JPH0350127A - Method for manufacturing a mold for molding an optical glass element and method for manufacturing an optical glass element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a mold for molding an optical glass element for forming high-precision optical glass elements such as lenses and prisms used in optical equipment by an ultra-precision glass molding method. and a method for manufacturing an optical glass element.

BACKGROUND OF THE INVENTION In recent years, as a manufacturing method for high-precision optical lenses, especially aspherical glass lenses, many attempts have been made and are being realized by one-shot molding without using an optical polishing method and without a polishing process. One of the molding methods is to heat the glass material to a temperature at which it can be deformed, for example, to a temperature near its softening point, and then mold the glass material using means such as press molding. The molds for molding optical glass elements used in these molding processes are required to have extremely high precision surface shapes and quality. This mold is chemically inert to glass when pressed at high temperatures, the glass press surface of the mold is sufficiently hard and resistant to damage such as scratches, and the glass press surface is sufficiently hard to resist damage such as scratches. does not cause plastic deformation and is heat resistant.

It is necessary to have excellent thermal shock resistance, good mold workability, and the ability to perform precision processing.

To achieve this purpose, for example, a press molding mold using silicon carbide or silicon nitride (Japanese Unexamined Patent Publication No. 52-45613), a base material of tungsten carbide, cermet, or zirconia, and a precious metal on this base material are used. Press molding molds and the like constructed by forming an alloy film have been proposed, and various studies are being conducted.

Problems to be Solved by the Invention However, in order to finish the above-mentioned molds, such as silicon carbide, silicon nitride, tungsten carbide, zirconia, cermet, and precious metal alloy films, into the desired surface shape, grinding with a diamond grindstone is required. I will finish it. However, since the material of the mold having the above-mentioned structure is extremely hard, the diamond grinding wheel is severely worn, making it difficult to perform high-precision machining, and it takes a very long time to meet the required precision. for example,
When machining large-diameter molds, accuracy cannot be met unless the amount of wear is checked while machining. Furthermore, the number of mold surfaces to be machined with one grindstone is small. Further, in the case of a small diameter, there is no diamond grindstone that can be processed if the radius of curvature is extremely small. As described above, due to processing limitations, the range of mold shapes that can be created is narrow, and the processing time is long, making the molds extremely expensive. If a material is used that takes only workability into account, the processing time will be shortened and a mold with good shape accuracy will be produced, but the problem will be that the mold life will be short. Furthermore, since it is difficult to process a sufficient surface shape, the performance of optical glass elements molded using the above-mentioned molds has not been satisfactory.

Means for Solving the Problems In order to solve the above problems, the present invention uses a cemented carbide mainly composed of tungsten carbide, or titanium carbide, titanium nitride, chromium carbide, or alumina as the base material of the mold. After processing these base materials into a state close to the desired shape by grinding using cermet as a component, nickel-phosphorus, a nickel metal with excellent machinability, high melting point, and chemical stability, is placed on the base material. An alloy whose main component is nickel-boron or an alloy whose main component is nickel-boron is formed as an intermediate layer, and after precisely processing it into a desired shape by cutting or grinding, a metal layer is formed as a protective film on the intermediate layer. Means for producing a mold for molding an optical glass element by forming a nitride, metal shelving, metal carbide, iridium-tungsten alloy, ruthenium-tungsten alloy, iridium-tantalum alloy, iridium-rhenium alloy, or ruthenium-rhenium alloy film is used.

Function The present invention has an intermediate layer with excellent grinding and cutting workability through the above-mentioned means, so that it has become possible to easily obtain a highly accurate surface shape. Additionally, since there is no need to process extremely hard materials, there is almost no wear on the diamond tool or grinding wheel, and the life of the diamond tool is longer, making it possible to create many large-diameter molds with a single tool and grinding wheel. . In addition, cutting with a diamond cutting tool has become possible, allowing molds with a small radius of curvature to be machined, expanding the range of machining. Furthermore, since the base material 2 protective film is made of a material with excellent surface quality, heat resistance, and impact resistance, it is easy to create a mold that has both good workability and mold life. By press molding, it became possible to obtain an inexpensive optical glass element with a highly accurate surface shape.

EXAMPLE Hereinafter, a method for manufacturing a mold for molding an optical glass element and a method for manufacturing an optical glass element according to an example of the present invention will be described with reference to Table 9 of the drawings.

First, we conducted an experiment on the workability of the material used as the intermediate layer. In the experiment, various materials were used with a diameter of 8 circles and a radius of curvature of 7.51.
It was decided to finish it in a concave shape of 1IIn. Since it is not possible to obtain objects of the above-mentioned size depending on the material, we decided to use cemented carbide as the base material and create a shape close to the desired shape, and then form the material on the base material and process it. The machining method involves cutting with a diamond cutting tool and grinding with a diamond grindstone on various materials.The evaluation method is to measure the surface shape using an interferometer and evaluate the machinability based on the machining accuracy. Approved. The experimental results are shown in Table 1.

Table 1. Various Materials Machinability Experimental Results The experimental results showed that nickel, nickel-phosphorus alloy, and nickel-boron alloy can be cut and have good machining accuracy. Other materials cannot be machined because they are extremely hard and the diamond tool wears out instantly.

Furthermore, grinding also causes wear, which takes a very long time. The surface shape after processing is also not satisfactory.

Next, we will show the surface shape when the mold surface is continuously cut using cemented carbide as the base material and nickel is formed on it, and the surface shape when the mold surface is continuously cut after forming an iridium-tungsten alloy on the cemented carbide. An experiment was conducted to confirm the change in surface shape after processing.

The shape of the created mold is 42 mm in diameter and 18.3 mm in radius of curvature.
The base material was processed in advance into a shape similar to that of the concave shape. The results are shown in Table 2.

Table 2. Continuous machining experiment results for nickel and iridium-tungsten alloy *unit (λ) When machining a nickel surface, it is possible to obtain a highly accurate surface shape, and there is no wear of the diamond grinding wheel (and many formed surfaces can be created) I understand.

On the other hand, when processing an iridium-tungsten alloy film, the first mold met the accuracy, but as the number of molds increased, the accuracy deteriorated, and the fifth mold could not be processed.

As can be seen from Table 19 and Table 2, it was experimentally confirmed that the nickel, nickel-phosphorus alloy, and nickel-boron alloy used as the intermediate layer in the present invention have good workability, and have a long life without wear of the diamond cutting tool. Additionally, processing time can be significantly reduced compared to other materials. With the above materials, even large-diameter molds can be machined with high accuracy on multiple mold surfaces with a single diamond bit. In addition, in cutting processing, the radius of the cutting tip of the diamond tool can be made smaller than in grinding processing, and molds having surfaces with a small radius of curvature can be processed, which greatly expands the processing range. Although not listed here, nickel, nickel-phosphorus alloys, nickel-boron alloys, nickel-phosphorus-based alloys, and nickel-boron-based alloys are chemically stable with a high melting point and workability similar to or higher than nickel-phosphorus alloys. There is no problem with using .

Next, a method for manufacturing a mold and a method for manufacturing an optical glass element of the present invention will be explained.

FIG. 1 is a process schematic diagram of the method for manufacturing a molding die of the present invention. 1 is a base material, 2 is an intermediate layer, and 3 is a protective film.

Cemented carbide and cermet with a diameter of 30 mm and a thickness of 6 ff I11 are used as the base material for a pair of molds consisting of an upper mold and a lower mold with concave radii of 141 and 20 mm, and are rough-processed by grinding. The amount of deviation was set to 10 μm or less. It is shown in FIG. 1(a). Next, an intermediate layer of nickel, an alloy containing nickel-phosphorus as a main component, or an alloy containing nickel-boron as a main component was formed on these base materials to a thickness of 15 μm by ion blasting. It is shown in FIG. 1(b). Thereafter, it was finished into the desired shape with high precision by cutting with a diamond cutting tool. It is shown in FIG. 1(C).

Finally, a film of metal nitride, metal carbide, metal shelf, iridium-tungsten alloy, ruthenium-tungsten alloy, iridium-tantalum alloy, iridium-rhenium alloy, or ruthenium-rhenium alloy was formed on the intermediate layer. In any of the molds shown in Figure 1(d), the shape accuracy required for the optical glass element (RM30
．． 04λ or less) was easily achieved. By providing an easy-to-cut intermediate layer as described above, there is no need to process extremely hard materials, the machining time is significantly shortened, and a mold with a highly accurate surface shape can be created at a low cost. .

Needless to say, the intermediate layer and the protective film may be formed by a method other than the sputtering method or the ion blasting method.

Figure 2 shows a pair of upper and lower molds set in a press machine. 4 is an upper mold, 5 is a lower mold, 6 is a heater for the upper mold, 7 is a heater for the lower mold, 8
9 is a pressure mechanism for the upper mold, 9 is a pressure mechanism for the lower mold, 10
11 is a supply glass, 11 is a glass supply jig, 12 is an outlet for the press-molded optical glass element, 13 is a preheating furnace for the supply glass, and 14 is a chamber.

In the press experiment, a glass material 7 made of lead oxide-based optical glass made of 70% by weight of lead oxide (Pb0), 27% by weight of silica (SiO□), and the rest being trace components was processed into a spherical shape with a radius of 10 mm, and the glass material 7 was placed in a preheating path. After heating at 10°C, it was placed on the lower mold 5 of the upper and lower molds 4.5 held at 550°C, and a press pressure of 5 kg/mm was applied with the upper mold 4 in a nitrogen gas atmosphere.
Transforms the glass material. After the transformation is completed, remove the upper mold, lower mold, and glass material.
Cool to 80°C.

Then, the molded optical glass element is taken out from the take-out port 12 and cooled to room temperature. After repeating the above molding process 5000 times with molds made of each material, molds 4 and 5
was removed from the press machine, and the shape accuracy and surface roughness of the mold surface were measured to evaluate the quality of the mold.

Pressing of a forming die that uses cemented carbide as the base material, forms nickel or nickel-phosphorus alloy as the intermediate layer, and then forms metal nitride, metal carbide, metal shelving, or other alloy on the intermediate layer. Table 3 shows the evaluation results after molding.

Table 3. Press evaluation of the mold of each configuration when the base material is cemented carbide (04!, ! (II) in the S Fruits and Vegetables table) indicates that there is no change in shape, etc.

After 5000 moldings in any mold configuration,
No surface roughness or change in shape was observed on the mold.

Adhesion between the base material, intermediate layer, and protective film was good, and there was no peeling of the film during molding. In addition, no reaction with glass was observed for each protective film. It can be said that it has a sufficient lifespan as a mold for molding optical glass elements. In addition, the shape of the molded optical glass element is a good transfer of the shape of the mold and satisfies the performance of the optical glass element. In the embodiment, the intermediate layer was made of nickel, a nickel-phosphorus alloy, and a nickel-boron alloy, but there is no problem in providing an intermediate layer of an alloy containing nickel-phosphorus as a main component or an alloy containing nickel-boron as a main component.

Effects of the Invention As described above, the method for manufacturing a mold for molding an optical glass element of the present invention does not require processing the base material or protective film, which are extremely hard materials, and uses an intermediate layer with good workability, making it possible to process diamond bits. It is possible to extend the lifespan, and molds with good surface shapes can be easily created in a short time. Since cutting processing is possible, it is possible to create molds with a small radius of curvature.
Since there is almost no wear on the diamond bite, it is easy to make large-diameter molds, and molds with a wide variety of shapes can be created. This greatly increases the shapes and types of optical glass elements that can be molded.

Furthermore, an optical glass element molded with the mold of the present invention having a highly precise molding surface becomes an inexpensive optical glass element with improved optical performance than conventional glass elements. In addition, since materials with excellent heat resistance and impact resistance are used for the base material and the protective film, the mold life is long and can be used for continuous molding.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the manufacturing process of a mold for molding an optical glass element according to an embodiment of the present invention, and FIG. 2 is a schematic sectional view showing the manufacturing process of a mold for molding an optical glass element according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a part of the device. 1... Base material, 2... Intermediate layer, 3...
...Protective film, 4... Upper mold, 5...
・Lower mold, 6...Heating heater for upper mold, 7
... Heater for lower mold, 8 ... Pressure mechanism for upper mold, 9 ... Pressure mechanism for lower mold, 10 ... Supply glass, 11... Glass supply jig, 12... Optical glass element outlet, 13... Supply glass preheating furnace, 14.
·····Chamber.

Claims (8)

[Claims] (1) Cemented carbide whose main component is tungsten carbide (Wc), titanium nitride (TiN), titanium carbide (Ti)
C) A cermet whose main component is chromium carbide (Cr_2C_3) or alumina (Al_2O_3) is used as a base material, and after processing the base material into a shape similar to the desired shape, nickel (Ni) metal as an intermediate layer, Nickel (N
i) After forming an alloy containing phosphorus (P) as a main component or an alloy containing nickel (Ni)-boron (B) as a main component, a process of processing it into a desired shape with high precision is performed,
A metal nitride, a metal carbide,
Metal shelf, iridium (Ir)-tungsten (W)
alloy, ruthenium (Ru)-tungsten (W) alloy,
Iridium (Ir)-tantalum (Ta) alloy, Ruthenium (Ru)-tantalum (Ta) alloy, Iridium (Ir)
)-rhenium (Re) alloy or ruthenium (Ru)
- A method for producing a mold for molding an optical glass element, characterized in that the mold is coated with a rhenium (Re) alloy film so as not to destroy the shape of the mold. (2) The nitride of the protective film is titanium nitride (TiN), zirconia nitride (ZrN), hafnium nitride (HfN), tantalum nitride (TaN), chromium nitride (CrN), and niobium nitride (NbN). The method for producing a mold for molding an optical glass element according to claim (1). (3) The protective film is characterized in that the carbides are titanium carbide (TiC), zirconia carbide (ZrC), hafnium carbide (HfC), tantalum carbide (TaC), chromium carbide (CrC), and niobium carbide (NbC). A method for producing a mold for molding an optical glass element according to claim (1). (4) The shelving materials of the protective film are titanium shelving (TiB_2), zirconia shelving (ZrB_2), and hafnium shelving (HfB).
_2), tantalum shelved (TaB_2), chromium shelved (C
2. The method for producing a mold for molding an optical glass element according to claim 1, wherein the molding material is niobium shelved (NbB_2). (5) Cemented carbide whose main component is tungsten carbide (Wc), titanium nitride (TiN), titanium carbide (Ti
C), chromium carbide (Cr_C_3), or alumina (
A cermet whose main component is Al_2O_3) is used as a base material, and after processing the base material into a shape similar to the desired shape, nickel (Ni) metal and nickel (Ni) are used as an intermediate layer.
) - After forming an alloy containing phosphorus (P) as a main component or an alloy containing nickel (Ni) - boron (B) as a main component, after going through a process of processing it into a desired shape with high precision, the intermediate As a protective film on the layer, a metal nitride, a metal carbide, a metal shelf, an iridium (Ir)-tungsten (W) alloy, a ruthenium (Ru)-tungsten (W) alloy, an iridium (Ir)-tantalum (Ta) alloy, Ruthenium (Ru)-tantalum (Ta) alloy, iridium (Ir)
-Rhenium (Re) alloy or Ruthenium (Ru)-
A method for producing an optical glass element, comprising press-molding using a mold made by coating a rhenium (Re) alloy film so as not to destroy the shape of the mold. (6) A mold in which the nitride of the protective film is titanium nitride (TiN), zirconia nitride (ZrN), hafnium nitride (HfN), tantalum nitride (TaN), chromium nitride (CrN), and niobium nitride (NbN). 6. The method of manufacturing an optical glass element according to claim 5, wherein the optical glass element is press-molded. (7) Using a mold in which the carbides of the protective film are titanium carbide (TiC), zirconia carbide (ZrC), hafnium carbide (HfC), tantalum carbide (TaC), chromium carbide (CrC), and niobium carbide (NbC). 6. The method of manufacturing an optical glass element according to claim 5, wherein the optical glass element is press-molded. (8) The shelving materials of the protective film are titanium shelving (TiB_2), zirconia shelving (ZrB_2), and hafnium shelving (HfB).
_2), tantalum shelved (TaB_2), chromium shelved (C
Claim (5) characterized in that press molding is carried out using a mold made of shelved niobium (NbB_2) and shelved niobium (NbB_2).
) The method for manufacturing an optical glass element described in .