Glass article production method and glass article production device

Abstract

A glass article production method including a processing step for processing molten glass Gm using a processing container 12, wherein vent pipes 18 are attached to and extend above an upper wall section 15c of the processing container 12, the method comprising a discharging step S1 for discharging gas inside the processing container 12 from the vent pipes 18 and a blocking step S2 for blocking the vent pipes 18 by raising the viscosity of the molten glass Gm inside the vent pipes 18 after the discharging step S1 has been executed.

Description

Glass article manufacturing method and glass article manufacturing device

[0001] The present invention relates to a technique for manufacturing a glass article using a processing vessel for processing molten glass.

[0002] In general, a method for manufacturing a glass article includes a transfer step of transferring molten glass flowing out of a melting furnace and a forming step of forming the transferred molten glass. In these transfer and forming steps, a treatment step of treating the molten glass using a treatment vessel is carried out.

[0003] As one example, Patent Document 1 discloses a process (forming process) for forming a glass ribbon from molten glass by a roll-out method using a processing vessel (called a sheet glass forming nozzle in the document).

[0004] The processing vessel disclosed in the document includes a nozzle having a slit at its lower end (referred to as a third flow path in the publication), and a reservoir (referred to as a second flow path in the publication) that is provided above the nozzle and serves as a supply unit that stores molten glass and supplies it to the nozzle.

[0005] Patent No. 6036192

[0006] Taking the processing vessel disclosed in Patent Document 1 as an example, the interior of this type of processing vessel is not filled with molten glass (e.g., is empty) when starting up the melting furnace or the manufacturing apparatus.

[0007] From this state, after a process of flowing molten glass into the processing vessel is performed to fill the interior of the processing vessel with molten glass, a gas accumulation portion (air accumulation portion) may occur inside the processing vessel, particularly in the upper portion (in the same document, the upper portion of the second flow path).

[0008] In such cases, when the processing process (molding process) is carried out, this gas accumulation may cause the inner wall surface of the processing vessel to oxidize, resulting in foreign matter being mixed into the molten glass or temperature unevenness in the molten glass, which may result in a decrease in the quality of the glass article being manufactured.

[0009] From the above viewpoints, an object of the present invention is to prevent the occurrence of gas accumulation inside a processing vessel after a process of flowing molten glass into the processing vessel is performed to change the inside of the processing vessel from a state in which it is not filled with molten glass to a state in which it is filled, thereby improving the quality of glass articles.

[0010] (1) A first aspect of the present invention, which has been invented to solve the above-mentioned problems, is a method for manufacturing a glass article, which includes a processing step of processing molten glass using a processing vessel, the method including a vent pipe attached to an upper wall portion of the processing vessel and extending upward, and which is characterized by including an exhaust step of discharging gas from inside the processing vessel through the vent pipe during the process of flowing molten glass into the processing vessel so that the inside of the processing vessel changes from a state in which it is not filled with molten glass to a state in which it is filled with molten glass, and a closing step of closing the vent pipe by increasing the viscosity of the molten glass inside the vent pipe when molten glass flows from inside the processing vessel into the vent pipe after the exhaust step has been performed.

[0011] According to this configuration, an exhaust process is performed until the process of flowing molten glass into the processing vessel is completed, and gas inside the processing vessel is discharged through the vent pipe. This makes it difficult for gas accumulation to occur inside the processing vessel. Then, if molten glass flows from the processing vessel into the vent pipe after the exhaust process is performed, a closing process is performed, and the viscosity of the molten glass inside the vent pipe increases, thereby closing the vent pipe. This prevents molten glass from continuously flowing out from the vent pipe. As a result, the processing vessel can be properly performed without gas accumulation occurring inside the processing vessel. This prevents problems such as oxidation of the inner wall surface of the processing vessel, which can cause foreign matter to be mixed into the molten glass, or temperature unevenness in the molten glass, thereby improving the quality of the glass article produced. Here, the above-mentioned exhaust process and closing process are performed when starting up the melting furnace or the manufacturing apparatus, specifically when replacing the processing vessel (e.g., a nozzle), changing the molten glass material, or performing maintenance and inspection of the melting furnace or processing vessel. Furthermore, even when the height position of the upper end of the processing vessel is significantly lower (for example, 1000 mm or more lower) than the liquid level of the molten glass in the melting furnace, the length of the vent pipe can be shortened by performing the closing step. This reduces deformation and thermal stress caused by thermal expansion of the vent pipe. Furthermore, when a terminal portion for electrically heating the vent pipe is provided as described below, the risk of damage to the vent pipe due to local heating during electrical heating can be reduced.

