JP2016069235A - Manufacturing method for glass substrate and manufacturing apparatus for glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a glass substrate and a manufacturing apparatus for a glass substrate that reduce formation of a stria by efficiently discharging glass foreign matter from an agitation device and uniformly stirring molten glass.SOLUTION: A stirring process comprises stirring molten glass G by a stirring device 100 comprising a stirring container 101 and a stirrer 102. A discharging process comprises discharging glass foreign matter formed on a glass liquid surface GL in the stirring container 101 from a discharge port 111a provided to a side wall of the stirring container 101. The discharging process comprises adjusting a height position of the glass liquid surface GL in the stirring container 101 so that a height position of the glass liquid surface GL in the stirring container 101 is within a range from a lower end to an upper end of the discharge port 111a.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a glass substrate manufacturing method and a glass substrate manufacturing apparatus.

  In the mass production process of glass products such as glass substrates, glass materials such as glass substrates are manufactured by heating glass raw materials to produce molten glass, and forming the produced molten glass. If the molten glass is inhomogeneous, striae occur in the glass product. A striae is a streak-like region having a refractive index and specific gravity different from the surroundings. In applications such as liquid crystal display (LCD) substrates, striae are required to be excluded from glass products. In order to prevent the occurrence of striae, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-100462), a molten glass is used by using a stirring device including a cylindrical stirring vessel and a stirrer. Stirring is performed so as to be uniform.

  In recent years, with the increase in the definition of liquid crystal displays, the pattern size of pixels arranged on the surface of the glass substrate has decreased, and the line width and pitch of the black matrix formed on the surface of the glass substrate have decreased. ing. Further, glass substrates used as substrates for high-definition LCDs have stricter standards for preventing the occurrence of striae compared to ordinary glass substrates, and thorough elimination of striae is strongly required.

  However, even if the molten glass is stirred using a stirrer, a glass foreign body having a glass composition different from that of the molten glass is formed on the surface of the molten glass in the stirrer, and this glass foreign body is homogenized together with the molten glass. As a result, the molten glass was discharged from the stirring vessel without causing a problem that the molten glass was not uniformly stirred. In order to solve this problem, a method of discharging the glass foreign matter from the stirring vessel can be considered, but a glass substrate cannot be manufactured while the glass foreign matter is being discharged from the stirring vessel.

  Accordingly, the present invention provides a glass substrate manufacturing method and a glass substrate manufacturing apparatus capable of reducing the occurrence of striae by efficiently discharging the glass foreign matter from the stirring device and uniformly stirring the molten glass. The purpose is to provide.

  The method for manufacturing a glass substrate according to the present invention includes a stirring step and a discharging step. The stirring step is a step of stirring the molten glass produced by melting the glass raw material with a stirring device including a stirring container and a stirrer. The discharging step is a step of discharging, in the stirring step, a glass foreign matter formed on the molten glass liquid surface in the stirring vessel and having a glass composition different from that of the molten glass from a discharge port provided on the side wall of the stirring vessel. In the discharging step, the height position of the molten glass liquid surface in the stirring vessel is adjusted so that the height position of the molten glass liquid surface in the stirring vessel falls within the range from the lower end to the upper end of the discharge port.

  In this method for manufacturing a glass substrate, a discharging step of discharging molten glass containing a glass foreign substance from the stirring vessel is performed. The glass foreign matter is contained in the molten glass at a height position in the vicinity of the molten glass liquid surface in the stirring vessel. In the discharge process, the height position of the molten glass liquid level in the stirring vessel is adjusted so that the height position of the molten glass liquid level in the stirring vessel is within the range from the lower end to the upper end of the discharge port of the stirring vessel. Is done. Thereby, in a discharge | emission process, the height position of the molten glass liquid level in the space connected via the stirring container and the discharge port becomes the same as the height position of the molten glass liquid level in a stirring container. Therefore, the molten glass containing the glass foreign matter in the stirring vessel is discharged from the stirring vessel through the discharge port without lowering the flow rate. Therefore, this glass substrate manufacturing method can reduce the occurrence of striae by efficiently discharging the glass foreign matter from the stirring device and stirring the molten glass uniformly.

  Further, in the glass substrate manufacturing method according to the present invention, in the discharging step, the flow rate of the molten glass flowing into the stirring vessel with respect to the flow rate of the molten glass discharged from the stirring vessel through the discharge port, and in the stirring vessel It is preferable that the height position of the molten glass liquid surface in the stirring vessel is adjusted by adjusting at least one of the flow rates of the molten glass that are stirred and flow out of the stirring vessel.

