JP2002234736A - Flow rate regulating device of fused glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate regulating device of fused glass which enables the supply of a fused glass block which is small in weight fluctuation, is excellent in shape, is stria free and is excellent in optical quality for a long time to a molding die. SOLUTION: This flow rate regulating device of fused glass is provided with an outlet pipe 3 made of platinum or platinum alloy which is attached to an outlet 2 of a glass fusion vessel 1, power feeding terminals 11, 12 made of platinum or platinum alloy which is connected with the outlet pipe in order to impress the DC or AC voltage on the outlet pipe 3 and a power feeder 16 for supplying the power to the power feeding terminals. Furthermore, terminals 13, 14 having bends made of gold are connected with the base edge sides of the power feeding terminals 11, 12 and the terminals made of gold are equal in electric resistance and is smaller in strength as compared to the power feeding terminals 11, 12 made of platinum or platinum alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for preventing a deformation of an outflow pipe for a long time when supplying molten glass to a molding die or the like through a glass outflow pipe and realizing an accurate flow rate. is there.

[0002]

2. Description of the Related Art A molten glass flow rate adjusting device for adjusting the flow rate of glass when supplying the molten glass to a molding die or the like is disclosed in Japanese Patent Publication No. 40-11742 and Japanese Patent Application Laid-Open No. Sho 64-7.
It is disclosed in Japanese Patent Publication No. 2927. The former is shown in FIG. 4 and the latter is shown in FIG.

The former device will be described with reference to FIG. This apparatus applies an outflow pipe 103 made of platinum or a platinum alloy attached to an outflow port 102 of a glass melting tank 101, a heat insulating material 104 covering the outflow pipe 103, and applies a DC or AC voltage to the outflow pipe 103. Terminals 105 and 106 connected to the outflow pipe 103 and the power supply device 107
And a thermocouple 109 welded to the outflow pipe 103 for detecting the temperature of the outflow pipe 103 (the temperature of the molten glass 108 flowing in the outflow pipe 103). In this case, while detecting the temperature of the outflow tube 103 or the molten glass 108 with the thermocouple 109, a DC or AC voltage is applied to the outflow tube 103, and the viscosity of the glass 108 is controlled by the heat generation action of the outflow tube 103 itself. The flow of the glass 108 is adjusted.

The latter device will be described with reference to FIG. The device comprises an outlet pipe 111 which is connected to an upper part 111a and a lower part 1a.
11b, the electric resistance of the lower part is made larger than that of the upper part, and the calorific value of the lower part of the outflow pipe can be made larger. In FIG.
The thickness of the outflow pipe is the same, and the electrical resistance of the lower portion is increased by making the inner diameter of the lower portion 111b slightly smaller than the inner diameter of the upper portion 111a. Thus, even if the outflow pipe tip 116 is exposed, glass can be discharged without lowering the temperature of the outflow pipe tip 116. Since there is no heat insulating material in the vicinity of the outflow pipe tip 116, a glass flow cutting device (not shown) or the like can be easily attached immediately below the outflow pipe tip 116.

[0005]

The above apparatus detects the temperature of the glass (108 or 119) flowing in the outflow pipe with almost no time lag, controls the temperature of the outflow pipe (103 or 111), and regulates the flow rate. Both are excellent devices in that they can do this.

However, it has been found that when the outflow of the molten glass is performed for a long time using such a conventional flow control device, the following problem occurs.

In the flow control devices shown in FIGS. 4 and 5, the power supply terminals (105, 106, 113, 114) are provided only on one side of the outflow pipe (left side in the figure). Using such a device, the temperature was raised in the morning to start the outflow of molten glass, and continued to flow in the same temperature range for about 6 hours until the evening, then lowered the temperature in the evening and stopped the outflow As a result of repeating this operation every day, the intermediate portions 121 and 124 of the outflow pipe were curved as shown in FIGS. When the experiment was further continued, the degree of bending progressed little by little with the passage of time, and when the heat insulating materials 122 and 125 were peeled off three months later, it was found that the middle part of the outflow pipe was crushed. Also, it was found that the cross-sections of the distal end portions 123 and 126 of the outflow pipes were initially circular, but collapsed into elliptical shapes after about one month.

As a result of the curvature of the outflow pipe and the collapse of the cross-sectional shape of the outflow pipe, the flow rate of the glass changes under the same temperature setting, and the weight of the molten glass lump supplied to the forming die or the like becomes constant. However, the cross-sectional shape of the outflow glass was crushed by reflecting the cross-sectional shape of the outflow pipe, and a problem occurred in that a molten glass lump having a desired shape could not be obtained, and striae occurred in the molten glass lump. It is not clear that the cause of the striae is unclear, but it is because the flow of glass is disturbed inside the outflow pipe and at the place where it exits from the tip of the outflow pipe as a result of the curvature of the outflow pipe and collapse of the cross-sectional shape. is expected.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a molten glass ingot having a small weight variation, a good shape, and a good optical quality without striae over a long period of time. To provide a molten glass flow rate control device capable of supplying the molten glass to a molding die or the like.

