JP5162725B2 - Glass plate manufacturing method and glass plate manufacturing apparatus - Google Patents

Description

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

  Conventionally, a glass plate is used for a display part of a flat panel display such as a liquid crystal display. The glass plate is produced by forming molten glass into a sheet-like sheet glass. Sheet glass is melted in a melting tank to form molten glass, and the molten glass is poured into a molding apparatus through a clarification tank that removes bubbles, a stirring tank that makes the composition distribution uniform, and the like. Molded into glass.

  Generally, platinum or a platinum alloy is used for an apparatus or piping through which molten glass melted in a melting tank flows. This is to prevent the molten glass from being contaminated by melting the materials constituting the apparatus and piping, and to adjust the temperature of the molten glass flowing inside by flowing electricity to the apparatus and piping itself. It is.

  Here, for example, in the manufacturing process of a glass plate for a flat panel display, since the temperature of the molten glass is as high as about 1000 ° C. to 1700 ° C., thermal expansion is taken into consideration for the piping and apparatus for conveying the molten glass. There is a need to. For example, in Patent Document 1 (Japanese Patent No. 449830), in order to suppress damage due to thermal expansion of a platinum or platinum alloy pipe during operation, the outer wall and the inner wall of the pipe through which molten glass flows bulge in the radial direction. The bulging part to be formed is formed in a spiral shape in the peripheral part.

  By the way, piping which conveys a molten glass is divided | segmented into plurality in many cases, as disclosed by patent document 1 (patent 4498390 gazette). This is because, if the pipe is not divided into a plurality of parts, it becomes difficult to absorb the elongation due to the thermal expansion that occurs when the pipe or the device rises to the operating temperature. That is, because the elongation due to thermal expansion cannot be absorbed, there is a risk that the piping and the apparatus may be deformed or damaged. For this reason, in patent document 1, in the state which heated up piping and a device to predetermined temperature (in a high temperature state), by connecting a plurality of divided piping and devices by welding etc., the pipe and devices after connection are connected. It is trying to reduce the amount of expansion due to expansion and suppress deformation of piping and equipment.

  Moreover, it is necessary to raise the temperature of the piping, apparatus, and peripheral members for conveying the molten glass to the vicinity of the temperature at the time of operation before the operation.

  This is because if the temperature of the pipe or device is not sufficiently high, the temperature of the molten glass flowing through the pipe or device is lowered, and the molten glass may solidify in the pipe or device and may not flow.

  Moreover, it is because it is thought that when high temperature molten glass is poured into piping and an apparatus of a normal temperature state, thermal expansion according to the temperature difference will arise in these and peripheral members. That is, in such a case, it is considered that thermal expansion and thermal distortion occur in the piping, apparatus, and peripheral members for conveying the molten glass. And it is because it is thought that the deformation | transformation and damage by the said thermal expansion and a thermal strain arise.

  However, in a state where the temperature has been raised to a predetermined temperature (that is, in a high temperature state), it is difficult for an operator to bring a plurality of pipes into a state during operation by performing welding or the like. For this reason, welding or the like cannot be performed with accuracy, and a problem that molten glass leaks from the welded portion may occur. In addition, the strength of the welded region is inevitably lower than the strength of the non-welded region.

  In addition, although the temperature of the pipe is raised in advance, it is actually difficult to raise the temperature to the temperature at the time of operation in consideration of the workability of an operator who performs welding or the like. Therefore, even if the temperature of the pipe is raised to a predetermined temperature in advance in order to suppress deformation and damage due to thermal expansion, after the pipe is connected and brought into the operating state, the temperature is further increased to the operating temperature. Become. For this reason, thermal expansion of the piping still occurs, and there is a concern that the piping may be deformed or damaged.

  In recent years, along with the increase in the size of flat panel displays, the glass plates used therefor also have a tendency to increase in size. As the glass plate to be manufactured becomes larger, the molding apparatus becomes larger, so in order to maintain productivity, it is necessary to increase the amount of molten glass that flows into the molding apparatus in one day. In addition, if the amount of the molten glass that flows into the molding apparatus is increased in one day, the piping and the apparatus through which the molten glass flows tend to increase in size. Here, when the size of the pipe or the apparatus is increased, there is a problem that the amount of expansion when the temperature is raised increases, and the damage or deformation of the pipe becomes remarkable.

In recent years, the demand for defects due to bubbles in glass plates used in electrical products such as flat panel displays has become stricter, and it has become necessary to reduce the number of bubbles in glass plates using fining agents. ing.
Furthermore, in recent years, due to the problem of environmental burden, it is required to apply metal oxides such as tin oxide and iron oxide instead of highly toxic As ₂ O ₃ although a high clarification effect can be obtained as a clarifier. Here, in order to function tin oxide and iron oxide as a refining agent, it is necessary to further increase the temperature of the molten glass in comparison with the As ₂ O _3. More specifically, the temperature at which tin oxide begins to function as a fining agent is higher than As ₂ O ₃ . That is, in the production of a glass plate containing tin oxide or the like as a fining agent, the temperature of the fining tank or the surrounding pipes needs to be higher than when As ₂ O ₃ is contained as a fining agent. For this reason, there is a problem that the amount of expansion of the clarification tank and the surrounding piping increases, and the damage and deformation of the piping become remarkable.

  Thus, in recent years, the expansion amount of platinum or platinum alloy pipes and devices tends to increase. Therefore, the method described in Patent Document 1 sufficiently suppresses damage and deformation of the pipes. Have difficulty.

  Then, the subject of this invention is providing the manufacturing method and glass plate manufacturing apparatus of a glass plate which can suppress the deformation | transformation and damage of piping through which a molten glass flows by simpler operation | work.

  The manufacturing method of the glass plate which concerns on this invention is equipped with a melt | dissolution process, a conveyance process, a supply process, a shaping | molding process, and a cutting process. In the melting step, the glass raw material is melted to obtain molten glass. In the transporting process, the molten glass is transported by flowing it into a platinum group element or platinum group element alloy pipe. In the supplying step, molten glass is supplied to the molding apparatus. In the forming step, the molten glass supplied in the supplying step is formed into a sheet glass. In the cutting step, the sheet glass is cut to form a glass plate. The piping for transporting the molten glass in the transporting process has a first tube and a second tube, and a covering member. The first pipe and the second pipe are arranged apart from each other, and a thermal expansion allowable space that allows thermal expansion during operation is formed therebetween. The covering member covers the end portions of the first tube and the second tube and the thermal expansion allowable space, and is movable in the axial direction with respect to the first tube and the second tube. The conveying process includes a viscosity increasing process. In the viscosity increasing step, when the molten glass is transported from the first tube to the second tube through the thermal expansion allowable space, the amount of heat transferred from the molten glass to the outside of the covering member is determined from the molten glass to the first tube. The viscosity of the molten glass is increased by increasing the amount of heat transferred to the outside of the first tube and the second tube.

  Here, for example, the covering member is not limited to one covering the entire circumference of the first tube and the second tube.

  Here, the pipe through which the molten glass flows can be brought into a state during operation with a simple operation.

  Further, in the viscosity increasing step, the viscosity of a part of the molten glass is increased between the end of the first tube on the second tube side and the cover member, and the end of the second tube on the first tube side and the cover member It is preferable to increase the viscosity of a part of the molten glass between.

  Further, in the viscosity increasing step, log η = 4 to 13 for the viscosity η of the molten glass between the end of the first tube on the second tube side and the covering member, and the end of the second tube on the first tube side It is preferable that log η = 4 to 13 with respect to the viscosity η of the molten glass with the covering member.

  Moreover, it is preferable that the cover member in a conveyance process has a cover part and at least 1 flange part. The cover covers the first tube, the second tube, and the thermal expansion allowable space. The flange portion extends outward from the cover portion.

  Further, at least one opening is formed in the cover part, the flange part extends outward from the opening part forming part that forms the opening part, and a space between the flange parts is formed by the flange part. The viscosity η of the molten glass in the space between the flange portions is preferably set to log η = 6 or more.

The glass plate is free of As ₂ O ₃ as a glass raw material is dissolved substantially in the dissolution step is preferably a glass plate for a liquid crystal display.

  The temperature at which log η = 2.5 in the viscosity η of the molten glass used for manufacturing the glass plate is preferably 1500 ° C. to 1750 ° C.

  It is preferable that the strain point of the glass used for manufacture of the said glass plate is 655 degreeC or more.

The glass raw material preferably contains tin oxide as a fining agent.

The glass plate contains SiO ₂ and Al ₂ O ₃ , the total content of the SiO ₂ and the Al ₂ O ₃ in the glass plate is 70% by mass or more, and the alkali metal oxide of the glass plate The content is preferably 2% by mass or less.

It is preferable that the said glass plate is an alkali free glass which does not contain an alkali metal oxide substantially.

The glass plate, a SiO ₂ 50-70 _mass%, the B 2 _{O 3} 0 to 15 wt%, the _Al 2 _{O 3} 5 to 25 wt%, 0-10 wt% of MgO, 0 to 20 mass CaO %, SrO 0 to 20% by mass, BaO 0 to 10% by mass, RO 5 to 20% by mass (where R is a component contained in the glass plate selected from Mg, Ca, Sr and Ba, It is preferable to contain at least one kind.

  In the supplying step, it is preferable to supply 6 t or more of the molten glass per day to the molding apparatus.

  The glass plate manufacturing apparatus which concerns on this invention is equipped with a dissolution tank, a shaping | molding apparatus, and piping. The melting tank melts the glass raw material to form molten glass. The forming apparatus forms molten glass into sheet glass. The piping is made between a platinum group element or a platinum group element alloy, which is disposed between the melting tank and the molding apparatus and in which molten glass flows. The pipe includes a first pipe and a second pipe that are spaced apart from each other, and a covering member that is movable in the axial direction with respect to the first pipe and the second pipe. A thermal expansion allowable space that allows thermal expansion during operation is formed between the first pipe and the second pipe. The covering member covers the end portions of the first tube and the second tube and the thermal expansion allowable space, and is movable in the axial direction with respect to the first tube and the second tube. Further, when the pipe conveys the molten glass from the first pipe to the second pipe through the thermal expansion allowable space, the pipe transfers the amount of heat transfer from the molten glass to the outside of the covering member from the molten glass to the first pipe and the second pipe. The viscosity of the molten glass is increased by increasing the amount of heat transfer to the outside of the tube.

