Float glass manufacturing device and float glass manufacturing method

Abstract

The invention relates to a float glass manufacturing apparatus and a float glass manufacturing method. This float glass production device is a float glass production device for forming molten glass supplied onto a molten metal into a glass ribbon on the molten metal, and is provided with: a float bath furnace for storing the molten metal; and a cleaning member having a rod-shaped shaft portion and a contact portion provided at the tip of the shaft portion, the float bath comprising: a bottom wall portion extending in a direction orthogonal to the vertical direction; and a side wall part which extends from the peripheral edge of the bottom wall part to the upper side in the vertical direction and is provided with an opening part through which the shaft part passes, and the cleaning member is capable of moving along the bottom surface of the bottom wall part facing the upper side in the vertical direction in a state in which the contact part is in contact with the bottom surface.

Description

Technical Field

[0001] Embodiments of the present invention relate to a float glass manufacturing apparatus and a float glass manufacturing method.

[0002] This application claims priority based on Japanese Patent Application No. 2023-96880 filed in Japan on June 13, 2023, and its contents are cited herein. Background Art

[0003] The production of sheet glass formed by the float process is generally carried out in the following order. First, the molten glass obtained by heating and melting glass raw materials is continuously supplied to the surface of molten metal such as molten tin stored in a float furnace. Then, the molten glass is transferred along the surface of the molten metal and formed into a glass ribbon. Then, the formed glass ribbon is pulled out of the float furnace, annealed and cleaned, and then cut to obtain sheet glass of the desired size.

[0004] The production method of sheet glass formed by the float process has high productivity and the obtained sheet glass has excellent flatness. Therefore, sheet glass produced by the float process is widely used as sheet glass for buildings, sheet glass for automobiles, sheet glass for FPD (flat panel display), etc.

[0005] Patent Document 1 discloses a float glass production apparatus including a float glass kiln having a bath-like structure in which a plurality of brick bottom bricks are arranged in a row inside a metal bottom shell.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-124123 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In a float kiln having the above-mentioned structure, precipitates from bricks that are dissolved and precipitated from bricks exposed to high temperatures by molten metal adhere to the bricks. When the precipitates are peeled off from the bricks and float toward the surface of the molten metal, they sometimes adhere to the molten glass and glass ribbon that are transferred on the molten metal. As a result, defects such as depressions and protrusions are generated on the surface of the glass ribbon, and thus the adhesion of the precipitates to the molten glass and glass ribbon becomes a major cause of a decrease in the yield of plate glass.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a float glass manufacturing apparatus and a float glass manufacturing method capable of suppressing adhesion of precipitates to molten glass and a glass ribbon conveyed on a molten metal.

[0012] Technical solutions to solve problems

[0013] The present invention has the following aspects.

[0014] [1] A float glass manufacturing device that forms molten glass supplied to a molten metal into a glass ribbon on the molten metal, wherein the device comprises: a float kiln that stores the molten metal; and a cleaning member having a rod-shaped shaft and a contact portion provided at the front end of the shaft, the float kiln having: a bottom wall portion that extends in a direction perpendicular to the vertical direction; and a side wall portion that extends from the periphery of the bottom wall portion toward the upper side in the vertical direction and is provided with an opening portion for the shaft portion to pass through, the cleaning member being able to move along the bottom surface of the bottom wall portion in a state where the contact portion is in contact with the bottom surface of the bottom wall portion facing the upper side in the vertical direction.

[0015] [2] The float glass manufacturing apparatus according to [1], wherein the contact portion is capable of contacting a portion of the bottom surface that overlaps with the molten glass or the glass ribbon when viewed in a vertical direction.

[0016] [3] The float glass manufacturing apparatus according to [1] or [2], wherein a portion of the bottom wall portion having the bottom surface is made of brick, the shaft portion is made of metal, and the contact portion is made of a material containing carbon fibers.

[0017] [4] The float glass manufacturing apparatus according to any one of [1] to [3], wherein the float glass manufacturing apparatus includes a vibration excitation device for applying vibration to at least the bottom wall portion of the float glass furnace.

[0018] [5] A method for manufacturing float glass, forming a glass ribbon using a float glass manufacturing device, wherein the float glass manufacturing device includes a float kiln, which stores molten metal and has a bottom wall portion extending in a direction perpendicular to the vertical direction and a side wall portion extending from the periphery of the bottom wall portion toward the upper side in the vertical direction and having an opening, wherein the float glass manufacturing method includes the following steps: transferring and forming the molten glass supplied to the molten metal into the glass ribbon; and using a cleaning member to clean the bottom surface of the bottom wall portion toward the upper side in the vertical direction, the cleaning member having: a rod-shaped shaft portion passing through the opening portion; and a contact portion provided at the front end of the shaft portion, wherein the step of cleaning the bottom surface includes: moving the cleaning member along the bottom surface to clean the bottom surface while the contact portion is in contact with the bottom surface.

[0019] [6] The float glass manufacturing method according to [5], wherein the step of cleaning the bottom surface includes: moving the molten glass supplied onto the molten metal, and cleaning the bottom surface using the contact portion.

[0020] [7] The float glass manufacturing method according to [5] or [6], wherein the float glass manufacturing method includes a step of applying vibration to the bottom wall portion using a vibration excitation device capable of applying vibration to the float glass furnace to clean the bottom surface.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a float glass manufacturing apparatus and a float glass manufacturing method capable of suppressing adhesion of precipitates to molten glass and a glass ribbon conveyed on a molten metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional view showing an example of the float glass manufacturing apparatus according to the first embodiment of the present invention.

[0024] Figure 2 This is a cross-sectional view showing an example of a state of molten glass transferred on a molten metal according to the first embodiment of the present invention.

[0025] Figure 3 is a cross-sectional view showing an example of a float glass manufacturing apparatus according to a first embodiment of the present invention, and is Figure 1 III-III sectional view.

[0026] Figure 4 It is a perspective view showing an example of the cleaning member according to the first embodiment of the present invention.

[0027] Figure 5 This is a flowchart showing the float glass manufacturing method according to the first embodiment of the present invention.

