JP2003192360A - Die for glass molding and method for manufacturing glass optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die good in precision of a formed surface, without a fear for long term reliability, and capable of preventing occurance of a detect of a glass element. <P>SOLUTION: The die 1 is polished after ground around forming faces 2a, 3a made of silicon carbide, and worked into a spherical surface of aspherical surface with a predetermined shape precision and a surface roughness R<SB>max</SB>of ≤25 nm, then subjected to 1,500-2,000°C heat treatment. Thereby the forming surface 2a, 3a, or other materials used around them can be strengthened. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for press molding of glass and a method for manufacturing a glass optical element using the mold.

[0002]

2. Description of the Related Art Various studies have been made on a technique for manufacturing a glass optical element with high precision by press-molding a glass material in a molding die. For example, as a mold for press-molding a glass material, a mold whose molding surface is made of silicon carbide (SiC), silicon nitride, or the like is known. Japanese Patent Publication No. 4-61816 discloses a mold having a hard carbon film formed on the surface of a mold made of silicon carbide by a sputtering method. Further, JP-A-2-199036 discloses a molding die in which an i-carbon film is coated by an ion plating method on a substrate made of silicon carbide whose surface is formed by a CVD method. In addition, JP-A 6-1
Japanese Patent No. 91864 discloses a processed surface of a molding die in which an i-carbon film and a hard carbon film are sequentially laminated.

[0003]

Silicon carbide, silicon nitride, and the like are excellent materials such as high temperature hardness and high temperature strength, and are suitable as a material for a molding die. For example, if the surface of the mold is manufactured by the CVD method, it is dense without defects such as pores,
A very smooth mirror surface can be obtained by polishing. Such materials have high resistance to oxidation at high temperatures. High resistance to oxidation means that the extreme surface is oxidized and it is difficult for it to progress in the depth direction. However, there is a problem in that an oxide layer having a thickness of about several tens of angstroms is formed on the extreme surface thereof, and the glass material softened by press molding easily causes glass fusion. Furthermore, when cooling after press molding, stress concentration occurs in places of the mold, so that a phenomenon in which the surface layer of the mold is spotted in a spot shape (hereinafter, this phenomenon is referred to as pull-out) may occur.

[0004] Japanese Patent Publication No. 4-61816 and JP-A-2-199
As disclosed in Japanese Patent No. 036, coating the surface of a silicon carbide or silicon nitride of a mold with a carbon-based thin film by a sputtering method or an ion plating method improves mold releasability and prevents fusion and pullout. It is an effective means for The adhesion between silicon carbide and silicon nitride and the carbon thin film is strong. Then, when the softened glass is pressed in a non-oxidizing atmosphere, the glass is not fused to the carbon-based thin film and the releasability is good. Therefore, the mold coated with the carbon-based thin film is effectively used as a mold for press lenses. However, a problem with the film forming technique is that it is difficult in terms of production technology to form a defect-free complete film over the entire press-molded surface of the mold. From a microscopic point of view, foreign matter may be attached at several places, or film blanks may be present.
Therefore, pull-out cannot be completely prevented.

Further, as the pressing is repeated, the carbon thin film is oxidized and consumed. That is, even if the press molding atmosphere is set to a non-oxidizing atmosphere, it is difficult to completely prevent oxidation due to moisture and oxygen inside and outside the glass, so that the carbon-based thin film is oxidized and consumed, which causes pull-out. . Therefore, after a certain period of time or a certain number of pressings, it is necessary to peel off the carbon-based thin film and perform a reclaiming operation to form a new carbon-based thin film. Even with such efforts, there is a certain probability that pullout will occur.

Further, the glass component may diffuse into the carbon-based thin film to weaken the adhesive force with SiC and cause film peeling. When the film is peeled off, the glass is fused to the SiC by the press, and stress is generated during cooling, so that the SiC is spotted and pulled out. When pullout occurs, the obtained glass optical element has a defect and becomes a defective product. Also, expensive molds can no longer be used. Incidentally, JP-A-8-277127 aims at reduction of pull-out from the viewpoint of the composition and characteristics of glass.

As described above, the carbon-based thin film and the glass composition can suppress the phenomenon of fusion and pull-out to some extent. However, in order to prevent defective glass optical elements, the carbon-based thin film must be regenerated. Even if the maintenance is performed frequently, fusion and pull-out occur early and late, which has been a problem in terms of productivity of highly accurate optical elements. In addition, if pull-out occurs, the mold itself cannot be used even if the carbon-based thin film is regenerated, which is a big problem in terms of production cost.

