JP2011088816A - Glass substrate manufacturing apparatus, glass substrate manufacturing method and stirring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stirring blade for molten glass which is capable of sufficiently stirring the whole molten glass in a stirring tank including the center part area of the tank to homogenize the molten glass even when the number of revolutions is not raised. <P>SOLUTION: The stirring blade is provided with: a vertical bar type first blade 12 vertically provided to extend in a position apart from a rotary shaft line L10 in the rotary radius direction and for stirring the molten glass present in the outer peripheral zone of the stirring tank by rotating in the vicinity of the inner wall of the stirring tank 1; a horizontal bar type second blade 13 provided to extent along the rotary radius direction and stirring the molten glass present in a zone from the center part zone to the outer peripheral part zone in the stirring tank by rotating in a range from the center part zone to the outer peripheral part zone in the stirring tank; and a disk type third blade 14 provided in the inner peripheral side of the first blade to extend in plane in a direction intersecting the rotary axis line to lead the molten glass present in the center part zone in the stirring tank to the outer peripheral part zone. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a stirring blade for molten glass for homogeneously stirring molten glass in a stirring tank, and a stirring device provided with the stirring blade in the stirring tank.

In the production of glass plates, there is a problem that the presence of inhomogeneous glass in molten glass has a great influence on the quality deterioration of glass products. Inhomogeneous glass is a phenomenon in which glass having a different composition exists in molten glass, and characteristics such as specific gravity and refractive index are different from the surrounding molten glass. If the inhomogeneous glass is present in the glass product after being solidified, streaks called striae are generated, which distorts the optical image and impairs transparency and reflectivity.

In particular, in the field of manufacturing glass substrates and optical glass for flat panel displays (FPDs), the occurrence of striae significantly reduces product quality and, for example, striae irregularities cause defects in the formation of TFT circuits. This causes a trouble in the manufacturing process of the display device. In recent years, glass substrates for FPDs tend to increase in size. As glass substrates increase in size, the amount of glass used per product increases.
When the molten glass is formed while the heterogeneous glass is contained, the entire surface of the glass substrate becomes defective, and the product yield is remarkably deteriorated.

The cause of the generation of this inhomogeneous glass is inappropriate mixing of glass raw materials, inadequate melting conditions,
There are various components such as elution components from melting furnace materials and volatilization on the surface of molten glass liquid. Therefore,
In the production of glass plates, mechanical stirring is widely performed as a method for preventing the generation of heterogeneous glass and homogenizing molten glass.

The purpose of stirring is to reduce or eliminate the heterogeneous glass generated in the glass manufacturing process. In particular, since optical glass and glass for FPD substrates are required to have a high degree of homogeneity, it is necessary to homogenize the molten glass in a step before the molten glass is solidified in the molding step. Therefore, the inhomogeneous glass generated in the melting process, the clarification process, or in the transfer pipe to which the molten glass is transferred is eliminated or reduced by mechanical stirring.

Stirring is performed in a cylindrical container or a flow channel called a stirring tank. There is an agitating blade in the agitation tank, and a shearing force is applied to the molten glass by rotating at a predetermined number of revolutions to agitate the molten glass. In the stirring tank, the molten glass flows from the upper inlet and flows out from the lower outlet of the stirring tank while being stirred. Or conversely, it flows in from the lower inflow port and flows out from the outflow port in the upper part of the stirring tank while being stirred.

When a shearing force is applied to the heterogeneous glass in the molten glass, the heterogeneous glass is divided, and the heterogeneous glass disappears or decreases. The portion where the shearing force is generated is a portion where a speed difference occurs in the flow of the molten glass, such as a stirring blade and a stirring tank wall. The stirring speed (number of revolutions: rpm) is appropriately determined depending on the viscosity (temperature) and specific gravity of the molten glass, but the higher the viscosity of the molten glass, the lower the rotation speed. For example, stirring is performed at a low speed of about 10 rpm.

As a conventional stirring blade for molten glass, a so-called crank-type stirring blade or paddle-type stirring blade (for example, see Patent Document 1) or a screw-type stirring blade (for example, Patent Document 2).
See).

