JPH0472777B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an apparatus for molding optical elements by press molding, and more specifically, the present invention relates to an apparatus for molding optical elements by press molding, and more specifically, the present invention relates to a molding device for optical elements by press molding, and more specifically, it is possible to improve surface accuracy without going through processes such as grinding and polishing after press molding. The present invention also relates to an apparatus for molding an optical element with good weight accuracy or a preform suitable for reheat pressing thereof.

(Prior art) In recent years, by press-molding a glass material in a mold with a predetermined surface precision,
Methods have been developed for molding high-precision optical elements that do not require post-processing such as grinding and polishing.

This press molding method generally includes a heat press method and a direct press method.

In the reheat press method, the necessary amount of glass material that has been melted and solidified in advance is cut, the weight is adjusted using methods such as sanding, and the resulting glass pellets are placed in a mold for molding. This is a method of molding an optical element by heating the molds simultaneously or separately to a pressing temperature, and then pressing and transferring the optical functional surface formed on the mold by press molding.

On the other hand, in the direct press method, the necessary amount of molten glass flowing out or being pressed from a molten glass outflow orifice is cut by a cutting blade, and the cut is directly dropped into a mold or introduced by a chute. This is a method of molding an optical element by pressing a mold for post-molding.

In addition, in the above reheat press method, molten glass is put into a mold and press-formed into a final product, as in the above direct press method, without going through low productivity steps such as cutting and sanding. After obtaining a preform with a similar shape, press molding is performed by placing the preform into a mold having an optical functional surface with the same or higher precision than the shape and area of the final product. There is a way.

(Problems to be solved by the invention) Optical elements obtained by these molding methods are
A certain level of surface accuracy and dimensional accuracy are required to obtain good image formation quality, and for this reason, in any of the above methods, the glass material supplied for press forming to obtain the final product must be sufficiently weight-adjusted. must be done.

However, in the above-mentioned method of press forming using small glass lumps, the weight of the glass lumps is adjusted by cutting, sanding, etc., so grit remains on the surface of the molded product, and the glass small lumps are removed before press forming. When heating the lump, there is a problem in that the mold release agent applied to prevent the glass and the heating tray from fusing together bites into the surface of the molded product during pressing, significantly deteriorating the surface precision of the molded product.

Further, in the method of directly press-molding using molten glass, there is a problem that cutting marks called shear marks are generated on the molded product when cutting with a cutting blade, and the surface precision of the molded product is deteriorated. In addition, in this press molding method, the weight of the molded product is adjusted by cutting the molten glass flow, so weight fluctuations may occur in the molded product due to temperature changes in the molten glass flow, cutting timing, pulsation of the glass flow, etc. However, there is also the problem that a predetermined dimensional accuracy cannot be obtained.

In addition, as a press molding method which particularly prevents the occurrence of shear marks, there is a method described in Japanese Patent Publication No. 41-9190 or Japanese Patent Application Laid-open No. 132523/1983.

In the molding method described in Japanese Patent Publication No. 41-9190, press molding is performed by pressing a mold in a direction perpendicular to the direction of flow of molten glass to fill the mold cavity with molten glass. When the mold is pressed, a phenomenon occurs in which excess glass in the mold cavity flows out from between the mold and the anvil facing the mold. As the pressing operation of the mold progresses, this excess glass increases its outflow resistance and is cooled by the mold, increasing its viscosity, until it is completely cut off between the mold and the opposing anvil. The molded product is cooled without being completely wet, and a protruding portion is formed on the outer periphery of the molded product. Therefore, after press forming, it is necessary to break the protruding portion and finish the broken surface. Furthermore, due to variations in the size of the molten glass flow, the glass thickness between the above-mentioned molded product and the protruding portion changes, causing variations in the thickness of the molded product, making it difficult to adjust the weight with high precision. There is also the problem of not having one.

On the other hand, in the molding method described in JP-A No. 61-132523, the precision of the molded product depends on the size of the flowing glass body before punching it, and highly accurate dimensions and shapes can be produced. A rod or glass sheet is required.

In order to solve the above-mentioned problems, the present inventors have made a molded product free from surface defects such as shear marks,
A method of manufacturing an optical element with very good dimensional accuracy and weight accuracy has already been proposed.

