JPH02157128A - Method for forming optical element - Google Patents

Abstract

PURPOSE:To prevent the fusion of glass to a forming mold at high temp. and to obtain an optical element with the transmissivity not deteriorated by press- forming a glass material with the forming mold in the atmosphere of the mixture of a nonoxidizing gas and gaseous hydrocarbons. CONSTITUTION:The mold charged with a glass material is set in a device, the lid 2 of a vacuum vessel 1 is closed, water is passed through a water-cooled pipe 20, and a heater 8 is energized. At this time, the valves 16 and 18 for the gaseous mixture of Ar and CH4 are closed, and the evacuating valves 12, 13 and 14 are also closed. The valve 12 is opened to start to start evacuation, and the valve 12 is closed when the vessel is evacuated to <= about 10<-2> Torr, and the valve 16 is opened to introduce the gas contg. Ar and 1wt.% CH4 into the vacuum vessel. The material is pressed at about 10kg/cm<2>, then the pressure is turned off, and the material is cooled to a temp. below the transition point at the rate of -5 deg.C/min. The material is then cooled to <= about 200 deg.C, the valve 16 is closed, and the leak valve 13 is opened to introduce air into the vessel 1. The lid 2 is then opened, and the upper mold presser is released, and the formed product is taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Application in Industry-1-" The present invention relates to an optical element molding method for manufacturing optical elements made of glass, such as lenses and prisms, by press molding a glass material.

[Prior Art] The technology of manufacturing lenses by press molding glass materials without the need for a polishing process eliminates the complicated steps required in conventional lens manufacturing, making it possible to manufacture lenses easily and inexpensively. In recent years, it has come to be used to manufacture not only lenses but also prisms and other optical elements made of glass.

Hardness is one of the properties required of the R4V material used for press molding such glass optical elements. Conventionally, many proposals have been made as this type of mold material, such as metals, ceramics, and materials coated with these materials. To give some examples, JP-A-49-5
] 112 is made of 13Cr mardensite steel, which was published in JP-A-52
-45613 proposes SiC and Si, IN<.

[Problems to be Solved by the Invention] However, 13cr martensitic steel has the disadvantage that it is easily oxidized and that Fc diffuses into the glass at high temperatures, causing the glass to become colored. Although S+C and Si3N4 are generally considered to be difficult to oxidize, oxidation still occurs at high temperatures and a film of SiO□ is formed on the surface, causing fusion with the glass, and furthermore, due to their high hardness, the mold itself It has the disadvantage of extremely poor additivity.

Therefore, an object of the present invention is to provide an optical element forming force method suitable for molding glass optical elements r-, and in particular, to prevent the glass and the mold from re-melting at high temperatures and to prevent the mold from being oxidized. <,
It is an object of the present invention to provide an optical element forming force method in which lead does not precipitate and the optical element transmittance obtained does not decrease.

[Means for Solving the Problems] According to the present invention, in the optical element forming force method in which a glass material is press-molded using a molding machine, the press-forming is performed using a Jl-oxidizing gas and a hydrocarbon gas. An optical element molding method is provided, which is characterized in that the method is carried out in a mixed gas atmosphere of: .

Although the mechanism by which the method of the present invention provides excellent mold releasability between the glass and the mold is not necessarily clear, the hydrocarbons in the mixed gas are adsorbed onto the surface of the mold and the glass, causing the glass material to This is thought to be due to the formation of a hydrocarbon film of about 19 to 10 layers between the two.

The present invention will be specifically explained.

Examples of the non-oxidizing gun include inert gas such as NO, Ar gas, and N2 gas. , as the hydrocarbon gas, for example, C114, C2II I+, C:lII, .
The concentration of hydrocarbon gas in the mixed gas is preferably 0.5 to 4,000%. If the hydrocarbon gas is less than Q, 5?99%, it is suitable for glass and molding!
(There is a tendency for fusion to occur without increasing the adhesion of the glass, and if it exceeds 4% by weight, fusion R1 tends to occur, which is thought to be due to a decrease in the strength of the glass.)

Examples of the material of the molding die include SiC, 5llN4,
Yaramic materials with excellent specularity and heat resistance, such as Al2O□, BN, and 'l'iN, can be mentioned.

[Example] The present invention will be specifically explained using two examples.

