JPH0624989B2 - Method for manufacturing optical glass element and manufacturing apparatus used for the method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to the production of highly accurate optical glass elements such as lenses and prisms, and optical glass elements such as an optical glass molded body of a material for reheat press molding of the optical glass element. The present invention relates to a method and a manufacturing apparatus used for the manufacturing method.

2. Description of the Related Art In recent years, optical glass lenses are in the direction of aspherical surface that can achieve both simplification of the lens structure of optical equipment and weight reduction of the lens portion at the same time. In manufacturing this aspherical lens, it is difficult to process and mass-produce it by a conventional polishing method which is a manufacturing method of optical glass, and a molding method using a mold is considered to be promising.

The molding method using this mold is that aluminum hydroxide is applied on the mold that has been finished to the desired surface quality and surface accuracy in advance,
This is a method in which a lump of optical glass is heat-molded or a lump of optical glass in a molten state is heat-molded in a state where a release agent such as magnesium carbonate or carbon is applied or covered (for example, Japanese Patent Publication No. 54-60312).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the case of an optical glass element such as an aspherical lens or a prism, it is required to have a surface free from defects or a release agent, surface roughness, and surface accuracy. Also, the optical glass molded body of the reheat press molding material for the optical glass element has become very expensive.

That is, it is necessary to perform polishing or etching treatment in order to make the surface of the optical glass molded body have no defects (for example, a mirror surface state with a surface roughness RMS of 0.005 micron or less), and the optical glass molded body is expensive. Has become
There has been a strong demand for development of a method capable of producing a highly accurate optical glass molded body at low cost.

Means for Solving the Problems In order to solve the above problems, the present invention comprises a step of receiving molten glass with a first heat processing jig in a non-oxidizing atmosphere, and inverting the first heat processing jig. A step of inverting and replacing the molten glass with a second heat processing jig, a step of producing an optical glass molded body by thermal deformation with the second heat processing jig,
A method for manufacturing an optical glass element including a step of heating and pressing an optical glass molded body with a press molding die, and by reversing a first heat processing jig that receives molten glass flowing out from a nozzle used in the method. Provided is an optical glass element manufacturing apparatus provided with means for replacing a molten glass in an inverted state with a second heat processing jig for thermal deformation.

Action Since high-temperature molten glass is in a chemically extremely active state, it caused a great deal of damage to the heat processing jig and reacted or fused with the optical glass. In order to prevent this, it is effective to use the heat processing jig without heating it, but large wrinkle-shaped defects due to thermal contraction occur on the optical glass surface in contact with the heat processing jig.

In order to remove the wrinkle-like defects on the surface of the optical glass in contact with the heat processing jig, the molten glass is received by the first heat processing jig at a relatively low temperature and then the first heat processing jig is inverted. The molten glass is replaced by the second thermal processing jig in the inverted state, and thermal deformation is performed by the second thermal processing jig with the wrinkled surface of the optical glass facing upward. Furthermore, the optical glass element having no surface defects can be manufactured by subjecting this optical glass molded article to heat and pressure molding with a press molding die.

For the first heat processing jig that directly receives the molten glass, a material having poor wettability with the molten glass and excellent releasability, such as carbon, boron nitride, aluminum nitride, chromium nitride, and stainless steel is suitable. There is. Further, the cigar covering the second heat processing jig and the press molding die is a noble metal that does not react with or fuse with the optical glass in a non-oxidizing atmosphere,
Desirably, it is a simple substance of tungsten, tantalum, rhenium, or hafnium or an alloy thereof.

In the present invention, the non-oxidizing atmosphere in which the optical glass and these thin films do not react or fuse with each other is nitrogen, argon,
Inert gas such as helium, and hydrogen, carbon monoxide, carbon dioxide of carbon dioxide,
Hydrocarbons such as methane, ethane, ethylene, toluene,
It is a mixture of halogenated hydrocarbons such as trichloroethylene and trichlorotrifluoroethane, alcohols such as ethylene glycol and glycerin, and fluorocarbons such as F-113 and F-11.

These atmospheres are appropriately selected according to the conditions such as the optical glass composition, the thin film roughening covering the heat processing jig, the temperature and time of thermal deformation, the temperature and time of press molding, the shape of the optical glass molded body, and the like.

Embodiment One embodiment of the present invention will be described in detail below with reference to the drawings.

