Glass article manufacturing method and manufacturing device

Abstract

A method for manufacturing a glass article includes a melting step for obtaining molten glass (Gm) by melting a glass raw material (Gr) by heating an electrode (3) immersed in the molten glass (Gm) housed in a melting furnace (1). The melting furnace (1) is provided with a heat insulating layer (8) that insulates the top wall (1c) of the melting furnace (1). In the melting step, a covering layer (Gx), which covers the liquid surface (LS) of the molten glass (Gm) and comprises a material layer (Ga) and a bubble layer (Gb), is formed, and the lowest temperature of the top wall (1c) is kept at 600-1100 DEG C by means of a heat insulating layer (8).

Description

Technical Field

[0001] The present invention relates to a method and a device for manufacturing a glass article. Background Art

[0002] The manufacturing method of glass products such as glass fiber and plate glass includes, for example: a supply process of supplying glass raw materials from the upstream side of a melting furnace to molten glass contained in the melting furnace; a melting process of melting the glass raw materials to obtain molten glass; and a discharge process of discharging the molten glass from the downstream side of the melting furnace.

[0003] In the melting process, for example, glass raw materials are sometimes melted by heating (energizing) by electrodes immersed in the molten glass to obtain molten glass. When heating by electrodes is used in this way, in order to improve the thermal efficiency of the melting furnace, the liquid surface of the molten glass is covered with a covering layer derived from the glass raw materials, which sometimes suppresses heat dissipation from the molten glass (for example, refer to Patent Document 1). Here, the covering layer includes: a material layer formed by the glass raw materials; and a bubble layer formed as the glass raw materials are melted.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 054385 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When the liquid surface of the molten glass is covered with a covering layer, the covering layer needs to be at a temperature (viscosity) at which the gas generated from the covering layer and the molten glass is fully discharged during the process of melting the glass raw materials. On the other hand, when the glass flow rate is increased in order to improve the production efficiency of glass products, the supply of glass raw materials to the glass melting furnace needs to be increased.

[0009] However, when the supply of glass raw materials increases, the covering layer covering the liquid surface of the molten glass inevitably contains a large amount of unmelted glass raw materials with a relatively low temperature. As a result, the temperature of the covering layer decreases, and it is difficult for gas to be discharged from the covering layer. When it is difficult for gas to be discharged from the covering layer, the liquid surface level of the molten glass becomes unstable, which may cause problems such as poor production efficiency of glass products.

[0010] An object of the present invention is to suppress a decrease in the temperature of a coating layer covering the liquid surface of molten glass, stabilize the liquid surface level of molten glass, and improve the production efficiency of glass products.

[0011] Solutions to Solve Problems

[0012] (1) The present invention made in order to solve the above-mentioned problems is a method for manufacturing glass articles, comprising: a supplying step of supplying glass raw materials from the upstream side of a melting furnace to molten glass contained in the melting furnace; a melting step of melting the glass raw materials to obtain molten glass by heating with electrodes immersed in the molten glass; and a discharging step of discharging the molten glass from the downstream side of the melting furnace, wherein the method for manufacturing glass articles is characterized in that the melting furnace has a heat-insulating structure for insulating the top wall of the melting furnace, and in the melting step, a covering layer including a material layer and a bubble layer is formed to cover the liquid surface of the molten glass, and the heat-insulating structure is used to keep the minimum temperature of the top wall at 600 to 1100°C.

[0013] When the minimum temperature of the top wall is less than 600°C due to the heat-insulating structure, the temperature of the covering layer covering the liquid surface of the molten glass decreases, and it is difficult for the gas to be discharged from the covering layer. On the other hand, when the minimum temperature of the top wall exceeds 1100°C due to the heat-insulating structure, part of the covering layer (such as the bubble layer) disappears, and the thermal efficiency of the melting furnace may be significantly reduced. In contrast, if the minimum temperature of the top wall is kept at 600-1100°C by the heat-insulating structure, the temperature drop of the covering layer can be suppressed by the heat of the top wall while maintaining the covering layer in a stable state. Therefore, the liquid level of the molten glass can be stabilized, and the production efficiency of glass products can be improved.

[0014] (2) In the configuration of (1) above, the heat-insulating structure may include a heat-insulating layer provided on the outer side of the top wall.

[0015] In this way, the top wall can be reliably insulated and the minimum temperature of the top wall can be easily managed.

[0016] (3) In the configuration of (1) or (2) above, the heat-insulating structure may include a resistance heater.