[0010]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a flow control device for molten glass according to the present invention includes a platinum or platinum alloy outflow pipe attached to an outflow port of a glass melting tank, and applies a DC or AC voltage to the outflow pipe. A power supply terminal made of platinum or a platinum alloy connected to the outflow pipe, and a power supply device for supplying power to the power supply terminal, and having a bent portion made of gold on a base end side of the power supply terminal. A terminal is connected, and the gold terminal is characterized in that it has the same electrical resistance and a lower strength than the power supply terminal made of platinum or a platinum alloy.

The apparatus for controlling the flow rate of molten glass according to the present invention comprises an outflow pipe made of platinum or a platinum alloy attached to an outflow port of a glass melting tank, and a DC or AC voltage applied to the outflow pipe. A power supply terminal made of platinum or a platinum alloy connected to the outflow tube, and a power supply device for supplying power to the power supply terminal, wherein the power supply terminal is axially symmetric with respect to the flowing direction of the glass. And a terminal having a bent portion made of gold is connected to the base end side of the power supply terminal. The gold terminal has an electric resistance lower than that of the power supply terminal made of platinum or a platinum alloy. Are equivalent and have low strength.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

[0013] In one embodiment of the present invention, there is provided a flow control device comprising an outflow pipe made of platinum or a platinum alloy attached to an outflow port of a glass melting tank, a heat insulating material covering the outflow pipe, and a direct current or direct current flowing through the outflow pipe. A power supply terminal made of platinum or a platinum alloy connected to the outflow pipe for applying an AC voltage, a power supply device, and an outflow pipe for detecting the temperature of the outflow pipe (the temperature of the molten glass flowing in the outflow pipe). In a flow control device for molten glass provided with a thermocouple welded to a terminal, a terminal having a bent portion made of gold is connected to the base end side of the power supply terminal, and the gold terminal is a power supply made of platinum or a platinum alloy. Compared to the terminals, the electrical resistance is equal to or less than that and the strength is reduced.

Thus, when the temperature of the outflow pipe is raised or lowered, even if the length of the outflow pipe changes due to thermal expansion and contraction, the gold terminal connected to the base end side of the power supply terminal is deformed, and the outflow occurs. It is possible to prevent the force from being applied to the pipe, and it is possible to prevent the outflow pipe from being curved or the outflow pipe from being collapsed in cross section.

A flow control device according to another embodiment of the present invention includes an outflow pipe made of platinum or a platinum alloy attached to an outflow port of a glass melting tank, a heat insulating material covering the outflow pipe, and an outflow pipe. A power supply terminal and a power supply device connected to the outflow pipe for applying a DC or AC voltage to the outflow pipe, and welded to the outflow pipe for detecting the temperature of the outflow pipe (the temperature of the molten glass flowing in the outflow pipe). In the molten glass flow rate control device provided with a thermocouple, the power supply terminal is installed at an axially symmetric position with respect to the flowing direction of the glass, and further, a terminal having a bent portion made of gold on the base end side of the power supply terminal. Connect the gold terminal, compared to the platinum or platinum alloy power supply terminal,
The electrical resistance is equal to or less than that, and the strength is reduced.

Thus, even if the temperature of the outflow pipe rises and falls relatively quickly, the gold terminal connected to the base end of the power supply terminal responds to the change of the length of the outflow pipe due to thermal expansion and contraction. Is deformed to prevent the force from being applied to the outflow pipe, and it is possible to prevent the outflow pipe from being curved or the outflow pipe cross-sectional shape from being crushed.

Hereinafter, embodiments will be specifically described.

First Embodiment First, an outline of a molten glass flow rate control device according to a first embodiment will be described with reference to the drawings.

FIG. 1 is a view showing an apparatus for controlling the flow rate of molten glass according to a first embodiment, wherein 1 is a glass melting tank in which an outflow pipe 3 is attached to an outlet 2 at the bottom. Both the melting tank and the outflow pipe are made of platinum or a platinum alloy. The melting tank 1 is installed in a glass melting furnace 4 made of a refractory or a heat insulating material, and the furnace atmosphere 5 is heated by a heater 6 so that the molten glass 7 in the melting tank can be melted. .

The molten glass 7 in the glass melting tank is stirred and homogenized by a stirring rod 8 so that glass without striae can flow out. The portion of the stirring rod that contacts the molten glass 7 is made of platinum or a platinum alloy.

On the right side of FIG. 1, although not shown, a device for charging a predetermined weight of glass raw material is provided, and by inputting a glass raw material having a weight corresponding to the glass outflow amount, The height of the molten glass liquid surface 9 can be kept constant. Then, if necessary, the glass can be continuously melted and flown out.