[0012] (2) In the configuration of (1) above, the closing step may be performed before the molten glass overflows from the inside of the vent pipe.

[0013] This arrangement can prevent the molten glass from being wasted due to the molten glass overflowing from the inside of the vent pipe.

[0014] (3) In the configuration of (1) or (2) above, in the closing step, a cooling gas may be blown onto the vent pipe to increase the viscosity of the molten glass inside the vent pipe.

[0015] In this way, the closing step can be performed with a simple configuration.

[0016] (4) In any of the configurations (1) to (3) above, the method may further include a step of heating the vent pipe after the closing step is performed and before the exhaust step is performed again, thereby heating the glass that closes the vent pipe and removing it from inside the vent pipe.

[0017] In this way, when the exhaust process is performed again, the gas inside the processing vessel can be appropriately exhausted through the vent pipe.

[0018] (5) In any of the above configurations (1) to (4), the treatment vessel or the vent pipe may have a terminal portion for electrically heating the vent pipe.

[0019] In this way, when the above-mentioned extraction step is carried out, the ventilation pipe can be easily heated with a simple configuration.

[0020] (6) In any of the configurations (1) to (5) above, the processing vessel is a forming vessel used to form a glass ribbon from molten glass by a slit downdraw method, and the forming vessel includes a nozzle having a slit and a supply unit disposed above the nozzle and supplying molten glass to the nozzle, the longitudinal direction of the supply unit is the same as the longitudinal direction of the slit, and the vent pipe may be attached to an upper wall of the supply unit.

[0021] In this way, gas can be discharged through the vent pipe from the inside of the supply section of the forming vessel, where gas accumulation is likely to occur, thereby enabling a high-quality glass ribbon to be formed by the slit downdraw method during the forming step.

[0022] (7) In the configuration of (6) above, an inlet section may be provided for allowing molten glass to flow into the supply section from above, and the vent pipes may be attached to both sides of the supply section in the longitudinal direction with respect to the inlet section.

[0023] In this way, gas can be discharged through the vent pipes from both sides of the supply section in the longitudinal direction when the inlet section is used as the reference, so that the occurrence of gas accumulation sections can be reliably prevented.

[0024] (8) In the configuration of (6) or (7) above, the ventilation pipe may be attached to an end region in the longitudinal direction of the supply part.

[0025] In this way, gas can be efficiently discharged through the vent pipe from the inside of the end region where gas accumulation is most likely to occur.

[0026] (9) A second aspect of the present invention, which has been invented to solve the above-mentioned problems, is a glass article manufacturing apparatus comprising a processing vessel for processing molten glass, characterized in that it comprises an air vent pipe attached to an upper wall portion of the processing vessel and extending upward, and glass for blocking the air vent pipe.

[0027] In the apparatus having such a configuration, the provision of a vent pipe allows gas inside the processing vessel to be discharged, and the provision of glass for closing the vent pipe allows the manufacturing apparatus to operate properly.

[0028] (10) A third aspect of the present invention, which has been invented to solve the above-mentioned problems, is a glass article manufacturing apparatus comprising a processing vessel for processing molten glass, characterized in that it comprises an air vent pipe attached to an upper wall portion of the processing vessel and extending upward, and a heating mechanism for heating the air vent pipe.

[0029] In the apparatus having such a configuration, the provision of a vent pipe allows gas inside the processing vessel to be discharged, and the provision of a heating mechanism allows the glass blocking the vent pipe to be heated and removed from inside the vent pipe.

[0030] According to the present invention, after carrying out a process of flowing molten glass into the interior of a processing vessel so that the interior of the processing vessel changes from a state in which it is not filled with molten glass to a state in which it is filled, gas accumulation is less likely to occur inside the processing vessel, thereby improving the quality of the glass article.

