JPH0747493B2 - Optical glass element molding die, method for producing the same, and method for producing optical glass element - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass element molding die for forming a high precision optical glass element such as a lens or a prism used in optical equipment by an ultraprecision glass molding method, and The present invention relates to a manufacturing method thereof and an optical glass element manufacturing method.

2. Description of the Related Art In recent years, as a method of manufacturing a high-precision optical lens, in particular, an aspherical glass lens, many attempts have been made to form it by one-shot molding without using an optical polishing method and without a polishing step.

As one of the forming methods, there is a method in which the glass material is heated to a deformable temperature, for example, a temperature near the softening point temperature, and is formed using a means such as press forming.

The optical glass element molding dies used for these moldings are naturally required to have extremely high-precision surface shape and quality.

This mold is chemically inert to glass under high temperature, the glass press surface of the mold is sufficiently hard to be easily damaged by friction, etc. It is necessary that plastic deformation does not occur, that the workability of the mold is good, and that precision processing is possible.

In order to meet these requirements, for example, silicon carbide, a press molding die using silicon nitride (for example, JP-A-52-45613), tungsten carbide, cermet, zirconia as a base material, There has been proposed a press molding die or the like formed by forming a noble metal alloy film on.

In this case, in order to finish the silicon carbide, silicon nitride, tungsten carbide, zirconia, cermet and noble metal alloy film into a desired surface shape, a grinding process using a diamond grindstone is used.

However, in the forming die having the above-mentioned structure, the hardness of the material is extremely high, and the diamond grindstone is heavily worn, making it difficult to perform highly accurate processing, and it takes a very long time to satisfy the required accuracy.

For example, in the case of machining a large-diameter mold, satisfactory accuracy cannot be obtained unless machining is performed while confirming the wear amount of the grindstone.

Furthermore, the number of surfaces that can be used to process a mold with one grindstone is small. Further, in the case of a small diameter, if the radius of curvature is extremely small, there is no grindstone that can be processed.

Due to such processing restrictions, the range of mold shapes that can be created is narrow and the processing time and the like are long, making the molding die very expensive.

On the other hand, if a material in which only the workability is taken into consideration is used, the processing time is shortened, and a mold having a good shape accuracy can be obtained, but there is a problem that the mold life is short.

Therefore, the inventors of the present application have made the following proposal in Japanese Patent Application Laid-Open No. 1-184070 for the purpose of solving these problems.

That is, as the base material of the molding die, a cemented carbide containing tungsten carbide as a main component or a cermet containing titanium carbide, titanium nitride, chromium carbide or alumina as a main component is used, and these base materials have a desired shape by grinding. After being processed into a state close to that of the above, it has excellent workability in grinding and cutting on the base material, and has a high melting point and is chemically stable nickel metal, nickel-
An alloy containing phosphorus as a main component or an alloy containing nickel-boron as a main component is formed as an intermediate layer, and the intermediate layer is precisely processed by a cutting process or a grinding process into a desired shape. As a protective film, for forming an optical glass element by forming a metal nitride, metal shelf compound, metal carbide, iridium-tungsten alloy, ruthenium-tungsten alloy, iridium-tantalum alloy, iridium-rhenium alloy, or ruthenium-rhenium alloy film Creating a type.

FIG. 3 shows an example of the molding die thus prepared.

Problems to be Solved by the Invention According to the method described in Japanese Patent Application No. 1-184070 (Japanese Patent Application Laid-Open No. 3-50127), the machining time of the mold is shortened, and a mold with good shape accuracy can be obtained. It is possible to sufficiently solve the problems of mold processing time and mold manufacturing cost.

However, the nickel metal used as the intermediate layer 2, the alloy containing nickel-phosphorus as a main component, or the alloy containing nickel-boron as a main component causes peeling or cracks on the outer peripheral portion of the mold before or during use. There was a case to wake up.

That is, when molding is continued using the molding die shown in FIG. 3, cracks or peeling may occur at the corners of the outer periphery of the molding die regardless of the combination of the intermediate layer and the protective film. That is, peeling or cracking of the intermediate layer may occur from the outermost periphery of the molding die to the start of the concave surface. It is considered that this is because stress concentration is likely to occur in the intermediate layer at the corners of the mold.

The present invention further develops the invention described in JP-A-1-184070, which is a prior art made by the inventors of the present application, to solve the above problems, and further excellent optical glass element molding die and its manufacturing method. Another object is to provide a method for manufacturing an optical glass element.

Means for Solving the Problems In order to solve the above problems, the present invention uses, as a base material of a molding die, a cemented carbide containing tungsten carbide (WC) as a main component, or titanium nitride (TiN) or titanium carbide ( TiC),
A step of processing a base material of a cermet mainly composed of chromium carbide (Cr ₂ C ₃ ) or alumina (Al ₂ O ₃ ) into a shape close to a desired shape, nickel (Ni) as an intermediate layer ) Metal, a step of forming an alloy containing nickel (Ni) -phosphorus (P) as a main component, a step of processing the intermediate layer into a desired shape with high precision, and a step of removing the intermediate layer on the outer peripheral portion of the base material. And a metal nitride, a metal carbide, a metal shelf compound, an iridium (Ir) -tungsten (W) alloy, a ruthenium (Ru) -as a protective film on the base material and the intermediate layer.
Tungsten (W) alloy, iridium (Ir) -tantalum (Ta) alloy, ruthenium (Ru) -tantalum (Ta) alloy,
Using a means for forming a mold for forming an optical glass element by a step of coating an iridium (Ir) -rhenium (Re) alloy or ruthenium (Ru) -rhenium (Re) alloy film so as not to destroy the shape of the mold It is a thing.

Action In the present invention, since the outer peripheral portion of the molding die is removed by the above-mentioned means, stress concentration in the intermediate layer and peeling or cracking due to repeated expansion and contraction due to molding temperature cycle are eliminated during use. As a result, it has become possible to easily obtain a highly accurate surface shape of the intermediate layer which is excellent in grinding and cutting workability.

In addition, since it is not necessary to process extremely hard materials, there is almost no wear of the diamond bite and grindstone, the life of the diamond bite and grindstone is long, and many large-diameter molding dies can be created with one bite and grindstone. . In addition, since it is possible to perform cutting with a diamond bite, it is possible to process a mold with a small radius of curvature and expand the processing range. Furthermore, since the base material and protective film are made of materials with excellent surface quality, heat resistance, and impact resistance, it is easy to create a mold that has good processability and mold life, and press the mold. Molding makes it possible to obtain an inexpensive optical glass element having a highly precise surface shape.

Example Hereinafter, a method for producing 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 the accompanying drawings.

First, an experiment was conducted on the workability of the material used as the intermediate layer. In the experiment, we decided to finish various materials into a concave shape with a diameter of 8 mm and a radius of curvature of 7.5 mm.

Since materials of the above-mentioned size cannot be obtained depending on the material, it was decided to use a cemented carbide as the base material to form a material close to the desired shape, then form the material on the base material and perform processing.

As the processing method, cutting processing using a diamond bite and grinding processing using a diamond grindstone were performed on various materials, and the evaluation method was to measure the surface shape using an interferometer and confirm the processing accuracy by the processing accuracy.

The experimental results are shown in Table 1.

From Table 1, nickel, nickel-phosphorus alloy, and nickel-boron alloy which can be cut and have good working accuracy were obtained. Since the hardness of other materials was extremely high, the diamond bite was worn out instantaneously and could not be cut.

Further, the grinding process also causes wear, which requires a very long time. The surface shape after processing is also not sufficient.

Next, using a cemented carbide as the base material, the surface shape of the mold surface with nickel formed on it continuously cut, and the iridium-tungsten alloy formed on the cemented carbide and then continuously ground An experiment was carried out to confirm the transition of the surface shape when processing was performed.

The shape of the created mold was performed after processing the base material into a similar shape in advance so as to have a concave shape with a diameter of 42 mm and a radius of curvature of 18.3 mm.

The results are shown in Table 2.

It can be seen that when the nickel surface is processed, a highly accurate surface shape can be obtained, and the diamond grindstone is not worn, so that many molding surfaces can be formed.

On the other hand, in the processing of the iridium-tungsten alloy film, the precision of the first mold is satisfied, but the precision deteriorates as the number of processes increases, and the fifth mold cannot be processed.

As can be seen from Tables 1 and 2, by using nickel, nickel-phosphorus alloy, and nickel-boron alloy as the intermediate layer, the workability is good, and the diamond tool does not wear and has a long life. It could be confirmed. Also, the processing time can be significantly shortened compared to other materials.

As described above, with the above material, even a large-diameter die can be processed with high precision using a single diamond tool.
Further, in the cutting process, the radius of the cutting tip of the diamond bite can be made smaller than that of the grinding process, and a die having a surface having a small radius of curvature can be processed, so that the processing range is greatly expanded.

