JPH07133119A - Method for forming optical glass element or the like - Google Patents

Abstract

PURPOSE:To form an optical glass element, etc., with the quality stabilized without using any expensive preform by supplying the raw material without being influenced by the shape of a formed article and precisely controlling the weight of the raw material to be supplied. CONSTITUTION:The fine grain 35 (or globule) of glass as the raw material is weighed by a weighing device 50, and the specified amt. of the grain corresponding to a formed article 70 is taken out, supplied between a couple of upper and lower dies 20 and 21 of the forming device 100, heated and pressed to form an optical element 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding an optical glass element such as a glass lens of a camera or a pickup lens of a compact disc, or an optical glass element such as a cover glass of a watch, which is formed by pressing. .

[0002]

2. Description of the Related Art Conventionally, as a method of press-molding an optical glass element or the like of this type, (A) a method of press-molding a glass gob obtained by discharging softened glass through a nozzle and measuring and cutting the glass gob.

(B) A method in which a preform which has been preliminarily processed into a spherical shape or a disc shape and whose weight is controlled or a prepressed preform is heated and press-molded at a predetermined temperature.
Etc. have been adopted.

[0004]

However, the molding method of the former (A) is as follows. Since glass that is softened at high temperature is cut while being weighed, there is difficulty in temperature control and cutting, and the stability of quality is lacking due to variations in weighing. Further, when molding a large-diameter optical glass element, weighing becomes more difficult. b. Due to the relationship between the glass gob supply and the molding cycle, it is difficult to match the timing with measuring cutting and press molding. c. Since the glass gob is transported at a high temperature, there are restrictions on the transportation device. d. In the case of glass materials with different specific gravities, it is difficult to control the measurement and the glass materials are restricted. Have problems such as.

The molding method of the latter (B) is as follows. Accurate weight control and processing of the preform adds to the cost of the preform. b. Although there is no problem in molding a convex lens, for example, in molding a biconcave lens, it is not possible to place a spherical preform in the center of the mold, so there is a constraint such as using a disc-shaped or prepressed approximate preform. Receive. Have problems such as.

The present invention has been made in view of the above circumstances. It does not use expensive preforms and can supply raw materials regardless of the shape of the molded product, and the weight of the supplied raw materials can be accurately controlled. An object of the present invention is to provide a molding method of an optical glass element or the like which can be carried out and enables molding of an optical glass element or the like having stable quality.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention measures the fine particles or small spheres of glass, which is a glass raw material, and takes out a predetermined weight corresponding to a molded product and removes it between a pair of upper and lower molds. A glass raw material supplying step, a heating step of heating the glass fine particles or small spheres and the mold supplied by the glass raw material supplying step, and the upper and lower parts in a state of being heated to a predetermined temperature by this heating step. And a press step of press-forming a pair of molds to press-mold an optical glass element or the like.

[0008]

According to the molding method of the present invention, fine particles or small spheres of glass are used as a glass raw material, and this is weighed, and a predetermined weight corresponding to the molded product is supplied between the upper and lower molds, followed by heating and pressing. Therefore, it is possible to use an electronic balance or the like that can be used at room temperature for measuring the glass raw material, compared to the conventional glass gob or expensive preform as the glass raw material,
It is possible to accurately control the weight of the raw material to be supplied, and it is possible to obtain a molded product such as an optical glass element having stable quality. In addition, even a biconcave lens or an asymmetrically shaped lens can be molded without being restricted by the shape of the molded product.

Further, when an infrared lamp is used as a heating source, the temperature rise rate of the fine particles or small spheres of glass is higher than that of the preform, and the temperature reaches a predetermined temperature in a short time. As a result, the cycle time can be shortened by improving the heating efficiency and the productivity can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows only the molding apparatus 100,
FIG. 2 shows an overall configuration including a molding apparatus 100, an autoloader 52 as a loading / unloading apparatus for loading a glass raw material into the molding apparatus 100 and unloading a molded product, a weighing apparatus 50, and a work stocker 53. .

First, the molding apparatus 100 will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a fixed shaft, the upper end side of the fixed shaft 1 is fixed to the ceiling portion of the frame 2, and the fixed die plate 4 is attached to the lower end via a hollow heat insulating member 3. 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 with bolts or the like.

A moving shaft 7 is provided below the fixed shaft 1 so as to be coaxial therewith, and an upper end of the moving shaft 7 is moved by a hollow heat insulating member 8 like the fixed shaft 1. A plate 9 is attached, and a lower cavity die 11 made of ceramics or the like is attached to the moving die plate 9 together with the moving die 10.

The moving shaft 7 penetrates the base 22 and extends downward, and is connected to the servo motor 16 via a reduction gear, a coupling, or the like (not shown). The servomotor 16 moves up and down at a desired speed according to the molding process, is given a desired lifting force (pressing force), and is stopped at a desired position.

A drive device such as an air cylinder (not shown) is provided on the frame 2, and a bracket 23 having the fixed shaft 1 as a guide is attached to the drive device so as to be vertically movable. A hollow cylindrical partition wall 24 made of a heat-resistant and transparent member that transmits infrared rays, such as transparent quartz glass, is attached to the bracket 23.

The partition wall 24 has an upper die 20 made of an assembly of a fixed die plate 4, a fixed die 5 and an upper cavity die 6 and a lower die made of an assembly of a moving die plate 9, a moving die 10 and a lower cavity die 11. 21 and the vertical movement of the bracket 23 forms an openable / closable molding chamber 25 between the bracket 23 and the base 22.

An infrared lamp unit 30, which is a heating source, is attached to the bracket 23 so as to surround the partition wall 24, and heats the upper mold 20, the lower mold 21, and the glass fine particles 35 as a glass raw material. ing.

Further, as shown in FIG. 2, an auto loader 52 as a loading / unloading device has a grip portion 55A capable of reversing and gripping operation at the tip of an arm 55 which can be swiveled, extended, and vertically moved. The robot 51 has a container 51 containing glass fine particles 35 as a glass raw material and an optical glass element 70 which is a molded product and can be carried to a predetermined position.

The weighing device 50 is composed of an electronic balance such as a plate type which can be used at room temperature, and is an optical glass element 70 which is a molded product.
The glass fine particles 35 as a glass raw material corresponding to the predetermined weight can be accurately measured.

Further, the work stocker 53 is composed of a carrier truck capable of stocking a plurality of optical glass elements 70 on the upper surface thereof. Next, the molding operation will be described with reference to FIGS. 1 and 2.

First, while the partition wall 24 of the molding apparatus 100 is elevated, the glass particles 35 are supplied into the container 51 on the weighing device 50 by a feeder (not shown).
Then, when the weighing device 50 weighs a predetermined weight corresponding to the molded product, the supply is stopped. Next, the glass particles 35 in a predetermined weight are put together with the container 51 in the autoloader 5
To the molding apparatus 100 via the lower cavity die 1
1 Put it on so that it does not spill.

Next, the partition wall 24 is lowered to form a sealed molding chamber 25, and the inside of the molding chamber 25 is replaced with N ₂ . Then, the infrared lamp unit 30 heats the upper mold 20, the lower mold 21, and the glass particles 35.
Then, the lower mold 21 is raised at a desired speed and a desired pressing force in accordance with the molding process to mold the optical glass element 70.

After cooling, the partition wall 24 is raised and the molded optical glass element 70 is molded by the autoloader 52 by the molding apparatus 1.
00 and store it in the work stocker 53. Here, the glass fine particles 35 as a glass raw material used as an example are a glass type of LLF-6 and have a particle size of 1 μm.
Spherical glass particles having a peak of were used.

The glass type LLF-6 used has a transition point of 453 ° C., a softening point of 637 ° C. and a specific gravity of 2.79.
For comparison with the present invention, a molding experiment using a conventional spherical preform 60 as shown in FIG. 3 was also conducted in parallel.

The molded lens is a convex lens having an outer diameter of φ33. In addition, we have also confirmed the biconcave lens and obtained a highly accurate concave lens, but with the biconcave lens,
Since it is difficult to arrange the spherical preform 60 in the center of the mold by molding the concave lens using the spherical preform 60 of the conventional example, the description of the biconcave lens will be omitted and the convex lens of φ33 will be described. . (Comparative Example) First, an example in which the conventional spherical preform 60 is used will be described.

The outer diameter of the spherical preform 60 used was measured with a micrometer, and the outer diameter was 18.136 mm.
Then, the weight = 8.6931 g. This preform 6
0 on the lower cavity die 11 as shown in FIG.
After moving down the partition wall 24 and replacing the inside of the molding chamber 25 with N ₂ ,
The fixed die 5 and the movable die 10 are respectively 40a and 40b.
The temperature was measured by a thermocouple of No. 1 and the temperature was controlled and heated to 605 ° C. Although the temperature reached 605 ° C in about 130 seconds, it was held for 180 seconds in order to stabilize the temperature of the upper mold 20, the lower mold 21, and the preform 60, and then the press was started. Stop, 45
As a result of repressing after cooling and holding to 5 ° C, surface accuracy λ / 1
A highly accurate convex lens of 0 was obtained. (Example) Next, an example of the present invention will be described.

Spherical glass fine particles having a particle diameter of 1 μm are weighed by an electronic balance having a maximum weight of 32 g and a minimum display of 0.01 mg to be in the range of 8.693050 to 8.693060 g, and placed on the lower cavity die 11. did.

For weighing and transferring, an electronic balance is attached to the apparatus as shown in FIG.
The method of transporting with an electronic balance installed on the device without using the autoloader 52
There is a method in which the partition wall 24 is raised and a feeder is directly inserted between the upper die 20 and the lower die 21 to transfer it to the die. In addition, what has been weighed in advance at another place outside the device is the autoloader 52.
Or a feeder may be transferred between the molds.

After the partition wall 24 was lowered and the inside of the molding chamber 25 was replaced with N ₂ as in the above, the temperature of the fixed die 5 and the moving die 10 was set to 630 ° C. and heated. The temperature reached 630 ° C. for about 120 seconds, which was faster than that when the preform 60 was used. This is used for stabilizing the entire temperature of the upper mold 20, the lower mold 21, and the preform 60 in the same manner as described above.
After holding for 0 sec, it enters the press and before the die comes into close contact with it.
As a result of stopping once at 01 mm, cooling and holding to 455 ° C. and then re-pressing, a highly accurate convex lens with a surface accuracy of λ / 4 was obtained. Here, as a result of examining the weighing accuracy, it was found that the present invention has the following advantages.

Although the weight of the obtained preform 60 depends on the manufacturing method, the value of 0.001 g = 1 mg has changed, and if the accuracy is further increased, it becomes more expensive and there is a problem in terms of profitability. is there.

Now, the diameter is 18.136 mm and the weight is
Assuming that the outer diameter of the 8.6931 g of preform 60 can be reduced by 1 μm, the weight of the preform 60 will be reduced by 1.44 mg by calculation. W ₁ = 4/3 × π × (1.8136 / 2) ³ × 2.79
= 8.71420 (g) W ₂ = 4/3 × π × (1.8135 / 2) ³ × 2.79
_{= 8.71276 (g) W 1 -W2} = 8.71496-8.71275 = 0.0
On the other hand, in the case of the present invention, a particle having a particle size of 1 μm is 0.14 = 1.44 (mg).
It is 4/3 × π × (0.0001 / 2) ³ × 2.79 =
1.46 × 10 ⁻¹⁰ (g) 0.1 × 10 ⁻³ /1.46×10 ⁻¹⁰ = 6.85 × 10
Since it becomes ⁵ (pieces), weight management becomes easy, and it becomes easy to improve weighing accuracy.

Since some electronic balances have an RS232C interface function and a limiter function,
The control of the feed amount from the feeder improves the weighing accuracy and can be automated.

Further, as an effect of the present embodiment, it is possible to further increase the heating rate. Presuming the reason, since glass transmits most of infrared rays, it is difficult to directly heat the preform 60.

However, in the case of fine particles or small spheres, the infrared rays incident on one particle are refracted, so that even if they are transmitted, they are incident on the next particle and refracted. For this reason, it is considered that the infrared rays are trapped and do not easily go out to the outside, but are substantially absorbed and the heating efficiency is improved.

The concern when using fine particles or small spheres was that the gas was confined. Whether the heating temperature and pressing speed were appropriate, or whether the degassing structure of the mold was appropriate. Or, it is not clear whether the gas diffused in the molded product, but it is not a problem.

It should be noted, however, that when the inside of the molding chamber 25 is replaced with N _2, if the mold structure is such that the flow rate of N ₂ gas is high and the particles are directly blown onto the particles, the particles will fly up.

As described above, it is possible to mold a lens with sufficiently high accuracy by using inexpensive fine particles or small spheres without using the expensive preform 60. The present invention provides stable cost and weight management. It was confirmed that the present invention is superior in terms of heating rate and molding of biconcave lenses and odd-shaped lenses.

Further, as described above, the softened glass is taken out from the nozzle and weighed and cut, and the glass gob is placed between the molds and press-molded. Regarding the method of press-molding, the softened glass is cut while being weighed. Therefore, there is a difficulty in temperature control and cutting, lack of stability in quality due to variation in weighing, and when molding a large-diameter optical glass element, weighing becomes more difficult and glass gob supply and Due to the cycle, it is difficult to match the timing with measuring cutting and press forming, the glass gob is conveyed at high temperature, there are restrictions on the conveying device, and these things and the measurement management in the case of glass materials with different specific gravity, etc. Therefore, there is a problem that the glass material is restricted.

It is considered that the present invention solves these problems. As described above, the present invention proposes what form of glass raw material is to be supplied when press-molding, and the molding conditions, molding method, heating method, etc. are not limited, For example, as a heating method, it goes without saying that the mold may be heated by high frequency induction heating and the radiant heat may be used to heat the glass.

However, when an infrared lamp is used as the heating source, when the glass particles or small spheres are used as the glass raw material, the temperature rising rate is faster than in the case of the preform, and the temperature reaches the predetermined temperature in a short time. As a result, heating efficiency can be improved and cycle time can be shortened, and productivity can be improved.

The particle size of the fine particles used was a peak of 1 μm.
If the fine particles of m can be manufactured at a low cost, the technical effect does not change even if it is slightly increased or decreased, and thus there is no restriction.
In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the spirit of the present invention.

[0041]

As described above, the present invention has the following effects. According to the molding method of claim 1, fine particles or small spheres of glass are used as a glass raw material, and the glass raw material is weighed and a predetermined weight corresponding to the molded product is supplied between the pair of upper and lower molds, followed by heating and pressing. Therefore, an electronic balance that can be used at room temperature can be used to measure the glass raw material, and the weight of the supplied raw material can be controlled more accurately than the conventional glass gob or expensive preform method. Thus, it is possible to obtain a molded product such as an optical glass element having stable quality. In addition, even a biconcave lens or an asymmetrically shaped lens can be molded without being restricted by the shape of the molded product.

According to the molding method of claim 2, since an infrared lamp is used as a heating source, the temperature rise rate of the fine particles of glass or small spheres is faster than that of the preform.
The predetermined temperature is reached in a short time, the heating efficiency can be improved, the cycle time can be shortened, and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view schematically showing an embodiment of a molding apparatus that can carry out the present invention.

FIG. 2 is a partial cross-sectional plan view for explaining the overall configuration of the device.

FIG. 3 is an explanatory view showing a molding state of a spherical preform.

[Explanation of symbols]

20 ... Upper mold, 21 ... Lower mold, 24 ... Partition wall, 25 ... Molding chamber,
30 ... Infrared lamp unit (heating source), 35 ... Glass fine particles (glass raw material), 50 ... Weighing device, 51 ... Container,
52 ... Auto loader (loading / unloading device), 53 ... Work stocker, 55 ... Arm, 55A ... Gripping part, 70 ... Optical element (molded product), 100 ... Molding device.

Claims (2)

[Claims] 1. A glass raw material supplying step of measuring fine particles or small spheres of glass, which is a glass raw material, and taking out a predetermined weight corresponding to a molded product and disposing the glass raw material between a pair of upper and lower molds, and the glass raw material supplying step. And a heating step of heating the glass fine particles or small spheres and the mold, and a press for press-forming the optical glass element etc. by pressing the pair of upper and lower molds in a state of being heated to a predetermined temperature by this heating step. And a step of forming an optical glass element or the like. 2. The method for molding an optical glass element or the like according to claim 1, wherein an infrared lamp is used as a heating source in the heating step.