[0031] 1 is a schematic front view showing the overall configuration of a glass article manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of a main part of the glass article manufacturing apparatus according to the first embodiment of the present invention. FIG. 3 is a longitudinal side view cut along line A-A in FIG. 2. FIG. 4 is a longitudinal front view cut along line B-B in FIG. 2. FIG. 5 is a longitudinal side view cut along line CC in FIG. 2. FIG. 6 is a perspective view showing components of the glass article manufacturing apparatus according to the first embodiment of the present invention. FIG. 7 is a flowchart showing a glass article manufacturing method according to the first embodiment of the present invention. FIG. 8 is a longitudinal front view of a main part showing a state in which the glass article manufacturing method according to the first embodiment of the present invention (middle stage of the evacuation process) is being performed. FIG. 9 is a longitudinal front view of a main part showing a state in which the glass article manufacturing method according to the first embodiment of the present invention (final stage of the evacuation process) is being performed. FIG. 10 is a longitudinal front view of a main part showing a state in which the glass article manufacturing method according to the first embodiment of the present invention (closing process) is being performed. FIG. 11 is a longitudinal front view of a main part showing a state in which the glass article manufacturing method according to the first embodiment of the present invention (final stage of the closing process) is being performed. FIG. 12 is a longitudinal front view of a main part showing a state in which the glass article manufacturing method according to the first embodiment of the present invention (removal process) is being performed. FIG. 13 is a perspective view showing the configuration of a main part of the glass article manufacturing apparatus according to the second embodiment of the present invention. FIG. 14 is a schematic front view showing the overall configuration of a glass article manufacturing apparatus according to a third embodiment of the present invention.

[0032] Hereinafter, a glass article manufacturing apparatus and a glass article manufacturing method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0033] 1 illustrates a schematic configuration of a glass article manufacturing apparatus according to a first embodiment of the present invention. As shown in the figure, the manufacturing apparatus 1 includes a melting furnace 2 disposed at an upstream end thereof for heating glass raw materials to produce molten glass Gm, a transfer device 3 for transferring the molten glass Gm flowing out of the melting furnace 2 toward the downstream side, and a forming device 4 for forming a glass ribbon Gr using the molten glass Gm supplied from the transfer device 3.

[0034] Transfer device 3 comprises, in order from the upstream side, a fining vessel (fining vessel) 5, an agitating vessel (agitation vessel) 6, and a conditioning vessel (conditioning vessel) 7. The upstream end of fining vessel 5 is connected to the outlet of melting furnace 2 via an upstream connecting pipe 8, and the downstream end of fining vessel 5 is connected to the upstream end of agitating vessel 6 via a downstream connecting pipe 9. The downstream end of agitating vessel 6 is connected to the upstream end of conditioning vessel 7 via a cooling pipe 10. The downstream end of conditioning vessel 7 is connected to a downstream end pipe section 11 extending downward.

[0035] The fining vessel 5 performs a fining treatment on the molten glass Gm produced in the melting furnace 2. The stirring vessel 6 stirs the molten glass Gm that has been subjected to the fining treatment to perform a homogenization treatment. The cooling pipe 10 cools the molten glass Gm that has been subjected to the homogenization treatment to adjust its viscosity, flow rate, etc. The condition adjusting vessel 7 further adjusts the viscosity, flow rate, etc. of the cooled molten glass Gm.

[0036] The forming device 4 includes a forming container 12. The forming container 12 is disposed below an inlet pipe (inlet portion) 13 that communicates with the downstream end pipe portion 11 of the transfer device 3. In this embodiment, the forming container 12 is used to form a glass ribbon Gr from the molten glass Gm by the slit downdraw method.

[0037] The configuration of the forming container 12 will be described in detail below. Fig. 2 is a perspective view showing the overall configuration of the forming container 12, Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2, Fig. 4 is a cross-sectional view taken along line B-B in Fig. 2, and Fig. 5 is a cross-sectional view taken along line C-C in Fig. 2. As shown in Figs. 2 and 3, the forming container 12 broadly comprises a nozzle 14 having a slit Sr at its lower end, a storage tank (storage section) 15 provided above the nozzle 14, and an introduction section 16 provided above the storage section 15. In the following description, the direction indicated by X-X in Fig. 2 (the same direction as the longitudinal direction of the storage section 15 and the longitudinal direction of the slit Sr) will be referred to as the longitudinal direction, and the direction indicated by Y-Y in Fig. 2 will be referred to as the width direction.