[0028] Figure 6 This is a diagram showing an example of transition of the number of defects in the sheet glass according to the first embodiment of the present invention.

[0029] Figure 7 It is a cross-sectional view showing an example of a float glass manufacturing apparatus according to a second embodiment of the present invention.

[0030] Figure 8 It is a flowchart which shows the float glass manufacturing method which concerns on 2nd Embodiment of this invention. DETAILED DESCRIPTION

[0031] The float glass manufacturing apparatus of the present invention forms a glass ribbon by float forming. Hereinafter, an example of the float glass manufacturing apparatus of the present invention will be described with reference to the accompanying drawings. In addition, the dimensions and the like of the drawings illustrated in the following description are examples, and the present invention is not necessarily limited thereto, and can be implemented by appropriately changing within the scope of not changing the gist thereof.

[0032] In each of the accompanying drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. The Z-axis direction is the vertical direction. In the following description, the side (+Z side) to which the arrow of the Z-axis is directed is referred to as the "upper side" or "upper side in the vertical direction", and the opposite side (-Z side) to which the arrow of the Z-axis is directed is referred to as the "lower side". The X-axis direction is a direction orthogonal to the Z-axis direction, and in the following embodiments, it is the direction in which the molten glass and the glass ribbon are transferred. In the following embodiments, the molten glass and the glass ribbon are transferred in the direction to which the arrow of the X-axis is directed. In the following description, the X-axis direction is referred to as the "transfer direction", the side (+X side) to which the arrow of the X-axis is directed is referred to as the "downstream side", and the opposite side (-X side) to which the arrow of the X-axis is directed is referred to as the "upstream side". The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction, and is the width direction of the float glass manufacturing device. In the following description, the Y-axis direction is referred to as the “width direction”, the side to which the Y-axis arrow is pointing (+Y side) is referred to as the “one side of the width direction”, and the side opposite to the side to which the Y-axis arrow is pointing (-Y side) is referred to as the “other side of the width direction”.

[0033] <First Embodiment>

[0034] Hereinafter, the float glass manufacturing apparatus 10 and the float glass manufacturing method Mg according to the first embodiment will be described with reference to the drawings.

[0035] like Figure 1 As shown, the float glass manufacturing apparatus 10 of the present embodiment is an apparatus for transferring molten glass G supplied to the molten metal 28 stored in the float furnace 20 along the surface of the molten metal 28 and utilizing Figure 2 The upper roller 61 shown in the figure expands from both sides in the width direction (Y-axis direction) to form a glass ribbon GR in a strip shape on the molten metal 28. Figure 1 As shown in FIG. 1 , the float glass manufacturing apparatus 10 includes a float glass furnace 20, a molten metal 28, a top 30, a lifting roller 41, and a conveying roller 42. Figure 2 As shown in FIG. 1 , the float glass manufacturing apparatus 10 includes an upper roller 61. Figure 3 As shown, the float glass manufacturing apparatus 10 includes a cleaning member 50 .

[0036] A melting furnace (not shown) is arranged on the upstream side (-X side) of the float furnace 20 to heat and melt the glass material to generate molten glass G. The molten glass G is supplied from the melting furnace to the molten metal 28 stored in the float furnace 20. In the float furnace 20, the molten glass G is transferred toward the downstream side (+X side) on the molten metal 28, and as shown in FIG. Figure 2As shown in FIG. 1 , tension is applied by upper rollers 61 disposed on both sides of the molten glass G in the width direction, and the molten glass G is adjusted to a desired width and thickness. Thus, a glass ribbon GR in a strip shape adjusted to a desired width and thickness is formed. Figure 1 As shown, the glass ribbon GR is lifted from the float kiln 20 by a lifting roller 41 disposed on the downstream side of the float kiln 20, and is conveyed to an annealing furnace (not shown) by a conveying roller 42 for annealing. Then, the glass ribbon GR annealed in the annealing furnace is cleaned and then cut into a predetermined size by a cutting device (not shown) to obtain a plate glass of a predetermined size.

[0037] On the upstream side (-X side) of the float furnace 20, the inlet 16a is formed by the molten metal 28 and the top 30. The molten glass G transported from the melting furnace (not shown) to the downstream side (+X side) via the supply passage 12 is supplied to the molten metal 28 via the lip 13 provided at the downstream end of the supply passage 12, and is transferred to the downstream side on the molten metal 28 via the inlet 16a. A gate 14 for regulating the flow of the molten glass G is arranged on the supply passage 12 on the upstream side of the lip 13. In addition, the temperature of the molten glass G supplied to the molten metal 28 is a temperature higher than the softening point of the molten glass G. For example, when the molten glass G is soda-lime glass, the softening point of the molten glass G is about 750°C.

[0038] On the downstream side (+X side) of the float furnace 20, the float furnace 20 and the ceiling 30 form an exit 16b. The glass ribbon GR formed into a predetermined width and thickness by the upper roller 61 as described above is lifted up from the float furnace 20 by the lifting roller 41 through the exit 16b.

[0039] The float kiln 20 stores molten metal 28. In this embodiment, the molten metal 28 is molten tin. Figure 1 and Figure 2 As shown in FIG. 1 , the float kiln 20 is a substantially rectangular container with its long sides extending in the conveying direction (X-axis direction). The float kiln 20 is open on the upper side (+Z side). Figure 1 As shown, the float kiln 20 has a bottom wall 20a and a side wall 20b. The bottom wall 20a extends in a direction perpendicular to the vertical direction (Z-axis direction). When viewed from the vertical direction, the bottom wall 20a is a substantially rectangular shape with the long side extending in the transfer direction. The bottom wall 20a is the bottom of the float kiln 20.

