JPH08319125A - Production of optical element-forming material - Google Patents

Abstract

PURPOSE: To produce a generally usable optical element-forming material capable of continuously producing a large number of spherical optical element- forming materials by a producing device having a simple structure and easily producing the elements having even different sizes and glass species. CONSTITUTION: This production method of an optical element-forming material is to melt a metal having a melting point lower than the transition temperature of a glass material 5, a boiling point higher than the softening point of the glass material 5 and a specific gravity larger than that of the glass material 5 and nonwetting with the glass material 5, heat and soften the glass material 5 in a molten metal bath 2, obtain glass elements 7 by cutting the softened glass material, heat the glass elements while keeping the temperature in the bath to obtain the objective optical element-forming material by floating the glass elements on the molten metal bath 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a material for molding an optical element whose surface is a mirror surface, which is obtained by press molding optical elements such as lenses, prisms and filters.

[0002]

2. Description of the Related Art In recent years, optical elements such as lenses, prisms and filters have come to be obtained by heating and softening a polished optical element molding material and pressing it with a pair of molding dies. However, this method requires a step of polishing the optical element molding material before press molding,
It was a cause of high cost. Therefore, as a technique for heating a glass gob sized to a predetermined volume by cutting or grinding to make the surface smooth and spherical, Japanese Patent Application Laid-Open No. 61-2
Japanese Patent No. 32236 discloses "a method for producing a material for molding an optical element". This technique will be described with reference to FIG. FIG. 10 is a vertical cross-sectional view of a material processing device of this technique.

This device has a housing 11 made of heat insulating material.
Including 9. In this housing 119, an upright S-shaped tube 116 is installed, and a heating gas generator 120 is connected to the lower end of this tube to guide the heating gas to the tube 11.
6 is to be supplied. A lid 117 for taking out the processed material is provided on the lower surface of the curved portion of the pipe 116.
A heater 118 is provided around the upper portion of the tube 116.
During the work, the heated gas is supplied from the heated gas generator 120 into the pipe 116, and the flow of the heated gas rising in the pipe 116 is generated.

Next, the glass gob 115 is put into this tube 116. This may be done by any suitable means from outside housing 119, or glass gob 115 may be placed in tube 116 and then surrounded by housing 119. At this time, by appropriately selecting the flow rate of the heating gas and the tube diameter of the tube 116, the glass gob 115 can be changed to the tube 116.
It is held in the tube 116 in a floating state without touching the inner wall surface of the tube. Further, by appropriately selecting the temperature and flow rate of the heated gas, the surface of the glass gob 115 softens and becomes smooth, and the glass lump 115 becomes spherical due to the surface tension.

As an example, in the case of SF14, 800 ° C.
When heated to 850 ° C, the glass lump self-deforms into a shape close to a sphere due to the surface tension of the glass material itself, and the surface roughness R
It has a smooth surface of max = 0.04μ or less. When the glass gob 15 becomes a spherical material, the temperature of the heated gas is gradually lowered to a temperature at which it does not self-deform, the flow rate is gradually reduced, the spherical material is lowered in the pipe 116, and the lid 117 is opened. Take it out.

[0006]

However, in the above-mentioned prior art, there is a problem that the number of steps is increased because the optical element molding material must be cut and processed in the preprocessing. In addition, since it is a method of heating and softening an optical glass block in a suspended state by heating gas flowing from below and then gradually lowering the temperature of the heating gas, it takes a long time for each, and one optical element molding There is a problem that the time required to obtain the material becomes long and the cost becomes high. Further, in order to float the glass gob inside the tube, it is necessary to select the flow rate of the heating gas and the tube diameter, and there is a problem that it is not versatile in selecting the tube diameter depending on the size of the glass gob.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the invention according to claim 1, 2 or 3 is to mold a large number of spherical optical elements by a manufacturing apparatus having a simple structure. It is an object of the present invention to provide a versatile method for producing a material for optical element molding, which is capable of continuously producing materials and easily producing materials having different sizes and glass types.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1, 2 or 3 is a method for producing an optical element molding material, wherein the melting point is lower than the transition point of the glass material, A metal whose boiling point is higher than the softening point of the glass material and whose specific gravity is larger than that of the glass material and which does not wet the glass material is melted, and the glass material is heated and softened in the molten metal bath and then cut into glass. An element is obtained, and after heating the glass element while keeping it warm, it is floated on the liquid surface of the molten metal bath to obtain a material for forming an optical element.

