JPH07118023A - Method and device for forming glass optical element - Google Patents

Abstract

PURPOSE:To improve productivity and to greatly improve the working rate of a forming machine by shortening dropping intervals of fused glass. CONSTITUTION:A high-frequency heating coil 2 exists in the outer peripheral part of an annular member 1 consisting of a material having low reactivity with the fused glass. The annular member 1 and the high-frequency heating coil 2 are mounted at a heat insulating member 3. The bottom end of a glass rod 4 freely liftably held exists in the aperture 1a of the annular member 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method and an apparatus for obtaining a glass optical element by dropping molten glass into a molding die for molding.

[0002]

2. Description of the Related Art Conventionally, as a method of dropping molten glass for molding, there is, for example, the invention described in Japanese Patent Publication No. 4-16414. The above invention is a step of dropping a molten glass drop from a nozzle tip provided at the bottom of the melting crucible to make the surface temperature of the molten glass drop lower than the softening temperature of the glass and an internal temperature higher than the softening temperature, and dropping. And a step of receiving the formed glass drops with a first mirror surface mold, and a step of press-molding the glass drops with the first mirror surface mold and the second mirror surface mold to obtain a glass lens. A method and a manufacturing apparatus thereof.

[0003]

However, the above-mentioned prior art has a structure in which molten glass is dripped from a nozzle provided at the bottom of the melting crucible, and has the following drawbacks. That is, when obtaining a certain amount of molten glass droplets, the interval at which the molten glass is dropped from the nozzle depends on the balance between the self-weight of the molten glass in the melting crucible and the viscous resistance (that is, the self-weight moving speed of the molten glass in the melting crucible). Almost decided.

In order to shorten this interval and improve productivity, it is conceivable to periodically control the balance by periodically controlling the temperature of the molten glass. However, it is difficult to precisely and periodically control the temperature of the molten glass in the vicinity of the nozzle so as to shorten the interval of the dropping while keeping the dropping amount of the molten glass constant.

Even if the molten glass is sent to the nozzle side by some means from the molten crucible side, the viscous resistance of a large amount of the molten glass in the melting crucible causes the molten glass to move accurately and instantaneously in the vicinity of the nozzle. It is difficult to control. Furthermore, since the heating time of the glass in the melting crucible required until the dropping can be started, the operating rate of the molding machine is inevitably lowered.

Therefore, the present invention has been made in view of the above-mentioned drawbacks in the prior art, and it is possible to shorten the dropping interval of the molten glass to improve the productivity and to significantly increase the operating rate of the molding machine. An object of the present invention is to provide a glass optical element molding method and apparatus that can be improved.

[0007]

The present invention is a method for molding a glass optical element in which a glass material is heated and melted and then a predetermined amount of molten glass is supplied to a molding die. It is a molding method including a step of supplying a material in an amount not less than a dropping amount within a desired dropping time to heat and melt, and a step of dropping molten glass from a ring-shaped high-temperature member and supplying the molten glass to a molding die. Further, a ring-shaped member for melting the glass material, and heating means provided on the ring-shaped member,
A molding apparatus having a supply means for supplying a predetermined amount of a glass material to the ring-shaped member at a desired supply rate, and a mold for pressing molten glass dropped from the ring-shaped member.

[0008]

When a drop of solid glass material is supplied to the inner surface of the ring-shaped high-temperature member and heated and melted, the glass material melts and adheres to the inner surface of the ring-shaped high-temperature member while gradually forming molten glass droplets. The molten glass droplets are formed by a balance between the weight of the molten glass below the ring-shaped high-temperature member and the surface tension of the molten glass near the ring-shaped high-temperature member.

Accordingly, the molten glass is dripped by further supplying a predetermined amount of the solid glass material so that the weight of the molten glass below the ring-shaped high temperature member exceeds the surface tension of the molten glass. The timing of can be controlled freely. Further, since the solid glass material is supplied in a dropping amount in accordance with the dropping of the molten glass without using the melting crucible, the setup time before the start of molding is not required, and the operating rate of the molding machine is improved.

