Method for manufacturing a glass article and glass melting furnace

Abstract

To surely detect an occurrence of a leakage of a molten glass in a glass melting furnace.SOLUTION: A manufacturing method of a glass article includes: a melting step of heating a molten glass Gm in a glass melting furnace 2 by energizing electrode sets 13-16 composed of multiple electrodes A-H connected to a common electricity supply system; and a formation step of forming a glass fiber Gf from the molten glass Gm heated in the melting step. The melting step includes: a measurement step of measuring ground voltages of the electrodes A-H included in the electrode sets 13-16; and a determination step of determining a leaked glass Gx from the glass melting furnace 2 based on a variation of the ground voltage measured in the measurement step.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Methods for manufacturing glass articles such as glass fibers and sheet glass include a melting step of melting glass raw materials to obtain molten glass. In the melting step, a glass melting furnace equipped with a plurality of electrodes extending from the bottom wall portion in the furnace may be used. In this type of glass melting furnace, by supplying power to each electrode and performing energization heating, the glass raw materials are melted in the furnace to obtain molten glass. Such energization heating does not generate exhaust gas from a fuel source and can also suppress the scattering of glass raw materials compared to burner heating using fuels such as LPG and heavy oil. In addition, energization heating has advantages such as being excellent from the perspective of environmental protection, being easily heated to a high temperature, and being easily subjected to uniform heating.

[0003] On the other hand, in a glass melting furnace, if the refractory is damaged due to some cause and molten glass leaks out, it can cause serious troubles. Therefore, when such a leakage of molten glass occurs, it is extremely important to quickly detect the leakage. Thus, for example, Patent Document 1 discloses providing a temperature measuring portion between an electrode and the bottom wall portion (through hole) of a glass melting furnace that holds the electrode, and determining that a leakage of molten glass has occurred when the temperature measured by the temperature measuring portion rises rapidly.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a glass melting furnace, the position where leakage of molten glass occurs is not limited to the electrode arrangement position. That is, even outside the electrode arrangement position, the refractory may be damaged due to aging or the like, and there is a risk of molten glass leaking out. However, in the invention according to Patent Document 1, when leakage of molten glass occurs outside the electrode arrangement position, there is a problem that the leakage cannot be detected.

[0006] An object of the present invention is to surely detect the occurrence of leakage of molten glass in a glass melting furnace.

Means for Solving the Problems

[0007] (1) The present invention devised to solve the above problems is a method for manufacturing a glass article including a melting step of heating molten glass in a glass melting furnace by energizing an electrode group composed of a plurality of electrodes connected to a common power supply system, and a forming step of forming a glass article from the molten glass heated in the melting step. The melting step includes a measuring step of measuring the ground voltage of the electrodes included in the electrode group, and a determining step of determining leakage of molten glass from the glass melting furnace based on fluctuations in the ground voltage measured in the measuring step. Here, the “determination of leakage of molten glass” in the present invention includes not only the case of determining the presence or absence of leakage of molten glass, but also the case of determining the occurrence position of leakage of molten glass.

[0008] In this way, in a glass melting furnace, when leakage of molten glass occurs, the ground voltage of the electrodes arranged near the occurrence position of the leakage tends to decrease. On the other hand, among the electrode groups to which the electrodes belong, the ground voltage of the other electrodes arranged at positions away from the occurrence position of leakage of molten glass tends to increase. That is, when leakage of molten glass occurs in a glass melting furnace, as described above, characteristic fluctuations occur in the ground voltage of each electrode of the electrode group. Therefore, if the ground voltage of the electrodes is measured in the measuring step, the leakage of molten glass can be surely determined based on the fluctuations in the ground voltage in the determining step.

[0009] (2) In the configuration of (1) above, it is preferable that a plurality of electrode groups are provided.

[0010] In this way, the fluctuations in the ground voltage of the electrodes included in each electrode group can be measured precisely. Therefore, the presence or absence of leakage of molten glass can be determined precisely. Also, when determining the location where leakage occurs, there is an advantage that the determination accuracy of the occurrence location is improved.

[0011] (3) In the configuration of (1) or (2) above, in the determination step, it is preferable to determine the leakage of molten glass based on the decrease in the ground voltage.

[0012] As described above, when leakage of molten glass occurs, the ground voltage of the electrodes near the location where the leakage of molten glass occurs decreases. Therefore, if the leakage of molten glass is determined based on the decrease in the ground voltage, the leakage of molten glass can be determined more reliably.

[0013] (4) In the configuration of (3) above, in the determination step, it is preferable to determine that leakage of molten glass has occurred near the electrode where the ground voltage has decreased among the electrode groups.

[0014] As described above, when leakage of molten glass occurs, the ground voltage of the electrodes near the location where the leakage of molten glass occurs decreases. Therefore, if it is determined that leakage of molten glass has occurred near the electrode where the ground voltage has decreased, the determination accuracy of the location where the leakage of molten glass occurs is improved.

[0015] (5) The present invention devised to solve the above problems includes a measurement unit that measures the ground voltage of electrodes in a glass melting furnace that includes an electrode group composed of a plurality of electrodes connected to a common power supply system and heats molten glass in a furnace by energizing the electrode group, and a determination unit that determines the leakage of molten glass from the furnace based on fluctuations in the ground voltage of the electrodes measured by the measurement unit.

[0016] In this way, the same operational effects as the corresponding configurations already described can be enjoyed.

Advantages of the Invention

[0017] According to the present invention, it is possible to reliably detect the occurrence of leakage of molten glass in a glass melting furnace.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of a method for manufacturing a glass article according to the present invention will be described with reference to the drawings. In each embodiment, corresponding components may be denoted by the same reference numerals, and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, for the other parts of the configuration, the configurations of other embodiments described previously can be applied. Also, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined with each other without any problem in the combination, even if not explicitly shown.

[0020] (First Embodiment) As shown in FIGS. 1 and 2, the method for manufacturing a glass article according to the first embodiment manufactures glass fiber Gf as a glass article using a glass article manufacturing apparatus 1. The glass article manufacturing apparatus 1 includes a glass melting furnace 2 that melts a glass raw material Gr to form molten glass Gm, and a forehearth 3 that is connected to the downstream end of the glass melting furnace 2 and allows the molten glass Gm supplied from the glass melting furnace 2 to flow through.

[0021] The glass melting furnace 2 includes a refractory 4 that partitions and forms a melting space S1 for the molten glass Gm, and a casing 5 that covers the periphery outside the refractory 4. Note that the melting space S1 means the internal space of the glass melting furnace 2 where the molten glass Gm is stored.

[0022] The refractory 4 is formed of a refractory brick such as a zirconia-based electrocast brick, an alumina-based electrocast brick, an alumina-zirconia-based electrocast brick, an AZS (Al-Zr-Si)-based electrocast brick, or a dense fired brick.

[0023] The casing 5 is formed of a metal (conductor) such as a steel material (e.g., stainless steel). In this embodiment, the casing 5 is grounded by a ground wire 7.

[0024] An inlet 2a for charging a glass raw material Gr obtained by mixing silica sand, limestone, soda ash, cullet, etc. into the furnace is provided at the upstream end (side wall portion) of the glass melting furnace 2. A raw material supply means 8 such as a screw feeder is arranged at the inlet 2a. Note that the glass raw material Gr may contain cullet.

[0025] In the bottom wall portion of the glass melting furnace 2, as heating means, a plurality of electrodes A to H immersed in the molten glass Gm are arranged. Each of the electrodes A to H is formed of, for example, rod-shaped molybdenum (Mo). Then, by passing an electric current through the molten glass Gm using the plurality of electrodes A to H, the glass raw material Gr introduced from the charging port 2a is melted. Thereby, the molten glass Gm is continuously formed from the glass raw material Gr. The molten glass Gm flows into the forehearth 3 from the downstream end portion of the glass melting furnace 2. Note that the electrodes may be arranged on the side wall portion of the glass melting furnace 2 at the height position where they are immersed in the molten glass Gm. Further, the glass melting furnace 2 is not limited to all-electric melting using only electric current heating, and may use a combination of gas combustion and electric current heating.

[0026] In the present embodiment, as shown in FIG. 3, each of the electrodes A to H is arranged on the bottom wall portion of the glass melting furnace 2 while being held by a cylindrical electrode holder 9 formed of a metal such as a ferrous material (e.g., stainless steel). Specifically, the outer peripheral surfaces of the electrodes A to H are held by the inner peripheral surface 9a of the cylindrical electrode holder 9, and the outer peripheral surface 9b of the electrode holder 9 is held by a through hole 4a formed in the bottom wall portion of the refractory 4. The electrode holder 9 is provided with cooling means (not shown) for cooling the electrodes A to H in order to suppress wear of the electrodes A to H due to heat. The cooling means is constituted by, for example, a flow path for circulating a refrigerant such as water or air inside the electrode holder 9. Each of the electrodes A to H penetrates the bottom wall portion (refractory 4 and casing 5) of the glass melting furnace 2 while being held by the electrode holder 9.

