JPH1081539A - Production of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an optical element while keeping good die-releasability and preventing the prolonged interruption of the production by pressing a glass with a die coated its surface with a specific coating in the press-forming step at intervals of prescribed shots. SOLUTION: An optical element is produced by pressing a glass with a pair of dies under an atmosphere suitable for forming in a forming chamber shielded from the outer atmosphere. The surface of the die in the forming chamber is coated with a hydrocarbon film at intervals of prescribed shots. Preferably, a hydrocarbon gas is introduced into the forming chamber in the press-forming step at intervals of prescribed shots to substitute the atmosphere with the hydrocarbon gas, the die surface is coated with the hydrocarbon film by applying a high-frequency voltage or DC voltage or using an ion gun, the atmosphere is again returned to the original state suitable for forming and the glass is pressed with the coated die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an optical element by press-molding glass using a pair of molds in a molding chamber in a required atmosphere.

[0002]

2. Description of the Related Art The technology of manufacturing a lens by press-molding a glass material without the need for a polishing step has already been developed.
Various methods have been proposed, which omit the complicated steps required in the conventional manufacturing of lenses, and provide the advantage of easily and inexpensively manufacturing lenses.
In the manufacture of not only lenses but also prisms and other optical elements made of glass, the above-mentioned methods have come to be used frequently.

[0003] Properties required for a mold used in press molding of such a glass optical element include excellent hardness, heat resistance, mold releasability, mirror workability, and the like. Therefore, conventionally, as this type of mold material,
Numerous things have been proposed, such as metals, ceramics, and materials coated with them.

[0004] To give some examples, see JP-A-49-49
13Cr martensitic steels invention of Shosai in JP 51112 is, the SiC and Si ₃ N ₄ in the invention Shosai in JP-A-52-45613, JP 60-24623
In the invention described in Japanese Patent Application Publication No. 0-086, a material obtained by coating a hard metal with a noble metal is disclosed in JP-A-61-183134, JP-A-61-281030, and JP-A-1-30.
A material coated with a diamond thin film or a diamond-like carbon film is proposed in the invention described in Japanese Patent No. 1864 and the like, and a material coated with a hard carbon film is proposed in the invention described in JP-A-64-83529. ing.

[0005]

However, however, 13Cr
Tensite steel is easily oxidized, and at high temperatures, Fe
It has the disadvantage that it diffuses into the glass and the glass is colored.
One. In addition, SiC, Si _ThreeN_FourIs generally oxidized
At high temperatures, oxidation still occurs,
SiO on the surface_TwoFusing with glass
Rub On the other hand, materials coated with precious metals have
It is hard to cause, but it is very soft, so it is easily scratched,
In addition, it has a disadvantage that it is easily deformed.

Further, when a mold in which a hydrocarbon film containing CH ₃ and CH ₂ or a carbon film on which graphite is deposited is formed on a cemented carbide or ceramic mold base material is used for glass molding, Since the film is consumed by about a shot, it is necessary to form the film frequently.In each case, the mold is taken out of the molding chamber, the film is formed, and then the film is returned to the molding chamber. Interruptions are required, hindering continuous molding operations.
On the other hand, in the case of a hard carbon film, it has excellent mold release properties, does not cause fusion with glass, and has high hardness and wear resistance. In some cases, it is difficult to release the carbon film. That is, depending on the type of glass, even with a hard carbon film, the adhesion between the mold and the glass is high, which may result in poor mold release or cracking of the lens.

In order to remove the mold from the molding chamber and coat the surface of the mold with a hydrocarbon film in the process of press molding, the mold is cooled to a temperature at which the mold is not oxidized, and the molding chamber is exposed to the atmosphere. Remove the fixing means such as bolts that fix the mold, disassemble the mold unit, take out the mold to be coated, then set the mold in the coating device, and evacuate the inside of the coating device. Further, a number of procedures such as coating the hydrocarbon film thereon and then returning the mold back into the molding chamber are required. This results in a significant loss of time.

The present invention has been made on the basis of the above circumstances, and focuses on the fact that the molding chamber is configured to be shielded from the atmosphere.
Maintaining good release properties, and devised so that the production of hydrocarbon film does not interrupt production for a long time.
An object of the present invention is to provide a method and an apparatus for manufacturing an optical element.

[0009]

In order to achieve the above object, according to the present invention, a glass is pressed using a pair of molding dies in a molding chamber shielded from the atmosphere under an atmosphere suitable for molding. By molding, in the method of manufacturing an optical element, in the process of press molding, for each required shot,
The surface of the mold in the molding chamber is coated with a hydrocarbon film.

