JP2835241B2 - Optical element molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming an optical element such as a lens for glass and a pickup head lens for a compact lens.

[0002]

2. Description of the Related Art In recent years, optical element molding methods of this type include a method of polishing and finishing, which requires complicated steps, and a method of plasticizing a preliminarily measured glass block by an induction heating method using a high frequency or the like. Attention has been paid to a method of directly processing a glass lens into a final use shape by pressing.

Conventionally, this type of glass lens press molding apparatus is disclosed in Japanese Unexamined Patent Publication No.
There is one having a configuration as disclosed in Japanese Patent No. 170225.

[0004] Since such a conventional apparatus in the prior art is induction heating (hereinafter referred to as RF heating), it is inactive for the purpose of achieving uniform heating of the mold and shortening the cooling time. It proposes the introduction of gas.

That is, by forming an exhaust passage formed of a plurality of flow grooves communicating with the inside of the molding chamber in a radial manner between a die plate and a heat insulating material disposed on the back side of the mold, the molding is performed. The mold is cooled.

[0006]

SUMMARY OF THE INVENTION The above-mentioned prior invention,
This is a very effective means for uniformly cooling the mold, and is an indispensable technique especially for molding a large-diameter precision lens.

However, Japanese Patent Application Laid-Open No. 63-170225
The technique disclosed in Japanese Patent Laid-Open Publication No. H10-25067 indirectly cools a mold, and thus has a problem that a sufficient reduction in cooling time cannot be expected. In addition, if the cooling time of the mold in the molding cycle is long, not only does mass productivity decrease,
There is a problem that the consumption of the inert gas also increases.

The present invention has been made in view of the above circumstances, and an object thereof is to sufficiently reduce the cooling time of a mold after press molding and improve mass productivity. An object of the present invention is to provide an optical element molding apparatus.

[0009]

In order to solve the above-mentioned problems, an apparatus for forming an optical element according to the present invention comprises a chamber
And provided in this chamber to mold the optical element
A pair of molds with molding surfaces and each mold
Re a pair of die plates to be supported from the rear, the die plate
The plate is connected to the back of the
Materials with different conductivity, emissivity and / or light transmittance
And a cavity is formed along the central axis.
And the intermediate member of the pair, respectively connected to the rear of the intermediate member, and a pair of shaft members having a supply passage of the internal inert gas
Wherein the die plate, or the supply passage therein
Pass the inert gas supplied through the cavity
A through hole is formed, and contact with the mold is made.
The contact surface and the contact surface with the intermediate member are respectively
A plurality of active gas flows and is discharged into the chamber
Are formed .

[0010]

According to the above-mentioned means, the inert gas is brought into direct contact with the mold of the mold member to be cooled, thereby improving the cooling efficiency of the mold member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to one embodiment shown in FIGS. FIG. 1 schematically shows the entire configuration of an optical element molding apparatus according to the present invention. That is, in the figure, reference numeral 1 denotes a main body frame, and an upper shaft 2 as a shaft member fixed by bolts 3 or the like is provided on a ceiling portion of the main body frame 1. A fixed-side die plate 6 formed of a tungsten alloy or the like is attached to a lower end portion of the upper shaft 2 by a bolt 5 via a joint 4.

The joint 4 is preferably made of a material different from the die plate 6 in heat conductivity and / or radiation rate and light transmittance, and is formed of silicon nitride or quartz glass. Above the die plate 6 is adapted to the outer mold 8 made of such Similarly tungsten emissions alloy and the die plate 6 is attached by bolts (not shown).

The mold 9 is held by the die plate 6 and the outer mold 8 to form a mold member 7a. The mold 9 has a molding surface 9a for molding an optical glass element, and is molded of a ceramic such as silicon carbide (SiC) or a cemented carbide mainly containing tungsten carbide (WC). A lower shaft 10 is provided below the upper shaft 2 as a shaft member coaxially opposed thereto.

An upper end of the lower shaft 10 is attached to the upper shaft 2.
In the same manner as described above, a joint 11, a moving plate 12, a mold 13, and an outer mold 14 constituting the mold member 7b are attached.

The lower shaft 10 is provided with a desired pressing force at a desired speed in a vertical direction by a servomotor 21 or another device such as a hydraulic drive device at another desired position. It can be stopped.

On the other hand, a bracket 15 is attached to the upper shaft 2 so as to be vertically movable. The bracket 15 is moved up and down by a driving device (not shown) attached to the main body frame 1. The space between the bracket 15 and the upper shaft 2 is slidably sealed by a seal material 15a. The bracket 15 is provided with an infrared lamp 16 as a heating source and a high-frequency induction heating coil used as a heating source in other embodiments.

