JP3187903B2 - Glass optical element molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding of a glass optical element in which a heated glass material is placed between a mold having an upper mold and a lower mold, and the glass material is pressed to produce a glass optical element. Related to the device.

[0002]

2. Description of the Related Art In the above molding apparatus, particularly when molding a glass molded article having a large difference in wall thickness, the amount of shrinkage differs due to a difference in cooling temperature gradient between a thick section and a thin section. It is not possible to cool while applying a uniform pressure with a molding die, which causes problems such as impairing the shape accuracy. Therefore, JP-A-2-55235 and JP-A-2-111635
A molding die has been proposed.

A molding die disclosed in Japanese Patent Application Laid-Open No. 2-55235 is a molding die for precision glass press comprising a pair of a convex molding die and a body die, in which a hollow portion is provided in a part of a die which is in contact with a heat source to form a concave lens. It is configured such that pressure cooling can be performed while maintaining the temperature at the center of the optical surface portion higher than the temperature of the non-optical surface portion. In this mold, the air heat insulation layer is interposed by the hollow part of the mold, so that the temperature at the center of the lens optical surface where the amount of shrinkage is small during pressurized cooling is kept high, and the non-optical surface side where the amount of shrinkage is large is By cooling while reducing the difference in shrinkage, a molded lens having good shape accuracy and high accuracy is obtained.

[0004] A molding die disclosed in Japanese Patent Application Laid-Open No. 2-111635 has a first molding die having a concave first optical surface, a second molding die having a concave second optical surface, and And a body die for guiding the first and second molding dies, and a concave portion is provided on the outer peripheral portion of the back surface of at least one of the optical surfaces of the first and second molding dies. Further, a concave portion is not provided in an outer peripheral portion of the molding die, and a second trunk die made of a material having lower thermal conductivity than the trunk die is provided outside the trunk die. In addition, a first optical surface having a convex first optical surface
, A second mold having a convex second optical surface, and a body mold for guiding the first and second molds, wherein the first and second molds are provided. A concave portion is provided at the center of the back surface of at least one of the optical surfaces.
In this molding die, the heating stage in each step does not come into contact with the concave portion of the molding die, and the heat transfer is controlled, so that a temperature difference is hardly generated in the glass between the molding dies. Further, by providing the second body die outside the body die, it is possible to prevent heat from being taken away from the outer periphery of the lens, thereby making it difficult to generate a temperature difference inside the glass. The mold having the concave optical surface and the mold using the second body mold are used for molding the convex lens and the convex meniscus lens, while the mold having the convex optical surface is the concave lens and the concave meniscus lens. It is intended to manufacture a high-precision press lens by using it for molding.

[0005]

However, Japanese Patent Application Laid-Open No. 2-5 / 1990
In the mold described in Japanese Patent No. 5235, a hollow portion must be provided in a part of the mold, and the structure of the mold becomes complicated, resulting in an increase in processing cost of the mold. Also,
In order to control the temperature at the time of pressurized cooling of the glass material, when the shape of the hollow part becomes complicated, the processing of the molding die becomes difficult because the molding die is difficult to process, and the cost further increases, In some cases, processing was not possible depending on the shape. Further, it is necessary to provide a cutout portion in each of the molds according to the shape of the optical element to be molded, and it takes a lot of time to create the molds.

[0006] On the other hand, even in the molding die disclosed in Japanese Patent Application Laid-Open No. Hei 2-111635, a cut-out portion must be provided in the same manner as in the above-mentioned molding die, and thus has the same problem as described above. Further, when the second body die is provided outside the body die, the cooling is performed under pressure while suppressing the heat radiation from the outer peripheral portion of the glass material, so that the cooling efficiency is poor and the cooling requires a long time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a method for shrinking a glass optical element having a large thickness difference between an outer peripheral portion and a central portion without providing a hollow portion in a molding die. It is an object of the present invention to provide a molding apparatus for a glass optical element, which can be molded in a short time, at low cost and with high precision by making equal.

[0008]

In order to achieve the above object, the present invention relates to a glass optical element forming apparatus in which a forming die comprising an upper die and a lower die is positioned and mounted on a pair of die mounts, respectively. A heat transfer member for controlling the amount of heat flowing from the mold to the mold mount is provided between the mold and the mold mount. Further, the heat transfer member may be configured to have a cavity at a position corresponding to the thin portion of the glass optical element between the upper mold and the lower mold. Further, the heat transfer member is
It may be composed of composite materials having different thermal conductivity.