FIG. 9 shows an example of a crank type stirring blade. The stirring blade 110 is disposed inside the cylindrical stirring tank 101 and is driven to rotate around a rotation axis set on the central axis of the stirring tank 101, whereby the molten glass G in the stirring tank 101 is driven. The rotary shaft 111 located on the rotational axis and the longitudinal axis extending along the rotational axis at a position away from the rotational axis in the rotational radial direction, and rotating near the inner wall of the stirring tank 101 As a result, the first rod 112 having a vertical bar shape that stirs the molten glass G existing in the outer peripheral region in the stirring tank 101 and the rotation radius direction orthogonal to the rotation axis extend in the stirring tank 101. A horizontal rod-shaped second blade 113 that stirs the molten glass G existing in the range from the central region to the outer peripheral region in the stirring tank 101 by rotating in the range from the central region to the outer peripheral region. I have. The rotating shaft 111 is
It is rotated by a motor 118.

The agitation tank 101 has molten glass inflow / outflow ports 102 and 103 at the top and bottom, and in the agitation tank 101, the molten glass G flows from the upper inflow / outflow port 102 and flows out of the lower inflow / outflow port 103 while being stirred. Or conversely, it flows in from the lower inflow port 103 and flows out from the upper inflow port 102 while being stirred.

JP 2001-72426 A JP 2008-120630 A

By the way, the conventional stirring blade has a problem that the inhomogeneous glass easily flows out due to insufficient shearing force during stirring. That is, some molten glass in the stirring tank extends from the inlet to the outlet with almost no shearing force applied by stirring.

This is considered to be caused by the difference in peripheral speed between the central portion and the outer peripheral portion of the stirring blade. For example, in the case of the crank type stirring blade 110 shown in FIG. 9, as shown in a horizontal section in FIG. 10, the peripheral speed R1 at the center of the rotating stirring blade 110 is small and the peripheral speed at the outer peripheral portion is small. R2 is large.

Therefore, as shown in the schematic longitudinal sectional view of FIG. 11, the molten glass G that has flowed into the outer peripheral region FB of the agitation tank 101 as indicated by the arrow A from the upper inflow port 102 is the vertical rod-shaped first blade 112 and the horizontal The outlet 3 is agitated well while receiving sufficient shearing force by the rotation of the rod-shaped second blade 113.
The molten glass G that has flowed into the central region FA of the stirring tank 101 is not sufficiently subjected to the shearing force due to the stirring, and as shown by the arrow P, the molten glass G passes through the central region FA from above. The phenomenon of going down and going out from the lower outlet 103 occurs. in this way,
Molten glass that does not receive a sufficient shearing force in the stirring tank 101 is insufficiently homogenized due to insufficient stirring, which causes striae. The same applies to the paddle type stirring blade.

In order to solve this problem, it is conceivable to increase the rotation speed of the stirring blade. If the rotation speed of the stirring blade is increased, the shearing force applied to the molten glass in the stirring tank can be increased, and the stirring effect can be increased.

However, when the molten glass has a high viscosity, if the rotational speed of the stirring blade is increased, the high-viscosity molten glass may rotate together with the stirring blade, so there is a limit to increasing the rotational speed.

In addition, platinum or a platinum alloy is used as a material for the stirring tank and the stirring blade from the viewpoint of corrosion resistance and heat resistance. However, when the rotation speed of the stirring blade is increased, the molten glass to be stirred becomes the There is a possibility that a phenomenon of peeling off platinum or the like may occur. The phenomenon in which the molten glass peels platinum and the like is a portion to which a shearing force is applied due to the stirring of the molten glass, and tends to occur as the molten glass becomes higher in viscosity. If foreign matter (platinum foreign matter) such as platinum or platinum alloy that has been peeled off from the stirring tank or stirring blade is mixed in the molten glass, it will be contained in the glass after molding, causing trouble in the product glass. End up. For this reason, the rotation speed of the stirring blade cannot be increased so much.

