JPH02225324A - Production of optical glass element and apparatus therefor - Google Patents

Abstract

PURPOSE:To prevent fine bubble-like defects from occurring in a formed glass body by providing the same apparatus with a nozzle, thermal working jig and metallic mold for press forming and enabling continuous press forming in a nonoxidizing atmosphere. CONSTITUTION:Molten glass 14 discharged from the tip of a nozzle 12 provided in an apparatus kept in a nonoxidizing atmosphere is fed to a thermal working jig 16 in the same apparatus. The above-mentioned glass 14 is then thermally deformed on the jig 16 to afford a formed body 18 of optical glass, which is subsequently press formed in a metallic mold 20 for press forming in the aforementioned same apparatus to provide optical glass elements 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to optical glass elements such as high-precision optical glass elements such as lenses and prisms, and optical glass molded bodies of materials for reheat press molding of optical glass elements. The present invention relates to a manufacturing method and a manufacturing device used in the method.

2. Description of the Related Art In recent years, there has been a trend toward aspheric optical glass lenses, which can simultaneously simplify the lens structure of optical equipment and reduce the weight of the lens portion. In manufacturing this aspherical lens, processing and mass production are difficult using the polishing method, which is a conventional optical lens manufacturing method, and a molding method using a mold is considered to be promising.

The molding method using this mold involves placing aluminum hydroxide on a mold that has been finished to the desired surface quality and precision in advance.
This is a method in which a lump of optical glass is heat-molded in a state in which a mold release agent such as magnesium carbonate or carbon is coated or coated, or a lump of optical glass in a molten state is heat-molded. (For example, Japanese Patent Publication No. 54-60312) Problems to be Solved by the Invention In the case of optical glass elements such as aspherical lenses and prisms, the surface, surface roughness, and surface precision are free of defects or adhesion of mold release agents. As a result, optical glass elements and optical glass molded bodies, which are raw materials for reheat press molding of optical glass elements, have become extremely expensive.

In other words, in order to make the surface of the optical glass molded object free from defects such as bubbles and scratches (for example, a mirror-like state with a surface roughness of 0.005 microns or less in RMS), it is necessary to perform a polishing or etching process. Molded objects have become expensive, and there has been a strong desire to develop a method that can produce high-precision optical glass elements at low cost.

Means for Solving the Problems In order to solve the problems described above, the present invention provides a step of supplying the molten glass flowing out from the nozzle tip to a thermal processing jig while being maintained in a non-oxidizing atmosphere, and a step of continuously supplying the molten glass from the supply step. A method for producing an optical glass element, comprising the steps of: thermally deforming it on the optical surface of a thermal processing jig in a non-oxidizing atmosphere; and press-molding the thermally deformed optical glass molded body using a press molding die. Also, a nozzle for supplying molten glass to a thermal processing jig used in the method, a thermal processing jig for thermally deforming the molten glass, and a press molding die for press-molding the thermally deformed optical glass molded body. The present invention provides an apparatus for manufacturing optical glass elements, which is provided within the same apparatus maintained in a non-oxidizing atmosphere.

The thin film coated on the heat processing jig and press mold is preferably made of noble metals, tungsten, tantalum, rhenium, hafnium, or alloys thereof, which do not react or fuse with optical glass in a non-oxidizing atmosphere. .

Function Conventionally, when molten glass flows out from the tip of a nozzle in the atmosphere, microscopic bubble-like defects are likely to occur in the thermally deformed optical glass molded body. As a result of extensive research into this phenomenon, we found that when molten glass flows out from the nozzle tip in the atmosphere, the surface of the molten glass is rapidly cooled while being fed to the heat processing jig, and is firmly bonded to the molten glass. Moisture, oxygen, etc. in the atmosphere are adsorbed to the surface of the molten glass. It is thought that this is because such adsorbed matter expands as a gas when it comes into contact with a thermal processing jig, causing minute bubble-like defects in the optical glass molded body.

To solve this problem, the molten glass flowing out from the nozzle tip is kept in a non-oxidizing atmosphere while being supplied to the thermal processing jig, and then continuously placed on the optical surface of the thermal processing jig in the non-oxidizing atmosphere. We devised a manufacturing method in which the optical glass molded body was thermally deformed using a press-molding mold.