[0040] The side wall portion 20b extends from the peripheral edge of the bottom wall portion 20a toward the upper side (+Z side), that is, toward the upper side in the vertical direction. Figure 2 As shown in FIG. 1 , when viewed from the vertical direction (Z-axis direction), the side wall portion 20b is substantially in the shape of a square frame. The side wall portion 20b includes an upstream wall portion 20e, a downstream wall portion 20f, a first wall portion 20g, a second wall portion 20h, and an opening 25. Figure 1As shown, the upstream wall portion 20e is a plate-shaped portion extending upward from the edge of the upstream side (-X side) of the bottom wall portion 20a. When viewed from the transfer direction (X-axis direction), the upstream wall portion 20e is substantially rectangular. The upstream wall portion 20e is located on the upstream side of the lip portion 13. The downstream wall portion 20f extends upward from the edge of the downstream side (+X side) of the bottom wall portion 20a. When viewed from the transfer direction, the downstream wall portion 20f is substantially rectangular.

[0041] like Figure 3 As shown, the first wall portion 20g extends from the edge of one side (+Y side) of the width direction of the bottom wall portion 20a to the upper side (+Z side). The second wall portion 20h extends from the edge of the other side (-Y side) of the width direction of the bottom wall portion 20a to the upper side. Observed from the width direction (Y-axis direction), the first wall portion 20g and the second wall portion 20h are roughly rectangular. The opening 25 is an opening provided between the first wall portion 20g and the second wall portion 20h and the top 30 respectively. The opening 25 extends along the transfer direction (X-axis direction). The opening 25 connects the internal space of the float tank 20 and the top 30 respectively with the space outside the float glass manufacturing device 10.

[0042] like Figure 1 As shown, the float kiln 20 has a shell 21 and a plurality of brick components 22. Figure 1 and Figure 3 As shown, the housing 21 is a substantially rectangular container with its long sides extending in the transfer direction (X-axis direction). The housing 21 is open on the upper side (+Z side). In this embodiment, the housing 21 is made of metal. The material constituting the housing 21 is not particularly limited, and metal materials such as iron and stainless steel can be used. Figure 1 As shown, the housing 21 has a housing bottom wall portion 21 a and a housing side wall portion 21 b.

[0043] The housing bottom wall 21a is in the shape of a plate extending in a direction perpendicular to the vertical direction (Z-axis direction). When viewed from the vertical direction, the housing bottom wall 21a is in the shape of a substantially rectangular shape with the long sides extending in the transfer direction. The housing side wall 21b extends upward (+Z side) from the peripheral edge of the housing bottom wall 21a. When viewed from the vertical direction, the housing side wall 21b is in the shape of a substantially rectangular frame.

[0044] A plurality of brick components 22 are arranged inside the housing 21. In the present embodiment, each brick component 22 is roughly rectangular. Each brick component 22 is made of bricks. The material constituting each brick component 22 is preferably a material that is not easy to react with molten tin as the molten metal 28 and has high temperature and moisture resistance, for example, alumina, sillimanite, clay and the like can be used. The plurality of brick components 22 include a plurality of bottom wall bricks 22a and a plurality of side wall bricks 22b.

[0045] like Figure 1and Figure 3 As shown, a plurality of bottom wall bricks 22a are arranged on the bottom wall portion 21a of the shell. The bottom wall bricks 22a are arranged in a row in the conveying direction (X-axis direction) and the width direction (Y-axis direction). The bottom wall bricks 22a arranged adjacent to each other in the conveying direction and the width direction are in contact with each other. The surface of each bottom wall brick 22a facing the upper side (+Z side) constitutes the bottom surface 20c which is the surface facing the upper side of the bottom wall portion 20a, that is, facing the upper side in the vertical direction. Therefore, in the present embodiment, the portion of the bottom wall portion 20a having the bottom surface 20c is made of bricks.

[0046] A plurality of side wall bricks 22b are arranged on the bottom wall portion 21a of the housing along the inner side surface of the side wall portion 21b of the housing. The side wall bricks 22b arranged adjacent to each other in the transfer direction (X-axis direction) and the width direction (Y-axis direction) are in contact with each other. The dimension of each side wall brick 22b in the vertical direction (Z-axis direction) is larger than the dimension of each bottom wall brick 22a in the vertical direction.

[0047] like Figure 1 and Figure 3 As shown, the top 30 is a roughly rectangular box-shaped body with long sides extending in the conveying direction (X-axis direction). The top 30 is open on the lower side (-Z side). The top 30 is arranged on the upper side (+Z side) of the float kiln 20. Thus, the upper space of the float kiln 20 is surrounded by the top 30. The interior of the top 30 is filled with a reducing atmosphere such as a nitrogen atmosphere containing about 12% or less hydrogen. Thus, the upper space of the molten metal 28 is isolated from the external atmosphere as much as possible. The top 30 is arranged at a distance from the float kiln 20 in the vertical direction (Z-axis direction). A plurality of heaters not shown in the figure are arranged inside the top 30. The plurality of heaters adjust the temperature inside the top 30. In addition, heaters may not be provided. As Figure 1 As shown, the top portion 30 has a top wall portion 31, an upstream protruding wall 32 and a downstream protruding wall 33. Figure 3 As shown, the top portion 30 has a first protruding wall 34a and a second protruding wall 34b.

[0048] like Figure 1As shown, the top wall portion 31 is a plate-shaped portion extending in a direction orthogonal to the vertical direction (Z-axis direction). Although not shown in the figure, when viewed from the vertical direction, the top wall portion 31 is a roughly rectangular portion with a long side extending in the transfer direction (X-axis direction). When viewed from the vertical direction, the top wall portion 31 overlaps with the bottom wall portion 20a. The end of the upstream side (-X side) of the top wall portion 31 is located on the downstream side (+X side) than the end of the upstream side of the float kiln 20. The upstream protruding wall 32 is a plate-shaped portion protruding from the edge of the upstream side of the top wall portion 31 to the lower side (-Z side). When viewed from the transfer direction, the upstream protruding wall 32 is roughly rectangular. The upstream protruding wall 32 is arranged on the downstream side than the upstream wall portion 20e. The upstream protruding wall 32 is arranged at a distance from the molten metal 28 in the vertical direction. Therefore, the inlet portion 16a is arranged between the upstream protruding wall 32 and the surface of the molten metal 28.

