JPH0977520A - Optical element forming device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the sure releasing of formed optical elements from dies by constituting a forming device for press forming the optical elements in such a manner that the forming surface of upper dies and the forming surfaces of lower dies respectively vary in their surface roughness from each other. SOLUTION: The plural upper dies 22 are supported by a moving upper die supporting member 14 via an upper die pressing drum 20 and the plural lower dies 26 are supported by a stationary lower die sill 12 via a lower die pressing drum 24. Further, the forming surfaces of the upper dies 22 and the forming surfaces of the lower dies 26 are so formed as to vary in their surface roughnesses from each other. More preferably, the surface roughness of the forming surfaces among the smaller surface roughness upper dies 22 and the larger roughness lower dies 26 is specified to Rmax of <=0.03μmm. Optical element materials 4 are placed on the forming surfaces of the respective lower dies 26 and are softened by heating with heaters 18 and, thereafter, the moving upper die supporting member 14 is lowered to crush the optical element materials 4 between the upper dies 22 and the lower dies 26, by which the press forming is executed. The upper dies 22 are then risen after cooling and the molded goods of the optical elements are taken out.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical element molding apparatus and method for pressing an optical element material softened by heating to form an optical element and then cooling the optical element to obtain an optical element.

[0002]

2. Description of the Related Art In the conventional glass molding method, after pressing and cooling, either the upper mold or the lower mold is moved from the other, and the molded optical element (molded product) is predetermined. It was taken out from the inside of the molding apparatus by being sucked or pinched by using the jig. However, when the upper mold and the lower mold are separated from each other after cooling, the molded product is not always on the lower mold and often adheres to the molding surface of the upper mold.

When the upper mold and the lower mold are separated from each other after cooling, it is difficult to take out the molded product by a jig unless the molded product is always positioned on either side of the upper mold and the lower mold. In addition, there is a possibility that a jig may be applied to the molding surface of the upper mold or the lower mold without moldings to damage the molding surface.

As an example of a means for solving this inconvenience,
JP-A-5-43259 (Japanese Patent Application No. 3-334576)
There is a "method for manufacturing an optical element" disclosed in. This publication discloses a method of detecting the position of a molded product using a sensor and then taking out the molded product from the apparatus. However, in this method, it is necessary to provide a sensor for detecting the position of the molded product, an electric circuit connected to the sensor, and the like, and thus the device becomes complicated and large.

Another example is the "press lens molding method" disclosed in Japanese Patent Application Laid-Open No. 5-70154 (Japanese Patent Application No. 4-62473). This publication discloses a method in which a temperature difference is provided between the upper mold and the lower mold so that the molded product adheres to the mold on the high temperature side. However, in this method, since a temperature difference is generated between the upper and lower sides of the optical element, a defect such as distortion of the molded product may occur.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and requires no special equipment, and an optical element for surely releasing the molded optical element after press molding. An object of the present invention is to provide a molding apparatus and method.

[0007]

SUMMARY OF THE INVENTION When an extremely smooth plane is formed on each of two objects and the two smooth planes are joined together, the two
It is well known that an intermolecular force (atomic force) works between two planes to bring two objects into contact with each other. The present invention
It was made with this fact in mind, and the surface roughness (smoothness) of the upper mold surface and the lower mold surface was made different from each other, and after pressing, the upper mold and lower mold were separated. At that time, the intermolecular force that acts between the molding surface with the smaller surface roughness and the surface to be molded of the molded product will attempt to reliably release the molded product from the molding surface with the larger surface roughness. It is a thing.

That is, the present invention is an apparatus for molding an optical element by pressing an optical element material softened by heating with a molding die consisting of an upper die and a lower die, and It is characterized in that the surface roughness of each molding surface is different from each other.

Further, the present invention is a method for molding an optical element by pressing an optical element material softened by heating with a molding die consisting of an upper die and a lower die, wherein the surface roughness of each molding surface is It is characterized in that an optical element is molded by using an upper mold and a lower mold which are different from each other.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. A molding apparatus 10 to which the present invention is applied includes a fixed lower mold base 12 fixed to a main body of the molding device 10 and a movable upper mold support member 14 which is vertically driven so as to be able to come into contact with and separate from the fixed lower mold base 12. have. A quartz tube 16 is provided around the fixed lower mold base 12 and the movable upper mold support member 14. The quartz tube 16 is movable in the vertical direction, and a heater 18 is fixed around the quartz tube 16.

