JP2002348128A - Molding die for press molding of optical glass element and glass element molded by the molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding die for press molding capable of repeated press moldings of various shapes of optical glass elements, and glass elements molded by the molding die. SOLUTION: A cutting layer consisting of super heat-resistant polyimide is laid on a base metal for the molding die and the surface of the molding die is worked by cutting. Furthermore, the first surface is coated with i-C to prevent fusion bonding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical glass element, and more particularly, to a press-molding die for an optical glass element used for press-forming a high-precision optical glass element, and a method for forming the same. The present invention relates to a glass element formed by using the glass element.

[0002]

2. Description of the Related Art In order to repeatedly mold a high-precision optical glass element by press molding, as a mold material family, it is stable even at the molding temperature of glass, has excellent oxidation resistance, and is inert to glass. It is necessary to have something with excellent mechanical strength so that the shape accuracy does not collapse when it is done, but on the other hand,
It must be easy to process and easy to machine.

[0003] As a mold material which satisfies the conditions necessary for the press mold for optical glass elements as described above to some extent, a mixed material family of titanium carbide (TiC) and metal (for example, JP-A-59-121126) and Ultra Noble metal thin film formed on a hard alloy base material (for example, Japanese Unexamined Patent Publication No. 62-96331)
No.) are being considered.

[0004]

However, the conventional section members do not satisfy all the above conditions.
For example, when a mixed material of titanium carbide (TiC) and a metal is used as a mold material, it is very hard and has excellent mechanical strength, but is inferior in workability and difficult to perform high-precision work. Further, it has a disadvantage that it easily reacts with lead (Pb) or an alkali element which is a component of the optical glass element.

Further, in a mold in which a noble metal thin film is formed on a cemented carbide base material, if the cemented carbide is machined using a diamond grindstone, the diamond grindstone is severely worn, and precise shape machining is difficult. Special processing equipment is required. Further, there is a problem that the processing time is long and the die cost is very high.

As a remedy, a thin film having good adhesion to a base metal is formed on a cemented carbide base material, and an electroless Ni—P plating film, for example, is formed on the thin film as a film that can be easily processed with precision. A method of forming an alloy thin film as a protective film (for example, JP-A-3-23230) has been studied.

However, in this method, electroless Ni-
There is a problem that the heat resistance and strength of the P plating film are low and the film peels off during molding.

[0008] As described above, the conventional mold material has not yet satisfied all of the requirements for the mold material described above.

The present invention solves such a conventional problem,
It is an object of the present invention to provide a press-molding die capable of repeatedly press-molding optical glass elements having various shapes which could not be realized by conventional grinding and polishing.

[0010]

In order to achieve the above object, a first invention according to the present invention is directed to an optical element molding die used for press molding of an optical element made of glass, comprising: A cutting layer made of a super heat-resistant polyimide resin molded body.

In the above configuration, the super heat-resistant polyimide resin molded article has sufficient strength and hardness as a glass element molding die, and is excellent in workability (cutting is possible). The mechanical strength required for the mold is mainly attributable to the mold base material. Therefore, it is excellent in oxidation resistance required for optical glass element molding dies, is inert to glass, has excellent mechanical strength that does not lose shape accuracy when pressed, and has excellent workability, precision processing Completely satisfy the condition that it must be able to be done easily. Note that a substance expressed as a super heat-resistant polyimide in the present invention indicates a polyimide resin that does not thermally decompose at 500 ° C. or lower.

In a second aspect of the present invention, the molding surface is machined into a desired shape by cutting, and a diamond film, a diamond-like carbon film, a hydrogenated amorphous carbon film (iC film) is formed on the molding surface. ) And a hard carbon film.

In the above configuration, the super heat-resistant polyimide resin molded body has sufficient strength and hardness and can be cut, so that precision processing can be easily performed. Furthermore, no special equipment is required for processing. Processing time is also short. Therefore, the mold cost can be extremely reduced. Furthermore, it has become possible to produce surfaces that can only be made by cutting. Also, as compared with a method of forming a plating layer and cutting the layer, this base material is superior in heat resistance, so that it can be used for molding of high melting point glass and does not differ from plating. Further, in the above configuration, by using a coating of one type of film selected from a diamond film, a diamond-like carbon film, a hydrogenated amorphous carbon film (i-C film), and a hard carbon film on the molding surface, In addition to preventing fusion of the glass with the mold and obtaining good mold releasability between the mold and the glass. Therefore, the mold of the present invention satisfies all the necessary conditions required for the mold material described above. Therefore, it becomes possible to repeatedly press-mold optical glasses having various shapes, which cannot be realized by conventional grinding.

A third invention according to the present application is directed to a super heat-resistant polyimide resin molded article on the molding die base material, which is obtained by polycondensation of biphenyltetracarboxylic dianhydride (BPDA) and diamine, thereby obtaining a wholly aromatic resin. It is a molded product of a polyimide resin.