[0049] The downstream protruding wall 33 is a plate-shaped protrusion from the edge of the downstream side (+X side) of the top wall 31 toward the lower side (-Z side). When viewed from the transfer direction (X-axis direction), the downstream protruding wall 33 is substantially rectangular. The downstream protruding wall 33 is spaced apart from the downstream wall 20f of the float kiln 20 in the vertical direction (Z-axis direction). Thus, the outlet 16b is provided between the downstream protruding wall 33 and the downstream wall 20f.

[0050] like Figure 3 As shown, the first protruding wall 34a is a plate-shaped protruding from the edge of one side (+Y side) of the width direction of the top wall portion 31 to the lower side (-Z side). The second protruding wall 34b is a plate-shaped protruding from the edge of the other side (-Y side) of the width direction of the top wall portion 31 to the lower side. When viewed from the width direction (Y-axis direction), the first protruding wall 34a and the second protruding wall 34b are roughly rectangular. The first protruding wall 34a and the second protruding wall 34b are each spaced apart from the first wall portion 20g and the second wall portion 20h of the float kiln 20 in the vertical direction (Z-axis direction). Thus, an opening 25 is provided in the side wall portion 20b.

[0051] In addition, as long as the internal space of each of the float glass kiln 20 and the top 30 is connected to the external space of the float glass manufacturing device 10, the structure of the opening 25 is not limited to the present embodiment. For example, when the first protruding wall 34a and the second protruding wall 34b are in contact with the first wall 20g and the second wall 20h of the float glass kiln 20 in the vertical direction (Z-axis direction), the opening 25 may be a hole that penetrates the first wall 20g and the second wall 20h in the width direction (Y-axis direction), or a hole that penetrates one of the first wall 20g and the second wall 20h in the width direction. In this case, a plurality of openings 25 may be provided along the transfer direction (X-axis direction).

[0052] The cleaning member 50 is a member for cleaning the bottom surface 20c of the floating kiln 20. Figure 4 As shown, the cleaning member 50 has a shaft 51, a connecting portion 52 and a contact portion 53. The shaft 51 is a rod extending in a straight line. In the present embodiment, the shaft 51 is a cylindrical rod. The shaft 51 may also be a rod of other shapes such as a prism. In the present embodiment, the shaft 51 is made of metal. The material constituting the shaft 51 is preferably a material having high heat resistance, such as iron and stainless steel. Figure 3 As shown, the diameter of the shaft portion 51 is smaller than the dimension of the opening portion 25 in the vertical direction (Z-axis direction). Thus, the shaft portion 51 can pass through the opening portion 25. The shaft portion 51 can move in the width direction (Y-axis direction) and the transfer direction (X-axis direction) inside the opening portion 25. In addition, the cleaning member 50 can be installed in the floating kiln 20 in a manner that it can move relative to the floating kiln 20, and can also be loaded and unloaded relative to the floating kiln 20.

[0053] like Figure 4 As shown, the connecting portion 52 connects the shaft portion 51 and the contact portion 53. The connecting portion 52 is connected to the front end 51a of the shaft portion 51. In the present embodiment, the connecting portion 52 is substantially rectangular. In the present embodiment, the connecting portion 52 is made of metal. The material constituting the connecting portion 52 is preferably a material with high heat resistance, for example, iron and stainless steel can be used.

[0054] The contact portion 53 is a portion of the cleaning bottom surface 20c in the cleaning member 50. The contact portion 53 is connected to the connecting portion 52. Thus, the contact portion 53 is provided at the front end 51a of the shaft portion 51 via the connecting portion 52. In the present embodiment, the connecting portion 52 is substantially rectangular. In the present embodiment, the contact portion 53 is formed of a material containing carbon fibers. The contact portion 53 can be formed of, for example, a resin, ceramic and metal containing carbon fibers, a carbon extruded material, a carbon CIP material, and the like. Thus, compared with the case where the contact portion 53 is made of metal, the heat resistance of the contact portion 53 can be improved, and the hardness of the contact portion 53 can be made smaller than the hardness of the brick member 22.

[0055] like Figure 3As shown in the figure, when the shaft 51 is passed through the opening 25, the contact portion 53 can contact the bottom surface 20c of the float kiln 20. In addition, if the shaft 51 is moved in the transfer direction (X-axis direction) and the width direction (Y-axis direction) while the shaft 51 is passed through the opening 25, the contact portion 53 can be moved along the bottom surface 20c while the contact portion 53 is in contact with the bottom surface 20c. Thus, the precipitate P described later attached to the bottom surface 20c can be removed by the contact portion 53. That is, the bottom surface 20c can be cleaned by the cleaning member 50. In addition, in the present embodiment, the contact portion 53 can contact the portion of the bottom surface 20c that overlaps with the molten glass G or the glass ribbon GR when viewed from the vertical direction (Z-axis direction). Thus, the cleaning member 50 can clean the portion of the bottom surface 20c that overlaps with the molten glass G or the glass ribbon GR when viewed from the vertical direction.

[0056] Next, a float glass manufacturing method Mg for forming a glass ribbon GR using the float glass manufacturing apparatus 10 of the present embodiment will be described. Figure 5 As shown, the float glass manufacturing method Mg of the present embodiment includes: a forming step S01, transferring and forming the molten glass G supplied to the molten metal 28 into a glass ribbon GR; an inspection step S02, inspecting the plate glass; a first cleaning step S04, cleaning the bottom surface 20c of the float kiln 20 using the contact portion 53 of the cleaning member 50; and a recovery step S05, recovering the precipitate P removed from the bottom surface 20c from the molten metal 28. In the following description, the so-called "operator, etc." includes operators and devices, etc. who perform operations in each step. The operations in each step may be performed only by the operator, only by the device, etc., or by the operator and the device, etc.

