JPH11106221A - Molding of glass element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding a glass element, directly giving the molded glass element having a surface shape good in precision from a molding glass raw material in a molten state. SOLUTION: In this method for molding a glass element by press-molding a softened molding glass raw material by the use of a porous mold, the shape of the molding raw material is arranged so as to follow the molding surface, while a fluid is blown out from the molding surface of the mold to maintain the molding glass raw material and the molding surface in a mutually non- contact state. Therein, a groove continued to the molding surface and used for discharging a gas is disposed in the mold, and the molding raw material is pressed and molded, while the mold and the molding glass raw material are relatively rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for hot-pressing optical glass elements such as lenses used in cameras and video cameras.

[0002]

2. Description of the Related Art Conventionally, in pressure molding of a glass element, a so-called softened molded glass material is brought into contact with a molding surface of a molding die to obtain a surface shape corresponding to a required optical functional surface. A hot press forming method is widely used, and usually, in this forming method, a forming die including a body die and a plurality of upper and lower forming mold members combined with the body die is adopted. Then, the molded glass material in the heat-softened state is pressed, a shape corresponding to the molding surface of the mold member is transferred to the surface of the molded glass material, and then cooled, and the glass element is taken out from the mold member. It is.

Further, Japanese Patent Publication No. 48-22977 and Japanese Patent Application Laid-Open No. Sho 59-195541 disclose that a porous material is used as a mold member, and a gas film is formed on the surface of a molding die by using ultrasonic vibration. A technique for obtaining a glass element such as a lens through the same process as described above, in which the molding surface of the molding die and the molded glass material in a softened state are in a non-contact state through the gas film, is disclosed. ing.

[0004]

However, in a method of forming an optical glass element in which the shape of a molding surface of a mold is brought into contact with and transferred to the surface of a molded glass material (conventional example), a heated mold and a molded glass are used. Because the materials are in direct contact with each other, fusion occurs between them, and due to the temperature difference between the two during molding, the molded glass material undergoes non-uniform heat shrinkage. There have been problems such as poor transfer of the surface shape.

[0005] In particular, when the material is glass, such a problem is remarkable because the molding temperature is high, and the molding temperature is increased to shorten the molding time, or the precision is directly increased from the high-temperature molten glass. In order to obtain a glass element having a shape, considerable difficulty was involved. Also, the reaction between the molding glass material and the molding surface of the molding die due to the contact between them and the abrasion of the molding die surface tend to cause the molding die to deteriorate, and the use of a release agent to prevent fusion and reaction. In addition, the conditions for obtaining a high-precision glass element are severe, and accordingly, there is a problem that the material of a mold that can be used is considerably limited, and the type of glass from which the mold can be formed is greatly restricted. Was.

In order to avoid the above problems, as described above, Japanese Patent Publication No. 48-22977 and Japanese Patent Application Laid-Open No.
Japanese Patent Application Publication No. 195541 discloses a technique in which a molding die and a molded glass material are not brought into contact with each other. Certainly, forming the molding die and the molded glass material in a non-contact state has a sufficient effect for preventing fusion, but the glass material in a softened state and having a high temperature. When press molding and cooling, if the thickness of the finished molded product is not constant or the cooling to the molded product is not uniform, there will be a difference in the temperature distribution inside the molded product during cooling. ,
Heat shrinkage during cooling does not occur evenly, and the shrinkage is concentrated in a relatively high temperature part, so that part is deformed into a recessed state after cooling, a phenomenon called so-called sink occurs, and the original There is a problem in that a molded product greatly different from the intended surface shape is formed.

Further, due to the difference in pressure distribution of the gas ejected from the mold and the variation in temperature used for maintaining the non-contact state, the shape of the surface of the molded glass material to be transferred becomes unstable, In conjunction with the occurrence of the sink described above,
There is a problem that it is difficult to obtain a desired surface shape, and it is very difficult to produce a glass element with high accuracy.

The present invention has been made on the basis of the above circumstances, and aims to solve the above-mentioned various problems and to directly improve the precision of a molded glass material in a softened state. An object of the present invention is to provide a method for forming a glass element capable of obtaining a glass element such as an optical glass element having a surface shape.

