Device and method for manufacturing glass article

Abstract

To suppress generation of a foreign matter defect in a glass article.SOLUTION: A glass article manufacturing device 1 includes: a transfer pipe 14 for transferring a molten glass Gm; and a holding brick 24 disposed on an outer peripheral side of the transfer pipe 14 to hold the transfer pipe 14. The transfer pipe 14 includes: a tubular part 16; and a flange part 17 installed to an end 16a of the tubular part 16. The end 16a of the tubular part 16 and the flange part 17 are exposed to the outside from the holding brick 24. A cover member 28 for covering the end 16a of the tubular part 16 from the outside while storing the flange part 17 therein is installed in a part exposed from the holding brick 24.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for manufacturing glass articles such as glass sheets. [Background technology]

[0002] A glass article manufacturing apparatus includes a transfer pipe for transferring molten glass produced in a glass melting furnace and a retaining brick arranged on the outer periphery of the transfer pipe for retaining the transfer pipe in order to supply the molten glass produced in the glass melting furnace to a molding apparatus (see, for example, Patent Documents 1 and 2). Typically, a glass article manufacturing apparatus includes a plurality of pairs of transfer pipes and retaining bricks, and the ends of the transfer pipes of adjacent pairs are connected to each other.

[0003] Each of the transfer pipes includes a tubular portion and a flange portion provided at an end of the tubular portion. A longitudinal middle portion of the tubular portion is surrounded by the retaining bricks. Meanwhile, the longitudinal ends of the tubular portion and the flange portion are not surrounded by the retaining bricks and are exposed from the retaining bricks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-19629 A [Patent Document 2] JP 2019-108258 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the transfer pipe, the end of the tubular portion and the flange portion are exposed from the retaining bricks, which may cause foreign matter defects (such as tin oxide particles) in the manufactured glass article.

[0006] Here, the cause of the foreign matter defect is presumed to be as follows. That is, an air layer may be formed inside the transfer tube at a position corresponding to the end of the tubular part exposed from the retaining brick and the flange part. Then, some components (e.g., SnO2) may volatilize from the molten glass transferred inside the transfer tube into this air layer. However, the end of the transfer tube exposed from the retaining brick and the flange part are easily cooled by the outside air, especially in winter. As a result, it is considered that the components such as SnO2 volatilized in the air layer cool and solidify and mix into the molten glass, causing foreign matter defects such as tin oxide spots in the glass article. Note that SnO2 is added to the molten glass, for example, as a fining agent.

[0007] An object of the present invention is to suppress the occurrence of foreign matter defects in glass articles. [Means for solving the problem]

[0008] (1) The present invention, which has been invented to solve the above problems, is a glass article manufacturing apparatus comprising a transfer tube for transporting molten glass and a retaining brick arranged on the outer periphery of the transfer tube for holding the transfer tube, wherein the transfer tube comprises a tubular portion and a flange portion provided at an end of the tubular portion, the end and the flange portion of the tubular portion being exposed from the retaining brick, and the portion exposed from the retaining brick is provided with a cover member that covers the end of the tubular portion from the outside with the flange portion housed inside.

[0009] In this way, the tubular portion and flange portion of the transfer pipe exposed from the retaining bricks are kept warm by the cover member, which prevents the tubular portion and flange portion of the transfer pipe exposed from the retaining bricks from being cooled by outside air, thereby preventing the occurrence of foreign matter defects in the glass article.

[0010] (2) In the above configuration (1), it is preferable that a casing is provided for accommodating and fixing the retaining bricks therein, and the cover member is disposed along the casing.

[0011] In this way, the cover member can be easily disposed, and an appropriate space can be formed between the cover member and the transfer tube.

[0012] (3) In the above configuration (1) or (2), it is preferable that the transfer pipe has a cooling device that circulates gas to cool the flange portion, and the gas used to cool the flange portion is discharged into the space between the cover member and the transfer pipe.

