Method for manufacturing glass articles, and apparatus for manufacturing glass articles

Abstract

This suppresses improper erosion of the side walls of the melting furnace, thereby increasing the durability of the melting furnace and reducing energy efficiency losses during the melting process. [Solution] The method for manufacturing glass articles comprises a supply step of supplying glass raw material Ga from the upstream side of a melting furnace 2, a melting step of continuously producing molten glass Gm by heating and melting the supplied glass raw material Ga in the melting furnace 2, an outflow step of letting the continuously produced molten glass Gm flow out from the downstream side of the melting furnace 2, and a cooling step of cooling the side wall 2c of the melting furnace 2 using a refrigerant. In the cooling step, the cooling capacity obtained by the refrigerant is relatively higher in the downstream region 2cy of the side wall 2c than in the upstream region 2cx.

Description

Technical Field

[0001] The present invention relates to a technique for manufacturing glass articles using a melting furnace.

Background Art

[0002] As is well known, in a method for manufacturing glass articles, a supply step of supplying glass raw materials from the upstream side of a melting furnace, a melting step of continuously generating molten glass by heating and melting the supplied glass raw materials in the melting furnace, and an outflow step of causing the continuously generated molten glass to flow out from the downstream side of the melting furnace are performed. Then, the molten glass flowing out from the downstream side of the melting furnace is transferred to a forming device by a feeder or the like, formed into a predetermined shape, and then becomes a glass article as a final product.

[0003] Further, the melting furnace includes a bottom and a ceiling portion extending from the upstream end portion to the downstream end portion, a pair of side walls extending from the upstream end portion to the downstream end portion between these, and a pair of end walls disposed at the upstream end portion and the downstream end portion of this pair of side walls.

[0004] The side walls are generally formed of refractory bricks. Therefore, in the process where the heating and melting of the glass raw materials are continuously performed in the melting step, the inner surface of the side walls is eroded. In this case, suppressing the erosion of the inner surface of the side walls is an important matter in the design of the melting furnace, the quality control of the molten glass, and thus the quality control of the glass articles.

[0005] Therefore, Patent Document 1 discloses that by blowing a refrigerant (cooling air) over the entire area of the side walls, the temperature (atmosphere temperature) inside the melting furnace can be kept constant without being affected by changes in the outside air temperature or the like. According to this, it is expected that the temperature of the molten glass inside the melting furnace can also be kept constant.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] As disclosed in Patent Document 1, the method of cooling the entire side wall involves blowing a refrigerant of the same flow rate and temperature over the entire side wall. However, the temperature of the side wall of a melting furnace is not uniform, and tends to be higher downstream than upstream. As a result, excessive erosion may occur in the downstream region of the side wall due to contact with molten glass. To prevent this, increasing the flow rate of the refrigerant or lowering the temperature of the refrigerant over the entire side wall will lower the ambient temperature inside the melting furnace and the temperature of the molten glass. To address this, if these temperatures are to be maintained at a constant temperature required for the melting process, the energy used in the melting process will increase significantly, leading to a loss of energy efficiency.

[0008] From the above perspective, the object of the present invention is to suppress improper erosion of the side walls of the melting furnace, thereby increasing the durability of the melting furnace, while reducing the loss of energy efficiency in the melting process. [Means for solving the problem]

[0009] (1) The first aspect of the present invention, which was devised to solve the above problems, is a method for manufacturing a glass article comprising: a supply step of supplying glass raw materials from the upstream side of a melting furnace; a melting step of continuously producing molten glass by heating and melting the supplied glass raw materials in the melting furnace; an outflow step of discharging the continuously produced molten glass from the downstream side of the melting furnace; and a cooling step of cooling the side wall of the melting furnace using a refrigerant, wherein in the cooling step, the cooling capacity obtained by the refrigerant is relatively higher in the downstream region of the side wall than in the upstream region.

[0010] This configuration allows for sufficient cooling of the downstream region of the sidewall, where erosion by molten glass is likely to be significant, using a refrigerant, thereby suppressing improper erosion of the sidewall. Furthermore, it improves the durability of the melting furnace. Moreover, since the cooling capacity for the upstream region of the sidewall can be reduced or eliminated, there is no need to significantly increase the energy used in the melting process. This also reduces the loss of energy efficiency in the melting process.