  Moreover, in the manufacturing method of the glass substrate which concerns on this invention, it is preferable that a stirring container has an inflow port of the molten glass formed in a side wall in the height position near the molten glass liquid surface. In this case, the discharge port is preferably opposed to the inflow port in the stirring vessel.

  Moreover, in the manufacturing method of the glass substrate which concerns on this invention, it is preferable that a stirring apparatus further has a buffer container connected via the stirring container and the discharge port. In this case, the buffer container further has a discharge pipe port for discharging the molten glass in the buffer container, and the internal space of the buffer container is preferably narrowed from the discharge port toward the discharge pipe port. .

  The apparatus for producing a glass substrate according to the present invention includes a stirring device that stirs molten glass produced by melting a glass raw material and includes a stirring container and a stirrer. The stirring vessel has a discharge port for discharging glass foreign matter formed on the surface of the molten glass in the stirring vessel and having a glass composition different from that of the molten glass. The discharge port is provided on the side wall of the stirring vessel. The stirrer adjusts the height position of the molten glass liquid surface in the stirring vessel so that the height position of the molten glass liquid surface in the stirring vessel falls within the range from the lower end to the upper end of the discharge port.

  The glass substrate manufacturing method and glass substrate manufacturing apparatus according to the present invention can reduce the occurrence of striae by efficiently discharging the glass foreign matter from the stirring device and stirring the molten glass uniformly. it can.

It is a schematic diagram which shows an example of a structure of the glass manufacturing apparatus which concerns on embodiment. It is a side view of a stirring apparatus. It is a top view of a stirring apparatus. It is a figure showing the flow of the molten glass stirred by the stirring apparatus. It is an enlarged view of the side view of a stirring apparatus, and is a figure which shows the main flows of the molten glass near a glass liquid level. It is an enlarged view of the top view of the stirrer as a comparative example, and is a view showing the main flow of the molten glass near the glass liquid surface.

(1) Overall Configuration of Glass Manufacturing Apparatus An embodiment of a glass substrate manufacturing method and a glass substrate manufacturing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a glass manufacturing apparatus 200 of the present embodiment. The glass manufacturing apparatus 200 includes a melting tank 40, a clarification tank 41, a stirring device 100, and a molding device 42. The melting tank 40 and the clarification tank 41 are connected by a conduit 43a. The clarification tank 41 and the stirring device 100 are connected by a conduit 43b. The stirring device 100 and the molding device 42 are connected by a conduit 43c. The molten glass G produced | generated by the melting tank 40 flows into the clarification tank 41 through the conduit | pipe 43a. The molten glass G clarified in the clarification tank 41 passes through the conduit 43b and flows into the stirring device 100. The molten glass G stirred by the stirring device 100 passes through the conduit 43 c and flows into the molding device 42. In the forming apparatus 42, the glass ribbon 44 is formed from the molten glass G by the overflow downdraw method.

Although not shown, the melting tank 40 includes heating means such as a burner. In the melting tank 40, the glass raw material is melted by the heating means, and the molten glass G is generated. The glass raw material is prepared so that a glass having a desired composition can be substantially obtained. As an example of the composition of the glass, non-alkali glass and fine alkali glass are SiO ₂ : 57 mass% to 70 mass%, Al ₂ O ₃ : 15 mass% to 25 mass%, B ₂ O ₃ : 0 mass% to 13 mass. wt%, MgO: 0% to 15 wt%, CaO: 0% to 20 wt%, SrO: 0% to 20 wt%, BaO: 0 wt% to 10 wt%, Na ₂ O: 0 wt% To 1% by mass, K ₂ O: 0% by mass to 1% by mass, As ₂ O ₃ : 0% by mass to 1% by mass, Sb ₂ O ₃ : 0% by mass to 1% by mass, SnO ₂ : 0% by mass to 1% by mass, Fe ₂ O ₃ : 0% by mass to 1% by mass, ZrO ₂ : 0% by mass to 1% by mass. Here, “substantially” means that the presence of other trace components is allowed in the range of less than 0.1% by mass. Moreover, regarding the glass having the above composition, each content of Fe ₂ O ₃ , As ₂ O ₃ , Sb ₂ O ₃ and SnO ₂ is a component of Fe, As, Sb or Sn having a plurality of valences, The values are respectively converted as Fe ₂ O ₃ , As ₂ O ₃ , Sb ₂ O ₃ or SnO ₂ .