Further, according to the present invention, an optical element for manufacturing an optical element is formed by press-molding glass using a pair of molding dies in an atmosphere suitable for molding in a molding chamber shielded from the atmosphere. In the device manufacturing apparatus, the molding chamber is equipped with a hydrocarbon gas introduction port, a high-frequency application antenna or a DC discharge electrode or an ion gun, in addition to the atmosphere replacement introduction port and the atmosphere replacement port. In this process, a hydrocarbon film is coated on the surface of the mold for each required shot by using these.

Therefore, with the mold installed in the molding chamber,
Since a hydrocarbon film having excellent releasability is coated, it is possible to reduce a large time loss that occurs when a mold is inserted into and removed from a molding chamber for forming a film, and interruption of production during that time. Although the loss time due to the periodic coating is inevitable, the workability of continuous molding can be sufficiently maintained as compared with the conventional method.

As an embodiment of the present invention, the coating of the hydrocarbon film is performed every 1 to 100 shots. This is necessary depending on the degree of adhesion between the mold and the glass. Frequently, only a hydrocarbon film is applied to the surface of the mold in the molding chamber, so that the molding die is not removed from the molding chamber as in the related art. Therefore, continuous molding can be performed without substantially interrupting mass production.

The frequency of coating here is determined by the required tact and the relationship between the adhesion between the glass and the mold. In other words, how much time (permissible) required for one coating can be shortened in the time required for taking out the molded article from the mold and charging the next molding material into the mold, During this time, the continuous workability is determined by how many shots the release effect of the hydrocarbon film to be coated can be kept effective.

In the case of a combination having a strong adhesion between the mold and the glass, the number of shots becomes one shot. In some cases, it is necessary to increase the coating time. It is enough.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are applied to press molding of an optical lens. FIG. 1A is a longitudinal sectional view showing a first embodiment of a press forming apparatus according to the present invention,
FIG. 1B is a sectional view taken along line BB of FIG. (A) corresponds to the AA cross section of (b).

In these figures, reference numeral 2 denotes a lower mold member, whose mold surface (upper surface) is finished to a required surface accuracy in order to transfer and form the first optical function surface of the lens. This surface may have an aspherical shape depending on the order of the molded product. Reference numeral 4 denotes an upper mold member, whose mold surface (lower surface) is finished to a required surface accuracy in order to transfer and form the second optical function surface of the lens. This surface may also be aspheric. These two mold members 2, 4 constitute a pair of molding dies.

Reference numeral 6 denotes a sleeve-shaped guide member, by which the lower mold member 2 and the upper mold member 4 are supported so as to be movable in the vertical direction. In the groove of the guide member 6, an opening 7 for introducing a glass material for molding and taking out a molded product is formed. A support plate 8 is fixed below the guide member 6. The lower plate member 2 is restricted from moving downward by the support plate 8. Although not shown, the support plate 8 is attached to a molding machine in a molding chamber that is shielded from the atmosphere.

Reference numeral 10 denotes a holder for holding the upper die member 4, which can be engaged with the upper flange portion of the upper die member 4. Reference numeral 12 denotes a rod for pressing the upper die member 4 downward, and the pressing rod 12 is provided in the above-described molding machine. Reference numeral 40 denotes a hydrocarbon gas inlet provided in the molding chamber separately from an entrance (not shown) provided for replacing the atmosphere in the molding chamber described above, and reference numeral 41 denotes a hydrocarbon gas inlet provided in the molding chamber. This is the obtained high-frequency application antenna. The symbol G is a glass material for molding.

Next, a method of manufacturing the optical element according to the above-described embodiment will be sequentially described in time series. FIG. 2 is a cross-sectional view showing a state in which the forming glass material G is introduced into a forming die before pressing in the present embodiment. Here, the interior of the molding chamber is replaced with an atmosphere suitable for molding, such as nitrogen gas, and in this state, the pressing rod 12 and the holder 10 are pulled up, so that the upper die member 4 is held by the holder 10. Hold and move upward. Then, in a state where the glass material G for molding is vacuum-adsorbed by the suction portion 32 provided at the tip of the transfer arm 30, the arm 3
0 in the horizontal direction so that the suction portion 32 is
The glass material G for molding is placed on the mold surface (upper surface) of the lower mold member 2 by inserting the glass material G into the molding die through the opening 7 and slightly moving it downward to release the suction. Then, the arm 30 is moved in the horizontal direction, and the suction portion 32 is retracted outside the molding die.