An infrared lamp 1 is provided on the inner peripheral side of the heating source.
6 is a cylindrical chamber made of quartz glass made of a material which does not transmit most of the infrared light from No. 6 and is not subjected to induction heating.
Is provided. The chamber 17 is held by the bracket 15, and is moved up and down by the up and down movement of the bracket 15.

The upper end surface of the chamber 17 is sealed by a packing 18 made of silicon rubber or the like. The lower end surface of the chamber 17 is sealed when the chamber 17 is lowered by a packing 20 such as silicon rubber provided on a lower bracket 19 fixed to the main body frame 1.

Further, since the outer peripheral portion of the lower shaft 10 is also sealed with the main body frame 1, if a gas is introduced into the chamber 17 and the gas is exhausted, the gas is removed from the atmosphere. (Hereinafter referred to as purge).

The reason for purging the inside of the chamber 17 is that the molds 9 and 13 are provided with a code to prevent glass adhesion.
Coating and die plate - DOO 6,12 is for preventing oxidation such as the outer mold 8, 14 cooling, as the gas is used an inert gas such as N ₂ gas, when after molding cooling also by N ₂ gas doing. Next, a method for molding an optical element will be described.

First, the bracket 17 is raised by a driving means (not shown) to raise the chamber 17.
Thereafter, a preform (material of an optical element) 22 such as a sphere is placed on the molding surface 13a of the movable side mold 13, and then the bracket 15 is lowered by the driving means to lower the chamber 17. At this time, the gas supply passage 2a of the upper shaft 2 and the lower shaft 10 from the N ₂ gas supply source (not shown), N ₂ gas into the chamber -17 through 10a is supplied N ₂ Pa - is di. The N ₂ Pas - after di also N ₂ gas is continuously supplied, also by energizing the infrared lamp 16, an infrared is transmitted through the chamber -17, this infrared, mode - field 9,13, die plate - DOO 6 , 12, and outer dies 8, 14 are heated to a predetermined temperature to form a preform 22.
Is heated.

Here, since it is difficult to directly measure the glass temperature of the preform, the temperature of the outer molds 8 and 14 is measured, and the time until the temperature of the glass reaches a predetermined temperature at which the glass can be deformed beyond the glass transition point is obtained. After reaching the time, the temperature is maintained at a predetermined temperature for a predetermined time, and then the servomotor 21 is driven to raise the lower shaft 10. This allows
A predetermined pressure is applied to the preform 22 so that the preform 22 is deformed and the lens molding surfaces 9 of the molds 9 and 13 are formed.
For example, a convex lens of φ33 × t6.6 corresponding to a and 13a is formed. Then, after cooling by increasing the flow rate of N ₂ gas, the molded lens is taken out when the side temperature reaches 200 ° C.

By the way, the time required for molding, the mold 9 and 13, the die plate 6, 12, materials such as the outer mold 8, 14, the material of the preform 22, the lens material and geometry, _{N 2} gas flow rate and, Depending on the molding method, etc., the molds 9 and 13 are made of SiC and die plates 6 and 1.
2. Tungsten alloy, preform 2 for outer dies 8, 14
LLF 6 in 2 (softening point = 637 ° C, transition point = 453 ° C)
At the time of cooling, N ₂ gas was introduced at 100 l / min from the upper shaft 2 side and the lower shaft side 10 respectively, as described in FIG. 1 of Japanese Patent Application Laid-Open No. 63-170227 proposed by the present inventors. Exhaust holes 22 and 23 provided in the hollow heat insulating materials 10 and 11 and exhaust means (communication grooves 20 and 21).
As a result of molding using the infrared lamp 16 as a heating source in a certain configuration, the time required for molding was about 19 minutes. However, the details of the molding method are omitted here,
The cooling time from about 580 ° C to 200 ° C
It took three minutes.

Japanese Unexamined Patent Publication (Kokai) No. 63-170225 discloses a method of equalizing the temperature and improving the cooling efficiency while solving only the problem of high frequency induction heating that only the outer peripheral portion is easily heated due to the skin effect. However, in the case of JP-A-63-170225,
The cooling time from about 580 ° C. to 200 ° C. was about 7 minutes and 30 seconds, and was reduced by about 5 minutes and 30 seconds.
It was 3 minutes and 30 seconds. However, there is a high demand for a reduction in the cycle time, and a further need has arisen. Therefore, as a result of repeated studies and experiments, the structure proposed in the present invention was devised.

That is, according to the present invention, when cooling, the molding surfaces 9a, 13 for molding the optical elements of the molds 9, 13 are formed.
The structure is such that N ₂ gas can be directly introduced into the surface on the side opposite to “a”.