[0013] In this way, the cooling by the cooling device can suppress thermal wear of the flange portion. Also, the gas used to cool the flange portion reaches a relatively high temperature. Therefore, if the gas used to cool the flange portion is discharged into the space between the cover member and the transfer pipe, the heat retention effect of the tubular portion of the transfer pipe exposed from the retaining brick and the flange portion can be improved.

[0014] (4) In the above configuration (3), it is preferable that the flange portion comprises a first flange portion and a second flange portion arranged opposite the first flange portion, and that the discharge direction of the gas used to cool the first flange portion and the discharge direction of the gas used to cool the second flange portion are different from each other.

[0015] This makes it easier for the temperature in the space between the cover member and the transfer pipe to become uniform, and the heat retention effect of the tubular portion and flange portion of the transfer pipe exposed from the retaining bricks is stabilized.

[0016] (5) In any one of the above configurations (1) to (4), the cover member is preferably made of a heat-resistant fabric.

[0017] In this way, appropriate ventilation can be ensured in the cover member, and the gas used for cooling can be discharged to the outside of the cover member while preventing outside air from flowing in. This makes it possible to prevent an excessive supply of the gas used for cooling to the space between the cover member and the transfer pipe.

[0018] (6) The present invention, which has been invented to solve the above problems, is a method for manufacturing a glass article, characterized in that it comprises a step of transporting molten glass using a transport pipe provided in a glass article manufacturing apparatus having any one of the configurations (1) to (5) above.

[0019] In this way, the same effects as those of the corresponding configurations already described can be obtained. Effect of the Invention

[0020] According to the present invention, the occurrence of foreign matter defects in glass articles can be suppressed. [Brief description of the drawings]

[0021] [Figure 1] 1 is a side view showing a glass article manufacturing apparatus according to a first embodiment of the present invention. [Diagram 2] 4 is a cross-sectional view showing the periphery of the connection portion between the first transport pipe and the second transport pipe. FIG. [Diagram 3] FIG. 3 is an enlarged view of a region X in FIG. [Figure 4] FIG. 4 is a perspective view showing an end portion of a first transfer pipe. [Diagram 5] 3 is a cross-sectional view of FIG. 2 taken along the line YY. [Figure 6] FIG. 3 is a cross-sectional view of FIG. 2 . [Figure 7] A cross-sectional view showing the periphery of the connection portion of adjacent transfer pipes of a glass article manufacturing apparatus according to a second embodiment of the present invention. [Figure 8] A cross-sectional view showing the periphery of the connection portion of adjacent transfer pipes of a glass article manufacturing apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the drawings. In addition, by assigning the same reference numerals to corresponding components in each embodiment, duplicated descriptions may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. In addition to the combination of the configurations clearly stated in the description of each embodiment, the configurations of multiple embodiments can be partially combined together even if not clearly stated, as long as there is no particular problem with the combination.

[0023] First embodiment As shown in Figure 1, the glass article manufacturing apparatus 1 of the first embodiment includes a melting furnace 2 arranged at the upstream end for heating glass raw material 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.

[0024] Transfer device 3 comprises, in order from the upstream side, a fining tank 5, a stirring tank 6, and a pot 7. Inlet portion 5a of fining tank 5 is connected to outlet portion 2b of melting furnace 2 via an upstream connecting pipe 8. Outlet portion 5b of fining tank 5 is connected to inlet portion 6a of stirring tank 6 via a midstream connecting pipe 9. Outlet portion 6b of stirring tank 6 is connected to inlet portion 7a of pot 7 via a cooling pipe 10.

[0025] The fining tank 5 is used to perform a fining process on the molten glass Gm produced in the melting furnace 2. The stirring tank 6 is used to perform a homogenization process by stirring the molten glass Gm that has been subjected to the fining process. The cooling pipe 10 is used to cool the molten glass Gm that has been subjected to the homogenization process and adjust the viscosity and other properties. The pot 7 is used to further adjust the viscosity, flow rate, and other properties of the cooled molten glass Gm. Note that a plurality of stirring tanks 6 may be arranged on the transfer path of the transfer device 3.