The outflow pipe is covered with a heat insulating material 10. Feeding terminals 11 and 12 made of platinum or a platinum alloy of the same material as the outflow tube are welded to the outflow tube. At the base end of each power supply terminal, a plate-like terminal 13, 1 made of gold is provided.
4 are welded, and each has a bent shape so that it can be slightly expanded and contracted. Further, a power supply wire 15 is connected to the end of the gold terminal, and a voltage is applied from a power supply device 16. 17 is the outflow pipe 3
(A temperature of the molten glass flowing in the outflow pipe) and is welded to the outflow pipe 3.

Although not shown, for example, a molding die for receiving the outflow glass 20 for a predetermined time to obtain a molten glass lump is installed immediately below the outflow tube tip portion 19.

The molten glass flow control device described above is
A DC or AC voltage is applied to the outflow pipe 3 by the power supply device 16, and the temperature of the glass 18 (that is, corresponding to the viscosity) is changed by the heat generated by the Joule heat of the outflow pipe itself, thereby adjusting the flow rate of the molten glass. At that time, thermocouple 1
Adjusting the flow rate of the molten glass 18 in the pipe by adjusting the voltage of the power supply device 16 so that the temperature of the outflow pipe 3 becomes a set value while detecting the temperature of the outflow pipe 3 at 7. Can be.

Next, a specific glass outflow experiment was attempted.
The outflow pipe 3 has a thickness of 1.5 mm, an inner diameter of 6.0 mm, and a length of 50 mm.
0 mm (from the outlet 2 of the glass melting tank to the outlet pipe tip 19
Length), made of platinum. Power supply terminal 11,
The material of No. 12 is the same platinum, thickness 2.0 mm, width 20 m
m, a plate shape having a length of 50 mm (in the left-right direction in FIG. 1). A heat insulating material 10 having a thickness of 12.5 mm is wound around the outflow pipe 3 to form a heat insulating material 10.

At the base end of the power supply terminal, a bent plate made of gold, which is a feature of the present embodiment, is welded as terminals 13 and 14. The gold terminal had a thickness of 0.5 mm, a width of 20 mm, and a length of 60 mm when extended. The thickness of the gold terminal is as thin as 1/4 of that of the platinum power supply terminal, but since the width is the same, the force required for bending is considerably smaller than that of the platinum power supply terminal. As for the cross-sectional area, the gold terminal is １ ／ of the platinum power supply terminal. The specific resistance of gold and platinum is, for example, 20 ° C.
In contrast to platinum, which is 10.6 × 10 ^-6 Ωcm, that of gold is 2.2 × 10 ^-6 Ωcm, which is about 1/5. Accordingly, the electrical resistance per unit length of the gold terminals 13 and 14 and the platinum power supply terminals 11 and 12 is substantially equal or slightly different.
Since the gold terminals are smaller, it is possible to prevent the gold terminals from abnormally generating heat when energized.

Using the apparatus described above, the outflow of heavy barium crown optical glass was attempted. The glass is a specific gravity at room temperature is ^{3.3, 1300 ℃ 10 1.5 dPa ·} s 1200 10 2.2 dPa · s 890 when 10 ^1.6 dPa · s 1100 ℃ when 10 ^1.8 dPa · s 1000 ℃ when ° C. When the It has a viscosity characteristic of 10 ^2.9 dPa · s at 610 ° C., 10 ^7.6 dPa · s at 610 ° C., and 10 ¹³ dPa · s at 498 ° C. This glass was melted in the melting tank 1 and adjusted to 1000 ° C. The stirring rod 8 is 60 rpm
m so that the molten glass 7 was homogenized.

Next, the outflow pipe 3 was heated by energization.
To do this, while detecting the temperature of the outflow pipe 3 with the thermocouple 17, the temperature of the outflow pipe 3 is raised at a rate of 100 ° C./min.
The voltage of the power supply device 16 was adjusted to be 0 ° C. At this time, since the length of the outflow pipe 3 becomes longer due to thermal expansion with an increase in temperature, the height of the outflow pipe tip 19 is lowered by 4 to 5 m.
m lower. Corresponding to the elongation of the outflow pipe, the gold terminals 13 and 14, particularly the 14 on the tip side of the outflow pipe, were deformed, but no deformation was observed in the platinum power supply terminals 11 and 12. The flow rate of the molten glass at this time was 12 g / min. By changing the temperature measured by the thermocouple 17 to, for example, 850 to 1100 ° C., the flow rate of the molten glass can be changed in a range of 2 to 40 g / min, and the flow rate can be set as necessary. it can.

Next, the molten glass 20 is obtained by receiving the outflow glass 20 for 10 seconds by using a molding tool (not shown) installed immediately below the outflow pipe end portion 19. Was. When this operation was continuously performed for 6 hours, six molten glass blocks were obtained per minute, and about 6160 molten glass blocks were obtained in six hours. In terms of weight, 97% of the glass block is 2
g was within ± 1%, which was good. Striae were not observed in all the glass ingots regardless of the weight, and the optical quality was also good. The roundness (variation due to the difference in diameter in the radial direction) was also good within ± 1% of the diameter for all the glass blocks regardless of the weight.

Next, the temperature was lowered at a rate of 100 ° C./min until the temperature of the outflow pipe 3 became 500 ° C. or less, and the outflow of glass was stopped. Then, further at room temperature (about 20-25
(° C.).

The steps of raising the temperature of the outflow pipe 3 (start of outflow of glass), outflow of glass for about 6 hours, and lowering of the temperature of the outflow pipe (stopping outflow) have been described above. After the temperature was raised, the glass flowed out for 6 hours to obtain a glass lump, and in the evening, the temperature of the outflow pipe was lowered to stop the outflow of the glass. This operation was continued for about six months, during which time approximately 95% of the glass mass was weight, striae,
It had good quality in both roundness. After the experiment for 6 months, the heat insulating material 10 was peeled off and the outflow pipe 3 was examined, but almost no deformation was observed.

The rate of temperature rise and fall of the outflow pipe 3 was set at 100 ° C./min as described above. However, if this rate is increased, the quality of the outflow glass deteriorates and the way the outflow pipe deforms is advanced. Tended to be faster. In the case of the device used in the first embodiment,
In order to obtain good quality glass lumps and not to deform the outflow tube, both the heating rate and the cooling rate should be about 20 min / min.
It was found that the temperature should be 0 ° C. or less.

(Comparative Example 1) Here, for comparison, the results of an experiment performed with a conventional apparatus will be described. The conventional device is shown in FIG.
The device shown in Table 1 was used.

In this comparative experiment, except for not using the gold terminal used in the first embodiment, the type of glass and
Materials and dimensions of the outflow pipe 103 and the power supply terminals 105 and 106,
Further, the set temperature conditions and the like are all the same as in the first embodiment. Although not shown in FIG. 4, a stirrer for stirring and homogenizing the molten glass 110 and a glass raw material charging device are provided as in the first embodiment.

In this case, the outflow tube is heated at a rate of 100 ° C./min in the morning, and then the glass is discharged for 6 hours to obtain a glass lump. In the evening, the temperature of the outflow tube is increased to 100 ° C./min. When the operation of lowering and stopping the outflow of glass is repeated every day in the same manner as in the first embodiment, for the first half month, approximately 90% or more of the produced glass lump has weight, striae and trueness. It had good quality in both roundness. However, only about one month after the start of the experiment, the outflow pipe intermediate portion 121 was curved as shown in FIG. As the experiment continued, the degree of curvature gradually progressed over time,
Three months later, when the heat insulating material 122 was peeled off, it was found that the middle portion of the outflow pipe was almost crushed. Also, it was found that the cross section of the outflow pipe tip portion 123 was initially circular, but was crushed into an elliptical shape after about one month.

As a result of such curvature of the outflow pipe and collapse of the outflow pipe cross-section, after about half a month from the start of the experiment, the glass flow began to decrease under the same temperature setting.
Unless the temperature of the outflow pipe 103 is gradually increased or the time for supplying the outflow glass to the mold is not increased, the weight of the molten glass lump obtained on the mold does not fall within the tolerance of ± 1%, and this In that case, it was less than 2 g.

Similarly, as a result of the curvature of the outflow pipe and the collapse of the cross-sectional shape of the outflow pipe, it was found that the roundness of the molten glass lump deteriorated after about one month from the start of the experiment. After about 3 months, the roundness of most molten glass blocks is ±
It exceeded 1%, and a good-shaped thing could not be obtained practically.

The same applies to the stria. As a result of the outflow pipe bending and the collapse of the outflow pipe cross-section, stria was observed in the molten glass lump after about one month from the start of the experiment.

As described above, the platinum power supply terminal 1
The electrical resistance of the gold terminals 13 and 14 at the base end is set to be equal to or less than 1 and 12, and by reducing the strength, when the temperature of the outflow pipe 3 is raised or lowered, the thermal expansion and contraction is reduced. Accordingly, even if the length of the outflow tube changes, the gold terminal is deformed, so that it is possible to prevent the force from being applied to the outflow tube.

As a result, even if the temperature of the outlet pipe is repeatedly raised and lowered, the molten glass ingot having a small weight fluctuation, a good shape, and a good optical quality without striae can be supplied to a molding die or the like over a long period of time. Can be provided.

In the above description, the outflow pipe is attached to the bottom of the glass melting tank so as to face vertically downward. Alternatively, the outflow pipe may be attached to the side surface of the melting tank or the direction may be horizontal. It does not matter if it is directed in the direction or obliquely downward, or is given a predetermined bend in advance. In addition, a configuration in which a plurality of power supply devices are prepared as necessary and the outflow pipe is divided into a plurality of zones and energized and heated may be used. In this case, at the base end of the power supply terminal made of platinum or platinum alloy,
If the gold bent terminals are connected, the first
Needless to say, the same effects as those of the embodiment can be obtained. Further, the set temperature of the outflow pipe is not limited to the condition of the first embodiment, and the condition can be appropriately changed according to the glass material used, the desired weight of the glass lump, and the like.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The device of the second embodiment is basically the same as that of the first embodiment,
Outflow pipe shape is different. In the second embodiment, the outflow pipe 31 is composed of an upper part 31a and a lower part 31b, and the electric resistance of the lower part is made larger than that of the upper part, so that the lower part of the outflow pipe generates heat. The amount can be increased. Thereby, even if the outflow pipe tip 32 is exposed, the glass can flow out without lowering the temperature of the outflow pipe tip. The thickness of the outflow pipe is 1.5 mm as in the first embodiment, the inner diameter of the upper part 31a is 6.0 mm, and the inner diameter of the lower part 31b is 4.0 mm. The length of the upper part 31a is 300 mm, the length of the lower part 31b is 200 mm, and the length of the entire outflow pipe is 500 mm. The material of the outflow pipe 31 is the same as that of the first embodiment, and is made of platinum.

The material of the power supply terminals 33 and 34 is also platinum, 2.4 mm in thickness, 16 mm in width, and 70 mm in length (FIG. 2).
In the left-right direction). A heat insulating material 35 having a thickness of 12.5 mm is wound around the outflow pipe 31 to form a heat insulating material 35.

At the base end, a bent plate made of gold
6, 37 are welded. Gold terminals are 0.6 thick
mm, the width was 16 mm, and the length when extended was 80 mm. The gold terminal has a thickness of 1/4 of the platinum power supply terminal.
Since the widths are the same, the settings are the same as in the first embodiment. For this reason, the gold terminals 36 and 37 at the base end of the platinum power supply terminals 33 and 34 have an electric resistance equal to or less than that and have a small strength.

Using the apparatus described above, the outflow of the same heavy barium crown-based optical glass as in the first embodiment was attempted. The temperature of the glass in the melting tank 38 (1000 ° C.) and the number of rotations of the stirring rod 41 (60 rpm) are the same as in the first embodiment.

The outflow experiment was performed as follows. While detecting the temperature of the outflow pipe 31 with the thermocouple 44, the voltage of the power supply device 48 was adjusted at a heating rate of 150 ° C. per minute so that the temperature of the outflow pipe 31 became 950 ° C. At this time, although the temperature of the lower portion 31b of the outflow pipe can be measured by the thermocouple 45, it was 955 ° C., and was not lower than that of the upper portion 31a and was almost the same temperature. At this time, the length of the outflow pipe 31 becomes longer due to thermal expansion, and the height of the outflow pipe tip 32 is lowered by about 5 m.
m lower. The gold terminals 36 and 37 were deformed in response to the elongation of the outflow pipe.
No deformation was observed in both samples. The molten glass flow rate at this time was 8 g / min. It is to be noted that the flow rate of the molten glass can be changed by changing the temperature measured by the thermocouple 44, and the flow rate can be set as required, as in the first embodiment.

Next, using a mold (not shown) installed immediately below the outlet pipe tip 32, for 12 seconds,
By receiving the outflow glass 47, 1.6 g of molten glass lump was obtained. When this operation was continuously performed for 6 hours, 5 molten glass blocks were obtained per minute, and about 1800 molten glass blocks were obtained in 6 hours. With respect to the weight, 94% of the glass block was within ± 1% of 1.6 g, which was good. Striae were not observed in all the glass lumps, and the roundness (variation due to the difference in the diameter in the radial direction) was also good for all the glass lumps within ± 1% of the diameter.

Next, the temperature was lowered at a rate of 150 ° C./min until the temperature of the outflow pipe 31 became 500 ° C. or less, and the outflow of glass was stopped. Then, at room temperature (about 20-2
(5 ° C.).

For each of the above steps, in an actual experiment,
The temperature of the outflow tube was increased in the morning, and then the glass was allowed to flow out for 6 hours to obtain a glass lump. In the evening, the temperature of the outflow tube was lowered to stop the outflow of the glass. This operation was continued for about 6 months, during which time about 93% of the glass lump had good quality in weight, striae, and roundness. After the experiment for 6 months, the heat insulating material 35 was peeled off and the outflow pipe 31 was examined, but almost no deformation was observed.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. The configuration of the apparatus of the third embodiment is basically the same as that of the first embodiment with respect to a glass melting furnace 51, a glass melting tank 52, a stirring rod 53, and a heater 54. In addition, it is possible to keep the height of the molten glass liquid level 57 constant by attaching an outflow pipe 56 to the outflow port 55 of the glass melting tank or installing a glass raw material charging device (not shown). Is the same as in the first embodiment.