[0027] As shown in FIGS. 1 and 2, the forehearth 3 includes a refractory 10 that partitions and forms a flow space S2 for the molten glass Gm. Note that the flow space S2 means the internal space of the forehearth 3 where the molten glass Gm is stored. Although not shown, the forehearth 3 may also be provided with a casing, similar to the glass melting furnace 2.

[0028] On the bottom wall portion of the forehearth 3, a plurality of bushings 12 made of platinum or a platinum alloy are provided at intervals in the flow direction X of the molten glass Gm. A plurality of nozzles (not shown) are provided in each bushing 12. Each nozzle causes the molten glass Gm to flow down to form glass fibers Gf. The molten glass Gm flowing down from each nozzle is formed into glass fibers Gf having a predetermined diameter while being stretched downward. Thereafter, the glass fibers Gf are coated with a sizing agent so that a plurality of them are bundled to form a glass fiber bundle. Note that the forehearth 3 may be heated by a burner.

[0029] As shown in FIG. 2, the glass melting furnace 2 includes a plurality of electric circuits 17 to 20 that supply power to each of a plurality of electrode sets 13 to 16 formed by a set of two out of a plurality of electrodes A to H extending from the bottom wall portion inside the furnace. Each of the electric circuits 17 to 20 constitutes an electrically independent power supply system.

[0030] In the present embodiment, a total of eight electrodes A to H are arranged in a state where four are arranged at equal intervals in the width direction Y inside the furnace and two are arranged at equal intervals in the flow direction X inside the furnace. Then, two electrodes A and E facing each other in the flow direction X are taken as the first electrode set 13. Two electrodes B and F facing each other in the flow direction X are taken as the second electrode set 14. Two electrodes C and G facing each other in the flow direction X are taken as the third electrode set 15. Two electrodes D and H facing each other in the flow direction X are taken as the fourth electrode set 16. Note that the arrangement pattern such as the number of electrodes and the arrangement position, and / or the combination of electrodes in each electrode set is not particularly limited and can be appropriately changed according to the size of the glass melting furnace 2 and the like.

[0031] Terminals a1 and b1, which are connected to electrodes A and E of the first electrode group 13, are connected to a first electric circuit 17 that includes a first single-phase AC power supply 21. Terminals a2 and b2, which are connected to electrodes B and F of the second electrode group 14, are connected to a second electric circuit 18 that includes a second single-phase AC power supply 22. Terminals a3 and b3, which are connected to electrodes C and G of the third electrode group 15, are connected to a third electric circuit 19 that includes a third single-phase AC power supply 23. Terminals a4 and b4, which are connected to electrodes D and H of the fourth electrode group 16, are connected to a fourth electric circuit 20 that includes a fourth single-phase AC power supply 24.

[0032] The glass melting furnace 2 includes a plurality of measuring units 25 to 32 that measure the ground voltages of the respective electrodes A to H, and a determination unit 33 that determines leakage of the molten glass Gm (hereinafter referred to as "leaked glass") based on fluctuations in the ground voltages of the respective electrodes A to H measured by the measuring units 25 to 32.

[0033] In the present embodiment, since eight electrodes A to H are provided, a total of eight measuring units 25 to 32 corresponding to the respective electrodes A to H are provided. In FIG. 2, a state in which one measuring unit 30 is connected to the determination unit 33 is illustrated. However, in reality, all of the measuring units 25 to 32 are connected to the determination unit 33, and the ground voltages measured by the respective measuring units 25 to 32 are input to the determination unit 33. The connection method between the determination unit 33 and each of the measuring units 25 to 32 may be either wired or wireless. As the determination unit 33, for example, a personal computer, a mobile tablet, or the like can be used.

[0034] Here, since the molten glass Gm has conductivity in the molten state, when the electrodes A to H are energized and heated, a potential is generated in the entire molten glass Gm in the melting space. Further, when a ground electrode is provided in the melting space S1, the ground voltage of the molten glass Gm in the melting space S1 becomes 0 V at the position of the ground electrode. When the ground electrode is not provided, for example, at the central position P1 between the electrodes A to D and the electrodes E to H, which is a structurally symmetric position, the ground voltage of the molten glass Gm in the melting space S1 becomes 0 V. In the present embodiment, a case where no ground electrode is provided in the melting space S1 is illustrated.

[0035] In this state, as shown in Fig. 4, when leakage glass Gx is generated due to a crack or the like in the refractory 4, the following events occur. In the following, in the electrode assembly 13 including the pair of electrodes A and E, the case where leakage glass Gx is generated near the electrode A will be described as an example, but the same events can occur when leakage glass Gx is generated near the other electrode assemblies 14 to 16.

[0036] The leakage glass Gx reaches the casing 5 along a crack or the like in the refractory 4. As a result, the molten glass Gm in the melting space S1 becomes conductive through the leakage glass Gx and is electrically connected to the casing 5. When electrically connected in this way, since the casing 5 is grounded by the ground wire 7, the position where the ground voltage of the molten glass Gm in the melting space S1 becomes 0V changes, for example, from the central position P1 to the generation position P2 of the leakage glass Gx. Along with this, the ground voltage of each electrode A and E of the electrode assembly 13 also changes.

[0037] Specifically, the ground voltage of the electrode A disposed near the generation position P2 of the leakage glass Gx tends to decrease. On the other hand, the ground voltage of the electrode E disposed at a position away from the generation position P2 of the leakage glass Gx tends to increase. Specifically, assuming that the ground voltages of the electrodes A and E before the generation of the leakage glass Gx are 50V each, and the line voltage (the applied voltage of the first single-phase AC power supply 21) of the voltages A and E is 100V, after the generation of the leakage glass Gx, for example, the ground voltage of the electrode A close to the generation position P2 of the leakage glass Gx decreases to 30V, and the ground voltage of the electrode E far from the generation position P2 of the leakage glass Gx increases to 70V. Although not shown in the figure, when the leakage glass Gx is generated at the arrangement position of the electrode A (for example, the electrode holder 9), the ground voltage of the electrode A where the leakage glass Gx is generated decreases to 0V, and the ground voltage of the electrode E far from the generation position of the leakage glass Gx increases to 100V.

[0038] As described above, when the leak glass Gx occurs, characteristic fluctuations occur in the ground voltages of the electrodes A to H of the electrode sets 13 to 16. Therefore, if the ground voltages of the electrodes A to H are measured by the respective measurement units 25 to 32, the determination unit 33 can determine the leak glass Gx based on the fluctuations in the measured ground voltages of the electrodes A to H.

[0039] The determination unit 33 preferably determines the leak glass Gx based on the decrease in the ground voltages of the electrodes A to H measured by the respective measurement units 25 to 32. That is, for at least one electrode (for example, electrode A) included in at least one electrode set (for example, electrode set 13), when the ground voltage measured by the measurement unit (for example, measurement unit 25) becomes equal to or lower than a predetermined first threshold value, it is preferable to determine that the leak glass Gx has occurred. This is because, as described above, when the leak glass Gx occurs, the ground voltage of the electrode (for example, electrode A) close to the occurrence position P2 of the leak glass Gx tends to decrease. In this case, the determination unit 33 stores the first threshold value in advance in a storage means such as a memory. In consideration of the fact that the ground voltages (standard ground voltages) in the state without the leak glass Gx are different for each of the electrodes A to H, different values may be set as the first threshold value for each of the electrodes A to H.

[0040] Note that the determination unit 33 may determine the leak glass Gx based on the increase in the ground voltages of the electrodes A to H measured by the respective measurement units 25 to 32. That is, for at least one electrode (for example, electrode E) included in at least one electrode set (for example, electrode set 13), when the ground voltage measured by the measurement unit (for example, measurement unit 29) becomes equal to or higher than a predetermined second threshold value, it may be determined that the leak glass Gx has occurred. This is because, as described above, when the leak glass Gx occurs, the ground voltage of the electrode (for example, electrode E) arranged at a position away from the occurrence position P2 of the leak glass Gx tends to increase. In this case, the determination unit 33 stores the second threshold value in advance in a storage means such as a memory. In consideration of the fact that the ground voltages (standard ground voltages) in the state without the leak glass Gx are different for each of the electrodes A to H, different values may be set as the second threshold value for each of the electrodes A to H.

