JPH0471853B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing an optical element by press molding, and more specifically, to improve surface accuracy without undergoing processes such as grinding and polishing after press molding. The present invention also relates to a method for manufacturing 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 without requiring post-processing such as grinding and polishing.

This press molding method generally includes a reheat 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 extruded 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 surface precision 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.

The present invention was made based on the above circumstances, and
Provides a method for manufacturing optical elements by press molding that does not require any processes such as grinding and polishing after press molding, has no surface defects such as shear marks, and has good dimensional accuracy such as wall thickness and weight accuracy. The purpose is to

(Means for Solving the Problems) In order to solve the above problems, in the present invention, a pair of molds are arranged facing each other so as to sandwich the glass fluid therebetween, and the cavities of the molds are set,
In the method for manufacturing an optical element, the glass fluid is pressed against each other by the mold to form a molded part, wherein the glass fluid has a viscosity of 10 to 10 ⁷ poise, and the temperature of the mold is controlled by the glass viscosity. The temperature is set within the range of ¹⁰⁸ poise and 100°C lower than the glass transition point, and a mold set at the temperature is pressed against the glass at the temperature to hold the mold in a predetermined position. After stopping, the molded part and other parts are cut and separated by a cutting member provided on the outer periphery of the mold.

(Function) In the method for manufacturing an optical element configured as described above, if each mold member constituting a pair of molding 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 an already molded glass fluid, in addition to the above-mentioned arrangement, the first mold member and the second mold member may each be It is also possible to arrange them so as 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 molded is determined by the preset cavity of the mold. This cavity can be set by the distance between the molding surfaces of the opposing mold members when they are closest to each other.

Excess glass generated when pressing each mold member freely flows out of the molding surface, and the thickness of the molded product is determined by the cavity of the mold without being affected by the size of the glass flow.

After pressing the glass fluid with each mold member to form a molded part, the molded part and other surplus parts are cut and separated by a cutting member provided on the outer periphery of the mold, and the outer periphery of the molded part is A shape is formed. The thus obtained molded product 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 part to be molded using the preset 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.

Note that the viscosity of the glass fluid in the present invention is 10
~ ¹⁰⁷ poise is preferred. When the glass viscosity is lower than 10 poise, the glass flow becomes filamentous and the required glass volume within the mold cavity 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. The optimum viscosity of these glass fluids is 10 ³ to 10 ⁵ poise.

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. The optimum viscosity of these glass fluids is 10 ³ to 10 ⁵ poise.

In addition, the temperature of the molding die ranges from the temperature equivalent to 10 ⁸ poise in terms of glass viscosity to the glass transition point (hereinafter referred to as Tg).
It is called. Equivalent to glass viscosity of approximately 10 ¹³ . ) It is necessary to set the temperature within the range of 100℃ lower than (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. Moreover, the glass and the molding surface of the mold tend to be fused together, which is undesirable. 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.

The temperature of the cutting member is preferably equal to the mold temperature of the mold, so that the influence of temperature changes on the glass is similar to that of the mold.

Furthermore, the viscosity of the molded product when taken out is such that when the molded product is used as a preform for reheat press, it can be used if it is cooled to a viscosity of 10 ⁸ poise or higher, but when used as is for optical lenses etc. If it is cooled in a mold while applying pressure and taken out when it becomes clay of about 10 ^{to 14.5} poise, it can be used as an optical element with good shape accuracy and surface accuracy.

Note that the press molding and subsequent cutting treatment in the present invention are preferably performed in a non-oxidizing atmosphere in order to maintain the life of the mold and cutting member.

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

FIG. 1 is a schematic sectional view of a press molding apparatus used in an embodiment of the present invention.

In FIG. 1, 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. Reference numeral 4 denotes a cutting blade that is provided below the nozzle 1 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 therefore a first mold member 5 forming a pair of molding molds and The second mold member 6 is disposed facing each other so as to narrow the glass fluid 2 from a substantially right angle direction. Each mold member 5, 6
has molded surfaces 5a and 6a which are mirror-finished on their opposing surfaces.

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. .

Furthermore, heaters 8 and 9 are installed inside each mold member 5 and 6.
is provided. 10 and 11 are conducting wires connected to the respective heaters. Reference numeral 19 is the base of the entire apparatus, which firmly supports the cylinders 13, 16, 17 and the slide shaft 18.

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 on both sides, 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. T ₂ indicates the start time of the pressing operation of the mold members 5 and 6 against the glass fluid 2. Then, 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 operation start time T=0 and the pressing start time T2 of the mold members 5 and 6 may be the same, but the time _T4 when the cutting blade ₄ completes cutting the glass fluid 2 means that the mold members 5 and 6 are not in contact with the glass fluid. 2 must be held sufficiently. Preferably, the time required from the operation start time T=0 of the cutting blade 4 to the cutting completion time _T4 is set to 0.3 to 0.4 seconds. Thereafter, the cutting blade 4 is returned to its original state. In FIG. 8, the timing at which the return of the cutting blade is completed is indicated as T5.

