JP2015134691A - Float glass manufacturing method and float glass manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a float glass manufacturing device capable of lowering a frequency of replacement of a heater.SOLUTION: There is provided a float glass manufacturing device including: a bathtub in which molten metal is stored; a supply part which is installed at an upstream-side end of the bathtub, and supplies molten glass onto molten metal in the bathtub; a back tile which blocks molten glass flowing backward upstream from the position of supply of the molten glass by the supply part; a pair of side tiles which widen the width of the molten glass flowing downward from the back tile; a heater arranged between the supply part and back tile; and a pair of side blocks adjoining a downstream side of the supply part and mounted on the pair of saddle tiles. The heater has a heat generation part and a power supply part provided on both sides across the heat generation part, and the heat generation part is arranged inside in a width direction of the pair of side blocks.

Description

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

  The float glass manufacturing apparatus has a bathtub for containing molten metal, continuously supplies the molten glass on the molten metal in the bathtub, and forms the molten glass into a plate-like glass ribbon on the molten metal (for example, patent) Reference 1). The glass ribbon gradually hardens while flowing over the molten metal. The glass ribbon is pulled up from the molten metal in the downstream area of the bathtub and is sent toward the slow cooling furnace. The glass ribbon has a flat portion between both side edges. Since both side edges of the glass ribbon are thicker than the flat part of the glass ribbon, they are cut off after slow cooling. Thereby, the float glass of substantially uniform board thickness is obtained.

  The supply part which supplies a molten glass on the molten metal in a bathtub is installed in the edge part of the upstream of a bathtub. The molten glass supplied onto the molten metal by the supply unit forms a backflow that flows backward toward the upstream and a front flow that flows downstream. The backflow is redirected by the back tile and the pair of side tiles and merges on both sides of the front flow.

  A back tile stops the flow of the molten glass which flows backward from the supply position of the molten glass by a supply part toward upstream. The pair of side tiles increases the width of the molten glass from the back tile toward the downstream. A heater is disposed between the supply unit and the back tile, and the heater heats the back tile. Thereby, the fluidity | liquidity of the molten glass in the back tile vicinity can be improved.

JP 2007-131525 A

  Conventionally, there is a stagnation of gas below the supply unit, and the heater may continue to deteriorate due to the staying gas.

  This invention is made | formed in view of the said subject, Comprising: The main objective is to provide the float glass manufacturing apparatus which can reduce the replacement frequency of a heater.

In order to solve the above problems, according to one aspect of the present invention,
A bathtub containing molten metal;
A supply unit that is installed at an upstream end of the bathtub and supplies molten glass onto the molten metal in the bathtub;
A back tile that stops the flow of the molten glass that flows backward from the supply position of the molten glass by the supply unit;
A pair of side tiles that widen the width of the molten glass downstream from the back tile;
A heater disposed between the supply unit and the back tile;
A pair of side blocks that are installed on the downstream side of the supply unit and placed on the pair of side tiles;
The heater has a heat generating part and a power feeding part provided on both sides of the heat generating part,
A float glass manufacturing apparatus is provided in which the heat generating portion is disposed on the inner side in the width direction of the pair of side blocks.

  According to one aspect of the present invention, a float glass manufacturing apparatus that can reduce the replacement frequency of a heater is provided.

It is sectional drawing which shows the float glass manufacturing apparatus by one Embodiment of this invention, Comprising: It is sectional drawing along the II line | wire of FIG. It is sectional drawing along the II-II line of FIG. It is sectional drawing along the III-III line of FIG. It is sectional drawing along the IV-IV line of FIG. It is sectional drawing along the VV line of 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, “to” representing a numerical range means a range including numerical values before and after the numerical range. In the present specification, the “width direction” means a direction perpendicular to the flow direction of the molten glass.

  FIG. 1 is a cross-sectional view showing a float glass manufacturing apparatus according to an embodiment of the present invention, and is a cross-sectional view taken along the line II of FIG. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG.

  The float glass manufacturing apparatus 10 continuously supplies the molten glass G to the molten metal M in the bathtub 11 and forms the molten glass G into a plate-like glass ribbon on the molten metal M. The glass ribbon gradually becomes hard while flowing on the molten metal M. The glass ribbon is pulled up from the molten metal M in the downstream region of the bathtub 11 and sent toward the slow cooling furnace. The glass ribbon has a flat portion between both side edges. Since both side edges of the glass ribbon are thicker than the flat part of the glass ribbon, they are cut off after slow cooling. Thereby, the float glass of substantially uniform board thickness is obtained.

