JP2015131761A - Glass conduit, and manufacturing method of glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently conduct electric heating of molten glass using a different method from conventional methods in manufacturing a glass plate.SOLUTION: A glass conduit is used for conveying molten glass under heating in a manufacturing method of a glass plate. The glass conduit includes a conduit body made of metal, a pair of flanges provided at different positions in the longitudinal direction of the conduit body, and an electrode connected to each of the flanges to energize and heat the conduit body. A current path from the electrode to the flange has a branch to supply power to two different positions on the periphery of the flange before supplying power to each flange. The width of the electrode is larger than the outer diameter of the flange.

Description

  The present invention relates to a glass conduit that conveys molten glass while heating, and a glass plate manufacturing method for manufacturing a glass plate.

  As a glass substrate used for a flat panel display (hereinafter referred to as “FPD”) such as a liquid crystal display or a plasma display, a thin glass plate having a thickness of, for example, 0.5 to 0.7 mm is used. For example, the FPD glass substrate has a size of 300 × 400 mm in the first generation, but has a size of 2850 × 3050 mm in the tenth generation.

  Such a glass substrate for FPD of a large size after the 8th generation, for example, a glass substrate on which a TFT (Thin Film Transistor) is formed on the glass surface does not contain any alkali metal so as not to deteriorate the TFT characteristics. Alternatively, a glass plate containing a small amount is preferably used. Moreover, since such a glass plate has a very small thermal shrinkage, it is also suitably used when a polysilicon TFT is formed on the glass surface by performing a heat treatment at 400 to 500 ° C.

On the other hand, the high-temperature viscosity of molten glass is high at the production stage of a glass plate that contains no or even a small amount of alkali metal. For this reason, the clarification tank for defoaming the molten glass raises the temperature of the molten glass to a higher temperature than the conventional molten glass containing an alkali metal in order to effectively defoam the molten glass. . In the refining treatment, a refining agent for releasing oxygen and the like to grow bubbles in the molten glass is contained in the molten glass. However, the refining function is large from the viewpoint of reducing the environmental load in recent years. In many cases, a refining agent such as SnO ₂ is used instead of highly toxic As ₂ O ₃ to bring the molten glass to a high temperature of 1600 to 1630 ° C. or higher so that the defoaming treatment functions effectively.

For the above reasons, the molten glass is heated to a high temperature of 1600 ° C. or higher in the clarification tank. In order to increase the temperature of several hundred degrees Celsius from the melting tank that melts the glass raw material to produce the molten glass, such heating is performed on the glass conduit that transports the molten glass from the melting tank to the clarification tank. An electrode for heating the molten glass being conveyed by energizing and heating the conduit is provided.
Further, in order to adjust the temperature of the molten glass to a desired temperature, a glass conduit for conveying the molten glass from the clarification tank to a stirring tank for homogenizing the molten glass, which is a subsequent process of the clarification tank, An electrode for heating the molten glass being conveyed by energizing and heating the manufactured glass conduit is provided.
In addition, in order to adjust the temperature of the molten glass to a desired temperature, the glass glass conduit that conveys the molten glass from the stirring tank to the desired temperature is heated by heating the molten glass being conveyed. An electrode is provided for this purpose.
When an electrode is provided on a glass conduit, the electrode is generally connected to the tube body of the glass conduit via a flange that surrounds the circumference of the tube body of the glass conduit. However, since the electrode is connected to the tube body from one direction, the current flowing through the tube body is likely to be localized on a part of the circumference of the tube. For this reason, the electric heating is also localized, the temperature on the circumference of the glass conduit has a distribution, affects the heating of the molten glass, and creates a temperature difference in the molten glass. This temperature difference is likely to cause unevenness on the glass surface due to variation in the thickness of the sheet glass when the sheet glass is formed in the forming step. Moreover, since the low temperature part exists in a part on the periphery of a glass conduit | pipe, the glass of this part becomes easy to devitrify.
In addition, in order to heat the molten glass to a desired temperature, an excessive current flows through the electrode and the flange in order to pass a current through a portion where the energization heating is not sufficient, and the flange is heated more than necessary. A part is heated to a higher temperature than necessary.

