JPH085680B2 - Method for producing optical glass element molding die and method for producing optical glass element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing 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 ultra-precision glass molding method. And a method for manufacturing an optical glass element.

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 or the like, many attempts have been made and realized 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 of heating a glass material to a temperature at which it can be deformed, for example, a temperature near the softening point, and forming it by means of press molding or the like. The optical glass element molding die used in these moldings is required to have extremely high-precision surface shape and quality. This molding die is chemically inert to glass at high temperatures, the glass press surface of the die is sufficiently hard to be easily damaged by scratches, etc. Must not cause plastic deformation, have excellent heat resistance and thermal shock resistance, and have good mold workability and capable of precision processing. In order to achieve this object, for example, a die for press molding using silicon carbide or silicon nitride (JP-A-52-45613), tungsten carbide, cermet, zirconia as a base material, and a precious metal on the base material. A press molding die or the like formed by forming an alloy film has been proposed, and various studies have been conducted.

However, in order to finish the molding die as described above, for example, silicon carbide, silicon nitride, tungsten carbide, zirconia, cermet and a precious metal alloy film into a desired surface shape, grinding with a diamond grindstone is performed. It will be finished using. However, since the hardness of the material is extremely hard in the molding die having the above-described configuration, the diamond grindstone wears hard and high-precision machining is difficult,
It takes a very long time to meet the required accuracy. For example, in the case of machining a large-diameter mold, the accuracy cannot be satisfied unless the machining is performed while confirming the wear amount. In addition, the number of surfaces that can be processed by a single whetstone is small. Further, in the case of a small diameter, if the radius of curvature is extremely small, there is no machinable diamond grindstone. As described above, the range of mold shapes that can be created due to processing restrictions is narrow, the processing time is long, and the molding dies are very expensive. If a material that only considers workability is used, the processing time is shortened, and a mold with good shape accuracy can be obtained, but there is a problem that the mold life is short. Further, since it is difficult to process a sufficient surface shape, the performance of the optical glass element molded by the above-mentioned molding die was not sufficient.

Means for Solving the Problems In order to solve the above problems, the present invention mainly uses a cemented carbide containing tungsten carbide as a main material, or titanium carbide, titanium nitride, chromium carbide or alumina as a base material of a molding die. Using a cermet as a component, after grinding these base materials into a shape close to a desired shape by grinding, the base material is excellent in grinding and cutting workability, 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, which is precisely processed into a desired shape by cutting or grinding, and then as a protective film on the intermediate layer,
A metal nitride, a metal boride, a metal carbide, an iridium-tungsten alloy, a ruthenium-tungsten alloy, an iridium-tantalum alloy, an iridium-rhenium alloy, or a ruthenium-rhenium alloy film is formed to form an optical glass element molding die. It uses a means.

Action The present invention includes the intermediate layer excellent in grindability and cutting workability by means of the above-described means, so that it is possible to easily obtain a highly accurate surface shape. Also, since it is not necessary to machine extremely hard materials, there is almost no wear on the tire bite and grindstone, the life of the diamond bite and grindstone is long, and a large-diameter molding die can be created with one bite and grindstone. became. 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, the base material and the protective film are
Since a material with excellent surface quality, heat resistance, and impact resistance is used, it is easy to create a mold with good workability and mold life, and press molding with that mold will give a highly accurate surface shape. It has become possible to obtain an inexpensive optical glass element having the same.

EXAMPLES Hereinafter, a method for producing an optical glass element molding die and an optical glass element production method according to an example of the present invention will be described with reference to the drawings and tables.

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 using a diamond bite and grinding 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 workability by the processing accuracy. The experimental results are shown in Table 1.

From the experimental results, nickel, nickel-phosphorus alloys, and nickel-boron alloys that can be cut and have good working accuracy were obtained. Since the other materials had extremely high hardness during cutting, the diamond bite was worn out instantly and could not be processed. 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 when continuously cutting the mold surface on which nickel is formed,
An experiment was conducted to confirm the transition of the surface shape when the iridium-tungsten alloy was formed on the cemented carbide and then continuously ground. The shape of the prepared die was performed after the base material was processed in advance into a similar shape so as to have a concave shape with a diameter of 42 mm and a radius of curvature of 18.3 mm. Table 2 shows the results.

It can be seen that when the nickel surface is processed, the surface shape can be obtained with high accuracy, and the diamond grindstone is not worn, so that many molding surfaces can be formed. On the other hand, iridium-
In the processing of the tungsten alloy film, the accuracy of the first mold is sufficient, but the accuracy deteriorates as the number of processes increases, and it becomes impossible to process the fifth mold.

As can be seen from Tables 1 and 2, it was confirmed by experiments that nickel, nickel-phosphorus alloy, and nickel-boron alloy used as the intermediate layer in the present invention have good workability and the diamond tool does not wear and has a long life. . Also, the processing time can be significantly shortened compared to other materials. With the above materials, even a large-diameter mold can be processed with high precision on a large number of molding die surfaces with one 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, an alloy containing nickel-phosphorus as a main component, nickel-phosphorus as a main component, which has the same or higher workability and high melting point as those of the nickel-phosphorus alloy, and is chemically stable, and nickel-boron as a main component. There is no problem even if the alloy used is used.

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

FIG. 1 is a process schematic view of a 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.

Curvature radius of cemented carbide and cermet with diameter 30 mm and thickness 6 mm
Roughly processed by grinding as a base material of a pair of molds consisting of 14 mm and 20 mm concave upper molds, lower molds,
The amount of deviation from the final shape was 10 μm or less. Fig. 1 (a)
Shown in Next, on each of these base materials, nickel, an alloy containing nickel-phosphorus as a main component, or an alloy containing nickel-boron as a main component was formed as an intermediate layer to a thickness of 15 μm by an ion plating method. It is shown in FIG. 1 (b). After that, a desired shape was accurately finished by cutting with a diamond tool. It is shown in FIG. 1 (c). Finally, a metal nitride, a metal carbide, a metal boride, or an iridium-tungsten alloy, a ruthenium-tungsten alloy, an iridium-tantalum alloy, an iridium-rhenium alloy, or a ruthenium-rhenium alloy was formed on the intermediate layer. It is shown in FIG. The shape accuracy (RMS 0.04λ or less) required for the optical glass element was easily achieved with any of the molds. 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 significantly shortened, and a molding die having a highly accurate surface shape can be produced at 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 plating method.

FIG. 2 shows a state in which the pair of upper and lower molds are 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 is a pressure mechanism for the upper mold, 9 is a pressure mechanism for the lower mold, 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 (Sb
27% by weight of iO ₂ ) and the balance is a trace of lead oxide type optical glass processed into a spherical glass material 7 with a radius of 10 mm, which is heated in a preheating furnace 10 and then held at 550 ° C. in the upper and lower molds. Place it on the lower molds 4 and 5 and place the upper molds 4 in a nitrogen gas atmosphere.
Pressing pressure of 5kg / mm ² is applied to deform the glass material. After the deformation, the upper mold, the lower mold, 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 the molding dies of each material, the molds 4 and 5 were removed from the press machine, and the shape accuracy and surface roughness of the mold surface were measured to evaluate the superiority of the mold.

Using cemented carbide as a base material, nickel as an intermediate layer, after forming a nickel-phosphorus alloy, a metal nitride on the intermediate layer,
Table 3 shows the evaluation results after the press forming of the forming die formed by forming the metal carbide, the metal boride, and other alloys.

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. It can be said that it has a sufficient life as an optical glass element molding die. 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. .

EFFECTS OF THE INVENTION As described above, the method for producing a mold for molding an optical glass element of the present invention does not require processing of the base material and the protective film, which are extremely hard materials, and uses an intermediate layer having good workability, thereby making The working life can be extended, and a mold with a good surface shape can be easily created in a short time. Molding with a small radius of curvature is possible because it can be cut, and diamond dies are hardly worn, making it easy to manufacture large-diameter molds. Molds with a wide variety of shapes Can be created. As a result, the shape and type of the optical glass element to be molded is also significantly increased. The optical glass element molded with the molding die of the present invention having a highly accurate molding surface is an inexpensive optical glass element having improved optical performance as compared with conventional optical glass elements. In addition, since the base material and the protective film are made of materials having excellent heat resistance and impact resistance, the mold life is long, and continuous molding can be sufficiently performed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process of an optical glass element molding die according to an embodiment of the present invention, and FIG. 2 is molding performed by the optical glass element molding die according to an embodiment of the present invention. It is a schematic sectional drawing which shows a part of apparatus. 1 ... Base material, 2 ... Intermediate layer, 3 ... Protective film, 4 ... Upper mold, 5 ... Lower mold, 6 ... 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.

Front page continuation (72) Inventor Takao Aoyama 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshinori Shirato 1006, Kadoma, Kadoma City, Osaka (72) Invention Yoshio Inoue 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (8)

[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 )
Any of the cermets containing any of the above as a base material, and after processing the base material into a shape approximate to the desired shape, nickel (Ni) metal as an intermediate layer, nickel (Ni)
-After forming either an alloy containing phosphorus (P) as a main component or an alloy containing nickel (Ni) -boron (B) as a main component, after performing a step of highly accurately processing into a desired shape, A metal nitride, a metal carbide, a metal boride, an iridium (Ir) -tungsten (W) alloy, a ruthenium (Ru) -tungsten (W) alloy, an iridium (Ir) -tantalum (Ta) as a protective film on the intermediate layer. Alloy film, ruthenium (Ru) -tantalum (Ta) alloy, iridium (Ir) -rhenium (Re) alloy, or ruthenium (Ru) -rhenium (Re) alloy film so as not to destroy the shape of the mold A method for producing a mold for molding an optical glass element, the method comprising: 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 (Nb).
The method for producing an optical glass element molding die according to claim 1, wherein the method is any one of N). 3. Carbide of the protective film is titanium carbide (TiC), zirconia carbide (ZrC), hafnium carbide (HfC), tantalum carbide (TaC), chromium carbide (CrC) and niobium carbide (Nb).
The method for producing an optical glass element molding die according to claim 1, which is any one of C). 4. The boride of the protective film is titanium boride (TiB ₂ ), zirconia boride (ZrB ₂ ), hafnium boride (HfB ₂ ), tantalum boride (TaB ₂ ), chromium boride (CrB ₂ ). and boride niobium claims, characterized in that either (NbB ₂₎ (1)
A method for producing the optical glass element molding die described. 5. 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 )
Any of the cermets containing any of the above as a base material, and after processing the base material into a shape approximate to the desired shape, nickel (Ni) metal as an intermediate layer, nickel (Ni)
-After forming either an alloy containing phosphorus (P) as a main component or an alloy containing nickel (Ni) -boron (B) as a main component, after performing a step of highly accurately processing into a desired shape, A metal nitride, a metal carbide, a metal boride, an iridium (Ir) -tungsten (W) alloy, a ruthenium (Ru) -tungsten (W) alloy, an iridium (Ir) -tantalum (Ta) as a protective film on the intermediate layer. Alloy film, ruthenium (Ru) -tantalum (Ta) alloy, iridium (Ir) -rhenium (Re) alloy, or ruthenium (Ru) -rhenium (Re) alloy film so as not to destroy the shape of the mold A method for manufacturing an optical glass element, which comprises press-molding using the molding die manufactured in this way. 6. 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 (Nb).
The method for producing an optical glass element according to claim (5), wherein press molding is performed using the molding die that is any one of N). 7. The carbide of the protective film is titanium carbide (TiC), zirconia carbide (ZrC), hafnium carbide (HfC), tantalum carbide (TaC), chromium carbide (CrC) and niobium carbide (Nb).
The method for producing an optical glass element according to claim (5), characterized in that press molding is performed using the molding die which is any one of C). 8. The boride of the protective film is titanium boride (TiB ₂ ), zirconia boride (ZrB ₂ ), hafnium boride (HfB ₂ ), tantalum boride (TaB ₂ ), chromium boride (CrB ₂ ). 6. The method for producing an optical glass element according to claim 5, wherein press molding is performed using a molding die that is either niobium boride (NbB ₂ ).