[0057] The forming step S01 is a step of transferring and forming the molten glass G supplied to the molten metal 28 into a glass ribbon GR. Figure 1 As shown in FIG. 1 , the operator supplies the molten glass G onto the molten metal 28 stored in the float furnace 20. Figure 2 As shown, the operator transfers the molten glass G on the molten metal 28 toward the downstream side (+X side), and adjusts the molten glass G to a desired width and thickness using the upper roller 61, thereby forming a plate-shaped glass ribbon GR adjusted to the desired width and thickness. After that, as described above, the glass ribbon GR is lifted from the float furnace 20, and the glass ribbon GR cooled in the annealing furnace (not shown) is cut into a predetermined size by a cutting device (not shown), thereby obtaining a plate-shaped glass of a predetermined size.

[0058] The inspection step S02 is a step of inspecting the presence or absence of defects and the number of defects in the plate-shaped glass obtained in the forming step S01. The operator may perform this inspection on all the plate-shaped glasses, or may perform this inspection on a predetermined number of plate-shaped glasses at predetermined intervals, such as inspecting one plate-shaped glass every day. Defects in the plate-shaped glass are caused, for example, by the adhesion of precipitates P from the bricks that are dissolved and precipitated from the brick components 22 exposed to high temperatures by the molten metal 28 to the molten glass G and the glass ribbon GR. The precipitates P are alkaline substances produced by the melting and deterioration of the bricks. The size of the precipitates P is, for example, about several tens of μm. The precipitates P are firstly as shown in FIG. Figure 3 As shown in FIG. 2 , the precipitate P is attached to the surface of the brick member 22, but when peeled off from the brick member 22, the specific gravity of the precipitate P is smaller than the specific gravity of the molten tin as the molten metal 28, so it floats toward the upper side (+Z side) inside the molten metal 28. Therefore, if the precipitate P adheres to the molten glass G and the glass ribbon GR transferred on the molten metal 28, defects such as depressions and protrusions will be generated on the surface of the glass ribbon GR. In the inspection process S02, the plate-shaped glass whose size or number of defects exceeds the specified size or number is defective. Therefore, in order to improve the yield of the plate-shaped glass, it is necessary to suppress the precipitate P from adhering to the molten glass G and the glass ribbon GR in the forming process S01.

[0059] like Figure 5 As shown, in the float glass manufacturing method Mg of the present embodiment, when the result of inspecting the sheet glass is that the number of defects Nd per predetermined area of ​​the sheet glass is less than the predetermined target number of defects Na, the forming of the glass ribbon GR is continued (S03), and when the number of defects Nd of the sheet glass is greater than the target number of defects Na, the first cleaning step S04 (S03) is performed. In addition, in the first cleaning step S04, the forming of the glass ribbon GR to become a product is not performed.

[0060] The first cleaning step S04 is a step of cleaning the bottom surface 20c of the floating kiln 20 using the contact portion 53 of the cleaning member 50. Figure 3 As shown, in the first cleaning step S04, the molten glass G and the glass ribbon GR supplied to the molten metal 28 are transferred, and the bottom surface 20c is cleaned by the contact portion 53. The operator moves the shaft portion 51 passing through the opening 25 in the transfer direction (X-axis direction) and the width direction (Y-axis direction) while the contact portion 53 of the cleaning member 50 is in contact with the bottom surface 20c. Thus, the contact portion 53 can be brought into contact with the bottom surface 20c and moved along the bottom surface 20c, so that the precipitate P attached to the bottom surface 20c can be removed from the bottom surface 20c by the contact portion 53. That is, the bottom surface 20c can be cleaned by the cleaning member 50.

[0061] The precipitate P removed from the bottom surface 20c floats upward (+Z side) in the molten metal 28. A portion of the precipitate P removed from the bottom surface 20c adheres to the molten glass G and the glass ribbon GR, is pulled up from the molten metal 28 together with the glass ribbon GR, and is removed from the molten metal 28. Another portion of the precipitate P removed from the bottom surface 20c floats on the surface of the molten metal 28. When the cleaning of the bottom surface 20c is completed, the first cleaning step S04 is completed.

[0062] In addition, the surface of the brick member 22 cleaned in the first cleaning step S04 is not limited to the bottom surface 20c. For example, the inner surface of the side wall brick 22b can be cleaned in addition to the bottom surface 20c. In addition, the cleaning of the bottom surface 20c by the cleaning member 50 can be performed manually by an operator, or automatically by a device that holds the cleaning member 50 and enables the contact portion 53 to slide on the bottom surface 20c. In the first cleaning step S04, in order to suppress the deformation and melting of the shaft portion 51 and the connecting portion 52 of the cleaning member 50 due to the heat applied from the molten metal 28, the cooling operation of taking the shaft portion 51 and the connecting portion 52 out of the inside of the molten metal 28 for cooling and the cleaning of the bottom surface 20c can be alternately repeated. In addition, the shaft portion 51 can also be constructed to be hollow, and the shaft portion 51 can be cooled by flowing a cooling medium such as a liquid, a gas, or a mixture of a liquid and a gas into the inside of the shaft portion 51.

[0063] The recovery step S05 is a step of recovering the precipitates P removed from the bottom surface 20c from the molten metal 28. In the first cleaning step S04, the operator recovers the precipitates P that are not lifted up from the molten metal 28 together with the glass ribbon GR and float on the surface of the molten metal 28 from the molten metal 28. The operator can recover the precipitates P floating on the surface of the molten metal 28 by scooping them up with a member such as a handle scoop. Figure 5 As shown, after the recovery step S05 is completed, the forming step S01 is started again to form the glass ribbon GR.