  The float glass manufacturing apparatus 10 includes a bathtub 11, a ceiling 12, a front lintel 13, a supply unit 14, a pair of heat insulation blocks 19, a pair of support blocks 21, a metal casing 23, a back tile 25, and a pair of side tiles 27. , A heater 29, a pair of side blocks 31, and the like.

  The bathtub 11 accommodates the molten metal M, as shown in FIG. The molten metal M may be a common one, and may be, for example, molten tin or a molten tin alloy.

  The ceiling 12 is disposed above the bathtub 11 and covers the upper space of the bathtub 11.

  The front lintel 13 partitions the upper space of the bathtub 11 into an upstream spout space and a downstream main space. The main space is much larger than the spout space. In order to prevent the molten metal M from being oxidized, reducing gas is supplied to the main space from the through hole of the ceiling 12. As the reducing gas, for example, a mixed gas of hydrogen gas and nitrogen gas is used. The front lintel 13 restricts the flow of reducing gas from the main space on the downstream side to the spout space on the upstream side. When a member made of platinum or a platinum alloy is present upstream of the spout space or the spout space, deterioration of the member can be limited.

  The supply unit 14 is installed at the upstream end of the bathtub 11 and supplies the molten glass G onto the molten metal M in the bathtub 11. As shown in FIGS. 1 and 3, the supply unit 14 includes a spout lip 15, a pair of side jamb 16 disposed on both sides of the spout trip 15, and a pair of side jams. And twele 17 inserted between the two.

  As shown in FIG. 1, the spout trip 15 integrally includes a horizontal portion 15a and an inclined portion 15b extending obliquely downward from a downstream end of the horizontal portion 15a. Molten glass G flowing on the spout trip 15 is thrown into the bathtub 11 from the downstream end of the inclined portion 15b.

  As shown in FIG. 3, the space under the spout trip 15 extends laterally under the pair of side jams 16 and under the pair of heat insulating blocks 19. On the other hand, a space above the spout trip 15 is formed between the pair of side jams 16.

  As shown in FIG. 3, the pair of side jams 16 prevents the molten glass G flowing on the spout trip 15 from overflowing outward in the width direction. Each side jam 16 integrally includes a width direction inner portion 16a and a width direction outer portion 16b. The lower surface of each width direction inner part 16a is formed along the lower surface of the spout trip 15, and has a horizontal surface and an inclined surface. On the other hand, the lower surface of the width direction outer side portion 16 b is flush with the lower surface of the horizontal portion 15 a of the spout trip 15.

  The twill 17 protrudes downward from the ceiling 12 as shown in FIG. 1, and is inserted between the pair of side jams 16 as shown in FIG. The twill 17 is movable in the vertical direction with respect to the spout trip 15. Molten glass G having a flow rate corresponding to the size of the opening surrounded by the spout trip 15, the pair of side jams 16, and the twill 17 is supplied into the bathtub 11. The contact surface of the twill 17 with the molten glass G may be covered with a protective film made of platinum or a platinum alloy.

  The pair of heat insulation blocks 19 sandwich the pair of side jams 16 as shown in FIG. The lower surface of each heat insulation block 19 is flush with the lower surface of the width direction outer side portion 16 b of each side jam 16.

  As shown in FIG. 3, the pair of support blocks 21 sandwich the metal casing 23 between the pair of heat insulation blocks 19 and support the metal casing 23 from below.

  The metal casing 23 has a bottom wall portion 23a and a side wall portion 23b extending upward from the outer edge of the bottom wall portion 23a. The bottom wall portion 23a is formed, for example, in a U-shape. On the bottom wall portion 23a, as shown in FIGS. 1 and 3, the horizontal portion 15a of the spout trip 15, the width direction outer side portion 16b of each side jam 16, And the heat insulation block 19 etc. are mounted.

  As indicated by arrows in FIG. 5, the molten glass G forms a backflow that flows backward from the supply position of the molten glass G by the supply unit 14 and a front flow that flows downstream. The backflow includes a portion in contact with the spout trip 15 and includes bubbles generated by a reaction with the spout trip 15. The direction of the back flow is changed by the back tile 25 and the pair of side tiles 27 and merges with both sides of the front flow. Bubbles gather on both side edges of the glass ribbon, and defects in the flat part of the glass ribbon can be reduced.

