Apparatus and method for manufacturing float glass

Abstract

To provide an apparatus and method for manufacturing float glass, capable of preventing a deposit from adhering to molten glass and glass ribbon transferred on molten metal.SOLUTION: An apparatus for manufacturing float glass, capable of molding molten glass supplied on molten metal into a glass ribbon on the molten metal includes: a float bus for storing the molten metal; and a cleaning member including a rod-like axial part and a contact part provided at the tip of the axial part. The float bus includes: a bottom wall part expanding in a direction orthogonal to the vertical direction; and a side wall part extending on the upper side in the vertical direction from the periphery of the bottom wall part and having an opening passing the axial part. The cleaning member can move along the bottom surface in the state of contacting the contact part to the bottom surface of the bottom wall part facing on the upper side in the vertical direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an apparatus and a method for manufacturing float glass. [Background technology]

[0002] The manufacture of sheet glass by float forming is generally carried out as follows. First, molten glass obtained by heating and melting glass raw materials is continuously supplied onto the surface of molten metal such as molten tin stored in a float bath. Then, the molten glass is formed into a glass ribbon while being transported along the surface of the molten metal. The formed glass ribbon is then drawn out of the float bath, slowly cooled and washed, and then cut to obtain sheet glass of a desired size. The float forming method for producing sheet glass has high productivity and the obtained sheet glass has excellent flatness, and therefore the sheet glass produced by the float forming is widely used as a sheet glass for construction, an automobile, a flat panel display (FPD), etc. Patent Document 1 discloses an apparatus for producing float sheet glass, which includes a float bath formed in a bathtub shape by arranging a plurality of bottom bricks inside a metal bottom casing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-124123 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a float bath having the above-mentioned configuration, deposits derived from the bricks that are exposed to high temperatures by the molten metal melt and precipitate adhere to the bricks. When such deposits peel off from the bricks and float toward the surface of the molten metal, they may adhere to the molten glass and glass ribbon transported on the molten metal. This causes defects such as depressions and protrusions on the surface of the glass ribbon, and the deposition of deposits on the molten glass and glass ribbon has been a factor in reducing the yield of sheet glass.

[0005] In view of the above circumstances, 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 the molten glass and glass ribbon transported on the molten metal. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] A float glass manufacturing apparatus in which molten glass supplied onto molten metal is formed into a glass ribbon on the molten metal, the float glass manufacturing apparatus comprising: a float bath for storing the molten metal; and a cleaning member having a rod-shaped shaft portion and a contact portion provided at a tip of the shaft portion, wherein the float bath has a bottom wall portion extending in a direction perpendicular to the vertical direction, and a side wall portion extending vertically upward from a periphery of the bottom wall portion and having an opening through which the shaft portion is passed, and the cleaning member is movable along the bottom surface with the contact portion in contact with the bottom surface facing vertically upward of the bottom wall portion. [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 from a vertical direction. [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 composed of a material containing carbon fiber. [4] The float glass manufacturing apparatus according to any one of [1] to [3], further comprising a vibration device that applies vibration to at least the bottom wall portion of the float bath. [5] A method for manufacturing float glass, in which a glass ribbon is formed by a float glass manufacturing apparatus including a float bath that stores molten metal, and that has a bottom wall portion extending in a direction perpendicular to the vertical direction, and a side wall portion extending vertically upward from a periphery of the bottom wall portion and having an opening, the method including: forming molten glass supplied onto the molten metal into the glass ribbon while transporting the molten glass, and cleaning a bottom surface facing vertically upward of the bottom wall portion using a cleaning member, the cleaning member having a rod-shaped shaft portion that is passed through the opening and a contact portion provided at a tip of the shaft portion, and cleaning the bottom surface includes moving the cleaning member along the bottom surface with the contact portion in contact with the bottom surface to clean the bottom surface. [6] The float glass manufacturing method according to [5], wherein cleaning the bottom surface includes cleaning the bottom surface with the contact portion while transferring the molten glass supplied onto the molten metal. [7] The method for manufacturing float glass according to [5] or [6], further comprising: applying vibration to the bottom wall portion by a vibration excitation device capable of applying vibration to the float bath to clean the bottom surface. Effect of the Invention

[0007] 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 the molten glass and glass ribbon transported on the molten metal. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing an example of a float glass manufacturing apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing an example of a state of molten glass transported on molten metal in the first embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing an example of the float glass manufacturing apparatus according to the first embodiment of the present invention, taken along line III-III in FIG. [Figure 4]FIG. 2 is a perspective view illustrating an example of a cleaning member according to the first embodiment of the present invention. [Diagram 5] 1 is a flowchart showing a float glass manufacturing method according to a first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing an example of a change in the number of defects in the glass plate according to the first embodiment of the present invention. [Figure 7] FIG. 4 is a cross-sectional view showing an example of a float glass manufacturing apparatus according to a second embodiment of the present invention. [Figure 8] 5 is a flowchart showing a float glass manufacturing method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 drawings. Note that the dimensions of the drawings illustrated in the following description are merely examples, and the present invention is not necessarily limited thereto, and can be appropriately modified and implemented within the scope of the present invention.

