JP2022034527A - Float glass manufacturing apparatus and float glass manufacturing method - Google Patents

Abstract

To provide a technology for obtaining a glass ribbon having a large width and a plane thickness deviation.SOLUTION: A float glass manufacturing apparatus includes a bath, a spout lip, a pair of restrictor tiles, a plurality of top rolls, a ceiling, a plurality of heaters, and a plurality of controllers. In each section that is composed by dividing the ceiling into a plurality of rows in a glass ribbon flowing direction and then dividing each row in a width direction of the glass ribbon, the heaters that are, except a specified section, collectively controlled by one of the controllers selected for each section are installed. The specified section is the section just above a downstream edge of each restrictor tile. In each sub section that is made by dividing the specified section in the flow direction, the heaters that are collectively controlled by one of the controllers selected for each sub section are installed.SELECTED DRAWING: Figure 4

Description

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

The float glass manufacturing apparatus continuously supplies the molten glass onto the molten metal in the bathtub, causes the molten glass to flow on the molten metal, and forms the molten glass into a strip-shaped glass ribbon. After the glass ribbon is slowly cooled, both ends of the glass ribbon in the width direction are cut off to obtain a float glass. Float glass is used for a glass substrate of a flat panel display (FPD) or the like.

Patent Document 1 describes a technique for controlling the temperature distribution of the glass ribbon in order to reduce the plate thickness deviation of the float glass. A plurality of heaters are provided in each section in which the heater region is divided into a plurality of rows in the flow direction of the glass ribbon and each row is divided in the width direction of the glass ribbon, and each section is collectively controlled.

Japanese Unexamined Patent Publication No. 8-325024

With the increase in the screen size of FPDs, wide glass ribbons are desired. However, the wider the width of the glass ribbon, the larger the plate thickness deviation of the glass ribbon tends to be. The plate thickness deviation is the difference between the maximum value and the minimum value of the plate thickness.

One aspect of the present disclosure provides a technique for obtaining a glass ribbon having a wide width and a small plate thickness deviation.

The float glass manufacturing apparatus according to one aspect of the present disclosure includes a bathtub, a spout trip, a pair of restrictor tiles, a plurality of top rolls, a ceiling, a plurality of heaters, and a plurality of controllers. The bathtub houses the molten metal. The spout trip continuously supplies the molten glass onto the molten metal. The pair of restrictor tiles widens the flow width of the molten glass supplied over the molten metal from the upstream side to the downstream side. The plurality of top rolls press the widthwise end of the strip-shaped glass ribbon downstream of the pair of restrictor tiles. The ceiling is provided above the glass ribbon. The plurality of heaters are suspended from the ceiling. The plurality of controllers control the plurality of the heaters. The ceiling is divided into a plurality of rows in the flow direction of the glass ribbon, and each of the rows is divided in the width direction of the glass ribbon, and each section is selected for each section except for a specific section. A plurality of the heaters, which are collectively controlled by the one controller, are provided. The particular compartment is the compartment directly above the downstream end of each restrictor tile. Each sub-compartment formed by dividing the specific section in the flow direction is provided with a plurality of the heaters collectively controlled by one controller selected for each sub-compartment.

According to one aspect of the present disclosure, a glass ribbon having a wide width and a small plate thickness deviation can be obtained.

FIG. 1 is a vertical cross-sectional view of a float glass manufacturing apparatus according to an embodiment, and is a vertical cross-sectional view taken along the line II of FIG. FIG. 2 is a horizontal cross-sectional view of the float glass manufacturing apparatus according to the embodiment, and is a horizontal cross-sectional view taken along the line II-II of FIG. FIG. 3 is a plan view showing an example of the flow of molten glass on the molten metal. FIG. 4 is a plan view showing an example of a ceiling section. FIG. 5 is a cross-sectional view showing an example of convection of molten metal in the deep bottom region. FIG. 6 is a plan view showing a float glass manufacturing apparatus according to a modified example. FIG. 7 is a cross-sectional view showing an example of a cooling pipe and a heat insulating material. FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.

