JP2017178724A - Manufacturing method for glass plate and melting tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress local heat stagnation occurring to a foundation part of a melting tank and also to suppress a downward flow at the periphery of a side wall of the melting tank which may cause stria undesirable for glass quality, in manufacturing a glass plate.SOLUTION: In manufacturing a glass plate, a first heat insulation suppression structure and a second heat insulation suppression structure are provided at a bottom part of a melting tank in which molten glass is made through electric heating, the first heat insulation suppression structure being larger in heat dissipation quantity than the second heat insulation suppression structure. The one first heat insulation suppression structure is provided at a position, within a range of 5% of a lengthwise center length of a floor wall from a lengthwise center position of the melting tank, of the floor wall in contact with the molten glass in the melting tank, and when the region of the floor wall is divided into a first floor wall region on the side of a lengthwise raw material feed opening and a second floor wall region on the side of an outflow opening based upon the position of the first heat insulation suppression structure, at least one second heat insulation suppression structure is provided in the first floor wall region and the second floor wall region, respectively.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for producing a glass plate and a melting tank.

  In recent years, in the field of flat panel displays (hereinafter referred to as FPDs) such as liquid crystal displays and plasma displays, quality requirements for glass substrates for FPDs have become increasingly severe with the progress of high definition image display. In particular, in order to suppress the thermal shrinkage of the glass substrate that occurs during display panel manufacture, which causes pixel pitch shift, the glass substrate tends to be formed at a higher temperature than before, and the molten glass tends to have a higher temperature.

In order to manufacture a glass plate that meets the quality requirements for thermal shrinkage by the downdraw method, for example, glass having a glass composition having a higher strain point than that of a conventional glass composition is used. That is, a glass having a high temperature viscosity is used. For example, a glass manufacturing system and method for reducing gaseous inclusions in high melting glass or high strain point glass such as those used as glass substrates for FPDs are known (Patent Document 1). . In this system and method, a batch material is heated in a melting vessel to form a molten glass containing a polyvalent oxide material at a melting temperature T _M , and then the molten glass is cooled to less than T _M in a refractory tube. Cooling to a temperature T _C , the molten glass is retained in the refractory tube for a predetermined residence time. Thereafter, heating the cooled glass melt until a clear temperature T _F ≧ T _M.

JP 2012-517398 A

  In general, a glass whose glass composition is adjusted so as to be a glass having a high temperature viscosity or a high strain point tends to have a high electrical resistivity at the time of molten glass. In the melting process in which the molten glass is energized and heated, for example, in the case of a molten glass having an electrical resistivity at 1550 ° C. of 160 Ω · cm or more, part of the current to be applied to the molten glass for heating the molten glass Is heated and flows to the refractory bricks that form the melting tank, so that the heat is accumulated in the refractory bricks of the laying part that forms the bottom of the melting tank and the temperature rises locally compared to its surroundings Cannot be ignored. Due to local heat, the strength of the refractory brick is reduced and easily deformed, and in some cases, the refractory brick may be melted.

  Furthermore, in the melting tank as described above, the molten glass descends around the side wall of the melting tank around the side wall of the melting tank or around the outlet of the molten glass provided in the lower part of the side wall of the melting tank due to heat radiation to the outside of the melting tank. It tends to make a flow. In particular, the downward flow of the molten glass generated around the outlet provided in the lower part of the side wall of the melting tank entrains a heterogeneous substrate containing unmelted raw material components floating on the surface (liquid surface) of the molten glass. May cause undesirable striae.

  From this situation, when the molten glass, which has a tendency to increase the electrical resistivity, is heated and energized in the melting tank, it suppresses the local heat build-up of the laying part of the melting tank, and the glass quality is striking. It is preferable to control the temperature distribution of the molten glass in the melting tank so as to suppress the downward flow around the side wall of the melting tank, which is the cause.

  The object of the present invention is to suppress the local heat accumulation generated in the laying part of the melting tank, and to suppress the downward flow around the side wall of the melting tank, which is a cause of unfavorable striations in the glass quality. It is in providing a manufacturing method and a dissolution tank.

One embodiment of the present invention is a method for manufacturing a glass plate. The manufacturing method is
A process of making molten glass by electric heating in a melting tank;
Forming a glass plate by forming the molten glass.
The bottom of the melting tank is provided with a first heat retention suppressing structure and a second heat retention suppressing structure,
The heat dissipation amount of the first heat retention suppression structure is larger than the heat dissipation amount of the second heat retention suppression structure.
When the direction from the raw material inlet to the outlet of the molten glass is the longitudinal direction of the melting tank,
The first heat retention suppressing structure is provided at a position within a range of 5% of the longitudinal center length of the floor wall from the longitudinal center position of the floor wall in contact with the molten glass of the melting tank,
The floor wall region is divided into a first floor wall region on the raw material input side in the longitudinal direction and a second floor wall region on the outlet side with respect to the position of the first heat retention suppressing structure. Then, at least one second heat retention suppressing structure is provided in each of the first floor wall region and the second floor wall region.