Although not described here, nickel, nickel-phosphorus alloy, an alloy containing nickel-phosphorus as a main component, which is chemically stable with high workability and high melting point similar to nickel-boron alloy,
There is no problem even if an alloy containing nickel-boron as a main component is used.

Next, the method for producing the molding die and the method for producing the optical glass element of the present invention will be described.

FIG. 1 is a schematic view of steps of the method for producing a molding die of the present invention. Reference numeral 1 is a base material, 2 is an intermediate layer, and 3 is a protective film.

As shown in Fig. 1 (a), a cemented carbide with a diameter of 30mm and a thickness of 6mm, cermet is used as a base material for a pair of molds consisting of a concave upper mold with a radius of curvature of 14mm and 20mm and a lower mold. Roughly processed by grinding, the amount of deviation from the final shape is 10 μm
I did the following.

Next, as shown in FIG. 1 (b), nickel, an alloy containing nickel-phosphorus as a main component, nickel-
One of the alloys containing boron as the main component was formed as the intermediate layer 2 by the ion plating method to have a thickness of 15 μm.

Thereafter, as shown in FIG. 1 (c), the intermediate layer 2 was cut with a diamond cutting tool to finish the surface shape into a desired shape with high accuracy.

Further, as shown in FIG. 1 (d), the outer peripheral portion of the intermediate layer of the base material was removed by grinding or turning.

Finally, as shown in FIG. 1 (e), a metal nitride, a metal carbide, a metal shelf compound or an iridium (Ir) -tungsten (W) alloy, a ruthenium (Ru) -on the intermediate layer 2.
Tungsten (W) alloy, iridium (Ir) -tantalum (Ta) alloy, ruthenium (Ru) -tantalum (Ta) alloy,
An iridium (Ir) -rhenium (Re) alloy or a ruthenium (Ru) -rhenium (Re) alloy was deposited.

It is possible to easily achieve the shape accuracy (RMS 0.04λ or less) required for the optical glass element in any molding die.

By providing an intermediate layer that is easy to cut as described above, it is not necessary to process an extremely hard material, the processing time is greatly shortened, and a molding die with a highly accurate surface shape can be produced at low cost. it can.

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

Also, since the outer peripheral portion of the intermediate layer of the base material was removed by grinding or turning, the peeling and cracks that often occur because stress concentration is likely to occur in the intermediate layer at the corners of the mold, No longer occurs during the initial period of use and during long-term use.

FIG. 3 shows a state in which the pair of upper and lower molds are set in a press machine.

4 is an upper molding die, 5 is a lower molding die, 6 is an upper molding die heating heater, 7 is a lower molding die heating heater, 8 is an upper molding die pressure mechanism, 9 is a lower molding die pressure mechanism, Reference numeral 10 is a supply glass, 11 is a glass supply jig, 12 is an outlet for a press-molded optical glass element, 13 is a preheating furnace for supply glass, and 14 is a chamber.

In a press experiment, 70% by weight of lead oxide (PbO) and silica (SiO 2
₂ ) 27% by weight of lead oxide and the balance is trace amount of lead oxide optical glass processed into a spherical shape with a radius of 10 mm
After heating at 10, place it on the lower molds of upper and lower molds 4 and 5 held at 550 ° C, and press with the upper mold 4 in a nitrogen gas atmosphere.
Apply 5Kg / mm ² to deform the glass material.

After the deformation, the upper mold 4, the lower mold 5, and the glass material are cooled to 380 ° C. Then, the molded optical glass element is taken out from the take-out port 12 and cooled to room temperature.

After the above-described molding process was repeated 5000 times with a mold of each material, the molds 4 and 5 were taken out from the press machine, and the shape accuracy and surface roughness of the mold surface were measured to evaluate the superiority and inferiority of the mold.

Using a cemented carbide as a base material, nickel as a middle layer, after forming a nickel-phosphorus alloy, a metal nitride, a metal carbide, a metal shelf compound, and other alloys formed on the middle layer The evaluation results after press molding are shown in Table 3.

The mark ◯ in the table indicates that there is no peeling or shape change.

In each of the molding dies having any structure, after the molding was performed 5000 times, the surface was not roughened or the shape was not changed. The adhesion between the base material, the intermediate layer and the protective film was good, and there was no peeling of the film due to molding.

In addition, no reaction with glass is observed in each protective film. Further, the shape of the molded optical glass element also satisfactorily transfers the shape of the mold, and the performance of the optical glass element is sufficiently satisfied.

In the examples, the intermediate layer was nickel, a nickel-phosphorus alloy, and a nickel-boron alloy, but there is no problem if an intermediate layer of an alloy containing nickel-phosphorus as a main component or an alloy containing nickel-boron as a main component is provided. .

As described above, in the case of the molding die of this example having a configuration in which the intermediate layer on the outer peripheral portion of the molding die is previously removed and then the protective film is formed, not only in the initial stage of use but also after more than 5000 times of use. Even without peeling or cracking, the mold for optical glass element molding has a longer life than ever before.

Effects of the Invention As described above, the method for producing the optical glass element molding die of the present invention removes the outer peripheral portion of the molding die, so that peeling and cracking due to repeated stress expansion and contraction due to stress concentration and molding temperature cycle in the intermediate layer are caused. There is nothing to wake up during use. As a result, it has become possible to easily obtain a highly accurate surface shape of the intermediate layer which is excellent in grinding and cutting workability.

In addition, since it is not necessary to process extremely hard materials, there is almost no wear of the diamond bite and grindstone, the life of the diamond bite and grindstone is long, and many large-diameter molding dies can be created with one bite and grindstone. . In addition, since it is possible to perform cutting with a diamond bite, it is possible to process a mold with a small radius of curvature and expand the processing range. Furthermore, since the base material and protective film are made of materials with excellent surface quality, heat resistance, and impact resistance, it is easy to create a mold that has good processability and mold life, and press the mold. Molding makes it possible to obtain an inexpensive optical glass element having a highly precise surface shape.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a process of producing an optical glass element molding die according to an embodiment of the present invention, and FIG. 2 is a molding process using the optical glass element molding die according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a part of the apparatus, and FIG. 3 is a schematic cross-sectional view showing a process for producing a mold for molding an optical glass element in a prior example of the inventor of the present application. 1 ... Base material, 2 ... Intermediate layer, 3 ... Protective film, 4 ... Upper mold, 5 ... Lower mold, 6 ... Upper mold heating heater,
7 ... Lower mold heating heater, 8 ... Upper mold pressure mechanism, 9 ... Lower mold pressure mechanism, 10 ... Supply glass, 11
...... Optical glass element outlet, 13 …… Supply glass preheating furnace, 14 …… Chamber.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kiyoshi Kuribayashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoshinori Shirato 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshio Inoue 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A cemented carbide containing tungsten carbide (WC) as a main component, or titanium nitride (TiN) and titanium carbide (Ti).
C), chromium carbide (Cr ₂ C ₃ ) or alumina (Al ₂ O ₃ )
Of cermet as a main component, and a step of processing the base material into a shape approximate to a desired shape, nickel (Ni) metal, nickel (Ni) -phosphorus (P) as a main component as an intermediate layer A step of forming an alloy, a step of highly accurately processing the intermediate layer into a desired shape, a step of removing the intermediate layer on an outer peripheral portion of the base material, a metal nitride as a protective film on the base material and the intermediate layer Thing, metal carbide, metal shelf compound, iridium (Ir) -tungsten (W) alloy, ruthenium (Ru) -tungsten (W) alloy, iridium (Ir)-
Tantalum (Ta) alloy, ruthenium (Ru) -tantalum (T
a) An optical glass comprising a step of coating an alloy, an iridium (Ir) -rhenium (Re) alloy or a ruthenium (Ru) -rhenium (Re) alloy film so as not to lose the shape of the mold. A method for manufacturing an element molding die. 2. A cemented carbide containing tungsten carbide (WC) as a main component, or titanium nitride (TiN) and titanium carbide (Ti).
C), chromium carbide (Cr ₂ C ₃ ) or alumina (Al ₂ O ₃ )
As a base material, a cermet containing as a main component, the base material,
A shape similar to the desired transfer surface shape is processed, and nickel (Ni) metal, nickel (Ni)-
An alloy layer containing phosphorus (P) as a main component is formed, and metal nitride, metal carbide, metal shelf compound, iridium (Ir) -tungsten (W) alloy, ruthenium (Ru) is formed on the alloy layer.
-Tungsten (W) alloy, Iridium (Ir) -Tantalum (Ta) alloy, Ruthenium (Ru) -Tantalum (Ta) alloy, Iridium (Ir) -Rhenium (Re) alloy or Ruthenium (Ru) -Rhenium (Re) alloy A mold for forming an optical glass element, characterized in that the above film is formed. 3. A method for producing an optical glass element, which comprises press-molding using the optical glass element molding die according to claim 2.