[0010] In each drawing, 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 where the Z-axis arrow points (+Z side) is called the "upper side" or "vertically upper side", and the opposite side to the side where the Z-axis arrow points (-Z side) is called the "lower side". The X-axis direction is a direction perpendicular to the Z-axis direction, and in the following embodiment, is the direction in which the molten glass and the glass ribbon are transported. In the following embodiment, the molten glass and the glass ribbon are transported in the direction where the X-axis arrow points. In the following description, the X-axis direction is simply called the "transport direction", the side where the X-axis arrow points (+X side) is called the "downstream side", and the opposite side to the side where the X-axis arrow points (-X side) is called the "upstream side". The Y-axis direction is a direction perpendicular to both the X-axis direction and the Z-axis direction, and is the width direction of the float glass manufacturing apparatus. In the following description, the Y-axis direction will simply be referred to as the "width direction", the side toward which the Y-axis arrow points (+Y side) will be referred to as "one side in the width direction", and the side opposite to the side toward which the Y-axis arrow points (-Y side) will be referred to as "the other side in the width direction".

[0011] First Embodiment Hereinafter, a float glass manufacturing apparatus 10 and a float glass manufacturing method Mg according to a first embodiment will be described with reference to the drawings. As shown in FIG. 1, the float glass manufacturing apparatus 10 of the present embodiment is an apparatus that transfers molten glass G supplied onto molten metal 28 stored in a float bath 20 along the surface of the molten metal 28, while spreading the molten glass G from both sides in the width direction (Y-axis direction) by top rolls 61 shown in FIG. 2, to form a strip-shaped glass ribbon GR on the molten metal 28. As shown in FIG. 1, the float glass manufacturing apparatus 10 includes a float bath 20, molten metal 28, a roof 30, a lift-out roll 41, and a conveying roll 42. As shown in FIG. 2, the float glass manufacturing apparatus 10 includes a top roll 61. Furthermore, as shown in FIG. 3, the float glass manufacturing apparatus 10 includes a cleaning member 50.

[0012] A melting furnace (not shown) is disposed upstream (-X side) of the float bath 20, which heats and melts a glass material to produce molten glass G. The molten glass G is supplied from the melting furnace onto the molten metal 28 stored in the float bath 20. In the float bath 20, the molten glass G is transported downstream (+X side) on the molten metal 28, and tension is applied by top rolls 61 disposed on both sides of the width direction of the molten glass G as shown in FIG. 2, and the molten glass G is adjusted to a desired width and thickness. As a result, a band-shaped glass ribbon GR adjusted to a desired width and thickness is formed. As shown in FIG. 1, the glass ribbon GR is lifted up from the float bath 20 by a lift-out roll 41 disposed downstream of the float bath 20, and is transported by a transport roll 42 to an annealing furnace (not shown) and annealed. The glass ribbon GR annealed in the annealing furnace is then washed and cut to a predetermined dimension by a cutting device (not shown), to obtain a plate glass of a predetermined size.

[0013] The inlet portion 16a is formed by the molten metal 28 and the roof 30 on the upstream side (-X side) of the float bath 20. The molten glass G transported from a melting furnace (not shown) to the downstream side (+X side) through the supply passage 12 is supplied onto the molten metal 28 through a lip 13 provided at the downstream end of the supply passage 12, and is transported downstream on the molten metal 28 through the inlet portion 16a. A twill 14 for adjusting the flow of the molten glass G is disposed in the supply passage 12 upstream of the lip 13. The temperature of the molten glass G supplied onto the molten metal 28 is equal to or 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.

[0014] On the downstream side (+X side) of the float bath 20, an outlet portion 16b is formed by the float bath 20 and the roof 30. The glass ribbon GR formed to a predetermined width and thickness by the top roll 61 as described above is pulled up from the float bath 20 by the lift-out roll 41 through the outlet portion 16b.

[0015] The float bath 20 stores the molten metal 28. In this embodiment, the molten metal 28 is molten tin. As shown in FIGS. 1 and 2, the float bath 20 is a container having a substantially rectangular parallelepiped shape with its long sides extending in the transport direction (X-axis direction). The float bath 20 opens on the upper side (+Z side). As shown in FIG. 1, the float bath 20 has a bottom wall portion 20a and a side wall portion 20b. The bottom wall portion 20a extends in a direction perpendicular to the vertical direction (Z-axis direction). When viewed in the vertical direction, the bottom wall portion 20a has a substantially rectangular shape with its long sides extending in the transport direction. The bottom wall portion 20a is the bottom of the float bath 20.

[0016] The side wall portion 20b extends upward (+Z side) from the periphery of the bottom wall portion 20a, that is, vertically upward. As shown in FIG. 2, the side wall portion 20b is substantially rectangular frame-shaped when viewed in the vertical direction (Z-axis direction). The side wall portion 20b has an upstream wall portion 20e, a downstream wall portion 20f, a first wall portion 20g, a second wall portion 20h, and an opening 25. As shown in FIG. 1, the upstream wall portion 20e is plate-shaped 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 upstream of the lip 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 conveying direction, the downstream wall portion 20f has a substantially rectangular shape.