  Compared to the center position in the longitudinal direction in the first floor wall region, the molten glass in the first floor wall region is closer to the side wall of the melting tank on the raw material inlet side in the longitudinal direction. In the second floor wall region, the temperature is the highest and the second floor wall region is closer to the side wall of the melting tank on the outlet side in the longitudinal direction than the central position in the longitudinal direction. It is preferable that the first heat retention suppressing structure and the second heat retention suppressing structure are provided so that the temperature of the molten glass becomes maximum.

One of the second heat insulation suppressing structures positioned in the first floor wall region is a second heat insulation suppressing structure A, and one of the second heat insulation suppressing structures positioned in the second floor wall region is a second heat insulation suppressing structure. With structure B,
The position where the temperature of the molten glass is highest in the first floor wall region is between the position of the second heat retention suppressing structure A and the side wall of the melting tank on the raw material inlet side in the longitudinal direction. The position where the temperature of the molten glass is highest in the second floor wall region is, in the longitudinal direction, the position of the second heat retention suppressing structure B, and the side wall of the melting tank on the outlet side. It is preferable that the 1st heat retention suppression structure, the 2nd heat retention suppression structure A, and the 2nd heat retention suppression structure B are provided so that it may be located in between.

  It is preferable that the second heat retention suppressing structure is provided within a range of a length of one third of the center length along the longitudinal direction with the position of the first heat retention suppressing structure as a center.

Another embodiment of the present invention is a melting tank for producing molten glass. The bottom portion of the melting tank for storing the molten glass of the melting tank is provided with a first heat retention suppressing structure and a second heat retention suppressing structure,
The heat dissipation amount of the first heat retention suppressing structure is larger than the heat dissipation amount of the second heat retention suppressing structure.
When the direction from the raw material inlet to the outlet of the molten glass is the longitudinal direction of the melting tank,
One of the first heat retention suppressing structures is provided at a position within a range of 5% of the center length of the floor wall in the longitudinal direction from the center position of the floor wall in contact with the molten glass of the melting tank. ,
The floor wall region is divided into a first floor wall region on the raw material input side in the longitudinal direction and a second floor wall region on the outlet side with respect to the position of the first heat retention suppressing structure. Then, at least one second heat retention suppressing structure is provided in each of the first floor wall region and the second floor wall region.

  Compared to the center position in the longitudinal direction in the first floor wall region, the molten glass in the first floor wall region is closer to the side wall of the melting tank on the raw material inlet side in the longitudinal direction. In the second floor wall region, the temperature is the highest and the second floor wall region is closer to the side wall of the melting tank on the outlet side in the longitudinal direction than the central position in the longitudinal direction. It is preferable that the first heat retention suppressing structure and the second heat retention suppressing structure are provided so that the temperature of the molten glass becomes maximum.

One of the second heat insulation suppressing structures positioned in the first floor wall region is a second heat insulation suppressing structure A, and one of the second heat insulation suppressing structures positioned in the second floor wall region is a second heat insulation suppressing structure. With structure B,
The position where the temperature of the molten glass is highest in the first floor wall region is between the position of the second heat retention suppressing structure A and the side wall of the melting tank on the raw material inlet side in the longitudinal direction. The position where the temperature of the molten glass is highest in the second floor wall region is, in the longitudinal direction, the position of the second heat retention suppressing structure B, and the side wall of the melting tank on the outlet side. It is preferable that the 1st heat retention suppression structure, the 2nd heat retention suppression structure A, and the 2nd heat retention suppression structure B are provided so that it may be located in between.

  According to the glass plate manufacturing method and the melting tank of the present invention, even when the molten glass that tends to increase the electrical resistivity is energized and heated in the melting tank, the local heat generated in the laying part of the melting tank is prevented. It is possible to control the temperature distribution of the molten glass in the melting tank so as to suppress the downward flow around the side wall of the melting tank, which is a cause of generation of striae that is unfavorable to the glass quality.

It is a conceptual diagram explaining arrangement | positioning of the 1st heat retention suppression structure and the 2nd heat retention suppression structure in the floor wall of the melting tank which concerns on this embodiment. It is a figure which shows an example of the process of the manufacturing method of the glass plate of this embodiment. It is a figure which shows typically an example of the glass plate manufacturing apparatus which performs the melting process-cutting process in this embodiment. It is a perspective view explaining the outline of the structure of the melting tank main body of the melting tank of this embodiment, and its periphery. It is a figure which simplifies and demonstrates the cross section of the melting tank of this embodiment. It is sectional drawing along the longitudinal direction of the melting tank main body in the melting tank of this embodiment. It is a figure which shows the melting tank model used for the simulation calculation of the melting tank of this embodiment. It is a figure explaining the temperature distribution of the molten glass which is the result of the simulation calculation of the heat conduction of this embodiment.