  The glass raw material prepared as described above is put into the melting tank 40. In the melting tank 40, the glass raw material is melted at a temperature corresponding to its composition. Thereby, in the melting tank 40, the high temperature molten glass G of 1500 degreeC-1620 degreeC is obtained, for example.

  The molten glass G obtained in the melting tank 40 passes through the conduit 43 a from the melting tank 40 and flows into the clarification tank 41. Although not shown in the figure, the clarification tank 41 is provided with a heating means like the melting tank 40. In the clarification tank 41, the molten glass G is clarified by further raising the temperature of the molten glass G. In the clarification tank 41, the temperature of the molten glass G is preferably raised to 1600 ° C to 1800 ° C, more preferably from 1630 ° C to 1750 ° C, and even more preferably from 1650 ° C to 1750 ° C.

  The molten glass G clarified in the clarification tank 41 passes through the conduit 43b from the clarification tank 41 and flows into the stirring device 100. Since the molten glass G is cooled when passing through the conduit 43b, the molten glass G having a temperature lower than that of the molten glass G in the clarification tank 41 is stirred in the stirring device 100. Regarding the glass having the above composition, in the stirring device 100, the temperature of the molten glass G is set within a range of 1400 ° C to 1550 ° C, and the viscosity of the molten glass G is within a range of 2500 dPa · s to 450 dPa · s. It is preferable that the molten glass G is stirred after adjustment. The molten glass G is homogenized by being stirred in the stirring device 100.

  The molten glass G stirred and homogenized by the stirring device 100 passes through the conduit 43c from the stirring device 100 and flows into the molding device 42. When the molten glass G passes through the conduit 43c, it is cooled to a temperature suitable for molding in the molding apparatus 42, for example, 1200 ° C. In the forming apparatus 42, the glass ribbon 44 is formed from the molten glass G by the overflow downdraw method. Specifically, the molten glass G overflowing from the upper part of the forming device 42 flows downward along the side wall of the forming device 42, so that the glass ribbon 44 is continuously formed from the lower end of the forming device 42. The glass ribbon 44 is gradually cooled as it goes downward, and is finally cut into a glass substrate of a desired size.

(2) Configuration of Stirrer A specific configuration of the stirrer 100 will be described. FIG. 2 is a side view of the stirring device 100. FIG. 3 is a top view of the stirring device 100. The stirring device 100 mainly includes a stirring container 101, a stirrer 102, a buffer container 111, and a discharge pipe 112.

  The stirring container 101 is a cylindrical container. The stirring vessel 101 has an upstream conduit 103 attached to the upper side surface and a downstream conduit 104 attached to the lower side surface. The upstream conduit 103 is the conduit 43b of FIG. 1, and the downstream conduit 104 is the conduit 43c of FIG. Hereinafter, a hole formed in the side wall of the stirring vessel 101, which is a connection portion between the stirring vessel 101 and the upstream conduit 103, is referred to as an inflow port 103a. Moreover, the hole formed in the side wall of the stirring vessel 101, which is a connecting portion between the stirring vessel 101 and the downstream conduit 104, is referred to as an outlet 104a. In the following, “radial direction” means the radial direction of a circle that is a cross-sectional shape of the stirring vessel 101 in the horizontal direction, and “circumferential direction” means the circumferential direction of the circle. The horizontal cross-sectional shape of the stirring vessel 101 may be an ellipse.

  The molten glass G flows into the stirring vessel 101 in the horizontal direction from the upstream conduit 103 through the inlet 103a, and is stirred by the stirrer 102 while being guided downward from above in the stirring vessel 101, From the outlet 104a to the downstream conduit 104 in the horizontal direction. The height position of the glass liquid level GL which is the liquid level of the molten glass G in the stirring vessel 101 is preferably about the same as the upper end of the inflow port 103a or lower than the upper end of the inflow port 103a.

  The stirrer 102 is disposed in the stirring vessel 101 and is used for stirring the molten glass G. The stirrer 102 is made of reinforced platinum. Reinforced platinum is a material rolled by dispersing an oxide such as zirconia in platinum or a platinum alloy. Reinforced platinum has a layered platinum grain boundary structure, and has higher creep strength and tensile strength at higher temperatures than platinum or platinum alloys. Therefore, reinforced platinum is a suitable material for the stirrer 102 with which the high temperature molten glass G contacts.