With regard to such a glass conduit, a connection form of the electrode to the glass conduit has been proposed in order to connect the electrode to the glass conduit and to efficiently heat the glass conduit.
For example, a hollow tube body (glass conduit) for molten glass in which local overheating of an electrode for current heating is prevented is known (Patent Document 1).
The hollow tube body is a hollow tube body having a platinum or platinum alloy hollow tube used for energization heating, and a ring-shaped electrode is joined to the outer periphery of the hollow tube. Yes. One or more lead electrodes are joined to the outer edge of the ring-shaped electrode, and the ring-shaped electrode is provided at the center of the platinum or platinum alloy electrode and outside the center of the electrode. And a thick part made of platinum or a platinum alloy or a metal material other than platinum.

International Publication 2006/132044 Pamphlet

  On the outer edge of the ring-shaped electrode of the hollow tube described above, a thick part made of platinum or a platinum alloy or a metal material other than platinum provided outside the center of the electrode is provided. The current flows more uniformly on the circumference than in the prior art. For this reason, local overheating of the electrode for energization heating is prevented. However, in this hollow tube, since two extraction electrodes are provided on the hollow tube from opposite directions, the arrangement of the electrodes becomes complicated, and a complicated apparatus configuration tends to occur.

  An object of the present invention is to provide a glass conduit capable of efficiently conducting electric heating of molten glass using a method different from the conventional one, and a glass plate manufacturing method for producing a glass plate using the glass conduit. And

One embodiment of the present invention is a glass conduit that conveys molten glass while heating. The glass conduit is
A metal tube body,
A pair of flanges provided at different positions in the longitudinal direction of the tube body;
An electrode connected to each of the flanges for heating the tube body by passing an electric current.
The current path from the electrode to the flange includes a branch path that branches the current in order to supply power to two different locations on the circumference of the flange when a current flows through each of the flanges. The width of the electrode is larger than the outer diameter of the flange.

  In a preferred embodiment of the glass conduit, the electrode is a plate electrode connected to the outer edge of the flange, and the direction in which the center line extends in the width direction of the plate electrode is the center point of the cross section of the tube body The radial direction extending from

In still another preferred form of the glass conduit, the flange includes an inner ring part connected so as to surround the tube body, and an outer ring part surrounding the inner ring part and connected to the electrode. The thickness of the inner ring portion is smaller than the thickness of the outer ring portion.
At this time, the outer ring part has a thick part on the circumference and a thin part that is thinner than the thick part, and the connection part of the flange connected to the electrode is the thin part. It is preferable that

  In still another preferred embodiment of the glass conduit, the center point of the tube body is offset from the center point of the flange in a direction in which the electrode extends to the flange.

Another embodiment of the present invention is a glass plate manufacturing method for manufacturing a glass plate. The manufacturing method is
A melting process for melting glass raw material to produce molten glass;
A clarification step of clarifying the molten glass by energizing and heating a clarification tank composed of a metal tube through which the molten glass flows;
A homogenization step of homogenizing the molten glass after clarification;
In order to manufacture a glass plate, a forming step of forming the homogenized molten glass into a sheet glass is included.
The glass conduit is used for conveying molten glass during the melting step, the refining step, the homogenizing step, and the forming step.

  In the manufacturing method of the glass conduit | pipe and glass plate of the said aspect, the electrically heated heating of the molten glass in conveyance can be performed efficiently.

It is process drawing of the manufacturing method of the glass plate of this embodiment. It is a figure which shows typically the apparatus which performs the melting process-cutting process shown in FIG. (A), (b) is a figure explaining the glass conduit | pipe of this embodiment. (A), (b) is a figure explaining the modification of the glass conduit | pipe of this embodiment.