[0009]

In the above construction, the glass material pressed by the upper mold and the lower mold after being softened by heating, the amount of heat of the glass material is transferred from the mold to the mold mount when cooled and pressed by the mold. Cooled by going. Therefore, an air heat insulating layer can be provided between the mold and the mold mount to provide a distribution of the amount of heat conducted to the heat transfer member, thereby delaying an increase in the viscosity of the thin glass portion during cooling. Further, by forming the heat transfer member separately from the mold, the heat transfer member can be formed of a material having relatively good workability. Further, by forming the heat transfer member with composite materials having different thermal conductivity, the heat transfer member can be formed with a simple shape.

[0010]

Embodiment 1 FIG. 1 is a sectional view showing a mold part in a glass optical element forming apparatus according to Embodiment 1 of the present invention, and FIG. 2 shows a glass optical element forming apparatus according to Embodiment 1 of the present invention. In a sectional view, a convex lens forming apparatus is shown. In FIG. 2, reference numeral 1 denotes a forming section, and a heating furnace 2 having a heater 2a is adjacent to the forming section. The periphery of the forming part 1 and the heating furnace 2
A cover 3 made of a quartz glass tube or a stainless steel tube is closed by an upper base 4 and a lower base 5, and a molding chamber 6 is formed by the cover 3, the upper base 4 and the lower base 5. A gas nozzle 7 connected to an atmosphere gas supply device (not shown) is provided through the upper and lower bases 4 and 5, and nitrogen gas, inert gas or reduction gas supplied into the molding chamber 6 via the gas nozzle 7 is provided. The oxidizing gas prevents the inside of the molding chamber 6 from being oxidized. The upper base 4 and the lower base 5 are connected via a member (not shown), and are configured so that the mutual distance and position between the upper base 4 and the lower base 5 do not change. .

In the molding chamber 6, an upper mold section 8 and a lower mold section 9 are provided.
Are opposed to each other on the same axis so that they can approach and separate relatively. The upper mold part 8 is fixed to the upper base 4, and the lower mold part 9 is fixed to the tip of the press shaft 10. The press shaft 10 is held slidably in the axial direction by a bearing (sliding bearing) 12 in a housing 11 fixed to the lower base 5, and the driving cylinder 1 connected at its lower end.
3 is provided so as to be vertically movable.

As shown in FIG. 1, the upper mold section 8 includes an upper mold mount 14, an upper mold heater 15, a heat transfer plate 16 and an upper mold 17.
It is composed of The upper die mount 14 is made of Si ₃ N ₄
-Al ₂ O ₃ ceramics (linear expansion coefficient 3.5 × 10
^-6 ), the upper end of which is fixed to the upper base 4 and the lower end surface (tip surface) thereof is provided with a concave portion 14a for positioning and fixing the upper die 17. The bottom surface is flat. Upper heater 1
Numeral 5 is embedded near the bottom surface of the concave portion 14a in the upper die mount 14, is connected to a temperature control device (not shown), and can be controlled to a predetermined temperature.

The heat transfer plate 16 is made of a heat-resistant stainless steel (thermal conductivity: 0.04 cal / cm · sec · ° C., Vickers hardness: 196), and has a parallel end face provided with a step 16a on the outer periphery of the lower part (upper side in the figure). And the entire height (distance between the end faces) is formed smaller than the depth of the concave portion 14a of the upper die mount 14. This heat transfer panel 16
The recess 14a is arranged in the recess 14a such that the bottom surface of the recess 14a is in contact with the lower end surface (hereinafter, referred to as the lower end surface).

The upper die 17 is made of a cemented carbide (having a thermal conductivity of 0.3 c).
al / cm · sec · ° C., Vickers hardness 1450, coefficient of linear expansion 4.8 × 10 ⁻⁶ ), and its molding surface 17a
Is mirror-finished in a predetermined concave shape, and
An end face on the opposite side of a (hereinafter referred to as a lower end face) is flat-finished. The upper mold 17 is provided at the tip of the upper mold mount 14, and the lower part thereof is housed in the recess 14a. The outer diameter of the lower outer peripheral surface of the upper die 17 housed in the concave portion 14a is such that when the upper die 17 is heated to a predetermined temperature by the upper die heater 15, the lower outer peripheral surface is in close contact with the inner peripheral surface of the concave portion 14a. In order to be fixed, it is formed to have a predetermined clearance between the inner peripheral surfaces of the concave portions 14a and to have a dimension in consideration of a linear expansion coefficient. At this time, the upper die mount 14, the heat transfer plate 16 and the upper die 17 are in close contact with each other so that heat conduction is performed well, and the step 16a of the heat transfer plate 16 and the lower end surface of the upper die 17 are in contact with each other. A cavity 18 is formed therebetween.

