JPH0741323A - Production of glass gob - Google Patents

Abstract

PURPOSE:To easily obtain a glass gob of desired weight by melting a weighed glass lump in a crucible with the bottom closed and the upper part opened and inclining the crucible at an angle of >=90 deg. to perpendicular to drip the molten glass. CONSTITUTION:A weighed glass pellet is placed in a crucible 1 provided with an injection port at the upper part and heated with a high-frequency heating furnace, etc., to melt the pellet, and molten glass 2 is formed. The whole molten glass 2 in the crucible 1 is discharged by inclining the crucible 1 at an angle of >=90 deg. to perpendicular and dripped on a receiver 4 set below the crucible. The molten glass in the receiver 4 is formed to produce a glass gob. Consequently, since the weight of the formed glass gob is determined by the weight of the glass pellet charged into the crucible 1, a glass gob of any weight is produced.

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 gob used for press-molding a molten glass gob with a pair of dies.

[0002]

2. Description of the Related Art In recent years, as a method of efficiently manufacturing an optical element such as an aspherical lens, a method of press-forming a gob of molten glass with a pair of molds has been used. As a method for producing a gob of molten glass, for example, Japanese Patent Application Laid-Open No. Sho-6-
There is an invention described in the publication 1-146721. As shown in FIG. 7, the apparatus used in the above invention comprises a crucible 71 for melting glass and a nozzle 72 provided at the lower end of the crucible 71.
And heaters 73, 74, 75 arranged around the crucible 71 and the nozzle 72.

In the process of manufacturing a gob using the apparatus having the above structure, first, the molten glass 76 flowing out of the nozzle 72 is discharged.
Becomes a sphere due to surface tension and adheres to the tip of the nozzle 72. Subsequently, the spheres of the molten glass 76 gradually become larger, and finally fall when their own weight exceeds the adhesive force (surface tension) to the tip of the nozzle 72. The sphere of the molten glass 76 that has dropped falls in a receiver 77 that is arranged below the nozzle 72.
Supplied as molten glass gob. The receiver 77 is a lower mold of a molding die, and a lower mold (receiver) on which a gob is placed is conveyed below a corresponding upper mold, and an optical element is manufactured by pressing the upper mold and the lower mold.

[0004]

However, in order to manufacture the gob as in the prior art, the diameter of the nozzle 72 must be below a certain level. This is because when the diameter of the nozzle 72 is too large, the molten glass 76 flows out in a laminar flow and does not become a drop. On the other hand, the weight of the gob is determined by the diameter of the nozzle 72 and the surface tension of the molten glass 76. However, since the nozzle 72 has a diameter restriction, the conventional gob manufacturing method has a drawback that a gob having a certain weight or more cannot be manufactured. That is, as described in the above publication, the maximum weight of the gob is 4 to 5 g for the lanthanum type optical glass and 2 for the heavy flint type optical glass.
It will be limited to ~ 3g.

Therefore, the present invention was developed in view of the above-mentioned drawbacks in the prior art, and an object thereof is to provide a glass gob manufacturing method capable of freely manufacturing a glass gob of any weight.

[0006]

The present invention relates to a method for producing a glass gob in which molten glass is dripped from a crucible, after melting a glass gob measured by a crucible having a closed end at the bottom and an open end at the top. This is a method of inclining the crucible at 90 ° or more with respect to the vertical line.

1 and 2 are conceptual diagrams showing the present invention. As shown in FIG. 1, the crucible 1 has an opening upward, and a weighed glass lump as a molten glass 2 is contained therein. When the crucible 1 is tilted as shown in FIG. 2, the position of the pouring port 3 of the crucible 1 becomes lower than the liquid surface of the molten glass 2 and the molten glass 2 flows out of the pouring port 3 and is placed below. It falls on the container 4.

At this time, the outflow of the molten glass 2 stops when the liquid surface reaches the position of the pouring port 3. Therefore, if the crucible 1 is tilted by 90 ° or more, all the molten glass 2 in the crucible 1 will flow out. become. Therefore, if the molten glass 2 dropped into the receiver 4 is formed into a glass gob, the amount of the gob is determined by the amount of the weighed glass mass initially charged into the crucible 1, and the amount of the gob in the prior art described above. Weight restrictions can be eliminated.