  In addition, piping should just be arrange | positioned, for example between a dissolution tank and a shaping | molding apparatus, and does not need to be directly connected with a dissolution tank and a shaping | molding apparatus. Here, the pipe through which the molten glass flows can be brought into a state during operation with a simple operation.

  In the present invention, deformation and breakage of the piping through which the molten glass flows can be suppressed with a simpler operation.

The flowchart for demonstrating the manufacturing method of the glass plate which concerns on this embodiment. The schematic diagram of a glass plate manufacturing apparatus. The schematic exploded perspective view of 1st piping. The schematic perspective view of a covering member and a pressing member. The figure which shows the state in which the 1st member and the 2nd member were normally attached to the 1st pipe and the 2nd pipe, ie, the 1st piping. Sectional drawing at the time of cut | disconnecting the 1st piping shown in FIG. 5 in the direction which passes along 1st space and is perpendicular | vertical to a 1st direction. The schematic perspective view of the 1st piping concerning modification 1A. The schematic perspective view of the 1st piping concerning modification 1C.

  Hereinafter, the manufacturing method of the glass plate of one Embodiment of this invention is demonstrated, referring drawings.

(1) Outline of Glass Plate Manufacturing Method FIG. 1 is a partial flowchart of the glass plate manufacturing method according to the present embodiment. Hereinafter, the manufacturing method of a glass plate is demonstrated using FIG.

  As shown in FIG. 1, the glass plate is manufactured through various processes including a melting process ST1, a clarification process ST2, a homogenization process ST3, a supply process ST4, and a molding process ST5. Hereinafter, these steps will be described in detail.

In the melting step ST1, the glass raw material is melted. Glass raw material _is a composition such as SiO 2, _Al 2 _{O 3.} The glass raw material thrown into the furnace is heated and melted. The completely melted glass raw material becomes molten glass, and flows out to the accommodating portion where the clarification step ST2, which is the next step, is performed.

  In the clarification step ST2, the molten glass is clarified. Specifically, the gas component contained in the molten glass is discharged out of the molten glass as bubbles, or is dissolved in the molten glass. The clarified molten glass flows out to the accommodating portion where the next step, the homogenization step ST3, is performed.

  In the homogenization step ST3, the molten glass is homogenized. Specifically, the molten glass is homogenized by stirring. In this step, the temperature of the molten glass that has been clarified is adjusted. The homogenized molten glass flows out to the accommodating part where the next process, the supply process ST4, is performed.

  In supply process ST4, it supplies to the apparatus which shape | molds molten glass. In this step, the molten glass is cooled to a temperature suitable for starting the formation of the sheet-like sheet glass.

  In the forming step ST5, the molten glass is formed into a sheet glass. The formed sheet glass plate is cut in a cutting process using a cutting device to become a glass plate. As a molding method, a downdraw method, a float method, a rollout method, or the like can be used. In the present embodiment, it is preferable to use the over-down draw method of the down-draw method. The overdown draw method will be described later. The cut glass plate is then subjected to processing such as cutting, grinding / polishing, and cleaning and inspection.

(2) Outline of Glass Plate Manufacturing Apparatus 100 FIG. 2 shows an example of the glass plate manufacturing apparatus 100 according to this embodiment.

  As shown in FIG. 2, the glass plate manufacturing apparatus 100 includes a dissolution tank 101, a clarification tank 102, a stirring tank 103, a forming apparatus 104, a first pipe 105 (corresponding to a pipe), and a second pipe 106. Have

  The melting tank 101 is a tank for melting a glass raw material. The dissolution tank 101 is made of a refractory material such as brick, and has a liquid tank at the bottom. For example, the dissolution tank 101 is heated by a burner that is appropriately disposed on the wall surface. And a radiant heat generate | occur | produces because a wall surface is heated with a burner, and a glass raw material is heated and melt | dissolved by the said radiant heat. The liquid tank is provided with an electric heating device for generating Joule heat from the glass raw material itself by energizing the glass raw material. An electrode of an electric heating device is provided on the wall surface of the liquid tank so as to be in contact with the glass raw material. In the dissolution tank 101, the dissolution step ST1 is performed. In the above description, the glass raw material heating means having the burner and the electrode has been described as an example. However, the present invention is not limited to this, and any glass material may be provided. The method for melting the glass raw material is not particularly limited to this, and the glass raw material can be melted using other heating means.

  The clarification tank 102 is a tank for removing bubbles from the molten glass melted in the melting tank 101. By further heating the molten glass fed from the melting tank 101 in the clarification tank 102, defoaming of bubbles in the molten glass is promoted. In the clarification tank 102, a clarification step ST2 is performed. More specifically, the temperature of the molten glass in the fining tank 102 is equal to or higher than the temperature at which the fining agent releases a gas component (for example, oxygen if tin oxide), and the gas component is added to the existing bubbles in the molten glass. Is increased to a temperature at which the bubble diameter of the existing bubbles expands. Further, the temperature of the molten glass is raised to a temperature higher than a temperature at which a viscosity (200 to 800 poise) at which bubbles in the molten glass become a sufficient flying speed is realized. Thereby, the bubble in molten glass is discharge | released outside from the inside of molten glass. Thereafter, the temperature of the molten glass is lowered, and bubbles remaining in the molten glass are absorbed by the fining agent. Thereby, the bubbles in the molten glass can be eliminated and clarification is performed. The disappearance of bubbles may be performed in the clarification tank 102, the first pipe 105, and the stirring tank 103.

  The agitation tank 103 has an agitation device including a container for containing molten glass, a rotation shaft, and an agitation blade attached to the rotation shaft. As a container, a rotating shaft, and a stirring blade, although the thing made from platinum group elements, such as platinum, or the alloy of a platinum group element, for example can be used, it is not restricted to this. When the rotating shaft is rotated by driving of a driving unit (not shown) such as a motor, the stirring blade attached to the rotating shaft stirs the molten glass. In the stirring vessel 103, the homogenization step ST3 is performed.

  It should be noted that the glass raw material is charged into the dissolution tank 101 and the melting process ST1, the clarification process ST2, and the homogenization process ST3 are performed (that is, the dissolution tank 101, the clarification tank 102, the first pipe 105, the stirring). Here, the process in which the molten glass flows into the tank 103 and the second pipe 106 is referred to as a conveyance process.

  The molding apparatus 104 includes a molded body in which a groove is formed in an upper portion and a longitudinal section has a wedge shape. The groove is formed along the longitudinal direction of the molded body. The molded body is a refractory material. In addition, the molding device 104 includes a roller that extends downward from the molten glass that overflows the molded body and joins at the lower end of the molded body, a cooling device that gradually cools the glass, and the like. In the molding apparatus 104, a molding step ST5 is performed. In the supply process ST4, 6 t or more of molten glass per day is supplied to the molding apparatus 104.

The first pipe 105 and the second pipe 106 are pipes made of a platinum group element (platinum, iridium, osmium, palladium, rhodium, ruthenium, etc.) or a platinum group element alloy. The first pipe 105 is a pipe that connects the clarification tank 102 and the stirring tank 103. The second pipe 106 is a pipe that connects the stirring tank 103 and the molding apparatus 104.
The clarification tank 102, the first pipe 105, the stirring tank 103, and the second pipe 106 made of a platinum group element or a platinum group element alloy are heated by passing a current directly through the platinum group element or the platinum group element alloy. It is preferable. By flowing a current directly through the platinum group element or platinum group element alloy and heating it, the temperature of the molten glass can be increased efficiently. For this reason, even when tin oxide is used as a fining agent, the temperature of the molten glass can be easily raised to a temperature at which tin oxide effectively functions as a fining agent (for example, to 1620 ° C. or higher).
In addition, the heating method of the clarification tank 102, the 1st piping 105, the stirring tank 103, and the 2nd piping 106 is not limited to the said method, For example, the clarification tank 102, the 1st piping 105, the stirring tank 103, the 2nd piping 106 It is also possible to install a heating device such as an electric heater around and heat by the heating device.

(3) Detailed Configuration of First Pipe 105 FIG. 3 is a schematic exploded perspective view of the first pipe 105.

  As shown in FIG. 3, the first pipe 105 includes a first pipe 111, a second pipe 112, and a covering member 113.

  The first tube 111 is a hollow tube made of a platinum group element or a platinum group element alloy, and is connected to the clarification tank 102. The first pipe 111 protrudes in the first direction in which molten glass flows from the clarification tank 102 to the stirring tank 103.

  The second tube 112 is a hollow tube made of a platinum group element or a platinum group element alloy, and is connected to the stirring vessel 103. The second pipe 112 protrudes from the stirring tank 103 in a second direction that is opposite to the first direction. For the first pipe 111 and the second pipe 112, for example, pipes having a diameter of 10 to 1000 mm (preferably 70 mm to 200 m) are used. In addition, the diameter of the 1st pipe | tube 111 and the 2nd pipe | tube 112 is not restricted to this.

  Between the 1st pipe | tube 111 and the 2nd pipe | tube 112, 1st space S1 (equivalent to thermal expansion allowable space) exists. That is, the first pipe 111 and the second pipe 112 are installed apart from each other. Here, in this embodiment, the 1st pipe | tube in a separated state based on the heat dissipation amount of molten glass (calculated based on the amount of glass temperature fall, flow rate, specific heat, and heat dissipation conditions) The length between the end faces of 111 and the second pipe 112 that are not opposite to each other (that is, the end face on the second direction side of the first pipe 111 and the end face on the first direction side of the second pipe 112) is determined.

  The ends of the first tube 111 and the second tube 112 that are not opposite to each other (that is, the end of the first tube 111 on the second direction side and the end of the second tube 112 on the first direction side) A plurality of layers of heat insulating materials are arranged.