[0026] The forming device 4 includes a forming body 11 in which the molten glass Gm is caused to flow down and formed into a band shape by the overflow downdraw method, and a large-diameter introduction pipe 12 that introduces the molten glass Gm to the forming body 11. The introduction pipe 12 is supplied with the molten glass Gm from the pot 7 of the transfer device 3 via a small-diameter pipe 13.

[0027] The glass ribbon Gr formed into a belt shape is passed through an annealing furnace and then cut into a predetermined size by a cutting device to form a glass plate as a glass product. The glass plate has a thickness of, for example, 0.01 to 2 mm, and is used as a glass substrate or cover glass for displays such as liquid crystal displays and organic EL displays. The forming device 4 may be one that performs another downdraw method such as a stopped downdraw method, or may be one that performs a method other than the downdraw method such as a float method.

[0028] Examples of the material for the plate glass include silicate glass, silica glass, borosilicate glass, soda-lime glass, aluminosilicate glass, alkali-free glass, and aluminosilicate glass.

[0029] The alkali-free glass preferably contains, in mass %, 50-70% SiO2, 12-25% Al2O3, 0-12% B2O3, 0-12% Li2O+Na2O+K2O (total amount of Li2O, Na2O and K2O) of 0-1%, 0-8% MgO, 0-15% CaO, 0-12% SrO, 0-15% BaO, and 0.01-1.5% SnO2. Such a glass composition is suitable for glass substrates for displays.

[0030] The aluminosilicate glass preferably contains, in mass %, 40% to 70% SiO2, 10% to 30% Al2O3, 0% to 3% B2O3, 5% to 25% Na2O, 0% to 5.5% K2O, 0.1% to 10% Li2O, 0% to 5.5% MgO, 2% to 10% P2O5, and 0.01 to 1.5% SnO2. Such a glass composition makes it easier to achieve both high levels of ion exchange performance and devitrification resistance, and is suitable for chemically strengthened glass, particularly for cover glass for displays.

[0031] The fining tank 5, mixing tank 6, pot 7, upstream connecting pipe 8, midstream connecting pipe 9, and cooling pipe 10 of the transfer device 3 are all composed of transfer pipes. The ends of two adjacent transfer pipes on the transfer path of the transfer device 3 are connected to each other. Each of the fining tank 5, mixing tank 6, pot 7, upstream connecting pipe 8, midstream connecting pipe 9, and cooling pipe 10 may be composed of a single transfer pipe, or may be composed of multiple transfer pipes connected together. These transfer pipes will be described in detail below.

[0032] Fig. 2 shows two adjacent transfer pipes in the transfer path of the transfer device 3. Here, the transfer pipe located on the upstream side is the first transfer pipe 14, and the transfer pipe located on the downstream side is the second transfer pipe 15. Fig. 2 illustrates the periphery of the connection between the downstream end of the first transfer pipe 14 and the upstream end of the second transfer pipe 15.

[0033] Specific examples of the first transfer pipe 14 and the second transfer pipe 15 include the following: (1) when the first transfer pipe 14 is the upstream connecting pipe 8 and the second transfer pipe 15 is the fining tank 5, (2) when the first transfer pipe 14 is the fining tank 5 and the second transfer pipe 15 is the midstream connecting pipe 9, etc. Alternatively, when the fining tank 5, the upstream connecting pipe 8, the midstream connecting pipe 9 and the cooling pipe 10 are configured by connecting a plurality of transfer pipes, for example, when the first transfer pipe 14 is a part of the upstream side of the fining tank 5 and the second transfer pipe 15 is a part of the downstream side of the fining tank 5, etc.