An upper die pressing cylinder 20 is fixed to the movable upper die support member 14 via a bolt or the like (not shown) so as to be detachable. The plurality of upper molds 22 are supported by the movable upper mold support member 14 via the upper mold pressing cylinder 20. On the other hand,
A lower presser cylinder 24 is removably fixed to the fixed lower mold base 12 via bolts or the like (not shown). The plurality of lower molds 26 are supported by the fixed lower mold base 12 via the lower mold pressing body 24. A mold height adjusting spacer 28 having a predetermined thickness is provided between the lower surface of each lower mold 26 and the upper surface of the fixed lower mold base 12. The mold height adjusting spacer 28 is for making the mold height the same for all of the plurality of molds and for making the thickness of the molded product uniform. The mold height is the total length of the length of the upper mold 22, the length of the lower mold 26, and the length (thickness) of the mold height adjusting spacer 28. The temperature of the molds (upper mold 22 and lower mold 26) heated by the heater 18 is set to the lower mold holding cylinder 24.
It is measured by a thermocouple 30 in which the temperature sensor part is located.

Further, the molding apparatus 10 has a jig 7 for taking out each of the optical element molded products 5 completed after the press molding to the outside of the device (FIG. 3). The jig 7 is provided so as to be movable back and forth between an upper mold 22 and a lower mold 26 separated from each other. More specifically, after the pressing step and the cooling step, the quartz tube 16 is moved upward from the fixed lower die base 12 together with the movable upper die support member 14, and then the jig 7 is
It is inserted between the upper mold 22 and the lower mold 26, and each optical element molded product 5 is adsorbed by the corresponding adsorption portion 7a and carried out of the apparatus.

Usually, the molding die used for glass molding is processed so that the surface of the molding surface becomes R _max 0.06 μm or less. Preform (optical element material)
Has a surface roughness of R _{max of} 0.05 μm or less. This is press-molded with a viscosity of about 10 ⁹ to 10 ¹¹ poises, and the molding surface of the molding die and the preform are treated with a strong force. It is in close contact. Under these conditions, during press molding, the preform material does not enter the fine irregularities on the molding surface of the molding die and the molded product does not adhere to the molding surface of the molding die.

Immediately after the press molding, the molded product molded from the preform adheres to the mold with a slight force. This force is an intermolecular force that acts between two objects when the smooth surfaces are brought together. It is due to. Therefore, in the present embodiment, by setting the surface roughness of the molding surface of the lower mold to be smaller than the surface roughness of the molding surface of the upper mold, when the upper mold and the lower mold are separated after the press molding, the intermolecular force It is intended to make the molded product always exist on the molding surface of the strong lower mold.

As shown in FIG. 5, each of the upper mold 22 and the lower mold 26 used in the present invention has a concave molding surface 32. In each of the upper mold 22 and the lower mold 26, the thin film 2 for the purpose of heat resistance, oxidation resistance and wettability is formed on the surface of the base material 1 on the molding surface 32 side.

For the lower mold 26, silicon carbide (SiC) deposited by the CVD method is used as a base material. In the processing operation of the forming surface 32 of the lower mold 26, first, the forming surface of the base material is ground by an ultra-precision lathe, and then processed with a diamond abrasive so that the surface roughness becomes R _max 0.03 μm or less. . Then, a thin film 2 made of various ceramics, gold, platinum, a noble metal such as a platinum group metal, or the like is formed on the surface of the processed molding surface by a method such as sputtering or ion plating. The surface roughness of the processed molding surface is
It is not affected by the formation of this thin film 2.

For the upper die 22, cemented carbide tungsten carbide WC is used as a base material. In the working of the molding surface 32 of the upper mold 22, first, the molding surface of the base material is ground by an ultra-precision lathe, and then a diamond abrasive is used to make the surface roughness R _max 0.06 μm or less and the surface of the lower mold 26. Roughness R
_Polish to 1.5 times _max or more, and form thin film 2 on the surface by sputtering, ion plating, etc., made of various ceramics, precious metals such as gold, platinum and platinum group metals. To do. The surface roughness of the processed molding surface is not affected by the formation of this thin film 2.

Each of the upper mold 22 and the lower mold 26 has a molding surface 3
A flange portion 3 is integrally formed at an end portion opposite to the end portion on which 2 is formed, and the flange portion 3 prevents the upper die holding cylinder 20 or the lower die holding cylinder 24 from coming off. ing.

