied to the center portion of the width direction of the glass ribbon G, the occurrence of warpage of the glass ribbon G can be suppressed. However, in the conveyance area | region where the temperature of the center part of the width direction of the glass ribbon G becomes more than (cool point temperature +5 degreeC) in the conveyance area | region of glass ribbon G, glass ribbon G by inflow of low temperature air, etc., for example. ) Is locally quenched, the temperature profile cannot be realized, causing a problem that warpage occurs in the glass ribbon G.

Moreover, in the conveyance area | region where the temperature of glass ribbon G becomes (strain point temperature -50 degreeC) from (slow cooling point temperature +5 degreeC) in the conveyance area | region of glass ribbon G, the width direction of glass ribbon G is The temperature of the glass ribbon G is controlled so that temperature may become substantially uniform between the both ends of and the center part of the width direction. Thereby, the residual stress of the glass ribbon G can be reduced, and the plane deformation of a glass plate can be reduced. Moreover, the heat shrink of a glass plate can be reduced, so that the temperature of glass ribbon G is kept in the range contained in the range of (cooling point temperature +5 degreeC) to (strain point temperature -50 degreeC) for a long time. However, in the conveyance area | region where the temperature of glass ribbon G becomes (strain point temperature +5 degreeC) from (strain point temperature -50 degreeC), when glass ribbon G is locally quenched by the inflow of low temperature air, etc., for example Since the plane strain occurs in the quenched portion, or the heat shrinkage ratio of the portion increases, a problem arises in that the plane strain increases or the deviation of the heat shrinkage occurs.

The problem described above is that the temperature difference of the furnace interior space is reduced by adjusting the difference in the atmospheric pressure to the above range and preventing the low temperature air from flowing into the furnace interior space of the slow cooling furnace 50 from the furnace exterior spaces S3a to S3c. By suppressing, it can reduce.

Moreover, in this embodiment, although the air pressure of the furnace external space is adjusted so that the air pressure of all the furnace external spaces becomes lower with respect to the air pressure of the furnace internal space at the same position in the height direction, the air pressure of the furnace external space is adjusted. The air pressure in the furnace outer space may be adjusted so that the air pressure is lowered with respect to the air pressure in the furnace inner space at the same position in the height direction. In this case, in the region between the position in the slow cooling furnace corresponding to the slow cooling point temperature of the glass ribbon G and the position in the slow cooling furnace corresponding to the strain point temperature of the glass ribbon G, the air pressure in the furnace external space is It is preferable to adjust so that it may become low with respect to the air pressure of the furnace internal space in the same position of a height direction. The position corresponding to the slow cooling point temperature is, for example, a position in the height direction of the furnace external space S3a, and the position corresponding to the strain point temperature is, for example, a position in the height direction of the furnace external space S3b. Is in. In this region, the glass ribbon G is a step of solidifying, and most affects the plane deformation and thermal contraction of the glass, thereby efficiently adjusting the air pressure in the region to suppress the inflow of air from the outside space of the furnace, It is preferable to suppress the temperature variation in the furnace interior space.

Moreover, in the furnace outer space in the same position of the height direction corresponding to the area | region where the temperature of glass ribbon G becomes less than (strain point temperature -50 degreeC) in the furnace inner space of the slow cooling furnace 50 By adjusting the air pressure, the inflow of air from the outside space of the furnace can be suppressed, and the temperature variation of this region can be suppressed, and the curvature of the glass ribbon G can be prevented by this suppression. Here, the glass ribbon G is one continuous board until it cuts from the shaping | molding furnace 40. As shown in FIG. Therefore, when the bending shape of glass ribbon G changes in the area | region where the temperature of glass ribbon G becomes less than (strain point temperature -50 degreeC), the glass ribbon of the area | region which becomes (strain point temperature -50C) or more It also affects the heat shrinkage. As described above, that is, by suppressing the temperature variation of the region where the temperature of the glass ribbon G is less than the strain point temperature of -50 ° C, the variation in warpage, plane deformation and heat shrinkage can be suppressed.

