JP2000302473A - Optical element, and production of formed glass lump for production of the optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a formed glass lump highly accurately transcribing the shape accuracy of a mold in the order of μm, and having a high-quality surface state utilizable as a material for producing an optical element by using the porous mold. SOLUTION: This method for producing a formed glass lump for producing an optical element by using a pair of porous molds 1, 1, receiving a molten glass lump on a molding surface, and carrying out the press-molding of the molten glass lump in a noncontact state by the gas spouting from the molding surface to provide a desired shape comprises bringing a part of the surface to be molded into contact with the molding surface of the porous mold to transcribe the shape of the surface of the mold, and holding the other part by the gas spouting from the molding surface of the mold to keep the noncontact state, to carry out the press-molding of the formed glass lump 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and a method for producing a molded glass lump for producing the optical element.

[0002]

2. Description of the Related Art Conventionally, an optical element such as a lens used for an optical device is prepared by first grinding a material for manufacturing an optical element into a rough shape approximate to the outer shape of the optical element, and then polishing the processed surface. Processed and smoothed to obtain the desired shape. Further, such a material for manufacturing an optical element can also be obtained by press-forming a softened optical glass with a molding die composed of a pair of upper and lower dies. This mold is generally made of heat-resistant stainless steel.

[0003] When press-molding a softened optical glass, in order to prevent the glass from being fused to the mold, a release agent made of powdery boron nitride or the like is applied to the surface of the mold. And then, press forming. Further, in order to prevent fusion between the glass and the mold, press molding is performed while the mold temperature is considerably lower than the temperature of the softened glass.

[0004] The material for producing an optical element obtained by press forming in this manner has a mold release agent powder embedded in its surface and is cooled by a low-temperature mold. There is a large undulation on the glass surface. Then, the large undulation and the release agent on the glass surface are removed by a subsequent grinding process.

On the other hand, recently, a technique for directly obtaining an optical element by pressing a softened optical glass lump with a pair of molding dies has been developed. In particular, this method is also used for manufacturing an aspheric lens, which is difficult to manufacture by a conventional polishing method. By using the aspheric lens thus obtained for an optical system, miniaturization and high precision of an optical device have been achieved.

[0006] The molding die used in this molding method is made of ceramics or cemented carbide, and its molding surface is polished smoothly. Then, a carbon film having a releasing effect is generally formed as a release film on the polished molding surface, and is used in this state.

[0007] The surface of the molded glass lump (optical glass lump) used here must be smooth and free from foreign matter and the like. Further, the shape of the formed glass lump is preferably a middle contact shape as compared with the shape of the forming die. This is because, during press molding, the transfer and molding to the glass block proceeds from the center of the molding surface to the periphery thereof. That is, by performing press molding in this way, it is possible to avoid a phenomenon in which gas is trapped between the molding surface and the surface of the glass lump in the molding surface.

As a method for producing such an optical glass lump, Japanese Patent Publication No. 22857/1992 discloses a method of receiving molten glass flowing out of a nozzle in a molten state on a receiving mold made of heat-resistant stainless steel. A technique for obtaining an optical glass lump is disclosed. In this way, the obtained optical glass lump is rapidly cooled by the receiving mold, so that the surface in contact with the receiving mold shrinks, and macroscopic undulation occurs. In addition, it is described herein that even when such a macroscopic undulating optical glass block is used, a phenomenon in which gas is trapped during molding does not occur.

However, according to the study of the present inventor,
When press molding such an optical glass block having macroscopic undulations, gas is often generated during molding due to the relationship between the size and shape of the undulations, the shape of the optical glass block, and the shape of the final molded optical element. There were cases that were trapped.

Therefore, the following method is used as a method for obtaining an optical glass lump having no macroscopic undulation on its surface and a low cost. That is, the molten glass flowing out in a molten state is received on a receiving mold made of a porous material, and the receiving mold is made of a porous material,
By blowing gas from the receiving surface, the glass is solidified while keeping the glass in a non-contact state with the receiving mold, and a required amount of optical glass block is obtained. The optical glass lump thus obtained has no macroscopic undulation on its surface, is smooth, has convex surfaces on both sides, and has a slightly flat shape.

Further, as disclosed in JP-A-59-195541, when a softened optical glass block is press-formed with a pair of forming dies to obtain an optical element, a molding made of a porous material is used. Using a mold, the gas is ejected from the molding surface of this mold, and press molding is performed through the gas film generated on the molding surface without contacting the softened optical glass and the mold. There is also known a technique for obtaining an optical element. By pressing the optical glass lump in a non-contact state through such a gas film, fusion of the glass and the mold can be prevented, and deterioration of the mold can be prevented.

[0012]

However, the above conventional example has the following problems. (1) Polishing method As described above, conventionally, in order to obtain an optical element by polishing, a press-formed optical element material has large undulations generated by rapid cooling in a molding die on its molding surface. There is adhesion of the release agent, and in order to remove these, the surface to be molded of the material, by grinding, a considerable amount to a certain shape,
Specifically, about 0.5 mm to 1 mm per surface,
It had been ground and removed.

On the other hand, the optical glass contains lead for increasing the refractive index and toxic substances such as arsenic and antimony as defoaming agents at the time of melting. Therefore, if the fine grinding dust (sludge) such as powder generated by grinding the surface of the optical element material is discarded as it is, the poisonous substances contained therein are eluted by moisture, and the soil environment There is a fear of causing pollution.

In order to detoxify the grinding dust such as powder, the grinding dust may be melted and then solidified into a glassy lump. However, the detoxification treatment of the grinding waste has a disadvantage that it costs a lot. In particular, when producing lenses by polishing overseas, it is very difficult to detoxify grinding dust (sludge) because there is no apparatus.

That is, when an optical element is obtained by polishing, the surface of the material must be largely removed by grinding, and the grinding waste (sludge) generated there is toxic. Will be invited,
There is a disadvantage of saying. (2) Method of press-molding a glass lump In a method of receiving a molten glass in a non-contact state on a porous receiving mold and thereby obtaining a molten glass lump adjusted to a predetermined amount, the method was obtained. Since the entire surface of the glass block is formed of a free surface and its shape is determined by the balance between the surface tension of the molten glass and its own weight, the glass block usually has a biconvex and slightly flat shape.

However, the shape of the lens is a thin biconvex, convex meniscus, or concave lens, and there is a great difference between the shape of the above-mentioned glass block as a material and the shape of a lens molded therefrom. That is, if such a glass lump is used as it is as a press material, the amount of press deformation during lens production increases. On the other hand, a thin carbon film is generally formed on a molding surface of a mold as a release film having a release effect.

Therefore, when press molding a glass block,
Along with the press deformation, a shear force acts at the interface between the molding surface of the molding die and the molding surface of the molded product, so if the press molding in such a state is repeated, the molding surface of the molding die is deformed. The formed carbon thin film is consumed. In particular, when the difference between the shape of the pressed glass body and the shape of the lens to be molded is large, the carbon thin film is greatly consumed, and only about 100 molding operations are performed, and the carbon thin film disappears. I will.

