JPH09235122A - Production of glass gob - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a glass gob having a stable small particle diameter to be a preformed material of a fine optical glass element at a high production rate. SOLUTION: A molten glass melted in a melting furnace 1 is discharged from a nozzle 2 as a continuous stream. The flow rate, flow velocity, viscosity, etc., of the molten glass are regulated to thereby change the molten glass flowed down as the continuous stream into a glass gob in the form of droplets falling in one row in the course thereof. The glass gobs falling in the form of droplets in one row are received in a heated oil 4a in a liquid vessel 4 and recovered as the glass gobs. Thereby, the glass gobs having a much smaller diameter than that obtained by directly dropping the molten glass from the nozzle 2 can be obtained. The production rate based on one glass gob is higher than that formed by directly dropping the molten glass from the nozzle 2. Since the continuous stream is not cut with a cutting blade, shear marks, etc., are not formed in the glass gobs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a glass gob as a preform material or a lens used for molding an optical glass element such as a lens or a prism used in an optical device.

[0002]

2. Description of the Related Art In recent years, in order to reduce the cost of optical elements,
Non-polished lenses are manufactured without the polishing step after glass molding. The above-mentioned non-polished lens is manufactured by, in a glass melting furnace, flowing out molten glass from a nozzle, dividing the flowing out glass by some method and cooling to manufacture a glass gob, and then pressing it with a heated mold or the like. It is what is molded.

There are the following two basic methods for dividing the glass flowing out from the tip of the nozzle. One method is a method in which the flow rate of the molten glass flowing out from the tip of the nozzle is narrowed down, the molten glass is dropped from the tip of the nozzle, and a glass gob in the form of droplets is used as a glass gob. Another method is a method in which molten glass is made to flow down from a nozzle as a continuous flow, the glass that has flowed down as a continuous flow is cut by a shear blade or the like and divided, and the divided glass gobs are made into glass gobs.

In the production of the above-mentioned glass gob, the surface of the produced glass gob needs to be in a smooth state free from scratches, stains and wrinkles in order to omit polishing after press molding. For this reason, various proposals have already been made in the production of glass gobs. For example, in the method for producing a glass gob described in Japanese Patent Laid-Open No. 61-146721, by dropping molten glass from the tip of a nozzle and allowing the molten glass to naturally fall until the surface temperature of the glass droplet becomes lower than the softening temperature, It is said that a glass gob having a smooth surface and high weight accuracy can be obtained.

Further, in the glass body forming method described in Japanese Patent Laid-Open No. 2-14839, the molten glass flowing down from the outflow pipe is naturally dropped or cut with a cutting blade to drop the molten glass gob, The glass gob is received by a mold having a recess, and the recess of the mold has pores for blowing out a gas such as air and an inert gas. By blowing out gas from the pores, a gas layer is formed between the molten glass gob and the inner surface of the molding die, and the surface of the molten glass is kept in non-contact with the mold. According to this method, a glass gob without scratches or dirt on the surface can be obtained.

[0006]

By the way, there are some minute optical glass elements, for example, those made of glass bodies of several tens mg to several mg. Such an optical glass element is manufactured by the above-mentioned method. In doing so, it is necessary to divide the molten glass into fine pieces. However, in the method of dropping the molten glass from the nozzle tip and dividing the molten glass, when the molten glass flows out from the nozzle at a small flow rate, the outflowing molten glass first undergoes surface tension (adhesive force) to cause the nozzle tip to flow. The glass drops adhere to the nozzle tip by the molten glass that continuously flows out from the nozzle, and when the weight of the glass drops increases due to surface tension, the glass drops It will be dropped.

Therefore, unless the weight of the glass droplet attached to the tip of the nozzle becomes large to some extent, the molten glass does not drip, so there is a limit to the minimum weight of the glass droplet that can be dropped. It should be noted that the minimum value of the weight of the glass drops that can be dropped seems to vary due to various factors. Further, in the above-mentioned JP-A-61-146721, the nozzle tip diameter is
It is one of the factors that influence the weight of the glass droplet, and the weight of the glass droplet is generally mg = 2πrγ (m: weight, r: nozzle tip diameter, γ:
Surface tension). In the above publication, the glass droplet weight can be reduced by reducing the nozzle tip diameter. However, there is a practical limit to the nozzle tip diameter that can be processed, and the minimum glass droplet weight is 50 mg. However, it is difficult to reduce the weight of the glass gob to several tens of mg or less by the method of dropping the molten glass.

