JP2003267734A - Stirrer for molten glass - Google Patents

Abstract

(57) [Summary] [Problem] To minimize the amount of platinum or platinum alloy used,
And provision of the stirring apparatus for molten glass which has sufficient intensity | strength with respect to the pressure of molten glass. An agitator for agitating molten glass, the agitator comprising a central axis, a drum disposed around the central axis, and an agitating blade disposed around the drum, The inside of the central shaft, the drum, and the stirring blade has a hollow structure that does not have a core material, the portion that comes into contact with the molten glass is made of platinum or the like, and the drum is filled with torque transmitting particulate matter. A stirrer for molten glass, characterized by comprising: The torque transmission granular material is preferably a ceramic, and the torque transmission granular material preferably has an average particle size of 20 to 200 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirrer for stirring molten glass to improve its homogeneity.

[0002]

2. Description of the Related Art Conventionally, in a glass melting furnace, a stirring device has been installed for the purpose of improving the homogeneity of molten glass. The stirring device is generally composed of a stirring shaft having a central axis which is a rotation center and a plurality of stirring blades arranged around the central shaft. Examples of the structure of the stirring device include a drum type in which a stirring blade is arranged around a drum having a large diameter for the purpose of narrowing the flow path of the molten glass, and a screw type in which a stirring blade is provided only at the lower end of the central shaft. To be In addition, various structures such as a fan type, a crank type, a paddler type, and a screw (radial fan) type are being studied for the structure of the stirring blade.

Further, in order to further enhance the effect of stirring by these stirring devices, many inventions have been made in which the structure of the stirring device is combined, the shape of the flow channel or the use condition is improved, or a combination thereof is used. .

In order to stir molten glass having a high viscosity, a large force acts on the stirring blade due to the resistance of the molten glass, so that the stirring blade and the central shaft are made of a material and structure having sufficient strength at high temperature. It must be. Furthermore, since a material having heat resistance to the molten glass having a high temperature and not contaminating the molten glass must be used in a portion of the stirrer in contact with the molten glass, platinum or platinum alloy (precious metal) ( Hereinafter, platinum or the like) is generally used. Platinum and the like have a high melting point, do not contaminate the molten glass, and are extremely stable at high temperatures, so it would be ideal if the stirrer itself could be made of only platinum or the like.

However, in order to have high strength that is not defeated by the pressure of the molten glass, very expensive platinum or the like must be used with a thickness that allows sufficient rigidity. Usually, considering cost, etc., heat-resistant materials other than platinum, such as refractory metals such as molybdenum and refractory materials such as ceramics, are used as core materials, and the surroundings of these core materials are coated with platinum, so that the stirring device In many cases, both heat resistance and strength are achieved.

However, the following problems occur in a structure in which platinum or the like is used as a coating material for the outer periphery and a refractory metal or refractory other than platinum is used as the core material as the stirring device.

First, when molybdenum is used as the core material, molybdenum is easily recrystallized at a high temperature of 1100 ° C. or higher, and as a result, crystal grains grow, and when it is used for a long period of time, the molybdenum itself is transformed by creep deformation. There is a problem that the strength is lowered. When the strength of the molybdenum core material further decreases, the core material is likely to be twisted, and the coating material made of platinum or the like is easily broken. When the coating material is broken, the core material molybdenum is exposed to high-temperature air, and the strength of the molybdenum is rapidly reduced by oxidation, resulting in breakage in a short time.

In order to solve the above problems, Japanese Patent Laid-Open No. 61-
Japanese Patent No. 36123 discloses an invention which prevents a decrease in strength of molybdenum by providing a heat-resistant intermediate layer between a core material made of molybdenum and a coating material containing platinum as a main component. However, the purpose of this intermediate layer is merely to resist heat, that is, to prevent the heat from the molten glass from being transferred to molybdenum through platinum, and not to improve the strength of the stirrer itself.

Further, since molybdenum has a property of being oxidized when it comes into contact with air at high temperature, it cannot be joined by welding. Therefore, in order to manufacture the stirrer, molybdenum metal must be accurately manufactured and assembled into parts such as bolts and rivets, which requires a very troublesome work.

When a refractory material is used as the core material,
If the coating material platinum or the like breaks, the glass is contaminated, and the refractory material is very hard but lacks flexibility, so that the chipping tends to occur due to impact.

