JP2015063436A - Glass outflow device, glass outflow method, method for manufacturing glass molding and method for manufacturing optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for flowing out a molten glass material having volatility from a pipe to manufacture a preform, capable of preventing a stria from occurring in the preform.SOLUTION: A glass outflow device 1 for flowing out a molten glass comprises: an outflow pipe 4 extended in a vertical direction and flowing out the molten glass; an induction heating coil 6 provided on the outer peripheral side of the outflow pipe 4; and a loop member 14 provided so as to surround the outside of the outflow pipe 4 in a horizontal view and consisting of a closed loop shaped conductor allowing induction heating by the induction heating coil 6.

Description

  The present invention relates to a glass outflow device, a glass outflow method, a glass molded product manufacturing method, and an optical element manufacturing method, and in particular, a glass outflow device, a glass outflow method for manufacturing a glass molded product such as a preform, The present invention relates to a method for producing a glass molded article and a method for producing an optical element.

  Conventionally, as a method for producing a glass optical element such as a lens, a method is used in which a preform having a shape similar to the optical element is molded, and this preform is heated and press-molded. As a manufacturing method of the preform used in this method, the glass melted in the crucible is caused to flow out of the outflow pipe by a glass outflow device, dropped onto the forming die (cast), and molded and cooled on the forming die. The method is widely used (for example, see Patent Documents 1 to 4).

  FIG. 4 is a vertical sectional view showing a configuration of an example of a glass outflow apparatus conventionally used for manufacturing a preform. As shown in the figure, a conventionally used glass spill device 101 is composed of an spill pipe 104 disposed in a casing 102, an induction heating coil 106 disposed outside the casing 102, and an inert gas. An outer channel member 108 and an inner channel member 110 that define the gas channel 112 are provided. When a preform is manufactured using such an apparatus, the molten glass supplied from the glass melting apparatus 120 flows out of the outflow pipe 104 and is dropped onto the forming die 116. At this time, in order to isolate the molten glass from the outside air, an inert gas is blown from the gas flow path 112 to the tip of the outflow pipe 104, and the outflow pipe 104 is heated by the induction heating coil 106 so that the temperature of the molten glass does not decrease. To do.

In the apparatus described in Patent Document 1, as shown in FIG. 1B of Patent Document 1, the periphery of the outflow pipe is surrounded by a quartz glass cover, and the periphery of the mold is also surrounded by the cover, and the molten glass flows out. The atmosphere in the molding space can be controlled.
In the apparatus described in Patent Document 2, as shown in FIG. 2 of Patent Document 2, a nozzle cover is provided around the nozzle that flows out of the molten glass, and gas is allowed to flow downward between the nozzle and the nozzle cover. A downward wind pressure is applied to the molten glass that appears at the tip of the nozzle to allow dripping of a molten glass droplet that is lighter than the weight that naturally drops.
In the apparatus described in Patent Document 3, in order to suppress the wetting of the molten glass on the outer periphery of the outflow pipe, as shown in FIG. It has become.
The apparatus described in Patent Document 4 has a structure in which gas is blown to promote cooling of the surface of the molten glass in order to suppress volatilization from the molten glass flowing out.

JP 2006-232584 A JP 2002-121032 A JP 2003-026424 A JP 2006-248873 A

  In recent years, glass materials that are volatile in a molten state have been used as glass materials. Among these, fluorophosphate glass, boric acid-containing glass, alkali metal-containing glass, and the like exhibit high volatility in the molten state. In the case where preforms are continuously produced from such volatile molten glass using the glass outflow device described above, striations occur suddenly in the preforms if the production time is extended for a long time. There arises a problem that the quality of the reform is deteriorated.

  The present invention has been made in view of the above problems, and a glass outflow device, a glass outflow method, and a glass molded product manufacturing method capable of stably producing a high-quality glass molded product by causing molten glass to flow out of a pipe. And to provide a method for producing an optical element using the glass molded article produced by the above method.

  As a result of trial and error, the applicants of the present application have found that the occurrence of striae in the preform is caused by the volatile matter generated from the molten glass adhering to the outer periphery of the pipe, and this adhering matter is mixed into the molten glass flowing out of the pipe as a foreign substance It was found that this was the cause.

  The glass outflow device of the present invention is based on the above-mentioned knowledge of the applicants, and is a glass outflow device for outflowing molten glass, which extends in the vertical direction and flows out of the molten glass, and the outer peripheral side of the pipe And a loop member made of a closed loop conductor that is provided so as to surround the outside of the pipe in a horizontal view and can be induction-heated by the induction heating coil.