[0034] The first transfer pipe 14 includes a tubular portion 16, a flange portion (first flange portion) 17 provided at one end (upstream end portion) and the other end (downstream end portion 16a) in the longitudinal direction of the tubular portion 16, an electrode portion 18, and a cooling device 19 that cools the flange portion 17. Similarly, the second transfer pipe 15 includes a tubular portion 20, a flange portion (second flange portion) 21 provided at one end (upstream end portion 20a) and the other end (downstream end portion) in the longitudinal direction of the tubular portion 20, an electrode portion 22, and a cooling device 23 that cools the flange portion 21.

[0035] The tubular parts 16, 20 are, for example, circular tubular. The tubular parts 16, 20 are made of platinum, platinum alloy, reinforced platinum, reinforced platinum alloy, etc. The molten glass Gm is transferred inside the tubular parts 16, 20 to the downstream side.

[0036] The flange portions 17, 21 are, for example, disk-shaped. The flange portions 17, 21 are formed so as to surround the entire circumference of the outer periphery of the tubular portions 16, 20. In this embodiment, the flange portion 17 of the first conveying pipe 14 includes an annular inner flange portion 17a provided on the outer periphery of the tubular portion 16, and a circular tube-shaped outer flange portion 17b provided on the outer periphery of the inner flange portion 17a. The flange portion 21 of the second conveying pipe 15 includes an annular inner flange portion 21a provided on the outer periphery of the tubular portion 16, and a circular tube-shaped outer flange portion 21b provided on the outer periphery of the inner flange portion 21a. The inner flange portions 17a, 21a are made of platinum, platinum alloy, reinforced platinum, reinforced platinum alloy, or the like. The outer flange portions 17b, 21b are made of nickel, nickel alloy, or the like.

[0037] The electrode parts 18, 22 are, for example, plate-shaped. The electrode parts 18, 22 are made of nickel, nickel alloy, or the like. In this embodiment, the electrode parts 18, 22 are attached to the flange parts 17, 21 (outer flange parts 17b, 21b). In this embodiment, the electrode part 18 of the first conveying pipe 14 is provided so as to protrude upward from the flange part 17, and the electrode part 22 of the second conveying pipe 15 is provided so as to protrude downward from the flange part 21. The protruding direction of the electrode parts 18, 22 is not particularly limited. The electrode parts 18, 22 penetrate the cover member 28 described later, and are connected to an electric wire (not shown) on the outside of the cover member 28.

[0038] The first transfer pipe 14 and the second transfer pipe 15 are connected with a flange portion 17 provided at the downstream end of the first transfer pipe 14 and a flange portion 21 provided at the upstream end of the second transfer pipe 15 facing each other.

[0039] The longitudinal middle portion 16b of the tubular portion 16 of the first transfer pipe 14 is held by the retaining brick 24. The retaining brick 24 is arranged so as to surround the entire circumference of the outer periphery of the tubular portion 16. The retaining brick 24 is fixed to the metal casing 25 while being accommodated inside the casing 25. Meanwhile, the downstream end 16a and the flange portion 17 of the tubular portion 16 of the first transfer pipe 14 are exposed from the retaining brick 24 while protruding downstream from the retaining brick 24. The length of the downstream end 16a of the tubular portion 16 of the first transfer pipe 14 (the length of the exposed portion of the tubular portion 16) is, for example, 1 to 50 m. Although not shown, the upstream end and the flange portion provided at the upstream end of the tubular portion 16 of the first transfer pipe 14 are also exposed from the retaining brick 24 while protruding upstream from the retaining brick 24.