Another object of the present invention is as follows.
It is an object of the present invention to provide some means in a method for forming a glass element in a more stable and non-contact pressure forming.

[0010]

In order to solve the above-mentioned problems, the pressure applied to the formed glass material, its distribution, the temperature during forming and cooling, and It is necessary to stabilize the distribution and the like, and furthermore, the thickness of the non-contact fluid existing between the molding glass material and the molding surface of the molding die is made uniform, and the molding die and the molding glass material are always It is necessary to keep an even non-contact state.

In consideration of the above, in order to achieve the above object, according to the present invention, when a softened molded glass material is subjected to pressure molding using a porous molding die, a molding surface of the molding die is formed. The method of forming a glass element, wherein the shape of the molded glass material is adjusted to follow the molding surface while maintaining the molded glass material and the molding surface in a non-contact state by ejecting a fluid from the molding die, In addition, a groove for venting gas is provided continuously with the molding surface, and pressure molding is performed while relatively rotating the molding die and the molding glass material.

In the above configuration, by providing a gas vent groove in a part of the porous molding surface, it becomes easy to control the gas pressure applied to the molding glass material from the molding surface,
In particular, it is possible to prevent a tendency that the central part is higher than the peripheral part. What should be considered here is that simply providing a groove on the molding surface causes the shape of the groove to be transferred to the surface of the glass lump to be molded. Relative rotation is required.

In addition, not only can the above-mentioned problem be solved, but also the relative rotation can equalize the pressure distribution, in particular the pressure substantially on the glass material about the axis of rotation, and at the same time,
It is also possible to make the temperature distribution of the entire molding surface uniform,
It is possible to obtain a glass element which does not easily cause sink marks and has a smooth surface.

The proper rotation speed at this time depends on the viscosity and the shape of the molded glass material, but the higher the speed, the more stable the temperature and pressure, and a good result can be obtained. Further, the groove needs to be formed from the center of rotation to the outer periphery, but by devising the shape of the groove, it is possible to control the pressure distribution at the center and the outer peripheral edge. .

Further, in the present invention, one or a plurality of the grooves are formed in a shape extending in a radial direction from a central portion of a molding surface, and a surface of the molding glass material is formed with a surface of the molding die. By the relative rotation, pressure molding is performed so as to follow the shape of the molding surface, in other words, the molding surface involved in molding is reduced in length in the normal direction of the rotation, and that part is made into a material. By rotating while pressing against the non-contact, an axisymmetric transfer surface is formed on the surface of the formed glass material block.

According to the above method, the molding surface of the molding die can be made substantially small, whereby the unevenness of the pressure distribution on the molding surface is reduced and the control over the pressure is facilitated. It is easy to stabilize the distance between the mold and the molding surface. Further, since the molding area is small, it is easy to increase the processing accuracy of the molding surface, and it is easy to increase the precision of the molded product. However, at this time, since the area for molding the glass material is smaller than the area to be molded, it is necessary to increase the rotation speed in a sense of compensating for this, and by doing so, the shape of the molded article Accuracy can be further improved and stabilized.

By providing a plurality of grooves, it is easy to balance the pressure on the entire molding surface of the mold, and to easily secure high shape accuracy of the molded product. However, it is convenient to correct the balance by additionally processing a plurality of grooves.

Therefore, according to the molding method of the present invention, when a glass element is obtained in a non-contact manner using a molding die having a molding surface made of a porous material from which a fluid can be ejected, the fluid is applied to the molding surface. The pressure distribution of the fluid between the molding material and the molding surface, which greatly affects the shape accuracy of the molded product, is provided by providing a groove for allowing air to escape and rotating the molding surface and the molding material relatively. It is possible to greatly improve the uniformity and controllability of thickness and temperature distribution, and it is possible to obtain a glass element with a highly accurate shape, especially for axial objects around the rotation axis. By easily making the film thickness uniform, there is a great effect on a glass element having a functional surface such as a lens having an axially symmetric shape.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be specifically described with reference to the drawings. 1 and 2 are a schematic diagram of a molding apparatus used in the present invention and an explanatory view of a molding die used in the present invention, respectively. In FIG. 1, reference numeral 1 denotes a mold unit, which is composed of a lower mold member 2 and an upper mold member 3, and further, the constituent members 2 and 3 are a lower mold member 11 and an upper mold member 21, respectively.
And a lower mold holder 12 for holding them respectively,
The upper mold holder 22 is provided.