[0010]

Embodiment 1 FIGS. 1 to 3 show an apparatus used in this embodiment, FIG. 1 is a schematic configuration diagram, and FIGS. 2 and 3 are sectional views showing a molding process. Reference numeral 1 is a ring-shaped member made of a material having conductivity and low reactivity with molten glass, such as platinum, gold and carbon. A high frequency heating coil 2 is located on the outer peripheral portion of the ring-shaped member 1 so that the ring-shaped member 1 can be heated to a temperature above the melting temperature of glass by a control power supply device (not shown).

Ring-shaped member 1 and high-frequency heating coil 2
Is attached to the heat insulating member 3, and the heat insulating member 3 is fixed to a molding machine base (not shown). Further, the heat insulating member 3 also has a function of a heat insulating cover of the ring-shaped member 1 having a high temperature. 4 is a glass rod made of glass to be melted. The upper end of the glass rod 4 is attached to the chuck portion 5 a of the elevating mechanism 5.

The elevating mechanism 5 controls the chuck portion 5a, the elevating member 5b, a slide base 5c that holds the elevating member 5b so that the elevating operation is possible, and a drive source (not shown) for the elevating operation and the operation of the drive source. And a control device that operates. A slide base 5c is fixed to the molding machine base so that the glass rod 4 can be moved up and down substantially vertically and the lower end of the glass rod 4 is located in the opening 1a of the ring-shaped member 1. 6 is located above the opening 1a of the ring-shaped member 1, and the lower end of the glass rod 4 is located at the opening 1a.
It is a roller for leading to.

At the lower position of the ring-shaped member 1, a cylindrical sleeve 7 is formed which is long in the lateral direction (left-right direction in FIG. 1).
Is provided. An input port 7a for the molten dropping glass 8 is provided at the center of the sleeve 7. The insertion port 7a is arranged directly below the opening 1a of the ring-shaped member 1. Further, the inner diameter of the sleeve 7 is configured to be equal to the outer diameter value of the desired molded product to be molded.

Inside the sleeve 7, a pair of molding dies 9, 10 molded of a heat resistant material such as SiC or cemented carbide is slidably fitted and mounted in the sleeve 7. The respective molding surfaces 9a, 10a of the pair of molding dies 9, 10 are mirror-finished and formed, and chromium nitride (CrN) or boron nitride (B) for preventing fusion with molten glass is formed on the surfaces.
N) and the like nitride coating is applied. The inner peripheral surface 7b of the sleeve 7 is slidable by disposing the respective molding surfaces 9a and 10a so as to face each other.

The inner peripheral surface 7b of the sleeve 7 is also coated with the same nitride coating as the molding surfaces 9a and 10a of the molding dies 9 and 10. The clearance due to the fitting of the sleeve 7 and the molding dies 9 and 10 and the lengths (horizontal direction) of the respective fitting portions of the molding dies 9 and 10 are such that the inclination of the molding surfaces in the molded product to be molded is a desired value. It is configured to be.

A pressing plate 11 is mounted on one (right) end surface of the sleeve 7, and a hole 11 is formed in the center thereof.
a is provided. Although not shown, a retractable press rod 12 having a base end portion connected to a driving device is disposed in the hole 11a, and a front end portion of the press rod 12 serves as a central rear end surface of the molding die 10. It is configured to be connected and slide on the inner peripheral surface 7b of the sleeve 7.

Although not shown, inside the other (left side) of the sleeve 7, its base end is attached to a driving device, for example, an air cylinder, and its tip is attached to the center of the rear end surface of the molding die 9. The press rod 14 attached to the mold is disposed so that the mold 9 can slide on the inner peripheral surface 7b of the sleeve 7. That is, the pair of molding dies 9 and 10 are configured to transfer the dropped glass 8 and pressurize the dropped glass 8 by the press rods 12 and 14.

On the lower left peripheral wall surface of the sleeve 7, there is formed a take-out hole 7f for taking out the formed glass molded product 15 to the outside. Further, on the outer peripheral surface of the sleeve 7, a heater 13 that freely controls the temperatures of the sleeve 7 and the molding dies 9, 10 and the dropped glass 8 is wound. Although not shown in the figure, the molding apparatus having the above-described structure is configured so as to have an N ₂ atmosphere by the N ₂ supply apparatus, although it is not shown in the figure.