[0038] The introduction section 16 is a portion where the molten glass Gm is introduced from the inlet section 13 to the reservoir section 15. As shown in FIGS. 2 and 4 , the introduction section 16 widens in the longitudinal direction as it moves downward. Furthermore, the introduction section 16 extends by the same distance on both sides in the longitudinal direction, based on the inlet section 13. As shown in FIG. 3 , the width dimension L1 of the introduction section 16 is equal to (the same as or approximately the same as) the diameter L2 of the inlet section 13 from the upper end to the lower end. As shown in FIG. 2 , the two upper wall sections 16 a of the introduction section 16 are inclined flat surfaces.

[0039] The reservoir 15 is a portion where the molten glass Gm introduced through the introduction portion 16 is temporarily stored and allowed to flow down. Therefore, in this embodiment, the reservoir 15 serves as a supply portion that supplies the molten glass Gm to the nozzle 14. As shown in FIGS. 2 and 3 , the reservoir 15 includes a cylindrical tubular portion 15a. As shown in FIG. 4 , both longitudinal ends of the tubular portion 15a are closed by end wall portions 15b. Furthermore, the reservoir 15 extends by the same distance on both longitudinal sides of the inlet portion 13. As shown in FIG. 3 , the diameter L3 of the reservoir 15 is longer than the width dimension L1 of the introduction portion 16.

[0040] The nozzle 14 is composed of a main body 14a and a slit plate 14b detachably attached to the lower end of the main body 14a. As shown in FIG. 6, the slit plate 14b has a slit Sr extending in a straight line. The width dimension L4 of the slit Sr is suitable for producing a glass ribbon Gr (a glass sheet as a final product) with an extremely thin sheet thickness. Specifically, this dimension is suitable for producing a glass sheet with a sheet thickness of 30 μm to 300 μm, preferably 50 μm to 100 μm. In this embodiment, multiple slit plates 14b having slits Sr with different width dimensions L4 are prepared, and these slit plates 14b are interchangeable. As shown in FIG. 3, the width dimension L5 of the main body 14a is shorter than the width dimension L1 of the introduction portion 16 and longer than the width dimension L4 of the slit Sr.

[0041] As shown in Figures 2 and 4, a terminal portion (not shown) of a heating mechanism for electrical heating is attached to each end wall portion 15b of the storage portion 15. The terminal portion is a rod-shaped member extending longitudinally outward from each end wall portion 15b. The terminal portion is primarily used for electrically heating the storage portion 15. In this embodiment, in addition to this terminal portion, a terminal portion (not shown) is provided for electrically heating only the slit plate 14b. Note that other heating means may be used instead of electrical heating, or other heating means may be used in addition to electrical heating.

[0042] An upwardly extending vent pipe 18 is attached to the upper wall of the forming container 12. In this embodiment, as shown in FIGS. 3 and 5 , the vent pipe 18 is attached to the upper wall 15c of the storage section 15. Specifically, the vent pipe 18 is attached to both longitudinal sides of the storage section 15 (the supply section of the forming container 12). More specifically, the vent pipe 18 is attached to an end region 15y in the longitudinal direction of the storage section 15 (the supply section of the forming container 12). Here, the end region 15y refers to, for example, a region extending inward from both longitudinal ends of the storage section 15 (the supply section of the forming container 12) and having a length of 0.3×L6 (mm) (preferably 0.2×L6 (mm)), assuming that the longitudinal dimension of the storage section 15 (the supply section of the forming container 12) is L6 (mm). The ventilation pipe 18 may be electrically heated by the terminal portion of the end wall portion 15b described above, but in this embodiment, a terminal portion (not shown) is provided in addition to the terminal portion of the end wall portion 15b described above for electrically heating only the ventilation pipe 18.

[0043] The above-described components of the forming container 12, i.e., the introduction section 16, the storage section 15, the main body 14a of the nozzle 14, and the slit plate 14b, are made of platinum or a platinum alloy. The vent pipe 18 is also made of platinum or a platinum alloy.

[0044] Next, a method for manufacturing a glass article carried out using the manufacturing apparatus 1 having the above-described configuration will be described.

[0045] 7, this manufacturing method mainly includes an evacuation step S1, a closing step S2, a molding step S3, and a removal step S4. After the removal step S4 is performed, the evacuation step S1, the closing step S2, and the molding step S3 can be performed again.

[0046] The exhaust step S1 is performed as follows. For example, when replacing the forming vessel 12, when replacing only the slit plate 14b of the forming vessel 12, when changing the material of the molten glass Gm, or during maintenance and inspection of the melting furnace 2 or the forming vessel 12, the interior of the forming vessel 12 becomes a state where it is not filled with molten glass Gm (here, it is empty). The exhaust step S1 is performed in the process of flowing molten glass Gm into the interior of the forming vessel 12 through the inlet portion 13 to change the interior of the forming vessel 12 from such a state to a state where it is filled with molten glass Gm.

[0047] FIG. 8 is a vertical cross-sectional view showing the state of the evacuation step S1 in the middle stage, and FIG. 9 is a vertical cross-sectional view showing the state of the evacuation step S1 in the final stage. Note that these figures only show one half of the longitudinal direction of the forming vessel 12 provided with the vent pipe 18, but the other half of the longitudinal direction has a similar configuration. As shown in these figures, as the amount of molten glass Gm inside the forming vessel 12 increases, gas inside the forming vessel 12 is discharged through the vent pipe 18 as indicated by the arrows. The evacuation step S1 is continued until the step of flowing the molten glass Gm into the forming vessel 12 is completed. This prevents gas accumulation (air accumulation) inside the forming vessel 12.

[0048] In this embodiment, since gas accumulation is likely to occur in the storage section 15 (the upper part of the interior) of the forming container 12, a vent pipe 18 is attached to the upper wall 15c of the storage section 15. Furthermore, since gas accumulation is particularly likely to occur in end regions 15y (the upper part of the interior) of the storage section 15 in the longitudinal direction, a vent pipe 18 is attached to the upper wall 15c of these end regions 15y. Here, the region where gas accumulation is particularly likely to occur is the region depicted by the dotted line indicated by symbol Z in Fig. 8.

[0049] Note that, while this exhaust step S1 is being performed, the molten glass Gm does not flow down through the slits Sr of the slit plate 14b. That is, when the molten glass Gm starts to flow into the forming container 12, the slit plate 14b is not electrically heated and its temperature is lowered, so the slits Sr become viscous and are blocked with solidified glass Gf. In this case, the slits Sr may be blocked with the solidified glass Gf by lowering the temperature of the slit plate 14b, for example, by blowing a cooling gas onto the slit plate 14b. And, while the exhaust step S1 is being performed, the slit plate 14b is not electrically heated, so the slits Sr remain blocked with the solidified glass Gf.

[0050] FIG. 10 is a vertical cross-sectional view showing the implementation of the closing step S2. While FIG. 10 illustrates only one longitudinal half of the forming vessel 12 provided with the vent pipe 18, the other longitudinal half is similarly configured. As shown in FIG. 10, after the exhaust step S1 is performed, the molten glass Gm flows from the inside of the forming vessel 12 into the inside of the vent pipe 18. At this time, the closing step S2 is performed. More specifically, in the closing step S2, before the molten glass Gm overflows from the inside of the vent pipe 18, a cooling gas E (e.g., high-pressure air) is blown toward the vent pipe 18 using a gas blowing means 19 or the like. This blowing is performed when a temperature sensor, such as a thermocouple, provided in the vent pipe 18 detects a temperature increase due to contact of the vent pipe 18 with the molten glass Gm. As a result, the viscosity of the molten glass Gm inside the vent pipe 18 increases, and the molten glass solidifies into glass Gh, as shown in FIG. 11. The solidified glass Gh ensures that the vent pipe 18 is closed.

[0051] 1 , the height difference ΔL between the liquid level GL of the molten glass Gm in the melting furnace 2 and the upper end of the forming container 12 is 1000 mm to 3000 mm, or 1500 mm to 2500 mm. Therefore, if the closing step S2 is not performed, a vent pipe 18 of a length corresponding to the height difference ΔL is required. However, by performing the closing step S2 as described above, the length of the vent pipe 18 can be shortened. In this embodiment, the length of the vent pipe 18 is 100 mm to 500 mm. This eliminates the need to use a large amount of platinum or platinum alloy, reduces manufacturing costs, and eliminates the difficult task of manufacturing and installing a long vent pipe 18.

