JP3243219B2 - Method for manufacturing glass optical element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glass optical element such as a glass lens by pressing a glass material to be molded. In particular, the present invention, even if it is necessary to significantly deform the glass material to be molded having a different shape from the glass optical element as the final product by press molding,
The present invention relates to a molding method capable of obtaining, at a relatively high production speed, a glass optical element having good optical characteristics that does not require subsequent grinding and polishing.

[0002]

2. Description of the Related Art A glass preform, which is a glass material to be molded, is press-molded in a molding die having the required surface accuracy and surface roughness required for the surface of the glass molded body, and the glass which does not require grinding and polishing after the press molding is required. Various methods for manufacturing an optical element have been conventionally known. For example, the method described in Japanese Patent Application Laid-Open No. 64-72929 or Japanese Patent Publication No. 2-62525 is a method of heating a mold and a glass preform together. That is, a glass preform is inserted into a molding die composed of an upper die, a lower die and a guide die for guiding them, and heated together with the molding die to a temperature at which the preform is sufficiently softened, followed by pressure molding. Next, the glass molded body is cooled to a temperature near the glass transition point at a cooling rate that does not impair the surface accuracy of the molded glass (or cooled to around room temperature after a certain period of time). The glass compact is removed.

[0003] As described above, in a method in which the preform is heated, molded and cooled together with the mold while the glass preform is held in the mold, the temperature of the glass and the mold is always substantially equal, and the press is performed. As the process progresses,
The temperature difference between the surface of the glass and the inside of the glass is eliminated, so that sink is unlikely to occur and stable surface accuracy is obtained. However, there is a drawback that the cycle time required for all the steps is extremely long because the temperature rise time before starting the press and the cooling time required for taking out after the press are required. Furthermore, since the contact time between the glass and the mold surface in the process from heating to pressing is long, there is a disadvantage that a reaction easily occurs between the glass and the mold surface, and the mold life is shortened.

On the other hand, a glass preform softened in advance is inserted separately into a heated mold,
There is also known a method of forming a glass optical element which can eliminate the need for grinding and polishing after press forming [Japanese Patent Laid-Open No. 251529/1986].
No., No. 61-286232, No. 62-27334,
No. 63-45134]. Also in this method, as described above, a molding die having the required surface accuracy and surface roughness required for the glass molded body surface is used. As described above, the method of press-molding a glass preform that has been heated and softened in a preheated mold has an advantage that a short press time is required. Furthermore, since the temperature of the mold can be made relatively low and the mold can be released if a certain period of time is left for cooling the glass temperature after pressing, the cycle time can be greatly reduced.

[0005]

However, in this method, when the glass material needs to be largely deformed, it may not be possible to form the glass material to a desired shape. That is, in this method, a mold at a relatively low temperature is usually used to shorten the cycle time.
Therefore, the glass may be cooled and solidified before press molding to a desired thickness. As a result, it is not possible to stably obtain a glass molded body obtained by greatly deforming a glass material, such as a biconvex lens having a small edge thickness (about 0.8 to 1.3 mm), a meniscus lens, a concave lens, and the like. There was a problem. Also, when a spherical glass material to be molded is molded, the amount of deformation increases, and the same problem occurs. Furthermore, even if it can be molded to the desired shape,
There was also a drawback that sink marks and shape distortions were easily generated and surface accuracy was hardly obtained. That is, there was a problem that the shape transferability was insufficient.

In particular, when a glass preform is manufactured by a hot forming method, the glass preform usually has a spherical shape or a marble shape, and does not have a shape close to a final product. Therefore, in order to obtain a desired shape, it is necessary to greatly deform the material by press molding, and the above-described problem has occurred.

Therefore, the object of the present invention is not different from the conventional one, even when a glass material is largely deformed to manufacture a glass optical element, such as when a glass material having a shape greatly different from the final product is used. It is an object of the present invention to provide a method for forming a glass optical element, which can be formed with a relatively short cycle time and can stably obtain a glass formed body having excellent surface accuracy.

The present inventor has made intensive studies to solve the above-mentioned problems of the prior art. As a result, at the time of press molding of the glass optical element, the temperature (viscosity) of the glass material to be molded and the temperature of the mold are maintained so as to maintain a constant relationship.
It has been found that a glass optical element having excellent surface precision can be manufactured by shortening the cycle time of the press forming step and prepressing by heating them in advance. Further, the present inventor has found that when a glass material is press-molded under the above temperature conditions, the center thickness of the glass material is 7 mm.
The present inventors have found that by applying pressure to 0% or less, it is possible to obtain a glass molded body having particularly excellent surface accuracy, and completed the present invention.

[0009]

The present invention for solving the above-mentioned problems is the following four manufacturing methods. The first method is to heat and soften a glass material to be molded into a molding die including an upper mold and a lower mold until the center thickness of the glass molded body becomes 70% or less of the center thickness of the glass material to be molded. A method for producing a glass optical element including a step of forming a glass molded body by pressure molding, wherein the molded glass material is heated and softened to a temperature at which the molded glass material exhibits a Y poise viscosity, and The heat-softened glass material to be molded is introduced into a mold in which the average temperature of each molding surface of the upper mold and the lower mold is adjusted to a temperature at which the glass material to be molded exhibits a viscosity of X poise, and the pressure molding is performed. And a viscosity X and a viscosity Y satisfy the following formulas. logX <10 logY ≧ 6.5 Y <X −logX + 14.5 ≦ logY ≦ −logX + 18 The second method is to press a heat-softened spherical glass material to be molded with a mold including an upper mold and a lower mold. What is claimed is: 1. A method for producing a glass optical element comprising a step of molding to form a glass molded body, wherein the molded glass material is heated and softened to a temperature at which the molded glass material has a viscosity of Y poise. Introducing the molded glass material into a mold in which the average temperature of each molding surface of the upper mold and the lower mold is adjusted to a temperature at which the molded glass material exhibits a viscosity of X poise. And the viscosity X and the viscosity Y satisfy the following formulas. logX <10 logY ≧ 6.5 Y <X −logX + 14.5 ≦ logY ≦ −logX + 18 The third method is to press a heat-softened spherical glass material to be molded with a mold including an upper mold and a lower mold. A method for producing a glass optical element including a step of molding to form a glass molded body, wherein the pressure molding, the molded glass material is a temperature at which the molded glass material exhibits a viscosity of Y Poise, The average temperature of the molding surface of each of the upper mold and the lower mold is a temperature at which the glass material to be molded shows a viscosity of X poise, and the viscosity X and the viscosity Y are started when the following formula is satisfied. This is a method for manufacturing a glass optical element, which is a feature. logX <10 logY ≧ 6.5 (however, when 9.0 ≦ logX <10, logY> 7.0) Y <X−logX + 14.5 ≦ logY ≦ −logX + 18 The fourth method is heat softening. A method for manufacturing a glass optical element, comprising a step of forming a molded glass material into a glass molded body by pressure molding with a molding die including an upper mold and a lower mold, wherein the pressure molding is performed on the molded glass. The material is a temperature at which this molded glass material exhibits a viscosity of Y poise, and the average temperature of each molding surface of the upper mold and the lower mold is a temperature at which the molded glass material exhibits a viscosity of X poise, A method for producing a glass optical element, which is started when the viscosity X and the viscosity Y satisfy the following formulas. logX <9 logY ≧ 6.5 Y <X logY ≧ −logX + 14.5

In the present invention, there is further provided a method for manufacturing a glass optical element, wherein the glass material to be formed is softened by heating while being floated by an air current.