As described above, when a refractory metal such as molybdenum other than platinum or a high temperature refractory is used as the core material of the agitator, the aforesaid problems occur. Therefore, the agitator is made of platinum or the like. However, a proposal has been made for a hollow structure that does not use a core material.

However, when the stirrer is made of platinum or the like and has a hollow structure without using a core material, as described above, in order to make the strength of the molten glass comparable to the pressure and the cost, the thickness of platinum or the like should be as much as possible. The structure must be thin and strong. However, heretofore, there is no stirring device having a hollow structure, which is superior in cost and strength to the stirring device using the core material.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an agitator for molten glass which minimizes the amount of platinum or the like used and has sufficient strength against the pressure of the molten glass. .

[0014]

SUMMARY OF THE INVENTION The present invention is a stirrer for stirring molten glass, the stirrer comprising a central axis, a drum disposed around the central axis, and around the drum. The central shaft, the drum, and the inside of the stirring blade have a hollow structure having no core material, and the portion in contact with the molten glass is made of platinum or the like, and the drum is provided. The stirring device for molten glass is characterized in that the torque transmission granules are filled inside.

The torque transmitting particles are preferably made of ceramics, and the average particle diameter of the torque transmitting particles is preferably 20 to 300 μm.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a molten glass stirring apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall view of the stirring apparatus for molten glass according to the present invention, FIG. 2 is a vertical sectional view of the stirring apparatus of FIG. 1, and FIG. 3 is a transverse sectional view of the stirring apparatus taken along the line aa ′ of FIG. Show.
As shown in FIG. 1, the stirring device 10 of the present invention includes a central shaft 1
2 and a drum 14 arranged around the central axis 12, and a stirring blade 16 arranged around the drum 14. The central shaft 12 is formed by inserting the opening 14b of the upper lid 14a of the drum 14 and welding the joint surface thereof so that the central shaft 12 and the drum 14 are integrated. Also,
The drum 14 has a total of 12 stirring blades 16 for sufficiently stirring the molten glass.

The internal structure of the stirring apparatus of the present invention shown in FIG. 1 will be described with reference to FIGS. 2 and 3. In Figure 2,
A longitudinal cross-sectional view of the stirring device of FIG.
Is inserted through the opening 14 b of the drum 14 and the center of the upper disc 20, and is joined to the center of the lower disc 24. The upper disc 20 and the lower disc 24 are attached for the purpose of imparting strength to the drum 14, and the inside of the drum 14 is filled with the torque transmission granules 26.

3 (a) and 3 (b), a- of FIG.
The cross-sectional views of the stirring device along the line a'are shown respectively,
(A) shows a cross-sectional view of the agitator 10 in which the drum 14 is filled with the torque transmission granules 26, and (b) shows the torque transmission granules 2 in order to clearly describe the drawing numbers and the like.
6 shows a cross-sectional view of the stirring device 10 with 6 removed. As shown in FIG. 3 (a), the drum 14 is filled with the torque transmission granular material 26, and as shown in FIG. 3 (b), a vertical bar 30 is provided inside the drum 14. Three pieces are attached to the inside so as to partition the inside of the drum 14. This vertical bar 30 is the central axis 1
2 and the drum 14 by joining the drum 14
The strength of can be improved. Further, the joint surfaces are joined together by welding without any gap.

The thickness of platinum, etc. constituting the stirring device 10, the shape and size of the drum 14, the shape of the stirring blade 16, the number of blades to be installed, the installation angle, etc. are as shown in FIGS. It is not limited, and can be appropriately determined in consideration of the shape of the flow path through which the molten glass flows, the temperature of the molten glass used, the flow rate, and the like. In particular, the molten glass flows from bottom to top in FIG.
In the vertical flow path formed by the furnace material 100 as described above, since the torque transmission granules 26 are filled in the drum 14, the weight of the stirrer is increased, and the torque from the lower portion due to the flow of the molten glass G is increased. It is preferable because it can withstand pressure. Further, the upper end of the central shaft 12 is connected to a rotation driving device (not shown), and the stirring device 10 can be rotated at a desired rotation speed.

As described above, as the material forming the portion that comes into contact with the molten glass, platinum, which is a material that does not contaminate the molten glass, is used. As platinum or the like, it is preferable to use a platinum-rhodium alloy, but fine ceramics, for example, special ceramics dispersion-strengthened platinum or ceramics dispersion-strengthened platinum alloy with enhanced high-temperature strength by dispersing platinum or the like in platinum (hereinafter, It is also possible to use dispersion strengthened platinum. However, in general, dispersion-strengthened platinum and the like are very expensive, and it is usually practiced to limit the range of use to only places where high-temperature strength is required.

