WO2015025568A1

WO2015025568A1 - Float glass production device and float glass production method using same

Info

Publication number: WO2015025568A1
Application number: PCT/JP2014/063379
Authority: WO
Inventors: 哲史瀧口; 督博鏡味; 和明隅田; 正信白井
Original assignee: 旭硝子株式会社
Priority date: 2013-08-22
Filing date: 2014-05-20
Publication date: 2015-02-26
Also published as: CN105377777B; KR20160045040A; TW201507982A; CN105377777A; JP2016183054A; KR102153289B1

Abstract

A float glass production device provided with: a bath containing a molten metal; a ceiling situated above the bath and extending from an entrance wall to an exit wall; a plurality of top rolls provided so as to be spaced along the flow direction of a glass ribbon flowing above the liquid level of the molten metal, rotating by themselves and pressing the widthwise extremities of the glass ribbon having traversed the space between the liquid level and the entrance wall; a dividing wall whereby a forming space enclosed by the ceiling, the bath, the entrance wall, and the exit wall is divided into a high-temperature space on the upstream side and a low-temperature space on the downstream side; and an exhaust path wherefrom a gas in the high-temperature space is exhausted to the exterior of the forming space. The dividing wall is arranged more to the downstream side than the entrance wall and upstream from the top roll on the most upstream-side among the plurality of top rolls.

Description

Float glass manufacturing apparatus and float glass manufacturing method using the same

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

The float glass manufacturing method includes a forming step of flowing a glass ribbon on a liquid surface of a molten metal (for example, molten tin) in a bathtub to form a plate (for example, refer to Patent Document 1). The molding space between the bathtub and the ceiling is filled with a reducing gas in order to suppress the oxidation of the molten metal. The forming space contains a small amount of gas evaporated from the molten metal. This gas contains the metal element evaporated from the molten metal in the form of a simple substance or a compound. Examples of the compound include metal oxides and metal sulfides.

Japanese Unexamined Patent Publication No. 50-3414

Conventionally, the gas evaporated from the molten metal is cooled to form foreign matters such as droplets and particles, and the foreign matters fall on the upper surface of the glass ribbon, resulting in many defects.

The present invention has been made in view of the above problems, and has as its main object to provide a float glass manufacturing apparatus with a reduced number of defects.

In order to solve the above problems, according to one aspect of the present invention,
A bathtub containing molten metal;
An entrance wall located above the upstream portion of the bathtub;
An outlet wall located above the downstream part of the bathtub;
A ceiling disposed above the bathtub and extending from the entrance wall to the exit wall;
Provided at intervals along the flow direction of the glass ribbon flowing over the liquid surface of the molten metal, pressing the width direction end of the glass ribbon that has passed between the liquid surface and the inlet wall, And a plurality of top rolls rotating by itself,
A partition wall that partitions the molding space surrounded by the ceiling, the bathtub, the entrance wall and the exit wall into a high temperature space on the upstream side and a low temperature space on the downstream side;
An exhaust passage for discharging the gas in the high temperature space to the outside of the molding space,
The float glass manufacturing apparatus is provided in which the partition wall is disposed on the downstream side of the inlet wall, and is disposed on the upstream side of the most upstream top roll among the plurality of top rolls.

According to one aspect of the present invention, there is provided a float glass manufacturing method with a reduced number of defects.

It is sectional drawing which shows the shaping | molding apparatus of the float glass manufacturing apparatus by one Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted. In this specification, the “width direction” means a direction orthogonal to the flow direction of the glass ribbon in the forming step.

FIG. 1 is a sectional view showing a forming apparatus of a float glass manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. In FIG. 2, the heater and the upper side wall are not shown in order to make the drawing easy to see. FIG. 3 is a sectional view taken along line III-III in FIG.

The float glass manufacturing apparatus has a forming apparatus 10. The forming apparatus 10 causes the glass ribbon 14 to flow on the liquid surface of the molten metal 11 in the bathtub 20 to form a plate shape. The glass ribbon 14 is pulled up from the molten metal 11 in the downstream area of the bathtub 20, and is sent from the outlet formed between the bathtub 20 and the outlet wall 28 to the slow cooling furnace. A plate-like float glass is obtained by cutting the glass ribbon 14 that has been gradually cooled in the slow cooling furnace.

