JP2016033099A - Method for manufacturing glass plate, and agitator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method, etc., for manufacturing a glass plate, capable of enhancing the agitation efficiency of a molten glass by obtaining a path in which the molten glass flows to sufficiently homogenize the molten glass.SOLUTION: The method for manufacturing a glass plate comprises: a melting step of melting a glass raw material to form a molten glass; an agitation step of rotating an agitator having a rotary shaft forming a center of rotation and an agitation wing provided in the rotary shaft to agitate the molten glass in an agitation tank sectioned by a bottom surface, a side surface extended upward from the bottom surface and a top surface crossing the side surface using at least two agitation devices including the agitation tank and the agitator; and a molding step of molding the agitated molten glass to form a glass plate. In the agitation step, the rotary shaft is provided so that a shear stress applied to the molten glass by the side surface and the agitation wing is varied in the circumferential direction of the side surface. The agitators of the two agitation devices rotate in a forward direction and a reverse direction, respectively.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for producing a glass plate and a stirring device.

  When manufacturing a glass plate, if the molten glass is not sufficiently homogenized, striae may occur in the obtained glass substrate. Therefore, stirring molten glass using a stirrer has been conventionally performed. The stirrer generally includes a stirrer to which molten glass is supplied and a stirrer disposed in the stirrer, and the stirrer has a rotating shaft and a stirring blade attached to the rotating shaft. Yes. In a conventional stirring apparatus, a plurality of stirring blades are provided along the axial direction of a rotating shaft in order to improve stirring performance (Patent Document 1). According to this stirring device, the molten glass is stirred over a wider region in the axial direction.

JP 2011-88816 A

  As the demand for improving the quality of glass substrates increases, the degree of homogenization of molten glass is also required to be increased. However, in the conventional stirring apparatus, since the route through which the molten glass flows is short, the effect of homogenizing the molten glass may not be sufficient.

  Then, this invention provides the manufacturing method of a glass plate which can raise the stirring efficiency of molten glass, and fully homogenize molten glass, and a stirring apparatus by ensuring the path | route through which molten glass flows. For the purpose.

One aspect of the present invention is a method for producing a glass plate,
A melting step for melting glass raw material to produce molten glass, a bottom surface, a side surface extending upward from the bottom surface, a stirring tank defined by a top surface intersecting with the side surface, a rotation shaft serving as a rotation center, and a rotation shaft A stirring step of stirring the molten glass in the stirring tank by rotating the stirrer using at least two stirring devices provided with a stirring blade having a stirring blade;
Forming a glass plate by forming the stirred molten glass, and
In the stirring step, the rotating shaft is provided such that a shear stress applied to the molten glass by the side surface and the stirring blade changes in a circumferential direction of the side surface, and each stirrer provided in the two stirring devices includes: Rotate in the forward and reverse directions,
It is characterized by that.

The side surface of the agitation tank is formed with a port through which the molten glass flows into or out of the agitation tank,
In the stirring step, the distance between the end of the stirring blade farthest away from the rotating shaft in the radial direction of the rotating shaft and the side surface of the rotating shaft is minimum at a portion of the side surface corresponding to the mouth. It is preferable that it is provided.

Another aspect of the present invention includes a stirring vessel that is supplied with molten glass and defined by a bottom surface, a side surface that extends upward from the bottom surface, and a top surface that intersects the side surface, a rotation shaft that serves as a rotation center, and the rotation shaft A stirrer provided with a stirrer having a stirring blade,
The rotating shaft is provided such that shear stress applied to the molten glass by the side surface and the stirring blade changes in the circumferential direction of the side surface, and at least two of the stirring devices are connected, and the two stirring devices are provided. Each stirrer rotates in the forward and reverse directions,
It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the stirring efficiency of molten glass can be improved and homogenization of molten glass can fully be performed.

It is a figure which shows the flow of the manufacturing method of the glass plate of this embodiment. It is a schematic diagram which shows the glass plate manufacturing apparatus used with the manufacturing method of FIG. It is a side view of one stirring apparatus. It is the schematic side view which connected the stirring apparatus of FIG. It is the projection which projected the stirrer with which the 1st stirring apparatus of FIG. 3 is provided on the bottom face of the stirring tank. It is the projection which projected the stirrer with which the 2nd stirring apparatus of FIG. 3 is provided on the bottom face of the stirring tank. It is the figure which showed a mode that the heterogeneous molten glass flows from an upstream conduit to a conduit and from a conduit to a downstream conduit. It is the figure which showed the stirring position in the conduit | pipe which connects two stirring apparatuses. It is the figure which showed an example in which molten glass flows from an upstream conduit to a downstream conduit via a first stirring device and a second stirring device. It is a perspective view of the stirring blade of the stirring apparatus of FIG. It is a top view of the stirring blade of the stirring apparatus of FIG. It is a perspective view of the stirring blade of the stirring apparatus of FIG. It is a top view of the stirring blade of the stirring apparatus of FIG. It is a figure explaining the arrangement | positioning relationship of two stirring blades of the stirring apparatus of FIG. It is a figure showing arrangement | positioning of the bearing of the stirring blade of the stirring apparatus of FIG. It is a side view of the bearing of the stirring blade of the stirring apparatus of FIG. It is a top view of the bearing of the stirring blade of the stirring apparatus of FIG. It is a top view showing the state before the wedge of the stirring blade of the stirring apparatus of FIG. 3 is fitted to the rotating shaft. It is a top view showing the state after the wedge of the stirring blade of the stirring apparatus of FIG. 3 was fitted to the rotating shaft. It is a figure showing the flow of the molten glass in the stirring apparatus of FIG.

  Hereinafter, the manufacturing method and stirring apparatus of the glass plate which concern on this invention are demonstrated. FIG. 1 is a view showing a flow of a glass plate manufacturing method of the present embodiment.

(Glass plate manufacturing method)
The glass plate manufacturing method includes a melting step (ST1), a clarification step (ST2), a stirring step (ST3), a supplying step (ST4), a forming step (ST5), a slow cooling step (ST6), 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.

  FIG. 2 is a diagram schematically showing an apparatus 200 that performs the melting step (ST1) to the cutting step (ST7). The 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 sheet glass 44 is formed from the molten glass G by the down draw method.

In the melting step (ST1), the glass raw material supplied into the melting tank 40 is melted by heating with a flame and / or an electric heater (not shown) to obtain a molten glass G.
The clarification step (ST2) is performed in the clarification tank 41, and by heating the molten glass in the clarification tank 41, oxygen and SO ₂ bubbles contained in the molten glass grow by the oxidation-reduction reaction of the clarifier. Then, it floats on the liquid surface and is released, or the gas component in the bubbles is absorbed into the molten glass and the bubbles disappear.
In the stirring step (ST3), the molten glass supplied through the conduit 43b is stirred in the stirring device 100 to homogenize the glass components.
In the supplying step (ST4), the molten glass is supplied to the forming apparatus 42 through the conduit 43c.

In the forming step (ST5), in the forming device 42, the molten glass is formed into a sheet glass to create a flow of the sheet glass. In the present embodiment, an overflow down draw method using the molded body 45 is used. In the molding step (ST5), molding may be performed using a slot down draw method. In other embodiments, other methods such as a float method, a rollout method, and a redraw method may be used.
In the slow cooling step (ST6), the sheet glass 44 supplied from the molding apparatus 300 is cooled to have a desired thickness, so that plane distortion does not occur and the thermal shrinkage rate does not increase.
In the cutting step (ST7), a sheet glass 44 is obtained by cutting the sheet glass 44 into a predetermined length from the forming device 42 in a cutting device (not shown). The cut glass plate is further cut into a predetermined size to produce a glass plate of a target size. After this, the glass end face is ground and polished, then cleaned, and further inspected for abnormal defects such as bubbles and striae, and then the glass plate that passed the inspection is packed as the final product. The

(Overall configuration of stirring device)
FIG. 3 is a side view of the stirring device 100. FIG. 4 is a schematic side view in which two stirring devices 100 are connected. The stirring device 100 includes a cylindrical stirring tank 101 and a stirrer 102 disposed inside the stirring tank 101. The stirrer 100 of this embodiment includes two stirrers 101 and a stirrer 102 connected to two stirrers 100. The first stirring device 100a on the upstream side and the second stirring device 100b on the downstream side have the same cylindrical shape. The radius and height (size) of the first stirrer 100a and the second stirrer 100b can be arbitrarily changed, and even if the sizes of the first stirrer 100a and the second stirrer 100b are different. Good. The first stirring device 100a includes an upstream conduit 43b attached to the lower side surface and a downstream conduit 46 attached to the upper side surface. The second stirring device 100a includes an upstream conduit 46 attached to the upper side surface and a downstream conduit 43c attached to the lower side surface. The arrow shown by FIG. 4 represents the direction of the flow of the molten glass G stirred with the 1st stirring apparatus 100a and the 2nd stirring apparatus 100b. The molten glass G flows into the first stirring device 100a in the horizontal direction from the upstream side conduit 43b, and is stirred by the stirrer while being guided upward from below in the stirring tank. 2 is agitated by the agitator while being guided downward from above in the agitation tank, and flows out from the agitation tank to the downstream conduit 44c in the horizontal direction.

  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 five stirring blades 106 a, 106 b, 106 c, 106 d, and 106 e connected to the outer peripheral surface of the rotary shaft 105. Yes. The stirring blades 106a, 106b, 106c, 106d, and 106e are arranged at equal intervals in this order from the upper side to the lower side along the rotation shaft 105. The rotation shaft 105 rotates about a center line O connecting the center of the upper surface and the center of the lower surface of the cylindrical shape. That is, the rotating shaft 105 has a configuration in which five stages of stirring blades 106 a to 106 e are arranged along the center line O. The rotating shaft 105 is a tubular member having a hollow inside.

(Positioning of stirrer)
Next, an aspect of positioning of the rotating shaft 105 of the stirrer 102 in the stirring process will be described. FIG. 5 is a projection view in which the stirrer 102 provided in the first stirring device 100 a is projected onto the bottom surface of the stirring tank 101. The arrows in the figure indicate the rotation direction of the stirrer 102, and the stirrer 102 rotates, for example, clockwise as viewed from above. As shown in the figure, the rotating shaft 105 of the stirrer 102 is positioned so as to be shifted to the inflow port 43 in from the central axis of the cylindrical stirring tank 101. A circle indicated by a broken line is a virtual circle C centered on the center O2 of the rotation shaft 105 and having an end E of the blade furthest away from the rotation shaft 105 in the radial direction of the rotation shaft 105 as an arbitrary point on the circumference. is there. O1 indicates the center of the bottom surface 101a of the stirring tank 101 having a circular shape. As shown in the figure, the position of the rotation axis 105 is such that the circumference of the bottom surface 101a includes a proximity point N closer to the projection body of the rotation axis 105 than the other points included in the circumference of the bottom surface 101a. Is positioned. In the drawing, the proximity point N closest to the projection body of the rotation shaft 105 among such proximity points is illustrated. When the rotary shaft 105 is thus positioned, a region is formed in which the distance between the end E of the stirring blade 106 of the stirrer 102 and the side surface of the stirring tank 101 is locally shortened. In this region, a higher shear stress can be applied to the molten glass G between the stirrer 102 and the side surface of the stirring tank 101. By locally increasing the shear stress on the molten glass G, the stirring effect of the molten glass G can be enhanced. In other words, in the stirring device 100a, the rotating shaft 105 is provided so that the shear stress applied to the molten glass G by the side surface of the stirring tank 101 and the stirring blade 106 of the stirrer 102 changes in the circumferential direction of the side surface. From another viewpoint, the stirrer 102 is provided so that the distance between the end E of the stirring blade 106 farthest from the stirrer 102 in the radial direction of the stirrer 102 and the side surface changes in the circumferential direction of the side surface. It can also be said.