The holders 12 and 22 are provided with pressure chambers 12a and 22a for supplying and distributing a fluid (gas) to the holders 12 and 22 in a well-balanced manner.
3, 23 and a temperature measuring means (not shown) are respectively embedded, so that the temperatures of the lower mold member 11, the upper mold member 12, and the fluid can be finally adjusted.

Reference numerals 11a and 21a represent, respectively,
FIG. 2 shows a molding surface of a lower mold member 11 and an upper mold member 21 which determine the surface shape of a molded product as a glass element, and the upper mold member 21 is located on a molding surface 21a as shown in FIG. In addition, a groove 21b for extracting a fluid is provided in a part thereof. Reference numeral 31 denotes a fluid supply pipe, which is configured to supply the fluid supplied from the portion indicated by the arrow A in the drawing to the pressure / flow rate regulators 32a and 32b, and further, the pressure / flow rate regulator 32a. , 32b are provided with heaters 33 for the purpose of adjusting the temperature of the fluid.
a and 33b are attached.

Each of the constituent members 2 and 3 is provided with a driving device (not shown).
As in Ba and Bb, the constituent members 2 and 3 can be independently moved in the vertical and horizontal directions. Further, as shown by arrows: Ca and Cb, the lower die member 11 and the upper die member Around each center of 21 at an arbitrary rotation speed,
They can rotate in opposite directions. For this reason, the constituent members 2 and 3 are made of the heat-resistant flexible tubes 34 a and 34 b and the rotary joint 1.
The heaters 33a and 33b are connected via the heaters 4 and 24, respectively.

Reference numeral 41 denotes a fluid controller for controlling the flow pressure and temperature of the fluid, and the pressure / flow controller 3 is controlled by signal lines 42a and 42b and control lines 43a and 43b.
2a, 32b and the heaters 33a, 33b can be freely controlled.

FIG. 3 is an explanatory view of a process when the molten glass material in a melt-softened state is supplied to a mold unit from a molding material supply nozzle, and the supplied molded glass material is cut and separated from the nozzle. In FIG.
Reference numeral 102 denotes a molding material supply nozzle for the molded glass material 102 in a molten and softened state, and 102 b denotes a molding surface 11 of the lower mold member 11.
a, the molded glass material lump before cutting, and 102c the molded glass material 102 flowing down from the molding material supply nozzle 101 and the molded glass material lump 1 before cutting.
The constriction created during 02b,
Reference numeral 102a denotes a molded glass material lump obtained on the molding surface 11a of the lower mold member 11.

[0025]

【Example】

(First Embodiment) Next, the steps of forming a glass element using the above-described forming apparatus will be specifically described with reference to the drawings. The glass element molded here is an approximate shape blank for a biconvex spherical lens used for a video camera. For example, the outer diameter is 14 mmφ, and the curvature of each surface is R: 20 mm and R: 35 mm. , Center thickness is 3m
m. Further, by further processing this approximate shape blank, a lens having a desired function can be obtained. The glass material for optical glass element, 10 ^1.5 dPa · s at the time of the temperature of 1300 ° C., 120
10 ^1.6 dPa · s at 0 ° C, 10 at 1100 ° C
^1.8 dPa · s, 10 ^2.2 dPa · at 1000 ° C
s, 10 ^2.9 dPa · s at 890 ° C., 10 ⁵ dPa · s at 720 ° C., 10 ^7.6 dPa · s at 610 ° C.
An optical glass having a viscosity characteristic of a glass viscosity of 10 ¹³ dPa · s at 498 ° C. is used.

The materials of the mold members 11 and 21 are as follows.
Porous carbon having a porosity of 30% and a maximum hole diameter of 12 microns is used. Nitrogen gas is used as a fluid in order to prevent oxidation of the mold members 11 and 21. Further, as shown in FIG. 2, the mold member 21 is provided with a gas vent groove 21b having a width and a depth that increase with approaching the outer peripheral edge thereof in order to improve gas venting. 21 from a portion slightly away from the center of the molding surface 21a.
Are radially extended to the outer periphery of the.