As shown in FIGS. 1 to 3, for example, the molding apparatus 10 includes a bathtub 20, a spout trip 22, a twill 23,

restrictor tiles

24 and 25, an inlet wall 26, an outlet wall 28, a ceiling 30, upper side walls 32 and 33, An air passage 34, a heater 36, a top roll 40, a partition wall 42, an exhaust passage 44, and the like are included.

The bathtub 20 accommodates the molten metal 11 as shown in FIGS. As the molten metal 11, for example, molten tin or a molten tin alloy can be used as long as it can float the glass ribbon 14.

As shown in FIG. 1, the spout trip 22 continuously supplies the molten glass 12 on the liquid surface of the molten metal 11. The molten glass 12 passes between the spout trip 22 and the twill 23, is supplied onto the liquid surface of the molten metal 11, and becomes a glass ribbon 14.

The twill 23 is movable up and down with respect to the spout trip 22 in order to make the flow rate of the molten glass 12 variable. The larger the distance between the spout trip 22 and the twill 23, the greater the flow rate of the molten glass 12.

The

restrictor tiles

24 and 25 are in contact with the glass ribbon 14 as shown in FIG. 2 and regulate the width of the glass ribbon 14. The restrictor tiles 24 and 25 expand toward the downstream side. Therefore, between the

restrictor tiles

24 and 25, the glass ribbon 14 is widened while flowing toward the downstream. On the downstream side of the

restrictor tiles

24 and 25, the glass ribbon 14 flows at a distance from the side wall of the bathtub 20, and the width can be freely changed between the side walls of the bathtub 20.

The entrance wall 26 is located above the upstream part of the bathtub 20 as shown in FIG. For example, the inlet wall 26 is disposed on the downstream side of the spout trip 22 and is disposed above the

restrictor tiles

24 and 25. As shown in FIG. 2, the entire liquid surface of the molten metal 11 is covered with the glass ribbon 14 on the upstream side of the inlet wall 26. On the other hand, most of the liquid level of the molten metal 11 is covered with the glass ribbon 14 on the downstream side of the inlet wall 26, but a part of the liquid level of the molten metal 11 is not covered with the glass ribbon 14.

The exit wall 28 is located above the downstream part of the bathtub 20 as shown in FIG.

The ceiling 30 is provided above the bathtub 20 as shown in FIG. 1 and extends from the entrance wall 26 to the exit wall 28. The forming space 50 surrounded by the bathtub 20, the ceiling 30, the inlet wall 26 and the outlet wall 28 is filled with a reducing gas in order to suppress oxidation of the exposed portion of the liquid surface of the molten metal 11 that is not covered by the glass ribbon 14. May be. In order to reduce the mixing of outside air, the pressure in the molding space 50 may be higher than the atmospheric pressure.

The upper side walls 32 and 33 block the gap between the side wall of the bathtub 20 and the ceiling 30 as shown in FIG. The upper side walls 32, 33 extend from the inlet wall 26 to the outlet wall 28. In the upper side walls 32 and 33, a through hole through which the rotation shaft of the top roll 40 is inserted, an end portion of the exhaust passage 44, and the like are formed.

As shown in FIG. 1, the heater 36 is inserted into the air supply path 34 of the ceiling 30, and the heat generating portion of the heater 36 is disposed in the molding space 50. The heater 36 heats the molten metal 11 and the glass ribbon 14 from above. A plurality of heaters 36 are provided at intervals in the flow direction (X direction) and the width direction (Y direction) of the glass ribbon 14. The output of the heater 36 is controlled so that the temperature of the glass ribbon 14 becomes lower toward the downstream side.

As shown in FIG. 2, the top rolls 40 are used in pairs, pressing the end of the glass ribbon 14 in the width direction, and applying tension to the glass ribbon 14 in the width direction. A plurality of pairs of top rolls 40 are disposed at intervals along the flow direction of the glass ribbon 14.