[0017] As shown in FIG. 3, the first wall portion 20g extends upward (+Z side) from an edge portion on one side (+Y side) in the width direction of the bottom wall portion 20a. The second wall portion 20h extends upward from an edge portion on the other side (-Y side) in the width direction of the bottom wall portion 20a. When viewed from the width direction (Y axis direction), the first wall portion 20g and the second wall portion 20h are substantially rectangular. The opening portion 25 is an opening provided between each of the first wall portion 20g and the second wall portion 20h and the roof 30. The opening portion 25 extends along the transfer direction (X axis direction). The opening portion 25 connects the internal spaces of the float bath 20 and the roof 30 to the external space of the float glass manufacturing apparatus 10.

[0018] As shown in FIG. 1, the float bath 20 has a case 21 and a plurality of brick members 22. As shown in FIGS. 1 and 3, the case 21 is a substantially rectangular parallelepiped container whose long sides extend in the transfer direction (X-axis direction). The case 21 opens on the upper side (+Z side). In this embodiment, the case 21 is made of metal. There are no particular limitations on the material constituting the case 21, and metal materials such as iron and stainless steel can be used. As shown in FIG. 1, the case 21 has a case bottom wall portion 21a and a case side wall portion 21b.

[0019] The case bottom wall 21a is a plate-like shape that extends in a direction perpendicular to the vertical direction (Z-axis direction). When viewed from the vertical direction, the case bottom wall 21a is substantially rectangular with its long side extending in the transfer direction. The case side wall 21b extends upward (to the +Z side) from the periphery of the case bottom wall 21a. When viewed from the vertical direction, the case side wall 21b is substantially rectangular frame-like.

[0020] The plurality of brick members 22 are disposed inside the case 21. In this embodiment, each brick member 22 has a substantially rectangular parallelepiped shape. Each brick member 22 is made of brick. The material constituting each brick member 22 is preferably one that is unlikely to react with molten tin, which is the molten metal 28, and has high temperature and moisture resistance, and may be, for example, alumina, sillimanite, clay, or other material. The plurality of brick members 22 include a plurality of bottom wall bricks 22a and a plurality of side wall bricks 22b.

[0021] As shown in Figs. 1 and 3, a plurality of bottom wall bricks 22a are arranged on the case bottom wall portion 21a. The bottom wall bricks 22a are arranged side by side in the transfer direction (X-axis direction) and the width direction (Y-axis direction). The bottom wall bricks 22a arranged adjacent to each other in the transfer direction and the width direction are in contact with each other. The surface facing the upper side (+Z side) of each bottom wall brick 22a constitutes the upper side of the bottom wall portion 20a, that is, the bottom surface 20c, which is the surface facing the upper side in the vertical direction. Therefore, in this embodiment, the portion of the bottom wall portion 20a having the bottom surface 20c is made of brick.

[0022] The sidewall bricks 22b are arranged side by side on the case bottom wall 21a along the inner surface of the case sidewall 21b. The sidewall bricks 22b arranged adjacent to each other in the transfer direction (X-axis direction) and width direction (Y-axis direction) are in contact with each other. The vertical dimension (Z-axis direction) of each sidewall brick 22b is larger than the vertical dimension of each bottom wall brick 22a.

[0023] As shown in FIG. 1 and FIG. 3, the roof 30 is a substantially rectangular box shape with its long sides extending in the transport direction (X-axis direction). The roof 30 opens on the lower side (-Z side). The roof 30 is disposed on the upper side (+Z side) of the float bath 20. As a result, the space above the float bath 20 is surrounded by the roof 30. The inside of the roof 30 is filled with a reducing atmosphere such as a nitrogen gas atmosphere containing about 12% or less hydrogen. As a result, the space above the molten metal 28 is isolated from the external atmosphere as much as possible. The roof 30 is disposed at a distance from the float bath 20 in the vertical direction (Z-axis direction). A plurality of heaters (not shown) are disposed inside the roof 30. The plurality of heaters adjust the temperature inside the roof 30. Note that the heaters may not be provided. As shown in FIG. 1, the roof 30 has a top wall portion 31, an upstream protruding wall 32, and a downstream protruding wall 33. As shown in FIG. 3, the roof 30 has a first protruding wall 34a and a second protruding wall 34b.

[0024] As shown in FIG. 1, the top wall portion 31 is a plate-like shape extending in a direction perpendicular to the vertical direction (Z-axis direction). Although not shown, the top wall portion 31 is a substantially rectangular shape with a long side extending in the transfer direction (X-axis direction) when viewed in the vertical direction. When viewed in the vertical direction, the top wall portion 31 overlaps with the bottom wall portion 20a. The upstream end (-X side) of the top wall portion 31 is located downstream (+X side) of the upstream end of the float bath 20. The upstream protruding wall 32 is a plate-like shape protruding downward (-Z side) from the upstream edge of the top wall portion 31. When viewed in the transfer direction, the upstream protruding wall 32 is a substantially rectangular shape. The upstream protruding wall 32 is disposed downstream of the upstream wall portion 20e. The upstream protruding wall 32 is disposed at a vertical interval from the molten metal 28. As a result, the inlet portion 16a is provided between the upstream protruding wall 32 and the surface of the molten metal 28.

[0025] The downstream protruding wall 33 is a plate-like member protruding downward (-Z side) from the edge of the downstream side (+X side) of the top wall portion 31. When viewed from the transfer direction (X-axis direction), the downstream protruding wall 33 is substantially rectangular. The downstream protruding wall 33 faces the downstream wall portion 20f of the float bath 20 with a gap therebetween in the vertical direction (Z-axis direction). As a result, the outlet portion 16b is provided between the downstream protruding wall 33 and the downstream wall portion 20f.