Moreover, the pressure sensor 415 in the height direction position which does not have a furnace inner space adjusts the furnace outer space S1 by the blower 421 so that air may not flow into a furnace inner space from the furnace outer space S1. In order to measure the air pressure in the furnace external space S1. The pressure sensor 418 adjusts the atmospheric pressure of the space S4 by the blower 424, and is used for the atmospheric pressure measurement in the space S4. For example, the air pressure in the space S4 is preferably adjusted so that the space S4 becomes lower with respect to the lowest air pressure in the furnace interior space. By adjusting the air pressure in the space S4 as described above, the air flowing from the space S4 into the furnace interior space can be reduced.

In addition, the blowers 421, 422, 423a, 423b, 423c, 424, and 425 send air to the furnace external spaces S1, S2, S3a to S3c, the space S4, and the space S5, thereby providing Although the air pressure is also adjusted high with respect to the atmospheric pressure, increasing the air pressure of these spaces with respect to the atmospheric pressure is a large amount of air and the air in the furnace outside space (S1, S2, S3a to S3c), the space (S4) and the space (S5). In order to prevent particles contained in from flowing out of the outside of the building B, furthermore, to effectively adjust the air pressure in the furnace exterior spaces S1, S2, S3a to S3c, the space S4, and the space S5. .

Moreover, it is preferable that the air pressure in a furnace internal space is controlled so that air pressure may become high, so that the position of a height direction is high. Thus, even if temperature distribution generate | occur | produces in a furnace internal space and distribution generate | occur | produces in air pressure, the air pressure in a furnace external space is adjusted according to this air pressure distribution. This is to prevent air from entering the furnace interior space or leaking air into the furnace exterior space due to the difference between the air pressure of each of the outside space of the furnace and the air pressure of the inside space of the furnace, so that air convection does not occur. For this reason, the pressure sensor is installed in the furnace inner space at the same position in the height direction as the pressure sensor provided in each of the furnace outer space. In this way, when a pressure distribution occurs in the furnace interior space, the difference between the air pressure in the furnace exterior space and the air pressure in the furnace interior space at the same position in the height direction of the furnace exterior space is at the position in the height direction. It is preferable to adjust to change accordingly. For example, a comparison was made between the furnace outer space S2 at the top and the furnace outer space S3c at the bottom of the furnace outer spaces S2, S3a to S3c where the furnace inner spaces exist at the same position in the height direction. At this time, it is preferable that the difference in the air pressure at the uppermost portion is adjusted to be larger than the difference in the air pressure at the lowermost portion. For example, what is necessary is just to set so that the said difference of air pressure may become large as the position of a height direction becomes high. This is because in a furnace interior space in a slow cooling furnace, since the temperature is high, so that the position of a height direction is high, the temperature difference with glass ribbon G when cold air flows in becomes large, and the higher the position of a height direction, This is to prevent the temperature variation of the glass ribbon G from increasing.

Moreover, it is preferable that the air pressure of the furnace outer space becomes higher as the position in the height direction is higher. Thereby, since the magnitude | size of the rising airflow which generate | occur | produces along a furnace wall in a furnace exterior space can be reduced, it can suppress that the temperature of the furnace wall side in a furnace interior space falls locally by the said upward airflow. For this reason, temperature fluctuations in the furnace internal space can be suppressed. In other words, by controlling the air pressure in the furnace outside space so that the air pressure in the outside space of the furnace increases upstream of the flow direction of the glass ribbon G, the temperature fluctuations in the furnace inside space can be suppressed.

Moreover, it is preferable to adjust so that the air pressure of space S4 may become low with respect to the air pressure of the furnace internal space. Thereby, the air of the space S4 containing the particle | grains of the glass which generate | occur | produced at the time of the cutting of the glass ribbon G can be prevented from moving upward by an upward airflow. That is, even if air flows into the space S4 from the space S5, it is possible to prevent particles of the glass contained in the introduced air from moving to the furnace interior space by the rising airflow. For this reason, since the particle | grains of glass can be prevented from adhering to glass ribbon G, it can suppress that the surface quality of glass plate G1 shape | molded by glass ribbon G deteriorates.