In the third embodiment, as shown in FIG.
Power supply terminals 58, 59 and 60, 61 are provided at symmetrical positions of the outflow pipe 56. In other words, a pair of power supply terminals are provided at axially symmetric positions with respect to the flowing direction of the glass. The power supply terminals 58 and 59 closer to the outlet 55 are welded near the base of the outflow pipe 56 and are bent in the furnace wall 62 as shown in FIG. It is designed to be pulled out to the outside. Another pair of power supply terminals 6
0 and 61 are welded to the outflow pipe tip 71, and FIG.
As shown in FIG.

The material of the outflow pipe and the power supply terminals 58, 59, 60, 61 used in the third embodiment are all 90% platinum.
A platinum alloy of rhodium 10% (Pt-Rh 10%) was used. The strength (tensile strength) of this material is about twice as strong as before adding rhodium to platinum.

The outflow pipe 56 has a thickness of 1.0 mm and an inner diameter of 3.0.
mm and a length of 800 mm, and have the same thickness from the outlet 55 of the glass melting tank to the tip 71 of the outlet pipe. A heat insulating material 63 having a thickness of 12.5 mm is wound around the outflow pipe 56 to form a heat insulating material 63. The power supply terminals 58 and 59 have a thickness of 1.4 mm and a width of 10 m.
m, 120 mm in length (because it is bent in a crank shape in FIG. 3, the length when it is extended) is a plate shape. The other pair of power supply terminals 60 and 61 has a thickness of 1.4 m.
m, width 10 mm, total length 50 mm.

Next, terminals 64, 65, 66, and 67 having a bent portion made of gold are connected to the base end side of the power supply terminal. In the third embodiment, the gold terminal is made to have a lower electrical resistance and a lower strength than the power supply terminal made of a platinum alloy. To explain the specific dimensions, all four gold terminals have a thickness of 0.2 mm and a width of 1
0 mm, and the length when extended was 100 mm. The thickness of the gold terminal is as thin as 1/7 that of the platinum alloy power supply terminal, but since the width is the same, the force required for bending is considerably smaller than that of the power supply terminal. Regarding the cross-sectional area, the gold terminal is 1/7 of the power supply terminal. Comparing the specific resistance, for example, at 20 ° C., 19.2 × 10 ⁻⁶ of Pt-Rh 10%
For gold, 2.2 × 10 ^-6 Ωcm is about 1 /
8.7. Accordingly, the electrical resistance of the gold terminal per unit length is smaller for the gold terminal, and it is possible to prevent the gold terminal from abnormally generating heat when energized.

An outflow of lanthanum borate-based optical glass was attempted using the apparatus described above. The glass is a specific gravity at room temperature is ^{3.8, 1100 ℃ 10 0.3 dPa ·} s 1000 10 when ^{10 1.0 10 2.8 dPa · s 817} ℃ when dPa · s 890 ° C. When the ℃ ^3.0 dPa · s 764 when It has a viscosity characteristic of 10 ^4.0 dPa · s at 654 ° C., 10 ^7.6 dPa · s at 654 ° C., and 10 ¹³ dPa · s at 579 ° C. This glass is melted in a melting tank 52
The temperature was adjusted to 1100 ° C. by melting. The stirring rod 53 is 10
It was moved at 0 rpm so that the molten glass 68 was homogenized.

The effluent experiment was performed as follows. While detecting the temperature of the outflow pipe 56 with the thermocouple 69, the voltage of the power supply device 70 was adjusted at a heating rate of 100 ° C. per minute so that the temperature of the outflow pipe 56 became 1000 ° C. At this time, the length of the outflow pipe 56 was increased due to thermal expansion, and the height of the outflow pipe tip 71 was reduced by about 8 mm downward. In response to the outflow pipe elongation,
The gold terminals 64, 65, 66, and 67 were deformed, but the platinum power supply terminals 58, 59, 60, and 61 were not deformed. The molten glass flow rate at this time was 2
It was 1 g / min. Note that, similarly to the other embodiments, the thermocouple 6
By changing the temperature measured at 9, the flow rate of the molten glass can be changed.

Next, by using a mold (not shown) installed immediately below the outlet pipe tip 71, the outflow glass 72 is received for 5.6 seconds to melt 1.96 g. A glass mass was obtained. If this operation is performed continuously for 6 hours,
In 6 hours, about 3800 molten glass ingots were obtained in total. In terms of weight, 95% of the glass block is 1.96 g
The variation was within ± 1%, which was good.
Striae were not observed in all the glass lumps, and the roundness (variation due to the difference in the diameter in the radial direction) was also good for all the glass lumps within ± 1% of the diameter.

Next, the temperature was lowered at a rate of 100 ° C./min until the temperature of the outflow pipe 56 became 580 ° C. or less, and the outflow of glass was stopped. Then, at room temperature (about 20-2
(5 ° C.).