Originally, SiC is much stronger than glass. Nevertheless, as described above, for example, when the glass is fused or stress concentrates due to cooling, the phenomenon of losing the glass and being dug out occurs, which deteriorates the molding accuracy and the mold life. In this regard, the present inventor has found out the following. For example, SiC (hereinafter referred to as C
When VD-SiC) is ground and / or polished with diamond or the like, grinding scratches and polishing scratches are observed. There are slight microcracks under the scratches, and CVD-
It seems that SiC has grain boundaries because of grain growth. Such minute scratches and microcracks affect the surface strength of the die material, for example, SiC, and the SiC surface is dug when a force is applied. The same kind of problem exists in silicon carbide by hot pressing,
The mold is remarkably deteriorated due to particles falling off.

The present invention has been made on the basis of such findings, and solves the above problems by strengthening the surface itself of the material used for the molding surface or in the vicinity thereof, and a glass element to be molded. The object of the invention is to improve the service life of the molding die while preventing the defects of No. 1 and maintaining the precision of the molding surface in good condition.

[0010]

Means for Solving the Problems As a result of earnest studies, the present inventor has suppressed the occurrence of pull-out and drastically prolonging the life of the molding die by the following molding die and glass optical element manufacturing method. It was found that a glass optical element with high shape accuracy and surface accuracy can be efficiently produced.

That is, according to the first aspect of the present invention,
At least the molding surface or the vicinity of the molding surface is silicon carbide or nitrogen.
A mold for a glass molded body made of silicon oxide, comprising:
The part made of silicon carbide or silicon nitride is
Polished to a certain shape accuracy and R _maxSurface of less than 25nm
1500-20 after being processed into a spherical or aspherical surface
Characterized by being subjected to heat treatment at 00 ° C
A mold is provided.

Further, according to the second aspect of the present invention, there is provided a mold for a glass molded body, wherein at least the molding surface or the vicinity of the molding surface is made of silicon carbide or silicon nitride, and the molding die is made of silicon carbide or silicon nitride. The formed part is processed into a spherical surface or an aspherical surface having a predetermined shape accuracy and a surface roughness of 100 nm or less by R _max by grinding, then heat-treated at 1500 to 2000 ° C., and cooled, and then the spherical surface or the non-spherical surface. Provided is a mold characterized in that a silicon carbide surface or a silicon nitride surface having an R _max of 25 nm or less is produced by polishing a spherical surface.

According to a third aspect of the present invention, there is provided a molding die for a glass molded body, at least the molding surface or the vicinity of the molding surface of which is made of silicon carbide or silicon nitride. part comprising, after being processed into a spherical or aspherical surface roughness of not more than 50nm in grinding and a predetermined shape accuracy and R _{ma x} by polishing, 1500-200
Molding characterized in that a silicon carbide surface or a silicon nitride surface having a R _max of 25 nm or less is produced by polishing the spherical surface or aspherical surface after heat treatment at 0 ° C. and cooling. A mold is provided.

According to a fourth aspect of the present invention, the first aspect
A molding die according to any one of the third to third aspects, wherein the molding surface or the vicinity of the molding surface is made of silicon carbide.

According to the fifth aspect of the present invention, the fourth aspect
In the molding die according to the above aspect, there is provided a molding die characterized in that the molding surface or the vicinity of the molding surface is made of silicon carbide produced by a CVD method.

According to a sixth aspect of the present invention, the first aspect
A molding die according to any one of the fifth to fifth aspects, wherein the heat treatment is performed in a non-oxidizing atmosphere.

According to a seventh aspect of the present invention, the first aspect
A molding die according to any one of the sixth to sixth aspects, wherein a carbon-based thin film is formed on the molding surface.

According to an eighth aspect of the present invention, there is provided a molding die for a glass molded body, at least a molding surface of which or a vicinity of the molding surface is made of a silicon carbide produced by a CVD method. A forming die is provided, wherein the forming part is heat-treated at 1500 to 2000 ° C.

According to a ninth aspect of the present invention, the first aspect
Glass optical including a step of transferring the molding surface of the mold to the glass material to be molded by press-molding the glass material to be molded that has been softened by heating using the mold according to any one of the eighth to eighth aspects. A method of manufacturing the device is also provided.

Here, the molding surface means the surface of the molding die with which the glass element to be molded is in contact.