Example 1 FIG. 1 is a sectional view of a first heat processing jig, a second heat processing jig and a press molding die used in the present invention. Carbon was used as the first heat processing jig and processed into a concave shape with a radius of curvature of 15 mm. Cemented carbide (WC-5TiC-8Co) was used as the base material of the second heat processing jig, and the radius of curvature was 15
A concave optical surface 1 of mm was formed. The optical surface 1 was lapped with ultrafine diamond powder to obtain about 1
The surface had a surface roughness (RMS) of about 30Å in time. Platinum was sputtered on the mirror surface of the heat processing jig.
A thin film 2 of an iridium-osmium alloy (Pt-Ir-Os) was coated. Similar to the second heat processing jig, a cemented carbide (WC-5TiC-8Co) is used as a base material to form a concave optical surface 1 having a radius of curvature of 20 mm, and a platinum-iridium-osmium alloy is formed by a sputtering method. A thin film 2 of (Pt-Ir-Os) was coated to obtain a press molding die.

As the molten glass 14, 30% by weight of silica (SiO ₂ ), 50% by weight of barium oxide (BaO), 15% by weight of boric acid (B ₂ O ₃ ), and barium borosilicate glass having the balance of trace components were used. After melting this glass at 1200 ° C., about 3 g of molten glass 14 was passed through the nozzle 12 kept at 800 ° C. and nitrogen gas 2
First heat processing jig 24 held in a molding machine in an atmosphere mixed with 0 liter / min and hydrogen gas 2 liter / min.
Was added dropwise. The first heat processing jig 24 is heated to 200 ° C. in advance, the first heat processing jig 24 is inverted by the arm 25 immediately after dropping, and the second heat processing jig 16 is moved to the second heat processing jig 16.
Molten glass 14 was placed as shown. After being thermally deformed by the second heat processing jig 16 at 360 ° C. for 10 minutes, it was press shaped by the press molding die 20. Press molding conditions are mold temperature 560 ° C., press pressure 30 kg / cm ² , press time 2
It was a minute. After that, slowly cool to 300 ° C, and take out port 2
The optical glass element 22 was taken out from No. 3.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press-molded surface is about 25Å
No optical defects such as bubbles, scratches, or traces of peeling were observed, and the surface accuracy was within 2 Newton rings and within 1/5 ass, and the optical performance was extremely excellent.

Example 2 Using boron nitride as the first thermal processing jig,
It was processed into a concave shape with a radius of curvature of 45 mm. A concave optical surface 1 having a radius of curvature of 45 mm was formed using austenitic steel (SUS316) as a base material of the second heat processing jig. The optical surface 1 was further lapped with ultrafine diamond powder to make it a mirror surface having a surface roughness (RMS) of about 30Å in about 1 hour. On the surface of the heat processing jig that became a mirror surface,
Platinum-iridium-osmium alloy (Pt
-Ir-Os) thin film 2 was coated. Austenitic steel (SUS316) as a base material similar to the second heat processing jig
Is used to form a concave optical surface 1 having a radius of curvature of 150 mm, and a rhodium-gold-tungsten alloy (R
h-Au-W) was coated to form a die for press molding.

Molten glass 14, zirconia _(ZrO 2) 8% by weight, lanthanum oxide _(La 2 _{O 3)} 30% by weight, of boric acid _(B 2 _{O 3)} 42% by weight, calcium oxide (CaO) 10% by weight, the balance being trace amounts A lanthanum-based glass composed of the components was used. 1400 this glass
After melting at 950 ° C., about 3 grams of molten glass 14 was discharged from the nozzle 12 kept at 950 ° C. to 20 liters of nitrogen gas /
Min, was added dropwise to trichloro trifluoroethane (C ₂ Cl 3 _{F 3)} first heat working jig 24 holding the molding machine of the halogenated hydrocarbon atmosphere in a mixing ratio of 1 liter / minute gas. The first heat processing jig 24 is heated to 400 ° C. in advance, the first heat processing jig 24 is inverted by the arm 25 immediately after dropping, and the second heat processing jig 16 is placed on the second heat processing jig 16 as shown in FIG. The molten glass 14 was placed on. Second heat processing jig 16
After being thermally deformed at 780 ° C. for 20 minutes, it was press-molded with the press-molding die 20. The press molding conditions were a mold temperature of 680 ° C., a press pressure of 30 kg / cm ² , and a press time of 2 minutes. After that, it was gradually cooled to 400 ° C., and the optical glass element 22 was taken out from the take-out port 23.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press molding surface is about 209.
Since it is an optical mirror surface of Å, defects such as bubbles, scratches, and peeling marks were not recognized, and the surface accuracy was within 2 Newton rings and within 1/5 ass, and its optical performance was extremely excellent.