The top roll 40 has a rotating member in contact with the glass ribbon 14 at the tip. While the rotating member rotates and the plurality of pairs of top rolls 40 apply tension to the glass ribbon 14, the glass ribbon 14 gradually cools and becomes hard while flowing in the downstream direction.

The top roll 40 may have a refrigerant flow path inside to suppress deterioration due to heat. A coolant such as water flowing through the coolant channel absorbs the heat of the top roll 40 and transports it to the outside, thereby cooling the top roll 40.

As shown in FIG. 1, the partition wall 42 partitions the molding space 50 into an upstream high temperature space 51 and a downstream low temperature space 52, and restricts the outflow of gas from the high temperature space 51 to the low temperature space 52. As shown in FIG. 3, the partition wall 42 may extend from one upper side wall 32 to the other upper side wall 33, and may cross the molding space 50.

Since the high temperature space 51 is hotter than the low temperature space 52, it contains a large amount of gas evaporated from the molten metal 11 in the bathtub 20. This gas contains the metal element evaporated from the molten metal 11 in the form of at least one of a simple substance and a compound. Examples of the compound include metal oxides and metal sulfides. Hereinafter, this gas is referred to as a metal-containing gas.

The partition wall 42 restricts the outflow of the metal-containing gas from the high temperature space 51 to the low temperature space 52. The number of foreign matters such as droplets and particles that can be formed by cooling the metal-containing gas in the low temperature space 52 can be reduced. As a result, it is possible to reduce the number of defects caused by the foreign matter falling on the surface of the glass ribbon 14.

Gas is supplied to the high temperature space 51 and the low temperature space 52 from the outside of the molding apparatus 10 via the air supply passages 34 formed on the respective ceilings. This gas may be a reducing gas in order to limit oxidation of the exposed portion of the liquid surface of the molten metal 11. The reducing gas includes, for example, 1 to 15% by volume of hydrogen gas and 85 to 99% by volume of nitrogen gas. The reducing gas may be supplied to the high temperature space 51 and the low temperature space 52 through the air supply path 34 after being preheated in the preheating space 53 surrounded by the roof casing 31 and the ceiling 30. The gas in the preheating space 53 flows into the molding space 50 not only through the air supply passage 34 but also through brick joints that form the ceiling 30.

In addition, although the same kind of gas is supplied to the high temperature space 51 and the low temperature space 52 of this embodiment via the air supply path 34 formed in each ceiling, a different kind of gas may be supplied. .

Gas is supplied to the high temperature space 51 from the outside of the molding apparatus 10 through a spout space 27 formed between the twill 23 and the inlet wall 26 in addition to the air supply path 34 formed on the ceiling. .

The gas may be supplied to the spout space 27 from at least one of the upper side and the side. This gas may be either an inert gas or a reducing gas. An exhaust path is not connected to the spout space 27, and most of the gas supplied to the spout space 27 passes below the inlet wall 26 and is supplied to the high temperature space 51.

An exhaust path 44 is formed on the side wall of the high temperature space 51 (that is, the upper side walls 32 and 33). The exhaust path 44 exhausts the gas in the high temperature space 51 to the outside of the molding apparatus 10. Hereinafter, the outside of the molding apparatus 10 may be read as the outside of the molding space 50. The exhaust path 44 may discharge gas using a pressure difference between the high temperature space 51 and the outside of the molding apparatus 10, or may discharge gas using a suction force of a pump or the like. The exhaust path 44 may be formed not only on the side wall of the high temperature space 51 but also on the side wall of the low temperature space 52.

Next, with reference to FIGS. 1 to 3 again, a method for manufacturing a float glass using the float glass apparatus having the above configuration will be described.

The float glass manufacturing method has a forming step in which the glass ribbon 14 is flowed on the liquid surface of the molten metal 11 in the bathtub 20 to form a plate shape. In the forming step, the width direction end of the glass ribbon 14 that has passed between the liquid surface of the molten metal 11 and the inlet wall 26 is pressed by the top roll 40, the top roll 40 rotates, and the glass ribbon 14 moves downstream. Fluidized.

