JPH01148716A - Die for forming optical element - Google Patents

Abstract

PURPOSE:To obtain an optical element having high precision inexpensively by forming a die with plural concentric die members dividedly in the stage of press-forming a glass raw material softened by heating, and providing a means for setting a forming pressure and forming temp. of the divided die member independently to each other. CONSTITUTION:A die for producing an optical element, etc., by press-forming a glass raw material softened by heating is constituted of a die 1 having a forming surface 1a for forming a desired lens surface and a pressing die 3 arranged facing oppositely to the die 1 and constituted of plural die members 2 divided concentrically. Further, means for setting a forming pressure and a forming temp. independently to each of the plural die members 2 are provided. By this constitution, reversibility of the shape of a forming surface 1a of a die 1 is improved even, for example, for a glass lens having a large difference of thickness and a large asphericity on one surface, and an optical element, etc., can be press-formed in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mold for molding an optical element, which heats and softens a glass material and molds it under pressure.

[Conventional technology]

Conventionally, as a mold for press-molding an optical element by heating and softening a glass material, for example, Japanese Patent Publication No. 62-45173
There is a mold disclosed in the publication.

The above-mentioned molding die is slidably fitted into the cylindrical body mold, and the optically effective area surface of the lens is continuously formed by the lower inner peripheral edge of the body mold and the molding surface shown in the arrow direction. The upper mold is formed by forming.

[Problem that the invention seeks to solve]

However, in conventional molding molds, the body mold and the arrow view are locked, making it impossible to apply pressure to the glass material partially, and the glass material cannot be pressed under conditions of a constant pressure and a constant temperature. Because glass lenses are molded by pressure molding, there is a large amount of glass flow, and there is a large difference in temperature distribution inside the glass.For example, when molding a glass lens that has a large amount of aspherical surface on one side, it is necessary to It was difficult to accurately reverse the shape of the mold or to press-mold glass lenses in a short time. In other words, if the press-forming was completed in a short time, the glass would be cooled with a temperature distribution inside, causing the meat to deteriorate. The problem is that thin parts solidify first, and no more pressure can be applied to thick parts that can be press-molded due to high temperatures, making it impossible to press-form them into the desired shape due to the difference in the internal shrinkage rate of the glass. There was a point.

On the other hand, by holding the glass in a high-temperature mold until the internal temperature of the glass becomes uniform, the shape error due to the difference in the shrinkage rate inside the glass can be reduced and the desired glass lens can be press-molded, but the molding time will be longer. There were problems in that productivity decreased and costs increased.

Therefore, the present invention has been made in view of the above-mentioned problems, and is particularly directed to a molding tool for optical elements that can mold a desired lens surface even if the optical element has a large amount of aspherical surface on one side. The purpose is to provide a type.

[Means for solving problems]

As shown in FIG. 1, the mold for molding an optical element of the present invention includes a mold 1 having a molding surface 1a forming a desired lens surface, and a mold 1 that is placed opposite to the mold 1 and is concentric with the mold 1. The press mold 3 is composed of mold members 2 divided into shapes, and each of the mold members 2 is configured to be able to independently control temperature and pressure.

[Effect]

According to the above configuration, when press molding a glass material, each divided mold member 2 of the pressing mold 3 presses the glass material independently, and the shape of the molding surface 1a of the mold 1 is suitable for the glass material. The lens material 4 is then molded. FIG. 1 shows the molded lens material 4, in which a lens surface 4a to which the molding surface 1a of the mold 1 is accurately transferred is formed;
By polishing the pressing surface 4b formed by the pressing mold into a desired shape, a desired glass lens 5 shown in FIG. 1 can be obtained.

〔Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Example) FIG. 3 is a sectional view showing a first example of a mold for molding an optical element according to the present invention.

In the figure, 10 indicates a molding die, and this molding die 10 has a molding surface 11a for press-molding a desired lens surface.
A press having a pressing surface 13a which is arranged on the axis of the mold 11 to face the mold 11 so as to be able to approach and move away from the mold 11, and which presses the glass preform 12 against the molding surface 11a. It is composed of a mold 13.

The mold 11 is formed of a 13 chromium stainless steel member or other carbide member, and has a molding surface 11a.
is formed into an aspherical shape with a surface roughness of 0.02 μm (R
max) or less and is coated with a film of chromium nitride, titanium nitride, boron nitride, or the like. Furthermore, the mold 11 is equipped with a heater (not shown) that heats the mold to a desired temperature, and in this embodiment, the viscosity of the glass preform 12 corresponds to lo".5 to 101'.5 poise. It is designed to maintain the temperature.

The pressing mold 13 is divided into an outer mold 14 and an inner mold 15. The outer mold 14 has a cylindrical recess 16 formed in the center thereof, and a heater 18 is provided in the outer peripheral part 17 so as to be able to set the temperature to a desired temperature. Further, the outer mold 14 is connected to a pressure means (not shown), and is held movably in the vertical direction in the figure so as to be able to press the glass preform 12 with a predetermined pressure.

The inner mold 15 is slidably fitted into the cylindrical recess 16. This inner mold 15 is provided with a heater 19 inside, and a lower end 15a of the inner mold 15 and a cylindrical recess 1.
An elastic member 20 is provided between the bottom portions 16a of the glass preform 12, and the temperature is controlled separately from the outer mold 14 by the heater 19 and the elastic member 20, so that the glass preform 12 can be pressed. In addition, in this example,
Outer mold 14. The temperature of the inner mold 15 can be set by heaters 18 and 19 to a temperature corresponding to the viscosity of the glass preform 12 from 10'4·S to 107 poise.

The pressing die 13 having the above configuration has a pressing surface 14b that presses the glass preform 12 on the upper end surface 13a.

15b is formed, and these pressing surfaces 14b and 15b push the glass preform 12 onto the molding surface 11a of the mold 11.
to change the shape of the molding surface 11a to the glass preform 1.
Since the pressing surfaces 14b and 15b which are transferred to the lens surface 13 are not required to have the shape accuracy and surface roughness required to form a lens surface, the pressing mold 13, that is, the outer mold 14 and the inner mold 15 are made of 13 chromium-based stainless steel material, carbide. It can be formed from many suitable materials such as members and other ceramic members.

In the figure, reference numeral 23 denotes a transfer plate that holds the glass preform 12 and the glass lens after pressing is completed. 12 between the mold 11 and the pressing mold 13, and after the pressing is completed, the lens is transferred to the next process.

In addition, in the molding die 10 of this embodiment, only one side of the lens, that is, the molding surface 11a of the mold 11, is transferred and formed, so the glass preform 12 has a thickness that is equal to the thickness of the lens to be manufactured. They do not need to be of the same extent, and in order to slow down the cooling rate of the glass material, a parallel plate shape is used, which is about 1.5 times the maximum thickness of the lens to be manufactured and is easy to manufacture.

Next, a process of molding an optical element using the molding die described above will be explained.

First, a glass preform 12 heated and softened so as to be press moldable is held on a conveyance tray 23 and transferred to a mold 11 via a conveyance arm. Transfer between pressing molds 13.

Next, the mold 11 is moved down and the press mold 13 is moved up to remove the glass preform 12 held on the transfer plate 23.
is lifted from the transfer tray 23, and as shown in FIG. Transfer to renovation. After the molding of the lens material 25 as shown in FIG.
3 to hold the lens material 25 on the conveying tray 23. The glass material 25 is then transferred via a transfer arm, subjected to a cooling process, and then taken out. Lens material 2
5, as shown in FIG. 3a, only one side is the molding surface 11.
It is formed on an optically usable lens surface 25a which is an inverted version of a, and then one surface 2 of this lens material 25 is formed.
Lens surface 2 having desired optical performance by polishing 5b
5c, a glass lens 26 having a spherical surface on one side and an aspherical surface on one side as shown in FIG. 3 can be obtained.

In the molding die 10 having the above configuration, when the glass preform 12 is held under pressure by the mold 11 and the press die 13, the glass preform 12 is held at the peripheral portion 12 near the outside air.
Since it is cooled from a to the center part 12b, the peripheral part 12a
There is a state in which the central portion 12b is solidified and the center portion 12b is not solidified and can be molded. In such a case, first, the shape of the molding surface 11a is transferred to the peripheral part 12a under the pressure of the outer mold 14 and solidified,
After that, the center part 12b is separated from the inner mold 15 from the peripheral part 12a.
As a result, pressure is applied by the elastic force of the elastic member 20, and the shape of the molding surface 11a is transferred well and solidified.

Therefore, according to this embodiment, the pressing mold is divided into an outer mold and an inner mold so that the temperature can be set independently and the pressure can be applied to the peripheral part and the central part of the glass preform.
Due to the difference in solidification speed between the periphery and the center of the glass preform, the area where solidification progressed first received all the pressure from the pressing die, and the pressure was no longer applied to the area where the solidification rate was slow. This problem has been resolved, and the shape of the molding surface of the mold can be reversed with high precision, even if the lens surface has a large aspherical surface on one side.

Next, a fourth example of a molding apparatus will be constructed using the mold of this example.
The outline of the molding apparatus will be explained below.

In the figure, 30 is a molding device, and this molding device 30 has a molding chamber 31 for press-molding the glass preform 12, transferring the glass preform 12 between molding molds, and recovering the press-molded lens material 25. It is composed of a transfer chamber 32 and a heating chamber 33 provided between the molding chamber 31 and the transfer chamber 32.

In the molding chamber 3I, the mold 11 and the press mold 13 are disposed facing each other on the same axis. The mold 11 is an air cylinder 3
4 and is held so that it can move up and down. 35a is a mold release member, and 35b is a heater for heating the mold 11.

The pressing die 13 has a push-up shaft 36a connected to the drive section 36.
It is attached to and held so that it can move up and down. In addition,
37 is a pipe connected to a vacuum pump (not shown);
This is a pipe for injecting inert gas into the molding chamber 31.

In the transfer chamber 32, a supply section 39 for the glass preform 12 is provided.
and a collection unit 40 that collects the lens material 25 that has been press-molded.
are provided so that they can be attached and detached. A plurality of glass preforms 12 are stored in the supply section 39 while being held by the transport tray 23, and a supply shaft 41 provided at a position facing the supply section 39 moves upward to feed the glass preforms on the upper surface of the supply shaft 41. The glass preform 12 is held together with the transfer plate 23, and in this state, the supply shaft 41 is moved down to transfer the glass preform 12 and the transfer plate 23 to the transfer arm 42.

43 is an actuator for vertically moving the supply shaft 41.

The collection unit 40 collects and stores a plurality of lens materials 25 while being held on the transport tray 23. A collection shaft 44 provided at a position facing the collection unit 40 is moved upward to move the lens material 25 to the transport arm 42.
The lens material 25 held in the transport tray 23 is transferred to the collection unit 40.
The uke is supposed to be passed by pushing it up. 45 is an actuator for vertically moving the collection shaft 44.

The transfer arm 42 is provided on a transfer machine 47 that reciprocates by a drive device (not shown), and is located at the supply position of the supply section 39, inside the heating chamber 33, between the forming die 11 and the suppression die 13, and at the recovery position of the recovery section 40. It is designed to be able to move and stop. In addition, in the figure, 46 is an O-ring for sealing the molding chamber 31 and the transfer chamber 32.

Next, when press-molding the lens material 25 using the above-mentioned molding device, first the transport arm 42 is moved to the glass preform 12.
The preform 12 is moved to the supply position and stopped, and the preform 12 is placed on the mounting portion of the transport arm 42 while being held on the transport tray 23 via the supply shaft 41. Next, the transport arm 42 is moved to transport the preform 12 into the heating chamber 33, where it is heated and softened to a predetermined temperature. After that, the transfer arm 4
The preform 12 heated and softened by moving the preform 12 is placed between the mold 11 and the press mold 13, and the lens material 25 is press-molded in the same manner as the above process, and the lens material 25 is placed on the transport arm 42. Then, the lens material 25 is moved to the collection position of the collection section 40 by moving the transport arm 42, and the lens material 25 is stored together with the transport tray 23 via the collection shaft 44.

Then, the transport arm 42 is positioned in the supply section 39, and the molding device 30 is operated in the same manner as described above to continuously press mold the lens material.

(Second Embodiment) FIG. 5 shows a second embodiment of a mold for molding an optical element according to the present invention, and is a sectional view of the pressing mold.

The pressing mold 50 of this embodiment has an outer peripheral mold 51. It is divided into a middle mold 52 and a central mold 53.

The outer peripheral mold 51 has a cylindrical recess 55 formed in the center thereof, and a coil heater 56 is provided in the outer peripheral part 51a so that a desired temperature can be set. A medium mold 52 is slidably fitted into the cylindrical recess 55 and held by an elastic member 57 provided between the bottom 55a of the cylindrical recess 55 and the lower end 52a of the medium 52.

The middle mold 52 has a central mold 53 in the center like the outer peripheral mold 51.
A fitting recess 58 is formed, and a coil heater 59 is installed inside.
is provided.

The center mold 53 is slidably fitted into the recess 58 and held by an elastic member 60 in the same manner as described above, and a cartridge type heater 61 is provided inside. In the figure, 6
2 and 63 are power supply holes for the heaters 59 and 61 formed in the outer mold 51 and the middle mold 52.

The winter molds 51, 52 and 53 have a pressing surface 51a on the upper end surface.
, 52a and 53a are formed, and this pressing surface 51a,
52a and 53a press the glass preform against the molding surface of a mold (not shown) to form a lens material with an inverted molding surface shape. During such molding, the temperatures of the winter molds 51, 52 and 53 are controlled by heaters 56 and 59, 61, respectively, and the temperatures of the winter molds 51, 52 and 53 are controlled by the middle mold 52 and the center mold 5.
3 is an outer peripheral mold 51 by elastic members 57 and 60, respectively.
The glass preform is configured to be able to be pressed separately from the glass preform. The rest of the configuration is the same as that of the first embodiment, so the explanation thereof will be omitted. Furthermore, since the process for molding the lens material and the glass lens is the same, the explanation thereof will be omitted.

According to this embodiment, the same functions and effects as those of the first embodiment are achieved, and since the pressing mold is divided into three parts, the shape of the molding surface of the molding mold can be adjusted with higher precision to form the glass preform. can be reversed.

〔Effect of the invention〕

According to the present invention, it is possible to press the glass preform by independently setting pressure and temperature using a press mold that is divided into molding surfaces. Even in the case of a glass lens having a large amount of aspherical surface on one side, the reversibility of the shape of the molding surface of the molding die is improved, and an optical element can be press-molded in a short time. Therefore, it is possible to obtain an optical element with high precision and low cost.

[Brief explanation of the drawing]

FIG. 1a is a conceptual diagram showing a mold for molding an optical element according to the present invention. FIG. 1 is a front view of the lens material molded by the mold, FIG. 1C is a front view of an optical element obtained by post-processing the lens material, and FIG. 2 is a first embodiment of the present invention. FIG. 2a is a cross-sectional view showing the state before press molding, FIG. 2 is a cross-sectional view during press molding, and FIG. 3 is a front view of an optical element obtained by post-processing the lens material, FIG. 4 is a cross-sectional explanatory view showing an example of a molding apparatus using the molding die, and FIG. FIG. 3 is a cross-sectional view of a pressing die according to a second embodiment of the present invention. 1...Molding die 2...Divided die 3...Press die 10...Molding die 11...Molding die 12...Glass preform 13.50...Press die 14...・Outer mold 15...Inner mold 18.19, 50.59.61...Heater 20.57
．． 60...Elastic member 51...Peripheral type 52...Medium type 53...Central type Patent applicant Olympus Optical Industry Co., Ltd. Agent Patent attorney Takeshi Nara, "1-2 \" Figure 4 Showa Mr. Kunio Ogawa, Commissioner of the Haji Patent Office in February 19631, Indication of the case, 1988 Patent Application No. 3065092, Name of the invention, Mold for molding optical elements 3, Person making the amendment Relationship to the case Patent applicant address: 2-43-2 Hatagaya, Shibuya-ku, Tokyo Name:
(037) Representative of Olympus Optical Industry Co., Ltd.
Satoshi Yama, Department 4, Agent 105 Address: 2-2-15-6 Hamamatsucho, Minato-ku, Tokyo Subject of amendment (+) "Detailed description of the invention" column 7 of the specification, Contents of amendment

Claims (1)

[Claims] (1) In a mold for press-molding a glass material by heating and softening, one mold is divided concentrically into at least two or more mold members, and each of the divided mold members is independent. 1. A mold for molding an optical element, comprising means for setting molding pressure and molding temperature.