JPH05186230A - Apparatus for forming optical glass element - Google Patents

Abstract

PURPOSE:To enable the uniform heating of a mold made from not only a metal but also ceramics and the press forming of an optical element with a high accuracy. CONSTITUTION:The objective apparatus is capable of heating a mold and a lens material (15) with infrared rays and equipped with semicircular arc-shaped infrared lamps 30 and 30 and reflecting mirrors 31 and 31 which are formed into an annular shape by respectively mating two pieces thereof and superposed in plural stages. Thereby, uniform heating of the mold is facilitated and the efficiency is high. Accordingly, press forming of an optical element with a high accuracy can be carried out. A large-sized high-frequency oscillator, a bus bar, etc., are not required in the apparatus and miniaturization can be attained. Exchange of an infrared lamp unit 32 is simultaneously simplified. Even if the size or shape of the mold is changed, the infrared lamp unit may be exchanged and this apparatus is capable of readily responding to the diversified small-quantity production.

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, a glass lens,
The present invention relates to a molding device for an optical glass element such as a prism. More specifically, an optical glass element is formed by placing a lens material between a pair of molds, heating the mold and the lens material, and pressing the lens material. The present invention relates to a glass element molding device.

[0002]

2. Description of the Related Art Usually, in a molding apparatus of this type, as a heating means for a mold and a lens material, for example, JP-A-64-64
-45734 and JP-A-63-170228.
The high frequency induction heating (RF induction heating) as shown in Japanese Patent Laid-Open Publication is adopted.

Conventionally, a metal part made of tungsten, molybdenum or the like of a mold is heated by high frequency induction heating, and a cavity die made of ceramics is heated by heat transfer or radiant heat from the metal part, and the lens material is heated by these heats. (Glass material) was being heated.

However, heating by high frequency induction heating has a problem of penetration depth as shown in FIG. 5, and it is difficult to uniformly heat the metal part. Especially, when the diameter is increased, an induction coil is provided on the outer circumference. It is difficult to arrange and heat the object to be heated. Further, in the high frequency induction heating, the cavity material made of ceramics or the lens material which is the work is rarely directly induction-heated.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 62-59539, there is a method in which a mold is heated by infrared rays and the glass material placed in the mold is heated by the heating of the mold.
This is a method in which the mold space in which the glass material is placed is closed by the upper and lower molds and the barrel mold, and the outer periphery of the barrel mold is intensively heated to heat the mold space, thereby heating the glass material. Therefore, there is a drawback that the optical glass element cannot be molded with high precision.

[0006]

As described above, the conventional apparatus cannot directly heat the mold made of ceramics, and the whole mold is not uniformly heated.
There is a problem that it is not possible to mold an optical glass element with high accuracy.

The present invention has been made based on the above circumstances. It is possible to directly heat not only a mold made of metal but also a mold made of ceramics, and moreover, the mold can be heated more uniformly. It is an object of the present invention to provide an optical glass element molding apparatus capable of molding an optical glass element with high precision.

[0008]

The present invention provides an optical glass element for forming an optical glass element by disposing a lens material between a pair of molds and heating the mold and the lens material to press the lens material. In the molding apparatus, each shaft supporting the mold, a heat insulating member provided between the shaft and the mold to make it difficult for heat of the mold to be transferred to the shaft, and an outer peripheral portion of the mold are provided. An infrared lamp unit for heating the mold and the lens material, which includes an infrared lamp and a reflection mirror provided on the back surface of the infrared lamp,
The infrared lamp unit comprises a chamber for forming a molding chamber that can be kept under an inert gas atmosphere between the infrared lamp and the mold, and the infrared lamp unit is provided with a semi-circular infrared lamp and a reflection chamber. A plurality of two mirrors each having a substantially annular shape are stacked and stacked.