[0064] Figure 6 : is a diagram showing an example of the transition of the number of defects in the sheet glass of this embodiment. More specifically, Figure 6 This is a graph showing the transition of the number Nd of defects in the sheet glass detected in the above-mentioned inspection step S02. Figure 6 The horizontal axis is the number of days. Figure 6 The vertical axis is the number Nd of defects in the plate glass. In this embodiment, the number Nd of defects in the plate glass is the number of defects per square meter of the plate glass. Figure 6In the transition of the number of defects Nd of the plate glass shown in FIG. 1 , the first cleaning step S04 and the recovery step S05 are performed on day 0. That is, the number of defects Nd of the plate glass before day 0 is the number of defects of the plate glass before the first cleaning step S04 and the recovery step S05 are performed. In addition, the number of defects Nd of the plate glass after day 0 is the number of defects of the plate glass after the first cleaning step S04 and the recovery step S05 are performed. Figure 6 As shown in FIG. 1 , the number Nd of defects in the sheet glass is reduced by about 80% by performing the first cleaning step S04 and the recovery step S05. This is because, as described above, by cleaning the bottom surface 20c of the float kiln 20 with the cleaning member 50, the precipitates P adhering to the bottom surface 20c can be removed from the bottom surface 20c, and by recovering the precipitates P from the molten metal 28, the precipitates P adhering to the molten glass G and the glass ribbon GR in the forming step S01 are reduced. In addition, after performing the first cleaning step S04 and the recovery step S05, the number Nd of defects in the sheet glass can be suppressed from increasing for a long period of at least 90 days.

[0065] According to the present embodiment, the float glass manufacturing apparatus 10 comprises: a float kiln 20 storing molten metal 28; and a cleaning member 50 having a rod-shaped shaft 51 and a contact portion 53 provided at the front end 51a of the shaft 51, the float kiln 20 having: a bottom wall 20a extending in a direction orthogonal to the vertical direction (Z-axis direction); and a side wall 20b extending from the periphery of the bottom wall 20a to the upper side (+Z side), that is, the upper side in the vertical direction, and having an opening 25 through which the shaft 51 passes, the cleaning member 50 can move along the bottom surface 20c in a state where the contact portion 53 contacts the bottom surface 20c of the bottom wall 20a facing the upper side. Thus, as described above, in the first cleaning step S04, the bottom surface 20c is rubbed by the contact portion 53 of the cleaning member 50, so that the precipitate P attached to the bottom surface 20c can be removed from the bottom surface 20c. That is, the bottom surface 20c can be cleaned by the cleaning member 50. Thus, in the forming step S01, the precipitate P can be prevented from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR conveyed on the molten metal 28. Therefore, the occurrence of defects in the glass ribbon GR formed in the forming step S01 can be prevented, and the yield of the sheet glass can be improved.

[0066] According to the present embodiment, the contact portion 53 can contact the portion of the bottom surface 20c that overlaps with the molten glass G or the glass ribbon GR when viewed from the vertical direction (Z-axis direction). As described above, the precipitate P peeled off from the bottom surface 20c floats toward the upper side (+Z side) inside the molten metal 28. Therefore, in the forming step S01, the precipitate P peeled off from the portion of the bottom surface 20c that overlaps with the molten glass G and the glass ribbon GR when viewed from the vertical direction is easily attached to the molten glass G and the glass ribbon GR. In this regard, in the present embodiment, in the first cleaning step S04, the portion of the bottom surface 20c that overlaps with the molten glass G or the glass ribbon GR when viewed from the vertical direction can be cleaned by the cleaning member 50. Therefore, in the forming step S01, the precipitate P peeled off from the bottom surface 20c can be more appropriately suppressed from adhering to the molten glass G or the glass ribbon GR. Therefore, it is possible to more appropriately suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, so that the yield of the sheet glass can be further improved.

[0067] According to the present embodiment, the portion of the bottom wall 20a having the bottom surface 20c is made of brick, the shaft 51 is made of metal, and the contact portion 53 is made of a material containing carbon fiber. Therefore, the hardness of the contact portion 53 can be made smaller than the hardness of the bottom surface 20c, so that the wear of the bottom surface 20c can be suppressed when the bottom surface 20c is cleaned by the contact portion 53. Therefore, in the recovery process S05, the amount of wear powder of the bottom surface 20c recovered from the molten metal 28 can be suppressed from increasing, so the increase in the working hours of the recovery process S05 can be suppressed. Thus, the increase in the time from stopping the forming process S01 to restarting the forming process S01 can be suppressed. Therefore, the reduction in the productivity of the glass ribbon GR and the plate glass can be suppressed. In addition, in the forming process S01, the wear powder of the bottom surface 20c can be suppressed from adhering to the molten glass G and the glass ribbon GR. Thus, the generation of defects in the glass ribbon GR formed in the forming process S01 can be more appropriately suppressed, so the yield of the plate glass can be further improved.

[0068] According to the present embodiment, the float glass manufacturing method Mg includes: a forming step S01, transferring and forming the molten glass G supplied to the molten metal 28 into a glass ribbon GR; and a first cleaning step S04, using a cleaning member 50 to clean the bottom surface 20c of the bottom wall portion 20a facing upward (+Z side), that is, facing upward in the vertical direction, wherein the cleaning member 50 has: a rod-shaped shaft portion 51 passing through the opening portion 25; and a contact portion 53, which is provided at the top end 51a of the shaft portion 51, and the first cleaning step S04 includes: in a state where the contact portion 53 is in contact with the bottom surface 20c, the contact portion 53 is moved along the bottom surface 20c to clean the bottom surface 20c. Therefore, as described above, in the first cleaning step S04, the bottom surface 20c can be cleaned by the cleaning member 50. Thus, in the forming step S01, it is possible to suppress the precipitate P from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR transferred on the molten metal 28. Therefore, since it is possible to suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, the yield of the sheet glass can be improved.

[0069] In addition, in the present embodiment, the precipitate P removed from the bottom surface 20c in the first cleaning step S04 is recovered from the molten metal 28. Therefore, as described above, by recovering the precipitate P removed from the bottom surface 20c and floating on the surface of the molten metal 28, the precipitate P can be removed from the molten metal 28. Therefore, it is possible to more appropriately suppress the precipitate P from adhering to the molten glass G and the glass ribbon GR transferred on the molten metal 28 in the forming step S01. Therefore, it is possible to more appropriately suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, so that the yield of the sheet glass can be further improved.

[0070] According to the present embodiment, the first cleaning step S04 includes: transferring the molten glass G supplied to the molten metal 28, and cleaning the bottom surface 20c by the contact portion 53. Therefore, as described above, in the first cleaning step S04, a part of the precipitate P removed from the bottom surface 20c adheres to the molten glass G and the glass ribbon GR. Therefore, by lifting the precipitate P from the molten metal 28 together with the glass ribbon GR, a part of the precipitate P can be removed from the molten metal 28. Therefore, the precipitate P floating on the surface of the molten metal 28 can be reduced, and thus in the recovery step S05, the precipitate P recovered from the molten metal 28 can be reduced. Therefore, the increase in the working hours of the recovery step S05 can be suppressed, and the increase in the time from stopping the forming step S01 to restarting the forming step S01 can be suppressed. Thus, the reduction in the productivity of the glass ribbon GR and the sheet glass can be suppressed.

[0071] In addition, in the present embodiment, in the first cleaning step S04, the molten glass G supplied to the molten metal 28 is transferred and the bottom surface 20c is cleaned, so when the first cleaning step S04 is started, it is not necessary to stop the supply of the molten glass G to the molten metal 28. In addition, after the first cleaning step S04 is completed, when the forming step S01 is restarted, it is not necessary to restart the supply of the molten glass G to the molten metal 28. Thus, the forming step S01, the first cleaning step S04, and the forming step S01 restarted after the first cleaning step S04 are completed can be continuously performed, so the time from the forming step S01 to the start of the first cleaning step S04 and the time from the first cleaning step S04 to the restart of the forming step S01 can be suppressed from increasing. Therefore, it is possible to suppress the reduction in the productivity of the glass ribbon GR and the plate glass.

[0072] In addition, since the glass ribbon GR formed in the first cleaning step S04 is prone to many defects, the glass ribbon GR may be discarded or melted in a melting furnace as a glass material and reused as molten glass G. In addition, when the size and number of defects of the glass ribbon GR formed in the first cleaning step S04 are better than the predetermined size and number, the plate glass formed from the glass ribbon GR may be used as a product.

[0073] <Second Embodiment>

[0074] Figure 7 1 is a cross-sectional view showing a float glass manufacturing apparatus 110 according to a second embodiment. In the following description, the same reference numerals are used for the same components as those of the first embodiment, and the description thereof is omitted. The float glass manufacturing apparatus 110 according to the present embodiment includes a float kiln 20, molten metal 28, a top portion 30, a lifting roller 41, a conveying roller 42, and a vibration device 150.

[0075] The excitation device 150 is a device for applying vibration to the float glass kiln 20. In the present embodiment, the float glass manufacturing device 110 is provided with a plurality of excitation devices 150. Each excitation device 150 is mounted on the surface of the bottom wall 20a of the float glass kiln 20 facing the lower side (-Z side). Thus, the excitation device 150 applies vibration to at least the bottom wall 20a in the float glass kiln 20. The excitation device 150 may also be mounted on the side wall 20b of the float glass kiln 20. In the present embodiment, each excitation device 150 is arranged at intervals along the conveying direction (X-axis direction). Thus, the unevenness of the vibration applied to the bottom wall 20a can be reduced, so that the precipitate P attached to the bottom wall 20a can be removed from the entire range of the bottom wall 20a. In addition, each excitation device 150 may also be arranged at intervals along the conveying direction and the width direction (Y-axis direction). In this case, the unevenness of the vibration applied to the bottom wall 20a can be more appropriately reduced. The other structures and the like of the float glass manufacturing apparatus 110 of the present embodiment are the same as the other structures and the like of the float glass manufacturing apparatus 10 of the above-mentioned first embodiment.

[0076] Next, a float glass manufacturing method Mg for forming a glass ribbon GR using the float glass manufacturing apparatus 110 of the present embodiment will be described. Figure 8 As shown, the float glass manufacturing method Mg of the present embodiment includes a forming step S01, an inspection step S02, a first cleaning step S04, a second cleaning step S041 for applying vibration to the bottom wall portion 20a using an excitation device 150, and a recovery step S05. The forming step S01, the inspection step S02, the first cleaning step S04, and the recovery step S05 of the present embodiment are the same as the forming step S01, the inspection step S02, the first cleaning step S04, and the recovery step S05 of the above-mentioned first embodiment.

[0077] The second cleaning step S041 is a step of applying vibration to the bottom wall 20a by the vibration device 150 to clean the bottom surface 20c. As described above, when the vibration is applied to the bottom wall 20a, the precipitate P attached to the bottom surface 20c can be removed from the bottom surface 20c. Thus, the bottom surface 20c can be cleaned by the vibration device 150. As described above, in the first cleaning step S04, the bottom surface 20c is cleaned by rubbing the bottom surface 20c with the rectangular contact portion 53. Therefore, in the first cleaning step S04, it is difficult to remove the precipitate P attached to the inside of the pores of the bottom surface 20c. In contrast, in the second cleaning step S041, the precipitate P is removed by applying vibration to the bottom wall 20a, so the precipitate P attached to the inside of the pores of the bottom surface 20c can be easily removed. In addition, in the second cleaning step S041, the glass ribbon GR that becomes a product is not formed.

[0078] In the second cleaning step S041, similarly to the above-mentioned first cleaning step S04, the molten glass G and the glass ribbon GR supplied to the molten metal 28 are transferred, and the bottom surface 20c is cleaned by the excitation device 150. Therefore, a part of the precipitate P removed from the bottom surface 20c adheres to the molten glass G and the glass ribbon GR, is pulled up from the molten metal 28 together with the glass ribbon GR, and is removed from the molten metal 28. Another part of the precipitate P removed from the bottom surface 20c floats on the surface of the molten metal 28. When the cleaning of the bottom surface 20c is completed, the second cleaning step S041 is completed.

[0079] In the recovery step S05 of the present embodiment, the precipitates P that are not lifted up from the molten metal 28 together with the glass ribbon GR and float on the surface of the molten metal 28 among the precipitates P removed from the bottom surface 20c in the first cleaning step S04 and the second cleaning step S041 are recovered from the molten metal 28. Figure 8 As shown, after the collection step S05 is completed, the forming step S01 is started again to form the glass ribbon GR.