[0011]

Embodiments of the present invention will be described below. The present invention is a method for molding a glass optical element by pressure-molding a heat-softened glass material to be molded with a preheated mold. The types and shapes of the glass constituting the glass material are conventionally known.
The glass material can be, for example, a glass preform or a glass gob. The glass preform refers to a molded product formed into a predetermined shape used as a precursor when molding a glass optical element. The glass preform may be formed by cold forming or molten glass being formed by hot forming, or may be obtained by subjecting them to mirror polishing or the like. Further, the surface may be not a mirror surface but a rough surface. For example, a ground product ground with # 800 diamond may be used as a glass preform.

The shape of the glass preform is determined in consideration of the size and capacity of the glass optical element as a final product, the amount of change during molding, and the like. In the first method of the present invention, the center thickness of the final product is set so as to be 70% or less of the center thickness of the glass material to be molded such as a preform in order to obtain a molded article having particularly excellent surface accuracy. Is done. The ratio of the center thickness of the final product to the center thickness of the glass material to be formed is more preferably 50% or less from the viewpoint of obtaining a molded product having more excellent surface accuracy.
It is more preferably at most 40%. In order to obtain a molded product having excellent surface accuracy, it is ideally preferable to use a preform that approximates the shape of the final product and to reduce the amount of deformation with a higher viscosity. However, manufacturing a preform that approximates the shape of the final product is costly and impractical. Therefore, in the present invention, even if a preform that does not approximate the shape of the final product is used, a molded product having excellent surface accuracy is obtained by setting the deformation amount to a certain degree or more as described above.

Further, in order to prevent a gas trap from being generated at the time of molding, it is preferable that the shape of the molded product is such that the center of the molded product first comes into contact with the molding surface of the preform. The shape of the glass preform can be, for example, a sphere, a marble, a disk, a square plate, or the like, but a sphere generally has the largest deformation during molding. On the other hand, a glass gob is a piece of glass obtained by dividing molten glass into a predetermined volume, and usually has an irregular shape such as wrinkles. The preform is obtained by further hot or cold forming this glass gob into a predetermined shape, or directly from molten glass, a spherical shape, a marble shape, a disk shape,
It was hot-formed into a square plate shape. In this case, the forming method includes a method in which the molten glass is dropped and solidified in the middle of dropping, and a method in which the molten glass is formed into a sphere or marble while being floated on a gas and cooled. Since the preform has a spherical shape, it can be formed while dripping molten glass or floating with gas,
This is preferable in that a preform having no surface defects can be formed. However, when the preform has a spherical shape, not only the degree of wall thickness deformation at the time of pressure molding is large, but also the degree of elongation in the width direction increases. Therefore, by using the second method or the third method of the present invention, an optical element with good surface accuracy can be obtained.

In the production method of the present invention, a glass lump obtained without returning a lump of molten glass produced from molten glass to room temperature can be used as the glass material to be molded. Specifically, such a glass lump can be produced by converting molten glass continuously supplied from an outflow pipe into individual glass lump. For example, a method described in JP-A-9-12317 can be used. Further, it is preferable that the glass block has a spherical shape or a marble shape (a shape obtained by flattening a sphere). As a method of forming an independent glass lump, the following three methods are preferable. (1) A method in which a molten glass flow is naturally cut by its own weight and surface tension before or during receiving a molten glass flowing down from an outflow pipe by a receiving mold to obtain a glass block having a desired weight. (2) A method of obtaining a glass block having a desired weight by blowing a gas and forcibly cutting it by wind pressure before or during receiving molten glass flowing down from an outflow pipe by a mold. (3) A method in which a molten glass flowing down from an outflow pipe is received by a mold, and then the molten glass is rapidly lowered to cut the molten glass flow to obtain a glass block having a desired weight.

A feature of the above methods (1) and (2) is that no shearing is performed. According to the above-mentioned methods (1) to (3), there is an advantage that a cutting defect due to a shear such as a bubble or a folding vein does not occur in the molten glass lump. The temperature of the molten glass is appropriately determined in consideration of the viscosity of the molten glass flowing down from the outflow pipe. The viscosity of the molten glass flowing down depends on the diameter of the outflow pipe,
In consideration of the stability of the glass, the surface tension of the glass, stringing, and the like, it is appropriate that the range is 5 to 50 poise. The temperature at which the glass has a viscosity in the above range varies depending on the type of glass, but is, for example, in the range of 800 to 1100 ° C. The weight of the independent molten glass lump can be appropriately determined according to the size of the glass optical element as the final product.
Further, the type of glass to be used can be appropriately determined in consideration of the functional characteristics and the like required for the glass optical element as the final product.

The molten glass lump formed and dripped or flowing down by the above method is received by an airflow spouting from below, and the glass lump received by the airflow is floated and held. For the receiving and floating holding, for example, a receiving die described in Japanese Patent Application Laid-Open No. 2-14839 can be used. The receiving mold has a concave portion for receiving and floating the glass lump, and the concave portion is provided with one or a plurality of gas outlets for floating the glass lump.

Further, in the present invention, Japanese Patent Application Laid-Open No. 2-14839
It is also possible to use a modified mold of No. That is, the improved receiving mold forms a closed space with the glass block and the opening below the glass block in the opening. In this space, the glass lump can be floated in the opening by an air current ejected from a small hole from below. By configuring the closed space as described above, good levitation can be obtained. still,
When the airflow is concentrated on the glass lump at the lower central portion, when the glass is made low-viscosity in the process of adjusting the temperature, a depression is generated at the lower central portion. Therefore, by ejecting gas from the plurality of small holes, it is possible to concentrate on the lower central portion of the glass lump and cause the glass lump to float without causing dents. The glass lump is held in a non-contact state by blowing gas in the concave portion of the receiving die.

Further, by giving directionality to the air flow, the glass lump can be floated while rotating. By controlling the rotation direction and rotation speed of the softened glass block,
The shape of the glass lump can be changed to a desired shape. Rotating the glass block in the horizontal direction improves the roundness, and rotating the glass block in the vertical direction improves the sphericity.

It is preferable that the gas used for floating the glass lump is appropriately selected in consideration of the prevention of deterioration of the glass lump floating softening apparatus and the molding apparatus. Examples of such a gas include a non-reactive gas such as nitrogen and a non-oxidizing gas. Furthermore, it is also possible to add some reducing components, such as hydrogen gas, to nitrogen or the like. However, air may be used if the material of the floating softening device forms an oxide film or an oxide is selected.

The flow rate of the air flow can be changed as appropriate in consideration of the shape of the outlet from which the air flow is blown out, the shape and weight of the glass block, and the like.
Normally, a gas flow rate in the range of 0.005 to 20 liters / minute is suitable for floating the glass block. However, if the gas flow rate is less than 0.005 liter / minute, the glass lump may not be able to float sufficiently when the weight of the glass lump is 300 mg or more. Further, when the gas flow rate exceeds 20 liters / minute, even if the glass weight is 2000 mg or more, the glass on the levitation softening device shakes greatly,
This is because the glass block may change into an unintended shape during heating.

The material of the flotation device is not particularly limited as long as it has a heat resistance that does not cause a defect or a defect in the glass lump even when the glass slightly contacts during molding. Examples include silicon, silicon carbide, silicon nitride, tungsten carbide, aluminum oxide, titanium nitride, titanium carbide, zirconium oxide, various cermets,
Examples include carbon, stainless steel, quartz glass, glass, and various heat-resistant metals.

In a usual method, it is very difficult to prevent fusion of the glass with a device for holding the glass lump during heating in a low viscosity region where the glass lump is deformed by its own weight. Therefore, in the present invention, a gas layer is formed between the apparatus surface and the glass surface by ejecting a gas from the inside of the flotation device and causing the glass block to float by an air current,
As a result, a glass lump can be formed from the molten glass without the floating device reacting with the glass. Further, by rotating the glass lump, the glass lump can be floated more stably. Further, it can be softened by heating while maintaining the shape of the glass lump, and can be further deformed to a desired shape if necessary. In addition, even when there is a surface defect such as a wrinkle on the surface of the glass lump, it is possible to adjust the shape and eliminate the surface defect by floating by an air current, but it is a bubble or a broken vein. Shermarks cannot be erased by softening them to very high temperatures.

In the manufacturing method of the present invention, at the time of molding, it is necessary to heat and mold the glass so that the temperature of the mold and the temperature (viscosity) of the glass material to be molded maintain a constant relationship. That is, in the first and second methods of the present invention, a step of heating and softening a glass material to be molded to a temperature at which the glass material to be molded exhibits a viscosity of Y poise, The method includes a step of introducing the average temperature of the molding surfaces of the mold and the lower mold into a molding die adjusted to a temperature at which the glass material to be molded exhibits a viscosity of X poise to perform pressure molding.
Then, the viscosity X and the viscosity Y are adjusted so as to satisfy the following equations. Further, in the third method of the present invention, the pressure molding is performed, wherein the glass material to be molded is at a temperature at which the glass material to be molded exhibits a Y poise viscosity, and the molding surface of each of the upper mold and the lower mold is formed. Is the temperature at which the glass material to be formed exhibits a viscosity of X poise and the viscosity X and the viscosity Y satisfy the following formula. logX <10 logY ≧ 6.5 Y <X −logX + 14.5 ≦ logY ≦ −logX + 18 However, in the third method of the present invention, 9.0 ≦ logX <1.
When it is 0, logY> 7.0.

Further, in the fourth method of the present invention, the pressure molding may be performed by the step wherein the glass material to be molded is at a temperature at which the glass material to be molded exhibits a Y poise viscosity. When the average temperature of each molding surface is X
It is started when the temperature is the temperature indicating the viscosity of Poise and the viscosity X and the viscosity Y satisfy the following formulas. logX <9 logY ≧ 6.5 Y <X logY ≧ −logX + 14.5

FIG. 8 shows the relationship between X and Y, that is, the relationship between the average temperature of the mold and the temperature of the glass material to be molded.
Description will be made with reference to (first method), FIG. 9 (second method), FIG. 10 (third method), and FIG. 4 (fourth method). The temperature of the molding die and the glass material to be molded in each figure is the viscosity (Poise) of the corresponding glass material to be molded.
Is shown as the common logarithm of In this specification, as the temperature of the molding surface of the upper mold and the temperature of the molding surface of the lower mold, the temperature inside the upper mold or the lower mold about 1 to 2 mm from the molding surface can be applied. The temperature at the above position can be measured and has a temperature that can be substantially approximated to the temperature of the molding surface. Here, the temperature of the molding die indicates an average temperature on each molding surface when there is a temperature distribution on each molding surface of the upper die and the lower die. At this time, the average of the temperatures at two points near the center of the molding surface and at the peripheral portion may be used as the average temperature. In the present invention, it is necessary to carry out pressure molding by setting the average temperature of the molding surface of the upper mold and the temperature of the molding surface of the lower mold to a predetermined temperature range (a range satisfying the above formula). At this time, when the average temperature of the molding surfaces of the upper mold and the lower mold is within the predetermined temperature range, the case where the upper mold or the lower mold and the upper mold and the lower mold are not within the predetermined temperature range is also included.

The first method will be described below with reference to FIG. (1) At the time of molding, if the temperature of the molding die is equal to or higher than the temperature of the glass material to be molded, the molding cycle time becomes longer, and the life of the mold is shortened. In addition, the temperature of the molding die needs to be lower than the temperature of the glass material to be molded. When the relationship between the temperature of the glass material to be formed and the temperature of the molding die is represented by the viscosity of the glass material to be molded, Y (viscosity corresponding to the temperature of the glass material to be molded) <X (corresponding to the temperature of the molding die) (Viscosity of the glass material to be molded) (below the straight line A in FIG. 8). Further, it is more preferable that the temperature of the molding die is lower than the temperature of the glass material to be molded by 10 ° C. or more, and the viscosity of the glass material to be molded is shown in FIG.
This is the area below the straight line A 'in the middle.