FIG. 1A shows a pressed state, in which the pressing rod 12 and the holder 10 are moved downward, and the upper die member 4 is pressed downward by the pressing rod 12. At this time, the holding of the upper mold member 4 by the holder 10 has been released, and the lower mold member 2 is held at that position by being restricted from moving downward by the support plate 8. Thus, the lower mold member 2 and the upper mold member 4
Is press-formed.

The removal of the molded product is performed in a similar manner to the case of introducing the glass material for molding. That is, by lifting the pressing rod 12 and the holder 10 upward, the upper die member 4 is held by the holder 10 and moved upward. Then, the transfer arm 30 is moved in the horizontal direction, the suction part 32 is inserted into the molding die from the opening 7 of the guide member 6, and is further moved slightly downward to suction the molded product. Then, the arm 30 is moved slightly upward, and then moved in the horizontal direction so that the suction portion 32 is retracted out of the mold.

In the above process, one-shot cycle press molding is performed. As the glass material at this time, for example, SK12 (glass transition point: 550)
° C, yield point: 588 ° C, specific gravity: 3.19),
In addition, a so-called precision molding is performed by using a cemented carbide alloy as a mold member and finishing the mold surface with a desired surface accuracy and coating titanium nitride with 1 μm.

For precision molding, first, a set of molding dies (without glass) yet set as shown in FIG. 1 is set in a molding chamber (not shown) by fixing means such as bolts. Next, the pressing rod 12 and the holder 10 are pulled up by an air cylinder (not shown), and the upper mold member 4 is moved upward. Thereafter, the inside of the molding chamber is evacuated by a vacuum pump (not shown), and for example, 1
The pressure is reduced until the pressure becomes ^10-3 Pa or less. An exhaust port (not shown) for this is provided in the molding chamber.

Thereafter, methane gas, for example, 1 × 10 ^-1 P is supplied as a hydrocarbon gas from the hydrocarbon gas inlet 40.
Introduce until a. Then, a high-frequency power of 500 W is applied to the high-frequency applying antenna 41 installed in the molding chamber to perform a high-frequency discharge to form, for example, a hydrocarbon film of about 20 nm on the surface of each mold.

Next, the molding chamber is filled with nitrogen gas through a nitrogen gas inlet (not shown) provided in the molding chamber.
The internal pressure is set slightly higher than the atmospheric pressure. And
Electricity is supplied to a heater (not shown) provided in the molding machine, and the mold members 2 and 4 are heated to 620 ° C. Thereafter, the forming glass material G is sucked and held by the suction unit 32 provided at the tip of the transfer arm 30, and the operation of the transfer arm 30 causes
This is guided onto the lower mold member 2 and put into the mold surface.

Next, by the operation of the air cylinder,
The upper mold member 4 is pressurized via the pressing rod 12, and press forming is continued until the upper edge of the upper mold member 4 hits the guide member 6. Thereafter, the temperature is cooled to a desired temperature, and the transfer arm 30 is operated to take out the molded product.

Such a series of molding processes in a nitrogen gas atmosphere are continuously performed a required number of times.
No formation of a hydrocarbon film is performed. Then, when the preset number of times is completed, a routine for forming a hydrocarbon film is interposed at the break of the above-described molding process, but this is performed in the molding chamber while the molding die is installed in the molding machine. Is achieved. At this time, 1 × 10
^The pressure is reduced again until the pressure becomes ^-3 Pa or less. Then, a hydrocarbon film is formed in the same manner as described above. [Example 1] Under the above conditions, a hydrocarbon film was formed on the surface of a mold, and using this, a press molding was performed continuously.
After 100 times, there was no problem in the releasability, and no cracking or fusion occurred. Then, a hydrocarbon film was formed on the mold surface of the mold every 100 press moldings. Such a series of operation cycles was repeated 50 times,
Total: As a result of press forming of 5,000 shots, there was no problem in arrowheading and releasability, and no cracking or fusion occurred.

As a comparative example, cracking occurred in the molded product from the first shot as a result of performing press molding without coating the hydrocarbon film under the same other conditions. In addition, as a result of performing the coating of the hydrocarbon film only in the first stage of the press molding, and then continuously performing the press molding, in this experiment, minute cracks began to be generated from a time exceeding 100 shots. As a result of the continued molding, cracking continued up to 110 shots, and fusion occurred at the 111th shot. Thus, the effectiveness of the process of the present invention has been confirmed. Example 2 This example was performed under the same conditions as in Example 1. In Example 2, S-NPH1 (trade name) manufactured by OHARA CORPORATION (nd = 1.80800, V
d = 22.7, glass transition point: 563 ° C., yield point: 58
9 ° C., specific gravity: 3.29, composition: see Table 1).
The mold surface of the mold member was prepared by finishing a cemented carbide with a desired surface accuracy, coating TiN to a thickness of 1 μm, and then coating the surface with a hydrogenated aluminum foil carbon film.