Biphenyltetracarboxylic dianhydride (B
A molded article of a wholly aromatic polyimide resin by polycondensation of PDA) and a diamine has no melting point and is thermally decomposed at 540 ° C. or higher. Therefore, if used below this temperature, it can be used favorably. Therefore, the glass that can be molded with the mold material of the present invention is limited to a glass having a molding temperature of 540 ° C. or lower, but many commercially available glass molding glasses satisfy this condition. In addition, this material can be subjected to mirror finishing required for a glass forming die. That is,
This is because this material can be cut and has a porosity of zero. An additive may be added to this material in order to improve heat resistance, improve adhesion with a mold base material, or improve mold releasability from glass.

A fourth invention according to the present application is characterized in that the desired shape is a shape that cannot be produced by grinding and polishing.

A fifth invention according to the present application is a glass element press-formed using a mold that cannot be manufactured by grinding and polishing. In the past, such glass elements could not be produced because mold processing was not possible.

With the above configuration, it is possible to mass-produce an optical element having a shape which cannot be realized conventionally.

[0019]

An embodiment of the present invention will be described below with reference to the drawings.

A super heat-resistant polyimide resin molded body having a diameter of 16 mm and a thickness of 100 mm is mounted on a cemented carbide, and is used for press molding a pair of optical glass lenses composed of upper and lower molds having a concave press surface having a radius of curvature of 10 mm. The mold was machined by grinding with a cemented carbide tool.

Next, the pressed surface was finished to a very high precision by cutting with a diamond tool. As described above, by cutting the ultra-heat-resistant polyimide resin molded body, a highly accurate surface conventionally obtained only by polishing is obtained. In addition, it has become possible to produce surfaces that can only be made by cutting. Table 1 shows the types of the super heat-resistant polyimide resin moldings used.

[0022]

[Table 1]

In FIG. 1, reference numeral 1 denotes a mold base material (a cemented carbide), and reference numeral 2 denotes a super heat-resistant polyimide resin formed by cutting.

In this embodiment, a cemented carbide is used as the base material. However, if the material has excellent strength and heat resistance, it is OK.
Met. Examples of the test include cermet, silicon nitride, and the like containing titanium carbide or titanium nitride as a main component.

Further, in this embodiment, the base material and the super heat-resistant polyimide resin molded body are screwed by cutting both members with screws. However, bonding with an adhesive for ceramics, caulking, and other members are used. Any joining method, such as joining via a wire, may be used. Alternatively, a polyimide obtained by dissolving a heat-resistant polyimide precursor in a solvent is applied to a mold base material, and then heated to cause a dehydration cyclization reaction, thereby forming a polyimide on the base material.

Next, a diamond film, a diamond-like carbon film, a hydrogenated amorphous carbon film (i-C
Film) and a hard carbon film.

The diamond thin film is formed by a microwave plasma CVD method, a hot filament CVD method, a plasma jet method, an electron cyclotron resonance plasma CVD method or the like, and the DLC film, aC: H film and the hard carbon film are formed by a plasma CVD method. , An ion beam sputtering method, an ion beam evaporation method, a plasma sputtering method or the like. Examples of the gas used for forming the film include hydrocarbons such as methane, ethane, propane, ethylene, benzene, and acetylene, which are carbon-containing gases; halogenated hydrocarbons such as methylene chloride, carbon tetrachloride, chloroform, and trichloroethane; methyl alcohol , Alcohols such as ethyl alcohol;
Ketones such as (CH ₃ ) ₂ C0 and (C ₆ H ₅ ) ₂ Co;
Gases such as CO and CO ₂ , and N ₂ ,
A mixture of gases such as H ₂ , O ₂ , H ₂ O, and Ar can be used.

Next, an optical element was molded using the resin molds shown in Table 1 obtained as described above.

The glass was CD45 (made by Sumita Optical Glass Co., Ltd., lead-free SF8 equivalent glass, nd 1.69)
320, νd 33.7, Tg 456 ° C, At 50
8 ° C., see Table 2 for composition) and PSK50 (SK2 equivalent glass, manufactured by Sumita Optical Glass Co., Ltd., nd 1.593)
80, νd 61.4, Tg 381 ° C, At 403
The composition was processed into a ball lens using C.C. and the composition shown in Table 3).

[0030]

[Table 2]

[0031]

[Table 3]

FIG. 2 shows the outline of the apparatus used for the molding test. In FIG. 2, 24 is a chamber, 25 is an upper shaft, 26
Is a lower shaft, 27 is a block with a built-in heater (heater block), 28 is a heater block, 29 is an upper mold,
0 is a lower mold, 31 is glass, and 32 is a hydraulic cylinder.

After the chamber 24 is evacuated by a vacuum pump (not shown), N 2 gas is introduced, and
After the inside of the heater block 4 is set to the N2 atmosphere,
8, the upper mold 29 and the lower mold 30 are heated, and the temperature (CD4) corresponding to 10 ガ ラ ス 9 d · Pa · s in the viscosity of the glass to be formed.
5: 540 ° C., PSK 50: 425 ° C.), the upper shaft 25 is pulled up by the hydraulic cylinder 32 and the lower die 3
A molding material (ball lens) was placed on top of the lens 0 by an automatic hand (not shown). After holding for 1 minute at the same mold temperature, the upper shaft 25 is lowered by the hydraulic cylinder 32,
The ball lens was pressed by the upper mold 29 and the lower mold 30 with a force of 3,000 N for 3 minutes. Thereafter, cooling is performed at 70 ° C./min, and when the upper and lower mold temperatures reach 340 ° C., the upper mold 29 is raised, and the molded product 3 on the lower mold 30 is moved by an auto hand (not shown).
Then, the molded product 31 was taken out of the chamber 24 through a replacement device (not shown).

The upper and lower molds were heated again, and the above operation was repeated to perform 5,000 shot molding. 5,000sh
As a result of molding ot, all the molds shown in Table 1 (Example 1)
~ 3) Good moldability was obtained.

After the step-like mold shown in FIG. 3 was machined by cutting with a carbide tool, the pressed surface was finished with very high precision by machining with a diamond tool. Thus, by cutting the super heat-resistant polyimide resin molded body provided on the base material, it becomes possible to process a surface that cannot be obtained by conventional grinding and polishing.

The same test as described above was conducted for this mold, but exactly the same results were obtained. This molded product is a kind of diffraction grating, and is an example of a so-called fine optical element.

The shapes that cannot be processed by grinding and polishing here include an element having a free-form surface (a so-called free-form surface element), an element having a fine pattern (a so-called fine optical element), and each polar shape (spherical or aspherical). And planes) are combined to form a mold having a complicated shape that cannot be manufactured by polishing or are bonded together, and a combination of these shapes.

[0038]

As described above, according to the first aspect of the present invention,
In producing a press mold for optical glass elements,
According to the second aspect of the present invention, all necessary conditions required for a glass forming mold material are satisfied by using a cutting layer formed of a super heat-resistant polyimide resin molded body on a base material for the forming surface. Is processed into a desired shape by cutting, and the formed surface is coated with one kind of film selected from a diamond film, a diamond-like carbon film, a hydrogenated amorphous carbon film (iC film) and a hard carbon film. This provides a press-molding die capable of press-molding optical glasses of various shapes, and was not obtained by conventional press-molding by repeatedly press-molding optical glass using this mold. It has become possible to produce optical glass elements having a low cost and in large quantities.

According to the third aspect of the present invention, the super heat-resistant polyimide resin molded article is a wholly aromatic polyimide resin molded article by polycondensation of biphenyltetracarboxylic dianhydride (BPDA) and diamine. As a result, while being a resin material, it can withstand the temperature at which glass is formed, and it is possible to perform mirror processing while being able to perform cutting, reducing the time and cost of processing a mold and making processing difficult until now. Shapes can now be made.

According to the fourth and fifth aspects of the present invention, a mold having a shape that could not be produced by the conventional grinding and polishing method can be produced. Can now be obtained.

Accordingly, it has become possible to produce optical glass elements having shapes that could not be obtained by conventional press molding inexpensively and in large quantities.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the present invention.

FIG. 2 is a schematic sectional view of a press forming apparatus for an optical element.

FIG. 3 is a schematic sectional view of a press mold for an optical element.

[Explanation of symbols]

Reference Signs List 1 mold base material 2 super heat-resistant polyimide resin molded body (pressed surface processed by cutting) 24 chamber 25 upper shaft 26 lower shaft 27 heater block 28 heater block 29 upper die 30 lower die 31 glass 32 hydraulic cylinder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (72) Inventor Keiji Hirabayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (5)

[Claims] 1. An optical element molding die used for press molding an optical element made of glass, wherein a cutting layer made of a super heat resistant polyimide resin molded body is provided on a molding surface on the mold base material. Press mold for glass elements. 2. A molding surface of the optical element molding die is processed into a desired shape by cutting, and a diamond film, a diamond-like carbon film, a hydrogenated amorphous carbon film (iC film) is formed on the molding surface. 1 selected from carbon and hard carbon films
The mold for press-molding an optical glass element according to claim 1, wherein a seed film is coated. 3. The super heat-resistant polyimide resin molded article on the molding die base material is a wholly aromatic polyimide resin molded article by condensation polymerization of biphenyltetracarboxylic dianhydride (BPDA) and a diamine. 3. The mold for press-molding an optical glass element according to claim 1, wherein: 4. The mold according to claim 2, wherein the desired shape is a shape that cannot be processed by grinding and polishing. 5. A glass element press-formed using the press-molding die according to claim 4.