The meaning that the molding surface consists of silicon carbide or silicon nitride in or near the molding surface may mean that the molding surface consists of silicon carbide or silicon nitride, and on top of the part consisting of silicon carbide or silicon nitride. This means that a layer or film made of silicon carbide or silicon nitride having a different manufacturing method, or another composition may be applied. Preferably, by applying a carbon-based thin film to the surface of the mold, not only the releasability is improved, but also fusion and pullout are further prevented.

In the present invention, at least the molding surface or the vicinity of the molding surface is preferably made of silicon carbide produced by the CVD method. Only the molding surface or the vicinity of the molding surface may be made of silicon carbide by the CVD method, and the base of the molding die itself may be made of silicon carbide by the CVD method. In the former case, the material of the molding die other than the portion made of silicon carbide by the CVD method is not particularly limited, and known materials can be appropriately used. For example, a thin film of silicon carbide is CVD-deposited directly or through an intermediate layer on a base material such as cemented carbide.
You may form into a film by the method. Examples of the cemented carbide include tungsten carbide. There is also a mode in which the base of the mold is sintered SiC and the vicinity of the molding surface is CVD-SiC. Preferably, a base material made of silicon carbide by the CVD method is used, and the molding surface thereof is preferably provided with the above-mentioned carbon-based thin film.

When a silicon carbide thin film is formed by a CVD method on a base material other than silicon carbide, its thickness is 0.0
The thickness is preferably 2 [μm] to 2 [μm]. A thick film may be formed on the silicon carbide sintered body by the CVD method.

The above-mentioned carbon-based thin film is preferably a carbon thin film composed of an amorphous and / or crystalline single-component layer or a mixed layer having a graphite structure and / or a diamond structure, because it is particularly excellent in fusion preventing property. . Sputtering method,
It can be applied by an ion plating method or the like. You may make it a multilayer structure. Preferably, a hard carbon film formed by a sputtering method is laminated on an i carbon layer formed by an ion plating method to form a formed film.

The thickness of the carbon-based thin film is less likely to be consumed,
From the viewpoint of long-lasting effect, 0.02 [μm] or more is preferable. Also, if it is too thick, peeling easily occurs, so 0.5
[Μm] or less is preferable. In the case of the above-mentioned laminated layers, it is preferable that the total is within this range. At this time, i
-The carbon film thickness is 0.01 [μm] to 0.49 [μ]
m] is preferable, and 0.2 [μm] or less is more preferable. This is because when it is 0.01 [μm] or more, a very uniform film can be formed, and when it is 0.2 [μm] or less, a film having no distortion and particularly good mold adhesion can be obtained. Because. The thickness of the hard carbon film is 0.005 [μm]
It is preferable to be set to 0.2 [μm]. The reason is that, like the above, the film quality is the highest.

When molding a glass optical element using the mold of the present invention, a silicon carbide or silicon nitride portion, preferably a silicon carbide portion formed by a CVD method is ground and / or polished to have a predetermined shape. It is processed into a spherical surface or an aspherical surface with precision and surface roughness. Here, the predetermined shape accuracy is
The surface accuracy required as an optical lens is, for example, Newton ± 3, and ass and habit are within 0.5.

The surface roughness is set to R _max 25 [nm] or less before the heat treatment of the present invention, or R _max 100
If the heat treatment of the present invention is performed after the _{thickness is} [nm] or less and the surface having R _{max of} 25 [nm] or less is manufactured by cooling the molding surface after cooling, it is possible to manufacture a highly accurate molding surface. The surface roughness of the molding surface with high precision is preferably 10
[Nm] or less, more preferably 5 [nm] or less.

The surface roughness R _max as used herein refers to that according to the definition of JIS. That is, R _max represents the maximum height of the surface roughness standards. The maximum height refers to a value obtained by measuring the distance between two straight lines when the extracted portions are sandwiched by two straight lines parallel to the average line of the reference length extracted from the sectional curve in the longitudinal magnification direction of the sectional curve.
However, it is usually expressed in units of micrometer (μm), but in this application, the numerical value is small, so nanometer (nm)
It is expressed in units. In the examples of the present invention, measurement was carried out by a contact type measuring machine.

The glass material to be molded by the molding die and the manufacturing method of the present invention is not particularly limited, but barium borosilicate optical glass or the like is particularly effectively used. These glass materials are likely to cause fusion or pull-out, but the present invention is an example of a glass material that can be molded with high accuracy without impairing the mold life.