Embodiment 1 An example of a molding apparatus used in the molding method of the present invention is shown in FIG. 1. In FIG.
I ゛Molding a basic knife/'5 1 mold, 4 is its G shape, 5 is an L-shaped holder for holding down the 2 mold, 6 is a plate mold, 7 is a mold holder, 8 is a heater, 9 1 is a bar for lifting the lower mold, 10 is an air cylinder that operates the bar, 11 is an oil rotary pump, 12°3.14 is a valve, 1
5 is a r4Cl14 mixed gas inflow vibrator, 16 is a valve, 17 is a leak vibrator, 18 is a valve, 19 is a temperature sensor, 20 is a water cooling pipe, and 21 is a stand that supports the vacuum chamber.

The process of manufacturing the lens will be described next. .

First, the Iu) material SiC of the mold is pressed into a predetermined shape, and the lens molding surface is mirror polished. Next, a SiC coating is formed by sputtering. The film thickness was 1.0 mm.

Next, the amount of Furan 1 to system optical glass (SF-'+4) is adjusted to a predetermined amount, and the spherical glass material is placed in the gear of the mold before being installed in the apparatus.

After placing the mold containing the glass material in the device, the lid 2 of the vacuum chamber 1 is closed, water is poured into the water cooling pipe 20, and the heater 8 is heated. Not through L flow. At this time, the Ar"Cl1a mixed gas valves 16 and 18 are closed, and the exhaust system valves 12, 13.
14 is also closed. Note that the oil rotary pump 11 is constantly rotating.

Valve 12 is opened to begin exhaustion. When the temperature becomes below 0-2 Torr, valve I2 is closed, and valve 16 is opened (A
r+ 1% (weight %, same hereinafter) CI+4+ gas is introduced into the vacuum chamber through a bong. When the temperature reaches a predetermined temperature, the air cylinder 10 is operated to pressurize it at a pressure of 1 kg/cm2 for 5 minutes. After removing the pressure, reduce the cooling temperature to -5°
C/min until it becomes below the dislocation point, and then cooled at a rate of 0°C/min or more for 200'
When the temperature drops below C, close valve 16 and close league valve 1.
3 to introduce air into the vacuum chamber 1. Then, open the lid 2, remove the old type presser, and take out the molded product.

” - As described above, flint-based optical glass S[? 14(
Softening point 5p = 586°C, dislocation point 1-g = 485°C
) was used to mold the lens. The molding conditions at this time, that is, the time-temperature relationship diagram is shown in FIG.

In the molding performed in this manner, no fusion occurred between the mold and the glass, and a good molding direction was achieved.

In addition, the molding atmosphere was changed to (Ar + 4% CI + 4) gas, (
A lens was molded using the glass material sF]4 in the same manner as in 1. except that the gas was replaced with Ar+5% Cu41 gas. In the case of (Ar-1-4% CH4) gas, no fusion of the mold and glass occurs, and a good molding direction is 1! ,7. It was done. (8) In the case of +5% CH41 gas, celebrity fusion occurred.

Next, the adhesion between the glass and the mold in the above molding atmosphere was measured, and the transmittance of the lens obtained above was measured. .

Measurement of adhesion force〉 Ar + Cl14 ] %, 8r + Cl144
%, 8r+cl145%, N2 Δ for comparison
"We measured the adhesion in the atmosphere.

The results are shown in Figure 3.

As is clear from Fig. 3, non-oxidizing gas Ar and hydrocarbon gas C! It can be seen that the adhesion between the glass and the mold is small in the mixed gas of No. 14. Therefore, in the Ar + Cl1a gas atmosphere, the excellent mold releasability described in Lens Molding No. 1111 can be obtained. The reason why the adhesion force at 530'C in N2 gas is reduced by 510°C is because the glass peels off due to fusion. Furthermore, in an Ar+Cl14 gas atmosphere, c
The higher the 14e4 degree, the lower the adhesion, but at 5%, cracks may occur, probably due to the low strength of the glass, so the preferred concentration range is 05 to 4%. .

FIG. 4 shows the device used for adhesion measurement.

In Fig. 4, 31 is a vacuum chamber, 32 is a water cooling pipe, 33.34 is a stand, 35 is a vacuum pump, 36 is an air supply pipe, 37 is a vacuum exhaust pipe, 338 is a leak pipe, 39.40° 41.42 is Valve, 43 is air cylinder, 44 is load cell, 4
5 is a lot, 46.47 is a thermocouple, 48 is an insulator, 49
is a heater, 50 is a stand, 51 is a type 2 retaining ring, 5
2 is the upper mold of the sample material, 53 is the plate mold, 54 is the glass material, 55
56 is a lower die, 56 is a pedestal, and 57 is a pedestal.

Next, the procedure for measuring the dense 49 force will be described.

As shown in Figure 4, flint-based glass material (SF)
4) Apply 54 to 1 inch of the lower mold 55, and place the sample material into the mold 5.
2 is mounted on the flat surface of the rod 45 with an upper die holding ring 51. The vacuum pump 35 is constantly rotating. Air supply valve 3
9. From the state where the leak valve 42 and the exhaust system valves 40 and 41 are closed, the valve 40 is opened to begin exhausting the inside of the vacuum chamber. When the inside of the vacuum chamber becomes I0-2 Torr or less, close the valve 40, open the valve 36, and release the gas to the bomb (Ar+
The water is introduced into a vacuum chamber with a constant I% CILI level 6. Next, water is caused to flow through the water cooling tube 32, and an electric current is passed through the heater 49. When the temperature of the upper mold and 11 reaches 530°C, operate the air cylinder 43 and lower the 7 lot 45 to I OJ/c.
Pressure is applied for 5 minutes with 1 force of m''. The state after pressurization is shown in Fig. 5. In Fig. 5, 58 indicates the molded product. Next, after removing the pressure by operating the air cylinder, the lot is Gradually let them borrow two. At this time, the force required to release the molded body 58 from the L shape is measured by the load cell 44.

<Measurement of Transmittance> The transmittance of the three types of lenses obtained by the above lens molding was measured using a self-recording spectrophotometer 340 manufactured by IU Manufacturing Co., Ltd. The results are shown in Figure 6. ,56
The transmittance in mm1 is (Ar+1%CU, ) gas,
(Ar+4%C114) gas, (Δr+5%C04)
In all cases of gas, about 86% of the glass material S l-
It was the same as 4, and there was no deterioration in molding. This indicates that the reduction of lead oxide in the glass did not occur at all during molding.

Transmittance measurement conditions.

Feed speed: 3m1n / IQO-850%m (
Wavelength range) Slit width: 2 nm Vertical magnification: 100% Measuring point: UV-VIS (ultraviolet-visible) sensor:
Tomal Example 2 FIGS. 7 to 12 are diagrams showing other apparatuses used in the molding method of the present invention.

The overall configuration of this device includes a material intake chamber 61, a heating section 62
, a material transfer section 63, a press section 65, an annealing section 66, and a molded product removal chamber 67. The material intake chamber 61, the heating section 62, the material transfer section 63, and the press section 65 are arranged in the same line, and a slow cooling section 66 is arranged in parallel with these lines.

A first transfer chamber 81 is constructed near the entrance of the heating section 62, and the material intake chamber 61 is provided in this first transfer chamber 81. A second transfer chamber 82 is constructed near the exit of the breath section 65 (21), and a slow cooling section (3
A transfer chamber 83 is constructed, and these second and 33rd transfer chambers are connected by a transfer path 85. In addition, a fourth transfer chamber 84 is constructed near the outlet of the slow cooling section 6 [3], and this fourth
The transferred molded product take-out chamber 67 is provided in the transfer chamber 84, and is connected to the fourth transfer chamber 84 by a first transfer 45s + melting recirculation path 86. This molding apparatus has a molding chamber 99 that forms a continuous circulation path. .

71 is a pallet to which this molding chamber 99 is transferred, and on the pallet 71, a material mounting table 72, a -11 (" 73 for press molding) and a lower mold 74 are arranged with a fixed interval. Also, on the outer periphery of l;' !fil! 74, a guide member 87 is provided to guide one movement of the lower mold 73 onto the lower mold 73 and to serve as a positioning guide for the lower mold 733.
It is fixed so that it protrudes slightly from the upper end. 1-
The press molding surfaces of the mold 73 and the lower j (:474) are provided with mirror surfaces 73a and 74a for molding optical element functional surfaces, respectively.

As a means for transferring the pallet 71 in the above-mentioned path, an extrusion cylinder 91 is provided in the first transfer chamber 81, and the pallet 71 is moved to the press section [35] by this extrusion cylinder. The second transfer chamber 82 is provided with a push-out cylinder 93 and a draw-out cylinder 92, and the pallet 71 moved to the brace part 65 by the draw-out cylinder 92 is pulled out to the second transfer chamber 82, and the pallet 71 is pulled out by the push-out cylinder 93. The pallet 71 moved to the second transfer chamber is pushed out to the third transfer chamber 83. The third transfer chamber 83 is provided with an extrusion cylinder 94, and the pallet 71 moved to the third transfer chamber 83 is pushed 111 to just before the fourth transfer chamber 84 by the extrusion cylinder. A push-out cylinder 95 and a draw-out cylinder 96 are installed in the transfer chamber 84 of 4-. 1, and a drawer cylinder 96 connects the fourth transfer chamber 84
The pallet 71 that has been moved to the straight position 01j is pulled out to the fourth transfer chamber 84. 2 Then, this fourth transfer chamber 84
The pallet 7I that has been moved is pushed out again to the first transfer chamber 81 by the pushing cylinder 95.

