JPH06340429A - Fused glass outflow device - Google Patents

Abstract

PURPOSE:To easily prevent the regeneration of devitrification and foam and to improve a temp. distribution by successively providing the front end side of the nozzle part of a prescribed device with a heat insulating cylinder having the inside diameter larger than the inside diameter of the nozzle part and providing the nozzle part and the heat insulating cylinder with electrodes for electrical heating. CONSTITUTION:A platinum pipe 1 made of platinum (alloy), an outflow nozzle 3, a juncture 3, the heat insulating cylinder 4, energizing rings 5a, 6a and the electrodes 5, 6 are disposed. The inside diameters of the pipe 1 and the nozzle 2 are set at about 6mm and the outside diameters thereof at about 8mm. The heat insulating cylinder 4 is finished to about 10mm inside diameter and about 11.3mm outside diameter. The respective sectional areas for the flow direction of currents are made the same. The juncture 3 is formed as a plate of about 0.8mm thickness, thinner than the thickness of the nozzle 2 so that the temp. near the nozzle 2 is kept highest and falls gradually nearer the heat insulating cylinder 4 when the juncture is energized from a power source 12, by which the fused glass outflow device is produced. The pipe 1 and the nozzle 2 are then heated by regulating the power sources 11, 12, by which the glass flow 21 is made to flow out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a pipe-shaped nozzle for flowing glass melted in a melting furnace from a melting furnace to a mold outside the furnace in a glass product manufacturing process such as optical elements. And a molten glass outflow device.

[0002]

2. Description of the Related Art Conventionally, since the tip of a nozzle through which glass flows out is cooled by contact with the outside atmosphere, the nozzle tip has been heated by a burner or the like so that the nozzle can be smoothly discharged. As one example thereof, Japanese Patent Laid-Open No. 62-270427 discloses a technique of covering the tip of the nozzle with a heater for heating the nozzle so that the glass flows out. In addition,
No. 74 discloses a technique of increasing the electric resistance value of the lower part of the outflow platinum pipe to be larger than that of the upper part and applying a voltage to the pipe to prevent the temperature drop at the tip of the pipe. There is.

However, since the method of heating the nozzle tip with a burner or a heater as in the above-mentioned conventional example uses indirect heating, problems in temperature response and accuracy with respect to the nozzle tip are likely to occur. Further, since a burner, a heater, etc. are arranged near the tip of the nozzle, there are problems that it is difficult to secure a working space for a press or the like performed below the nozzle, and the apparatus itself becomes complicated. Also, a method of preventing the temperature drop at the tip of the pipe by increasing the electric resistance value of the lower part of the outflow platinum pipe disclosed in the conventional example to be larger than that of the upper part and applying a voltage to the pipe. In this case, regarding the temperature of the glass outlet at the tip of the pipe, the contact area with the outside air increases and the electrode for energization is placed in this part, so the temperature of the lower part of the pipe is It will be lower than the comparison. Therefore, the glass is devitrified (crystallized) at the glass outlet at the tip of the pipe.
And deteriorate the quality of the glass that has flowed out. Conversely, if the temperature at the glass outlet is raised to prevent devitrification, the temperature at the top of the pipe will rise too high and bubbles will be regenerated in the glass. There is a problem that the difference becomes large and it is difficult to obtain a glass flow with a small temperature distribution. When cutting the glass flow with a cutting blade to obtain a necessary mass of glass like ordinary press molding, such a temperature difference between the outer peripheral portion and the inner portion of the outflowing glass does not become a problem. . However, when the glass flow is cut by the surface tension of the glass by dropping the glass from the outlet or changing the descending speed of the glass flow, if there is no difference in temperature between the outer peripheral portion of the outflowing glass and the inside, Due to the surface tension of the glass flow, the glass flow can be cut without leaving any defects on the cut surface, but if this temperature difference is large, the glass at the cutting part will be stretched into a thread at the time of cutting, and it will adhere to the cutting cross section, There is a problem that defects are left in the glass by being caught again in the cut portion.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the temperature in the vicinity of the nozzle, especially the glass outlet, and to provide a simple apparatus. An object of the present invention is to provide a molten glass outflow device capable of obtaining a glass flow having no temperature distribution with a configuration.

[0005]

In order to achieve the above object, the present invention provides a pipe-shaped molten glass in which a nozzle portion is formed at one end and the other end is connected to a glass melting furnace to take out the molten glass in the furnace. In the outflow device, a heat retaining tube having an inner diameter larger than the inner diameter of the nozzle portion is continuously provided on the tip side of the nozzle portion, and an electric heating electrode is provided on the nozzle portion and the heat retaining tube. And / or forming the wall thickness of the connecting portion connecting the tip end side of the nozzle portion and the heat insulating cylinder smaller than the wall thickness of the nozzle portion, the nozzle portion being made of platinum or a platinum alloy, and the nozzle portion. Heating the heat retaining tube with a single direct current flow.

