JPH0585751A - Molding device and molding method for optical element - Google Patents

Abstract

(57) [Summary] [Purpose] In molding an optical element having a convex surface, a high quality optical element is molded with high productivity. [Structure] The molding apparatus 1 includes a molding chamber 2, a decompression chamber 3, a heater 4, and a tip end portion of the heater 4 and a transfer arm 5 movable in the molding chamber 2. Upper and lower molds 6 and 7 and a nozzle 9 for ejecting a non-oxidizing gas are provided in the molding chamber 2, and a disk 16 and a valve 10 capable of sealing while accommodating the distal end portion of the transfer arm 5 in the molding chamber 2. 11 is provided. The decompression chamber 3 is connected to a rotary pump 13 that constantly decompresses the decompression chamber 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press molding apparatus for manufacturing an optical element such as a high precision glass lens and a molding method therefor.

[0002]

2. Description of the Related Art Conventionally, the following inventions have been disclosed as inventions for molding an optical element such as a high precision glass lens.

For example, in the invention disclosed in Japanese Patent Laid-Open No. 2-74532, a barrel carrier for transporting an optical material between upper and lower dies, and a plurality of sprays for uniformly cooling the optical material placed on the barrel carrier. A molding apparatus comprising a nozzle and a non-oxidizing gas supply means connected to the spray nozzle. Another method is a molding method in which an optical material that has been softened by heating is conveyed between upper and lower molds by using this molding apparatus and press-molded, and then the molded optical material is uniformly cooled with a non-oxidizing gas. The above invention can cool the optical material uniformly and quickly, and shorten the molding cycle time.

Further, in the invention described in Japanese Patent Publication No. 63-8050, press molding is performed in a vacuum, and oxidation of the mold can be prevented.

[0005]

However, the above-mentioned respective prior arts have the following problems.

That is, in the invention described in the above-mentioned Japanese Patent Application Laid-Open No. 2-74532, when the molding surface is concave with respect to the surface shape of the optical material, it is press-molded by the air between the optical material and the mold. This air remains, and it is difficult to secure transferability by the air left between the optical material and the mold.

Further, in the invention described in Japanese Patent Publication No. 63-8050, press molding is performed in a vacuum,
Although it is possible to remove air between the optical material and the mold, there is a problem that the molding cycle time is rather lengthened because vacuuming must be performed after the press is completed.

Therefore, the present invention was developed in view of the problems in the above-mentioned respective prior arts, and when molding an optical element having a convex surface from a flat plate preform, the molding cycle time can be shortened and it is excellent. It is an object of the present invention to provide an optical element molding apparatus and a molding method capable of ensuring transferability.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a transport arm for transporting an optical material placed on a carrier between at least one of the upper and lower molds whose molding surface is formed as a concave surface, and a peripheral of the upper and lower molds. In a molding device for an optical element, which is provided with a non-oxidizing gas feeding means for cooling the molded optical element, a means for sealing the molding chamber while accommodating the tip of the transfer arm in the molding chamber. , A decompression chamber connected to the molding chamber via a valve.

Further, the heat-softened flat plate-shaped optical material is conveyed between the upper and lower molds in which at least one molding surface is formed into a concave surface, the molding chamber is depressurized and press-molded, and then the molded optical element. Is a method of cooling with a non-oxidizing gas.

[0011]

According to the present invention, the decompression chamber is designed in consideration of the desired degree of vacuum in the molding chamber and the desired volume of the molding chamber in order to maintain the pressure in the molding chamber at a pressure at which air is not trapped between the mold and the optical material. By appropriately setting the volume of, the pressure in the molding chamber can be reduced to the atmospheric pressure or less at the moment when the valve between the decompression chamber and the molding chamber is opened, faster than when the vacuum is directly drawn by the rotary pump. Further, the optical material can be rapidly cooled uniformly by feeding the non-oxidizing gas.

[0012]

[Embodiment 1] FIG. 1 is a schematic configuration diagram of an apparatus used in this embodiment.

A molding apparatus 1 includes a molding chamber 2, a decompression chamber 3 connected to the right side of the molding chamber 2, a heater 4 installed on the left side of the molding chamber 2, and an external unit. The distal end portion is composed of a heater 4 and a transfer arm 5 movably provided in the molding chamber 2.

An upper mold 6 having a concave molding surface is fixedly mounted on the inner upper surface of the molding chamber 2, and a lower mold having a flat molding surface provided below the molding mold 6 so as to be vertically movable on the same axis. 7 are arranged to face each other. The molding surfaces of the upper mold 6 and the lower mold 7 are formed in a shape for obtaining a desired optical element.
The V value is processed with an accuracy of 0.1 μm to 0.2 μm.

Further, an optical material 8 is provided on the upper surface inside the molding chamber 2.
A plurality of nozzles 9 for ejecting N ₂ gas (cooling gas) for rapidly cooling the are vertically provided around the upper mold 6, and the nozzles 9 are connected to an N ₂ gas supply device (not shown). There is.

Valves 10 and 11 are provided on the right side and the bottom of the molding chamber 2, respectively, and a hole 12 is formed on the left side of the molding chamber 2 so that the transfer arm 5 can be inserted and the inside of the molding chamber 2 can be kept airtight. Is formed, and the inside of the molding chamber 2 is closed by closing the hole 12.

The decompression chamber 3 is connected to the molding chamber 2 via the valve 10. A rotary pump 13 for constantly decompressing the decompression chamber 3 is connected to the right side of the decompression chamber.

A holding portion 15 for holding the carrier 14 on which the optical material 8 is placed is formed at the tip of the transfer arm 5, and the transfer arm 5 has a disc 16 for closing the hole 12.
Is fitted so as to be movable in the front-rear direction of the transfer arm 5. By adjusting the fixing position of the disk 16 with the positioning pin 18 fixed to the transfer arm 5 with the screw 17, the molding chamber 2 can be sealed and the transfer position of the carrier 14 can be adjusted during molding. It is configured.

In the molding using the molding apparatus 1 having the above-described structure, the optical material 8 is first SK ground on both planes.
Place 11 on carrier 14. After holding the carrier 14 by the holding portion 15 of the transfer arm 5, the transfer arm 5
Is moved forward and heated by the heater 4 to 680 ° C. which is a temperature at which the optical material 8 is softened.

Next, the carrier arm 5 is further advanced to carry the carrier 14 on which the optical material 8 is placed between the upper mold 6 and the lower mold 7. At this time, the temperatures of the upper and lower molds 6 and 7 are respectively heated to 510 ° C., and the disc 16 fitted to the transfer arm 5 and the valve 1 previously closed.
The forming chamber is closed by 0 and 11.

Next, the valve 10 of the decompression chamber 3 which is constantly decompressed by the rotary pump 13 is opened to prevent air from forming in the molding chamber 2 between the upper die 6 and the optical material 8.
Reduce the pressure so that the upper and lower molds 6 and 7 can be prevented from being oxidized. At the same time, the lower die 7 is raised to start pressing.

During the pressing, the valve 10 is closed and the valve 11 is closed.
Is opened and N ₂ gas is ejected from the tip of the nozzle 9 to cool the optical element. After cooling, the lower mold 7 is lowered to complete the pressing. At this time, the ejection of N ₂ gas is also completed. After that, the transport arm 5 is retracted to take out the molded optical element.

When SK11 was actually molded, the shape accuracy of the optical element when the pressure was not reduced was 10 μm, whereas the shape accuracy of the optical element when the pressure was reduced was 0.3.
was μm.

According to the present embodiment, the pressure in the molding chamber immediately before pressing is reduced, and it is possible to prevent the accumulation of air between the mold and the optical material and to obtain a highly accurate optical element.
Also, the N ₂ gas is jetted to rapidly cool the optical element uniformly, and the pressure inside the molding chamber can be instantly reduced by the decompression chamber that is constantly decompressed, so that the molding cycle time can be shortened.