In this embodiment, cooling control of glass ribbon G can be performed about each form demonstrated below in shaping | molding space S6 and slow cooling space S7 shown in FIG. Specifically, the cooling units 340, the temperature adjusting units 370a to 370c, and the cooling rollers 330 are temperature-controlled in accordance with the instructions of the control device 600 to cool the glass ribbon G as follows. I can do it.

For example, when the glass ribbon G flows in the slow cooling space S7 downstream using the cooling roller 330 or the conveyance rollers 350a-350h, it is effective in the flow direction of the glass ribbon G. By making tension act, the curvature of the glass ribbon G can be suppressed. Moreover, it can also suppress that wavy deformation | transformation generate | occur | produces in the adjacent area | region adjacent to the part which is supported by each roller of the glass ribbon G, and flows.

In order to effectively exert the tension in the flow direction of the glass ribbon G, for example, in the molding space S6 and the slow cooling space S7, the temperature in the center of the width direction of the glass ribbon S is the softening point of the glass. In the area | region which is more than temperature, the temperature of glass ribbon G is controlled so that the both ends (ear part) of the width direction of glass ribbon G may be lower than the temperature of a center part, and the temperature of a center part may become uniform. Moreover, in the area | region where the temperature of the center part of the width direction of glass ribbon G is less than a softening point temperature, and more than strain point temperature so that the tensile stress of a conveyance direction may act on the center part of the width direction of glass ribbon G, glass ribbon G The temperature of the glass ribbon G is controlled so that the temperature of the temperature distribution (temperature profile) of the width direction of () may become low from a center part to both ends. In addition, in the temperature range where the temperature of the center portion in the width direction of the glass ribbon G becomes the strain point temperature of the glass, the glass ribbon so that the temperature gradient between the both ends (ears) and the center portion in the width direction of the glass ribbon G disappears. The temperature of (G) is controlled. Thereby, the tensile stress of the conveyance direction is applied to the center part of the width direction of the glass ribbon G, and the adjacent area | region adjacent to the part which bends the glass ribbon G and is clamped by the rollers of the lath ribbon G, and flows. It can suppress that a wave-like deformation | transformation arises.

Moreover, in the slow cooling space S7, in the area | region below the strain point temperature of glass, the temperature of the center part of the width direction of glass ribbon G is acting on the conveyance direction tension part in the center part of the width direction of glass ribbon G. The temperature of the glass ribbon G may be controlled so that the temperature of the temperature distribution (temperature profile) of the glass ribbon G is lowered from both ends in the width direction toward the center of the width direction of the glass ribbon G. . Thereby, in the area | region below the strain point temperature vicinity of the center part of the width direction of glass ribbon G, tensile stress can always be applied to a conveyance direction in the center part of the width direction of glass ribbon G, and glass ribbon G ) Warpage can be suppressed.

In this embodiment, by adjusting the cooling rate of the molded glass ribbon G, the deformation | transformation of a glass plate can be suppressed, curvature can be suppressed, and the absolute value of a thermal contraction rate can be further reduced.

Specifically, in the slow cooling space S7, when cooling the glass ribbon G while conveying the glass ribbon G using the conveying rollers 350a to 350h, from the temperature obtained by adding 150 ° C to the slow cooling point temperature of the glass ribbon G. The temperature range from the strain point temperature of the glass ribbon G to the temperature minus 200 ° C is determined. At this time, in at least the said temperature range, the cooling rate of the center part of the width direction of glass ribbon G is faster than the cooling rate of the both ends of glass ribbon G, and the temperature of the center part of the width direction of glass ribbon G is a glass ribbon. It is preferable to change the glass ribbon G from the state higher than the both ends of (G) to the state where the temperature of a center part is lower than the both ends. Thereby, tensile stress can be made to act in the flow direction of glass ribbon G in the center part of the width direction of glass ribbon G. As shown in FIG. By the tensile stress acting on the flow direction of the glass ribbon G, the curvature of the glass ribbon G and further glass plate can be suppressed further.

Examples of the glass composition of the glass plate used in the present embodiment include the followings.