[0009]

In the operation of the invention according to claim 1, 2 or 3,
A glass element is obtained by heating and softening the glass material in a molten metal bath to obtain a glass element, and after heating the glass element while heating, the glass element is floated on the liquid surface of the molten metal bath, so that the cut glass element is self-deformed by surface tension. It becomes spherical and floats toward the liquid surface of the molten metal bath due to the difference in specific gravity from the molten metal bath. The surface of the glass element is a mirror surface because it only contacts the molten metal bath. The spherical glass element exposed to the outside air on the liquid surface of the molten metal bath is cooled and solidified to obtain an optical element molding material. In the operation of the invention according to claim 2, in addition to the above operation, since the liquid surface of the molten metal bath and the lower part thereof have a temperature gradient, the glass element has a temperature range from the softening point or higher to the transition point or lower. In the process of ascending to, it is gradually cooled with spheroidization. In the operation of the invention according to claim 3, in addition to the above operation, since the initial shape of the glass material is formed into a rod shape, the rod-shaped tip portion is heated and softened and then cut, and then the cut length is cut. It is possible to feed in, handle the next tip portion in the same manner, and continue the work continuously.

[0010]

[Embodiment 1] FIGS. 1 to 5 show Embodiment 1, FIG. 1 is a front sectional view of an optical element molding material manufacturing apparatus, and FIG. 2 is a side sectional view of an optical element molding material manufacturing apparatus. 3 is a perspective view of a shear of the manufacturing apparatus, FIG. 4 is a plan view of a guide of the manufacturing apparatus,
FIG. 5 is a process diagram of a method for manufacturing a material for molding an optical element.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a metal melting tank, which is filled with a molten metal bath 2. Molten metal bath 2
For this, Sn (melting point: 232 ° C., boiling point: 2260 ° C.) is used. Heaters 3 </ b> A and 3 </ b> B for melting Sn and maintaining the temperature of the molten metal bath 2 are provided on the rear surface and the lower outer surface of the metal melting tank 1. A cooling water pipe 4 is provided on the upper outer surface of the metal melting tank 1 for circulating cooling water to bring the temperature near the liquid surface of the molten metal bath 2 to a temperature lower than the temperature of the bottom surface. ing. Further, shears 6A and 6B for cutting the optical glass rod 5 are provided in the molten metal bath 2.

As shown in FIG. 3A, the shear 6A
Is fixed to the lower end of the shear holding member 10A so that its lower surface is perpendicular to the longitudinal direction of the shear holding member 10A. The shear 6A has an upper surface inclined toward the tip to form a cutting blade 6Aa. On the other hand, shear 6B
Is fixed to the lower end of the shear holding member 10B so that the upper surface thereof is perpendicular to the longitudinal direction of the shear holding member 10B, as shown in FIG. Also, the shear 6B is
The lower surface is inclined toward the tip to form the cutting blade 6Ba. Cutting blades 6Aa, 6Ba at the tips of the shears 6A, 6B
The optical glass rods 5 are cut when the two intersect close to each other. The shear holding members 10A and 10B having the shears 6A and 6B fixed to the lower ends are connected to a shear drive device (not shown) above the metal melting tank 1.
They are driven so that they can move toward and away from each other in the horizontal direction and can move up and down. As a result, the shears 6A and 6B can approach and intersect each other.