This manufacturing method prevents the adsorption of moisture, oxygen, etc. in the atmosphere that is strongly bonded to the molten glass, and eliminates the generation of minute bubble-like defects in the optical glass molded body during thermal deformation.

In the present invention, the non-oxidizing atmosphere in which minute bubble-like defects are less likely to occur in the optical glass molded article is nitrogen, argon,
Inert gas atmosphere such as helium, and in these inert gas atmospheres, hydrogen, carbon oxide, carbon oxides of carbon dioxide, hydrocarbons such as methane, ethane, ethylene, toluene, trichloroethylene, trichlorotrifluoriethane, etc. halogenated hydrocarbons, alcohols such as ethylene glycol and glycerin, F-113, F-
It is a mixture of fluorocarbons such as No. 11 as appropriate.

These atmospheres are appropriately selected depending on conditions such as the composition of the optical glass, the composition of the thin film coated on the thermal processing jig and press mold, the temperature and time of thermal deformation, and the shape of the optical glass molded body.

When the glass gob is thermally deformed on the optical surface of the thermal processing jig coated with a chemically stable thin film, not only the free surface of the optical glass molded object but also the optical surface of the thermal processing jig is transferred. It is possible to obtain an optical glass molded article that does not have minute bubble-like defects even on its surface.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

<Example 1> FIG. 1 is a sectional view of a thermal processing jig used in the present invention. Cemented carbide (WC-5TiC-8
A concave optical surface l having a radius of curvature of 20 decibels was formed using Co. This optical surface 1 is further lapped using ultra-fine diamond powder, and the surface roughness (
RMS) made a mirror surface of about 25 people. The mirror-finished surface of the thermal processing jig was coated with a thin film 2 of platinum-iridium-osmium alloy (PL-1r-Os) by sputtering to produce a thermal processing jig 16 for an optical glass molded body. In addition, a press molding die having a concave optical surface with a radius of curvature of 200 m was manufactured in the same manner as the thermal processing jig 16.

The molten glass 14 used was barium borosilicate glass containing 30% by weight of silica (S i Ox ), 50% by weight of barium oxide (Bad), 15% by weight of boric acid (B, Os 2 ), and the remainder being trace components. As shown in FIG. 2, the nozzle 12 is held in an atmosphere-controlled molding machine, and the glass melting furnace
Nozzle 1 melted at °C and maintained at nozzle temperature 800 °C
Approximately 3 grams of molten glass from No. 2 was supplied to the thermal processing jig 16 described above. The inside of the molding machine was maintained in an atmosphere in which nitrogen gas was mixed at a rate of 2 liters per minute and 2 liters per minute of hydrogen gas. The heat processing jig 16 is preheated to 640°C, and as shown in Fig. 2, the molten glass 14 is placed on the heat processing jig 16 and thermally deformed for 10 minutes, then transported by the conveyor 21 and press-formed. Press cylinder E9 with the mold 2゜ attached
Press molded. For press molding, mold temperature is 580″C1
The molding time was 2 minutes and the pressure was 30 kg/cd. Immediately after the press molding, the optical glass element 2 is transferred to an annealing furnace and slowly cooled, and after reaching 300°C, it is taken out from the outlet 23.
I got 2.

The optical glass element 22 manufactured by such a process has a press-molded surface with a surface roughness (RMS) of about 20 optical mirror surfaces, no defects such as bubbles, scratches, or peeling marks, and has a high surface accuracy. The optical performance was within two Newton rings and within one-fifth of an American ring, and its optical performance was extremely excellent.

<Example 2> Austenitic steel (SUS3) was used as the base material 3 of the heat processing jig.
16) was used to form a concave optical surface 1 with a radius of curvature of 45 mm. This optical surface 1 was further lapped using ultrafine diamond powder, and the surface roughness (RMS) was made into a mirror surface of about 30 in about 1 hour. A thin film 2 of rhodium-gold-tungsten alloy (Rh-Au-W) was coated on the mirror-finished surface of the heat-processing jig by sputtering to produce a heat-processing jig for an optical glass molded body. Also, the heat processing jig 16
A press molding die having a concave optical surface with a radius of curvature of 150 avn was produced in the same manner as above.

The molten glass 14 contains 8 percent by weight of zirconia (ZrOz), 30 percent by weight of lanthanum oxide (Lazowl), and 42 iklt/'' of boric acid (B20:l).
A lanthanum-based glass consisting of 10% by weight of calcium oxide (Cab) and the balance being trace components was used.

