JPH08133751A - Method and device for supplying fused glass - Google Patents

Abstract

PURPOSE: To freely control the supply timing of glass gob having a desired viscosity by heating and melting the glass in a crucible so that the prescribed glass viscosity is attained, heating the glass to the prescribed glass viscosity, dropping the fused glass from a supply nozzle, cooling the intermediate part of this supply nozzle, stopping the glass dropping, further, stopping the cooling and again dropping the glass drops. CONSTITUTION: The glass is heated and fused in the crucible to the glass viscosity of 10<5> to 10<2> poises and is further heated to the glass viscosity of 10<5> to 10<2> poises and is dropped from the supply nozzle. A nozzle heater 9 and a gas cooling nozzle 10 are arranged on the side face of the glass supply nozzle 4 as shown in the fig. The glass fused in the crucible flows in the supply nozzle 4 and is cooled by the cooling nozzle 10. The flow of the fused glass is then stopped. The glass is heated again up to the desired temp. and the dropping from the front end of the nozzle begins when the cooling is stopped at this time. The dropped glass gob 8 drops onto a lower die 13 and is moved to above the axis of an upper die 12 by a lower die sliding base 22 after dropping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for melting and supplying glass, and more particularly to a method and an apparatus for melting and supplying a glass gob for forming an optical glass and manufacturing an optical element.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Publication No.
Japanese Patent No. 16414 and Japanese Patent Publication No. 4-32772 are known.

In Japanese Patent Publication No. 4-16414, a crucible for melting glass, a supply nozzle provided at the bottom of the crucible, a lower mold for receiving the glass dropped from the nozzle, and a press molding after receiving the glass drop. And an upper mold for making the same. And to mold with this device, by adjusting the distance between the nozzle and the mold, the surface temperature of the glass drops received by the mold is lower than the glass softening temperature,
A method is described in which the internal temperature is set to be higher than the softening temperature, and after receiving with a mold, press molding with a second mold is described.

Japanese Patent Publication No. 4-32772 discloses a crucible for melting glass, a supply nozzle provided at the bottom of the crucible, a lower mold for receiving the glass dropped from the nozzle, and a press molding after receiving the glass drop. In order to control the temperature of the upper part of the supply nozzle from the upper part of the supply nozzle to 5
A method in which the temperature is set to be 0 to 200 ° C. higher, the surface temperature of the glass drops is lower than the glass softening temperature, and the internal temperature is dropped to be higher than the softening temperature, and then received by a lower mold and press-molded by a second mold Has been described.

[0005]

However, the above-mentioned conventional technique has the following problems.

In Japanese Patent Publication No. 4-16414, when the temperature of the supply nozzle 1 is lowered, the glass viscosity increases,
As shown in FIG. 1, the dropped glass is in the stringing state 3. On the contrary, when the temperature of the supply nozzle 1 is increased, the molten glass continuously flows out and does not become a glass drop state. In order to produce a glass drop state by this method, it is necessary to control the temperature of the supply nozzle. However, if the temperature is controlled, it can be made into a glass drop state, but since the temperature is limited to maintain the glass drop state, this time it is necessary to control the drop interval of glass drops by changing the supply nozzle temperature. Can not be. Therefore, the molding interval is set by the interval of glass drops. There is no problem with a lens that can be molded within the glass dropping interval, but with a large-diameter lens or a lens with a thick wall, the molding time becomes long, and depending on the lens shape, it cannot be molded within the dropping interval. Further, depending on the type of glass, there are glasses that are sensitive to temperature changes and glasses that are insensitive, and the dropping intervals differ even with the same glass viscosity. Therefore, there is a problem that the molding interval changes depending on the type of glass and the productivity is not constant.

Japanese Patent Publication No. 4-32772 discloses means for dropping glass drops by providing a temperature difference between the upper part and the lower part of a supply nozzle. If the upper temperature of the supply nozzle is set low and the lower temperature of the supply nozzle is set high, the glass flow in the nozzle becomes slow and the dropping interval becomes long. Therefore, the dropping interval can be changed by controlling the temperature of the nozzle. However, since the dropping gob cannot be stopped and the discharge cannot be controlled, it cannot be stopped due to mechanical troubles. Therefore, there is a problem that once the melting is started, it is not possible to make changes in the middle.

