JP2021109817A - Float glass manufacturing device and float glass manufacturing method - Google Patents

Abstract

To provide a float glass manufacturing device that can prevent a sheet part of a drape which is disposed in a dross box from deforming, and to provide a float glass manufacturing method.SOLUTION: A float glass manufacturing device includes a float bath 10, a slow cooling furnace 20 and a dross box 30. The dross box 30 includes a drape 6 in an upper part of multiple lift-out rolls 4 for transporting a glass ribbon G. The drape 6 includes: a sheet part; and a frame part for nipping an upper part of the sheet part. The sheet part is formed of a material which is a non-metal material with a bend elastic modulus of 20 GPa or more at room temperature.SELECTED DRAWING: Figure 1

Description

The present invention relates to a float glass manufacturing apparatus and a float glass manufacturing method.

The float glass manufacturing apparatus includes a float bath for accommodating the molten metal, a slow cooling furnace for carrying a glass ribbon formed in a strip shape on the molten metal, and a dross box provided between the float bath and the slow cooling furnace. ..

Inside the dross box, drapes are placed on top of a plurality of lift-out rolls that carry the glass ribbon. The drape functions to prevent the pressure in the dross box and the float bath from fluctuating, and to prevent oxygen in the slow cooling furnace and SO ₂ gas supplied into the slow cooling furnace from entering the dross box and the float bath.

The drape is in a state where the surface on the upstream side in the transport direction of the glass ribbon is constantly under the atmospheric pressure from the float bath. Therefore, with the passage of time, the surface of the drape on the downstream side in the transport direction of the glass ribbon swells and deforms, and the drape may not sufficiently perform the above-mentioned function.

Therefore, in order to prevent the drape from being deformed, a drape having a frame portion and a corrugated iron plate portion and a reinforcing means provided on the downstream side in the transport direction of the glass ribbon has been proposed (see Patent Document 1). .. Here, the corrugated iron plate portion (corresponding to the seat portion of the present invention) is a corrugated iron plate made of stainless steel and having a corrugated shape, and a thin corrugated iron plate having a thickness of 0.1 mm to 0.2 mm is used and has a certain degree of rigidity. And it is lightweight.

JP-A-2016-204248

However, since the ambient temperature inside the dross box is 550 ° C. or higher, the stainless steel corrugated iron plate of Patent Document 1 has a phenomenon in which chromium and carbon contained in stainless steel combine to generate chromium carbides at grain boundaries (so-called grain boundaries). Due to (sensitization), corrosion tends to proceed along the grain boundaries. Then, since oxygen and SO ₂ gas in the slow cooling furnace enter into the dross box, the corrugated iron plate may be deformed due to a decrease in rigidity due to corrosion of _{oxygen and SO 2.}

The present invention has been made in view of the above problems, and an object of the present invention is to provide a float glass manufacturing apparatus and a float glass manufacturing method capable of preventing deformation of a drape sheet portion arranged in a dross box.

In order to solve the above problems, the float glass manufacturing apparatus of the present invention includes a float bath for accommodating molten metal, a slow cooling furnace in which a glass ribbon formed in a strip shape on the molten metal is carried in, and the float bath. A float glass manufacturing apparatus provided with a dross box provided between the slow cooling furnace, wherein the dross box has a drape on the upper part of a plurality of lift-out rolls for carrying the glass ribbon. It has a sheet portion and a frame portion that sandwiches the upper portion of the sheet portion, and the material of the sheet portion is a non-metallic material having a bending elasticity of 20 GPa or more at room temperature.

Further, in the float glass manufacturing method of the present invention, a strip-shaped glass ribbon is formed on the molten metal of the float bath, the glass ribbon is pulled out from the float bath by a lift-out roll provided in a dross box, and a slow cooling furnace is used. A method for producing float glass in which the glass ribbon is slowly cooled, the dross box has a drape on the upper part of a plurality of lift-out rolls for conveying the glass ribbon, and the drape has a sheet portion and the sheet portion. The sheet portion is made of a non-metallic material having a bending elasticity of 20 GPa or more at room temperature.

According to the float glass manufacturing apparatus and the float glass manufacturing method of the present invention, it is possible to prevent deformation of the sheet portion of the drape arranged in the dross box.

It is a partial cross-sectional view of the float glass manufacturing apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the drape of FIG. 1, (A) is a cross-sectional view taken along the line I-I of (B) and (C), (B) is a front view of the drape, and (C) is (A). ) Is a cross-sectional view taken along the line II-II.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each drawing, the same or corresponding configurations are designated by the same or corresponding reference numerals and the description thereof will be omitted. In the present specification, "~" representing a numerical range means a range including numerical values before and after the range. In the following description, the "upstream side" refers to the upstream side in the transport direction of the glass ribbon, and the "downstream side" refers to the downstream side in the transport direction of the glass ribbon.

(Float glass manufacturing equipment)
A float glass manufacturing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a partial cross-sectional view of a float glass manufacturing apparatus according to an embodiment of the present invention.

The float glass manufacturing apparatus 1 is located between a float bath 10 accommodating a molten metal M, a slow cooling furnace 20 into which a glass ribbon G formed in a strip shape on the molten metal M is carried, and the float bath 10 and the slow cooling furnace 20. It is provided with a dross box 30 provided in. The dross box 30 has a drape 6 on top of a plurality of lift-out rolls 4 that convey the glass ribbon G.

The glass ribbon G formed to a desired width and thickness is lifted from the bath surface 12 of the molten metal M by the traction force of the lift-out roll 4 and the transport roll 21. Then, the glass ribbon G is carried into the dross box 30 from the outlet 13 of the float bus 10, then carried into the slow cooling furnace 20 by the lift-out roll 4, and is slowly cooled while being carried by the transport roll 21. After that, the glass ribbon G is carried out of the slow cooling furnace 20, cooled to around room temperature, and then cut to a predetermined size to become a product glass plate.

The glass composition is appropriately selected according to the application of the glass plate and the like. For example, when the glass plate is used as a glass substrate for a liquid crystal display, alkali metal adversely affects the quality of the liquid crystal display. Therefore, alkali-free glass that does not substantially contain alkali metal oxides such as _{Na 2} O and K _{2 O.} Is used. Here, the fact that the alkali metal oxide is substantially not contained means that the total content of the alkali metal oxide is 0.1% by mass or less.

The upper space in the float bath 10 is filled with a reducing mixed gas containing nitrogen and hydrogen in order to prevent oxidation of the molten metal M. Further, the upper space in the float bath 10 is set higher than the atmospheric pressure in order to prevent the inflow of air from the outside. The reducing atmosphere in the float bath 10 flows out from the outlet 13 of the float bath 10 toward the dross box 30. A heater 18 for adjusting the glass ribbon G to a temperature at which it can be plastically deformed is provided near the outlet 13 of the float bath 10. The metal used for the molten metal M is, for example, tin or a tin alloy.

The outlet on the downstream side of the slow cooling furnace 20 is open to the outside. _{Further, SO 2} gas is supplied to the lower surface of the glass ribbon G in the slow cooling furnace 20 to form a buffer film. Therefore, the inside of the slow cooling furnace 20 has an atmosphere containing _{oxygen and SO 2 gas.} The inside of the slow cooling furnace 20 communicates with the inside of the float bath 10 via the inside of the dross box 30.

In the slow cooling furnace 20, a heater 28 and the like are provided in addition to the transfer roll 21. Each of the plurality of transport rolls 21 is rotationally driven by a driving device such as a motor, and the glass ribbon G is transported in the horizontal direction by the driving force.

In the dross box 30, the upper outer wall 31 is covered with the heat insulating material 33, and the lower inner wall 32 is covered with the heat insulating material 34. By using the heat insulating materials 33 and 34, heat dissipation from the dross box 30 can be suppressed, the temperature distribution of the glass ribbon G can be stabilized, and warpage of the product can be suppressed.

In the dross box 30, in addition to the lift-out roll 4, a contact member 5, a drape 6, a heater 8, and the like are provided. Each of the plurality of lift-out rolls 4 is rotationally driven by a driving device such as a motor, and the driving force thereof conveys the glass ribbon G diagonally upward. The number of lift-out rolls is not particularly limited as long as there are a plurality of lift-out rolls.

The contact member 5 is provided below the lift-out roll 4. Each of the plurality of contact members 5 is in sliding contact with the outer peripheral surface of the corresponding lift-out roll 4, and partitions the lower part of the glass ribbon G into a plurality of spaces 35 to 38.

The drape 6 is provided above the glass ribbon G and above the lift-out roll 4 to shield the space above the glass ribbon G. A plurality of drapes 6 are suspended by the outer wall 31 and are provided at intervals in the transport direction of the glass ribbon G. The reducing atmosphere flowing out from the outlet 13 of the float bath 10 flows through the space above the glass ribbon G in the dross box 30 toward the inlet 23 of the slow cooling furnace 20 (exit 39 of the dross box 30).

The drape 6 limits the intrusion of oxygen from the slow cooling furnace 20 and regulates the increase in the oxygen concentration in the dross box 30. As a result, the combustion of hydrogen contained in the reducing atmosphere is suppressed, and the temperature fluctuation and local heating of the glass ribbon G due to the combustion flame of hydrogen can be suppressed. _{Further, the drape 6 limits the invasion of SO 2} gas from the slow cooling furnace 20 and suppresses the reaction of hydrogen contained in the reducing atmosphere in the dross box 30 with SO _{2 to generate H 2 S.} As a result, corrosion of the metal material constituting the furnace shell of the dross box 30 can be suppressed. The drape 6 is arranged so as to be slightly (for example, 1 cm) away from the upper surface of the glass ribbon G so as not to interfere with the transportation of the glass ribbon G.

The plurality of heaters 8 are provided on both the upper and lower sides of the glass ribbon G at intervals, and a plurality of rows of heaters 8 are provided in the transport direction of the glass ribbon G, respectively. The heaters 8 in each row are provided between the drapes 6 and between the contact members 5. The heaters 8 in each row are preferably divided in the width direction of the glass ribbon G in order to make the temperature distribution in the width direction of the glass ribbon G uniform. The atmospheric temperature in the dross box 30 is adjusted to 550 ° C. or higher, although it depends on the glass composition.

The float glass manufacturing apparatus 1 preferably includes a surveillance camera in order to control the height of the drape 6, manage the gap between the drape 6 and the glass ribbon G, detect cracks in the glass ribbon G, and the like. The surveillance camera is provided on the outside of the side wall portion of the dross box 30, and photographs the drape 6 and the glass ribbon G in the dross box 30 from the window of the side wall portion. Then, the image taken by the surveillance camera is subjected to image processing. Thereby, the distance between the drape 6 and the glass ribbon G in the width direction of the glass ribbon G can be measured over time.

Then, by adjusting the height of the drape 6 to keep the distance between the drape 6 and the glass ribbon G constant, the flow rate of the reducing atmosphere flowing through the gap becomes constant, so that the quality of the glass ribbon G can be improved. It can be stabilized.

Further, since the drape 6 can prevent the deformation of the sheet portion as described later, the warp of the glass ribbon G can be quantitatively evaluated by measuring the distance between the drape 6 and the glass ribbon G. As a result, the heater 8 in the dross box 30 can be adjusted at an early stage, so that deterioration of the warp of the float glass can be suppressed.

(drape)
Next, the drapes constituting the float glass manufacturing apparatus will be described with reference to FIG.

FIG. 2 is a schematic configuration diagram of the drape of FIG. 1, (A) is a cross-sectional view taken along the line II of (B) and (C), (B) is a front view of the drape, and (C). ) Is a cross-sectional view taken along the line II-II of (A). Here, FIG. 2B is a front view when the drape is viewed from the upstream side to the downstream side.

As shown in FIG. 2A, the drape 6 has a seat portion 62 and a frame portion 61 that sandwiches the upper portion of the seat portion 62. The drape 6 further includes a bolt 63 for fastening the seat portion 62 and the frame portion 61, and a nut 64 for fixing the bolt 63.

Since the frame portion 61 is suspended by the outer wall 31 (see FIG. 1) above the dross box, the frame portion 61 has frame members 61A and 61B having an inverted L-shaped cross section. The frame material 61A is arranged on the upstream side surface of the seat portion 62, and the frame material 61B is arranged on the downstream side surface of the seat portion 62.

The through holes of the frame materials 61A and 61B are round holes. The through hole of the frame material 61B may be a screw hole. In this case, the bolt 63 can be fixed without the nut 64. This facilitates the work of assembling the drape 6. The through holes of the frame materials 61A and 61B may be elongated holes as in the through holes 65 of the sheet portion 62 (see FIG. 2C), which will be described later. In this case, the frame material 61B and the bolt 63 are fixed by a nut 64, welding, or the like.

The frame materials 61A and 61B are preferably made of stainless steel (SUS304, SUS410, SUS430, etc. described in JIS G4304: 2012) from the viewpoint of heat resistance, workability, strength and the like. The material of the frame materials 61A and 61B is not limited to stainless steel, and may be a non-metal material such as ceramic or carbon material from the above viewpoint. Incidentally, SUS304, SUS410, the thermal expansion coefficient of SUS430 is respectively ^{17.3 × 10 -6 /K,9.9×10 -6 /K,10.4×10 -6} / K.

The thickness of the frame materials 61A and 61B is preferably 2 mm to 10 mm, more preferably 2 mm to 7 mm, still more preferably 2 mm to 4 mm. The heights of the frame materials 61A and 61B are preferably 70 mm to 110 mm, more preferably 80 mm to 100 mm.

The sheet portion 62 has a rectangular shape in the cross section of FIG. 2A. The rectangular shape here includes a shape in which the corners of the rectangle are C-chamfered and a shape in which the corners of the rectangle are R-chamfered (rounded rectangular shape).

The material of the sheet portion 62 is a non-metallic material having a flexural modulus of 20 GPa or more at room temperature. Room temperature is 25 ° C.

If the material of the sheet portion 62 is a non-metal material, even if oxygen and SO ₂ gas in the slow cooling furnace enter the dross box, corrosion due to sensitization of the metal structure does not occur. Therefore, unlike the conventional corrugated iron plate portion, the seat portion 62 does not have a problem that the rigidity is lowered due to the corrosion of _{oxygen and SO 2.} Here, since the non-metallic material has an atmospheric temperature of 550 ° C. or higher in the dross box, it is premised that it has heat resistance that can withstand this.

Further, when the flexural modulus of the non-metallic material at room temperature is 20 GPa or more, the rigidity of the seat portion 62 can be increased, so that the seat portion 62 is not easily deformed even when the pressure of the atmosphere from the float bath is applied. Therefore, the flexural modulus of the non-metallic material at room temperature is preferably 30 GPa or more, more preferably 35 GPa or more.

The non-metal material preferably has a flexural modulus of 100 GPa or less at room temperature. If the flexural modulus is 100 GPa or less, even if the seat portion 62 is deformed, the restoring force of the seat portion 62 can be suppressed, so that the deformation of the outer wall 31 (see FIG. 1) for suspending the drape 6 can be suppressed. .. Therefore, the flexural modulus at room temperature is more preferably 80 GPa or less, further preferably 70 GPa or less, and particularly preferably 65 GPa or less.