[0017] In this way, the top wall can be reliably insulated and the minimum temperature of the top wall can be easily managed.

[0018] (4) In any one of the above-mentioned structures (1) to (3), the heat-insulating structure may include an induction heater.

[0019] In this way, the top wall can be reliably insulated and the minimum temperature of the top wall can be easily managed.

[0020] (5) In any one of the above structures (1) to (4), preferably, the melting step further includes: a measuring step of measuring the temperature of the top wall; and an adjusting step of adjusting the insulation temperature brought about by the insulation structure based on the temperature of the top wall measured in the measuring step.

[0021] In this way, it is easy to manage the minimum temperature of the top wall in detail.

[0022] (6) In any one of the above-mentioned structures (1) to (5), it is preferable that the lowest temperature of the ceiling wall is higher on the downstream side than on the upstream side of the melting furnace.

[0023] Gas generated by glass raw materials is more likely to be discharged in the bubble layer than in the material layer. As the amount of unmelted glass raw materials decreases from the upstream side of the melting furnace toward the downstream side, there is a tendency for the material layer to decrease and the bubble layer to increase on the downstream side of the melting furnace. Therefore, if the minimum temperature of the top wall is set higher on the downstream side than on the upstream side of the melting furnace, the gas can be efficiently discharged through the bubble layer on the downstream side of the melting furnace.

[0024] (7) The present invention made in order to solve the above-mentioned problems is a manufacturing device for glass products, which has a melting furnace that contains molten glass inside, and the manufacturing device for glass products is characterized in that the melting furnace has: a supply machine, which is arranged on the front wall of the melting furnace and supplies glass raw materials to the molten glass; an electrode, which is immersed in the molten glass and heats the glass raw materials to melt them; a discharge port, which is arranged on the rear wall of the melting furnace and discharges the molten glass; and a heat-insulating structure, which insulates the top wall of the melting furnace, and the heat-insulating structure is configured to keep the minimum temperature of the top wall at 600 to 1100°C.

[0025] In this way, the same effects as those of the corresponding structures already described can be enjoyed.

[0026] Effects of the Invention

[0027] According to the present invention, it is possible to suppress a decrease in the temperature of a coating layer covering the liquid surface of molten glass, stabilize the liquid surface level of molten glass, and improve the production efficiency of glass products. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view showing the manufacturing apparatus of the glass article according to the first embodiment of the present invention.

[0029] Figure 2 It is a cross-sectional view showing a manufacturing apparatus for a glass article according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same reference numerals are used for the corresponding components in each embodiment, so that repeated descriptions are sometimes omitted. In the case where only a part of the structure is described in each embodiment, the structure of other embodiments previously described can be applied to the other parts of the structure. In addition, not only the combination of structures explicitly described in the description of each embodiment, but also the structures of multiple embodiments can be partially combined with each other even if not explicitly described, as long as there is no particular obstacle in the combination.

[0031] (First embodiment)

[0032] like Figure 1 As shown in FIG. 1 , the manufacturing apparatus of the glass article according to the first embodiment includes a melting furnace 1 , a feeder 2 , and a forming apparatus (not shown).

[0033] The melting furnace 1 includes a bottom wall 1a, side walls 1b, and a ceiling wall 1c, and the components 1a to 1c define a space for storing the molten glass Gm. The side wall 1b includes a front wall 1b1 located on the upstream side and a rear wall 1b2 located on the downstream side.

[0034] In the melting furnace 1, the glass raw material Gr is melted to form a molten glass Gm. In addition to natural raw materials and chemically synthesized raw materials, the glass raw material Gr may also contain cullet. When the glass article is glass fiber, the molten glass Gm can be made of E glass, NE glass, C glass, S glass, T glass, or D glass. In addition, when the glass article is a glass substrate for a display, the molten glass Gm can be made of alkali-free glass. When the glass article is a cover glass for a display, etc., it can be made of aluminosilicate glass for chemical strengthening.

[0035] A plurality of rod-shaped electrodes 3 are provided on the bottom wall 1a of the melting furnace 1. The electrode 3 is not limited to a rod-shaped electrode, but may be a plate-shaped electrode, a block-shaped electrode, or a combination of these. In addition, the electrode 3 may also be provided on the side wall of the melting furnace 1 (for example, a side wall extending along the flow direction F described later). The electrode 3 is formed of molybdenum (Mo), for example. The electrode 3 is immersed in the molten glass Gm, and the molten glass Gm is electrically heated to melt the glass raw material Gr. The electrode 3 is held in a through hole provided in the bottom wall 1d while being held in a cylindrical electrode holder 4 having a cooling mechanism (not shown). That is, the electrode holder 4 is held in the bottom wall 1d, and the electrode 3 is held in the electrode holder 4. In this state, the electrode 3 can adjust the protruding length of the electrode 3 in the melting furnace 1 by changing the insertion length of the electrode 3 into the melting furnace 1. The number and configuration position of the electrode 3 can be appropriately changed according to the size of the melting furnace 1, etc.

[0036] It should be noted that in the present embodiment, a heating mechanism such as a burner for melting the glass raw material Gr is not provided in the space above the liquid level LS of the molten glass Gm in the melting furnace 1. That is, in the melting process described later, the present embodiment is a so-called all-electric melting method in which the glass raw material Gr is melted only by electrical heating performed by the electrode 3. It should be noted that a burner may also be used in the startup process (the process of heating the melting furnace from room temperature to a temperature at which the glass raw material can be melted) before starting the melting process.

[0037] A supply port 5 for supplying glass raw material Gr is provided on the front wall 1b1 of the melting furnace 1. A feeder 6 is provided at the supply port 5. In the present embodiment, the feeder 6 is a screw feeder. The feeder 6 may also be other known feeders such as a pusher and a vibration feeder. The number and arrangement position of the feeders 6 may be appropriately changed according to the size of the melting furnace 1, etc.

[0038] A discharge port 7 for discharging molten glass Gm is provided at the rear wall 1b2 of the melting furnace 1. The discharge port 7 is connected to the feeder 2, and the molten glass Gm is sequentially supplied from the melting furnace 1 to the feeder 2. In the melting furnace 1, the molten glass Gm flows along a flow direction F from the front wall 1b1 toward the rear wall 1b2.

[0039] The glass raw material Gr supplied by the supply machine 6 is melted by the electric heating performed by the electrode 3, and molten glass Gm is continuously generated. The liquid surface LS of the molten glass Gm is covered by the covering layer Gx. The covering layer Gx includes a material layer Ga formed by the glass raw material Gr and a bubble layer Gb formed along with the melting of the glass raw material Gr. The bubble layer Gb is formed along with the generation of carbon oxygen gas (CO, CO2), O2 gas, SO2 gas and other gases X caused by the glass raw material Gr. By covering the liquid surface LS of the molten glass Gm with the covering layer Gx in this way, the heat dissipation of the molten glass Gm can be suppressed. As a result, the temperature of the molten glass Gm can be reliably maintained, thereby achieving energy saving. It should be noted that in Figure 1 In the figure, the bubble layer Gb is shown to be formed only on the downstream side of the melting furnace 1, but it can also be formed on the upstream side of the melting furnace 1. Specifically, for example, the bubble layer Gb can be formed on both sides of the material layer Ga in the width direction (direction perpendicular to the flow direction F) on the upstream side of the melting furnace 1. In addition, the bubble layer Gb can also be formed between the material layer Ga and the liquid surface LS of the molten glass Gm.

[0040] The ceiling 1c of the melting furnace 1 is provided with a heat insulating layer 8 covering at least a portion of the outer wall surface of the ceiling 1c as a heat insulating structure for heat insulating the ceiling 1c. The heat insulating layer 8 is formed by stacking one or more layers of felt 8a. It should be noted that the illustrated example shows a state where three layers of felt 8a are stacked.

[0041] As the felt 8a, for example, a felt made of a fire-resistant fiber material can be used. Specifically, a felt having heat resistance and elasticity that can withstand a temperature of 1100° C. or higher (preferably 1150° C. or higher) can be used. For example, a felt made of alumina fiber, silica fiber, zirconia fiber, or a blended fiber thereof can be used.

[0042] In the present embodiment, the heat insulating layer 8 is provided to cover the entire region from the upstream side to the downstream side of the outer wall surface of the top wall 1c, but may be provided only on the downstream side of the top wall 1c, and its arrangement position may be changed as appropriate.

[0043] A thermometer (for example, a thermocouple) 9 capable of measuring the temperature of the ceiling wall 1 c is provided on the ceiling wall 1 c of the melting furnace 1 .

[0044] The feeder 2 is used to transfer the molten glass Gm formed by the melting furnace 1 to the forming device on the downstream side of the feeder 2. The feeder 2 includes a transfer path for transferring the molten glass Gm, a clarification chamber for clarification of the molten glass Gm, a homogenization chamber (stirring chamber) for stirring the molten glass Gm by a stirrer, etc. as needed.