The optical glass rod 5 is provided above the metal melting tank 1 so as to be inserted between the shears 6A and 6B and parallel to the longitudinal direction of the shear holding members 10A and 10B. It is held by a glass rod driving device (not shown) for moving 5 up and down. The glass rod driving device is vertically movable independently of the shear driving device. The optical glass rod 5 is made of a glass material.
SF11 (transition point: 467 ° C., softening point: 568 ° C.) is used. Further, when the optical glass rod 5 is moved up and down, the guides 8A and 8B are prevented from shifting from the shears 6A and 6B.
Are fitted to the shear holding members 10A and 10B at positions slightly apart from the tips of the shears 6A and 6B upward. As shown in FIG. 4 (a), the guides 8A and 8B face the V-grooves 8Aa and 8B toward 10A and 10B, respectively.
Ba is provided. As shown in FIGS. 4B and 4C, the optical glass rod 5 is guided so as not to come off from the shears 6A and 6B not only when the guide is closed (b) but also when the guide is opened (c). Has been done.

Next, a manufacturing method using the above-described manufacturing apparatus for the optical element molding material will be described. First, Sn, which is a molten metal, is charged into the metal melting tank 1, and the heaters 3A and 3B are
And melted by heating to form a molten metal bath 2. Heating is performed until the temperature near the bottom of the metal melting tank 1 reaches 850 ° C. (temperature above the softening point of glass), and this temperature is maintained. Further, cooling water is caused to flow through the cooling water pipe 4 above the metal melting tank 1 so that the temperature of the upper part of the molten metal bath 2 is 450 ° C. and 250
The cooling water is adjusted so that the temperature becomes ℃ or more, and this temperature is maintained. In this embodiment, the temperature of the upper part of the molten metal bath 2 is set to 300
Set to ℃. As a result, the molten metal bath 2 has an inclined temperature distribution from the lower portion to the upper portion of the metal melting tank 1. Further, the tips of the shears 6A and 6B are positioned so as to come close to 630 ° C. at the temperature of the molten metal bath.

Next, the optical glass rod 5 is inserted by the glass rod driving device up to the vicinity of the tips of the shears 6A, 6B. Hold for a certain period of time until the tip of the optical glass rod 5 reaches or exceeds the softening point temperature. The optical glass rod 5 is lowered by a certain amount by the glass rod driving device (see (a) of FIG. 5). Subsequently, the shear holding members 10A and 10B move so as to sandwich the optical glass rod 5, and the shears 6A and 6B intersect with each other to cut the optical glass rod 5 (FIG. 5).
(B)). Then, leaving the optical glass rod 5, the shears 6A and 6B are lowered to the lower portion of the metal melting tank 1 through the shear holding members 10A and 10B. As a result, the cut glass element 7 is left in the shears 6A and 6B, and the temperature of the molten metal bath 2 is lowered to a region of 850 ° C. Here, after being held for a certain period of time until the viscosity becomes such that it can be freely deformed, the shears 6A and 6B are opened and the glass element 7 is detached from the shears 6A and 6B (see (c) of FIG. 5).

Here, the specific gravity of Sn in the molten metal bath 2 is 7.
29, since the specific gravity of SF11 of the optical glass rod 5 is 4.79, the glass element 7 separated from the shears 6A and 6B.
Fluctuates and the glass element 7 in the softened state becomes spherical due to surface tension. When the levitation is further continued, the upper part of the molten metal bath 2 is below the transition point temperature, so that the glass element 7 is solidified and floats on the liquid surface of the molten metal bath. As a result, a material for molding an optical element can be obtained. The shears 6A and 6B rise after opening and return to the position before the cutting of the optical glass rod 5, and the optical glass rod 5 is stopped by the glass rod driving device at the position where the optical glass rod 5 was previously stopped (FIG. 5). (A)). After that, by repeating the above-mentioned operation, the optical element molding material can be continuously manufactured.