That is, when an optical element is obtained by press-molding a glass lump, if the shape difference between the glass lump as a molding material and the lens to be molded is large, the separation formed on the molding surface of the molding die is large. There is a disadvantage that the durability of the mold film is deteriorated. (3) Method of press-molding molten glass lump with porous mold If the molten glass lump is press-molded in a state where gas is jetted from the pores of the porous molding die, the mold and molten glass do not come into contact with each other. Since press molding proceeds, it is considered that molding can be performed without deterioration of the mold. However, this method has a drawback that it is difficult to obtain optimum molding conditions.

That is, when the flow rate of the gas ejected from the pores of the porous mold is small, the molten glass penetrates the pores of the porous mold, and conversely, when the flow rate of the gas is large. Although there is no biting into the mold, the shape of the glass surface that should conform to the shape of the mold departs from the shape of the mold due to gas pressure and is greatly deformed. Therefore, the molded glass obtained by this method has low shape accuracy,
It is difficult to use as an optical element.

The present invention has been made based on the above circumstances, and a main object of the present invention is to transfer the shape accuracy of a mold with high accuracy in the order of μm, and to use a high-quality material usable as a material for manufacturing an optical element. An object of the present invention is to provide a method for producing a molded glass lump in a surface state using a porous mold.

Another object of the present invention is to obtain a molded glass lump suitable as a material for manufacturing an optical element, and to remove the surface of the molded glass lump by polishing to obtain an optical element. In a manufacturing method, it is to reduce the amount of glass dust to be removed, and to reduce the amount of press deformation when an optical element is manufactured from a molded glass lump by press molding.

[0022]

In order to achieve the above object, according to the present invention, a pair of porous molds is used to receive a molten glass lump on a molding surface thereof, and use a gas ejected from the molding surface. In the method for producing a molded glass lump for producing an optical element, the molten glass lump is press-molded in a non-contact state with respect to the molding surface to obtain a desired shape. A part of the molding surface is brought into contact with the molding surface of the porous mold, and the shape of the molding surface is transferred, and the other part is held by gas ejected from the molding surface of the molding die. It is characterized by being maintained in a non-contact state and being press-formed.

According to such a manufacturing method, the molten glass ingot is press-formed using a pair of porous molds in a state where gas is jetted from the molding surface, and the molded glass ingot having a desired shape is formed. When the flow rate of the gas ejected from the molding surface is sufficiently reduced when obtaining the material, the thickness of the void formed by the molding surface of the mold and the molding surface of the glass lump is reduced, and the material particles forming the porous material are reduced. The irregularities of the molding surface of the porous mold corresponding to the pores and the pores therebetween are transferred to the molding surface of the molded glass lump and slightly irregularized.

That is, the projections of the raw material grains in the molding surface of the porous molding die are transferred as the depressions of the molded glass lump, and as a result, the molding surface of the molded glass lump is slightly uneven. In addition, since the pressure of the gas ejected from the molding surface of the mold contributes here, the glass does not penetrate into the pores of the porous mold. Further, due to the action of the gas pressure, the convex portion of the material grain does not come into contact with the concave portion of the molded glass lump, and a slight gap is maintained between them. In this way, the formed glass lump formed in a state in which the forming surface of the formed glass lump is slightly uneven maintains a geometric relationship such that the protrusions of the material grains form the recesses of the formed glass lump. Cooled down.

In this state, the molded glass block is cooled to the removal temperature, and the molded glass block is removed by opening the mold.
Until immediately before the mold opening, the molded glass lump is lightly constrained by the projections of the material particles of the porous molding die, so its shape is a shape formed by the porous molding die, that is, Thus, the shape becomes almost similar to the finally formed optical element. When such a molded glass lump is used as a material for an optical element for polishing, the shape of the material and the shape of the optical element are approximated, so that the amount of grinding dust (sludge) removed by the polishing is reduced. be able to.

In addition, since the surface of the molded glass lump has only a small amount of unevenness, the molded glass lump is heated and softened and pressed to obtain a molded optical element. Due to the deformation at the time, the unevenness is eliminated and the surface becomes smooth. The molding optical element thus obtained has a smooth surface to be molded, and by approximating the shape of the molding material and the shape of the molding optical element, the amount of pressing can be reduced from that point as well. In the embodiment, it is preferable that the molding is performed so that the difference in shape between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block is 100 μm or less.

For this reason, in the present invention, a part of the molding surface where the molded glass block comes into contact with the molding die and another part which is not in contact with the molding die are substantially uniform over the entire molding surface. Being pressed in a mold so as to be distributed in
In addition, the area of a part of the molded glass block in contact with a molding die occupying the molding surface is 50% or less of the molding surface, and the remaining area is other than non-contact with the molding die. It is preferred that the molded glass block is formed on a molding surface so as to be occupied by a portion.

In the present invention, the forming surface is preferably formed such that the surface roughness of the forming surface of the formed glass lump is within a range of Ra = 0.05 μm to 20 μm.
It is effective in the following points.

That is, by setting the surface roughness of the surface of the molded glass block to be Ra = 20 μm or less, when the molded glass block is used as a material for molding an optical element, the molding of the molded glass block is performed. It is possible to prevent the gas from being formed in a state where the gas remains in the concave portion of the surface. Further, when the surface roughness of the molding surface of the molded glass lump is in the above range of Ra = 0.05 μm or more, the molded glass lump is used as a raw material for manufacturing an optical element by grinding, or grinding and grinding. When used, the surface to be formed of the formed glass lump can be reliably polished, or ground and polished.

By the way, the surface to be formed of a smooth formed glass lump having too small surface roughness is not effectively polished by the abrasive grains, and the lapping or the lapping and the lapping are surely performed. May not be possible.

In order to form the surface to be molded having such a surface roughness, in the present invention, the surface roughness of the molding surface of the porous mold is adjusted so that Ra = 5 μm to Ra100 μm. , Constituting the molding surface. The porous mold used for this purpose is preferably made of a porous material having a porosity of 35% or less and an average pore diameter of 50 μm or less.

Further, compared to the surface roughness of the porous mold,
Adjusting the flow rate of the gas ejected from the molding surface of the porous mold so as to reduce the surface roughness of the molded glass lump is most effective in realizing the method of manufacturing the molded glass lump.

That is, if the flow rate of the gas ejected from the molding surface of the molding die is small, the glass penetrates into the pores of the molding surface of the molding die when obtaining a molded glass lump, and the surface roughness of the porous mold is reduced. The surface roughness of the formed glass block becomes almost the same.
In this case, it is difficult to remove the molded glass lump from the porous mold. Further, when such a molded glass block is used as a molding material for molding an optical element, there is a fear that residual gas may be generated at an interface during molding due to irregularities on the molding surface of the molded optical element.