  The stirrer 102 includes a cylindrical rotary shaft 105 disposed along the vertical direction, and a stirring blade 106 connected to the outer peripheral surface of the rotary shaft 105. The rotation shaft 105 rotates in the direction of the arrow in FIG. 3 around a center line L that connects the center of the cylindrical upper surface and the center of the lower surface. The rotating shaft 105 is a tubular member having a hollow inside. The stirring blade 106 is formed of a tubular member that is thinner than the rotating shaft 105. The stirring blade 106 is composed of a plurality of support tubes 106a that penetrate the rotating shaft 105 and a frame tube 106b that connects both ends of the support tube 106a. As shown in FIG. 3, when the stirring device 100 is viewed along the center line L, the plurality of support tubes 106a and the frame tube 106b overlap each other. The support tube 106a and the frame tube 106b are attached to the outer peripheral surface of the rotating shaft 105 by welding. The support tube 106a and the frame tube 106b may be an integral member.

  The buffer container 111 is attached to the upper side surface of the stirring container 101. The buffer container 111 is made of the same material as the stirring container 101. The buffer container 111 and the stirring container 101 may be an integral member. Hereinafter, a hole formed in the side wall of the stirring container 101, which is a connection portion between the stirring container 101 and the buffer container 111, is referred to as a discharge port 111a. In the stirring vessel 101, the discharge port 111a faces the inflow port 103a with the rotation shaft 105 interposed therebetween.

  The molten glass G in the stirring vessel 101 flows into the buffer vessel 111 through the discharge port 111a. When the stirrer 100 is viewed along the center line L, the internal space of the buffer container 111 has a shape in which the width, which is a circumferential dimension, gradually decreases from the discharge port 111a toward the radially outer side. Yes. In the buffer container 111, a molten glass G containing a glass foreign substance to be described later is temporarily stored.

  The discharge pipe 112 is a pipe attached to the bottom surface of the buffer container 111 and extending in the vertical direction. The discharge pipe 112 is formed of the same material as the stirring container 101 and the buffer container 111. The buffer container 111 and the discharge pipe 112 may be an integral member. Hereinafter, a hole formed in the bottom surface of the buffer container 111, which is a connection portion between the buffer container 111 and the discharge pipe 112, is referred to as a discharge pipe port 112a. The discharge pipe port 112 a is formed radially outward on the bottom surface of the buffer container 111. That is, the width of the internal space of the buffer container 111 is gradually reduced from the discharge port 111a toward the discharge pipe port 112a. The discharge pipe 112 is a pipe for discharging the molten glass G containing the glass foreign matter in the buffer container 111 to the outside of the stirring device 100. An open / close valve (not shown) that can be manually operated is attached to the discharge pipe 112. While the open / close valve is open, the molten glass G containing glass foreign matter flows into the discharge pipe 112 from the buffer container 111 through the discharge pipe port 112a, and flows through the discharge pipe 112 to be discharged. While the open / close valve is closed, the molten glass G containing the glass foreign matter is not discharged from the buffer container 111.

(3) Stirring step of stirring device The stirring step of the molten glass G by the stirring device 100 will be described. FIG. 4 is a diagram illustrating the flow of the molten glass G that is stirred by the stirring device 100. The arrows shown in FIG. 4 represent the flow direction of the molten glass G. In the stirring process, the open / close valve of the discharge pipe 112 is closed. Inside the stirring vessel 101, the molten glass G flows in the horizontal direction from the upstream conduit 103 through the inflow port 103 a. The upper end of the rotating shaft 105 of the stirrer 102 is connected to a motor (not shown). When the agitator 100 is viewed from above, the agitator 102 rotates around the center line L of the rotation shaft 105. The rotation direction of the agitator 102 is determined based on the positional relationship between the inlet 103a, the outlet 104a, and the outlet 111a, and may be clockwise or counterclockwise. In the present embodiment, the stirrer 102 rotates counterclockwise. Inside the stirring vessel 101, the molten glass G is stirred by the stirrer 102 while being gradually guided downward from above. The stirred molten glass G flows out from the inside of the stirring vessel 101 into the downstream conduit 104 in the horizontal direction through the outlet 104a. In addition, when the temperature of the molten glass G stirred by the stirring apparatus 100 has a viscosity of 10 ^2.5 dPa · s, it is preferable when it is 1450 ° C. to 1750 ° C., and when it is 1500 ° C. to 1750 ° C. It is suitable, and it is further more suitable when it is 1530 to 1750 degreeC.