In the case of Japanese Patent Application Laid-Open No. 63-170225, there is a concern that if the cooling is performed steeply, the molded lens may be adversely affected. In order to cool the molds 9 and 13, it has been impossible to efficiently cool the glass having low thermal conductivity and the molds 9 and 13. Hereinafter, a specific description will be given based on the embodiment shown in FIGS.

In FIG. 2 and FIG. 3, the surface of the die plate 12 of the movable mold member 7b, that is, the surface opposite to the surface opposite to the molding surface 13a for molding the optical element of the mold 13, is provided. Eight grooves 30 are formed radially.
Further, as shown in FIG.
Eight through holes 31 communicating with the grooves 30 are formed in an annular direction. The through holes 31 and the grooves 30 constitute guide means for an inert gas, and the gas supply passage 10a is communicated with the inside of the chamber 17 through the through holes 31 and the grooves 30.

As shown in FIG. 1, a die plate is also provided on the fixed mold member 7a similarly to the movable mold member 7b.
6 , that is, a surface opposite to a surface opposite to the molding surface 9 a for molding the optical element of the mold 9, eight grooves 30.
Are formed radially. In addition, the die plate 6
Are provided with eight through holes 31 communicating with the grooves 30 in an annular direction. The through holes 31 and the grooves 30
Constitute an inert gas guide means, and the gas supply passage 2a is communicated with the inside of the chamber 17 through the through holes 31 and the grooves 30.

The N ₂ gas supplied to the gas supply passages 2a, 10a of the upper shaft 2 and the lower shaft 10 is supplied to the hollow joint 4,
11 and through the through holes 31... And the grooves 30... Of the die plates 6 and 12, and flows in direct contact with the surfaces opposite to the molding surfaces 9 a and 13 a for molding the optical elements of the molds 9 and 13. The gas flows into the chamber 17 and the exhaust port 3
3 ... is exhausted out of the chamber. Next, a description will be given with experimental data attached. 4, 5, 9, 10,
FIGS. 12 and 13 show experimental data of the cooling time, in which the horizontal axis represents time and the vertical axis represents temperature.

Further, in FIG. C. 1 is a thermocouple,
The temperature of the mold 13 was measured. C. Numeral 2 indicates the measured data when the temperature of the outer mold 14 is measured and the temperature is controlled to the set temperature.

As a result, FIG. 9 and FIG.
The data using the structure shown in FIG.
About 1 to cool from 550 ° C to 200 ° C
It took two and a half minutes.

On the other hand, FIG. 12 and FIG.
It is data using the structure of FIG. 11 which is close to the structure of JP-A-170225, and it can be seen that cooling from 550 ° C. to 200 ° C. was improved to about 7 minutes and 20 seconds.

Here, the structure close to the structure disclosed in JP-A-63-170225 means that the joint 11 is not provided with a lateral hole, and in FIG.
All of the gas passing through the joint 11 is exhausted through the grooves 32. The result is almost similar to the structure of JP-A-63-170225. A confirmation experiment was also performed. FIGS. 4 and 5 show data of an experimental example of the present invention.
Cooling was achieved in 30 minutes and improved significantly. As a result, the effect of the present invention became clear. Also, it was found that the amount of N ₂ gas used was greatly reduced, and there was also an effect of reducing running costs. The experimental conditions in FIGS. 4, 5, 9, 10, 12, and 13 are as follows: heating N ₂ gas flow rate = 5 l / min from upper and lower axes Cooling N ₂ gas flow rate = upper and lower axes To 100 l /
min shed. Groove size = 0.4 (depth) x 4 (width) mm

The heating temperature is set at 580 ° C.
A sufficient holding time of 12 minutes was set, and the cooling time was compared under a uniform condition such as a time from 550 ° C to 200 ° C. Note that the present invention is not limited to the above embodiment, and may be configured as shown in FIG.

That is, the one shown in FIG. 6 is provided with a plurality of grooves 32 on the surface of the die plate 12 which comes into contact with the hollow joint 11, and the N ₂ gas is supplied from the upper and lower shafts 2, 10 respectively. And a cooling experiment was conducted under the same conditions as described above. However, the effect is greater than that of the conventional example, and it can be said that the present embodiment is significant. Further, the present invention may be as shown in FIGS.

That is, the one shown in FIG. 7 is configured such that N ₂ gas is introduced into the grooves 30... 32 provided on the front and back of the die plate 12 from different paths 35 a and 35 b, respectively. . From the introduction paths 35a and 35b, N ₂
As a result of performing a cooling experiment under the same conditions as described above under a flow of 50 l / min for a total of 100 l / min, 55
It took about 2 minutes and 30 seconds from 0 ° C to 200 ° C. According to this, it was confirmed that the cooling time was further shortened by one minute compared to that shown in FIG. 2 and the effect was large.