  Hereinafter, the manufacturing method of the glass conduit | pipe and glass plate of this embodiment is demonstrated.

(Overall overview of glass plate manufacturing method)
FIG. 1 is a process diagram of a method for producing a glass plate.
The glass plate manufacturing method includes a melting step (ST1), a refining step (ST2), a homogenizing step (ST3), a supplying step (ST4), a forming step (ST5), and a slow cooling step (ST6). And a cutting step (ST7). In addition, a plurality of glass plates that have a grinding process, a polishing process, a cleaning process, an inspection process, a packing process, and the like and are stacked in the packing process are conveyed to a supplier.

  FIG. 2 is a diagram schematically showing an apparatus for performing the melting step (ST1) to the cutting step (ST7). As shown in FIG. 2, the apparatus mainly includes a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300. The melting apparatus 100 includes a melting tank 101, a clarification tank 102, a stirring tank 103, and glass conduits 104, 105, and 106.

In the melting step (ST1), molten glass is obtained by heating and melting the glass raw material supplied in the melting tank 101 with a flame and an electric heater (not shown).
The clarification step (ST2) is mainly performed in the glass conduit 104, the clarification tank 102, and the glass conduit 105, and by heating the molten glass MG in the clarification tank 102, bubbles such as O ₂ contained in the molten glass MG. However, it grows by the oxidation-reduction reaction of the clarifying agent and floats on the liquid surface and is released, or the gas component in the bubbles is absorbed into the molten glass and the bubbles disappear.
In the homogenization step (ST3), the glass components are homogenized by stirring the molten glass MG in the stirring vessel 103 supplied through the glass conduit 105 using a stirrer.
In the supply step (ST4), molten glass MG is supplied to the forming apparatus 200 through the glass conduit 106.

In the molding apparatus 200, a molding process (ST5) and a slow cooling process (ST6) are performed.
In the forming step (ST5), the molten glass MG is formed into a sheet glass G, and a flow of the sheet glass G is created. In this embodiment, an overflow down draw method using a molded body (not shown) is used. In the slow cooling step (ST6), the formed and flowing sheet glass SG is cooled to have a desired thickness and no internal distortion occurs.
In a cutting process (ST7), in the cutting device 300, the sheet glass SG supplied from the shaping | molding apparatus 200 is cut | disconnected to predetermined length, and a plate-shaped glass plate is obtained. The cut glass plate is further cut into a predetermined size to produce a target size glass plate. Thereafter, the glass end surface is ground, polished, and the glass main surface is cleaned, and further, the presence or absence of abnormal defects such as bubbles is inspected, and then the glass plate that has passed the inspection is packed as a final product.

(Glass conduit)
FIG. 3A is a cross-sectional view illustrating the glass conduit 104 shown in FIG. 2 in more detail. FIG. 3B is a view for explaining the arrangement of the flanges extending over the electrodes when the left end of the glass conduit 104 shown in FIG. 3A is viewed from the X direction. The form of the glass conduit 104 described below can also be used in the glass conduits 105 and 106.

  The glass conduit 104 has a tube made of platinum or a platinum alloy that connects the melting tank 101 and the clarification tank 102. Specifically, the glass conduit 104 includes a tube body 110 made of platinum or a platinum alloy, a pair of metal flanges 112 and 114 provided at different positions in the longitudinal direction of the tube body 110, and the tube body 110. And plate-like electrodes 116 and 118 connected to the flanges 112 and 114, respectively, for heating by supplying a current. In the present embodiment, the electrodes 116 and 118 are arranged in parallel to the flanges 112 and 114, but may be arranged to be inclined with respect to the flanges 112 and 114. The material of the flanges 112 and 114 may be a conductor that allows current to flow. Preferably, platinum or a platinum alloy is preferably used from the viewpoint of withstanding high temperatures. The flanges 112 and 114 include inner ring portions 112 a and 114 a connected to the tube main body 110, and outer ring portions 112 b and 114 b surrounding the inner ring portions 112 a and 114 a and connected to the electrodes 116 and 118. The inner ring portions 112a and 114a are thinner than the outer ring portions 112b and 114b. The outer ring portions 112b and 114b are connected to the electrodes 116 and 118.

  As described above, the outer ring portions 112b and 114b connected to the electrodes 116 and 118 are made thicker than the inner ring portions 112a and 114a because the electrical resistance of the outer ring portions 112b and 114b is set to the inner ring portions 112a and 114a. This is to reduce the size. Thereby, the current flowing from the electrodes 116 and 118 to the flanges 112 and 114 can easily flow through the outer ring portions 112b and 114b. That is, in this embodiment, compared with the case where the thicknesses of the inner ring portions 112a and 114a and the outer ring portions 112b and 114b are the same, current flows to the portion opposite to the electrodes 116 and 118 across the flanges 116 and 118. It becomes easy to flow around. As a result, in the present embodiment, a more uniform current flow can be formed on the circumference of the tube main body 110, and local current heating as in the prior art can be eliminated.

The current paths of the currents flowing toward the flanges 112 and 114 in the electrodes 116 and 118 are branched in order to supply power to two different locations on the circumference of the flange before supplying power to the flanges 116 and 118, respectively. , 116b (118a, 118b).
Such branch paths 116a and 116b (118a and 118b) are formed, for example, by forming notches 117 and 119 in parts of the electrodes 116 and 118 as shown in FIG. 3B. 116b (118a, 118b) are preferably formed. By forming the notches 117 and 119 in a part of the electrodes 116 and 118, the branch paths 116a and 116b (118a and 118b) can be easily formed. The notches 117 and 119 do not have to be formed in order to form the branch paths 116a and 116b (118a and 118b). For example, even if the plate thickness of the electrodes 116 and 118 is not completely zero as in the notches 117 and 119, by reducing the plate thickness, the current can be divided into two or more as shown in FIG. Can be branched.
In the present embodiment, the electrodes 116 and 118 are connected to the flanges 112 and 114 from above the tube body 110, but the connection of the electrodes 116 and 118 is connected to the flanges 112 and 114 from above the tube body 110. It is not limited to a form, You may connect from the diagonally upper direction of the pipe | tube main body 110 from a horizontal direction, a diagonally downward direction, or a direct downward direction.

The center line CL in the width direction of the electrodes 116 and 118 is a radial direction extending from the center point O of the cross section of the tube body 110, and the notches 117 and 119 are formed on the center line CL. This is preferable in that the current is evenly distributed and the current flows through the branch paths 116a and 116b (118a and 118b). As a result, the current is easily distributed and distributed on the circumference of the tube main body 110.
In addition, the width of the plate-like electrodes 116 and 118 is larger than the diameter of the tube main body 110, and is larger than the outer diameter of the tube main body 110 at the upper part of the flange 112 (part on the electrode connection position side). This is preferable in that a current is supplied over a wide range, and the current can easily reach the bottom of the tube main body 110 (the portion on the side opposite to the electrode connection position). The width of the electrodes 116 and 118 may be larger than the outer diameter (diameter) of the flange 112. In this case, it is preferable in that the current is supplied in a wider range than the outer diameter of the flange 112, and the current can easily reach the bottom of the tube main body 110 (the portion on the side opposite to the electrode connection position). Further, the width of the electrodes 116 and 118 may be equal to or smaller than the diameter of the flange 112. In this case, compared with the case where the width of the electrodes 116 and 118 is larger than the diameter of the flange 112, the heat radiation in the electrodes can be further reduced. In consideration of the balance between the ease of current flow and heat dissipation, the width of the electrodes 116 and 118 may be larger than the diameter of the tube body 110 and smaller than the diameter of the flange 112. As in this embodiment, the width W ₁ of the electrodes 116, 118 is equal to the diameter (W ₂ ) of the flanges 112, 114, current is distributed to the tube body 110, and heat dissipation at the electrodes 116, 118 is performed. It is preferable at the point which can suppress.
The flanges 112 and 114 of the present embodiment include an inner ring part 112 a connected to the tube main body 110, and outer ring parts 112 b and 114 b surrounding the inner ring part 112 a and connected to the electrodes 116 and 118. The thickness of the inner ring portions 112a and 114a is smaller than the thickness of the outer ring portions 112b and 114b. The flanges 112 and 114 in this embodiment have inner and outer ring portions having different thicknesses, but the thicknesses of the flanges 112 and 114 may be uniform. In the present embodiment, before the current paths of the electrodes 116 and 118 supply power to the flanges 116 and 118 before supplying power to the flanges 116 and 118, respectively, two branched branches 116a and 116b ( 118a, 118b) at least.

(Modification 1)
FIG. 4A shows a first modification different from that shown in FIG.
In the first modification shown in FIG. 4A, the center point of the tube body 110 is offset to the opposite side of the electrodes 116 and 118 (the lower side in FIG. 4A) with respect to the center point of the flanges 112 and 114. doing. In the form shown in FIG. 3, the center points of the flanges 112 and 114 and the center point of the tube main body 110 coincided. Only the presence / absence of the offset of the center point is the difference between the above embodiment and the first modification. By offsetting the center point as described above, the length L ₁ of the inner ring portions 112a and 114a on the electrodes 116 and 118 side (the upper side in FIG. 4A) is increased with respect to the above embodiment. The length L ₂ on the opposite side of the inner ring portion 112 from the electrodes 116 and 118 (the lower side in FIG. 4A) can be made shorter than in the above embodiment. Since the inner ring portions 112a and 114a are thinner than the outer ring portions 112b and 114b, the electrical resistance is relatively high. For this reason, the portion where the length of the flow path through which the current flows is relatively long on the side of the electrodes 116 and 118 of the inner ring portions 112a and 114a is difficult for current to flow. The portion where the length of the flow path through which the current flows is relatively short, the current flows easily. Therefore, in the case of the first modification shown in FIG. 4A, the current tends to flow to the opposite side (the lower side in FIG. 4A) of the inner ring portions 112a and 114a from the electrodes 116 and 118. A uniform current flow can be formed on the circumference of the tube body 110. For this reason, local energization heating can be eliminated.

(Modification 2)
FIG. 4B is a second modification different from the form shown in FIG.
In the second modification shown in FIG. 4B, the upper half of the flanges 112 and 114 connected to the electrodes 116 and 118 are thin portions 112b ₁ and 114b ₁ , and the lower half is the thick portion 112b. _2, has become 114b _2. That is, the outer ring portion 112b, 114b has a thick portion 112b _2, 114b ₂ and the thick portion 112b _2, 114b ₂ thin walled portion 112b ₁ of the thickness as compared with, 114b ₁ on the circumference, the electrode Connection portions of the flanges 112 and 114 connected to the 116 and 118 are thin-walled portions 112b ₁ and 114b ₁ . In this way, the connection portions of the flanges 112 and 114 connected to the electrodes 116 and 118 are thin-walled portions 112b ₁ and 114b ₁ , so that the thick-walled portions 112b ₂ and 114b ₂ on the opposite side to the electrodes 116 and 118 are obtained. It is possible to make the current easily wrap around. Therefore, in the second modification, a more uniform current flow can be formed on the circumference of the tube body 110. For this reason, local energization heating can be eliminated.

(Glass raw material, glass composition)
The glass plate manufacturing method of the present embodiment can be applied to the manufacture of any glass plate. In particular, a glass substrate for a flat panel display such as a liquid crystal display device, an organic EL display device or a plasma display device, or a display unit. It is suitable for manufacture of the cover glass which covers.
In order to manufacture a glass plate according to the manufacturing method of the glass plate of this embodiment, a glass raw material is prepared so that it may become a desired glass composition. For example, when manufacturing a glass substrate for a flat panel display, it is preferable to mix the raw materials so as to have the following composition.

(A) SiO ₂ : 50 to 70% by mass,
(B) B ₂ O ₃ : 5 to 18% by mass,
(C) Al ₂ O ₃ : 10 to 25% by mass,
(D) MgO: 0 to 10% by mass,
(E) CaO: 0 to 20% by mass,
(F) SrO: 0 to 20% by mass,
(O) BaO: 0 to 10% by mass,
(P) RO: 5 to 20% by mass (wherein R is at least one selected from Mg, Ca, Sr and Ba, and is a component contained in the glass plate),
(Q) R ′ ₂ O: more than 0.10% by mass and 2.0% by mass or less (provided that R ′ is at least one selected from Li, Na, and K and is contained in the glass plate) Metal component),
(R) 0.05 to 1.5% by mass in total of at least one metal oxide selected from tin oxide, iron oxide, cerium oxide, and the like.

In addition, since (q) R ′ ₂ O is not essential, it may not be contained. In this case, 'becomes alkali-free glass containing no ₂ O in substantially from the glass plate R' R can reduce the risk of destroying the TFT ₂ O flows out. On the other hand, by deliberately containing (q) R ′ ₂ O in excess of 0.10% by mass and 2.0% by mass or less, deterioration of TFT characteristics and thermal expansion of glass are suppressed within a certain range, while It is possible to increase the basicity, facilitate the oxidation of a metal whose valence fluctuates, and improve the clarity. Furthermore, since the specific resistance of glass can be reduced, it is suitable for performing electric melting in the melting tank 101.

  Furthermore, in order to realize further high definition in recent years, a display using p-Si (low temperature polysilicon) TFT or oxide semiconductor instead of α-Si (amorphous silicon) TFT (Thin Film Transistor) is required. It has been. Here, in the process of forming the p-Si • TFT and the oxide semiconductor, there is a heat treatment process at a higher temperature than the process of forming the α-Si • TFT. Therefore, a glass plate on which p-Si.TFT or an oxide semiconductor is formed is required to have a low thermal shrinkage 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, it is necessary to raise the temperature of molten glass more in a glass conduit. However, the electric power supplied from the electrodes 116 and 118 to the flanges 112 and 114 in order to increase the temperature of the molten glass increases. In the conventional glass conduit, since the current is concentrated on the electrode side, the glass conduit may be damaged. However, since the current concentration on the electrodes 116 and 118 side of the glass conduit 104 can be alleviated in the present embodiment and Modifications 1 and 2, it is also suitable for manufacturing a high strain point glass that tends to have high temperature viscosity.

  For example, this embodiment and modified examples 1 and 2 are suitable for manufacturing a glass plate having a strain point of 655 ° C. or higher. In particular, a glass plate having a strain point of 675 ° C. or higher suitable for p-Si · TFT and oxide semiconductor is suitable for the present embodiment and Modifications 1 and 2, and a glass plate having a strain point of 680 ° C. or higher is more preferable. A glass plate having a strain point of 690 ° C. or higher is particularly suitable.

Examples of the composition of the glass plate having a strain point of 675 ° C. or higher include those in which the glass plate is represented by mass% and contains the following components.
SiO _2: 52~78% by weight,
Al ₂ O ₃ : 3 to 25% by mass,
B ₂ O ₃ : _{3 to} 15% by mass,
RO (provided that RO is a component of MgO, CaO, SrO and BaO and contained in the glass plate): 3 to 20% by mass,
The mass ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ is in the range of 7 or more.
It is preferable.
Further, in order to further increase the strain point, the mass ratio (SiO ₂ + Al ₂ O ₃ ) / RO 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 < ^-1 >. On the other hand, R ₂ O (where R ₂ O is a component of Li ₂ O, Na ₂ O and K ₂ O, and is not applied to the glass plate so that current does not flow through the melting tank 101 instead of glass during melting. The total amount of the components contained) It is preferable to reduce the specific resistance of the glass as 0.01 to 0.8% by mass. Alternatively, the mass to reduce the specific resistance of the glass ratio Fe ₂ O _3: It is preferable that 0.01 to 1 mass%. Furthermore, the mass ratio CaO / RO is preferably 0.65 or more in order to prevent an increase in the devitrification temperature while realizing a high strain point. Alternatively, the weight ratio _{(SiO 2 + Al 2 O 3} ) / B 2 O 3 is preferably in the range of 7.5 to 20. By setting the devitrification temperature to 1250 ° C. or lower, the overflow downdraw method can be applied. In consideration of application to mobile devices, the total content of SrO and BaO is preferably 0 to less than 2% by mass from the viewpoint of weight reduction.

In addition, it is preferable that said glass substrate for flat panel displays does not contain arsenic substantially, and it is more preferable that it does not contain arsenic and antimony substantially. That is, even if these substances are included, they are as impurities. Specifically, these substances include 0.1% by mass including oxides of As ₂ O ₃ and Sb ₂ O _3. The following is preferable.

In addition to the components described above, the glasses used in this embodiment and variations 1 and 2 contain various other oxides to adjust various physical, melting, fining, and forming properties of the glass. It doesn't matter. Examples of such other oxides, but are not limited _{to, SnO 2, TiO 2, MnO} , ZnO, Nb 2 O 5, MoO 3, Ta 2 O5, WO 3, Y 2 O 3, and , La ₂ O ₃ . Here, since the glass substrate for flat panel displays, such as a liquid crystal display and an organic EL display, has a particularly severe requirement for bubbles, it is preferable to contain at least SnO ₂ having a high clarification effect among the oxides.

  As mentioned above, although the manufacturing method of the glass conduit | pipe and glass plate of this invention was demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, even if various improvement and a change are carried out. Of course it is good.

100 melting apparatus 101 melting tank 102 fining vessel 103 stirred vessel 104, 105, 106, the glass conduit 110 tube body 112 flange 112a, 114a in the ring portion 112b, 114b outer ring portion 112b _1, 114b ₁ thin portion 112b _2, 114b ₂ Thick portions 116, 118 Electrodes 116a, 116b, 118a, 118b Branch paths 117, 119 Notches

Claims (6)

A glass conduit for conveying molten glass while heating,
A metal tube body,
A pair of flanges provided at different positions in the longitudinal direction of the tube body;
An electrode connected to each of the flanges for heating the tube body by passing an electric current,
The current path from the electrode to the flange includes a branch path for branching the current to supply power to two different locations on the circumference of the flange when a current flows through each of the flanges.
The glass conduit characterized in that the width of the electrode is larger than the outer diameter of the flange.   The electrode is a plate electrode connected to an outer edge of the flange, and a direction in which a center line extends in a width direction of the plate electrode is a radial direction extending from a center point of a cross section of the tube body. The glass conduit according to 1. The flange has an inner ring part connected so as to surround the pipe body, and an outer ring part surrounding the inner ring part and connected to the electrode,
The glass conduit according to claim 1 or 2, wherein a thickness of the inner ring portion is thinner than a thickness of the outer ring portion.   The outer ring part has a thick part on the circumference and a thin part that is thinner than the thick part, and a connection part of the flange connected to the electrode is the thin part. The glass conduit according to claim 3.   The center point of the said tube main body is a glass conduit | pipe as described in any one of Claims 1-4 offset toward the direction where the said electrode extends to the said flange with respect to the center point of the said flange. A glass plate manufacturing method for manufacturing a glass plate,
A melting process for melting glass raw material to produce molten glass;
A clarification step of clarifying the molten glass by energizing and heating a clarification tank composed of a metal tube through which the molten glass flows;
A homogenization step of homogenizing the molten glass after clarification;
Forming a glass plate, and forming the homogenized molten glass into a sheet glass,
The glass conduit according to any one of claims 1 to 5 is used for conveying molten glass during the melting step, the refining step, the homogenizing step, and the forming step. A method for manufacturing a glass plate.

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