The present invention has been made in view of the above problems, and it is an object of the first and third aspects to freely control the supply timing of a glass gob having a desired viscosity.

The second and fourth aspects are intended to stop the supply of the molten glass.

[0010]

In order to achieve the above object, a method of supplying molten glass according to the present invention according to claim 1 is a method of melting glass by heating in a crucible and dropping the glass into a receiving member from a supply nozzle. , The step of heating and melting the glass in the crucible to a temperature corresponding to 10 ⁵ to 10 ² poise in glass viscosity, and the glass viscosity in the supply nozzle installed below corresponds to 5 to 10 ² poise in glass viscosity Heating to a temperature to drop in a glass droplet state, cooling the intermediate portion of the supply nozzle with a cooling jig to stop the glass dropping, cooling the cooling jig to stop the glass droplet again. And a step of dropping.

In this case, as described in claim 2, it is preferable that the glass is cooled by the cooling jig to have a glass viscosity of 10 ⁶ poise or more.

Further, in the molten glass supply device of the present invention according to claim 3, the melting crucible for melting the glass, the supply nozzle installed at the bottom of the melting crucible, and the temperature control of the crucible and the supply nozzle independently. A crucible heater and a supply nozzle heater for cooling the supply nozzle, and a cooling jig installed in an intermediate portion of the supply nozzle for cooling the supply nozzle.

In this case, as described in claim 4, in the cooling jig, cooling is performed by spraying a gas whose temperature is set in advance to the middle portion of the supply nozzle, and a cooling jacket is installed in the middle portion of the supply nozzle to set the temperature in advance. It is preferable to select any one of cooling by flowing a set liquid and cooling by bringing a solid whose temperature is set in advance into contact with an intermediate portion of the supply nozzle.

[0014]

The operation of claims 1 and 3 will be described with reference to FIGS. As shown in FIG. 2, the nozzle heater 9 and the nozzle cooling device 7 are arranged on the side surface of the glass supply nozzle 4. The glass melted in a melting crucible (not shown) is set in advance by a nozzle heater 9 to a temperature at which the glass gob has a desired viscosity.
It flows in. However, as shown in FIG. 3 (a), since the cooling device 7 cools the intermediate portion of the supply nozzle 4, the molten glass has a high viscosity and stops at the cooled portion. Therefore, the flow does not proceed below that position.
When the cooling of the supply nozzle 4 is stopped as shown in FIG. 3B, the temperature of the cooled portion of the supply nozzle 4 is raised to a desired temperature by the nozzle heater 9 and the glass viscosity is lowered, so that the flow again occurs. At the beginning, dripping is started from the tip of the nozzle. As shown in FIG. 3C, when the supply nozzle 4 is cooled again, the low temperature glass portion of the nozzle cooling portion is formed and the glass dropping is stopped. This stops the dropping of the glass,
In addition, re-dripping becomes possible. Therefore, it is possible to freely control the supply of the molten glass and the stop interval, which have been problems in the past.

The reason why the nozzle middle part is cooled in order to cool and stop the nozzle is as follows. FIG. 2 shows the glass temperature distribution when the dropping is stopped. The glass temperature of the cooling part is low (the glass low temperature part 6) and the glass temperatures of the upper and lower parts are high (the glass high temperature part 5) centering on the nozzle cooling part. As described above, when the cooling of the cooling device 7 is stopped, the molten glass of the glass high temperature portion 5 located at the lower part drops. Therefore, the glass having a desired viscosity can be dropped regardless of the dropping interval. However, when the position of the cooling device 7 is set to the tip of the supply nozzle 4, there is no region of high temperature glass located at the lower part, so when dropping, the viscous glass is formed and the shape of the glass drop does not occur. As shown, stringing occurs and the glass gob becomes defective.
Therefore, if the molding is performed after the dropping, defects on the molding surface occur, and a highly accurate lens cannot be obtained.

On the contrary, if the cooling device is installed above the supply nozzle, the following problems occur. When the upper part of the supply nozzle 4 is cooled, the temperature distribution becomes as shown in FIG. Since the area of the lower glass high temperature portion 5 becomes long, the glass low viscosity area becomes large. The stoppage of glass dropping according to the present invention is due to the adhesion between the inner surface of the nozzle and the glass and the stoppage of the flow due to the low temperature glass portion 6. However, in this state, since there are many low-viscosity regions of the glass, it is difficult to stop the flow in the low-temperature glass part 6, and therefore the dropping of the glass cannot be stopped. From the above, it is necessary to cool the intermediate portion of the supply nozzle.