The present invention relates to this manufacturing method, in which the outer periphery of a part to be molded formed by a pair of molds is cut and separated using a cutting member, and when forming the outer periphery shape of a molded product, the cut surface is made to have good properties. An object of the present invention is to provide a molding device that can suppress the occurrence of distortion, sink marks, etc.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the optical element molding apparatus of the present invention is arranged opposite to each other so as to narrow the glass fluid, and presses the glass fluid to form a molded part. An optical system comprising a pair of molds, a cutting member provided on the outer periphery of the mold to cut and separate the part to be molded from other parts, and means for heating the mold and the cutting member. In the device molding apparatus, the glass fluid has a viscosity of 10 ³ to 10 ⁵ poise, and the temperature of the mold when pressing the glass fluid is a temperature corresponding to a glass viscosity of 10 ⁸ poise, and a glass transition. The temperature of the cutting member when cutting the part to be formed is within the range of 100°C lower than the point (corresponding to about 10 ¹³ poise in terms of glass viscosity), and the temperature of the cutting member when cutting the part to be formed is within the range of 100°C lower than the temperature of the cutting member when pressing the glass fluid. It is characterized by being within ±50℃ of the mold temperature.

(Function) In the optical element molding apparatus configured as described above, if each mold member constituting a pair of molds used is a first mold member and a second mold member, these mold members The respective molding surfaces are arranged to face each other with the glass fluid interposed therebetween. When the glass fluid is, for example, molten glass flowing out from a melting furnace through a nozzle, the arrangement of such molding molds is such that the first mold member and The molding surfaces of the second mold member can be arranged to face each other.

In addition, if the glass fluid is in the form of a rod or sheet that has fluidity by reheating a molded glass fluid, in addition to the above arrangement,
It is also possible to arrange the first mold member and the second mold member to face each other in the vertical direction.

Therefore, for example, when a mold according to the present invention is constructed for a flowing molten glass fluid, each mold member is pressed against each other from a direction substantially perpendicular to the direction of flow of the glass fluid, and the mold members are pressed against each other from a direction substantially perpendicular to the direction of flow of the glass fluid. By adjusting the timing of pressing each mold member against the glass fluid, it is possible to form a molded part while avoiding the tip of the glass fluid, that is, cutting marks.

The wall thickness of the part to be formed is determined by setting the cavity of the forming die. This cavity can be set by the distance between the molding surfaces when the mold members are closest to each other during press molding. Excess glass generated when pressing the mold member freely flows out to the outside of the molding surface, and the thickness of the molded product is not affected by the size of the glass flow.

The optimum viscosity of the glass fluid in the present invention is 10 ³ to 10 ⁵ poise. If the glass viscosity is lower than 10 ³ , it is likely to cause fusion with the mold during molding, and if it is higher than 10 ⁵ poise, cracks will easily occur when cutting with a cutting member. Note that when the viscosity of the glass fluid is lower than 10 poise, the glass fluid becomes filamentous and the required glass capacity within the cavity of the molding die becomes insufficient. On the other hand, when the glass viscosity is higher than 10 ⁷ poise, it becomes difficult to cut the glass after press molding.

In addition to the above-mentioned molten glass, the glass fluid used in the present invention may be one obtained by reheating a previously formed glass rod or sheet.

The temperature of the mold during molding (when pressing the mold) ranges from a temperature corresponding to 10 ⁸ poise in terms of glass viscosity to a glass transition point (hereinafter referred to as Tg, which corresponds to approximately 10 ¹³ poise in terms of glass viscosity). ) than 100℃
It is necessary to set it within a low temperature range (Tg - 100℃). If the mold temperature exceeds a temperature equivalent to 10 ⁸ poise, the hardness of the glass surface in the molded part after press forming until cutting is slow, and when the outer periphery of the molded part is cut and formed. , predetermined shape accuracy and surface accuracy cannot be obtained. or,
This is undesirable because the glass and the molding surface of the mold tend to be fused together, and the surface precision of the obtained molded product is significantly reduced. On the other hand, if the mold temperature is lower than Tg - 100°C, cutting the outer periphery of the part to be molded will not only be difficult, but may also cause cracks at the cut part.