The lower mold section 9 is composed of a lower mold mount 19, a lower mold heater 20, a heat transfer panel 21 and a lower mold 22 in the same manner as the upper mold section 8. The description is omitted because it is the same as the mold portion 8.

In FIG. 1, reference numeral 23 denotes a carrier on which the optical glass material 24 and the optical element after press molding are mounted and transported.
5 inside the heating furnace 2 and the upper and lower dies 17, 22
It is configured to be conveyed in between.

Next, the operation of the molding apparatus of this embodiment will be described. First, nitrogen gas or the like is supplied from the gas nozzles 7 of the upper and lower bases 4 and 5 into the molding chamber 6 to replace the oxygen concentration inside the molding chamber 6 with 1% or less. Next, the heating furnace 2, the upper mold part 8, and the lower mold part 9 are heated to a predetermined temperature by the heater 2a, the upper heater 15, and the lower heater 20. In this state, the optical glass material 24 is placed in the carrier 23, and the carrier transport arm 25 is transported into the heating furnace 2;
The heating and softening treatment is performed by the upper and lower heaters 2a until the optical glass material 24 becomes a moldable state (softening point).

Next, the transfer arm 25 is advanced, and the optical glass material 24 is moved together with the carrier 23 into the upper mold 17 and the lower mold 2.
Convey between two. Then, the lower mold 22 is moved upward by the cylinder 13 via the press shaft 10, and the optical glass material 24 in a softened state is press-molded by the molding surfaces 17 a and 22 a of the upper and lower molds 17 and 22. At this time, the upper and lower dies 17, 2
Since the air heat insulating layer is formed by the hollow portion 18 on the outer peripheral portion of the lower end surface of 2, the cooling rate of the outer peripheral surface of the optical surface portion 24a of the press-molded optical glass material 24 is slowed down. On the other hand, the center of the optical surface portion 24a and its vicinity are located on the heat transfer plate 1.
The heat escapes to the upper and lower mounts 14 and 19 through 6, 21 so that they cool rapidly. Therefore, the optical glass material 2
The optical glass material 24 is pressurized and cooled while keeping the outer peripheral temperature, which is the thin portion, of the sample 4 higher than the central portion, which is the thick portion,
As a result of the uniform shrinkage, an optical element having a desired shape accuracy can be easily formed.

After the press forming between the upper and lower dies 17 and 22 is completed, the lower dies 22 are lowered and released, and a lehr is provided on the side of the forming chamber 6 opposite to the heating furnace 2 (not shown). The press-formed optical element is conveyed by the transfer arm 25 and gradually cooled. After the completion of the slow cooling, the optical element is taken out of the slow cooling furnace.

According to the present embodiment, the heat transfer plates 16 and 21 can be formed separately from the upper and lower dies 17 and 22 using a material having relatively good workability such as heat-resistant stainless steel. The shapes 16 and 21 can be arbitrarily and easily processed, and an optical element having good shape accuracy can be obtained at low cost.

FIG. 3 shows the heat transfer plates 16 and 2 in the first embodiment.
It is sectional drawing of the heat transfer board 25 which shows the modification of 1. Heat transfer panel 2
5 is configured by providing a space 25a from the edge to the center. Even with this heat transfer plate 25, the same operation and effect as those of the first embodiment can be obtained. In the first embodiment and the modified examples, the heat-transfer panels 16, 21, and 25 are described by taking heat-resistant stainless steel as an example. However, the present invention is not limited thereto. For example, free-cutting ceramics and heat-resistant metal may be used. It can be implemented using The same applies to the following embodiments.

