JPH0445454B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing optical elements 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 that do not require 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 forming quality, and for this reason, in any of the above methods, the weight of the glass material supplied to the press forming to obtain the final product must be sufficiently 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.

The molding method described in Japanese Patent Publication No. 41-9190 is a method of press-forming 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 accuracy 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 generally proposed a method for manufacturing an optical element in which the molded product is free from surface defects such as shear marks and has excellent dimensional and weight accuracy.

The present invention relates to this manufacturing method, and in particular proposes a method for manufacturing an optical element in which a glass fluid continuously flowing down from an outflow nozzle of a melting furnace is supplied in good condition during press molding.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the optical element manufacturing method of the present invention includes a pair of left and right molding molds sandwiching a glass fluid flowing down from an outflow nozzle of a glass melting furnace. After forming a molded part by pressing the glass fluid with the mold, a cutting member provided on the outer periphery of the mold is operated to separate the molded part and other parts. The method is characterized in that the glass fluid is cut and separated near the outflow position of the nozzle.

(Function) In the method for manufacturing an optical element configured as described above, when left and right mold members constituting a pair of molding molds are used as a first mold member and a second mold member, these mold members are melted. They can be arranged to be substantially perpendicularly opposed to each other with the glass fluid flowing down from the furnace outlet nozzle. That is, it is possible to adopt a structure in which each mold member is pressed against each other from a direction substantially perpendicular to the flow direction of the glass fluid, and 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, the cutting trace.

The wall thickness of the part to be molded is determined by setting the cavity of the mold in advance. This cavity is
The distance between the molding surfaces of the opposing mold members during press molding can be set by making it correspond to the distance between the functional surfaces of the desired optical element.

When a sufficient volume of glass fluid is supplied between each mold member during press molding, the excess glass generated when each mold member is pressed freely flows out of the molding surface, and the wall thickness of the molded product is adjusted to the above-mentioned molding level. Determined by mold cavity.

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 operating a cutting member provided on the outer periphery of the mold. The shape of the outer peripheral side surface of the molded part is formed.

Furthermore, by cutting the glass fluid that flows continuously from the melting furnace in the vicinity of the nozzle outflow position along with this cutting operation on the part to be formed, the glass capacity required for the next press forming can be improved. Supplied.

This point will be further explained with reference to FIG. FIG. 10 is a diagram showing the flow of glass fluid flowing out from the nozzle.

FIG. 10A shows an ideal flow situation of the glass fluid 2 flowing out from the nozzle 1. In press molding, when forming a molded part (indicated by 21 in Figure B) by pressing each mold member against the thickened part of the glass fluid as shown in Figure A, The glass capacity required for the press molding will be ensured.

Then, during this press molding, as shown in FIG. 10B, if the glass fluid 2 is cut near the outflow position of the nozzle 1, a glass fluid with a thick tip as shown in FIG. 10A can be obtained again.

However, if the glass fluid 2 is not cut near the outflow position of the nozzle 1 after press forming as described above, as shown in FIG. The glass flows down from the vicinity of the outflow position in a thin stream, making it impossible to obtain the glass capacity necessary for press forming.

In addition, when it becomes a tapered glass fluid as described above, it is easily affected by thermal changes, and the shrinkage layer that occurs when it is cooled by the outside air becomes uneven.
Molded products are more likely to have sink marks.

The present invention eliminates the above-mentioned disadvantages by cutting the glass fluid near the outflow position of the nozzle before the glass fluid stretches under its own weight, thereby obtaining a glass fluid with a thick tip as shown in FIG. 10A. are doing.

The molded product thus obtained is formed from a portion that does not contain cut marks of the glass fluid, so there are no surface defects such as shear marks, and the outer periphery of the molded part is formed by the set cavity and cutting member. By performing press molding on the glass fluid supplied in good condition, a molded product whose capacity and weight can be adjusted with high precision 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 high-precision functionality can be obtained.

Note that the viscosity of the glass fluid in the present invention is 10
~ ¹⁰⁷ pores are 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. Furthermore, the viscosity of these glass fluids is
10 ³ to ^{10 5} poise is optimal.

In addition, the temperature of the mold for molding varies from the temperature equivalent to ¹⁰⁸ Boas 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 in the cutting member.

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 if 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 if it is used as is for optical lenses etc. If it is cooled in a mold with pressure applied and taken out when it reaches a viscosity of about 10 ^{to 14.5} poise, it can be used as an optical element with good shape 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.

A cutting blade 4 is provided near the bottom of 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 includes a first mold member and a second mold member constituting a pair of molds. 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 an independent motion.

Furthermore, heaters 8 and 9 are installed inside each mold member 5 and 6.
is set up. 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.

FIGS. 2 to 7 are sectional views of essential parts showing the operating state of the apparatus in each process order. FIG. 8 is a timing chart showing the operation timings of the operating parts of this device, that is, the first mold member 5, the second mold member 6, the cutting blade 4, and the cutting ring 7, and the horizontal axis represents time T. show. 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. 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 (T ₂ to T ₆ ), and during this period, the molded part 21 remains pressed.
Pressure transfer is performed on both surfaces by the respective molding surfaces 5a and 6a.

The operation start time of the cutting blade 4 may be the same as the operation start time T=0 of the mold members 5, 6, but the end time T2 of cutting the glass fluid 2 by the cutting blade 4 is the same as the operation start time T ₌₀ of the mold members 5, 6. This must be at the same time as or at least after holding the glass fluid 2. Thereafter, the cutting blade 4 is returned to its original state. In FIG. 8, the return start time of the cutting blade 4 is shown as _T4 , and the return end time is shown as _T5 . 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.
During this time, the glass fluid 2 cut by the cutting blade 4 near the outflow position of the nozzle 1 as described above is transferred to the second
The glass fluid 2 with a thicker tip as shown in the figure continues to flow out and is supplied to the next press molding.