(4) Discharge process of glass foreign material The discharge process of the molten glass G containing the glass foreign material by the stirring apparatus 100 is demonstrated. When stirring of the molten glass G in the stirring device 100 is continued for a long period of time, a glass foreign substance having a glass component different from the molten glass G is gradually generated in the layer near the glass liquid level GL in the stirring vessel 101. The glass foreign matter is a molten glass mainly composed of components having a specific gravity smaller than those of other components among the glass components contained in the molten glass G. Since the glass foreign matter causes striae of the glass substrate manufactured by the glass manufacturing apparatus 200, it is discharged from the stirring vessel 101 and removed during a period when the glass manufacturing apparatus 200 does not manufacture the glass substrate.

  The discharge process of the molten glass G containing glass foreign substances by the stirring device 100 is started by opening the opening / closing valve of the discharge pipe 112. In the discharging step, the height position of the glass liquid level GL in the stirring container 101 is adjusted so that the height position of the glass liquid level GL in the stirring container 101 falls within the range from the lower end to the upper end of the discharge port 111a. Is done. The range from the lower end to the upper end of the discharge port 111a means a range from the height position of the lower end of the discharge port 111a to the height position of the upper end. In FIG. 2, the range from the lower end to the upper end of the discharge port 111 a is indicated by the symbol H. By adjusting the height position of the glass liquid level GL in the stirring container 101 in this way, the height position of the liquid level of the molten glass G in the buffer container 111 is adjusted to the glass liquid level GL in the stirring container 101. It becomes the same as the height position.

  In order to adjust the height position of the glass liquid level GL in the stirring vessel 101, the discharge amount which is the flow rate of the molten glass discharged from the stirring vessel 101 through the discharge port 111a, the stirring vessel through the inlet port 103a At least one of an inflow amount that is a flow rate of the molten glass that flows into 101 and an outflow amount that is a flow rate of the molten glass that flows out of the stirring vessel 101 via the outflow port 104a is adjusted. The discharge amount can be adjusted by adjusting the opening degree of the open / close valve of the discharge pipe 112. The amount of inflow can be adjusted by adjusting the amount of glass raw material charged into the melting tank 40 upstream of the stirring device 100 and the temperature and viscosity of the molten glass G flowing upstream of the stirring device 100. The outflow amount can be adjusted by adjusting the temperature and viscosity of the molten glass G flowing downstream of the stirring device 100.

(5) Features In the method for manufacturing a glass substrate according to the present embodiment, a discharging step of discharging the molten glass G containing the glass foreign matter from the stirring vessel 101 is performed. In the discharging step, the height position of the glass liquid level GL in the stirring container 101 is adjusted so that the height position of the glass liquid level GL in the stirring container 101 falls within the range from the lower end to the upper end of the discharge port 111a. Is done. Thereby, in the discharge process, the height position of the liquid surface of the molten glass G in the buffer container 111 is the same as the height position of the glass liquid surface GL in the stirring container 101.

  As shown in FIG. 2, the liquid surface height position of the molten glass G in the buffer container 111 is made the same as the glass liquid surface GL height position in the stirring container 101, so that stirring is performed in the discharging step. The molten glass G containing the glass foreign material generated in the vicinity of the glass liquid level GL in the container 101 can be efficiently fed into the buffer container 111. The reason will be described below.

  FIG. 5 is an enlarged side view of the stirring device 100 in the vicinity of the buffer container 111. In FIG. 5, the flow of the molten glass G flowing from the stirring vessel 101 into the buffer vessel 111 in the vicinity of the glass liquid level GL is indicated by arrows. In FIG. 5, the height position of the liquid level of the molten glass G in the buffer container 111 is the same as the height position of the glass liquid level GL in the stirring container 101. Therefore, the molten glass G in the vicinity of the glass liquid level GL that flows into the stirring vessel 101 from the inlet 103 a and flows into the buffer vessel 111 from the outlet 111 a is an outlet that is a boundary between the stirring vessel 101 and the buffer vessel 111. When passing through 111a, the flow velocity is unlikely to decrease. Therefore, the molten glass G in the vicinity of the glass liquid level GL in the stirring vessel 101 efficiently flows into the buffer vessel 111 and is discharged.

  On the other hand, FIG. 6 is an enlarged view of a side view of the stirring device 100 in the vicinity of the buffer container 111 as a comparative example. In FIG. 6, the same reference numerals as those in FIG. 5 are used for convenience of explanation. In FIG. 6, in the vicinity of the glass liquid level GL, the flow of the molten glass G flowing from the stirring vessel 101 into the buffer vessel 111 is indicated by arrows. In FIG. 6, the height position of the liquid level of the molten glass G in the buffer container 111 is lower than the height position of the glass liquid level GL in the stirring container 101. In addition, the height position of the liquid level of the molten glass G in the buffer container 111 is the height position of the upper end of the discharge port 111a.