[0011] (2) In the configuration of (1) above, the flow rate of the refrigerant may be relatively higher in the downstream region of the side wall than in the upstream region during the cooling process.

[0012] In this way, differences in refrigerant flow rates can be translated into differences in cooling capacity. Therefore, the same effects and advantages as those obtained with the configuration described in (1) above can be obtained.

[0013] (3) In the configuration of (1) or (2) above, the temperature of the refrigerant may be relatively lower in the downstream region of the side wall than in the upstream region during the cooling process.

[0014] In this way, differences in refrigerant temperature can be converted into differences in cooling capacity. Therefore, the same effects and advantages as those obtained with the configuration described in (1) above can be obtained. Alternatively, differences in both refrigerant temperature and the refrigerant flow rate may be used to convert into differences in cooling capacity.

[0015] (4) In any of the configurations (1) to (3) above, the melting process may be carried out primarily by heating and melting the glass raw material with electrodes.

[0016] This allows for precise and meticulous temperature control of the molten glass during the melting process, which is advantageous in obtaining the effects of the configuration described in (1) above.

[0017] (5) In any of the configurations described in (1) to (4) above, the electrodes may be provided on the side wall, bottom, or top side of the melting furnace and immersed in the molten glass.

[0018] In this way, the molten glass can be suitably heated by electrical current using electrodes.

[0019] (6) In any of the above configurations (1) to (5), the configuration may further include a modification step to change the immersion length of the electrode provided on the bottom or top side of the melting furnace into the molten glass.

[0020] In this way, if there is a risk that erosion on the sidewall will be particularly large in a part of the sidewall, the immersion length of some or all of the electrodes in the molten glass is changed in advance during the modification process. In this case, when the molten glass is heated by electric current using the electrodes, the erosion of the sidewall by the molten glass progresses most rapidly at a height position near the tip of the electrode. Therefore, by appropriately changing the immersion length of the electrodes, the erosion of the sidewall will progress evenly. This avoids problems such as loss of energy efficiency due to excessive heat dissipation from the sidewall caused by improper erosion of the sidewall. Furthermore, this also improves the durability of the melting furnace.

[0021] (7) In any of the configurations described in (1) to (6) above, multiple electrodes are provided on the bottom or top side of the melting furnace, extending from the upstream side to the downstream side of the melting furnace, and the distance between the electrode located on the downstream side of the melting furnace and the downstream side of the side wall may be longer than the distance between the electrode located on the upstream side of the melting furnace and the upstream side of the side wall.

[0022] By doing so, the distance from the downstream region of the side wall, which is a location where erosion by molten glass can be significant, to the electrode becomes relatively long. As a result, the temperature rise in the downstream region of the side wall is suppressed, and improper erosion in the downstream region of the side wall is inhibited. Therefore, the heat dissipation amount from the side wall can be reduced, and the energy efficiency loss in the melting process can be decreased. Moreover, since the distance from the upstream region of the side wall to the electrode becomes relatively short, the temperature drop in the upstream region of the side wall is suppressed. Thus, it is not necessary to significantly increase the energy used in the melting process. This also enables the reduction of the energy efficiency loss in the melting process. From the above viewpoints, according to the configuration here, even without the above-described cooling process, the problems of the present invention can be solved, and substantially the same operational effects as those in the case of the configuration of (1) above can be obtained. Also, if both the configuration here and the configuration of (1) above are provided, the operational effects by the configuration of (1) above will be doubled.

[0023] (8) A second aspect of the present invention devised to solve the above problems is a manufacturing apparatus for glass articles, comprising a melting furnace configured to continuously generate molten glass by supplying glass raw materials from the upstream side and heating and melting the supplied glass raw materials, and causing the continuously generated molten glass to flow out from the downstream side, and a cooling mechanism for cooling the side wall of the melting furnace using a refrigerant, wherein the cooling mechanism is characterized in that the cooling capacity obtained by the refrigerant is relatively higher in the downstream region of the side wall than in the upstream region of the side wall.

[0024] According to an apparatus having such a configuration, substantially the same operational effects as those in the case of the configuration of (1) above can be obtained.

Effects of the Invention

[0025] According to the present invention, improper erosion of the side wall of the melting furnace can be suppressed, the durability of the melting furnace can be enhanced, and the energy efficiency loss in the melting process can be reduced.

