JPH0686298B2 - Glass material forming equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass material having an airtight structure for guiding molten glass from a crucible through an outflow nozzle to a clean room containing a molding die. The present invention relates to a molding device.

(Prior Art) In recent years, a method for molding a high-precision optical element that does not require post-processing such as grinding and polishing by accommodating a glass material in a molding die having a predetermined surface accuracy and performing press molding. Is being developed.

When molding such an optical element, the molding equipment is maintained in a specific atmosphere such as non-oxidizing to prevent deterioration of the molding die, and molding is performed to ensure the surface accuracy of the molded product. The area around the equipment must be kept clean.

Therefore, in glass molding in a non-oxidizing atmosphere such as N ₂ , the entire molding apparatus including the melting furnace as described above is placed in the predetermined atmosphere as described above, or the periphery of the molding apparatus is kept clean. For this purpose, the entire apparatus including the glass melting furnace is placed in a clean room for molding, or the molding surface is blown off with air or the like immediately before molding to remove dust and the like from the surface.

In general, dust and the like attached to the surface of a molded product are often generated mainly from the refractory itself of the glass melting furnace. Therefore, it is difficult to prevent dust or the like generated from the furnace itself by a method of forming a room in a predetermined atmosphere by using a room that surrounds the entire molding apparatus including the glass melting furnace. Moreover, since the chamber surrounds the glass melting furnace and the entire molding apparatus, the apparatus becomes large in size and the cost increases. Further, in this method, the size of the melting furnace used is limited, and it becomes difficult to use a large melting furnace.

Further, the method of blowing off the surface of the mold with air or the like immediately before molding to remove dust and the like from this surface cannot be expected to have any effect when the atmosphere itself is contaminated with dust or the like.

Therefore, a method was proposed in which a crucible was placed outside the clean room, and the molten glass in this was introduced into the clean room via a nozzle and supplied to the molding die, but here it was heated to keep it warm. With the heat transfer from the nozzle
It is necessary to prevent the airtightness of the airtight holding means in the clean room from being thermally deteriorated.

The present invention is made on the basis of the above circumstances, even if the nozzle is heated to keep the temperature of the molten glass passing therethrough, the connection point with the airtight holding means is not thermally affected, and An object of the present invention is to provide a glass material molding apparatus having a structure capable of preventing the hermeticity from being thermally damaged.

(Means for Solving Problems) Therefore, in the present invention, as shown in the drawings, a melting means 1 including a crucible 3 for melting a glass material, and molten glass from the crucible are received to form a molded product. Glass forming means 17 and means for keeping the glass forming means in an airtight state
11 and a glass introducing nozzle 5 extending from the crucible 3 is introduced into the glass forming means from the center of the opening provided in the airtight holding means, and the center of the seal plate 7 that shields the opening causes The nozzle is held, and the seal plate 7 and the nozzle 5 are made of the same material.

(Operation) Therefore, the nozzle 5 penetrating the seal plate 7 is effectively used for feeding the molten glass from the outside (crucible) to the glass forming means 17 housed in the airtight holding means 11, and accordingly, Even if the nozzle 5 is heated to keep the molten glass passing therethrough, heat is transferred to the connection point between the seal plate 7 and the airtight holding means 11 through the seal plate 7, so that heat is radiated during this period. Thus, it is possible to prevent the airtightness of the peripheral portion of the seal plate from being thermally damaged.

(Example) Hereinafter, the Example of this invention is described, referring drawings.

(First Embodiment) FIG. 1 is a schematic sectional view showing the overall configuration of the first embodiment of the present invention.

Reference numeral 1 is a main body of a melting furnace as a melting means composed of refractories such as fibers. Molten glass 4 in this melting furnace
A platinum crucible 3 for accommodating the above and a melting superheater 2 installed around the crucible are provided. A platinum nozzle 5 is provided below the crucible 3, and the molten glass 4 in the platinum crucible 3 flows down through the nozzle 5. Reference numeral 6 is a heater for overheating provided around the nozzle 5.

Below the outlet of the nozzle 5, there is provided a press molding device 16 having a molding die 17 that performs a lateral pressing operation. The molding die 17 as a glass molding means is composed of a pair of mold members 17a and 17b which are opened or pressed to the left and right, and the glass fluid 18 flowing out from the nozzle 5 is made to flow down between the mold members in the open state.

A molding apparatus 16 having such a mold member 17 is surrounded by an airtight cover 11 as airtight holding means, and the entire molding apparatus is shielded from the outside atmosphere. This airtight cover
At 11 is provided an inlet 12 for introducing the atmosphere adjusting gas and an outlet 14 for discharging the same. Reference numerals 13 and 15 are valves provided at the inlet 13 and the outlet 14.