Hereinafter, the manufacturing method of the glass plate of this embodiment is demonstrated.
(Overview of this embodiment)
Drawing 1 is a key map explaining arrangement of the 1st heat retention suppression structure 12 and the 2nd heat retention suppression structure 14 which are mentioned below in floor wall 10 of a melting tank concerning this embodiment. The floor wall 10 has an end on the raw material inlet side (portion where the floor wall 10 contacts the side wall) 16 and an end on the outlet side of molten glass (portion where the floor wall 10 contacts the side wall) 18. The longitudinal direction of the floor 10 of the melting tank is the X direction in the figure from the end 16 toward the end 18.
In this embodiment, the 1st heat retention suppression structure 12 and the 2nd heat retention suppression structure 14 (The heat dissipation amount of a 1st heat retention suppression structure> The heat dissipation amount of a 2nd heat retention suppression structure) are provided in the bottom part containing the floor wall 10 of a melting tank. Provided. The first heat retention suppressing structure 12 is formed in the longitudinal direction of the floor wall 10 from the center position C in the longitudinal direction of the floor wall 10 of the melting tank (X direction from the end 16 on the raw material inlet side to the end 18 on the outlet side of the molten glass). One is provided at a position within a range of 5% of the central length L in the direction. Furthermore, the first floor wall region 20 (the region on the side of the raw material inlet in the longitudinal direction of the melting tank with reference to the position of the first heat retention suppressing structure) and the second floor wall region 22 (the position of the first heat retention suppressing structure) At least one second heat retention suppressing structure 14 is provided in each of the melting tanks on the outflow side in the longitudinal direction with respect to the reference.

Here, the heat retention suppressing structure includes at least one of a drain hole of a molten glass provided at the bottom of the melting tank, a hole for installing a temperature sensor, and a gas introduction hole for foam formation. The thermal insulation suppressing structure is configured such that when a laying portion of a plurality of refractory bricks provided below the floor wall is provided, the thermal conductivity of the refractory brick of the laying portion is partially set in at least one of the refractory bricks of the laying portion. A structure that is raised relative to the surroundings.
These thermal insulation control structures, for example, use the simulation model of the melting tank as a reference to perform simulation calculation to make molten glass, predict the temperature distribution at the bottom of the melting tank, and confirm from the temperature distribution obtained by the prediction calculation be able to. Since there is no refractory brick with high heat insulation in the hole space of the drain hole, the temperature sensor installation hole, and the bubble forming gas introduction hole, these holes are likely to radiate heat along the hole space. For this reason, it can be said that the structure of the area | region provided with these holes is a heat retention suppression structure.
The amount of heat radiation in the heat retention suppression structure is calculated by, for example, performing the above simulation calculation using a simulation model with a heat retention suppression structure and a simulation model without a heat retention suppression structure, and calculating the difference in temperature of the molten glass at the position of the heat retention suppression structure. Can be determined by size. For example, a large hole has a larger hole space than a small hole, and therefore a large amount of heat is released.

  Thus, by providing the 1st heat retention structure 12 and the 2nd heat retention structure 14 in the bottom part of a melting tank, the local heat | fever mass produced in the laying part of a melting tank is suppressed, and it is unpreferable for glass quality. The downward flow around the side wall of the melting tank, which causes striae, can be suppressed. Details of this embodiment will be described below.

(Overall overview of glass plate manufacturing method)
Drawing 2 is a figure showing an example of a process of a manufacturing method of a glass plate of this embodiment.
The glass plate manufacturing method includes a melting step (ST1), a refining step (ST2), a homogenizing step (ST3), a supplying step (ST4), a forming step (ST5), and a slow cooling step (ST6). And a cutting step (ST7). In addition, a plurality of glass plates that have a grinding process, a polishing process, a cleaning process, an inspection process, a packing process, and the like and are stacked in the packing process are conveyed to a supplier.

The melting step (ST1) is performed in a melting tank. In the melting tank, a glass raw material is poured into the liquid surface of the molten glass stored in the melting tank and heated to make molten glass. Furthermore, molten glass is poured toward the downstream process from the outlet provided in one of the inner side walls of the melting tank.
Heating of the molten glass in the melting tank is performed by supplying electricity to the molten glass itself, generating heat, and heating the glass, and supplementing a flame with a burner to melt the glass raw material. Specifically, the charged glass raw material is heated by thermal radiation heat transfer from the wall surface of the gas phase space of the melting tank or the flame of the burner, and is pyrolyzed and melted. The molten glass produced in this way is heated to a higher temperature. A clarifier is added to the glass raw material. SnO ₂ , As ₂ O ₃ , Sb ₂ O _{3 and the} like are known as fining agents, but are not particularly limited. However, it is preferable to use SnO ₂ (tin oxide) as a clarifying agent from the viewpoint of reducing environmental burden. In the melting tank, the glass raw material is completely melted so as not to cause striae, and a molten glass having a predetermined viscosity is produced by energization heating so that the subsequent process is appropriately performed.

The clarification step (ST2) is performed at least in the clarification tank. In the clarification process, when the molten glass in the clarification tank is heated, the bubbles containing O ₂ , CO ₂ or SO ₂ contained in the molten glass absorb O ₂ generated by the reductive reaction of the clarifier. As a result, the bubbles rise to the liquid surface of the molten glass and are discharged. Furthermore, in the clarification step, the reducing substance obtained by the reduction reaction of the clarifier undergoes an oxidation reaction by lowering the temperature of the molten glass. Thereby, gas components such as O ₂ in the foam remaining in the molten glass are reabsorbed in the molten glass, and the foam disappears. The oxidation reaction and reduction reaction by the fining agent are performed by controlling the temperature of the molten glass. In the clarification step, a clarification method using tin oxide as a clarifier can be used.