Brief Description of the Drawings

[0026] [Figure 1]This is a schematic side view showing the overall configuration of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 2] A longitudinal cross-sectional side view showing a melting furnace, which is a component of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 3] This is a cross-sectional plan view taken along line AA in Figure 2, showing a melting furnace and a cooling mechanism, which are components of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 4] A perspective view showing a melting furnace and a cooling mechanism, which are components of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 5] A perspective view showing a melting furnace and a cooling mechanism, which are components of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 6] This is a cross-sectional plan view showing a melting furnace and a cooling mechanism, which are components of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 7] A longitudinal front view showing the operation of a glass article manufacturing apparatus according to an embodiment of the present invention. [Figure 8] This is a cross-sectional plan view showing a melting furnace, which is a component of a glass article manufacturing apparatus according to a modified embodiment of the present invention. [Modes for carrying out the invention]

[0027] Hereinafter, a manufacturing apparatus for glass articles and a method for manufacturing glass articles according to embodiments of the present invention will be described with reference to the attached drawings.

[0028] Figure 1 illustrates a schematic configuration of a glass article manufacturing apparatus according to an embodiment of the present invention. As shown in the figure, the manufacturing apparatus 1 comprises, in order from the upstream side, a melting furnace 2, a clarification tank 3, a stirring tank 4, a conditioning tank 5, and a molding apparatus 6. These parts 2 to 6 are connected by transfer pipes 7 to 10.

[0029] The melting furnace 2 heats the glass raw material to produce molten glass Gm (the detailed configuration of the melting furnace 2 will be described later). The clarification tank 3 clarifies the molten glass Gm produced in the melting furnace 2. The stirring tank 4 homogenizes the clarified molten glass Gm by stirring it. The conditioning tank 5 adjusts the viscosity and flow rate of the molten glass Gm cooled in the transfer pipe 9.

[0030] The molding apparatus 6 processes molten glass Gm into a desired shape. In this embodiment, the molding apparatus 6 processes molten glass Gm into a plate shape by the overflow downdraw method to obtain a glass plate as a glass article. This molding apparatus 6 includes a molded body 11 with a roughly wedge-shaped cross-section (cross-sectional shape perpendicular to the plane of the paper) and an overflow groove formed at the top. Molten glass Gm transported by the transfer pipe 10 is supplied to the overflow groove of the molded body 11, overflows from the overflow groove, and flows down along both sides of the molded body 11 (both sides located on the front and back sides of the plane of the paper). This flowing molten glass Gm fuses at the lower tops of both sides and is formed into a plate shape.

[0031] The glass plate obtained after molding has a thickness of, for example, 30 μm to 1000 μm (preferably 50 μm to 400 μm) and is used as a substrate or protective cover for panel displays such as liquid crystal displays and organic EL displays, organic EL lighting, and solar cells. The molding apparatus 6 may also perform other down-draw methods such as the slot down-draw method or the float method. When the glass plate is used as a substrate, the glass composition can be alkali-free glass, and when the glass plate is used as a protective cover, if the glass composition is alkali-containing aluminosilicate glass, it becomes suitable as a glass plate for chemical strengthening.

[0032] Transfer tubes 7-10 are made of cylindrical tubes, for example, platinum or a platinum alloy. Transfer tubes 7-10 are electrically heated as needed.

[0033] Figure 2 is a longitudinal cross-sectional view showing the configuration of the melting furnace 2, Figure 3 is a cross-sectional view along line AA of Figure 2, and Figure 4 is a perspective view showing the main parts of the melting furnace 2. In each of these figures, the direction of arrow X is the upstream side, and the direction of arrow Y is the downstream side (the same applies to other figures described later). In the following explanation, the directions along arrows X and Y in each of these figures are referred to as the upstream and downstream directions, and the direction along arrow Z in each of these figures is referred to as the width direction (the same applies to other figures described later).

[0034] As shown in Figures 2 and 3, the melting furnace 2 comprises a bottom (only the bottom wall 2a is shown in the figures), a top (only the top wall 2b is shown in the figures), a pair of side walls 2c, and a pair of end walls 2d. The bottom wall 2a, the top wall 2b, and the pair of side walls 2c all extend from the upstream end to the downstream end of the melting furnace 2. The pair of end walls 2d are located at the upstream end and the downstream end of the melting furnace 2, respectively.

[0035] The bottom wall 2a, the top wall 2b, the pair of side walls 2c, and the pair of end walls 2d are all made of refractory bricks. Examples of refractory bricks used for the bottom wall 2a, the side walls 2c, and the end walls 2d include zirconia-based electroformed bricks, alumina-based electroformed bricks, alumina-zircon-based electroformed bricks, AZS (Al-Ze-Si)-based electroformed bricks, and dense-fired bricks.

[0036] As shown in Figure 2, a screw feeder 12 is provided as a raw material supply device on the upstream side (upstream end in the example shown) of the melting furnace 2. The screw feeder 12 sequentially supplies glass raw material (solid raw material) Ga to the liquid level GmL of molten glass Gm in the melting furnace 2.

[0037] The raw material supply device 12 may be a pusher or a vibrating feeder. In addition, the illustrated example shows a so-called semi-hot top type in which a portion of the liquid surface GmL of the molten glass Gm (the downstream portion) is not covered by the glass raw material, but it may also be a so-called cold top type in which the entire area of ​​the liquid surface GmL of the molten glass Gm is covered by the glass raw material Ga.

[0038] An outlet 2e for discharging molten glass Gm is provided on the downstream side of the melting furnace 2 (the downstream end in the diagram). The outlet 2e is connected to the transfer pipe 7.

[0039] The melting furnace 2 continuously produces molten glass Gm by heating and melting the glass raw material Ga through electric heating. Multiple electrodes 13 for wire heating are provided on the bottom wall 2a of the melting furnace 2. The multiple electrodes 13 are immersed in the molten glass Gm.

[0040] In this embodiment, the melting furnace 2 does not have any heating means other than the electrode 13 (e.g., a burner), and the glass raw material Ga is heated and melted (total electromelting) solely by the energizing (electrical energy) of the electrode 13. However, the energizing of the electrode 13 may be used in combination with other heating means.

[0041] When the glass raw material Ga is heated and melted primarily by energizing electrode 13, the ambient temperature inside the melting furnace 2 can be reduced, and consequently, the amount of heat radiated from the ceiling wall 2b of the melting furnace 2 can be reduced. Therefore, from the viewpoint of improving energy efficiency, it is preferable to heat and melt the glass raw material Ga primarily by energizing electrode 13. In this case, as the ambient temperature inside the melting furnace 2 is reduced, the temperature difference between the molten glass Gm at the liquid surface GmL and the molten glass Gm around the bottom wall 2a becomes larger. As a result, the convection of the molten glass Gm becomes more intense, and the side wall 2c becomes more susceptible to erosion. In this case, the effect of suppressing improper erosion of the side wall 2c of the melting furnace 2 according to this embodiment, and the effect of reducing the loss of energy efficiency in the melting process, become even more pronounced.

[0042] Here, "primarily heating and melting the glass raw material Ga by electrode 13" means, for example, that 80% or more of the total energy supplied to the melting furnace 2 is energy supplied by the electric heating of electrode 13. Preferably, the proportion of energy supplied by the electric heating of electrode 13 to the total energy supplied to the melting furnace 2 is 90% or more, more preferably 95% or more, and even more preferably 100%. Even when heating and melting the glass raw material primarily by electrode 13, other heating means may be used in combination when starting up the melting furnace 2.

[0043] As shown in Figures 3 and 4, the manufacturing apparatus 1 is equipped with a cooling mechanism 14 for cooling each of the pair of side walls 2c. Each pair of cooling mechanisms 14 includes a tubular duct 14a to which a refrigerant is supplied under pressure from a fan chamber (not shown) located below the melting furnace 2, and a plurality of discharge pipes 14b leading to the duct 14a. In this embodiment, cooling air Ai, one of the cooling fluids, is used as the refrigerant. The temperature of the cooling air Ai is set to be lower than the ambient temperature outside the melting furnace 2.