For each of the above steps, in an actual experiment,
The temperature of the outflow tube was increased in the morning, and then the glass was allowed to flow out for 6 hours to obtain a glass lump. In the evening, the temperature of the outflow tube was lowered to stop the outflow of the glass. This operation was continued for about 6 months, during which time about 92% of the glass lump had good quality in weight, striae, and roundness. After the experiment for 6 months, the heat insulating material 63 was peeled off and the outflow pipe 56 was examined, but almost no deformation was observed.

Next, an experiment was performed in which the heating rate and the cooling rate of the outlet pipe 56 were changed. The rate of temperature rise and fall of the outlet pipe 56 was set at 100 ° C./min in the above-mentioned experiment, but the rate of temperature rise and fall was 200 ° C./min and 400 ° C./min.
An experiment was conducted to increase the speed to 600 ° C./min.

As a result, in the case of the apparatus used in the third embodiment, in order to obtain a good quality glass lump and not to deform the outflow pipe for at least 6 months or more, the heating rate and the cooling rate are set to be equal. In any case, it was found that 400 ° C./min or less was sufficient. In the case of 600 ° C./min, after about one month from the start of the experiment, the outflow pipe starts to bend and the flow rate of the glass changes, and the weight of the glass lump obtained in the molding die for a certain period of time fluctuates. Deterioration of roundness and striae of glass ingots have been observed.

The apparatus used in the third embodiment, that is, the apparatus in which a pair of power supply terminals are installed at a position axially symmetrical with respect to the outflow pipe (with the glass flowing direction as an axis) when installing the power supply terminal, As compared with the device used in the first and second embodiments, that is, the device in which the power supply terminal is provided only on one side of the outflow pipe, the temperature of the outflow pipe can be raised or lowered at a higher temperature. On the other hand, in the device used in the third embodiment, a large number of power supply terminals are provided, and accordingly, an amount of platinum or a platinum alloy is required. Therefore, the type of the third embodiment or the types of the first and second embodiments may be selected according to the situation.

Comparative Example 2 For comparison, a comparative experiment was performed using a conventional device (not shown) not using a gold terminal. In this experiment, the configuration and dimensions of the apparatus, the type of glass, the set temperature conditions of the outflow pipe, and the like are all the same as those of the third embodiment except that the gold terminals are not used.
In this case, the outflow tube was heated at a rate of 100 ° C./min in the morning, and then the glass was discharged for 6 hours to obtain a glass lump,
In the evening, if the operation of lowering the temperature of the outflow pipe at 100 ° C./min and stopping the outflow of the glass is repeated every day in the same manner as in the third embodiment, the outflow pipe will bend after only about one month has elapsed. For the first time, the glass flow rate changed, and-the weight fluctuation of the glass lump obtained by the fixed-time molding die, the deterioration of roundness, and the occurrence of striae were observed.

As described above, when the power supply terminal made of platinum or a platinum alloy is installed, the power supply terminal is installed at an axially symmetrical position with respect to the outflow pipe (the direction in which the glass flows is the axis). The gold terminal connected to the base end of
At the same time as having the bent portion, the electric resistance was equal to or less than that of the power supply terminal made of platinum or a platinum alloy, and the strength was reduced. As a result, even if the temperature of the outflow pipe is raised and lowered relatively quickly, the force applied to the outflow pipe is reduced by deforming the gold terminal in accordance with the change in the length of the outflow pipe due to thermal expansion and contraction. Can be prevented. Therefore, even if the temperature of the outflow pipe is raised and lowered relatively quickly, the outflow pipe does not bend or the outflow pipe cross-section does not collapse.

As a result, even if the temperature of the outflow pipe is raised and lowered relatively quickly, the molten glass ingot having a small weight fluctuation, a good shape, and a good optical quality without striae over a long period of time into a molding die or the like. It becomes possible to provide a molten glass flow rate adjusting device for supplying.

As described above, according to the above embodiment, (1) a platinum or platinum alloy power supply terminal is connected to a molten glass outflow pipe made of platinum or a platinum alloy, and Gold terminals were connected to the ends. At the same time as the gold terminal has the bent portion, the electric resistance is equal to or less than that of the power supply terminal made of platinum or platinum alloy, and the strength is reduced. As a result, even if the temperature of the outflow pipe is raised or lowered and the length of the outflow pipe changes due to thermal expansion / contraction, it is possible to prevent the force from being applied to the outflow pipe due to the deformation of the gold terminal. Therefore, even if the temperature of the outflow pipe is repeatedly raised and lowered, the outflow pipe does not become curved or the outflow pipe cross-sectional shape does not collapse.