The mold members 11, 21 thus prepared
Was attached to the molding apparatus shown in FIG. 1, and a molded glass material block 102a in a softened state was obtained by a cutting method using glass outflow as shown in FIG. Here, this process will be described more specifically with reference to FIG. First, the above glass material is melted in a glass melting furnace (not shown), and thereafter, through a process of defoaming and homogenizing, a homogeneous molten glass material 102 which is a softened molded glass material is prepared. Furthermore,
It is guided to a forming glass material supply nozzle 101 provided at the end of the glass melting furnace.

Here, the supply nozzle 101 is set at 1200 ° C.
Is adjusted and set to the temperature, and the glass material 102 is caused to flow out, and the lower mold component 2 is taken directly below 101,
After receiving a predetermined volume on the molding surface 11a as shown in FIG. 3A, the lower mold component 2 is moved downward as shown by the arrow D in FIG. The molded glass material 102 which is slightly lowered and flows down, and the molded glass material lump 1 before cutting
02b, a constriction 102c is generated, and the constriction 102c waits for cutting by itself due to its own weight and surface tension (the state shown in FIG. 3 (c)). A material mass 102a was obtained. in this way,
In the cutting step of the constriction 102, by temporarily stopping the lower mold component 2, the portion of the constriction 102c is less likely to be cooled, and it is possible to cut naturally by its own weight and surface tension.

[0029] For this reason, since a cut mark or a break mark hardened in a thread like a conventional one does not remain at the cut portion of the molded glass material, the surface of the molded glass material block 102a
There is no harmful defect, and by adjusting the lowering timing of the lower mold component 2 and the temperature of the supply nozzle 101 arbitrarily, it is possible to always adjust the molded glass material block 102a to a target weight. .

The temperature of the fluid (nitrogen gas) at this time is 200 ° C., which is lower than the transition point of the glass when the glass material is received on the molding surface 11a. The temperature of the heaters 33a and 13 is adjusted so as to be 450 ° C., and the flow rate of the nitrogen gas is also set to 20 liters per minute until immediately before the glass material 102 is received on the molding surface 11a. Minute: Controlled by the pressure / flow controller 32a so as to be 5 liters.

By doing so, the glass material 102
Before reaching the molding surface 11a, the tip of the glass material 102 is slightly solidified and the flow rate of the nitrogen gas is increased, so that the tip of the glass material 102 does not contact the molding surface 11a at all, and Together with the use of the above cutting method, a molded glass material block 102a having no defect on the surface was obtained.

Next, the lower mold component 2 is moved directly below the upper mold component 3 and the lower
a at the part receiving the
Of the lower surface viscosity in the vicinity of 10 ⁶ ¯ ^7.5 dPa · s, the viscosity of the other near the surface in 10 ³ ¯ ⁶ dPa · s, within a sufficiently soft near the center, on the molding surface, in a non-contact state pressurized It is pressed.

At this time, the flow rate of the nitrogen gas ejected from the molding surfaces 11a and 21a is set to 2 liters per minute, and the glass temperature becomes 500 ° C. corresponding to 10 ¹³ dPa · s in terms of the viscosity of the glass. As shown in FIG.
a, 32b and the heaters 33a, 33b are set by the fluid controller 41, and only the upper mold member 21 is rotated in the direction of Cb at a speed of 120 rotations per minute while the lens is in a cold state. The mold unit 1 was closed and the shape of the molding surfaces 11a and 21a was indirectly transferred to the molded glass material lump 102a over about 20 seconds until the central thickness of the molded glass material became 3 mm.

Thereafter, the viscosity in the vicinity of the surface of the shaped blank (a lump of shaped glass material) having a viscosity of 10 ¹² dPa · s
When the temperature reached (about 515 ° C. in temperature), the mold unit was opened, and the approximate shape blank was taken out with a suction hand (not shown) while the nitrogen gas was jetted from the lower mold member 11. Further, the blank having the approximate shape thus obtained was polished and then centered to obtain a lens having a desired shape.