A molding method using the apparatus having the above structure will be described below. In this embodiment, Lak7 (transition temperature 617) of lanthanum optical glass is used as the glass material.
C., softening point temperature 694.degree. C., specific gravity 3.73). The inner diameter of the opening 1a of the ring-shaped member 1 was set to 5 mm. The inner diameter of the opening 1a is determined from the weight of the dropped glass, and the inner diameter is set to increase as the weight increases. In the present embodiment, it is set so that a dropping weight of 0.3 g can be dropped.

The ring-shaped member 1 is heated by the high-frequency heating coil 2 and its control power supply device so that at least the glass has a glass viscosity of 10 ⁵ poise or less at which the glass can be dropped by its own weight, and preferably the glass viscosity is 10 ³ poise or less. Temperature, and the dropping becomes easy. In this embodiment, the temperature is 1000 ° C., which gives a glass viscosity of 10 ² poise. It should be noted that the glass material having an outer diameter larger than the inner diameter of the opening 1a is placed on the upper end of the opening 1a so that the glass material is preliminarily attached and filled in the opening 1a, and then the ring-shaped member is heated. The residual glass is melted and dropped from the opening 1a, and the residual glass is attached to the inside of the opening.

The glass rod 4 having an outer diameter of 3 mm, which is smaller than the opening 1a of the ring-shaped member 1, is chucked to the chuck portion 5a of the elevating mechanism 5, and the lower end of the glass rod 4 is attached to the attached glass in the opening 1a. Contact. The lower end of the glass rod 4 is gradually heated and melted by heat conduction from the adhered glass, but at least the weight of the glass rod 4 is dropped within a desired dropping time.
Lower by a length corresponding to 3 g. In this case, the descending amount of the glass rod is 1.15 mm or more. As the glass rod 4 descends, the amount of molten glass in the opening 1a increases, the molten glass moves downward correspondingly, and the weight of the molten glass located below the opening lower end 1b can be increased.

The molten glass droplets are formed by the balance between the weight of the molten glass below the lower end 1b of the opening and the surface tension of the molten glass near the lower end 1b of the opening.
Therefore, it becomes possible to supply the solid glass material so that the self-weight of the molten glass below the lower end 1b of the opening exceeds the surface tension of the molten glass within the desired dropping time. It is possible to cause the dropping of molten glass. In this way, if the descending speed of the glass rod 4 is set so that more than the dropping weight of the glass is supplied into the ring-shaped member within the desired dropping time, the timing of dropping the glass can be freely controlled. As described above, the dropping glass 8 having a constant weight is dropped from the ring-shaped member 1 and supplied between the molding dies 9 and 10.

Next, as shown in FIG. 2, the press rod 14 mounted on the rear end of the forming die 9 is driven to move the dropping glass 8 and the forming dies 9 and 10 to the right respectively, so that the dropping glass 8 is moved. Is pressed into a desired molded product 15. In addition, the molding dies 9, 1 at the time of supplying the dripping glass 8
The temperature of 0 is preferably maintained in a relatively low temperature region below the glass transition temperature in order to prevent fusion with glass. The pressure molding conditions are, for example, the temperature of the glass deformation point (viscosity 10 ^10.5 poise) by controlling the heater 13, the pressure is 20 kg / cm ² , and the temperature is maintained until the molding is completed. Cool the product to near the slow cooling temperature. Thereafter, the gradually cooled molded product 15 is taken out by the press rods 12 and 14 as shown in FIG.
It is moved to f and taken out of the sleeve 7 to complete the molding process.

According to the present embodiment, a plurality of molding portions including the sleeve 7 and the pair of molding dies 9 and 10 are prepared and are sequentially supplied in accordance with the dropping timing of the dropping glass from the ring-shaped member 1. By doing so, an efficient molding line with a short production takt time can be constructed. Furthermore, since the glass can be dropped by heating only a small amount of glass material corresponding to the weight of the molded product, the time until the start of molding is extremely short and the operating rate of the molding machine can be improved.

The following may be considered as modifications of this embodiment. It is conceivable to provide a cooling mechanism on the outer periphery of the lower end of the glass rod 4 slightly above the melting part to heat and melt only the lower end to prevent deformation of the lower part of the glass rod 4. As a result, it is possible to prevent variations in the weight of the glass supplied into the ring-shaped member 1. Further, the molding die may be arranged in a vertical position, and after dropping the molten glass on the molding surface of the lower die, the lower die moves laterally and stops immediately below the upper die,
Next, a configuration is conceivable in which the upper mold is lowered and press molding is performed. Further, the material of the glass rod is not limited to LaK7 and can be implemented on any optical glass.

[0026]

Second Embodiment FIG. 4 is a schematic configuration diagram of an apparatus used in this embodiment. In this embodiment, the glass material supply method is different from that of the first embodiment, and the other construction is composed of the same constituent parts. The same constituent parts are designated by the same reference numerals and the description thereof will be omitted.

In order to be located above the ring-shaped member 1,
A funnel-shaped glass material receiver 16 is attached to the heat insulating member 3. Reference numeral 17 is a solid glass material having a weight corresponding to the dropped portion. The glass material 17 is aligned with the storage hole 18a of the pallet 18. Reference numeral 19 is a robot having a chuck 19a. The robot 19 can chuck the glass materials 17 in the pallet 18 one by one and transfer them onto the glass material receiver 16 at an arbitrary takt time, and open the chuck to supply the glass material 17 to the ring-shaped member 1. It is configured like.

A molding method using the apparatus having the above structure will be described below. If the robot 19 is controlled so that the supply interval of the glass material 17 becomes a desired interval, the glass material is supplied into the ring-shaped member 1 at the time intervals, and then melts and moves downward to form glass drops. And then drip. At this time, the surface area of the ring-shaped member 1 is set to be large so that the dropped glass material 17 does not penetrate the molten glass adhering to the inside of the ring-shaped member 1.

When the surface area of the ring-shaped member 1 is increased,
The adhered area of the molten glass inside becomes large, and the supplied glass material can be sufficiently held in the ring-shaped member 1. Therefore, it becomes possible to stably form glass drops. As a method of increasing the surface area, it is possible to increase the length of the ring-shaped member or provide a step.

According to this embodiment, a predetermined weight of the solid glass material can be reliably supplied into the ring-shaped member.

As a modified example of this embodiment, the glass material may be heated in advance and then supplied. In this case, since the melting time of the glass material can be shortened, the dropping can be performed with a shorter takt time.

[0032]

As described above, according to the glass optical element molding method and apparatus of the present invention, the molten glass dropping interval is shortened to improve the productivity, and the operating rate of the molding machine is greatly increased. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a first embodiment.

FIG. 2 is a cross-sectional view showing a first embodiment.

FIG. 3 is a cross-sectional view showing the first embodiment.

FIG. 4 is a schematic configuration diagram showing a second embodiment.

[Explanation of symbols]

 1 ring-shaped member 2 high frequency heating coil 3 heat insulating member 4 glass rod 5 lifting mechanism 6 roller 7 sleeve 8 dripping glass 9,10 molding die 11 pressing plate 12, 14 press rod 13 heater

Claims (3)

[Claims] 1. A method for molding a glass optical element, which comprises heating and melting a glass material and then supplying a predetermined amount of molten glass to a molding die, wherein a solid glass material is applied to the inner surface of a ring-shaped high temperature member within a desired dropping time. A method for molding a glass optical element, comprising: a step of supplying a dripping amount or more to heat and melt; and a step of dripping and supplying molten glass from a ring-shaped high temperature member to a molding die. 2. The method for molding a glass optical element according to claim 1, wherein the glass material is rod-shaped or fiber-shaped. 3. A ring-shaped member for melting a glass material,
A heating means provided on the ring-shaped member, a supply means for supplying a predetermined amount of glass material to the ring-shaped member at a desired supply rate, and a mold for pressing molten glass dropped from the ring-shaped member. An apparatus for molding a glass optical element, which comprises: