JP2023001476A - Float glass production device, and float glass production method - Google Patents

Abstract

To provide a technique to improve the quality of glass ribbon.SOLUTION: A float glass production device has: a float bath for molding a glass ribbon on molten metal; a dross box having a plurality of lift-out rolls to pull up the glass ribbon; and a slow-cooling furnace having a plurality of layer rolls to convey the glass ribbon. The slow-cooling furnace has: a pair of side walls provided across the conveyance route of the glass ribbon; a ceiling that seals the top of the conveyance route; a gas discharge nozzle that discharges a sulfur oxide gas to the conveyance route from below it; and a gas suction nozzle that is inserted inward from the side wall and sucks a lower gas upwards, above the conveyance route, or sucks a lateral gas sideways. The gas suction nozzle is disposed at the same position as the gas discharge nozzle in the conveyance direction or disposed upstream from the gas discharge nozzle.SELECTED DRAWING: Figure 1

Description

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

A float glass manufacturing apparatus includes a float bath for forming a glass ribbon on a molten metal, a dross box having a plurality of lift-out rolls for pulling up the glass ribbon, and an annealing furnace having a plurality of layer rolls for transporting the glass ribbon. . A float glass is obtained by cutting the glass ribbon annealed in an annealing furnace into a desired size and shape.

The interior of the float bath is filled with a reducing gas to suppress oxidation of the molten metal. The reducing gas flows from the inside of the float bath into the inside of the dross box, and the inside of the dross box is also filled with the reducing gas. On the other hand, the interior of the slow cooling furnace is filled with air.

The dross box includes a carbon member that contacts the lift out roll. The carbon member removes dross adhering to the lift out roll. Dross is an oxide of molten metal brought into the dross box along with the glass ribbon.

If the air flows into the dross box from the slow cooling furnace, the oxygen gas in the air causes the carbon member to be oxidized and consumed, making it difficult to remove the dross. As a result, the lower surface of the glass ribbon is damaged.

Patent Literature 1 discloses a technique of using an atmosphere partition device to prevent air from flowing into the dross box from the slow cooling furnace. The atmosphere partitioning device separates the space below the transport path through which the glass ribbon is transported in the dross box from the space below the transport path in the annealing furnace.

JP 2016-050160 A

The slow cooling furnace has a gas discharge nozzle for discharging sulfur oxide gas from below the conveying path of the glass ribbon toward the conveying path. The sulfur oxide gas reacts with the lower surface of the glass ribbon to form a buffer film on the lower surface of the glass ribbon. The buffer film reduces collision between the glass ribbon and the layer roll. The buffer film contains sulfate crystals and the like. Sulfate crystals form in an oxidizing atmosphere.

If the gap between the upper surface of the glass ribbon and the drape is narrow inside the dross box, the reducing gas may flow into the slow cooling furnace from the inside of the dross box. The reducing gas that has flowed in wraps around the glass ribbon from above to below. As a result, there are problems such as the flow of sulfur oxide gas being disturbed, or the oxygen concentration around the gas discharge nozzle being lowered. Therefore, the formation of the buffer film was hindered, and the lower surface of the glass ribbon was easily damaged.

One aspect of the present disclosure provides a technique for improving the quality of the glass ribbon by suppressing the formation of the buffer film from being inhibited by the reducing gas flowing from the inside of the dross box into the inside of the annealing furnace.

A float glass manufacturing apparatus according to an aspect of the present disclosure includes a float bath for forming a glass ribbon on a molten metal, a dross box having a plurality of lift out rolls for pulling up the glass ribbon, and a plurality for conveying the glass ribbon. and a slow cooling furnace having a layer roll of The slow cooling furnace includes a pair of side wall portions sandwiching the conveying path of the glass ribbon, a ceiling portion blocking the upper part of the conveying path, and discharging sulfur oxide gas from below the conveying path toward the conveying path. It has a gas discharge nozzle, and a gas suction nozzle that is inserted inward from the side wall and sucks downward gas upward or sucks lateral gas laterally above the conveying path. The gas suction nozzle is arranged in the transport direction at the same position as the gas discharge nozzle, or arranged upstream of the gas discharge nozzle.