[0022]

Embodiment 2 FIG. 4 is a plan view of a heat transfer plate in a glass optical element forming apparatus according to a second embodiment of the present invention, and FIG. 5 is a sectional view of the heat transfer plate. The heat transfer plate 26 of the present embodiment is configured such that a plurality of heat insulating holes 26a formed of through holes opened in both flat portions are distributed more toward the outer peripheral portion. The diameter of the heat insulating hole 26a may be changed and the total area thereof may be changed. Further, the heat insulating hole 26a may be formed in a concave portion opened on one surface or both surfaces without forming a through hole. Other configurations are the same as the configuration of the molding apparatus of the first embodiment.

In the present embodiment, the cooling rate of the outer peripheral portion of the optical glass material can be freely controlled to be lower than the center by the distribution of the heat insulating holes 26a, and the same operation and effect as in the first embodiment can be obtained. .

[0024]

Third Embodiment FIG. 6 is a sectional view of a heat transfer plate in a glass optical element forming apparatus according to a third embodiment of the present invention. The heat transfer panel 27 of the present embodiment is configured such that the surface roughness of the central portion and the outer peripheral portion of both flat portions are different from each other.
The outer peripheral portion 27b is formed so as to have a higher surface roughness than the surface roughness a.

In the present embodiment, a fine air heat insulating layer is distributed and interposed between the upper and lower mold mounts and the upper and lower molds in the outer peripheral portion having a rough surface roughness. Functions and effects can be obtained. Further, it is easy to form the heat transfer board 27 into a desired shape, and the heat transfer board 27 can be easily formed at a desired shape at low cost.

[0026]

Fourth Embodiment FIG. 7 is a sectional view showing a mold part in a molding apparatus for a glass optical element according to a fourth embodiment of the present invention. The molding apparatus of this embodiment can press-mold a concave lens,
The heat transfer panels 28 and 29 and the upper and lower dies 30 and 31 are configured, and the other configuration is the same as that of the first embodiment. That is, the heat transfer plates 28 and 29 have hollow portions 32 and 33 at the center,
It is formed in a ring shape having an end surface parallel to the outer peripheral portion. Also, the molding surfaces 30a, 31a of the upper and lower dies 30, 31
Is formed in a predetermined convex shape and is mirror-finished.

In this embodiment, the upper and lower mounts 14 and 19 are formed by the cavities 32 and 33 of the heat transfer panels 28 and 29.
Since the air heat insulating layer is formed between the upper and lower dies 30, 31, the cooling rate at the center of the optical surface portion 24a of the optical glass material 24 is reduced. On the other hand, since the outer peripheral portion of the optical surface portion 24a conducts heat through the heat transfer plates 28 and 29, it is rapidly cooled. Therefore, the optical glass material 24 is pressurized and cooled and shrinks evenly while maintaining the temperature of the central portion which is the thin portion of the optical glass material 24 higher than that of the outer peripheral portion which is the thick portion. Similar functions and effects can be obtained.

FIG. 8 shows the heat transfer plates 28 and 2 in the fourth embodiment.
It is sectional drawing of the heat transfer board 35 which shows the modification of FIG. Heat transfer panel 3
Reference numeral 5 denotes a configuration in which a space portion 35a formed of a concave portion is provided at the center of the plane portion.
4 or may be formed on any flat portion in contact with the lower mold mount 19, or may be formed on both flat portions and implemented.
The same operation and effect as those of the fourth embodiment can be obtained.

[0029]

Fifth Embodiment FIG. 9 is a plan view of a heat transfer plate in a glass optical element forming apparatus according to a fifth embodiment of the present invention, and FIG. 10 is a sectional view of the heat transfer plate. The heat transfer board 36 of the present embodiment is configured such that a plurality of heat insulating holes 36a formed of through holes opened in both flat portions are distributed more toward the center. The diameter of the heat insulating hole 36a may be changed, and the heat insulating hole 36a may be formed not as a through hole but as a concave portion opened on one side or both sides. Other configurations are the same as the configuration of the molding apparatus of the fourth embodiment.

In the present embodiment, the central portion of the optical glass material can be freely controlled at a lower cooling rate than the outer peripheral portion by the distribution of the heat insulating holes 36a, and the same operation and effect as those of the fourth embodiment can be obtained. it can.

[0031]

Sixth Embodiment FIG. 11 is a sectional view of a heat transfer plate in a glass optical element forming apparatus according to a sixth embodiment of the present invention. The heat transfer plate 37 of the present embodiment is configured such that the surface roughness of the central portion and the outer peripheral portion of both flat portions are different from each other.
The surface roughness is formed so as to be closer to the central portion 37b than the surface roughness of 7a.