Further, in order to drop the molten glass, it is necessary to adjust the flow rate so that the molten glass does not form a continuous flow, and from one glass drop is dropped until the next glass drop is dropped. As described above, since it takes time for the glass droplets to grow, it takes time to manufacture each glass gob, and there is a problem that the glass gob manufacturing speed is slow. Further, in the method of dropping molten glass, if the weight of the glass droplet attached to the tip of the nozzle becomes large to some extent, the glass droplet will be dropped, so there is a limit to the maximum value of the weight of the glass gob that can be manufactured.

On the other hand, in the method of cutting and dividing the continuous flow of molten glass flowing out of the nozzle by the above-mentioned shear blade (cutting blade) or the like, JP-A-2-148
As described in Japanese Patent No. 39, a larger molten glass gob can be obtained as compared with the case where the molten glass is dropped and divided.

However, in the division by cutting, for example, the shear blade comes into contact with the molten glass flow, and when the molten glass is divided into small pieces, the divided molten glass adheres to the shear blade. Since problems may occur and the shear blade needs to be operated with high accuracy, the division of molten glass by cutting is not suitable for the production of small-sized glass gobs. Further, in the division of the molten glass by cutting, since a shear mark occurs on the glass gob,
There is a problem in the smoothness of the surface of the glass gob as compared with the case where the molten glass is dropped.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass gob manufacturing method capable of easily manufacturing a glass gob having a small particle diameter with high weight accuracy and at a high production rate. It is what

[0012]

According to a first aspect of the present invention, there is provided a glass gob manufacturing method, wherein molten glass is flown out from a nozzle, the outflowing molten glass is divided into glass gobs, and the glass gobs are manufactured from the glass gobs. The molten glass is caused to flow out from the nozzle as a continuous flow, and after the molten glass flowing out as the continuous flow is changed into a glass mass in the form of droplets during the flow, it is necessary to collect these glass masses, respectively. And the solution.

That is, in the method for manufacturing a glass gob of the present invention, even if the molten glass is divided by dropping the molten glass from the tip of the nozzle, the continuous flow of the molten glass flowing out from the tip of the nozzle is cut by a shear blade or the like. It is not a thing, but the molten glass is made to flow down from the tip of the nozzle as a continuous flow, and when the continuous flow of the molten glass changes into droplets due to surface tension, these glass aggregates in the droplet form are collected.

When the liquid is made to flow down as a continuous flow in a substantially laminar flow state, when the liquid flows down to a certain extent as a continuous flow, the continuous flow becomes a turbulent state due to the resistance of air, the surface tension of the liquid, etc. It is known that a large number of liquid droplets and droplets are formed, and by adjusting the flow rate of the liquid that flows down at this time, when the liquid has flowed down to some extent, the continuous flow drops in a line due to surface tension. It is known to result in uniform droplets.

As a result of the earnest test research, the present inventor has found that even when the molten glass flows out from the nozzle, by adjusting the flow rate, the flow rate, etc., the glass flowing down as a continuous flow from the nozzle drops in a row. It has been found that it can be transformed into a glass lump in the shape of a glass, and that the glass lump in the form of droplets can be effectively used as a glass gob. Then, the molten glass, which has changed into a droplet shape after flowing down from the nozzle as a continuous flow, is not in a state of being adhered to the nozzle. It is possible to make a glass drop having a small particle diameter more easily than when the molten glass is dropped from the tip of the nozzle.

Therefore, by collecting the molten glass that has changed into a droplet-like glass gob that drops in a row from the continuous flow, a glass gob that becomes a glass gob with a small particle size suitable for manufacturing a fine optical glass element can be easily obtained. Can be obtained. Further, the continuous flow of the molten glass is not broken into a large number of droplets due to air resistance or the like, but by adjusting the flow rate, the flow velocity, the viscosity, etc. of the continuous flow of the molten glass flowing out from the nozzle, When the continuous flow is changed to the droplets that drop in a row, the droplets are in a relatively homogeneous state, and the glass gob having substantially the same weight can be obtained with relatively high accuracy.

Further, when the molten glass is dropped from the tip of the nozzle, as described above, a certain interval is required after one glass drop is dropped until the next glass drop is dropped. It takes a long takt time to produce a glass gob, but when the continuous flow of molten glass is changed to a droplet-like glass block, the continuous flow changes to a droplet-like glass block almost continuously. Therefore, after one glass gob is formed, it takes almost no time until the next glass gob is formed, and the glass gob can be manufactured with a short tact.