[0026] As shown in FIG. 3, the first protruding wall 34a is a plate-like protruding downward (-Z side) from an edge of one side (+Y side) in the width direction of the top wall portion 31. The second protruding wall 34b is a plate-like protruding downward from an edge of the other side (-Y side) in the width direction of the top wall portion 31. When viewed from the width direction (Y axis direction), the first protruding wall 34a and the second protruding wall 34b are substantially rectangular. The first protruding wall 34a and the second protruding wall 34b are each disposed at an interval in the vertical direction (Z axis direction) from the first wall portion 20g and the second wall portion 20h of the float bath 20, respectively. This provides an opening 25 in the side wall portion 20b.

[0027] In addition, as long as the opening 25 connects the internal space of the float bath 20 and the roof 30 with the external space of the float glass manufacturing apparatus 10, the configuration 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 bath 20 in the vertical direction (Z-axis direction), the opening 25 may be a hole penetrating the first wall 20g and the second wall 20h in the width direction (Y-axis direction), or may be a hole penetrating one of the first wall 20g or the second wall 20h in the width direction. In this case, a plurality of openings 25 may be provided along the transport direction (X-axis direction).

[0028] The cleaning member 50 is a member that cleans the bottom surface 20c of the float bath 20. As shown in FIG. 4, the cleaning member 50 has a shaft portion 51, a connection portion 52, and a contact portion 53. The shaft portion 51 is a rod-like member that extends linearly. In this embodiment, the shaft portion 51 is a cylindrical rod-like member. The shaft portion 51 may be a rod-like member having another shape, such as a rectangular column shape. In this embodiment, the shaft portion 51 is made of metal. The material constituting the shaft portion 51 is preferably a material having high heat resistance, and may be, for example, iron or stainless steel. As shown in FIG. 3, the diameter of the shaft portion 51 is smaller than the dimension of the opening 25 in the vertical direction (Z-axis direction). This allows the shaft portion 51 to pass through the opening 25. The shaft portion 51 is movable inside the opening 25 in the width direction (Y-axis direction) and the transfer direction (X-axis direction). The cleaning member 50 may be attached to the float bath 20 so as to be movable relative to the float bath 20, or may be detachable from the float bath 20.

[0029] As shown in Fig. 4, the connection part 52 connects the shaft part 51 and the contact part 53. The connection part 52 is connected to the tip 51a of the shaft part 51. In this embodiment, the connection part 52 has a substantially rectangular parallelepiped shape. In this embodiment, the connection part 52 is made of metal. The material constituting the connection part 52 is preferably a material having high heat resistance, and materials such as iron and stainless steel can be used, for example.

[0030] The contact portion 53 is a portion of the cleaning member 50 that cleans the bottom surface 20c. The contact portion 53 is connected to the connection portion 52. As a result, the contact portion 53 is provided at the tip 51a of the shaft portion 51 via the connection portion 52. In this embodiment, the connection portion 52 is substantially rectangular. In this embodiment, the contact portion 53 is made of a material containing carbon fiber. The contact portion 53 can be made of, for example, a resin containing carbon fiber, ceramics and metal, a carbon extrusion material, a carbon CIP material, or the like. As a result, the heat resistance of the contact portion 53 can be improved compared to when the contact portion 53 is made of metal, and the hardness of the contact portion 53 can be made smaller than the hardness of the brick member 22.

[0031] As shown in FIG. 3, when the shaft portion 51 is passed through the opening 25, the contact portion 53 can contact the bottom surface 20c of the float bath 20. When the shaft portion 51 is moved in the transfer direction (X-axis direction) and the width direction (Y-axis direction) while passing through the opening 25, the contact portion 53 can move along the bottom surface 20c while in contact with the bottom surface 20c. This allows the contact portion 53 to remove deposits P, which will be described later, attached to the bottom surface 20c. That is, the cleaning member 50 can clean the bottom surface 20c. In this embodiment, the contact portion 53 can contact a 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). This allows the cleaning member 50 to clean a portion of the bottom surface 20c that overlaps with the molten glass G or the glass ribbon GR when viewed from the vertical direction.

[0032] Next, a float glass manufacturing method Mg for forming a glass ribbon GR by the float glass manufacturing apparatus 10 of the present embodiment will be described. As shown in FIG. 5, the float glass manufacturing method Mg of the present embodiment includes a forming step S01 for forming the molten glass G supplied onto the molten metal 28 into a glass ribbon GR while transferring it, an inspection step S02 for inspecting the sheet glass, a first cleaning step S04 for cleaning the bottom surface 20c of the float bath 20 by the contact portion 53 of the cleaning member 50, and a recovery step S05 for recovering the precipitate P removed from the bottom surface 20c from the molten metal 28. In the following description, "workers, etc." includes workers and devices, etc. performing the work of each process. The work of each process may be performed only by the workers, only by the devices, etc., or by the workers and the devices, etc.

