JPH0645464B2 - 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 method of manufacturing an optical lens, and a molding method using a mold is considered 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. 54-6031
(2) The problem 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 release agent, surface roughness, and surface accuracy. The optical glass element and the optical glass molded body of the reheat press molding material for the optical glass element have become very expensive.

That is, there is no defect on the surface of the optical glass molded body (for example, mirror surface state with surface roughness RMS of 0.005 micron or less).
In order to achieve this, it is necessary to perform a polishing or etching treatment, and the optical glass molded body is expensive, and it has been strongly desired to develop 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 provides a step of receiving molten glass with a first heat processing jig in a non-oxidizing atmosphere, and a step of receiving the molten glass in a second heat processing jig. The step of inverting and replacing the molten glass and the second heat processing jig in the bonded state, the step of producing an optical glass molded body by thermal deformation with the second heat processing jig, the pressing of the optical glass molded body A method for manufacturing an optical glass element including a step of heating and pressing with a molding die, and melting the second heat processing jig with the molten glass received by the first heat processing jig used in the method, and melting The glass is attached to the second thermal processing jig, and the molten glass is attached to the second thermal processing jig, the second thermal processing jig is inverted, and the molten glass is attached to the first thermal processing jig. From the second heat processing jig to an optical glass element manufacturing device. It is provided.

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 that was in contact with the heat processing jig, after receiving the molten glass with the first heat processing jig at a relatively low temperature, the second heat processing jig was applied to the molten glass. The molten glass adheres to the second heat processing jig by contacting, and the second heat processing jig is inverted with the molten glass adhered to the second heat processing jig, and The heat processing jig of No. 1 is stably replaced with the second heat processing jig, and the second heat processing jig heat-deforms 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. The thin film that covers the second heat-processing jig and the press-molding die is a simple substance of noble metal, tungsten, tantalum, rhenium, or hafnium that reacts with or slightly adheres to the optical glass in a non-oxidizing atmosphere, or their An alloy is desirable.

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 oxide of carbon dioxide,
Hydrocarbons such as methane, ethane, ethylene and 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 depending on the conditions such as the optical glass composition, the thin film composition to be coated on the thermal 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 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. A thin film 2 of platinum-iridium-osmium alloy (Pt-It-Os) was coated on the mirror-finished surface of the heat processing jig by a sputtering method. Similar to the second heat processing jig, a cemented carbide (WC-5TiC-8Co) was used as a base material to form a concave optical surface 1 having a radius of curvature of 20 mm, and platinum was formed by sputtering.
A thin film 2 of an iridium-osmium alloy (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 (Ba ₂ O ₃ ), and the balance borosilicate barium glass was used. After melting this glass at 1200 ° C., about 3 grams of molten glass 14 was kept at 800 ° C. and held in a molding machine in an atmosphere in which nitrogen gas was mixed at a rate of 20 liters / minute and hydrogen gas was 2 liters / minute. First heat processing jig 2
4 was added dropwise. The first heat processing jig 24 is heated to 200 ° C. in advance, and immediately after the dropping, the second heat processing jig 16 is melted in the molten glass 14 and the molten glass 14 is transferred to the second heat processing jig 16. Attached. The second heat processing jig 16 having the molten glass 14 attached thereto was inverted by the arm 25, and the molten glass 14 was replaced with the second heat processing jig 16 as shown in FIG. After being thermally deformed by the second heat processing jig 16 at 630 ° C. for 10 minutes, it was press-molded by the press-molding die 20. Press molding conditions are mold temperature 560 ° C and press pressure 3
It was 0 kg / cm ² and the pressing time was 2 minutes. After that, 300 ° C
Then, 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-molded surface is about 25Å
No optical defects such as bubbles, scratches, or peeling marks were observed, and the surface accuracy was within 2 Newton rings and within 1/5 ass, and its optical performance was extremely excellent.

