JP2002348129A - Method for manufacturing molding die for optical glass element and method for molding optical glass element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding die, for molding an optical glass element at a high temperature, which can be worked into a precise shape and has no cracks. SOLUTION: A cutting layer consisting of a Ni-P vacuum deposition layer is laid on a parent material composed of sintered hard alloys, cermets, ceramics, iron-based alloys and the like. The shape of the optical surface of the cutting layer is finished with a required degree of precision by high-precision cutting using a diamond cutting tool, and thereafter, is heat-treated at a temperature higher than the molding temperature by 10 deg.C or more. Furthermore, an optical glass element having a molding temperature range of 390-490 deg.C is molded by the use of a molding die for optical glass elements, which has a middle layer consisting of nitride or carbide ceramics and the like on the optical surface, which is the molding face, and a mold releasing layer of DLC film (a diamond- type carbon film) on the middle layer. Thereby, an optical glass element, fit for practical use, can be molded by continuous molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in forming a plastic lens having a free-form surface shape or a fine lattice shape, an electroless nickel plating layer made of Ni and P capable of ultra-precision cutting is cut with a diamond tool as a forming die. An optical mirror surface is obtained by processing. For those requiring a more precise optical surface, an optical mirror surface is obtained by polishing. In this case, since the molding temperature of the plastic is 200 ° C. or less, heat treatment was performed at a temperature in the range of 200 ° C. to 250 ° C. before cutting and polishing.

[0003]

However, in the above-mentioned conventional example, it is possible when the molding temperature is 200 ° C. or less like plastic, but in the press molding of glass, it is necessary to obtain high-temperature durability. It is necessary to heat-treat a vacuum deposited film made of Ni-P as a processing layer at a high temperature. However, when the heat treatment temperature is raised to 300 ° C. or higher, the crystallization of the film composed of Ni—P proceeds. I couldn't. Further, the thermal expansion coefficient of the base material is Ni-P
If the film is significantly different from the film composed of, there is a problem that cracks occur due to a difference in the amount of heat shrinkage when cooling after heating.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mold for a glass optical element which can be formed at a high temperature into a precise shape and has no cracks.

[0005]

According to the present invention, a thermal expansion coefficient of the present invention is 10 × 10 ^{−6 to} 16 ×.
After finishing a working layer made of Ni-P on a mold base material of ^10-6 by ultra-precision cutting using a diamond bite to a desired precision of the optical surface shape, it is higher than the forming temperature by 10 degrees or more. A method for producing a glass optical element molding die, comprising a step of performing a heat treatment at a temperature in the range of 400 ° C. to 500 ° C.

Further, an intermediate layer made of nitride or carbide ceramics and the like and a release layer of a DLC film (diamond-like carbon film) are provided on the molding surface formed by the above method, and the molding temperature is 390 ° C. A method for forming a glass optical element, comprising forming a glass at a temperature of 490 ° C.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Mold Production) As shown in FIG.
Heat-treated with a thermal expansion coefficient of 13 × 10 ⁻⁶ , mainly composed of iron, having a molding surface 41 processed within ± 10 μm from the required shape accuracy of the optical element molding surface (a concave shape having a radius of curvature of 20 mm). On the molding surface of the iron-based alloy mold base material 42,
Twenty molds each having a 50 μm-thick sputtering film made of Ni—P as a processing layer were prepared.

[0008] Of these, type 10 is a single-crystal precision diamond tool as it is, and is subjected to precision cutting within ± 0.1 µm from the required shape accuracy, and the other type 10 is heat-treated at 450 ° C for 1 hour in a non-oxidizing atmosphere. Later, the same precision cutting as described above was performed. At that time, the abrasion state of the diamond bite and the surface state of the processed layer were observed. Table 1 shows the processing results.

[0009]

[Table 1] Cutting results of electroless nickel plating

As can be seen from Table 1, Ni without heat treatment was used.
1 in the processing of the sputtering layer composed of -P
The surface roughness of the sputtered layer on which both the pattern and the pattern 10 were processed was good, and abrasion of the diamond bite did not occur. However, in the processing of the sputtered layer subjected to the heat treatment at 450 ° C. for 1 hour, the first mold did not suffer from bite wear, but the surface roughness was slightly coarser than that of the unheated mold. Further, in the tenth type, tool wear occurred and the surface roughness was extremely deteriorated. Cause is 450
This is probably because Ni of the sputtering layer composed of Ni-P was crystallized by the heat treatment at ℃ / 1 hour.
FIG. 3 shows the result of X-ray diffraction analysis of the state of crystallization of the sputtering layer composed of Ni—P with or without heat treatment. 3, no crystallization of Ni was observed without heat treatment, but a sharp peak of Ni (200), that is, crystallization was observed after heat treatment at 450 ° C. for 1 hour.

Next, the mold cut without heat treatment and the mold cut after heat treatment are heat-treated at 450 ° C. for 1 hour in a non-oxidizing atmosphere to change the surface shape and the surface roughness. The presence or absence of film peeling was confirmed. As a result, neither a change in the surface shape (see FIG. 4) nor a change in the surface roughness was observed for either type. Also, no film peeling was observed.

In preparation for forming a glass with the mold manufactured by the above two methods, 1 μm of TiN is formed on the glass forming surface of the mold, that is, the precision cut surface of the sputtering layer by a vacuum evaporation method. Then, a DLC film was formed thereon by 0.5 μm. Here, no deviation in the surface shape due to the formation of the two types of thin films was observed. FIG. 1 is a configuration diagram of the glass molding die of the present invention manufactured by the above method.
The manufacturing procedure is shown in FIG. In FIG. 1, 11 is a DLC
Reference numeral 12 denotes a TiN film, 13 denotes a precision-cut sputtering layer, and 14 denotes a mold base material. As mentioned above,
Table 2 shows the types of mold processing methods.

[0013]

[Table 2] Manufacturing method of glass molding die

(Molding test) Each mold manufactured by the two methods described above was continuously used with glass having a molding temperature of 400 ° C.
A molding test was performed 00 times to check the mold deformation, surface condition, film peeling, and molded product surface condition.

FIG. 6 is a schematic view of a molding state of the continuous molding.
Shown in Reference numerals 51 and 52 denote an upper die and a lower die having a radius of curvature of 20 mm. 53 is a spherical glass material adjusted to a desired volume. Reference numeral 54 denotes a press shaft to which the upper die is attached, which can be pressed with a load of 200 kgf. Furthermore, a heater, a glass material, a molded product stocker, and a handling mechanism (not shown) are provided. The glass material is manually supplied to the lower mold forming surface, heated, pressed at 400 ° C. for 5 minutes, and then released at 300 ° C. Mold and discharge the molded product by hand. This step was repeated 100 times. Table 3 shows the results of the molding test 100 times in succession.

[0016]

[Table 3] Continuous glass forming

As can be seen from Table 3, neither the mold of the present invention nor the comparative mold was deteriorated by continuous molding, that is, no change in the shape of the molded surface, an increase in surface roughness, the occurrence of peeling cracks in the sputtered film, and the like were not observed. . However, as described above, the surface roughness of the comparative mold is 50 nm, and this roughness is directly transferred to a molded product, and the molded product has a 50 nm swirling state. The molded product was coarser than 20 nm and could not withstand practical use.

On the other hand, the molded product of the mold of the present invention had a surface roughness of 10 nm even at the 100th shot, and was sufficiently practical.

[0019]

As described above, the thermal expansion coefficient is 1
On a base material of 0 × 10 ^{−6 to} 16 × 10 ⁻⁶ , such as cemented carbide, cermet, ceramics, iron-based alloy, etc., a deposition layer formed by Ni or P is formed by sputtering or ion plating as a cutting layer. After finishing the optical surface shape to a desired accuracy by ultra-precision cutting using a diamond bite, the cutting layer is heated at a molding temperature of 1%.
Heat-treated at a temperature higher than 0 degrees, furthermore the optical surface,
That is, a molding temperature of 390 ° C. is used by using a glass optical element molding die having an intermediate layer made of nitride or carbide ceramics on the molding surface and a release layer of a DLC film (diamond-like carbon film) on the upper surface. When a glass optical element in the range of -490 ° C was molded, an optical element that could withstand practical use in continuous molding could be molded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a glass molding die according to the present invention.

FIG. 2 is a view showing a manufacturing procedure of a glass molding die according to the present invention.

FIG. 3 shows a X of a sputtering film composed of Ni and P
It is a line diffraction analysis result.

FIG. 4 is an explanatory diagram showing a change in surface shape before and after heat treatment.

FIG. 5 is a view showing a metal mold having a precision-cut sputtering layer on a base material.

FIG. 6 is a schematic view of a continuous molding state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 DLC film 12 TiN film 13 Precisely cut sputtering layer 14 Mold base material 42 Iron-based alloy base material 43 Precisely cut sputtering processed layer 51 Upper die having a radius of curvature of 20 mm 52 Lower die having a radius of curvature of 20 mm 53 Spherical shape Glass material 54 Press shaft with upper die attached

Claims (3)

[Claims] In a method for manufacturing a glass optical element molding die in which a processing layer composed of Ni and P is formed by a vacuum deposition method, the processing layer is processed into an optical surface having a desired shape accuracy by cutting. A method for producing a mold for molding glass optical elements, wherein heat treatment is performed at a temperature higher than the molding temperature by 10 ° C. or more and 400 ° C./500° C. 2. A glass characterized by having a thermal expansion coefficient of 10 × 10 ^{−6 to} 16 × 10 ^−6, which is a material such as cemented carbide, cermet, ceramics, iron-based alloy or the like as a base material of the processed layer. A method for manufacturing a mold for molding an optical element. 3. An optical layer processed by the above method is provided with an intermediate layer made of nitride or carbide ceramics, and a release layer of a DLC film (diamond-like carbon film) on the upper surface thereof. A method for molding a glass optical element for molding glass in the range of 490 ° C.