According to this embodiment, a large number of spherical optical element molding materials can be continuously manufactured by a manufacturing apparatus having a simple structure. Further, since the optical glass rod is cut in the molten metal bath having a temperature higher than the softening point of the glass, the cutting can be performed easily. Furthermore, since the molten metal bath has a larger specific gravity than glass, the glass element rises due to buoyancy, and the glass element in the softened state is spherical due to surface tension and has a regular shape. Furthermore, since the optical element molding material only comes into contact with the molten metal bath, the surface is mirror-finished. Also, since the optical glass rod is used as the material, other glass materials can be easily used as the optical element forming material by simply changing the optical glass rod, and the desired amount can be accurately determined by the descending amount of the optical glass rod. There is also the effect that it can be cut by measuring. In addition, since the molten metal bath has a temperature distribution beforehand, the glass element can change from the softened state to the solidified state, and by simply levitating the glass element from below the molten metal bath, the optical element molding material is manufactured. The manufacturing time can be shortened.

In this embodiment, as shown in FIG. 4, V-grooves 8Aa and 8Ba are formed in the guides 8A and 8B, but instead of this, the optical glass rod is guided in the longitudinal direction. As described above, a semi-cylindrical shape in which the outer diameter of the optical glass rod and the inner diameter are appropriately matched may be used, which is advantageous when the outer diameter of the optical glass rod is small.

In this embodiment, the temperature distribution is provided between the upper and lower portions of the molten metal bath, but it is not always necessary.
The temperature may be almost equal to or higher than the softening point of the optical glass rod, and the cut glass element floats and is cooled at the liquid surface, so it takes time until it becomes a material for optical element molding, but it is practical. The above is possible. In this case, the optical glass rod needs to be pulled out of the molten metal bath after cutting the glass element and kept at an appropriate temperature so as not to destroy the original shape.

Further, although the optical glass rod is used in the present embodiment, it is not necessarily required to be rod-shaped, and even if it is a plate-shaped or band-shaped glass material, by using a guide and a shear corresponding thereto, A material for molding an optical element can be obtained.

[0021]

[Embodiment 2] Since the manufacturing apparatus used in the method for manufacturing the optical element molding material of Embodiment 2 is the same as that of Embodiment 1, the illustration and description thereof are omitted. 1 to 5 to understand the explanation of the manufacturing method.
Please refer to. In this embodiment, the optical glass rod 5
Uses LaSF03 (transition point: 730 ° C., softening point: 808 ° C.) as a glass material.

Next, a method for manufacturing the optical element molding material of this embodiment will be described. First, Sn, which is a molten metal, is put into the metal melting tank 1 and heated and melted by the heaters 3A and 3B to form a molten metal bath 2. The temperature near the bottom of the metal melting tank 1 is 1100 ° C (temperature above the softening point of glass)
Heat to and maintain this temperature. Further, cooling water is caused to flow through the cooling water pipe 4 above the metal melting tank 1, and the cooling water is adjusted so that the temperature above the molten metal bath 2 is 730 ° C. and 250 ° C. or higher, and this temperature is maintained. . In this embodiment, the temperature of the upper portion of the molten metal bath 2 is set to 300 ° C. As a result, the molten metal bath 2 has an inclined temperature distribution from the lower portion to the upper portion of the metal melting tank 1. Also,
The tips of the shears 6A and 6B are 87 at the temperature of the molten metal bath.
It is positioned so that it is near 0 ° C.

The optical glass rod 5 is cut in the same manner as in Example 1. The cut glass element 7 has shears 6A and 6A.
The temperature of the molten metal bath 2 remains 1100 ° C.
Descend to the area. Here, after being held for a certain period of time until the viscosity becomes such that it can be freely deformed, the shear 6A,
6B is opened, and the glass element 7 is separated from the shears 6A and 6B.

Here, the specific gravity of Sn in the molten metal bath 2 is 7.
29, the specific gravity of LaSF03 of the optical glass rod 5 is 5.5.
Since it is 2, the glass element 7 separated from the shears 6A and 6B floats, and the glass element 7 in the softened state is spherical due to the surface tension. When the levitation is further continued, the upper part of the molten metal bath 2 is below the transition point temperature, so that the glass element 7 is solidified and floats on the liquid surface of the molten metal bath. As a result, a material for molding an optical element can be obtained. The other methods for manufacturing the optical element molding material are the same as in Example 1.

According to this embodiment, in addition to the effect of the first embodiment, LaSF03 is used as the optical glass rod.
A material for molding an optical element can be obtained as in Example 1 only by changing the temperature of the molten metal bath.

The modified example described in the first embodiment can be similarly applied to the present embodiment and the third embodiment described later, and the same effect can be obtained.

[0027]

Third Embodiment FIGS. 6 to 9 show a third embodiment, FIG. 6 is a front view of a cutting mechanism of an optical element molding material manufacturing apparatus, and FIGS. 7 and 8 show shear and shear receivers of the cutting mechanism, respectively. FIG. 9 is a detailed view, and FIG. 9 is a process drawing showing a method for manufacturing a material for molding an optical element. The configuration of the optical element molding material manufacturing apparatus of this embodiment is the same as that of the first embodiment except that the cutting mechanism is partially different. Therefore, only different parts will be described, and the description with other drawings will be omitted.

In FIG. 6, the cutting mechanism 20 comprises a half cup-shaped shear 9A and a flat shear receiver 9B.
They are fixed to the shear holding members 11A and 11B, respectively. The upper portions of the shear holding members 11A and 11B are connected to a shear driving device (not shown) as in the first embodiment, and the shear 9A and the shear receiver 9B are moved away from each other to cut the optical glass rod 5 and It is configured so that it can move freely. FIG. 7 shows the details of the shear 9A,
(A) is a side view and (b) is a front view. A semi-circular cutting blade 9Ac is formed by the half cup-shaped inner surface 9Aa and the outer peripheral conical surface 9Ab of the shear 9A. The inner surface 9Aa has a function of reliably retaining the cut glass element 7 in the shear 9A (see FIG. 9). FIG. 8 shows details of the shear receiver 9B, (a) is a side view and (b) is a front view. The receiving surface 9Ba of the shear receiver 9B has a flat shape, and the shear 9A
The semicircular cutting blade 9Ac of the
Is cut (see FIG. 9). In this example, SK11 (transfer point: 535 ° C, softening point: 639 ° C) is used as the glass material for the glass rod 5.

Next, a method of manufacturing the optical element molding material of this embodiment will be described. First, Sn, which is a molten metal, is put into the metal melting tank 1 and heated and melted by the heaters 3A and 3B to form a molten metal bath 2. Heating is performed until the temperature near the bottom of the metal melting tank 1 reaches 950 ° C. (the temperature equal to or higher than the softening point of glass), and this temperature is maintained. Further, cooling water is caused to flow in the cooling water pipe 4 above the metal melting tank 1, and the cooling water is adjusted so that the temperature above the molten metal bath 2 is 639 ° C. and 250 ° C. or higher, and this temperature is maintained. . In this embodiment, the temperature of the upper portion of the molten metal bath 2 is set to 300 ° C. As a result, the molten metal bath 2 has an inclined temperature distribution from the lower portion to the upper portion of the metal melting tank 1. Further, the tip ends of the shear 9A and the shear receiver 9B are positioned so as to come close to 870 ° C. at the temperature of the molten metal bath.

As in the first embodiment, the shear holding member 11
The optical glass rod 5 is moved so as to be sandwiched between A and 11B, and the shear glass 9A and the shear receiver 9B are applied to cut the optical glass rod 5 (see (a) of FIG. 9). Next, the cut glass element 7 remains retained between the half cup-shaped shear 9A and the shear receiver 9B,
The temperature of the molten metal bath 2 is lowered to a region of 950 ° C.
Here, after being held for a certain period of time until the viscosity becomes such that it can be freely deformed, the shear 9A and the shear receiver 9B are opened, and the glass element 7 is sheared 6A and the shear receiver 6
Separate from B.

Here, the specific gravity of Sn in the molten metal bath 2 is 7.
In 29, since the specific gravity of SK11 of the optical glass rod 5 is 2.78, the glass element 7 separated from the shear 9A and the shear receiver 9B floats up, and the glass element 7 in the softened state is spherical due to the surface tension. To do. When the levitation is further continued, the upper part of the molten metal bath 2 is below the transition point temperature, so that the glass element 7 is solidified and floats on the liquid surface of the molten metal bath. As a result, a material for molding an optical element can be obtained. The other methods for manufacturing the optical element molding material are the same as in Example 1.

According to the present embodiment, in addition to the effect of the first embodiment, since the tip of the shear is formed in a half cup shape, the cut glass element stays in the upper part of the shear,
When lowering the shear, you will not accidentally ascend.
Further, since the glass element rises along the inner surface by the opening of the shear and is reliably and promptly released, the glass element does not remain in the shear.

[0033]

According to the invention of claim 1, 2 or 3, a large number of spherical optical element molding materials can be continuously manufactured by a manufacturing apparatus having a simple structure. In addition, it is possible to easily manufacture products having different sizes and glass types. According to the invention of claim 2, in addition to the above effect, since the temperature distribution is given to the molten metal bath in advance, the glass element can change from the softened state to the solidified state,
Just float the glass element from the bottom of the molten metal bath,
A material for molding an optical element can be manufactured, which can shorten the manufacturing time. According to the invention of claim 3, in addition to the above effect, other glass materials can be easily used as a material for optical element molding only by changing the optical glass rod. The desired amount can be measured and cut.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view of an optical element molding material manufacturing apparatus of Example 1.

FIG. 2 is a side sectional view of an apparatus for manufacturing a material for molding an optical element of Example 1.

FIG. 3 is a perspective view of a shear of the manufacturing apparatus according to the first embodiment.

FIG. 4 is a plan view of a guide of the manufacturing apparatus according to the first embodiment.

FIG. 5 is a process drawing of the method for manufacturing the optical element molding material of Example 1.

FIG. 6 is a front view of a cutting mechanism of an optical element molding material manufacturing apparatus according to a third exemplary embodiment.

FIG. 7 is a detailed view of a shear of the cutting mechanism according to the third embodiment.

FIG. 8 is a detailed view of a shear receiver of the cutting mechanism of the third embodiment.

FIG. 9 is a process drawing showing the method for manufacturing the optical element molding material of Example 3.

FIG. 10 is a vertical sectional view of a conventional material processing apparatus.

[Explanation of symbols]

 1 Metal Melt Tank 2 Molten Metal Bath 3A, 3B Heater 4 Cooling Water Pipe 5 Optical Glass Rod 6A, 6B Shear 7 Glass Element 8A, 8B Shear Guide 10A, 10B Shear Holding Member

Claims (3)

[Claims] 1. The melting point is lower than the transition point of the glass material,
A metal whose boiling point is higher than the softening point of the glass material and whose specific gravity is larger than that of the glass material and which does not wet the glass material is melted, and the glass material is heated and softened in the molten metal bath and then cut into glass. A method for producing an optical element forming material, which comprises obtaining an element, heating the glass element while keeping it warm, and then levitating it to the liquid surface of a molten metal bath to obtain an optical element forming material. 2. The temperature of the molten metal bath is lower than the transition point of the glass material near the liquid surface and higher than the softening point of the glass material below the liquid surface. The method for producing an optical element molding material according to claim 1, wherein the material has a gradient. 3. The method for producing an optical element molding material according to claim 1, wherein the glass material cut in the molten metal bath has a rod-shaped initial shape.