(2) If the glass material to be molded is too viscous, that is, the temperature is low, the elongation when the glass material to be molded is pressurized becomes insufficient, and the center thickness of the glass material to be molded is 70% or less. Cannot be obtained. Therefore, in order to obtain sufficient elongation of the glass material to be formed, it is necessary that the temperature of the glass material to be formed and the temperature of the mold are high to some extent. If the relationship between the preferable temperature of the glass material to be formed and the preferable temperature of the forming die is represented by a common logarithm of the viscosity (Poise) of the glass material to be formed, logX + logY ≦ 18 (see FIG. 8). Below line B). Further, in order to obtain the most suitable elongation of the glass material to be formed, it is more preferable that logX + logY ≦ 17.5 (below the straight line B ′ in FIG. 8).

(3) If the temperature of the molding die is too low, the elongation of the glass material to be molded deteriorates. Therefore, it is necessary that the preheating temperature of the mold is higher than the temperature at which the viscosity of the glass material to be molded is 10 ¹⁰ poise, and when expressed in logarithm, logX <10 (left side of the straight line C in FIG. 8). .

(4) If the temperature of the glass material to be formed and the temperature of the mold are too high, the glass material to be formed is too soft and too long, and it is difficult to control the thickness by the second pressing.
Further, the glass material to be molded is easily fused to the molding die, and the die is easily damaged, so that the life of the die is shortened. Therefore, it is necessary that both the glass material to be molded and the molding die are at a certain temperature or lower. If the relationship of this temperature is represented by a common logarithm of the viscosity of the glass material to be formed, logX + lo
gY ≧ 14.5 (above the straight line D in FIG. 8). Further, the relationship between the temperature of the glass material to be formed and the temperature of the forming die is logX.
More preferably, + logY ≧ 15 (above the straight line D ′ in FIG. 8).

(5) Even if the temperature of the molding die is somewhat low, if the glass material itself is too high, it is difficult to deform the glass material in advance by heating and softening the glass material or to hold the glass material. Become. For example, during the softening of the glass material to be floated, the deformation in the floating dish increases, and
The floating is not good, and a trace of contact with the floating plate is generated. For this reason, the temperature of the glass material to be molded is set to a value of 10
It is necessary that the temperature be lower than ^6.5 poise, and logY ≧ 6.5 (above the straight line E in FIG. 8). It is more preferable that logY ≧ 7 (above the straight line E ′ in FIG. 8).

As described above, in the first method of the present invention, the average temperature of the temperature near the molding surface of the upper die and the temperature near the molding surface of the lower die, and the temperature of the glass material to be molded are set to these values. When the viscosity (Poise) of the corresponding glass material to be formed is represented by a common logarithm, the viscosity must be within a range surrounded by straight lines A, B, C, D, and E in FIG. , B ′, C, D ′ and E ′ are more preferable.

In the third method of the present invention, for the same reason as in the first method, the average temperature of the temperature near the molding surface of the upper mold and the temperature near the molding surface of the lower mold, and the temperature of the glass material to be molded are determined. When the temperature is represented by a common logarithm of the viscosity (Poise) of the glass material to be formed corresponding thereto, a range surrounded by straight lines A, B, C, C ′, D, E and E ′ in FIG. Need to be within. The present invention is not limited to a method (first and second methods) of introducing a glass material to be molded into a molding die after pressurizing the molding die and the glass material to be molded to a predetermined temperature (first and second methods). The present invention is also applicable to a method of heating a molded glass material to a predetermined temperature (third and fourth methods). In the third method, 6.5 ≦ logY ≦ 7.5 in a state where the molding die and the glass material to be molded are in contact with each other (that is, in a state where the glass material to be molded is introduced into the molding die).
(Below E ′ in FIG. 10) and 9.0 ≦ logX
≦ 10.0 (to the right of C ′ in FIG. 10),
This temperature range is excluded because the partial temperature difference of the glass material to be formed becomes large and an optical element with a desired surface accuracy cannot be obtained (because the contact portion is at the same temperature in both the mold and the glass material to be formed). .

The fourth method of the present invention is a method which enables the production of an optical element such as a concave meniscus which is not easily stretched at the time of pressure molding and has low surface accuracy, and is similar to the second method. For this reason, the average temperature of the temperature near the molding surface of the upper mold and the temperature near the molding surface of the lower mold, and the temperature of the glass material to be molded are determined by the corresponding viscosity (Poise) of the glass material to be molded. When represented by a common logarithm, a straight line A in FIG.
It must be within the range enclosed by C, D and E. However, in the fourth method, since the purpose of the manufacturing method is to manufacture an optical element in which elongation at the time of pressure molding is not easy and surface accuracy is difficult to be obtained, the preheating temperature of the molding die is determined by the viscosity of the glass material to be molded. 10 ^9.0 Poise or more (log X
≤9.0, left side of the straight line C in FIG. 11). Further, in the case where a glass material to be molded such as a concave meniscus is molded under pressure, it is preferable to apply the second pressure. However, when the temperature of the glass material to be formed and the temperature of the molding die are too high, the glass material to be formed is too soft and too long, and it is difficult to control the thickness by the second pressing. In addition, the glass material to be molded is easily fused to the mold, and the mold is easily damaged,
The life of the mold is shortened. The temperature of the glass material to be formed and the temperature of the forming die both need to be lower than a certain level. When this temperature relationship is represented by the common logarithm of the viscosity of the glass material to be molded,
ogX + logY ≧ 14.5 (above the straight line D in FIG. 11). Further, it is more preferable that the relationship between the temperature of the glass material to be formed and the temperature of the forming die is 17.5 ≧ logX + logY ≧ 15 (the upper side of the straight line D ′ in FIG. 11 and the lower side of D ″).

The preheating temperature of the upper mold and the lower mold of the molding die is:
By lowering the temperature in the vicinity of the molding surface of the upper mold by 5 to 40 ° C., preferably 5 to 25 ° C. in comparison with the temperature in the vicinity of the molding surface of the lower mold, it is possible to more smoothly release the molded glass material after molding. it can. In the molding method of the present invention, the heat-softened glass material is placed in the preheated mold in a range of 1 to
Apply initial pressure for 20 seconds. If the initial pressure is less than 2 seconds, the elongation of the glass is insufficient, and a glass optical element having a desired shape cannot be obtained. In addition, the initial pressurization improves the surface accuracy and the like as much as it is longer. However, if it is too long, the cycle time cannot be shortened, and the life of the mold may be adversely affected. The upper limit is 20 seconds. . The molding pressure can be appropriately determined in consideration of the temperature of the glass material, the temperature of the molding die, and the like. It is usually appropriate to set the pressure in the range of 30 to 300 kg / cm ² . As described above, in the present invention, pressure molding is started in a state where the temperature of the molding die is lower than the temperature of the glass material to be molded (the molding die and the glass material to be molded are non-isothermal) (X> Y). . After the start of pressure molding, the glass material to be molded and the mold are cooled while reducing the temperature difference. At this time, the cooling is performed simultaneously with the start of the pressurization (initial pressurization) or during the pressurization.
Alternatively, it is performed naturally or artificially after the end of the initial pressurization. As a result of the cooling, the glass material to be molded can be cooled to a viscosity that can be released from the mold.

At the same time as the start of the initial pressurization, during the initial pressurization, or after the end of the initial pressurization, the vicinity of the molding surface of the mold is preferably cooled at a rate of 20 ° C./min or more. . The cooling rate can be slower than 20 ° C./min, but this only unnecessarily increases the molding cycle time. Although it depends on the size and shape of the glass molding, it is preferable to cool the vicinity of the molding surface at a rate of 20 to 180 ° C./min from the viewpoint of obtaining high surface accuracy.

In addition, during the cooling after the initial pressurization, the secondary pressurization is performed at a lower pressure than the initial pressurization, and the vicinity of the molding surface is cooled while maintaining this pressure without causing sink marks or distortion in the surface shape. It is preferable from the viewpoint that good surface accuracy can be obtained and the center wall thickness can be kept within an allowable tolerance. Secondary pressure is 10-1
It is performed at a pressure of 00 kg / cm ² or 0.001-1 kg / cm ² , or pressurized at 10-100 kg / cm ² in the first half,
It is preferable to apply a pressure of 0.001 kg / cm ² in the latter half.

Further, the center thickness of the heat-softened glass material is 0.3 mm smaller than the center thickness of the final product. l
It is preferable to perform the initial pressurization so as to be within a range larger by 5 mm, and then perform the secondary pressurization from the viewpoint of maintaining the center thickness of the final product within an allowable tolerance. That is, in the second pressurization, the pressure is reduced at a stroke compared to the initial pressurization, and the glass has a high viscosity.
Since only about 12 mm is deformed under pressure, it is easy to set the final center thickness within the tolerance ± 0.03 mm.

The above-mentioned initial pressurization and secondary pressurization reduce the initial pressurization of the heat-softened glass material by 0.03 mm from the center thickness of the final product. Stop by means of stopping the pressurization so that the desired center thickness is within a range larger by 15 mm,
Further, by performing the secondary pressurization before or simultaneously with the stop of the initial pressurization, the center thickness of the final product is obtained, and the pressurization is performed between the initial pressurization and the secondary pressurization. Since it is continuous, it is preferable from the viewpoint that surface accuracy is not impaired.

When a desired center thickness is obtained by an external stopper mechanism or the like and a secondary pressurization is performed, the pressurization is interrupted for a moment, so that good surface accuracy tends to be difficult to obtain.
The initial pressurization and the secondary pressurization are preferably performed by a double cylinder mechanism. The double cylinder mechanism will be further described in embodiments described later. The glass molded article which has been molded under pressure as described above and then cooled is released from the molding die after the temperature near the molding surface has fallen below the temperature corresponding to the viscosity of the glass material of 10 ¹² poise. When the glass viscosity exceeds 10 ¹² poise, viscous flow does not occur in a short time, and the glass may be regarded as substantially solidified. As a result, the glass molded body is not deformed after the mold release, and a good surface accuracy is obtained. The cooled glass molded body is released after reaching a temperature at which the viscosity becomes 10 ¹² poise or more. Glass viscosity is 10
If it becomes ¹² poises or more, the glass may be regarded as substantially solidified without viscous flow occurring in a short time. As a result, good surface accuracy can be obtained without deformation or the like of the glass molded body after release. Here, if the temperature of the mold near a temperature corresponding to a viscosity of more than 10 ¹² poises is capable of releasing regarded as the glass is also a viscosity of more than 10 ¹² poises.

In particular, when the glass molded body is released from the mold, the temperature in the vicinity of the molding surface is changed from the transition point to the transition point −50 of the glass material.
It is particularly preferable to carry out when the temperature is in the range of ° C. As the mold used in the present invention, a conventionally known mold can be used as it is, for example, an upper mold 35 as shown in FIG.
A molding die 39 including a lower die 34 and a guide die 36 can be used. However, it is not limited to these. In addition, as a mold, cermets such as silicon carbide, silicon, silicon nitride, tungsten carbide, aluminum oxide and titanium carbide, and diamond, heat-resistant metals, noble metal alloys, carbides, nitrides, borides, oxides, etc. Those coated with ceramics or the like can be used. In particular, after forming a silicon carbide film on the silicon carbide sintered body by the CVD method and processing it into a finished shape,
It is preferable to form a carbon film composed of a single component layer or a mixed layer of amorphous and / or crystalline graphite and / or diamond such as an i-carbon film by an ion plating method or the like. The reason is that no fusion occurs even when the molding is performed at a relatively high mold temperature, and that the mold can be easily released at a relatively high temperature because of good releasability.

Further, for heating the mold, a resistance heater, a high-frequency heater, an infrared lamp heater or the like can be used. In particular, from the viewpoint that the recovery time of the mold temperature is short, a high-frequency heater and an infrared lamp heater are preferable. Further, the cooling of the molding die can be performed by a power cut cooling or a cooling gas flowing through the inside of the molding die. In the forming method of the present invention, the softening of the glass material by heating can be performed while the glass material body is levitated by an air current, and the heated and softened glass material is transferred to the preheated mold.

In a low-viscosity region where the glass material is deformed by its own weight, it is very difficult to prevent fusion of the glass with a jig holding the glass material during heating. On the other hand, a gas layer is formed on both the jig surface and the glass surface by ejecting gas from the inside of the jig and causing the glass material to float by the air current. As a result, the jig and the glass react. Without heating, it is possible to soften by heating. Further, when the glass material is a preform, it can be softened by heating while maintaining the shape of the preform. In addition, even if the glass material is a glass gob and has an irregular shape with surface defects such as wrinkles, it is possible to adjust the shape and eliminate surface defects by floating by airflow while heating and softening. is there.

In the present invention, there is no particular limitation on the gas used as the air flow for floating the glass material. However, from the viewpoint that the heated glass material does not react with the jig, and furthermore, from the viewpoint of preventing the heated jig from being deteriorated by oxidation, it is preferable to use a non-oxidizing gas.
Suitably, it is nitrogen or the like. Also, reducing gas,
For example, hydrogen gas or the like can be added.

The flow rate of the air flow can be changed as appropriate in consideration of the shape of the opening for blowing the air flow, the shape and weight of the glass material, and the like. Usually, a gas flow rate in the range of 0.005 to 20 liters / minute is suitable for floating the glass material. However, if the gas flow rate is less than 0.005 liter / min, the glass material may not be able to float sufficiently if the weight of the glass material is 300 mg or more. When the gas flow rate exceeds 20 liters / minute, the glass weight becomes 2000
This is because even in the case of mg or more, the glass on the floating jig shakes greatly, and the shape may change when the glass material is a preform during heating.

The floating of the glass material by the air current is, for example,
This can be performed by an airflow flowing upward from an upper opening having an opening diameter smaller than the diameter of the glass material. As shown in FIG. 2, the upper opening 11 of the floating jig 10 supported by the floating jig support 13 is smaller than the diameter of the glass material 1 and rises from the bottom 12 of the upper opening 11 of the floating jig 10. The glass material l floats on the upper opening 11 by the airflow flowing out, and is held so as not to contact the floating jig 10. The glass material 1 is heated by a glass softening heater 14 provided around the glass material. In addition, the floating jig 10
May have a structure that can be divided into two (each part is denoted by 10a and 10b), as shown in FIG.

Further, the floating of the glass material by the air flow can be performed by an air flow flowing out from a porous surface having a spherical surface or a flat surface approximating the curvature of the outer diameter of the glass material. In particular, when the glass material is a preform, it is effective because the shape of the preform is extremely easy to maintain. Further, when the glass material is a glass gob, the surface defect of the glass gob can be removed by heating while being floated by an air current from the porous surface. For example, as shown in FIG. 3, a porous surface 18 supported by a floating jig support 19 and having a spherical surface approximating the curvature of the glass material l.
The glass material l is held in a floating state by the airflow flowing out of the porous surface 18 on the floating jig 17 having. The floating jig support 19 and the floating jig 17 are shown in FIG.
As in the case of (1), it is also possible to have a dividable structure.

Further, the heating of the glass material includes a case where the glass material is heated from room temperature to a predetermined temperature, a case where a glass material having a certain temperature is further heated, and a case where a glass material already heated to a predetermined temperature is used. For example, when the glass material is a glass gob, a glass goff made of molten glass can be used without cooling.

In the present invention, the transfer of the heat-softened glass material to the preheated mold can be carried out, for example, by suction-holding the glass material to be formed or by dropping the softened glass material. . The suction holding of the glass material can be performed, for example, by a suction holding device 15 having a movable lower opening 16 shown in FIG. The lower opening 16 communicates with, for example, a decompression pump, a vacuum pump, or the like that suctions the inside, and the lower opening 16 can hold the glass material by suction. Floating jig 10
The glass material l heated and softened above is sucked and held in the lower opening 16 of the movable suction holding device 15 and transferred onto the forming surface 40 of the lower mold 34 as shown in FIG. . Next, as shown in FIG. 5, the glass material 1 softened is press-molded with the molding surface 40 of the lower mold 34 and the molding surface 4l of the upper mold 35, whereby the glass molded body 2 can be obtained.

The heat-softened glass material can be transferred by dropping the glass material. The drop of the glass material can be performed, for example, by dividing the floating jig used for heating the glass material into two or more parts and opening the lower part. For example, as shown in FIG. 6, when the glass material 1 is heated on the floating jig 10 and the glass material 1 is softened, as shown in FIG.
Is horizontally divided into two portions 10a and 10b and moves in opposite directions (left and right in the figure), so that the glass material l falls. At this time, the lower mold 3 is provided by installing the lower mold 34 as a receiver for the falling glass material l.
The glass material 1 can be transferred onto the molding surface 40 of the fourth step.

Further, in the present invention, guide means can be used for the purpose of dropping and moving the heat-softened glass material onto a predetermined molding surface. For example, as shown in FIGS. 6 and 7, a cylindrical guide means 50 (individable portions 50a and 50b) having an inner diameter dimension capable of maintaining an outermost diameter of the glass material l and an appropriate clearance can be provided above the floating jig 10. The glass material l can be dropped to the center of the mold. However, the structure of the guide means is not particularly limited as long as it can prevent the glass material from being displaced when the floating jig is divided and moved. For example, the present invention is not limited to a cylindrical shape, and may be a plurality of pipes arranged in a lattice or two or more plates facing each other. In addition, the guide means may have a structure that can be divided and moved in consideration of the fact that the upper mold moves onto the lower mold holding the glass material and performs pressure molding during molding.

There is no particular limitation on the method of dividing and moving the floating jig used to heat the glass material. For example, when the floating jig moves horizontally as described above, the
Divided into four or four directions and moved in three directions (different directions by 120 degrees) or four directions (different directions by 90 degrees)
Glass material can also be dropped. By dropping and moving the heat-softened glass material, the glass material can be transferred into the mold in a short time. The production method of the present invention can be applied to the production of optical elements such as lenses, prisms, diffraction gratings, and fiber guide blocks.

[0052]

Next, the present invention will be described in more detail with reference to Examples.
Will be described. Example 1Press mold  As shown in Fig. 1, the press mold is used as a base material.
Using silicon carbide (SiC) sintered body 31, grinding
After processing into a less mold shape, the molding surface is further
Forming silicon carbide film 32 and grinding and polishing
Mirror-finished to the shape corresponding to the glass compact to be
The mold base was obtained. Furthermore, the silicon carbide film 3 of the mold base
2 on top of i-carbon (diamond-like carbon)
The film 33 is formed to a thickness of 500 by the ion plating method.
Φ16mm (φ14m after centering)
m) A lower mold 34 for a lens was obtained.

The upper mold 35 shown in FIG. 5 was also obtained by the same method as the lower mold 34. The upper mold 35 and the lower mold 34 are
As shown in FIG. 5, a molding die 39 is formed of an upper die 35, a lower die 34, and a guide die 36 that guides the lower die 34 and the lower die 34 during press forming. Further, on the upper surface of the upper mold 35, a push rod 45 for secondary pressurization is provided. The lower mold 34 and the upper mold 35 are heated by a mold heater 44 attached to the outer periphery of the body mold 37,
Is controlled by a mold-side temperature thermocouple 42 inserted into the lower mold 34 from the lower part of the mold. Further, the temperature of the body die 37 is side-heated by the body-side heating thermocouple 43 inserted into the body die 37.

[0054]Floating jig and transfer means  The same closed chamber with the mold heating mechanism described above (Figure
(Not shown), a floating jig and transfer means shown in FIG.
Have been killed. Use a glass material (prefor
A glass softening heater 14 for heating and softening l is provided.
The glass softening heater 14 has a floating jig support
Glassy carbon levitation jig set in l3
(Hereinafter, referred to as “GC floating jig”).
Further, whether the glass material l is inside the floating jig support 13 or not.
98% N supplied to the lower part of GC floating jig 10₂+2
% H₂Gas or N₂Levitated and held by gas jet
You. Also, besides the glass softening heater 14,
Glassy carbon vacuum pack
DO15 (hereinafter referred to as "GC vacuum pad")
Usually, it is on standby above the GC floating jig 10.

[0055]Preheating and pressing process  A closed chamber containing a mold and a floating jig (shown
After evacuating the inside, the 98% N₂+ 2% H₂
Gas or N₂Gas is introduced, and the same gas is
Atmosphere. Next, from the barium shelf silicate optical glass
Preform 1 (a marker having a mirror surface without surface defects)
Bull shaped hot molded product, weight 1000mg, thickness 7mm, rolled
Transfer point 514 ° C., yield point 545 ° C.)
A lens and a concave meniscus lens were manufactured. The result
It is shown in Table 1.

[0056]

[Table 1]

The mold heater 44 measures 1 m from the molding surface of the upper mold 35 and the lower mold 34 measured by the thermocouple 43 for mold temperature measurement.
Heat until the temperature of the portion inside the m (molding mold temperature) reaches a temperature corresponding to the viscosity of the glass shown in Table 1 and maintain the same temperature. On the other hand, the glass softening heater 14 heats the temperature of the glass preform 1 on the GC floating jig 10 to a temperature corresponding to the viscosity of the glass shown in Table 1 to soften the glass. The relationship between the viscosity of glass and the temperature is as follows.

Relationship between viscosity and temperature Viscosity of glass Temperature 10 ^6.5 poise 647 ° C. 10 ⁷ poise 628 ° C. 10 ^7.3 poise 618 ° C. 10 ^7.5 poise 611 ° C. ^107.7 poise 605 ° C. 10 ^7.9 poise 599 ° C 10 ⁸ poise 596 ° C 10 ^8.2 poise 590 ° C 10 ^8.3 poise 588 ° C 10 ^8.4 poise 585 ° C 10 ^8.7 poise 578 ° C 10 ^9.1 poise 569 ° C 10 ^9.3 poise 565 ° C 10 ^9.8 Poise 556 ° C

Then, the floating-softened preform 1 is
The GC vacuum pad 15 waiting above the GC floating jig 10 outside the glass softening heater 14 descends to the preform 1 and holds it by suction. At this time, the temperature of the GC vacuum pad is heated to 300 to 400 ° C. by the radiant heat from the glass softening heater 14, but since the temperature is low, the glass does not fuse.

Next, as shown in FIG.
The GC vacuum pad 15 holding the preform 1 quickly moves to above the lower mold 34, descends again to near the molding surface 40 of the lower mold 34, stops suction, and stops the preform 1 on the molding surface 40 of the lower mold 34. Is placed. Thereafter, the GC vacuum pad 15 retreats above the lower mold 34 and returns to the original standby position, so that there is no obstacle at the upper part of the lower mold 34, and the molding die support 38 instantaneously moves the lower mold 34 to the lower mold 34. 34
Is raised to the upper die 35 fixedly set together with the molding die support base 38 above the same axis.

As shown in FIG. 5, a molding die 39 composed of an upper die 35, a lower die 34 and a guide die 36 for guiding them.
Inside, the preform 1 is press-molded at the respective times and pressures shown in Table 1, and when the flange portion of the lower mold 34 and the bottom surface of the guide mold 36 are in contact with each other, the thickness of the preform 1 is reduced by 30 from the thickness of the final product.
The thickness is larger by μm. Next, the mold heater 44 is turned off to cool at the respective cooling rates shown in Table 1. On the other hand, at the same time when the pressurization by the first cylinder is completed, the pressure shown in Table 1 is applied to the back surface of the upper mold 35 by the push rod 45 connected to the second cylinder inside the first cylinder. To hold the glass molded body 2 and the molding die 39 under pressure. Thereafter, when the temperatures of the upper mold 35 and the lower mold 34 measured by the thermocouple 42 for mold temperature measurement reach the temperatures shown as the mold release temperatures in Table 1, and when the glass molded body 2 has a predetermined thickness, The glass molding 2 was released from the molding die 39 and taken out. The relationship between the viscosity of glass and the temperature is as described above.

The glass compact 2 thus obtained
(Outer diameter 16mm, center thickness 2.6mm, edge thickness 1.0m
The performance after annealing of a convex meniscus lens having an outer diameter of 15 m, a concave meniscus lens having an outer diameter of 15 mm, a center wall thickness of 1.3 mm, and an edge thickness of 3.0 mm (Table 1) was evaluated by measuring the surface accuracy with an interferometer, the visual appearance, and When the surface condition was evaluated by a stereoscopic microscope, all the lenses were less than one lens and had good surface quality.

Example 2 A meniscus lens and a concave meniscus lens were manufactured in the same manner as in Example 1 except that the marble shape was changed to a spherical shape. The preform used at this time was the same glass type as in Example 1, weighed 1000 mg, and was a spherical hot-formed product having a diameter of 8.742 mm and a mirror surface having no surface defects. Table 2 shows the manufacturing conditions.

[0064]

[Table 2]

The glass molded body thus obtained (outer diameter 16 mm, central wall thickness 2.6 mm, convex meniscus lens with edge thickness 1.0 mm, outer diameter 15 mm, central wall thickness 1.3 mm, edge thickness 3.0 mm concave meniscus lens)
The performance after annealing in Table 2 was evaluated for surface accuracy using an interferometer, visual appearance, and surface state using a stereomicroscope. As a result, each lens was less than one lens and had good surface quality.

Example 3 After planar polishing, a planarly polished coating was placed between a disk-shaped lower die having fine grooves of 1 μm width and 0.1 μm depth formed on the surface and an upper die which had been planarly polished. A molded glass material is placed, and the glass material to be molded on the lower mold is heated and softened by a heater, and then pressure-molded with an upper mold and a lower mold to obtain a fine pattern transfer product having an outer diameter of 50 mm ( See FIG. 12). The molding conditions were the same as No. 9 in Table 1.

In the above embodiment, the cycle time of press molding is the sum of the molding time and the recovery time of the mold temperature (the temperature rise time from the temperature at the time of release from the temperature at the time of mold release). In this example, since the resistance heating was used for heating the mold, the recovery time was about 50 seconds. Therefore, the cycle time was about 100-250 seconds. In addition, by using high frequency heating or infrared heating for heating the mold,
The recovery time can be about 20 seconds, and the cycle time can be shortened accordingly.

[0068]

The method for producing a glass optical element according to the present invention comprises:
During press molding, the temperature (viscosity) of the glass material to be molded
In order to maintain a constant relationship between the temperature of the mold and the mold, press processing is started after heating these to a predetermined temperature in advance, so that a glass optical element with excellent surface accuracy can be manufactured, and with a high precision press. In addition, the cycle time of the press forming process can be shortened. In particular, in the method for manufacturing a glass optical element of the present invention, the center thickness of the glass molded product is 70% or less of the center thickness of the glass material under the above temperature conditions of the glass material to be formed and the molding die. Because it is molded by pressurizing, even if a glass material having a shape different from the final molded product is greatly deformed by press molding,
With a relatively short cycle time, it has become possible to manufacture a glass optical element having better surface accuracy than conventional products. Further, according to the present invention, since the glass material to be formed is transferred to the press forming step in a state where the glass material is heated and softened while being floated by an air current, it is possible to completely prevent the surface of the glass material from being damaged, which is more excellent. A glass optical element having improved surface accuracy can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a lower mold of a molding die used in the present invention.

FIG. 2 is a schematic explanatory view of a method of softening and transferring a glass preform on a floating jig used in the present invention.

FIG. 3 is a schematic explanatory view of a method for softening the floating of a glass preform on a floating jig used in the present invention.

FIG. 4 is a schematic explanatory view of a method for transferring a softened glass preform to a molding die.

FIG. 5 is a schematic explanatory view of pressure molding with a molding die used in the present invention.

FIG. 6 is a schematic explanatory view of a method for transferring a softened glass preform to a molding die.

FIG. 7 is a schematic explanatory view of a method for transferring a softened glass preform to a molding die.

FIG. 8 is a graph for explaining the first method of the present invention.

FIG. 9 is a graph for explaining a second method of the present invention.

FIG. 10 is a graph for explaining a third method of the present invention.

FIG. 11 is a graph for explaining a fourth method of the present invention.

FIG. 12 is an explanatory diagram of the method for manufacturing the optical element in the third embodiment.

[Explanation of symbols]

 l ... Glass material 2 ... Glass molded body l0, l7 ... Floating jig lOa, lOb ... Divided floating jig l1 ... The upper opening of the floating jig l2 ... Floating jig Bottom of upper opening l3, l9 ... floating jig support l4 ... heater for softening glass l5 ... suction holding device l6 ... lower opening l8 ... porous surface 34 ... Lower mold 35 ... Upper mold 36 ... Guide mold 37 ... Body mold 40, 4l ... Molding surface 45 ... Push rod 50a, 50b ... Guide means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-236829 (JP, A) JP-A-9-118530 (JP, A) JP-A-9-48621 (JP, A) JP-A 8- 325022 (JP, A) JP-A-8-133758 (JP, A) JP-A-8-40733 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 11/00-11 / 16

Claims (12)

(57) [Claims] 1. A heat-softened glass material to be molded is applied to a molding die including an upper mold and a lower mold until the center thickness of the glass molded body becomes 70% or less of the center thickness of the glass material to be molded. A method for producing a glass optical element, comprising a step of pressing and forming a glass molded body, wherein the glass material to be molded is heated and softened to a temperature at which the glass material to be molded exhibits a viscosity of Y poise, The softened glass material to be molded
Introducing the average temperature of the molding surface of each of the upper mold and the lower mold to a molding die adjusted to a temperature at which the glass material to be molded exhibits a viscosity of X poise to perform the pressure molding;
And a method of producing a glass optical element, wherein the viscosity Y satisfies the following expression. logX <10 logY ≧ 6.5 Y <X −logX + 14.5 ≦ logY ≦ −logX + 18 2. A method for producing a glass optical element, comprising a step of pressure-forming a heat-softened spherical glass material to be molded into a glass molded body by using a molding die including an upper die and a lower die, The molded glass material, a step of heating and softening the molded glass material to a temperature indicating the viscosity of Y poise, and the heated and softened molded glass material, the average temperature of each molding surface of the upper mold and the lower mold, The method further comprises the step of introducing the glass material to be molded into a molding die adjusted to a temperature indicating the viscosity of X poise and performing the pressure molding, and wherein the viscosity X and the viscosity Y satisfy the following formula: A method for manufacturing a glass optical element. logX <10 logY ≧ 6.5 Y <X −logX + 14.5 ≦ logY ≦ −logX + 18 3. A method for producing a glass optical element, comprising a step of pressure-forming a heat-softened spherical glass material to be molded into a glass molded body by using a molding die including an upper die and a lower die, In the pressure molding, the molded glass material is a temperature at which the molded glass material exhibits a viscosity of Y Poise, and the average temperature of each molding surface of the upper mold and the lower mold is equal to or less than the average temperature of the molded glass material. A method for producing a glass optical element, wherein the method starts when the viscosity is X poise and the viscosity X and the viscosity Y satisfy the following formulas. logX <10 logY ≧ 6.5 (however, when 9.0 ≦ logX <10, logY> 7.0) Y <X−logX + 14.5 ≦ logY ≦ −logX + 18 4. A method for manufacturing a glass optical element, comprising a step of forming a glass material by heating and softening a glass material to be formed with a forming die including an upper die and a lower die. In the molding, the glass material to be molded is a temperature at which the glass material to be molded exhibits a viscosity of Y poise, and the average temperature of each molding surface of the upper mold and the lower mold is such that the glass material to be molded is X poise. A method for producing a glass optical element, wherein the method is started when the viscosity X and the viscosity Y satisfy the following formulas at a temperature indicating a viscosity. logX <9 logY ≧ 6.5 Y <X logY ≧ −logX + 14.5 5. The method according to claim 1, wherein the pressing is performed until the center thickness of the glass molded body becomes 50% or less of the center thickness of the glass material to be formed. 6. An average temperature of each molding surface of the upper mold and the lower mold,
The temperature of the glass material to be formed is 10 ° C. or lower.
6. The production method according to any one of 5. 7. The production method according to claim 1, wherein the molding surface temperature of the upper mold is lower by 5 to 40 ° C. than the molding surface temperature of the lower mold. 8. The temperature around the molding surface of the mold is 20 to 180 ° C. /
The method according to any one of claims 1 to 7, wherein the cooling is performed at a cooling rate of one minute. 9. During cooling after pressurizing the glass material to be molded,
The secondary pressurization at a pressure lower than the pressurization and at a pressure of 10 to 100 kg / cm ² and / or 0.001 to 1 kg / cm ^2.
9. The production method according to any one of items 1 to 8. 10. The production method according to claim 1, wherein the glass material to be molded is softened by heating while being floated by an air current. 11. The method according to claim 1, wherein the heat-softened glass material is transferred to a preheated molding die by sucking and holding the molded glass material or by dropping the glass material.
0. The production method according to item 0. 12. The manufacturing method according to claim 11, wherein the heating and softening glass material is dropped by dividing a floating jig used for heating the glass material into two or more parts.