JP2021169384A - Manufacturing method of glass article and manufacturing apparatus of glass article - Google Patents

Abstract

To suppress a generation of a glass retaining layer around a bottom part of a main body part with a bottom extending in the vertical direction.SOLUTION: A manufacturing method of a glass article includes a transfer step of transferring a molten glass Gm using a transfer device 2. A stirring tank 5 included in the transfer device 2 includes: a main body part 11 with a bottom extending a vertical direction; an outflow part 13 arranged in a lower part of a side wall of the main body part 11 for transferring the molten glass Gm in the main body part 11 to a next step; a discharge part 14 arranged in a bottom part of the main body part 11 for discharging the molten glass Gm in the main body part 11; a first electrode 18 arranged in the bottom part of the main body part 11; and a second electrode 19 arranged in the discharge part 14. The transfer step applies a voltage between the first electrode 18 and the second electrode 19 so as to heat the discharge part 14.SELECTED DRAWING: Figure 2

Description

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

The method for manufacturing a glass article includes a transfer step of transferring the molten glass produced in the melting furnace to a molding apparatus using a transfer device and a molding step of molding a glass article such as flat glass from the molten glass using the molding apparatus. (See, for example, Patent Document 1).

The above transfer device is provided with a plurality of electrodes at intervals from the upstream side to the downstream side in order along the transfer path, and by energizing between these electrodes, the inside of the transfer device is transferred. The molten glass is heated (see, for example, Patent Documents 2 and 3). The transfer device includes, for example, a clarification tank, a stirring tank, a state adjusting tank (pot), and the like.

Japanese Unexamined Patent Publication No. 2016-88754 Japanese Unexamined Patent Publication No. 2012-10970 Japanese Unexamined Patent Publication No. 2012-116693

By the way, the stirring tank or the like included in the transfer device includes a main body portion having a bottom extending in the vertical direction and an outflow portion provided at the lower part of the side wall of the main body portion for transferring the molten glass in the main body portion to the next process. ing.

In such a configuration, the fluidity of the molten glass becomes insufficient around the bottom of the main body, and a glass stagnant layer is likely to occur around the bottom of the main body. This glass stagnant layer may contain foreign glass having a composition different from that of molten glass that normally flows inside the main body. When such foreign glass is mixed in the molten glass that flows normally, it can become a defect of the manufactured glass article. Therefore, from the viewpoint of producing a high-quality glass article, it is desired to suppress the generation of a glass stagnant layer around the bottom of the main body.

An object of the present invention is to suppress the generation of a glass stagnant layer around the bottom of a bottomed main body extending in the vertical direction.

The present invention, which was devised to solve the above problems, is a method for manufacturing a glass article including a transfer step of transferring molten glass using a transfer device, wherein the transfer device is a body with a bottom extending in the vertical direction. A unit, an outflow portion provided at the lower part of the side wall of the main body for transferring the molten glass in the main body to the next process, and a discharge portion provided at the bottom of the main body for discharging the molten glass in the main body. A first electrode provided at the bottom and a second electrode provided at the discharge portion are provided, and in the transfer step, electricity is applied between the first electrode and the second electrode to heat the discharge portion. ..

In this way, the temperature of the molten glass around the bottom of the main body rises due to the heating of the discharge portion. As a result, the fluidity of the molten glass around the bottom of the main body is improved, and the generation of a glass stagnant layer around the bottom of the main body can be suppressed.

In the above configuration, the transfer device further includes a third electrode provided in the main body on the upstream side of the first electrode, and in the transfer step, energization is performed between the first electrode and the third electrode to press the main body. It is preferable to heat it.

In this way, the molten glass inside the main body can be adjusted to a suitable temperature by heating the main body.

In the above configuration, the maximum value of the first alternating current supplied to the discharge unit is A, the maximum value of the second alternating current supplied to the main body is B, and the third alternating current flowing to the first electrode by supplying the current to the transfer device. When the maximum value of the current is C, the phase difference between the first alternating current and the second alternating current is set so that the third alternating current satisfies the relationship ^{(A 2} + B ² + AB) ^{1/2 ≤ C.} It is preferable to adjust.

By adjusting the phase difference between the first alternating current and the second alternating current in this way, it is used both when supplying the first alternating current to the discharge section and when supplying the second alternating current to the main body. The magnitude of the third alternating current flowing through the first electrode (common electrode) to be generated can be easily and surely increased. Then, if the phase difference between the first alternating current and the second alternating current is adjusted so that the third alternating current satisfies the relationship of the above equation, the third alternating current flowing through the first electrode becomes large, and the third alternating current flows. The molten glass around one electrode can be heated efficiently. Therefore, it is possible to more reliably suppress the generation of the glass stagnant layer around the bottom of the main body.

In the above configuration, it is preferable that the glass transfer device further includes a fourth electrode provided in the outflow portion, and in the transfer step, an electric current is applied between the first electrode and the fourth electrode to heat the outflow portion.

In this way, the molten glass inside the outflow portion can be adjusted to a suitable temperature by heating the outflow portion.

In the above configuration, the maximum value of the first alternating current supplied to the discharge unit is A, the maximum value of the second alternating current supplied to the main body is B, and the third alternating current flowing through the first electrode by supplying the current to the transfer device. When the maximum value of the current is C and the maximum value of the fourth alternating current supplied to the outflow portion is D, the third alternating current satisfies the relationship ^{(A 2} + B ² + D ² + AB + 2AD + BD) ^{1/2 ≤ C.} As described above, it is preferable to adjust the phase difference between the first alternating current, the second alternating current, and the fourth alternating current.

By adjusting the phase difference between the first alternating current, the second alternating current, and the fourth alternating current in this way, when the first alternating current is supplied to the discharging portion and when the second alternating current is supplied to the main body portion, And, the magnitude of the third alternating current flowing through the first electrode (common electrode) used for all of supplying the fourth alternating current to the outflow portion can be easily and surely increased. Then, if the phase difference between the first alternating current, the second alternating current, and the fourth alternating current is adjusted so that the third alternating current satisfies the relationship of the above equation, the third alternating current flowing through the first electrode is generated. It becomes large and the molten glass around the first electrode can be heated efficiently. Therefore, it is possible to more reliably suppress the generation of the glass stagnant layer around the bottom of the main body.

In the above configuration, it is preferable that the transfer device includes a stirring tank having a main body portion, a discharge portion, and an outflow portion.

The present invention, which was devised to solve the above problems, is a glass article manufacturing device including a transfer device for transferring molten glass, and the transfer device includes a main body having a bottom extending in the vertical direction and the inside of the main body. An outflow portion provided at the lower part of the side wall of the main body portion for transferring the molten glass in the main body, a discharge portion provided at the bottom portion of the main body portion for discharging the molten glass in the main body portion, and a first provided at the bottom portion. It is characterized by including one electrode, a second electrode provided in the discharge portion, and a power source for supplying a current to the discharge portion located between the first electrode and the second electrode.

In this way, it is possible to enjoy the same effect as the corresponding configuration described above.

According to the present invention, it is possible to suppress the generation of a glass stagnant layer around the bottom of the main body.

It is a side view which shows the manufacturing apparatus of the glass article which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the periphery of the stirring tank of the manufacturing apparatus of the glass article which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the periphery of the stirring tank of the manufacturing apparatus of the glass article which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the periphery of the stirring tank of the manufacturing apparatus of the glass article which concerns on 3rd Embodiment of this invention. It is a graph which shows the change of the 3rd alternating current which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, duplicate description may be omitted by assigning the same reference numeral to the corresponding component 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. Further, 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, in the first embodiment, a glass article manufacturing apparatus and a glass article manufacturing method are illustrated. The glass article manufacturing apparatus according to the present embodiment includes a melting furnace 1, a transfer device 2, and a molding device 3 in this order from the upstream side to the downstream side in the transfer direction of the molten glass Gm. Further, the method for producing a glass article according to the present embodiment includes a melting step, a transfer step, and a molding step in order. The method for manufacturing the glass article will be described together with the description of the configuration of the glass article manufacturing apparatus.

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.} The total amount of O, Na ₂ O and K ₂ O) 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 the 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 has a transfer path (space) inside for transferring the molten glass Gm. Consists of tubes. Here, the term transfer tube includes a tube having a tubular structure as well as a tube having a tank-like (container-like) structure.

In the present embodiment, 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 connecting each of these parts. That is, the transfer step includes a clarification step, a stirring step, and a state adjusting step.

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 molten glass Gm clarified in the clarification tank 4 is stirred by a stirring blade (stirrer) 5a and homogenized.

The state adjusting tank 6 is for carrying out a state adjusting step of adjusting the molten glass Gm stirred in the stirring tank 5 to a state suitable for molding. 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, and the like of the molten glass Gm immediately before the molding apparatus 3.

The connecting tubes 7 to 10 are formed of, for example, a cylindrical 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, in the transfer device 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 located on the downstream side above the upstream side. It is inclined to.

The molding device 3 is for carrying out a molding step of molding the molten glass Gm transferred by the transfer device 2 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 another down-draw method such as a slot down-draw method or a known molding method such as a float method.

In the case of the overflow down draw method, the molten glass Gm supplied to the molding 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 panel displays such as liquid crystal displays and organic EL displays, substrates for organic EL lighting, solar cells, and protection. Used for covers.

As shown in FIG. 2, the stirring tank 5 includes a main body portion 11, an inflow portion 12, an outflow portion 13, and a discharge portion 14.

The main body 11 is a tubular body with a bottom extending in the vertical direction, and has a stirring blade 5a inside thereof. By rotating the stirring blade 5a around an axis, the molten glass Gm in the main body 11 can be stirred.

The main body 11 includes an inflow port 15 provided on the upper side wall, an outflow port 16 provided on the lower side wall, and an outlet 17 provided on the bottom.

A cylindrical inflow portion 12 extending in the lateral direction is connected to the inflow port 15. A connecting pipe 8 is connected to the upstream end of the inflow portion 12. That is, the molten glass Gm is transferred from the previous process (in the present embodiment, the clarification tank 4) into the main body 11 through the inflow section 12.

A cylindrical outflow portion 13 extending in the lateral direction is connected to the outflow port 16. A connecting pipe 9 is connected to the downstream end of the outflow portion 13. That is, the molten glass Gm in the main body 11 is transferred to the next step (in this embodiment, the state adjusting tank 6) through the outflow portion 13.

A cylindrical discharge portion (drain) 14 extending in the vertical direction is connected to the discharge port 17. At the time of manufacturing the glass article, the discharge unit 14 is closed by the solidified glass Gx solidified in the discharge unit 14. On the other hand, when the molten glass Gm is discharged, the molten glass Gm in the main body 11 is discharged to the outside through the discharge unit 14 by heating the solidified glass Gx in the discharge unit 14 to soften and flow it.

A first electrode 18 is provided at the bottom (lower end) of the main body 11, and a second electrode 19 is provided at the lower end of the discharge portion 14. The position of the second electrode 19 may be any position of the discharge portion 14 as long as it is below the first electrode 18. However, from the viewpoint of expanding the heating region by energization of the discharge unit 14, it is preferable to provide the second electrode 19 at the lower end portion of the discharge unit 14.

Each of the electrodes 18 and 19 is formed of, for example, a ring-shaped flange portion made of platinum or a platinum alloy, and is joined to the outer peripheral surface of the stirring tank 5 at a predetermined position by welding or the like. Although not shown, the electrodes 18 and 19 are further provided with a lead-out electrode (for example, made of platinum or a platinum alloy) for connecting the current supply path 20 described later, and a cooling mechanism (for example, water cooling).

Between the first electrode 18 and the second electrode 19, a first current supply path 20 for energizing the discharge portion 14 located between the electrodes 18 and 19 is provided. The first current supply path 20 is provided with a first power supply (voltage source) 21 for applying a voltage between the first electrode 18 and the second electrode 19. By applying a voltage from the first power supply 21, the first alternating current i1 is supplied to the discharge unit 14.

In this way, the temperature of the molten glass Gm around the bottom portion of the main body portion 11 rises due to the energization heating of the discharge portion 14. As a result, the fluidity of the molten glass Gm around the bottom of the main body 11 is improved, and the generation of a glass stagnant layer around the bottom of the main body 11 can be suppressed.