[0052] The forming step S3 is a processing step for forming a glass ribbon Gr using the forming container 12. The forming step S3 is performed after the closing step S2 is completed. Before the forming step S3 is performed, the occurrence of gas accumulation inside the forming container 12 is suppressed in the above-described exhaust step S1. Therefore, during the forming step S3, problems such as the inner wall surface of the forming container 12 being oxidized, causing foreign matter to be mixed into the molten glass Gm, or temperature unevenness in the molten glass Gm are less likely to occur. This improves the quality of the formed glass ribbon Gr (a glass sheet, which is the final product). Furthermore, while the forming step S3 is being performed, all components of the forming container 12 (including the slit plate 14b) are electrically heated, but the vent pipe 18 is not. Therefore, the vent pipe 18 is maintained in a state where it is blocked by the solidified glass Gh.

[0053] In the forming step S3, a glass ribbon Gr is formed by a slit downdraw method using the forming container 12. In this case, referring to Fig. 1 , in order to suppress widthwise shrinkage of the glass ribbon Gr immediately after it flows down from the slit Sr of the forming container 12, measures such as blowing cooling air onto both longitudinal end portions R1 of the glass ribbon Gr or clamping both longitudinal end portions R1 with cooling rollers are taken. Furthermore, after the glass ribbon Gr no longer contracts in the width direction, measures such as clamping both longitudinal end portions R2 of the glass ribbon Gr with conveying rollers over multiple stages (three positions in the upper and lower directions in the illustrated example, but more than one position may be used) and feeding the glass ribbon Gr downward are taken.

[0054] The formed glass ribbon Gr is cut to produce glass plates of predetermined dimensions. These glass plates can be used as glass substrates in displays such as liquid crystal displays and organic EL displays. In this case, the composition of the glass plate can be alkali-free glass. The glass plate can also be used as a cover glass for the display. In this case, the composition of the glass plate can be aluminosilicate glass, which makes the glass plate suitable for chemically strengthened glass.

[0055] FIG. 12 is a vertical cross-sectional view showing the implementation of the removal step S4. While the drawing shows only one longitudinal half of the forming vessel 12 provided with the vent pipe 18, the other longitudinal half is similarly configured. As shown in the drawing, in the removal step S4, the vent pipe 18 is electrically heated, thereby melting part or all of the solidified glass Gh that blocks the vent pipe 18. As a result, the solidified glass Gh escapes from the vent pipe 18 as indicated by the arrow. In the illustrated example, the removal step S4 is performed when the inside of the forming vessel 12 is empty. However, the removal step S4 may also be performed when the inside of the forming vessel 12 is not empty, as long as the inside of the forming vessel 12 is not filled with molten glass Gm.

[0056] When the extraction step S4 is completed, it becomes possible to circulate gas through the ventilation pipe 18. Therefore, the exhaust step S1 can be performed again in the same manner as described above. After the exhaust step S1, the closing step S2 and the molding step S3 can be performed again in the same manner as described above. The execution of these steps S1, S2, S3, and S4 can be performed repeatedly any number of times.

[0057] Considering the above manufacturing method, the manufacturing apparatus 1 according to the present embodiment requires glass (solidified glass Gh) to block the vent pipe 18 when performing the forming step S3. That is, when forming the glass ribbon Gr using this manufacturing apparatus 1, the vent pipe 18 needs to be closed, and therefore the glass Gh to block the vent pipe 18 is an essential component.

[0058] 13 is a perspective view showing a main part of a glass article manufacturing apparatus 1 according to a second embodiment of the present invention. This second embodiment differs from the above-described first embodiment in that the forming device 4 includes a pair (or may include multiple pairs) of rolling rollers 21 that form a glass ribbon Gr from the molten glass Gm by the roll-out method, and a processing vessel (supply nozzle) 22 that supplies the molten glass Gm to these rolling rollers 21 from above.

[0059] More specifically, the supply nozzle 22 widens in the longitudinal direction as it moves downward. Furthermore, the supply nozzle 22 extends by the same distance on both sides in the longitudinal direction, based on the inlet portion 13. A vent pipe 18 is attached to each of the upper wall portions 22c on both sides in the longitudinal direction of the supply nozzle 22. The molten glass Gm flowing down from the supply nozzle 22 is rolled between a pair of rolling rollers 21 to form a glass ribbon Gr having a desired thickness.