  Further, the glass outflow method of the present invention is a method of outflowing molten glass, and an induction heating coil is provided on the outer peripheral side of a pipe through which molten glass flows out, and a closed loop conductive material that can be induction heated by the induction heating coil. A loop member made of a body is provided so as to surround the outside of the pipe in a horizontal view, and the molten glass flows out from the pipe while induction heating the loop member by an induction heating coil.

  Moreover, the manufacturing method of the glass molded product of this invention flows out and shape | molds molten glass with said glass outflow method.

  The optical element manufacturing method of the present invention includes a step of manufacturing a press molding preform by flowing out molten glass by the glass outflow method, a step of heating the preform, and pressing the heated preform. Forming.

  According to this invention of the said structure, since the loop member is arrange | positioned on the outer periphery of the outflow pipe, molten glass can be flowed out from an outflow pipe, heating this loop member with an induction heating coil. As a result, the periphery of the outflow pipe can be kept at a high temperature, volatiles generated from the molten glass can be prevented from adhering to the lower end of the outflow pipe, and striae can be prevented from suddenly occurring in the preform. be able to.

According to the glass outflow device of the present invention, it is possible to provide a glass outflow device that can stably produce a high-quality glass molded product from molten glass.
Moreover, according to the glass outflow method of this invention, the glass outflow method for producing stably a high quality glass molded product from molten glass can be provided.
Moreover, according to the manufacturing method of the glass molded product of this invention, the manufacturing method of the glass molded product which can manufacture a high quality glass molded product stably from molten glass can be provided.
Furthermore, according to the method for manufacturing an optical element of the present invention, it is possible to provide an optical element manufacturing method capable of stably manufacturing a high-quality optical element through a preform from molten glass.

It is a vertical sectional view showing the composition of the glass outflow device of a 1st embodiment. It is a vertical sectional view showing the glass outflow device of a 2nd embodiment, and the circumference of an outflow pipe is expanded and shown. It is a vertical sectional view showing a glass outflow device of a 3rd embodiment, and the circumference of an outflow pipe is expanded and shown.

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a vertical cross-sectional view showing the configuration of the glass outflow device of the present embodiment. The glass outflow apparatus 1 of this embodiment is an apparatus which manufactures the preform which is a glass molded article by supplying the molten glass heated and melt | dissolved in the melting furnace, and dripping the supplied molten glass.

  As shown in FIG. 1, the glass outflow device 1 includes a casing 2 formed in a cylindrical shape, an outflow pipe 4 disposed in the center of the casing 2, an induction heating coil 6 disposed outside the casing 2, The outer flow path member 8 and the inner flow path member 10 which define the gas flow path 12 which blows inactive gas, and the loop member 14 arrange | positioned in the gas flow path 12 are provided. Further, below the outflow pipe 4 of the glass outflow device 1, a forming die 16 supported by the lifting device 22 is disposed. In addition, the manufacturing apparatus of the glass molded product of this invention is comprised including the glass outflow apparatus 1 and the shaping | molding die 16. FIG.

  The casing 2 is a member formed in a cylindrical shape, and is made of, for example, a non-conductive material with low heat conductivity such as quartz. The casing 2 forms an airtight space in the interior together with the mold side casing 18.

  The outflow pipe 4 is connected to the glass melting apparatus 20, and molten glass is supplied from the glass melting apparatus 20. The outflow pipe 4 is made of a conductor material that is resistant to corrosion, such as platinum. The inner diameter of the lower end portion of the outflow pipe 4 is a predetermined diameter corresponding to the size of the preform to be manufactured. The outflow pipe 4 casts the molten glass supplied from the glass melting apparatus 20 onto the mold 16.

  The induction heating coil 6 is a member made of a conductor formed in a coil shape, and is connected to a power source (not shown). When a current flows from the power source to the induction heating coil 6, a magnetic field is generated inside the induction heating coil 6. Thereby, an eddy current due to electromagnetic induction can be generated in the conductor disposed inside the induction heating coil 6, and the conductor can be heated by the electric resistance of the conductor.

  The outer flow path member 8 and the inner flow path member 10 are made of, for example, a non-conductive material such as quartz formed in a cylindrical shape. The inner flow path member 10 is disposed in the outer flow path member 8 so that the central axis is coaxial. In addition, a gas flow path 12 having an annular horizontal section is defined between the inner flow path member 10 and the outer flow path member 8 so as to surround the outflow pipe 4. For example, an inert gas such as nitrogen gas is supplied to the gas flow path 12 from an external gas source. The lower end of the outer flow path member 8 is inclined toward the center. Thereby, the inert gas supplied from the gas flow path 12 is sprayed toward the tip of the outflow pipe 4.