  In the present embodiment, it is preferable that the proximity point N is included in a side surface portion corresponding to the inlet 43in of the bottom surface 101a. In other words, the rotating shaft 105 of the stirrer 102 is the end of the stirring blade 106 at the portion corresponding to the inlet 43in on the side surface of the stirring vessel 101 (the portion on the side surface extending in the direction parallel to the rotating shaft 105 from the inlet). It is preferable that E is positioned so as to be closest to the side surface of the stirring tank 101. That is, the rotation shaft 105 has the smallest distance between the end E of the stirring blade 106a farthest from the rotation shaft 105 in the radial direction of the rotation shaft 105 and the side surface of the stirring tank 101 at the portion corresponding to the inlet 43in on the side surface. It is provided to be. In the present embodiment, since the shape of the bottom surface 101a of the stirring tank 101 is a circle, it can also be said that the rotation shaft 105 is positioned so that the rotation shaft 105 approaches the inlet 43in side from the center of the bottom surface 101a.

  When the rotary shaft 105 is positioned in this manner, the end E of the stirring blade 106 of the stirrer 102, the upstream side conduit 43b that is an inflow tube, and the conduit 46 that is an outflow tube are on the side closer to the stirring blade. Therefore, the area where the molten glass G is transmitted through the side surface (wall) of the stirring tank 101 in this portion becomes small. At this time, of the outflow pipe and the inflow pipe, the reason for giving priority to the side closer to the stirring blade 106 is that the closer the distance between the stirring blade 106 and the side surface, the greater the shear stress increases, and the reduction effect of the region that propagates near the side surface. This is because it increases. If the distance between the side surface of the stirring tank 101 and the stirrer 102 is too short, the load that the side surfaces of the stirrer 102 and the stirring tank 101 receive from the molten glass increases. On the other hand, if the distance between the side surface of the stirring vessel 101 and the stirrer 102 is too long, it is difficult to locally apply high shear stress to the molten glass G by the side surface and the stirring blade 106 of the stirrer 102. From such a viewpoint, when the position of the rotating shaft 105 is at an eccentric position such as O2, the distance when the end E of the stirring blade 106 and the side surface of the stirring tank 101 are closest, that is, E and N And the distance between E and N when the position of the rotary shaft 105 is located at O1, is preferably in the range of 0% to 75% or less, and 20 to 70%. More desirably, 40 to 70% is further desirable. By changing the position of the rotating shaft 105, a region where the distance between the stirring member and the side surface of the chamber is locally shortened is formed. In this region, higher shear is generated between the stirrer 102 and the side surface of the stirring tank 101. Stress can be applied to the molten glass G, that is, the amount of the molten glass G that rises along the side surface of the agitation tank 101 without being stirred by the stirrer 102 is reduced. Can be increased. In other areas, the distance between the side surface of the stirring tank 101 and the stirrer 102 becomes longer. As a result, it is possible to reduce the stress applied to the side surfaces of the stirring blade 106 and the stirring vessel 101 from the molten glass G by the stirring device 100 as a whole.

  Next, an aspect of positioning the rotating shaft 105 of the second stirring device 100b on the downstream side by the first stirring device 100a will be described. FIG. 6 is a projection view in which the stirrer 102 provided in the second stirring device 100 b is projected onto the bottom surface of the stirring tank 101. As shown in the figure, the rotating shaft 105 of the stirrer 102 is positioned at O3 shifted from the central axis O1 of the cylindrical stirring vessel 101 to the inlet 46in side and the outlet side 43out. The stirring device 100b has a configuration similar to that of the stirring device 100, except for points specifically described. In the drawing, the top surface of the stirring tank is omitted for illustration. The arrows in the figure indicate the direction of rotation of the stirrer 102. As shown in the figure, the upstream side conduit 46 and the downstream side conduit 43c are arranged at positions shifted from each other by 90 °. Accordingly, the inlet 46in and the outlet 43out of the molten glass G are disposed at positions shifted from each other by 90 °. The stirrer 102 rotates counterclockwise, for example, when viewed from above. In the second stirring device 100b, the stirrer 102 rotates in the opposite direction to the first stirring device 100a. In other words, the rotation direction of the agitator 102 is a direction approaching the outlet 43out as seen from the inlet 46in. The molten glass G immediately after flowing into the stirrer 100b from the inflow port 46in maintains a certain amount of momentum when flowing into the stirrer 100b. In FIG. 6, when the stirrer 102 is rotated clockwise, that is, when the stirrer 102 is rotated away from the outlet 43out when viewed from the inlet 46in, the stirrer 102 is moved from the inlet 46in to the outlet 43out. The momentum that the molten glass G immediately after flowing into the stirrer 100b flows into the stirrer 100b almost disappears during the 270 ° rotation. That is, the amount of the molten glass G that is not stirred by the stirrer 102 and descends along the side surface of the stirring tank 101 is not reduced, and the stirring ability is reduced. Therefore, when the stirrer 102 is rotated in this way, there is a risk that a part of the molten glass G immediately after flowing into the stirring device 100b from the outlet 43out rotates by 270 ° from the inlet 46in to the outlet 43out. There is. On the other hand, if the stirrer 102 is rotated as in this embodiment, only 90 ° is rotated from the inlet 46in to the outlet 43out, and the molten glass G retains a certain amount of momentum when flowing into the stirring device 100b. Since it passes through the outlet 43out in a state, the possibility that the molten glass 7 immediately after flowing into the stirring device 100b flows out of the outlet 43out is small. Therefore, by rotating the stirrer 102 as described above, the time during which the molten glass G stays in the stirring device 100b becomes longer, and the stirring effect of the molten glass is enhanced, so that the molten glass G can be stirred more uniformly. As a result, the occurrence of striae can be reduced. In addition, the shift | offset | difference of the inflow port 46in and the outflow port 43out is not limited to 90 degrees. For example, if this deviation is in the range of 30 ° to less than 180 ° and the rotation direction of the stirrer 102 is a direction approaching the outlet as seen from the inlet, the time for the molten glass to stay becomes longer. The stirring effect of the molten glass is enhanced, and the molten glass can be stirred more uniformly. If the rotation direction of the stirrer 102 is opposite between the first stirrer 100a and the second stirrer 100b, the time during which the molten glass stays becomes longer. The clockwise rotation direction may be a clockwise rotation direction in the second stirring device 100b.

  In the above aspect, the molten glass G flows in from above the stirring device 100b, and the molten glass G flows out from below the stirring device 100b. Conversely, the molten glass G flows in from below the stirring device 100b, It is good also as an aspect from which the molten glass G flows out from the upper direction of the stirring apparatus 100b. Even in this case, when the stirrer 102 is projected onto the bottom surface of the stirring device 100b, at least a proximity point where the circumference of the bottom surface is closer to the projection body of the rotation shaft 105 than the other points included in the circumference of the bottom surface. It is sufficient that the rotary shaft 105 is positioned so as to include one.

Next, the flow of the heterogeneous molten glass BG that causes striae will be described. When this extraordinary molten glass BG enters the sheet glass 44 formed by the forming apparatus 42, it causes streaks, striae, and the like. This striae is a kind of distortion in which the thickness (height) of the glass plate fluctuates within a predetermined width, and continuously occurs in a streak pattern in the conveying direction of the sheet glass 44. For example, SiO ₂ is light and tends to stay on the upper surface side (upper part) of the tube that supplies the molten glass G. In the tube, non-uniformity of these components occurs in the molten glass G, causing striae. For this reason, in the stirrer 100, the heterogeneous molten glass BG is agitated and mixed with other high-quality molten glass G, so that the molten glass G is homogenized and the occurrence of striae can be suppressed. FIG. 7 is a diagram showing a state in which a different molten glass BG flows from the upstream side conduit 43b to the conduit 46 and from the conduit 46 to the downstream side conduit 43c. In this drawing, the molten glass G advances from the front side of the paper toward the back side. Since the different molten glass BG containing a large amount of SiO ₂ is lighter than other high-quality molten glass G, the upstream side conduit 43b before flowing into the stirrer 100a accumulates on the upper surface side (upper part) of the tube. . When the foreign molten glass BG flows into the stirrer 100a, the rotating shaft 105 is eccentric to the upstream conduit 43b side as described above, so that the foreign molten glass BG is mixed with the stirring blade 106 of the stirrer 102. In the region where the distance between the edge E of the slab and the side surface of the stirring tank 101 is locally shortened, stirring is performed with high shear stress. The heterogeneous molten glass BG stirred by the stirring blade 106 rises along the side surface of the stirring tank 101 of the stirring device 100 a and enters the conduit 46 so as to be pushed out by the stirring blade 106. At this time, since the molten glass G has a high viscosity, the foreign molten glass BG does not float on the upper surface side of the pipe in the conduit 46, and the bottom surface side (lower portion) of the conduit 46 is pushed by the momentum pushed out by the stirring blade 106. Flowing. When the rotating shaft 105 of the stirrer 100a rotates clockwise, when entering the conduit 46 from the stirrer 100a, the molten glass G and the foreign molten glass BG travel from the center of the bottom of the conduit 46. On the other hand, the region biased to the left has a high shear stress. Further, the foreign molten glass BG flows from the side surface of the stirring vessel 101 toward the rotating shaft 105 and moves while being stirred by the stirring blade 106. The extraordinary molten glass BG that has flowed toward the rotating shaft 105 is continuously stirred by the stirring blade 106 and thus decreases, and the molten glass G becomes a high-quality molten glass G. FIG. 8 is a view showing a stirring position in a conduit connecting two stirring devices. When the rotation shaft 105 of the stirring device 100a located on the upstream side of the conduit 46 is rotating clockwise, the region near the arrow A1 in the drawing, that is, the region biased to the left from the bottom center of the conduit 46 is stirred. Agitation is performed by the rotating shaft 105 of the apparatus 100a. This is because this region is a region where the foreign molten glass BG is first pushed out by the stirring blade 106 of the rotating shaft 105 and the shear stress is not attenuated. When the extraordinary molten glass BG that has flowed through the conduit 46 flows into the stirrer 100b, the rotating shaft 105 is eccentric to the conduit 46 and the downstream conduit 43c as described above. In the region where the distance between the end E of the stirring blade 106 of the stirrer 102 and the side surface of the stirring tank 101 is locally shortened, stirring is performed with high shear stress. Further, the foreign molten glass BG flows from the side surface of the stirring vessel 101 toward the rotating shaft 105 and moves while being stirred by the stirring blade 106. In addition, the extraordinary molten glass BG that has flowed toward the rotating shaft 105 is continuously stirred by the stirring blade 106, so that it decreases and becomes a high-quality molten glass G. Here, the foreign molten glass BG when flowing into the stirrer 100b is a region that is biased to the right with respect to the traveling direction of the molten glass G and the foreign molten glass BG from the bottom center (bottom top center) of the conduit 46. Is stirred by the rotating shaft 105 of the stirring device 100b. Since the rotating shaft 105 of the stirring device 100b rotates in the direction opposite to the rotating direction of the rotating shaft 105 of the stirring device 100a, that is, counterclockwise, the vicinity of the arrow A2 in FIG. The heterogeneous molten glass BG located on the right side is most stirred. The rotating shaft 105 and the stirring blade 106 of the stirrer 100b and the region located to the right of the center of the bottom surface of the conduit 46 are closest in distance, and the shear stress is not attenuated. Is done. For this reason, in the area | region where a different molten glass BG flows by changing the rotation direction of a stirrer forward / reversely with the stirring apparatus located in the upstream of the conduit | pipe which conveys the molten glass G, and the stirring apparatus located downstream. The stirring ability can be increased. Returning to FIG. 7, the molten glass G and the foreign molten glass BG stirred by the rotating shaft 105 and the stirring blade 106 of the stirring device 100 b descend while being transmitted along the side surface of the stirring tank 101 of the stirring device 100 b. Into the downstream conduit 43c so as to be pushed out into the downstream. At this time, the heterogeneous molten glass BG flows through the upper surface side (upper part) of the downstream side conduit 43c and flows toward the downstream side with the momentum pushed out by the stirring blade 106. As described above, in the conduit to which the two stirring devices 100a and 100b are connected, a path through which the molten glass flows is ensured, and the foreign molten glass BG is stirred, so the foreign molten glass before flowing into the stirring device. The amount of BG decreases after stirring, the molten glass can be sufficiently homogenized, and the occurrence of striae and the like can be suppressed.

  FIG. 9 is a diagram showing an example in which molten glass flows from the upstream conduit to the downstream conduit via the first stirring device and the second stirring device. The arrow shown by FIG. 9 has shown the flow of the molten glass G stirred with the 1st stirring apparatus 100a and the 2nd stirring apparatus 100b. The molten glass G is stirred by the stirring blade 106 of the stirrer 102. However, if the molten glass G continues to flow on the inner side surface (inner wall surface) of the first stirring device 100a, the molten glass G is not stirred by the stirring blade 106. There is a case where it flows into the conduit 46 which is a downstream pipe. And when the stirrer 102 of the 2nd stirrer 100b is the same rotation direction as the stirrer 102 of the 1st stirrer 100a, as shown to the molten glass G which flowed out from the conduit | pipe 46, the broken-line arrow in a figure There is a possibility that the gas flows from the conduit 46 toward the conduit 43c on the side surface of the inner wall of the second stirring device 100b and flows into the conduit 43c without being stirred by the stirrer 102 of the second stirring device 100b. When the rotation direction of the stirrer 102 is the same in the first stirrer 100a and the second stirrer 100b, there is a possibility that there is a molten glass G that is not stirred by the stirrer 102, and a different molten glass. If BG flows to the molding apparatus 300 without being stirred, striae or the like may occur. On the other hand, when the rotation direction of the stirrer 102 is normal in the first stirrer 100a and the second stirrer 100b, the molten glass G flowing out from the conduit 46 is second It flows in the direction of the central axis of the stirrer 102 of the stirrer 100 b and is stirred by the stirrer 102. If the rotation direction of the stirrers of the two stirrers is not the same direction but different from the forward and reverse directions, the molten glass will not be stirred by the stirrer in one stirrer, flowing on the inner wall side surface of the stirrer However, in the other stirring device, the molten glass is stirred by the stirrer without flowing through the inner wall side surface of the stirring device which is the shortest path from the upstream conduit to the downstream conduit. Thereby, it can prevent that the molten glass which is not stirred with the stirrer which a stirring apparatus has is generated.

(Composition of stirring blade)
Next, the configuration of the stirring blades 106a to 106e will be described. In the present embodiment, the stirring blades 106a, 106c, and 106e have the same shape, and the stirring blades 106b and 106d have the same shape. 10 and 11 are a perspective view and a plan view of the stirring blades 106a, 106c, and 106e. 12 and 13 are a perspective view and a plan view of the stirring blades 106b and 106d. 10 and 12 show stirring blades 106a to 106e attached to the outer peripheral surface of the rotating shaft 105. FIG. In the present embodiment, there are two stirring devices, that is, the stirring device 100a and the stirring device 100b. Here, the stirring device 100b will be described as an example. The stirrer 100a has the same configuration as that of the stirrer 100b. However, since the molten glass flows from the bottom surface toward the top surface, the stirrer 100a is symmetrical with the stirrer 100b.

  Each of the stirring blades 106 a to 106 e is disposed so as to extend from the rotating shaft 105 toward the inner wall of the stirring tank 101. Each stirring blade 106a to 106e includes three support plates 108 orthogonal to the center line O of the rotation shaft 105, one upper auxiliary plate 119a disposed on the upper main surface of each support plate 108, And a single lower auxiliary plate 119b disposed on the lower main surface of each support plate. Hereinafter, the upper auxiliary plate 119a and the lower auxiliary plate 119b are collectively referred to as the auxiliary plate 109. The auxiliary plate 109 of the stirring blades 106a to 106e is formed by bending. Specifically, the stirring blades 106a to 106e in which the support plate 108 and the auxiliary plate 109 are integrated are formed by bending one reinforced platinum plate.

  When the stirring blades 106 a to 106 e are viewed along the center line O of the rotating shaft 105, the three support plates 108 of the stirring blades 106 a to 106 e are moved three times with respect to the position of the center line O of the rotating shaft 105. It is arranged at a symmetrical position. The normal line of the main surface of each support plate 108 is parallel to the center line O of the rotation shaft 105. That is, the support plate 108 is disposed horizontally. Further, the three support plates 108 of the respective stirring blades 106 a to 106 e are connected to each other by a connecting portion 110 around the rotating shaft 105. That is, the three support plates 108 of the stirring blades 106a to 106e substantially constitute one component.

  When the support plates 108 of the stirring blades 106a to 106e arranged in two adjacent stages are projected on the bottom surface of the stirring vessel 101, the stirring blades 106a to 106e have the smallest distance between the support plate 108 and the support plate 108. Or the area where the support plate 108 and the support plate 108 overlap is minimized. In the present embodiment, the support plates 108 of the two stirring blades 106 a to 106 e that are adjacent along the center line O of the rotating shaft 105 do not overlap each other when viewed along the center line O of the rotating shaft 105. Are arranged as follows. As an example, FIG. 14 shows the positional relationship between the two stirring blades 106 a and 106 b when the stirrer 102 is viewed along the center line O of the rotating shaft 105. As shown in FIG. 14, each support plate 108 of the stirring blade 106a is located between the two support plates 108 of the stirring blade 106b. That is, the six support plates 108 of the two stirring blades 106 a and 106 b appear to be arranged at positions that are six-fold symmetric with respect to the position of the center line O of the rotating shaft 105.

  The auxiliary plate 109 is disposed on the main surface of the support plate 108 so that the main surface thereof is perpendicular to the main surface of the support plate 108. The auxiliary plate 109 is disposed on the upper main surface and the lower main surface of the support plate 108. As described above, the upper auxiliary plate 119a is disposed on the upper main surface of the support plate 108, and the lower auxiliary plate 119b is disposed on the lower main surface of the support plate 108. 11 and 13, the lower auxiliary plate 119b is indicated by a broken line. When the stirring blades 106a to 106e are viewed along the center line O of the rotating shaft 105, the upper auxiliary plate 119a and the lower auxiliary plate 119b intersect each other.

  The auxiliary plate 109 is disposed so as to extend from the vicinity of the rotation shaft 105 toward the outer edge of the support plate 108. The auxiliary plate 109 has an inner end portion 109a closest to the rotating shaft 105 and an outer end portion 109b opposite to the inner end portion 109a and closest to the outer edge of the support plate 108. ing. When the stirrer 102 is viewed from above, the auxiliary plate 109 gradually moves away from the straight line 111 connecting the center line O of the rotating shaft 105 and the inner end 109a as it goes from the inner end 109a to the outer end 109b. Are arranged as follows. In the case of the stirring blades 106a, 106c, and 106e, as shown in FIG. 11, the upper auxiliary plate 119a is disposed so as to be separated from the straight line 111 in the counterclockwise direction from the inner end 109a toward the outer end 109b. The lower auxiliary plate 119b is arranged so as to be separated from the straight line 111 in the clockwise direction. On the other hand, in the case of the stirring blades 106b and 106d, as shown in FIG. 13, the upper auxiliary plate 119a is disposed so as to be separated from the straight line 111 in the clockwise direction from the inner end 109a to the outer end 109b. The lower auxiliary plate 119b is disposed so as to be separated from the straight line 111 counterclockwise. That is, in each of the stirring blades 106a to 106e, the upper auxiliary plate 119a and the lower auxiliary plate 119b are arranged so as to extend in opposite directions. In addition, the pair of auxiliary plates 109 facing each other between the two stirring blades 106a to 106e adjacent to each other along the center line O of the rotating shaft 105 are arranged so as to extend in the same direction. Yes. For example, the lower auxiliary plate 119b of the agitating blade 106a and the upper auxiliary plate 119a of the agitating blade 106b that is one step below the agitating blade 106a are both arranged so as to be separated from the straight line 111 in the clockwise direction.

(Configuration of the connecting part between the rotating shaft and the stirring blade)
Next, the connection part of the rotating shaft 105 and the stirring blades 106a-106e is demonstrated. Each stirring blade 106a-106e is attached to the outer peripheral surface of the rotating shaft 105 by fitting. A fitting hole 105 a that is a through hole into which a part of the stirring blades 106 a to 106 e is fitted is formed on the outer peripheral surface of the rotating shaft 105. Each of the stirring blades 106a to 106e includes a main body in which three support plates 108 are connected to each other by a connecting portion 110, three bearings 116, and six wedges 126. The bearing 116 is joined to the auxiliary plate 109 as will be described later. The wedge 126 is not joined to the support plate 108 or the bearing 116, but is regarded as one of the members constituting the stirring blades 106a to 106e. The wedge 126 may be joined to the support plate 108 or the bearing 116.

  Each bearing 116 has two wedge through holes 116d for allowing the wedge 126 to pass therethrough. The wedge 126 is a member that has a protrusion that passes through the wedge through hole 116 d of the bearing 116 and is fitted into the fitting hole 105 a of the rotating shaft 105. Each bearing 116 is fixed to the outer peripheral surface of the rotating shaft 105 by two wedges 126 without being joined to the outer peripheral surface of the rotating shaft 105. The stirrer 102 may have a configuration including a bearing 116 in which the wedge through hole 116d is not formed, and a wedge 126 fitted into the fitting hole 105a without penetrating the wedge through hole 116d. Hereinafter, the shape of the bearing 116 and the wedge 126 and a method of attaching the stirring blades 106a to 106e to the outer peripheral surface of the rotating shaft 105 by fitting will be described.

  FIG. 15 is a view showing the arrangement of the rotating shaft 105, the support plate 108 and the bearing 116. FIG. 16 is a side view of the bearing 116 viewed along the radial direction of the rotating shaft 105 at the height position of the support plate 108. In FIG. 16, the support plate 108 is indicated by a dotted line. FIG. 17 is a top view of the bearing 116 as viewed from above in the vertical direction along the center line O of the rotating shaft 105. FIG. 17 shows a cross section of the rotating shaft 105 and a fitting hole 105 a of the rotating shaft 105. FIG. 18 is a top view illustrating a state before the wedge 126 of the stirring blades 106 a to 106 e is fitted to the rotating shaft 105. FIG. 19 is a top view illustrating a state after the wedges 126 of the stirring blades 106 a to 106 e are fitted to the rotating shaft 105. In FIG. 18, an arrow shown in the vicinity of the wedge 126 represents a direction in which the wedge 126 is inserted into the wedge through hole 116 d of the bearing 116 and the fitting hole 105 a of the rotating shaft 105.

  As shown in FIG. 16, the bearing 116 includes an upper end portion 116a, a lower end portion 116b, and a shaft contact portion 116c between the upper end portion 116a and the lower end portion 116b. As shown in FIG. 17, the upper end portion 116 a and the lower end portion 116 b are connected to both ends in the horizontal direction of the shaft contact portion 116 c having an arc shape when viewed from above, in a substantially L shape. As shown in FIG. 17, the main surface of the shaft contact portion 116 c that is opposite to the side to which the upper end portion 116 a and the lower end portion 116 b are connected is in contact with the outer peripheral surface of the rotating shaft 105. doing. As shown in FIGS. 18 and 19, the side surface of the upper end portion 116a is joined to the side surface of the inner end portion 109a of the upper auxiliary plate 119a, and the side surface of the lower end portion 116b is the inner end of the lower auxiliary plate 119b. It is joined to the side surface of the portion 109a. The shaft contact portion 116c and the auxiliary plate 109 are joined by, for example, platinum or a platinum alloy in which a minute gap is formed between the upper end portion 116a and the inner end portion 109a of the upper auxiliary plate 119a, and the gap is melted. Is done by filling in. The shaft contact portion 116c and the auxiliary plate 109 may be joined by welding. Each of the three support plates 108 of the stirring blades 106 a to 106 e is connected to a pair of auxiliary plates 109.

  As shown in FIG. 16, the shaft contact portion 116 c of the bearing 116 includes a bearing upper portion 116 c 1 above the support plate 108 and a bearing lower portion 116 c 2 below the support plate 108. Each of the bearing upper portion 116c1 and the bearing lower portion 116c2 is formed with one wedge through hole 116d. The wedge through hole 116d has a substantially circular cross-sectional shape. In each stirring blade 106a to 106e, the wedge through holes 116d of the bearing upper portions 116c1 of the three bearings 116 are formed at different height positions, and the wedge through holes 116d of the bearing lower portions 116c2 of the three bearings 116 are different from each other. It is formed in the position. A fitting hole 105a is formed on the outer peripheral surface of the rotating shaft 105 at a position communicating with each wedge through hole 116d of the bearing 116 of the stirring blades 106a to 106e. The fitting hole 105a has the same substantially circular cross-sectional shape as the wedge through hole 116d.

  As shown by the arrows in FIG. 18, the two wedges 126 are inserted through the two wedge through holes 116 d of the respective bearings 116 and further inserted into the two fitting holes 105 a of the rotating shaft 105. Each bearing 116 of the stirring blades 106 a to 106 e is fixed to the outer peripheral surface of the rotating shaft 105. That is, each of the stirring blades 106 a to 106 e is attached to the rotating shaft 105 by fitting the six wedges 126 into the six fitting holes 105 a of the rotating shaft 105 via the three bearings 116.

  In this embodiment, the wedge 126 has a substantially circular cross-sectional shape, and has a rod-like protrusion that can be fitted into the fitting hole 105a of the rotating shaft 105 and the wedge through hole 116d of the bearing 116. It is a member. However, the wedge 126 can have any shape with such protrusions.

(Operation of stirring device)
Operation | movement of the stirring apparatus 100 which concerns on this embodiment is demonstrated. FIG. 20 is a diagram illustrating the flow of the molten glass G stirred by the stirring device 100. The arrow shown in FIG. 20 represents the direction of the flow of the molten glass G. Inside the agitation tank 101, molten glass G flows from the upstream side conduit 103 in the horizontal direction. The upper end of the rotating shaft 105 of the stirrer 102 is connected to a motor (not shown). When the stirring device 100 is viewed from above, the stirrer 102 rotates counterclockwise around the center line O of the rotating shaft 105. Inside the agitation tank 101, the molten glass G is agitated by the agitator 102 while being gradually guided downward from above. The stirred molten glass G flows out in the horizontal direction from the inside of the stirring vessel 101 to the downstream conduit 104. 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 is 1500 ° C. to 1750 ° C. It is more suitable in some cases, and it is more suitable in the case of 1530 ° C to 1750 ° C.

  In the stirring vessel 101, the molten glass G is stirred by rotating the stirring blades 106a to 106e. The auxiliary plate 109 of each of the stirring blades 106a to 106e scrapes the molten glass G from the inner wall side of the stirring tank 101 to the rotating shaft 105 side or pushes the molten glass G from the rotating shaft 105 side to the inner wall side of the stirring tank 101. In the present embodiment, in each of the stirring blades 106a to 106e, one of the upper auxiliary plate 119a and the lower auxiliary plate 119b scrapes the molten glass G from the inner wall side of the stirring vessel 101 toward the rotating shaft 105 side, and the other The molten glass G is extruded from the rotating shaft 510 side to the inner wall side of the stirring tank 101. That is, the flow directions of the molten glass G in the radial direction of the rotating shaft 105 are opposite to each other above the support plate 108 and below the support plate 108 of each stirring blade 106a to 106e. Further, with respect to the two stirring blades 106a to 106e adjacent to each other along the center line O of the rotating shaft 105, the main surface of the lower auxiliary plate 119b of the upper stirring blades 106a to 106e and the lower stirring blades 106a to 106e. The main surface of the upper auxiliary plate 119a of 106e is separated from the straight line 111 in the same direction. Therefore, the pair of auxiliary plates 109 facing each other along the center line O of the rotating shaft 105 causes the flow of the molten glass G in the same direction along the radial direction of the rotating shaft 105.

  In addition, about the structure of the stirring apparatus 100, operation | movement, and a modification, the said content is considered including the content described in Unexamined-Japanese-Patent No. 2013-241324. Moreover, the structure of the stirring apparatus 100 includes the content described in Unexamined-Japanese-Patent No. 2010-1000046, Unexamined-Japanese-Patent No. 2011-88816, and Unexamined-Japanese-Patent No. 2014-9136, and the said content is considered.

(Glass plate)
As the glass used for the glass plate of the present embodiment, for example, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, soda lime glass, alkali silicate glass, alkali aluminosilicate glass, alkali aluminogermanate glass, etc. can be applied. it can. The glass applicable to the present invention is not limited to the above.

Examples of the glass composition of the glass plate used in the present embodiment include the following. However, it is not limited to the following glass composition. The content rate display of the composition shown below is mass%.
SiO _2: 50~70%,
B ₂ O _3: 5~18%,
Al ₂ O _3: 0~25%,
MgO: 0 to 10%,
CaO: 0 to 20%,
SrO: 0 to 20%,
BaO: 0 to 10%,
RO: 5 to 20% (However, R is at least one selected from Mg, Ca, Sr and Ba, and the glass plate contains),
It is preferable that it is an alkali free glass containing.

In addition, although it was set as the alkali free glass in this embodiment, the glass plate may contain a trace amount of alkali metals. When the alkali metal is contained, the total of R ′ ₂ O exceeds 0.20% and is 2.0% or less (provided that R ′ is at least one selected from Li, Na and K, and is contained in the glass plate). It is preferable to contain. Moreover, in order to make glass melting easy, it is more preferable that content of the iron oxide in glass is 0.01 to 0.2% from a viewpoint of reducing a specific resistance.

Here, Li ₂ O, Na ₂ O, and K ₂ O are components that may be eluted from the glass to deteriorate the TFT characteristics, and may increase the thermal expansion coefficient of the glass to break the substrate during heat treatment. Therefore, when it is applied as a glass substrate for a liquid crystal display or a glass substrate for an organic EL display, it is preferably not substantially contained. However, by deliberately containing the above-mentioned components in the glass, the basicity of the glass is increased while the deterioration of the TFT characteristics and the thermal expansion of the glass are suppressed within a certain range, and the oxidation of the metal whose valence varies. It is possible to make clear and exhibit clarity. Therefore, the total amount of Li ₂ O, Na ₂ O, and K ₂ O is 0 to 2.0%, more preferably 0.1 to 1.0%, and still more preferably 0.2 to 0.5%. Incidentally, Li 2 _O, without Na 2 _O is allowed to contain, in the component, most glass eluted from be contained hardly K _{2 O} which deteriorates the characteristics of the TFT are preferred. The content of K ₂ O is 0 to 2.0%, more preferably 0.1 to 1.0%, and further preferably 0.2 to 0.5%.

  In the glass of the glass plate, a clarifying agent can be added as a component for defoaming bubbles in the glass. The fining agent is not particularly limited as long as it has a small environmental burden and excellent glass fining properties. For example, from a metal oxide such as tin oxide, iron oxide, cerium oxide, terbium oxide, molybdenum oxide and tungsten oxide. There may be mentioned at least one selected.

Note that As ₂ O ₃ , Sb ₂ O ₃ and PbO are substances having an effect of clarifying the glass by causing a reaction accompanied by valence fluctuation in the molten glass, but As ₂ O ₃ , Sb ₂ O ₃ and Since PbO is a substance having a large environmental load, it is preferable that PbO is not substantially contained. In the present specification, “substantially not containing As ₂ O ₃ , Sb ₂ O ₃ and PbO” means less than 0.01% by mass and intentionally not containing impurities.

  It is preferable that the thickness of the glass plate of this embodiment is 0.05 mm-0.4 mm, for example. The length in the width direction of the glass plate of the present embodiment is, for example, 500 mm to 3500 mm, preferably 1000 mm to 3500 mm, and more preferably 2000 mm to 3500 mm. On the other hand, the length of the glass plate in the vertical direction is, for example, 500 mm to 3500 mm, preferably 1000 mm to 3500 mm, and more preferably 2000 mm to 3500 mm.

  The glass plate manufactured by the manufacturing method of this embodiment is used suitably for the glass substrate for liquid crystal displays, the glass substrate for organic EL displays, and a cover glass, for example. In addition, the glass plate formed by the forming apparatus 300 can also be used as a display for a portable terminal device, a cover glass for a housing, a touch panel plate, a glass substrate or a cover glass of a solar cell. Particularly, it is suitable for a glass substrate for a liquid crystal display using a polysilicon TFT.

  As mentioned above, although the manufacturing method of the glass plate concerning this invention and the stirring apparatus were demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, various improvement and a change are carried out. Of course it is also good.

40 Melting tank (melting part)
42 Molding device (molding part)
43b Upstream side conduit 43c Downstream side conduit 46 Conduit 100 (100a, 100b) Stirrer (stirring section)
DESCRIPTION OF SYMBOLS 101 Stirrer tank 102 Stirrer 105 Rotating shaft 105a Fitting hole 106a-106e Stirring blade 108 Support plate 109 Auxiliary plate 126 Wedge (fitting protrusion)
200 Glass production equipment (Glass substrate production equipment)
G molten glass BG heterogeneous molten glass

Claims (3)

A method of manufacturing a glass plate,
A melting step for melting glass raw material to produce molten glass, a bottom surface, a side surface extending upward from the bottom surface, a stirring tank defined by a top surface intersecting with the side surface, a rotation shaft serving as a rotation center, and a rotation shaft A stirring step of stirring the molten glass in the stirring tank by rotating the stirrer using at least two stirring devices provided with a stirring blade having a stirring blade;
Forming a glass plate by forming the stirred molten glass, and
In the stirring step, the rotating shaft is provided such that a shear stress applied to the molten glass by the side surface and the stirring blade changes in a circumferential direction of the side surface, and each stirrer provided in the two stirring devices includes: Rotate in the forward and reverse directions,
The manufacturing method of the glass plate characterized by the above-mentioned. The side surface of the agitation tank is formed with a port through which the molten glass flows into or out of the agitation tank,
In the stirring step, the distance between the end of the stirring blade farthest away from the rotating shaft in the radial direction of the rotating shaft and the side surface of the rotating shaft is minimum at a portion of the side surface corresponding to the mouth. As provided,
The manufacturing method of the glass plate of Claim 1 characterized by the above-mentioned. An agitation tank supplied with molten glass and having a bottom surface, a side surface extending upward from the bottom surface, and an agitation tank defined by a top surface intersecting with the side surface, a rotation shaft serving as a rotation center, and a stirring blade provided on the rotation shaft A stirring device comprising a vessel,
The rotating shaft is provided such that shear stress applied to the molten glass by the side surface and the stirring blade changes in the circumferential direction of the side surface, and at least two of the stirring devices are connected, and the two stirring devices are provided. Each stirrer rotates in the forward and reverse directions,
A stirrer characterized by the above.

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