Further, the temperature of the cutting member when cutting the part to be molded is suitably within the range of ±50°C of the temperature of the mold when pressing the glass fluid. If the temperature of the cutting member is higher than 50°C compared to the temperature of the mold when pressing the glass fluid, it will tend to fuse with the molded part during cutting, and if it is lower than 50°C, cracks will easily occur from the cut part during cutting. Become.

Under such conditions, after pressing the glass fluid with each mold member to form a molded part, the molded part and other surplus glass are cut and separated using a cutting member provided on the outer periphery of the mold. The outer peripheral shape of the molded part is formed.

The molded product thus obtained is free from surface defects such as shear marks, since it is formed from a portion that does not contain cutting marks of the glass fluid, as described above.
By forming the outer periphery of the molded part using the set cavity and cutting member, a molded product with high shape accuracy and weight accuracy can be obtained. In addition, since the functional surface of this molded product is formed by transferring the molding surface of each mold member, the surface texture of each molding surface can be made with high precision equal to or higher than that of the desired molded product. By finishing the product and press-molding it, a molded product with a high-precision surface can be obtained.

In addition, the softened glass fluid in the present invention includes:
As mentioned above, in addition to molten glass, glass obtained by reheating a previously formed glass rod or sheet may also be used.

Regarding the viscosity at the time of taking out the molded product, when the molded product is used as a preform for reheat press, it is sufficient to cool it to a viscosity of 10 ⁸ poise or more, but when used as is for optical lenses etc. Cool in the mold while applying pressure,
If it is taken out when the viscosity reaches about 10 ^{to 14.5} poise, it can be used as an optical element with good shape accuracy and surface accuracy.

Note that in order to maintain the lifespan of the mold and the cutting member, it is desirable that the press molding and subsequent cutting treatment in the present invention be performed in a non-oxidizing atmosphere.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1a is a schematic cross-sectional view of a press-forming apparatus used in an embodiment of the present invention, and FIG. 1b is an enlarged cross-sectional view of a main part of the press-forming apparatus shown in FIG. 1a with a heating device connected thereto. .

In FIG. 1a, 1 is a nozzle through which molten glass flows out from a melting furnace (not shown), 2 is a glass fluid flowing out from this nozzle, and 3 is a cut mark produced at the tip of the glass fluid 2. 4 is nozzle 1
It is a cutting blade that is provided below the glass fluid 2 and cuts the glass fluid 2 by opening and closing operations by a drive device (not shown). When the cutting blade 4 operates and cuts the glass fluid 2 midway, a cutting mark 3 is generated.

The press molding apparatus shown in this embodiment is configured for a type in which glass fluid 2 flows down from a nozzle 1, and includes a first mold member 5 and a second mold member constituting a pair of molds. The members 6 are arranged to face each other so as to narrow the glass fluid 2 from a substantially right angle direction. Each mold member 5, 6 has a molding surface 5a, 6a which is mirror-finished on each opposing surface.

The first mold member 5 is held by the slider 14,
This slider 14 is slidably supported by a slide shaft 18. 16 is slider 14
This is the cylinder that drives the cylinder 1.
6, the slider 14 moves in the sliding direction of the slide shaft 18, and the first mold member 5 is pressed.

On the other hand, the second mold member 6 is connected to a cylinder 13 via an adapter 12, and this cylinder 1
3 causes the second mold member 6 to be pressed.

A cavity formed by each molding surface 5a, 6a of these mold members 5, 6 is formed by each cylinder 13,
It can be set by 16 strokes.

Further, a cutting ring 7 having a cutting blade formed on the side of the first mold member 5 is provided on the outer periphery of the second mold member 6, and this cutting ring 7 is connected to the slide shaft 18.
The slider 15 is slidably supported by the slider 15. Furthermore, the slider 15 is connected to a cylinder 17 whose actuation allows the cutting ring 7 to slide around the outer periphery of the second mold part 6 in a movement independent of the second mold part 6. .

Further, 19 is the base of the entire device, which includes cylinders 13, 16, 17 and a slide shaft 18.
is firmly supported.