Example 3 Aluminum nitride was used as the first heat processing jig and processed into a concave shape with a radius of curvature of 200 mm. Cermet (TiC-10Mo-9Ni) was used as the base material of the second heat processing jig, and the radius of curvature was 2
A 00 mm concave optical surface 1 was formed. Lapping the optical surface 1 with ultrafine diamond powder,
The surface roughness (RMS) was about 30Å in about 1 hour. A thin film 2 of platinum-tantalum-rhenium alloy (Pt-Ta-Re) was coated on the mirror-finished surface of the heat-processing jig by a sputtering method. Similar to the second heat processing jig, cermet (TiC-10Mo-9Ni) was used as a base material to form a concave optical surface 1 having a radius of curvature of 500 mm, and a platinum-tantalum-rhenium alloy (Pt) was formed by a sputtering method. -Ta-Re) thin film 2 was coated to obtain a die for press molding.

The molten glass 14 comprises 65 weight percent silica (SiO ₂ ), 9 weight percent potassium oxide (K ₂ O), 10 weight percent boric acid (B ₂ O ₃ ), 10 weight percent sodium oxide (Na ₂ O), and the balance being Borosilicate glass consisting of trace components was used.

After melting this glass at 1350 ° C., about 3 g of molten glass 14 was discharged from the nozzle 12 kept at 920 ° C., with an argon gas of 20 liter / min, ethylene (C ₂ H ₄ ) 1
It was dropped onto the first thermal processing jig 24 held in the molding machine in a hydrocarbon atmosphere mixed at a rate of liter / minute. The first heat processing jig 24 is heated to 550 ° C. in advance, and immediately after the dropping, the first heat processing jig 24 is inverted by the arm 25, and the second heat processing jig 16 is placed on the second heat processing jig 16 as shown in FIG. The molten glass 14 was placed on. Second heat processing jig 16 at 780 ° C., 5
After thermally deforming for a minute, it was press-molded with the press-molding die 20. The press molding conditions were a mold temperature of 680 ° C., a press pressure of 80 kg / cm ² , and a press time of 1 minute. Then 3
After gradually cooling to 80 ° C., the optical glass element 22 was taken out from the take-out port 26.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press-molded surface is about 20Å
No optical defects such as bubbles, scratches, or traces of peeling were observed, and the surface accuracy was within 2 Newton rings and within 1/5 ass, and the optical performance was extremely excellent.

Example 4 Martensitic stainless steel (SUS420) was used as the first heat processing jig and processed into a concave shape having a radius of curvature of 45 mm. A concave optical surface 1 having a radius of curvature of 55 mm was formed by using silicon as a base material of the second heat processing jig. The optical surface 1 was further lapped with ultrafine diamond powder to make a mirror surface having a surface roughness (RMS) of about 20Å in about 1 hour. The thin film 2 of rhodium-gold-Tungsten alloy (Rh-Au-W) was coated on the mirror surface of the heat-processed jig by a sputtering method. Similar to the second heat processing jig, silicon is used as the base material and the radius of curvature is 1
A 00 mm concave optical surface 1 was formed, and a thin film 2 of a rhodium-gold-Tungsten alloy (Rh-Au-W) was coated by a sputtering method to obtain a press molding die.

The molten glass 14 contains 52 weight percent silica (SiO ₂ ), 6 weight percent potassium oxide (K ₂ O), 35 weight percent lead oxide (PbO), and sodium oxide (N
a ₂ O) 5% by weight, the balance being a heavy flint glass consisting of trace components.

After melting this glass at 1250 ° C., from a nozzle 12 kept at 750 ° C., about 5 g of molten glass 14 was mixed in a molding machine in an atmosphere of 20 liter / min of helium gas and 2 liter / min of carbon dioxide gas. It was dropped on the held first heat processing jig 24. First heat processing jig 24
Is left unheated, the first heat processing jig 24 is inverted by the arm 25 immediately after dropping, and the second heat processing jig 16
The molten glass 14 was placed on the glass as shown in FIG. After being thermally deformed at 610 ° C. for 5 minutes by the second heat processing jig 16, it was press-molded by the press molding die 20. The press molding conditions were a mold temperature of 550, a press pressure of 80 kg / cm ² , and a press time of 1 minute. After that, it was gradually cooled to 380 ° C., and the optical glass element 22 was taken out from the take-out port 26.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press-molded surface is about 20Å
No optical defects such as bubbles, scratches, or traces of peeling were observed, and the surface accuracy was within 2 Newton rings and within 1/5 ass, and the optical performance was extremely excellent.