The upper mold holding cylinder 20 is provided with five upper molds 22, and the lower mold holding cylinder 24 is provided with five lower molds 26 facing these five upper molds 22. FIG.
As can be seen from the top view of the lower die holding cylinder 24 shown in FIG.
The remaining four are arranged at equal intervals in the circumferential direction around the lower die 26 in the center. Although not shown, five upper molds 22 are arranged on the upper mold holding cylinder 20 in the same arrangement as the lower mold 26 of the lower mold holding cylinder 24.

The molding apparatus 1 of the first embodiment having the above construction
According to No. 0, when the upper mold 22 is separated from the lower mold 26 after the press molding, the intermolecular force generated between the lower mold 26 and the molded surface of the molded product is more than the molded product of the upper mold and the molded product. The molded product is always located on the lower mold 26 because it is larger than the intermolecular force generated between the molded product and the surface.

A specific molding example of the optical element by the illustrated molding apparatus 10 of the present invention will be described. FIG. 1 shows a state before molding in which the preform 4 is placed on the molding surface of each lower mold 26,
2 shows a state in which the preform 4 is press-molded, and FIG. 3 shows a state in which the upper mold 22 is separated from the lower mold 26 after the molding is completed.

First, as shown in FIG. 1, with the upper mold 22 and the lower mold 26 separated from each other, the preform 4 is placed on the molding surface 32 of each lower mold 26. After that, the movable upper die supporting member 14 is lowered to bring the upper die 22 close to the preform 4 so that the upper die 22 does not come into contact with the preform 4, and the quartz tube 16 is heated by the heater 18 while being purged with an inert gas.

The temperature measured by the thermocouple 30 is 420 ° C.
When it becomes, the movable upper die support member 14 is further lowered,
The preform 4 is crushed between the upper mold 22 and the lower mold 26 to perform press molding (FIG. 2). The molding pressure at this time is usually around 100 kg / cm ² .

After the molding of the preform 4 between the upper mold 22 and the lower mold 26 is completed, the heater 18 is stopped and cooled. After that, when the temperature measured by the thermocouple 30 reaches a temperature below the glass transition point of the molding material, the movable upper die support member 14 and the quartz tube 16 are raised (FIG. 3). At this time, the respective optical element molded products 5 made of the preform 4 are all positioned on the lower mold 26 without adhering to the molding surface 32 of the upper mold 22. After that, each optical element molded product 5 is taken out of the apparatus by the jig 7 moved onto the lower mold 26.

[Molding Example 1] Cemented carbide tungsten carbide WC was used as the base material for the upper mold 22. In the processing of the molding surface 32 of the upper die 22, first, the molding surface of the base material was ground with an ultra-precision lathe, and then polished with a diamond abrasive to obtain a molding surface having a surface roughness R _{max of} 0.026 μm. .
Then, platinum is sputtered on the surface by 1 μm.
The thin film 2 was formed by coating. This coating did not change the surface roughness of the processed molding surface 32.

Silicon carbide (SiC) deposited by the CVD method was used as the base material for the lower mold 26. This lower mold 26
In the processing of the forming surface 32, first, the forming surface of the base material was ground by an ultra-precision lathe, and then polished with a diamond abrasive to obtain a forming surface having a surface roughness R _{max of} 0.012 μm. Then, similarly to the upper die 22, platinum was coated on the surface by sputtering to a thickness of 1 μm to form a thin film 2.
This coating did not change the surface roughness of the processed molding surface 32.

A plurality of sets of these upper mold 22 and lower mold 26 were set in the same molding apparatus 10 in the arrangement shown in FIG. next,
The PSK50 manufactured by Sumita Optical Glass Co., Ltd. selected as the preform 4 is placed on the molding surface 32 of each lower mold 26, and thereafter,
The movable upper die support member 14 is lowered to bring the upper die 22 close to the preform 4 until it comes into contact with the preform 4, and then the quartz tube 1
The inside of 6 was heated with a heater 18 while purging with nitrogen gas. PSK50 manufactured by Sumita Optical Glass Co., Ltd. selected as the preform 4 is an optical element material having a surface roughness R _{max of} 0.010 μm.

The temperature measured by the thermocouple 30 is 420 ° C.
Then, the movable upper mold supporting member 14 was lowered, and the preform 4 was crushed between the upper mold 22 and the lower mold 26 to perform press molding. The molding pressure at this time is about 100 kg.
/ Cm ² . Then, the heater 18 was stopped and gradually cooled, and when the temperature measured by the thermocouple 30 reached 350 ° C., which was below the transition point of the optical element material, the movable upper die supporting member 14 was raised. At this time, the optical element molded product 5
None of them existed on the lower mold 26 without adhering to the upper mold 22. Thereafter, the jig 7 is used to form the optical element molded product 5
Was adsorbed and taken out of the apparatus.