  In this case, as shown in FIG. 6, the molten glass G in the vicinity of the glass liquid level GL that flows into the stirring vessel 101 from the inlet 103a and flows into the buffer vessel 111 from the outlet 111a passes through the outlet 111a. Before starting, it flows downward in the stirring vessel 101. Therefore, as shown in FIG. 6, in the stirring vessel 101, a molten glass G is formed at a liquid surface corner portion 101 a near the discharge port 111 a, above the discharge port 111 a, and below the glass liquid level GL. May be caught. The liquid surface corner portion 101a is a space where the flow rate of the molten glass G is small, and the molten glass G of the liquid surface corner portion 101a is less likely to flow toward the discharge port 111a. Therefore, when the molten glass G in the vicinity of the glass liquid level GL flows into the buffer container 111 in the stirring vessel 101, the flow rate of the molten glass G decreases at the liquid level corner portion 101a and in the vicinity thereof. That is, the presence of the liquid surface corner portion 101 a prevents the molten glass G in the vicinity of the glass liquid surface GL from flowing into the buffer container 111, and as a result, the molten glass G containing glass foreign matter is removed from the stirring container 101. Outflow is suppressed. Moreover, if the molten glass G stays in the liquid surface corner portion 101a for a long time, glass foreign matter may accumulate in the liquid surface corner portion 101a, and the glass foreign material may flow out to the downstream conduit 104 through the outlet 104a. is there. Therefore, it is preferable that the liquid surface corner portion 101a in the stirring vessel 101 does not exist.

  In the present embodiment, the height position of the glass liquid level GL in the stirring vessel 101 is set so that the height position of the glass liquid level GL in the stirring vessel 101 is within the range from the lower end to the upper end of the discharge port 111a. Since the adjustment is made, the liquid surface corner portion 101 a shown in FIG. 6 does not exist in the stirring vessel 101. Therefore, the molten glass G containing a glass foreign material can be efficiently discharged from the stirring vessel 101.

  Therefore, in the manufacturing method of the glass substrate which concerns on this embodiment, it is suppressed that the molten glass G flows out into the downstream conduit | pipe 104 via the outflow port 104a with the glass foreign material in the stirring container 101. FIG. The glass substrate manufactured from the heterogeneous molten glass G mixed with the glass foreign matter is highly likely to cause striae. In this embodiment, the molten glass G can be uniformly stirred in the stirring device 100 by efficiently removing the glass foreign matter from the stirring vessel 101. Thereby, generation | occurrence | production of striae is suppressed and a high quality glass product can be obtained.

  In the glass substrate manufacturing method according to the present embodiment, in the stirring vessel 101, the discharge port 111a faces the inflow port 103a with the rotation shaft 105 interposed therebetween. Therefore, the molten glass G that has flowed into the stirring vessel 101 from the inflow port 103a in the discharge step easily flows through the glass liquid level GL without changing the flow direction and flows into the buffer vessel 111 from the discharge port 111a. Therefore, by providing the discharge port 111a at a position facing the inflow port 103a, the molten glass G can be discharged efficiently in the discharge process.

  Further, in the glass substrate manufacturing method according to the present embodiment, the discharge pipe port 112a is formed radially outward on the bottom surface of the buffer container 111, and the width of the internal space of the buffer container 111 is discharged from the discharge port 111a. It gradually becomes smaller toward the tube port 112a. Thus, since the circumferential dimension of the discharge port 111a is large, the molten glass G that has flowed into the stirring vessel 101 from the inflow port 103a in the discharge process flows from the discharge port 111a to the buffer container after flowing through the glass liquid level GL. It is easy to flow into 111. Therefore, the molten glass G can be efficiently discharged | emitted by providing the buffer container 111 with the large dimension of the circumferential direction of the discharge port 111a.

(6) Modification (6-1) Modification A
In this embodiment, in order to adjust the height position of the glass liquid level GL in the stirring vessel 101, at least one of the discharge amount, the inflow amount, and the outflow amount is adjusted. However, in order to adjust the height position of the glass liquid level GL in the stirring vessel 101, at least one of the ratio of the inflow amount to the discharge amount and the ratio of the outflow amount to the discharge amount may be adjusted.