In the production of the above glass gob, the production apparatus basically requires a melting furnace for melting the glass and a nozzle for letting out the melted glass. The shapes of the melting furnace and the nozzle are required. The configuration and the like are not particularly limited, and known ones can be used. In addition, since the molten glass is allowed to flow down naturally without using external power, the flow rate and flow rate of the molten glass depend on the temperature of the melting furnace, the temperature of the nozzle, and the path (conduit) from the melting furnace to the nozzle. Temperature, the amount of molten glass in the melting furnace (height of the liquid surface), the inner diameter of the conduit or nozzle, the composition of the glass, and the like.

Further, the conditions of the flow rate and the flow rate include the temperature of the melting furnace, the temperature of the nozzle, and the temperature of the conduit. This is because the viscosity of the molten glass changes depending on the temperature. That is, the temperature of the molten glass changes depending on the temperature of each part, and the viscosity of the molten glass changes, which affects the flow rate and flow velocity of the molten glass. Also,
In order for the continuous flow of molten glass to change into a glass mass in the form of drops that drop in a row, the viscosity of the glass also has an effect, and it is possible to adjust the viscosity of the glass when it flows down as a continuous flow. Preferably, this can be achieved by adjusting the temperature as described above.

Therefore, it goes without saying that the temperature of the melting furnace can be controlled in the glass gob manufacturing apparatus.
It is preferable to be able to control the temperature of the conduit and nozzle. Further, the temperature of the nozzle or the conduit may be controlled by heating from the outside, or the nozzle may be heated by directly energizing the nozzle.

By controlling the temperatures of the nozzle and the conduit, the viscosity of the molten glass can be controlled, and
The flow rate and the flow rate can be changed in accordance with the change in the viscosity of the molten glass, and the conditions for changing the molten glass from the continuous flow into the droplet-shaped glass gobs that are dropped in a row can be adjusted. The composition of the glass used here is
Although not particularly limited, since the viscosity varies depending on the composition of the glass, there is a possibility that the conditions for changing the molten glass from the continuous flow into the droplet-shaped glass lumps that are dropped in one row may be different.

In the glass gob manufacturing method according to claim 2 of the present invention, the inner diameter of the nozzle tip portion is 0.1 to 0.1 mm.
It was set to 5.0 mm as a means for solving the above problems. As described above, when changing the continuous flow of the molten glass into droplet-shaped glass gobs that drop in a row, increasing the diameter of the continuous flow of the molten glass, that is, increasing the inner diameter of the nozzle,
If the flow rate when the molten glass is made to flow out from the nozzle as a continuous flow is large, the continuous flow remains as it is for a long distance, so it is difficult to collect it as a glass gob without cutting the continuous flow. Is.

Further, even if it may change into droplets after flowing down as a continuous flow over a long distance, a long fall distance is required, so that it is practically difficult to collect it as a glass gob. Therefore, when the inner diameter of the nozzle is larger than 5 mm, it is practically difficult to collect the glass gob as a droplet-like glass block for the reason described above. It is preferable that

If the diameter of the continuous flow of the molten glass is made small, that is, if the inner diameter of the nozzle is made small, the flow rate when the molten glass flows out from the nozzle becomes extremely small, and it is difficult to obtain the continuous flow. Therefore, if the inner diameter of the nozzle is smaller than 0.1 mm, a continuous flow cannot be obtained, and due to surface tension, molten glass is attached to the tip of the nozzle as glass droplets, and a glass lump with a small weight is obtained as described above. Absent.

In the method for manufacturing a glass gob according to claim 3 of the present invention, the viscosity of the molten glass flowing out from the nozzle is log η = 0.01 to 3.0, which is a means for solving the above problems. When changing the continuous flow of molten glass into droplet-shaped glass gobs that fall in a line as described above,
When the viscosity of the molten glass is large, for example, when using a glass having a high viscosity composition and the temperature of the molten glass when flowing out from the nozzle is low,
There is a possibility that the molten glass flowing out as a continuous flow cannot be changed into droplets due to the effect of surface tension.

Therefore, the viscosity of the outflowing glass is log η =
When it is more than 3.0, it is difficult to collect the glass gob as a droplet-shaped glass block, and the viscosity of the outflowing glass is l.
It is preferable that og η = 3.0 or less. Further, in order to efficiently change the continuous flow of molten glass into a glass mass in the form of liquid droplets by the action of surface tension, the viscosity of the outflowing glass is
It is more preferable that ogη = 2.0 or less.