[0041] Further, the determination unit 33 may determine the leakage glass Gx based on the increase and decrease of the ground voltages of the electrodes A to H measured by the measurement units 25 to 32. That is, for at least one electrode (for example, electrode A) included in at least one electrode group (for example, electrode group 13), the ground voltage measured by the measurement unit (for example, measurement unit 25) becomes equal to or lower than a predetermined third threshold value, and for at least one other electrode (for example, electrode E paired with electrode A) included in the same electrode group (for example, electrode group 13), when the ground voltage measured by the measurement unit (for example, measurement unit 29) becomes equal to or higher than a predetermined fourth threshold value, it may be determined that the leakage glass Gx has occurred. In this way, since it is possible to make a determination in consideration of both the tendency for the ground voltage of the electrode (for example, electrode A) close to the occurrence position P2 of the leakage glass Gx to decrease and the tendency for the ground voltage of the electrode (for example, electrode E) far from the occurrence position P2 of the leakage glass Gx to increase, the occurrence of the leakage glass Gx can be detected with higher accuracy. In this case, the determination unit 33 stores the third threshold value and the fourth threshold value in advance in a storage means such as a memory. Note that, considering that the ground voltage (standard ground voltage) in the state without the leakage glass Gx is different for each of the electrodes A to H, different values may be set as the third threshold value and the fourth threshold value for each of the electrodes A to H.

[0042] Furthermore, it is preferable that the determination unit 33 determines that leakage glass Gx has occurred near the electrode (for example, electrode A) among the electrode groups 13 to 16 where the ground voltage has decreased. Here, "near the electrode where the ground voltage has decreased" means that, as shown in FIG. 4, when the straight-line distance from the electrode A where the ground voltage has decreased to the generation position P2 of the leakage glass Gx is the first distance L1, and the straight-line distance from the electrode E where the ground voltage has increased to the generation position P2 of the leakage glass Gx is the second distance L2, the first distance L1 is smaller than the second distance L2. For example, when the ground voltage of the electrode A included in the electrode group 13 decreases while the ground voltage of the electrode E increases, and the ground voltage of the electrode B included in the electrode group 14 adjacent to the electrode group 13 decreases while the ground voltage of the electrode F increases, and there is no significant change in the ground voltages of the electrodes C, D, G, H included in the other electrode groups 15 and 16, it can be determined that leakage glass Gx has occurred near the electrode A and the electrode B. Furthermore, when the ground voltage of the electrode A has decreased more than the ground voltage of the electrode B (that is, when the fluctuation ratio is large), it can be determined that the leakage glass Gx has occurred closer to the electrode A than to the electrode B. That is, the two-dimensional coordinates (the position in the XY direction) of the generation position P2 of the leakage glass Gx can be determined based on the fluctuation ratio of the ground voltage of each electrode. In this way, the generation position P2 of the leakage glass Gx can be specified quickly, which is particularly advantageous when the melting space S1 of the glass melting furnace 2 is large (for example, the dimension in the width direction Y is 5 m or more and the dimension in the flow direction X is 5 m or more).

[0043] Next, a method for manufacturing a glass article using the glass article manufacturing apparatus 1 configured as described above will be described.

[0044] As shown in FIGS. 1 to 4, the method for manufacturing a glass article according to the present embodiment includes a melting step of melting a glass raw material Gr in a glass melting furnace 2 to form molten glass Gm, a supply step of circulating the molten glass Gm inside a forehearth 3 and supplying it to a bushing 12 provided on the bottom wall portion of the forehearth 3, and a forming step of flowing down the molten glass Gm from a bushing nozzle (not shown) provided on the bushing 12 to form glass fibers Gf.

[0045] The melting process includes a measurement process of measuring the ground voltage of each of the electrodes A to H by a plurality of measurement units 25 to 32, and a determination process of determining the leakage glass Gx based on the fluctuations in the ground voltage of each of the electrodes A to H measured by each of the measurement units 25 to 32 by a determination unit 33. Further, in the present embodiment, when it is determined in the determination process that the leakage glass Gx has occurred, a repair process (not shown) of repairing the glass melting furnace 2 to stop the leakage glass Gx is further included. From the viewpoint of smoothly starting the repair process, it is preferable to determine the occurrence position P2 of the leakage glass Gx in the determination process.

[0046] In the determination process, for example, for at least one electrode (for example, electrode A) included in at least one electrode group (for example, electrode group 13), when the ground voltage measured by the measurement unit (for example, measurement unit 25) becomes equal to or lower than a predetermined first threshold value, it is determined that the leakage glass Gx has occurred. Note that the method for determining the leakage glass Gx is not limited to this, and other methods exemplified in the description of the determination unit 33 above can also be applied.