Example 2 Boron nitride 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 45 mm was formed using austenitic steel (SUS316) as a base material of the second heat processing jig. The optical surface 1 was lapped with ultrafine diamond powder, and the surface roughness (RMS) of the surface was about 3 in about 1 hour.
I made it a 0Å mirror surface. A platinum-iridium-osmium alloy (Pt-
A thin film 2 of Ir-Os) was coated. Similar to the second heat processing jig, austenite steel (SUS316) is used as the base material to form the concave optical surface 1 having a radius of curvature of 150 mm,
Rhodium-gold-tungsten alloy (Rh-
Au-W) thin film 2 was coated to obtain a die for press molding.

The molten glass 14 contains zirconia (ZrO ₂ ) 8 weight percent, lanthanum oxide (Las ₂ O ₃ ) weight percent, boric acid (B ₂ O ₃ ) 42 weight percent, calcium oxide (CaO) 10 weight percent, and the balance trace components. Was used. This glass 14
Nozzle 12 held at 950 ° C after melting at 00 ° C
From about 3 grams of molten glass 14 to 20 liters / minute of nitrogen gas, trichlorotrifluoroethane (C ₂ Cl ₃ F
₃ ) First heat processing jig 2 held in a molding machine in a halogenated hydrocarbon atmosphere mixed with gas at a rate of 1 liter / min.
4 was added dropwise. The first heat processing jig 24 is heated to 400 ° C. in advance, and immediately after the dropping, the second heat processing jig 16 is brought into contact with the molten glass 14 so that the second heat processing jig 16 receives the molten glass 14. Attached. The second heat processing jig 16 having the molten glass 14 attached thereto was inverted by the arm 25, and the molten glass 14 was replaced with the second heat processing jig 16 as shown in FIG. After being thermally deformed at 780 ° C. for 20 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 680 ° C., a pressing pressure of 30 kg / cm ² , and a pressing 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-molded surface is an optical mirror surface of about 20Å, and defects such as bubbles, scratches, and peeling marks are not recognized, and the surface accuracy is also Within 2 Newton rings,
It was within 1/5 of the asbestos, 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. A concave optical surface 1 having a radius of curvature of 200 mm was formed by using cermet (TiC-10Mo-9Ni) 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. Platinum-tantalum-rhenium alloy (Pt-Ta-R
The thin film 2 of e) was coated. 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 press molding die.

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 preheated to 550 ° C., and the molten glass 14 is brought into contact with the second heat processing jig 16 immediately after the dropping, so that the second heat processing jig 16 is exposed to the molten glass 14. Attached. The second heat processing jig 16 having the molten glass 14 attached thereto was inverted by the arm 25, and the molten glass 14 was replaced with the second heat processing jig 16 as shown in FIG. After being thermally deformed by the second heat processing jig 16 at 780 ° C. for 5 minutes, press molding was performed by the press molding die 20. The press molding conditions were a mold temperature of 680 ° C., a pressing pressure of 80 kg / cm ² , and a pressing 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 23.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press molding surface is an optical mirror surface of about 20Å, and the Newton ring
The number of lines was less than 1/5 and the amount of as was less than one-fifth, 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. Rhodium-gold-tungsten alloy (R
h-Au-W) thin film 2 was coated. Similar to the second heat processing jig, the radius of curvature is 100 using silicon as the base material.
mm concave optical surface 1 is formed and sputtered with rhodium
A thin film 2 of gold-tungsten alloy (Rh-Au-W) was coated 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 and the balance was a heavy flint gas consisting of trace components.

After melting this glass at 1250 ° C., about 5 g of molten glass 14 was mixed from the nozzle 12 kept at 750 ° C. at a rate of 20 liters / minute of helium gas and 2 liters / minute of carbon dioxide gas into a molding machine in an atmosphere. It was dropped on the held first heat processing jig 24. First heat processing jig 24
The second heat processing jig 16 was brought into contact with the molten glass 14 immediately after dropping, and the molten glass 14 was attached to the second heat processing jig 16. The second heat processing jig 16 having the molten glass 14 attached thereto was inverted by the arm 25, and the molten glass 14 was replaced with the second heat processing jig 16 as shown in FIG. Second heat processing jig 16 at 610 ° 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 550 ° 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 23.