In addition, in the case of a screw-type stirring blade as described in Patent Document 2, the purpose is to cause molten glass to flow along the shape of a spiral blade by rotational force, and there is a speed difference in the molten glass. Since it does not occur, there is a problem that the action of shearing the molten glass is weak and the stirring effect for eliminating the heterogeneous glass is low.

In consideration of the above circumstances, the present invention can sufficiently stir the entire molten glass in the stirring tank, including the central area of the tank, without increasing the number of rotations, and homogenize the molten glass. It is an object to provide a stirring blade for molten glass and a stirring device for molten glass provided with the stirring blade.

The stirring blade for molten glass of the invention of claim 1 is disposed inside a cylindrical stirring tank, and is rotated by being driven around a rotation axis set on the central axis of the stirring tank. In the stirring blade for molten glass that stirs the molten glass in the tank, the rotating shaft located on the rotational axis and the longitudinal direction extending along the rotational axis at a position away from the rotational axis in the rotational radial direction Then, by rotating near the inner wall of the agitation tank, the first rod-shaped first blade for agitating the molten glass existing in the outer peripheral region in the agitation tank, and the rotation radial direction orthogonal to the rotation axis And agitating the molten glass existing in the range from the central region to the outer peripheral region in the stirring vessel by rotating in the range from the central region to the outer peripheral region in the stirring vessel. Rod-shaped second
A blade, and a molten glass provided in an inner peripheral side of the vertical blade-shaped first blade and extending in a plane shape in a direction perpendicular to the rotation axis, and the molten glass existing in a central region in the stirring vessel And a face plate-like third wing for guiding to the region.

A second aspect of the present invention is the agitating blade for molten glass according to the first aspect, wherein the horizontal bar-shaped second blade and the face plate-shaped third blade are provided in a large number at intervals in the rotation axis direction. It is characterized by being.

A third aspect of the present invention is the stirring blade for molten glass according to the second aspect, wherein the horizontal bar-shaped second blade and the face plate-shaped third blade are integrally formed at the same position in the rotational axis direction. It is characterized by having.

Invention of Claim 4 is the stirring blade for molten glass of any one of Claims 1-3, Comprising: The said 3rd blade | wing of face plate shape is formed as a disc centering on the said rotating shaft. It is characterized by being.

The invention of claim 5 is the stirring blade for molten glass according to any one of claims 1 to 4, wherein the face plate-like third blade is provided with a protruding fourth blade. It is characterized by.

Invention of Claim 6 is the stirring blade for molten glass of any one of Claims 1-5, Comprising: The said 3rd blade | wing of face plate shape inclines with respect to the surface perpendicular | vertical to the said rotating shaft line. It is characterized by being provided with a posture.

The stirring device for molten glass of the invention of claim 7 is disposed with the central axis directed in the vertical direction,
An inflow port is provided on one end side in the vertical direction, and an outflow port is provided on the other end side, so that the molten glass is arranged to flow in the vertical direction, and inside the stirring tank, any one of claims 1 to 6. The agitating blade described in 1 is provided.

According to the first aspect of the present invention, the molten glass present in the central region of the stirring tank, which tends to be insufficiently stirred due to the low peripheral speed of the stirring blade, is surrounded by the face plate-like third blade that performs induction. Since it can be guided to the partial region, the insufficient stirring of the molten glass in the central region can be solved by the stirring action by the first blade and the second blade in the state guided to the outer peripheral region. Therefore, even if it does not raise the rotation speed of a stirring blade, stirring of the molten glass of the whole stirring tank can be accelerated | stimulated, and homogenization of a molten glass can be promoted. As a result, even when inhomogeneous glass flows into the stirring vessel, it is possible to eliminate or reduce the inhomogeneous glass by stirring, and it is not necessary to increase the rotation speed of the stirring blade. Occurrence of a peeling phenomenon such as platinum which is a material of the tank can be suppressed.

According to the second aspect of the present invention, a large number of horizontal bar-shaped second wings and face plate-shaped third wings are provided at intervals in the rotation axis direction. The flow of the molten glass which goes to the outer peripheral part area | region from the center part area | region in a tank can be made, and stirring of molten glass can be accelerated | stimulated.