The glass composition is, for example, as a glass component,
₃₀ to 55 wt% of SiO ₂ and 5 to 30 wt% of B ₂ O ₃
(However, the total amount of SiO ₂ and B ₂ O ₃ is 56 to 70 wt% and the weight ratio of SiO ₂ / B ₂ O ₃ is 1.3 to 12.0), Li ₂
O of 7 to 12 wt% (excluding 7 wt%), Na
₀ to 5 wt% of ₂ O and 0 to 5 wt% of K ₂ O (however, Li ₂
The total amount of O, Na ₂ O, and K ₂ O is 7 to 12 wt% (however, 7
wt% is not included)), 10 to 30 wt% of BaO, M
0 to 10 wt% gO, 0 to 20 wt% CaO, Sr
0 to 20 wt% O, 0 to 20 wt% ZnO (however, B
The total amount of aO, MgO, CaO, SrO, and ZnO is 10
˜30 wt%), and the total content of SiO ₂ , B ₂ O ₃ , Li ₂ O, and BaO in the glass components is 72 wt% or more, and TeO ₂ is not contained. Optical glass is preferably used.

Alternatively, in the above glass, further, Al ₂
O _{3 is 1} to 7.5 wt%, P ₂ O ₅ is 0 to 3 wt%, La ₂
0 to 15 wt% O ₃ , 0 to 5 wt% Y ₂ O ₃ , Gd ₂ O
₃ to 0 to 5 wt%, TiO ₂ to 0 to 3 wt%, Nb ₂ O ₅ to 0 to 3 wt%, ZrO ₂ to 0 to 5 wt%, PbO to 0 to
Glass containing 5 wt% is preferably used.

As a specific glass material to be molded, Si is used.
O ₂ is 37.8 wt%, B ₂ O ₃ is 24.0 wt%, Al ₂
O ₃ 5.3 wt%, Li ₂ O 8.5 wt%, CaO 5.0 wt%, BaO 16.1 wt%, La ₂ O ₃ 3.3 wt%, As ₂ O ₃ 0.5 wt% , Sb ₂ O ₃ of 0.2 wt% and a glass transition point T _g of 500 ° C.

Further, as a concrete glass material to be molded
Is SiO₂47.2 wt%, B₂O ₃11.5 wt
%, Al₂O₃3.2 wt%, Li₂O is 7.3 wt
%, K₂O is 1.8 wt%, BaO is 21.8 wt%,
5.0 wt% ZnO, La₂O₃2.2 wt%, As
₂O₃Containing 0.5 wt% of glass transition point T_gIs 495 ° C
There are things such as

In the present invention, the heat treatment is performed at 1500 ° C. to 2 ° C.
It is carried out at 000 ° C. A pull-out prevention effect by diffusion bonding is significantly recognized by heat treatment at 1500 ° C or higher, and a heat treatment effect can be obtained without deteriorating the outer diameter dimension and molding surface shape of the mold by setting the temperature to 2000 ° C or lower. . Further, the heat treatment of the present invention is performed at 1500 ° C to 200 ° C.
The temperature is 0 ° C., preferably 1600 ° C. to 1800 ° C.

The molding die and manufacturing method of the present invention are not particularly limited in the shape of the glass optical element to be manufactured, and can be applied to a wide range of shapes and uses. In particular, it is effectively used for a convex meniscus lens having a flat shape with a thin edge. Further, examples of applications include optical elements for video cameras and digital cameras.

The heat treatment of the present invention is preferably performed in a non-oxidizing atmosphere. As the non-oxidizing atmosphere, for example, argon, nitrogen, hydrogen or the like can be used.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the present invention will be described below, but the present invention is not limited thereto. 1A and 1B are schematic cross-sectional views showing a molding die according to an example, where FIG. 1A shows a state immediately before pressing, and FIG. 1B shows a state during pressing. In this mold 1, the molding surface 2a of the upper mold 2 is an aspherical surface, and the lower mold 3 is
The molding surface 3a is a spherical surface. These pair of molds 2,
3 is made of SiC by the CVD method, and the molding surfaces 2a and 3a thereof have i-carbon films 21 and 3 respectively.
1 and the hard carbon films 22 and 32 are laminated in this order.

In FIG. 1, reference numeral 4 is a pair of molds 2,
The reference numeral 5 is a glass material to be molded. Further, as shown in FIG. 1 (b), the size of the pair of molds 2 and 3 is 17 [mm], and during the pressing, the heat-softened glass material 5 to be molded has a substantially diameter. It is extended to 15 [mm]. Hereinafter, Examples 1 to 3 will be described with reference to FIG. [Example 1] (1) Manufacturing method of a molding die Outer diameter processing was performed on upper and lower mold shapes of isotropic β-type SiC, which was entirely manufactured by a CVD method, and one of the pair of molds was non-machined. It was processed into a spherical surface and the other one was processed into a spherical surface.

First, an aspherical surface processing method will be described. First, using a metal-bonded diamond grindstone in a spherical grinder, a flat surface was processed into an approximate spherical surface, and then, in an aspherical grinder, processing was performed from a spherical surface to an aspherical surface. The shape accuracy at this time is about 10 [μm]. Next, using a resin-bonded grindstone, the shape accuracy was reduced to 0.
It was finished to 1 [μm]. And finally, after removing the grinding marks by using diamond paste in the aspherical polishing machine, the surface roughness is R _max of 5 [nm] while maintaining the shape.
Polished as follows.

Next, a method of processing a spherical mold will be described.
First, after using a metal-bonded diamond grindstone in a spherical grinder to machine a flat surface into a spherical surface, the aspherical grinder has a spherical shape accuracy of 2 [μm] to 3 [μm].
m] was processed. Next, in a spherical polishing machine, while using diamond slurry to remove scratches and the like in the foreground process, a predetermined radius of curvature and shape were obtained,
Further, the radius of curvature was set within the standard tolerance by making the shape such that the as-habit was 0.5 or less, and polishing was performed so that the surface roughness was 5 [nm] or less in R _max .

The aspherical surface type and the spherical surface type manufactured as described above were heated to 1600 ° C. in 2 hours in an Ar (argon) atmosphere, held for 1 hour, and then allowed to cool to room temperature. At this time, the surface roughness was R _max of 10 [nm]. Then, these molds were subjected to press molding.

On the other hand, as comparative samples, aspherical and spherical molds prepared in the same manner as above except that no heat treatment was performed were prepared.

(2) Press molding By the above method, the aspherical type for this example and the comparative example and
A large number of spherical molds were produced and the i-carbon film 2 was formed by a known method.
1,31 and the hard carbon film 22,32 by the sputtering method
A carbon-based thin film is formed by laminating barium borosilicate
Salt glass (SiO ₂: 37.8 [wt%], B₂O₃: 2
4.0 [wt%], Al₂O₃: 5.3 [wt%], Li
₂O: 8.5 [wt%], CaO: 5.0 [wt%],
BaO: 16.1 [wt%], La₂O₃: 3.3 [wt
%], As₂O₃: 0.5 [wt%], Sb₂O₃: 0.2
[Wt%], glass transition point T_gOf 495 ° C)
The molded glass material 5 is heated and softened in a nitrogen atmosphere,
Press molding was repeated at 610 ° C. Here press
The carbon-based thin film is removed once every 500 moldings, and a new carbon-based
The film formation was repeated.

As a result, in the molding die according to the comparative example, pull-out occurred after averaging 10,000 presses, whereas in the molding die according to this example, the pull-out did not occur up to 15,000 times on average, and the die life was extended. Further, the molding surface of this molding die could be continuously transferred to the glass material to be molded with high accuracy.

Example 2 (1) Manufacturing Method of Mold For both the aspherical surface type and the spherical surface type, the processing steps before the heat treatment are the same as in the first embodiment. In Example 1, the heat treatment was performed at 1600 ° C, but in Example 2, it was performed at 1800 ° C. After the heat treatment, the surface roughness R _max was 25 [nm]. The aspherical surface type was again polished in an aspherical surface polishing machine so that the surface roughness was 5 [nm] or less at R _max and the processing was completed. On the other hand, the spherical type is again in the spherical polishing machine and the surface roughness R _max is 5 [n without deteriorating the shape and curvature.
m] or less, and the processing was completed.

(2) Press molding When press molding was carried out in the same manner as in Example 1, the number of presses at which pullout occurred was extended to an average of 20,000, and the die life was further extended.

(3) AFM Observation After Etching After polishing after heat treatment and after polishing with heat treatment, the surface was etched with hydrofluoric acid and the surface was observed with AFM (atomic force microscope). It was observed that the processing flaws were shallower than those without heat treatment. It seems that the micro-cracks on the surface of the CVD-SiC were diffusion bonded.