In the optical glass element 22 manufactured by such a process, the surface roughness (RMS) of the press-molded surface is an optical mirror surface of about 20Å, and defects such as bubbles, scratches, or peeling marks are not recognized, and the surface accuracy is also Within 2 Newton rings and within 1/5 ass, the optical performance was extremely excellent.

The manufacturing method of the optical glass element of the present invention and the manufacturing apparatus used for the method include a step of receiving the molten glass with the first heat processing jig in the non-oxidizing atmosphere, and a molten glass for the second heat processing jig. The step of inverting and replacing the molten glass and the second heat-processing jig in the state where they are bonded, the step of producing an optical glass molded body by thermal deformation with the second heat-processing jig, the optical glass molded body A method for producing an optical glass element including a step of heating and pressurizing with a press-molding die, and bringing the second heat-processing jig into contact with the molten glass received by the first heat-processing jig used in the method, The molten glass is attached to the second heat processing jig, and the second heat processing jig is inverted with the molten glass attached to the second heat processing jig, so that the molten glass is treated by the first heat processing jig. Of the optical glass element provided with means for replacing the tool with the second heat processing jig It is a manufacturing device, and the conditions such as molding atmosphere, optical glass composition, thin film composition to cover the thermal processing jig, temperature and time of thermal deformation, or shape of optical glass molded product are It is not limited to the examples.

EFFECTS OF THE INVENTION As described above, the method for manufacturing an optical glass element of the present invention and the manufacturing apparatus used for the method are such that after the molten glass is received by the first heat processing jig at a relatively low temperature, The second heat processing jig is brought into contact, the molten glass is attached to the second heat processing jig, and the second heat processing jig is inverted with the molten glass attached to the second heat processing jig. Stably replace the molten glass from the first heat processing jig to the second heat processing jig, and perform thermal deformation with the wrinkled surface of the optical glass on the second heat processing jig. . 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]

1 (a) to 1 (c) are sectional views of a first heat processing jig, a second heat processing jig, and a press molding die used in the present invention, and FIG. 2 is a manufacturing process of an optical glass element. 1 is a cross-sectional view of an embodiment of the present invention showing a device. 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 …… Pre-cylinder, 20 ……
Press molding die, 21 ... Conveyor, 22 ... Optical glass element, 23 ... Ejection port, 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 thermal processing jig in a non-oxidizing atmosphere, and a molten glass and a second thermal processing with the molten glass adhered to the second thermal processing jig. The step of inverting and replacing the jig, the step of producing an optical glass molded body by thermal deformation with the second heat processing jig, and the step of heating and pressing the optical glass molded body with a press molding die. A method for manufacturing an optical glass element including the same. 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 second heat-processing jig and press-molding die are processed into a desired shape and optical surface and are covered with a thin film which has good wettability with molten glass and is chemically stable. (1) The method for producing an optical glass element described in (1). 4. The thin film is a noble metal, tungsten, tantalum,
The method for producing an optical glass element according to claim 3, wherein rhenium or hafnium is a simple substance or an alloy thereof. 5. The molten glass received by the first thermal processing jig is brought into contact with the second thermal processing jig to adhere the molten glass to the second thermal processing jig so that the molten glass is Of the optical glass element provided with means for inverting the second heat processing jig in a state where it is attached to the heat processing jig and replacing the molten glass from the first heat processing jig with the second heat processing jig. Manufacturing equipment. 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 device according to claim 5, wherein the second heat processing jig is processed into a desired shape and optical surface and is coated with a thin film which has good wettability with the molten glass and is chemically stable. Glass element manufacturing equipment. 8. The thin film is a noble metal, tungsten, tantalum,
The optical glass element manufacturing apparatus according to claim 7, wherein rhenium or hafnium is a simple substance or an alloy thereof.