As shown in Fig. 2, after melting this glass at 1400°C, the nozzle 12 is held in an atmosphere-controlled molding machine, and at a nozzle temperature of 950°C, 4 grams of molten glass 14 is placed in the atmosphere-controlled molding machine. It was dripped onto the held thermal processing jig 16. Inside the molding machine, trichlorotrifluoroethane (Cm
It was a halogenated hydrocarbon atmosphere into which C1s Fz) steam was introduced. The heat processing jig 16 is heated to 780°C in advance, and the molten glass 14 is placed on the heat processing jig 16 as shown in FIG.
and press-molded using a press cylinder 19 equipped with a press-molding die 20. Press molding was performed at a mold temperature of 680° C., a molding time of 2 minutes, and a pressure of 30 kg/c+1. Immediately after press forming, it is transported to an annealing furnace for annealing, and
After the temperature reached 0°C, it was taken out from the takeout port 23 to obtain an optical glass element 22.

The optical glass element 22 manufactured by such a process has a press-molded surface with a surface roughness (RMS) of about 20 optical mirror surfaces, no defects such as bubbles, scratches, or peeling marks, and has a high surface accuracy. The optical performance was within two Newton rings and within one-fifth of American, and its optical performance was extremely excellent.

<Example 3> Cermet (TtC-10M
A concave optical surface 1 with a radius of curvature of 200+nl11 was formed using a material (concave optical surface 1). This optical surface 1 was further lapped using ultrafine diamond powder, and the surface roughness (RMS) was made into a mirror surface of about 30 in about 1 hour. A thin film 2 of platinum-tantalurenium alloy (Pt-Ta-Re) was coated on the mirror-finished surface of the heat-processing jig by sputtering to produce a heat-processing jig for an optical glass molded body. In addition, a press molding die having a concave optical surface with a radius of curvature of 500 degrees was produced in the same manner as the thermal processing jig 16.

The molten glass 14 is composed of silica csio□) 65 weight percent, potassium oxide (K, O) 9 weight percent, boric acid CBtOs) 10 weight percent, sodium oxide (Na, O) weight percent, and the balance consisting of trace components. Acid glass was used.

After melting this glass at 1350°C, a thermal processing jig 1 holds 3 grams of molten glass 14 in a molding machine with a controlled atmosphere at a nozzle temperature of 920°C as shown in Figure 2.
6. Inside the molding machine, there is 20 liters of argon gas.
The atmosphere was a hydrocarbon atmosphere mixed with 1 liter of ethylene (C,H4) per minute.

The heat processing jig 16 is preheated to 780°C, and as shown in Fig. 2, the molten glass 14 is placed on the heat processing jig 16 and thermally deformed for 5 minutes, and then conveyed by the conveyor 21 to be used for press forming. Press molding was carried out using a press cylinder 19 equipped with a mold 20. Press molding was performed at a mold temperature of 680° C., a molding time of 1 minute, and a pressure of 80 kg/cj.

Immediately after press molding, it is transported to a slow cooling furnace and slowly cooled to 380°C.
After this point, the optical glass element 22 was taken out from the takeout port 23.

The optical glass element 22 manufactured by such a process has a press-molded surface with a surface roughness (RMS) of about 20 optical mirror surfaces, no defects such as bubbles, scratches, or peeling marks, and has a high surface accuracy. The optical performance was within two Newton rings and within one-fifth of an American ring, and its optical performance was extremely excellent.

Example 4 A concave optical surface 1 with a radius of curvature of 45 degrees was formed using silicon as the base material 3 of a thermal processing jig. This optical surface 1 is further wrapped with ultra-fine diamond powder,
In about 1 hour, the surface roughness (RMS) reached a mirror surface of about 20 people. A thin film 2 of rhodium-gold-tungsten alloy (Rh-Au-W) is coated on the mirror-finished surface of the heat processing jig by sputtering to form a heat processing jig 16 for forming an optical glass body as shown in FIG. was created. In addition, a press molding die having a concave optical surface with a radius of curvature of 100 m was produced in the same manner as the thermal processing jig 16.

The optical glass lump 3 contains 52% by weight of silica (Sint), 6% by weight of potassium oxide (K,0), 35% by weight of lead oxide (PbO), and 35% by weight of sodium oxide (N
a, O) A heavy flint glass consisting of 5% by weight and the remainder consisting of trace components was used.