The operation of claim 2 is as follows. In the nozzle cooling, cooling the cooling temperature to a glass viscosity of 10 ⁶ poise or more is a viscosity required to stop the flow of glass. At a temperature corresponding to a viscosity of 10 ⁶ poise or less, the dropping of glass cannot be stopped because the glass flow does not stop.

Claim 4 specifies the nozzle cooling means. Cooling of gases, liquids and solids is possible.

[0019]

Embodiments of the molten glass supply method and apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1) This embodiment is a method of controlling a glass gob by introducing a gas and cooling it.
After the dropping, the optical element is manufactured by molding with a pair of molding dies. 5 is a sectional view of the crucible-nozzle apparatus, FIG. 6 is a perspective view of the supply nozzle, and FIG. 7 is a sectional view showing a portion below the nozzle.

(Structure) The crucible heater 19 is installed on the outer peripheral portion of the melting crucible 21 to melt the glass to a desired viscosity.
The supply nozzle 4 is installed at the bottom of the melting crucible 21. The outer peripheral portion of the supply nozzle 4 is surrounded by a nozzle heater 9 and a heat insulating material.

A gas cooling nozzle 10 shown in FIG. 6 is installed in the middle of the supply nozzle 4. As shown in FIG. 5, the gas cooling nozzle 10 has a U-shaped cross section and is installed so as to surround the entire outer peripheral portion of the supply nozzle 4. In addition, pipes for introducing and exhausting gas are welded in a direction perpendicular to the direction of the supply nozzle 4. The gas cooling nozzle 10 is not welded to the supply nozzle 4. Accordingly, the melting crucible 21 can be easily removed because it is independent of the gas cooling nozzle 10. The gas cooling nozzle 10 may be made of any material as long as it can support the heating temperature, but Pt of the same material as the supply nozzle 4 or ceramics having high thermal shock resistance is preferable.

As shown by the arrow in FIG. 5, the gas flow is introduced from one side and discharged from the other side, whereby the supply nozzle 4 is cooled. As the nozzle heater 9, a heater capable of heating to a temperature corresponding to a glass viscosity of 5 poises is used. Generally, a sintered body heater or a high frequency heating device is preferable.

A lower mold 13 having a holder 14 is arranged on the axis of the supply nozzle 4 and below the axis. The lower mold 13 is heated and maintained at a desired temperature by a heater. The lower die 13 is installed on the lower die slide table 22 and moves to the axis of the upper die 12. Like the lower mold 13, the upper mold 12 is heated and maintained at a desired temperature by a heater. For molding, the upper mold 12 is driven in the axial direction to mold the glass gob. After molding, a transfer arm 24 for taking out the lens is installed, and it is possible to take out the lens together with the holder 14 from above the lower mold 13.

(Method) A method for forming a lens from molten glass by the above apparatus will be described.

The molten glass 20 is heated and melted by the crucible heater 19 to a temperature corresponding to a glass viscosity of 10 ⁵ poise. After the melting, the supply nozzle heater 9 heats the supply nozzle 4 to a temperature corresponding to a glass viscosity of 10 poise. At this time, the middle portion of the supply nozzle 4 is the gas cooling nozzle 1
0 cools to a temperature corresponding to a glass viscosity of 10 ⁶ poise. In this embodiment, the pressure of the gas at room temperature is 2 kgf / cm.
² , introduced at a flow rate of 151 / min. The molten glass 20 flows due to the heating of the supply nozzle 4, and flows to the upper portion of the nozzle cooling unit. After the glass viscosity in the supply nozzle 4 reaches 10 poise, gas introduction is stopped. When the gas introduction is stopped, the temperature of the cooling part of the supply nozzle 4 rises, and the molten glass starts flowing. Immediately after the molten glass is dropped from the tip of the supply nozzle 4, the gas under the same conditions as described above is introduced into the gas cooling nozzle 10. As a result, the molten glass in the supply nozzle 4 has a glass high temperature portion 5 and a glass low temperature portion 6 as shown in FIG. 5, and the glass flow stops.