Therefore, in order to prevent such a phenomenon and form the molded glass block so that the surface roughness becomes smaller than the surface roughness of the porous mold, it is necessary to adjust the gas flow rate described above. Is the most effective.

For this reason, in the present invention, the approach speed (press speed) of a pair of porous molds is set so that the surface to be molded of the molded glass block is slightly uneven with a desired surface roughness. Further, the flow rate of the gas ejected from the molding surface of the porous mold is controlled at a desired time to a desired value. This makes it possible to obtain a molded glass lump whose molding surface is slightly uneven with a desired surface roughness, that is, a molded glass lump more suitable as a material for manufacturing an optical element.

That is, for example, if the pressing speed is too high, or if the gas flow rate is too small, the glass penetrates into the pores of the mold, which is not preferable. Conversely, if the pressing speed is too slow, or if the gas flow rate is too large, the molding surface of the glass lump is not slightly uneven,
Non-contact and smooth surface, but the shape of the molding surface is
The mold is largely separated from the shape to be transferred. In order to prevent these, the above-described means for controlling the press speed and the gas flow rate to have desired numerical values at a desired time is effective.

For the production of the optical element, it is effective as an embodiment that the surface roughness of the molded glass block is 1/5 or less of the surface roughness of the porous mold. In this case, there is no fear that gas remains at the interface between the molding surface of the molding die and the molding surface of the glass lump during press molding of the molded glass lump. In addition, removal from the porous mold is performed smoothly.

As described above, a molded glass lump having a shape approximating the shape of a finished product is employed as a material for an optical element, and the surface to be molded of the molded glass lump is polished or ground and polished. Thus, when an optical element is obtained, the amount of processing removal (the amount of harmful sludge) can be significantly reduced, and the processing time can be shortened.

The molded glass lump obtained by the above-mentioned method for producing a molded glass lump whose surface to be molded is slightly uneven is heated to a temperature at which it is softened, and pressed with a pair of precision molding dies. In the process of molding, obtaining a molded optical element having a desired shape excluding the irregularities is because the press amount can be reduced, the wear and damage of the release film on the molding surface of the mold are reduced, and the life of the mold is improved. And the effect of shortening the press time can be obtained.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) In a first embodiment of the present invention, a molten glass block is formed by using a pair of upper and lower porous forming dies through pores on the forming surface thereof. Press molding in a state where the gas is jetted, to obtain a molded glass lump in a state where the molding surface is slightly uneven, and polishing or grinding the molding surface of the molded glass lump. It is intended to obtain an optical element by removing it by polishing, which will be specifically described below.

That is, in FIG. 1, reference numeral 1 denotes a molding die made of a porous material, 2 denotes a molded glass block pressed by the porous molding die 1, and 3 denotes a porous molding die. This is a gas supply chamber for supplying gas ejected from the molding surface, and the gas supply chamber 3 is formed on the back surface of the porous mold 1. Reference numeral 4 denotes a gas supply pipe for supplying gas to the gas supply chamber 3, and reference numeral 5 denotes a holding block which holds the porous mold 1 and serves to form the gas supply chamber 3. The porous mold 1, the gas supply chamber 3, the gas supply pipe 4, and the mold holding block 5 that constitute the upper and lower dies have substantially the same configuration in both the upper and lower dies.

FIG. 2 is a diagram for explaining the schematic configuration of the control unit of the apparatus used in the first embodiment of the present invention. FIG.
In the figure, reference numeral 1 denotes a porous mold, 4 denotes a gas supply pipe, and 6 denotes a gas for controlling a gas supplied to the porous mold 1 through the gas supply pipe 4 to a desired flow rate. A mass flow controller 7 is a gas supply unit for supplying gas to the mass flow controller 6. In addition,
The configuration of the series of gas flow control units is substantially the same for both the upper and lower molds.

In FIG. 2, reference numeral 8 denotes a one-axis NC (numerical control) driving device for controlling the pressing speed, that is, the moving speed and the moving position of the molding die to desired numerical values. In FIG. 2, the NC driving device 8 is connected to the lower die of the porous molding die 1 to control the moving speed of the lower die and the press speed. NC
The driving device 8 may be connected.
Press control may be performed by connecting a C drive device.

In FIG. 2, reference numeral 9 denotes a computer for setting desired settings of the gas flow rate and the press speed of the upper and lower molds. Reference numeral 10 denotes a sequencer for controlling the operation of this device. Desired set values set by the computer 9 are stored in the sequencer 10 as data of the sequencer 10. Reference numeral 11 denotes a controller for controlling the mass flow controller 6 or the NC driving device 8 based on a signal from the sequencer 10.

Then, by using the sequencer 10, the controller 11, and the mass flow controller 6, the flow rate of the gas ejected from each of the upper and lower porous molds 1 is reduced.
The desired value can be controlled at a desired timing during the molding process. Further, by using the sequencer 10, the controller 11, and the NC driving device 8, the pressing speed by the upper and lower dies, that is, the die position and the moving speed can be controlled to desired values at desired timings during the molding process. . These desired values can be easily changed by the computer 9.

FIG. 3 is an electron micrograph of a porous material as a material of the porous mold 1 according to the embodiment of the present invention. Here, a micrograph of Porous Carbon VCP-10 manufactured by Nippon Carbon Co., Ltd. is shown, and this photograph is reprinted from a catalog of Porous Carbon of the same company. As can be seen from FIG. 3, the porous material is formed by gathering fine spherical material particles, and is formed as a porous material by partially connecting the material particles. I understand. The porous material used in the present invention is not limited to the porous carbon VCP-10, and it goes without saying that other materials may be used.

FIG. 4 is a view for explaining a state in the vicinity of the forming surface of the porous mold and in the vicinity of the forming surface of the glass while the glass is being formed in this embodiment. In FIG. 4, reference numeral 2 denotes a part of the shaped glass block in the vicinity of the surface to be formed, and reference numeral 12 denotes spherical material particles constituting a porous forming die.

FIG. 5 shows data obtained by measuring the shape of the molding surface of the porous mold 1 with a form Talysurf, a shape measuring instrument manufactured by Rank Taylor Hobson. FIG. 6 shows data obtained by measuring the shape of the molding surface of the molded glass lump 2 obtained here. Further, FIG. 7 shows measurement data of the shape of the entire molding surface of the porous lower mold 1 used in this embodiment. Similarly, FIG. 8 is data obtained by measuring the shape of the entire lower surface of the obtained molded glass lump 2 to be molded, FIG. 9 is data obtained by measuring the shape of the entire molding surface of the porous upper mold 1, and FIG. 4 shows data obtained by measuring the shape of the entire upper surface of the obtained molded glass lump 2 to be molded.