[0033] The forming step S01 is a step of forming the molten glass G supplied onto the molten metal 28 into a glass ribbon GR while transferring it. In the forming step S01, an operator or the like supplies the molten glass G onto the molten metal 28 stored in the float bath 20 as shown in FIG. 1. Next, as shown in FIG. 2, an operator or the like adjusts the molten glass G to a desired width and thickness by a top roll 61 while transferring the molten glass G on the molten metal 28 toward the downstream side (+X side), thereby forming a band-shaped glass ribbon GR adjusted to a desired width and thickness. Thereafter, as described above, the glass ribbon GR is pulled up from the float bath 20, and the glass ribbon GR cooled in an annealing furnace (not shown) is cut into a predetermined dimension by a cutting device (not shown) to obtain a plate glass of a predetermined size.

[0034] The inspection process S02 is a process for inspecting the glass sheets obtained in the forming process S01 for defects and the number of defects. An operator may inspect all glass sheets, or may inspect a predetermined number of glass sheets at a predetermined period, such as inspecting one glass sheet per day. Defects in glass sheets are generated, for example, when deposits P derived from bricks, which are melted and deposited from the brick members 22 exposed to high temperatures by the molten metal 28, adhere to the molten glass G and the glass ribbon GR. The deposits P are alkaline substances formed by melting and altering the properties of the bricks. The size of the deposits P is, for example, about several tens of μm. The deposits P first adhere to the surface of the brick members 22 as shown in FIG. 3, but when they peel off from the brick members 22, they float up inside the molten metal 28 toward the upper side (+Z side) because the specific gravity of the deposits P is smaller than the specific gravity of the molten tin, which is the molten metal 28. As a result, if the precipitates P adhere to the molten glass G and the glass ribbon GR transported on the molten metal 28, defects such as depressions and protrusions will occur on the surface of the glass ribbon GR. In the inspection step S02, glass sheets with defects exceeding a predetermined size or number will be deemed defective. Therefore, in order to increase the yield of glass sheets, it is necessary to suppress the deposition of such precipitates P on the molten glass G and the glass ribbon GR in the forming step S01.

[0035] 5, in the float glass manufacturing method Mg of the present embodiment, when the number Nd of defects per a given area of ​​the plate glass is smaller than a predetermined target number Na of defects as a result of inspecting the plate glass, the forming of the glass ribbon GR is continued (S03), and when the number Nd of defects in the plate glass is larger than the target number Na of defects, a first cleaning step S04 is performed (S03). Note that in the first cleaning step S04, the forming of the glass ribbon GR to be the product is not performed.

[0036] The first cleaning step S04 is a step of cleaning the bottom surface 20c of the float bath 20 with the contact portion 53 of the cleaning member 50. As shown in FIG. 3, in the first cleaning step S04, the bottom surface 20c is cleaned with the contact portion 53 while transferring the molten glass G and the glass ribbon GR supplied to the molten metal 28. With the contact portion 53 of the cleaning member 50 in contact with the bottom surface 20c, the worker or the like moves the shaft portion 51 passed through the opening 25 in the transfer direction (X-axis direction) and the width direction (Y-axis direction). This allows the contact portion 53 to move along the bottom surface 20c while being in contact with the bottom surface 20c, so that the deposit 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.

[0037] The precipitates P removed from the bottom surface 20c float upward (to the +Z side) inside the molten metal 28. A portion of the precipitates P removed from the bottom surface 20c adheres to the molten glass G and the glass ribbon GR, and is pulled up together with the glass ribbon GR from the molten metal 28 and removed from the molten metal 28. Another portion of the precipitates P removed from the bottom surface 20c floats on the surface of the molten metal 28. When cleaning of the bottom surface 20c is completed, the first cleaning step S04 is completed.

[0038] In addition, the surface of the brick member 22 to be 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 may be cleaned in addition to the bottom surface 20c. The cleaning of the bottom surface 20c by the cleaning member 50 may be performed manually by an operator or automatically by a device that holds the cleaning member 50 and can slide the contact portion 53 on the bottom surface 20c. In the first cleaning step S04, in order to prevent the shaft portion 51 and the connection portion 52 of the cleaning member 50 from being deformed and melted by the heat given from the molten metal 28, a cooling operation in which the shaft portion 51 and the connection portion 52 are removed from the inside of the molten metal 28 and cooled, and cleaning of the bottom surface 20c may be performed alternately and repeatedly. In addition, the shaft portion 51 may be formed to be hollow, and a cooling medium such as a liquid, a gas, or a mixture of liquid and gas may be poured into the shaft portion 51 to cool the shaft portion 51.

[0039] The recovery step S05 is a step of recovering the precipitate P removed from the bottom surface 20c from the molten metal 28. The worker or the like recovers from the molten metal 28 the precipitate P that was not pulled up from the molten metal 28 together with the glass ribbon GR and floats on the surface of the molten metal 28, among the precipitate P removed from the bottom surface 20c in the first cleaning step S04. The worker or the like can recover the precipitate P by scooping up the precipitate P floating on the surface of the molten metal 28 using, for example, a ladle-shaped member. As shown in FIG. 5, when the recovery step S05 is completed, the forming step S01 is resumed and the glass ribbon GR is formed.

[0040] FIG. 6 is a diagram showing an example of the transition of the number of defects in the glass sheet in this embodiment. More specifically, FIG. 6 is a graph showing the transition of the number Nd of defects in the glass sheet detected in the above-mentioned inspection step S02. The horizontal axis of FIG. 6 is the number of days. The vertical axis of FIG. 6 is the number Nd of defects in the glass sheet. In this embodiment, the number Nd of defects in the glass sheet is the number of defects per square meter of the glass sheet. In the transition of the number Nd of defects in the glass sheet shown in FIG. 6, the above-mentioned first cleaning step S04 and collection step S05 are performed on day 0. That is, the number Nd of defects in the glass sheet before day 0 is the number of defects in the glass sheet before the above-mentioned first cleaning step S04 and collection step S05 are performed. Moreover, the number Nd of defects in the glass sheet after day 0 is the number of defects in the glass sheet after the above-mentioned first cleaning step S04 and collection step S05 are performed. 6, the number Nd of defects in the plate glass is reduced by about 80% by performing the first cleaning step S04 and the collecting step S05. This is because, as described above, by cleaning the bottom surface 20c of the float bath 20 with the cleaning member 50, the precipitates P adhering to the bottom surface 20c can be removed from the bottom surface 20c, and the precipitates P adhering to the molten glass G and the glass ribbon GR in the forming step S01 are reduced by collecting the precipitates P from the molten metal 28. In addition, after performing the first cleaning step S04 and the collecting step S05, an increase in the number Nd of defects in the plate glass can be suppressed for a long period of at least 90 days or more.

[0041] According to this embodiment, the float glass manufacturing apparatus 10 includes a float bath 20 storing the molten metal 28, and a cleaning member 50 having a rod-shaped shaft portion 51 and a contact portion 53 provided at the tip 51a of the shaft portion 51. The float bath 20 has a bottom wall portion 20a extending in a direction perpendicular to the vertical direction (Z-axis direction), and a side wall portion 20b extending from the periphery of the bottom wall portion 20a to the upper side (+Z side), i.e., vertically upward, and provided with an opening portion 25 through which the shaft portion 51 passes. The cleaning member 50 can move along the bottom surface 20c with the contact portion 53 in contact with the bottom surface 20c facing the upper side of the bottom wall portion 20a. As a result, as described above, in the first cleaning step S04, the contact portion 53 of the cleaning member 50 rubs against the bottom surface 20c, so that the deposit 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. This makes it possible to suppress, in the forming step S01, the deposits P from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR transported on the molten metal 28. This makes it possible to suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, thereby increasing the yield of the plate glass.

[0042] According to this 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 up inside the molten metal 28 toward the upper side (+Z side). 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 likely to adhere to the molten glass G and the glass ribbon GR. In contrast, in this 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 suitably prevented from adhering to the molten glass G or the glass ribbon GR. Therefore, the occurrence of defects in the glass ribbon GR formed in the forming step S01 can be more suitably suppressed, and the yield of plate glass can be further increased.

[0043] According to this embodiment, the portion of the bottom wall portion 20a having the bottom surface 20c is made of brick, the shaft portion 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 contact portion 53 cleans the bottom surface 20c. Therefore, in the recovery step S05, the amount of wear powder of the bottom surface 20c recovered from the molten metal 28 can be suppressed from increasing, so that the number of work steps in the recovery step S05 can be suppressed from increasing. This can suppress an increase in the time from when the forming step S01 is stopped to when the forming step S01 is resumed. Therefore, the productivity of the glass ribbon GR and the plate glass can be suppressed from decreasing. Also, in the forming step S01, the wear powder of the bottom surface 20c can be suppressed from adhering to the molten glass G and the glass ribbon GR. This can more suitably suppress the occurrence of defects in the glass ribbon GR formed in the forming step S01, so that the yield of the plate glass can be further increased.

[0044] According to this embodiment, the float glass manufacturing method Mg includes a forming step S01 in which the molten glass G supplied onto the molten metal 28 is formed into a glass ribbon GR while being transported, and a first cleaning step S04 in which the upper side (+Z side) of the bottom wall portion 20a, i.e., the bottom surface 20c facing upward in the vertical direction, is cleaned using a cleaning member 50. The cleaning member 50 has a rod-shaped shaft portion 51 that is passed through the opening 25 and a contact portion 53 provided at the tip 51a of the shaft portion 51, and the first cleaning step S04 includes moving the contact portion 53 along the bottom surface 20c while the contact portion 53 is in contact with 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. This makes it possible to suppress the deposit P from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR transported on the molten metal 28 in the forming step S01. Therefore, the occurrence of defects in the glass ribbon GR formed in the forming step S01 can be suppressed, and the yield of sheet glass can be increased.

[0045] Moreover, in this embodiment, the precipitate P removed from the bottom surface 20c in the first cleaning step S04 is collected from the molten metal 28. Thus, as described above, by collecting 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. This makes it possible to more suitably prevent the precipitate P from adhering to the molten glass G and the glass ribbon GR transported on the molten metal 28 in the forming step S01. Thus, it is possible to more suitably prevent the occurrence of defects in the glass ribbon GR formed in the forming step S01, thereby further increasing the yield of plate glass.

[0046] According to the present embodiment, the first cleaning step S04 includes cleaning the bottom surface 20c by the contact portion 53 while transferring the molten glass G supplied onto the molten metal 28. Thus, 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 pulling up the precipitate P together with the glass ribbon GR from the molten metal 28, 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 therefore the precipitate P recovered from the molten metal 28 in the recovery step S05 can be reduced. Therefore, an increase in the number of steps in the recovery step S05 can be suppressed, and therefore an increase in the time from the stop of the forming step S01 to the resumption of the forming step S01 can be suppressed. This can suppress a decrease in the productivity of the glass ribbon GR and the plate glass.