Incidentally, as shown in FIG. 2, since the entire liquid surface of the molten metal 11 is covered with the glass ribbon 14 on the upstream side of the inlet wall 26, the amount of the metal-containing gas is small. On the other hand, on the downstream side of the inlet wall 26, a part of the liquid surface of the molten metal 11 is not covered with the glass ribbon 14, so that the amount of the metal-containing gas is large. Therefore, the partition wall 42 is disposed on the downstream side of the inlet wall 26. The high temperature space 51 on the upstream side of the partition wall 42 can capture a large amount of the metal-containing gas.

Also, the airflow tends to become unstable near the top roll 40. The causes of the unstable airflow include, for example, cold ambient air from the through hole through which the rotation shaft of the top roll 40 is inserted in the upper side wall 32, and the temperature difference between the top roll 40 cooled by the refrigerant and its surroundings. Etc. Therefore, the partition wall 42 is disposed on the most upstream side among the plurality of top rolls 40 arranged at intervals in the flow direction of the glass ribbon 14 (hereinafter referred to as “the most upstream top roll 40”). It arrange | positions rather than the upstream. The airflow in the vicinity of the partition wall 42 is stabilized, and the outflow of the metal-containing gas captured in the high temperature space 51 to the low temperature space 52 can be suppressed.

Thus, the partition wall 42 is disposed on the downstream side of the inlet wall 26, and is disposed on the upstream side of the most upstream top roll 40. Thereby, the high temperature space 51 upstream from the partition wall 42 can capture a large amount of the metal-containing gas, and the outflow of the metal-containing gas captured in the high temperature space 51 to the low temperature space 52 can be suppressed.

Further, as shown in FIG. 2, the partition wall 42 may be disposed in a range Z in which the viscosity of the glass ribbon 14 is 10 ^4.9 to 10 ^5.6 dPa · s in the flow direction of the glass ribbon 14. If the partition wall 42 is disposed in the range Z, the partition wall 42 is disposed at a position sufficiently away from the uppermost upstream roll 40 on the upstream side, so that the airflow in the vicinity of the partition wall 42 is easily stabilized. This is particularly effective in that the airflow can be stabilized when the thickness of the float glass is 2 mm or less, preferably 1 mm or less, and more preferably 0.7 mm or less. The thinner the float glass, the greater the number of top rolls 40 used to draw the glass ribbon 14 thinner. In such a case, if the partition wall 42 is disposed in the range Z, the partition wall 42 is disposed at a position sufficiently upstream from the uppermost top roll 40, so that the airflow in the vicinity of the partition wall 42 Is easy to stabilize. Further, if the partition wall 42 is disposed in the range Z, the partition wall 42 is disposed at a position sufficiently separated from the inlet wall 26 on the downstream side, so that the upstream high-temperature space 51 contains a large amount of metal-containing gas. Can capture. The partition wall 42 is preferably disposed in the flow direction of the glass ribbon 14 so that the viscosity of the glass ribbon 14 is in the range of 10 ^4.9 to 10 ^5.5 dPa · s, and the viscosity of the glass ribbon 14 is 10 ^5. More preferably, it is disposed in the range of ^0.0 to 10 ^5.4 dPa · s.

Between the partition wall 42 and the inlet wall 26, the ratio of the exposed portion of the liquid surface of the molten metal 11 that is not covered by the glass ribbon 14 may be 10 to 40%. If the ratio of the exposed portion is 10% or more, the high temperature space 51 formed between the partition wall 42 and the inlet wall 26 can sufficiently capture the metal-containing gas. Moreover, if the ratio of an exposed part is 40% or less, deterioration of the heater 36 by metal containing gas can be suppressed. The ratio of the exposed portion in the liquid surface of the molten metal 11 between the partition wall 42 and the inlet wall 26 is preferably 10 to 35%, more preferably 10 to 20%.