After this glass was melted at 1250°C, 5 grams of molten glass 14 was dropped at a nozzle temperature of 750°C into a thermal processing jig 16 held in an atmosphere-controlled molding machine as shown in FIG. The atmosphere inside the molding machine was a mixture of 20 liters/minute of helium gas and 2 liters/minute of carbon dioxide gas. The heat processing jig 16 is preheated to 610°C, and as shown in Fig. 2, the molten glass 14 is placed on the heat processing jig 16 and thermally deformed for 5 minutes, and then conveyed by the conveyor 21 to be used for press forming. Press molding was carried out using a press cylinder 19 equipped with a mold 20. For press molding, mold temperature is 5.
50"C1 molding time was 1 minute and the pressure was 80) cg/cd. Immediately after press molding, it was transferred to an annealing furnace and slowly cooled.
After the temperature reached 0''C, it was taken out from the takeout port 23 to obtain an optical glass element 22.

The optical glass element 22 manufactured by such a process has a press-molded surface with a surface roughness (RMS) of about 20 optical mirror surfaces, no defects such as bubbles, scratches, or peeling marks, and has a high surface accuracy. The optical performance was within two Newton rings and within one-fifth of an American ring, and its optical performance was extremely excellent.

The method for manufacturing an optical glass element of the present invention and the manufacturing apparatus used in the method include a step of supplying the molten glass flowing out from the nozzle tip to a thermal processing jig while being maintained in a non-oxidizing atmosphere, and a continuous step from the supply step. Manufacturing of an optical glass element, which includes the steps of thermally deforming it on the optical surface of a thermal processing jig in a non-oxidizing atmosphere, and press-molding the thermally deformed optical glass molded object with a press molding die. A method, a nozzle for supplying molten glass to a thermal processing jig used in the method, a thermal processing jig for thermally deforming the molten glass, and a press molding die for press forming a thermally deformed optical glass molded body. This is an optical glass element manufacturing apparatus in which the following are installed in the same apparatus maintained in a non-oxidizing atmosphere, and the molding atmosphere, optical glass composition, thin film composition coated on the thermal processing jig, Conditions such as the temperature and time of thermal deformation or the shape of the optical glass molded body are not limited to those in this example.

As described in detail of the invention, the method of manufacturing an optical glass element of the present invention and the manufacturing apparatus used in the method include maintaining a nozzle, a heat processing jig, and a press molding die in a non-oxidizing atmosphere. The molten glass flowing out from the nozzle tip is supplied to the thermal processing jig while being maintained in a non-oxidizing atmosphere, and then the optical processing of the thermal processing jig is continuously performed in the non-oxidizing atmosphere. It is now possible to thermally deform the optical glass molded body on the surface and then continuously press-form the thermally deformed optical glass molded body using a press-forming mold. Adsorption is prevented, and the occurrence of minute bubble-like defects in the optical glass molded body during thermal deformation can be eliminated.

That is, the present invention makes it possible to mass-produce high-precision optical glass elements, and has a significant effect on improving productivity and reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a thermal processing jig, and FIG. 2 is a sectional view showing an apparatus for manufacturing an optical glass element according to an embodiment of the present invention. 1... Optical surface, 2... Thin film, 3...
...Base material. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1/Optical surface 3 base material

Claims (4)

[Claims] (1) A step in which the molten glass flowing out from the nozzle tip is supplied to a thermal processing jig while being maintained in a non-oxidizing atmosphere, and an optical surface of the thermal processing jig is continuously maintained in a non-oxidizing atmosphere from the supply step. A method for producing an optical glass element, comprising the steps of thermally deforming the above, and press-molding the thermally-deformed optical glass molded body using a press mold. (2) The method for manufacturing an optical glass element according to claim (1), wherein the thermal processing jig and the press molding die are coated with a chemically stable thin film and have a desired shape and optical surface. (3) The method for manufacturing an optical glass element according to claim (2), wherein the chemically stable thin film is a noble metal, tungsten, tantalum, rhenium, hafnium, or an alloy thereof. (4) A nozzle that supplies molten glass to a thermal processing jig, a thermal processing jig that thermally deforms the molten glass, and a press molding die that press-forms the thermally deformed optical glass molded body in a non-oxidizing manner. Optical glass element manufacturing equipment installed in the same equipment maintained in a neutral atmosphere.