[0040] The intermediate portion 20b in the longitudinal direction of the tubular portion 20 of the second transfer pipe 15 is held by the retaining brick 26. The retaining brick 26 is arranged so as to surround the entire circumference of the outer periphery of the tubular portion 20. The retaining brick 26 is housed inside a metal casing 27. Meanwhile, the upstream end portion and the flange portion 21 of the tubular portion 20 of the second transfer pipe 15 are exposed from the retaining brick 26 in a state where they protrude from the retaining brick 26 to the upstream side. The length of the upstream end portion of the tubular portion 20 of the second transfer pipe 15 (the length of the exposed portion of the tubular portion 20) is, for example, 1 to 50 mm. Although not shown, the downstream end portion and the flange portion provided at the downstream end portion of the tubular portion 20 of the second transfer pipe 15 are also exposed from the retaining brick 26 in a state where they protrude from the retaining brick 26 to the downstream side.

[0041] In the portions exposed from the retaining bricks 24, 26, the downstream end 16a of the tubular portion 16 of the first transfer pipe 14 and the upstream end 20a of the tubular portion 20 of the second transfer pipe 15 are covered by a cover member 28. In this state, the cover member 28 is disposed so as to surround the entire periphery of the ends 16a, 20a of the tubular portions 16, 20 with the flange portions 17, 21 housed therein.

[0042] In this embodiment, the cover member 28 is disposed along the casings 25, 27 of the first transfer pipe 14 and the casing 27 of the second transfer pipe 15 in a state of being bridged between them. More specifically, the cover member 28 is disposed by being wound around the casings 25, 27 in the circumferential direction.

[0043] The cover member 28 is disposed away from the ends 16a, 20a of the tubular parts 16, 20 and the flange parts 17, 21 so that a space S is interposed therebetween. The space S is a closed space. The cover member 28 prevents outside air from entering the space S. Therefore, the space S keeps the ends 16a, 20a of the tubular parts 16, 20 and the flange parts 17, 21 warm. Therefore, as shown in FIG. 3, even if an air layer A is formed inside the first transfer pipe 14 and the second transfer pipe 15 in the parts exposed from the retaining bricks 24, 26, the air layer A is not unduly cooled by the outside air. As a result, it is possible to suppress the occurrence of foreign matter defects such as tin oxide spots in the plate glass due to the cooling of the air layer A. In addition, air layer A is likely to be formed, for example, when the inner surface of the connecting portion between the tubular portion 16 and the flange portion 17 of the first transfer pipe 14 or the inner surface of the connecting portion between the tubular portion 20 and the flange portion 21 of the second transfer pipe 15 is curved outward.

[0044] The cover member 28 is made of a metal plate, a heat-resistant cloth, etc. However, the heat-resistant cloth has an advantage over a metal plate in that it is easier to fill gaps in the space S and improve heat retention. An example of the heat-resistant cloth is glass cloth.

[0045] As shown in Figs. 4 and 5, the cooling device 19 of the first transfer pipe 14 has a cooling flow passage 29 through which a cooling gas C, such as air, flows. The cooling flow passage 29 is formed inside the outer flange portion 17b. The cooling flow passage 29 includes a first cooling flow passage 29a and a second cooling flow passage 29b that constitute flow passages independent of each other. The number and shape of the flow passages that constitute the cooling flow passage 29 are not particularly limited and can be set appropriately according to the dimensions of the flange portion 17. In addition, the cooling flow passage 29 may be formed on the surface of the flange portion 17 by piping or the like, rather than inside the flange portion 17.

[0046] The first cooling flow passage 29a and the second cooling flow passage 29b each include an inlet 30 and an outlet 31 for the gas C. The inlet 30 of each cooling flow passage 29a, 29b is provided in the upper part of the outer flange portion 17b. The position of the inlet 30 is not particularly limited, and may be provided on the side or lower part of the outer flange portion 17b. A cooling pipe 32 for transporting the gas C is connected to the inlet 30 of each cooling flow passage 29a, 29b. The cooling pipe 32 penetrates the cover member 28 and is connected to a gas supply source (not shown) outside the cover member 28.