[0045] The molding device (not shown) molds a glass article from the molten glass Gm supplied from the feeder 2. In the present embodiment, the glass article is a glass fiber.

[0046] When the glass article is glass fiber, for example, a bushing provided at the bottom of the feeder 2 can be used as the molding device. The bushing includes a plurality of nozzles for flowing out molten glass to mold the glass fiber.

[0047] Next, a method for producing a glass article according to the present embodiment will be described. In this method, the above-mentioned production apparatus is used.

[0048] like Figure 2 As shown, the method includes a supplying step, a melting step, a discharging step, a transferring step, and a forming step.

[0049] In the supply step, glass-making feedstock Gr is supplied from the supply machine 6 located on the upstream side of the melting furnace 1 onto the molten glass Gm accommodated in the melting furnace 1 .

[0050] In the melting process, the glass raw material Gr is melted by heating by the electrode 3 immersed in the molten glass Gm to obtain the molten glass Gm. At this time, the heating temperature of the electrode 3 and the temperature of the space above the liquid surface LS of the molten glass Gm in the melting furnace 1 are adjusted in such a way that a covering layer Gx including a material layer Ga and a bubble layer Gb is formed on the liquid surface LS of the molten glass Gm. It should be noted that in the melting process, combustion heating by a burner can also be used as an auxiliary. In this case, the ratio of the heat generated by the electrode to the total heat generated by the electrode and the burner is preferably 80% or more, more preferably 90% or more, and even more preferably 100%, that is, a full electric melting method.

[0051] The area A of the portion covered by the covering layer Gx in the liquid surface LS of the molten glass Gm in the melting furnace 1 is preferably 80% or more of the entire area B of the liquid surface LS of the molten glass Gm in the melting furnace 1, and more preferably 90% or more. On the other hand, the upper limit of the area A can be 100% or less of the area B, and more preferably 98% or less. In addition, the area C covered by the bubble layer Gb in the liquid surface LS of the molten glass Gm in the melting furnace 1 is preferably 5 to 50% of the area D of the portion covered by the material layer Ga in the liquid surface LS of the molten glass Gm in the melting furnace 1. The area C is more preferably 10 to 40% of the area D, and further preferably 15 to 30%.

[0052] In addition, in the melting process, the minimum temperature of the top wall 1c is kept at 600 to 1100°C by the heat insulating layer 8. Here, when the minimum temperature of the top wall 1c becomes less than 600°C by the action of the heat insulating layer 8, the temperature (viscosity) of the cover layer Gx covering the liquid surface LS of the molten glass Gm decreases, and the gas X generated along with the melting of the glass raw material Gr is difficult to be discharged from the cover layer Gx. On the other hand, when the minimum temperature of the top wall 1c exceeds 1100°C by the action of the heat insulating layer 8, part of the cover layer Gx disappears, etc., and there is a possibility that the thermal efficiency of the melting furnace 1 is significantly reduced. In contrast, if the minimum temperature of the top wall 1c is kept at 600 to 1100°C by the heat insulating layer 8, the temperature drop of the cover layer Gx can be suppressed by the heat of the top wall 1c while maintaining the cover layer Gx in a stable state. Therefore, the gas X is easily discharged from the cover layer Gx to the upper space. As a result, the level of the liquid surface LS of the molten glass Gm is stabilized, and the production efficiency of glass products can be improved.

[0053] The minimum temperature of the top wall 1c is more preferably 600 to 1000°C, and further preferably 600 to 800°C. The maximum temperature of the top wall 1c is preferably 700 to 1100°C, more preferably 750 to 1050°C, and further preferably 800 to 1000°C.

[0054] As for the minimum temperature of the top wall 1c, it is preferably higher on the downstream side than on the upstream side of the melting furnace 1. Here, "the upstream side of the melting furnace 1" means, for example, an area on the upstream side of the position where the inside of the melting furnace 1 is divided into two halves along the flow direction F, and "the downstream side of the melting furnace 1" means, for example, an area on the downstream side of the position where the inside of the melting furnace 1 is divided into two halves along the flow direction F. As for the gas X, it is easier to discharge in the bubble layer Gb than in the material layer Ga. The unmelted glass raw material Gr gradually decreases from the upstream side of the melting furnace 1 to the downstream side, so there is a tendency for the material layer Ga to decrease and the bubble layer Gb to increase on the downstream side of the melting furnace 1. Therefore, if the minimum temperature of the top wall 1c is set to be higher on the downstream side than on the upstream side of the melting furnace 1, the gas X can be efficiently discharged through the bubble layer Gb on the downstream side of the melting furnace 1.

[0055] The temperature difference (T1-T2) between the lowest temperature T1 of the ceiling wall 1c on the downstream side of the melting furnace and the lowest temperature T2 of the ceiling wall 1c on the upstream side of the melting furnace 1 varies greatly depending on the length of the melting furnace (the dimension in the flow direction F), but is preferably 10°C or more, more preferably 15°C or more, and further preferably 20°C or more. On the other hand, the upper limit of the temperature difference is, for example, preferably 500°C or less, more preferably 450°C or less, and further preferably 400°C or less.

[0056] In the melting process, the temperature of the top wall 1c may be measured by the thermocouple 9, and the heat insulation temperature provided by the heat insulation layer 8 may be adjusted based on the measured temperature. As a method of adjusting the heat insulation temperature provided by the heat insulation layer 8, for example, the number of stacked sheets of the felt 8a or the arrangement position of the felt 8a may be changed. In this way, the minimum temperature of the top wall 1c can be accurately managed.

[0057] In the discharging step, the molten glass Gm is discharged from the discharge port 7 on the downstream side of the melting furnace 1 , and the molten glass Gm is supplied to the feeder 2 .

[0058] In the transfer step, the molten glass Gm formed in the melting furnace 1 is transferred to the forming device by the feeder 2 .

[0059] In the forming step, glass fibers as a glass article are formed from the molten glass Gm using a forming device.

[0060] (Second embodiment)

[0061] In the second embodiment, a modified example of the heat-insulating structure of the top wall 1c in the manufacturing apparatus and the manufacturing method of the glass article is illustrated. Figure 2 As shown, in this embodiment, a heater 21 is provided inside the top wall 1c as a heat-retaining structure.

[0062] As the heater 21, for example, a resistance heater or an induction heater can be used. In the case where a plurality of heaters 21 are provided, a resistance heater and an induction heater can also be used simultaneously. Among the resistance heaters, for example, SiC heaters, molybdenum disilicide heaters, metal heaters, etc. can be used. Among the metal heaters, for example, heaters made of iron alloy, chromium alloy, nickel alloy, aluminum alloy, platinum, platinum alloy, tungsten, etc. can be used.

[0063] The heater 21 keeps the minimum temperature of the top wall 1c at 600 to 1100°C during the melting step. During the melting step, the temperature of the top wall 1c may be measured by the thermocouple 9, and the heating temperature (keeping temperature) by the heater 21 may be adjusted based on the measured temperature.

[0064] In the present embodiment, the heater 21 is provided only on the downstream side of the outer wall surface of the ceiling wall 1c, but may be provided on both the upstream side and the downstream side of the ceiling wall 1c, and the arrangement position thereof may be changed as appropriate.

[0065] The arrangement of the heater 21 is not particularly limited as long as it can keep the top wall 1c warm. For example, a portion of the heater 21 disposed inside the top wall 1c may be exposed inside the top wall 1c (inside the furnace). Alternatively, the heater 21 may be disposed outside the top wall 1c (outside the furnace).

[0066] It should be noted that the present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. The present invention can be modified in various ways without departing from the gist of the present invention.

[0067] In the above-described embodiment, as the heat-insulating structure of the ceiling wall 1 c , the heat-insulating layer 8 including the felt 8 a and the heater 21 may be used simultaneously.

[0068] In the above embodiment, the glass article is described as glass fiber, but the glass article can be, for example, glass balls, glass tubes, glass blocks, plate glass, glass rolls, etc., or any other shape. When the glass article is plate glass or glass roll, as a forming device, for example, a down-draw method such as overflow down-draw method, a float method, etc. can be used.

[0069] In the above-mentioned embodiment, the number of stacked sheets of the felt 8a covering the outer wall surface of the ceiling 1c may be greater on the downstream side than on the upstream side of the melting furnace 1. Alternatively, the outer wall surface of the ceiling 1c may be covered with the felt 8a from the upstream side to the downstream side and the heater 21 may be provided only on the downstream side of the ceiling 1c. In this way, it is easy to make the lowest temperature of the ceiling 1c higher on the downstream side than on the upstream side of the melting furnace 1.

[0070] Example

[0071] Hereinafter, the glass article of the present invention will be described based on Examples. It should be noted that the following Examples are merely illustrative, and the present invention is not limited to the following Examples in any way.