  The back tile 25 is disposed below the spout trip 15 as shown in FIG. 1, and stops the flow of the molten glass G that flows backward toward the upstream as shown in FIG.

  As shown in FIG. 5, the pair of side tiles 27 increases the width of the molten glass G that travels downstream from the back tile 25. The pair of side tiles 27 are inclined with respect to the center line of the molten glass G supplied on the molten metal M, and the distance between the pair of side tiles 27 is wider toward the downstream.

  As shown in FIG. 1, the heater 29 is disposed between the supply unit 14 and the back tile 25 and heats the back tile 25. The fluidity of the molten glass G in the vicinity of the back tile 25 can be improved.

  As shown in FIGS. 3 and 5, the heater 29 includes a heat generating portion 29 a and power feeding portions 29 b provided on both sides of the heat generating portion 29 a. The power feeding unit 29b supplies power to the heat generating unit 29a.

  The heater 29 may be a silicon carbide heater, for example. In this case, the power feeding unit 29b includes a metal material such as metal silicon and has a higher conductivity than the heat generating unit 29a.

  The heater 29 may be rod-shaped and parallel to the width direction of the molten glass G. The molten glass G tends to flow outward in the width direction along the back tile 25.

  The heater 29 may be either cylindrical or cylindrical, but may be cylindrical from the viewpoint of raw material cost. The outer diameter of the heater 29 is, for example, 20 mm to 40 mm.

  The open porosity (Japanese Industrial Standard JIS R1634) of the heater 29 is, for example, 25% or less, preferably 10% or less. When the open porosity of the heater 29 is 10% or less, deterioration of the heater 29 due to gas can be suppressed.

  The pair of side blocks 31 are disposed between the supply unit 14 and the front lintel 13 as shown in FIGS. 1, 4, and 5. The pair of side blocks 31 are adjacent to the downstream side of the supply unit 14 and are placed on the pair of side tiles 27 as shown in FIG. Each side block 31 is formed of a heat-resistant brick or the like, and comes into contact with the side jam 16 and the heat insulation block 19 through the metal casing 23 as shown in FIG.

  Each side block 31 has a through hole 31a as shown in FIGS. 1 and 2, and gas is supplied from the through hole 31a to the spout space. Examples of the gas supplied to the spout space include an inert gas such as nitrogen gas and a reducing gas. As the reducing gas, for example, a mixed gas of nitrogen gas and hydrogen gas may be used. When reducing gas is supplied to the spout space, the hydrogen gas concentration (volume%) of the reducing gas supplied to the spout space is higher than the hydrogen gas concentration (volume%) of the reducing gas supplied to the main space. It can be low. When a member made of platinum or a platinum alloy is present upstream of the spout space or the spout space, deterioration of the member can be limited.

  In the present embodiment, the gas supplied to the spout space is supplied from the pair of side blocks 31, but may be supplied from the ceiling 12 or the pair of side jams 16.

  The spout space is surrounded by the bathtub 11, the ceiling 12, the front lintel 13, the twill 17, the pair of side jams 16, the pair of side blocks 31, and the like. In the spout space, the gas passes between the pair of side blocks 31 and moves back and forth between the spout trip 15 and the lower side.

  Under the spout trip 15, as shown in FIG. 5, there is a space wider than the distance between the pair of side blocks 31. In the space, a gas flow is formed on the inner side in the width direction of the pair of side blocks 31, and a gas flow is hardly formed on the outer side in the width direction than the gap between the pair of side blocks 31. This is because the gas passes between the pair of side blocks 31 and travels between the upper side and the lower side of the spout trip 15.

  Since the heat generating portion 29a is disposed in the space below the spout trip 15 as shown in FIG. 3, it is disposed inside the pair of side blocks 31 in the width direction as shown in FIG. The gas passing between the pair of side blocks 31 can disturb the gas around the heat generating portion 29a. Therefore, it can restrict | limit that the heat-emitting part 29a continues deteriorating with gas.

  Examples of the deterioration of the heat generating portion 29a due to gas include active oxidation under a low oxygen partial pressure. When heat generating portion 29a contains silicon carbide, silicon monoxide is produced when silicon carbide is actively oxidized. Since silicon monoxide is volatile, when silicon monoxide is generated, the heat generating portion 29a becomes porous.

