JPH01133948A - Manufacture of optical element - Google Patents

Abstract

PURPOSE:To obtain an optical element which is free from a surface flow and excellent in dimensional accuracy with good productivity by pressing glass melt with a pair of molding dies to mold it and thereafter cutting it with a cutting member provided on the outer periphery of the dies and separating the molded body from the other part. CONSTITUTION:A pair of molding dies 5, 6 are oppositely arranged so that glass melt 2 made flowed out through the nozzle 1 of a melting kiln is pinched from the orthogonal direction and a cavity is formed by respective molding faces 5a and 6a. This glass melt 2 made flowed out through the nozzle 1 is pressed with molding dies 5, 6 to form a part 21 to be molded and also the state being left to press it is held in a prescribed time and press-transcription due to the molding faces 5a, 6a is performed for both faces of the part 21 to be molted. Then cutting blades 4 provided on the outer periphery of the dies 5, 6 and a cutting ring 7 are successively actuated to cut the part 21 to be molded and this part 21 is separated from the other part and thereby an optical element is obtained.

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 producing an optical element with good weight accuracy or a preform suitable for reheat pressing thereof.

(Prior art) In recent years, a method of molding high-precision optical elements that eliminates the need for post-processing such as grinding and polishing has been developed by housing a glass material in a mold with a predetermined surface accuracy and press-molding it. is being developed.

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 by sanding, etc., to form glass pellets, and this is 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 charged into a chute, and then molded. This is a method of molding an optical element by pressing a mold.

In addition, in the above-mentioned reheat press method, the molten glass is put into a mold and press-molded, as in the direct press method described above, without going through low-productivity steps such as cutting and sanding, and the final product is produced. A preformed product with a shape similar to (
There is a method in which after obtaining a preform (1), the preform is placed in a mold having an optically functional surface with the same or higher precision than the shape and surface precision of the final product, and press molding is performed.

(Problems that 1994 Ming tries to solve) Optical elements obtained by these molding methods.

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 molding using small glass lumps, the IT adjustment of the glass small lumps is performed by cutting, sanding, etc., so that grains may remain on the surface of the molded product.
When heating a small glass lump before press molding, 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. There is a problem with doing so.

In addition, in the method of press forming directly using molten glass,
When cutting with a cutting blade, cutting marks called shear marks are generated on the molded product, which causes a problem in that the surface precision of the molded product deteriorates. In addition, in this press molding method, the weight of the molded product is adjusted by cutting the molten glass flow, so weight fluctuations occur in the molded product due to temperature changes in the molten glass flow, cutting timing, pulsation of the glass flow, etc. There is also the problem that dimensional accuracy cannot be obtained.

In addition, as a press molding method that particularly prevents the occurrence of shear marks for 1 hour, there is a method described in Japanese Patent Publication No. 41-9190-1 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 compressed, a phenomenon occurs in which excess glass in the mold cavity flows out from between the mold and the anvil facing it. As the suppression action of the mold progresses, this excess glass increases its outflow resistance and is cooled by the mold, increasing its viscosity, and is completely cut off between the mold and the opposing anobile. 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. Also, due to variations in the size of the molten glass flow, the thickness of the glass between the molded product and the protruding portion as described changes, resulting in variations in the thickness of the molded product. There is also the problem that the t31 adjustment cannot be performed with high precision.

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 high precision dimensions are required. A shaped rod or glass sheet is required.

The present invention was made in view of the above-mentioned circumstances, and does not require any steps such as grinding and polishing after press molding.
Moreover, it is an object of the present invention to provide an optical element that is free from surface defects such as shear marks and has good dimensional accuracy and weight accuracy, and a press molding method that allows for highly accurate weight adjustment as a preform for press molding of this optical element. .

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, a method for manufacturing an optical element according to the present invention includes disposing a pair of molds facing each other so as to narrow the glass fluid, and After setting a mold cavity and pressing the glass fluid against each other with the molding mold to form a molded part, the molded part and other parts are separated by a cutting member provided on the outer periphery of the molding mold. It is characterized by cutting and separating.

(Function) In the method for manufacturing an optical element configured as described above, each mold member constituting the pair of molding molds used is
and a second mold member, the respective molding surfaces of these mold members are arranged so as to face each other via the glass fluid. 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, in the case where the glass fluid is in the form of a rod or sheet that has fluidity by reheating an already molded product, in addition to the arrangement described above, 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, if the mold according to the present invention is configured for, for example, a flowing molten glass fluid, each mold member will be pressed against each other from a direction substantially perpendicular to the direction of flow of the glass fluid, and By adjusting the timing of pressing each mold member against the glass fluid,
The molded part can be formed 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 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. As mentioned above, 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 part to be molded is cut by the preset cavity and cutting member. By forming the outer periphery, a molded product with high shape accuracy and weight accuracy can be obtained. In addition, since the tiat@ 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 the surface texture of the desired molded product. By finishing the material 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 lO~10
'Poise is preferred. When the glass viscosity is lower than 10 poise, the glass flow becomes filamentous and the required glass capacity within the mold cavity becomes insufficient. It becomes difficult to cut the glass later. Note that the optimum viscosity of these glass fluids is 103 to 105 poise.

Also, as the softened glass fluid in the present invention.

As mentioned above, in addition to molten glass, glass fluids obtained by reheating preformed glass rods or sheets may also be used.The optimum viscosity of these glass fluids is 103 to 105 poise. .

In addition, the temperature of the molding die ranges from a temperature corresponding to 1 OLI poise in terms of glass viscosity to 100° below the glass transition point (hereinafter referred to as tg, which corresponds to approximately 1013 in terms of glass viscosity).
It is necessary to set the temperature within the range of 100°C (Tg - 100°C). If the mold temperature exceeds a temperature corresponding to 108 poise, the hardness of the glass surface in the molded part after press molding 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. In addition, the molding surfaces of the glass and the mold tend to be fused, which is undesirable.
When cutting the outer periphery of the part to be formed.

Not only will it be difficult to cut, but there is a risk that cracks will occur at the cut portion.

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 IPi when taking out the molded product is 1 when the molded product is used as a preform for reheat press.
It can be used sufficiently if it is cooled to a viscosity of 0.8 poise or higher, but if it is used as is for optical lenses etc., it must be cooled in a mold with pressure applied until it reaches a viscosity of about 5 poise. If taken out, it can be used as an optical element with good shape accuracy and surface accuracy.

"In addition, in order to maintain the life of the mold and 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. 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. 4 is provided below the nozzle l, and the glass fluid 2 is opened and closed by a drive device (not shown).
It is a cutting blade that cuts. When the cutting blade 4 operates and the glass fluid 2 is cut midway, a cutting mark 3 is generated.

The press molding apparatus shown in this embodiment is configured for a type in which the glass fluid 2 flows down from a /l, and therefore the first mold member 5 constituting a pair of molds is
and the second mold member 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 molding surfaces 5a, 6a which are mirror-finished on opposing surfaces.

The first mold member 5 is held by a slider 14, which is slidably supported on a slide shaft 18. 16 is a cylinder that drives the slider 14, and the operation of this cylinder 16 causes the slider 1 to move.
4 moves in the sliding direction of the slide shaft 18, and the first mold member 5 is suppressed.

On the other hand, the second mold member 6 is connected to a cylinder 13 via an adapter 12, and the operation of the cylinder 13 causes the second mold member 6 to be suppressed.

The cavity formed by each molding surface 5a, 6a of these mold parts 5.6 can be set by the stroke of each cylinder 13.16.

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 slidable on the slide shirt 18. It is connected to a supported slider 15. Further, the slider 15 is connected to a cylinder 17, and this cylinder 1
7 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 provided inside each mold member 5.6. to and ii are conducting wires connected to each heater. 19 is the base of the entire device, which firmly supports the cylinders 13, 16, 17 and the slide shaft 18.

Next, the operation of this device will be explained using factors 2 to 7 and FIG. 8.

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 operating parts can be controlled by a controller (not shown) connected to each operating part. can.