Hereinafter, the float glass manufacturing apparatus and the float glass manufacturing method according to the embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations may be designated by the same reference numerals and description thereof may be omitted. In each drawing, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other, the X-axis direction and the Y-axis direction are the horizontal direction, and the Z-axis direction is the vertical direction. The X-axis direction is the flow direction of the glass ribbon GR, and the Y-axis direction is the width direction of the glass ribbon GR. In the specification, "-" indicating a numerical range means that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

As shown in FIG. 1, the float glass manufacturing apparatus 1 continuously supplies the molten glass G onto the molten metal M in the bathtub 10, causes the molten glass G to flow on the molten metal M, and forms a strip. It is molded into the glass ribbon GR of. The glass ribbon GR is pulled up from the molten metal M in the downstream region of the bathtub 10, then slowly cooled by a slow cooling device (not shown), and cut to a predetermined size by a processing device (not shown). The processing device cuts both ends of the glass ribbon GR in the width direction. Float glass, which is a product, can be obtained by processing the glass ribbon GR with a processing device.

Examples of the type of float glass include non-alkali glass, aluminosilicate glass, borosilicate glass and soda lime glass. The non-alkali glass means a glass that does not substantially contain alkali metal oxides such as Na ₂ O and K ₂ O. Here, "substantially containing no alkali metal oxide" means that the total content of the alkali metal oxide is 0.1% by mass or less.

The use of the float glass is not particularly limited, but is, for example, a flat panel display (FPD) such as a liquid crystal display (LCD) or an organic EL display, and is, for example, a glass substrate for FPD. When the use of the float glass is a glass substrate for FPD, the type of the glass of the float glass is non-alkali glass.

Float glass is expressed in terms of mass% based on oxides, SiO ₂ : 54% to 66%, Al ₂ O ₃ : 10% to 23%, B ₂ O ₃ : 6% to 12%, MgO + CaO + SrO + BaO: 8% to 26. A non-alkali glass substrate containing% is preferable.

Float glass should have a high strain point in terms of oxide-based mass%, SiO ₂ : 54% to 68%, Al ₂ O ₃ : 10% to 25%, B ₂ O ₃ : 0.1%. A non-alkali glass substrate containing ~ 5.5%, MgO + CaO + SrO + BaO: 8% to 26% is preferable.

The thickness of the float glass is selected according to the application of the float glass. When the use of the float glass is a glass substrate for FPD, the plate thickness of the float glass is preferably 0.7 mm or less, more preferably 0.5 mm or less, still more preferably 0.4 mm or less, 0.3 mm or less, 0. It may be .2 mm or less, or 0.1 mm or less.

The plate thickness of the float glass is measured over the entire width direction of the glass ribbon GR after the end portion in the width direction of the glass ribbon GR is cut off. The plate thickness deviation of the float glass is calculated based on the result of the plate thickness measurement of the float glass.

As shown in FIG. 1, the float glass manufacturing apparatus 1 includes a bathtub 10. The bathtub 10 accommodates the molten metal M. As the molten metal M, for example, molten tin is used. In addition to molten tin, a molten tin alloy or the like can also be used, and the molten metal M may have a higher density than the molten glass G.

The bathtub 10 includes a box-shaped bottom casing 11 opened upward, a side brick 12 that protects the side wall of the bottom casing 11 from the molten metal M, and a bottom brick 13 provided inside the bottom wall of the bottom casing 11. Has.

The float glass manufacturing apparatus 1 includes a spout trip 14. The spout trip 14 supplies the molten glass G onto the molten metal M in the bathtub 10. As shown in FIG. 2, the side jams 16 and 17 sandwich the spout trip 14 in the width direction and prevent the molten glass G flowing over the spout trip 14 from spilling in the width direction.

As shown in FIG. 1, the float glass manufacturing apparatus 1 includes a twill 18. The twill 18 is movable up and down with respect to the spout trip 14, and adjusts the flow rate of the molten glass G flowing over the spout trip 14. The narrower the distance between the twill 18 and the spout trip 14, the smaller the flow rate of the molten glass G flowing over the spout trip 14.

The twill 18 is made of a refractory material. The twill 18 may be formed with a protective film 19 that prevents the twill 18 from coming into contact with the molten glass G. The protective film 19 is formed of, for example, platinum or a platinum alloy.

As shown in FIG. 3, the float glass manufacturing apparatus 1 has a wet back tile 22 and a pair of restrictor tiles 24 and 25. The wet back tile 22 is provided below the spout trip 14 and comes into contact with the upstream end of the molten glass G. The pair of restrictor tiles 24 and 25 extend diagonally downstream from the wet back tile 22 and expand downstream. The pair of restrictor tiles 24 and 25 gradually widen the width of the flow of the molten glass G from the upstream side to the downstream side.