[0072] In Comparative Example 1, no heat-insulating structure was provided on the top wall of the melting furnace. On the other hand, in Example 1, a layer of felt (silica fiber) was provided as a heat-insulating structure on the top wall of the melting furnace so as to cover the entire outer wall surface of the top wall (see Figure 1 In Example 2, as a heat-insulating structure of the top wall of the melting furnace, a resistance heater is provided only on the top wall on the downstream side of the melting furnace (refer to Figure 2In Example 3, as the heat insulation structure of the top wall of the melting furnace, three layers of felt (silica fiber) are provided in a manner covering the entire outer wall surface of the top wall (refer to Figure 1 ).

[0073] For each of Comparative Example 1 and Examples 1 to 3, a supply process, a melting process, and a discharge process were performed, and the temperature of the top wall, the standard deviation of the liquid level of the molten glass, and the relative flow rate of the molten glass at this time were measured. The relative flow rate of the molten glass was measured based on the flow rate of Comparative Example 1. The flow rate of the molten glass was calculated based on the obtained glass article. These measurement results are shown in Table 1.

[0074] Table 1

[0075]

[0076] In Comparative Example 1 in which the heat-insulating structure is not provided on the top wall, the minimum temperature of the top wall is less than 600° C. In contrast, in Examples 1 to 3 in which the heat-insulating structure is provided on the top wall, the minimum temperature of the top wall can be maintained in the range of 600 to 1100° C. Moreover, in all Examples 1 to 3, the fluctuation of the liquid level of the molten glass is suppressed compared with Comparative Example 1. In addition, in Examples 1 to 3, the flow rate of the molten glass can be gradually increased as the minimum temperature of the top wall increases.

[0077] Description of Reference Numerals

[0078] 1 Melting furnace

[0079] 1a Bottom wall

[0080] 1b Sidewall

[0081] 1b1 Anterior wall

[0082] 1b2 Back wall

[0083] 1c Top wall

[0084] 1d Bottom wall

[0085] 2 feeder

[0086] 3 Electrodes

[0087] 4 Electrode holder

[0088] 5 Supply port

[0089] 6 Feeder

[0090] 7 Exhaust port

[0091] 8 Insulation

[0092] 8a Felt

[0093] 9 Thermocouple

[0094] 21 Heater

[0095] Ga layer

[0096] Gb Bubble layer

[0097] Gm Molten glass

[0098] Gr Glass Raw Materials

[0099] Gx Overlay

[0100] LS Liquid Level

[0101] X-gas.

Claims

1. A method for manufacturing a glass article, comprising: A supplying step of supplying glass raw materials from an upstream side of the melting furnace onto the molten glass contained in the melting furnace; a melting step of melting the glass raw material to obtain the molten glass by heating with electrodes immersed in the molten glass; and a discharging step of discharging the molten glass from the downstream side of the melting furnace. The method for manufacturing the glass article is characterized in that: The melting furnace includes a heat-insulating structure for insulating a top wall of the melting furnace. In the melting process, a covering layer including a material layer and a bubble layer is formed to cover the liquid surface of the molten glass, and the minimum temperature of the top wall is kept at 600-1100° C. by the heat-insulating structure.

2. The method for manufacturing a glass article according to claim 1, wherein: The heat-insulating structure includes a heat-insulating layer provided on the outer side of the top wall.

3. The method for manufacturing a glass article according to claim 1 or 2, wherein: The heat-insulating structure includes a resistance heater.

4. The method for manufacturing a glass article according to claim 1 or 2, wherein: The heat-insulating structure includes an induction heater.

5. The method for manufacturing a glass article according to claim 1 or 2, wherein: The melting step further includes: a measuring step of measuring the temperature of the top wall; and an adjusting step of adjusting the heat-retaining temperature by the heat-retaining structure based on the temperature of the top wall measured in the measuring step.

6. The method for manufacturing a glass article according to claim 1 or 2, wherein: The lowest temperature of the top wall is higher on the downstream side than on the upstream side of the melting furnace.

7. A device for manufacturing glass articles, comprising a melting furnace for accommodating molten glass inside, The manufacturing device of the glass article is characterized in that: The melting furnace comprises: a feeder, which is arranged on the front wall of the melting furnace and supplies glass raw materials to the molten glass; an electrode, which is immersed in the molten glass and heats and melts the glass raw materials; a discharge port, which is arranged on the rear wall of the melting furnace and discharges the molten glass; and a heat-insulating structure, which keeps the top wall of the melting furnace warm. The heat-insulating structure is configured to keep the minimum temperature of the top wall at 600-1100°C.

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