The content rate display of the composition shown below is the mass%.

SiO ₂ : 50 to 70%,

B ₂ O ₃ : 5 to 18%

Al ₂ O ₃ : 0-25%,

MgO: 0 to 10%,

CaO: 0-20%,

SrO: 0-20%,

BaO: 0 to 10%,

It is preferable that it is an alkali free glass containing RO: 5 to 20% (However, R is at least 1 sort (s) chosen from Mg, Ca, Sr, and Ba, and a glass plate is contained.).

Moreover, in this embodiment, although it was set as the alkali free glass, the glass plate may contain the trace amount of alkali metal. When the alkali metal is contained, the total of R ' ₂ O exceeds 0.20% and 2.0% or less (wherein R' is at least one selected from Li, Na, and K, and a glass plate is included). desirable. Moreover, in order to make melting of a glass easy, it is more preferable that content of iron oxide in glass is 0.01 to 0.2% from a viewpoint of reducing specific resistance.

Here, Li ₂ O, Na ₂ O, and K ₂ O are components that may elute from the glass and deteriorate the characteristics of the TFT. Therefore, when applied as a glass substrate for a liquid crystal display or a glass substrate for an organic EL display, It is preferable not to include it. However, by incorporating a specific amount of the above components into the glass, the basicity of the glass can be increased while suppressing the deterioration of the characteristics of the TFT, the oxidation of the metal which is hydrolyzed easily, and the clarity can be exhibited. Therefore, the total amount of Li ₂ O, Na ₂ O, K ₂ O is 0 to 2.0%, more preferably 0.1 to 1.0%, still more preferably 0.2 to 0.5%.

In addition, among Li ₂ O, Na ₂ O does not substantially contained in the composition, it is preferable to contain to deteriorate the characteristics of the TFT by elution from the glass is difficult K ₂ O. The content of K ₂ O is 0 to 2.0%, more preferably 0.1 to 1.0%, still more preferably 0.2 to 0.5%.

This embodiment is suitable for manufacture of the glass plate whose thickness of a glass plate is 0.05 mm-1.5 mm. Here, the thinner the glass plate, the easier it is to bend by the flow of air generated by the air pressure difference, so that it is difficult to convey it stably. Therefore, the glass plate which is 0.05-0.5 mm in thickness of the glass plate damaged during conveyance by applying the method of this embodiment which set the atmospheric pressure difference within the predetermined range between the space S4 and the space S5. The effect of reducing the number is great.

The length of the width direction of the glass plate of this embodiment is 500 mm-3500 mm, for example, and the length of the longitudinal direction of a glass plate is 500 mm-3500 mm, for example.

In addition, when the glass plate is enlarged, the glass plate tends to bend due to the flow of air generated by the air pressure difference, so that it is difficult to convey the glass plate stably. Therefore, by applying the method of this embodiment which set the atmospheric pressure difference between the space S4 and the space S5 to the predetermined range, the effect of reducing the number of glass plates which are broken during conveyance is large. Moreover, the effect of this embodiment becomes remarkable so that the length of the glass plate becomes 2000 mm or more in width direction. Specifically, this embodiment is suitable for manufacture of the glass plate of 2000 mm-3500 mm in length of the width direction, and 2000 mm-3500 mm in length of the longitudinal direction.

<Examples>

In order to confirm the effect of this embodiment, the manufacturing method of the glass plate was variously changed, the glass plate was manufactured, and also the degradation evaluation of the surface quality of a glass plate, and the damage evaluation at the time of conveyance of the glass plate were performed.

Here, the deterioration evaluation of the surface quality of a glass plate determines the ratio of the glass plate in which the flaw which contained the bubble and a microprotrusion occurred in the surface among the glass plates shape | molded in the glass ribbon cutting space, and the value of a comparative example is "1.0". It is the numerical value obtained as a ratio with respect to a comparative example when it did. The number of samples of the evaluated glass plate is 1000 sheets, respectively. In evaluation, when a normal inspection was performed and there was a flaw in one place, it was regarded as a rejected product, and the ratio of the glass plate in which the scratch occurred was calculated by counting the number of glass plates of the rejected product. That is, when the evaluation of deterioration of the surface quality of a glass plate is a value less than 1.0, it turns out that the number of glass plates in which a scratch generate | occur | produces on a surface is reduced rather than a comparative example.