In this manner, the pallet 71 is transferred to each of the 17 culms by a series of cylinder extrusion or withdrawal operations, and can be moved within the molding chamber 99 of the apparatus. Note that the pallet 71 is placed on a rail (not shown) provided in the molding chamber 99, and is moved on the rail by pushing out or pulling out a cylinder.

Next, each part of the molding chamber described in -1-) will be explained.

−114;+ in the material transfer section 62 and the molded product removal chamber 07;
Holders 76 and 80 (FIG. 10) are provided for lifting the mold 173 to the lower die 74 at a required interval. This handle hunt is moved downward by a lift means (not shown). Furthermore, the material transfer department (33
is provided with a suction finger 64 for transferring the material 75 placed on the material mounting table 721- in the material intake chamber 61 to the lower I-I, lj 74-1- (table 10 figure), After the tr and mold 73 are lifted by F by the operation of the lifting hand 76, the suction hunt 64 is activated,
The material 75 is transferred to a predetermined position on the lower mold 740. This suction finger 64 is connected to the material mounting table 72 of the pallet 71
It is configured to operate with a constant stroke of 1-1 millimeter parallel translation by a predetermined interval length between 4 and 4.

In addition, the material 7 is stored in the material intake chamber 61 and the molded product removal chamber 67.
5 on the mounting table 72-1-, or place the molded product 78 on the mounting table 72-1-.
A suction finger 79 for taking out the mold 74 is provided (FIG. 12).

The breath portion 65 is provided with a breath rod I/77 for pressing the mold 1 73 during breath molding (the first
Figure 1).

In addition, in this apparatus, the inside of the molding chamber 99 is 1-Fll.
In order to prevent the mold material forming the 73 and 1 rishi 74 from being oxidized due to high d1,
Since it is necessary to fill with atmospheric gas, the sliding parts of the above-mentioned handle hunt 7 [3, suction fingers 64 and four braces 1 to Fufu hat and the outer wall of the furnace body 99 should be sufficiently shielded. Although not shown in the drawings, this device requires a material 7.
5 into the material intake' [61, when outside air is taken into the molding chamber 99
"Do not infiltrate the inside of the sea urchin.": It is necessary to provide an atmosphere exchange room for sea urchins. Infrared gas analysis to adjust the CI+4 gas concentration in the atmosphere;? 1100 is installed in the molding room.

Next, we will discuss the operation of the device configured as follows.
Brace molding shown in FIGS. 12 to 12 will be explained according to the culm+++n. FIG. In order to prevent oxidation of the periphery material 74, the inside of the molding chamber 99 is evacuated to IX]0-2 Torr using a vacuum pump (not shown), and then filled with (Ar+1%cn4) gas.

The C114 gas concentration is process-controlled using an infrared gas analyzer 100 to within a volume value.

Next, the heaters 97 and 98 are energized to raise the temperature inside the furnace to a predetermined value. After the completion of the ambient temperature, the material 75 is passed through the atmosphere exchange chamber described in 1-1 in the material intake chamber 61 and placed on the mounting table 72 of the pallet 71 in the material intake chamber 61 using the suction finger 79 as shown in FIG. Deploy.

Next, the extrusion cylinder 91.93.94
．． 95 and the drawer cylinders 92 and 96, each time the pallet 71 is sequentially sent from the molded product take-out chamber 67 to the material intake chamber 61, the material 75 is placed on each mounting table 720 in the above-described manner.

By repeating this operation 1-i, the blanks 5 and 1' supplied to the first pallet 71 and the mold 73
and - When the upper mold 74 is heated to a temperature necessary for press molding near the material transfer portion 63, the material 75 is transferred to the F-type 74 (step 11).

Note that at this time, it is desirable that the material 75, the L-shaped mold 73, and the upper mold 74 be heated to approximately the same temperature of d11 degrees. By doing this, the temperature of the material 75 after transfer does not change depending on the temperature of the first mold 73 or the bottom mold 74, and the press molding can be performed under the optimal press temperature condition. In the material transfer section 6:3, as shown in FIG. After this, the extrusion cylinder 91
The pallet 71 on which the material 75 has been transferred by extruding is moved to the first position of the brace part 65. At this time, the handle
At the same time as removing the handle 76, actuate the brace rod 77, press the upper die 7; 3 with a predetermined brace loaf,
Breath molding is performed on the material 75.