The flexural modulus was measured at room temperature using a three-point bending test. When the non-metallic material was a C / C composite, the flexural modulus was measured at room temperature using a JIS K 7078 shear test (test piece: 60 mm × 10 mm × thickness 3 mm). When the non-metallic material was a CIP material, the flexural modulus was measured at room temperature using the method for measuring the flexural strength of JIS R 7222. When the non-metallic material was ceramic, the flexural modulus was measured at room temperature using the static modulus test method of JIS R 1602.

The non-metal material preferably has a bending strength of 90 MPa or more at room temperature. When the bending strength is 90 MPa or more, the sheet portion 62 is less likely to be damaged, and the deformation of the sheet portion 62 can be better prevented. Therefore, the bending strength at room temperature is more preferably 120 MPa or more, and even more preferably 140 MPa or more.

The non-metal material preferably has a bending strength of 300 MPa or less at room temperature. When the bending strength is 300 MPa or less, even if the seat portion 62 is deformed, it is possible to suppress the deformation of the outer wall 31 (see FIG. 1) for suspending the drape 6. Therefore, the bending strength at room temperature is more preferably 270 MPa or less, further preferably 250 MPa or less.

The bending strength is measured in the same manner as the flexural modulus described above.

The non-metallic material preferably has a bulk density of 3 g / cm ³ or less at room temperature. When the bulk density is 3 g / cm ³ or less, the thickness of the seat portion 62 can be increased and the rigidity of the seat portion 62 can be increased without modifying the outer wall 31 (see FIG. 1) at the upper part of the dross box. can. Therefore, the bulk density at room temperature, more preferably not more than 2.5 g / cm ^3, more preferably 2 g / cm ³ or less, 1.7 g / cm ³ or less is particularly preferred. The bulk density was measured at room temperature using the Archimedes method.

The non-metal material preferably has a compressive strength of 90 MPa or more at room temperature. When the compressive strength is 90 MPa or more, the sheet portion 62 is less likely to be damaged, and the deformation of the sheet portion 62 can be better prevented. Therefore, the compressive strength at room temperature is more preferably 120 MPa or more, and even more preferably 140 MPa or more.

The non-metallic material preferably has a compressive strength of 300 MPa or less at room temperature. When the compressive strength is 300 MPa or less, even if the sheet portion 62 is deformed, it is possible to suppress the deformation of the outer wall 31 (see FIG. 1) for suspending the drape 6. Therefore, the compressive strength at room temperature is more preferably 270 MPa or less, and even more preferably 250 MPa or less.

When the non-metallic material was a C / C composite, the compressive strength was measured at room temperature using an in-plane compression test of JIS K 7076. When the non-metallic material was a CIP material, the compressive strength was measured at room temperature using the method for measuring the compressive strength of JIS R 7222. When the non-metallic material was ceramic, the compressive strength was measured at room temperature using the compressive strength test method of JIS R 1608.

The non-metal material preferably has a tensile strength of 90 MPa or more at room temperature. When the tensile strength is 90 MPa or more, the sheet portion 62 is less likely to be damaged and the sheet portion 62 is less likely to be deformed by its own weight. Therefore, the tensile strength at room temperature is more preferably 120 MPa or more, and even more preferably 140 MPa or more.

The non-metal material preferably has a tensile strength of 300 MPa or less at room temperature. When the tensile strength is 300 MPa or less, even if the seat portion 62 is deformed, it is possible to suppress the deformation of the outer wall 31 (see FIG. 1) for suspending the drape 6. Therefore, the tensile strength at room temperature is more preferably 270 MPa or less, and even more preferably 250 MPa or less.

When the non-metal material was a C / C composite, the tensile strength was measured at room temperature using a monofilament test. When the non-metallic material was a CIP material, the tensile strength was measured at room temperature using the method for measuring the tensile strength of JIS R 7222. When the non-metallic material was ceramic, the tensile strength was measured at room temperature using the room temperature tensile strength test method of JIS R 1606.

The non-metallic material is preferably ceramic. Ceramic is suitable as a material for the sheet portion 62 in the dross box because it has excellent heat resistance, rigidity, and the like.

The ceramic is preferably silicon carbide or silicon nitride. Since silicon carbide or silicon nitride is excellent in heat resistance, oxidation resistance, etc., it is suitable as a material for the sheet portion 62 in the dross box in which oxygen enters.

The ceramic is preferably one or more selected from the group consisting of silica, alumina, magnesia, and calcia. Specifically, a ceramic board obtained by molding a ceramic fiber containing silica, magnesia and calcia into a plate shape, mullite containing alumina and silica, and the like are used. Ceramic boards are preferable in that they are excellent in heat resistance, oxidation resistance, processability, etc., and are lightweight. Further, mullite is preferable because it is excellent in heat resistance, heat impact resistance and the like.

The non-metal material is preferably a carbon material. Since the carbon material is excellent in heat resistance, rigidity, workability, etc. and is lightweight, it is suitable as a material for the seat portion 62 in the dross box.

The carbon material is more preferably a CIP material or a C / C composite material. Here, the CIP material is a carbon material formed by using a cold isotropic pressure pressurization method (CIP method). The C / C composite material is a carbon composite material reinforced with high-strength carbon fibers. Both members are excellent in rigidity and workability. In particular, the C / C composite material is excellent in strength and rigidity, and is suitable for preventing deformation of the seat portion. Most of the C / C composite materials have a coefficient of thermal expansion of 1.0 × ^10-6 / K or less in the direction parallel to the fiber.

The carbon material is preferably coated on its outer surface in order to prevent it from being oxidized by oxygen that has entered the dross box. Examples of the coating component include silicon carbide, oxides containing aluminum and phosphorus, and the like. The thickness of the coating is, for example, 10 μm to 1 mm.

The thickness of the sheet portion 62 is preferably 0.8 mm to 15 mm, more preferably 1 mm to 10 mm, further preferably 1 mm to 7 mm, and particularly preferably 1.5 mm to 4 mm. When the thickness of the seat portion 62 is 0.8 mm or more, the rigidity of the seat portion 62 can be increased, so that the deformation of the seat portion 62 can be suppressed. Further, when the thickness of the seat portion 62 is 15 mm or less, the seat portion 62 can be easily molded and processed, and even if the seat portion 62 is deformed, the outer wall 31 (see FIG. 1) for suspending the drape 6 is formed. Deformation can be suppressed.

The height of the seat portion 62 is preferably 250 mm to 500 mm, more preferably 300 mm to 400 mm, depending on the distance between the upper end of the lift-out roll and the lower end of the outer wall 31 (see FIG. 1) of the upper part of the dross box.

It is preferable that the surface of the sheet portion 62 on the upstream side in the transport direction of the glass ribbon is linear in a plan view. Here, the "plane" in the plan view refers to a plane perpendicular to the vertical direction. In the conventional corrugated iron plate portion, since the upstream and downstream surfaces of the glass ribbon in the transport direction have a wavy shape in a plan view, there is a problem that the portion is easily deformed when a strong local pressure is applied. rice field. On the other hand, if the surface on the upstream side in the transport direction of the glass ribbon is linear in a plan view, the pressure is dispersed toward the entire surface on the upstream side even if a strong pressure is locally applied. Deformation of the part can be suppressed.

It is more preferable that the surface of the sheet portion 62 on the downstream side in the transport direction of the glass ribbon is linear in a plan view. As a result, especially when the thickness of the sheet portion 62 is thin, even if a strong pressure is locally applied to the sheet portion 62, the pressure is dispersed toward the entire surface on the upstream side and the downstream side, so that the portion is deformed. Can be suppressed more. Here, the linear shape means that the drape is linear in the state before being installed in the dross box. This is because the seat portion 62 receives the pressure of the atmosphere from the float bath, and therefore, strictly speaking, it cannot be said that the seat portion 62 is linear in a plan view.

The sheet portion 62 preferably has a rectangular cross-sectional shape in a plan view. As a result, the above-mentioned local deformation of the sheet portion 62 can be suppressed, and the sheet portion 62 can be easily molded and processed. The rectangular shape here includes a shape in which the corners of the rectangle are chamfered and a shape in which the corners of the rectangle are chamfered (rounded rectangular shape).

As shown in FIG. 2B, a plurality of bolts 63, which are vertically provided, are provided at intervals in the longitudinal direction of the drape 6. The number of bolts 63 may be three or more at the top and bottom.

The sheet portion 62 has a plurality of sheet materials. Two sheet materials are shown in FIG. 2 (C). This is because the length of the drape 6 in the longitudinal direction is, for example, 5 m or more, and it is difficult to manufacture the sheet portion 62 with one sheet material. It is preferable that the sheet portion 62 is in contact with adjacent sheet materials in the longitudinal direction of the drape 6 so as to withstand the pressure of the atmosphere from the float bath. However, the sheet portion 62 may be provided with a gap between adjacent sheet materials as long as it can withstand the pressure.

Therefore, the drape 6 further includes a joining plate 67 for joining the sheet material in the longitudinal direction of the drape 6, a bolt 68 for fastening the seat portion 62 and the joining plate 67, and a nut for fixing the bolt 68. The joint plate 67 is preferably made of the same material as the sheet portion 62 in order to eliminate the difference in the coefficient of thermal expansion from the sheet portion 62.

The three bolts 68 arranged in a row in the vertical direction are provided at or near the end of the sheet material in the longitudinal direction of the drape 6. The number of bolts 68 arranged in a row in the vertical direction may be two or four or more.

As shown in FIG. 2C, the seat portion 62 further has a through hole 65 through which the bolt 63 is inserted. The through holes 65 are through holes corresponding to the bolts 63, and a plurality of through holes 65 are provided at intervals in the longitudinal direction of the drape 6.

Here, the drape 6 is heated from room temperature to 550 ° C. or higher before starting the production of the float glass. Further, when the drape 6 is replaced after the production of the float glass is started, the newly installed drape 6 is heated from room temperature to 550 ° C. or higher.

Therefore, although the materials of the frame portion 61 and the seat portion 62 constituting the drape are different, if the through hole 65 is a round hole, the seat portion penetrates through the bolt 63 due to the difference in the coefficient of thermal expansion of both materials. Restrained in the hole. Then, the sheet portion is deformed without uniformly expanding in the longitudinal direction of the drape 6 (the width direction of the glass ribbon), and the gap between the lower end of the sheet portion and the glass ribbon becomes non-uniform in the width direction of the glass ribbon.