[0009]

According to the conventional high-frequency wave, the infrared rays are used as a heating source as described above, and the infrared lamps are formed by stacking a plurality of semi-circular infrared lamps and two reflecting mirrors each having an annular shape. Unlike induction heating, it is possible to heat a die member made of non-metal such as ceramics, it is easy to achieve uniform heating of the die, and efficiency is high. Also, in terms of equipment, a large high-frequency transmitter, a bus bar, etc. are not required, and the size can be reduced. Further, even if the size or shape of the mold is changed, it is sufficient to replace the infrared lamp unit, and it is possible to easily cope with the production of various kinds.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a fixed shaft having a top end side fixed to a ceiling portion of a frame 2 as a first shaft, and a fixed die plate 4 is attached to a lower end of the fixed shaft 1 via a heat insulating member 3. There is.

The heat insulating member 3 is a hollow shaft member 3a made of a heat insulating material such as ceramics such as Si ₃ N ₄ and a ring member 3b made of a transparent heat insulating material such as transparent quartz glass which transmits infrared rays. The fixed die plate 4 is connected by bolts (not shown). And
An upper cavity die 6 made of ceramics or the like is attached to the fixed die plate 4 together with the fixed die 5.

Reference numeral 7 is a moving shaft which is disposed coaxially with the fixed shaft 1 and serves as a second shaft. The upper end of the moving shaft 7 has a hollow shaft member 8a and a ring member 8b as described above.
A moving die plate 9 is attached via a heat insulating member 8 made of
A lower cavity die 11 made of ceramics or the like is attached together with 0.

A preform 15 which is a lens material (glass material) is placed on the lower cavity die 11, and when a predetermined temperature is reached, a system connected to the moving shaft 7 is raised by a hydraulic cylinder 16 which is a driving device. , The fixed die 5 and the movable die 10 are brought into close contact with each other, and the preform 15 is pressed so as to be deformed into the shape of the cavity 17 part constituted by the upper cavity die 6 and the lower cavity die 11, and the optical glass element (this In the embodiment, a convex lens) 15 'is molded.

An upper mold 2 comprising an assembly of the fixed die plate 4, the fixed die 5 and the upper cavity die 6.
0, and a lower die 21 composed of an assembly of the moving die plate 9, the moving die 10, the lower cavity die 11 and the like.
Is in a molding chamber 25 under an inert gas atmosphere surrounded by a cylindrical chamber 24 having both ends closed by a base 22 and a bracket 23.

For example, when forming a convex lens having an outer diameter of 50 mm as the optical glass element 15 ', the outer diameters of the fixed die 5 and the moving die 10 are each 75 mm, and the upper die 20 is used.
And as the chamber 24 surrounding the outer periphery of the lower mold 21,
A quartz tube made of transparent quartz glass having an outer diameter of φ90 and a wall thickness of 4 mm was used.

Further, a plurality of annular infrared lamps 30 serving as heating sources are provided on the outer circumference of the chamber 24 made of a quartz tube.
, And an infrared lamp unit 32 including a reflection mirror 31 formed by polishing aluminum and gold-plated on the back surface of the infrared lamps 30.
Has been placed. By energizing the infrared lamps 30 ..., Infrared rays are transmitted through the chamber 24 to irradiate the upper mold 20 and the lower mold 21.

Fixed die 5 and movable die 10 at this time
Is a tungsten alloy, the moving cavity die 6 and the fixed cavity die 9 are made of SiC, and the glass material is an optical glass having a maximum yielding temperature of about 650 ° C.

The infrared lamp 30 is 200V, max2K
Five W / one W / ten units were used and heated while adjusting the output, and pressed at a display temperature of the thermocouple 35 of about 640 ° C. The press pressure was 1200 kgf by the press force of the hydraulic cylinder 16, and as a result, a good optical glass element (lens) 15 'was obtained. In the embodiment, the infrared lamp 30 is bent in a semicircular shape as shown in FIG. 2, and the two infrared lamps 30 are arranged in a substantially circular shape. In FIG. 2, reference numeral 36 is a lamp terminal, and 37 is an insulator.

As shown in FIG. 1, on the outside of the infrared lamp unit 32, there is provided a cooling unit 39 in which water cooling pipes 38 are arranged on the back surface of the reflection mirrors 31. It is designed to prevent damage from overheating. The cooling unit 39 is attached as needed.

The infrared lamp 30 is a halogen lamp using a coiled filament of tungsten and has a wide wavelength range, but is generally an infrared lamp having a peak wavelength range of 1.2 μm to 1.8 μm. ..

This wavelength is [transmittance of T-1030 transparent quartz glass] shown in FIG. 3 (from Toshiba Ceramics Co., Ltd. catalog) and [transmittance of T-2030 transparent quartz glass] shown in FIG. 4 (Toshiba Ceramics Co., Ltd.). (From the company catalog), the chamber 24 made of a transparent quartz tube and the ring members 3b, 8b for heat insulation made of transparent quartz are set to 90.
Permeate more than%.

By forming the infrared lamps 30 and 30 into a substantially circular shape as described above, the reflection mirror 31 is formed.
Combined with the effect of ..., The upper die 2 composed of an assembly of the fixed die plate 4, the fixed die 5, and the upper cavity die 6.
It has been found that the lower die 21, which is an assembly of 0 and the moving die plate 9, the moving die 10, and the lower cavity die 11, can be efficiently heated and more uniformly heated.

Although there are some differences depending on the glass material, generally, optical glass almost transmits infrared rays of 1.2 μm to 1.8 μm, so that the preform 15 should be substantially heated directly by the infrared lamps 30. Not indirectly, but indirectly heated.

On the other hand, in the molding chamber 25, arrows A, B,
As indicated by C, N ₂ gas which is an inert gas is introduced and exhausted as indicated by arrow D, and the heating is performed after the oxygen concentration in the molding chamber 25 is reduced to a concentration that does not affect the quality of the glass. It has become. The gas supply pipe and the gas exhaust pipe are omitted in the figure.

A chamber 24 including an infrared lamp unit 32, a cooling unit 39, and a transparent quartz tube.
Are integrally assembled with the bracket 23, and these can be integrally moved upward by an air cylinder as a driving device (not shown) so that the molding chamber 25 can be opened if necessary. Is becoming

Then, the lower cavity die 11 of the lower mold 21.
The preform 15 and the pressed optical glass element (lens) 15 'can be easily taken out.

Then, the preform 15 which is a lens material (glass material) is placed on the lower cavity die 11, and when the temperature reaches a predetermined temperature, the hydraulic cylinder 16 which is a driving device.
Is operated to raise the lower mold 21, the movable die 10 is brought into close contact with the fixed die 5, and an optical glass element 15 'such as a glass lens corresponding to the shape of the cavity 17 is press-molded.

At this time, the mating surface accuracy of the fixed die 5 and the movable die 10 and its reproducibility are high, the combined accuracy of the fixed die 5 and the upper cavity die 6 and the combined accuracy of the movable die 10 and the lower cavity die 11 are high, The upper and lower cavity dies 6 and 11 have excellent lens shape accuracy, surface accuracy, etc., and by obtaining an appropriate heating state as described above, the high-precision optical glass element (lens) 15 'uses a polishing process. It will be obtained without any trouble.

As a heating means for heating the preform 15 and the like to a predetermined temperature, the fixed die plate 4, the fixed die 5, the movable die plate 9 and the movable die 10 are induction-heated by high frequency induction heating (RF induction heating). However, it is possible to indirectly heat the upper cavity die 6, the lower cavity die 11 and the preform 15 by heat conduction or radiation from the member heated by induction heating. However, as a problem of high frequency induction heating, as shown in FIG. As shown in FIG. 3, there is a problem of penetration depth (see Japanese Patent Laid-Open No. 63-170225), and as the outer diameter of the cavity die 6, 11 increases, the die 5, 1
When the diameter of 0 becomes large, it becomes difficult to make the temperature uniform, and it becomes difficult to perform press molding under favorable conditions. In addition, since the cavity dies 6 and 11 are made of ceramics, they cannot generally be subjected to high frequency induction heating, and thus have poor thermal efficiency. Therefore, the present invention adopts the infrared heating method as described above in order to solve the above problems.

There are many types of optical glass materials used as the preform 15, and the physical properties such as the refractive index are selected according to the purpose of use, but since the glass transition point, yield point, etc. change, the infrared lamp 30 The output of and the required number also change. Therefore, output control and infrared lamp unit 32
It is good to adjust it by replacing.

Further, it is necessary to change the size of the infrared lamp unit 32 or replace the molds 20 and 21 depending on the glass material and the sizes and shapes of lenses and prisms to be molded. Therefore, in this embodiment, the infrared lamp 3
0, the reflection mirror 31 and the like are unitized so that they can be easily replaced. When the high frequency induction heating system is used as in the conventional case, there is a matching problem when the high frequency induction coil is replaced.

Although SiC is used for the cavity dies 6 and 11 in the above-mentioned embodiment, TiC, Si ₃ N ₄ ,
Ceramics such as TiN, or the surface of these ceramics may be further coated with other ceramics or noble metal, and the die plates 4 and 9 may be ceramics unlike the case of the high frequency induction heating method (RF). Of course, it can be arranged. In addition, it goes without saying that the present invention can be variously modified and implemented within the scope of the invention.

[0034]

As described above, according to the apparatus for molding an optical glass element of the present invention, infrared rays are used as a heating source and two semi-circular infrared lamps and two reflecting mirrors are combined into a substantially annular shape. By using an infrared lamp unit formed by stacking a plurality of stages, it is easy to uniformly heat the mold and the efficiency is high. Therefore, it is possible to press-mold an optical glass element with high accuracy. Also, in terms of the apparatus, a large high-frequency transmitter, a bus bar, etc. are not required, so that the size can be reduced and the infrared lamp unit can be easily replaced. Further, even if the size or shape of the mold is changed, it is sufficient to replace the infrared lamp unit, and it is possible to easily cope with the production of various kinds.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the overall configuration of an embodiment of a molding apparatus of the present invention.

FIG. 2 is a schematic cross-sectional plan view of an infrared lamp unit.

FIG. 3 is a diagram showing an infrared transmittance of transparent quartz glass.

FIG. 4 is a diagram showing infrared transmittance of a transparent quartz glass of a type different from that of FIG.

FIG. 5 is an explanatory diagram showing the relationship between distance and temperature in high frequency induction heating.

[Explanation of symbols]

1 ... 1st axis (fixed axis), 7 ... 2nd axis (moving axis), 3
... Heat insulating member, 3a ... Hollow shaft member, 3b ... Ring member, 8
... Heat insulating member, 8a ... Hollow shaft member, 8b ... Ring member, 1
5 ... Preform (lens material), 15 '... Optical glass element (lens), 20 ... Mold (upper mold), 21 ... Mold (lower mold), 24 ... Chamber, 25 ... Molding chamber, 30 ... Infrared lamp, 31 ... Reflecting mirror, 32 ... Infrared lamp unit.

Claims (1)

[Claims] 1. An optical glass element molding apparatus for molding an optical glass element by disposing a lens material between a pair of molds and heating the mold and the lens material to press the lens material. Each supporting shaft, a heat insulating member provided between the shaft and the mold to prevent heat of the mold from being easily transferred to the shaft, an infrared lamp provided on the outer periphery of the mold, and a rear surface of the infrared lamp. And an infrared lamp unit for heating the mold and lens material, and a molding chamber that can be kept in an inert gas atmosphere between the infrared lamp and the mold of the infrared lamp unit. And a chamber for operating the infrared lamp unit, wherein the infrared lamp unit is formed into a substantially annular shape by combining two semi-circular infrared lamps and two reflecting mirrors. A molding apparatus for an optical glass element, characterized in that a plurality of layers are laminated.