(6-2) Modification B
In this embodiment, in order to adjust the height position of the glass liquid level GL in the stirring vessel 101, at least one of the discharge amount, the inflow amount, and the outflow amount is adjusted. However, the discharge amount, inflow amount, and outflow amount may be automatically controlled by a computer. Further, the ratio of the inflow amount with respect to the discharge amount and the outflow amount with respect to the discharge amount in the modified example A may be automatically controlled by a computer.

(6-3) Modification C
In the present embodiment, the molten glass G is stirred by the stirrer 102 while being gradually guided downward from above in the stirring vessel 101. However, the molten glass G may be stirred by the stirrer 102 while being gradually guided from below to above. In this case, the molten glass G flows into the stirring vessel 101 from the inlet formed on the lower side surface of the stirring vessel 101 and flows out from the outlet formed on the upper side surface of the stirring vessel 101.

(6-4) Modification D
In the glass manufacturing apparatus 200 according to the present embodiment, the stirring apparatus 100 is installed between the clarification tank 41 and the molding apparatus 42 and agitates the molten glass G clarified in the clarification tank 41. However, the stirring device 100 may be installed between the melting tank 40 and the clarification tank 41. In this case, the stirring device 100 stirs the molten glass G generated in the melting tank 40 and supplies the homogenized molten glass G to the clarification tank 41. Two stirring devices 100 may be installed between the melting tank 40 and the clarification tank 41 and between the clarification tank 41 and the molding apparatus 42.

(7) Example A thermal fluid analysis simulation was performed on the flow of the molten glass G passing through a space having the same configuration as the stirring device 100 shown in FIGS. 5 and 6. The flow was steady and solved using a single solver using the SIMPLE algorithm. In addition, this time, because it is an analysis of the flow field in the isothermal state, it did not solve the convective heat transfer and radiant heat transfer. Next, various parameters set at the time of analysis will be described. The same reference numerals are used for the same components as in the embodiment.
(A) Viscosity of molten glass: 90.88 Pa · s,
(B) Four patterns of flow rate d1: 0.5, 1.0 and 1.4 (t / day) of the molten glass G flowing out from the discharge port 111a,
(C) Flow rate d2: 18 (t / day) of molten glass G flowing out from the outlet 104a,
(D) The flow rate d3 of the molten glass G flowing in from the inlet 103a: d1 + d2 (t / day),
(E) Height position of the glass liquid level GL of the stirring vessel 101: 5 mm above the upper end of the inflow port 103a,
(F) Height position of the lower end of the stirrer 102: 30 mm above the bottom surface of the stirring vessel 101,
Under the above parameters, the flow field of the molten glass G in the stirring device 100 was analyzed for the following two types of models.
(Model 1) This is a configuration corresponding to the embodiment shown in FIG. The height position of the liquid surface GL in the stirring container 101 is the same as the height position of the liquid surface of the molten glass G in the buffer container 111.
(Model 2) This is a configuration corresponding to the comparative example shown in FIG. The height position of the glass liquid level GL in the stirring container 101 is 20 mm higher than the height position of the liquid level of the molten glass G in the buffer container 111.

In the analysis of the flow field of the molten glass G, the following four types of flow velocity distributions were compared for each of the above two types of models and the above three patterns of the flow rate d1.
(Distribution 1) Vertical flow velocity distribution at the position of the discharge port 111a,
(Distribution 2) Vertical flow velocity distribution at a position 75 mm radially inward from the discharge port 111a,
(Distribution 3) Vertical flow velocity distribution at a position 75 mm radially inward from the inlet 103a,
(Distribution 4) Flow velocity distribution in the radial direction of the glass liquid level GL,
Regarding distribution 1, in model 1, the closer to the glass liquid level GL, the larger the flow velocity. On the other hand, in the model 2, the flow velocity was small at the height position of the lower end and the height position of the upper end of the discharge port 111a, and the flow velocity showed the maximum value at the intermediate height position. However, the maximum value of the flow rate in the model 2 was about half of the maximum value of the flow rate in the model 1. In Model 1 and Model 2, the larger the flow rate d1, the greater the flow velocity. Therefore, it was confirmed that the model 1 can discharge the molten glass G more efficiently than the model 2.