[0025]

Second Embodiment FIG. 2 is a partial cross-sectional view used in this embodiment.

The present embodiment differs from the first embodiment in that the vicinity of the hole 12 of the molding chamber 2 and the shape of the transfer arm 5 are different, and the other components are the same, and the same components are designated by the same reference numerals. The description is omitted.

Reference numeral 21 denotes a transfer arm inlet formed on the left side of the molding chamber 2, and a holding portion 22 having a substantially L-shaped cross section is provided on the outside of the transfer arm inlet 21 in a protruding manner. A positioning plate 23 is fixed by a screw 24 of the holding portion 22 in a space formed by the outside of the transfer arm inlet 21 and the holding portion 22. A hole 25 is formed in the positioning plate 23, and the hole 25
A taper 25a is formed on the pressing portion 22 side so as to be an opening.

Reference numeral 26 designates a transfer arm whose tip is movably provided in the heater 4 and the molding chamber 2. The transfer arm 26 has a columnar shape and has the same outer diameter as the hole 25 of the positioning plate 23. is there. A taper 27 tapering toward the tip is formed on the transfer arm 26, and a holding portion 28 for the carrier 14 is formed at the tip. The holding portion 28 has a size that does not extend beyond the outer diameter of the transfer arm 26, and is formed so as not to interfere with the hole 25 of the positioning plate 23.

A pin 29 is fixed to the transfer arm 26 with a screw 30, so that the carrier 14 is held between the upper and lower molds in the molding chamber 2.
When the sheet is conveyed, its positioning can be adjusted. In addition, the positioning plate 23 is a transfer arm 26.
Is smoothly fixed to a position passing through the hole 25 of the positioning plate 23. Then, the transfer arm 26 and the positioning plate 23
Are formed of SUS, and are configured to have the same linear expansion coefficient.

When the molding was carried out by the same molding method as in Example 1 using the apparatus having the above-mentioned structure, the carrying arm 2
No. 6 entered the positioning plate 23 without resistance, and the decompression in the molding chamber 2 was also good.

According to the present embodiment, when the SK11 plano-convex lens is molded, the shape accuracy of the convex surface is 0.3 μ in PV value.
It was possible to obtain an optical element with a high precision of m, and the molding cycle time was almost the same as in Example 1 above.

[0032]

As described above, according to the optical element molding apparatus and molding method of the present invention, when molding an optical element having a convex surface, the pressure inside the molding chamber is reduced during pressing, and the mold and the optical material. It is possible to obtain an optical element with high surface accuracy without the formation of air pockets between and. Further, the decompression in the molding chamber is instantaneously performed by opening and closing the valve by the decompression chambers connected to each other, and the molding cycle time is shortened by uniformly and rapidly cooling the molded optical element by jetting the non-oxidizing gas. be able to. Therefore, a high quality optical element can be molded with high productivity.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a partial cross-sectional view of a second embodiment.

[Explanation of symbols]

 1 Molding Device 2 Molding Chamber 3 Decompression Chamber 4 Heater 5 Transfer Arm 6 Upper Mold 7 Lower Mold 8 Optical Material 9 Nozzle 10, 11 Valve

Claims (2)

[Claims] 1. A transport arm for transporting an optical material placed on a carrier between upper and lower molds, at least one of which has a concave surface, and an optical member arranged around the upper and lower molds. In a molding apparatus for an optical element, which comprises a non-oxidizing gas feeding means for cooling a material, a means for sealing the molding chamber while accommodating the tip of the transfer arm in the molding chamber, and a valve for the molding chamber via a valve. And a decompression chamber connected in series. 2. A heat-softened flat plate-shaped optical material is conveyed between upper and lower molds having at least one molding surface formed as a concave surface, press-molded in a molding chamber under reduced pressure, and then the molded optical element. A method for molding an optical element, which comprises cooling the resin with a non-oxidizing gas.