[0060] According to the manufacturing apparatus 1 of the second embodiment configured as described above, a processing step (supply step) is performed in which the molten glass Gm is supplied from above to the pair of rolling rollers 21 using the supply nozzle 22. Therefore, in this second embodiment, the evacuation step S1, the closing step S2, the supply step, and the extraction step S4 are performed in this order. Note that the evacuation step S1, the closing step S2, and the extraction step S4 are performed in the same manner as in the first embodiment described above.

[0061] The supplying process will now be described. If the vent pipe 18 were not provided before the supplying process, gas accumulations could occur inside the end regions on both longitudinal sides of the supply nozzle 22 (regions around the attachment portions of the vent pipe 18). In this regard, the occurrence of gas accumulations inside the supply nozzle 22 is suppressed in the above-described exhausting process S1. Therefore, during the supplying process, problems such as oxidation of the inner wall surface of the supply nozzle 22 causing foreign matter to be mixed into the molten glass Gm or temperature unevenness in the molten glass Gm are less likely to occur. This improves the quality of the glass ribbon Gr (a glass sheet, which is the final product) formed using the pair of rolling rollers 21.

[0062] 14 is a front view showing a schematic configuration of a glass article manufacturing apparatus 1 according to a third embodiment of the present invention. This third embodiment differs from the above-described first embodiment in that the forming device 4 includes a forming body 23 that forms a glass ribbon Gr from the molten glass Gm by the overflow downdraw method, and in that a vent pipe 18 is attached to an upper wall portion 24c of a treatment container (transfer and supply container) 24 that communicates with a downstream end tube portion 11 extending downward from the condition adjustment container 7 of the transfer device 3. The transfer and supply container 24 is a container that transfers and supplies the molten glass Gm to the forming body 23.

[0063] According to the manufacturing apparatus 1 of the third embodiment configured as described above, a process step (transfer and supply step) is performed in which the molten glass Gm is transferred and supplied to the forming body 23 using the transfer and supply container 24. Therefore, in this third embodiment, the evacuation step S1, the closing step S2, the transfer and supply step, and the withdrawal step S4 are performed in this order. Note that the evacuation step S1, the closing step S2, and the withdrawal step S4 are performed in the same manner as in the first embodiment described above.

[0064] Here, the transfer and supply process will be described. If the vent pipe 18 were not provided before the transfer and supply process, a gas accumulation portion could occur inside the transfer and supply container 24 at a position near the downstream end between the upstream end 24x and the downstream end 24y (the area around the attachment portion of the vent pipe 18). In this regard, the occurrence of a gas accumulation portion inside the transfer and supply container 24 is suppressed in the above-described exhaust process S1. Therefore, during the transfer and supply process, adverse effects such as oxidation of the inner wall surface of the transfer and supply container 24, contamination of the molten glass Gm with foreign matter, or temperature unevenness in the molten glass Gm, are less likely to occur. This improves the quality of the glass ribbon Gr (a glass sheet, which is the final product) formed using the forming body 23.

[0065] The first, second, and third embodiments of the present invention have been described above, but the embodiments of the present invention are not limited to these, and various modifications are possible without departing from the gist of the present invention.

[0066] For example, in the first embodiment, the introduction part 16 is provided above the storage part 15 of the forming container 12, but the introduction part 16 may be omitted. That is, the storage part 15 may be connected to the lower end part of the inlet part 13.

[0067] In the first embodiment, the cross-sectional shape of the reservoir 15 of the forming container 12 (see FIG. 3) is circular, but it may be elliptical, rectangular, or another polygonal shape.

[0068] In the first embodiment, the supply portion of the forming vessel 12 is the reservoir 15 having a circular cross-sectional shape (see FIG. 3 ), but the supply portion may not fulfill the role of the reservoir 15. That is, the supply portion of the forming vessel 12 does not have to fulfill the role of temporarily retaining the molten glass Gm and supplying it to the nozzle 14. Therefore, the supply portion of the forming vessel 12 does not have to bulge in the width direction as in a circular cross-sectional shape.

[0069] In the first embodiment, the reservoir 15 of the forming container 12 extends from the inlet 13 to both sides in the longitudinal direction along a horizontal line, but may extend from both sides in the longitudinal direction along an inclined line that slopes downward. Note that the inclined line may be bent midway.