In the homogenization step (ST3), the glass components are homogenized by stirring the molten glass in the stirring tank supplied through the pipe extending from the clarification tank using a stirrer. Thereby, the composition unevenness of the glass which is a cause of striae or the like can be reduced.
In the supply step (ST4), the molten glass is supplied to the molding apparatus through a pipe extending from the stirring tank.

In the molding apparatus, a molding step (ST5) and a slow cooling step (ST6) are performed.
In the forming step (ST5), the molten glass is formed into a band-shaped glass plate to make a flow of the glass plate. For forming, an overflow downdraw method is used.
In the slow cooling step (ST6), the molded glass sheet is cooled to have a desired thickness, so that internal distortion does not occur and warpage does not occur.
In the cutting step (ST7), a single glass plate is obtained by cutting the strip-shaped glass plate supplied from the molding device into a predetermined length in the cutting device. The cut glass plate is further cut into a predetermined size to produce a target size glass plate. After this, the end face of the glass plate is ground and polished, the glass plate is cleaned, and further, the presence of abnormal defects such as bubbles and striae is inspected. Will be packed as.

Drawing 3 is a figure showing typically an example of the glass plate manufacturing device which performs the melting process (ST1)-cutting process (ST7) in this embodiment. As shown in FIG. 3, the apparatus mainly includes a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300. The melting apparatus 100 includes a melting tank 101, a clarification tank 102, a stirring tank 103, and glass supply pipes 104, 105, and 106.
In the melting apparatus 101 shown in FIG. 3, the glass raw material is charged using a bucket 101d, and the molten glass MG is heated so that the molten glass MG obtained by melting the glass raw material has a predetermined viscosity. In the clarification tank 102, the temperature of the molten glass MG is adjusted, and the clarification of the molten glass MG is performed using the oxidation-reduction reaction of the clarifier. Further, in the stirring vessel 103, the molten glass MG is stirred and homogenized by the stirrer 103a. In the forming apparatus 200, the sheet glass SG is formed from the molten glass MG by the overflow down draw method using the formed body 210. In the present embodiment, the bucket 101d is used as a glass raw material charging unit, but is not limited thereto. For example, a screw feeder can be used.

In such a glass plate manufacturing method and glass plate manufacturing apparatus, in order to produce a glass plate having a small thermal shrinkage, when glass having a glass composition having a high temperature viscosity is used, the melting tank 101 is not a glass having a high temperature viscosity. Compared to the above, it is necessary to heat by energizing by passing a large amount of current. However, in a glass having a high temperature viscosity, the electrical resistivity in the molten state tends to increase, and the electrical resistivity of the molten glass is equivalent to the electrical resistivity of the refractory brick used for the side wall and floor wall of the melting tank 101. . For this reason, when an electric current is made to flow through the electrode pair provided on the side wall of the melting tank 101 and an electric current is made to flow through the molten glass, a part of the current that should originally flow through the molten glass is applied to the side wall and the floor wall of the melting tank 101. The stream, side walls and floor walls are heated. In particular, in the laying portion of the layer structure in which a plurality of layers of refractory bricks having excellent heat insulating properties are spread below the floor wall of the melting tank 101, heat does not escape due to the heat insulating properties, and heat is partially accumulated, resulting in a high temperature. A heat turbulence is generated. Such a hot weight lowers the mechanical strength of the refractory bricks on the floor wall and the laying part, resulting in thermal creep, and part of the refractory bricks may be melted and the molten glass to be stored may flow out. There is also.
For this reason, in this embodiment, by appropriately determining the arrangement positions of the first heat retaining structure 12 and the second heat retaining structure 14 provided at the bottom of the melting tank 101, local heat buildup generated in the laying part of the melting tank is prevented. It is possible to suppress the downward flow around the side wall of the melting tank, which is suppressed and causes the occurrence of striae that are not preferable for the glass quality. Hereinafter, the configuration of the melting tank will be described in more detail.

(Melting tank)
FIG. 4 is a perspective view for explaining the outline of the melting tank main body of the melting tank 101 and its peripheral structure, and FIG. 5 is a diagram for explaining the simplified section of the melting tank 101. The cross section shown in FIG. 5 is a cross section at the position in the longitudinal direction where the electrode 114 shown in FIG. 4 is provided. FIG. 6 is a cross-sectional view along the longitudinal direction of the melting tank body.

  In the present embodiment, the melting tank 101 mainly has a melting tank main body 110, a burner 112, an electrode pair 114, and a compression portion 118.

The melting tank main body 110 has a gas phase space in the upper part and stores molten glass in the lower part.
Three burners 112 are provided on both walls facing each other at different positions in the longitudinal direction on the gas phase space partition wall 116 surrounding the gas phase space of the melting tank main body 110. At this time, the burners 112 are not provided at positions facing each other, but are provided alternately. Note that three burners 112 may be provided on one wall, not on both walls facing each other. In FIG. 4, only the burner 112 provided on the inner wall of the melting tank main body 110 is shown. The burner 112 emits a flame by burning a combustion gas in which fuel and oxygen are mixed. In FIG. 5, two burners 112 are shown to be provided at opposing positions on the opposing walls, but the two burners 112 shown in FIG. 5 are provided at different positions in the direction perpendicular to the paper surface of FIG. ing.

  Three pairs of the electrode pairs 114 are provided at three different positions in the longitudinal direction of the side wall portion of the melting tank main body 110 so as to energize and heat the molten glass so as to face each other with the molten glass interposed therebetween. In FIG. 4, only the electrode provided in the side wall part of the near side of the melting tank main body 110 is shown. For the electrode pair 114, for example, a conductive material having heat resistance such as tin oxide or molybdenum is used. The electrode pair 114 is connected to the control unit 120 and receives a controlled current supply from the control unit 120.

  The gas phase space partition wall 116 is a part of the melting tank main body 110 and is a wall provided above the storage portion of the molten glass. A burner 112 is provided on this wall. Further, the gas-phase space partition wall 116 is provided with a raw material inlet 101f that can be freely opened and closed, and a bucket 101d (see FIG. 2) in which glass raw materials are loaded enters and exits through the raw material inlet 101f. Glass material is thrown into the liquid level of the molten glass stored in the melting tank main body 110 by the bucket 101d. An outflow port 104a is provided in the vicinity of the floor wall of the side wall facing the raw material charging port 101f of the melting tank main body 110. The melting tank 101 flows the molten glass from the outlet 104a toward the subsequent process.

The compression portion 118 is a ceiling wall that closes the gas phase space of the melting tank 101.
As the melting tank main body 110, the gas phase space partition wall 116, and the compression portion 118, those having heat resistance to the temperature of the molten glass are used.

  Below the melting tank main body 110, a laying portion 124 having a laminated structure made of refractory bricks is provided. The laying part 124 has a heat insulating layer having a four-layer structure. The bottom 126 of the melting tank 101 includes a floor wall 10 corresponding to the bottom of the tank of the melting tank main body 110 and a laying part 124, and the floor wall 10 and the laying part 124 constitute a laminated structure. For the floor wall 10 of the melting tank main body 110 in contact with the molten glass, for example, a dense refractory brick having a lower porosity than that of the refractory brick used for the laying portion 124 is used, and the heat conduction of the refractory brick used for the floor wall 110a. The rate is higher than that of the refractory brick used for the laying portion 124.

  As shown in FIG. 6, a temperature sensor installation hole 126 a and a drain hole 126 b are provided in the bottom 126 of the melting tank main body 110.

The temperature sensor installation hole 126a is a hole provided in the floor wall of the melting tank main body 110 in order to install a temperature sensor that measures the temperature of the molten glass MG located on the floor wall 10, for example, a thermocouple. Therefore, the temperature sensor installation hole 126a is suppressed from keeping the hole and the periphery of the hole so that the molten glass MG has a high viscosity and the molten glass MG does not leak from the hole. The temperature sensor installation hole 126a extends to the refractory bricks of the floor wall 10 and the laying portion 124 and is blocked in the middle. The temperature sensor installation hole 126a may be a hole penetrating through the refractory bricks of the floor wall 10 and the laying portion 124, or may be a hole blocked in the middle.
The drain hole 126b is a discharge port through which the refractory bricks of the floor wall 10 and the laying portion 124 flow out to the outside of the glass plate manufacturing apparatus without flowing the molten glass MG in a subsequent process. The molten glass MG stored in the melting tank main body 110 may be completely extracted from the melting tank main body 110 in order to repair the melting tank 101 or the melting apparatus 100. In this case, the molten glass MG is discharged from the drain hole 126b.

Since the hole diameter of the drain hole 126b is larger than the hole diameter of the temperature sensor installation hole 126a and penetrates the bottom 126, the heat radiation amount of the layer structure surrounding the drain hole 126b is the layer structure surrounding the temperature sensor installation hole 126a. Larger compared to the amount of heat released. Therefore, the layer structure surrounding the drain hole 126b is a first heat retention suppressing structure, and the layer structure surrounding the temperature sensor installation hole 126a is a second heat retention suppressing structure.
Here, the layer structure (first heat retention suppressing structure) surrounding the drain hole 126b is 1 at a position within a range of 5% of the center length L in the longitudinal direction of the floor wall 10 from the center position C in the longitudinal direction of the floor wall 10. One is provided. The position of the layer structure (first heat retention suppressing structure) surrounding the drain hole 126b is the center position of the drain hole 126b. Furthermore, the area of the floor wall 10 with respect to the position of the layer structure surrounding the drain hole 126b is defined as the first floor wall area 20 on the side of the raw material inlet 101f in the longitudinal direction (X direction) and the first floor wall area 20 on the outlet 104a side. When divided into two floor wall regions 22, each of the first floor wall region 20 and the second floor wall region 22 is provided with a layer structure (second heat retention suppressing structure) surrounding at least one temperature sensor installation hole 126a. It has been. The position in the width direction of the floor wall 10 perpendicular to the X direction of the layer structure (first heat retention suppressing structure) surrounding the drain hole 126b and the layer structure (second heat retention suppressing structure) surrounding the temperature sensor installation hole 126a is particularly limited. Not.

  In this embodiment, the layer structure surrounding the temperature sensor installation hole 126a and the layer structure surrounding the drain hole 126b are exemplified as the heat retention suppressing structure, but other structures may be included, for example, a bubble forming gas introduction hole It may be a layered structure surrounding. In the melting tank main body 110, in order to grow bubbles in the molten glass MG and make it easy to clarify in a subsequent clarification step, bubbles may be introduced into the molten glass MG. In this case, a bubble forming gas introduction hole for introducing bubbles into the molten glass MG is provided in the floor wall 10 of the melting tank main body 110. The bubble forming gas introduction holes are also kept at a low temperature so as to prevent the molten glass MG from leaking out of the holes by increasing the viscosity of the molten glass MG. Moreover, the layer structure surrounding the hole extended from the lower part of the laying part 124 to the middle of the lamination | stacking of a firebrick can also be mentioned as an example of a heat retention suppression structure. By providing such a hole, the layer structure surrounding the hole has a large area in contact with the outside air, so that it is easy to radiate heat. For this reason, the heat insulation of the refractory brick around the hole is suppressed.

  In the present embodiment, in the first floor wall region 20, the first floor wall region 20 is closer to the side wall of the melting tank 101 on the side of the raw material charging port 101 f in the longitudinal direction than the center position C in the longitudinal direction. When the temperature of the molten glass is the highest and the longitudinal center position C of the second floor wall region 22 is compared with the side wall of the melting tank 101 on the outlet 104a side in the longitudinal direction, the melting tank in the longitudinal direction. The layer structure surrounding the drain hole 126b (first heat retention suppressing structure) and the layer structure surrounding the temperature sensor installation hole 126a so that the temperature of the molten glass in the second floor wall region 22 becomes the highest at a position close to the side wall 101. It is preferable that a (second heat retention suppressing structure) is provided. By providing the 1st floor wall area | region 20 and the 2nd floor wall area | region 22 as mentioned above, the maximum temperature in each area | region of a molten glass is located near the side wall of the raw material input port 101f side and the outflow port 104a side. Therefore, the downward flow in which the molten glass descends along the side wall can be suppressed. On the surface (liquid level) of the molten glass in the melting tank 101, a heterogeneous substrate of unmelted glass components out of the charged glass raw material floats. In particular, in the vicinity of the side wall on the side of the raw material inlet 101f and the outlet 104a, a lot of heterogeneous substrate of unmelted glass component is floating, so if there is a large downward flow of molten glass, the unmelted glass component The heterogeneous substrate descends along the side wall, flows out from the outflow port 104a, and easily flows into the clarification step ST2. Such a heterogeneous substrate is not preferable because it causes striae. For this reason, the maximum temperature in the 1st floor wall area | region 20 and the 2nd groove bottom area | region 22 of molten glass is near the side wall of the raw material input port 101f side and the outflow port 104a side so that a downward flow of molten glass does not arise easily. It is preferable that a layer structure (first heat retention suppression structure) surrounding the drain hole 126b and a layer structure (second heat retention suppression structure) surrounding the temperature sensor installation hole 126a are provided. That is, the temperature distribution of the molten glass in the melting tank 101 can be controlled so as to suppress the downward flow around the side wall of the melting tank that causes striae in the glass quality.

The position in the longitudinal direction where the temperature of the molten glass is highest in the first floor wall region 20 is a layer structure (second heat retention suppressing structure) surrounding the temperature sensor installation hole 126a provided in the first floor wall region 20 in the longitudinal direction. It is located between the position A) (the center position of the temperature sensor installation hole 126a) and the side wall of the melting tank 101 on the raw material charging port 101f side, and the temperature of the molten glass reaches the maximum in the second floor wall region 22. The position in the longitudinal direction is the position of the layer structure (second heat retention suppressing structure B) surrounding the temperature sensor installation hole 126a provided in the second floor wall region 22 in the longitudinal direction (center position of the temperature sensor installation hole 126a). And a layer structure surrounding the drain hole 126b (first heat retention suppressing structure) and a layer structure surrounding the temperature sensor installation hole 126a so as to be located between the side wall of the melting tank 101 on the outlet 104a side (second Rise restraining structure A, it is preferred that B) is provided. More specifically, the layer structure (second heat retention suppression structure A and second heat retention suppression structure B) surrounding the temperature sensor installation hole 126a is a layer structure (first heat retention suppression structure) surrounding the drain hole 126b, respectively. The center is preferably provided within the range of one-third of the central length L along the longitudinal direction of the melting tank 101 with the position at the center. Thereby, as above-mentioned, the downward flow which a molten glass descend | falls along a side wall can be suppressed, and it suppresses that the heterogeneous base material of an unmelted glass component rides on a downward flow and flows out out of the outflow port 104a. Can do. That is, the temperature distribution of the molten glass in the melting tank 101 can be controlled so as to suppress the downward flow around the side wall of the melting tank, which causes the occurrence of striae that are undesirable for the glass quality.
When the layer structure (second heat retention suppressing structure A, B) surrounding the temperature sensor installation hole 126a is brought close to the layer structure (first heat retention suppressing structure) surrounding the drain hole 126b, the downward flow of the molten glass descends along the side wall. It is not possible to suppress the heat and the heat of the bottom 126 cannot be dispersed and radiated, so that the heat trap cannot be suppressed. For this reason, the position in the longitudinal direction of the layer structure (second heat retention suppression structure A, B) surrounding the temperature sensor installation hole 126a is kept away from the center of the layer structure (first heat retention suppression structure) surrounding the drain hole 126b. It is preferable to provide them.