Furthermore, as shown in FIG. 1b, the first mold member 5 and the second mold member 6 have built-in heating heaters 30 and 31 each having a built-in thermocouple for measuring mold temperature. 32 and 33 are conducting wires connected to the respective heaters. Also, the cutting ring 7 is equipped with a heater 3.
4, 35 and a thermocouple 39 are built-in. 3
6, 37, and 38 are conducting wires connected to a heater and a thermocouple, respectively. These conductive wires are connected to a controller 40 installed outside the molding apparatus. This controller includes a power regulator 4
1. A temperature regulator 42 and an external power supply 43 for a power regulator 41 are provided.

The thermocouple 36 is connected to a temperature regulator 42, and the measured value detected by the thermocouple 36 is sent as an output control signal to a power regulator 41, which controls the cutting ring 7 by the heaters 34 and 35. is heated.

The illustrated controller described above is connected to the cutting ring 7, but similar controllers (not shown) are also connected to the mold members 5 and 6.

These controllers apply temperature changes to the mold members 5, 6 according to the molding process, and also control the temperature of the cutting ring 7 according to the temperature of the mold members 5, 6.

Next, the operation of this device is shown in Figures 2 to 7 and 8.
This will be explained using figures.

2 to 7 are main part sectional views showing the operating state of this device in each process order, and FIG. , is a timing chart showing the operation timing of each part of the cutting blade 4 and the cutting ring 7, and the horizontal axis shows time T. The operation timing of these actuating parts can be controlled by a controller (not shown) connected to each actuating part.

FIG. 2 shows the state immediately before press molding, with glass fluid 2 flowing down from nozzle 1. When the tip of the glass fluid 2, that is, the cutting mark 3, flows downward from the opposing molding surfaces 5a, 6a, the pressing operation of the first mold member 5 and the second mold member 6 is started. In FIG. 8, T=0 means both mold members 5 and 6.
Indicates when the operation starts. The operation start timings of these mold members 5 and 6 may be the same for both, but the timing of the end of the pressing operation of the mold members 5 and 6 against the glass fluid 2
It is preferable that T ₂ be at the same time or within an error of ±0.05 s on both sides. If this error is large, only one of the mold members 5 and 6 collides with the glass fluid 2, causing lateral wobbling of the glass fluid 2, which is undesirable. Thereafter, as shown in FIG. 3, the mold members 5 and 6 keep pressing the molded part 21 of the glass fluid 2 for a predetermined period of time, and during this time, the mold members 5 and 6 press the molded part 21 on both surfaces of the molded part 21. Pressure transfer is performed using surfaces 5a and 6a.

The operation start time and cutting start time of the cutting blade 4 are as follows.
The glass fluid 2 by the cutting blade 4 may be at the same time as the operation start time T=0 of the mold members 5 and 6, respectively.
The cutting completion time _T4 must be at the same time as the mold members 5 and 6 hold the glass fluid 2, or _at least after the mold members 5 and 6 hold the glass fluid 2.

Thereafter, the cutting blade 4 is returned to its original state. Figure 8 shows the timing at which the cutting blade 4 starts returning.
T ₄ is indicated, and the return end time is indicated as T ₅ .
Preferably, the time required from the operation start time T=0 of the cutting blade 4 to the cutting end time _T2 is set to 0.3 to 0.4 seconds.

As shown in FIG. 5, the operation start timing T ₁ of the cutting ring 7 is determined at least when the cutting blade 4 finishes cutting the glass fluid 2 (T ₃ ) before the cutting ring 7 finishes cutting the outer periphery of the part to be formed 21 (T 3 ). T ₂ ). By doing this, the glass fluid 2 is already cut off by the cutting blade 4 when the cutting operation of the cutting ring 7 is finished, and the cut piece 22 cut by the cutting ring 7 is easily attached to the first mold member. 5 can be moved outside. Thus, the cutting ring 7
The molded part 2 is slid along the outer periphery of the mold member 6.
The outer periphery of the molded portion 21 is cut to form the outer periphery shape of the molded portion 21.

Thereafter, the cutting ring 7 maintains the state at the end of cutting (T ₃ ), cools the molded part 21 from the outer periphery due to the temperature difference while holding the outer periphery of the molded part 21, and cools the molded part 21 from the outer periphery. The viscosity increases in the vicinity and the shape becomes fixed. On the other hand, after being pressed by the mold members 5 and 6, the molded part 21 is cooled from both surfaces due to the temperature difference between the mold members and the molded part 21, increasing its viscosity and stabilizing the surface shape.