When the viscosity of the outflow glass is low,
It takes time to solidify, and the drop distance must be lengthened in order to cool the glass gobs that have changed into droplets and cool them to some extent during the fall to make them harder. It will be difficult. Further, there is a limit to lowering the viscosity of the molten glass, and in order to lower the viscosity more than necessary, the temperature of the outflow glass needs to be extremely high, which is a problem in terms of equipment and cost. Therefore, the viscosity of the outflowing glass is preferably log η = 0.01 or more.

In the method for producing a glass gob according to claim 4 of the present invention, after the molten glass flowing out from the nozzle as a continuous flow is changed into a glass mass in the form of liquid droplets during the flow, the glass mass is treated with water or oil. The above-mentioned problem was solved by dropping it into a liquid such as the above and collecting it. As described above, when the molten glass is made to flow out in a continuous flow state and then changed into glass droplets, the falling distance of the molten glass may become long, and thereby the falling speed of the glass gob also increases. In this case, if a glass drop is received by a receiving mold or the like, a large impact force may be applied to the glass drop and the glass drop may be deformed.

Therefore, when collecting the molten glass that has changed into a droplet after flowing out as a continuous flow, it is preferable to drop the molten glass into the liquid so as not to give an impact to the glass lump and to collect the glass. Incidentally, when a glass lump of relatively high temperature is dropped into the liquid, if the temperature difference between the glass lump and the liquid is extremely large, the glass lump may be cooled rapidly and adversely affected, A liquid having a relatively high boiling point is selected as the liquid, the temperature difference between the liquid and the glass gob is reduced by heating the liquid, or the glass gob is dropped over a long distance to radiate heat to form a glass gob. It is preferable to cool to reduce the temperature difference between the liquid and the glass gob.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Here, before explaining the method for manufacturing the glass gob of the example of this embodiment,
The manufacturing apparatus used for the method for manufacturing the glass gob will be described. This manufacturing apparatus is used experimentally to try the method for manufacturing the glass gob of the present invention, and the method for manufacturing the glass gob of the present invention is the manufacturing method. It is not limited to using the device.

FIG. 1 shows a manufacturing apparatus for experimentally manufacturing a glass gob using the method for manufacturing a glass gob of the present invention. As shown in FIG. 1, a glass gob manufacturing apparatus used in a glass gob manufacturing method according to an example of this embodiment includes a melting furnace 1 for melting glass, a nozzle 2 for letting out molten glass A, and a melting furnace. Pipe 3 that serves as a path (conduit) for molten glass from the nozzle to the nozzle
And a liquid tank 4 for receiving the molten glass A flowing out from the nozzle 2.
And

The melting furnace 1 comprises a platinum crucible 5 serving as a container for melting glass, a furnace body 6 made of a heat-resistant material for covering the crucible 5, and a furnace body 6 disposed on the bottom of the furnace body 6. A pedestal 7 that supports the crucible 5, and thermocouples 8, 9, and 10 for measuring the temperature of the crucible 5 at three heights (upper, middle, and lower).
And a stirring propeller 11 for stirring the molten glass A in the crucible 5, and a heating device (not shown).

The melting furnace 1 is a well-known one capable of melting glass and controlling heating so that the temperature of the molten glass A can be maintained at a predetermined temperature. The pipe 3 serving as the conduit is provided with a heating device (not shown) so that the temperature of the pipe 3 can be controlled. By controlling the temperature of the pipe 3, the viscosity of the molten glass in the pipe 3 can be controlled and the flow rate of the molten glass A in the pipe 3 can be controlled.

The nozzle 2 is, for example, as shown in FIG.
A cross-sectional shape as shown in (B) and (C) can be used. The nozzle 2 shown in FIG. 2 basically has a conical shape in which the tip of the nozzle 2 becomes narrower toward the tip, and an outlet 2a through which molten glass flows out is formed at the tip of the conical tip. Has been done.

In the nozzle 2A shown in FIG. 2 (A), the wall thickness of the conical tip portion is formed so that it becomes thinner toward the tip. In FIG. 2 (B) (C), The thicknesses of the tip portions of the nozzles 2B and 2C are substantially uniform. Further, as compared with the nozzle 2B shown in FIG. 2 (B), the nozzle 2C shown in FIG.