The insides of the central shaft 12, the drum 14 and the stirring blades 16 constituting the stirring device 10 of the present invention have a hollow structure having no core material. In the present invention, the core material is a structure that is a core in a conventional stirring device formed of a heat-resistant metal or refractory other than platinum, and in the conventional stirring device, platinum or the like is provided around the core material. By coating with, the heat resistance and strength of the stirrer were achieved at the same time. In the present invention, the main purpose is to keep the strength while reducing the amount of platinum or the like to be used by filling the inside of the drum 14 with the torque transmitting granular material 26 even when the core material does not exist. Therefore, in order to make up for the lack of strength, a disk made of platinum or the like may be attached inside. It is also possible to directly attach the stirring blade 16 from the central shaft 12 and fill the central shaft 12 with the torque transmission granular material 26.

The present invention is characterized in that the torque transmitting particles are filled in the drum of the agitator as described above, and the following remarkable effects are exhibited.

When the central shaft of the stirrer rotates, the torque of the central shaft is transmitted to the stirring blade through the drum upper lid, upper disc, vertical bar, etc., and the stirring blade stirs the molten glass. However, in a hollow-type stirring device that does not have a core material, since the strength of the stirring device itself is reduced because there is no core material, the platinum thickness must be increased in order to have strength that can withstand twisting and deformation. However, it was necessary to take measures such as joining or newly joining as a reinforcement with a platinum plate such as a disc or a vertical rail. However, by filling the inside of the drum of the stirrer with the torque transmitting granules as in the present invention, the torque of the rotating shaft is not limited to the drum upper lid, the upper disc, the vertical rail, etc. As a result, it is transmitted hydrostatically to the stirring blade, so that the strength is increased, troubles such as damage to the welded portion are less likely to occur, and as a result, the required amount of platinum can be reduced. Further, since it is not necessary to use the core material, the time for processing the core material is not required, and the period for manufacturing the stirring device is significantly shortened.

The filled torque transmitting granules are also excellent in that they act as a heat insulating layer. Normally, the upper end of the central axis of the stirrer is at room temperature, while the temperature of the molten glass (about 1000
~ 1400 ° C), the temperature gradient is very large,
The heat of the molten glass flows from the stirrer to the central axis, resulting in a decrease in the temperature of the molten glass.If the number of revolutions of the stirrer is increased too much, the cooling of the molten glass causes the cooling ream (when the molten glass cools). However, there is a problem in that the components in the molten glass are unevenly distributed, which causes a defect that the components look like streaks). However, in the stirrer of the present invention, since the filled torque transmission granules act as a heat insulating layer, the temperature decrease of the molten glass can be suppressed to a minimum, so that the occurrence of cold ream can be suppressed.

Further, the present invention is excellent in that it is possible to accurately determine the replacement time of the stirring device. Normally, a stirrer for molten glass makes it easier to break the coated platinum etc. after long-term use, but since the breaking of platinum etc. cannot be confirmed from the outside in the part immersed in the molten glass, the platinum etc. If it is overlooked and if the platinum or the like further breaks, there is a problem that a part of the stirrer may fall into the molten glass and damage the entire equipment. However, in the stirrer of the present invention, when local breakage of platinum or the like occurs,
The torque-transmitting granules filled inside flow out little by little, and the torque-transmitting granules are detected from the molten glass, so that it is possible to know when to replace the stirring device and minimize damage to the equipment itself. You can

As the torque transmission granules to be filled in the drum of the stirrer, a material having sufficient heat resistance in the temperature range in which the stirrer is used, that is, a material which does not melt even at a high temperature, is particularly preferable. Although not limited, a ceramic material is particularly preferable, and for example, one or more selected from the group consisting of aluminum oxide, zirconium oxide, and yttrium oxide is preferable.

Further, since the torque transmission granular material needs to have a certain degree of fluidity, it is preferable to granulate primary particles having a small particle diameter. The average particle size of the torque transmission granules after granulation is preferably 20 to 300 μm. By setting the average particle size of the torque transmission granules within the above range,
Since the torque transmission granules have a certain degree of fluidity, it is difficult to form a space into which the torque transmission granules do not flow even when filling the inside of the stirring device.