FIG. 7 is a diagram showing a melting tank model 101M used for simulation calculation of heat conduction in the melting tank (the temperature sensor installation hole 126a and the drain hole 126b are not shown). FIG. 8 is a diagram illustrating an example of a temperature distribution of the molten glass as a result of the simulation calculation of heat conduction.
FIG. 7 shows a view of the melting tank model 101M cut along a vertical plane along the longitudinal direction, passing through the center position in the width direction orthogonal to the longitudinal direction. The melting tank model 101M includes a melting tank main body model 110M and a laying part model 124M. The laying part model 124M is configured by a four-layer brick layer model.
In the model shown in FIG. 7, the layer structure (first heat retention suppressing structure) surrounding the drain hole 126 b is within a range of 5% of the center length L in the longitudinal direction of the floor wall 10 from the center position C in the longitudinal direction of the floor wall 10. The layer structure (second heat retention suppressing structure A and second heat retention suppressing structure B) surrounding the drain hole 126b is provided in the layer structure (one first heat retention suppressing structure B). ) Is employed within the range of one-third of the central length L along the longitudinal direction of the melting tank 101.

As the thermal conductivity of the melting tank main body model 110M and the laying part model 124M, the values of the thermal conductivity of the melting tank main body 110 and the laying part 124 of the actual actual melting tank 101 were used. The thermal conductivity of the part corresponding to the wall of the melting tank main body model 110M is (3.18799 × 10 ⁻¹² T ⁴ −1.8239798 × 10 ⁻⁸ T ³ + 4.0884149 × 10 ⁻⁵ T ² −0.0384005T + 13.677581) [W / ( m · K)] (T: temperature [K]), and the thermal conductivity of the four-layer laying part model 124M is, in order from the upper layer,
・ (3.18799 × 10 ⁻¹² T ⁴ −1.8239798 × 10 ⁻⁸ T ³ + 4.0884149 × 10 ⁻⁵ T ² −0.0384005T + 13.677581) [W / (m · K)] (T: temperature [K]),
3.605 [W / (m · K)],
-2.093 [W / (mK)],
・ (3.05869 × 10 ^-4 T-0.159519) [W / (m ・ K)] (T: Temperature [K]),
It was.

  As the heat conduction simulation calculation, the fluid element simulating the molten glass MG is filled in the melting tank main body model 110M, and the temperature of the radiant heat transfer boundary condition (emissivity 0.7, reference temperature 1580 ° C.) on the liquid surface of the fluid element. Boundary conditions are applied, and heating is applied to the fluid elements under conditions of 114 amperes, 125 amperes, and 138 amperes in order from the side of the raw material inlet 101f for three electrodes (flow rate 6 tons / day, inflow temperature 1500 ° C.) The simulation of heating was performed and the temperature distribution due to the heat conduction of the molten glass MG and the melting tank 101 was calculated.

  In the temperature distribution of the molten glass, which is the simulation result shown in FIG. 8, the layer structure model (the model of the second heat retention suppressing structure A) surrounding the side wall of the melting tank main body model 110M on the raw material inlet 101f side and the temperature sensor installation hole model 126Ma. ), The temperature of the molten glass in the first floor wall region 20 becomes the maximum temperature Ta, and the layer structure model (the first model) surrounding the side wall of the melting tank main body model 110M on the outlet model 104Ma side and the hole model 126Ma for installing the temperature sensor 2) The temperature of the molten glass in the second floor wall region 22 is the maximum temperature Tb.

  Thus, in the melting tank 101 of this embodiment, the layer structure (first heat retention suppressing structure) surrounding the drain hole 126b in the bottom portion 126 and the layer structure (second heat retention suppressing structures A and B) surrounding the temperature sensor installation hole 126a. ) Is distributed in the above-described range, the heat dissipation at the bottom 126 is dispersed, so that local heat buildup at the laying portion 124 is suppressed and the periphery of the side wall of the melting tank 101 that causes striae Can be suppressed.

  As mentioned above, although the manufacturing method and melting tank of the glass plate of this invention were demonstrated in detail, this invention is not limited to the said embodiment, Even if it is variously improved and changed in the range which does not deviate from the main point of this invention. Of course it is good.