According to one aspect of the present disclosure, the gas suction nozzle can restrict the reducing gas that has flowed into the slow cooling furnace from the inside of the dross box from reaching the periphery of the gas discharge nozzle, thereby inhibiting the formation of the buffer film. can be suppressed, and the quality of the glass ribbon can be improved.

FIG. 1 is a side sectional view showing a float glass manufacturing apparatus according to one embodiment. FIG. 2 is a front cross-sectional view showing an example of a slow cooling furnace.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, in each drawing, the same reference numerals are given to the same or corresponding configurations, and explanations thereof may be omitted. In each drawing, the X-axis direction, Y-axis direction and Z-axis direction are perpendicular to each other, the X-axis direction and Y-axis direction are horizontal directions, and the Z-axis direction is vertical direction. The X-axis direction is the conveying direction of the glass ribbon G, and the Y-axis direction is the width direction of the glass ribbon G. In the specification, "-" indicating a numerical range means that the numerical values described before and after it are included as lower and upper limits.

A float glass manufacturing apparatus 1 according to one embodiment will be described with reference to FIG. A float glass manufacturing apparatus 1 includes a float bath 2 , a dross box 3 , and a slow cooling furnace 5 , arranged from the upstream side to the downstream side in the glass ribbon G conveying direction. A float glass manufacturing apparatus 1 forms a glass ribbon G on a molten metal M stored in a float bath 2, and lifts the formed glass ribbon G into a float bath 2 by a plurality of lift out rolls 31 provided inside a dross box 3. , and sent to the slow cooling furnace 5 . Moreover, the float glass manufacturing apparatus 1 anneals the glass ribbon G inside the annealing furnace 5, and then cuts it into desired dimensions and shapes. By cutting the glass ribbon G, float glass is obtained.

Float glass is, for example, alkali-free glass, aluminosilicate glass, borosilicate glass, soda lime glass, or the like. Alkali-free glass means glass that does not substantially contain alkali metal oxides such as Na ₂ O and K ₂ O. Here, "substantially free of alkali metal oxides" means that the total content of alkali metal oxides is 0.1% by mass or less.

The use of float glass is not particularly limited, but for example, it is cover glass for displays (for example, liquid crystal displays, organic EL displays, etc.). If the application of float glass is cover glass, the float glass is chemically strengthened glass. Unlike non-alkali glass, glass for chemical strengthening contains alkali metal oxides.

The glass for chemical strengthening is, for example, SiO ₂ : 62% to 68%, Al ₂ O ₃ : 6% to 12%, MgO: 7% to 13%, Na ₂ O: 9% in terms of mol% based on oxides. ~17%, K ₂ O: 0% to 7%, the difference obtained by subtracting the Al ₂ O ₃ content from the total content of Na ₂ O and K ₂ O is less than 10%, and ZrO ₂ When it is contained, its content is 0.8% or less.

Another glass for chemical strengthening is SiO ₂ : 65% to 85%, Al ₂ O ₃ : 3% to 15%, Na ₂ O: 5% to 15%, K ₂ O, in terms of mol% based on oxides. : 0% to less than 2%, MgO: 0% to 15%, ZrO ₂ : 0% to 1%, and the total SiO ₂ +Al ₂ O ₃ content of SiO ₂ and Al ₂ O ₃ is 88% or less is.

Another glass for chemical strengthening is 50% to 75% SiO ₂ , 9% to 20% Al ₂ O ₃ , 10% to 20% Na ₂ O, K ₂ O 0% to 6%, MgO 0% to 15%, total amount of CaO, SrO and BaO (CaO + SrO + BaO) 0% to 10%, total amount of ZrO ₂ and TiO ₂ (ZrO ₂ + TiO ₂ ) 0% ~5%, B ₂ O ₃ from 0% to 10%, and Li ₂ O from 0% to 20%.

Float glass may be used as a glass substrate to form thin film transistors, color filters, etc. in displays. If the application of the float glass is as a glass substrate, the float glass is alkali-free glass. Alkali-free glass does not substantially contain alkali metal oxides, unlike glass for chemical strengthening.

Alkali-free glass is, for example, 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%.