As a member constituting the first path 35a, a stainless pipe having an external diameter of 3/8 inch is used, and N ₂ gas is introduced into the groove 30. Further, 36 separator for separating N ₂ gas - are data, a groove 37 with four provided ceramics on the outer periphery, N ₂ gas introduced from the second path 35b flows into the groove 32 I did it. The separator 36 may be formed integrally with the hollow joint 11.

As a result of actual molding under these conditions,
There was no problem due to too fast cooling, and the cycle time was shortened and the cost was reduced by reducing the amount of N ₂ gas used. As a result of actual molding, it was found that the following effects were also obtained.

In the conventional case, when the outer mold and the mold have higher thermal conductivity, the outer mold is cooled first, and then the mold is cooled. Although the cooling of the lens was delayed, it has been found that, according to the present invention, even if the heat conductivity of the mold is low, the molded lens is cooled earlier because it is cooled first. In the experimental example, the description has been given of an example in which a single convex lens is formed. However, the effect is not changed even when a multiple lens or a concave lens is used. Further, there are many inventions having a mold structure different from the mold structure in the above embodiment, but it goes without saying that the present invention is also effective for these inventions.

The point is that it is sufficient that the mold can be cooled by flowing the inert gas directly into the mold having the molding surface for molding the lens, and the mold can be cooled, and is not limited to the surface opposite to the lens molding surface as in the above embodiment. At an appropriate position considering the temperature distribution
Can be provided. Also restricted by the type structure
not. For example, as described in the embodiment,
The present invention can also be applied to a structure called a mold.

[0041]

According to the present invention, as described above, a pair of mold members each including a chamber and a mold provided in the chamber and having a molding surface for molding an optical element are provided.
A shaft member connected to each of the pair of mold members and having an inert gas supply passage therein; and an inert gas supplied from the supply passage of the shaft members directly contacting the mold of the pair of mold members. Since it is provided with an inert gas guide means for flowing and discharging into the chamber, the mold of the mold member can be directly cooled, the cooling efficiency is improved, and the molding cycle can be greatly shortened. In addition, the amount of inert gas used can be reduced, which is economical.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an optical element forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a mold member provided in the molding apparatus of FIG.

FIG. 3 is a transverse sectional view taken along line AA in FIG. 2;

FIG. 4 is an explanatory view showing a temperature drop characteristic of the mold member of FIG. 2;

FIG. 5 is an explanatory diagram showing a temperature drop characteristic of the mold member of FIG. 2;

FIG. 6 is a schematic sectional view showing a mold member according to a first other embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a mold member according to a second other embodiment of the present invention.

FIG. 8 is a transverse sectional view taken along the line BB in FIG. 7;

FIG. 9 is an explanatory diagram showing a temperature drop characteristic of a mold member in the first conventional example.

FIG. 10 is an explanatory diagram showing a temperature drop characteristic of a mold member in the first conventional example.

FIG. 11 is a schematic sectional view showing a mold member according to a second conventional example.

FIG. 12 is an explanatory diagram showing a temperature drop characteristic of a mold member in a second conventional example.

FIG. 13 is an explanatory diagram showing a temperature drop characteristic of a mold member in a second conventional example.

[Explanation of symbols]

17 ... chamber, 9a, 13a ... molding surface, 9, 13 ...
Mold, 7a, 7b ... a pair of mold members, 2a, 10a ...
Inert gas supply path, 2, 10 ... shaft member, 30 ... groove (inert gas guide means), 31 ... through hole (inert gas guide means).

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Tanioka 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Co., Ltd. Numazu Office (56) References JP-A-4-6124 (JP, A) JP-A-63 -170225 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C03B 11/12 C03B 11/08

Claims (2)

(57) [Claims] 1. A chamber, and provided in the chamber.,Molding for molding optical elements
FaceHaving a pair of molds, A pair of die plates that support each mold from behind
And It is connected behind each die plate,
Is the difference in thermal conductivity, emissivity, and / or light transmittance.
The hollow part is formed along the central axis.
A pair of intermediate members formed, Behind each intermediate member Connected to each other,Inert gas inside
Supply pathHaving a pairWith the shaft memberWith The die plate is provided inside the supply path from the supply path.
The through-hole through which the inert gas supplied through the cave passes
And a contact surface with the mold and
On the contact surface with the intermediate member, respectively, the inert gas
Flows into the chamber and is discharged into the chamber.
Is characterized by Optical element molding equipment. 2. A supply from the supply path through the cavity.
The inert gas to be applied to one surface of the die plate.
The plurality of grooves formed, the said formed on the other surface
A distribution means for distributing between a plurality of grooves is provided.
The optical device molding apparatus according to claim 1, wherein: