Glass article manufacturing method and manufacturing device

Abstract

The method for manufacturing a glass article comprises: a first stirring step for stirring molten glass in a first stirring tank (6a); a second stirring step in which the molten glass that has been subjected to the first stirring step is stirred in a second stirring tank (6b); and a molding step for molding a glass article from the molten glass that has been subjected to the second stirring step. The liquid level (GM2) of the molten glass in the second stirring tank (6b) is located at a position lower than the liquid level (GM1) of the molten glass in the first stirring tank (6a).

Description

Technical Field

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

[0002] As is known, in the manufacturing process of glass sheets, a stirring step is performed to stir molten glass, which is a raw material of the glass sheet, in a stirring tank to homogenize the molten glass. Patent document 1 discloses a technique for stirring molten glass using a first stirring tank and a second stirring tank provided in the middle of a transfer path of the molten glass.

[0003] The first stirred tank and the second stirred tank are connected by a connecting pipe. The first stirred tank and the second stirred tank are provided with stirring devices as stirrers inside. With this structure, the molten glass stirred by the first stirring device in the first stirred tank is transferred to the second stirred tank through the connecting pipe and stirred by the second stirring device in the second stirred tank.

[0004] The first stirred tank and the second stirred tank are arranged at the same height. The connecting pipe extends horizontally and connects the upper part of the first stirred tank to the upper part of the second stirred tank. With this structure, the height of the liquid level of the molten glass flowing into the first stirred tank is the same as the height of the liquid level of the molten glass flowing into the second stirred tank (refer to the document Figure 2 ).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2013 / 073059 Summary of the invention

[0008] Problems to be solved by the invention

[0009] As described above, in the conventional stirred tank structure, the liquid level of the molten glass flowing into the second stirred tank located downstream of the first stirred tank is the same as the liquid level of the molten glass supplied to the first stirred tank on the upstream side. As a result, the viscosity of the molten glass in the second stirred tank is substantially equal to the viscosity of the molten glass in the first stirred tank.

[0010] The stirred molten glass is formed into a glass ribbon by a forming device, for example. Between the second stirred tank and the forming device, a process is performed to adjust the molten glass to a viscosity suitable for forming. Specifically, a process is performed to increase the viscosity by lowering the temperature of the molten glass.

[0011] The technical subject of the present invention is to adjust the viscosity of molten glass to be suitable for molding by using a plurality of stirring tanks.

[0012] Solutions to Solve Problems

[0013] (1) The present invention is a method for manufacturing a glass article for solving the above-mentioned problems, comprising: a first stirring step of stirring molten glass in a first stirred tank; a second stirring step of stirring the molten glass that has undergone the first stirring step in a second stirred tank; and a forming step of forming a glass article from the molten glass that has undergone the second stirring step, wherein the method for manufacturing a glass article is characterized in that a liquid level of the molten glass in the second stirred tank is located at a position lower than a liquid level of the molten glass in the first stirred tank.

[0014] When the viscosity of the molten glass is low, the liquid level of the molten glass in each stirred tank is easy to rise. Therefore, in the present invention, by setting the liquid level of the molten glass in the second stirred tank to a position lower than the liquid level of the molten glass in the first stirred tank, the viscosity of the molten glass in the second stirred tank becomes high and close to the viscosity suitable for the forming process. Thus, the burden of adjusting the viscosity of the molten glass after the second stirring process can be reduced.

[0015] (2) In the method for manufacturing a glass article described in (1) above, it may be that, in the first stirring step, the molten glass supplied from a supply port provided at the upper portion of the first stirred tank is discharged from a discharge port provided at the lower portion of the first stirred tank, and the liquid level of the molten glass in the first stirred tank is located at a position lower than the top of the supply port of the first stirred tank.

[0016] According to the present inventors' understanding, it has been found that when the liquid level of the molten glass supplied to the stirred tank is located above the top of the supply port of the stirred tank, a layer of stagnant molten glass exists for a long time in the area above the supply port. Hereinafter, the layer of molten glass that continues to stagnate in the upper part of the stirred tank is referred to as a "stagnant layer".

[0017] When there is a stagnant layer in the molten glass in the first stirred tank, the molten glass in the stagnant layer is deteriorated. Due to changes in operating conditions, the deteriorated molten glass in the stagnant layer flows out, which may deteriorate the quality of glass products formed from the molten glass.

[0018] According to the present invention, the liquid level of the molten glass in the first stirred tank is set lower than the top of the supply port of the first stirred tank, thereby preventing the generation of a stagnant layer. Thus, high-quality glass products can be manufactured.

[0019] (3) In the method for manufacturing a glass article described in (2) above, it may be that, in the second stirring step, the molten glass supplied from a supply port provided at the upper portion of the second stirred tank is discharged from a discharge port provided at the lower portion of the second stirred tank, and the liquid level of the molten glass in the second stirred tank is located at a position lower than the top of the supply port of the second stirred tank.

[0020] According to this configuration, by making the liquid level of the molten glass in the second stirred tank lower than the top of the supply port of the second stirred tank, it is possible to prevent the molten glass in the second stirred tank from forming a stagnant layer. Thus, high-quality glass products can be manufactured.

[0021] (4) In the method for producing a glass article described in (3) above, the top portion of the supply port of the second stirred tank may be located at a position lower than the top portion of the supply port of the first stirred tank.

[0022] According to this structure, by setting the top of the supply port of the second stirred tank at a position lower than the top of the supply port of the first stirred tank, it is possible to prevent the molten glass in the second stirred tank from generating a stagnant layer. In addition, the bottom of the supply port of the second stirred tank is also at a position lower than the bottom of the supply port of the first stirred tank. Therefore, even if the height of the liquid level of the molten glass in the second stirred tank is set to a position lower than the height of the liquid level of the molten glass in the first stirred tank, it is easy to maintain the height of the liquid level of the molten glass in the second stirred tank higher than the bottom of the supply port of the second stirred tank, and the molten glass can be continuously processed (transferred) more stably.

[0023] (5) In the method for manufacturing a glass article according to any one of (1) to (4), the difference between the liquid level of the molten glass in the second stirred tank and the liquid level of the molten glass in the first stirred tank may be 5 mm or more. The greater the difference, the easier it is to adjust the viscosity of the molten glass after the second stirring step.

[0024] (6) The present invention is a device for manufacturing a glass article for solving the above-mentioned problems, comprising: a first stirred tank for stirring molten glass; a second stirred tank for stirring the molten glass that has passed through the first stirred tank; and a forming device for forming a glass article from the molten glass that has passed through the second stirred tank, wherein the device for manufacturing the glass article is characterized in that the first stirred tank comprises a supply port for supplying the molten glass into the first stirred tank at an upper portion of the first stirred tank, and the second stirred tank comprises a supply port for supplying the molten glass that has passed through the first stirred tank into the second stirred tank at an upper portion of the second stirred tank, and a top portion of the supply port of the second stirred tank is located at a lower position than a top portion of the supply port of the first stirred tank.

[0025] According to this structure, by making the top of the supply port of the second stirred tank lower than the top of the supply port of the first stirred tank, the liquid level of the molten glass in the second stirred tank can be lower than the liquid level of the molten glass in the first stirred tank. Thus, the molten glass in the second stirred tank can be made close to a viscosity suitable for forming.

[0026] Effects of the Invention

[0027] According to the present invention, by using a plurality of stirring tanks, it is possible to bring the molten glass close to a viscosity suitable for molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a side view which shows the manufacturing apparatus of the glass article which concerns on 1st Embodiment.

[0029] Figure 2 It is a cross-sectional view showing the internal structure of the first agitation tank and the second agitation tank.

[0030] Figure 3 It is a three-dimensional diagram of a stirring device.

[0031] Figure 4 It is a cross-sectional view showing a part of the manufacturing apparatus of the glass article of the second embodiment.

[0032] Figure 5 is a cross-sectional view of the first stirring tank. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 1 to 3 A first embodiment of a method and apparatus for manufacturing a glass article of the present invention is described. In this embodiment, a case of manufacturing a glass plate is described as an example of a glass article, but the form of the glass article is not limited to this embodiment.

[0034] like Figure 1As shown, the production apparatus 1 includes a supply path 5 for supplying molten glass from a melting furnace 2 disposed at an upstream end and a clarification chamber 3 connected to the downstream side thereof to a forming device 4 disposed at a downstream end.

[0035] The supply path 5 includes stirring tanks 6a and 6b for stirring the molten glass flowing out of the clarification chamber 3, and a kettle 7 connected to the downstream side of the stirring tanks 6a and 6b for adjusting the viscosity and flow rate of the molten glass. The clarification chamber 3 and the stirring tanks 6a and 6b, the stirring tanks 6a and 6b and the kettle 7, and the kettle 7 and the forming device 4 are connected by flow pipes 8 to 11 for flowing the molten glass. In the flow pipe 10 between the stirring tanks 6a and 6b and the forming device 4, the kettle 7 and the flow pipe 11, the molten glass is adjusted to a viscosity suitable for forming. Specifically, the viscosity is increased by lowering the temperature of the molten glass.

[0036] The forming device 4 is a device for continuously forming a glass ribbon as a basis of a glass plate from the molten glass supplied through the clarification chamber 3, the stirring tanks 6a, 6b and the kettle 7. As the forming device 4, for example, a device for performing forming by an overflow down-draw method, a device for performing forming by a slit down-draw method, etc. are used. By cutting the formed glass ribbon, a glass plate as a glass article is manufactured. In addition, after the two ends of the formed glass ribbon in the width direction are removed by cutting, the glass ribbon is wound up to manufacture a glass roll as a glass article. It should be noted that the forming device 4 can be a device for forming glass articles other than glass plates, and as an example, it can also be a device for continuously forming a glass tube or a glass rod from molten glass using the Danner method.

[0037] Hereinafter, the structure of the stirring tanks 6a and 6b will be described in detail.

[0038] The stirred tanks 6a and 6b include: a first stirred tank 6a on the upstream side, which stirs the molten glass; and a second stirred tank 6b on the downstream side, which stirs the molten glass that has passed through the first stirred tank 6a. The number of stirred tanks 6a and 6b is not limited to the present embodiment, and for example, 3 to 8 stirred tanks may be provided in the supply path 5. In the present embodiment, the first stirred tank 6a and the second stirred tank 6b use stirred tanks of the same structure.

[0039] like Figure 2 As shown in FIG. 1 , the stirred tanks 6a and 6b are formed into a cylindrical shape with the center line of the cylinder extending in the vertical direction, and the surface of the inner peripheral wall 12 thereof is made of platinum or a platinum alloy. The stirred tanks 6a and 6b are configured to be electrically heated so as to adjust the temperature of the molten glass. A first stirring device 13a is arranged in the first stirred tank 6a, and a second stirring device 13b is arranged in the second stirred tank 6b.

[0040] Supply ports 14 and 15 for flowing molten glass into stirred tanks 6a and 6b are formed at the upper portions of stirred tanks 6a and 6b. Hereinafter, the supply port formed in first stirred tank 6a is referred to as first supply port 14, and the supply port formed in second stirred tank 6b is referred to as second supply port 15.

[0041] At the bottom of stirred tanks 6a and 6b, outlets 16 and 17 are formed for allowing molten glass stirred by stirring devices 13a and 13b to flow out of stirred tanks 6a and 6b. Hereinafter, the outlet formed in first stirred tank 6a is referred to as first outlet 16, and the outlet formed in second stirred tank 6b is referred to as second outlet 17.

[0042] The first supply port 14 of the first agitation tank 6a is connected to the flow pipe 8 connecting the clarification chamber 3 and the first agitation tank 6a. The first discharge port 16 of the first agitation tank 6a is connected to the second supply port 15 of the second agitation tank 6b by the flow pipe 9. The second discharge port 17 of the second agitation tank 6b is connected to the flow pipe 10 connecting the second agitation tank 6b and the kettle 7.

[0043] In this embodiment, the first agitation tank 6a and the second agitation tank 6b are arranged at the same height. That is, the first supply port 14 of the first agitation tank 6a and the second supply port 15 of the second agitation tank 6b are arranged at the same height. Figure 2 As shown, the height Ha1 of the top 14a of the first supply port 14 is equal to the height Ha2 of the top 15a of the second supply port 15. The first discharge port 16 of the first agitated tank 6a and the second discharge port 17 of the second agitated tank 6b are arranged at the same height. The height Hb1 of the bottom 18a of the first agitated tank 6a is equal to the height Hb2 of the bottom 18b of the second agitated tank 6b.

[0044] like Figure 2 as well as Figure 3 As shown, the stirring devices 13a and 13b include a shaft 19 and a plurality of stirring blades 20 installed along the length direction (up and down direction) of the shaft 19. The surfaces of the shaft 19 and each stirring blade 20 are made of platinum or a platinum alloy. The stirring devices 13a and 13b are configured to stir the molten glass in the stirring tanks 6a and 6b by rotating the plurality of stirring blades 20 around the shaft 19 as the shaft 19 rotates. It should be noted that, in the present embodiment, five stirring blades 20 are installed on the shaft 19, but the number of stirring blades 20 may be appropriately increased or decreased.

[0045] The shaft 19 is formed as a round rod extending in the vertical direction, and its upper end is connected to a driving source (such as a motor) not shown in the figure. Figure 2 as well as Figure 3The shaft 19 rotates in the direction indicated by the arrow R. It should be noted that the lower end of the shaft 19 is different from the upper end and is a free end.

[0046] The plurality of stirring blades 20 are installed at equal intervals along the length direction of the shaft 19. The stirring blades 20 are installed so that when rotating about the shaft 19, the stirring blades 20 on the upper end side of the shaft 19 have a slower phase about the shaft 19 than the stirring blades 20 on the lower end side.

[0047] In detail, between two stirring blades 20 and 20 adjacent to each other, the stirring blade 20 on the upper side is slower than the stirring blade 20 on the lower side by the amount of angle θ about the axis 19. It should be noted that the phases of the stirring blades 20 at the bottom with the fastest phase to the stirring blades 20 at the top with the slowest phase are successively slower by the same amount of angle θ.

[0048] According to the above-mentioned phase relationship, as the plurality of stirring blades 20 rotate around the shaft 19, an upward flow of the molten glass from the bottom to the top is formed near the shaft 19. And this upward flow merges with the downward flow of the molten glass from the top to the bottom, which is the original flow in the stirring tanks 6a and 6b, and the circumferential swirling flow generated by the rotation of the stirring blades 20, thereby generating a flow along the radial direction of the shaft 19. As a result, as in Figure 2 As shown by the black arrow in the middle, the molten glass near the axis 19 and the molten glass near the inner peripheral wall 12 are replaced.

[0049] Here, in order to appropriately form an upward flow of the molten glass, the value of the angle θ is preferably within a range of 10° to 80°. In addition, in the present embodiment, the value of the angle θ is set to 45°.

[0050] Each of the plurality of stirring blades 20 includes a pair of blade bodies 21 arranged symmetrically with respect to the shaft 19 (axially symmetrically with respect to the central axis of the shaft 19). Each of the pair of blade bodies 21 has two through openings 21a formed in a rectangular plate-like body in a vertical position.

[0051] Each through opening 21a is formed into a mutually identical rectangular shape and penetrates the blade body 21 along the rotation direction of the blade body 21 (in the present embodiment, equal to the thickness direction of the blade body 21). The front end portion 21b of each blade body 21 extends along the length direction of the shaft 19. The length L of the front end portion 21b along the length direction of the shaft 19 is longer than the diameter D of the shaft 19. It should be noted that a gap is formed between the inner peripheral wall 12 of the stirring tanks 6a, 6b and the front end portion 21b of each blade body 21.

[0052] According to the configuration of the front end portion 21b and the through opening 21a, a shearing force is applied to the molten glass by the front end portion 21b of each blade body 21 near the inner peripheral wall 12 of the stirring tanks 6a and 6b as the plurality of stirring blades 20 rotate about the shaft 19. In addition, the molten glass is passed through the through opening 21a of the rotating blade body 21, thereby preventing the molten glass from rotating in the same direction as the blade body 21 in the stirring tanks 6a and 6b, and a shearing force is applied to the molten glass as it passes through the through opening 21a.

[0053] Here, in order to facilitate the passage of the molten glass through the through opening 21a, the opening ratio of the through opening 21a in each blade body 21 is preferably 30% or more. The "opening ratio" means the ratio of the opening area of ​​the through opening 21a to the area of ​​the rectangular plate-like body (plate-like body without the through opening 21a) that is the raw material of the blade body 21. In addition, in order to appropriately apply shear force to the molten glass by the front end 21b of the blade body 21, it is preferred that the length L of the front end 21b is 50% to 150% of the distance S between the two stirring blades 20, 20 adjacent to each other along the length direction of the shaft 19 as a reference.

[0054] Regarding the two stirring blades 20, 20 adjacent to each other, the front end portions 21b of the blade bodies 21 provided therein are connected to each other by a connecting portion 22 (sandwiching portion) sandwiched between the front end portions 21b. The connecting portion 22 is formed as a square rod extending along a straight line, and is arranged in a manner of connecting the back surface A1 of the blade body 21 on the relatively lower side (the side with a faster phase) with the front surface A2 of the blade body 21 on the relatively upper side (the side with a slower phase). In addition, the connecting portion 22 connects the upper end 21b1 of the front end portion 21b in the blade body 21 on the relatively lower side with the lower end 21b2 of the front end portion 21b in the blade body 21 on the relatively upper side.

[0055] The connecting portion 22 is provided on one side and the other side of the pair of blade bodies 21. Furthermore, the connecting portion 22 on one side and the connecting portion 22 on the other side are arranged symmetrically with respect to the shaft 19 (axially symmetrically with respect to the central axis of the shaft 19 when viewed from the direction along the length direction of the shaft 19). In addition to the arrangement of the connecting portion 22, as described above, the pair of blade bodies 21 are arranged symmetrically with respect to the shaft 19, so that the center of gravity of the entire stirring device 13a, 13b of the present embodiment is located on the shaft 19.

[0056] According to the above-described configuration of the connecting portion 22 , the connecting portion 22 stirs the molten glass as the plurality of stirring blades 20 rotate about the shaft 19 .

[0057] Here, in addition to the connecting portion 22 that connects the front end portions 21b of the blade bodies 21, a connecting portion 22 that connects the portions other than the front end portions 21b may be provided separately. In addition, it is also possible that the connecting portion 22 that connects the front end portions 21b is not provided, and only the connecting portion 22 that connects the portions other than the front end portions 21b is provided. Furthermore, the connecting portion 22 may be formed as a round bar instead of a square bar.

[0058] In addition, the front end portions 21b of the blade body 21 are preferably connected to each other from the viewpoint of the strength of the stirring devices 13a and 13b, but are not necessarily limited to this, and may be set to a form in which they are not connected. For example, instead of the connecting portion 22, it is also possible to set it to a form in which the front end portions 21b are not connected to each other but are only provided with a member (sandwiching portion) sandwiched between the front end portions 21b. As an example, it is also possible to set it to a form in which the connecting portion 22 in this embodiment is disconnected at its middle point and there is a gap between the two parts after the disconnection.

[0059] According to the stirring devices 13a and 13b of the present embodiment, the molten glass near the inner peripheral wall 12 of the stirring tanks 6a and 6b can be effectively stirred by the front end portion 21b of the stirring blade 20 (blade body 21). In addition, the effect of stirring the molten glass by the connecting portion 22 is obtained, so the stirring of the molten glass can be further promoted. As a result, the stirring performance of the molten glass can be improved.

[0060] Hereinafter, a method for manufacturing a glass plate (glass article) using the manufacturing apparatus 1 having the above-mentioned structure will be described.

[0061] In this method, after melting glass raw materials in a melting furnace 2 (melting process) and obtaining molten glass, the molten glass is sequentially subjected to a clarification process performed by a clarification chamber 3, a stirring process (homogenization process) performed by stirring tanks 6a and 6b, and a state adjustment process between stirring tanks 6a and 6b and a forming device 4. After that, the molten glass is transferred to the forming device 4, and a glass ribbon is formed from the molten glass (forming process). After the forming process, an annealing process is performed by an annealing furnace, and a glass ribbon is cut by a cutting device to form a glass sheet of a specified size.

[0062] Hereinafter, an embodiment of the stirring step will be described in detail.

[0063] The stirring step includes a first stirring step of stirring the molten glass in first stirred tank 6 a and a second stirring step of stirring the molten glass having passed through first stirred tank 6 a in second stirred tank 6 b .

[0064] In the first stirring step, the molten glass supplied from the first supply port 14 of the first stirred tank 6a is stirred by the first stirring device 13a and discharged from the first discharge port 16. The molten glass discharged from the first discharge port 16 is transferred to the second stirred tank 6b through the flow pipe 9. In the second stirring step, the molten glass supplied from the second supply port 15 of the second stirred tank 6b is stirred by the second stirring device 13b and discharged from the second discharge port 17. The molten glass discharged from the second discharge port 17 is transferred to the kettle 7 through the flow pipe 10.

[0065] exist Figure 2 In FIG. 1 , the liquid level of the molten glass in the first stirred tank 6 a is indicated by reference symbol GM1 , and the liquid level of the molten glass in the second stirred tank 6 b is indicated by reference symbol GM2 .

[0066] In the first stirring step, molten glass is supplied into first stirred tank 6a without its liquid level coming into contact with top 14a of first supply port 14 of first stirred tank 6a. In the first stirring step, liquid level GM1 of molten glass in first stirred tank 6a is located lower than top 14a of first supply port 14.

[0067] In order to make the height H1 of the liquid level GM1 of the molten glass lower than the height Ha1 of the top 14a of the first supply port 14, it is preferable to adjust the energized heating of the first stirred tank 6a to reduce the temperature of the molten glass. As a result, the viscosity of the molten glass increases and the height H1 of the liquid level GM1 decreases. In addition to the above method, it is also possible to adjust the height of the first stirred tank 6a so that the liquid level GM1 of the molten glass is located at a position lower than the top 14a of the first supply port 14.

[0068] In addition, the height of the liquid level of the molten glass can be adjusted by adjusting the rotation speed of the stirring devices 13a and 13b. Alternatively, the height of the liquid level of the molten glass can be adjusted by replacing the stirring devices with different shapes (stirring forces). For example, if the rotation speed of the first stirring device 13a is greater than the rotation speed of the second stirring device 13b, the molten glass in the first stirred tank 6a is likely to remain in the first stirred tank 6a. That is, the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a becomes higher, and the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b becomes lower.

[0069] In the second stirring step, the molten glass that has undergone the first stirring step is supplied into the second stirred tank 6b without its liquid level coming into contact with the top 15a of the second supply port 15 in the second stirred tank 6b. In the second stirring step, the liquid level GM2 of the molten glass in the second stirred tank 6b is located at a position lower than the top 15a of the second supply port 15.

[0070] In the stirring step, the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b is lower than the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a. The difference ΔH (H1-H2) between the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a and the height H2 of the liquid level GM2 in the molten glass in the second stirred tank 6b is preferably set to 1 mm or more, 5 mm or more, 10 mm or more, 15 mm or more, or 20 mm or more. The height difference ΔH is preferably 40 mm or less. The larger the height difference ΔH, the easier it is to adjust the viscosity of the molten glass in the subsequent process, and the molten glass can be stirred more uniformly.

[0071] The difference ΔH (H1-H2) can be increased or decreased by adjusting the temperature difference between the molten glass in the first stirred tank 6a and the second stirred tank 6b, for example. More specifically, if the temperature of the molten glass is lowered by reducing the electric heating of the second stirred tank 6b, the difference ΔH (H1-H2) increases. On the other hand, if the temperature of the molten glass is raised by increasing the electric heating of the second stirred tank 6b, the difference ΔH (H1-H2) decreases. The difference (T1-T2) between the temperature T1 (°C) of the molten glass in the first stirred tank 6a and the temperature T2 (°C) of the molten glass in the second stirred tank 6b is preferably 5°C or more, 10°C or more, 20°C or more, and 30°C or less. The temperature difference is preferably 100°C or less. Here, the temperature T1 (°C) of the molten glass in the first stirred tank 6a and the temperature T2 of the molten glass in the second stirred tank 6b are temperatures obtained by measuring the temperature of the liquid surface of the molten glass using a radiation thermometer.

[0072] The difference ΔH (H1-H2) can also be increased or decreased by adjusting the rotation speed of the stirring devices 13a and 13b or replacing the stirring devices with stirring devices having different shapes (stirring forces).

[0073] According to the manufacturing method and manufacturing device 1 of the glass article of the present embodiment described above, the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b is set to a position lower than the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a, so that the viscosity of the molten glass in the second stirred tank 6b can be increased to be suitable for the forming process. Thus, after the second stirring process, when the state adjustment process is performed between the stirred tanks 6a, 6b and the forming device 4, the burden of adjusting the viscosity of the molten glass can be reduced.

[0074] Furthermore, when the liquid level GM1 of the molten glass supplied to the first stirred tank 6a is located above the top 14a of the first supply port 14 of the first stirred tank 6a, a stagnant layer of the molten glass is easily generated in the region above the first supply port 14. When a stagnant layer exists in the molten glass in the first stirred tank 6a, the molten glass in the stagnant layer is degraded, and the degraded glass is mixed into the molten glass, which may deteriorate the quality of the glass article formed from the molten glass.

[0075] According to the present embodiment, by making height H1 of liquid level GM1 of molten glass in first stirred tank 6a lower than height Ha1 of top portion 14a of first supply port 14 in first stirred tank 6a, generation of a stagnant layer in the molten glass in first stirred tank 6a can be prevented.

[0076] Similarly, by making the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b lower than the height Ha2 of the top 15a of the second supply port 15 in the second stirred tank 6b, it is possible to prevent the molten glass in the second stirred tank 6b from generating a stagnant layer. Thus, high-quality glass products can be manufactured.

[0077] Figure 4 A second embodiment of the manufacturing method and manufacturing device of the glass article of the present invention is shown. In this embodiment, the manufacturing device has three stirred tanks, namely, a first stirred tank 6a, a second stirred tank 6b, and a third stirred tank 6c, in the supply path 5. The first stirred tank 6a and the second stirred tank 6b are connected via a flow pipe 9a. The second stirred tank 6b and the third stirred tank 6c are connected via a flow pipe 9b.

[0078] In the present embodiment, the first stirring device 13a provided in the first stirred tank 6a has the same structure as the stirring device used in the first embodiment. The second stirring device 13b provided in the second stirred tank 6b and the third stirring device 13c provided in the third stirred tank 6c do not have the connecting portion 22 provided in the first stirring device 13a. Therefore, the first stirring device 13a is superior in stirring force compared with the second stirring device 13b and the third stirring device 13c. For example, when the first stirring device 13a is replaced from a stirring device having a connecting portion 22 to a stirring device not having a connecting portion 22, the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a is reduced. The second stirring device 13b and the third stirring device 13c have four stirring blades 20, but the number of stirring blades 20 is not limited to the present embodiment.

[0079] In the present embodiment, second agitated tank 6b is disposed at a position lower than first agitated tank 6a in the vertical direction. Therefore, height Ha2 of top 15a of second supply port 15 of second agitated tank 6b is lower than height Ha1 of top 14a of first supply port 14 of first agitated tank 6a. Similarly, height Hb2 of bottom 18b of second agitated tank 6b is lower than height Hb1 of bottom 18a of first agitated tank 6a.

[0080] Third agitated tank 6c is disposed at a position lower than second agitated tank 6b in the vertical direction. Therefore, height Ha3 of top 23a of third supply port 23 formed in the upper portion of third agitated tank 6c is lower than height Ha2 of top 15a of second supply port 15 of second agitated tank 6b. In addition, height Hb3 of bottom 18c of third agitated tank 6c is lower than height Hb2 of bottom 18b of second agitated tank 6b.

[0081] The stirring step in the method for producing a glass plate of the present embodiment includes a first stirring step performed in the first stirred tank 6 a , a second stirring step performed in the second stirred tank 6 b , and a third stirring step performed in the third stirred tank 6 c .

[0082] In the first stirring step, molten glass supplied from first supply port 14 of first stirred tank 6a is stirred by first stirring device 13a and discharged from first discharge port 16. The molten glass discharged from first discharge port 16 is transferred to second stirred tank 6b through flow pipe 9a.

[0083] In the first stirring step, the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a is lower than the height Ha1 of the top portion 14a of the first supply port 14 of the first stirred tank 6a.

[0084] In the second stirring step, molten glass supplied from second supply port 15 of second stirred tank 6b is stirred by second stirring device 13b and discharged from second discharge port 17. The molten glass discharged from second discharge port 17 is transferred to third stirred tank 6c through flow pipe 9b.

[0085] In the second stirring step, the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b is lower than the height Ha2 of the top 15a of the second supply port 15 of the second stirred tank 6b. In addition, the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b is lower than the height H1 of the liquid level GM1 of the molten glass in the first stirred tank 6a.

[0086] In the third stirring step, the molten glass supplied from the third supply port 23 of the third stirred tank 6c is stirred by the third stirring device 13c and discharged from the third discharge port 24 provided at the lower part of the third stirred tank 6c. The molten glass discharged from the third discharge port 24 is transferred to the kettle 7 through the flow pipe 10.

[0087] In the third stirring step, the height H3 of the liquid level GM3 of the molten glass in the third stirred tank 6c is lower than the height Ha3 of the top 23a of the third supply port 23 of the third stirred tank 6c. In addition, the height H3 of the liquid level GM3 of the molten glass in the third stirred tank 6c is lower than the height H2 of the liquid level GM2 of the molten glass in the second stirred tank 6b.

[0088] According to the manufacturing method and manufacturing apparatus of the glass article of the present embodiment described above, the molten glass that has passed through the first stirring step (first stirred tank 6a) passes through the second stirring step (second stirred tank 6b) and the third stirring step (third stirred tank 6c), thereby being adjusted to a viscosity close to that suitable for the subsequent forming step.

[0089] It should be noted that the present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. The present invention can be modified in various ways without departing from the gist of the present invention.

[0090] In the above embodiment, the manufacturing apparatus 1 is illustrated as having the same size of the stirred tanks 6a to 6c, but the present invention is not limited thereto, and the sizes of the stirred tanks 6a to 6c may be different. For example, the vertical dimension of the second stirred tank 6b may be larger than the vertical dimension of the first stirred tank 6a.

[0091] Figure 5 This is an embodiment showing the electrical heating of the molten glass in the stirred tank.

[0092] like Figure 5 As shown, the first stirred tank 6a includes a first electrode 25, a second electrode 26, a third electrode 27, and a fourth electrode 28. The first electrode 25 is provided in the flow tube 8 connected to the upper portion 6a1 of the first stirred tank 6a. The second electrode 26 is provided in the upper portion (top) 6a1 of the first stirred tank 6a. The third electrode 27 is provided in the lower portion 6a2 (bottom portion 18a) of the first stirred tank 6a. The fourth electrode 28 is provided in the flow tube 9 connected to the lower portion 6a2 of the first stirred tank 6a.

[0093] Each electrode 25 to 28 is composed of an annular flange portion made of platinum or a platinum alloy, for example. It should be noted that each electrode 25 to 28 also includes an extraction electrode (for example, platinum, platinum alloy, nickel or nickel alloy) for connecting the current supply paths 29, 31, 33 described later, and a cooling mechanism (for example, water cooling or air cooling), which is omitted in the figure.

[0094] A first current supply path 29 for supplying electricity to the upper portion 6a1 of the first agitated tank 6a is provided between the first electrode 25 and the second electrode 26. A first power source 30 (voltage source) for applying a voltage between the first electrode 25 and the second electrode 26 is provided in the first current supply path 29. By applying a voltage from the first power source 30, the first alternating current i1 is supplied to the upper portion 6a1 of the first agitated tank 6a.

[0095] A second current supply path 31 for passing electricity from the upper portion 6a1 of the first stirred tank 6a to the lower portion 6a2 (bottom portion 18a) is provided between the second electrode 26 and the third electrode 27. A second power source 32 (voltage source) for applying a voltage between the second electrode 26 and the third electrode 27 is provided in the second current supply path 31. By applying a voltage using the second power source 32, a second alternating current i2 is supplied to the upper portion 6a1 and the lower portion 6a2 (bottom portion 18a) of the first stirred tank 6a. It should be noted that the second electrode 26 is a common electrode used in both the first current supply path 29 and the second current supply path 31.

[0096] like Figure 5 As shown, the third alternating current i3 is supplied to the second electrode 26 by supplying the first alternating current i1 and the second alternating current i2.

[0097] A third current supply path 33 for supplying electricity to the lower portion 6a2 of the first stirred tank 6a is provided between the third electrode 27 and the fourth electrode 28. A third power source 34 (voltage source) for applying a voltage between the third electrode 27 and the fourth electrode 28 is provided in the third current supply path 33. By applying a voltage using the third power source 34, a fourth alternating current i4 is supplied to the lower portion 6a2 of the first stirred tank 6a. It should be noted that the third electrode 27 is a common electrode used in both the second current supply path 31 and the third current supply path 33.

[0098] like Figure 5 As shown, the fifth alternating current i5 is supplied to the third electrode 27 by supplying the second alternating current i2 and the fourth alternating current i4.

[0099] The first stirred tank 6 a is provided with a phase adjustment unit 35 that adjusts a phase difference θ1 between the first alternating current i1 and the second alternating current i2 and a phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 .

[0100] The phase adjustment unit 35 is connected to each power source 30, 32, 34. Each power source 30, 32, 34 is, for example, a three-phase AC power source. In the case of a three-phase AC power source, the phase difference θ1 between the first AC current i1 and the second AC current i2 and the phase difference θ2 between the second AC current i2 and the fourth AC current i4 can be adjusted by appropriately changing the connection terminals (for example, TR, RT, RS, SR, etc.).

[0101] The phase adjustment unit 35 is configured to adjust 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 formula (1) when the maximum value of the first alternating current i1 is set to A, the maximum value of the second alternating current i2 is set to B, and the maximum value of the third alternating current i3 is set to C. That is, in the method for manufacturing a glass article of the present invention, in the first stirring step, 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 following formula (1).

[0102] (A 2 +B 2 +AB) 1 / 2 >C (1)

[0103] Here, it is defined as i1 = Asinωt, i2 = Bsin(ωt + θ1), i3 = i1 - i2. It should be noted that ω is the angular velocity, t is the time, and θ1 is the phase difference of the second alternating current i2 relative 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 to this. Figure 5 The directions of the currents are defined in , so when the root of the second electrode 26 (the junction with the first stirred tank 6a) is considered as a branch point, the inflow current into the branch point becomes i1, and the outflow currents from the branch point become i2 and i3. Therefore, the third alternating current i3 is represented by "i1-i2" as described above according to Kirchhoff's law.

[0104] In this case, the third alternating current i3 can be expressed by the following equation (2) based on the addition theorem of trigonometric functions.

[0105] i3=Asinωt-Bsin(ωt+θ1)

[0106] =(A-Bcosθ1)sinωt-Bsinθ1cosωt (2)

[0107] Furthermore, the formula (2) can be expressed by the following formula (2)′ based on the synthesis formula of trigonometric functions.

[0108] i3={(A-Bcosθ1) 2 +B 2 sin 2 θ1 1 / 2 sin(ωt-α)

[0109] =(A 2 +B 2 -2ABcosθ1) 1 / 2 sin(ωt-α) (2)'

[0110] Where sinα=Bsinθ1 / (A 2 +B 2 -2ABcosθ1) 1 / 2 , cosα=(A-Bcosθ1) / (A 2 +B 2 -2ABcosθ1) 1 / 2 .

[0111] −1≤sin(ωt−α)≤1, so when sin(ωt−α)=1, the formula (2)′ shows the maximum value. That is, the maximum value C of the third alternating current i3 is expressed by the following formula (3).

[0112] C=(A 2 +B 2 -2ABcosθ1) 1 / 2 (3)

[0113] In this example, the second electrode 26 provided in the upper portion 6a1 of the first stirred tank 6a is located at a position separated from the liquid level GM1 of the molten glass, and a gas phase space exists in the upper portion 6a1. Therefore, when the third alternating current i3 is too large, the upper portion 6a1 of the first stirred tank 6a near the second electrode 26 may be melted.

[0114] In this regard, as described above, by adjusting the phase difference θ1 between the first alternating current i1 and the second alternating current i2, the magnitude of the third alternating current i3 flowing to the second electrode 26 can be simply and reliably adjusted. Furthermore, 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-mentioned formula (1), the third alternating current i3 flowing to the second electrode 26 becomes appropriately small, and the melting loss of the first stirred tank 6a near the second electrode 26 can be reliably suppressed. Furthermore, the height of the liquid level GM1 of the molten glass in the first stirred tank 6a can be appropriately adjusted.

[0115] The phase adjustment unit 35 is configured to adjust the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 so that the fifth alternating current i5 satisfies the relationship of the following formula (4) when the maximum value of the fourth alternating current i4 is set to D and the maximum value of the fifth alternating current i5 is set to E. That is, in the manufacturing method of the glass article of the present invention, in the first stirring step, the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 is adjusted so that the fifth alternating current i5 satisfies the relationship of the following formula (4).

[0116] (B 2 +D 2 +BD) 1 / 2 ≤E (4)

[0117] By referring to the above-mentioned equations (2), (2)′, and (3), the maximum value E of the fifth alternating current i5 is expressed by the following equation (5).

[0118] E=(B 2 +D 2 -2DEcosθ2) 1 / 2 (5)

[0119] In the lower portion 6a2 of the first stirred tank 6a, it is preferred to heat efficiently to avoid stagnation of the molten glass. By adjusting the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 as described above, the magnitude of the fifth alternating current i5 flowing to the third electrode 27 can be simply and reliably adjusted. Furthermore, if the phase difference θ2 between the second alternating current i2 and the fourth alternating current i4 is adjusted in such a manner that the fifth alternating current i5 satisfies the relationship of the above-mentioned formula (4), the fifth alternating current i5 flowing to the third electrode 27 becomes larger, and the molten glass around the lower portion 6a2 of the first stirred tank 6a and the bottom 18a can be efficiently heated. Therefore, the flow of the molten glass around the lower portion 6a2 and the bottom 18a becomes good. That is, a glass stagnation layer containing heterogeneous glass is generally easy to be generated around the bottom 18a, but this can be suppressed.

[0120] The method of heating the molten glass in the first stirred tank 6 a as described above can also be applied to the second stirred tank 6 b (second stirring step) and the third stirred tank 6 c (third stirring step).

[0121] Description of Reference Numerals

[0122] 1 Manufacturing equipment

[0123] 4 Forming device

[0124] 6a First stirring tank

[0125] 6b Second stirring tank

[0126] 14 First supply port

[0127] 14a Top of the first supply port

[0128] 15 Second supply port

[0129] 15a Top of the second supply port

[0130] 16 Exit 1

[0131] 17 Second row exit

[0132] 18a Bottom of the first stirring tank

[0133] 18b Bottom of the second mixing tank

[0134] GM1 Liquid level of molten glass in the first stirred tank

[0135] GM2 The liquid level of the molten glass in the second stirred tank

[0136] H1 Height of the liquid level of the molten glass in the first stirred tank

[0137] H2 Height of the liquid level of the molten glass in the second stirred tank

[0138] Ha1 Height of the top of the first supply port

[0139] Ha2 Height of the top of the second supply port

[0140] Hb1 Height of the bottom of the first stirring tank

[0141] Hb2 Height of the bottom of the second stirred tank.

Claims

1. A method for manufacturing a glass article, comprising: a first stirring step of stirring the molten glass in a first stirring tank; a second stirring step of stirring the molten glass that has undergone the first stirring step in a second stirred tank; as well as forming a glass article from the molten glass that has undergone the second stirring step, The method for manufacturing the glass article is characterized in that: The liquid level of the molten glass in the second stirred tank is located at a position lower than the liquid level of the molten glass in the first stirred tank.

2. The method for manufacturing a glass article according to claim 1, wherein: In the first stirring step, the molten glass supplied from the supply port provided at the upper portion of the first stirred tank is discharged from the discharge port provided at the lower portion of the first stirred tank. The liquid level of the molten glass in the first stirred tank is located at a position lower than a top portion of the supply port of the first stirred tank.

3. The method for manufacturing a glass article according to claim 2, wherein: In the second stirring step, the molten glass supplied from the supply port provided at the upper portion of the second stirred tank is discharged from the discharge port provided at the lower portion of the second stirred tank, The liquid level of the molten glass in the second stirred tank is located at a position lower than the top of the supply port of the second stirred tank.

4. The method for manufacturing a glass article according to claim 3, wherein: The top portion of the supply port of the second agitated tank is located at a position lower than the top portion of the supply port of the first agitated tank.

5. The method for producing a glass article according to any one of claims 1 to 4, wherein: A difference between a height of a liquid level of the molten glass in the second stirred tank and a height of a liquid level of the molten glass in the first stirred tank is 5 mm or more.

6. A device for manufacturing glass articles, comprising: a first stirring tank for stirring the molten glass; a second stirred tank for stirring the molten glass having passed through the first stirred tank; and a forming device for forming a glass article from the molten glass that has passed through the second stirring tank, The manufacturing device of the glass article is characterized in that: The first stirred tank includes a supply port at an upper portion of the first stirred tank for supplying the molten glass into the first stirred tank. The second stirred tank includes a supply port at an upper portion of the second stirred tank for supplying the molten glass having passed through the first stirred tank into the second stirred tank. The top of the supply port of the second agitated tank is located at a position lower than the top of the supply port of the first agitated tank.

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