[0044] The fan chamber is divided into two sections, with one fan chamber connected to one duct 14a and the other fan chamber connected to the other duct 14a. In each fan chamber, the temperature of the cooling air Ai supplied to both ducts 14a is controlled by mixing and adjusting warm air (air with a relatively higher temperature) and cold air (air with a relatively lower temperature). In this case, the temperature of the cooling air Ai supplied to one duct 14a and the other duct 14a is controlled to be the same.

[0045] Furthermore, the configuration in which one fan chamber leads to one duct 14a and one duct 14a leads to multiple discharge pipes 14b is identical to the configuration in which the other fan chamber leads to the other duct 14a and the other duct 14a leads to multiple discharge pipes 14b; therefore, in the following explanation, only one configuration will be mentioned.

[0046] Cooling of the side wall 2c by the cooling mechanism 14 is performed as follows: Cooling air Ai is discharged from multiple discharge pipes 14b leading to the duct 14a toward the outer surface 2ca of the side wall 2c. Therefore, the cooling air Ai is discharged toward the entire area of ​​the outer surface 2ca of the side wall 2c, from the upstream side to the downstream side. In the illustrated example, the upstream and downstream arrangement pitch of the multiple discharge pipes 14b relative to the duct 14a is the same.

[0047] In this case, each of the multiple discharge pipes 14b is provided with a flow rate adjustment valve at the connection point to the duct 14a. These flow rate adjustment valves are located, for example, inside the position indicated by the symbol V in Figure 4. By changing the opening degree of these flow rate adjustment valves, the flow rate of the cooling air Ai discharged from each discharge pipe 14b is adjusted.

[0048] Here, the side wall 2c is divided into an upstream region 2cx and a downstream region 2cy. In this embodiment, the boundary between the upstream region 2cx and the downstream region 2cy of the side wall 2c is located at the center of the distance from the upstream end to the downstream end of the side wall 2c. Then, on the inner surface 2cb of the side wall 2c shown in Figure 3, greater erosion occurs in the downstream region 2cy compared to the upstream region 2cx.

[0049] To address this problem, the cooling capacity of the cooling mechanism 14 shown in Figures 3 and 4 is set to be relatively higher in the downstream region 2cy of the side wall 2c than in the upstream region 2cx. More specifically, among the multiple discharge pipes 14b, the opening of the flow control valve corresponding to the discharge pipe 14b of the downstream region Ey, which discharges cooling air Ai toward the downstream region 2cy of the side wall 2c, is set to be larger than the opening of the flow control valve corresponding to the discharge pipe 14b of the upstream region Ex, which discharges cooling air Ai toward the upstream region 2cx of the side wall 2c. It should be noted that the aforementioned large erosion does not necessarily occur throughout the entire downstream region 2cy of the side wall 2c, but may occur only in a part of the downstream region 2cy of the side wall 2c (for example, a part near the downstream end).

[0050] In this case, the opening of the flow control valve corresponding to the discharge pipe 14b in the downstream area Ey is set to 2 to 5 times the opening of the flow control valve corresponding to the discharge pipe 14b in the upstream area Ex. It is preferable, however, that the opening of all flow control valves corresponding to the discharge pipe 14b in the downstream area Ey is greater than the opening of all flow control valves corresponding to the discharge pipe 14b in the upstream area Ex, but this is not required. However, the total opening of the flow control valves corresponding to the discharge pipe 14b in the downstream area Ey must be 2 to 5 times the total opening of the flow control valves corresponding to the discharge pipe 14b in the upstream area Ex.

[0051] Therefore, the total flow rate of cooling air Ai discharged from the discharge pipe 14b in the downstream area Ey is 2 to 5 times the total flow rate of cooling air Ai discharged from the discharge pipe 14b in the upstream area Ex. Cooling the side wall 2c in this manner suppresses undue erosion of the downstream area 2cy of the side wall 2c.

[0052] Here, the discharge pipe 14b of the upstream area Ex and the discharge pipe 14b of the downstream area Ey may be separated at a position corresponding to the central position in the upstream-downstream direction of the side wall 2c, or at a position shifted downstream or upstream from the position corresponding to the central position. The separation position between the upstream area Ex and the downstream area Ey is preferably within the range of 30% to 70% of the distance from the upstream end to the downstream end, with the upstream end as the starting point (0%), and more preferably within the range of 50% to 70%. However, it is preferable that the average flow rate of cooling air Ai discharged from the discharge pipe 14b of the downstream area Ey to the downstream region 2cy of the side wall 2c is 2 to 5 times the average flow rate of cooling air Ai discharged from the discharge pipe 14b of the upstream area Ex to the upstream region 2cx of the side wall 2c. Here, the average flow rate means the flow rate per unit area of ​​the side wall 2c.