FIG. 2 shows the press molding in a straight bent state, and the glass fluid 2 is flowing down from the nozzle l. At the point when the tip of the glass fluid 2, that is, the cutting mark 3 flows downward from each opposing molding surface 5a, 6a, the first mold member 5 and the second mold member 6
Starts the pressing operation. In No. 8!4, T=0 indicates the start time of the operation of both mold members 5 and 6.
, 6 may be started at the same time on both sides, but the timing at which the suppression operation of the mold member 5.6 for the glass fluid 2 ends is T2.
It is preferable that T7 be the same or within an error of ±0.055 at most on both sides. T7 is the glass fluid 2 of the mold member 5.6
It indicates the start time of the suppressing operation for the mold member 5.
6 is a molded part 2 of the glass fluid 2, as shown in FIG.
1 is kept pressed for a predetermined period of time, and during this time, pressure transfer is performed on both surfaces of the molded portion 21 by the respective molding surfaces 5a and 6a.

When does the cutting blade 4 start operating and when does it start cutting?

The operation start time T=O and the pressing start time T2 of the mold members 5 and 6 may be the same, respectively, but the time T4 when the cutting blade 4 finishes cutting the glass fluid 2 is the same as the time when the mold members 5 and 6 cut the glass fluid 2. It must be released after being held sufficiently, preferably from the operation start time T=O of the cutting blade 4 to the cutting start time T4.
The time required for this is 0.3 to 0.4 seconds. after that,
The cutting blade 4 is returned to its original state yE. In FIG. 8, the return completion time of the νJ cutting blade is indicated as T5.

The operation start time T+ (FIG. 4) of the cutting ring 7 may be earlier than the cutting start time T2 of the cutting blade 4, but
As shown in FIG. 5, it is desirable that cutting of the glass fluid 2 by the cutting blade 4 is completed at least before the cutting edge 7 finishes cutting the outer periphery of the part 21 to be formed. When the cutting operation of the cutting ring 7 is completed T, the glass fluid 2 has already been cut off by the cutting blade 4, and the cut piece 2 cut by the cutting ring 7 is
2 can be easily moved to the outside of the first mold member 5. Thus, the cutting ring 7 extends M! along the outer circumference of the second mold member 6. The outer periphery of the part 21 to be formed is cut while moving in the same direction, thereby forming the shape of the outer periphery of the part 21 to be formed. Thereafter, 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 is reduced. It gradually increases and its shape becomes established. On the other hand, after being suppressed by the mold member 5.6, the molded part 21 is cooled from both surfaces due to the temperature difference between the molded member and the molded part 21, gradually increasing its viscosity and stabilizing its surface shape.

Next, after maintaining this state for a predetermined 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 end time TI of the first mold member 5, and at the same time as the return end time T8 of the cutting ring 7, the part to be formed, that is, the molded product 23 This can be done using a well-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 shown as T9, and the return end time is shown as TIO.

Note that FIG. 7 shows a state in which the cutting ring 7 is returned to its original position, and at this time the molded product 23 is released from the holding of the cutting ring 7 and falls naturally.

In the above-described operation, press molding by the molding die 5.6 is performed on the tip of the glass fluid 2, that is, the part excluding the cut marks 3, so that the resulting molded product 23 has surface marks such as shear marks. No defects occur.

Furthermore, the volume of the cavity formed by the mold 5.6 can be set by the stroke of each cylinder 13.16. i.e. set cylinder 13.16
By the stroke of each molded member 5,
The shortest approach width between the molds 6 and 6 is determined, and this regulates the distance between each molding surface of the mold 5.6. Therefore, since the wall thickness of the molded product 23 is determined by this molding surface interval, by setting the stroke of the cylinder 13, 16 according to the wall thickness of the molded product 23 to be manufactured, a predetermined wall thickness can always be achieved. A molded article having the following properties is obtained. Further, the surface shape and properties of the molded article 23 are determined by the respective molded portions 5a, 6a of each molded member 5.6. moreover.

The outer peripheral shape of the molded product 23 is determined by the inner peripheral shape of the cutting ring 7, and the molded product 23 is cut simultaneously with the cutting operation of the cutting ring 7.
The outer periphery of is formed.