[0006]

Embodiments of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a first embodiment of the molten glass outflow apparatus of the present invention. In FIG. 1, 1 is a platinum pipe connected to a melting furnace (not shown). 1
An outflow nozzle 2 which serves as a glass outflow portion is connected to the lower part. Reference numeral 4 denotes a heat-retaining cylinder connected to the outflow nozzle 2 by the connecting portion 3, and the inner diameter thereof is formed to be larger than the inner diameter of the outflow nozzle 2, whereby the glass 21 abruptly flowed out from the tip of the nozzle 2. It prevents temperature drop.

Energizing rings 5a, 6 for preventing a local increase in the current density when electricity is energized at one end of the platinum pipe 1 and the connecting portion of the outflow nozzle 2 and at the tip of the heat insulating cylinder 4.
a is provided, and the energization rings 5a and 6a are further provided with electrodes 5 and 6, respectively. Reference numeral 11 denotes a power source for heating the platinum pipe 1, one of the power sources is connected to the electrode 5 via the lead wire 14, and the other one is similarly connected via the lead wire 13 to the platinum pipe 1 not shown.
Is connected to the electrode provided on the other end side (upper part) of
By adjusting the electric power of the power supply 11, the temperature of the platinum pipe can be arbitrarily controlled. Similarly, reference numeral 12 is a power source for heating the outflow nozzle 2, the connecting portion 3, and the heat insulating cylinder 4, and is connected to the electrodes 5 and 6 through the lead wires 15 and 16, respectively. Reference numeral 17 is a heat insulating material for reducing the influence of disturbance and enhancing heating and soaking effects, and covers the platinum pipe 1 and the outflow nozzle 2 as shown in the figure.

A platinum pipe 1, an outflow nozzle 2, a connecting portion 3,
The heat insulating cylinder 4, the energizing rings 5a and 6a, and the electrodes 5 and 6 are all made of platinum or a platinum alloy, and the pipe 1 and the nozzle 2 are finished to have an inner diameter of 6 mm and an outer diameter of 8 mm. The heat insulating cylinder 4 is finished to have an inner diameter of 10 mm and an outer diameter of 11.3 mm, and the cross-sectional areas in the current flow direction are substantially the same. The connecting portion 3 is made of a 0.8 mm-thick plate and is thinner than the nozzle 2 and has a highest temperature in the vicinity of the nozzle 2 when an electric current is supplied from the power supply 12 and keeps it warm. The structure is such that the temperature gradually decreases as it approaches the cylinder 4.

First, by using the outflow device having the above structure, the power source 1
Control 1 and set pipe 1 to 1050 ° C,
Furthermore, the power supply 12 was adjusted and the nozzle 2 was set to 1040 degreeC. In this state, at 950 ° C, 30 Pa · s, 104
10Pa ・ s at 0 ℃, 5Pa ・ at 1135 ℃
When the glass showing the viscosity characteristic of s was discharged, the nozzle 2
A stable glass flow 21 having a central temperature of 1045 ° C. and an outer peripheral temperature of 1035 ° C. was obtained 15 mm below the outlet at the lower end of the. Further, the nozzle 2 of the connecting portion 3 at that time
The temperature near 10 ° C. was 1045 ° C., and the temperature of the heat insulating cylinder 4 was 950 ° C. (Second Embodiment) A second embodiment will be described with reference to FIG. This embodiment has the same configuration as that of the first embodiment except that a groove-shaped outflow heating portion 2a is formed by cutting out along the outer periphery of the nozzle 2 on the tip side.

Similar to the first embodiment, the platinum pipe 1, the outflow nozzle 2, the outflow heating part 2a, the connecting part 3, the heat retaining tube 4, the energizing rings 5a and 6a, and the electrodes 5 and 6 are all made of platinum or a platinum alloy. The pipe 1 and the nozzle 2 have an inner diameter of 6 mm and an outer diameter of 8 mm. Inner diameter φ10
mm, the outer diameter φ10.8 mm, and the current density was increased by about 20% as compared with the nozzle 2. Heating part 2
a has an inner diameter of 6 mm and an outer diameter of 7.6 mm so that the current density is slightly less than 30% larger than that of the nozzle 2, and the connecting portion 3 is made of the same 0.8 mm thick plate as the heating portion 2a. .

In the same manner as in Example 1, the power source 11 was controlled and the pipe 1 was set at 1050 ° C. Further power 12
Was adjusted to set the nozzle 2 to 1040 ° C. and the same glass as that used in Example 1 was allowed to flow out.
The temperature of the central part and the outer part is the same at 5mm below 1045
A stable glass flow of 21 ° C. was obtained. At that time, the temperature of the heating part 2a was 1055 ° C., the temperature of the connection part 3 near the nozzle 2 was 1050 ° C., and the temperature of the heat retaining cylinder 4 was 1000 ° C. (Third Embodiment) A third embodiment will be described with reference to FIG.

The apparatus is constructed so that the connecting portion 3 is eliminated and the nozzle 2 is folded through the folded portion 7 which is once folded upward as shown in the figure.
The configuration was the same as that of Example 1 except that the tip end side and the heat insulating cylinder 4 were connected.