The energization heating of the discharge unit 14 during the manufacture of such a glass article is such that the solidified glass Gx of the discharge unit 14 does not soften and flow, that is, the molten glass Gm does not flow out from the discharge unit 14. For example, the temperature of the solidified glass Gx of the discharge unit 14 may be energized and heated so as to be equal to or lower than the softening point. On the other hand, when the molten glass Gm in the main body 11 is discharged to the outside through the discharge unit 14, the first alternating current i1 supplied by the first power supply 21 is made larger than that at the time of manufacturing the glass article, and the discharge unit 14 is solidified. The glass Gx is softened and flowed.

(Second Embodiment)
As shown in FIG. 3, in the second embodiment, a modified example of the stirring tank 5 is illustrated. Since the basic configuration of the stirring tank 5 is the same as that of the first embodiment, the differences from the first embodiment will be mainly described.

In the present embodiment, the third electrode 22 is provided at the upper end of the main body 11. The position of the third electrode 22 may be any position of the main body 11 as long as it is on the upstream side of the first electrode 18. However, from the viewpoint of expanding the heating region by energization of the main body 11, the position of the third electrode 22 is preferably above the liquid level Gs of the molten glass Gm in the main body 11, and the main body 11 It is more preferably the upper end portion.

A second current supply path 23 for energizing the main body 11 located between the electrodes 18 and 22 is provided between the first electrode 18 and the third electrode 22. The second current supply path 23 is provided with a second power source (voltage source) 24 for applying a voltage between the first electrode 18 and the third electrode 22. By applying a voltage from the second power supply 24, the second alternating current i2 is supplied to the main body 11. The first electrode 18 is a common electrode used in both the first current supply path 20 and the second current supply path 23.

In this way, the molten glass Gm in the main body 11 can be adjusted to a suitable temperature by energizing and heating the main body 11. Therefore, even if the magnitude of the first alternating current i1 supplied to the discharge portion 14 by the first power supply 21 is reduced, the generation of the glass stagnant layer around the bottom portion of the main body portion 11 can be reliably suppressed.

Further, in the present embodiment, the stirring tank 5 is provided with a phase adjusting unit 25 for adjusting the phase difference θ between the first alternating current i1 and the second alternating current i2. The phase adjusting unit 25 is connected to the first power supply 21 and the second power supply 24. The first power supply 21, the second power supply 24, 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 θ 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.).

For example, the phase adjusting unit 25 flows the maximum value of the first alternating current i1 to A, the maximum value of the second alternating current i2 to B, and the supply of the first alternating current i1 and the second alternating current i2 to the first electrode 18. When the maximum value of the third alternating current i3 is C, the phase difference 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). It is configured to adjust θ. That is, in the method for manufacturing a glass article, in the transfer step (in the present embodiment, the stirring step included in the transfer step), the first alternating current i3 satisfies the relationship of the following formula (1). The phase difference θ between the alternating current i1 and the second alternating current i2 is adjusted.
(A ² + B ² + AB) ^1/2 ≤ C ... (1)

Here, i1 = Asin (ωt + θ), i2 = Bsinωt, and i3 = i2-i1 are defined. Note that ω is the angular velocity, t is the time, and θ is the phase difference of the first alternating current i1 with respect to the second alternating current i2. The phase difference θ is based on the phase of the second alternating current i2, but is not limited thereto. Since the direction of each current is defined in FIG. 3, when the base of the first electrode 18 (the junction with the main body 11) is considered as a branch point, the inflow current to the branch point is i2, and the inflow current from the branch point is i2. Since the outflow currents are i1 and i3, the third alternating current i3 is represented by "i2-i1" 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 = Bsinωt-Asin (ωt + θ)
= (B-Acosθ) sinωt-Asinθcosωt ... (2)

Further, the equation (2) can be expressed by the following equation (2)'from the composition formula of the trigonometric function.
i3 = {(B-Acosθ) ² + A ² sin ² θ} ^1/2 sin (ωt-α)
= (A ² + B ² -2ABcosθ) ^1/2 sin (ωt-α) ... (2)'
Here, sin α = Asin θ / (A ² + B ² -2 AB ^{cos θ) 1/2} , and cos α = (B-A cos θ) / (A ² + B ² -2 AB cos θ) ^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 -2ABcosθ) ^1/2 ... (3)

By adjusting the phase difference θ 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 first electrode 18 can be easily and surely adjusted. Then, if the phase difference θ 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 first electrode 18. 3 The alternating current i3 becomes large, and the periphery of the bottom of the first electrode 18 and the main body 11 can be efficiently heated. Therefore, the flow of the molten glass Gm around the bottom of the main body 11 becomes good. That is, the generation of the glass stagnant layer around the bottom of the main body 11 can be suppressed more reliably.

The phase adjusting unit 25 is preferably configured to adjust the phase difference θ of the first alternating current i1 and the second alternating current i2 so as to satisfy the relationship of the following equation (4).
A + B = C ... (4)

Here, the phase difference θ is preferably 120 ° to 240 ° (or −120 ° to −240 °), and more preferably 180 ° (or −180 °). The left side of the equation (1) is the value of the equation (3) when θ = 120 ° (or −120 °), and the left side of the equation (4) is θ = 180 ° (or −180 °). 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 the same value, but are preferably different values (for example, B> A). Further, 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 θ 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 stirring tank 5 is illustrated. Since the basic configuration of the stirring tank 5 is the same as that of the second embodiment, the differences from the second embodiment will be mainly described.

In the present embodiment, the fourth electrode 26 is provided at the outflow portion 13 (in the illustrated example, the downstream end of the outflow portion 13).

Between the first electrode 18 and the fourth electrode 26, a third current supply path 27 for energizing the outflow portion 13 located between the electrodes 18 and 26 is provided. The third current supply path 27 is provided with a third power source (voltage source) 28 for applying a voltage between the first electrode 18 and the fourth electrode 26. By applying a voltage from the third power source 28, the fourth alternating current i4 is supplied to the outflow section 13. The first electrode 18 is a common electrode used in all of the first current supply path 20, the second current supply path 23, and the third current supply path 27.

In this way, the molten glass Gm in the outflow portion 13 can be adjusted to a suitable temperature by energizing and heating the outflow portion 13. Therefore, even if the magnitude of the first alternating current i1 supplied to the discharge portion 14 by the first power supply 21 is reduced, the generation of the glass stagnant layer around the bottom portion of the main body portion 11 can be reliably suppressed.

Further, in the present embodiment, the phase adjusting unit 25 is connected to the first power supply 21, the second power supply 24, and the third power supply 28, and has a phase difference θ1 between the first alternating current i1 and the second alternating current i2, and the first It is configured to adjust the phase difference θ2 of the two alternating currents i2 and the fourth alternating current i4. The first power supply 21, the second power supply 24, the third power supply 28, and the phase adjusting unit 25 are composed of, for example, a three-phase AC power supply.

For example, 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, the maximum value of the third alternating current i3 to C, and the maximum value of the fourth alternating current i4. In the case of D, the phase difference θ1 of the first alternating current i1 and the second alternating current i2, the second alternating current i2, and the second alternating current i2 so that the third alternating current i3 satisfies the relationship of the following equation (5). It is configured to adjust the phase difference θ2 of the fourth alternating current i4. That is, in the method for manufacturing a glass article, in the transfer step (in the present embodiment, the stirring step included in the transfer step), the first alternating current i3 satisfies the relationship of the following formula (5). The phase difference θ1 of the alternating current i1 and the second alternating current i2 and the phase difference θ2 of the second alternating current i2 and the fourth alternating current i4 are adjusted.
(A ² + B ² + D ² + AB + 2AD + BD) ^1/2 ≤ C ... (5)

Here, i1 = Asin (ωt + θ1), i2 = Bsinωt, i4 = Dsin (ωt + θ2), i3 = i2-i1-i4 are defined. Note that ω is the angular velocity, t is the time, θ1 is the phase difference of the first alternating current i1 with respect to the second alternating current i2, and θ2 is the phase difference of the fourth alternating current i4 with respect to the second alternating current i2. The phase differences θ1 and θ2 are based on the phase of the second alternating current i2, but are not limited thereto. The third alternating current i3 is a current flowing through the first electrode 18 by supplying the first alternating current i1, the second alternating current i2, and the fourth alternating current i4.

In this case, the third alternating current i3 can be expressed by the following equation (6) from the addition theorem of trigonometric functions.
i3 = Bsinωt-Asin (ωt + θ1) -Dsin (ωt + θ2)
= (B-Acosθ1-Dcosθ2) sinωt
-(Asinθ1 + Dsinθ2) cosωt ... (6)

Further, equation (6) can be expressed by the following equation (6)'from the composition formula of trigonometric functions.
i3 = {(B-Acosθ1-Dcosθ2) ²
+ (Asinθ1 + Dsinθ2) ² } ^1/2 sin (ωt−α) ・ ・ ・ (6)'
However, if r = {(B-Acosθ1-Dcosθ2) ² + (Asinθ1 + Dsinθ2) ² } ^1/2 , then sinα = (Asinθ1 + Dsinθ2) / r and cosα = (B-Acosθ1-Dcosθ2) / r.

Since -1 ≤ sin (ωt-α) ≤ 1, the equation (6)'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 (7).
C = {(B-Acosθ1-Dcosθ2) ²
+ (Asinθ1 + Dsinθ2) ² } ^1/2 ... (7)

By adjusting the phase differences θ1 and θ2 between the first alternating current i1, the second alternating current i2, and the fourth alternating current i4 in this way, the magnitude of the third alternating current i3 flowing through the first electrode 18 can be simplified. And it can be adjusted reliably. Then, the phase differences θ1 and θ2 between the first alternating current i1, the second alternating current i2, and the fourth alternating current i4 are adjusted so that the third alternating current i3 satisfies the relationship of the above equation (5). For example, the third alternating current i3 flowing through the first electrode 18 becomes large, and the periphery of the bottom of the first electrode 18 and the main body 11 can be efficiently heated. Therefore, it is possible to more reliably suppress the generation of a glass stagnation layer around the bottom of the main body 11.

The phase adjusting unit 25 adjusts the phase differences θ1 and θ2 between the first alternating current i1, the second alternating current i2, and the fourth alternating current i4 so as to satisfy the relationship of the following equation (8). It is preferably configured.
A + B + D = C ... (8)

Here, the phase differences θ1 and θ2 are preferably 120 ° ≦ θ ≦ 240 ° (or −120 ° ≧ θ ≧ −240 °), and more preferably 180 ° (or −180 °). The left side of the equation (5) is the value of the equation (7) when θ1 = θ2 = 120 ° (or −120 °), and the left side of the equation (8) is θ1 = θ2 = 180 ° (or). It is the value of the equation (7) when −180 °).

The maximum value A of the first alternating current i1, the maximum value B of the second alternating current i2, and the maximum value D of the fourth alternating current i4 may be the same value, but are preferably different values (for example,). B> D> A). Further, the maximum value A of the first alternating current i1, the maximum value B of the second alternating current i2, and the fourth alternating current current are satisfied together with the phase differences θ1 and θ2 so as to satisfy the relationship of the above equation (5) or (8). At least one of the maximum values D of i4 may be adjusted.

The present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-mentioned effects. The present invention can be modified in various ways without departing from the gist of the present invention.

The energization heating method described in the above embodiment can also be applied to a stirring tank in which a plurality of main bodies are connected. In this case, it is preferable to connect the upper part of one of the two adjacent main bodies and the lower part of the other with a connecting pipe.

In the above embodiment, an electrode may be further provided in the inflow portion of the stirring tank, and further energization may be performed between the electrode of the inflow portion and the third electrode of the main body portion. In this way, heating of the inflow portion and the upper end portion of the main body portion is promoted.

The energization heating method described in the above embodiment can be similarly applied to a portion of the transfer device other than the stirring tank.

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.

Hereinafter, examples according to the present invention will be described, but the present invention is not limited to these examples.

In this embodiment, in the stirring tank 5 shown in FIG. 4, the phase difference θ1 between the first alternating current i1 and the second alternating current i2 and the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 are changed. The changes in the third alternating current i3 and its maximum value C when the current is made are shown. The maximum value A of the first alternating current i1 was 500A, the maximum value B of the second alternating current i2 was 3000A, and the maximum value D of the fourth alternating current i4 was 2000A. The third alternating current i3 and its maximum value C at this time can be obtained from the above equations (6) and (7). The results are shown in FIG. 5 and Table 1.