When the alkali-free glass has both a high strain point and a high solubility, it preferably contains SiO ₂ : 58% to 66%, Al ₂ O ₃ : 15% to 22%, in terms of % by mass based on oxides. 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% ~ Contains 18%.

When it is desired to obtain a particularly high strain point, alkali-free glass preferably contains SiO ₂ : 54% to 73%, Al ₂ O ₃ : 10.5% to 22.5%, in terms of % by mass based on oxides. 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 % to 26%.

The thickness of the float glass is selected according to the use of the float glass. If the application of the float glass is as cover glass for displays, the thickness of the float glass is, for example, 0.1 mm to 2.0 mm. On the other hand, when the float glass is used as a glass substrate for displays, the thickness of the float glass is, for example, 0.1 mm to 0.7 mm.

Next, referring to FIG. 1 again, the float bus 2 and the like according to one embodiment will be described. The float bath 2 has a bathtub 21 . The bath 21 contains the molten metal M. As the molten metal M, for example, molten tin is used. In addition to molten tin, molten tin alloys and the like can also be used, and the molten metal M should have a density higher than that of molten glass. Molten glass is continuously supplied onto the molten metal M, and formed into a strip-shaped glass ribbon G using the smooth liquid surface of the molten metal M.

The float bath 2 has a ceiling 22 forming a space above the bathtub 21. - 特許庁The inside of the float bath 2 is filled with a reducing gas to prevent oxidation of the molten metal M, and is maintained at a pressure higher than the atmospheric pressure. The reducing gas is, for example, a mixed gas of nitrogen gas and hydrogen gas, containing 85% to 98.5% by volume of nitrogen gas and 1.5% to 15% by volume of hydrogen gas. The reducing gas is supplied from the joints between the bricks of the ceiling 22 and the holes of the ceiling 22 .

The float bath 2 includes a heater 23 that heats the glass ribbon G. As shown in FIG. The heater 23 is suspended from the ceiling 22, for example, and heats the glass ribbon G passing below. The heater 23 is, for example, an electric heater, and is electrically heated. A plurality of heaters 23 are arranged in a matrix in the conveying direction and the width direction of the glass ribbon G. As shown in FIG. By controlling the outputs of the plurality of heaters 23, the temperature distribution of the glass ribbon G can be controlled, and the plate thickness distribution of the glass ribbon G can be controlled.

The dross box 3 includes a lift out roll 31 for pulling up the glass ribbon G. The lift out roll 31 is rotationally driven by a driving device (not shown) such as a motor, and conveys the glass ribbon G obliquely upward by the driving force thereof. The driving device is provided outside the dross box 3 . Therefore, the outer wall of the dross box 3 is formed with a hole through which the lift out roll 31 is inserted.

A plurality of lift out rolls 31 are arranged inside the dross box 3 at intervals in the conveying direction (X-axis direction) of the glass ribbon G. Although the number of lift out rolls 31 is three in FIG. 1, the number may be two, or may be four or more. The axial direction of the lift out roll 31 is the same as the width direction of the glass ribbon G (Y-axis direction).

The dross box 3 includes a carbon member 32 that contacts the lift out roll 31 . The carbon member 32 is arranged in the lower space of the dross box 3 . The lower space of the dross box 3 is a space below the glass ribbon G. The carbon member 32 abuts on the outer peripheral surface of the lift out roll 31 and removes foreign matter adhering to the outer peripheral surface of the lift out roll 31 . The foreign matter includes so-called dross, which is oxide of the molten metal M brought into the dross box 3 together with the glass ribbon G, for example.

The carbon member 32 is, for example, a rectangular parallelepiped. The carbon member 32 may be a trapezoidal or inverted trapezoidal quadrangular prism as viewed in the X-axis direction. A plurality of carbon members 32 may be provided in the axial direction of the lift out roll 31 . The number of carbon members 32 arranged along each lift out roll 31 is determined according to the width of the glass ribbon G (Y-axis direction dimension) or the axial length (Y-axis direction dimension) of the lift out roll 31. be.

The Y-axis dimension of the carbon member 32 is, for example, 300 mm to 1000 mm, preferably 400 mm to 800 mm. The Z-axis direction dimension of the carbon member 32 is, for example, 50 mm to 200 mm, preferably 70 mm to 150 mm. The dimension of the carbon member 32 in the X-axis direction is, for example, 20 mm to 100 mm, preferably 30 mm to 80 mm.