Further, as shown in FIG. 1, the partition wall 42 has a horizontal distance (X-direction distance) L1 between the upstream end of the inlet wall 26 and the upstream end of the partition wall 42 such that the upstream end of the inlet wall 26 and the outlet wall 28. May be disposed at a position that is 5 to 20% of the distance L2 in the X direction between the upstream end and the upstream end. If the distance L1 is 5% or more of the distance L2, the high temperature space 51 formed between the partition wall 42 and the inlet wall 26 can sufficiently capture the metal-containing gas. In addition, if the distance L1 is 20% or less of the distance L2, the partition wall 42 can be disposed at a position sufficiently away from the most upstream top roll 40 on the upstream side. The distance L1 is preferably 5 to 15% of the distance L2, and more preferably 5 to 10% of the distance L2.

The partition wall 42 protrudes downward from the ceiling 30. With reference to the exposed portion of the liquid surface of the molten metal 11, the height H1 (see FIG. 3) of the lower end of the partition wall 42 is, for example, 10 to 40% of the height H2 (see FIG. 1) of the lower surface of the ceiling 30. . If the height H1 of the lower end of the partition wall 42 is 10% or more of the height H2 of the lower surface of the ceiling 30, it is possible to monitor the glass ribbon downstream from the partition wall 42 from the uppermost stream of the molding space 50. is there. Further, if the height H1 of the lower end of the partition wall 42 is 40% or less of the height H2 of the lower surface of the ceiling 30, the metal-containing gas can be retained in the high temperature space 51, and the high temperature space 51 is moved to the low temperature space 52. The outflow of the metal-containing gas can be reduced. The height H1 of the lower end of the partition wall 42 is preferably 10 to 35% of the height H2 of the lower surface of the ceiling 30, and more preferably 10 to 20% of the height H2 of the lower surface of the ceiling 30.

The partition wall 42 may be movable in the vertical direction with respect to the ceiling 30 in order to make the height H1 variable. For example, as shown in FIGS. 1 and 3, a connecting rod 46 is connected to the partition wall 42, and a nut 47 is rotatably held on the roof casing 31. When the nut 47 is rotated, the connecting rod 46 screwed with the nut 47 moves in the vertical direction, and as a result, the partition wall 42 moves in the vertical direction.

In the high temperature space 51, the gas discharge amount Qout to the outside of the molding apparatus 10 is preferably 100% or more of the gas supply amount Qin from the outside of the molding apparatus 10, and more preferably 170% or more of the supply amount Qin. More preferably, it is 230% or more of the supply amount.

Here, Qin means the normal flow rate (Nm ³ / hr) of the gas supplied to the high temperature space 51 from at least one of the upper side, the side, and the upstream (from the upper side and the upstream side in this embodiment). The amount of gas supplied from the downstream is not included in Qin. The reason why the amount of gas supplied from the upstream (that is, the spout space 27) is included in Qin is that most of the gas supplied to the spout space 27 from the outside of the molding apparatus 10 is supplied to the high temperature space 51 as it is. . In addition, when gas is supplied to the high temperature space 51 from the side, an air supply path may be provided in the upper side walls 32 and 33.

On the other hand, Qout means the normal flow rate (Nm ³ / hr) of the gas discharged from the high temperature space 51 to at least one of the upper side and the side (side in this embodiment). The amount of gas discharged downstream and upstream is not included in Qout. Note that the amount of gas discharged to the upstream (that is, the spout space 27) is very small. This is because the exhaust path is not connected to the spout space 27. Note that when the gas is discharged upward from the high temperature space 51, an exhaust path may be provided in the ceiling 30.

If the discharge amount is equal to the supply amount, there is almost no gas inflow and outflow between the high temperature space 51 and the low temperature space 52, and there is almost no outflow of metal-containing gas from the high temperature space 51 to the low temperature space 52.

Further, if the discharge amount is larger than the supply amount, the gas is supplied from the low temperature space 52 to the high temperature space 51. Therefore, an air flow from the low temperature space 52 toward the high temperature space 51 is formed, and this air flow can suppress the outflow of the metal-containing gas from the high temperature space 51 to the low temperature space 52.

The manufactured float glass may be, for example, an alkali-free glass. The alkali-free glass is a glass that does not substantially contain an alkali metal oxide (Na ₂ O, K ₂ O, Li ₂ O, etc.). The alkali-free glass may have a total content of alkali metal oxides of 0.1% by mass or less.