Next, as shown in FIG. 6, the first mold member 5
to return to its original state. This operation start time is T ₆
Assuming that the operation end time is _T7 , and the start time for returning the cutting ring 7 to its original state is at the same time as or after the return end time _T7 of the first mold member 5,
Before the cutting ring 7 starts operating, the part to be formed 21
is held by the cutting ring 7,
It will not fall naturally.

Then, at the same time as the return completion time _T8 of the cutting ring 7, the part to be molded, that is, the molded product 23 is taken out. This can be done using a known suction hand or the like. After this removal work is completed, the second mold member 6
to return to its original state. In FIG. 8, the return start time of the second mold member 6 is indicated as _T9 , and the return end time is indicated as _T10 .

Note that FIG. 7 shows the state in which the cutting ring 7 has been returned to its original position, and at this time the molded product 23 is removed from the cutting ring 7.
The hold is released and it falls naturally.

In the above-described operation, press molding by the molding dies 5 and 6 is performed on the tip of the glass fluid 2, that is, the portion excluding the cut marks 3, so the resulting molded product 23 has surface defects such as shear marks. does not occur.

Further, the cavity capacity formed by the molds 5 and 6 can be set by the stroke of each cylinder 13 and 16. That is, the set strokes of the cylinders 13, 16 determine the shortest approach width between the molding members 5, 6 during pressing, which regulates the distance between the molding surfaces of the molds 5, 6. Therefore, since the wall thickness of the molded product 23 is determined by this molding surface interval, by setting the strokes of the cylinders 13 and 16 according to the wall thickness of the molded product 23 to be manufactured, a predetermined thickness can always be achieved. A molded article having a thickness is obtained. Also, molded product 2
The surface shape and properties of the molded parts 3 are determined by the molded surfaces 5a and 6a of the molded members 5 and 6, respectively. Furthermore, the outer peripheral shape of the molded product 23 is determined by the inner peripheral shape of the cutting ring 7, and the outer periphery of the molded product 21 is formed simultaneously with the cutting operation of the cutting ring 7.

Note that the press molding apparatus described above uses a mold that performs pressing operations from the left and right directions in response to the nozzle through which the glass fluid, which is the molding material, flows downward. The type and mold are not limited; for example, molds configured for transversely or obliquely supplied glass fluid may also be used.

Next, a specific example using the press molding method as described above will be described with reference to FIGS. 1 to 8.

(Example 1) Optical glass usually used for camera lenses, etc.
Using SF8 (Tg=443℃, specific gravity 4.22), outer diameter 20
mm, center thickness 2.7mm, edge thickness 1.29mm, curvature R ₁ = 20
A preform for reheat press having a convex meniscus shape with mm, R ₂ =40 mm, glass capacity of 0.636 cc, and weight of 2.68 g was molded.

The mold members 5 and 6 are made of SUS420J, and their respective molding surfaces 5a and 6a are polished to optical mirror surfaces. The mold temperature of mold members 5 and 6 is 400℃ (Tg of SF8 = 443
Heater 30 so that the temperature is 43℃ lower than
Heat at 31. Further, the cutting ring 7 is also heated to 400° C. by heaters 34 and 35, similar to the mold temperature.

The strokes of the cylinders 13 and 16 are determined by the maximum approach width during the pressing operation of each mold member 5 and 6.
The thickness was adjusted to 2.7 mm to obtain the desired wall thickness.

First, glass was melted in a melting furnace (not shown) and the viscosity of the glass fluid 2 was adjusted to about 10 ^4.6 poise (815°±5°C), and the glass fluid 2 was flowed out from the nozzle 1. Next, as shown in FIG. 2 and FIG.
Cylinder 1 at the point when it flows downward from a and 6a
3 and 16 were activated, and at the same time, the cutting blade 4 was also activated. The operating pressures of these cylinders 13 and 16 are 120Kg and 300Kg, respectively, and the operating speeds of both cylinders are 120Kg and 300Kg, respectively.
It is set as 200mm/s.