The high-frequency applying antenna 41 used in the molding chamber is not of the fixed configuration shown in the above-described embodiment, but is formed by the upper die member 4 and the lower die member through the hole 7 into which the transfer arm 30 enters. 2 so that it can be inserted freely (see FIG. 3).

[0030]

[Table 1] In the precision molding, as in the case of the above-described embodiment, after a set of molding dies is set in the molding chamber, the pressure in the molding chamber is reduced, and when the pressure becomes 1 × 10 ⁻³ Pa, the hydrocarbon gas inlet is formed. 40, methane gas was 1 × 1 as hydrocarbon gas.
It was introduced until it became 0 ^-1 Pa. Next, the upper mold member 4 was lifted by a cylinder, and a high-frequency application antenna 41 was inserted between the upper mold member 4 and the lower mold member 2 as shown in FIG. Then, 500 is applied to the high-frequency application antenna 41.
A high frequency of W was applied and high frequency discharge was performed to form a hydrocarbon film of about 20 nm on the mold surface. In the second embodiment,
Since the high-frequency application antenna and the mold surface of the molding die are closer to each other than in the above-described embodiment, it was possible to form a film in a shorter time (several seconds).

Next, the high-frequency application antenna 41 was retracted from the position of the molding die, and the heaters were energized while the molding chamber was kept in a methane gas atmosphere to heat the mold members 2 and 4 to 630 ° C. Then, in the same manner as in Example 1, the glass material for molding was put into a mold and press-molded. After molding, 50
When the mold was cooled to 0 ° C., the cylinder was operated to raise the upper mold member 4, the transfer arm 30 was inserted between the upper and lower molds, and the molded product was taken out.

Next, the high frequency application antenna was again inserted between the upper and lower molds, a high frequency of 500 W was applied, high frequency discharge was performed, and a hydrocarbon film of about 20 nm was formed on the mold surface.
Then, the high-frequency application antenna 41 was retracted, the next forming glass material was placed on the lower mold member 2 by operating the transfer arm 30, and the forming mold was heated again to 630 ° C. to perform press forming.

The above working process was performed 5,000 times continuously. As a result, there was no mold release failure, no cracking or fusion, and good moldability was obtained. Third Embodiment In the first and second embodiments, an antenna for applying a high frequency was used to form a hydrocarbon film. In the third embodiment, an ion gun was used. FIG. 4 is a schematic view of an apparatus used for executing the third embodiment.
Reference numeral 1 denotes a set of molding dies, which is the same as in the above-described embodiment. Reference numeral 51a denotes a mold holder serving as a substrate holder, to which a bias voltage is applied. Reference numeral 52 denotes a hydrocarbon gas inlet, 53 denotes an ionization chamber, 54 denotes an ion beam device, 55 denotes an ion beam extraction grid, and 56 denotes an ion beam.

The method for forming a hydrocarbon film in the third embodiment will be described below. First, CH ₄ : 20 sccm is introduced into the ionization chamber 53, and the gas pressure is set to 4.0 × 10 ⁻² Pa.
After ionizing the methane gas, apply a voltage of 200 V to the ion beam extraction grid, extract the ion beam, apply a bias voltage of −100 V to the mold holder, and apply a hydrocarbon film of about 20 nm thickness to the mold surface. Then, a film was formed.

A molding test similar to that of Example 1 was performed using the above apparatus, but the same result was obtained. In Examples 1 to 3 described above, methane was used as the hydrocarbon gas. However, the same result was obtained when ethane, propane, ethylene, propylene, acetylene, or the like was used. Example 4 Example 4 was performed with the same mold configuration as that used in Example 1 (see FIG. 5). However, unlike the case of the first embodiment, the guide member 6 has two openings 7, and both sides of the opening 7 of the mold set installed in the molding machine (not shown) A DC discharge electrode 42 is provided.

With the above configuration, precision molding was performed using the same glass material, mold member material, and mold surface shape as in Example 1. For precision molding, a set of molding dies (without glass yet) set as shown in FIG. 5 is set on a molding machine with fixing means such as bolts, and then the pressing rod 12 and the By lifting the holder 10 upward, the upper die member 4 was moved upward. Then, the inside of the molding chamber was evacuated by a vacuum pump, and the pressure was reduced to 1 × 10 ⁻³ Pa or less. Thereafter, methane gas was supplied as a hydrocarbon gas from the hydrocarbon gas inlet 40 at a pressure of 1 Pa.
Until it was introduced. Then, 1 is applied to the DC discharge electrode 42.
A voltage of kV was applied to cause discharge, and a hydrocarbon film having a thickness of about 30 nm was formed on the mold surface.