  The covering member 113 includes an end portion on the second tube 112 side of the first tube 111 and an end portion on the first tube 111 side of the second tube 112 (that is, the end portion on the first direction side of the first tube 111 and the second end portion). The end of the tube 112 on the second direction side) and the first space S1 are covered. That is, the covering member 113 has a role of connecting the first tube 111 and the second tube 112 that are in a separated state. As a result, the molten glass flowing inside the first tube 111 can flow into the second tube 112. Further, the covering member 113 is movable in the axial direction (first direction and second direction) with respect to the first tube 111 and the second tube 112.

  The covering member 113 includes a first member 113a and a second member 113b.

  The first member 113 a is made of a platinum group element or a platinum group element alloy, and covers the upper portions of the first tube 111 and the second tube 112. The first member 113a covers the first space S1 from above.

  The first member 113a includes a cover portion 213a and flange portions 213b and 213c.

  The cover portion 213a is a portion that covers the first tube 111, the second tube 112, and the first space S1. The cover part 213a draws an arc having a substantially semicircular cross-sectional shape cut perpendicularly to the surface in the longitudinal direction so that the first tube 111 and the second tube 112 can be covered. The flange portions 213b and 213c extend in the horizontal direction from the both ends of the cover portion 213a to the outside in the radial direction (specifically, the direction orthogonal to the horizontal plane horizontal in the first direction). Here, the flange portions 213b and 213c extend in the horizontal direction from the cover portion 213a, but are not limited to those extending in the horizontal direction. The width W1 (see FIG. 4) of each of the flange portions 213b and 213c is preferably 20 mm or less (however, a natural number excluding 0), for example.

  The reason why the width W1 of the flange portions 213b and 213c is preferably 20 mm or less is because the flange portions 213b and 213c have a role as cooling fins. That is, if the width W1 of the flange portions 213b and 213c becomes too large (for example, becomes larger than the width of the first lower surface 414 of the first pressing member 114a described later), the first pipe 111 and the second pipe are unnecessarily necessary. This is to avoid the situation because the temperature of 112 and thus the temperature of the molten glass flowing inside the first tube 111 and the second tube 112 are cooled. Next, since the covering member 113 is made of a platinum group element or a platinum group element alloy which is relatively expensive compared to other metals, it is for the purpose of cost reduction.

  The second member 113 b is made of a platinum group element or a platinum group element alloy, and covers the lower portions of the first tube 111 and the second tube 112. The second member 113b covers the first space S1 from below. In the present embodiment, the second member 113b has a symmetrical shape with the longitudinal axis of the first member 113a as an axis, and includes a cover portion 214a and flange portions 214b and 214c.

  In addition, since the cover part 214a and the flange parts 214b and 214c have the structure similar to the cover part 213a and the flange parts 213b and 213c of the 1st member 113a, description is abbreviate | omitted. In addition, the 1st member 113a and the 2nd member 113b are not restricted to a symmetrical shape about those longitudinal axes.

  The first member 113a is supported by a first pressing member 114a described later. The second member 113b is supported by a support member (for example, a jack) (not shown) via a second pressing member 114b described later.

  Here, gaps S2 and S3 (see FIG. 5) exist in the circumferential direction between the first pipe 111 and the second pipe 112 and the first member 113a and the second member 113b. That is, the inner diameters of the first member 113a and the second member 113b are larger than the outer diameters of the first tube 111 and the second tube 112, respectively. Here, the presence of the gap S <b> 2 and the gap S <b> 3 makes it easier for the covering member 113 to move in the axial direction of the first pipe 111 and the second pipe 112.

  The difference between the inner diameter of the first member 113a and the second member 113b and the outer diameter of the first pipe 111 and the second pipe 112 is preferably 5 mm or less (however, a natural number excluding 0). This is because molten glass can be prevented from leaking outside.

  Between the flange portions 213b and 213c of the first member 113a and the flange portions 214b and 214c of the second member 113b, flange-to-flange spaces S4 (see FIG. 5) are formed, respectively.

  That is, the first member 113a and the second member 113b are respectively formed of molten glass flowing through the first tube 111 and the second tube 112 between both ends of the first member 113a and both ends of the second member 113b. It arrange | positions so that the opening part 313 (refer FIG.5 and FIG.6, in FIG. 5, only the opening part of the paper surface front side) which can flow in into the space S4 between flange parts is formed. Therefore, both end portions of the cover portions 213a and 214a function as an opening portion forming portion for forming the opening portion 313. The vertical height of the space S4 between the flange portions (specifically, the distance between the lower surface of the flange portions 213b and 213c and the upper surface of the flange portions 214b and 214c) is 5 mm or less (however, a natural number excluding 0). It is preferable. This is because molten glass can be prevented from leaking outside.

  The first member 113a and the second member 113b are pressed by the pressing member 114. The pressing member 114 will be described below.

(4) Detailed Configuration of Pressing Member 114 FIG. 4 is a schematic perspective view of the covering member 113 and the pressing member 114.

  As shown in FIG. 4, the pressing member 114 includes a first pressing member 114 a that presses the first member 113 a from above and a second pressing member 114 b that presses the second member 113 b from below. The first member 113a and the second member 113b are pressed in a direction approaching each other by the first pressing member 114a and the second pressing member 114b, respectively.

  The 1st pressing member 114a and the 2nd pressing member 114b are block-shaped members excellent in fire resistance and heat resistance, for example, are bricks etc. The first pressing member 114a and the second pressing member 114b have a higher thermal conductivity than the heat insulating material disposed at the end portions of the first tube 111 and the second tube 112 that are not opposed to each other (preferably Is 1.2-20 W / m · K). Each of the first pressing member 114a and the second pressing member 114b is formed with spaces S5 and S6 that are opened in a substantially semicircular shape along the longitudinal direction on one end in the thickness direction.

  The inner diameters of the first pressing member 114 a and the second pressing member 114 b are the same as the outer diameter of the covering member 113. Therefore, in the state where the first pressing member 114a is attached to the first member 113a (the state during operation), the inner periphery of the arc portion 314 that forms the space S5 of the first pressing member 114a covers the first member 113a. It contacts the outer periphery of the part 213a. Further, in the state where the second pressing member 114b is attached to the second member 113b (operation state), the inner periphery of the arc portion 315 forming the space S6 of the second pressing member 114b covers the second member 113b. It contacts the outer periphery of the part 214a. Further, in a state where the first pressing member 114a is attached to the first member 113a (operation state), the first lower surface 414 excluding the arc portion 314 of the first pressing member 114a is the flange portion 213b of the first member 113a. , 213c is in contact with the upper surface. Moreover, the 2nd lower surface 415 except the circular arc part 315 of the 2nd pressing member 114b contacts the lower surface of the flange parts 214b and 214c of the 2nd member 113b. Here, the widths of the first lower surface 414 and the second lower surface 415 of the first pressing member 114a and the second pressing member 114b are respectively set to the flange portions 213b and 213c of the first member 113a and the flange portions 214b of the second member 113b. The width is preferably the same as 214c.

  The first pressing member 114a is supported and fixed by a support member (for example, a screw) (not shown). The second pressing member 114b is supported and fixed by a support member (for example, a jack) not shown.

  The first pressing member 114a and the second pressing member 114b are formed by, for example, brick cutting or casting.

(5) Method for Attaching First Pipe 105 and Holding Member 114 Hereinafter, a method for attaching the first pipe 105 and the holding member 114 will be described.

  First, as shown in FIG. 3, the first direction end of the first pipe 111 connected to the clarification tank 102 and the second direction end of the second pipe 112 connected to the stirring tank 103 The first member 113a and the second member 113b are attached so as to cover the first space S1 between the first tube 111 and the second tube 112. Specifically, the first member 113a is attached from above the first tube 111 and the second tube 112, and the second member 113b is attached from below the first tube and the second tube 112. 5 shows a state in which the first member 113a and the second member 113b are properly attached to the first tube 111 and the second tube 112. FIG.

  Next, as shown in FIG. 4, the pressing member 114 is attached to the covering member 113. At this time, the first pressing member 114a is attached so that the inner periphery thereof is in contact with the outer periphery of the first member 113a and the inner periphery of the second pressing member 114b is in contact with the outer periphery of the second member 113b.

  After this, the clarification tank 102, the stirring tank 103, the molding apparatus 104, the first pipe 105, the second pipe 106, and the like are set to a predetermined temperature (for example, 1500, which is the temperature during operation) by a temperature control device disposed in the vicinity. Temperature). Then start operation. In the state of operation, the glass raw material is melted in the melting tank 101, and the molten glass flows through the first pipe 105 toward the molding apparatus 104 (that is, melts into the first pipe 111 and the second pipe 112). Glass flows).

  In addition, when a molten glass is conveyed from the 1st pipe | tube 111 to the 2nd pipe | tube 112 via 1st space S1, the viscosity of a part of molten glass rises locally (viscosity increase process). On the downstream side of the clarification tank 102 (on the downstream side of the clarification tank 102 of the flow of the molten glass flowing from the melting tank 101 toward the molding device 104), the temperature of the molten glass is gradually lowered, so that the molten glass is melted toward the downstream. The viscosity of the glass increases gradually. The viscosity increasing step referred to in the present embodiment is not to gradually decrease the molten glass temperature as described above, but locally and rapidly in the gap S2, the gap S3, and further in the first space S1, the glass viscosity. Is raised so that log η = 4 or more. In this step, the amount of heat transferred from the molten glass to the outside of the covering member 113 is increased compared to the amount of heat transferred to the outside during the conveyance of the molten glass through the first tube 111 and the second tube 112, thereby melting the molten glass. The viscosity of the glass is increased rapidly. The amount of heat transfer is the amount of heat transfer to the outside per unit length along the flowing direction of the molten glass.

  Specifically, in the viscosity increasing step, a part of the molten glass in the space formed between the end portion of the first tube 111 on the second tube 112 side and the covering member 113 in the gap S2 and the gap S3. The viscosity of is increased. At this time, log η = 4 to 13 for the viscosity η of the molten glass.

  Further, in the viscosity increasing step, in the gap S2 and the gap S3, in the space formed between the end portion of the second pipe 112 on the first pipe 111 side and the covering member 113, the viscosity of a part of the molten glass is reduced. Be raised. At this time, log η = 4 to 13 for the viscosity η of the molten glass.