A platinum seal plate 7 as a nozzle holding member is provided in the opening on the upper surface of the airtight cover 11 as a nozzle holding member which is fixedly held to the airtight cover 11 by a fixing jig 10 having a U-shaped cross section by bolt fastening, for example. There is. This seal plate 7
A nozzle 5 having a front end opened in the vicinity of the mold member 17 in the airtight cover 11 is firmly attached to the nozzle by welding. Since both the seal plate 7 and the nozzle 5 are made of platinum as described above, they are well welded to each other, and the airtightness of the airtight cover 11 does not occur in the welded portion without causing a chemical reaction such as fusion. Is also held.

In this embodiment, an O-ring 9 as an airtight holding member for holding the airtightness inside the airtight cover 11 is provided between the seal plate 7 and the airtight cover 11.
The airtightness inside 11 is secured. Further, cooling means 9 is provided between the seal plate 7 and the fixing jig 10. The cooling means 9 circulates low-temperature water as a cooling medium to prevent the O-ring 9 from being damaged by the temperature rise of the nozzle 5.

In order to use the apparatus of this embodiment configured as described above, a predetermined glass raw material is charged into the crucible 3 through the opening (not shown) of the melting furnace 1, and then the opening is closed, and then the superheater 2 is heated. The glass raw material in the crucible 3 is melted and clarified by performing energization, and a molten glass 4 is produced by performing a cell bubble operation. At the same time as this work, the heater 6 for overheating the nozzle 5
Also, when the molten glass 4 reaches the tip of the nozzle 5 by energizing, the energization of the overheating heater 6 is stopped, and the glass in the nozzle 5 is once solidified. After that, the valves 13 and 15 are opened, normal air is fed into the cover 11 through the inlet 12, and exhausted through the outlet 14. Then, after the inside of the airtight cover 11 has been sufficiently cleaned, the heater 6 for heating the nozzle 5 is re-energized to heat the heater 5 to heat and soften the molten glass 4 in the nozzle 5 so that the glass fluid flows from the tip of the nozzle 5. Drain 18

The mold member 17 is configured to open and close in the lateral direction as described above, and press-transfers the glass fluid 18 flowing downward from the nozzle 5 by each molding surface of the mold member 17. The mold member 17 is controlled in its operation timing by a controller (not shown) so that the pressing operation is performed after the tip of the glass fluid 18 passes through the molding surface of the mold member 17, and the holding condition is maintained for a certain period of time after the pressing. Due to the temperature difference between 17 and the glass fluid 18, the portion to be molded between the mold members is cooled and solidified.

Reference numeral 19 denotes a shear for cutting the glass fluid 18, which is opened and closed immediately after the mold member 17 presses the glass fluid 18 to cut the glass fluid 18 at a position below the nozzle 5. The glass fluid 18 is continuously made to flow down from the nozzle 5, and after cutting by the shear 19, the mold member 17 is opened and the press molding operation as described above is continuously performed again.

Molded products obtained by such press molding do not have defects such as shear marks that occur when the tip of the glass fluid is press-molded, have good surface accuracy, and there is no contamination of the molded products due to dust or the like. There wasn't.

Second Embodiment Hereinafter, another embodiment of the present invention will be described with reference to FIG.

This embodiment is different from the above embodiment in the heating means of the nozzle 5 and the means for cooling the O-ring 9 for hermetically sealing the seal plate 7 and the hermetic cover 11. That is, as shown in the figure, the electrode plate 21 is fixed to the nozzle 5 and
An energization terminal 22 connected to a power controller (not shown) is attached to the nozzle 21, and the nozzle 5 is directly heated unlike the above-described embodiment to heat the glass fluid 18 in the nozzle 5. Further, the seal plate 7 is attached to the airtight cover 11 by a fixing jig fixed to the airtight cover 11 and having a U-shaped cross section.
The upper and lower sides of the seal plate 7 are sandwiched by 10 and an O-ring 9 is interposed at both upper and lower contact portions. An annular cooling chamber 27 is formed inside the fixing jig 10, and the fixing jig is arranged so that the cooling gas supplied from the outside can be circulated in the cooling chamber 27.
Air inlet pipe 25 on one side and air exhaust pipe on the other side
26 are provided.