Next, the molding chamber was filled with nitrogen gas from a nitrogen gas inlet provided separately, and was slightly higher than the atmospheric pressure. The heater was energized, and the mold members 2 and 4 were heated to 620 ° C.
Then, the molding glass material G was put on the mold surface of the lower mold member 2 by operating the transfer arm 30. Then, the upper mold member 4 is pressurized by the air cylinder via the pressing rod 12 so that the upper edge of the upper mold member 4
Press forming was continued until it hit. Thereafter, the temperature was cooled to a desired temperature, and the molded product was taken out by operating the transfer arm 30.

The above press molding was performed 50 times continuously, and there was no problem in the releasability, and no cracking or fusion occurred. Next, the pressure in the molding chamber was reduced again to 1 × 10 ⁻³ Pa or less, and a hydrocarbon film was formed again on the mold surface in the same manner as described above.

In such a continuous press forming process, a series of operations for interposing a hydrocarbon film forming routine is described as 1
The press molding was repeated 00 times, and a total of 5000 shots were performed. As a result, there was no problem in the releasability.
No cracks or fusion occurred.

As a comparison with this example, as a result of performing press molding under the same conditions except that the hydrocarbon film was not coated, cracks occurred from the first shot. This confirmed the superiority of the present invention.

[0041]

As described above, according to the present invention,
In order to form a film on the mold surface to improve release properties, the film is formed while the mold is installed in the molding chamber, so the loss time required so far for forming the release film , And an excellent effect of increasing productivity and consequently enabling significant cost reduction can be obtained.

Further, according to the present invention, a relatively simple structure in which a hydrocarbon inlet, a high-frequency application antenna, a DC discharge electrode, or an ion gun is provided in a molding chamber,
Since the release film can be formed in the molding chamber, it has the effect of minimizing the increase in equipment cost, and the release film can be formed in a short time after removing the molded product from the mold. Yes, furthermore, depending on the degree of adhesion between the mold and the glass, the number of shots of the press molding can be applied as often as necessary, so that the hydrocarbon film can be applied. This has the effect of enabling continuous molding.

[Brief description of the drawings]

FIG. 1 is a view showing a main part of a molding machine according to a first embodiment of the present invention.

FIG. 2 is a view showing a state in which glass is put into a molding die according to the first embodiment of the present invention.

FIG. 3 is a view showing a main part of a molding machine according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a molding system according to a third embodiment of the present invention.

FIG. 5 is a view showing a main part of a molding machine according to a fourth embodiment of the present invention.

[Explanation of symbols]

 2 Lower mold member 4 Upper mold member 6 Guide member 7 Opening 8 Support plate 10 Holder 12 Press rod 30 Transfer arm 32 Suction unit G Molding glass material 50 Molding chamber 51 Mold set 51a Mold holder 52 Hydrocarbon gas inlet 53 Ionization chamber 54 ion beam device 55 ion beam extraction grit 56 ion beam

Claims (4)

[Claims] 1. A method for manufacturing an optical element by press-molding glass using a pair of molds in an atmosphere suitable for molding in a molding chamber shielded from the atmosphere. A method of coating the surface of the mold in the molding chamber with a hydrocarbon film for each required shot. 2. In the process of press molding, a hydrocarbon gas is introduced into the molding chamber for each required shot, the atmosphere is replaced, and a high-frequency voltage or a DC voltage is applied, or an ion gun is used. 2. The method according to claim 1, wherein the surface of the mold is coated with a hydrocarbon film, and then the atmosphere is changed to an atmosphere suitable for molding, and the glass is press-molded. Method. 3. The method according to claim 1, wherein the coating is performed every 1 to 100 shots. 4. An optical element manufacturing apparatus for manufacturing an optical element by press-molding glass using a pair of molds in an atmosphere suitable for molding in a molding chamber shielded from the atmosphere. In addition to the inlet and outlet for atmosphere replacement, the molding chamber is equipped with a hydrocarbon gas inlet, and an antenna for high-frequency application or a DC discharge electrode or an ion gun. Using these, for each required shot, on the mold surface of the mold,
An optical element manufacturing apparatus characterized by coating a hydrocarbon film.