Note that the press molding apparatus described above uses a mold that performs pressing operations from the left and right directions in response to a nozzle through which glass fluid, which is a 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 SF8 (
Tg=443℃, specific gravity 4.22), outer diameter 20+
am, center wall thickness 2.7cm, edge thickness 1.29m layer, curvature R
+ =20+*, R2=40mm, glass capacity 0, [
A 138 cc, 2.68 g convex meniscus preform for reheat press was molded.

The mold members 5 and 6 are made of 5US420J, and the respective molding surfaces 5a and 6a are polished to optical mirror surfaces. This mold member 5
．． Mold temperature of 6 is 400℃ (Tg of SF8 is 443℃)
Heat with heaters 8 and 9 so that the temperature is 3°C lower.

Further, the stroke of the cylinder 13.16 is adjusted so that the maximum width of approach during the pressing operation of each mold member 5.6 is 2.7 cm, so that the desired wall thickness can be obtained.

First, glass melted in a melting furnace (not shown) is heated to a glass fluid 2.
The viscosity was adjusted to about 1046 boads (815°±5°C), and the mixture was discharged from nozzle l. Next, as shown in FIGS. 2 and 3, there is a cut mark 3 at the tip of the glass fluid 2.
When the molding surfaces 5a and 6a of the mold members 5 and 6 flowed downward, the cylinders 13 and 16 were actuated, and at the same time, the cutting blade 4 was also actuated. The operating pressures of the cylinders 13 and 16 are 120 kg and 300 kg, respectively, and the operating speeds of both cylinders are 200 mm/s.

Then, as shown in Figure TiS3, after the pressing operation of the mold member 5.6 against the glass fluid 2 is started, the cutting ring 7 is activated. The cutting ring 7 is made of SK3, and 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.
, 2s by adjusting the operating timing of each cylinder 13° 16.17 using a controller (not shown).

The operating pressure of the cylinder 17 that drives this cutting ring 7 is 100 kg, and the operating speed is 2005 m/s. Further, as shown in FIG. 5, when the cutting operation by the cutting ring 7 is completed, the glass flow 2 by the cutting blade 4 is
The cutting 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. 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, the molded product 23 remains held in the cutting ring 7 so that it 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). cylinder 13
is operated to return the first mold member 6 to its original position, and the cut piece 22 is removed by a cut piece removing device (not shown).

Thus, the molded product 23 obtained in this example has an outer diameter accuracy of ±0.0005 layer 1, a center wall thickness of ±0.01 layer, and a weight of 0.02 g (±0 .7
%), there were no shear marks or other harmful surface defects, and sink marks were within 5% of each mold member.
, 6, and 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°:jS2 in this embodiment.
3 is a graph showing temporal changes in temperature of the mold member 6 and the glass which is the material to be molded. Incidentally, in this explanation, the time T shown in FIG. 8 is used.

Initially (T=O in FIG. 8), the first and second mold members 5.6 are set at the glass transition point Tg of the glass material (T of SF8).
g = 443°C) was adjusted to 400°C, which is 43°C lower.

Further, the viscosity of the glass fluid 2 flowing from the nozzle shown in FIG. 2 is adjusted to approximately IQ 4.6 poise (815°±5° C.).

Ta.

During the molding period (approximately 10 seconds) from the pressing start time T2 of the mold member 5.6 to the pressing end time T6, the glass in the molded part 21 is rapidly cooled due to the temperature difference between the mold members 5 and 6, and the viscosity is 1046 boaz to 10th 5 poise or more. In Example A, the mold member 5.6 is heated by heaters 8 and 9, respectively, so as to be maintained at 400° C. until the end of the compression, and at this time the glass temperature of the molded product 23 is approximately the same as that of the mold member 5.6. It becomes warm.

(Example 2) In this example, optical glass F8 (Tg=445
Using molten glass with a specific gravity of 3.36℃ and a specific gravity of 3.36), the outer diameter is 6 mm, the center thickness is 4 mm, and the edge thickness is 3.08 mm, using the same method as in Example 1.
m proverb, curvature is R1 = R2 = 10m intestine, glass volume 0.1
A biconvex preform for reheat press with a weight of 337 mg was molded.