In addition, about the damage evaluation at the time of conveyance of a glass plate, the glass plate conveyed from a glass ribbon cutting space to an ear | edge cutting space is damaged by the vibration and the warpage which generate | occur | produced by the air pressure difference between a glass ribbon cutting space and an ear | edge cutting space. It evaluated as "good" when the ratio of the prepared glass plate was less than the predetermined value, and evaluated as "possible" when it was more than the said predetermined value.

1. First Embodiment

After melt | dissolving, clarifying, and stirring a glass raw material, the glass ribbon was shape | molded using the overflow down draw method and was annealed. And the glass ribbon was cut | disconnected in the glass ribbon cutting space, and the ear | edge was cut | disconnected in the ear | edge cutting space. At this time, the air pressure of the glass ribbon cutting space and the ear cutting space was adjusted so that the air pressure of the glass ribbon cutting space was higher than the air pressure of the ear cutting space and the pressure difference was 5 Pa.

The manufactured glass plate is a glass substrate for liquid crystal displays, a size is 2200 mm x 2500 mm, and thickness is 0.7 mm. The glass composition of the glass plate was as follows.

Content rate is mass%.

SiO ₂ : 60%

Al ₂ O ₃ : 19.5%

B ₂ O ₃ : 10%

CaO: 5.3%

SrO: 5%

SnO ₂ : 0.2%

2. Second Embodiment

The glass substrate for liquid crystal display was manufactured by the method similar to Example 1 except the air pressure of the glass ribbon cutting space being higher than the air pressure of the ear cutting space, and whose pressure difference is 25 Pa.

3. Third Embodiment

The glass substrate for liquid crystal display was manufactured by the method similar to Example 1 except the air pressure of the glass ribbon cutting space being higher than the air pressure of the ear cutting space, and the air pressure difference being 35 Pa.

4. Fourth Embodiment

The glass substrate for liquid crystal display was manufactured by the method similar to Example 1 except the air pressure of the glass ribbon cutting space being higher than the air pressure of the ear cutting space, and the air pressure difference being 40 Pa.

5. Fifth Embodiment

The glass substrate for liquid crystal display was manufactured by the method similar to Example 1 except the air pressure of the glass ribbon cutting space being higher than the air pressure of the ear cutting space, and the air pressure difference being 45 Pa.

6. Comparative Example

The glass substrate for a liquid crystal display in the same manner as in the first embodiment except that the air pressure difference between the glass ribbon cutting space and the ear cutting space is -5 Pa (that is, the air pressure of the glass ribbon cutting space is lower than that of the ear cutting space). Was carried out.

Table 1 below is an evaluation result when the degradation evaluation of the surface quality of a glass plate was calculated | required about the 1st Example-5th Example and a comparative example. Further, in the first to fifth embodiments and comparative examples, in order to prevent the generation of upward airflow from the glass ribbon cutting space toward the furnace interior space along the glass ribbon, the glass ribbon cutting space and the furnace interior space; Control was performed so that the air pressure difference between

The following Table 2 is a result of the damage evaluation at the time of conveyance of a glass plate about 1st Example-5th Example.

In the above Table 1, when the air pressure in the glass ribbon cutting space is higher than the air pressure in the ear cutting space, the value of the degradation evaluation of the surface quality of the glass plates of the first to fifth embodiments is lower than the value of the degradation evaluation of the comparative example. Therefore, it is apparent that the surface quality of the glass plate is improved. Moreover, it is clear from Table 2 that when the air pressure in the cutting space is higher than the air pressure in the ear cutting space, and the air pressure difference is 40 Pa or less, the number of glass plates broken during transportation can be reduced. As mentioned above, the effect of the method of this embodiment is clear.

Moreover, also in manufacture of the glass plate which has a glass composition (mass% display) shown below containing a trace amount of alkali metal, the same result as the above was obtained.