Further, the nozzle 2 is provided with a heating device (not shown) so that the temperature of the nozzle 2 can be controlled, and the molten glass A flowing out from the tip of the nozzle 2 is provided.
The temperature of the molten glass A can be controlled to control the viscosity of the molten glass A. In addition, the nozzle 2 preferably has an inner diameter at its tip of 0.1 to 5.0 mm.

Further, by changing the inner diameter of the tip of the nozzle 2, it is possible to adjust the flow rate and the flow rate, and to change the particle size (weight) of the glass lumps in which the continuous flow has changed into droplets. That is, by reducing the inner diameter of the tip of the nozzle 2,
You can get a small glass gob. The liquid tank 4 contains cylinder oil 4a, and a heating device (not shown) is provided so that the cylinder oil 4a can be heated.

The liquid tank 4 drops the glass gob into the cylinder oil 4a to absorb the impact by the cylinder oil 4a and cool the glass gob to recover the glass gob as a glass gob. Further, the glass gob radiates heat during the fall, but since it is still in a relatively high temperature state, when it falls into the liquid tank 4, it will be affected by the temperature difference, By heating the cylinder oil 4a in the liquid tank, the temperature difference can be reduced and the influence of the temperature difference can be minimized.

In the glass gob manufacturing apparatus, the molten glass A can be basically supplied to the nozzle 2 and
The flow velocity and flow rate of the molten glass A flowing out of the nozzle 2 are
For example, the temperature of the molten glass A can be controlled within a certain range by controlling the temperature, and the nozzle 2
The viscosity of the molten glass flowing out from the molten glass can be adjusted within a certain range by controlling the temperature of the molten glass A, and the inner diameter of the tip of the nozzle 2 is 0.1 to 5.0.
The structure is not limited as long as it is in the range of mm.

For example, although the crucible 5, the pipe 3, the nozzle 2 and the like are made of platinum in consideration of the influence on the molten glass A, these are not necessarily limited to platinum. The flow velocity and flow rate of the molten glass A also change depending on the height of the upper surface of the molten glass A in the crucible 5 and the diameter of the pipe 3, but the flow rate and the flow rate of the molten glass A flow out from the nozzle 2 in combination with the adjustment of the temperature as described later. The shape of the crucible 5, the amount of the molten glass A in the crucible 5, the inner diameter of the pipe 3 and the like are not limited as long as the continuous flow of the molten glass A can be changed into a droplet shape.

Further, as each of the above-mentioned heating devices, an electric heater by electricity or a device for heating by combustion of gas or the like can be used, but the pipe 3 and the nozzle 2 portion can be heated by directly supplying electricity. It is preferable that Further, the molten glass A can be heated in the melting furnace 1, the pipe 3 and the nozzle 2, but the viscosity of the molten glass A when flowing out from the tip of the nozzle 2 is log η =
The heating is preferably performed so as to be 0.01 to 3.0.

In the melting furnace 1, even if the molten glass A melted in the crucible 5 is supplied to the nozzle 2 in a batch system, the molten glass A can be added to the crucible 5 continuously so that the molten glass A can be continuously supplied to the nozzle 2. May be supplied to The liquid contained in the liquid tank 4 is
Although not limited to the cylinder oil 4a, the liquid is
Since only the boiling point can be heated, a liquid having a relatively high boiling point and easy to handle is preferable in order to reduce the temperature difference from the falling glass gob. Also, if the falling distance of the glass gob is lengthened, the glass gob will radiate heat and the temperature of the glass gob will drop, so that the temperature difference can be made small even if a liquid having a relatively low boiling point is put in the liquid tank. It is also possible to use water instead of cylinder oil.

When collecting the falling glass gob, the glass gob may be sprayed with a liquid such as shower water, sprayed with a liquid such as water, or blown with air. May be cooled. Further, when receiving the falling glass lump, it is not always necessary to receive the glass lump in the liquid, and the glass lump may be received by various receiving members. Alternatively, the receiving surface of the receiving member may be an inclined surface or a curved inclined surface so that the glass gob may be received by rolling.

Further, the receiving member may be cooled or heated. A heat-resistant elastic member may be used as the receiving member. Further, the falling speed of the glass gob may be reduced by air and then the glass gob may be received by the receiving member. Next, a method of manufacturing a glass gob using the above manufacturing apparatus will be described.
First, in the melting furnace 1, the glass is melted to obtain a molten glass A.