[0047] The outlets 31 of the cooling passages 29a, 29b are provided in the upper part of the outer flange portion 17b, and eject upward the spent gas (exhaust gas) Cx used in cooling the flange portion 17. That is, the discharge direction of the spent gas Cx discharged from the outlets 31 into the space S is upward.

[0048] As shown in FIG. 6, the cooling device 23 of the second transfer pipe 15 has substantially the same configuration as the cooling device 19 of the first transfer pipe 14. That is, the cooling device 23 of the second transfer pipe 15 has a cooling flow passage 33 formed inside the outer flange portion 21b and circulating a cooling gas C such as air. The cooling flow passage 33 has a first cooling flow passage 33a and a second cooling flow passage 33b that constitute flow passages independent of each other. The number and shape of the flow passages that constitute the cooling flow passage 33 are not particularly limited and can be appropriately set according to the dimensions of the flange portion 21. In addition, the cooling flow passage 33 may be formed on the surface of the flange portion 21 by piping or the like, rather than inside the flange portion 21.

[0049] The first cooling flow passage 33a and the second cooling flow passage 33b each include an inlet 34 and an outlet 35 for the gas C. The inlet 34 of each cooling flow passage 33a, 33b is provided in the lower part of the outer flange portion 21b. The position of the inlet 34 is not particularly limited, and may be provided on the side or upper part of the outer flange portion 21b. A cooling pipe 36 for transporting the gas C is connected to the inlet 34 of each cooling flow passage 33a, 33b. The cooling pipe 36 penetrates the cover member 28 and is connected to a gas supply source (not shown) outside the cover member 28.

[0050] The outlets 35 of the cooling passages 33a, 33b are provided in the lower part of the outer flange portion 21b, and inject the used gas (exhaust gas) Cx used for cooling the flange portion 21 downward. That is, the discharge direction of the used gas Cx discharged from the outlets 35 into the space S is downward. Therefore, in the space S, the discharge direction of the used gas Cx of the cooling device 19 of the first transfer pipe 14 and the discharge direction of the used gas Cx of the cooling device 23 of the second transfer pipe 15 are different from each other.

[0051] Since the used gas Cx used for cooling has a relatively high temperature, higher than the outside air, supplying the used gas Cx from each cooling device 19, 23 into the space S improves the heat retention of the space S. As a result, it is possible to prevent an unduly low temperature of the ends 16a, 20a and flanges 17, 21 of the tubular portions 16, 20 exposed from the retaining bricks 24, 26. The temperature of the space S is preferably, for example, 100 to 500°C.

[0052] In addition, since the discharge direction of the used gas Cx of the cooling device 19 of the first transfer pipe 14 and the discharge direction of the used gas Cx of the cooling device 23 of the second transfer pipe 15 are different from each other within the space S, the used gas Cx fills the entire space S, and the heat retention effect of the space S is uniform. Note that the discharge direction of the used gas Cx of the cooling device 19 of the first transfer pipe 14 and the discharge direction of the used gas Cx of the cooling device 19 of the second transfer pipe 15 are not particularly limited as long as they are different from each other within the space S.

[0053] Furthermore, when the cover member 28 is made of a heat-resistant cloth, appropriate breathability is ensured for the cover member 28. If the used gas Cx is discharged into the space S, the pressure in the space S tends to become relatively higher than the pressure outside the cover member 28. As a result, the used gas Cx discharged into the space S can be gradually discharged to the outside of the cover member 28 through the cover member 28, and an excessive increase in the pressure in the space S can be prevented. Note that even if the cover member 28 is breathable, in a state in which the pressure in the space S is relatively higher than the pressure outside the cover member 28, the outside air is prevented from entering the space S.

[0054] Next, a method for manufacturing a glass article using the manufacturing apparatus 1 configured as above will be described.

[0055] The manufacturing method includes a melting step, a molten glass transporting step, a forming step, a slow cooling step, and a cutting step.

