WO2021002260A1

WO2021002260A1 - Manufacturing method for glass article and manufacturing device for glass article

Info

Publication number: WO2021002260A1
Application number: PCT/JP2020/024832
Authority: WO
Inventors: 周作玉村
Original assignee: 日本電気硝子株式会社
Priority date: 2019-07-03
Filing date: 2020-06-24
Publication date: 2021-01-07
Also published as: KR20220031859A; CN113874329A; JPWO2021002260A1; JP7497728B2; CN113874329B

Abstract

This manufacturing method for a glass article is provided with: a melting step for producing a molten glass Gm in a melting furnace 1; a state adjustment step for adjusting, by using a state adjustment furnace 6, the state of the molten glass Gm produced in the melting furnace 1; and a molding step for molding the molten glass Gm, the state of which has been adjusted by the state adjustment furnace 6, into a glass article by using a molding apparatus 3. The state adjustment furnace 6 is provided with: a cylindrical main body part 11 extending in the vertical direction; a inflow opening 12 provided in an upper section of the main body part 11; an outflow opening 13 provided to a lower section of the main body part 11; an upper electrode 15, a middle section electrode 16, and a lower electrode 17 which are respectively provided to an upper section, a middle section, and a lower section of the main body part 11. In the state adjustment step, an electric current is applied between the upper electrode 15 and the middle section electrode 16 and an electric current is applied between the middle section electrode 16 and the lower electrode 17.

Description

Manufacturing method of glass articles and manufacturing equipment of glass articles

The present invention relates to a method for manufacturing a glass article and an apparatus for manufacturing a glass article.

In the manufacturing process of glass articles, after the molten glass is produced in the melting furnace, the molten glass produced in the melting furnace is adjusted to a state suitable for molding in a state adjusting tank, and the molten glass in which the state is adjusted is formed into a molding apparatus. It is common to mold it into a glass article (see, for example, Patent Document 1).

When adjusting the state of the molten glass in the state adjusting tank, for example, as disclosed in Patent Document 2, energization heating of the state adjusting tank is used. As a result, the flow rate (viscosity) of the molten glass supplied from the state adjusting tank to the molding apparatus is adjusted.

Japanese Unexamined Patent Publication No. 2016-88754 JP-A-2017-14067

The state adjustment tank has a tubular main body extending in the vertical direction. Patent Document 2 does not disclose a specific method for energizing and heating, but if the energizing and heating of the main body is insufficiently adjusted, the following problems may occur.

That is, when the flow rate of the molten glass is reduced, the temperature of the molten glass near the liquid level inside the main body is lowered, and devitrification (crystallization) is likely to occur. Such devitrification can form a foreign glass layer (eg, cristobalite) near the liquid surface. Therefore, if a foreign glass layer due to devitrification is mixed with the molten glass and supplied to the molding apparatus, it causes a defect in the manufactured glass article. Therefore, when the adjustment of the energization heating of the main body portion is insufficient, the adjustable range of the flow rate of the molten glass is inevitably very narrow in order to suppress the occurrence of devitrification. As a result, there arises a problem that it becomes difficult to appropriately adjust the flow rate of the molten glass in the state adjusting tank.

An object of the present invention is to appropriately adjust the flow rate of the molten glass while suppressing devitrification of the molten glass in the state adjusting tank.

The present invention, which was devised to solve the above problems, has a melting step of producing molten glass in a melting furnace, a state adjusting step of adjusting the state of the molten glass produced in the melting furnace in a state adjusting tank, and a state. In a method for manufacturing a glass article including a molding step of molding molten glass whose state has been adjusted in the adjusting tank into a glass article by a molding apparatus, the state adjusting tank has a tubular main body extending in the vertical direction and a main body. The inlet of the molten glass provided on the upper side of the main body, the outlet of the molten glass provided on the lower part of the main body, and the upper electrodes and the middle portion provided on the upper, middle and lower parts of the main body, respectively. An electrode and a lower electrode are provided, and in the state adjusting step, an electric current is applied between the upper electrode and the intermediate portion electrode, and an electric current is applied between the intermediate portion electrode and the lower portion electrode.

By doing so, the molten glass near the liquid surface can be heated and maintained at a high temperature inside the main body by the energization between the upper electrode and the intermediate electrode, so that the molten glass near the liquid surface is devitrified. Can be suppressed. Then, in this state, if the amount of energization between the intermediate electrode and the lower electrode is adjusted, the flow rate of the molten glass can be appropriately adjusted without causing the temperature of the molten glass near the liquid level to drop.

In the above configuration, the main body has a large diameter portion provided with an inflow port, a reduced diameter portion that is connected to the lower end of the large diameter portion and whose inner diameter gradually decreases as it moves downward, and a lower end of the reduced diameter portion. It is preferable to have a small-diameter portion that is connected to and is provided with an outlet.

In this way, when shifting from the large diameter portion to the small diameter portion via the reduced diameter portion, the flow path cross-sectional area of the molten glass becomes smaller, so that the flow rate of the molten glass can be easily adjusted.

In the above configuration, it is preferable that the intermediate electrode is provided in the reduced diameter portion.

Since the large-diameter portion has a larger cross-sectional area of the tubular portion than the small-diameter portion, if the same voltage is applied to the large-diameter portion and the small-diameter portion when energized, the current density of the large-diameter portion is small and the current density of the small-diameter portion is large. .. As a result, the heat generated in the small diameter portion becomes too large, which may lead to damage. In order to reduce this, it is preferable that the intermediate electrode is provided at the lower part of the large diameter part, the reduced diameter part or the upper part of the small diameter part. Above all, it is more preferable to provide the intermediate portion electrode in the reduced diameter portion as in the above configuration. By doing so, in the small diameter portion, the range in which the same voltage as that in the large diameter portion is applied when energized is very small or completely eliminated, so that damage due to heat generation in the small diameter portion can be suppressed.

In the above configuration, it is preferable that the amount of energization between the upper electrode and the intermediate electrode is larger than the amount of energization between the intermediate electrode and the lower electrode.

By doing so, it is possible to reduce the flow rate of the molten glass while surely suppressing the devitrification of the molten glass near the liquid surface inside the main body.

In the above configuration, in the state adjusting step, it is preferable that the current flowing through the intermediate electrode satisfies (A ² + B ² + AB) ^1/2 > C by adjusting the phase of the alternating current supplied at the time of energization. .. However, A is the maximum current flowing in the main body between the upper electrode and the intermediate electrode, B is the maximum current flowing in the main body between the intermediate electrode and the lower electrode, and C is the maximum current flowing in the intermediate electrode. is there.

By adjusting the phase of the alternating current supplied during energization in this way, it is used both when energizing between the upper electrode and the intermediate electrode and when energizing between the intermediate electrode and the lower electrode. The magnitude of the current flowing through the intermediate electrode (common electrode) can be adjusted easily and reliably. Then, the phase of the AC current supplied at the time of energization (the current flowing in the main body between the upper electrode and the intermediate electrode and the intermediate electrode) so that the current flowing through the intermediate electrode satisfies the relationship of the above equation. By adjusting the phase difference of the current flowing through the main body with the lower electrode), the current flowing through the intermediate electrode becomes moderately small. Therefore, it is possible to suppress a situation in which a large current flows through the intermediate electrode, which is a common electrode, and the intermediate electrode is melted (for example, fusing) when energized.

In the above configuration, the upper electrode is preferably provided above the inflow port.

In this way, when energization is applied between the upper electrode and the intermediate electrode, the molten glass near the liquid surface inside the main body can be efficiently heated.

In the above configuration, the state adjusting tank further includes a tubular inflow portion connected to the inflow port and an inflow portion electrode provided in the inflow portion, and in the state adjusting step, the inflow portion electrode and the upper electrode are provided. It is preferable to energize during.

In this way, the molten glass near the liquid surface can be efficiently heated inside the main body by energizing between the inflow electrode and the upper electrode. In particular, when the upper electrode is provided above the inflow port, the energization between the inflow portion electrode and the upper electrode and the energization between the upper electrode and the intermediate electrode are performed inside the main body. Since the molten glass near the liquid surface is doubly heated and easily maintained at a high temperature, devitrification of the molten glass near the liquid surface can be reliably suppressed.

In the above configuration, when the inflow part electrode is provided in the inflow part, the current flowing through the upper electrode is (D ² + E ² + DE) ^{1 /} by adjusting the phase of the alternating current supplied at the time of energization in the state adjustment step. It is preferable to satisfy ² ≦ F. However, D is the maximum current flowing in the main body between the inflow electrode and the upper electrode, E is the maximum current flowing in the main body between the upper electrode and the intermediate electrode, and F is the maximum current flowing in the upper electrode. ..

By adjusting the phase of the alternating current supplied during energization in this way, it is used both when energizing between the inflow electrode and the upper electrode and when energizing between the upper electrode and the intermediate electrode. The magnitude of the current flowing through the upper electrode (common electrode) can be adjusted easily and reliably. Then, the phase of the AC current supplied at the time of energization (the current flowing in the main body between the inflow electrode and the upper electrode, and the upper electrode and the intermediate portion) so that the current flowing through the upper electrode satisfies the relationship of the above equation. By adjusting the phase difference of the current flowing through the main body between the electrodes, the current flowing through the upper electrodes becomes moderately large. Therefore, when energized, the current flowing through the upper electrode and the upper part of the large diameter portion, which are common electrodes, can be increased, and the molten glass near the liquid surface inside the main body portion can be efficiently heated.

In the above configuration, in the state adjusting step, it is preferable to position the liquid level of the molten glass between the upper end and the lower end of the inflow port.

In this way, the molten glass near the liquid level inside the main body is swept away by the molten glass flowing into the inside of the main body from the inflow port. Therefore, it is possible to suppress a situation in which the molten glass near the liquid surface stays for a long time and devitrifies inside the main body.

The present invention, which was devised to solve the above problems, has a melting furnace for producing molten glass, a state adjusting tank for adjusting the state of the molten glass produced in the melting furnace, and a state adjusting tank for adjusting the state. In a glass article manufacturing apparatus provided with a forming apparatus for forming a glass article from molten glass, the state adjusting tank has a tubular main body extending in the vertical direction and a melting device provided on the upper side of the main body. The inlet of the glass, the outlet of the molten glass provided at the lower part of the main body, the upper electrode, the middle electrode and the lower electrode provided at the upper part, the middle part and the lower part of the main body, respectively, and the upper electrode and the middle. It is characterized by including a first electric circuit capable of energizing between the partial electrodes and a second electric circuit capable of energizing between the intermediate electrode and the lower electrode.

In this way, the same action and effect as the above corresponding configuration can be enjoyed.

According to the present invention, the flow rate of the molten glass can be appropriately adjusted while suppressing the devitrification of the molten glass in the state adjusting tank.

It is a side view which shows the manufacturing apparatus of the glass article which concerns on 1st Embodiment. It is sectional drawing which shows the periphery of the state adjustment tank of the manufacturing apparatus of the glass article which concerns on 1st Embodiment. It is sectional drawing which shows the periphery of the state adjustment tank of the manufacturing apparatus of the glass article which concerns on 2nd Embodiment. It is sectional drawing which shows the periphery of the state adjustment tank of the manufacturing apparatus of the glass article which concerns on 3rd Embodiment.

Hereinafter, the manufacturing apparatus and manufacturing method of the glass article according to the embodiment of the present invention will be described with reference to the drawings. In addition, duplicate description may be omitted by assigning the same reference numerals to the corresponding components in each embodiment. When only a part of the configuration is described in each embodiment, the configurations of the other embodiments described above can be applied to the other parts of the configuration. Not only the combination of the configurations specified in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified.

(First Embodiment)
As shown in FIG. 1, the glass article manufacturing apparatus according to the first embodiment includes a melting furnace 1, a transfer apparatus 2, and a molding apparatus 3 in this order from the upstream side.

The melting furnace 1 is for carrying out a melting step of continuously forming molten glass Gm. Examples of the heating method of the molten glass Gm (or glass raw material) in the melting furnace 1 include a method of heating only by energization heating (total electrofusion method), a method of heating only by combustion of gas fuel, energization heating and gas fuel. A method of heating in combination with combustion can be adopted.

In the present embodiment, the molten glass Gm is made of non-alkali glass. The glass composition of the non-alkali glass is, for example, SiO ₂ 50 to 70%, Al ₂ O ₃ 12 to 25%, B ₂ O ₃₀ to 12%, Li ₂ O + Na ₂ O + K ₂ O (Li ₂ ) in terms of glass composition. Combined amount of O, Na ₂ O and K ₂ O) Includes 0 to less than 1%, MgO 0 to 8%, CaO 0 to 15%, SrO 0 to 12%, and BaO 0 to 15%. The electrical resistivity of molten glass Gm made of non-alkali glass is generally high, and is, for example, 100 Ω · cm or more at a heating temperature of 1500 ° C. of the melting furnace 1.

The molten glass Gm is not limited to non-alkali glass, and may be, for example, soda glass, soda lime glass, borosilicate glass, aluminosilicate glass, alkali-containing glass, or the like.

The transfer device 2 is for carrying out a transfer step of transferring the molten glass Gm from the melting furnace 1 to the molding device 3, and is energized and heated as needed. The transfer device 2 includes a clarification tank 4, a stirring tank 5, a state adjusting tank (pot) 6, and connecting pipes 7 to 10 for connecting each of these parts. Here, the term "tank" such as the clarification tank 4 includes those having a tubular structure in addition to those having a tank-like structure.

The clarification tank 4 is for carrying out a clarification step of clarifying (defoaming) the molten glass Gm supplied from the melting furnace 1 by the action of a clarifying agent or the like.

The stirring tank 5 is for carrying out a homogenization step in which the clarified molten glass Gm is stirred by the stirring blade 5a and homogenized. The stirring tank 5 may be a series of a plurality of stirring tanks. In this case, it is preferable to connect the upper part of one of the two adjacent stirring tanks and the lower part of the other with a connecting pipe.

The state adjusting tank 6 is for carrying out a state adjusting step of adjusting the molten glass Gm to a state suitable for molding. Specifically, the state adjusting tank 6 is a tank without mechanical stirring means such as a stirring blade, and is located on the most downstream side when the transfer device 2 has a plurality of tanks as described above. In other words, the state adjusting tank 6 is a tank that adjusts the flow rate, viscosity, etc. of the molten glass Gm immediately before the molding apparatus 3.

The connecting pipes 7 to 10 are made of, for example, a tubular body (for example, a cylindrical body) made of platinum or a platinum alloy, and transfer the molten glass Gm in the lateral direction (substantially horizontal direction). In the present embodiment, among the transfer devices 2, the connecting pipe 7 located at the most upstream portion and the connecting pipe 9 connecting the stirring tank 5 and the state adjusting tank 6 are inclined so that the downstream side is located above the upstream side. doing.

The molding apparatus 3 is for carrying out a molding step of molding the molten glass Gm into a desired shape. In the present embodiment, the molding apparatus 3 includes a molded body that continuously molds the glass ribbon G from the molten glass Gm by the overflow down draw method.

The molding apparatus 3 may implement a known molding method other than the overflow downdraw method, such as another downdraw method such as a slot downdraw method or a float method.

In the case of the overflow down draw method, the molten glass Gm supplied to the forming apparatus 3 has the molten glass Gm overflowing from the groove formed at the top of the forming apparatus 3 along both side surfaces forming a wedge-shaped cross section of the forming apparatus 3 and the lower end. The plate-shaped glass ribbon G is continuously formed by merging at. The molded glass ribbon G is slowly cooled (annealed), cooled, and then cut to a predetermined size to produce flat glass as a glass article.

The manufactured flat glass has a thickness of, for example, 0.01 to 10 mm (preferably 0.1 to 3 mm), and is used for flat panel displays such as liquid crystal displays and organic EL displays, organic EL lighting, and substrates such as solar cells. Used as a protective cover.

As shown in FIG. 2, the state adjusting tank 6 is provided at a tubular main body 11 extending in the vertical direction, a molten glass inflow port 12 provided at the upper part of the main body, and a lower portion of the main body 11. The molten glass Gm outlet 13 and the tubular inflow portion 14 are provided as a basic configuration.

The inflow port 12 is provided on the upper side of the main body 11. On the other hand, the outlet 13 is provided at the lower end of the main body 11, but is not limited to this. The outflow port 13 may be below the inflow port 12, and may be provided, for example, on the lower side of the main body 11.

A cylindrical (for example, cylindrical) inflow portion 14 extending in the lateral direction is joined to the inflow port 12 by welding or the like. A connecting pipe 9 is connected to the upstream end of the inflow portion 14. On the other hand, the outflow port 13 is inserted into the inside through the opening 10a at one end of the connecting pipe 10 as the outflow part.

An upper electrode 15, an intermediate electrode 16 and a lower electrode 17 are provided on each of the upper portion, the intermediate portion, and the lower portion of the main body portion 11. An inflow portion electrode 18 is provided at an upstream end portion of the inflow portion 14. These electrodes 15 to 18 are formed of, for example, a ring-shaped flange portion made of platinum or a platinum alloy, and are joined to the outer peripheral surface of the main body portion 11 or the inflow portion 14 by welding or the like. Although not shown, the electrodes 15 to 18 are further provided with lead-out electrodes (for example, made of platinum or platinum alloy) for connecting

electric circuits

19, 21 and 23, which will be described later, and a cooling mechanism (for example, water cooling). There is.

The main body 11 has a large diameter portion 11a provided with an inflow port 12, a reduced diameter portion 11b connected to the lower end of the large diameter portion 11a and gradually decreasing in inner diameter as it moves downward, and a reduced diameter portion 11b. It is provided with a small diameter portion 11c connected to the lower end and provided with an outlet 13. The large diameter portion 11a and the small diameter portion 11c are, for example, a cylindrical body, and the reduced diameter portion 11b is, for example, a conical body. The inner diameter of the large diameter portion 11a is preferably 1.5 to 5 times the inner diameter of the small diameter portion 11c, for example.

Although the upper electrode 15 is provided on the large diameter portion 11a, it is preferable that the upper electrode 15 is provided above the inflow port 12 (in the illustrated example, the upper end of the large diameter portion 11a). In other words, the upper electrode 15 is preferably located above the liquid level Gs of the molten glass Gm inside the main body 11.

It is preferable that the intermediate electrode 16 is provided in the lower part of the large diameter part 11a and the upper part of the reduced diameter part 11b or the small diameter part 11c. In the present embodiment, the intermediate electrode 16 is provided at the intermediate portion between the upper end and the lower end of the reduced diameter portion 11b, but may be provided at the upper end or the lower end of the reduced diameter portion 11b. The position of the intermediate electrode 16 is not particularly limited as long as it is between the upper electrode 15 and the lower electrode 17.

Although the lower electrode 17 is provided on the small diameter portion 11c, it is preferable that the lower electrode 17 is provided near the lower end of the small diameter portion 11c.

A first electric circuit 19 for energizing between the

electrodes

15 and 16 is provided between the upper electrode 15 and the intermediate electrode 16. That is, the first electric circuit 19 is a current supply path. The first electric circuit 19 is provided with a first power supply (voltage source) 20 for applying a voltage between the upper electrode 15 and the intermediate electrode 16.

A second electric circuit 21 for energizing between the

electrodes

16 and 17 is provided between the intermediate electrode 16 and the lower electrode 17. That is, the second electric circuit 21 is a current supply path. The second electric circuit 21 is provided with a second power source (voltage source) 22 for applying a voltage between the intermediate electrode 16 and the lower electrode 17. The intermediate electrode 16 is a common electrode used in both the first electric circuit 19 and the second electric circuit 21.

A third electric circuit 23 for energizing between the

electrodes

18 and 15 is provided between the inflow portion electrode 18 and the upper electrode 15. That is, the third electric circuit 23 is a current supply path. The third electric circuit 23 is provided with a third power supply (voltage source) 24 for applying a voltage between the inflow portion electrode 18 and the upper electrode 15. Although the third electric circuit 23 (third power supply 24) may be omitted, it is preferable to provide the third electric circuit 23 from the viewpoint of suppressing devitrification of the molten glass Gm near the liquid level Gs. The upper electrode 15 is a common electrode used in both the first electric circuit 19 and the third electric circuit 23.

The voltage applied to each of the

electric circuits

19, 21, 23 (each

power supply

20, 22, 24) can be adjusted individually.

Next, a method of manufacturing a glass article by the manufacturing apparatus configured as described above will be described.

As described above, the method for manufacturing a glass article according to the present embodiment includes a melting step, a transfer step, and a molding step. The transfer step includes a clarification step, a homogenization step, and a state adjustment step. Of these, the melting step, the clarification step, the homogenizing step, and the molding step are as described in accordance with the above-described configuration of the manufacturing apparatus. Therefore, the state adjusting process will be described in detail below.

As shown in FIG. 2, in the state adjusting step, the molten glass Gm homogenized in the stirring tank 5 is supplied from the inflow port 12 to the main body 11 of the state adjusting tank 6 through the connecting pipe 9 and the inflow portion 14. .. The molten glass Gm supplied to the main body 11 moves downward in the order of the large diameter portion 11a, the reduced diameter portion 11b, and the small diameter portion 11c while being energized and heated by the electrodes 15 to 18. During this time, the flow rate, viscosity, etc. of the molten glass Gm are adjusted to a state suitable for supplying to the molding apparatus 3. Then, the molten glass Gm whose state has been adjusted flows out from the outflow port 13 and is supplied to the molding apparatus 3 through the connecting pipe 10 as the outflow portion.

In the state adjusting step, the first electric circuit 19 and the second electric circuit 21 energize between the upper electrode 15 and the intermediate electrode 16 and between the intermediate electrode 16 and the lower electrode 17, respectively. That is, when energization is performed between the upper electrode 15 and the intermediate electrode 16 by the first electric circuit 19, the molten glass Gm near the liquid level Gs inside the main body 11 is heated and maintained at a high temperature, so that the liquid level is maintained at a high temperature. It is possible to suppress devitrification of the molten glass Gm in the vicinity of Gs. On the other hand, the second electric circuit 21 is independent of the first electric circuit 19, and the amount of energization can be adjusted individually. Therefore, if the amount of energization between the intermediate electrode 16 and the lower electrode 17 is adjusted by the second electric circuit 21, the molten glass Gm near the liquid level Gs inside the main body 11 is melted without causing a temperature drop. The flow rate of the glass Gm can be adjusted appropriately.

The amount of energization (current value) between the upper electrode 15 and the intermediate electrode 16 is preferably larger than the amount of energization (current value) between the intermediate electrode 16 and the lower electrode 17. For example, when the amount of energization between the upper electrode 15 and the intermediate electrode 16 is X [A] and the amount of energization between the intermediate electrode 16 and the lower electrode 17 is Y [A], X / Y is 1. It is preferably to 4.

Here, if the same voltage is applied to the large diameter portion 11a and the small diameter portion 11c during energization, the current density of the large diameter portion 11a is small and the current density of the small diameter portion 11c is large, so that the heat generation of the small diameter portion 11c becomes too large. , May lead to damage. In order to reduce this, in the present embodiment, the intermediate portion electrode 16 is provided in the reduced diameter portion 11b so that the same voltage as that of the large diameter portion 11a is not applied to the small diameter portion 11c. The same effect can be obtained when the intermediate portion electrode 16 is provided at the lower portion of the large diameter portion 11a and the upper portion of the small diameter portion 11c, but the intermediate portion electrode 16 is provided at the reduced diameter portion 11b. Is most preferable. This is because when the intermediate electrode 16 is provided in the reduced diameter portion 11b, a high voltage can be reliably applied to a wide range of the large diameter portion 11a in which the stored amount of the molten glass Gm is relatively large, and the flow rate of the molten glass Gm and the flow rate of the molten glass Gm can be increased. This is because it is efficient in adjusting the viscosity.

In the present embodiment, the inflow portion electrode 18 and the upper electrode 15 are also energized by the third electric circuit 23. As a result, the molten glass near the liquid level Gs inside the main body 11 is doubled by the energization between the inflow portion electrode 18 and the upper electrode 15 and the energization between the upper electrode 15 and the intermediate portion electrode 16. Since it is heated to, devitrification of the molten glass Gm near the liquid surface Gs can be reliably suppressed.

For example, when the energization amount between the inflow portion electrode 18 and the upper electrode 15 is Z [A] and the energization amount between the upper electrode 15 and the intermediate portion electrode 16 is X [A], Z / X is 0. It is preferably ~ 1.5.

While the molten glass Gm supplied to the state adjusting tank 6 is energized and heated in the above embodiment, the liquid level Gs of the molten glass Gm inside the main body 11 is a region between the upper end 12a and the lower end 12b of the inflow port 12. It is preferably located in H. In this way, the molten glass Gm near the liquid level Gs is swept away by the molten glass Gm flowing from the inflow port 12 into the main body 11. Therefore, it is possible to suppress a situation in which the molten glass Gm near the liquid level Gs stagnates for a long time and devitrifies. By adjusting the flow rate (viscosity) of the molten glass Gm, the height of the liquid level Gs of the molten glass Gm can be adjusted. That is, at least among the amount of energization between the inflow portion electrode 18 and the upper electrode 15, the amount of energization between the upper electrode 15 and the intermediate portion electrode 16, and the amount of energization between the intermediate portion electrode 16 and the lower electrode 17. The height of the liquid level Gs of the molten glass Gm can be adjusted by one or more.

Further, the temperature MT [° C.] of the molten glass Gm at the liquid level Gs inside the main body 11 is preferably higher than LT + 100 ° C. when the liquidus temperature of the molten glass Gm is LT [° C.]. The liquidus temperature LT of the molten glass Gm is an equilibrium temperature between the melt and the initial phase of the crystal, and theoretically, the crystal does not exist above the liquidus temperature LT. Here, the "liquid phase temperature" is determined by passing the standard sieve 30 mesh (500 μm), putting the glass powder remaining in 50 mesh (300 μm) into a platinum boat, holding it in a temperature gradient furnace for 24 hours, and then holding the platinum boat. Can be obtained by taking out and measuring the temperature at which the crystals precipitate. The temperature MT of the molten glass Gm at the liquid level Gs can be measured using an infrared radiation thermometer.

(Second Embodiment)
As shown in FIG. 3, in the second embodiment, a modified example of the state adjusting tank 6 and the state adjusting step is illustrated. The second embodiment is provided with the phase adjusting unit 25, which is different from the first embodiment.

In the present embodiment, by applying a voltage from the first power source 20, the first is supplied to the large diameter portion 11a and the reduced diameter portion 11b of the main body portion 11 located between the upper electrode 15 and the intermediate portion electrode 16. By applying an alternating current through i1 and a second power supply 22, a second alternating current is supplied to the reduced diameter portion 11b and the small diameter portion 11c of the main body portion 11 located between the intermediate portion electrode 16 and the lower electrode 17. Let the current be i2. Further, by supplying the first alternating current i1 and the second alternating current i2, the third alternating current flowing through the intermediate electrode 16 is defined as i3.

The state adjusting tank 6 is provided with a phase adjusting unit 25 for adjusting the phase difference θ1 between the first alternating current i1 and the second alternating current i2. The phase adjusting unit 25 is connected to the first power supply 20 and the second power supply 22. The first power supply 20, the second power supply 22, and the phase adjusting unit 25 are composed of, for example, a three-phase AC power supply. In the case of a three-phase AC power supply, the phase difference θ1 between the first AC current i1 and the second AC current i2 can be adjusted by appropriately changing the connection terminals (for example, TR, RT, RS, SR, etc.).

The phase adjusting unit 25 sets the maximum value of the first alternating current i1 to A, the maximum value of the second alternating current i2 to B, and supplies the first alternating current i1 and the second alternating current i2 to the intermediate electrode 16. When the maximum value of the alternating current i3 is C, the phase difference θ1 between the first alternating current i1 and the second alternating current i2 is set so that the third alternating current i3 satisfies the relationship of the following equation (1). It is configured to adjust. That is, in the method for manufacturing a glass article, in the state adjusting step, the phase difference θ1 between the first alternating current i1 and the second alternating current i2 so that the third alternating current i3 satisfies the relationship of the following equation (1). To adjust.
(A ² + B ² + AB) ^1/2 > C ... (1)

Here, i1 = Asinωt, i2 = Bsin (ωt + θ1), and i3 = i1-i2 are defined. Note that ω is the angular velocity, t is the time, and θ1 is the phase difference of the second alternating current i2 with respect to the first alternating current i1. The phase difference θ1 is based on the phase of the first alternating current i1, but is not limited thereto. Since the direction of each current is defined in FIG. 3, when the base of the intermediate electrode 16 (the junction with the main body 11) is considered as a branch point, the inflow current to the branch point is i1 and the inflow current from the branch point is i1. Since the outflow currents are i2 and i3, the third alternating current i3 is represented by "i1-i2" as described above according to Kirchhoff's law.

In this case, the third alternating current i3 can be expressed by the following equation (2) from the addition theorem of trigonometric functions.
i3 = Asin ωt-Bsin (ωt + θ1)
= (A-Bcosθ1) sinωt-Bsinθ1cosωt ... (2)

Further, the equation (2) can be expressed by the following equation (2)'from the trigonometric function synthesis formula.
i3 = {(A-Bcos θ1) ² + B ² sin ² θ1} ^1/2 sin (ωt-α)
= (A ² + B ² -2ABcos θ1) ^1/2 sin (ωt-α) ... (2)'
However, sinα = Bsinθ1 / (A ² + B ² -2ABcosθ1) ^1/2 , and cosα = (A−Bcosθ1) / (A ² + B ² -2ABcosθ1) ^1/2 .

Since -1 ≤ sin (ωt-α) ≤ 1, the equation (2)'shows the maximum value when sin (ωt-α) = 1. That is, the maximum value C of the third alternating current i3 is expressed by the following equation (3).
C = (A ² + B ² -2ABcos θ1) ^1/2 ... (3)

By adjusting the phase difference θ1 between the first alternating current i1 and the second alternating current i2 in this way, the magnitude of the third alternating current i3 flowing through the intermediate electrode 16 can be easily and surely adjusted. Then, if the phase difference θ1 between the first alternating current i1 and the second alternating current i2 is adjusted so that the third alternating current i3 satisfies the relationship of the above equation (1), the third alternating current i3 flows through the intermediate electrode 16. The three alternating currents i3 are appropriately reduced, and the melting damage of the intermediate electrode 16 and the state adjusting tank 6 in the vicinity of the intermediate electrode 16 can be reliably suppressed.

The phase adjusting unit 25 is preferably configured to adjust the phase difference θ1 between the first alternating current i1 and the second alternating current i2 so as to satisfy the relationship of the following equation (4), and C = Most preferably, it is 0A.
(A ² + B ^2- AB) ^1/2 ≧ C ... (4)

Here, the phase difference θ1 is preferably −120 ° <θ1 <120 °, more preferably −60 ° ≦ θ1 ≦ 60 °, and most preferably 0 °. The left side of the equation (1) is the value of the equation (3) when θ1 = 120 ° (or −120 °), and the left side of the equation (4) is the value of θ1 = 60 ° (or −60 °). It is the value of the equation (3) at the time of.

The maximum value A of the first alternating current i1 and the maximum value B of the second alternating current i2 may be different values or may be the same value. In addition, at least one of the maximum value A of the first alternating current i1 and the maximum value B of the second alternating current i2 is set together with the phase difference θ1 so as to satisfy the relationship of the above equation (1) or (4). You may adjust.

(Third Embodiment)
As shown in FIG. 4, in the third embodiment, a modified example of the state adjusting tank 6 and the state adjusting step is illustrated. In the third embodiment, the phase adjusting unit 25 is connected to the third power supply 24 in addition to the first power supply 20 and the second power supply 22. This point is different from the second embodiment.

In the present embodiment, by applying a voltage from the first power source 20, the first is supplied to the large diameter portion 11a and the reduced diameter portion 11b of the main body portion 11 located between the upper electrode 15 and the intermediate portion electrode 16. By applying an alternating current through i1 and the third power supply 24, a fourth alternating current is supplied to the inflow portion 14 located between the inflow portion electrode 18 and the upper electrode 15 and the large diameter portion 11a of the main body portion 11. Let the current be i4. Further, the fifth alternating current i5 that flows through the upper electrode 15 by supplying the first alternating current i1 and the fourth alternating current i4 is used.

The phase adjusting unit 25 is connected to the first power source 20, the second power source 22, and the third power source 24, and has a phase difference θ1 between the first alternating current i1 and the second alternating current i2 and the first alternating current i1. It is configured to adjust the phase difference θ2 with the fourth alternating current current i4. The first power supply 20, the second power supply 22, the third power supply 24, and the phase adjusting unit 25 are composed of, for example, a three-phase AC power supply.

The phase adjusting unit 25 adjusts the phase difference θ1 between the first alternating current i1 and the second alternating current i2 so as to satisfy the above equation (1) or (4) in the same manner as described in the second embodiment. It is configured to do. In addition, in the present embodiment, the phase adjusting unit 25 is configured to adjust the phase difference θ2 between the first alternating current i1 and the fourth alternating current i4 as follows.

That is, the phase adjusting unit 25 sets the maximum value of the first alternating current i1 to D (same as A of the second embodiment), the maximum value of the fourth alternating current i4 to E, the first alternating current i1 and the fourth alternating current. When the maximum value of the fifth alternating current i5 flowing through the upper electrode 15 due to the supply of i4 is F, the first alternating current i1 so that the fifth alternating current i5 satisfies the relationship of the following equation (5). And the phase difference θ2 of the fourth alternating current i4 is adjusted. That is, in the method for manufacturing a glass article, the first alternating current i1 and the second alternating current i3 so that the third alternating current i3 satisfies the relationship of the above equation (1) (or equation (4)) in the state adjusting step. The phase difference θ1 of the alternating current i2 is adjusted, and the phase difference θ2 of the first alternating current i1 and the fourth alternating current i4 is adjusted so that the fifth alternating current i5 satisfies the relationship of the following equation (5). To do.
(D ² + E ² + DE) ^1/2 ≤ F ... (5)

Here, i1 = Dsinωt, i4 = Esin (ωt + θ2), and i5 = i4-i1 are defined. Note that ω is the angular velocity, t is the time, and θ2 is the phase difference of the fourth alternating current i4 with respect to the first alternating current i1. The phase difference θ2 is based on the phase of the first alternating current i1, but is not limited thereto. Since the direction of each current is defined in FIG. 4, when the base of the upper electrode 15 (the junction with the main body 11) is considered as a branch point, the inflow current to the branch point is i4 and the outflow from the branch point. Since the currents are i1 and i5, the fifth alternating current i5 is represented by "i4-i1" as described above according to Kirchhoff's law.

In this case, the fifth alternating current i5 can be expressed by the following equation (6) from the addition theorem of trigonometric functions.
i5 = Esin (ωt + θ2) -Dsinωt
= (Ecosθ2-D) sinωt + Esinθ2cosωt ... (6)

Further, the equation (6) can be expressed by the following equation (6)'from the synthesis formula of trigonometric functions.
i5 = {(Ecos θ2-D) ² + E ² sin ² θ ² } ^1/2 sin (ωt + β)
= (D ² + E ² -2DEcos θ2) ^1/2 sin (ωt + β) ・・・ (6)'
However, sinβ = Esinθ2 / (D ² + E ² -2DEcos θ2) ^1/2 and cos β = (Ecos θ2-D) / (D ² + E ² -2DEcos θ2) ^1/2 .

Since -1 ≦ sin (ωt + β) ≦ 1, the equation (6)'shows the maximum value when sin (ωt + β) = 1. That is, the maximum value F of the fifth alternating current i5 is expressed by the following equation (7).
F = (D ² + E ² -2DEcos θ2) ^1/2 ... (7)

By adjusting the phase difference θ2 between the first alternating current i1 and the fourth alternating current i4 in this way, the magnitude of the fifth alternating current i5 flowing through the upper electrode 15 can be easily and surely adjusted. Then, if the phase difference θ2 between the first alternating current i1 and the fourth alternating current i4 is adjusted so that the fifth alternating current i5 satisfies the relationship of the above equation (5), the fifth alternating current i5 flows through the upper electrode 15. The alternating current i5 becomes moderately large. Therefore, the current flowing above the upper electrode 15 and the large diameter portion 11a can be increased, and the molten glass Gm near the liquid level Gs inside the main body portion 11 can be efficiently heated.

The phase adjusting unit 25 is preferably configured to adjust the phase difference θ2 of the first alternating current i1 and the fourth alternating current i4 so as to satisfy the relationship of the following equation (8).
D + E = F ... (8)

Here, the phase difference θ2 is preferably 120 ° ≦ θ2 ≦ 240 ° (or −120 ° ≧ θ2 ≧ −240 °), and more preferably 180 ° (or −180 °). The left side of the equation (5) is the value of the equation (7) when θ2 = 120 ° (or −120 °), and the left side of the equation (8) is the value of θ2 = 180 ° (or −180 °). It is the value of the equation (7) at the time of.

From the viewpoint of surely preventing the state adjustment tank 6 near the upper electrode 15 from being melted, the first alternating current i1 and the fourth alternating current i4 so as to satisfy (D ² + E ² + DE) ^1/2 > F. It is preferable to adjust the phase difference θ2.

The maximum value D of the first alternating current i1 and the maximum value E of the fourth alternating current i4 may be different values or may be the same value. In addition, at least one of the maximum value D of the first alternating current i1 and the maximum value E of the fourth alternating current i4 is set together with the phase difference θ2 so as to satisfy the relationship of the above equation (5) or (8). You may adjust.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and is not limited to the above-mentioned action and effect. The present invention can be modified in various ways without departing from the gist of the present invention.