[0053] In the above-described configuration for differentiating the cooling capacity for the side wall 2c, cooling air Ai is discharged from both the discharge pipe 14b of the upstream area Ex and the discharge pipe 14b of the downstream area Ey. However, it is also possible to discharge cooling air Ai only from the discharge pipe 14b of the downstream area Ey, without discharging any cooling air Ai from the discharge pipe 14b of the upstream area Ex. Therefore, in this case, the discharge pipe 14b of the downstream area Ey does not need to be provided. Alternatively, cooling air Ai may be discharged from a portion of the discharge pipe 14b of the upstream area Ex.

[0054] Furthermore, as another way to differentiate the cooling capacity for the side wall 2c, as shown in Figures 5 and 6, the upstream and downstream arrangement pitch of the multiple discharge pipes 14b relative to the duct 14a may be made denser in the downstream area Ey and sparser in the upstream area Ex. In this case, even without providing a flow rate adjustment valve, the total flow rate of cooling air Ai discharged from the discharge pipes 14b in the downstream area Ey can be made greater than the total flow rate of cooling air Ai discharged from the discharge pipes 14b in the upstream area Ex. In this case, it is preferable that the number of discharge pipes 14b discharging cooling air Ai into the downstream area 2cy of the side wall 2c be, for example, 2 to 5 times greater than the number of discharge pipes 14b discharging cooling air Ai into the upstream area 2cx of the side wall 2c. In this case, the dividing position between the upstream area Ex and the downstream area Ey is the same as described above.

[0055] Furthermore, instead of, or in conjunction with, differentiating the flow rates of cooling air Ai discharged between the upstream area Ex and the downstream area Ey as described above, the temperature of the cooling air Ai discharged from the discharge pipe 14b of the downstream area Ey may be lower than that of the cooling air Ai discharged from the discharge pipe 14b of the upstream area Ex. In this case, measures such as separating the duct 14a between the upstream area Ex and the downstream area Ey and supplying cooling air Ai with different mixing ratios of warm air and cold air separately to the upstream area Ex and the downstream area Ey of the duct 14a can be taken. In this case, the separation point between the upstream area Ex and the downstream area Ey is the same as in the previously described case.

[0056] In this manufacturing apparatus 1, the following measures are taken to further suppress erosion of the side wall 2c.

[0057] Figure 7 is a front cross-sectional view exaggerating the erosion of the inner surfaces 2cb of a pair of side walls 2c. As shown in the figure, electrodes 13 are provided on the bottom wall 2a of the melting furnace 2, and the electrodes 13 are immersed in the molten glass Gm with their extensions extending upward. In this example, for convenience, there are two electrodes 13 in the width direction (arranged in two rows in the upstream and downstream directions).

[0058] In the state shown in the figure, when the molten glass Gm is heated by current using the electrode 13, the erosion of the side wall 2c by the molten glass Gm progresses most rapidly at a height position near the tip (upper end) 13a of the electrode 13. Therefore, when the upper end 13a of the electrode 13 is at the height position shown by the solid line in the figure, the greatest erosion occurs near the position labeled W on the inner surface 2cb of the side wall 2c. To prevent such large erosion from occurring on the inner surface 2cb of the side wall 2c, the immersion length of the electrode 13 in the molten glass Gm is lengthened or shortened as shown by the dashed line (the dashed line labeled 13a).

[0059] As described above, changing the immersion length of the electrode 13 in the molten glass Gm changes the positional relationship between the upper end 13a of the electrode 13 and the height of the side wall 2c. It is preferable to change the immersion length of the electrode 13 at intervals of 3 months to 2 years, or at intervals of 6 months to 1 year and 6 months. Furthermore, it is preferable that the change in the electrode 13 length each time be 10% to 15% of the height of the internal space of the melting furnace 2. By changing the immersion length of the electrode 13 in the molten glass Gm in this way, the inner surface 2cb of the side wall 2c becomes uniformly eroded, as shown by the dashed line (dashed line with reference numeral 2cd) in the figure. As a result, improper erosion of the side wall 2c is suppressed. The effect of suppressing erosion of the side wall 2c in this case is particularly noticeable in the downstream region 2cy of the side wall 2c, but can also be obtained in the upstream region 2cx of the side wall 2c.

[0060] The modification of the immersion length of the electrode 13 as described above is not limited to the case where the electrode 13 is provided on the bottom wall 2a, but can also be performed in the same manner when the electrode 13 is provided on the ceiling wall 2b side and immersed in the molten glass Gm while extending downwards.

[0061] Next, a method for manufacturing a glass article according to an embodiment of the present invention will be described.

[0062] This manufacturing method comprises a supply step, a melting step, a discharge step, a cooling step, and a modification step.

[0063] The supply process involves supplying the glass raw material Ga into the melting furnace 2 from the upstream side of the melting furnace 2 using the raw material supply device 12 shown in Figure 2.

[0064] The melting process is a process of continuously producing molten glass Gm by heating and melting the glass raw material Ga supplied in the supply process in the melting furnace 2.

[0065] The discharge process involves discharging the molten glass Gm, which is continuously generated in the melting furnace 2, into the transfer pipe 7 from the downstream side of the melting furnace 2.

[0066] The cooling process involves cooling the side wall 2c of the melting furnace 2 using cooling air Ai as a refrigerant. Specifically, in the cooling process, the cooling capacity obtained by the cooling air Ai is relatively higher in the downstream region 2cy of the side wall 2c than in the upstream region 2cx. This manufacturing method, by including a cooling process, provides the following effects.

[0067] In the cooling process, as described above, the operation of the cooling mechanism 14 results in a relatively higher cooling capacity obtained by the cooling air Ai in the downstream region 2cy of the side wall 2c than in the upstream region 2cx. Therefore, the downstream region 2cy of the side wall 2c, where erosion by molten glass Gm is most significant, is sufficiently cooled by the cooling air Ai, suppressing improper erosion of the side wall 2c. Furthermore, the durability of the melting furnace 2 is improved. Moreover, since the cooling capacity for the upstream region 2cx of the side wall 2c can be reduced to zero, it becomes unnecessary to significantly increase the energy used in the melting process despite having a cooling process. This also reduces the loss of energy efficiency in the melting process.

[0068] The modification step involves changing the immersion length of the electrodes 13, which are provided on the side wall 2c, bottom wall 2a, or ceiling wall 2b of the melting furnace 2, into the molten glass. By including this modification step, the following effects and advantages can be obtained in this manufacturing method.

[0069] In the modification process, if there is a risk that erosion occurring on the side wall 2c will be particularly large in a part of the side wall 2c (as shown by the solid line in Figure 7), the immersion length of some or all of the electrodes 13 in the molten glass Gm is changed in advance. This change ensures that erosion occurs evenly on the side wall 2c, as shown by the dashed line (labeled 2cb) in Figure 7. This avoids problems such as excessive heat dissipation from the side wall 2c due to improper erosion, which leads to a loss of energy efficiency. This also improves the durability of the melting furnace 2. Furthermore, if this modification process is performed, sufficient effects can be obtained without performing the cooling process described above.

[0070] Next, a modified example of the glass article manufacturing apparatus 1 and manufacturing method according to this embodiment will be described.

[0071] Figure 8 is a cross-sectional plan view of a modified melting furnace 2. As shown in the figure, multiple electrodes 13 are provided on the bottom wall 2a of the melting furnace 2, extending from the upstream side to the downstream side. The distance L1 between the electrode 13 located on the upstream side of the melting furnace 2 (bottom wall 2a) and the upstream region 2cx of the side wall 2c is less than the distance L2 between the electrode 13 located on the downstream side of the melting furnace 2 (bottom wall 2a) and the downstream region 2cy of the side wall 2c.