[0047] In the determination process, the occurrence position P2 of the leakage glass Gx may also be determined. In this case, it is preferable to determine that the leakage glass Gx has occurred near the electrode (for example, electrode A) whose ground voltage has decreased among the electrode groups 13 to 16.

[0048] In the repair process, first, when it is determined in the determination process that there is a leaking glass Gx, the supply of the molten glass Gm is partially or completely stopped by stopping the raw material supply means 8 or the like. Thereby, the storage amount of the molten glass Gm in the melting space S1 is decreased, and the pressure applied to the outflow portion of the leaking glass Gx is reduced. Next, at the generation position P2 of the leaking glass Gx, a coolant (for example, water) is applied to the outflow portion of the leaking glass Gx to cool the leaking glass Gx from outside the furnace. Thereby, the leaking glass Gx is cooled and solidified to stop its leakage. Thereafter, at the generation position P2 of the leaking glass Gx, a refractory is arranged so as to block the outflow portion of the leaking glass Gx. Note that after arranging the refractory, the cooling at the generation position P2 of the leaking glass Gx may be stopped, but it is preferably continued. Further, during the repair process, the energization by the electrodes A to H may be stopped, but in this case, there is a problem that the temperature of the molten glass Gm is significantly decreased and it takes time to recover. Therefore, during the repair process, it is preferable to continue the energization by the electrodes arranged in an area not affecting the repair work.

[0049] (Second Embodiment) As shown in FIG. 5, the difference between the manufacturing apparatus and the manufacturing method of the glass article according to the second embodiment and the first embodiment lies in the configuration (combination of electrodes) of the electrode groups 41 to 44 of the glass melting furnace 2 and the configuration of the electric circuits 45 to 48 that supply power to the respective electrode groups 41 to 44. Also in this embodiment, the electric circuits 45 to 48 constitute a power supply system that is electrically independent of each other.

[0050] In this embodiment, similar to the first embodiment, a total of eight electrodes A to H are arranged in a state where four are equally spaced in the width direction Y in the furnace and two are equally spaced in the flow direction X in the furnace. Different from the first embodiment, two electrodes A and C facing each other in the width direction Y are defined as the first electrode set 41. Two electrodes D and B facing each other in the width direction Y are defined as the second electrode set 42. Two electrodes E and G facing each other in the width direction Y are defined as the third electrode set 43. Two electrodes H and F facing each other in the width direction Y are defined as the fourth electrode set 44. Note that the arrangement mode such as the number of electrodes, arrangement positions, etc. and / or the combination of electrodes in each electrode set are not particularly limited and can be appropriately changed according to the size of the glass melting furnace 2 and the like.

[0051] A first electric circuit 45 including a first three-phase AC power source 49 is connected to terminals o1 and u1 connected to the electrodes A and C of the first electrode set 41 via a first Scott connection transformer 50. Similarly, a second electric circuit 46 including the first three-phase AC power source 49 is connected to terminals o1' and v1 connected to the electrodes D and B of the second electrode set 42 via the first Scott connection transformer 50. Also, a third electric circuit 47 including a second three-phase AC power source 51 is connected to terminals o2 and u2 connected to the electrodes E and G of the third electrode set 43 via a second Scott connection transformer 52. Similarly, a fourth electric circuit 48 including the second three-phase AC power source 51 is connected to terminals o2' and v2 connected to the electrodes H and F of the fourth electrode set 44 via the second Scott connection transformer 52. And in each of the Scott connection transformers 50 and 52, three-phase AC is converted into two sets of single-phase AC. That is, a total of four sets of single-phase AC are converted by the two Scott connection transformers 50 and 52, and power is supplied to each of the electrode sets 41 to 44 in single-phase AC.

[0052] Even when converting three-phase alternating current to single-phase alternating current using the Scott-connected transformers 50 and 52 as described above, when a leakage glass Gx occurs, the ground voltage of the electrode (for example, electrode A) close to the generation position P2 of the leakage glass Gx decreases. Also, the ground voltage of the other electrode (for example, electrode C paired with electrode A) of the electrode group (for example, electrode group 41) to which the electrode with the decreased ground voltage belongs increases. Therefore, similar to the first embodiment, if the ground voltages of the respective electrodes A to H are measured by the respective measurement units 25 to 32, the determination unit 33 can surely determine the leakage glass Gx based on the fluctuations in the measured ground voltages of the respective electrodes A to H.