The molten glass G is supplied onto the molten metal M and then forms a main stream F1 and a tributary F2. The main stream F1 flows in the positive direction of the X axis. On the other hand, the tributary F2 flows backward toward the wet back tile 22 in the negative direction on the X-axis. When the tributary F2 reaches the wet back tile 22, it flows separately to the left and right along the wet back tile 22, then flows along the pair of left and right restrictor tiles 24 and 25, and joins both ends in the width direction of the main stream F1. do.

Therefore, at both ends in the width direction of the glass ribbon GR, foreign components generated by contact between the spout trip 14, the wet back tile 22, and the restrictor tiles 24 and 25 and the molten glass G are collected. Since both ends of the glass ribbon GR in the width direction are cut off after slow cooling and do not become a part of the product, good quality float glass can be obtained.

As shown in FIG. 1, the float glass manufacturing apparatus 1 includes an upper space S of the bathtub 10. The ceiling 27 forms the upper surface of the space S above the bathtub 10. Further, the partition wall 28 partitions the upper space S of the bathtub 10 into the spout space S1 on the upstream side and the main space S2 on the downstream side. The partition wall 28 is also called a front lintel.

The main space S2 is sufficiently larger than the spout space S1. The main space S2 is filled with a reducing gas in order to prevent oxidation of the molten metal M. The reducing gas is, for example, a mixed gas of nitrogen gas and hydrogen gas, and contains 85% by volume to 98.5% by volume of nitrogen gas and 1.5% by volume to 15% by volume of hydrogen gas. The reducing gas is supplied from the joints between the bricks of the ceiling 27 and the holes of the ceiling 27.

As shown in FIG. 3, the float glass manufacturing apparatus 1 includes a top roll 30. The top roll 30 rotates while pressing the widthwise end portion of the glass ribbon GR, and feeds out the glass ribbon GR in the X-axis direction. The glass ribbon GR is gradually cooled and hardened while moving in the X-axis direction.

A pair of top rolls 30 are provided on both sides of the glass ribbon GR in the width direction to suppress shrinkage of the glass ribbon GR in the width direction. The plate thickness of the glass ribbon GR can be made thinner than the equilibrium thickness. Although not shown, a plurality of a pair of top rolls 30 are provided at intervals in the flow direction of the glass ribbon GR.

The top roll 30 has a rotating member 31 and a rotating shaft 32. The rotating member 31 has, for example, a disk shape, and presses the end portion of the glass ribbon GR in the width direction at the outer periphery thereof, and sends out the glass ribbon GR in the flow direction of the glass ribbon GR. The rotary shaft 32 is rotationally driven by a drive device (not shown) to rotate the rotary member 31.

As shown in FIG. 1, the float glass manufacturing apparatus 1 includes a heater 50. The heater 50 is suspended from the ceiling 27 and heats the glass ribbon GR passing below. The heater 50 is an electric heater and is energized and heated. The heater 50 is, for example, a SiC heater. A plurality of heaters 50 are arranged in a matrix in the flow direction and the width direction of the glass ribbon GR.

By controlling the outputs of the plurality of heaters 50, the temperature distribution of the glass ribbon GR can be controlled, and the plate thickness distribution of the glass ribbon GR can be controlled. The output of the heater 50 means the amount of heat (unit: kW) per unit time. The output of the plurality of heaters 50 is controlled for each of the compartments A1, A3, A5, B1 to B4 except for the specific compartments A2 and A4 (see FIG. 4).

Next, a method of partitioning the ceiling 27 will be described with reference to FIG. The ceiling 27 is divided into a plurality of rows A and B in the flow direction of the glass ribbon GR. Each row A and B is divided into a plurality of sections A1 to A5 and B1 to B4 in the width direction of the glass ribbon GR. It is preferable that the rows A and B are symmetrically divided about the center line CL in the width direction of the glass ribbon GR. The temperature distribution of the glass ribbon GR can be controlled symmetrically with respect to the center line CL in the width direction of the glass ribbon GR.

In each section A1 to A5 and B1 to B4, a plurality of heaters collectively controlled by one controller 60 selected for each section A1, A3, A5, B1 to B4 except for specific sections A2 and A4. 50 is provided. Controlling all at once includes controlling to the same output. By controlling a plurality of heaters 50 at once with one controller 60, the number of controllers 60 can be reduced. The controller 60 is, for example, a microcomputer.

The boundary line D1 of the two rows A and B adjacent to each other in the flow direction of the glass ribbon GR is also referred to as a first partition line D1. Further, the boundary line D2 of the two sections adjacent to each other in the width direction of the glass ribbon GR is also referred to as a second dividing line D2. It is preferable that the second dividing line D2 is displaced in the width direction of the glass ribbon GR between the row A and the row B with the first dividing line D1 interposed therebetween.

For example, the boundary line D2 between the section A1 and the section A2 and the boundary line D2 between the section B1 and the section B2 are deviated from each other in the width direction of the glass ribbon GR with the first dividing line D1 interposed therebetween. Therefore, the portion of the glass ribbon GR that has passed below the boundary line D2 between the compartment A1 and the compartment A2 in the upstream row A will pass below the compartment B1 in the downstream row B.

In the upstream row A, if the output (unit: kW / m ² ) of the heater 50 per unit area is different between the compartment A1 and the compartment A2, the width of the glass ribbon GR near the boundary line D2 between the compartment A1 and the compartment A2. A sudden temperature difference occurs in the direction. This temperature difference also occurs in the portion of the glass ribbon GR that passes below the boundary line D2 between the compartment A1 and the compartment A2. The site passes below the compartment B1 in the downstream row B, at which time the temperature difference is alleviated. As a result, the plate thickness deviation of the glass ribbon GR can be reduced.

In the bathtub 10, the region from the downstream end of the pair of restrictor tiles 24 and 25 to the pair of top rolls 30 of the uppermost stream is also referred to as a hot region X1. Further, the region downstream of the pair of top rolls 30 of the uppermost stream is also referred to as a molding region X2. The viscosity of the glass ribbon GR in the hot region X1 is, for example, 10 ^3.8 dPa · s to 10 ^5.0 dPa · s. The viscosity of the glass ribbon GR in the molding region X2 is, for example, 10 ^5.0 dPa · s to 10 ^7.5 dPa · s.

In the molding region X2, the shrinkage of the glass ribbon GR in the width direction is suppressed, and the plate thickness distribution in the width direction of the glass ribbon GR is adjusted. Therefore, it is important to make the temperature distribution and the plate thickness distribution in the width direction of the glass ribbon GR as uniform as possible in advance in the hot region X1 upstream of the molding region X2. If the temperature distribution is made uniform, the plate thickness distribution is also made uniform.

Therefore, the specific compartments A2 and A4 are further divided into a plurality of sub-compartments in the flow direction of the glass ribbon GR. The specific compartments A2 and A4 are compartments directly above the downstream ends of the restrictor tiles 24 and 25, respectively. The pair of specific compartments A2 and A4 are arranged at intervals W1 in the flow direction of the glass ribbon GR. In the meantime, it is preferable to arrange the compartment A3 which is collectively controlled by one controller 60.

For example, the specific compartment A2 is divided into a plurality of sub-compartments A2-1 and A2-2 in the flow direction of the glass ribbon GR. Each sub-compartment A2-1 and A2-2 are provided with a plurality of heaters 50 that are collectively controlled by one controller 60 selected for each sub-compartment A2-1 and A2-2. It is preferable that the sub-compartments A2-1 and A2-2 are arranged directly above the hot region X1. The downstream sub-compartment A2-2 protrudes outward in the width direction of the glass ribbon GR from the upstream sub-compartment A2-1.

Similarly, the specific compartment A4 is divided into a plurality of sub-compartments A4-1 and A4-2 in the flow direction of the glass ribbon GR. Each sub-compartment A4-1 and A4-2 are provided with a plurality of heaters 50 collectively controlled by one controller 60 selected for each sub-compartment A4-1 and A4-2. It is preferable that the sub-compartments A4-1 and A4-2 are arranged directly above the hot region X1. The downstream sub-compartment A4-2 protrudes outward in the width direction of the glass ribbon GR from the upstream sub-compartment A4-1.

The width of the glass ribbon GR increases from the upstream side to the downstream side in the hot region X1. Both ends of the glass ribbon GR in the width direction, that is, the low temperature portions of the glass ribbon GR pass directly under the sub-compartments A2-1 and A4-1 on the upstream side. On the other hand, the central portion in the width direction of the glass ribbon GR, that is, the high temperature portion of the glass ribbon GR passes directly under the compartment A3 without passing directly under the sub-compartments A2-1 and A4-1 on the upstream side. .. After that, a part of the high temperature portion of the glass ribbon GR passes directly under the sub-compartments A2-2 and A4-2 on the downstream side.

According to the present embodiment, the output of the heater 50 per unit area can be independently controlled by the upstream sub-compartments A2-1 and A4-1 and the downstream sub-compartments A2-2 and A4-2. Therefore, in the hot region X1 upstream of the molding region X2, the temperature distribution and the plate thickness distribution in the width direction of the glass ribbon GR can be made uniform. As a result, a glass ribbon GR having a wide width and a small plate thickness deviation can be obtained.

When heating the glass ribbon GR, the output of the heater 50 per unit area of the downstream sub-compartments A2-2 and A4-2 is the heater per unit area of the upstream sub-compartments A2-1 and A4-1. It is controlled to be smaller than the output of 50. The low temperature part of the glass ribbon GR passes directly under the sub-compartments A2-1 and A4-1 on the upstream side, while the high temperature part of the glass ribbon GR passes directly under the sub-compartments A2-2 and A4- on the downstream side. This is because it passes directly under 2.

When heating the glass ribbon GR, the output of the heater 50 per unit area of the sub-compartments A2-1 and A4-1 on the upstream side is preferably 3 kW / m ² or more and 42 kW / m ² or less, more preferably 10 kW /. It is controlled to m ² or more and 38 kW / m ² or less. On the other hand, the output of the heater 50 per unit area of the sub-compartments A2-2 and A4-2 on the downstream side is preferably 0 kW / m ² or more and 5 kW / m ² or less, more preferably 0 kW / m ² or more and 4.5 kW /. It is controlled to m ² or less.

When heating the glass ribbon GR, the output of the heater 50 per unit area of the sub-compartments A2-2 and A4-2 on the downstream side may be 0 kW / m ² . The sub-compartments A2-2 and A4-2 on the downstream side may be used for heating the bathtub 10 at the time of heating in the stage before starting the production of the float glass, and may not be used for heating the glass ribbon GR. good.

The sub-compartments A2-1 and A4-1 on the upstream side are arranged directly above the downstream ends of the restrictor tiles 24 and 25, and heat the downstream ends thereof. Therefore, the stagnation of the flow of the molten glass G in the vicinity of the downstream end thereof can be suppressed, and the devitrification can be suppressed. Devitrification is a phenomenon in which crystals are deposited from the molten glass G and the transparency is lowered. Devitrification occurs in places where the flow of molten glass G is stagnant.

The pair of specific compartments A2 and A4 are arranged with the compartment A3 interposed therebetween. Immediately below the compartment A3, only the central portion in the width direction of the glass ribbon GR, that is, the portion where the temperature of the glass ribbon GR is high passes. Therefore, unlike the compartments A2 and A4, the compartment A3 is collectively controlled by one controller 60 without being divided into a plurality of sub-compartments in the flow direction of the glass ribbon GR.

When heating the glass ribbon GR, the output of the heater 50 per unit area of the compartment A3 is controlled to be smaller than the output of the heater 50 per unit area of the two sub-compartments A2-1 and A4-1 on the upstream side. It is preferably controlled to 0 kW / m ² or more and 1 kW / m ² or less, and more preferably 0 kW / m ² or more and 0.5 kW / m ² or less. In addition, although one section A3 is arranged between the section A2 and the section A4 in this embodiment, a plurality of sections may be arranged.

The distance W1 between the pair of specific compartments A2 and A4 is preferably 60% or more of the width W2 between the downstream ends of the pair of restrictor tiles 24 and 25. When the interval W1 is 60% or more of the width W2, the temperature of the central portion in the width direction of the glass ribbon GR (the portion where the temperature of the glass ribbon GR is high) is controlled by controlling the output of the heater 50 per unit area of the compartment A3 to be small. In the hot region X1, the temperature distribution and the plate thickness distribution in the width direction of the glass ribbon GR can be efficiently made uniform. W1 is more preferably 65% or more of W2. Further, W1 is preferably 75% or less, more preferably 70% or less of W2.

As shown in FIG. 1, the bathtub 10 has a deep bottom region X3 in which the depth of the molten metal M is constant and a shallow bottom region X3 in which the depth is shallower and constant than the deep bottom region X3 from upstream to downstream. It has X4 in this order.

The deep bottom region X3 is arranged upstream of the molding region X2. In the deep bottom region X3, the depth of the molten metal M is deep and the amount of the molten metal M is large. Therefore, the heat brought into the bath 10 of the molten glass G and the glass ribbon GR can be quickly absorbed by the molten metal M, and the temperature of the glass ribbon GR can be rapidly cooled to a temperature suitable for molding.

Further, in the deep bottom region X3, as shown in FIG. 5, convection of the molten metal M can be formed. At the center of the bathtub 10 in the width direction, the temperatures of the molten glass G and the glass ribbon GR are high, and a large amount of heat is absorbed by the molten metal M. As a result, the molten metal M is heated and becomes lighter, so that an ascending flow of the molten metal M is formed. On the other hand, at both ends in the width direction of the bathtub 10, the molten metal M is cooled and becomes heavy, so that a downward flow of the molten metal M is formed. Further, in the deep bottom region X3, since the glass ribbon GR spreads from the center in the width direction to both ends in the width direction, a downward flow and an upward flow of the molten metal M as shown in FIG. 5 are formed.

By the convection of the molten metal M, the temperature distribution in the width direction of the molten metal M can be made uniform, and by extension, the temperature distribution in the width direction of the glass ribbon GR can be made uniform. The deeper the molten metal M is, the more likely it is that an ascending flow and a descending flow are formed, and the stronger the flow becomes.

On the other hand, in the shallow bottom region X4, the depth of the molten metal M is shallow and the amount of the molten metal M is small. Therefore, the amount of molten metal M used can be reduced. As shown in FIG. 1, the shallow bottom region X4 is formed over the entire area from the upstream end to the downstream end of the molding region X2, and extends to the upstream side of the molding region X2. The upstream end of the shallow bottom region X4 is arranged in the hot region X1.

The length L1 in the X-axis direction of the portion overlapping the deep bottom region X3 of the hot region X1 is preferably 35% or more of the length L0 in the X-axis direction of the hot region X1. Conventionally, L1 is about 20% of L0. According to the present embodiment, since L1 is 35% or more of L0, convection of the molten metal M shown in FIG. 5 can be formed in a relatively wide range of the hot region X1. L1 is more preferably 30% or more of L0.

As shown in FIG. 1, it is preferable that the boundary line D3 of the two sub-compartments A2-1 and A2-2 is arranged directly above the deep bottom region X3. Similarly, it is preferable that the boundary line between the two sub-compartments A4-1 and A4-2 is also arranged directly above the deep bottom region X3. Convection of the molten metal M shown in FIG. 5 can be formed not only directly under the sub-compartments A2-1 and A4-1 on the upstream side but also directly under the sub-compartments A2-2 and A4-2 on the downstream side.

As shown in FIG. 3, in a plan view, the side wall of the bottom casing 11 extends outward in the width direction of the glass ribbon GR from the vicinity of the downstream ends of the restrictor tiles 24 and 25, and subsequently in the flow direction of the glass ribbon GR. It extends downstream and forms a right-angled corner CR. It is preferable that the side bricks 12 are provided in a triangular shape inside each corner CR.

In a plan view, the width of the glass ribbon GR is wider than the case where the side wall of the bottom casing 11 forms a diagonal corner instead of a right-angled corner CR and the side brick 12 is provided inside the corner in a diagonal straight line. The distance from the direction end to the side wall of the bottom casing 11 can be secured. Therefore, it is possible to suppress the heat of the widthwise end portion of the glass ribbon GR from flowing out to the outside in the width direction, and it is possible to suppress the temperature drop at the widthwise end portion of the glass ribbon GR.

Next, the float glass manufacturing apparatus 1 according to the modified example will be described with reference to FIG. As shown in FIG. 6, the float glass manufacturing apparatus 1 may include a cooling pipe 70. The cooling pipe 70 cools the central portion of the glass ribbon GR in the width direction from above in the hot region X1. As described above, the hot region X1 is a region from the downstream end of the pair of restrictor tiles 24 and 25 to the pair of top rolls 30 in the uppermost stream. The width of the central portion in the width direction of the glass ribbon GR is, for example, 40% of the total width of the glass ribbon GR.

In the hot region X1, the central portion in the width direction of the glass ribbon GR has a higher temperature and a thicker plate than the end portion in the width direction of the glass ribbon GR. If the central portion of the glass ribbon GR in the width direction is cooled by the cooling pipe 70, the temperature difference can be reduced, and thus the plate thickness deviation can be reduced. The cooling pipe 70 may cool the central portion of the glass ribbon GR in the width direction, and may also cool other portions. The cooling tube 70 may cool the glass ribbon GR so that the temperature difference in the width direction of the glass ribbon GR becomes small.

The cooling pipe 70 is arranged horizontally, for example, along the width direction of the glass ribbon GR. One cooling pipe 70 is inserted from each of the pair of side walls orthogonal to the Y-axis direction, and the cooling pipe 70 is installed on the side brick 12. The cooling pipe 70 may be continuously bridged from one side wall to the other side wall. Further, the cooling pipe 70 may be suspended from the ceiling 27 in the same manner as the heater 50.

As shown in FIG. 8, the cooling pipe 70 has a flow path 71 through which the refrigerant flows. The refrigerant is a liquid such as water. The refrigerant may be a gas such as air. The flow path 71 may separately include the outward path 72 and the return path 73. The refrigerant flows through the outward path 72 from the outside in the width direction of the glass ribbon GR to the inside, and then flows through the return path 73 from the inside to the outside in the width direction of the glass ribbon GR. The cooling efficiency can be improved by providing the outward path 72 and the return path 73 separately and adjusting the flow of the refrigerant. The cooling pipe 70 is a square pipe in FIG. 8, but may be a circular pipe.

The cooling pipe 70 selectively cools the central portion of the glass ribbon GR in the width direction with respect to the end portion in the width direction of the glass ribbon GR. However, the widthwise end of the glass ribbon GR is also cooled by the cooling pipe 70. Therefore, the controller 60 may increase the output of the heaters 50 provided in the compartments A1 and A5 in order to heat the widthwise end portion of the glass ribbon GR from the outside in the widthwise direction. Further, the controller 60 may increase the output of the heaters 50 provided in the compartments A2 and A4.

As shown in FIGS. 7 to 8, the float glass manufacturing apparatus 1 may include a heat insulating material 75 that covers the cooling pipe 70. The heat transfer coefficient of the heat insulating material 75 is, for example, 0.05 W / (m ² · K) to 1 W / (m ² · K), preferably 0.3 W / (m ² · K) to 0.7 W / (m 2 · K). m ² · K). The material of the heat insulating material 75 is determined so that foreign matter does not fall on the upper surface of the glass ribbon GR.

The thinner the thickness T of the heat insulating material 75, the easier it is for the refrigerant to absorb heat and the easier it is for the glass ribbon GR to be cooled. Therefore, as shown in FIG. 7, the thickness T of the heat insulating material 75 may be thinner from the outside to the inside in the width direction of the glass ribbon GR. Thereby, the central portion in the width direction of the glass ribbon GR can be selectively cooled with respect to the end portion in the width direction of the glass ribbon GR.

In FIG. 7, the entire Y-axis direction of the cooling pipe 70 is covered with the heat insulating material 75, but the entire Y-axis direction of the cooling pipe 70 may not be covered with the heat insulating material 75. For example, the thickness T of the heat insulating material 75 may be zero at the tip of the cooling pipe 70. The thickness T of the heat insulating material 75 may be thinner from the outside to the inside in the width direction of the glass ribbon GR. The thickness T of the heat insulating material 75 changes stepwise in FIG. 7, but may change continuously.

In the following experiment, the same except that the output of the heater per unit area of the sub-compartments A2-1, A2-2, A4-1, A4-2 and the compartment A3 shown in FIG. 4 was controlled to the values shown in Table 1. The glass ribbon GR was formed under the conditions and slowly cooled, and then both ends of the glass ribbon GR in the width direction were excised to obtain float glass. W1 was 71% of W2. Further, L1 was 35% of L0.

The float glass was divided into 6 equal parts in the width direction of the glass ribbon GR and divided into 6 test pieces. The plate thickness in the width direction of each test piece was measured, and the plate thickness deviation was calculated. The sum of the plate thickness deviations of the six test pieces is the sum of the plate thickness deviations of the six sites. The sum of the plate thickness deviations of the six sites means that the smaller the value, the smaller the plate thickness distribution in the width direction of the glass ribbon GR. Table 1 shows the test results. In Table 1, the total of the plate thickness deviations of the six sites is the average value of the float glass produced in one month.

表１において、例１が実施例、例２が比較例である。表１から明らかなように、上流側のサブ区画Ａ２－１、Ａ４－１と、下流側のサブ区画Ａ２－２、Ａ４－２とで、単位面積当たりのヒータの出力を独立に制御すれば、６部位の板厚偏差の合計を低減できることが分かる。つまり、幅が広く且つ板厚偏差が小さいガラスリボンが得られることが分かる。

In Table 1, Example 1 is an example and Example 2 is a comparative example. As is clear from Table 1, if the output of the heater per unit area is independently controlled in the upstream sub-compartments A2-1 and A4-1 and the downstream sub-compartments A2-2 and A4-2. , It can be seen that the total plate thickness deviation of 6 parts can be reduced. That is, it can be seen that a glass ribbon having a wide width and a small plate thickness deviation can be obtained.

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-described embodiment and the like. Various changes, modifications, replacements, additions, deletions, and combinations are possible within the scope of the claims. Of course, they also belong to the technical scope of the present disclosure.

10 Bath 14 Spout trip 24, 25 Restrictor tile 27 Ceiling 30 Top roll 50 Heater M Molten metal G Molten glass GR Glass ribbon

Claims (12)

A bathtub for accommodating the molten metal, a spout trip for continuously supplying the molten glass on the molten metal, and a flow width of the molten glass supplied on the molten metal from the upstream side to the downstream side. A pair of restrictor tiles to be unfolded, a plurality of top rolls for pressing the widthwise ends of the strip-shaped glass ribbon downstream of the pair of restrictor tiles, a ceiling provided above the glass ribbon, and the above. A float glass manufacturing apparatus comprising a plurality of heaters suspended from the ceiling and a plurality of controllers for controlling the plurality of heaters.
The ceiling is divided into a plurality of rows in the flow direction of the glass ribbon, and each of the rows is divided in the width direction of the glass ribbon, and each section is selected for each section except for a specific section. A plurality of the heaters, which are collectively controlled by one of the controllers, are provided.
The particular compartment is the compartment directly above the downstream end of each restrictor tile.
Float glass manufacturing is provided in each sub-compartment formed by dividing the specific section in the flow direction into a plurality of the heaters collectively controlled by one controller selected for each sub-compartment. Device. The specific compartments are arranged in pairs at intervals in the width direction.
The float glass manufacturing apparatus according to claim 1, wherein the compartments collectively controlled by one controller are arranged between the pair of the specific compartments. The float glass manufacturing apparatus according to claim 2, wherein the distance between the pair of the specific compartments is 60% or more of the width between the downstream ends of the pair of restrictor tiles. The bathtub has a hot region from the downstream end of the pair of restrictor tiles to the pair of upstream top rolls and a molding region downstream of the pair of upstream top rolls.
The float glass manufacturing apparatus according to any one of claims 1 to 3, wherein each of the sub-sections is arranged directly above the hot region. From upstream to downstream, the bathtub has a deep bottom region where the depth of the molten metal is constant and a shallow bottom region where the depth is shallower and constant than the deep bottom region. death,
The float glass manufacturing apparatus according to claim 4, wherein the length of the portion of the hot region overlapping the deep bottom region in the flow direction is 35% or more of the length of the hot region in the flow direction. The float glass manufacturing apparatus according to claim 5, wherein the boundary line between the two subsections adjacent to each other in the flow direction is arranged directly above the deep bottom region. The bathtub includes a box-shaped bottom casing opened upward, a plurality of bottom bricks that protect the bottom wall of the bottom casing from the molten metal, and a plurality of side bricks provided inside the side wall of the bottom casing. , Has,
In plan view, the sidewalls of the bottom casing form right-angled corners extending outward in the width direction from near the downstream end of each restrictor tile and subsequently extending downstream in the flow direction. The float glass manufacturing apparatus according to any one of claims 1 to 6, wherein the side bricks are provided in a triangular shape inside the corner. Claims 1 to 7 include cooling tubes for cooling the widthwise central portion of the glass ribbon from above in a hot region from the downstream end of the pair of restrictor tiles to the pair of top rolls in the uppermost stream. The float glass manufacturing apparatus according to any one of the above items. A heat insulating material that covers the cooling pipe is provided.
The cooling tube is arranged horizontally along the width direction of the glass ribbon.
The float glass manufacturing apparatus according to claim 8, wherein the thickness of the heat insulating material becomes thinner from the outside in the width direction to the inside in the width direction of the glass ribbon. A float glass manufacturing method using the float glass manufacturing apparatus according to any one of claims 1 to 9.
The molten glass flowing over the spout trip is continuously supplied onto the molten metal in the bathtub.
By flowing the molten glass on the molten metal and forming it into a strip-shaped glass ribbon,
Using the heater to heat the glass ribbon passing under the heater,
Float glass manufacturing method having. When heating the glass ribbon, the output of the heater per unit area of the sub-compartment on the upstream side is 3 kW / m ² or more, and the output of the heater per unit area of the sub-compartment on the downstream side is The float glass manufacturing method according to claim 10, wherein the float glass is 1 kW / m ² or less. The specific compartments are arranged in pairs at intervals in the width direction.
11. The float according to claim 11, wherein when the glass ribbon is heated, the output of the heater per unit area of the compartments arranged between the pair of the particular compartments is 1 kW / m ² or less. Glass manufacturing method.

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