  According to this embodiment, since the gas around the heat generating part 29a can be disturbed, it can be restricted that the heat generating part 29a continues to deteriorate due to the gas. In addition, since the length of the heat generating portion 29a is shorter than the distance between the pair of side blocks 31, and the length of the heat generating portion 29a is shorter than the conventional one, thermal deformation of the metal casing 23 can be suppressed.

  The heat generating portion 29a may extend to the outside in the width direction of the molten glass G so as to uniformly heat the entire width direction of the molten glass G flowing down from the supply portion 14 as shown in FIG. The length L of the heat generating part 29 a may be longer than the width W of the molten glass G flowing down from the supply part 14.

  In addition, the length L of the heat generating part 29a may be shorter than the width W of the molten glass G flowing down from the supply part 14. The length L of the heat generating portion 29a is, for example, 1/3 or more of the width W, preferably 2/3 or more of the width W. If the length L of the heat generating portion 29a is 2/3 or more of the width W, the back tile 25 can be heated sufficiently and the surface temperature of the heat generating portion 29a is sufficiently low. Active oxidation tends to occur at high temperatures.

  Next, with reference to FIG. 1 again, a float glass manufacturing method using the float glass manufacturing apparatus 10 having the above-described configuration will be described.

  The float glass manufacturing method has a forming step of continuously supplying the molten glass G onto the molten metal M in the bathtub 11 and forming the molten glass G into a plate-like glass ribbon on the molten metal M. The glass ribbon gradually becomes hard while flowing on the molten metal M. The glass ribbon is pulled up from the molten metal M in the downstream region of the bathtub 11 and conveyed toward the slow cooling furnace. Since both side edges of the glass ribbon are thicker than the flat part inside, the glass ribbon is cut off after the slow cooling. Thereby, the float glass of substantially uniform board thickness is obtained.

  According to the present embodiment, the heat generating portion 29 a of the heater 29 is disposed on the inner side in the width direction of the pair of side blocks 31. The gas passing between the pair of side blocks 31 can disturb the gas around the heat generating portion 29a. Therefore, the heat generating portion 29a does not continue to deteriorate due to the gas. Therefore, the replacement frequency of the heater 29 can be reduced.

  The thickness of the manufactured float glass is, for example, 1.0 mm or less, preferably 0.7 mm or less. That is, the thickness of the flat portion of the glass ribbon is, for example, 1.0 mm or less, preferably 0.7 mm or less.

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

The float glass produced may be alkali-free glass when used as a glass substrate for a display. The alkali-free glass is a glass that does not substantially contain an alkali metal oxide such as Na ₂ O, K ₂ O, or Li ₂ O. The alkali-free glass may have a total content of alkali metal oxides of 0.1% by mass or less.

Alkali-free glass, for example, represented by mass% based on _{oxide, SiO 2: 50% ~73%} , Al 2 O 3: 10.5% ~24%, B 2 O 3: 0% ~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 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 Contains 18%.

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

  The float glass produced may be a chemically strengthened glass when used as a cover glass for a display. What chemically-strengthened the glass for chemical strengthening is used as a cover glass. In the chemical strengthening treatment, ions having a small ion radius (for example, Li ions or Na ions) among alkali ions contained on the glass surface are replaced with ions having a large ion radius (for example, K ions) to obtain a predetermined depth from the glass surface. A compressive stress layer is formed.

Chemically strengthened glass, for example as represented by mol% based on _{oxides, SiO 2: 62% ~68%} , Al 2 O 3: 6% ~12%, MgO: 7% ~13%, Na 2 O: 9% to _17%, K 2 O: containing 0% to 7%, the difference obtained by subtracting the content of _Al 2 _{O 3} from the total content of Na ₂ O and _{K 2} O is less than 10%, a ZrO ₂ When it contains, the content is 0.8% or less.

Another chemically strengthened glass is represented by mol% based on _{oxides, SiO 2: 65% ~85%} , Al 2 O 3: 3% ~15%, Na 2 O: 5% ~15%, K 2 O : 0% to less than 2%, MgO: 0% to 15%, ZrO ₂ : 0% to 1%, the total content of SiO ₂ and Al ₂ O ₃ SiO ₂ + Al ₂ O ₃ is 88% or less It is.