[Embodiment 3] In Embodiment 2, after grinding the aspherical surface and the spherical surface, polishing is carried out until R _max becomes 5 [nm], and then heat treatment is carried out. However, the same heat treatment as in Example 2 was performed, and then polishing was performed up to R _max of 5 [nm]. As a result of press molding, the same results as in Example 2 were obtained.

[0049]

As described above, according to the present invention, fusion and pull-out that occur on the surface of the molding die can be prevented, and as a result, the life of the molding die can be significantly extended. As a result, the maintainability of the molding die is improved, and the glass optical element having excellent surface accuracy can be efficiently manufactured.

Further, in the molding die of the present invention, slight grinding scratches generated on the surface of CVD-SiC during heat treatment and microcracks generated under polishing scratches are diffusion-bonded, so that the molding surface Surface strength is improved. This suppresses fusion and pull-out due to pressing. Further, due to the pull-out prevention effect, the choice of glass materials to be molded by the precision press is expanded, and the degree of freedom in manufacturing can be expanded.

Providing a mold release film on the surface of the molding die is effective in preventing fusion and pullout, but in the present invention, by further strengthening the material of the die itself, fusion and pullout are further suppressed. Further, when the carbon-based thin film is provided, the releasing effect can be further enhanced. Further, even if the carbon-based thin film is exhausted, pull-out is prevented, so that if the carbon-based thin film is regenerated, it is possible to repeatedly use the carbon-based thin film. That is, when a carbon-based thin film is used, the carbon-based thin film and the strengthening of the die material by the heat treatment of the present invention cooperate with each other, and the life of the die can be further extended.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a mold according to an embodiment,
(A) shows the state immediately before pressing, and (b) shows the state during pressing.

[Explanation of symbols]

1 Mold 2a, 3a Molded surface 5 Molded glass material 21, 31 i-carbon film (carbon-based thin film) 22, 32 Hard carbon film (Carbon thin film)

Claims (9)

[Claims] 1. A molding die for a glass molded body, wherein at least a molding surface or the vicinity of the molding surface is made of silicon carbide or silicon nitride, and the portion made of silicon carbide or silicon nitride is ground and polished to a predetermined shape. After being processed into a spherical surface or an aspherical surface having a surface roughness of 25 nm or less in shape accuracy and R _max , 1500-2
A mold which has been heat-treated at 000 ° C. 2. A molding die for a glass molded body, at least the molding surface or the vicinity of the molding surface of which is made of silicon carbide or silicon nitride, wherein the portion made of silicon carbide or silicon nitride has a predetermined shape accuracy by grinding. After being processed into a spherical surface or an aspherical surface having a surface roughness of R _max of 100 nm or less, 1500 to 200
Molding characterized in that a silicon carbide surface or a silicon nitride surface having a R _max of 25 nm or less is produced by polishing the spherical surface or aspherical surface after heat treatment at 0 ° C. and cooling. Type. 3. A molding die for a glass molded body, at least the molding surface or near the molding surface of which is made of silicon carbide or silicon nitride, wherein the portion made of silicon carbide or silicon nitride has a predetermined shape by grinding and polishing. After being processed into a spherical surface or an aspherical surface having a surface roughness of 50 nm or less with accuracy and R _max ,
Molding characterized in that a silicon carbide surface or a silicon nitride surface having an R _max of 25 nm or less is produced by polishing the spherical surface or aspherical surface after heat treatment at 2000 ° C. and cooling. Type. 4. The molding die according to claim 1, wherein the molding surface or the vicinity of the molding surface is made of silicon carbide. 5. The mold according to claim 4, wherein the molding surface or the vicinity of the molding surface is made of silicon carbide produced by a CVD method. 6. The mold according to claim 1, wherein the heat treatment is performed in a non-oxidizing atmosphere. 7. The molding die according to claim 1, wherein a carbon-based thin film is formed on the molding surface. 8. A CV at least on the molding surface or in the vicinity of the molding surface.
A molding die for a glass molded body made of silicon carbide produced by a method D, wherein the portion made of silicon carbide is 1500 to 2000 ° C.
Molding die characterized by being subjected to the heat treatment of. 9. A molding surface of the mold is formed by press-molding a glass material to be molded, which has been softened by heating, by using the molding die according to any one of claims 1 to 8. A method for manufacturing a glass optical element including a step of transferring to a material.