[0047] In addition, in this embodiment, in the first cleaning step S04, the bottom surface 20c is cleaned while transferring the molten glass G supplied onto the molten metal 28, so that when the first cleaning step S04 is started, it is not necessary to perform an operation of stopping the supply of the molten glass G onto the molten metal 28. Furthermore, when the forming step S01 is resumed after the first cleaning step S04 is completed, it is not necessary to perform an operation of resuming the supply of the molten glass G onto the molten metal 28. As a result, the forming step S01, the first cleaning step S04, and the forming step S01, which is resumed after the first cleaning step S04 is completed, can be continuously performed, so that 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 resumption of the forming step S01 can be suppressed from increasing. Therefore, it is possible to suppress a decrease in the productivity of the glass ribbon GR and the plate glass.

[0048] 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 may be melted in a melting furnace as a glass material and reused as molten glass G. In addition, when the size and number of defects in the glass ribbon GR formed in the first cleaning step S04 are better than a predetermined size and number, a plate glass formed from the glass ribbon GR may be used as a product.

[0049] <Second embodiment> 7 is a cross-sectional view showing a float glass manufacturing apparatus 110 of the second embodiment. In the following description, the same components as those of the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted. The float glass manufacturing apparatus 110 of this embodiment includes a float bath 20, a molten metal 28, a roof 30, a lift-out roll 41, a transport roll 42, and a vibration device 150.

[0050] The vibration device 150 is a device that applies vibration to the float bath 20. In this embodiment, the float glass manufacturing apparatus 110 includes a plurality of vibration devices 150. Each vibration device 150 is attached to a surface facing the lower side (-Z side) of the bottom wall portion 20a of the float bath 20. As a result, the vibration device 150 applies vibration to at least the bottom wall portion 20a of the float bath 20. The vibration device 150 may be attached to the side wall portion 20b of the float bath 20. In this embodiment, each vibration device 150 is arranged at intervals along the transfer direction (X-axis direction). As a result, it is possible to reduce unevenness in the vibration applied to the bottom wall portion 20a, so that the precipitate P attached to the bottom wall portion 20a over the entire bottom wall portion 20a can be removed. Note that each vibration device 150 may be arranged at intervals along the transfer direction and the width direction (Y-axis direction). In this case, it is possible to more suitably reduce unevenness in the vibration applied to the bottom wall portion 20a. Other configurations of the float glass manufacturing apparatus 110 of the present embodiment are the same as other configurations of the float glass manufacturing apparatus 10 of the above-mentioned first embodiment.

[0051] Next, a float glass manufacturing method Mg for forming a glass ribbon GR by the float glass manufacturing apparatus 110 of this embodiment will be described. As shown in Fig. 8, the float glass manufacturing method Mg of this embodiment includes a forming step S01, an inspection step S02, a first cleaning step S04, a second cleaning step S041 in which vibration is applied to the bottom wall portion 20a by the vibration 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 this 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.

[0052] The second cleaning step S041 is a step of applying vibration to the bottom wall portion 20a by the vibration device 150 to clean the bottom surface 20c. As described above, when vibration is applied to the bottom wall portion 20a, the deposit P attached to the bottom surface 20c can be removed from the bottom surface 20c. This allows the bottom surface 20c to be cleaned by the vibration device 150. As described above, in the first cleaning step S04, the bottom surface 20c is rubbed with the rectangular parallelepiped contact portion 53 to clean the bottom surface 20c. Therefore, in the first cleaning step S04, it is difficult to remove the deposit P attached inside the fine holes of the bottom surface 20c. In contrast, in the second cleaning step S041, the deposit P is removed by vibration applied to the bottom wall portion 20a, so that the deposit P attached inside the fine holes of the bottom surface 20c can be easily removed. Note that the glass ribbon GR to be the product is not formed in the second cleaning step S041.

[0053] In the second cleaning step S041, similarly to the above-mentioned first cleaning step S04, the bottom surface 20c is cleaned by the vibration device 150 while transferring the molten glass G and the glass ribbon GR supplied to the molten metal 28. Thus, a part of the precipitates P removed from the bottom surface 20c adheres to the molten glass G and the glass ribbon GR, and is pulled up together with the glass ribbon GR from the molten metal 28 and removed from the molten metal 28. Another part of the precipitates 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.

[0054] In the recovery step S05 of the present embodiment, among the precipitates P removed from the bottom surface 20c in the first cleaning step S04 and the second cleaning step S041, the precipitates P that are not pulled up from the molten metal 28 together with the glass ribbon GR and float on the surface of the molten metal 28 are recovered from the molten metal 28. As shown in Fig. 8, when the recovery step S05 is completed, the forming step S01 is resumed to form the glass ribbon GR.

[0055] According to this embodiment, the float glass manufacturing apparatus 110 includes a vibration device 150 that applies vibration to at least the bottom wall portion 20a of the float bath 20. Thus, as described above, by applying vibration to the bottom wall portion 20a, the precipitates attached to the bottom surface 20c can be removed. Also, as described above, in the second cleaning step S041, the precipitates P attached inside the small holes in the bottom surface 20c can be removed. This makes it possible to more suitably prevent the precipitates P from peeling off from the bottom surface 20c and adhering to the molten glass G and the glass ribbon GR transported on the molten metal 28 in the forming step S01. Therefore, it is possible to more suitably prevent the occurrence of defects in the glass ribbon GR formed in the forming step S01, thereby further increasing the yield of the sheet glass.

[0056] According to this embodiment, the float glass manufacturing method Mg includes a second cleaning step S041 in which a vibration is applied to the bottom wall portion 20a by a vibration applying device 150 capable of applying vibration to the float bath 20 to clean the bottom surface 20c. Therefore, the bottom surface 20c can be cleaned in both the first cleaning step S04 and the second cleaning step S041. Also, as described above, in the second cleaning step S041, the precipitates P attached to the inside of the small holes in the bottom surface 20c can be easily removed. Therefore, the deposition of the precipitates P on the molten glass G and the glass ribbon GR transported on the molten metal 28 can be more suitably suppressed, and the yield of the sheet glass can be further increased.

[0057] In the present embodiment, in the second cleaning step S041, the bottom surface 20c is cleaned while the molten glass G supplied onto the molten metal 28 is transferred. Thus, similar to the above-described first cleaning step S04, a part of the precipitate P removed from the bottom surface 20c in the second cleaning step S041 can be pulled up together with the glass ribbon GR from the molten metal 28 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, and an increase in the number of steps in the recovery step S05 can be suppressed. This can suppress a decrease in the productivity of the glass ribbon GR and the plate glass.

[0058] 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 prevent an increase in the time from when the forming step S01 is stopped until when the forming step S01 is resumed. This makes it possible to suitably prevent a decrease in the productivity of the glass ribbon GR and the plate glass.

[0059] Although the embodiments of the present invention have been described above, the configurations and their combinations in the embodiments are merely examples, and the configurations may be added, omitted, substituted, or otherwise modified without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0060] The material constituting the shaft portion and the connection portion of the cleaning member is not limited to that of the present embodiment, and may be, for example, ceramic or a material containing carbon fiber like the contact portion. In addition, when the material constituting the shaft portion and the connection portion is the same material as the material constituting the contact portion, the cleaning member may be integrally molded. In addition, the shape of the contact portion may be other shapes such as a disk shape.

[0061] The configuration of the float bath is not limited to that of this embodiment, and for example, the float bath may have other shapes, such as a circular shape or an elliptical shape, when viewed in the vertical direction.

[0062] Furthermore, the first cleaning step and the second cleaning step may be performed by stopping the supply of the molten glass G onto the molten metal. This makes it possible to prevent a glass ribbon having many defects from being formed in the first cleaning step and the second cleaning step, thereby reducing the amount of glass ribbon to be discarded. [Explanation of symbols]

[0063] Reference Signs List 10,110...float glass manufacturing apparatus, 20...float bath, 20a...bottom wall portion, 20b...side wall portion, 20c...bottom surface, 25...opening portion, 28...molten metal, 50...cleaning member, 51...shaft portion, 53...contact portion, 150...vibration device, Mg...float glass manufacturing method, G...molten glass, GR...glass ribbon

Claims

1. A float glass manufacturing apparatus for forming molten glass supplied onto molten metal into a glass ribbon on the molten metal, comprising: a float bath for storing the molten metal; A cleaning member having a rod-shaped shaft portion and a contact portion provided at a tip of the shaft portion; Equipped with the float bath has a bottom wall portion extending in a direction perpendicular to a vertical direction, and a side wall portion extending vertically upward from a periphery of the bottom wall portion and having an opening through which the shaft portion is inserted, the cleaning member is movable along a bottom surface of the bottom wall portion facing upward in the vertical direction with the contact portion in contact with the bottom surface.

2. The float glass manufacturing apparatus according to claim 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 from the vertical direction.

3. 3. The float glass manufacturing apparatus according to claim 1, wherein a portion of said bottom wall portion having said bottom surface is made of brick, said shaft portion is made of metal, and said contact portion is made of a material containing carbon fiber.

4. 2. The float glass manufacturing apparatus according to claim 1, further comprising a vibration device that applies vibration to at least the bottom wall portion of the float bath.

5. A float glass manufacturing method for forming a glass ribbon using a float glass manufacturing apparatus including a float bath that stores molten metal, has a bottom wall portion extending in a direction perpendicular to a vertical direction, and a side wall portion extending vertically upward from a periphery of the bottom wall portion and having an opening, forming the molten glass supplied onto the molten metal into the glass ribbon while transferring the molten glass; cleaning a bottom surface of the bottom wall portion facing upward in the vertical direction using a cleaning member; Including, The cleaning member is A rod-shaped shaft portion that is passed through the opening; A contact portion provided at a tip of the shaft portion; having The method for manufacturing float glass, wherein cleaning the bottom surface includes moving the contact portion along the bottom surface while the contact portion is in contact with the bottom surface to clean the bottom surface.

6. 6. The float glass manufacturing method according to claim 5, wherein cleaning the bottom surface includes cleaning the bottom surface with the contact portion while transferring the molten glass supplied onto the molten metal.

7. 7. The method for producing float glass according to claim 5, further comprising the step of: applying vibration to the bottom wall portion by a vibration applying device capable of applying vibration to the float bath, thereby cleaning the bottom surface.

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