According to the invention of claim 3, since the horizontal bar-shaped second wing and the face plate-shaped third wing are integrally formed at the same position in the rotation axis direction, the rigidity is improved.

According to the invention of claim 4, the face plate-like third blade is formed as a disk centered on the rotation axis of the stirring blade and has no corners, so there is little risk of being worn by being melted by molten glass. .

According to the invention of claim 5, the presence of the protruding fourth wing provided on the third wing prevents slippage between the molten glass and the third wing, and actively melts the centrifugal force due to the rotation of the third wing. Since it can be imparted to the glass, it is possible to prevent the molten glass from staying on the third blade, and to strengthen the flow of the molten glass from the central region to the outer peripheral region in the stirring tank. Efficiency can be further increased.

According to the invention of claim 6, since the face plate-shaped third blade is provided in an inclined posture, the flow along the inclination can be given to the molten glass, and the molten glass on the third blade is Retention can be prevented. Moreover, since the inclined surface (face plate-like third blade) rotates, the flow in the direction of the rotation axis can be brought to the molten glass, so that the stirring efficiency can be further increased and the molten glass is further homogenized. Can be achieved.

According to the invention of claim 7, the molten glass is sufficiently stirred by the stirring blade while flowing from the upper part to the lower part of the stirring tank or from the lower part to the upper part. The homogenization of the molten glass can be promoted. As a result, even when the heterogeneous glass flows into the stirring tank, the heterogeneous glass can be eliminated or reduced by stirring.

It is a see-through | perspective perspective view which shows the structure of the stirring apparatus provided with the stirring blade of embodiment of this invention. It is a sectional side view of the stirring apparatus. It is a sectional side view for demonstrating the principle of the stirring apparatus. It is a perspective view of the stirring blade of another embodiment of this invention. It is a side view shown as a partial cross section of the stirring blade. It is a perspective view of the stirring blade of another embodiment of this invention. (A) is a partial top view of the stirring blade, and (b) is a side view. It is a figure which shows the modification (a)-(e) of the 4th blade | wing of the stirring blade shown in FIG. 6 and FIG. It is a see-through | perspective side view of the stirring apparatus provided with the conventional stirring blade. It is a principal part horizontal sectional view of the stirring apparatus. It is a sectional side view for demonstrating the principle of the stirring apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a configuration of a stirrer provided with a stirrer blade according to the embodiment, FIG. 2 is a side cross-sectional view of the stirrer, and FIG. 3 is a side cross-sectional view for explaining the principle of the stirrer. .

As shown in FIG. 1 and FIG. 2, this stirring device includes a cylindrical stirring tank 1 installed with the central axis L1 directed in the vertical direction, and a stirring blade 10 disposed in the stirring tank 1. It is composed of A molten glass inlet 2 is provided in the upper part of the stirring tank 1, and an outlet 3 is provided in the lower part. The molten glass G enters from the upper inlet 2 and moves downward in the stirring tank 1, Go out from the lower outlet 3.

The stirring blade 10 stirs the high-viscosity molten glass G in the stirring tank 1 by being driven to rotate at a low speed around the rotation axis L10 set on the central axis L1 of the stirring tank 1.

The stirring blade 10 has a so-called crank shape as a basic shape, and has a rotation axis L10.
The rotation axis 11 located above and the rotation axis L at a position away from the rotation axis L10 in the rotation radius direction
A vertical rod-shaped first blade 12 that stirs the molten glass G present in the outer peripheral region FB in the stirring tank 1 by extending in the vertical direction along the inner wall 10 and rotating near the inner wall of the stirring tank 1. , Rotation axis L
10 extends along the rotational radius direction orthogonal to 10 and rotates in a range from the central region FA in the stirring tank 1 to the outer peripheral region FB, thereby rotating from the central region FA in the stirring tank 1 to the outer peripheral region. F
A horizontal rod-shaped second blade 13 that stirs the molten glass G existing in the range up to B and a longitudinal rod-shaped first blade 12 that is provided on the inner peripheral side and extends in a plane perpendicular to the rotation axis L10. There is a stirring tank 1
And a face plate-like third wing 14 for guiding the molten glass G present in the inner central region FA to the outer peripheral region FB.

At least one horizontal bar-like second wing 13 and face plate-like third wing 14 are provided at intervals in the direction of the rotation axis L10, and are integrally formed at the same position in the direction of the rotation axis L10. At this time, the number of surface plate-like third blades is preferably two or more, and more preferably three to five. The face plate-shaped third wing 14 is formed as a disk centered on the rotation axis L10 and is fixed to the rotation shaft 11 and the second wing 13 in a posture perpendicular to the rotation axis L10. Further, two vertical bar-shaped first blades 12 are arranged at positions opposed to each other by 180 °, and both ends of the first rods 12 are connected to the two first blades 12 so that the horizontal bar-shaped second blades 13 are aligned with the rotation axis L10. It is arranged in a vertical posture. In addition, the 1st wing | blade 12 and the 2nd wing | blade 13 are formed with a round bar, and the diameter of the round bar of the 2nd wing | blade 13 is
It is set to be larger than the thickness of the disk-shaped third blade 14. The disc-shaped third wing 14 is joined to the central portion in the height direction of the round bar constituting the second wing 13.

As described above, the stirring blade 10 is characterized in that a disk-shaped third blade 14 is added to a so-called crank-type stirring blade, and by adding the third blade 14, the stirring device The molten glass G in the central region FA where the stirring effect is difficult to be obtained when rotating at a low speed with the stirring blade of the mold is moved to the outer peripheral region FB in the stirring tank 1, thereby increasing the stirring effect of the molten glass G I have to.

That is, according to this stirring device, the molten glass G present in the central region FA in the stirring tank 1 that tends to be insufficiently stirred due to the low peripheral speed of the stirring blade 10 is shown in FIG. In addition, it can be guided to the outer peripheral region FB by the disc-shaped third wing 14 that performs a guiding action,
By the stirring action by the first blade 12 and the second blade 13 in the state guided to the outer peripheral region FB,
Insufficient stirring of the molten glass G in the central region FA can be resolved. Therefore, even if it does not raise the rotation speed of a stirring blade, stirring of the molten glass of the whole stirring tank can be accelerated | stimulated, and homogenization of a molten glass can be promoted. As a result, even when inhomogeneous glass flows into the agitation tank, it can be eliminated or reduced by agitation, and the phenomenon of peeling of platinum, which is a material of the agitation blades and agitation tank, can occur. Can also be suppressed.

For example, as shown by the arrow A, the molten glass G that has entered the stirring tank 1 from the upper inlet 2.
Among them, the molten glass G that has flowed into the central region FA in the stirring tank 1 has the disk-shaped third blade 14 in the central portion of the stirring blade 10, and therefore, from the central region FA to the outer peripheral region FB. And flows as indicated by the arrow Q, and is stirred by the first blade 12 and the second blade 13 in the outer peripheral region FB. Therefore, stirring of the molten glass G in the entire stirring tank 1 can be promoted, and homogenization of the molten glass G by stirring can be promoted. As a result, even when the heterogeneous glass flows into the stirring tank 1, the heterogeneous glass can be eliminated or reduced by stirring.

In the case of this embodiment, a large number of horizontal rod-shaped second blades 13 and disk-shaped third blades 14 are provided at intervals in the direction of the rotation axis L10. At various places, a flow of the molten glass G from the central region FA in the stirring tank 1 toward the outer peripheral region FB can be created, and the stirring of the molten glass G can be promoted. Further, the disc-shaped third blade 14 is formed as a disc centered on the rotation axis L10 of the stirring blade 10, and has no corners.
There is also little risk of being worn by being melted by the molten glass G. Further, since the horizontal bar-shaped second blade 13 and the disk-shaped third blade 14 are integrally formed at the same position in the direction of the rotation axis L10, there is an advantage that the rigidity of the stirring blade 10 can be improved.