The float glass produced may be soda lime glass when used as a window glass. Soda lime glass, for example, represented by mass% based on _{oxide, SiO 2: 65% ~75%} , Al 2 O 3: 0% ~3%, CaO: 5% ~15%, MgO: 0% ~15% , Na ₂ O: 10% to 20%, K ₂ O: 0% to 3%, Li ₂ O: 0% to 5%, Fe ₂ O ₃ : 0% to 3%, TiO ₂ : 0% to 5% CeO ₂ : 0% to 3%, BaO: 0% to 5%, SrO: 0% to 5%, B ₂ O ₃ : 0% to 5%, ZnO: 0% to 5%, ZrO ₂ : 0% _{~5%, SnO 2: 0%} ~3%, SO 3: contains 0% to 0.5%.

  As mentioned above, although embodiment of the float glass manufacturing apparatus and the float glass manufacturing method 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 Can be modified and improved.

DESCRIPTION OF SYMBOLS 10 Float glass manufacturing apparatus 11 Bath 12 Ceiling 13 Front lintel 14 Supply part 15 Spout trip 16 Side jam 17 Twill 19 Heat insulation block 21 Support block 23 Metal casing 25 Back tile 27 Side tile 29 Heater 31 Side block G Molten glass M Molten metal

Claims (11)

A bathtub containing molten metal;
A supply unit that is installed at an upstream end of the bathtub and supplies molten glass onto the molten metal in the bathtub;
A back tile that stops the flow of the molten glass that flows backward from the supply position of the molten glass by the supply unit;
A pair of side tiles that widen the width of the molten glass downstream from the back tile;
A heater disposed between the supply unit and the back tile;
A pair of side blocks that are installed on the downstream side of the supply unit and placed on the pair of side tiles;
The heater has a heat generating part and a power feeding part provided on both sides of the heat generating part,
The float glass manufacturing apparatus, wherein the heat generating portion is disposed on the inner side in the width direction of the pair of side blocks.   The float glass manufacturing apparatus according to claim 1, wherein the heater is a silicon carbide heater.   The float glass manufacturing apparatus according to claim 1, wherein the heater has a rod shape and is parallel to a width direction of the molten glass.   The float glass manufacturing method using the float glass manufacturing apparatus of any one of Claims 1-3.   The float glass manufacturing method according to claim 4, wherein the manufactured float glass is an alkali-free glass. The alkali-free glass is represented by mass% based on _{oxide, SiO 2: 50% ~73%} , Al 2 O 3: 10.5% ~24%, B 2 O 3: 0% ~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% to The float glass manufacturing method of Claim 5 containing 5%.   The float glass manufacturing method according to claim 4, wherein the manufactured float glass is a glass for chemical strengthening. The chemically strengthened glass is represented by mol% based on _{oxides, SiO 2: 62% ~68%} , Al 2 O 3: 6% ~12%, MgO: 7% ~13%, Na 2 O: 9% to _17%, K 2 O: containing 0% to 7%, the difference obtained by subtracting the content of _Al 2 _{O 3} from the total content of Na ₂ O and _{K 2} O is less than 10%, a ZrO ₂ The float glass manufacturing method of Claim 7 whose content is 0.8% or less when it contains. The chemically strengthened glass is represented by mol% based on _{oxides, SiO 2: 65% ~85%} , Al 2 O 3: 3% ~15%, Na 2 O: 5% ~15%, K 2 O: 0% to less than 2%, MgO: 0% to 15%, ZrO ₂ : 0% to 1%, and the total content of SiO ₂ and Al ₂ O ₃ is SiO ₂ + Al ₂ O ₃ is 88% or less The method for producing float glass according to claim 7.   The float glass manufacturing method according to claim 4, wherein the manufactured float glass is soda lime glass. The soda lime glass is expressed in terms of mass% based on oxide, SiO ₂ : 65% to 75%, Al ₂ O ₃ : 0% to 3%, CaO: 5% to 15%, MgO: 0% to 15%. , Na ₂ O: 10% to 20%, K ₂ O: 0% to 3%, Li ₂ O: 0% to 5%, Fe ₂ O ₃ : 0% to 3%, TiO ₂ : 0% to 5% CeO ₂ : 0% to 3%, BaO: 0% to 5%, SrO: 0% to 5%, B ₂ O ₃ : 0% to 5%, ZnO: 0% to 5%, ZrO ₂ : 0% _{~5%, SnO 2: 0%} ~3%, SO 3: 0% to containing 0.5%, float glass manufacturing method according to claim 10.

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