[0070] In the first embodiment, the vent pipe 18 is attached to the upper wall portion 15c of the storage portion 15 of the forming container 12. However, instead of this, the vent pipe 18 may be attached to the upper wall portion 16a of the introduction portion 16 (for example, near the boundary between the upper wall portion 16a of the introduction portion 16 and the storage portion 15). In this case, it is preferable that the inclination angle of the upper wall portion 16a of the introduction portion 16 with respect to the horizontal plane is smaller than in the examples shown in FIGS. 2 and 4 .

[0071] In the first embodiment, the processing vessel is the forming vessel 12, in the second embodiment, the processing vessel is the supply nozzle 22, and in the third embodiment, the processing vessel is the transfer supply vessel 24. However, the present invention can be similarly applied to processing vessels other than these vessels 12, 22, and 24, as long as a gas accumulation portion can be similarly generated in the processing vessel.

[0072] DESCRIPTION OF SYMBOLS 1 Glass article manufacturing apparatus 2 Melting furnace 3 Transfer device 4 Forming device 12 Forming vessel (treatment vessel) 13 Inlet section (inlet pipe) 14 Nozzle 14a Nozzle body 15 Storage section (supply section of forming vessel) 15c Upper wall section of forming vessel (storage section) 15y End region of storage section (supply section of forming vessel) 16 Introduction section 16a Upper wall section of forming vessel (introduction section) 18 Vent pipe 22 Supply nozzle (treatment vessel) 22c Upper wall section of supply nozzle (treatment vessel) 24 Transfer supply vessel (treatment vessel) 24c Upper wall section of transfer supply vessel (treatment vessel) Gh Glass (solidified glass) Gm Molten glass Gr Glass ribbon S1 Evacuation process S2 Closing process S3 Forming process S4 Extraction process Sr Nozzle slit

Claims

1. A method for manufacturing a glass article, comprising a processing step of processing molten glass using a processing vessel, the processing vessel comprising a vent pipe attached to an upper wall portion and extending upward, an exhaust step of discharging gas from inside the processing vessel through the vent pipe during the process of flowing molten glass into the processing vessel to change the interior of the processing vessel from a state in which it is not filled with molten glass to a state in which it is filled with molten glass, and a closing step of closing the vent pipe by increasing the viscosity of the molten glass inside the vent pipe when molten glass flows from inside the processing vessel into the vent pipe after the exhaust step has been performed.

2. The method for manufacturing a glass article according to claim 1, wherein the closing step is carried out before molten glass overflows from the inside of the vent pipe.

3. A method for manufacturing a glass article according to claim 1, wherein in the closing step, a cooling gas is blown into the vent pipe to increase the viscosity of the molten glass inside the vent pipe.

4. A method for manufacturing a glass article as described in claim 1, further comprising an extraction step of heating the vent pipe after the closing step is performed and before the exhaust step is performed again, thereby heating the glass that closes the vent pipe and extracting it from inside the vent pipe.

5. The method for manufacturing a glass article according to claim 4, wherein the treatment vessel or the vent pipe is provided with a terminal portion for electrically heating the vent pipe.

6. A method for manufacturing a glass article as described in claim 1, wherein the processing vessel is a forming vessel used to form a glass ribbon from molten glass by a slit downdraw method, the forming vessel comprises a nozzle having a slit and a supply unit disposed above the nozzle and supplying molten glass to the nozzle, the longitudinal direction of the supply unit is the same as the longitudinal direction of the slit, and the vent pipe is attached to the upper wall of the supply unit.

7. A method for manufacturing a glass article as set forth in claim 6, wherein the supply section is provided with an inlet section for allowing molten glass to flow into the supply section from above, and the vent pipes are attached to both sides of the supply section in the longitudinal direction, with the inlet section as a reference.

8. The method for manufacturing a glass article according to claim 6, wherein the vent pipe is attached to an end region in the longitudinal direction of the supply part.

9. A glass article manufacturing apparatus comprising a processing vessel for processing molten glass, the apparatus comprising: a vent pipe attached to an upper wall of the processing vessel and extending upward; and glass for closing the vent pipe.

10. A glass article manufacturing apparatus having a processing vessel for processing molten glass, characterized in that the apparatus comprises: an air vent pipe attached to an upper wall portion of the processing vessel and extending upward; and a heating mechanism for heating the air vent pipe.

Images