[0053] Note that as a method for converting three-phase alternating current to single-phase alternating current, instead of the Scott-connected transformer, a Woodbridge-connected transformer, a modified Woodbridge-connected transformer, a Roof delta-connected transformer, etc. can also be used.

[0054] The present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described operational effects. The present invention can be variously modified without departing from the gist of the present invention.

[0055] In the above-described embodiment, the case where the glass melting furnace includes a refractory and a casing in order from the inside of the furnace has been described, but the present invention is not limited thereto. The casing may be omitted. However, when the casing is omitted, fluctuations occur in the ground voltage of the electrode at the stage when the leakage glass comes into contact with another grounded object (for example, the floor surface, etc.). Therefore, from the viewpoint of detecting the leakage of the molten glass at an early stage, it is preferable to provide a grounded casing.

[0056] In the above embodiment, the case of measuring the ground voltage of all the electrodes included in one electrode set has been described, but the present invention is not limited thereto. For example, if the ground voltage of one electrode included in one electrode set is measured, leakage of molten glass can be determined. That is, when leakage of molten glass occurs and the ground voltage of the electrode in the vicinity thereof decreases, the ground voltage of the other electrodes in the electrode set including that electrode increases. Therefore, since some fluctuation in the ground voltage occurs in any electrode, it is sufficient to measure the ground voltage of at least one electrode included in one electrode set. However, in order to accurately determine the generation position of the leaking glass, it is preferable to measure the ground voltage with a plurality of electrodes included in the electrode set, and it is more preferable to measure the ground voltage with all the electrodes included in the electrode set.

[0057] In the above embodiment, the case where one electrode set is constituted by two (a pair) of electrodes has been described, but one electrode set may be constituted by three or more electrodes. Specifically, for example, one electrode set may be constituted by connecting a plurality of electrode pairs in parallel to one single-phase AC power supply.

[0058] In the above embodiment, the glass melting furnace is a single melter having only one melting space for glass raw materials, but it may be a multi-melter having a plurality of melting spaces connected in series.

[0059] In the above embodiment, the case where the glass article is glass fiber has been described, but the glass article may be, for example, plate glass (including a glass roll obtained by winding a glass film in a roll shape), an optical glass component, a glass tube, a glass block, or the like.

Explanation of Signs

[0060] 1 Manufacturing apparatus for glass article 2 Glass melting furnace 3 Forehearth 4 Refractory 5 Casing 7 Ground wire 8 Raw material supply means 12 Bushing Electrode groups 13 - 16 Electrical circuits (power supply systems) 17 - 20 Single - phase AC power supplies 21 - 24 Measurement units 25 - 32 Judgment unit 33 Electrode groups 41 - 44 Electrical circuits (power supply systems) 45 - 48 Three - phase AC power supplies 49, 51 Scott - connected transformers 50, 52 Gf Glass fiber Gm Molten glass Gr Glass raw material Gx Leaked glass

Claims

1. A method for manufacturing a glass article, comprising: a melting step of heating molten glass in a glass melting furnace by energizing an electrode group composed of a plurality of electrodes connected to a common power supply system; and a forming step of forming a glass article from the molten glass heated in the melting step. The melting step includes a measuring step of measuring the ground voltage of the electrodes included in the electrode group, and a determining step of determining leakage of the molten glass from the glass melting furnace based on fluctuations in the ground voltage measured in the measuring step.

2. The method for manufacturing a glass article according to Claim 1, wherein a plurality of the electrode groups are provided.

3. The method for manufacturing a glass article according to Claim 1 or 2, wherein in the determining step, leakage of the molten glass is determined based on a decrease in the ground voltage.

4. The method for manufacturing a glass article according to Claim 3, wherein in the determining step, it is determined that leakage of the molten glass has occurred in the vicinity of the electrode in the electrode group where the ground voltage has decreased.

5. A glass melting furnace comprising an electrode group composed of a plurality of electrodes connected to a common power supply system, and heating molten glass in the furnace by energizing the electrode group. The glass melting furnace is characterized by comprising a measuring unit that measures the ground voltage of the electrodes, and a determining unit that determines leakage of the molten glass from the furnace based on fluctuations in the ground voltage measured by the measuring unit.

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