The operation start timing T ₁ (Fig. 4) of the cutting ring 7 is as follows:
The cutting start time T ₂ of the cutting blade 4 may be set earlier than T 2 , but as shown in FIG. It is desirable that it be in a completed state. By doing this, when the cutting operation of the cutting ring 7 is completed, the glass fluid 2 is already cut off by the cutting blade 4, and the cut piece 22 cut by the cutting ring 7 is
can be easily moved to the outside of the first mold member 5. In this way, the cutting ring 7 cuts the outer periphery of the molded part 21 while sliding along the outer periphery of the second mold member 6, thereby forming the outer peripheral shape of the molded part 21. After that, the cutting ring 7 maintains the state at the end of cutting, and cools the molded part 21 from the outer periphery by the temperature difference while holding the outer periphery of the molded part 21, and the viscosity near the outer periphery of the molded part 21 decreases. It gradually increases 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, gradually increasing its viscosity and stabilizing the surface shape.

Next, after maintaining this state for a predetermined period of time, first,
As shown in FIG. 6, the first mold member 5 is returned to its original state. Assuming that the operation start time is _T6 and the operation end time is _T7 , at this time the part to be formed 21 is held by the cutting ring 7 and will not fall off naturally.

The cutting ring 7 starts operating to its original state at the same time as or after the return completion time T ₇ of the first mold member 5, and at the same time as the return completion time T ₈ of the cutting ring 7, the part to be formed, that is, the molded part Take out item 23. This can be done using a known suction hand or the like. After this removal operation is completed, the second mold member 6 is returned 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
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
Heaters 8 and 9 so that the temperature is 43℃ lower than ℃
Heat it up. Further, the strokes of the cylinders 13 and 16 are adjusted so that the maximum width of approach during the pressing operation of each of the mold members 5 and 6 is 2.7 mm, so that the desired wall thickness can be obtained.

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 100
Kg, and the operating speed is 200 mm/s. or,
As shown in FIG. 5, when the cutting operation by the cutting ring 7 is completed, the cutting of the glass stream 2 by the cutting blade 4 is also completed. Furthermore, as shown in the same figure,
Due to the cutting operation of the cutting ring 7, the outer peripheral shape of the part to be formed 21 is formed, and at the same time, the part to be formed 21 is
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 the outer diameter accuracy of ±0.0005 for the desired molded product.
mm, center wall thickness ±0.01mm, weight 0.02g (±0.7%)
There are no harmful surface defects such as shear marks, and sink marks are within a maximum of 10 μm relative to the shape of each mold member 5 and 6, making it suitable for use as a reheat press preform. Rather, it could be used satisfactorily as an optical lens that did not require much precision.

FIG. 9 shows the first mold member 5 in this embodiment,
It is a graph showing temporal changes in the temperature of the second mold member 6 and the glass that is the material to be molded. Incidentally, in this explanation, the time T 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 higher. In this example,
The mold members 5 and 6 are heated by heaters 8 and 9, respectively, so as to be maintained at 400° C. until the end of pressing, and at this time the glass temperature of the molded product 23 becomes approximately the same temperature as the mold members 5 and 6.

(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 8 and 9 were adjusted so that the temperature was 70°C lower than Tg445°C.

Further, the glass fluid 2 melted in a melting furnace (not shown) has a viscosity of 10 ^2.95 to 10 ^3.1 poise (1080°C).
~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 0.693 cc, 2.92 g hand-shaped lens 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 8 and 9 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, and 17, while keeping the pressure applied, gradually weaken the output of heaters 8, 9, and an external heater for heating the cutting ring, and mold members 5, 6 and molded product 2.
After the molded product 23 was cooled to 400° C. (glass viscosity of about 10 ^14.5 poise or more), the molded product 23 was taken out from the second mold member 6 in the same manner as in Example 1. The obtained molded product has an outer diameter accuracy of ±0.005 mm, a center wall thickness of ±0.01 mm, and a weight variation of ±0.025 g (±0.85%) relative to the desired molded product.
The surface condition was good, with almost no surface deformation due to sink marks, and the lens could be used as is as a lens that did not require particularly high precision.

(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.

(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. or,
The melting furnace may also be inexpensive because it 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.

(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. 1 is a schematic sectional view of a press molding apparatus showing an embodiment of the present invention. 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. DESCRIPTION OF SYMBOLS 1... Nozzle, 2... Glass flow, 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.

Claims (1)

[Claims] 1. A pair of molding molds are arranged facing each other so as to sandwich a glass fluid therebetween, and a cavity of the molding molds is set, and the glass fluid is pressed against each other by the molding molds to form a molded part. In the manufacturing method, the glass fluid has a viscosity of 10 to 10 ⁷ poise, and the temperature of the mold is determined by the glass viscosity.
100 from the temperature equivalent to ⁸ poise and the glass transition point
℃, and after pressing the glass at the temperature with a mold set at the temperature and stopping the mold at a predetermined position, a cut is made on the outer periphery of the mold. A method of manufacturing an optical element, characterized in that the part to be molded and other parts are cut and separated by a member.