[0056] In the melting step, glass raw materials supplied into the melting furnace 2 are heated to produce molten glass Gm.

[0057] The molten glass Gm preferably contains 0.01 to 1.5 mass % of SnO2, which facilitates degassing of the molten glass Gm in the fining step included in the molten glass transporting step.

[0058] In the molten glass transfer process, the molten glass Gm in the melting furnace 2 is transferred in sequence to the fining tank 5, the stirring tank 6, the pot 7, and the forming body 11 via the upstream connecting pipe 8, the midstream connecting pipe 9, and the cooling pipe 10. That is, the molten glass transfer process includes a fining process, a homogenization process, and a condition adjustment process. In the fining process, gas (bubbles) is generated from the molten glass Gm in the fining tank 5 due to the action of the fining agent mixed in the glass raw material. This gas is discharged to the outside from the fining tank 5. In the homogenization process, the molten glass Gm is stirred and homogenized in the stirring tank 6. In the condition adjustment process, the condition (e.g. viscosity and flow rate) of the molten glass Gm is adjusted in the cooling pipe 10 and the pot 7.

[0059] Furthermore, in the molten glass transport process, as shown in Figures 2 and 5, a cover member 28 is arranged to keep warm the ends 16a, 20a and flange portions 17, 21 of the tubular portions 16, 20 exposed from the retaining bricks 24, 26, thereby preventing the occurrence of foreign matter defects in the plate glass produced.

[0060] The temperature of the molten glass Gm at the outlet 5b of the fining vat 5 is higher than the temperature of the molten glass Gm at the inlet 5a of the fining vat 5, and is, for example, 1300°C or higher. That is, at the outlet 5b of the fining vat 5, the temperature of the molten glass Gm becomes high, and volatilization of SnO2 and the like, which causes foreign matter defects, is particularly likely to occur. Therefore, it is preferable to arrange a cover member 28 around the connection portion between the fining vat 5 and the midstream connecting pipe 9.

[0061] In the forming step, the molten glass Gm that has been through the molten glass transport step is supplied to the forming body 11. The forming body 11 causes the molten glass Gm to overflow from the overflow groove and flow down along its side wall surface. The forming body 11 causes the flowing molten glass Gm to join at the lower end, thereby forming a belt-like glass ribbon Gr.

[0062] Thereafter, the band-shaped glass ribbon Gr is subjected to an annealing process in an annealing furnace and a cutting process in a cutting device, and then cut into glass sheets of a predetermined size. Through the above steps, a high-quality glass sheet with extremely few defects caused by foreign matter defects is completed.

[0063] Second Embodiment 7, in the glass article manufacturing apparatus 1 and manufacturing method according to the second embodiment of the present invention, the discharge direction of the used gas Cx of the cooling device 19 of the first transfer pipe 14 and the discharge direction of the used gas Cx of the cooling device 23 of the second transfer pipe 15 are in the same direction (upward in the illustrated example) in the space S formed by the cover member 28. Even in this case, the heat retention in the space S is improved, and an undue decrease in temperature of the ends 16a, 20a and flange portions 17, 21 of the tubular portions 16, 20 exposed from the retaining bricks 24, 26 can be suppressed.

[0064] Third embodiment 8, in the manufacturing apparatus 1 and manufacturing method for a glass article according to the third embodiment of the present invention, a blanket 37 is disposed as a heat-insulating member on the outer circumferential surface of the first transfer pipe 14 and the outer circumferential surface of the second transfer pipe 15 in the space S formed by the cover member 28. In this manner, the blanket 37 can further improve the heat retention of the ends 16a, 20a and flanges 17, 21 of the tubular parts 16, 20 exposed from the retaining bricks 24, 26. The blanket 37 may be disposed on only one of the outer circumferential surface of the first transfer pipe 14 and the outer circumferential surface of the second transfer pipe 15.