[0080] According to the present embodiment, the float glass manufacturing apparatus 110 is provided with an excitation device 150 for applying vibration to at least the bottom wall portion 20a in the float furnace 20. Therefore, as described above, by applying vibration to the bottom wall portion 20a, the precipitate attached to the bottom surface 20c can be removed. In addition, as described above, in the second cleaning step S041, the precipitate P attached to the inside of the pores of the bottom surface 20c can be removed. Thus, in the forming step S01, it is possible to more appropriately suppress the precipitate P from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR transferred on the molten metal 28. Therefore, it is possible to more appropriately suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, so that the yield rate of the plate glass can be further improved.

[0081] According to the present embodiment, the float glass manufacturing method Mg includes a second cleaning step S041 in which the bottom wall portion 20a is vibrated by the vibration device 150 capable of vibrating the float kiln 20 to clean the bottom surface 20c. Therefore, in both the first cleaning step S04 and the second cleaning step S041, the bottom surface 20c can be cleaned. In addition, as described above, in the second cleaning step S041, the precipitate P attached to the inside of the pores of the bottom surface 20c can be easily removed. Therefore, it is possible to more appropriately suppress the precipitate P from being attached to the molten glass G and the glass ribbon GR transferred on the molten metal 28, so that the yield rate of the plate glass can be further improved.

[0082] In addition, in the present embodiment, in the second cleaning step S041, the molten glass G supplied to the molten metal 28 is transferred, and the bottom surface 20c is cleaned. Therefore, similarly to the above-mentioned first cleaning step S04, a part of the precipitate P removed from the bottom surface 20c in the second cleaning step S041 can be lifted from the molten metal 28 together with the glass ribbon GR and removed from the molten metal 28. Therefore, in the recovery step S05, the precipitate P recovered from the molten metal 28 can be reduced, so that the increase in the working hours of the recovery step S05 can be suppressed. Thus, the reduction in the productivity of the glass ribbon GR and the plate glass can be suppressed.

[0083] In addition, in the present embodiment, the second cleaning step S041 is performed after the first cleaning step S04, but the second cleaning step S041 may be performed before the first cleaning step S04, or may be performed simultaneously with the first cleaning step S04. When the second cleaning step S041 is performed simultaneously with the first cleaning step S04, it is possible to suppress the increase in the time from stopping the forming step S01 to restarting the forming step S01. Thus, it is possible to appropriately suppress the reduction in the productivity of the glass ribbon GR and the plate glass.

[0084] The embodiments of the present invention are described above, but the various structures and their combinations in the embodiments are examples, and addition, omission, substitution and other changes of structures can be made without departing from the gist of the present invention. In addition, the present invention is not limited to the embodiments.

[0085] The material of the shaft portion and the connecting portion constituting the cleaning member is not limited to the present embodiment, and may be, for example, ceramic, or a material containing carbon fiber in the same manner as the contact portion. In addition, when the material constituting the shaft portion and the connecting portion is the same material as the material constituting the contact portion, the cleaning member may be integrally formed and constituted. In addition, the shape of the contact portion may also be other shapes such as a disc.

[0086] The structure of the floating kiln is not limited to the present embodiment. For example, the floating kiln may be in other shapes such as a circle or an ellipse when viewed from a vertical direction.

[0087] The first cleaning step and the second cleaning step may be performed by stopping the supply of the molten glass G to the molten metal. Thus, in the first cleaning step and the second cleaning step, it is possible to suppress the formation of a glass ribbon with many defects, thereby reducing the amount of discarded glass ribbon.

Claims

1. A float glass manufacturing apparatus, wherein molten glass supplied to a molten metal is formed into a glass ribbon on the molten metal, wherein: have: A floating kiln for storing the molten metal; and The cleaning member has a rod-shaped shaft portion and a contact portion provided at the front end of the shaft portion. The floating kiln comprises: a bottom wall portion extending in a direction perpendicular to the vertical direction; and a side wall portion extending from the peripheral edge of the bottom wall portion toward the upper side in the vertical direction and provided with an opening portion for the shaft portion to pass through. The cleaning member is movable along the bottom surface in a state where the contact portion is in contact with a bottom surface of the bottom wall portion that faces upward in a vertical direction.

2. The float glass manufacturing apparatus according to claim 1, wherein: The contact portion can be in contact with a portion of the bottom surface that overlaps with the molten glass or the glass ribbon when viewed in a vertical direction.

3. The float glass manufacturing device according to claim 1 or 2, wherein: The portion of the bottom wall portion having the bottom surface is made of brick, the shaft portion is made of metal, and the contact portion is made of a material containing carbon fibers.

4. The float glass manufacturing apparatus according to claim 1, wherein: The float glass manufacturing apparatus includes a vibration excitation device for applying vibration to at least the bottom wall portion of the float glass furnace.

5. A method for manufacturing float glass, comprising forming a glass ribbon using a float glass manufacturing device, wherein the float glass manufacturing device comprises a float kiln, the float kiln storing molten metal and having a bottom wall extending in a direction perpendicular to a vertical direction and a side wall extending from a peripheral edge of the bottom wall toward an upper side in a vertical direction and having an opening, wherein: The float glass manufacturing method comprises the following steps: transferring and shaping the molten glass supplied to the molten metal into the glass ribbon; and The bottom surface of the bottom wall portion facing upward in the vertical direction is cleaned using a cleaning member. The cleaning member comprises: A rod-shaped shaft portion passes through the opening portion; and A contact portion is provided at the front end of the shaft portion, The step of cleaning the bottom surface includes: moving the contact portion along the bottom surface to clean the bottom surface while the contact portion is in contact with the bottom surface.

6. The method for manufacturing float glass according to claim 5, wherein: The step of cleaning the bottom surface includes transferring the molten glass supplied onto the molten metal and cleaning the bottom surface using the contact portion.

7. The method for manufacturing float glass according to claim 5 or 6, wherein: The float glass manufacturing method includes a step of applying vibration to the bottom wall portion using a vibration excitation device capable of applying vibration to the float glass furnace to clean the bottom surface.

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