SiO ₂ : 61%,

Al ₂ O ₃ : 19.5%,

B ₂ O ₃ : 10%,

CaO: 9%

SnO ₂ : 0.3%,

R ₂ O (R is all the components contained in the glass plate in Li, Na, K): 0.2%

As mentioned above, although the manufacturing method of the glass plate of this invention and the manufacturing apparatus of a glass plate were explained in full detail, this invention is not limited to the said embodiment, A large improvement in the range which does not deviate from the main point of this invention, Of course, you can change it.

30: no
40: forming furnace
50: slow cooling
200: dissolution device
201: dissolution tank
202: clarification
203: Stirring Tank
204: first pipe
205: second pipe
300: forming apparatus
310: molded article
311 supply port
312: Home
313: lower end
320: atmosphere partition member
330: cooling roller
340: cooling unit
350a to 350h: conveying roller
355, 360a, 360b, 360c, 415, 416, 417a, 417b, 417c, 418, 419: pressure sensor
400: cutting device
411, 412, 413a, 413b, 413c, 414: bottom surface
421, 422, 423a, 423b, 423c, 424, 425: blower
500: Ear cutting device
600: control unit
610: drive unit

Claims (5)

As a manufacturing method of the glass plate by the down draw method,
A dissolution step of melting the glass raw material to obtain a molten glass;
A molding step of molding the glass ribbon by supplying the molten glass to a molded body provided in the molding furnace;
A slow cooling step of pulling the glass ribbon with a roller provided in the slow cooling furnace to cool the inside of the slow cooling furnace;
A glass ribbon cutting step of cutting the cooled glass ribbon in a glass ribbon cutting space;
Ear cutting process which cut | disconnects the ear | edge part formed in the both ends of the width direction of the said cut glass ribbon in an ear | edge cutting space.
/ RTI &gt;
So that the air pressure of the glass ribbon cutting space is increased with respect to the air pressure of the ear cutting space,
At least one air pressure of the glass ribbon cutting space and the ear cutting space is adjusted
A method for producing a glass plate, characterized in that. The glass plate of Claim 1 in which the air pressure of at least one of the said glass ribbon cutting space and the said ear cutting space is adjusted so that the difference of the air pressure of the said glass ribbon cutting space and the air pressure of the said ear cutting space may be 40 Pa or less. Method of preparation. The air pressure of the glass ribbon cutting space is the inside of the furnace when the inner space of the molding furnace in which the molded body is installed and the inner space of the slow cooling furnace in which the roller is installed are furnace interior spaces. The air pressure of the said glass ribbon cutting space is adjusted so that it may become low with respect to the air pressure of the space, The manufacturing method of the glass plate. As a manufacturing apparatus of the glass plate by the down draw method,
A melting tank for melting a glass raw material to obtain a molten glass,
A molding furnace for supplying the molten glass to a molded body provided in the molding furnace to form a glass ribbon;
A slow cooling furnace which pulls the said glass ribbon with the roller provided in the slow cooling furnace, and cools in the said slow cooling furnace,
A glass ribbon cutting device for cutting the cooled glass ribbon in a glass ribbon cutting space;
An ear cutting device which cuts the ear | edge part formed in the both ends of the width direction of the said glass ribbon cut | disconnected in an ear | edge cutting space,
So that the air pressure of the glass ribbon cutting space is increased with respect to the air pressure of the ear cutting space,
Adjusting means for adjusting the air pressure of at least one of the glass ribbon cutting space and the ear cutting space
An apparatus for producing a glass plate, characterized by including a. The method according to claim 4, wherein the adjusting means,
In the glass ribbon cutting space and the ear cutting space, a pressure sensor for measuring the pressure of air pressure, a blower for sending air from the atmosphere into the glass ribbon cutting space and the ear cutting space, and the glass ribbon cutting space and the ear cutting space An apparatus for manufacturing a glass plate, comprising: at least one of the dust collectors that attract and collect the air inside and a control device that adjusts the apparatus in accordance with a measurement result of the pressure sensor.

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