Therefore, the through hole 65 is preferably an elongated hole having a long side in the longitudinal direction of the drape 6. As a result, even if the materials of the frame portion 61 and the seat portion 62 are different, the seat portion 62 is not restrained by the through hole 65 via the bolt 63 and can move in the longitudinal direction of the drape 6. Therefore, the sheet portion 62 expands without being uniformly deformed in the longitudinal direction of the drape 6 (the width direction of the glass ribbon), and the gap between the lower end of the sheet portion 62 and the glass ribbon becomes uniform in the width direction of the glass ribbon.

On the other hand, the through hole corresponding to the bolt 68 is a round hole. This is based on the premise that the seat portion 62 and the joint plate 67 are made of the same material. Therefore, when the materials of the sheet portion 62 and the joint plate 67 are different, the through hole is preferably a long hole like the through hole 65.

When the sheet portion 62 can be manufactured from one sheet material, the drape does not have the through holes corresponding to the joint plate 67, the bolt 68, the nut 69, and the bolt 68 described above.

(Float glass manufacturing method)
Next, the float glass manufacturing method according to the embodiment of the present invention will be described again with reference to FIGS. 1 and 2.

In the float glass manufacturing method, a glass raw material supplied to a melting kiln (not shown) is heated to obtain molten glass, and then the molten glass is poured into a float bath 10. Then, as shown in FIG. 1, a strip-shaped glass ribbon G is formed on the molten metal M of the float bath 10, and the glass ribbon G is pulled out from the float bath 10 by a lift-out roll 4 provided in the dross box 30. , The glass ribbon G is slowly cooled in the slow cooling furnace 20.

The dross box 30 has a drape 6 on top of a plurality of lift-out rolls 4 that convey the glass ribbon G.

As shown in FIG. 2A, the drape 6 has a seat portion 62 and a frame portion 61 that sandwiches the upper portion of the seat portion 62. The drape 6 further includes a bolt 63 for fastening the seat portion 62 and the frame portion 61, and a nut 64 for fixing the bolt 63.

The material of the sheet portion 62 is a non-metallic material having a flexural modulus of 20 GPa or more at room temperature.

When the material of the sheet portion 62 is a non-metal material, unlike the conventional corrugated iron plate portion, the sheet portion 62 does not have a problem that the rigidity is lowered due to the corrosion of _{oxygen and SO 2.} Further, when the flexural modulus of the non-metal material is 20 GPa or more, the rigidity of the seat portion 62 can be increased.

Therefore, the seat portion 62 can prevent the seat portion 62 from being deformed even when it receives the atmospheric pressure from the float bath in the dross box in which _{oxygen and SO 2 are present.}

The non-metal material preferably has a flexural modulus of 100 GPa or less at room temperature. If the flexural modulus is 100 GPa or less, even if the seat portion 62 is deformed, the restoring force of the seat portion 62 can be suppressed, so that the deformation of the outer wall 31 (see FIG. 1) for suspending the drape 6 can be suppressed. ..

The manufactured float glass is used, for example, as a glass substrate for a display, a cover glass for a display, and a window glass.

The float glass produced is preferably non-alkali glass when used as a glass substrate for a display. Further, when used for construction and vehicles, soda lime glass is preferable. When used for cover glass, it is preferably chemically tempered glass.

For non-alkali glass, for example, in _{terms of mass% based on oxide, SiO 2} : 50% to 73%, Al ₂ O ₃ : 10.5% to 24%, B ₂ O ₃ : 0% to 12%, MgO : 0% to 10%, CaO: 0% to 14.5%, SrO: 0% to 24%, BaO: 0% to 13.5%, MgO + CaO + SrO + BaO: 8% to 29.5%, ZrO ₂ : 0% Contains ~ 5%.

In the case of achieving both high strain point and high solubility, the non-alkali glass is preferably expressed in mass% based on oxide, SiO ₂ : 58% to 66%, Al ₂ O ₃ : 15% to 22%, B ₂ O ₃ : 5% to 12%, MgO: 0% to 8%, CaO: 0% to 9%, SrO: 3% to 12.5%, BaO: 0% to 2%, MgO + CaO + SrO + BaO: 9% to Contains 18%.

When it is desired to obtain a particularly high strain point, the non-alkali glass is preferably expressed in terms of mass% based on oxide, SiO ₂ : 54% to 73%, Al ₂ O ₃ : 10.5% to 22.5%, B ₂ O ₃ : 0% to 5.5%, MgO: 0% to 10%, CaO: 0% to 9%, SrO: 0% to 16%, BaO: 0% to 2.5%, MgO + CaO + SrO + BaO: 8 Contains% to 26%.