The loop member 14 is a closed loop member made of a conductor, and is disposed in the gas flow path 12 so as to surround the outside of the outflow pipe 4 in a horizontal view. As the conductor constituting the loop member 14, a material such as a noble metal or a noble metal alloy such as platinum is suitable so that it can resist corrosion caused by volatile gas volatilized from the molten glass. The loop member 14 has a wave shape that swings in the vertical direction so that the entire length becomes a desired length. In this way, by making the entire length of the loop member 14 longer, it is possible to prevent the loop member 14 from becoming too hot and breaking.
The molding die 16 is supported by an elevating device 22 and can be moved up and down by the elevating device 22.

Hereinafter, a method for producing a preform using the glass outflow device 1 will be described.
When manufacturing the preform, first, the glass material is melted by the glass melting device 20. In the present embodiment, the glass material is a highly volatile glass material such as fluorophosphate glass, boric acid-containing glass, or alkali metal-containing glass. The molten glass material is supplied to the outflow pipe 4.
In parallel with this, a high-frequency alternating current is supplied to the induction heating coil 6. Thereby, the outflow pipe 4 and the loop member 14 are heated by electromagnetic induction by the induction heating coil 6.

  Then, the molten glass is caused to flow out from the lower end of the outflow pipe 4 while heating the outflow pipe 4 and the loop member 14 by the induction heating coil 6. At this time, the inert gas is injected toward the outflow pipe 4 through the gas flow path 12. Since the loop member 14 is provided in the gas flow path 12, the inert gas is blown toward the outflow pipe 4 while being heated to a high temperature by the loop member 14. By blowing high temperature gas onto the outflow pipe 4 in this way, volatile substances drifting around the outflow pipe 4 can be blown off. Further, when the temperature of the outer peripheral surface of the outflow pipe 4 is lowered, volatiles are likely to adhere to the outer peripheral surface, but by blowing high temperature gas, the temperature of the outer peripheral surface of the outflow pipe 4 is maintained at a high temperature. , Volatiles are less likely to adhere. Further, when the temperature of the outflow pipe 4 is lowered, the outflow amount of the molten glass is changed, so that the mass of one preform fluctuates or the molten glass is easily crystallized. The occurrence of such problems can be avoided by increasing the temperature of the gas blown to the nozzle.

  The molten glass flowing out from the lower end of the outflow pipe 4 stays on the mold 16. After the molten glass staying on the mold 16 reaches a predetermined amount, the mold 16 is rapidly lowered by the lifting device 22 to separate the molten glass on the mold 16 from the outflow pipe 4. A preform can be produced by forming the separated molten glass gob into a predetermined shape and solidifying.

  The preform thus formed is molded into an optical element such as a lens. As a method for molding into an optical element, a precision press molding method can be exemplified. In an example of the precision press molding method, first, a preform is heated and softened in a state of being accommodated in a mold, and then pressed by the mold. Thereby, an optical element having a shape corresponding to the mold is obtained.

  According to the present embodiment, the loop member 14 is disposed on the outer periphery of the outflow pipe 4, and the molten glass is caused to flow out from the outflow pipe 4 while the loop member 14 is heated by the induction heating coil 6. Thereby, the circumference | surroundings of the outflow pipe 4 can be maintained at high temperature, and it can prevent that the volatile matter generated from the molten glass adheres to the lower end of the outflow pipe 4. Thereby, it is possible to prevent sudden striae of the preform.

  Moreover, since the temperature of the molten glass which flows in the outflow pipe 4 will rise and a viscosity will fall when the temperature of the outflow pipe 4 itself is made too high, appropriate outflow conditions cannot be maintained. On the other hand, in this embodiment, since the periphery of the outflow pipe 4 is maintained at a high temperature by the loop member 14, volatiles generated from the molten glass are not generated in the outflow pipe 4 without increasing the temperature of the molten glass. It can prevent adhering to the lower end.

  The induction heating coil 6 is also provided in the conventional glass outflow device. For this reason, the conventional glass outflow apparatus can be easily changed to the glass outflow apparatus 1 of this embodiment only by incorporating the loop member 14.

  Moreover, according to this embodiment, since the loop member 14 is provided in the gas flow path 12, the inert gas sprayed on the outflow pipe 4 can be heated. Thereby, it can prevent that the volatile matter which generate | occur | produced from the molten glass adhered to the lower end of the outflow pipe 4 more reliably.

  Further, according to the present embodiment, the loop member 14 has a wave shape that swings in the vertical direction. Thereby, the full length of the loop member 14 can be changed and the temperature at the time of the heating of the loop member 14 can be adjusted. For this reason, it is possible to prevent the loop member 14 from being broken by excessive heating.

  In the present embodiment, the loop member 14 is provided in the gas flow path 12, but the position where the loop member is provided is not limited to this as long as it is around the outflow pipe 4.

  FIG. 2 is a vertical cross-sectional view showing a glass outflow device according to a second embodiment of the present invention, and shows the periphery of the outflow pipe 4 in an enlarged manner. In the present embodiment, the position and shape of the loop member 34 and the lower end position of the outer flow path member 30 are different from those of the first embodiment, but the other configurations are the same. In the present embodiment, components having the same functions and configurations as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  As shown in FIG. 2, in this embodiment, the outer flow path member 30 made of quartz extends until the lower end is positioned slightly lower than the lower end of the outflow pipe 4. An inclined portion 30 </ b> A that is inclined inward is formed at the lower end of the outer flow path member 30. In the present embodiment, the loop member 34 is formed in an annular shape, and is held at substantially the same height as the lower end of the outflow pipe 4 by the inclined portion 30 </ b> A of the outer flow path member 30.

  When the outflow pipe 4 is heated by the induction heating coil 6, the amount of heat released from the coil end is larger than that near the center of the coil, so that the lower end of the outflow pipe 4 has a lower temperature than the center. For this reason, the volatile matter generated from the molten glass may adhere to the lower end portion of the outflow pipe 4.

  On the other hand, in this embodiment, since the loop member 34 is disposed at substantially the same height as the lower end of the outflow pipe 4, the lower end of the outflow pipe 4 is heated by heating the loop member 34 with the induction heating coil 6. Can be effectively heated. Furthermore, since the outer flow path member 30 made of quartz extends until the lower end is positioned slightly lower than the lower end of the outflow pipe 4, the tip of the outflow pipe 4 is kept warm by the outer flow path member 30. .

  As described above, according to the second embodiment, the lower end of the outflow pipe 4 can be effectively heated and further kept warm.

  In addition, when manufacturing a small preform, it is necessary to make the front-end | tip of the outflow pipe 4 thin, and to make a glass outflow port small. As described above, the thinned outflow pipe 4 has a large amount of heat radiation, so that it is difficult to sufficiently heat the induction heating coil 6, which causes variations in the mass of the preform. On the other hand, as in the second embodiment, the loop member 34 is disposed at substantially the same height as the lower end of the outflow pipe 4, so that the temperature in the vicinity of the end of the outflow pipe 4 can be kept high. The mass accuracy of the reform can be maintained high.

  In the first and second embodiments, the loop member is disposed in the casing 2, but may be disposed below the casing 2.

  FIG. 3 is a vertical sectional view showing a glass outflow device according to a third embodiment of the present invention, and shows the periphery of the outflow pipe 4 in an enlarged manner. In the present embodiment, the loop member 44 is disposed below the casing 2. In addition, about another structure, it is the same as that of 1st Embodiment, In this embodiment, the code | symbol same as 1st Embodiment is attached | subjected about the component which has the function and structure similar to 1st Embodiment. The description is omitted.

  As shown in FIG. 3, the loop member 44 of the present embodiment is formed in an annular shape and is disposed below the lower end of the casing 2. Moreover, in this embodiment, in order to manufacture a large-sized preform, the outflow pipe 4 having a larger diameter than the first and second embodiments is used.

  In the case of manufacturing a large-sized preform, the time for the molten glass (glass material) to flow out from the outflow pipe 4 becomes long, so the temperature of the glass material in the mold 16 decreases, and the preform is deformed. Cause.

  On the other hand, in this embodiment, the loop member 44 is disposed below the casing 2. Thereby, not only the lower end of the outflow pipe 4 but also the molten glass (glass material) cast in the mold 16 can be heated by the loop member 44. Thereby, even when a large preform is manufactured, a preform with less deformation can be manufactured.

In addition, although each said embodiment demonstrated the case where the single loop member was provided, it is not restricted to this, It is also possible to use it combining the loop member of each embodiment.
Here, the inventors have described a glass outflow device (hereinafter referred to as a test example) including the loop member of the first embodiment described with reference to FIG. 1 and a glass outflow device (hereinafter referred to as a test example) that does not include the loop member. A comparative example) was used to make preforms made of fluorophosphate glass, boric acid-containing glass, and alkali-containing glass, which will be described below.

[Test Example of First Embodiment]
(Test Example 1-1: Production of preform made of fluorophosphate glass)
First, using phosphate, fluoride, etc., P ⁵⁺ is 26 cation%, Al ³⁺ is 20 cation%, Mg ²⁺ is 10 cation%, Ca ²⁺ is 14 cation%, Sr as cation components. ²⁺ 15 cation%, Ba ²⁺ 10 cation%, Li ⁺ 4 cation%, Y ³⁺ 1 cation%, F ⁻ 64 anion%, O ²⁻ 36 anion% A glass raw material was prepared so that a fluorophosphate glass having a refractive index nd of 1.501 and an Abbe number νd of 81.2 was obtained.

  Next, the glass raw material prepared in the platinum crucible of the glass melting apparatus 20 is introduced, heated and melted in the range of 850 to 1100 ° C. for several hours, clarified and homogenized to prepare a molten glass (glass material). did.

  A glass outflow device shown in FIG. 1 is attached under the platinum crucible. The casing 2, the outer flow path member 8, and the inner flow path member 10 are all made of quartz. A platinum loop member 14 is fixed inside the casing 2 as shown in FIG. The loop member 14 has a wave shape that swings in the vertical direction. When no force is applied, the loop member 14 has a diameter that is slightly smaller than the outer diameter of the inner flow path member 10 when viewed horizontally. An external force is applied so that the diameter of the loop member 14 in a horizontal view is slightly larger than the outer diameter of the inner flow path member 10, and the loop member 14 is placed on the outer peripheral surface of the inner flow path member 10, and then the external force is applied. By releasing, an elastic force to reduce the diameter is generated in the loop member 14, and the loop member 14 is fixed to the outside of the inner flow path member 10.

  In flowing out the molten glass in the platinum crucible from the glass outflow device, a high-frequency alternating current was passed through the induction heating coil 6 and dry nitrogen gas was passed through the gas passage 12 downward at a constant flow rate. The inside of the mold side casing 18 is also filled with dry nitrogen gas.

  When the lower end of the molten glass flowing out from the outflow pipe 4 at a constant flow rate is received by the concave surface of the molding die 16 supported at a high position by the lifting device 22, and the required amount of molten glass has accumulated in the concave surface, the lifting device 22. As a result, the mold 16 is rapidly lowered vertically downward. By this operation, the molten glass accumulated in the concave surface of the mold 16 is separated from the molten glass flowing out from the outflow pipe 4, and a molten glass lump corresponding to one preform is obtained on the concave surface of the mold 16.

  The concave surface of the mold 16 is made of a porous body, and dry nitrogen gas is injected from the concave surface by supplying high-pressure dry nitrogen gas to the back surface of the porous body. The molten glass lump on the concave surface is formed in a floating state by the wind pressure of the dry nitrogen gas sprayed from the concave surface.

  In this way, a plurality of molds are placed on the rotary table, the rotary table is index-rotated, the molds are sequentially transferred below the outflow pipe 4, and preforms are formed one after another from the molten glass that flows out continuously. To do. The point of transferring the mold using the rotary table, the structure of the mold side casing 18, the structure for taking out the preform molded from the mold, and the like are the same as the apparatus described in Patent Document 1.

As described above, the molten glass was poured out continuously for one day, and formed into a preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.
When the masses of the molded preforms were measured, the masses of all preforms were in the range of 300 mg ± 5 mg.
Further, after the outflow and molding of the molten glass were completed, the mold side casing 18 was removed and the outer periphery of the outflow pipe 4 was visually observed. As a result, there was no adhesion of volatiles from the molten glass.

(Test Example 1-2: Production of boric acid-containing glass preform)
In Test Example 1-2, the glass in the platinum crucible was changed to boric acid-containing glass, the mold-side casing 18 was removed, and the glass was formed in an air atmosphere. Other than that was carried out similarly to Experiment 1-1, and the molten glass was flowed out and the preform which consists of a boric-acid containing glass one after another was shape | molded.

  As described above, the molten glass was poured out continuously for one day, and formed into a preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.

When the masses of the molded preforms were measured, the masses of all the preforms were in the range of 1100 g ± 15 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

(Test Example 1-3: Production of glass preform containing alkali metal)
Except for changing the glass in the platinum crucible to an alkali metal-containing glass, the molten glass was flowed out in the same manner as in Test Example 1-2, and a preform made of the alkali metal-containing glass was formed one after another.

  As described above, the molten glass was poured out continuously for one day, and formed into a preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.

When the masses of the molded preforms were measured, the masses of all the preforms were within the range of 4500 g ± 25 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

[Comparative example of the first embodiment]
(Comparative Example 1-1: Production of fluorophosphate glass preform)
A preform made of fluorophosphate glass was continuously formed in the same manner as in Test Example 1-1 except that the loop member 14 was removed.

  90 minutes after the start of molding, striae suddenly occurred in the preform, and once the striae expanded gradually, it became impossible to obtain an optically homogeneous preform.

  The outflow and molding of the molten glass were stopped, the mold side casing 18 was removed, and the outer periphery of the outflow pipe 4 was visually observed. As a result, white deposits that seemed to be volatile from the molten glass were found on the outer periphery of the outflow pipe 4. From the part to the glass outlet.

  After removing the deposits, the mold side casing 18 was attached, and the molten glass flowed out and the molding was resumed. As a result, an optically homogeneous preform with no striae was obtained. After a minute, striae suddenly occurred again, and the striae once occurred gradually expanded, making it impossible to obtain an optically homogeneous preform.

  The outflow and molding of the molten glass were stopped again, the mold side casing 18 was removed, and the outer periphery of the outflow pipe 4 was visually observed. As a result, a white deposit adhered from the outer periphery of the outflow pipe 4 to the glass outlet. Was.

(Comparative Example 1-2: Production of boric acid-containing glass preform)
A preform made of boric acid-containing glass was continuously formed in the same manner as in Test Example 1-2 except that the loop member 14 was removed. Although it was not as frequent as the outflow and molding of fluorophosphate glass, striae suddenly occurred and an optically homogeneous preform could not be obtained.

(Comparative Example 1-3: Manufacture of alkali-containing glass preform)
A preform made of alkali metal-containing glass was continuously formed in the same manner as in Test Example 1-3 except that the loop member 14 was removed. Although it was not as frequent as the outflow and molding of fluorophosphate glass, striae suddenly occurred and an optically homogeneous preform could not be obtained.

  Next, the inventors have described a glass outflow device (hereinafter referred to as a test example) provided with the loop member of the second embodiment described with reference to FIG. 2 and a glass outflow device not provided with the loop member (hereinafter referred to as a test example). A test for preparing preforms made of boric acid-containing glass and alkali-containing glass was performed using a comparative example), and will be described below.

[Test Example of Second Embodiment]
(Test Example 2-1: Production of boric acid-containing glass preform)
Using the borate glass used in Test Example 1-2, the molten glass (glass material) flows out from the glass outflow device shown in FIG. 2, and the molten glass is dropped from the glass outlet at the lower end of the outflow pipe 4. The droplets were received by a mold (not shown) and formed into a spherical preform.

  The outflow pipe 4 is thinned to have a pipe diameter suitable for dripping molten glass droplets, the loop member 34 is formed in an annular shape, and is substantially the same height as the lower end of the outflow pipe 4 by the inclined portion 30A of the outer flow path member 30. The mold is not moved up and down by the lifting device, the index plane is rotated by the rotary table in the same horizontal plane, and the concave surface of the mold is not a porous body, and a gas outlet is provided at the bottom. It differs from Test Example 1-2 in that it has a trumpet type. The molding atmosphere of the molten glass was an air atmosphere.

  Under the above conditions, molten glass was dropped from the lower end of the outflow pipe for one day continuously, and formed into a spherical preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.

When the masses of the molded preforms were measured, the masses of all preforms were in the range of 15 mg ± 0.1 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

(Test Example 2-2: Production of alkali metal-containing glass preform)
Using the alkali metal-containing glass used in Test Example 1-3, the molten glass (glass material) flows out from the glass outflow device shown in FIG. 2, and the molten glass is dropped from the glass outlet at the lower end of the outflow pipe 4. Glass droplets were received by a mold (not shown) and formed into a spherical preform.

  The outflow pipe 4 is thinned to have a pipe diameter suitable for dripping molten glass droplets, the loop member 34 is formed in an annular shape, and is substantially the same height as the lower end of the outflow pipe 4 by the inclined portion 30A of the outer flow path member 30. The mold is not moved up and down by the lifting device, the index plane is rotated by the rotary table in the same horizontal plane, and the concave surface of the mold is not a porous body, and a gas outlet is provided at the bottom. It differs from Test Example 1-3 in that it has a trumpet type. The molding atmosphere of the molten glass was an air atmosphere.

Under the above conditions, molten glass was dropped from the lower end of the outflow pipe for one day continuously, and formed into a spherical preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.
When the masses of the molded preforms were measured, the masses of all the preforms were in the range of 25 mg ± 0.15 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

[Comparative Example of Second Embodiment]
(Comparative Example 2-1: Production of boric acid-containing glass preform)
A preform made of boric acid-containing glass was continuously formed in the same manner as in Test Example 2-1, except that the loop member 34 was removed.
The weight of the preform was in the range of 15 mg ± 0.3 mg, and the weight variation was large.

(Comparative Example 2-2: Production of alkali metal-containing glass preform)
A preform made of alkali metal-containing glass was continuously formed in the same manner as in Test Example 2-2 except that the loop member 34 was removed.
The weight of the preform was in the range of 25 mg ± 0.4 mg, and the weight variation was large.

  Next, the inventors have described a glass outflow device (hereinafter referred to as a test example) provided with the loop member of the third embodiment described with reference to FIG. A comparative example) was used to make preforms made of fluorophosphate glass, boric acid-containing glass, and alkali-containing glass, which will be described below.