[0009]

Embodiment 1 FIGS. 3 to 5 are sectional views showing the manufacturing process of this embodiment. 11 is a platinum crucible. This crucible 11
A drive arm 12 is attached to the side surface of the. The drive arm 12 can be moved back and forth and can be rotated about its axis.
Holds at 3. When the drive arm 12 is advanced (Fig. 4
High frequency heating furnace 14 is installed at a position where crucible 11 can be inserted therein.
A coil 15 is wound around the outer circumference of 4.

The manufacturing process of the glass gob using the apparatus having the above structure will be described below. The method of this embodiment is composed of a step of melting the weighed glass pellets 16 in the crucible 11 and a step of tilting the crucible 11 by 90 ° or more. In this example, SF11 was used as the glass pellet 16.

First, 10 g of the glass pellet 16 is put into the crucible 11 (see FIG. 3). Next, the drive arm 12 is advanced to insert the crucible 11 into the high-frequency heating furnace 14, and the glass pellets 16 are heated at 1300 ° C. for 3 minutes to be melted to obtain molten glass 17 (see FIG. 4).

Next, the drive arm 12 was retracted to take out the crucible 11 from the high-frequency heating furnace 14, and then the drive arm 12 was rotated to tilt the crucible 11 at an angle of 120 ° and hold the state for 2 seconds. By this operation, all of the molten glass 17 flowed out from the crucible 11 and dropped on the receiver 18 arranged below (see FIG. 5).

The receiver 18 is formed in the lower mold of the molding die, and the dropped molten glass 17 is placed and conveyed under the upper mold (not shown), followed by press molding to solidify by cooling. In this way, when 50 glass gobs were molded and weighed, the weight variation was 10 g ± 5%. Similar results were obtained even when the weight of the glass pellet 16 was 1 g.

As described above, in this embodiment, by changing the weight of the glass pellet, it is possible to manufacture a glass gob having any weight. It should be noted here that it was possible to produce 10 g of glass gob. According to the above-mentioned conventional publication, there is a limitation that the maximum weight of a gob that can be used is 2-3 g for heavy flint type glass.

According to this embodiment, the gob can be manufactured without being restricted by the weight.

[0016]

Second Embodiment FIG. 6 is a sectional view showing the present embodiment. The present embodiment is different in that the electric furnace 21 is connected to the high-frequency heating furnace 14 in the first embodiment, and the other components are the same, and the same components are designated by the same reference numerals. The description is omitted.

Front of the high-frequency heating furnace 14 (right side in FIG. 6)
An electric furnace 21 is connected in series. A hole 21a for dropping (passing) the molten glass 17 is provided in the lower portion of the electric furnace 21.
And a heater wire 22 is provided inside thereof. Further, the electric furnace 21 includes a high frequency heating furnace 1
Shutters 23 are provided at the boundary with 4 and the hole 21a.

To manufacture a gob using the apparatus having the above-described structure, the molten glass 17 heated and melted in the high-frequency heating furnace 14 is conveyed into the electric furnace 21, and the crucible 11 is heated in a high-temperature atmosphere inside the electric furnace 21. To the receiver 18. At this time,
The inside of the electric furnace 21 is in a high temperature atmosphere of 1000 ° C.

When 50 gobs were molded in the same manner as in Example 1, the weight variation of the gobs was smaller than that in Example 1 and was ± 2%. The reason for this is that in Example 1, when the molten glass 17 was caused to flow out of the crucible 11,
This is probably because the crucible 11 was taken out of the high-frequency heating furnace 14 into a normal temperature atmosphere, so that the temperature of the molten glass 17 drastically dropped, resulting in an increase in viscosity and a large amount of glass remaining on the inner wall of the crucible 11.

According to this embodiment, not only can a gob of any weight be manufactured as in the case of the first embodiment, but a gob with higher weighing accuracy can be manufactured.

[0021]

As described above, the glass gob manufacturing method according to the present invention can manufacture glass gobs of any weight.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the present invention.

FIG. 2 is a conceptual diagram showing the present invention.

FIG. 3 is a cross-sectional view showing the manufacturing process of the first embodiment.

FIG. 4 is a cross-sectional view showing the manufacturing process of the first embodiment.

FIG. 5 is a cross-sectional view showing the manufacturing process of the first embodiment.

FIG. 6 is a cross-sectional view showing a second embodiment.

FIG. 7 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 crucible 2 molten glass 3 spout 4 receiver

Claims (1)

[Claims] 1. A method for producing a glass gob in which molten glass is dripped from a crucible, after melting a glass lump measured by a crucible having a closed end at the bottom and an open end at the top, the crucible is 90 ° or more with respect to a vertical line. A method for manufacturing a glass gob, which comprises tilting.