When the glass gob drops, the glass gob 8 drops onto the lower mold 13, as shown in FIG. After dropping, the lower mold 13 is moved on the axis of the upper mold 12 by the lower mold slide table 22. The lower mold 13 and the upper mold 12 are heated and held in advance at a temperature corresponding to a glass viscosity of 10 ^12.5 poise.
After moving on the upper die 12 axis, the upper die 12 descends and the glass gob 8
Was molded at a pressing pressure of 50 kgf / cm ² and a pressing time of 20 sec.

After molding, the transfer arm 24 moves to move the holder 1
4. Remove 4 and molded lens. After taking out the lens, the holder 14 is conveyed to the lower mold 13, and the lower mold 13 moves again on the axis of the supply nozzle 4. After moving the lower mold 13, the gas in the gas cooling nozzle 10 is stopped and the dropping is started.

(Effect) According to this embodiment, the glass gob supply timing can be set to the molding timing. Generally, when the lens diameter is large, the pressing time is long, and when the lens diameter is small, the molding time is short. Even in such a case, the supply can be controlled only by changing the gas supply time. Further, since the cooling is performed by a gas, this method is suitable for a case where the cooling rate is high and the diameter of the supply nozzle is large, or for glass in which the change in glass viscosity due to temperature change is small.

In this embodiment, the molten glass viscosity was set to 10 ⁵ poise and the glass viscosity at the supply nozzle was set to 10 poise, but it can be changed depending on the characteristics of the glass. However, in order to drop one drop from the supply nozzle, the temperature needs to be 5 to 10 ² poises. When the viscosity is 5 poise or less, dropping is possible, but the glass component is decomposed and volatilized, which causes a problem in optical characteristics. On the contrary, when the viscosity is set to 10 ² poise or more, the viscosity is so high that a single drop does not occur and threading occurs, resulting in defects on the molding surface during molding.

Although the above-mentioned embodiment was a method of manufacturing an optical element by molding with a pair of molding dies, it can be applied to manufacture of a glass gob for molding as shown in FIG. In the configuration of the glass gob molding machine of FIG. 8, the centrifugal holder 15 is installed at the tip of the rotary arm 25 extending in the direction perpendicular to the axis of the rotary motor 18. The receiving mold 16 is installed in the holder. The glass contact surface of the receiving die 16 is polished into a desired shape. The centrifugal holder 15 can freely rotate about the axis of the rotating arm 25. Further, it freely moves like a pendulum around the centrifuge holder mounting shaft 26. Therefore, when the motor 18 rotates, the glass gob 8 acts in a direction of being in close contact with the receiving mold, so that the glass gob flows over the entire surface of the receiving mold, and a glass gob for molding having a spherical surface on one side and a free surface on the other side can be molded. Also in this apparatus, the timing of centrifugal molding can be set because the dropping can be controlled by installing the supply nozzle.

(Embodiment 2) This embodiment describes a method of cooling the middle portion of the supply nozzle with a liquid. After the dropping, the optical element is manufactured by molding with a pair of molding dies as in Example 1. FIG. 9 is a device cross-sectional view of the crucible and the nozzle.
The external appearance has the same shape as the perspective view of the supply nozzle in FIG. 6, and the molding apparatus has the shape shown in FIG. 7 as in the first embodiment.
The gas cooling nozzle 10 replaces the liquid cooling unit 27 shown in FIG.

(Structure) The melting crucible, the vicinity of the supply nozzle, and the molding section are the same as in Example 1. The liquid cooling unit 27 shown in FIG. 9 is installed in the middle of the supply nozzle 4.

As shown in FIG. 9, the liquid cooling unit 27 has a rectangular pipe-shaped cross section and is installed so as to surround the entire outer peripheral portion of the supply nozzle 4. Supply nozzle 4
The surface that comes into contact with is a flat surface so as to increase the efficiency of heat transfer. Further, pipes for introducing and discharging the liquid are welded in a direction perpendicular to the direction of the supply nozzle 4. Further Example 1
Similarly, the liquid cooling unit 27 is not welded to the supply nozzle 4. Thus, the melting crucible 21 can be easily removed because it is independent of the liquid cooling unit 27. The liquid cooling unit 27 may be made of any material as long as it can support the heating temperature, but Pt of the same material as the supply nozzle 4 or ceramics having high thermal shock resistance is preferable.