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, 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 easily attached to the first mold member. 5 can be moved outward. In this way, the cutting ring 7 cuts the outer periphery of the part to be formed 21 while sliding along the outer periphery of the second mold member 6, and forms the shape of the outer peripheral side surface of the part to be formed 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 by the temperature difference while maintaining the outer peripheral side surface of the molded part 21, and cools the molded part 21 from the outer periphery. The viscosity increases near the outer periphery and the shape is fixed. On the other hand, after being pressed by the mold members 5 and 6, the mold members and the molded part 2
Due to the temperature difference of 1, the molded part 21 is cooled from both surfaces, increasing its viscosity and stabilizing its surface shape.

Next, first, as shown in FIG. 6, the first mold member 5 is returned to its original state. Let T ₆ be the start time of this operation, T ₇ be the end time of the operation, and let the start time of the operation of the cutting ring 7 to return to its original state be at the same time as or after the return end time T ₇ of the first mold member 5. Before the cutting ring 7 starts operating, the part 21 to be formed is held by the cutting ring 7, and does not fall off 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 . Regarding the return operation of the second mold member 6, considering that the glass fluid 2 cut by the cutting blade 4 continues to flow out as described above, this glass fluid 2 is returned to the second mold member 6. It is necessary to take the timing to start the return of the second mold member 6 before contact is made.

Note that if the cutting ring 7 is returned to its original state before taking out the molded product 23, the molded product 23 will be released from the hold of the cutting ring 7 and will fall naturally, as shown in FIG.

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

Furthermore, since the flowing glass fluid 2 is supplied to the part where the molded part 21 is formed, it becomes thicker at the beginning.
Sufficient glass capacity is ensured for press molding, and non-uniform shrinkage layers are less likely to occur due to cooling, which occurs with tapered glass fluids.

The cavity formed by the molds 5 and 6 can be set by the stroke of each cylinder 13 and 16. That is, the distance between the molding surfaces of the molding dies 5 and 6 at the pressing end time _T2 is determined by the set strokes of the cylinders 13 and 16. Since the wall thickness of the molded product 23 is determined by the distance between the molded surfaces, the cylinder 13,
By setting the 16 strokes according to the thickness of the molded product 23 to be manufactured, a molded product always having a predetermined thickness can be obtained. The surface shape and properties of the molded product 23 are determined by the molding surface 5 of each molded member 5, 6.
Determined from a and 6a. 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.

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 normally 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 molded from 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 glass fluid 2 was adjusted to have a viscosity of about 10 ^4.6 poise (815°±5°C), and then 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 20mm/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,
Adjust the operation timing of 17. 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 fluid 2 by the cutting blade 4 is also completed. Further, as shown in the figure, the cutting operation of the cutting ring 7 forms the outer peripheral shape of the part to be formed 21 and at the same time separates the part to be formed 21 and the cut piece 22.

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 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 molded part. 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 (Tg of SF8 = 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).

The molding period from T ₂ when the pressing operation of the mold members 5 and 6 ends to T ₆ when the return operation starts (approximately 10 seconds)
In, the glass of the molded part 21 is molded into the mold member 5,
It is rapidly cooled due to a temperature difference of 6 degrees, and the viscosity increases from 10 ^4.6 poise to more than 10 ^14.5 poise. In this embodiment, 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 is approximately the same as that of the mold members 5 and 6. It becomes warm.

Example 2 In this example, optical glass F8 (Tg
= 445℃, specific gravity 3.36) using the same method as in Example 1 to obtain an outer diameter of 6 mm, center wall thickness of 4 mm, edge thickness of 3.08 mm, curvature of R ₁ = R ₂ = 10 mm, and glass capacity.
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 viscosity of the glass fluid 2 is 10 ^2.95 to 10 ^3.1 poise (1080°C to
The temperature was adjusted to 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.

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

(1) Since the fluidized glass fluid is supplied with a tapered tip to the part where the molded part is formed, sufficient glass capacity is secured for press molding, and it is difficult to cool the glass fluid as seen in tapered glass fluids. The concomitant non-uniformity of the shrinkage layer does not occur.

(2) 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 preforms for reheat press, do not require any grinding after press molding or post-processing after polishing. can be manufactured. especially,
An optical element with high capacity accuracy can be obtained by forming the functional surface during press molding and subsequently forming the outer peripheral side surface by cutting.

(3) Since the precision of the glass fluid used for molding is not required, a 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.

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

[Brief explanation of drawings]

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. FIG. 10 is a diagram showing the flow of glass fluid flowing out from the nozzle. 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.

Claims (1)

[Scope of Claims] 1. A pair of left and right molding molds are arranged opposite to each other with a glass fluid flowing down from an outflow nozzle of a glass melting furnace sandwiched therebetween, and a molded part is formed by pressing the glass fluid with the molding molds. After that, a cutting member provided on the outer periphery of the mold is operated to cut and separate the molded part from other parts and cut the glass fluid near the outflow position of the nozzle. Method of manufacturing elements. 2. Manufacturing the optical element according to claim 1, wherein the glass fluid is cut at the same time as or before the cutting and separation of the molded part and other parts by the cutting member. Method. 3. The method of manufacturing an optical element according to claim 1, wherein the glass fluid has a viscosity of 10 to 10 ⁷ poise. 4 The glass fluid was heated at a temperature corresponding to 10 ⁸ poise in glass viscosity and at a glass transition point (approximately
10. The method for manufacturing an optical element according to claim 1, characterized in that pressure molding is carried out in a mold at a temperature 100° C. lower than 10 ¹³ poise.