  In the viscosity increasing step, the viscosity of the molten glass in the vicinity of the flange portions 213b, 213c, 214b, and 214c (specifically, the molten glass that has entered the space S4 between the flange portions) is not so soft as to easily leak to the outside. On the other hand, the viscosity is such that viscous flow occurs.

  As a method for measuring the viscosity of the molten glass, a known method can be applied. For example, a ball pulling method, a penetration method, a beam bending method, or the like can be used as appropriate according to the viscosity of the molten glass.

(6) Example of glass plate manufactured using this invention The example of the glass plate manufactured using this invention is demonstrated below. Note that the present invention is not limited to the following form.

  Although the thickness of a glass plate is not specifically limited, 0.1-1.1 mm, 0.2 mm-0.7 mm, 0.2 mm-0.5 mm may be sufficient.

  Moreover, the magnitude | size of a glass plate is although it does not specifically limit, For example, the length of the width direction may be 500 mm-3500 mm, and the length of a longitudinal direction may be 500 mm-3500 mm. In addition, when a glass plate enlarges, in order to maintain productivity, it is necessary to increase the quantity (henceforth MG quantity) of molten glass. That is, the size of the pipes (first pipe 105 and second pipe 106) and apparatuses (dissolution tank 101, clarification tank 102, stirring tank 103, and molding apparatus 104) tend to increase as the glass plate becomes larger. is there. For this reason, the amount of thermal expansion of these pipes and devices increases, and the problem of damage to the pipes and devices becomes significant.

  Therefore, when the length in the width direction of the glass is 2000 mm or more, the effect of the present invention is particularly remarkable. Moreover, the effect of the present invention becomes more remarkable as the length in the width direction of the glass is 2500 mm or more and 3000 mm or more.

  The type of the glass plate is not particularly limited, but may be borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, soda lime glass, alkali silicate glass, alkali aluminosilicate glass, or alkali alumino gelate glass.

  Moreover, the use of the glass plate is not particularly limited, but it may be used for a glass plate for a flat panel display (liquid crystal display, plasma display, etc.), a panel for solar cell, and a cover glass. The cover glass is, for example, tempered glass obtained by chemically or physically strengthening a glass plate in order to protect a display screen or housing of an AV device (such as a portable terminal).

Moreover, as a glass plate for flat panel displays (a liquid crystal display, a plasma display, etc.), the glass plate is a mass% display and includes the following components. The indication in the following parentheses is a preferable content of each component, and the latter half is preferable.
_{SiO 2: 50~70% (55~65%} , 57~64%, 58~62%),
_{Al 2 O 3: 5~25% (} 10~20%, 12~18%, 15~18%),
_{B 2 O 3: 0~15% (} 5~15%, 6~13%, 7~12%).

At this time, the following composition may be included as an optional component.
MgO: 0 to 10% (lower limit is 0.01%, lower limit is 0.5%, upper limit is 5%, upper limit is 4%, upper limit is 2%),
CaO: 0 to 20% (lower limit is 1%, lower limit is 3%, lower limit is 4%, upper limit is 9%, upper limit is 8%, upper limit is 7%, upper limit is 6%),
SrO: 0 to 20% (lower limit is 0.5%, lower limit is 3%, upper limit is 9%, upper limit is 8%, upper limit is 7%, upper limit is 6%),
BaO: 0 to 10% (upper limit is 8%, upper limit is 3%, upper limit is 1%, upper limit is 0.2%),
ZrO ₂ : 0 to 10% (0 to 5%, 0 to 4%, 0 to 1%, 0 to 0.1%).

Further, in particular, the glass plate is represented by the following mass%,
SiO _2: 50~70%,
B ₂ O _3: 5~18%,
Al ₂ O _3: 10~25%,
MgO: 0 to 10%,
CaO: 0 to 20%,
SrO: 0 to 20%,
BaO: 0 to 10%,
RO: 5 to 20% (provided that R is at least one selected from Mg, Ca, Sr and Ba),
It is preferable to contain. further,
R ′ ₂ O: more than 0.2% and 2.0% or less (provided that R ′ is a component contained in a glass plate selected from Li, Na and K, and is at least one kind). It is preferable.
The glass having a glass composition at this time is referred to as alkali trace glass, and the glass plate having this glass composition is referred to as alkali trace glass. The alkali trace glass may have a content of R ′ ₂ O exceeding 0% and not more than 2.0%. In the present embodiment, an alkali trace glass having a content of R ′ ₂ O of more than 0% and not more than 2.0% can be used, but preferably more than 0.2% and not more than 2.0%. Further, R ′ ₂ O may be substantially 0.0%. The glass having a glass composition at this time is called non-alkali glass, and the glass plate having this glass composition is called an alkali-free glass plate.
Moreover, it is preferable that 0.05 to 1.5% of a fining agent is included in total and As ₂ O ₃ and PbO are not substantially included. Moreover, it is more preferable that the content of iron oxide in the glass is 0.01 to 0.2%.

In addition, the glass plate is represented by the following mass%,
SiO _2: 50~70%,
B ₂ O _3: 0~15%,
Al ₂ O _3: 5~25%,
MgO: 0 to 10%,
CaO: 0 to 20%,
SrO: 0 to 20%,
BaO: 0 to 10%,
RO: 5 to 20% (provided that R is a component contained in the glass plate selected from Mg, Ca, Sr and Ba, and is at least one type),
It is preferable to contain.
Furthermore, in the case where the glass plate to be manufactured is a glass plate used for a flat panel display (such as a liquid crystal display or an organic EL display) using a TFT (Thin Film Transistor), from the viewpoint of suppressing the destruction of the TFT, The glass plate to be produced is preferably an alkali-free glass plate. On the other hand, in order to improve the meltability of the glass as compared with the alkali-free glass, the glass plate produced in the present embodiment may be a glass plate containing a trace amount of alkali that dares to contain a trace amount of an alkali component. When the alkali metal oxide is eluted from the glass plate, the TFT may be destroyed. Therefore, an alkali-free glass plate or a glass plate containing a trace amount of alkali is suitably used for a flat panel display using the TFT.
In the case of a glass plate containing a trace amount of alkali, the alkali metal oxide R ′ ₂ O is more than 0.05% and less than 2.0% in terms of mass%, more preferably R ′ ₂ O is more than 0.1% and It is preferable to contain 0% or less (provided that R ′ is a component contained in a glass plate selected from Li, Na and K, and is at least one kind). Moreover, it is preferable that 0.05 to 1.5% of a refining agent is contained in total (expressed by mass%) and AS ₂ O ₃ and PbO are not substantially contained. Moreover, it is more preferable that the content of iron oxide in the glass composition is 0.01% to 0.2% in terms of mass%.
Since flat panel displays have been required to be light in recent years, in the case of a glass plate for flat panel displays, it is preferable that SrO + BaO is 0 to 10% in terms of mass%. Moreover, considering the environmental load in addition to the weight reduction, BaO is more preferably 0 to 2% in terms of mass%.

Here, the glass plate for flat panel display has a large content of SiO ₂ and Al ₂ O ₃ as described above, and a content of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O). A small amount of alkali-containing glass plate or non-alkali glass plate is preferably used as described above. However, the meltability of the alkali trace-containing glass plate or the alkali-free glass plate is low. Specifically, the temperature at which log η = 2.5 in the viscosity η of the molten glass is 1500 ° C. to 1750 ° C., which is higher than that of the alkali-containing glass. The molten glass having such a viscosity needs to raise the temperature of the clarification tank 102 and the surrounding piping as compared with the case of producing a glass plate using alkali-containing glass. For this reason, there is a problem that the expansion amount of the clarification tank 102 and the surrounding pipes increases, and the breakage and deformation of the pipes become remarkable.
More specifically, in the clarification step, the speed at which the bubbles in the molten glass float is affected by the viscosity of the molten glass, and the foam floating speed increases as the viscosity of the molten glass decreases. For this reason, in order to clarify the alkali-free glass or the alkali-containing glass, the viscosity of the molten glass is set to 200 to 800 poise which is a viscosity suitable for fining. As described above, the melting property of the alkali trace glass or alkali-free glass plate is low, so in the case of alkali-free glass or alkali trace glass, the temperature of the molten glass needs to be further increased compared to the alkali-containing glass. There is. More specifically, in the production of an alkali-free glass plate or a glass plate containing a trace amount of alkali, in the refining step, the temperature of the molten glass is higher than the temperature at which tin oxide begins to function as a refining agent (for example, 1620 ° C. or more, more preferably 1650 ° C. or higher, more preferably 1680 ° C. or higher). That is, the temperature of the clarification tank 102 provided on the downstream side of the dissolution tank 101 is increased to, for example, 1640 ° C. or higher, and thereby the molten glass is increased to, for example, 1620 ° C. or higher, more preferably 1650 ° C. Heat to above.
Moreover, the molten glass in which the glass raw material is melted in the melting tank 101 needs to be kept at a high temperature (for example, 1200 to 1600 ° C.) until it is supplied to the molding apparatus 104 after the fining tank 102. For this reason, in the production of an alkali-free glass plate or a glass plate containing a trace amount of alkali, an apparatus (specifically, a melting tank, a clarification tank, an agitation tank, and a molding apparatus) through which high-temperature molten glass flows is used. It is assumed that the expansion amount of the first pipe and the second pipe) increases. Therefore, these devices and piping are easily damaged. Accordingly, a glass plate for a flat panel display having a high content of SiO ₂ or Al ₂ O _{3 and} a low content of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) or not contained at all is manufactured. In doing so, the effect of the present invention becomes remarkable. For example, the content of SiO ₂ + Al ₂ O ₃ is 70% by mass or more (eg, 70% by mass to 95% by mass), and the content of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) is 2 This invention is suitable for the glass plate which is the mass% or less (for example, 0-2 mass% or less). The content of SiO ₂ + Al ₂ O ₃ is 70% by mass or more (for example, 70% by mass to 95% by mass), and the content of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) is 1 The present invention is more suitable for a glass plate having a mass% or less (for example, 0 to 1 mass%). Further, the content of SiO ₂ + Al ₂ O ₃ is 75% by mass or more (for example, 75% by mass to 95% by mass), and the content of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) is 0. The present invention is more suitable for a glass plate of 0.5 mass% or less (0 to 0.5 mass%).
As described above, the molten glass having a viscosity η = 2.5 at a viscosity η of 1500 to 1750 ° C. is obtained by, for example, the temperature of the molten glass in order to obtain a sufficient bubble rising speed in the fining tank 102. For example, it is necessary to set the temperature to 1620 ° C. or higher. Therefore, the amount of expansion of the platinum group element or platinum group element alloy constituting the fining tank 102 is increased in the molten glass as compared with the conventional alkali-containing glass. That is, in a molten glass having a temperature at which log η = 2.5 is 1500 to 1750 ° C., the expansion of the platinum group element or the platinum group element alloy is likely to increase. For this reason, the said molten glass is suitable for the manufacturing method of this embodiment. Regarding the viscosity of the glass, the temperature at which log η = 2.5 is preferably 1530 ° C. to 1750 ° C., more preferably 1550 ° C. to 1750 ° C., and even more preferably 1570 ° C. to 1750 ° C.

Moreover, as a glass plate applied to a cover glass or a glass plate for solar cells, for example, a glass plate is represented by mass% and includes the following components. The indication in the following parentheses is the preferred content of each component.
_{SiO 2: 50~70% (55~65%} , 57~64%, 57~62%),
_{Al 2 O 3: 5~20% (} 9~18%, 12~17%),
_{Na 2 O: 6~30% (7~20} %, 8~18%, 10~15%).

At this time, the following composition may be included as an optional component.
Li ₂ O: 0 to 8% (0 to 6%, 0 to 2%, 0 to 0.6%, 0 to 0.4%, 0 to 0.2%),
B ₂ O ₃ : 0 to 5% (0 to 2%, 0 to 1%, 0 to 0.8%),
K ₂ O: 0 to 10% (lower limit is 1%, lower limit is 2%, upper limit is 6%, upper limit is 5%, upper limit is 4%),
MgO: 0 to 10% (lower limit is 1%, lower limit is 2%, lower limit is 3%, lower limit is 4%, upper limit is 9%, upper limit is 8%, upper limit is 7%),
CaO: 0 to 20% (lower limit is 0.1%, lower limit is 1%, lower limit is 2%, upper limit is 10%, upper limit is 5%, upper limit is 4%, upper limit is 3%),
_{ZrO 2: 0~10% (0~5%} , 0~4%, 0~1%, 0~0.1%).
In particular, as a cover glass and a glass plate for solar cells that are chemically strengthened,
SiO _2: 50~70%,
Al ₂ O _3: 5~20%,
Na ₂ O: 6-30%,
K ₂ O: 0~10%,
MgO: 0 to 10%,
CaO: 0 to 20%,
It is preferable to contain.

  In the glass of the glass plate, a clarifying agent can be added as a component for defoaming bubbles in the glass. The fining agent is not particularly limited as long as it has a small environmental burden and excellent glass fining properties. For example, from a metal oxide such as tin oxide, iron oxide, cerium oxide, terbium oxide, molybdenum oxide and tungsten oxide. There may be mentioned at least one selected.

As ₂ O ₃ , Sb ₂ O ₃ and PbO are substances having an effect of clarifying the glass by causing a reaction with valence fluctuation in the molten glass, but As ₂ O ₃ and PbO have an environmental burden. Since it is a large substance, the glass plate of this embodiment does not substantially contain As ₂ O ₃ and PbO in the glass. In the present embodiment, “substantially not containing As ₂ O ₃ and PbO” means that the content is less than 0.01% by mass and is not intentionally contained except for impurities.

Here, for example, in order to allow a metal oxide such as tin oxide or iron oxide to function as a fining agent, it is necessary to raise the temperature of the molten glass more than As ₂ O ₃ . Therefore, since it is necessary to also raise the temperature of the clarification tank 102 and its surrounding piping, the amount of expansion of the clarification tank and its surrounding piping increases as compared with the case where As ₂ O ₃ is applied as a clarifier. The problem of deformation becomes significant. Therefore, when using metal oxides such as tin oxide, iron oxide, cerium oxide, terbium oxide, molybdenum oxide and tungsten oxide instead of As ₂ O ₃ and PbO as the fining agent, the effect of the present invention is more remarkable. Become.
Here, when a glass plate is used for the glass substrate for flat panel displays, the requirement for bubble defects is particularly severe. For this reason, as a clarifier, it is preferable to contain at least tin oxide having a particularly high clarification effect among metal oxides such as tin oxide, iron oxide, cerium oxide, terpium oxide, molybdenum oxide, and tungsten oxide.
When clarification is performed using tin oxide, in the clarification tank 102, for example, the molten glass needs to be 1600 ° C. or higher (for example, 1620 ° C. or higher). This is because the tin oxide does not release oxygen violently unless the temperature is 1600 ° C. or higher (for example, 1620 ° C. or higher). In order to heat the molten glass to 1600 ° C. or higher (for example, 1620 ° C. or higher), a current is passed directly to a platinum group element or a platinum group element alloy constituting the clarification tank 102 or a pipe provided downstream of the melting tank 101. . Thereby, the temperature of piping or the clarification tank 102 is raised to 1600 degreeC or more (for example, 1620 degreeC or more), and the molten glass in piping or the clarification tank 102 is heated to the temperature suitable for clarification. That is, in the manufacture of a glass plate that uses tin oxide as a fining agent, the temperature of the fining tank 102 and the surrounding piping is higher than that of a glass plate that uses As ₂ O ₃ as a fining agent. Therefore, there is a problem that the amount of expansion of the clarification tank 102 and the surrounding pipes increases, and the damage and deformation of the pipes become remarkable. Therefore, the effect of the present invention becomes more prominent in the case of glass that is clarified using tin oxide.

  In addition, when this invention is applied to the 1st piping 105 which connects the clarification tank 102 and the stirring tank 103 which need to raise temperature especially like this embodiment, the effect of the said damage suppression becomes remarkable. .

Furthermore, flat panel displays require display elements that use P-Si (low temperature polysilicon) TFTs and oxide semiconductors instead of α-Si (amorphous silicon) TFTs in order to achieve higher definition in recent years. It has been. Here, in the process of forming the P-Si (low-temperature polysilicon) TFT and the oxide semiconductor, a heat treatment at a higher temperature is performed than in the process of forming the α-Si TFT. Therefore, a glass plate on which P-Si (low-temperature polysilicon) / TFT or an oxide semiconductor is formed is required to have a small thermal contraction rate. In order to reduce the heat shrinkage rate, it is preferable to increase the strain point of the glass. However, a glass having a high strain point tends to have a high viscosity at high temperature (high temperature viscosity). Therefore, in the clarification tank 102, in order to make the molten glass have a viscosity suitable for clarification, it is necessary to further raise the temperature of the molten glass. That is, the production method of the present invention is suitable for producing a glass plate for a flat panel display using P-Si • TFT, because the temperature of the molten glass is increased as compared with the conventional case. For the same reason, the present invention is suitable for manufacturing a glass plate for a flat panel display using an oxide semiconductor.
For example, the present invention is suitable for producing a glass plate using a molten glass having a strain point of 655 ° C. or higher and a temperature at which log η = 2 in the viscosity η is 1600 ° C. or higher. In particular, the present invention is suitable for the production of a glass plate having a strain point of 675 ° C. or higher, which is more suitable for the formation of P-Si (low-temperature polysilicon) TFT or oxide semiconductor, and the production of a glass plate having a strain point of 680 ° C. or higher. And more suitable for the production of a glass plate having a strain point of 690 ° C. or higher. In addition, as a composition of a glass plate whose strain point is 675 degreeC or more, the glass plate is mass% display and the glass plate containing the following components is illustrated, for example.
SiO _2: 52~78%,
Al ₂ O ₃ : 3 to 25%,
B ₂ O ₃ : _{3 to} 15%,
RO (however, RO is the total amount of components contained in MgO, CaO, SrO, and BaO): 3 to 20%,
Including
The mass ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ is in the range of 7 to 20,
Is a glass plate.
Furthermore, in order to further increase the strain point, the mass ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ is preferably 7.5 or more. Furthermore, in order to raise a strain point, it is preferable to make (beta) -OH value into 0.1-0.3 mm. On the other hand, R ₂ O (where R ₂ O is the total amount of components contained in Li ₂ O, Na ₂ O and K ₂ O so that current does not flow through the melting tank 102 instead of molten glass during melting) ) Is preferably included in an amount of 0.01 to 0.8% by mass to reduce the specific resistance of the molten glass. Alternatively, it is also preferred to include Fe ₂ O ₃ 0.01 to 1.0 wt% in order to lower the specific resistance of the molten glass. Further, CaO / RO is preferably 0.65 or more in order to prevent the devitrification temperature from increasing while realizing a high strain point. By setting the devitrification temperature to 1250 ° C. or lower, the overflow downdraw method can be applied. When applied to mobile devices such as mobile communication terminals, the total content of SrO and BaO is preferably 0 to less than 2% by mass from the viewpoint of weight reduction.

(7) Features (7-1)
Conventionally, a glass plate is used for a display part of a flat panel display such as a liquid crystal display. The glass plate is formed by processing a sheet-like sheet glass. Sheet glass is molded by melting the prepared raw material in a melting tank to become molten glass, and the molten glass is poured into a molding apparatus through a clarification tank that removes bubbles, a stirring tank that makes the composition distribution uniform, and the like. Is done.

  In general, a device made of platinum or a platinum alloy is used for an apparatus or a pipe through which melted molten glass flows. This is for the purpose of preventing the molten glass from being contaminated by melting the materials constituting the apparatus and piping, and the purpose of adjusting the temperature of the molten glass flowing inside by flowing electricity to the apparatus and the piping itself, etc. There is.

  Here, the molten glass which flows through piping etc. at the time of operation is about 1000-1700 degreeC and high temperature. Further, the viscosity η of the molten glass at this time is log η = 5 or less. In particular, the viscosity η of the molten glass flowing through a pipe connecting the clarification tank and the stirring tank is log η = 4 or less. For this reason, a temperature difference arises at the time of installation of equipment and at the time of operation. Therefore, it is considered that the piping and the apparatus that convey the molten glass undergo thermal expansion. However, since the position of the melting tank for melting the glass raw material and the molding apparatus for molding the sheet glass are determined in advance, the melting tank and the molding apparatus are moved in accordance with the thermal expansion of the platinum or platinum alloy apparatus or piping. It is difficult.

  Therefore, unless the thermal expansion of the platinum or platinum alloy device or piping can be escaped well, these and the molding device may be deformed and the predetermined performance may not be sufficiently exhibited. Considering the further adverse situation, there is concern that some of these will be damaged.

  Therefore, it is an important issue regarding the thermal expansion of platinum or platinum alloy devices and pipes.

  Therefore, for example, in Patent Document 1 (Patent No. 4498390), in order to suppress damage due to thermal expansion of platinum or platinum alloy pipes during operation, the outer and inner walls of the pipe through which the molten glass flows are radially arranged. The bulging part which bulges is formed in the surrounding part at the spiral.

  By the way, the piping for conveying the molten glass is often divided into a plurality of pieces as disclosed in Patent Document 1 (Japanese Patent No. 4498390).

  This is because, if the pipe is not divided into a plurality of parts, it becomes difficult to absorb the elongation due to the thermal expansion that occurs when the pipe or the device rises to the operating temperature. That is, because the elongation due to thermal expansion cannot be absorbed, there is a risk that the piping and the apparatus may be deformed or damaged.

  Moreover, it is necessary to raise the temperature of the piping, apparatus, and peripheral members for conveying the molten glass to the vicinity of the temperature at the time of operation before the operation.

  This is because if the temperature of the pipe or device is not sufficiently high, the temperature of the molten glass flowing through the pipe or device is lowered, and the molten glass may solidify in the pipe or device and may not flow.

  Moreover, it is because it is thought that when high temperature molten glass is poured into piping and an apparatus of a normal temperature state, thermal expansion according to the temperature difference will arise in these and peripheral members. That is, in such a case, it is considered that thermal expansion and thermal distortion occur in the piping, apparatus, and peripheral members for conveying the molten glass, and it is considered that deformation and damage are caused by the thermal expansion and thermal distortion. It is.

  In the invention disclosed in Patent Document 1 (Japanese Patent No. 4498390), the temperature of the pipes for transporting the molten glass is increased to a predetermined temperature before being connected by welding or the like to the operating state. Conceivable.

  However, in a high temperature state, it is a terrible work to bring a pipe divided into a plurality of parts into an operating state by performing welding or the like.

  Specifically, first, it is generally considered that the space where the pipe is arranged is often narrow. Therefore, it is considered that it is difficult for an operator to perform welding work of a plurality of pipes in a high temperature and narrow space. For this reason, there exists a possibility that the efficiency and precision of welding operation may fall.

  Next, as described above, the pipe is heated to a predetermined temperature in advance before being connected and brought into a state of operation. However, even if the temperature of the pipe is raised in advance, the upper limit temperature is 1000 ° C. to 1200 ° C. in consideration of the workability of the worker, and the temperature is raised to the operating temperature (for example, 1500 ° C.) Have difficulty.

  Therefore, even if the temperature of the pipe is raised to a predetermined temperature in advance in order to suppress deformation and breakage due to thermal expansion, the temperature is further raised to the temperature during operation after the pipe is brought into the operating state. For this reason, thermal expansion of the piping still occurs, and there is a concern that the piping may be deformed or damaged. More specifically, it is considered that deformation or breakage of the pipe occurs due to stress concentration in a welding region where a plurality of pipes are connected, or in a place where the temperature is higher and the strength is weakened.

  In recent years, with the increase in size of flat panel displays, the glass plates used therefor also have a tendency to increase in size. Further, since the molding apparatus becomes larger as the glass plate to be manufactured becomes larger, in order to maintain productivity, it is necessary to increase the amount of MG that flows into the molding apparatus per day. In addition, when the amount of MG flowing into the molding apparatus is increased in one day, the piping and the apparatus through which the molten glass flows tend to increase in size. Here, when the size of the pipe or the apparatus is increased, there is a problem that the amount of expansion when the temperature is raised increases, and the damage or deformation of the pipe becomes remarkable.

Further, in recent years, due to the problem of environmental burden, it is required to use metal oxides such as tin oxide and iron oxide instead of highly toxic As ₂ O ₃ as a clarifying agent. Here, in order to function tin oxide and iron oxide as a refining agent, it is necessary to further increase the temperature of the molten glass in comparison with the As ₂ O _3. That is, since it is necessary to increase the temperature of the clarification tank and the surrounding pipes, the amount of expansion of the clarification tank and the surrounding pipes increases, and there is a problem that breakage and deformation of the pipes become remarkable.

  Thus, in recent years, the expansion amount of platinum or platinum alloy pipes and devices tends to increase. Therefore, the method described in Patent Document 1 sufficiently suppresses damage and deformation of the pipes. Have difficulty.

  Therefore, in this embodiment, even if the pipe through which the molten glass flows is still divided, that is, even if the pipes are separated like the first pipe 111 and the second pipe 112, The first pipe 111 and the second pipe 112 can be connected by covering the pipes 111 and 112 and the first space S1 between the pipes 111 and 112 with the covering member 113. That is, the pipe through which the molten glass flows, that is, the first pipe 105 can be brought into an operating state by a simple operation.

  In the present embodiment, both the first tube 111 and the second tube 112 are fixed at one end but not fixed at the other end. Further, the covering member 113 is made of the same member as the first tube 111 and the second tube 112. Therefore, in consideration of the thermal expansion of the pipe, it is not necessary to bring the pipe up to a predetermined temperature before the operation state. That is, since the first pipe 105 can be brought into an operating state at room temperature, the work efficiency is improved and the work accuracy is also improved.

  In general, it is said that the welded portions such as a plurality of members tend to have low strength. However, in the present embodiment, the pipes 111 and 112 and the first space S1 between the pipes 111 and 112 are formed. The first tube 111 and the second tube 112 can be indirectly connected by covering with the covering member 113. Therefore, it can be said that it is preferable also from the viewpoint of strength.

  Furthermore, in patent document 1 (patent 4498390), one end of piping is connected to the stirring apparatus, and the other end is connected to another piping. That is, both ends of the pipe are in a fixed state. Therefore, thermal expansion occurs when high-temperature molten glass flows inside, so even if the bulging portion that bulges radially in the outer wall and inner wall of the pipe is formed in a spiral shape in the peripheral portion, it is still in the longitudinal direction. There is a concern that compressive stress is applied.

  On the other hand, in the present embodiment, as described above, the first tube 111 and the second tube 112 are both in a state where one end is fixed but the other end is not fixed. A first space S1 exists between the first tube 111 and the second tube 112. Therefore, in the operating state, even if high-temperature molten glass flows through the first pipe 105 and thermal expansion occurs in the direction in which the first pipe 111 and the second pipe 112 approach each other, a compressive stress in the longitudinal direction is generated. Hateful. That is, since the first pipe 111 and the second pipe 112 are free at one end, the first pipe 111 and the second pipe 112 themselves may be damaged even if contraction or expansion occurs due to a change in temperature during operation. This is reduced. In other words, the first space S1 functions as a thermal expansion allowable space that allows thermal expansion of the first pipe 111 and the second pipe 112 during operation. Therefore, deformation and breakage of the first pipe 105 through which the molten glass flows can be suppressed.

  In addition, this inventor manufactured the glass plate of the longitudinal direction 1870mm, the width direction 2200mm, and thickness 0.7mm using the glass plate manufacturing method and the glass plate manufacturing apparatus 100 as described in this embodiment. In addition, the content rate (mass%) of each component contained in the molten glass at this time is as follows.

SiO ₂ 60%
Al ₂ O ₃ 19.5%
B ₂ O ₃ 10%
CaO 5%
SrO 5%
SnO ₂ 0.5%

  At this time, even if the glass plate was continuously manufactured, the glass plate manufacturing apparatus 100 including the first pipe 105 was not deformed or damaged. Therefore, the present invention has proved useful for suppressing deformation and breakage of the glass plate manufacturing apparatus 100.

(7-2)
In the present embodiment, the covering member 113 that covers the end portions of the first tube 111 and the second tube 112 and the first space S1 between the first tube 111 and the second tube 112 has a plurality of members, that is, It has the 1st member 113a and the 2nd member 113b. Thereby, the attaching operation | work to the 1st pipe | tube 111 and the 2nd pipe | tube 112 of the cover member 113 becomes easy.

(7-3)
In the present embodiment, the first member 113a and the second member 113b include cover portions 213a and 214a and flange portions 213b, 213c, 214b, and 214c, respectively. In this embodiment, the flange portion 213b of the first member 113a and the flange portion 213b of the second member 113b, and the flange portion 213c of the first member 113a and the flange portion 214c of the second member 113b, respectively. A space S4 between the flange portions is formed.

  For example, even if molten glass flowing from the first tube 111 to the second tube 112 via the first space S1 leaks to the outside of the first tube 111 and the second tube 112 and leaks to the covering member 113 side, The viscosity of the molten glass is increased in the inter-flange space S4. That is, the flange portions 213b, 213c, 214b, and 214c are provided so that the molten glass leaking from the gap S2 or the gap S3 is likely to increase in viscosity. In addition, the molten glass whose viscosity has increased plays a role in suppressing the molten glass flowing inside the first tube 111 and the second tube 112 from leaking outside the first tube 111 and the second tube 112. In addition, the molten glass having an increased viscosity also serves to bond the first member 113a and the second member 113b. Thereby, it becomes easy to adhere | attach the 1st member 113a and the 2nd member 113b. By making the molten glass have a function as an adhesive using the increase in viscosity of the molten glass, the first member 113a and the second member 113b need not be welded. Therefore, working efficiency is improved.

  Here, the reason why the viscosity of the molten glass in the inter-flange space S4 is likely to increase in viscosity is that the inter-flange space S4 is not covered with a heat insulating material and is easily affected by outside air. That is, the temperature is unlikely to rise compared to the inside of the first tube 111 and the second tube 112. Further, since the amount of heat transferred from the molten glass flowing inside the first tube 111 and the second tube 112 is also small, the temperature is unlikely to rise even compared to the gap S2 and the gap S3. In other words, in the first pipe 105 of the present embodiment, in the inter-flange space S4, the temperature of the molten glass flows through the first pipe 111 and the second pipe 112, and the temperature of the molten glass in the gaps S2 and S3. It becomes the structure which can adjust heat | fever so that it may become lower. Therefore, as described above, the molten glass that has entered the space S4 between the flanges is not so soft that it easily leaks to the outside, and has a viscosity that causes viscous flow.

(7-4)
In the present embodiment, in an operating state where the molten glass flows through the first tube 111 and the second tube 112, gaps S2 and S3 exist between the covering member 113 and the first tube 111 and the second tube 112. .

  The gaps S <b> 2 and S <b> 3 are not covered with the heat insulating material and are easily affected by the outside air, and therefore, the temperature is less likely to rise than inside the first pipe 111 and the second pipe 112. In other words, the first pipe 105 of the present embodiment heats the gaps S2 and S3 so that the temperature of the molten glass is lower than the temperature of the molten glass flowing inside the first pipe 111 and the second pipe 112. It can be adjusted. That is, in the transporting process of transporting the molten glass from the first pipe 111 to the second pipe 112 via the first space S1, the viscosity of the molten glass is increased (viscosity increasing process). Accordingly, the molten glass that has entered the gaps S2 and S3 (that is, the molten glass that has entered between the end of the first tube 111 on the second tube 112 side and the covering member 113 and the first tube 111 of the second tube 112). A portion of the molten glass that has entered between the end portion on the side and the covering member 113 is not so soft as to be easily leaked to the outside, whereas a viscosity that causes viscous flow (specifically, log η = 4˜ 13). Therefore, for example, even if the temperature of various members including the first pipe 111 and the second pipe 112 is changed during operation and the first pipe 111 and the second pipe 112 expand / contract (that is, stress is generated). Even if this is the case, the covering member 113 is movable in the axial direction of the first tube 111 and the second tube 112 for the above reasons, so that the molten glass that has entered the gaps S2 and S3 can absorb the stress.

  From the viewpoint of suppressing the molten glass from leaking outside from the first tube 111 and the second tube 112, log η = 6 to 13, log η = 8 for the viscosity η of the molten glass that has entered the gap S2 and the gap S3. It is preferably ~ 13. In the present embodiment, since the covering member 113 has the flange portions 213b, 213c, 214b, and 214c, the viscosity may be lower than the above. For example, log η = 2 to 10, log η = 3 to 8, and log η = 3 to 5 may be used for the viscosity η of the molten glass entering the gaps S2 and S3. In this case, it can suppress that the temperature of the molten glass inside the 1st pipe | tube 111 and the 2nd pipe | tube 112 falls too much, and a crystal | crystallization precipitates in a molten glass. Therefore, the quality of the glass plate can be further maintained.

(7-5)
In the present embodiment, the covering member 113 is pressed by the pressing member 114. Specifically, the first member 113a and the second member 113b are pressed in a direction approaching each other by the first pressing member 114a and the second pressing member 114b, respectively.

  Here, the first member 113a and the second member 113b can be fixed by a simple method by pressing the covering member 113 with the pressing member 114. Therefore, working efficiency is improved.

(7-6)
Generally, it is preferable to lower the temperature of the molten glass from the clarification tank to the stirring tank. And in the vicinity of piping which connects a clarification tank and a stirring tank, the temperature adjustment apparatus for adjusting the temperature of a molten glass indirectly is often used.

  On the other hand, in this embodiment, a member having a higher thermal conductivity than the heat insulating material disposed at the end portions of the first tube 111 and the second tube 112 that are not opposed to each other is used for the pressing member 114. Since the pressing member 114 is exposed to the outside air, it is easier to radiate heat than the heat insulating material. Therefore, the pressing member 114 has not only a role of pressing the covering member 113 but also a role of cooling the molten glass through the covering member 113.

  This eliminates the need to use a temperature adjustment device, so that cost and energy can be suppressed, or even if a temperature adjustment device is used, the pressing member 114 also has the function of the temperature adjustment device. Contributes to cost and energy saving. This effect becomes more prominent as the amount of MG increases. This is because as the amount of MG increases, the amount of heat retained by the molten glass increases, making it difficult to lower the temperature of the molten glass in the first pipe 105.

(7-7)
FIG. 6 is a cross-sectional view of the first pipe 105 shown in FIG. 5 cut in a direction that passes through the first space S1 and is perpendicular to the first direction. In addition, in FIG. 6, illustration is abbreviate | omitted about the molten glass which exists in the inside of the 1st piping 105. FIG.

  Conventionally, the piping through which the molten glass flows is hermetically sealed so that the molten glass does not leak outside the piping. Therefore, problems such as a problem of stress due to deformation due to thermal expansion and difficulty in welding work at a high temperature have been described.

  On the other hand, in the present embodiment, the first pipe 111 and the second pipe 112 can function as the first pipe 105 that conveys the molten glass by covering the covering member 113 in a separated state, and thus has been described above. In addition, the above problems can be reduced.

  Further, in the present embodiment, the molten glass flowing inside the first tube 111 and the second tube 112 is utilized outside the covering member 113 as shown in FIG. Suppressing leakage. That is, even if the molten glass leaks to the outside of the first tube 111 and the second tube 112, it is configured to make use of it.

(7-8)
For the glass plate for flat panel display, glass containing a trace amount of alkali or non-alkali glass is used from the viewpoint of suppressing the destruction of TFT, and tin oxide is used from the viewpoint of reducing environmental burden. For this reason, in at least the clarification process of the production of the glass plate, the clarification of the molten glass is efficiently performed, so that the temperature of the molten glass is adjusted to be higher than the conventional one. In addition, a glass composition having a high strain point is used because a glass plate with a low thermal shrinkage rate is desired to achieve a high-definition flat panel display. At this time, in a glass composition having a high strain point, the viscosity at high temperature (high temperature viscosity) becomes high. Accordingly, even when the thermal shrinkage rate is reduced, the temperature of the molten glass in the refining process is adjusted to be higher than that in the past. Thus, the manufacturing method of the present invention capable of suppressing deformation and breakage of the piping around the clarification tank 102 through which the molten glass flows can efficiently manufacture a glass plate against the high temperature of the molten glass required in the clarification step. Effective in terms.

(8) Modifications While the embodiment of the present invention has been described with reference to the drawings, the specific configuration is not limited to the above-described embodiment, and can be changed without departing from the scope of the invention. .

(8-1) Modification 1A
In the above embodiment, the first pipe 105 has been described. However, the present invention is not limited to this, and can be applied to a place where a platinum group element or platinum group element alloy pipe is used, for example, the second pipe 106. It is.

  That is, if there are a plurality of pipes (such as the first pipe 111 and the second pipe 112) spaced apart from each other (not limited to two, but may be three or more pipes), the plurality of pipes are covered with the covering member. 113 and the holding member 114 can be indirectly connected using a member having the same configuration and function. Thereby, even a pipe longer than the first pipe 105 can be formed.

  For example, FIG. 7 shows a case where three tubes 310, 320, and 330 that are spaced apart from each other are indirectly connected using a covering member 413. The covering member 413 has the same configuration and function as the covering member 113.

(8-2) Modification 1B
In the above embodiment, the first member 113a and the second member 113b have been described as having two flange portions 213b, 213c, 214b, and 214c, respectively, but the number is not limited to two, and at least 1 It suffices to have a flange portion.

  Moreover, in the said embodiment, flange part 213b, 213c, 214b, 214c demonstrated that it extended in the horizontal direction respectively outward from the both ends of cover part 213a, 214a, respectively. However, the positions where the flange portions 213b, 213c, 214b, and 214c are provided are not particularly limited, and may be provided so as to extend outward with respect to the first tube 111 and the second tube 112.

(8-3) Modification 1C
In the above embodiment, the first member 113a and the second member 113b have been described as having the flange portions 213b, 213c, 214b, and 214c. However, the flange portions 213b, 213c, 214b, and 214c are not essential components. Also good.

  For example, instead of providing the flange portions 213b, 213c, 214b, and 214c, the material of the pressing member 114 may be selected from materials having high thermal conductivity and easily cooled, or the first pressing member 114a and the second pressing member. A joint portion with the member 114b may be cooled.

  Moreover, in the said embodiment, the width W1 of the flange parts 213b and 213c demonstrated that 20 mm or less was preferable. Further, the widths of the first lower surface 414 and the second lower surface 415 of the first pressing member 114a and the second pressing member 114b are respectively the flange portions 213b and 213c of the first member 113a and the flange portions 214b and 214c of the second member 113b. It has been described that it is preferable that the width is the same as the width. However, it is not limited to this.

  For example, in consideration of various situations, the width W1 of the flange portions 213b and 213c and the width of the flange portions 214b and 214c may be larger than those in the above embodiment, or may be larger than the widths of the first lower surface 414 and the second lower surface 415. Each may also be enlarged.

  Specifically, for example, in order to reduce the amount of cooling of the molten glass in the first pipe 105, a material having a relatively high heat insulating property is used for the first pressing member 114a and the second pressing member 114b. This is a case where the temperatures of the flange portions 213b and 213c of the first member 113a and the flange portions 214b and 214c of the second member 113b are excessively increased.

  In short, depending on how much heat is radiated by the flange portions 213b, 213c, 214b, 214c, these widths, the material, dimensions, and the like of the pressing member 114 can be changed.

(8-4) Modification 1D
In the above embodiment, it has been described that the flange portion space S4 exists between the first member 113a and the second member 113b. However, the present invention is not limited to this, and the first member 113a and the second member 113b are You may touch. That is, the flange portion space S4 may not be formed. An example of this case is shown in FIG. In this case, for example, if the arc portion of the cover portion 213a of the first member 113a and / or the cover portion 214a of the second member 113b is formed long, the space S4 between the flange portions is not formed while forming the gap S2 and the gap S3. Can be.