In the above embodiment, the opening at the upper end of the main body 11 of the state adjusting tank 6 serves as an insertion port for the plunger that blocks the downward flow of the molten glass Gm. The opening at the upper end of the main body 11 may be covered with a lid. By doing so, it becomes easy to maintain the upper part of the main body 11 at a high temperature, so that devitrification of the molten glass Gm near the liquid level Gs can be further suppressed.

In the above embodiment, the case where the main body portion 11 of the state adjusting tank 6 has the large diameter portion 11a, the reduced diameter portion 11b, and the small diameter portion 11c is illustrated, but the main body portion 11 is a single body having a constant inner diameter. It may be a tubular body.

In the above embodiment, in order to heat the molten glass Gm near the liquid level Gs, an auxiliary heating device may be provided outside the main body 11 of the state adjusting tank 6. As a result, devitrification of the molten glass Gm near the liquid level Gs can be further suppressed. As the auxiliary heating device, a resistance heating type, an induction heating type, or the like can be adopted.

In the above embodiment, the case where the glass article molded by the molding apparatus is flat glass has been described, but the present invention is not limited to this. The glass article molded by the molding apparatus may be, for example, a glass roll obtained by winding a glass film into a roll, an optical glass component, a glass tube, a glass block, a glass fiber, or any other shape. Good.

1 Melting furnace 2 Transfer device 3 Molding device 4 Clarification tank 5 Stirring tank 6 Condition adjustment tank 9 Connection pipe 10 Connection pipe (outflow part)
11 Main body 11a Large diameter 11b Reduced diameter 11c Small diameter 12 Inflow port 13 Outlet 14 Inflow part 15 Upper electrode 16 Intermediate part electrode 17 Lower electrode 18 Inflow part electrode 19 First electric circuit 20 First power supply 21 Second electricity Circuit 22 Second power supply 23 Third electric circuit 24 Third power supply 25 Phase adjustment unit G Glass ribbon Gm Molten glass Gs Liquid level

Claims

A melting step of producing molten glass in a melting furnace, a state adjusting step of adjusting the state of the molten glass generated in the melting furnace in a state adjusting tank, and the molten glass whose state has been adjusted in the state adjusting tank. In a method for manufacturing a glass article, which comprises a molding process of forming a glass article with a molding apparatus.
The state adjustment tank
A tubular body that extends in the vertical direction,
The inlet of the molten glass provided on the upper side of the main body and
With the outlet of the molten glass provided in the lower part of the main body,
An upper electrode, an intermediate electrode, and a lower electrode provided on the upper part, the middle part, and the lower part of the main body portion are provided.
A method for manufacturing a glass article, which comprises energizing between the upper electrode and the intermediate electrode and energizing between the intermediate electrode and the lower electrode in the state adjusting step.
The main body includes a large-diameter portion provided with the inflow port, a reduced-diameter portion connected to the lower end of the large-diameter portion and gradually decreasing in inner diameter as it moves downward, and the lower end of the reduced-diameter portion. The method for manufacturing a glass article according to claim 1, further comprising a small-diameter portion that is connected and provided with the outlet.
The method for manufacturing a glass article according to claim 2, wherein the intermediate portion electrode is provided in the reduced diameter portion.
The method according to any one of claims 1 to 3, wherein the amount of energization between the upper electrode and the intermediate electrode is larger than the amount of energization between the intermediate electrode and the lower electrode. How to manufacture glass articles.
The glass article according to any one of claims 1 to 4, wherein in the state adjusting step, the phase of the alternating current supplied at the time of energization is adjusted so that the current flowing through the intermediate electrode satisfies the following equation. Production method.
(A 2 + B 2 + AB) 1/2 > C
However, A: the maximum current flowing in the main body between the upper electrode and the intermediate electrode B: the maximum current flowing in the main body between the intermediate electrode and the lower electrode C: the intermediate electrode Maximum current flowing through
The method for manufacturing a glass article according to any one of claims 1 to 5, wherein the upper electrode is provided above the inflow port.
The state adjusting tank further includes a tubular inflow portion connected to the inflow port and an inflow portion electrode provided in the inflow portion.
The method for manufacturing a glass article according to any one of claims 1 to 6, wherein in the state adjusting step, electricity is applied between the inflow portion electrode and the upper electrode.
The method for manufacturing a glass article according to claim 7, wherein in the state adjusting step, the phase of the alternating current supplied at the time of energization is adjusted so that the current flowing through the upper electrode satisfies the following equation.
(D 2 + E 2 + DE) 1/2 ≤ F
However, D: the maximum current flowing in the main body between the inflow electrode and the upper electrode E: the maximum current flowing in the main body between the upper electrode and the intermediate electrode F: in the upper electrode Maximum current flowing
The method for manufacturing a glass article according to any one of claims 1 to 8, wherein in the state adjusting step, the liquid level of the molten glass is positioned between the upper end and the lower end of the inflow port.
A melting furnace for producing molten glass, a state adjusting tank for adjusting the state of the molten glass generated in the melting furnace, and a molding apparatus for forming a glass article from the molten glass whose state has been adjusted in the state adjusting tank. In a glass article manufacturing apparatus equipped with
The state adjustment tank
A tubular body that extends in the vertical direction,
The inlet of the molten glass provided on the upper side of the main body and
With the outlet of the molten glass provided in the lower part of the main body,
The upper electrode, the middle electrode, and the lower electrode provided on the upper part, the middle part, and the lower part of the main body, respectively,
A first electric circuit capable of energizing between the upper electrode and the intermediate electrode,
An apparatus for manufacturing a glass article, which comprises a second electric circuit capable of energizing between the intermediate portion electrode and the lower electrode.