[0065] For example, a blanket made of a fire-resistant fiber material can be used as the blanket 37. Specifically, a blanket that has heat resistance capable of withstanding temperatures of 1000°C or higher (preferably 1300°C or higher) and has elasticity can be used. As an example, a blanket made of alumina fiber, silica fiber, zirconia fiber, or a blend of these fibers can be used.

[0066] The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

[0067] In the above embodiment, at least one of the used gas Cx of the cooling device 19 of the first transfer pipe 14 and the used gas Cx of the cooling device 23 of the second transfer pipe 15 may be directly discharged to the outside of the cover member 28 using piping or the like. In other words, the used gas Cx of the cooling devices 19, 23 does not have to be supplied to the space S. In other words, by simply blocking the outside air with the cover member 28, it is possible to suppress an unduly lowered temperature of the ends 16a, 20a and flange portions 17, 21 of the tubular portions 16, 20 exposed from the retaining bricks 24, 26.

[0068] In the above embodiment, a cooling device may be provided to cool at least one of the electrode portion 18 of the first transfer pipe 14 and the electrode portion 22 of the second transfer pipe 15. The cooling device for the electrode portions 18, 22 may also serve as a cooling device for the flange portions 17, 21. For example, if a cooling pipe for supplying gas C to the flange portions 17, 21 is brought into close contact with the surface of the electrode portions 18, 22, the electrode portions 18, 22 and the flange portions 17, 21 can be cooled simultaneously.

[0069] In the above embodiment, the glass article is a plate glass, but is not limited thereto. The glass article may be, for example, a glass roll obtained by winding a strip-shaped glass ribbon into a roll, an optical glass part, a glass tube, a glass block, a glass fiber, or the like. [Explanation of symbols]

[0070] 1 Manufacturing equipment 2 Melting furnace 3 Transfer device 4 Molding equipment 5. Clarifying tank 6 Mixing tank 7 Pot 8 Upstream connecting pipe 9. Midstream connecting pipe 10 Cooling pipe 11 Molded body 14 First transfer pipe 15 Second transfer pipe 16,20 Tubular part 17,21 Flange 18,22 Electrode part 19,23 Each cooling device 24,26 Retaining bricks 25,27 Casing 28 Cover member 29,33 Cooling Channel 30,34 Inlet 31,35 Outlet 32,36 Cooling piping 37 Blanket C Gas Cx Spent gas (exhaust gas) Gm Molten Glass Gr Glass ribbon S space

Claims

1. A glass article manufacturing apparatus comprising: a transfer pipe for transferring molten glass; and a retaining brick disposed on an outer periphery of the transfer pipe for retaining the transfer pipe, the transfer pipe includes a tubular portion and a flange portion provided at an end of the tubular portion, the end of the tubular portion and the flange portion being exposed from the retaining brick; A glass article manufacturing apparatus comprising: a cover member that covers the end of the tubular portion from the outside with the flange portion housed inside the cover member in the portion exposed from the retaining brick.

2. A casing is provided for accommodating and fixing the retaining brick therein, 2. The apparatus for manufacturing a glass article according to claim 1, wherein the cover member is disposed along the casing.

3. the transfer pipe has a cooling device that cools the flange portion by circulating a gas therethrough, 3. The apparatus for manufacturing a glass article according to claim 1, wherein the gas used to cool the flange portion is discharged into a space between the cover member and the transfer pipe.

4. The flange portion includes a first flange portion and a second flange portion disposed opposite the first flange portion, The apparatus for manufacturing a glass article according to claim 3 , wherein a discharge direction of the gas used to cool the first flange portion and a discharge direction of the gas used to cool the second flange portion are different from each other.

5. 3. The apparatus for manufacturing a glass article according to claim 1, wherein the cover member is made of a heat-resistant cloth.

6. A method for producing a glass article, comprising the step of transferring molten glass using a transfer pipe provided in the glass article production apparatus according to claim 1 or 2.

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