In the above-mentioned forming example 1, since the base material of the lower die 26 is made of ceramics and the base material of the upper die 22 is made of cemented carbide tungsten carbide WC, the surface of the forming surface 32 which is generated by repeating the forming operation. Roughness is upper mold 2
No. 2 progresses faster, and therefore, the relationship of "surface roughness of upper mold surface> lower mold surface" holds for a long time. Therefore, the press molding was repeated 10,000 times by the molding apparatus 10 in the above-mentioned molding example 1, but when the mold was released after the press molding, the optical element molded product 5 was never attached to the upper mold 22. .

In the above molding example 1, the surface roughness is R _max 0.
PSK50 manufactured by Sumita Optical Glass Co., Ltd. having a surface roughness of Rmax of 0.05 was used.
As a result of experiments, it was found that the optical element molded product 5 does not adhere to the upper mold 22 when the preform having a size of μm or less is used and the mold is released after the press molding.

Contrary to the above molding example, when the surface roughness of the molding surface of the upper mold is made smaller than the surface roughness of the molding surface of the lower mold, the molded product does not always have an upper surface when the mold is released after the press molding. Does not adhere to the mold. The reason for this is that the intermolecular force, which is the adhesive force between the molded product and the mold, is superior between the molded product and the upper mold, but this intermolecular force may be lost by gravity and the molded product may fall. Because there is. Therefore, it is preferable to set the surface roughness of the molding surface of the upper mold to be larger than the surface roughness of the molding surface of the lower mold.

The above-described molding apparatus 10 has a plurality of upper molds 22.
However, the present invention is not limited to the number of pairs of molding dies, and may include only a pair of an upper mold and a lower mold, or other A configuration including a plurality of pairs of molds may be used. Further, in the above-described embodiments and molding examples, the molding apparatus of the present invention has been described with respect to the molding apparatus 10. However, the present invention is not limited to this, and may be a molding apparatus including an upper die and a lower die that are contacted and separated from each other. For example, the present invention can be applied to a molding device having another structure.

[0033]

As described above, according to the apparatus and method for molding an optical element of the present invention, since the surface roughness of the molding surface of the upper mold is different from that of the molding surface of the lower mold, It is possible to reliably release the molded optical element after the press molding without using any special equipment.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a molding apparatus to which the present invention is applied.

FIG. 2 is a vertical sectional view showing the molding apparatus of FIG. 1 in a state different from that of FIG.

3 is a vertical cross-sectional view showing the molding apparatus of FIG. 1 in a state different from that of FIGS. 1 and 2. FIG.

FIG. 4 is a top view of a lower die holding cylinder of the molding apparatus shown in FIG.

5 is a vertical sectional view of an upper die or a lower die of the molding apparatus of FIG.

[Explanation of reference numerals] 10 molding device 12 fixed lower mold base 14 movable upper mold supporting member 16 quartz tube 18 heater 20 upper mold holding cylinder 22 upper mold 24 lower mold holding cylinder 26 lower mold 30 thermocouple 32 molding surface

Claims (7)

[Claims] 1. An apparatus for molding an optical element by pressing an optical element material softened by heating with a molding die composed of an upper die and a lower die, wherein a molding surface of the upper die and a molding surface of the lower die are formed. A molding device for an optical element, wherein the respective surface roughnesses are different from each other. 2. The molding apparatus for an optical element according to claim 1, wherein the molding surface of the molding surface of the upper mold and the molding surface of the lower mold having the smaller surface roughness has a surface roughness Rmax of 0.03 μm or less. . 3. The optical element molding apparatus according to claim 1, wherein the surface roughness of the molding surface of the upper mold is larger than the surface roughness of the molding surface of the lower mold. 4. The optical element molding apparatus according to claim 3, wherein the surface roughness of the molding surface of the upper die is 1.5 times or more the surface roughness of the molding surface of the lower die. 5. The optical element molding apparatus according to claim 1, wherein the optical element material has a surface roughness Rmax of 0.05 μm or less. 6. A method of molding an optical element by pressing an optical element material softened by heating with a molding die composed of an upper die and a lower die, wherein the surface roughness of each molding surface is different from each other. A method for molding an optical element, which comprises molding an optical element using a mold and a lower mold. 7. The method according to claim 6, wherein the surface roughness of the molding surface of the lower mold is made smaller than the surface roughness of the molding surface of the upper mold, and the optical element is molded using these upper mold and lower mold. A method for forming a featured optical element.