Next, a method for producing a molded glass lump according to the present invention will be described below. Here, first, optical glass melted in a glass melting crucible (not shown) is dropped from its outlet (not shown) via an outflow pipe connected to the lower part of the glass melting crucible. Outflow. Then, a porous lower mold 1 is installed at a position directly below the outlet of the outflow pipe. In the porous lower mold 1, high-pressure gas is supplied from a gas supply pipe 4 to the gas supply chamber 3, and this gas is ejected from the upper surface (molding surface) of the lower mold. At this time, the gas ejected from the porous molding surface is controlled to a desired flow rate by the mass flow controller 6.

The molten glass flow is received on the molding surface of the lower mold 1, and when the received molten glass lump has a desired weight, the lower mold 1 is lowered by a predetermined amount. This allows
The molten glass stream is constricted at this point and is immediately cut naturally. The molten glass lump thus obtained (not shown)
The upper and lower surfaces are free surfaces, have a very smooth surface to be molded without cutting scratches, and are placed on the porous lower mold 1 in a non-contact state with the molding surface, that is, in a floating state. Is held in.

Subsequently, the porous lower mold 1 holding the molten glass lump (not shown) in a floating state is moved to the porous upper mold 1.
To the position below. Therefore, the porous lower mold 1 is raised by using the NC driving device 8 to approach the porous upper mold 1. As the approach proceeds further, the molten glass lump proceeds to press-deform via the gas film in accordance with the shapes of the molding surfaces of the porous upper mold 1 and lower mold 1. And finally,
When the press deformation is completed, the shaped glass lump 2 having the desired shape is formed.
Is obtained. The situation at that time is as shown in FIG.

At this time, the pressing speed is controlled by the NC driving device 8 so as to be a desired speed set in advance by the computer 9. In addition, porous upper mold 1
The gas ejected from the lower mold 1 is controlled by the mass flow controller 6 so as to have a desired flow rate set in advance by the computer 9.

Therefore, during the press molding and at the time of completion of the press, a part of the surface irregularities is in contact with the other part, and the other part is not in contact via the gas film. A large gap is formed between the molding surface of the porous molding die and the molding surface of the molding glass lump without greatly penetrating into the pores of the molding surface of the porous mold. There is no fear that the molding surface of the molded glass block becomes smooth.

That is, the molding surface of the molded glass lump 2 obtained in this embodiment is, as schematically shown in FIG. 4, a convex surface of the outermost surface of the molding surface of the spherical material particles forming the porous mold. A recess is formed by slightly transferring the portion. At this time, the high-pressure gas supplied to the gas supply chamber 3 provided on the back of the porous mold 1 passes through the pores on the molding surface of the porous mold, as shown by arrows in FIG. , In the direction of the molding surface. The gas ejected from the molding surface passes through a gap between the molding surface of the porous molding die 1 and the molding surface of the molding glass lump 2, and flows toward the outer peripheral edge of the molding surface of the molding glass lump 2. Flows. Therefore, a gas flow flows through the gap between the molding die 1 and the molding glass lump 2, and a pressure is generated on this molding surface by Bernoulli's theorem. Therefore, the convex portion of the raw material grain 12 does not come into contact with the concave portion of the molded glass lump 2 due to the pressure.

As described above, after the molded glass lump 2 whose surface to be molded is slightly uneven is obtained by press molding, the molded glass lump 2 is cooled while being held inside the porous mold 1. To start. Here, since the coefficient of thermal expansion of the glass is larger than the coefficient of thermal expansion of the mold, the glass tends to shrink. However, in this embodiment, since the convex portions of the raw material grains 12 and the concave portions of the molded glass lump 2 have a corresponding positional relationship, the shrinkage of the glass is suppressed, and the shrinkage amount is small.

Therefore, the cooling is completed and the porous mold 1
When the molded glass lump 2 is taken out from the mold, the shape of the molding surface of the molded glass lump 2 becomes substantially similar to the shape of the molding surface of the porous mold 1. The surface roughness of the molding surface of the molded glass lump 2 is smaller than the surface roughness of the molding surface of the porous mold 1, and the surface is slightly uneven.

Next, the surface shape of the porous mold in this embodiment is shown in FIG. This is obtained by processing the porous carbon shown in FIG. 3 into a spherical molding surface by cutting. FIG. 5 shows the shape data after removing the spherical R component. In FIG. 5, the shape appears to have an edge. This is because the scale of the horizontal axis is 1/10 of the scale of the vertical axis. As shown in FIG. As can be seen from FIG. 5, the surface roughness of the molding surface of this porous mold is about 25 μm in PV value and about 15 μm in Ra.

FIG. 6 shows the shape data of the molding surface of the molded glass lump obtained in this embodiment. The measuring method is the same as that of the molding die shown in FIG. As is clear from FIG. 6, the surface roughness of the molding surface of this porous mold is about 5 μm in PV value and about 2 μm in Ra.

From the results shown in FIGS. 5 and 6, the surface roughness of the molding surface of the porous mold was not transferred to the molding glass lump, and the surface roughness of the molding surface of the molding glass lump was: It can be confirmed that the size of the swell is significantly smaller than that of the mold, and particularly, the size of the swell is reduced in the height direction and the span of the swell in the horizontal direction is increased.

Referring to FIG. 6, the valley shape of the concave portion of the molding surface of the molded glass lump looks like an edge, but this is due to the effect of the vertical and horizontal scale ratios. ,
The valley bottom is round. That is, the molding surface of the molded glass lump obtained here is slightly uneven, with a depth of about 3 μm every 0.3 mm. When the appearance of this molded glass lump is visually observed, the molding surface is a glossy smooth surface, but when viewed finely, it looks like a mat surface with light irregularities. 5 and 6 show shape data of a part of a molding surface of a mold and a part of a molding surface of a glass lump, respectively.

Next, the whole shape data will be shown. FIG.
8 shows the shape measurement data of the porous lower mold, FIG. 8 shows the lower surface of the molded glass lump, FIG. 9 shows the shape measurement data of the porous upper die, and FIG. These measurement methods are the same as in FIG. 5, and each shows the result of removing the spherical R component. In FIGS. 7 and 9, the surface shape of the porous mold appears to have an edge because the vertical and horizontal scales are reduced to 1/100, and the shape of the convex portion is actually spherical.

From these observations, it can be seen that the molding surface of the molded glass lump is on the order of μm over the entire surface of the molding surface, and that the desired shape accuracy is obtained. This is because the molded glass block is cooled while being lightly constrained by the projections of the material grains on the molding surface of the porous mold, so that the shape of the molding surface of the mold can be transferred well. It is because. On the other hand, it can be seen that the large surface roughness of the mold is not transferred to the molding surface of the molded glass lump and is slightly uneven.

Subsequently, the surface layer of the molding surface of the molded glass lump 2 finished to a high degree of shape accuracy was slightly ground and removed, and further polished to obtain an optical element. When an optical element is obtained from a conventional pressed glass material by grinding and polishing, first, rough grinding is performed by a curve generator processing machine using a cup-shaped diamond grindstone, so-called CG processing is performed. After
Precision grinding is performed using a pellet grinding stone, commonly called pellet processing, and then polishing is performed using abrasive grains. However, the molded glass block obtained in this embodiment has a high shape accuracy. Since it was high and there was no foreign matter on its surface, CG processing was not performed, but only pellet processing and polishing processing were performed. The amount removed by pellet processing was 5 μm, and the amount removed by polishing was 2 μm. The time for the removal processing was on one side, and the pellet processing was 1 minute and the polishing processing was 1 minute.

On the other hand, when a pressed glass material is ground and polished by a conventional method, the removal amount is 500 times by CG processing.
The processing time was 1 minute for CG processing, 10 minutes for pellet processing, and 3 minutes for polishing on one side.

Therefore, in the embodiment of the present invention, the grinding
The amount of grinding waste (sludge) generated at the time of removal processing by polishing is reduced to 1.3% compared to the conventional method.
It can be greatly reduced, and there is a great merit in protecting the global environment. Further, since the processing time can be shortened, the manufacturing cost is also reduced.

[0066]

EXAMPLES Hereinafter, more specific examples of the present invention will be described with several examples, and comparative examples of the present examples will be described with several examples.

(Embodiment 1-1) In this embodiment, the SK12
A considerable amount of optical glass material was placed in a crucible made of platinum (not shown), and its surroundings were heated to 1200 ° C. and melted. The molten optical glass was discharged through a platinum outflow pipe (not shown). The temperature of this outflow pipe is 8
The temperature was maintained at 60 ° C., and the molten glass flow was discharged as droplets from the outlet of the outlet pipe.

The porous mold 1 is made of porous carbon VCP-10 manufactured by Nippon Carbon Co., Ltd. as shown in FIG. 3, and has a porosity of 25% and an average pore diameter of 10 μm. As for the molding surface of this porous mold 1, the lower mold has a curvature radius of 6.5.
mm, the upper die has a curvature radius of 24 mm, and the opening diameter is 10 mm.
mm. The surface shape of the molding surface of this porous mold is such that the lower mold is as shown in FIG. 7 and the upper mold is as shown in FIG. 9. The surface roughness of the lower mold is Ra = 15 μm, Is R
a = 15 μm

The mold holding block 5 is always kept at 500 ° C. by a built-in heater (not shown). From the gas supply pipe 4, a nitrogen gas having a pressure of 0.2 MPa is provided.
It is initially supplied at a flow rate of 5 L (liter) per minute. The molding surface of the porous mold 1 in this state was installed at a position of 10 mm below the outlet of the outflow pipe, and the state was maintained for 5 seconds. Then, 0.7 g of molten glass having a desired weight was obtained in a floating state on the molding surface of the porous lower mold 1 via a gas film. Therefore, the porous mold 1
Was lowered 10 mm downward and stopped. Then, immediately, the molten glass flow began to be constricted at that position, and was spontaneously cut after 0.2 seconds.

The molten glass lump thus obtained is
After the porous lower mold 1 is moved to a position below the porous upper mold 1 in the state of being held floating, the NC driving device 8
As a result, the porous lower mold 1 was raised, and the upper and lower molds began to approach.

Then, 15 seconds after obtaining the molten glass lump, press molding of the molten glass lump with a porous upper and lower mold was started. At this time, the pressing speed, that is, the rising speed of the porous lower mold 1 by the NC driving device 8 is 0.3 mm / s.
Is controlled. The flow rate of the nitrogen gas ejected from the porous lower mold is controlled at 1 L / min, and the flow rate of the nitrogen gas ejected from the porous lower mold is controlled at 1 L / min.

Ten seconds after the start of the press molding, the press molding was completed, and a molded glass block 2 having a desired shape was obtained. At this time, the flow rate of nitrogen gas ejected from the porous lower mold is controlled to 0.5 L / min, and the flow rate of nitrogen gas ejected from the porous lower mold is controlled to 0.7 L / min. .
The pressing speed immediately before this is controlled to 0.1 mm / s.

Thereafter, in this state, the molding glass lump 2 is held for 40 seconds, and after the molded glass lump 2 is cooled, the mold is opened and the molded glass lump 2
Was taken out. The shaped glass lump 2 thus obtained
The surface shape of the surface to be molded has the lower surface shown in FIG. 8 and the upper surface shown in FIG. 10. The surface roughness is Ra = 2 μm on the lower surface and Ra = 2 μm on the upper surface. Was. That is, the surface roughness of the molding surface of the molded glass block is 1/8 or less of the surface roughness of the molding surface of the molding die in both upper and lower directions. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 5 μm or less.

Subsequently, the molding surface of the molded glass lump 2 thus obtained was finely ground by pellet processing and then polished to obtain an optical element. That is, first, one side is subjected to pellet processing for 1 minute, and a surface removal of 5 μm is performed.
Subsequently, polishing was performed for 1 minute to remove a surface of 2 μm. Subsequently, the opposite surface was similarly processed. The optical element thus obtained had excellent quality.

(Example 1-2) In this example, a porous mold was used as a porous carbon VCP manufactured by Nippon Carbon Co., Ltd.
Made with -15. The porosity is 30% and the average pore size is 15
μm. The surface roughness of the molding surface of this porous mold is Ra = 50 μm for the lower mold and Ra = 50 μm for the upper mold. The other conditions, that is, the shape of the mold and the molding process are the same as those in Example 1-1.

The surface roughness of the molding surface of the molded glass lump 2 thus obtained was Ra = 5 μm on the lower surface and Ra on the upper die.
= 5 μm. In other words, the surface roughness of the molding surface of the molded glass lump is 1/100 of the surface roughness of the molding surface of the molding die.
10 or less. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 8 μm or less.

Subsequently, the molding surface of the molded glass lump 2 thus obtained was finely ground by pellet processing and then polished to obtain an optical element. First, one side was pellet-processed for 2 minutes to remove the surface of 10 μm, and then polished for 1 minute to remove the surface of 2 μm.
Subsequently, the opposite surface was similarly processed. The optical element thus obtained had excellent quality.

(Example 1-3) In this example, a porous mold was used as a porous carbon VCP manufactured by Nippon Carbon Co., Ltd.
Made with -5. The porosity is 20% and the average pore size is 5 μm
It is. The surface roughness of the molding surface of this porous mold is as follows.
a = 8 μm, and Ra = 8 μm for the upper die. Other conditions, that is, the shape of the mold and the molding process are the same as in Example 1-1.
Is the same as

The surface roughness of the molding surface of the molded glass lump 2 thus obtained was Ra = 1 μm on the lower surface and Ra on the upper surface.
= 1 μm. In other words, the surface roughness of the molding surface of the molded glass lump is 1/100 of the surface roughness of the molding surface of the molding die.
8 or less. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 5 μm or less.

Subsequently, the molding surface of the molded glass lump 2 thus obtained was finely ground by pellet processing and then polished to obtain an optical element. First, pellet processing was performed on one surface for 1 minute to remove a surface of 5 μm, and then polishing was performed for 1 minute to remove a surface of 2 μm.
Subsequently, the opposite surface was similarly processed. The optical element thus obtained had excellent quality.

Comparative Example 1-1 In a comparative example for comparison with the example of the present invention, a porous mold was made of porous carbon VCF-25 manufactured by Nippon Carbon Co., Ltd. The porosity is 65% and the average pore size is 25 μm. The surface roughness of the molding surface of this porous mold is Ra = 80 μm for the lower mold and Ra = 80 μm for the upper mold. Other conditions, that is, the mold shape and the molding process are the same as those in Example 1-1.

The shaped glass lump thus obtained is
The molding surface bites into the pores of the porous mold, making it difficult to remove it from the mold. In addition, by changing the molding process to reduce the molding speed and to increase the flow rate of the gas ejected from the mold, the penetration into the mold was reduced. And the difference between the shape of the molded glass block and the surface to be molded greatly exceeded the allowable range.

Then, such a formed glass lump is subjected to CG
If precision grinding is performed only by pellet processing without forming, and processed into an optical element, a great amount of time is required, which is not practical.

(Comparative Example 1-2) In this comparative example, a porous mold was used as a porous carbon VCP manufactured by Nippon Carbon Co., Ltd.
Made at -50. The porosity is 40% and the average pore size is 50.
μm. The surface roughness of the molding surface of this porous mold is Ra = 50 μm for the lower mold and Ra = 50 μm for the upper mold. Other conditions, that is, the mold shape and the molding process are the same as those in Example 1-1.

The molded glass lump thus obtained is
The molding surface bites into the pores of the porous mold, making it difficult to remove it from the mold. In addition, by changing the molding process to reduce the molding speed and to increase the flow rate of the gas ejected from the mold, the penetration into the mold was reduced. And the difference between the shape of the molded glass block and the surface to be molded greatly exceeded the allowable range.

Then, such a formed glass lump is subjected to CG
If precision grinding is performed only by pellet processing without forming, and processed into an optical element, a great amount of time is required, which is not practical.

(Second Embodiment) In a second embodiment of the present invention, a molten glass ingot is blown out of the pores of the molding surface thereof using a pair of upper and lower porous molding dies. In the state,
Press molding, to obtain a molded glass lump in a state where the molding surface is slightly uneven, the molding surface of the molded glass lump,
The optical element is obtained by removing only by polishing.

The mold structure, device configuration and operation of the device in the second embodiment are the same as those in the first embodiment. That is, a molten glass lump is obtained on a porous lower mold in a state where it is held floating by a jet gas, and this is press-molded with a pair of upper and lower porous molds, and the molding surface is formed. The steps up to obtaining a slightly irregular shaped glass lump with high precision and shape accuracy are the same as in the first embodiment.

Subsequently, the surface layer of the molding surface of the molded glass lump 2 finished with high precision in this manner was polished to obtain an optical element. That is, it was performed when obtaining an optical element by grinding and polishing from a conventional press glass material,
The CG processing step and the pellet processing step are omitted in the second embodiment.

In this embodiment, the removal amount by polishing is 5
μm, and the removal processing time was 2 minutes per side. Therefore, according to the present embodiment, the amount of grinding waste (sludge) generated at the time of removal processing by grinding and polishing can be greatly reduced as compared with the conventional method, and there is a great merit in protecting the global environment. In addition, the processing time can be shortened, and processing equipment for CG processing and pellet processing is not required, so that manufacturing costs can be reduced.

Hereinafter, more specific examples of the present embodiment will be described with reference to several examples, and comparative examples of the present embodiment will also be described with reference to several examples. (Example 2-1) In this example, the same type as that in Example 1-1 was used. That is, the porous mold 1 is made of porous carbon VCP-10 manufactured by Nippon Carbon Co., Ltd.
The porosity is 25% and the average pore size is 10 μm. As for the molding surface of the porous mold 1, the lower mold has a radius of curvature: 6.5 mm,
The upper die has a radius of curvature of 24 mm and the opening diameter is 10 m.
m. The surface shape of the molding surface of the porous mold is such that the lower mold is as shown in FIG. 7 and the upper mold is as shown in FIG. 9. The surface roughness of the lower mold is Ra = 15 μm, and the upper mold is Ra =
It was 15 μm.

The process for obtaining a molded glass lump in this embodiment is substantially the same as that in Embodiment 1-1. However, in the present Example 2-1, the temperature of the mold holding block was 600 ° C. at the start of press molding, 500 ° C. at the start of press molding, and after the completion of press molding, a pair of upper and lower porous molds were placed in that state. The mold was held for 60 seconds, during which time the temperature of the mold holding block was controlled to 450 ° C. to prevent a difference in the temperature distribution inside the molded glass block.

The surface roughness of the molding surface of the molded glass lump 2 thus obtained was such that the lower surface was Ra = 1 μm and the upper surface was R
a = 1 μm. That is, the surface roughness of the molding surface of the molded glass lump is one of the surface roughness of the molding surface of the molding die, both up and down.
/ 15 or less. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 3 μm or less.

Subsequently, the molding surface of the molded glass lump 2 thus obtained was polished to obtain an optical element. Polishing was performed for 2 minutes to remove a surface of 5 μm. continue,
The opposite side was processed similarly. The optical element thus obtained had excellent quality.

Embodiment 2-2 In Embodiment 2-1 described above, an example of obtaining a biconvex lens has been described.
Now, an example of obtaining a biconcave lens will be described. The mold used here is VCP-10 of porous carbon. The shape of the mold is such that the lower mold has a convex shape with a radius of curvature of 24 mm, the opening diameter is 10 mm, and the upper mold has a radius of curvature of 6.5 mm.
Was a convex shape. The surface roughness of the lower mold was Ra = 20 μm, and the upper mold was Ra = 25 μm.

The process for obtaining a molded glass lump in this embodiment is the same as that in Embodiment 2-1. The surface roughness of the molding surface of the molded glass lump 2 thus obtained was Ra = 2 μm on the lower surface and Ra = 2 μm on the upper surface. That is, the surface roughness of the molding surface of the molded glass lump is 1/13 or less of the surface roughness of the molding surface of the molding die in both upper and lower directions. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 3 μm or less.

Subsequently, the molding surface of the molded glass lump 2 thus obtained was polished to obtain an optical element. Polishing was performed for 2 minutes to remove a surface of 5 μm. continue,
The opposite side was processed similarly. The optical element thus obtained had excellent quality.

(Comparative Example 2-1) In this comparative example, porous carbon V manufactured by Nippon Carbon Co., Ltd. was used as the porous mold material.
CP-0.5 was used. The porosity is 20% and the average pore size is 0.5 μm. The surface roughness of the molding surface of this porous mold is Ra = 1 μm for the lower mold and Ra = 1 μm for the upper mold.
Other conditions, that is, the shape of the mold and the molding process are the same as those in Example 2-1.

Since the porous mold has poor air permeability, the amount of gas blowout is small, and the molding surface of the molded glass block is in contact with the molding surface of the porous molding die. Carbon had adhered.

Even if the molding process is changed and the supply gas amount is increased, the gas leaks in the middle of the gas pipe due to poor air permeability of the mold, and the amount of gas ejected from the mold does not increase. And the mold could not be contacted. And since such a molded glass lump has carbon adhered to its molding surface, it was necessary to remove a large amount of its surface layer in order to use it as an optical element. That is, in order to remove this layer only by polishing, it was necessary to perform polishing on one side for 30 minutes, and there was no cost advantage.

(Comparative Example 2-2) In this comparative example, porous carbon V manufactured by Nippon Carbon Co., Ltd. was used as the porous mold material.
CP-50 was used. The porosity is 40% and the average pore size is 50 μm. The surface roughness of the molding surface of this porous mold is
The lower mold has Ra = 50 μm, and the upper mold has Ra = 50 μm.
Other conditions, that is, the shape of the mold and the molding process are the same as those in Example 2-1.

The molded glass lump thus obtained is
The molding surface bites into the pores of the porous mold, making it difficult to remove it from the mold. In addition, by changing the molding process to reduce the molding speed or increase the flow rate of the gas ejected from the mold, it is possible to reduce the bite into the mold. The difference between the surface shape and the surface shape of the molded glass block was increased. And if such a shaped glass lump is processed into an optical element only by polishing, a great amount of time is required,
Not practical.

(Third Embodiment) In a third embodiment of the present invention, a molten glass ingot is blown out of pores on the molding surface thereof using a pair of upper and lower porous molding dies. In the state,
Press molding is performed to obtain a molded glass lump having a slightly irregular surface, and the molded glass lump is press-molded with a pair of molding dies to obtain a molded optical element.

The mold structure, the device configuration, and the operation of the device in the third embodiment are the same as those in the first embodiment. That is, a molten glass lump is obtained in a state of being floated and held by a gas ejected on a porous lower mold, and is press-molded with a pair of upper and lower porous molds, and the molding surface is slightly reduced. The steps up to obtaining a molded glass lump having a high degree of accuracy and a high degree of accuracy are the same as in the first embodiment.

Subsequently, the molded glass block of high precision and shape obtained in this way is placed on a pair of upper and lower molding dies maintained at the molding temperature, and the molded glass block is press-molded. Heat soften until the temperature reaches a possible level. Thereafter, using the pair of upper and lower molding dies, the softened molded glass block was press-molded to obtain a molded optical element.

The molding die used in this embodiment is made of a cemented carbide, and the molding surface is placed on the polished surface.
A TiN film having a function as a protective film is formed, and a carbon film having a function as a release film is formed thereon.

In the present embodiment, the difference between the desired shape of the molded optical element and the shape of the molded glass block used as the molding material, that is, the difference between the radius of curvature of the molding surface and the molding surface is within 1000 μm. The difference between the center thicknesses, that is, the press allowance was set to within 1000 μm.

Therefore, after the molded glass block is placed on the lower molding die by the heat transfer from the mold maintained at the molding temperature, the molded glass block is heated to a temperature at which press molding is possible 45 seconds later. Was done. Thereafter, when a press force was applied to start press molding, the press was completed in 10 seconds because the press allowance was small. Thereafter, in this state, the molded optical element was cooled so as not to generate a temperature distribution inside, and then opened, and the molded optical element was taken out.

The molded optical element obtained according to this example is
The quality was excellent as a molded optical element. In this embodiment, the mold durability is very excellent, and the continuous molding is performed for 10,000 seconds.
Even after hot, the carbon film having a function as a release film formed on the molding surface of the molding die is not damaged. Therefore, according to the present embodiment, the heating time required for obtaining the molded optical element and the molding time can be reduced, the production cost can be reduced, and the production cost can be reduced by improving the mold durability. Go down.

Hereinafter, more specific examples of the present embodiment will be described with reference to several examples, and comparative examples of the present embodiment will also be described with reference to several examples.

(Embodiment 3-1) In this embodiment, the first embodiment will be described.
The same type as -1 was used. That is, the porous mold 1 is made of porous carbon VCP-10 manufactured by Nippon Carbon Co., Ltd., and has a porosity of 25% and an average pore diameter of 10 μm.
It is. The molding surface of the porous mold 1 is such that the lower mold has a radius of curvature:
6.5 mm, the upper die has a radius of curvature of 24 mm, and the opening diameter is 10 mm. The surface shape of the molding surface of this porous mold is such that the lower mold is as shown in FIG. 7 and the upper mold is as shown in FIG. 9. The surface roughness of the lower mold is Ra = 15 μm.
The upper mold had Ra = 15 μm. The process for obtaining a molded glass lump in the present embodiment is almost the same as that in Example 1-1.

The surface roughness of the molding surface of the molded glass lump 2 thus obtained was such that the lower surface was Ra = 1 μm and the upper surface was R
a = 1 μm. That is, the surface roughness of the molding surface of the molded glass lump is one of the surface roughness of the molding surface of the molding die, both up and down.
/ 15 or less. The difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 5 μm or less.

Subsequently, the formed glass block was press-formed with a pair of upper and lower forming dies to obtain a formed optical element. In this molding die, the molding surface of the lower die is polished to a radius of curvature of 7 mm, and the upper die is polished to a radius of curvature of 30 mm. Then, the pair of molds was kept at 580 ° C. The molded glass lump was placed on the lower molding die in this state, and after the molded glass lump was heated and softened, a pressing force of 3000 N was applied to obtain a molded optical element. The molded optical element thus obtained had very good quality.

(Example 3-2) In this example, a porous mold was used as a porous carbon VCP manufactured by Nippon Carbon Co., Ltd.
Made with -15. The porosity is 30% and the average pore size is 15
μm. The molding surface of the porous mold 1 is such that the lower mold has a radius of curvature of 6.5 mm, the upper mold has a radius of curvature of 24 mm, and the opening diameter is 10 mm. The surface roughness of the molding surface of this porous mold was Ra = 50 μm for the lower mold and Ra = 50 μm for the upper mold.
m. The process for obtaining a molded glass lump in the present embodiment is almost the same as in Example 1-1.

The surface roughness of the molding surface of the molded glass lump 2 thus obtained was Ra = 5 μm on the lower surface and R = 5 μm on the upper surface.
a = 5 μm That is, the surface roughness of the molding surface of the molded glass lump is one of the surface roughness of the molding surface of the molding die, both up and down.
/ 10 or less. Further, the difference between the shape of the molding surface of the porous mold and the shape of the molding surface of the molded glass block was 10 μm or less.

Subsequently, the formed glass lump was press-formed with a pair of upper and lower forming dies to obtain a formed optical element. In this molding die, the molding surface of the lower die is polished to a radius of curvature of 7 mm, and the upper die is polished to a radius of curvature of 30 mm. Then, the pair of molds was kept at 580 ° C. The molded glass lump was placed on the lower molding die in that state, and after the molded glass lump was heated and softened, a pressing force of 3000 N was applied thereto to obtain a molded optical element. The molded optical element thus obtained had very good quality.

(Comparative Example 3-1) In this comparative example, porous carbon V manufactured by Nippon Carbon Co., Ltd. was used as the porous mold material.
CP-50 was used. The porosity is 40% and the average pore size is 50 μm. The surface roughness of the molding surface of this porous mold is
The lower mold has a Ra of 30 μm, and the upper mold has a Ra of 30 μm.
Other conditions, that is, the mold shape and the molding process are the same as those in Example 3-1.

The shaped glass lump thus obtained is:
The molding surface penetrated into the pores of the porous mold, and it was difficult to remove the mold from the mold. In addition, by changing the molding process and reducing the molding speed or increasing the flow rate of the gas ejected from the mold, it is possible to reduce bite into the mold, but in this case, the molding surface shape of the porous mold and The difference between the shape of the molded glass block and the shape of the molding surface was increased. If such a molded glass lump having no desired shape is used as a molding optical element molding material, gas residues are often generated during press molding, which is not practical.

[0119]

As described above, according to the present invention,
As a material for manufacturing an optical element, a suitable high-precision molded glass block can be obtained, which contributes to cost reduction of the optical element.

Further, according to the present invention, it is possible to obtain a more accurate and highly accurate molded glass lump as a material for manufacturing an optical element, which contributes to cost reduction of the optical element.

Further, according to the present invention, in producing the optical element, it is possible to suppress the amount of processing chips discharged, thereby contributing to environmental protection and cost reduction of the optical element.

Further, according to the present invention, when manufacturing a molded optical element, the manufacturing time can be shortened and the mold durability can be improved, which contributes to the cost reduction of the optical element.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of a mold according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating the configuration of the device according to the first embodiment.

FIG. 3 is a view for explaining the structure of a mold member.

FIG. 4 is a diagram schematically illustrating a state during molding.

FIG. 5 is a view for explaining the shape of the molding surface of the mold.

FIG. 6 is a view for explaining a shape of a forming surface of a formed glass lump.

FIG. 7 is a view for explaining the shape of the molding surface of the lower mold.

FIG. 8 is a view for explaining the shape of the surface to be molded of the molded glass block.

FIG. 9 is a view for explaining the shape of the molding surface of the upper die.

FIG. 10 is a view for explaining the shape of a forming surface of a formed glass lump according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous mold 2 Molded glass lump 3 Gas supply chamber 4 Gas supply pipe 5 Mold holding block 6 Mass flow controller 7 Gas supply unit 8 NC drive device 9 Computer 10 Sequencer 11 Controller 12 Porous material particles

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akazu Mizuwa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hiroyuki Kubo 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Non-corporation F term (reference) 4G015 HA01

Claims (12)

[Claims] 1. Using a pair of porous molds, receiving a molten glass lump on a molding surface thereof, and using a gas ejected from the molding surface, the molten glass lump is brought into non-contact with the molding surface. In a method for producing a molded glass lump for producing an optical element by press-molding to obtain a desired shape, in the press molding step, the molded glass lump has a part of a molding surface formed by a porous molding die. The mold is brought into contact with the molding surface, the shape of the molding surface is transferred, and the other parts are held by a gas ejected from the molding surface of the molding die, and are kept in a non-contact state and are press-molded. A method for producing a molded glass lump for producing an optical element, characterized by comprising: 2. The method of manufacturing a molded glass lump according to claim 1, wherein the molded glass lump has a part to be molded that comes into contact with a molding die and another part that is not in contact with the molding die. A method for producing a molded glass block for producing an optical element, wherein the molded glass block is press-molded in a molding die so as to be substantially uniformly distributed over the entire molding surface. 3. The method for producing a molded glass lump according to claim 1, wherein the area of a part of the molded glass lump that contacts a molding die on the molding surface is 50% of the molding surface. The molded glass for forming an optical element, wherein the molded glass block is formed on a molding surface so that the remaining area is occupied by another part that is not in contact with the molding die. How to make a lump. 4. The method for producing a molded glass lump according to claim 1, wherein the surface roughness of the molding surface of the molded glass lump is Ra = 0.05 μm to 20 μm. And a method for producing a molded glass lump for producing an optical element, wherein the molding surface is formed. 5. The method for producing a molded glass lump according to claim 1, wherein a surface roughness of a molding surface of the porous molding die is in a range of Ra = 5 μm to Ra100 μm. And a method for producing a molded glass lump for producing an optical element, comprising forming the molding surface. 6. The method for producing a molded glass lump according to claim 1, wherein the porous molding die is formed of a porous material having a porosity of 35% or less and an average pore diameter of 50 μm or less. A method for producing a molded glass lump as a material for producing an optical element. 7. The method for producing a molded glass lump according to claim 1, wherein the surface roughness of the molded glass lump is smaller than the surface roughness of a porous molding die. A method for producing a molded glass lump for producing an optical element, comprising adjusting a flow rate of a gas ejected from a molding surface of a quality molding die. 8. The method for producing a molded glass lump according to claim 1, wherein the molding surface of the molded glass lump has a desired surface roughness and is slightly uneven. , The approach speed of a pair of molds (press speed), and
A method for producing a molded glass block for producing an optical element, characterized in that a flow rate of a gas ejected from a molding surface of a porous molding die is controlled at a desired time to a desired value. 9. The method for producing a molded glass lump according to claim 1, wherein the surface roughness of the molded glass lump is 1/5 or less of the surface roughness of the porous mold. A method for producing a molded glass lump for producing an optical element. 10. The method for producing a molded glass lump according to claim 1, wherein the difference between the shape of the molding surface of the porous molding die and the shape of the molding surface of the molded glass lump. The method for producing a molded glass lump for producing an optical element, characterized in that the molding is performed so as to be 100 μm or less. 11. A molding glass block obtained by the method according to claim 1, wherein the molding surface is slightly uneven, and the molding surface is polished or ground and polished. A surface layer portion of the surface to be molded is removed, thereby obtaining an optical element having a desired shape. 12. A molded glass block obtained by the method according to any one of claims 1 to 10 having a slightly uneven surface to be molded is heated to a temperature at which it is softened, and is heated with a pair of precision molding dies. A method for producing an optical element, comprising obtaining a molded optical element having a desired shape in which the irregularities are removed or reduced in the step of press molding.