Further, by using the torque transmission granules in the above-mentioned average particle diameter range, a space is formed inside the filled torque transmission granules, and rotation fluctuation caused by the loss of the weight balance between the left and right of the stirring device is prevented. it can. Also, when the stirrer is inserted into the high temperature molten glass, platinum expands due to contact with the high temperature molten glass and, conversely, it dents due to the stress due to the expansion, so very small torque without granulation When the transmission granular material is used, there is a problem that the torque transmission granular material does not follow the expansion of platinum and a space is formed, and the torque transmission of the stirring blade due to the rotation of the central axis becomes insufficient. However, by using the granulated torque transmission granules, the fluidity of the torque transmission granules is increased, and the torque transmission granules flow into the part where platinum has expanded, so that no space is formed and the torque transmission to the stirring blade is reduced. Can be performed sufficiently. The average particle diameter of the granulated torque transmitting granules is more preferably 30 to 150 μm.

Further, the torque transmission granules are solidified by granulating fine primary particles such as ceramics and then heat-treating them.
It is preferable to shrink. Normally, when ceramic powder or the like is heated, a chemical change occurs such that it hardens and solidifies and shrinks, as if a refractory material is manufactured from a ceramic material. When this chemical change occurs inside the stirrer installed in the flow path of the molten glass, the filled torque transmitting granules solidify and lose the fluidity. Moreover, the problem that a space is formed due to the contraction of the filled torque transmission granules simultaneously occurs.

However, when heat treatment is applied after granulating the fine primary particles, the granulated particles are solidified and contracted for each particle. By filling the inside of the stirrer with the torque transmission granules that have been subjected to such treatment, the problems such as the loss of fluidity and the formation of the space described above are prevented, and the torque transmission from the central shaft to the stirring blade is prevented. It can be done enough. The heat treatment is 1400 to 150 in the atmosphere.
It is preferable to carry out the treatment at a temperature of 0 ° C. for 2 to 5 hours. In order to adjust the particle size, it is more preferable to subject the torque transmitting particles that have been solidified and shrunk by heat treatment to a crushing process or the like so as to obtain the average particle size range as described above.

Conventionally, a stirring device having a hollow structure without a core material has a complicated internal structure in place of the core material or requires a very thick member in order to have its strength. I was trying. Therefore, the required amount of platinum or the like is inevitably large, and it is inferior to the stirring device having the core material in terms of cost. However, in the stirrer of the present invention, since the torque transmission granular material also plays a role of imparting strength, the amount of platinum or the like used is significantly smaller than that of the conventional stirrer, and the use of dispersion strengthened platinum or the like. Since the ratio also decreases, the manufacturing cost can be suppressed.

The larger the amount of the torque transmitting granules filled in the stirring device, the more sufficiently the torque can be transmitted, and the amount of platinum or the like used can be reduced. Therefore, it is preferable that the filling amount is as large as possible, but it is actually determined in consideration of the strength of the central shaft that supports the drum of the stirring device, the size of the stirring device to be used, and the like.

The molten glass applicable to the stirrer of the present invention is not particularly limited, and examples thereof include liquid crystal glass, cathode ray tube glass, architectural glass and the like.

[0034]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Example 1 is an example,
Example 2 is a comparative example.

Example 1 A dispersion strengthened platinum alloy (a platinum alloy is
It is formed from 90% by weight platinum and 10% by weight rhodium. ) Center axis formed by the drum, the upper disc,
A stirring device shown in FIGS. 1 to 3 in which the lower disk, the vertical crosspiece and the stirring blade were formed of a platinum alloy which was not dispersion-strengthened was produced, and heat treatment was performed inside the drum at 1450 ° C. for 3 hours. Average particle diameter: 45 μm The granulated aluminum oxide granules were packed. The outer diameter of the central shaft, the inner diameter of the central shaft, and the outer diameter of the drum (excluding the stirring blade) are 46 mm, 41 mm, and 150 mm, respectively, and the size of each of the 12 stirring blades is 45 mm × 30 mm × 2.5 mm. Met. Table 1 shows the weight of the platinum alloy used in the stirrer and the usage ratio of the dispersion-strengthened platinum.

[0036]

[Table 1]

This stirrer is vertically inserted into a vertical channel having an inner diameter of 250 mm as shown in FIG. 4 in which molten glass for liquid crystal at 1275 ° C. flows, and the molten glass is shaped into a plate after passing through the channel. Was continuously used for 26 months at a rotation speed of 3.5 rotations / minute and then taken out. There was no trouble caused by the rotating device during continuous use, and the appearance of the stirring device after taking out was not significantly different from that before taking out. In addition, the number of rotations of the stirring device of Example 1 was 5 rotations /
Even if it was raised to a minute and used, cold ream did not occur.