Similar to the first embodiment, the platinum pipe 1, the outflow nozzle 2, the folded portion 7, the heat retaining cylinder 4, the current-carrying rings 5a and 6 are used.
a, the electrodes 5 and 6 are all made of platinum or a platinum alloy, and the pipe 1 and the nozzle 2 have an inner diameter of 6 mm and an outer diameter of 8 m.
It is finished in m. The heat-retaining cylinder 4 is finished to have an inner diameter of 12 mm and an outer diameter of 13.1 mm, and the cross-sectional areas in the current flow direction are substantially the same. The folded-back portion 7 had an inner diameter of 9.5 mm and an outer diameter of 10.7 mm so that the current density was slightly less than 20% larger than that of the nozzle 2.

Similar to the first embodiment, the power source 11 is controlled, the pipe 1 is set to 1050 ° C., and the power source 12 is used.
Was adjusted and the nozzle 2 was set to 1040 ° C. Example 1
When the same glass as that used in Example 1 was allowed to flow out, a stable glass flow 21 having a central temperature of 1045 ° C. and an outer peripheral temperature of 1040 ° C. was obtained at a position 15 mm below the outlet. At that time, the temperature of the folded portion 7 is 1060 ° C,
The temperature of the heat insulating cylinder 4 was 950 ° C. (Fourth Embodiment) A fourth embodiment will be described with reference to FIG.

The apparatus configuration is the same as that of the third embodiment except that an outflow heating section 2a having a smaller outer diameter than the upper portion of the nozzle 2 is provided at the tip of the nozzle 2.

As in the third embodiment, the platinum pipe 1, the outflow nozzle 2, the outflow heating section 2a, the folded section 7, the heat retaining tube 4, the energizing rings 5a and 6a, and the electrodes 5 and 6 are all made of platinum or a platinum alloy. ing. Inner diameter of pipe 1 and nozzle 2 is φ6m
m, the outer diameter was φ8 mm, and the heat insulating cylinder 4 was finished to have an inner diameter of φ12 mm and an outer diameter of φ12.9 mm so that the current density was about 2.5% larger than that of the nozzle 2. Similarly, the folded-back portion 7 has an inner diameter of 9.5 mm and an outer diameter of 1
It was set to 0.7 mm so that the current density was slightly less than 20% larger than that of the nozzle 2. Further, the heating portion 2a has an inner diameter of φ6.
mm and outer diameter φ7.7 mm so that the current density is 20% larger than that of the nozzle 2.

Similar to the third embodiment, the power source 11 is controlled, the pipe 1 is set to 1050 ° C., and the power source 12
Was adjusted and the nozzle 2 was set to 1040 ° C. Example 1
When the same glass as that used for was flowed out, the temperature of the central part and the outer peripheral part was 1045 at 15 mm below the outlet.
A stable glass flow of 21 ° C. was obtained. At that time, the temperature of the heating part 2a is 1055 ° C., and the temperature of the folding part 7 is 1
The temperature was 065 ° C., and the temperature of the heat insulating cylinder 4 was 950 ° C.

[0018]

As described above, according to the present invention, a heat retaining portion is further provided at the tip of the glass outlet, and the temperature of the outlet or between the heat retaining portion and the outlet is raised above the temperature of the entire outflow nozzle. By keeping heat and heating, unnecessary heating, devitrification due to cooling, re-generation of bubbles can be prevented, and a very effective temperature-balanced outflow glass flow can be obtained for cutting a glass flow without using a cutting blade. You can

[Brief description of drawings]

FIG. 1 is a partially omitted view showing a first embodiment of the present invention.

FIG. 2 is a partially omitted view showing a second embodiment of the present invention.

FIG. 3 is a partially omitted view showing a third embodiment of the present invention.

FIG. 4 is a partially omitted view showing a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platinum pipe 2 Outflow nozzle 2a Outflow heating part 3 Connection part 4 Insulating cylinder 5,6 Electrode 5a, 6a Energizing ring 7 Folding part 17 Insulating material 21 Outflow glass

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mizukazu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A pipe-shaped molten glass outflow device having a nozzle portion formed at one end and the other end connected to a glass melting furnace to take out molten glass in the furnace, wherein the inner diameter is closer to the tip end side of the nozzle portion than the inner diameter of the nozzle portion. In addition to connecting a large-diameter heat insulation tube,
A molten glass outflow device, characterized in that an electric heating electrode is provided on the nozzle portion and the heat retaining cylinder. 2. The outflow device according to claim 1, wherein a thickness of a tip end side of the nozzle portion and / or a connecting portion connecting the tip end side of the nozzle portion and the heat insulating cylinder is smaller than a thickness of the nozzle portion. 3. The outflow device according to claim 1, wherein the nozzle portion is made of platinum or a platinum alloy. 4. The outflow device according to claim 1, wherein the nozzle portion and the heat insulating cylinder are heated by a single direct energization.