Since the non-alkali glass having the above glass composition has a strain point 100 ° C. or higher higher than that of the soda lime glass used for the window glass, the atmospheric temperature in the dross box 30 is 650 ° C. or higher, depending on the glass composition. It can reach 700 ° C or higher. Therefore, in the case of the conventional corrugated iron plate portion, the problem of a decrease in rigidity due to corrosion of _{oxygen and SO 2 is likely to occur.} On the other hand, the above-mentioned float glass manufacturing method is suitable for manufacturing non-alkali glass because even if the ambient temperature in the dross box 30 is high, there is no problem of a decrease in rigidity due to corrosion of _{oxygen and SO 2.} be.

The thickness of the manufactured float glass is 0.1 mm to 2.0 mm for cover glass applications and 0.1 mm to 0.7 mm for display glass substrate applications.

The substrate size of the float glass to be manufactured is preferably 2100 mm or more on the short side and 2400 mm or more on the long side, more preferably 2800 mm or more on the short side and 3000 mm or more on the long side, and 2900 mm or more on the short side and 3200 mm on the long side for glass substrate applications for liquid crystal displays. The above is more preferable.

Next, the present invention will be described in detail with reference to FIGS. 1 and 2 with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples and Comparative Examples.

The drapes of Examples and Comparative Examples were placed in the dross box 30 of the float glass manufacturing apparatus 1 of FIG. 1 for 4 months, and the presence or absence of deformation, the amount of deformation, and the presence or absence of corrosion of the sheet portion were confirmed.

The presence or absence of deformation was confirmed by visually observing the drape in the dross box 30 from the window on the side wall of the dross box 30.

The amount of deformation refers to the maximum displacement of the lower end of the drape in the transport direction of the glass ribbon. The maximum displacement means the maximum value of the displacement when compared in the longitudinal direction of the drape. This amount of deformation was measured using a surveillance camera that photographs the drape and the glass ribbon in the dross box 30 from the window on the side wall of the dross box 30. Since the image taken by the surveillance camera is subjected to image processing, the displacement of the lower end of the drape in the transport direction of the glass ribbon can be measured.

The presence or absence of corrosion was confirmed by visually observing the drape extracted from the dross box 30.

The float glass produced was non-alkali glass (manufactured by AGC Inc., trade name: AN100), and its plate thickness was 0.5 mm. The atmospheric temperature inside the dross box 30 was about 700 ° C.

The frame materials 61A and 61B are made of stainless steel (SUS304 described in JIS G4304: 2012) and have a thickness of 3 mm.

(Examples 1 and 2)
The material of the sheet portion was a C / C composite material which is a carbon material. Example 1 is a trade name CX-741 manufactured by Toyo Tanso Co., Ltd. Example 2 is a trade name CX-761 manufactured by Toyo Tanso Co., Ltd. The flexural modulus of Examples 1 and 2 is 46 GPa and 55 GPa, respectively (see Table 1). The flexural modulus was measured at room temperature using a JIS K 7078 shear test (test piece: 60 mm × 10 mm × thickness 3 mm).

The sheet portion has a rectangular cross-sectional shape in a plan view. The thickness of the sheet portion was 2.5 mm.

(Comparative Example 1)
The material of the seat portion was stainless steel (SUS304 described in JIS G4304: 2012). The flexural modulus of Comparative Example 1 is 197 GPa (see Table 1). The flexural modulus was measured at room temperature using a three-point bending method. Specifically, it was measured using the static Young's modulus test method of JIS Z 2280.

In the sheet portion, the surfaces on the upstream side and the downstream side in the transport direction of the glass ribbon have a wavy shape in a plan view. The thickness of the sheet portion was 0.15 mm.

(summary)
The results of Examples and Comparative Examples are as shown in Table 1.

The method for measuring the bending strength is the same as the method for measuring the flexural modulus described above in Examples and Comparative Examples.

The tensile strength was measured in Examples 1 and 2 at room temperature using a monofilament test, and in Comparative Example 1 at room temperature using the tensile test method of JIS Z 2241.

The compressive strength was measured at room temperature using the in-plane compression test of JIS K 7076 in Examples 1 and 2 and the tensile test method of JIS Z 2241 in Comparative Example 1. The compressive strength of Comparative Example 1 refers to the yield stress of JIS Z 2241.

The bulk density was measured at room temperature using the Archimedes method.

表１に示すように、実施例１及び２は、シート部の材質として、非金属材料であるＣ／Ｃコンポジット材を選定したため、酸素及びＳＯ_２によるシート部の腐食が目視で確認されなかった。また、実施例１及び２のＣ／Ｃコンポジット材は、いずれも曲げ強度が２０ＧＰａ以上であることにより、シート部の変形が目視で確認されず、監視カメラで計測したシート部の変形量が０ｍｍであった。さらに、シート部は、平面視における断面形状が矩形状であることにより、シート部の局所変形も目視で確認されなかった。

As shown in Table 1, in Examples 1 and 2, since a C / C composite material which is a non-metallic material was selected as the material of the sheet portion, corrosion of the sheet portion due to _{oxygen and SO 2 was not visually confirmed.} .. Further, in the C / C composite materials of Examples 1 and 2, since the bending strength is 20 GPa or more, the deformation of the sheet portion is not visually confirmed, and the deformation amount of the sheet portion measured by the surveillance camera is 0 mm. Met. Further, since the cross-sectional shape of the sheet portion in a plan view is rectangular, no local deformation of the sheet portion was visually confirmed.

On the other hand, in Comparative Example 1, since stainless steel, which is a metal material, was selected as the material of the seat portion, corrosion of the seat portion due to _{oxygen and SO 2 was visually confirmed.} Further, in the stainless steel of Comparative Example 1, the deformation of the seat portion was visually confirmed, and the amount of deformation of the seat portion measured by the surveillance camera was 20 mm. Further, since the surfaces of the sheet portion on the upstream side and the downstream side in the transport direction of the glass ribbon have a wavy shape in a plan view, local deformation of the sheet portion is also visually confirmed.

As described above, as described in the embodiments and examples for carrying out the invention, the float glass manufacturing apparatus and the float glass manufacturing method of the present invention can prevent deformation of the sheet portion of the drape arranged in the dross box.

As a result, oxygen and SO ₂ gas in the slow cooling furnace can be suppressed from entering the dross box and the float bath, and thus the occurrence of dross defects and the corrosion of the shell of the dross box can be suppressed. Further, since the deformation of the drape is suppressed, the drape replacement work becomes unnecessary, and the production loss at the time of the replacement work can be prevented.

The present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the gist of the invention described in the claims.

Applications of the manufactured float glass include construction, vehicle, flat panel display, cover glass, and various other uses.

1 Float glass manufacturing equipment 10 Float bath 12 Bath surface 13 Outlet 18 Heater 20 Slow cooling furnace 21 Transport roll 23 Inlet 28 Heater 30 Dross box 31 Outer wall 32 Inner wall 33, 34 Insulation material 35-38 Space 39 Outlet 4 Lift out roll 5 Contact member 6 Drape 61 Frame part 61A, 61B Frame material 62 Seat part 63 Bolt 64 Nut 65 Through hole 67 Joint plate 68 Bolt 8 Heater G Glass ribbon M Float metal

Claims (18)

Float glass provided with a float bath for accommodating the molten metal, a slow cooling furnace in which a glass ribbon formed in a strip shape on the molten metal is carried in, and a dross box provided between the float bath and the slow cooling furnace. It ’s a manufacturing device,
The dross box has a drape on top of a plurality of lift-out rolls that carry the glass ribbon.
The drape has a seat portion and a frame portion that sandwiches the upper portion of the seat portion.
A float glass manufacturing apparatus, wherein the material of the sheet portion is a non-metallic material having a flexural modulus of 20 GPa or more at room temperature. The float glass manufacturing apparatus according to claim 1, wherein the non-metal material has a flexural modulus of 100 GPa or less at room temperature. The float glass manufacturing apparatus according to claim 1 or 2, wherein the non-metal material has a bending strength of 90 MPa or more at room temperature. The float glass manufacturing apparatus according to any one of claims 1 to 3, wherein the non-metal material has a tensile strength of 90 MPa or more at room temperature. The float glass manufacturing apparatus according to claim 4, wherein the non-metal material has a tensile strength of 300 MPa or less at room temperature. The float glass manufacturing apparatus according to any one of claims 1 to 5, wherein the non-metal material has a bulk density of 3 g / cm ^{3 or less at room temperature.} The float glass manufacturing apparatus according to any one of claims 1 to 6, wherein the non-metal material is ceramic. The float glass manufacturing apparatus according to claim 7, wherein the ceramic is silicon carbide or silicon nitride. The float glass manufacturing apparatus according to claim 7, wherein the ceramic is one or more selected from the group consisting of silica, alumina, magnesia, and calcia. The float glass manufacturing apparatus according to any one of claims 1 to 6, wherein the non-metal material is a carbon material. The float glass manufacturing apparatus according to claim 10, wherein the carbon material is a CIP material or a C / C composite. The carbon material has a coating on the outer surface.
The float glass manufacturing apparatus according to claim 10 or 11, wherein the component of the coating is silicon carbide or an oxide containing aluminum and phosphorus. The float glass manufacturing apparatus according to any one of claims 1 to 12, wherein the sheet portion has a thickness of 0.8 to 15 mm. The float glass manufacturing apparatus according to any one of claims 1 to 13, wherein the surface of the sheet portion on the upstream side in the transport direction of the glass ribbon is linear in a plan view. The float glass manufacturing apparatus according to any one of claims 14, wherein the surface of the sheet portion on the downstream side in the transport direction of the glass ribbon is linear in a plan view. The float glass manufacturing apparatus according to any one of claims 1 to 13, wherein the sheet portion has a rectangular cross-sectional shape in a plan view. A method for producing float glass in which a strip-shaped glass ribbon is formed on the molten metal of a float bath, the glass ribbon is pulled out from the float bath by a lift-out roll provided in a dross box, and the glass ribbon is slowly cooled in a slow cooling furnace. And
The dross box has a drape on top of a plurality of lift-out rolls that carry the glass ribbon.
The drape has a seat portion and a frame portion that sandwiches the upper portion of the seat portion.
A method for producing float glass, wherein the material of the sheet portion is a non-metallic material having a flexural modulus of 20 GPa or more at room temperature. The float glass manufacturing method according to claim 17, wherein the non-metal material has a flexural modulus of 100 GPa or less at room temperature.

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