(Example 2) The number of upper and lower discs inside the drum of the stirrer was increased from one to two, the outer frame of the drum was doubled, and the central shaft, upper disc and The lower disk is made of dispersion-strengthened platinum alloy (platinum alloy is composed of 90% by weight of platinum and 10% by weight of rhodium), and the drum, vertical rail and stirring blade are not dispersion-strengthened platinum alloy. The stirring device was produced in the same manner as in Example 1 except that the aluminum oxide particles were not filled inside the stirring device. At this time, Table 1 shows the weight of the platinum alloy used in the stirrer and the usage ratio of the dispersion strengthened platinum.

This stirrer was operated under the same conditions as in Example 15
After being used for a month, the welded part was damaged and became unusable. Moreover, when the number of rotations of the stirring device of Example 2 was increased to 5 rotations / minute and used, a cold ream was generated.

[0040]

EFFECTS OF THE INVENTION The stirring apparatus of the present invention can continuously homogenize high temperature and high viscosity molten glass for a long period of time. That is, the stirring device of the present invention, since the torque transmission particles are filled in the drum of the hollow stirring device,
The torque of the rotating shaft is hydrostatically transmitted not only to the drum top cover, upper disc, vertical bar, etc. but also to the stirring blades using the torque transmission granules as a medium, so the strength is improved and the welded part is damaged, etc. The trouble described above is less likely to occur, and as a result, the amount of platinum and the like and the amount of dispersion strengthened platinum and the like that are required can be reduced.

Further, conventionally, it took a very long time to process the core material, but since the stirring device of the present invention can obtain high strength without using the core material, the period for manufacturing the stirring device is drastically increased. It can be shortened. In addition, since the torque transmission granules act as a heat insulating layer, the temperature drop of the molten glass can be minimized and the generation of cold ream can be effectively prevented. It is also possible to accurately determine the replacement timing of the stirring device based on the outflow.

Further, by setting the average particle size of the torque transmitting granules to be 20 to 300 μm, the fluidity of the torque transmitting granules is ensured, and it becomes difficult to form a space inside the torque transmitting granules, so that the rotation occurs. The fluctuation can be suppressed, and the torque can be sufficiently transmitted to the stirring blade.

Further, the torque transmission granules having an average particle diameter of 20 to 300 μm are solidified and contracted by heat treatment, so that the torque transmission granules in the stirrer when inserted into the molten glass flow path. It is possible to prevent solidification and shrinkage, and to sufficiently transmit torque to the stirring blade.

The amount of platinum or the like required in the stirrer of the present invention can be greatly reduced as compared with the conventional stirrer, and the use ratio of dispersion strengthened platinum or the like can be reduced, so that the manufacturing cost can be suppressed. be able to.

[Brief description of drawings]

FIG. 1 is an overall view of a molten glass stirrer according to the present invention.

FIG. 2 is a vertical cross-sectional view of the stirring device of FIG.

3 is a cross-sectional view of the stirring device taken along the line aa ′ in FIG. 2, and FIG. 3 (a) is a cross-sectional view of the stirring device in which the torque transmission granules are filled in the drum. b) It is a transverse cross-sectional view of the stirring device in a state in which the torque transmission particles are removed.

FIG. 4 is a cross-sectional view of a stirrer according to the present invention installed in molten glass in a vertical channel.

[Explanation of symbols]

10: Stirrer 12: central axis 14: Drum 14a: Top lid 14b: opening 16: Stirrer 20: Upper disc 24: Lower disc 26: Torque transmission granular material 30: Vertical cross 100: Furnace material G: Molten glass

Claims (3)

[Claims] 1. A stirrer for stirring molten glass, the stirrer comprising a central axis, a drum disposed around the central axis, and a stirring blade disposed around the drum. The inside of the central shaft, the drum, and the stirring blade has a hollow structure without a core material, and a portion that comes into contact with molten glass is made of platinum or the like, and the inside of the drum is filled with a torque transmitting granular material. A stirrer for molten glass, characterized in that 2. The stirrer for molten glass according to claim 1, wherein the torque transmitting particles are ceramics. 3. The average particle size of the torque transmission granules is 20 to.
The molten glass stirrer according to claim 1 or 2, which has a thickness of 300 μm.