The carbon member 32 may contain graphite powder. The maximum particle size of graphite powder is, for example, 0.1 mm to 3 mm, preferably 0.5 mm to 2.5 mm. When the maximum particle size of the graphite powder is 0.1 mm to 3 mm, the strength of the carbon member 32, which is a molded body of graphite powder, can be ensured.

The Shore hardness of the carbon member 32 is, for example, 20HS to 90HS, preferably 30HS to 80HS. When the Shore hardness of the carbon member 32 is 20HS to 90HS, the abrasion resistance of the carbon member 32 against the lift out rolls 31 can be ensured.

The dross box 3 may include a biasing member 33 that presses the carbon member 32 against the lift out roll 31 . The biasing member 33 includes, for example, a metal spring. The spring is a leaf spring. The biasing member 33 may include a coil spring, a compression coil spring, a disk spring, a bamboo spring, a ring spring, etc. instead of the leaf spring. Note that the biasing member 33 may include a fluid pressure cylinder such as a pneumatic cylinder.

The dross box 3 may include a support member 34 that supports the carbon member 32 so that it can move up and down. A support member 34 is arranged on the bottom wall 35 of the dross box 3 . The support member 34 has a U-shaped cross section perpendicular to the Y-axis direction, and the carbon member 32 and the biasing member 33 are arranged inside the support member 34 . The support member 34 prevents the carbon member 32 and the biasing member 33 from shifting in the X-axis direction.

The dross box 3 may have a heater 37 on the ceiling 36 to adjust the temperature of the glass ribbon G. The heater 37 may be provided not only above the glass ribbon G but also below it. In the dross box 3, the temperature of the glass ribbon G is preferably (Tg−50° C.) to (Tg+30° C.) with reference to the glass transition point Tg of the float glass.

The dross box 3 is suspended above the glass ribbon G from the lower surface of the hood 38 through a hood 38, a heat insulating material 39 placed on the hood 38, a part of the heat insulating material 39 and the hood 38. a lowered drape 40; The drape 40 is a plate-like member made of a refractory material such as steel or glass.

The drape 40 partitions the upper space of the dross box 3 into a plurality of spaces in the conveying direction of the glass ribbon G (X-axis direction). The upper space of the dross box 3 is a space above the glass ribbon G. The drape 40 is positioned, for example, directly above the centerline of rotation of each lift outroll 31 . The drape 40 extends in the axial direction (Y-axis direction) of each lift out roll 31 .

The annealing furnace 5 slowly cools the glass ribbon G to a temperature below the strain point of the glass while conveying the glass ribbon G by the layer rolls 51 . The slow cooling furnace 5 is provided with heaters (not shown) on the ceiling and bottom walls in order to adjust the temperature of the glass ribbon G. The layer roll 51 is rotationally driven by a driving device (not shown) such as a motor, and conveys the glass ribbon G in the horizontal direction by its driving force. The slow cooling furnace 5 is open to the outside at the outlet on the downstream side. Therefore, air flows into the slow cooling furnace 5 .

Next, an example of the slow cooling furnace 5 will be described with reference to FIGS. 1 and 2. FIG. As shown in FIG. 1, the slow cooling furnace 5 has, for example, a furnace body 52, a first gas discharge nozzle 53, a second gas discharge nozzle 54, a gas concentration meter 55, and a gas suction nozzle 56. Further, as shown in FIG. 2 , the slow cooling furnace 5 may have an ejector 57 and a vertical pipe 58 .

The furnace body 52 has, for example, a rectangular shape when viewed in the X-axis direction, as shown in FIG. The furnace body 52 includes a pair of side walls 521 and 522 , a ceiling 523 and a bottom wall 524 . A pair of side wall portions 521 and 522 are provided so as to sandwich the conveying path of the glass ribbon G in the Y-axis direction. The ceiling part 523 closes the upper part of the conveying path of the glass ribbon G. As shown in FIG. The bottom wall portion 524 closes the lower part of the glass ribbon G conveying path. A pair of side wall portions 521 and 522 are provided vertically so as to be orthogonal to the Y-axis direction, and a ceiling portion 523 and a bottom wall portion 524 are provided horizontally.

As shown in FIG. 1, the first gas discharge nozzle 53 discharges sulfur oxide gas from below the conveying path of the glass ribbon G toward the conveying path. The first gas ejection nozzle 53 extends, for example, in the Y-axis direction and has a plurality of gas ejection openings spaced apart in the Y-axis direction. Each gas discharge port discharges sulfur oxide gas upward.

The sulfur oxide gas reacts with the lower surface of the glass ribbon G to form a buffer film on the lower surface of the glass ribbon G. The buffer film reduces the collision between the glass ribbon G and the layer roll 51 and suppresses the lower surface of the glass ribbon G from being damaged. The buffer film contains sulfate crystals and the like. Sulfate crystals form in an oxidizing atmosphere.

The first gas discharge nozzle 53 discharges, for example, SO ₂ gas as the sulfur oxide gas to generate sulfate crystals.

The 1st gas discharge nozzle 53 is arrange|positioned between the 1st and 2nd layer rolls 51 and 51 toward the downstream from the upstream of the conveyance direction of the glass ribbon G, for example. The first (most upstream) layer roll 51 can block the flow of the reducing gas that has flowed into the slow cooling furnace 5 from the inside of the dross box 3 toward the outlet of the sulfur oxide gas. Therefore, it is possible to suppress the disturbance of the flow of sulfur oxide gas. Moreover, the buffer film can be formed relatively upstream of the slow cooling furnace 5, and the occurrence of scratches on the lower surface of the glass ribbon G can be suppressed.

The first gas discharge nozzle 53 may be arranged upstream of the first (most upstream) layer roll 51, although not shown. Also, although not shown, the first gas discharge nozzle 53 may be arranged downstream of the second layer roll 51 in the transport direction.

The second gas discharge nozzle 54 discharges an oxygen-containing gas from below the conveying path of the glass ribbon G toward the conveying path. The second gas ejection nozzle 54 extends, for example, in the Y-axis direction and has a plurality of gas ejection openings spaced apart in the Y-axis direction. Each gas ejection port ejects an oxygen-containing gas upward.

The oxygen-containing gas may be any gas containing oxygen gas, and may be pure oxygen gas or air. It is possible to increase the oxygen gas concentration around the first gas discharge nozzle 53 and promote the generation of sulfate.

The second gas discharge nozzle 54 is preferably arranged next to the first gas discharge nozzle 53. For example, the first and second layer rolls 51, 51 are arranged from the upstream side to the downstream side in the conveying direction of the glass ribbon G. may be placed between The oxygen gas concentration around the first gas discharge nozzle 53 can be efficiently increased.

The second gas discharge nozzle 54 may be provided next to the first gas discharge nozzle 53, and is arranged upstream of the first (most upstream) layer roll 51 in the same manner as the first gas discharge nozzle 53. Alternatively, it may be arranged downstream of the second layer roll 51 in the conveying direction.

The gas concentration meter 55 measures O ₂ gas concentration, SO ₂ gas concentration, H ₂ O gas concentration, or the like. The gas concentration meter 55 is provided next to the first gas ejection nozzle 53 , for example, below the first gas ejection nozzle 53 . A desired gas concentration can be detected around the first gas discharge nozzle 53 by the gas concentration meter 55, and the gas flow rate can be adjusted so that the gas concentration falls within the allowable range. Although not shown, a pressure gauge may be provided next to the gas concentration gauge 55 . A pressure gauge measures the pressure around the first gas discharge nozzle 53 .

By the way, if the gap between the upper surface of the glass ribbon G and the drape 40 is narrow inside the dross box 3 , the reducing gas may flow into the slow cooling furnace 4 from the inside of the dross box 3 . The reducing gas flows along the upper surface of the glass ribbon G.

Conventionally, the inflowing reducing gas wraps around the glass ribbon G from above to below and reaches the periphery of the first gas discharge nozzle 53 . As a result, there are problems such as turbulence in the flow of sulfur oxide gas and a decrease in oxygen concentration around the gas discharge nozzle. Therefore, the formation of the buffer film was hindered, and the lower surface of the glass ribbon was easily damaged.

The gas suction nozzle 56 is inserted inside from the side wall portions 521 and 522 and sucks gas above the conveying path of the glass ribbon G. As shown in FIG. The gas suction nozzle 56 sucks downward gas upward in this embodiment, but it may also suck lateral gas sideways. Note that the gas suction nozzle 56 may be provided on only one of the pair of side wall portions 521 and 522 .

The gas suction nozzle 56 is arranged upstream of the first gas discharge nozzle 53 in the transport direction of the glass ribbon G. As shown in FIG. The gas suction nozzle 56 may be arranged at the same position as the first gas discharge nozzle 53 in the glass ribbon G transport direction.

According to this embodiment, the gas suction nozzle 56 is arranged upstream of the first gas discharge nozzle 53 in the conveying direction of the glass ribbon G, or arranged at the same position as the first gas discharge nozzle 53, The reducing gas flowing along the upper surface of the glass ribbon G is sucked upward. Therefore, it is possible to restrict the reducing gas from reaching the periphery of the first gas discharge nozzle 53, suppress the inhibition of the formation of the buffer film, and improve the quality of the glass ribbon.

As a technique different from the technique of the present disclosure, it is conceivable to provide an opening in the ceiling portion 523 of the furnace body 52 and discharge the reducing gas to the outside of the furnace body 52 from the opening. However, if the opening is provided in the ceiling portion 523, the heat insulating property of the ceiling portion 523 is deteriorated. As a result, the glass ribbon G is rapidly cooled under the opening, and large residual stress is generated in the glass ribbon G.

According to this embodiment, the gas suction nozzle 56 is inserted through the small openings of the side wall portions 521 and 522 without providing an opening portion in the ceiling portion 523 . Therefore, deterioration of the heat insulating property of the furnace body 52 can be suppressed, a rapid temperature drop of the glass ribbon G can be suppressed, and residual stress generated in the glass ribbon G can be reduced.

The gas suction nozzle 56 may be arranged directly above the region where the temperature of the glass ribbon G is equal to or higher than the strain point. The reducing gas flowing from the dross box 3 can be sucked by the gas suction nozzle 56 on the relatively upstream side of the slow cooling furnace 5 . Therefore, the reducing gas can be discharged to the outside of the furnace body 52 before the reducing gas diffuses.

The gas suction nozzle 56 is arranged, for example, upstream of the first layer roll 51 from the upstream side to the downstream side in the glass ribbon G conveying direction. The reducing gas flowing from the dross box 3 can be sucked by the gas suction nozzle 56 at the uppermost upstream of the slow cooling furnace 5 . Therefore, the reducing gas can be discharged to the outside of the furnace body 52 before the reducing gas diffuses.

The gas suction nozzle 56 extends in the Y-axis direction from each of the pair of side wall portions 521 and 522 to above the conveying path of the glass ribbon G, and sucks the gas below upward. The gas suction nozzle 56 sucks the gas below vertically or obliquely upward. The gas suction nozzle 56 includes a suction port 56a for sucking gas.

For example, when viewed from above, the suction port 56a of one gas suction nozzle 56 overlaps at least one widthwise end Ga of the glass ribbon G and extends outward in the widthwise direction from the one widthwise end Ga of the glass ribbon G. good. Further, when viewed from above, the suction port 56a of the other gas suction nozzle 56 overlaps at least the other widthwise end Gb of the glass ribbon G, and extends outward in the widthwise direction from the other widthwise end Gb of the glass ribbon G. may

The reducing gas inside the dross box 3 flows into the slow cooling furnace 5 through the gap between the lift out roll 31 and the drape 40 . At this time, since the glass ribbon G does not exist on the outer side in the width direction of the glass ribbon G, the size of the gap is large and the reducing gas flow is likely to be formed.

If the suction port 56a of one gas suction nozzle 56 extends widthwise outward from one widthwise end Ga of the glass ribbon G when viewed from above, the reducing gas flowing on the widthwise outer side of the glass ribbon G can be efficiently sucked. can be absorbed. Similarly, if the suction port 56a of the other gas suction nozzle 56 extends widthwise outward from the other widthwise end Gb of the glass ribbon G when viewed from above, the reduction gas flowing outside the glass ribbon G in the widthwise direction is reduced. Efficient absorption of gas.

When viewed from above, the suction port 56a of one gas suction nozzle 56 extends from one end in the width direction of the glass ribbon G to the center in the width direction of the glass ribbon G, and the suction port 56a of another gas suction nozzle 56 extends to the glass ribbon G. may extend from the other end in the width direction to the center in the width direction. The reducing gas can be absorbed over the entire width direction of the glass ribbon G.

The gas suction nozzle 56 sucks downward gas upward in this embodiment, but it may also suck lateral gas sideways. In this case, for example, when viewed from above, the suction port 56a of one gas suction nozzle 56 is arranged facing one end in the width direction of the glass ribbon G, and the reducing gas flowing outside in the width direction of the glass ribbon G is You can suck it up. Both gas suction nozzles 56 for sucking downward gas upward and gas suction nozzles 56 for laterally sucking side gas may be used.

The ejector 57 adjusts the suction amount of the gas suction nozzle 56 . By adjusting the suction amount of the gas suction nozzle 56, the concentrations of various gases around the first gas discharge nozzle 53 can be kept within the allowable range. The suction amount of the gas suction nozzle 56 may be controlled based on the measurement result of the gas concentration meter 55 .

The vertical pipe 58 extends upward from one end of the gas suction nozzle 56 outside the pair of side wall portions 521 and 522 . The gas sucked by the gas suction nozzle 56 is cooled while ascending the vertical pipe 58 . The temperature of the gas decreases from the bottom to the top of the vertical pipe 58 . Due to the temperature difference of the gas, an ascending air current can be formed inside the vertical pipe 58 and the gas can be efficiently drawn into the gas suction nozzle 56 . In addition, compared to the case where the vertical pipe 58 extends from one end of the gas suction nozzle 56 in the X-axis direction, it is easier to secure a space for workers to work on the side of the furnace body 52 .

The ejector 57 is provided at the lower end of the vertical pipe 58 and includes an ejector nozzle 57a that ejects gas such as compressed air upward. The gas ejected from the ejector nozzle 57a can increase the rising speed of the ascending air current formed inside the vertical pipe 58, and the gas can be drawn into the gas suction nozzle 56 more efficiently.

Experimental data will be described below. Example 1 below is a comparative example, and Examples 2 to 4 are examples. In Examples 1 to 4, float glass was produced under the conditions shown in Table 1 using the float glass production apparatus 1 shown in FIGS. In Examples 1 to 4, float glasses were produced under the same conditions except for the amount of gas suctioned by the gas suction nozzle 56 (unit: Nm ³ /h). For example, the discharge rate (unit: NL/min) of the first gas discharge nozzle 53 and the discharge rate (unit: NL/min) of the second gas discharge nozzle 54 were set to be the same in Examples 1-4.

表１において、ガス吸引ノズル５６の吸引量、Ｏ_２ガス濃度、ＳＯ_２ガス濃度、Ｈ_２Ｏガス濃度、及び圧力を、相対値で示す。なお、Ｏ_２ガス濃度（単位：体積％）、ＳＯ_２ガス濃度（単位：体積ｐｐｍ）、Ｈ_２Ｏガス濃度（単位：ｇ／ｃｍ^３）は、ガス濃度計５５により測定した。また、圧力（単位：Ｐａ）は、大気圧との差圧であって、ガス濃度計５５の隣の圧力計により測定した。

In Table 1, the suction amount of the gas suction nozzle 56, O ₂ gas concentration, SO ₂ gas concentration, H ₂ O gas concentration, and pressure are shown as relative values. The O ₂ gas concentration (unit: volume %), SO ₂ gas concentration (unit: volume ppm), and H ₂ O gas concentration (unit: g/cm ³ ) were measured by the gas concentration meter 55 . The pressure (unit: Pa) is a differential pressure from the atmospheric pressure and was measured by a pressure gauge next to the gas concentration gauge 55 .

As shown in Table 1, in Example 1, no gas was sucked by the gas suction nozzle 56, whereas in Examples 2 to 4, gas was sucked by the gas suction nozzle 56. As a result, in Examples 2 to 4, compared to Example 1, the O ₂ gas concentration and the SO ₂ gas concentration were higher and the H ₂ O gas concentration was lower around the first gas discharge nozzle 53 .

When the reducing gas flows into the slow cooling furnace 5 from the inside of the dross box 3 and the H ₂ gas contained in the reducing gas reaches the vicinity of the first gas discharge nozzle 53, the H ₂ gas and the O ₂ gas react, _H2O gas is produced. As a result, the H ₂ O gas concentration increases and the O ₂ gas concentration decreases around the first gas ejection nozzle 53 .

From the results in Table 1, it can be seen that if the gas is sucked by the gas suction nozzle 56, the reducing gas that has flowed into the slow cooling furnace 5 from the inside of the dross box 3 can be restricted from reaching the vicinity of the first gas discharge nozzle 53. I understand.

Further, from the results in Table 1, it can be seen that the greater the suction amount of the gas suction nozzle 56, the higher the O ₂ gas concentration and the SO ₂ gas concentration, and the lower the H ₂ O gas concentration. In addition, in Example 4, the reason why the pressure is low is that the amount of suction by the gas suction nozzle 56 was large.

Although the float glass manufacturing apparatus and the float glass manufacturing method according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments and the like. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally belong to the technical scope of the present disclosure.

1 float glass manufacturing apparatus 2 float bath 3 dross box 5 slow cooling furnace 51 layer rolls 521, 522 side wall portion 523 ceiling portion 53 first gas discharge nozzle (gas discharge nozzle)
56 Gas suction nozzle M Molten metal G Glass ribbon

Claims (9)

A float glass manufacturing comprising a float bath for forming a glass ribbon on a molten metal, a dross box having a plurality of lift-out rolls for lifting the glass ribbon, and a annealing furnace having a plurality of layer rolls for conveying the glass ribbon. a device,
The slow cooling furnace includes a pair of side wall portions sandwiching the conveying path of the glass ribbon, a ceiling portion blocking the upper part of the conveying path, and discharging sulfur oxide gas from below the conveying path toward the conveying path. a gas discharge nozzle, and a gas suction nozzle that is inserted inward from the side wall and sucks downward gas upward or sucks lateral gas laterally above the conveying path. ,
The float glass manufacturing apparatus, wherein the gas suction nozzle is arranged at the same position as the gas discharge nozzle, or arranged upstream of the gas discharge nozzle in the conveying direction of the glass ribbon. The float glass manufacturing apparatus according to claim 1, wherein the gas suction nozzle is arranged directly above a region where the temperature of the glass ribbon is equal to or higher than the strain point. The float glass manufacturing apparatus according to claim 1 or 2, wherein the slow cooling furnace has an ejector that adjusts the suction amount of the gas suction nozzle. The float glass manufacturing apparatus according to any one of claims 1 to 3, wherein the slow cooling furnace has a vertical tube extending upward from one end of the gas suction nozzle outside the pair of side walls. The slow cooling furnace has a vertical pipe extending upward from one end of the gas suction nozzle outside the pair of side wall portions, and an ejector for adjusting the suction amount of the gas suction nozzle,
The float glass manufacturing apparatus according to claim 1 or 2, wherein the ejector includes an ejector nozzle provided at the lower end of the vertical pipe and ejecting gas upward. The float glass manufacturing apparatus according to any one of claims 1 to 5, wherein the gas discharge nozzle is arranged between the first and second layer rolls from the upstream side to the downstream side in the conveying direction. . The float glass manufacturing apparatus according to any one of claims 1 to 6, wherein the gas suction nozzle is arranged upstream of the first layer roll from the upstream side to the downstream side in the conveying direction. The gas suction nozzle includes a suction port for sucking gas,
When viewed from above, the suction port of the gas suction nozzle overlaps one widthwise end of the glass ribbon and extends outward in the widthwise direction from the one widthwise end of the glass ribbon. The float glass manufacturing apparatus according to any one of claims 1 to 3. A float glass manufacturing method for manufacturing float glass using the float glass manufacturing apparatus according to any one of claims 1 to 8.

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