In addition, about the 3rd wing | blade 14, flat plate shapes other than a disc, for example, a polygon (square, hexagon)
It is also possible to make it. However, when the polygon is formed, there is a concern that the “corner” portion is scraped and worn by the molten glass, and the scraped member becomes a foreign substance in the molten glass, which may cause a problem in terms of product quality. Therefore, polygons are less desirable and are most preferably circular. It can also be said that the oval shape is the next best.

Moreover, in the above, although the case where the molten glass was made to flow in from the upper part of the stirring tank 1 and was made to flow out from the lower part was described, you may use it by the reverse flow. In other words, it is a usage in which molten glass flows in from the lower part and flows out from the upper part. In that case, the upper inflow port 2 is the outflow port, and the lower outflow port 3 is the inflow port.

Moreover, in the said embodiment, as shown to FIG. 1 and FIG. 2, the case where the disk-shaped 3rd wing | blade 14 was provided with the attitude | position perpendicular | vertical with respect to the rotating shaft L10 was shown, but FIG. Like the stirring blade 20 shown in FIG. 5, the disk-shaped third blade 24 may be provided in a posture inclined with respect to a plane perpendicular to the rotation axis L <b> 10.

When the face plate-like third blade 24 is provided in an inclined posture as described above, a flow along the inclination of the third blade 24 can be given to the molten glass, and the molten glass G on the third blade 24 can be provided. Can be prevented. Moreover, since the flow in the direction of the rotation axis L10 can be brought to the molten glass G by rotating the inclined surface (face plate-shaped third blade 24), the stirring efficiency can be further increased, and further molten glass can be obtained. Can be homogenized.

Moreover, in the said embodiment, as shown to FIG. 1 and FIG. 2, although the case where nothing was added to the upper and lower surfaces of the disk-shaped 3rd wing | blade 14 was shown, stirring shown to FIG. 6 and FIG. Like the wing 30, the protruding fourth wing 35 can be provided on the plate surface of the disk-shaped third wing 14. In this case, the 4th blade | wing 35 shall be provided in the plate | board surface (the upper surface when flowing from the top, and the lower surface when flowing from the bottom) where the molten glass flows.

In this case, as shown in FIG. 7A, the fourth blade 35 extends radially outward from the outer peripheral surface of the rotating shaft 11, and two fourth blades 35 are provided at positions opposed to each other by 180 ° across the rotating shaft 11. Second wing 1
3 is arranged with an interval of an appropriate angle θ (for example, θ = 60 °) on the front side in the rotation direction R. The value of θ is preferably set to about 90 ° ≦ θ ≦ 30 °. Then, the fourth wing 3
This is because the upper surface region of the third blade 14 (region between the second blade 13 and the fourth blade 35) on the front side in the rotational direction 5 can be widened, and the scraping effect by the fourth blade 35 can be increased. . As shown in FIG. 7B, the fourth wing 35 has the upper half of the second wing 13 made of a round bar as the third wing 14.
It protrudes higher than the height h protruding from the upper surface of the. Otherwise, the scraping effect by the fourth blade 35 cannot be expected.

In the illustrated example, each of the fourth wings 35 is a flat plate perpendicular to the third wing 14 that is inclined such that the height on the rotation center side is high and the height decreases toward the outer peripheral side. Is formed. In addition, each 4th blade | wing 35 may be formed as what is extended from the rotation center side to an outer peripheral side only with the same height, and the height of the rotation center side is high contrary to the thing of the example of illustration, It may be formed with an inclination such that the height decreases as going to the outer peripheral side.

Further, as shown in FIG. 8, the fourth blade 35 can be variously modified.
(A) is an example in the case where the fourth blade 35a is configured by a flat plate standing upright with respect to the third blade 14, and (b) is a flat plate inclined backward with respect to the rotation direction R of the stirring blade. An example in the case where the blade 35b is configured, (c) is an example in which the fourth blade 35c is configured with a flat plate inclined forward with respect to the rotation direction R of the stirring blade, and (d) is a rod-shaped member having a triangular cross section. An example in the case where the fourth blade 35d is configured, (e) shows an example in which the fourth blade 35d is configured by a rod-like member having a semicircular cross section.

For example, as in the example of (b), when the fourth blade 35b is configured by a flat plate inclined backward with respect to the rotation direction R, the third blade is suppressed while suppressing the scraping resistance by the fourth blade 35b. 14 can be moved to the outer peripheral side. Therefore, the fourth wing 35 in FIG.
Compared with the case where a is vertical, the material of the fourth blade 35b is effectively prevented from being peeled off.

Further, as in the example of (c), when the fourth blade 35c is configured with a flat plate inclined forward with respect to the rotation direction R, slippage with respect to the molten glass staying on the third blade 14 can be suppressed. (A
), The scraping effect on the molten glass can be enhanced as compared with the case where the fourth blade 35a is vertical.

If the fourth blades 35d and 35e are triangular or semicircular in cross section as in the examples of (d) and (e), scraping by the fourth blades 35d and 35e is performed as in the example of (b). The molten glass staying on the third blade 14 can be moved to the outer peripheral side while suppressing the resistance to be small. Therefore,
Compared with the case where the fourth wing 35a of (a) is vertical, the material of the fourth wings 35d and 35e is effectively prevented from being peeled off.

Thus, when the 4th blade | wing 35 (35a-35e) is provided on the plate | board surface of the 3rd blade | wing 14, the presence of the 4th blade | wing 35 prevents the slip between molten glass and the 3rd blade | wing 14. can do. Therefore, the centrifugal force due to the rotation of the third blade 14 can be positively applied to the molten glass,
It is possible to prevent the molten glass from staying on the third blade 14. As a result, the flow of the molten glass from the central area FA in the stirring tank 1 to the outer peripheral area FB can be strengthened, and the stirring efficiency can be further increased.

  Next, specific examples will be described.

The viscosity, temperature, and flow rate of the molten glass used here are as follows.
Temperature: 1450 ° C-1550 ° C
Viscosity: 900-2000 poise (100 Pa · s)
Flow rate: 3 cm / min to 6 cm / min

  The composition of the molten glass is as shown in Table 1.

The material of the stirring tank and the stirring blade is platinum or a platinum alloy.
An example of a platinum alloy is “Platinum / Rhodium Alloy” when used for high-temperature molten glass.
And “platinum / iridium alloy”. Moreover, when using it for the molten glass of a low temperature range, "platinum palladium alloy", "platinum / gold alloy", and "platinum / nickel alloy" can be mentioned.

The size of the stirring blade depends on the inner diameter of the stirring tank and the average passing amount (average staying time) of the molten glass. Since there is a restriction in terms of strength and efficiency to increase the size of the stirring tank without limitation,
Usually, a plurality of agitation tanks are installed, for example, these agitation tanks are connected in series with a flow path. At that time, when the preceding agitation tank moves the molten glass from the top to the bottom, the flow path is connected so that the molten glass is moved from the bottom to the top in the agitation tank at the subsequent stage.

The optimum dimensions of the stirring tank and stirring blade are determined as follows.
First, regarding the clearance between the stirring blade and the stirring tank, generally, the smaller the clearance (gap) between the stirring blade and the inner wall surface of the stirring tank, the greater the shear effect. The actual clearance is preferably 10 mm to 30 mm, and most preferably 1 in terms of effectiveness and safety.
It is good to set it as 5-20 mm.

Moreover, as for the dimension of a stirring tank, it is desirable to make an internal diameter into 500 mm or less, 300 mm-40 mm.
Most preferably, it is 0 mm. The depth of the agitation tank is limited by strength because the pressure of the molten glass is applied to the lower part of the agitation tank (can be increased by increasing the thickness of platinum as the agitation tank member). Actually, the depth of the stirring tank is desirably set to 500 mm to 1500 mm, and most desirably 600 mm to 1000 mm.

Further, when the outer diameter of the third blade-shaped blade of the stirring blade is too large, a space between the upper and lower disks becomes a dead space (a space where the molten glass is not stirred). On the other hand, if the diameter of the disc blade is too small, the effect of moving the molten glass in the central region in the stirring vessel, which is the object of the present invention, to the outer peripheral region cannot be obtained. Therefore, the outer diameter of the third blade is 0. 0 when the inner diameter of the stirring tank is 1.0.
It is desirable to set it as 2-0.6.

When the experiment was performed while satisfying the above conditions, when the stirring blade of the present invention was used, it was possible to suppress the occurrence of striae without increasing the rotation speed of the stirring blade, but rather with the rotation speed decreased. I understood that I could do it. That is, when the stirring blade of the present invention is used, the occurrence of striae can be suppressed even when the rotational speed is reduced by 30% of the rotational speed required for homogenizing the molten glass with the conventional stirring blade. From this, the stirring blade of the present invention was able to apply sufficient shearing force to the entire molten glass in the stirring tank, including that in the central region of the stirring tank, and was able to eliminate the heterogeneous glass. I understand that. Moreover, since the rotation speed of the stirring blade could be reduced, no peeling phenomenon of platinum or the like was observed.

The stirring blade of the present invention described above includes a glass plate, a glass plate for an FPD glass substrate,
It can be used for the production of all kinds of glass such as optical glass, architectural glass and bottle glass. The molten glass supply device using the stirring blade of the present invention is suitable for use in a downdraw type molding device, but can also be applied to other types of molding devices.

DESCRIPTION OF SYMBOLS 1 Stirring tank 2 Inlet 3 Outlet 10 Stirring blade 11 Rotating shaft 12 1st blade 13 2nd blade 14 3rd blade 20 Stirring blade 24 3rd blade 30 Stirring blade 35 4th blade 35a, 35b, 35c, 35d, 35e 4th blade G Molten glass L1 Center axis L10 Rotation axis FA Center area FB Outer periphery area

Claims (7)

An agitating blade for molten glass, which is disposed inside a cylindrical agitation tank and agitates the molten glass in the agitation tank by being driven to rotate around a rotation axis set on the central axis of the agitation tank. In
A rotation axis located on the rotation axis;
The melt that exists in the outer peripheral region in the agitation tank by extending in the longitudinal direction along the rotation axis at a position away from the rotation axis in the radial direction of rotation and rotating near the inner wall of the agitation tank A vertical rod-shaped first wing for stirring the glass;
Extending along the rotational radius direction orthogonal to the rotation axis, and rotating in the range from the central region to the outer peripheral region in the stirring tank, from the central region to the outer peripheral region in the stirring tank A horizontal bar-like second wing for stirring molten glass existing in the range of
Provided on the inner peripheral side of the first bar-shaped first blade and extending in a plane shape in a direction perpendicular to the rotation axis, guiding the molten glass present in the central region in the stirring vessel to the outer peripheral region A face plate-shaped third wing,
A stirring blade for molten glass, comprising: A stirring blade for molten glass according to claim 1,
A stirring blade for molten glass, wherein at least one of the horizontal bar-shaped second blade and the face plate-shaped third blade is provided at intervals in the rotation axis direction. A stirring blade for molten glass according to claim 2,
The stirring blade for molten glass, wherein the horizontal rod-shaped second blade and the face plate-shaped third blade are integrally formed at the same position in the rotation axis direction. A stirring blade for molten glass according to any one of claims 1 to 3,
The stirring blade for molten glass, wherein the face plate-like third blade is formed as a disk centered on the rotation axis. A stirring blade for molten glass according to any one of claims 1 to 4,
A stirring blade for molten glass, wherein the face plate-like third blade is provided with a protruding fourth blade. A stirring blade for molten glass according to any one of claims 1 to 5,
The stirring blade for molten glass, wherein the face plate-like third blade is provided in a posture inclined with respect to a surface perpendicular to the rotation axis. The inside of the agitation tank that is arranged so that the molten glass flows in the vertical direction by being arranged with the central axis in the vertical direction, with an inlet at one end in the vertical direction and an outlet at the other end. A stirring device for molten glass, wherein the stirring blade according to any one of claims 1 to 6 is disposed.

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