Then, as shown in FIG. 3, after the pressing operation of the mold members 5 and 6 against the glass fluid 2 is started,
Activate the cutting ring 7. The cutting ring 7 is made of SK3, and a controller (not shown) controls each cylinder so that the time from the time when the pressing operation of the mold members 5 and 6 is completed until the cutting by the cutting ring 7 is completed is 0.2 seconds. 13,16,1
Adjust the operation timing of step 7. The operating pressure of the cylinder 17 that drives this cutting ring 7 is
The weight is 100Kg, and the operating speed is 200mm/s.
Further, as shown in FIG. 5, when the cutting operation by the cutting ring 7 is completed, the cutting of the glass flow 2 by the cutting blade 4 is also completed. Further, as shown in the same figure, the cutting operation of the cutting ring 7 causes the part to be formed to
At the same time as the outer peripheral shape of the molded portion 21 is formed, the molded portion 21 and the cut piece 22 are separated.

In FIG. 5, the first mold member 5 and the cutting ring 7 are in an engaged state, but the cutting condition was good even when the two were only in contact with each other.

Next, while applying pressure to the cylinders 13 and 16, the state shown in Fig. 5 is maintained for about 10 seconds until the temperature of the molded product 23 becomes approximately equal to the temperature of the mold members 5 and 6 (400°C), and then As shown in FIG. 6, only the cylinder 16 was operated and the first mold member 5 was separated from the molded product 23. At this time, molded product 23
remains held by the cutting ring 7 and does not fall off by itself. Next, the cylinder 17 is activated to pull back the cutting ring 7, and at the same time, the molded product 23 is taken out by a handling device (not shown), and the cylinder 13 is activated to return the first mold member 6 to its original position. Then, the cut piece 22 is removed by a cut piece removing device (not shown).

Thus, molded article 2 obtained in this example
3 is an outer diameter accuracy of ±0.005mm for the desired molded product.
The center wall thickness is within ±0.01mm and the weight is within ±0.02g (±0.7%), and there are no harmful surface defects such as shear marks, and sink marks are also consistent with the shape of each mold member 5 and 6. The maximum precision was within 10 μm, and it could be used not only as a preform for reheat press, but also as an optical lens that does not require much precision.

FIG. 9 is a graph showing temporal changes in the temperatures of the cutting ring 7, the first mold member 5, the second mold member 6, and the glass that is the material to be molded in this example. In addition, for this explanation, time T is shown in Fig. 8.
is used.

Initially (T=0 in Figure 8), first and second
The mold members 5 and 6 are formed at the glass transition point of the glass material.
The temperature was adjusted to 400°C, which is 43°C lower than the Tg (SF8 Tg = 443°C). The viscosity of the glass fluid 2 flowing from the nozzle 1 shown in Fig. 2 is approximately 10 ^4.6 poise (815°±5
°C).

During the molding period (approximately 10 seconds) from the pressing start time T ₂ of the mold members 5 and 6 to the pressing end time T ₆ , the glass in the molded part 21 is rapidly cooled due to the temperature difference between the mold members 5 and 6. , the viscosity ranges from 10 ^4.6 poise to 10 ^14.5 poise or more.

In this embodiment, the mold members 5, 6 and the cutting ring 7 are each heated with a heater so as to be maintained at 400° C. until the end of pressing. At this time, molded product 23
The glass temperature is approximately the same as that of the mold members 5 and 6.

Further, when molding was carried out with the cutting ring 7 at 350°C (the mold temperature was 400°C), the same results as above were obtained.

(Example 2) In this example, optical glass F8 (Tg=
Using molten glass at 445℃ and specific gravity 3.36), the outer diameter was 6 mm, the center wall thickness was 4 mm, the edge thickness was 3.08 mm, the curvature was R ₁ = R ₂ = 10 mm, and the glass capacity was obtained in the same manner as in Example 1.
A biconvex preform for reheat press with a size of 0.100 cc and a weight of 337 mg was molded.

In this example, as the mold members 5 and 6, Example 1 is used.
Use the same mold temperature as 375℃ (F8).
The heaters 30 and 31 were adjusted so that the temperature was 70°C lower than Tg445°C. The cutting ring 7 was similarly adjusted to 375°C±10°C using heaters 34 and 35.