Regarding the use of the apparatus of this embodiment, first, the molten glass 4 is made by the above-described method, the electrode plate 21 is energized to heat the nozzle 5, and the molten glass 4 is energized when it reaches the tip of the nozzle 5. And the glass in the nozzle 5 is solidified.
Next, argon gas is gradually injected from an opening (not shown) provided above the airtight cover 11 to fill the entire airtight cover 11 with this argon gas. Then, after closing the opening, the valve 13 is opened to allow a small amount of N ₂ gas to flow in from the inlet 12, the inside of the airtight cover 11 is kept in a non-oxidizing atmosphere, and the nozzle 5 is overheated. The press molding is performed by such an operation. Further, during such an operation, the air introduction pipe 25 and the air discharge pipe 26 are opened to circulate the cooling air in the cooling chamber 27 to prevent the O-ring 9 from being damaged due to the temperature rise and to prevent the inside of the airtight cover 11 from being damaged. Maintains airtightness.

The molded product obtained by such an operation has good surface accuracy as in the above-mentioned embodiment and contamination of the molded product by dust etc. is completely prevented, and the mold member 17 is oxidized by contact with glass during press molding. Was not seen at all.

Third Embodiment Further, another embodiment of the present invention will be described with reference to FIG.

The seal plate 7a in this embodiment is attached to the airtight cover 11 by the cooling means 8 of the type for circulating cooling water inside the seal plate 7a and in the fixing jig 10 as in the first embodiment.

The present embodiment is different from the first and second embodiments in that the seal plate 7a also serves as an electrode plate, and the end portion of the seal plate 7a is the same as in the second embodiment. An electrode plate 21 and an energizing terminal 22 are provided.

Also in this embodiment, the airtightness of the inside of the airtight cover 11 is maintained by welding or the use of the O-ring 9 at each joint, and the O-ring 9 is damaged due to the temperature rise of the seal plate 7a as described above. Is also prevented by the cooling means 8.

Also, the obtained molded product had good surface accuracy and no defects such as dust were observed at all as in the above.

(Effects of the Invention) As described above, according to the present invention, since the molding die member is housed in the clean room in which the airtightness is ensured, the molding die and its periphery are always kept clean. Be done.
Therefore, dust or the like does not adhere to the molded product obtained by such a molding method, which is useful for improving the surface accuracy of the molded product. Further, a nozzle penetrating the seal plate is effectively used for feeding the molten glass from the outside (crucible) to the glass forming means housed in the airtight holding means (airtight cover forming the clean room). Therefore, even if the nozzle is heated to keep the molten glass passing therethrough, heat is transferred through the seal plate up to the connection point between the seal plate and the airtight holding means, so that heat is radiated during this period. It is possible to prevent the airtightness of the peripheral portion of the seal plate from being thermally damaged. As a result, durable and reliable airtightness can be maintained.

Further, by providing a means for cooling the seal plate 7 as the nozzle holding member at the peripheral portion thereof, it is possible to prevent the airtightness of this portion from being impaired by the heat transfer from the nozzle 5 and it is durable. A certain airtightness can be maintained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of a first embodiment of the present invention, FIG. 2 is a schematic sectional view showing an essential part of a second embodiment of the present invention, and FIG. 3 is a schematic view of the present invention. It is a schematic sectional drawing which shows the principal part of 3rd Example. DESCRIPTION OF SYMBOLS 1 ... Melting furnace 2 ... Melting heater 3 ... Platinum crucible 4 ... Molten glass 5 ... Nozzle 6 ... Nozzle heating heater 7 ... Platinum seal plate 7a ... Electrode seal plate 8 ... Cooling means, 9 ... O-ring 10 ... Fixture 11 ... Airtight cover 17 ... Mold 18 ... Glass fluid

Claims (3)

[Claims] 1. A melting means including a crucible for melting a glass material, a glass molding means for receiving a molten glass from the crucible to mold a molded article, and a means for keeping the glass molding means in an airtight state. The glass introduction nozzle extending from the crucible is introduced into the glass forming means from the center of the opening provided in the airtight holding means, and the nozzle is held by the center of a seal plate that shields the opening, and the seal is formed. A glass material forming apparatus, wherein the plate and the nozzle are made of the same material. 2. A glass forming means for receiving a molten glass to form a glass molded article is housed in an airtight holding means, an opening for introducing a nozzle is provided in the airtight holding means, and the opening is held by a nozzle. Of the glass material, characterized in that the nozzle holding member is provided with cooling means for shielding the nozzle holding member via the airtight holding member to the airtight holding member Molding equipment. 3. The glass material according to claim 1, wherein a passage for a cooling medium is formed in the opening of the airtight holding means by the nozzle holding member and the airtight holding member. Molding equipment.