  Regarding distribution 2, in model 1, the larger the distance from the glass liquid level GL, the smaller the flow velocity. On the other hand, in the model 2, in the range from the glass liquid level GL to about 40 mm, the flow velocity is constant regardless of the distance from the glass liquid level GL, and in the range away from the glass liquid level GL from about 40 mm, The greater the distance from the liquid level GL, the smaller the flow rate. Further, in the range from the glass liquid level GL to about 40 mm, the flow rate of the model 1 was larger than that of the model 2. In Model 1 and Model 2, the larger the flow rate d1, the greater the flow velocity. Therefore, it was confirmed that the model 1 can discharge the molten glass G near the glass liquid level GL more efficiently than the model 2.

  Regarding distribution 3, the same flow velocity distribution was confirmed in model 1 and model 2. In model 1 and model 2, the flow velocity showed the maximum value at the height position in the middle of the inflow port 103a in the vertical direction. In Model 1 and Model 2, the larger the flow rate d1, the greater the flow velocity.

  Regarding the distribution 4, in the model 1, the flow velocity at the position of the discharge port 111a is the largest in the radial direction, and the flow velocity decreases from the position of the discharge port 111a toward the inside in the radial direction. On the other hand, in the model 2, the flow velocity at the position of the discharge port 111a in the radial direction was almost zero. The position of the discharge port 111a in the radial direction is a position corresponding to the liquid surface corner portion 101a in FIG. Further, in model 2, the flow velocity increased from the position of the discharge port 111a toward the inside in the radial direction, and then decreased after showing the maximum value. The position where the flow velocity shows the maximum value is an intermediate position between the discharge port 111 a and the rotation shaft 105. In Model 1 and Model 2, the larger the flow rate d1, the greater the flow velocity. Therefore, in the model 2, it was confirmed that the liquid surface corner portion 101a where the flow of the molten glass G shown in FIG. 6 stays exists. Moreover, in the model 1, it was confirmed that the liquid surface corner | angular part 101a of FIG. 6 does not exist, and the flow velocity of the molten glass G near the discharge port 111a is large. Therefore, it was confirmed that the model 1 can discharge the molten glass G near the glass liquid level GL more efficiently than the model 2.

DESCRIPTION OF SYMBOLS 100 Stirring apparatus 101 Stirring container 102 Stirrer 105 Rotating shaft 106 Stirring blade 111 Buffer container 111a Discharge port 112 Discharge pipe 200 Glass manufacturing apparatus (glass substrate manufacturing apparatus)
G Molten glass GL Glass liquid surface (molten glass liquid surface)
L Center axis of rotation axis

JP 2010-1000046 A

Claims (5)

An agitation step of agitating a molten glass produced by melting a glass raw material with an agitation device including an agitation vessel and an agitator;
In the stirring step, a discharging step of discharging the glass foreign matter formed on the molten glass liquid surface in the stirring vessel and having a glass composition different from that of the molten glass from a discharge port provided on a side wall of the stirring vessel;
With
In the discharging step, the height of the molten glass liquid surface in the stirring vessel is such that the height position of the molten glass liquid surface in the stirring vessel is within the range from the lower end to the upper end of the discharge port. Position is adjusted,
A method for producing a glass substrate. In the discharging step, the flow rate of the molten glass flowing into the stirring vessel with respect to the flow rate of the molten glass discharged from the stirring vessel through the discharge port, and the stirring vessel being stirred in the stirring vessel By adjusting at least one flow rate of the molten glass flowing out, the height position of the molten glass liquid surface in the stirring vessel is adjusted,
The manufacturing method of the glass substrate of Claim 1. The stirring vessel has an inlet for the molten glass formed on the side wall at a height position in the vicinity of the molten glass liquid surface,
The discharge port is opposed to the inflow port in the stirring vessel.
The manufacturing method of the glass substrate of Claim 1 or 2. The stirring device further has a buffer container communicating with the stirring container through the discharge port,
The buffer container has a discharge pipe port for discharging the molten glass in the buffer container,
The internal space of the buffer container is narrowed from the discharge port toward the discharge pipe port.
The manufacturing method of the glass substrate of any one of Claim 1 to 3. Stirring the molten glass produced by melting the glass raw material, equipped with a stirring device having a stirring container and a stirrer,
The stirring vessel has a discharge port for discharging a glass foreign material formed on the molten glass liquid surface in the stirring vessel and having a glass composition different from that of the molten glass,
The outlet is provided on a side wall of the stirring vessel,
The stirring device has a height of the molten glass liquid level in the stirring vessel so that a height position of the molten glass liquid level in the stirring vessel is within a range from a lower end to an upper end of the discharge port. Adjust the position,
Glass substrate manufacturing equipment.

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