  If such a structure is taken, the flange parts 213b and 213c of the 1st member 113a and the flange parts 214b and 214c of the 2nd member 113b will contact. Here, for example, when the weight of the first pressing member 114a is larger than the pressure in the first pipe 105, the first member 113a and the first member 113a disposed above the first pipe 111 and the second pipe 112 are used. The pressing member 114a may not be supported by the support member. In this case, it is possible to further contribute to cost saving and improvement of work efficiency. The first member 113a and the second member 113b can be connected by welding or the like. For example, the strength of the first pipe 105 can be improved by connecting the flange portions 213b and 213c of the first member 113a and the flange portions 214b and 214c of the second member 113b by welding or the like. Here, welding or the like between the first member 113a and the second member 113b can be performed before the temperature of the first pipe 105 is raised, so that work efficiency and work accuracy can be improved. Even in this case, the viscosity of the molten glass flowing outside from the first tube 111 and the second tube 112 tends to increase in the vicinity of the flange portions 213b, 213c, 214b, and 214c.

  Moreover, although the said embodiment demonstrated that the clearance gaps S2 and S3 exist between the covering member 113 and the 1st pipe | tube 111 and the 2nd pipe | tube 112, respectively, it is not restricted to this. For example, only the gap S3 may be formed, or neither of the gaps S2 and S3 may be formed.

  In the former case, the inner diameter of the first member 113a and the outer diameters of the first tube 111 and the second tube 112 are the same. In this case, the first member 113a is attached to the first tube 111 and the second tube 112 so that the inner periphery of the cover portion 213a contacts the outer periphery of the first tube 111 and the second tube 112. Leakage of molten glass to the outside of the first tube 111 and the second tube 112 can be further suppressed.

  In the latter case, the inner circumferences of the first member 113 a and the second member 113 b are in contact with the outer circumferences of the first pipe 111 and the second pipe 112. Although it is necessary to increase the manufacturing accuracy of the first member 113a and the second member 113b and the setting accuracy of each member, the temperature of the molten glass flowing in the first tube 111 and the second tube 112 is high, This is effective when it is desired to minimize cooling in this portion. Further, when the cross-sectional shape of the covering member 113 cut in the direction perpendicular to the first direction approaches a substantially perfect circle, for example, compared to the case where the cross-sectional shape is elliptical, the molten glass is heated uniformly. It becomes easy to conduct.

  In addition, you may take the structure which forms only clearance gap S2.

(8-5) Modification 1E
In the above-described embodiment, the cover member 113 has been described as having the first member 113a and the second member 113b. However, the present invention is not limited to this.

  For example, the covering member 113 may be a single pipe in which a cavity is formed. In this case, for example, the first pipe 111 or the second pipe 112 is first inserted into the pipe, and then, the first pipe 105 is slid to the other pipe 111 or 112 side. Can be formed.

  In the above embodiment, the covering member 113 basically covers almost the entire circumference of the first tube 111 and the second tube 112, but is not limited thereto. For example, it is sufficient that the molten glass flowing inside the first tube 111 has a shape capable of exhibiting a function of flowing inside the second tube 112.

(8-6) Modification 1F
In the above embodiment, the stirring tank 103 and the second pipe 112 are described as being connected, but the present invention is not limited to this. For example, when the second pipe 112 has a flange portion (not shown) at the end on the stirring tank 103 side, the flange portion of the second pipe 112 is joined to the wall surface of the stirring tank 103 by welding or the like. Thus, it may be connected to the stirring tank 103. In addition, the connection method with an apparatus is not specifically limited also regarding between others.

(8-7) Modification 1G
In the above-described embodiment, it has been described that 6 t or more of molten glass is supplied per day in the supply step ST4. However, the present invention is not limited to this and may be 3 t or more.

  Note that as the amount of MG increases (10 t or more, 15 t or more, 20 t or more), a pipe (in the above embodiment, the first pipe 105, the second pipe 106, etc.) or an apparatus (the above-mentioned implementation) that transports the molten glass is used. In the form, the size of the molding apparatus 104 or the like is increased. For this reason, the amount of thermal expansion of these piping and apparatus increases. Therefore, the problem of breakage of these pipes and devices becomes significant. Therefore, if the glass plate manufacturing apparatus 100 and the glass plate manufacturing method according to the present embodiment are used, a more useful effect can be expected in the above case.

(8-8) Modification 1H
In the above embodiment, it has been described that the molten glass that has entered the space S4 between the flanges is not so soft that it easily leaks to the outside, but on the other hand, the viscosity is such that viscous flow occurs.

  For example, the temperature of the molten glass that has entered the inter-flange space S <b> 4 may be lowered until it reaches a viscosity that does not cause viscous flow. For example, it is preferable that the log η = 6 or more with respect to the viscosity η of the molten glass that has entered the space S4 between the flanges because the molten glass can be further suppressed from leaking out of the space S4 between the flanges. More specifically, the viscosity η of the molten glass in the outermost region (region in contact with the outside air) of the inter-flange space S4 is preferably log η = 6 or more. Even if a part of the molten glass leaks into the holding member 114 from the inter-flange space S4, the molten glass is solidified by cooling in the vicinity of the outer portions of the flange portions 213b, 213c, 214b, and 214c. As described above, leakage of molten glass from the inter-flange space S4 can be suppressed. This is because the thermal conductivity of the pressing member 114 is higher than that of the heat insulating material.

(8-9) Modification 1I
In the above embodiment, the cover member 113 has a configuration in which two openings 313 are formed. However, the present invention is not limited to this, and a configuration in which at least one opening 313 is formed is adopted. May be.

  The present invention is applicable to various methods and various apparatuses for manufacturing a glass plate using a pipe through which high-temperature molten glass flows.

DESCRIPTION OF SYMBOLS 100 Glass plate manufacturing apparatus 104 Molding apparatus 105 1st piping (piping)
111 1st pipe | tube 112 2nd pipe | tube 113 Cover member 213a, 214a Cover part 213b, 213c, 214b, 214c Flange part S1 1st space (thermal expansion tolerance space)
S4 Flange space ST1 Dissolution process ST4 Supply process ST5 Molding process

Claims (11)

A melting step of melting glass raw material to form molten glass;
A transporting step for transporting the molten glass by flowing it into a pipe made of a platinum group element or a platinum group element alloy;
Supplying the molten glass to a molding apparatus;
A forming step of forming the molten glass supplied from the supplying step into a sheet glass;
A cutting step of cutting the sheet glass to form a glass plate;
With
The piping for conveying the molten glass in the conveying step is
A first pipe and a second pipe that are spaced apart and in which a thermal expansion allowance space that allows thermal expansion during operation is formed;
A covering member that covers end portions of the first tube and the second tube and the thermal expansion allowable space, and is movable in an axial direction with respect to the first tube and the second tube;
Have
In the transporting step, when the molten glass is transported from the first tube to the second tube through the thermal expansion allowable space, the amount of heat transferred from the molten glass to the outside of the covering member is determined. Including a viscosity increasing step of increasing the viscosity of the molten glass by increasing the amount of heat transferred from the glass to the outside of the first tube and the second tube,
Manufacturing method of glass plate. In the viscosity increasing step, the viscosity of a part of the molten glass is increased between the end portion on the second tube side of the first tube and the covering member, and the first tube side of the second tube is increased. Increasing the viscosity of a portion of the molten glass between the end and the covering member,
The manufacturing method of the glass plate of Claim 1. In the viscosity increasing step, log η = 4 to 13 for the viscosity η of the molten glass between the end of the first tube on the second tube side and the covering member, and the first tube of the second tube Log η = 4 to 13 for the viscosity η of the molten glass between the end on the side and the covering member,
The manufacturing method of the glass plate of Claim 1 or 2. The temperature at which log η = 2.5 in the viscosity η of the molten glass used for the production of the glass plate is 1500 ° C. to 1750 ° C.,
The manufacturing method of the glass plate of any one of Claims 1-3. The strain point of the glass used for manufacturing the glass plate is 655 ° C. or higher.
The manufacturing method of the glass plate of Claim 4. The glass raw material contains tin oxide as a fining agent,
The manufacturing method of the glass plate of any one of Claims 1-5. The glass plate containing SiO ₂ and _Al 2 _{O 3,} the total content of the SiO ₂ and the _Al 2 _{O 3} of the glass plate is 70 mass% or more,
The content of alkali metal oxide in the glass plate is 2% by mass or less.
The manufacturing method of the glass plate of any one of Claims 1-6.   The said glass plate is a manufacturing method of the glass plate of any one of Claims 1-7 whose content rate of an alkali metal oxide exceeds 0.05 mass% and is 2.0 mass% or less. The glass plate is an alkali-free glass substantially free of alkali.
The manufacturing method of the glass plate of any one of Claims 1-7. The glass plate, a SiO ₂ 50-70 _mass%, the B 2 _{O 3} 0 to 15 wt%, the _Al 2 _{O 3} 5 to 25 wt%, 0-10 wt% of MgO, 0 to 20 mass CaO %, SrO 0-20% by mass, BaO 0-10% by mass, RO 5-20% by mass (provided that R is at least one selected from Mg, Ca, Sr and Ba),
The manufacturing method of the glass plate of any one of Claims 1-9. A melting tank for melting glass raw material to form molten glass;
A molding apparatus for molding the molten glass into a sheet glass;
A pipe that is disposed between the melting tank and the molding apparatus and is made of a platinum group element or a platinum group element alloy through which the molten glass flows,
With
The piping is
A first pipe and a second pipe that are spaced apart and in which a thermal expansion allowance space that allows thermal expansion during operation is formed;
A covering member that covers end portions of the first tube and the second tube and the thermal expansion allowable space, and is movable in an axial direction with respect to the first tube and the second tube;
Have
The pipe transfers the amount of heat transferred from the molten glass to the outside of the covering member when the molten glass is transported from the first pipe to the second pipe through the thermal expansion allowable space. By increasing the amount of heat transfer from the first pipe and the second pipe to the outside, the viscosity of the molten glass is increased.
Glass plate manufacturing equipment.

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