DESCRIPTION OF SYMBOLS 10 Floor wall 12 1st heat retention suppression structure 14 2nd heat retention suppression structure 16, 18 End 20 1st floor wall area 22 2nd floor wall area 100 Melting apparatus 101 Melting tank 101d Bucket 101f Raw material input port 102 Clarification tank 103 Stirring tank 103a Stirrers 104, 105, 106 Glass supply pipe 104a Outflow port 110 Melting tank body 112 Burner 114 Electrode pair 116 Gas phase space partition wall 118 Close part 120 Control unit 124 Laying part 126 Bottom part 126a Temperature sensor installation hole 126b Drain hole 200 Molding device 210 Molded body 300 Cutting device 101M Melting tank model 104Ma Outlet model 110M Melting tank main body model 124M Laying part model 126M Bottom part model 126Ma Temperature sensor installation hole model 126Mb Drain hole model

Claims (7)

A process of making molten glass by electric heating in a melting tank;
Forming the glass melt by forming the molten glass,
The bottom of the melting tank is provided with a first heat retention suppressing structure and a second heat retention suppressing structure,
The heat dissipation amount of the first heat retention suppression structure is larger than the heat dissipation amount of the second heat retention suppression structure,
When the direction from the raw material inlet to the outlet of the molten glass is the longitudinal direction of the melting tank,
The first heat retention suppressing structure is provided at a position within a range of 5% of the longitudinal center length of the floor wall from the longitudinal center position of the floor wall in contact with the molten glass of the melting tank,
The floor wall region is divided into a first floor wall region on the raw material input side in the longitudinal direction and a second floor wall region on the outlet side with respect to the position of the first heat retention suppressing structure. Then, at least one second heat retention suppressing structure is provided in each of the first floor wall region and the second floor wall region.   Compared to the center position in the longitudinal direction in the first floor wall region, the molten glass in the first floor wall region is closer to the side wall of the melting tank on the raw material inlet side in the longitudinal direction. In the second floor wall region, the temperature is the highest and the second floor wall region is closer to the side wall of the melting tank on the outlet side in the longitudinal direction than the central position in the longitudinal direction. The manufacturing method of the glass plate of Claim 1 with which a said 1st heat retention suppression structure and a said 2nd heat retention suppression structure are provided so that the temperature of the said molten glass may become the maximum. One of the second heat insulation suppressing structures positioned in the first floor wall region is a second heat insulation suppressing structure A, and one of the second heat insulation suppressing structures positioned in the second floor wall region is a second heat insulation suppressing structure. With structure B,
The position where the temperature of the molten glass is highest in the first floor wall region is between the position of the second heat retention suppressing structure A and the side wall of the melting tank on the raw material inlet side in the longitudinal direction. The position where the temperature of the molten glass is highest in the second floor wall region is, in the longitudinal direction, the position of the second heat retention suppressing structure B, and the side wall of the melting tank on the outlet side. The manufacturing method of the glass plate of Claim 1 or 2 with which the said 1st heat retention suppression structure, the said 2nd heat retention suppression structure A, and the said 2nd heat retention suppression structure B are provided so that it may be located in between.   The said 2nd heat retention suppression structure is provided in the range of the length of 1/3 of the said center length along the said longitudinal direction centering on the position of the said 1st heat retention suppression structure. 4. The method for producing a glass plate according to any one of 3 above. A melting tank for making molten glass,
The bottom portion of the melting tank for storing the molten glass is provided with a first heat retention suppressing structure and a second heat retention suppressing structure,
The heat dissipation amount of the first heat retention suppression structure is greater than the heat dissipation amount of the second heat retention suppression structure,
When the direction from the raw material inlet to the outlet of the molten glass is the longitudinal direction of the melting tank,
One of the first heat retention suppressing structures is provided at a position within a range of 5% of the center length of the floor wall in the longitudinal direction from the center position of the floor wall in contact with the molten glass of the melting tank. ,
The floor wall region is divided into a first floor wall region on the raw material input side in the longitudinal direction and a second floor wall region on the outlet side with respect to the position of the first heat retention suppressing structure. Then, at least one second heat retention suppressing structure is provided in each of the first floor wall region and the second floor wall region.   Compared to the center position in the longitudinal direction in the first floor wall region, the molten glass in the first floor wall region is closer to the side wall of the melting tank on the raw material inlet side in the longitudinal direction. In the second floor wall region, the temperature is the highest and the second floor wall region is closer to the side wall of the melting tank on the outlet side in the longitudinal direction than the central position in the longitudinal direction. The melting tank according to claim 5, wherein the first heat retention suppressing structure and the second heat retention suppressing structure are provided so that the temperature of the molten glass becomes maximum. One of the second heat insulation suppressing structures positioned in the first floor wall region is a second heat insulation suppressing structure A, and one of the second heat insulation suppressing structures positioned in the second floor wall region is a second heat insulation suppressing structure. With structure B,
The position where the temperature of the molten glass is highest in the first floor wall region is between the position of the second heat retention suppressing structure A and the side wall of the melting tank on the raw material inlet side in the longitudinal direction. The position where the temperature of the molten glass is highest in the second floor wall region is, in the longitudinal direction, the position of the second heat retention suppressing structure B, and the side wall of the melting tank on the outlet side. The melting tank according to claim 5 or 6, wherein the first heat retention suppressing structure, the second heat retention suppressing structure A, and the second heat retention suppressing structure B are provided so as to be positioned between the two.

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