Next, the molten glass A is guided from the pipe 3 to the nozzle 2, and the molten glass A is flown out from the nozzle 2. At this time, by adjusting the heating temperatures of the melting furnace 1, the pipe 3, and the nozzle 2, the molten glass A flows out from the nozzle 2 as a continuous flow, and before the molten glass A reaches the liquid tank 4, the continuous flow of the molten glass A is generated. The viscosity, flow rate, etc. of the molten glass A are adjusted so as to change into a glass mass in the form of droplets. That is, when the molten glass A is dripping from the tip of the nozzle 2, for example, the heating temperature of the melting furnace 1, the pipe 3, the nozzle 2, and particularly the pipe 3 is increased so that the molten glass A flows from the nozzle 2. The flow rate and the flow velocity of the molten glass A are increased so that the molten glass A flows out as a continuous flow.

Further, the molten glass A flowing out from the nozzle 2
When the molten glass A reaches the liquid tank 4 in a continuous flow, the heating temperature of the melting furnace 1, the pipe 3, the nozzle 2, especially the pipe 3 is lowered to lower the flow rate and flow velocity of the molten glass A, or The heating temperature of the portion is increased to control the viscosity of the molten glass A and the like. In some cases, the distance from the nozzle 2 to the liquid tank 4 is lengthened to check whether or not the continuous flow is in the form of droplets further downward from the nozzle 2 and changes to droplets further downward. In this case, the position of the liquid tank 4 is below the position where the continuous flow is in the form of droplets.

Once the conditions for the continuous flow to be in the form of droplets are determined, thereafter, the temperatures of the melting furnace 1, the pipe 3 and the nozzle 2 are set so that the conditions are satisfied, and the temperature of the glass gob is maintained. Manufacture. Further, the temperature of the liquid tank 4 is determined in accordance with the temperature of the molten glass A that drops into the liquid tank 4 after flowing as a continuous flow from the nozzle 2 and drops into the liquid tank 4. In this case, when the temperature of the molten glass A falling into the liquid tank 4 is extremely higher than the boiling point of the liquid in the liquid tank 4 and the temperature difference between the molten glass A and the liquid in the liquid tank 4 is extremely large, , The liquid in the liquid tank 4 is exchanged with a liquid having a higher boiling point, and the temperature of the liquid in the liquid tank 4 is raised to reduce the temperature difference with the falling glass lump, or the position of the liquid tank 4 is set downward. After the temperature of the falling glass lump has cooled to some extent, the glass lump falls into the liquid tank 4.

Further, once the temperature of the liquid in the liquid tank 4 is determined, the temperature of the liquid in the liquid tank 4 is set to the determined temperature in the subsequent glass gob manufacturing. The above-mentioned respective temperatures need to be set again when, for example, the inner diameter of the tip of the nozzle 2 is changed, the composition of the molten glass A is changed, or the desired particle diameter of the glass gob is changed. .

Then, by setting the above-mentioned conditions, the molten glass A flowing out from the nozzle 2 as a continuous flow is changed to the liquid tank 4
Before reaching, the molten glass A is caused to flow out from the nozzle 2 in a state where it changes into a droplet-shaped glass gob, and the glass gob is dropped into the liquid tank 4 to be collected and dropped into the liquid tank 4. The glass drop is made into a glass gob. That is, the molten glass A is not dropped from the tip of the nozzle 2, and the molten glass A flowing out from the tip of the nozzle 2 as a continuous flow is not cut by a cutting blade such as a shear blade.
By collecting these glass gobs at the stage where the continuous flow has changed into glass gobs in the form of droplets, it is possible to collect the molten glass in a divided state.

Further, the glass gob made of the glass lumps thus collected can have a smaller particle diameter than that of the case where the molten glass is dropped from the tip of the nozzle 2, and a small optical glass element is formed. It can be preferably used in this case. Further, since the cutting is not performed by the cutting blade, shear marks are not formed on the glass gob, and the glass gob having a smooth surface can be obtained.

In addition, unlike the case where a glass drop is dropped from the tip of the nozzle, it does not take time from the dropping of one glass drop to the dropping of the next glass drop. Since the molten glass A that has flowed down changes into droplets almost continuously, a glass gob can be manufactured with an extremely short tact. Further, when the continuous flow of molten glass is changed into glass droplets that drop in a row while flowing down, each glass lump becomes a relatively homogeneous state, and a glass lump of approximately the same weight can be obtained. it can.

[0052]

EXAMPLES Examples of the glass gob manufacturing method of the present invention will be described below. (Example 1) As a glass gob manufacturing apparatus, the one shown in FIG. 1 described in the embodiment of the present invention was basically used.