The optical glass element manufacturing method of the present invention and the manufacturing apparatus used for the method include a step of receiving molten glass with a first thermal processing jig in a non-oxidizing atmosphere, and inverting the first thermal processing jig. By inverting the molten glass to the second heat processing jig to replace it, a step of producing an optical glass molded body by thermal deformation with the second heat processing jig, and a mold for press molding the optical glass molded body. A method for manufacturing an optical glass element including a step of heating and pressurizing at 1, and a second heat for thermally deforming by inverting the first heat processing jig that receives the molten glass flowing out from the nozzle used in the method. An apparatus for producing an optical glass element, which is provided with a means for displacing a molten glass in an inverted state in a processing jig, wherein a molding atmosphere, an optical glass composition, and a thin film for coating a thermal processing jig. composition, Temperature and time of the modification, or conditions such as the shape of the optical glass shaped material is not limited to this embodiment.

EFFECTS OF THE INVENTION As described above, the manufacturing method of the optical glass element of the present invention and the manufacturing apparatus used in the method are the same as the first thermal processing after receiving the molten glass by the first thermal processing jig at a relatively low temperature. By inverting the jig, the molten glass is replaced with the second heat processing jig in a reversed state, and the second heat processing jig performs thermal deformation with the wrinkled surface of the optical glass facing up. Furthermore, the optical glass element having no surface defects can be manufactured by subjecting this optical glass molded article to heat and pressure molding with a press molding die.

That is, the present invention enables mass production of highly accurate optical glass elements, and has a remarkable effect in improving productivity and reducing manufacturing cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a first thermal processing jig, a second thermal processing jig, and a press molding die, and FIG. 2 is a sectional view of an embodiment of the present invention showing an optical glass element manufacturing apparatus. . 1 ... Optical surface, 2 ... Thin film, 10 ... Glass melting furnace, 1
1 ... Heating heater, 12 ... Nozzle, 13 ... Nozzle heating heater, 14 ... Molten glass, 15 ... Heating heater,
16 ... Second heat processing jig, 17 ... Gas inlet, 18 ...
… Optical glass molding, 19 …… Press cylinder, 20…
... press molding die, 21 ... conveyor, 22 ... optical glass element, 23 ... outlet, 24 ... first heat processing jig, 25 ... arm.

Front page continuation (72) Inventor Makoto Umeya 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kiyuki Kawada 5-19, Higashi Omiya, Omiya City, Saitama Prefecture

Claims (8)

[Claims] 1. A step of receiving molten glass with a first heat processing jig in a non-oxidizing atmosphere, and reversing the first heat processing jig to reverse the molten glass to a second heat processing jig. Of the optical glass element, which has a step of performing the replacement, a step of producing an optical glass molded body by thermal deformation with a second thermal processing jig, and a step of heating and pressing the optical glass molded body with a press molding die. Production method. 2. The method for producing an optical glass element according to claim 1, wherein the first heat processing jig has poor wettability with the molten glass. 3. The optical glass according to claim 1, wherein the second heat processing jig and the press molding die are processed into a desired shape and optical surface and covered with a chemically stable thin film. Device manufacturing method. 4. The thin film is a noble metal, tungsten, tantalum,
4. The method for producing an optical glass element according to claim 3, which is a simple substance of rhenium or hafnium or an alloy thereof. 5. A means for replacing the molten glass in the inverted state with a second thermal processing jig for thermal deformation by reversing the first thermal processing jig for receiving the molten glass flowing out from the nozzle. A method for manufacturing the provided optical glass element. 6. The optical glass element manufacturing apparatus according to claim 5, wherein the first heat processing jig has poor wettability with the molten glass. 7. The optical glass element manufacturing apparatus according to claim 5, wherein the second heat processing jig is processed into a desired shape and optical surface and is covered with a chemically stable thin film. 8. The thin film is a noble metal, tungsten, tantalum,
8. The method for producing an optical glass element according to claim 7, which is a simple substance of rhenium or hafnium or an alloy thereof.