The cooling liquid is preferably oil or the like, particularly silicon-based oil having high heat resistance. The oil is circulated by a pump (not shown). Oil having a constant temperature is circulated in the circulation system by a temperature controller that controls the temperature of the oil. When cooling is stopped, the temperature of the supply nozzle 4 becomes high, so the circulating oil is temporarily collected in the pump. This prevents carbonization of the oil. During cooling, oil is sent to the liquid cooling unit 27 and circulated.

(Method) A method for forming a lens from molten glass by the above apparatus will be described.

As in Example 1, the crucible heater 19 heats and melts the molten glass 20 to a temperature corresponding to a glass viscosity of 10 ⁵ poise. After the melting, the supply nozzle heater 9 heats the supply nozzle 4 to a temperature corresponding to a glass viscosity of 10 poise. At this time, the intermediate portion of the supply nozzle 4 is cooled by the liquid cooling unit 27 to a temperature corresponding to a glass viscosity of 10 ⁶ poise. The temperature control is performed by controlling the oil flow rate. The molten glass 20 flows due to the heating of the supply nozzle 4, and flows to the upper portion of the nozzle cooling unit. After the glass viscosity in the supply nozzle 4 reaches 10 poise, the oil circulation is stopped and the oil is collected in the pump. When the oil circulation is stopped, the temperature of the cooling part of the supply nozzle 4 rises and the molten glass starts to flow. Immediately after the molten glass has dripped from the tip of the supply nozzle 4, the oil under the same conditions as described above is circulated in the liquid cooling unit 27. As a result, the molten glass in the supply nozzle 4 is
The glass high temperature part 5 and the glass low temperature part 6 as shown in FIG.

Hereinafter, the molding process is the same as that of the first embodiment.
After the molding is completed, the oil circulation of the liquid cooling unit 27 is stopped and the dropping is started.

(Effect) According to this embodiment, the glass gob supply timing can be set to the molding timing. Generally, the pressing time is long when the lens diameter is large, and the molding time is short when the lens diameter is small. Even in such a case, the supply can be controlled only by changing the gas supply time. Also, since oil is used for cooling, the cooling temperature can be controlled accurately. Therefore, it is good for controlling the supply of glass whose glass viscosity is sensitive to changes in temperature.

In this embodiment, the molten glass viscosity was set to 10 ⁵ poise and the glass viscosity at the supply nozzle was set to 10 poise, but it can be changed depending on the characteristics of the glass. However, in order to drop one drop from the supply nozzle, the temperature needs to be 5 to 10 ² poises. When the viscosity is 5 poise or less, dropping is possible, but the glass component is decomposed and volatilized, which causes a problem in optical characteristics. On the contrary, when the viscosity is set to 10 ² poise or more, the viscosity is so high that a single drop does not occur and threading occurs, resulting in defects on the molding surface during molding.

Although the above-mentioned embodiment was a method of manufacturing an optical element by molding with a pair of molding dies, like FIG.
It can also be applied to supply of glass gobs for molding as shown in FIG.

(Embodiment 3) This embodiment describes a method of cooling the middle portion of the supply nozzle with a solid. After the dropping, the optical element is manufactured by molding with a pair of molding dies as in Example 1. FIG. 10 is a sectional view of the nozzle to the molding apparatus, and FIG. 11 is a perspective view of the supply nozzle.

(Structure) A crucible heater is installed on the outer periphery of a melting crucible (not shown) to melt the glass to a desired viscosity. The general shape is similar to that of FIG. 5 or FIG. 9 of the above embodiment. The supply nozzle 4 is installed at the bottom of the melting crucible. The outer peripheral portion of the supply nozzle 4 is surrounded by a nozzle heater 9 and a heat insulating material.

The cooling member 11 shown in FIGS. 10 and 11 is installed in the middle of the supply nozzle 4. The shape is shown in Figure 1.
As shown in FIG. 1, it has a ring shape, and the center portion has the same diameter as the supply nozzle diameter, and the contact area with the supply nozzle 4 is increased to improve the cooling efficiency. The outer diameter varies depending on the thermal conductivity of the cooling member 11, but in the case of a material having a high thermal conductivity, the outer diameter is increased to increase the heat absorption amount. Further, in the case of a material having a low thermal conductivity, the outer diameter is reduced to improve heat absorption.

The movement of the cooling member is driven back and forth in the direction perpendicular to the supply nozzle 4, as shown by the arrow in FIG. 10 or 11. It is driven by a cylinder or the like (not shown). Cooling member 1 in contact to cool supply nozzle 4
Since the temperature of 1 is high, the cooling member 11 moves backward after the cooling is completed, and the cooling member cooling nozzle 28 blows cool air from the upper and lower surfaces to cool the cooling member 11. Since the cooling member needs to absorb heat instantly, it is preferable to use metal or ceramics having good heat conduction. As the nozzle heater 9, a heater capable of heating to a temperature corresponding to a glass viscosity of 5 poises is used. Generally, a sintered body heater or a high frequency heating device is preferable.

A lower mold 13 having a holder 14 is arranged on the axis of the supply nozzle 4 and below the axis. The lower mold 13 is heated and maintained at a desired temperature by a heater. The lower die 13 is installed on the lower die slide table 22 and moves to the axis of the upper die 12. Like the lower mold 13, the upper mold 12 is heated and maintained at a desired temperature by a heater. For molding, the upper mold 12 is driven in the axial direction to mold the glass gob. After molding, a carrier 24 for taking out the lens is installed, and it can be taken out together with the holder 14 from the lower mold 13.

(Method) A method for forming a lens from molten glass by the above apparatus will be described.

The molten glass is heated and melted in a crucible (not shown) to a temperature corresponding to a glass viscosity of 10 ⁵ poise. After the melting, the supply nozzle heater 9 heats the supply nozzle 4 to a temperature corresponding to a glass viscosity of 10 poise. At this time, the middle portion of the supply nozzle 4 is cooled to a temperature corresponding to a glass viscosity of 10 ⁶ poise by contact with the cooling member 11. When the temperature of the cooling member 11 rises during cooling,
The cooling member 11 is retracted, the temperature is lowered by the cooling member cooling nozzle 28, and the cooling member cooling nozzle 28 is brought into contact with the supply nozzle 4 again. The molten glass 20 flows due to the heating of the supply nozzle 4, and flows to the upper portion of the nozzle cooling unit. The glass viscosity in the supply nozzle 4 is 1
After reaching 0 poise, the cooling member 11 retracts. The temperature of the cooling part of the supply nozzle 4 rises due to the retreat of the cooling member 11, and the molten glass starts to flow. Immediately after the molten glass drops from the tip of the supply nozzle 4, the cooling member 11 is brought into contact with the supply nozzle 4. As a result, the molten glass in the supply nozzle 4 has a glass high temperature portion 5 and a glass low temperature portion 6 as shown in FIG. 5, and the glass flow stops.

After dropping the glass gob, the glass gob 8 falls onto the lower mold 13, as shown in FIG. After falling, lower mold 1
3 is moved by the lower die slide base 22 onto the 12 axes of the upper die. The lower mold 13 and the upper mold 12 have a glass viscosity of 10 in advance.
It is heated and maintained at a temperature equivalent to ^12.5 poise. Upper mold 12
After moving on the shaft, the upper mold 12 descended to mold the glass gob 8 at a pressing pressure of 50 kgf / cm ² and a pressing time of 20 sec.

After molding, the transfer arm 24 moves to move the holder 1
4. Remove 4 and molded lens. After taking out the lens, the holder 14 is conveyed to the lower mold 13, and the lower mold 13 moves again on the axis of the supply nozzle 4. After the lower mold 13 has moved, the cooling member is retracted to start dropping.

(Effect) According to this embodiment, the glass gob supply timing can be set to the molding timing. Generally, the pressing time is long when the lens diameter is large, and the molding time is short when the lens diameter is small. Even in such a case, the supply can be controlled only by changing the contact time of the cooling member. Further, the cooling efficiency of the method of this embodiment is lower than that of the above embodiments, but since there is no welding of the cooling unit to the supply nozzle, it is easy to change the diameter of the supply nozzle and to remove the crucible.

In this embodiment, the molten glass viscosity was set to 10 ⁵ poise and the glass viscosity at the supply nozzle was set to 10 poise, but it can be changed depending on the characteristics of the glass. However, in order to drop one drop from the supply nozzle, the temperature needs to be 5 to 10 ² poises. When the viscosity is 5 poise or less, dropping is possible, but the glass component is decomposed and volatilized, which causes a problem in optical characteristics. On the contrary, when the viscosity is set to 10 ² poise or more, the viscosity is so high that a single drop does not occur and threading occurs, resulting in defects on the molding surface during molding.

Although the above-mentioned embodiment was a method of manufacturing an optical element by molding with a pair of molding dies, it can be applied to the supply of the molding glass gob as shown in FIG. 8 described in the above-mentioned embodiment.

[0054]

As described above, according to the method and apparatus for supplying molten glass of the present invention, the following effects can be obtained.

According to the first aspect, the second aspect and the third aspect, the dropping supply interval can be controlled at a desired viscosity without lowering the viscosity of the molten glass.

According to the fourth aspect, the supply can be stopped without contact with the molten glass, so that no defects occur on the glass surface. In addition, the equipment is simple, so the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a problem of a conventional technique.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is a diagram illustrating the operation of the present invention.

FIG. 4 is a diagram for explaining the operation of the present invention.

FIG. 5 is a cross-sectional view showing a molten glass supply device according to a first embodiment of the present invention.

FIG. 6 is a perspective view showing a nozzle of the molten glass supply device according to the first embodiment.

FIG. 7 is a cross-sectional view showing a portion below the nozzle of the molten glass supply device according to the first embodiment.

FIG. 8 is a perspective view showing a modified example of the molten glass supply device according to the first embodiment.

FIG. 9 is a cross-sectional view showing a molten glass supply device according to a second embodiment of the present invention.

FIG. 10 is a sectional view showing a molten glass feeder according to a third embodiment of the present invention.

FIG. 11 is a perspective view showing a nozzle of a molten glass supply device of Example 3.

[Explanation of symbols]

 1 Supply Nozzle 2 Glass Drop 3 Threading 4 Supply Nozzle 5 Glass High Temperature Part 6 Glass Low Temperature Part 7 Cooling Device 8 Glass Gob 9 Nozzle Heater 10 Gas Cooling Nozzle 11 Cooling Member 12 Upper Die 13 Lower Die 14 Holder 15 Centrifugal Holder 16 Receiving 17 Transfer Chuck 18 Rotation motor 19 Crucible heater 20 Molten glass 21 Molten crucible 22 Lower slide table 23 Lower slide table 24 Transfer arm 25 Rotating arm 26 Centrifugal holder mounting shaft 27 Liquid cooling unit 28 Cooling member cooling nozzle

Claims (4)

[Claims] 1. A method of heating and melting glass in a crucible and dropping and supplying it to a receiving member from a supply nozzle, wherein the glass is heated and melted in the crucible to a temperature corresponding to a glass viscosity of 10 ⁵ to 10 ² poises. A step of heating the molten glass in a supply nozzle installed below to a temperature corresponding to a glass viscosity of 5 to 10 ² poise and dropping it in a glass droplet state; and cooling an intermediate portion of the supply nozzle with a cooling jig. Then, a method of supplying molten glass, comprising the steps of stopping the glass dropping and stopping the cooling of the cooling jig and dropping the glass again. 2. The method for supplying molten glass according to claim 1, wherein the glass is cooled by the cooling jig to have a glass viscosity of 10 ⁶ poise or more. 3. A melting crucible for melting glass, a supply nozzle installed at the bottom of the melting crucible, a crucible heater and a supply nozzle heater for independently controlling the temperature of the crucible and the supply nozzle, and a supply nozzle A molten glass supply device, which is installed in an intermediate portion and includes a cooling jig, for cooling the supply nozzle. 4. The cooling jig is cooled by spraying a gas whose temperature is set in advance to an intermediate portion of the supply nozzle, cooling by supplying a liquid whose temperature is preset with a cooling jacket installed in the intermediate portion of the supply nozzle. The molten glass supply apparatus according to claim 3, wherein the molten glass supply apparatus is any one of cooling methods in which a solid having a temperature set in advance is brought into contact with the middle portion of the nozzle.