The platinum crucible 5 in the melting furnace had an internal volume of 8 liters. Further, as the platinum pipe 3, a rear end portion 3a joined to the bottom portion of the melting furnace has an inner diameter of 12 mm, and a tip portion 3b where the nozzle 2 is formed has an inner diameter of 6 mm. That is, the tapered platinum pipe 3 was used. Further, the nozzle 2 has a shape shown in FIG.
The one with 0.33 mm was used.

Heavy lanthanum flint glass [Ohara Co. L
-LAH53] was used. Also, about 5 m below the nozzle 2.
The liquid tank 4 was placed at the position, the cylinder oil 4a was put in the liquid tank 4, and the cylinder oil 4a was heated to about 150 ° C. In this state, 26 kg of the above glass
Was charged into a platinum crucible 5 and heated and melted.

The furnace temperature after heating and melting was 1050 ° C., the temperature of the platinum pipe rear end 3a was 1050 ° C., the temperature of the platinum pipe tip 3b was 1100 ° C., and the nozzle 2
The temperature of the tip was kept at 1210 ° C. Further, the outflow amount (flow rate) of the molten glass A from the nozzle 2 in the above state is
It was 1.5 kg to 1.6 kg / hr.

When the liquid level in the platinum crucible 5 is lowered due to the outflow of the molten glass, the outflow rate is reduced. However, the outflow rate is about one hour after the outflow starts. Is. Further, in this experiment, the furnace temperature and the temperature of the platinum pipe 3 and the nozzle 2 were held constant, but the outflow rate can be changed by changing each temperature, and By increasing the temperature in response to the decrease in the liquid level in the platinum crucible 5,
It is also possible to stabilize the outflow.

The temperature (glass temperature) of the molten glass A immediately after flowing out from the tip of the nozzle 2 was 1090 ° C. In addition,
Although the temperature of the tip of the nozzle 2 is 1210 ° C., the temperature of the platinum pipe 3 is 1050 ° C. to 1100 ° C., and the temperature of the molten glass A passing through the tip of the nozzle 2 in a short time is The temperature never rises.

A radiation thermometer [Model TR420 manufactured by Minolta Co.] was used to measure the temperature of the molten glass A immediately after flowing out. When measuring the temperature of the molten glass that had flowed out, the glass that flowed out was received on a stainless steel plate, and the temperature of the molten glass that had accumulated in the plate was measured. Moreover, from the viscosity curve of the heavy lanthanum flint glass shown in FIG.
The viscosity of the molten glass A immediately after flowing out at 090 ° C is log
It was determined that η = 0.12.

The molten glass A flowing out of the nozzle 2 under the above conditions flows down as a continuous flow up to about 10 mm below the tip of the nozzle, and below that,
It changed into glass lumps in the form of droplets that were continuously arranged in a line and fell as glass lumps. Then, the glass gob further dropped into the liquid tank 4, and the cylinder oil 4 a absorbed the impact and cooled, and was collected in the liquid tank 4.

Further, the glass gob collected from the liquid tank 4, that is, the glass gob was washed. When the glass surface was observed under a microscope, the glass surface was in a smooth state without defects such as scratches and wrinkles. Then, the collected glass gob (glass gob) was ready for use as an optical material for mold press.

As a result of inspecting 300 obtained glass gobs, the particle size of the glass gobs was 1.22 to 1.25 m.
m and the weight were 4.2 to 4.5 mg, and a glass gob having a relatively stable particle size could be obtained. Further, the weight of the obtained glass gob was smaller than several tens of mg as described above, and the glass gob having an extremely small particle size could be easily obtained.

Example 2 A glass gob was manufactured by a method similar to that of Example 1 above. The difference from Example 1 is that the nozzle 2 used has the shape shown in FIG. 2B and the inner diameter of the tip is 0.55 mm, and the heating temperature of the nozzle 2 and the platinum pipe 3 is changed. The temperature of the glass (glass temperature) immediately after flowing out of the nozzle 2 was set to 1120 ° C., and by changing the diameter of the nozzle 2 and the heating temperature of the nozzle 2 and the platinum pipe 3, the amount of molten glass A flowing out was changed. 3.5-
This is the point at which it became 4.0 kg / hr. In addition, from the viscosity curve of the heavy lanthanum flint glass shown in FIG.
Of the molten glass A immediately after flowing out of log η = 0.
It was judged as 06.

When the molten glass A is caused to flow out from the nozzle 2 under such conditions, the molten glass A flows down from the tip of the nozzle 2 as a continuous flow and then falls in a line, as in the case of the first embodiment. It changes into a droplet-like glass block that
The glass gob fell into the liquid tank 4. Then, after washing the glass gob collected from the liquid tank 4, that is, the glass gob,
When the glass surface was observed under a microscope, the glass surface was in a smooth state without defects such as scratches and wrinkles.

Then, the collected glass gob (glass gob) was ready for use as an optical material for a mold press, as in Example 1. In addition, as a result of inspecting 300 obtained glass gobs, the particle size of the glass gobs is 1.45 to 1.55 mm and the weight is 7.0 to 8.6.
It was mg, and a glass gob having a relatively stable particle size could be obtained.

Further, the weight of the obtained glass gob was smaller than several tens of mg as described above, and the glass gob having an extremely small particle size could be easily obtained. Furthermore, the results of Example 1 and Example 2 are as follows:
By changing the heating temperature of the nozzle 2 and platinum pipe 3,
It is shown that the particle size (weight) of the obtained glass gob can be changed, and it is also possible to obtain the glass gob having a desired particle size (weight).

[0066]

According to the method for producing a glass gob according to the first aspect of the present invention, the molten glass is not dropped from the tip of the nozzle, and the molten glass flowing out as a continuous flow from the tip of the nozzle is not cut. At the stage where the molten glass flowing out as a continuous flow from the tip changed into a glass mass in the form of droplets, since the glass mass is collected as a glass gob,
The shear mark is not generated by cutting, and the manufacturing time per glass gob can be shortened as compared with the case where molten glass is dripped at the nozzle tip.

Further, when the molten glass flowing out from the nozzle tip as a continuous flow is changed into a droplet-shaped glass gob that drops in a row, when the glass gob is collected as a glass gob, the molten glass is blown from the nozzle tip. When dropped,
A glass gob having a small particle size and a stable particle size can be easily obtained as compared with the case where the molten glass flowing out from the nozzle tip as a continuous flow is cut.

According to the glass gob manufacturing method of the second aspect of the present invention, the inner diameter of the nozzle tip is 0.1 to 5.0.
By setting the thickness to mm, it becomes possible to easily change the molten glass flowing out as a continuous flow from the nozzle tip into a glass mass in the form of droplets, and it is possible to obtain a glass gob having a relatively stable particle diameter. .

According to the glass gob manufacturing method of the third aspect of the present invention, the viscosity of the glass flowing out from the nozzle tip is set to log η = 0.01 to 3.0, so that the glass flows out from the nozzle tip as a continuous flow. It becomes possible to easily transform the molten glass into a glass mass in the form of liquid droplets, and
It is possible to obtain a glass gob having a relatively stable particle size.

According to the method for producing a glass gob according to claim 4 of the present invention, by dropping the glass gob in the form of liquid drops into the liquid, the falling glass gob is not subjected to a large impact, and the glass due to the impact is dropped. It is possible to collect the glass gob while preventing the deformation of the lump.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a glass gob manufacturing apparatus used in a glass gob manufacturing method according to an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a nozzle of a glass gob manufacturing apparatus used in the glass gob manufacturing method of the above example.

FIG. 3 is a drawing showing a viscosity curve of heavy lanthanum-flint glass for judging the viscosity of molten glass that has flowed out in the method of manufacturing a glass gob of the above example.

[Explanation of symbols]

 1 Melting furnace 2 Nozzle 3 Pipe (conduit) 4 Liquid tank

Claims (4)

[Claims] 1. A method for producing a glass gob for producing a glass gob from a glass gob by dividing the molten glass into a glass gob by letting the molten glass flow out from a nozzle, and letting the molten glass flow out as a continuous flow from the nozzle. A method for producing a glass gob, which comprises recovering each of the glass gobs after the molten glass flowing out as a continuous flow has changed into a glass gob of a droplet form during the flow. 2. The inner diameter of the nozzle tip portion is 0.1-5.
It is 0 mm, The manufacturing method of the glass gob of Claim 1 characterized by the above-mentioned. 3. The method for manufacturing a glass gob according to claim 1, wherein the viscosity of the molten glass flowing out from the nozzle is logη = 0.01 to 3.0. 4. After the molten glass flowing out from the nozzle as a continuous flow is converted into a glass mass in the form of liquid droplets during flowing,
The glass gob manufacturing method according to claim 1, wherein the glass gob is dropped into a liquid such as water or oil to be collected.