Next, release the pressure on the bracelet rod 77, and press the mold 7.
3 maintains its state at the time of pressing, and by operating the extrusion cylinder 91, this pallet 71 is moved from the pressing portion 65 to near the exit Ml (=J) of the pressing portion 65.

Furthermore, after this pallet 71 is pulled out by the drawer cylinder 92 and moved to the second transfer chamber 82, it is pushed out by the extrusion cylinder 93, and passed through the transfer path 85 to the transfer chamber 82.
Transfer to.

Next, the pallet 71 is extruded by the extrusion cylinder 94 in the direction of the molded product removal chamber 67, but since another pallet 7I is arranged in the 0i direction in the extrusion direction, While this operation continues, the molded product 78 held in the seventh mold 73 and the upper mold 74 reaches the exit (=J) of the slow cooling section 66 while the pallet 71 approaches the exit (=J) of the slow cooling section 66.
6, where it is gradually cooled 1. The pallet 71, which has thus moved to the leading position of the slow cooling section 66, reaches the molded product take-out chamber 67 by the drawer cylinder 96.

Next, the holding hunt 80 is operated to remove the upper mold 73, and then the molded product 78 is taken out by the suction fingers 79. Then, the pallet 71 from which the molded products have been taken out is pushed out by the extrusion cylinder 95 into the feeding path 86.
The material is then transferred to the material intake room 61.

In the device described in ``-, the material 15 is placed 6 on the material loading table 12-1- until it is time to transfer the straight curved material for press molding.
3 and the lower die 14, the material 1
The structure is such that the reaction between Type 5 and Type 73 and 74 is as rain-proof as possible.

In the molding performed in this manner, no fusion of If, 11 and the glass occurred, and a good molding surface was obtained.

In addition, the transmittance of the obtained lens was also determined (j-line (587, 56
nm) is good at 86%! It was If.

[Effects of the Invention] According to the method of the present invention, the glass and the mold do not fuse with each other in high flood 1, lead is not oxidized, lead is not precipitated, and the transmittance of the obtained optical element is low. -Do not play.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a molding apparatus used in the optical element molding method of the present invention. FIG. 2 is a time-temperature relationship diagram during lens molding. Figure 3 is a diagram showing the relationship between the adhesion force and molding temperature between the glass and the mold, Figure 4 is the device used to measure the adhesion force, and Figure 5 is an enlarged view showing the state of the force and temperature during measurement. It is. FIG. 6 is a transmittance measurement diagram of the molded body. Figure 7 ~ 1st
FIG. 2 is a sectional view of another molding apparatus used in the method of the present invention, FIG. 7 is an overall plan view thereof, and FIGS. 8 to 12 are schematic sectional views of pallets at each upper stage. l...Vacuum chamber body, 2...Lid, 3...Old model, 4...Lower mold, 5..."-mold holder, 6...Mold, 7...Mold holder- , 8...
Heater 9... Lifting rod, 10... Air cylinder, 11... 1111 Rotary pump, 12.1
3.14...Valve, 15...Inflow pipe, I
6... Valve, 17... Outflow pipe, 18.
... Valve, 19... Temperature sensor, 20... Cold water pipe, 21... Stand, 31... Vacuum tank, 32... Water cooling pipe, 33.34... Frame, 35... Vacuum pump, 36... Air supply pipe, 3
7... Vacuum exhaust pipe, 38... Leak pipe, 39.
40.41.42... Valve, 43... Air cylinder 44... Load cell, 46, 47... Thermocouple, 49... Heater 51... Ten-shaped retaining ring, 53... For Mold, 55... Lower mold, 57... Frame, 61... Material intake chamber, 63... Material transfer section, 66... Annealing section, 72... Material mounting table, 74 ...lower mold. 45... lot, 48... heat insulator, 50... mount, 52...''-mold, 54... (1 portrait material, 56... pedestal, 58... molded body, 62...Heating part, 65...Brace part, 71...Pallet, 73..."-mold,

Claims (1)

[Claims] 1. In an optical element molding method by press molding a glass material using a mold, the press molding is performed in a mixed gas atmosphere of a non-oxidizing gas and a hydrocarbon gas. Characteristic optical element molding method. 2. The optical element molding method according to claim 1, wherein the concentration of hydrocarbon gas in the mixed gas is 0.5 to 4% by weight.