The alkali-free glass is, for example, expressed by 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 8%, CaO: 0 to 14.5%, SrO: 0 to 24%, BaO: 0 to 13.5%, ZrO ₂ : 0 to 5%, MgO + CaO + SrO + BaO: 8 to 29.5%.

When the alkali-free glass has both a high strain point and high solubility, it is preferably expressed in terms of mass% on the basis of 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 18%.

When it is desired to obtain a particularly high strain point, the alkali-free 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 8%, CaO: 0 to 9%, SrO: 0 to 16%, BaO: 0 to 2.5%, MgO + CaO + SrO + BaO: 8 to 26%.

The molding temperature of these alkali-free glasses is 100 ° C. or more higher than the molding temperature of general soda lime glass. Therefore, the amount of the metal-containing gas that evaporates from the molten metal 11 is large, and it is significant that the partition wall 42 suppresses the outflow of the metal-containing gas from the high temperature space 51 to the low temperature space 52.

As mentioned above, although embodiment of the float glass manufacturing method and the float glass manufacturing apparatus was described, this invention is not limited to the said embodiment etc., In the range of the summary of this invention described in the claim Various modifications and improvements are possible.

This application claims priority based on Japanese Patent Application No. 2013-171982 filed with the Japan Patent Office on August 22, 2013. The entire contents of Japanese Patent Application No. 2013-171982 are incorporated herein by reference. To do.

DESCRIPTION OF SYMBOLS 10 Molding apparatus 11 Molten metal 12 Molten glass 14 Glass ribbon 20 Bathtub 22 Spaw trip 26 Entrance wall 30 Ceiling 40 Top roll 42 Partition wall 50 Molding space 51 High temperature space 52 Low temperature space

Claims

A bathtub containing molten metal;
An entrance wall located above the upstream portion of the bathtub;
An outlet wall located above the downstream part of the bathtub;
A ceiling disposed above the bathtub and extending from the entrance wall to the exit wall;
Provided at intervals along the flow direction of the glass ribbon flowing over the liquid surface of the molten metal, pressing the width direction end of the glass ribbon that has passed between the liquid surface and the inlet wall, And a plurality of top rolls rotating by itself,
A partition wall that partitions the molding space surrounded by the ceiling, the bathtub, the entrance wall and the exit wall into a high temperature space on the upstream side and a low temperature space on the downstream side;
An exhaust passage for discharging the gas in the high temperature space to the outside of the molding space,
The said partition wall is a float glass manufacturing apparatus arrange | positioned in the downstream rather than the said entrance wall, and was arrange | positioned upstream from the most upstream top roll among these top rolls.
The float glass manufacturing apparatus according to claim 1, wherein the partition wall is disposed in a range of a viscosity of 10 4.9 to 10 5.6 dPa · s in the flow direction of the glass ribbon.
The float glass production according to claim 1 or 2, wherein a ratio of an exposed portion which is not covered by the glass ribbon in the liquid surface of the molten metal is 10 to 40% between the partition wall and the inlet wall. apparatus.
The partition wall protrudes downward from the ceiling,
The height of the lower end of the partition wall is 10 to 40% of the height of the lower surface of the ceiling with reference to the exposed portion of the liquid level of the molten metal. Float glass manufacturing equipment.
The float glass manufacturing apparatus according to any one of claims 1 to 4, wherein the float glass to be manufactured is alkali-free glass.
Using the float glass manufacturing apparatus according to any one of claims 1 to 5,
A method for producing float glass, characterized in that the gas in the high temperature space is discharged to the outside of the forming space through the exhaust passage.
Using the float glass manufacturing apparatus according to claim 1,
A method for producing float glass, wherein the partition wall is disposed in a range of viscosity of 10 4.9 to 10 5.6 dPa · s in the flow direction of the glass ribbon.
Using the float glass manufacturing apparatus according to claim 1,
The method for producing float glass, wherein a ratio of an exposed portion of the molten metal liquid surface not covered by the glass ribbon is 10 to 40% between the partition wall and the inlet wall.
Using the float glass manufacturing apparatus according to claim 1,
The float glass manufacturing method whose float glass manufactured is an alkali free glass.