Further, the viscosity of the glass fluid 2 is 10 ^2.95 to 10 ^3.1 poise (approximately 1080 poise).
℃~1050℃).

Then, the operating pressures of the cylinders 13, 16, and 17 were set to 50 kg, 200 kg, and 50 kg, respectively, and press molding and cutting were performed in the same manner as in Example 1, so that the internal viscosity of the molded product 23 was 10 ⁹ poise ( Approximately 540
When the molded product 23 was removed from the second mold member 6, the outer diameter accuracy was ±0.01 mm and the center wall thickness was ±0.01 mm relative to the desired molded product.
0.02, the weight variation was within ±3 mg (±0.9%), and the sink mark at the center of the surface was about 40 μm on average, and the surface condition was good and the precision was sufficient to be used as a reheat press preform. Ta.

(Example 3) In this example, a round bar made of optical glass SF8 similar to that in Example 1 was used, with an outer diameter of 20 mm and a center wall thickness of 3.
mm, edge thickness 1.6mm, curvature R ₁ = 32mm, glass capacity
A convex lens of 0.693 cc and weight of 2.92 g was molded in a non-oxidizing atmosphere.

The round bar made of SF8 has a diameter of 10mm±1mm.
After removing scratches and dust from the surface, it was heated in a heating furnace (not shown) to a viscosity of about 10 ⁵ poise (approximately 775°C).

The mold members 5 and 6 are made of tungsten carbide, and the molding surfaces 5a and 6a are optical mirror surfaces.
Heaters 30 and 31 were used to heat the mold to a temperature of 510° C. (corresponding to about 10 ⁹ poise in terms of glass viscosity). The cutting ring 7 was also made of tungsten carbide like the mold members 5 and 6, and the cutting ring 7 was heated to 400° C. using an external heater (not shown).

Further, in this example, since the molding was performed in a non-oxidizing atmosphere, the entire apparatus was covered with a cover and the atmosphere was replaced with argon gas.

Then, the operating pressures of the cylinders 13, 16, and 17 were set to 170 Kg, 350 Kg, and 150 Kg, respectively, and press forming and cutting were performed in the same manner as in Example 1. However, in this example, instead of the molten glass flow, a glass rod whose tip portion had been softened to the above-mentioned viscosity was used.

After press forming and cutting, each cylinder 1
3, 16, 17 are kept under pressure, the outputs of heaters 30, 31 and heaters 34, 35 for heating the cutting ring are gradually weakened, and mold members 5, 17 are heated.
The temperature of 6 and molded product 23 is 40℃ (approx.
After cooling the molded product 23 to a temperature of ^14.5 poise or higher), the molded product 23 is molded into the second mold member 6 in the same manner as in Example 1.
I took it out.

The obtained molded product has an outer diameter accuracy of ±0.005 mm, a center wall thickness of ±0.01 mm, and a weight accuracy of ±0.005 mm relative to the desired molded product.
The variation was within 0.025g (±0.85%), the surface condition was good, and there was almost no surface deformation due to sink marks, and the lens could be used as is without particularly high precision requirements.

(Example 4) In this example, optical glass SF8 (Tg=
Using molten glass at 443℃ and specific gravity 4.22), the outer diameter was 6 mm, the center wall thickness was 4 mm, the edge thickness was 3.08 mm, the curvature was R ₁ = R ₂ = 10 mm, and the glass capacity was obtained in the same manner as in Example 1.
A biconvex lens of 0.100 cc and weight of 422 mg was molded in a non-oxygen atmosphere.

In this example, as the mold members 5 and 6, Example 1 is used.
Using the same equipment as above, adjust the heaters 30 and 31 so that the mold temperature is 510°C (corresponding to about 10 ⁹ poise in terms of glass viscosity), and also adjust the cutting ring 7 to 510°C using heaters 34 and 35. It was adjusted.

Further, the glass was melted in a melting furnace (not shown) and the viscosity of the glass fluid 2 was adjusted to 10 ⁵ poise (approximately 775° C.).

Then, the operating pressures of the cylinders 13, 16, and 17 were set to 150 kg, 350 kg, and 100 kg, respectively, and press forming and cutting were performed in the same manner as in Example 1. Thereafter, while the molded product 23 is held in the mold members 5, 6 and the cutting ring 7, the heaters 30, 3
Gradually weaken the output of molds 1 and 34, molding molds 5 and 6,
After cooling the cutting ring 7 and the molded product 23 to 370°C (glass viscosity of 10 ^{to 14.5} poise or more),
Molded article 23 was taken out in the same manner as in Example 1. At this time, as shown in FIG. 10, the cutting ring was cooled while being adjusted so that the temperature was always 5 to 10 DEG C. higher than the temperature of the mold members 5 and 6. The obtained molded product has an outer diameter accuracy of ±0.005 mm with respect to the desired shape.
±0.02mm in center wall thickness, ±3mg in weight (±0.7%)
The surface condition is good, and the sink marks caused by shrinkage are concentrated in the center of the outer peripheral side of the lens because the cooling rate of the cutting ring is slightly faster than that of the mold, and the surface accuracy is also very good. As it was, it could be fully used as a normal lens.

(Effects of the Invention) As explained above, according to the present invention, the following effects occur.

(1) There are no surface defects such as shear marks on the surface of the molded product, and optical lenses with high dimensional and weight accuracy or optical elements such as reheat press preforms do not require any post-processing such as grinding or polishing after press molding. can be manufactured.

In addition, by setting the temperature of the mold to a predetermined temperature, it is possible to suppress the occurrence of sink marks and to obtain a molded product with high surface precision that suppresses the occurrence of fusion.

Furthermore, if cutting is performed at a low temperature without heating the cutting member, the outer periphery of the molded product will solidify first, causing the heat balance of the molded product itself to collapse and distortion to occur more often. Since the member is heated to a temperature corresponding to a predetermined glass viscosity and cut, the properties of the cut surface, that is, the outer circumferential side surface of the molded product are good.

(2) Since the glass fluid used for molding does not require much precision, the device for discharging molten glass etc. may be inexpensive and does not require high technology. Furthermore, since the melting furnace is flexible in response to changes in the flow rate and temperature of the outflowing glass due to fluctuations in the glass liquid level in the melting furnace, the melting furnace may also be inexpensive.

(3) In addition to molten glass, the glass material used for molding may be a glass rod or sheet, and the precision of these materials is not particularly required.

(4) Since the glass fluid is directly press-molded and cut, small and thin molded products, which were previously difficult to press-form, can be easily produced with high precision.

[Brief explanation of the drawing]

FIG. 1a is a schematic sectional view of a press molding apparatus showing an embodiment of the present invention. FIG. 1b is an enlarged sectional view of a main part of the apparatus shown in FIG. 1a, with a heating device added thereto. 2 to 7 are sectional views of essential parts of the apparatus shown in FIG. 1, showing the operating state of the apparatus in the order of steps. FIG. 8 is a diagram showing a timing chart of each operating section of the press molding apparatus shown in FIG. 1. FIG. 9 is a graph showing temporal changes in temperature of the mold member and glass during press molding in the first example. FIG. 10 is a graph showing temporal changes in temperature of the mold member and glass during press molding in the fourth example. DESCRIPTION OF SYMBOLS 1... Nozzle, 2... Glass fluid, 3... Cutting trace, 4... Cutting blade, 5... First mold member, 6...
Second mold member, 7... Cutting ring, 21... Molded part, 22... Cut piece, 23... Molded product, 30...
...Heater for heating the first mold member, 31...Second
heater for heating the mold member, 34, 35... heater for heating the cutting ring, 40... controller.

Claims (1)

[Claims] a pair of molds that are arranged opposite to each other so as to sandwich a glass fluid having a temperature corresponding to a viscosity of 1 10 ³ to 10 ⁵ poise, and press the glass fluid to form a molded part; a cutting member provided on the outer periphery for cutting ^and separating the part to be molded from other parts; a means for driving the mold and the cutting member; The temperature of the cutting member is set within a range of 100°C lower than the glass transition point, and the temperature of the cutting member is set within ± the temperature of the mold when pressing the glass fluid.
An optical element molding device characterized by having a controller that sets the temperature within a range of 50°C.