As a result, it is possible to provide a molten glass flow rate adjusting device for supplying a molten glass lump having a small weight variation, a good shape, and a good optical quality without striae to a molding die or the like over a long period of time. Become (2) A power supply terminal made of platinum or a platinum alloy is installed in a molten glass outflow pipe made of platinum or a platinum alloy at an axially symmetric position with respect to the flowing direction of glass as an axis. Gold terminals were connected. At the same time as the gold terminal has the bent portion, the electric resistance is equal to or less than that of the power supply terminal made of platinum or platinum alloy, and the strength is reduced. As a result, even if the temperature of the outflow pipe is raised and lowered relatively quickly and the length of the outflow pipe changes due to thermal expansion and contraction, it is possible to prevent the force from being applied to the outflow pipe by deforming the gold terminal. Become. Therefore, even if the temperature of the outflow pipe is raised and lowered relatively quickly, the outflow pipe does not bend or the outflow pipe cross-section does not collapse.

As a result, even if the temperature of the outflow pipe is raised and lowered relatively quickly, a molten glass lump having a small weight change, a good shape, and a good optical quality without striae over a long period of time into a molding die or the like. It becomes possible to provide a molten glass flow rate adjusting device for supplying.

[0069]

As described above, according to the present invention, a molten glass lump having a small weight fluctuation, a good shape, and a good optical quality without striae is supplied to a molding die or the like over a long period of time. There is provided an apparatus for controlling the flow rate of molten glass.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a second embodiment of the present invention.

FIG. 3 is a diagram for explaining a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional example.

FIG. 5 is an explanatory diagram of a conventional example.

FIG. 6 is a view showing deformation of an outflow pipe when glass is discharged based on the conventional apparatus shown in FIG.

FIG. 7 is a view showing a deformation of the outflow pipe when the glass flows out based on the conventional apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass melting tank 2 Outflow port 3 Outflow pipe 4 Glass melting furnace 5 Furnace atmosphere 6 Heater 7 Molten glass 8 Stirrer rod 9 Molten glass liquid level 10 Heat insulation material 11 Power supply terminal 12 Power supply terminal 13 Gold terminal 14 Gold terminal 15 Electric wire Reference Signs List 16 power supply device 17 thermocouple 18 molten glass 19 outflow pipe tip 20 outflow glass 31 outflow pipe 31a upper part of outflow pipe 31b lower part of outflow pipe 32 outflow pipe tip 33 power supply terminal 34 power supply terminal 35 heat insulator 36 gold Terminal 37 Gold terminal 38 Glass melting tank 39 Glass melting furnace 40 Heater 41 Stirrer rod 42 Melted glass 43 Outflow port 44 Thermocouple 45 Thermocouple 46 Molten glass 47 Outflow glass 48 Power supply device 49 Molten glass liquid level 51 Glass melting furnace 52 Glass Melting tank 53 Stirrer rod 54 Heater 55 Outlet 56 Outflow pipe 57 Melting gas Liquid surface 58 Power supply terminal 59 Power supply terminal 60 Power supply terminal 61 Power supply terminal 62 Furnace wall 63 Insulation material 64 Gold terminal 65 Gold terminal 66 Gold terminal 67 Gold terminal 68 Molten glass 69 Thermocouple 70 Power supply device 71 Outflow pipe tip Part 72 outflow glass 101 glass melting tank 102 outflow port 103 outflow pipe 104 heat insulator 105 power supply terminal 106 power supply terminal 107 power supply device 108 molten glass 109 thermocouple 110 molten glass 111 outflow pipe 111a upper part of outflow pipe 111b lower side of outflow pipe Part 112 Insulation material 113 Power supply terminal 114 Power supply terminal 115 Power supply device 116 Outflow pipe tip part 117 Thermocouple 118 Thermocouple 119 Fused glass 121 Outflow pipe middle part 122 Insulation material 123 Outflow pipe tip part 124 Outflow pipe middle part 125 Insulation material 126 Outflow Tube tip

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Kubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masayuki Tomita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (2)

[Claims] 1. An outflow pipe made of platinum or a platinum alloy attached to an outlet of a glass melting tank, and a platinum or platinum alloy connected to the outflow pipe for applying a DC or AC voltage to the outflow pipe. A power supply device for supplying power to the power supply terminal, a terminal having a bent portion made of gold is connected to a base end side of the power supply terminal, and the gold terminal is platinum or An apparatus for controlling the flow rate of molten glass, characterized in that the electric resistance is equal and the strength is small as compared with the power supply terminal made of a platinum alloy. 2. An outflow pipe made of platinum or a platinum alloy attached to an outlet of a glass melting tank, and a platinum or platinum alloy connected to the outflow pipe for applying a DC or AC voltage to the outflow pipe. And a power supply device for supplying power to the power supply terminal, wherein the power supply terminal is installed at an axially symmetric position of the outflow pipe with respect to a flowing direction of the glass as an axis, and a base end of the power supply terminal. A terminal having a bent portion made of gold is connected to the side, and the gold terminal has the same electrical resistance and lower strength than the power supply terminal made of platinum or a platinum alloy. Flow control device for molten glass.