From FIG. 5 and Table 1, if the phase difference θ1 between the first alternating current i1 and the second alternating current i2 and the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 are not properly managed, Examples 4 to 4 to It can be seen that the maximum value C of the third alternating current i3 becomes smaller as in No. 5, and the heating efficiency of the first electrode 18 and its surroundings decreases. On the other hand, if the phase difference θ1 between the first alternating current i1 and the second alternating current i2 and the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 are appropriately managed, as in the first to third embodiments. It can be seen that the maximum value C of the third alternating current i1 becomes large, and the first electrode 18 and its surroundings can be efficiently heated. Here, in Examples 1 and 2, the maximum value C of the third alternating current i1 satisfies the relationship of the above equation (5), and in the third embodiment, the maximum value C of the third alternating current i1 is the above equation ( The relationship of 8) is satisfied.

1 Melting furnace 2 Transfer device 3 Molding device 4 Clarification tank 5 Stirring tank 6 Condition adjustment tank 11 Main body 12 Inflow part 13 Outflow part 14 Discharge part 18 1st electrode 19 2nd electrode 20 1st current supply path 21 1st power supply 22 3rd electrode 23 2nd current supply path 24 2nd power supply 25 Phase adjustment unit 26 4th electrode 27 3rd current supply path 28 3rd power supply G Glass ribbon Gm Molten glass i1 1st AC current i2 2nd AC current i3 3rd AC current i4 4th AC current

Claims (7)

A method for manufacturing a glass article including a transfer step of transferring molten glass using a transfer device.
The transfer device includes a main body portion having a bottom extending in the vertical direction, an outflow portion provided in the lower part of a side wall of the main body portion for transferring the molten glass in the main body portion to the next step, and the said in the main body portion. A discharge portion provided at the bottom of the main body portion for discharging the molten glass, a first electrode provided at the bottom portion, and a second electrode provided at the discharge portion are provided.
A method for producing a glass article, which comprises heating the discharge portion by energizing between the first electrode and the second electrode in the transfer step. The transfer device further includes a third electrode provided on the main body on the upstream side of the first electrode.
The method for manufacturing a glass article according to claim 1, wherein in the transfer step, electricity is applied between the first electrode and the third electrode to heat the main body. The maximum value of the first alternating current supplied to the discharge unit is A, the maximum value of the second alternating current supplied to the main body is B, and the third alternating current flowing through the first electrode by supplying the current to the transfer device. When the maximum value of is C, the third alternating current is
(A ² + B ² + AB) ^1/2 ≤ C
The method for manufacturing a glass article according to claim 2, wherein the phase difference between the first alternating current and the second alternating current is adjusted so as to satisfy the above relationship. The glass transfer device further includes a fourth electrode provided in the outflow portion.
The method for manufacturing a glass article according to claim 2, wherein in the transfer step, electricity is applied between the first electrode and the fourth electrode to heat the outflow portion. The maximum value of the first alternating current supplied to the discharge unit is A, the maximum value of the second alternating current supplied to the main body is B, and the third alternating current flowing through the first electrode by supplying the current to the transfer device. When the maximum value of is C and the maximum value of the fourth alternating current supplied to the outflow portion is D,
The third alternating current is
(A ² + B ² + D ² + AB + 2AD + BD) ^1/2 ≤ C
The method for manufacturing a glass article according to claim 4, wherein the phase difference between the first alternating current, the second alternating current, and the fourth alternating current is adjusted so as to satisfy the above relationship. The method for producing a glass article according to any one of claims 1 to 5, wherein the transfer device includes a main body portion, a discharge portion, and a stirring tank having the outflow portion. A device for manufacturing glass articles provided with a transfer device for transferring molten glass.
The transfer device is
The main body with a bottom that extends in the vertical direction,
An outflow portion provided at the lower part of the side wall of the main body portion for transferring the molten glass in the main body portion to the next process,
A discharge portion provided at the bottom of the main body portion for discharging the molten glass in the main body portion, and a discharge portion provided at the bottom of the main body portion.
The first electrode provided on the bottom and
The second electrode provided in the discharge part and
An apparatus for manufacturing a glass article, which comprises a power source for supplying an electric current to the discharge portion located between the first electrode and the second electrode.

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