As a result, according to the manufacturing method of the present invention, there is almost no undulation or defect on the upper surface side of the approximate shape blank (molded product), there is no necessity of grinding, and by the direct polishing, It was confirmed that sufficient performance as an optical lens can be obtained only by polishing and removing the surface layer by about 10 μm.

(Second Embodiment) Next, mold members having the shapes shown in FIGS. 2 and 4 are used as a lower mold member and an upper mold member, respectively.
A case where a molded glass material block is obtained by using the molding apparatus used in the first embodiment will be described. Here, the diameter is 10 mm
φ, the curvature of the convex surface is R: 20 mm, and the curvature of the concave surface is R: 30
A convex meniscus lens having a thickness of 3.3 mm and a thickness of 3.3 mm at the center and a thickness of about 3.1 mm at the edge was molded.

In FIG. 4, reference numeral 221 denotes an upper mold member, and a molding surface 221a for forming an optical surface of the lens is formed from the center to the outer peripheral edge of the upper mold member. Like, except for a very small portion,
It is removed as the groove 221b of the escape portion. Furthermore the molding surface 221a, as shown in cross section Y ₂ -Y _2, leaving a part of the vertex, have been processed so as not edges, when the mold rotation, the glass material mass It has a smooth shape that does not bite.

Further, a porous hole on the surface of the upper die member 221 corresponding to the groove 221b is crushed so as to prevent airflow, and is treated so that fluid does not squirt out of the hole. . As the lower mold member, a mold member having the same shape as the mold member used for the lower mold member of the first embodiment is used. Further, both molding surfaces of the upper and lower mold members have been corrected for curvature so that the shape of the completed lens has a desired shape in consideration of shrinkage during cooling, and a porous surface on the molding surface is provided. Except for the hole, it is finished to be mirror surface. The same glass material as in the first embodiment was used as the glass material, nitrogen gas was used as the fluid, and porous carbon having a porosity of 20 to 25% and a maximum pore diameter of about 5 μm was used as the mold material. Was.

Thus, the mold member 2 thus prepared is
In the same manner as in the first embodiment, a softened glass material mass was obtained by attaching the device to a molding apparatus as shown in FIG. 1 and using the same method as described above. The temperature of the nitrogen gas at this time is 500 ° C., which is the temperature near the transition point of the glass when the molten glass material is received on the molding surface 21a, and immediately thereafter, the viscosity of the glass is 10 ^7.3 d.
The temperature was adjusted to 620 ° C. corresponding to Pa · s, and the flow rate of the nitrogen gas was further increased to 18 liters per minute with respect to the molding surface 21a until immediately before the molten glass material 102 was received by the molding surface 21a. After that, the control was performed so as to be 5 liters per minute.

Next, the lower mold component 2 is moved to a position immediately below the upper mold component 3, and the viscosity near the lower surface of the molded glass material block 102 a received by the lower mold member 11 becomes 10 ^5.6 ￣ ⁷ dPa.
· S, the viscosity of the other near the surface 10 ³ ¯ ^5.6 dPa ·
s, and while the vicinity of the center is sufficiently soft, the molding surface 21
a, the flow rate of the nitrogen gas ejected from the 221a is set to 2 liters per minute, the temperature of the glass is set to 610 ° C. corresponding to the viscosity of 10 ^7.6 dPa · s, and the lower mold member 2 and the upper The rotational speed of the mold component 3 is set such that the rotational speeds thereof are 200 rpm in the rotational directions that are opposite to each other.
8 mm per second until the center thickness of 2a becomes 3.4 mm
The mold unit 1 was closed at the speed shown in FIG.

Next, the lower component 2 and the upper component 3
, The temperature of the nitrogen gas is set to 580 ° C., and the flow rates from the molding surfaces 21a and 221a are set to 1 liter per minute, respectively. At the position corresponding to 3 mm, the mold unit 1 is closed while adjusting the closing speed so that the viscosity near the lens surface becomes 10 ^8.0 dPa · s. As a result, the shape of the molding surfaces 21a and 221a was transferred to the surface of the molded glass block as the lens material.

After the above-described shape transfer step, the temperature was set to 150 ° C. while keeping the flow rate of the nitrogen gas and the rotation of the lower mold member 2 and the upper mold member 3 unchanged, and cooling was started. After the start of cooling, the viscosity near the lens surface becomes 10 ¹² dP
When the temperature reaches a · s (a temperature corresponding to about 515 ° C.), the rotation of the lower mold component 2 and the upper mold component 3 is stopped, and at the same time, the mold unit 1 is opened and nitrogen gas is supplied from the lower mold member 21. The lens was taken out with a suction hand (not shown) in a state where it was jetted. After that, the accuracy of a plurality of lenses that had been molded was measured.
It was less than 0.5 or less, and as it was, sufficient accuracy as a normal optical lens could be obtained.

(Third Embodiment) Next, using a lower mold member 221 and an upper mold member 321 as shown in FIG. 5, the same molding apparatus and glass material as those of the first embodiment are used. A bi-convex glass aspheric lens for a compact camera, having an aspheric shape based on R: 50 mm on one side and R: 40 mm on the other side, was molded. Here, the center thickness of the lens is 4.3 mm and the diameter is 23 mmφ.

The lower mold member 221 has three radial grooves 221 curved with respect to a molding surface 221a for forming a transfer shape.
b, and the upper mold member 321 has a molding surface 321 a
It has a shape protruding from 21b. And in each groove, crush the porous hole,
It is processed so that gas does not blow out from the surface other than the molding surface.

Further, the shapes of the molding surfaces 221a and 321a have been corrected in advance together with the shape of the groove portion by data obtained by computer simulation and preliminary test, and are the same as in the case of the mold used in the second embodiment. In addition, the molding surface other than the holes is finished smoothly, and is processed so that the molded lens material has a desired shape.

Next, the mold member 22 prepared in this manner is prepared.
1 and 321 were attached to a molding apparatus as shown in FIG. 1, and a molded glass material lump 102a was obtained in exactly the same manner as in the first embodiment.

Prior to the pressure molding, in the step shown in FIG. 3, after the molten glass material 102b is received by the lower mold member 11, the lower mold member 2 is moved directly below the upper mold member 3, and
The viscosity near the lower surface of the molded glass material block 102a is 10 ^6
7.5 dPa · s, other viscosity near the surface is 10 ³ ￣ ⁶
dPa · s, and while the vicinity of the center is sufficiently soft, the flow rate of nitrogen gas ejected from the molding surfaces 221a and 321a is 2.5 liters per minute, and the temperature is 10 liters of glass viscosity.
^The pressure is adjusted to 610 ° C, which is equivalent to ^7.6 dPa · s.
The flow controllers 32a, 32b, the heaters 33a, 3
3b was set by the fluid controller 41.

The rotation of the lower mold member 221 and the upper mold member 321 was set to 225 rpm, and the mold unit 1 was closed at a speed of 8 mm per second until the center thickness of the molded glass material 102a became 4.4 mm. Next, the temperature of the ejected nitrogen gas was set to 600 ° C., and the flow rate was set to 1.5 liters per minute.
The mold unit 1 is closed until the center thickness of the cold lens reaches 4.3 mm, and the shapes of the molding surface 221a and the molding surface 321a are formed on the surface of the molding glass material.
Each was transcribed.

Thereafter, while keeping the flow rate of the nitrogen gas unchanged, the temperature was set to 150 ° C., cooling was started, and the temperature of the surface of the glass block was turned off at 498 ° C. (corresponding to a glass viscosity of 10 ¹³ dPa · s). Then, the mold unit 1 was opened and the lens was taken out. The mold unit 1 was opened, and the lens was taken out with a suction hand (not shown) while the nitrogen gas was jetted from the lower mold member 221. After that, the optical accuracy of the completed plurality of lenses was measured at a temperature of 20 ° C., but all were within 0.8 ass and 0.5 or less habit, showing good results. I got it.

(Fourth Embodiment) Next, an embodiment in which exactly the same as the first embodiment is formed from a glass material block whose weight has been adjusted in advance will be described. That is, a glass block is cut out from a glass block of the same material as used in the first embodiment,
It is further ground by grinding to a glass lump with a volume of 311 mm ^3, and then nitrogen gas per minute:
30 liters, was placed on the molding surface 11a that is ejected by a heater 13,33A, the temperature of the nitrogen gas, equivalent to 10 ^5.4 dPa · s in viscosity of the glass 70
The temperature was raised to 0 ° C., thereby heating the glass mass.

At this time, the upper mold member 3 is also connected to the lower mold member 2
, And while rotating the upper mold component 3 at a rotation speed of 30 rpm in the direction of Cb as shown in FIG. 1, a nitrogen gas at a similar temperature is flown to heat the glass material block from above. did. By doing so, a softened glass material mass 102a having no harmful defects, having a smooth surface, and having a viscosity of 10 ⁶ dPa · s was obtained.

Next, similarly to the first embodiment, the molding surface 11
a, the flow rate of the nitrogen gas ejected from 21a: 2 liters per minute, and the pressure / flow rate regulator 32a so that the temperature becomes 500 ° C., which is equivalent to 10 ¹³ dPa · s in glass viscosity.
32b and the heaters 33a and 33b are connected to the fluid controller 4
Set by 1. Here, while rotating only the upper mold member 21 in the direction of Cb at a speed of 120 revolutions per minute, it takes about 20 seconds until the center thickness of the blank at the time of cold becomes a position corresponding to 3 mm. The mold unit 1 is closed, and the molding surface 1 is placed on the surface of the molded glass material block 102a.
The shapes of 1a and 21a were transferred. Thereafter, a blank having an approximate shape was taken out and polished in the same manner as in the first embodiment. The result was the same as that obtained in the first embodiment.

[0053]

As described above, according to the present invention,
When using a mold made of a porous material with a molding surface capable of ejecting fluid, using a molding die made of porous material, in order to escape the fluid ejected from the molding surface to the molding surface when obtaining a molded glass material mass The fluid existing between the molding glass material and the molding surface, which greatly affects the shape accuracy of the molded article by relatively rotating the molding surface and the molding glass material block while providing the groove of The pressure distribution, film thickness and temperature distribution can be easily uniformized, and the controllability can be improved. As a result, glass elements with good shape accuracy, especially axially symmetrical elements such as lenses Glass elements with shapes can be easily formed, and furthermore, it is possible to extremely reduce waste such as sludge by conventional grinding and polishing. In large quantities, and It is possible to provide to the valence.

[Brief description of the drawings]

FIG. 1 is a schematic view of a molding apparatus used in the present invention.

FIG. 2 is a diagram of an example of a mold member used in the present invention.

FIG. 3 is an explanatory view of a method for cutting a molded glass material used in the present invention.

FIG. 4 is an explanatory view of a mold member used in another case of the present invention.

FIG. 5 is an explanatory view of a mold member used in still another case of the present invention.

[Explanation of symbols]

 Reference Signs List 1 mold unit 2 lower mold component 3 upper mold component 11, 12, 21, 221, 321 mold member 21a, 221a, 321a molding surface 21b, 221b, 321b groove 13, 23 heater 31 fluid supply pipe 32a, 32b pressure -Flow controllers 33a, 33b Heater 41 Fluid controller 101 Molded glass material supply nozzle 102 Molded glass material 102a Molded glass material lump 102b Molded glass material lump before cutting 102c Neck

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Tomita 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Aizuka Mizuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Non Corporation

Claims (3)

[Claims] When a molded glass material in a softened state is subjected to pressure molding using a porous molding die, a fluid is ejected from a molding surface of the molding die, so that the molded glass material and the molding surface are separated from each other. In a method of molding an optical glass element, which adjusts the shape of a molded glass material so as to follow the molding surface while maintaining the non-contact state with each other, the molding die is provided with a gas vent groove connected to the molding surface, A method for forming a glass element, comprising: performing pressure forming while relatively rotating a forming die and a formed glass material. 2. The groove is formed in a shape extending in a radial direction from a central portion of a molding surface, and a surface of the molding glass material follows a shape of the molding surface by relative rotation with the molding die. The method for forming a glass element according to claim 1, wherein the glass element is pressed. 3. The groove is formed in a shape extending in a radial direction from a central portion of a molding surface, and a plurality of the grooves are formed uniformly in a circumferential direction. 2. The method for forming a glass element according to claim 1, wherein the molding is performed under pressure so as to follow the shape of the forming surface by the relative rotation of.