In the present embodiment, a fine air heat insulating layer is distributed and interposed between the upper and lower mold mounts and the upper and lower molds in the central portion having a rough surface roughness. Similar functions and effects can be obtained. Further, it is easy to form the heat transfer plate 37 into a desired surface roughness, and the heat transfer plate 37 can be easily formed into a desired shape at low cost.

[0033]

Seventh Embodiment FIG. 12 is a cross-sectional view of a heat transfer plate in a glass optical element forming apparatus according to a seventh embodiment of the present invention. The heat transfer plate 38 of this embodiment is used for forming a convex lens, and is composed of two members made of materials having different thermal conductivity. That is, the heat transfer plate 38 is formed integrally by forming the outer peripheral member 38a into a ring shape, fitting the center member 38b to the center of the outer peripheral member 38a, and has a heat conductivity that is closer to that of the center member 38b. Is made of a material larger than the outer peripheral member 38a. Table 1 illustrates combinations of the material of the outer peripheral member 38a and the material of the central member 38b.

[0034]

[Table 1]

In the present embodiment, since the outer peripheral member 38a has a low thermal conductivity, the cooling rate of the outer periphery of the optical surface of the optical glass material is reduced. On the other hand, the center of the optical surface portion conducts heat through the central member 38b having a large heat conductivity.
Cools rapidly. Therefore, while maintaining the temperature of the outer peripheral portion, which is the thin portion of the optical glass material, higher than that of the central portion, which is the thick portion, the optical glass material is pressurized and cooled, and contracts uniformly, and the like, The effect can be obtained.
In addition, a heat transfer panel can be easily obtained by considering the difference in thermal conductivity between the outer peripheral member 38a and the outer peripheral member 38b according to the thickness difference of the optical element. When the concave lens is molded, the outer peripheral member 3
8a can be implemented by forming a heat transfer plate with a material having a higher thermal conductivity than the central member 38b.

[0036]

According to the present invention, since the heat transfer member is provided between the molding die and the mold mount, a distribution is given to the amount of heat to be electrically driven from the glass material, and cooling at the thin portion of the glass material being cooled is performed. In addition to pressing down, cooling in the thick portion can be promoted. Therefore, an increase in the viscosity of the thin glass portion can be delayed, and an optical element having good shape accuracy can be formed. Further, since the heat transfer member is formed separately from the molding die, a material having relatively good workability can be selected as the material of the heat transfer member, and an inexpensive optical element can be obtained. Further, by forming the heat transfer member from composite materials having different thermal conductivities, the heat transfer member can be formed by combining materials having simple shapes.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a mold part in a glass material forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a glass optical element forming apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view illustrating a modified example of the heat transfer panel in the first embodiment.

FIG. 4 is a plan view showing a heat transfer plate in a glass optical element forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of the heat transfer board shown in FIG.

FIG. 6 is a cross-sectional view illustrating a heat transfer plate in a glass optical element forming apparatus according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a mold part in a glass optical element forming apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a modification of the heat transfer panel in the first embodiment.

FIG. 9 is a plan view showing a heat transfer plate in a glass optical element forming apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view of the heat transfer panel shown in FIG.

FIG. 11 is a cross-sectional view showing a heat transfer plate in a glass optical element forming apparatus according to Embodiment 6 of the present invention.

FIG. 12 is a cross-sectional view showing a heat transfer plate in a glass optical element forming apparatus according to a seventh embodiment of the present invention.

[Explanation of symbols]

 14 Upper die mount 16, 21, 25, 26, 27, 28, 29 35, 36, 37, 38 Heat transfer board 17 Upper die 18 Cavity part 19 Lower die mount 22 Lower die

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C03B 9/00-17/06 C03B 19/00-19/10

Claims (3)

(57) [Claims] In a glass optical element forming apparatus in which a mold including an upper mold and a lower mold is positioned and mounted on a pair of mold mounts, a heat transfer member for controlling the amount of heat flowing from the mold to the mold mount is provided. A molding apparatus for a glass optical element, provided between a molding die and a mold mount. 2. The glass optical element according to claim 1, wherein the heat transfer member has a cavity at a position corresponding to a thin portion of the glass optical element between the upper mold and the lower mold. apparatus. 3. The apparatus according to claim 1, wherein the heat transfer member is made of a composite material having different thermal conductivity.