[Test Example of Third Embodiment]
(Test Example 3-1: Production of fluorophosphate glass preform)
Next, a preform was produced using the glass outflow apparatus shown in FIG.
The glass used is the same glass as in Test Example 1-1. The glass outflow device shown in FIG. 3 is substantially the same as that used in Test Example 1-1, but the diameter of the outflow pipe 4 is the diameter of the outflow pipe in Test Example 1-1 in order to produce a large preform. The casing which is thicker than the loop member 44 and has an annular shape and covers the periphery of the outflow pipe 4 is also fixed to the lower end by a fixture (not shown). Further, since a large preform is molded, the diameter of the concave surface of the mold 16 is larger than that in the case of FIG.

  The molding atmosphere of the molten glass was set to a dry nitrogen atmosphere by filling the inside of the mold side casing with dry nitrogen gas, as in Test Example 1-1.

  The concave surface of the mold 16 is made of a porous material, similar to Test Example 1-1, and a preform is formed by blowing up dry nitrogen gas and applying upward wind pressure to the molten glass lump cast on the concave surface to float. To form.

  In this way, the molten glass was discharged from the lower end of the outflow pipe for one day in succession and formed into a preform one after another. When the molded preform was observed, no striae and devitrification were observed, and an optically homogeneous preform could be produced continuously for one day.

When the mass of the molded preform was measured, the mass of all the preforms was in the range of 11800 mg ± 100 mg.
Further, after the outflow and molding of the molten glass were completed, the mold side casing 18 was removed and the outer periphery of the outflow pipe 4 was visually observed. As a result, there was no adhesion of volatiles from the molten glass.

(Test Example 3-2: Production of boric acid-containing glass preform)
The molten glass flows out in the same manner as in Test Example 3-1, except that the glass in the platinum crucible is changed to boric acid-containing glass, the mold-side casing 18 is removed, and the glass is molded in an air atmosphere. Then, preforms made of boric acid-containing glass were formed one after another.

  As described above, the molten glass was poured out continuously for one day, and formed into a preform one after another. When the molded preform was observed, no striae, devitrification, and deformed ibis shape were observed, and an optically homogeneous preform could be produced continuously for one day.

When the masses of the molded preforms were measured, the masses of all the preforms were in the range of 9800 mg ± 80 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

(Test Example 3-3: Production of preform made of alkali metal-containing glass)
Except for changing the glass in the platinum crucible to the alkali metal-containing glass, the molten glass was flowed out in the same manner as in Test Example 3-2, and a preform made of the alkali metal-containing glass was formed one after another.

  As described above, the molten glass was poured out continuously for one day, and formed into a preform one after another. When the molded preform was observed, no striae, devitrification, and deformed ibis shape were observed, and an optically homogeneous preform could be produced continuously for one day.

When the masses of the molded preforms were measured, the masses of all the preforms were within the range of 30000 mg ± 130 mg.
Furthermore, when the outer periphery of the outflow pipe 4 was visually observed after the outflow and molding of the molten glass, there was no adhesion of volatiles from the molten glass.

[Comparative Example of Third Embodiment]
(Comparative Example 3-1: Production of preform made of fluorophosphate glass)
A preform made of fluorophosphate glass was continuously formed in the same manner as in Test Example 3-1, except that the loop member 44 was removed.

  60 minutes after molding started, striae suddenly occurred in the preform, and once the striae expanded gradually, it became impossible to obtain an optically homogeneous preform.

  The outflow and molding of the molten glass was stopped, the mold side casing was removed, and the outer periphery of the outflow pipe 4 was visually observed. To the glass outlet.

  After removing this deposit, the mold side casing was attached, and molten glass flowed out and molding was resumed. As a result, an optically homogeneous preform with no striae was obtained, but 30 minutes after molding resumed. Later, striae occurred suddenly again in the preform, and once the striae gradually expanded, it became impossible to obtain an optically homogeneous preform.

  The outflow and molding of the molten glass were stopped again, the mold side casing was removed, and the outer periphery of the outflow pipe 4 was visually observed. As a result, a white deposit adhered from the outer periphery of the outflow pipe 4 to the glass outlet. It was.

(Comparative Example 3-2: Production of boric acid-containing glass preform)
A preform made of boric acid-containing glass was continuously molded in the same manner as in Test Example 3-2 except that the loop member 44 was removed. Streaks occurred over time, although not as frequently as the outflow and molding of fluorophosphate glass. Furthermore, the shape of the preform was deformed and distorted, making it impossible to obtain an optically homogeneous preform.

(Comparative Example 3-3: Production of alkali-containing glass preform)
A preform made of alkali metal-containing glass was continuously formed in the same manner as in Test Example 3-3 except that the loop member 44 was removed. Although it was not as frequent as the outflow and forming of fluorophosphate glass, striae occurred over time. Furthermore, the shape of the preform was deformed and distorted, making it impossible to obtain an optically homogeneous preform.

  Furthermore, the inventors have made a glass outflow device (hereinafter referred to as a test) including the loop member 14 that swings in the vertical direction of the first embodiment and has a loop member 44 disposed below the casing 2 of the third embodiment. A test for preparing a preform made of fluorophosphate glass was performed using an example), which will be described below.

[Combination of the first embodiment and the third embodiment]
(Test Example 4)
In Test Example 3-1, a platinum loop member having a wave shape that swings in the vertical direction as in Test Example 1-1 is attached, and the outflow pipe 4 and the outflowing molten glass are assisted by high-frequency induction heating together with the loop member 44. Heated.

  Also in this test example, an optically homogeneous preform made of fluorophosphate glass and having no striae could be produced with high mass accuracy.

Finally, the first embodiment will be summarized with reference to the drawings.
As shown in FIG. 1, the glass outflow apparatus 1 of 1st Embodiment is a glass outflow apparatus which flows out molten glass, Comprising: The outflow pipe 4 extended in an up-down direction and outflowing molten glass, and the outer periphery of the outflow pipe 4 An induction heating coil 6 provided on the side, and a loop member 14 that is provided so as to surround the outside of the outflow pipe 4 in a horizontal view and is made of a closed loop conductor that can be induction-heated by the induction heating coil 6.

  Moreover, the glass outflow method of 1st Embodiment is a method of flowing out molten glass, Comprising: The induction heating coil 6 is provided in the outer peripheral side of the outflow pipe 4 which flows out molten glass, and induction heating coil 6 carries out induction heating. A loop member 14 made of a possible closed loop conductor is provided so as to surround the outside of the outflow pipe 4 in a horizontal view, and the molten glass flows out from the outflow pipe 4 while induction heating the loop member 14 by the induction heating coil 6. To do.

DESCRIPTION OF SYMBOLS 1 Glass outflow apparatus 2 Casing 4 Outflow pipe 6 Induction heating coil 8, 30 Outer flow path member 10 Inner flow path member 12 Gas flow path 14, 34, 44 Loop member 16 Mold 18 Mold side casing 20 Glass melting apparatus 22 Elevation apparatus

Claims (12)

A glass outflow device for flowing out molten glass,
A pipe extending vertically and flowing out of the molten glass;
An induction heating coil provided on the outer peripheral side of the pipe;
A glass outflow device comprising: a loop member that is provided so as to surround the outside of the pipe in a horizontal view and is formed of a closed loop-shaped conductor that can be induction heated by the induction heating coil.   The glass outflow device according to claim 1, wherein the loop member is provided on an outer peripheral side of the pipe and on an inner peripheral side of the induction heating coil.   The glass outflow device according to claim 1 or 2, wherein the loop member is provided so as to surround an outer peripheral side of the pipe.   The glass outflow device according to any one of claims 1 to 3, wherein the loop member has a wave shape that swings in a vertical direction.   5. The gas passage is formed so as to surround the pipe, and is provided with a gas passage for blowing an inert gas in the vicinity of a tip of the pipe, and the loop member is provided in the gas passage. The glass outflow apparatus of any one of these. The glass outflow device according to any one of claims 1 to 5,
A glass molded product manufacturing apparatus, comprising: a molding apparatus configured to flow molten glass out of the glass outflow apparatus. A method for discharging molten glass,
An induction heating coil is provided on the outer peripheral side of the pipe that flows out of the molten glass,
A loop member made of a closed loop conductor that can be induction heated by the induction heating coil is provided so as to surround the outside of the pipe in a horizontal view,
A glass outflow method of flowing out the molten glass from the pipe while induction heating the loop member by the induction heating coil. Near the tip of the pipe, a gas flow path for flowing an inert gas along the outer peripheral surface of the pipe is formed so as to surround the pipe,
The glass outflow method according to claim 7, wherein the inert gas is allowed to flow downward in the gas flow path.   The glass outflow method according to claim 7 or 8, wherein the loop member is provided in the gas flow path.   The manufacturing method of the glass molded product which flows out molten glass with the glass outflow method of any one of Claim 7 to 9, and shape | molds.   The manufacturing method of the glass molded product of Claim 10 which shape | molds molten glass to the preform for press molding. A step of producing a preform for press molding by flowing out the molten glass by the glass outflow method according to claim 11;
Heating the preform;
Press-molding the heated preform;
A method for manufacturing an optical element.

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