[0072] In this modification, the distance L2 from the downstream region 2cy of the sidewall 2c, where erosion by the molten glass Gm is most pronounced, to the electrode 13 becomes relatively longer. This suppresses the temperature rise in the downstream region 2cy of the sidewall 2c, thereby preventing improper erosion in that region. As a result, the amount of heat dissipated from the sidewall 2c is reduced, thereby reducing the loss of energy efficiency in the melting process. Moreover, since the distance L1 from the upstream region 2cx of the sidewall 2c to the electrode 13 becomes relatively shorter, the temperature drop in the upstream region 2cx of the sidewall 2c is suppressed. This eliminates the need to significantly increase the energy used in the melting process. This also reduces the loss of energy efficiency in the melting process. This modification can achieve substantially the same effects as the cooling process described above, even without the cooling process described above. Furthermore, if both this modification and the cooling process described above are provided, the effects are doubled. Furthermore, this modification is not limited to the case where the electrode 13 is provided on the bottom wall 2a, but can also be applied in the same manner when the electrode 13 is provided on the ceiling wall 2b side and immersed in the molten glass Gm while extending downward.

[0073] Although embodiments of the present invention (including modifications) have been described above, the embodiments of the present invention are not limited to these, and various modifications are possible without departing from the spirit of the present invention.

[0074] For example, in the above embodiment, cooling air Ai was used as the refrigerant, but other gases or liquids such as water may also be used as the refrigerant.

[0075] In the above embodiment, the cooling mechanism 14 is provided with a duct 14a and a plurality of discharge pipes 14b, but other configurations are also possible.

[0076] In the above embodiment, the refrigerant is discharged to the outer surface 2ca of the side wall 2c, but a tubular member or the like may be provided to allow the refrigerant to flow through in a way that enables heat exchange with the side wall 2c. [Explanation of symbols]

[0077] 1. Apparatus for manufacturing glass articles 2. Melting furnace 2a Bottom (bottom wall) 2b Ceiling area (ceiling and walls) 2c side wall Upstream region of the 2cx side wall 2cy Downstream region of the side wall 13 electrodes 13a Tip of the electrode 13a Upper end 14 Cooling mechanism AI refrigerant (cooling air) Ga glass raw material Gm molten glass Distance between the L1 electrode and the upstream region of the side wall Distance between the L2 electrode and the downstream region of the side wall

Claims

1. A method for manufacturing a glass article, comprising: a supply step of supplying glass raw materials from the upstream side of a melting furnace; a melting step of continuously producing molten glass by heating and melting the supplied glass raw materials in the melting furnace; an outflow step of discharging the continuously produced molten glass from the downstream side of the melting furnace; and a cooling step of cooling the side wall of the melting furnace using a refrigerant, A method for manufacturing a glass article, characterized in that, in the cooling step, the cooling capacity obtained by the refrigerant is relatively higher in the downstream region of the side wall than in the upstream region.

2. The method for manufacturing a glass article according to claim 1, characterized in that, in the cooling step, the flow rate of the refrigerant is relatively higher in the downstream region of the side wall than in the upstream region.

3. The method for manufacturing a glass article according to claim 1 or 2, characterized in that, in the cooling step, the temperature of the refrigerant is relatively lower in the downstream region of the side wall than in the upstream region.

4. The method for manufacturing a glass article according to claim 1 or 2, characterized in that the melting step mainly involves heating and melting the glass raw material with an electrode.

5. The method for manufacturing a glass article according to claim 4, characterized in that the electrode is provided on the side wall, bottom, or ceiling side of the melting furnace and is immersed in molten glass.

6. The method for manufacturing a glass article according to claim 1 or 2, further comprising a modification step of changing the immersion length of an electrode provided on the bottom or top side of the melting furnace into the molten glass.

7. Multiple electrodes are provided on the bottom or top side of the melting furnace, extending from the upstream side to the downstream side of the melting furnace. A method for manufacturing a glass article according to claim 1 or 2, characterized in that the distance between the electrode located downstream of the melting furnace and the downstream region of the side wall is longer than the distance between the electrode located upstream of the melting furnace and the upstream region of the side wall.

8. A glass article manufacturing apparatus comprising: a melting furnace configured to continuously produce molten glass by supplying glass raw materials from an upstream side and heating and melting the supplied glass raw materials, and to discharge the continuously produced molten glass from a downstream side; and a cooling mechanism for cooling the side walls of the melting furnace using a refrigerant, A glass article manufacturing apparatus characterized in that the cooling mechanism is configured such that the cooling capacity obtained by the refrigerant is relatively higher in the downstream region of the side wall than in the upstream region.

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