In this example, the same mold members 5 and 6 as in Example 1 were used, and the heater 8.9 was adjusted so that the mold temperature was 375°C (70°C lower than the F8 Tg of 445°C). .

Further, the viscosity of the glass fluid 2 is 1Q2.95 to 1031 poise (1080
℃~1050℃).

Then, the operating pressure of each cylinder 13, 16, and 17 was set to 50 kg, 200 kg, and 50 kg, respectively, and press forming and cutting were performed in the same manner as in Example 1.
When the internal viscosity of the molded product 23 reached 109 poise (approximately 540°C), the second mold member 6 was also taken out.
The obtained molded product 23 has an outer diameter accuracy of ±0, OL+*m and a center wall thickness of ±0.02. ± in weight
The variation was within 31 g (±0.9%), and the sink mark at the center of the surface was about 40 JLm on average, and the surface condition was good and the precision was sufficient to be used as a reheat press preform.

(Example 3) - In this example, a round bar made of optical glass SF8 similar to Example 1 was used, with an outer diameter of 201 mm and a center thickness of 3 + s.
m, edge thickness, San, curvature R+=32mm, glass capacity 0. A plano-convex lens having an Ei of 133 cc and an ffE of 242 g was molded in a non-oxidizing atmosphere.

The round bar made of SF8 has a diameter of 10mm ± lag,
After removing scratches and dirt from the surface, heat it in a heating furnace (not shown).
The mixture was heated to a viscosity of approximately 0.05 poise (approximately 775°C).

The mold members 5 and 6 are made of tungsten carbide, the molding surfaces 5a and 6a are optical mirror surfaces, and the mold temperature is 510°C.
(corresponding to about 109 poise in terms of glass viscosity) using a heater 8.9. In addition, the cutting ring is also made of tungsten carbide like the mold members 5 and 6,
This 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 stirred with argono gas.

Then, the working pressures of each cylinder 13, 16, and 17 were set to 170 kg, 350 kg, and 150 kg, respectively.
Press molding 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 are completed, each cylinder is 13° 16.
17, while keeping the pressure applied, gradually weaken the output of heater 8.9 and the external heater for heating the cutting ring.
After cooling the mold member 5.6 and the molded product 22 until the temperature reaches 400° C. (glass viscosity of about 105 poise or more), the molded product 23 is molded into the second mold member 6 in the same manner as in Example 1. I took it out. 1! ) The molded product has an outer diameter accuracy of ±0.005-1 and a center wall thickness of ±0, relative to the desired molded product.
01m+s Weight: ±0.025g (±0.85
%), the surface condition was good, and there was almost no surface erosion due to sink marks, and the lens could be used as it is without particularly requiring 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.
Optical elements such as optical lenses or reheat press preforms with high dimensional and weight accuracy can be manufactured without any post-processing such as grinding or polishing after press molding.

(2) Since the precision of the glass fluid used for molding is not required, the device for discharging the molten glass etc. can be inexpensive and does not require high technology, and the weight of the discharged glass due to fluctuations in the glass liquid level in the melting furnace Since the melting furnace is flexible against temperature changes, the melting furnace may be inexpensive.

(3) In addition to molten glass, the glass material used for the I& shape may be a glass rod or sheet, and the accuracy of these materials is not required.

(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 manufactured 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. FIGS. 2 to 7 are sectional views of main parts of the apparatus shown in the first factor, and show 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. 1... Nozzle 2... Glass flow 3... Cutting mark 4... Cutting blade 5... First die member 6... Second die member 7... Cutting ring 21... Target Molded part 22... Cut piece 23... Molded product agent Patent attorney Jo Taira Yamashita Figure 1 Figure 2 Figure 31v1 Figure 4 Figure 5 Figure 6 Figure 72 Figure 8 T+ T2 T3 T4 T5 No. Figure 9

Claims (5)

[Claims] (1) After arranging a pair of molds facing each other so as to narrow the glass fluid and setting a cavity in the molds, and pressing the glass fluid against each other with the molds to form a molded part, A method for manufacturing an optical element, characterized in that the part to be molded and other parts are cut and separated using a cutting member provided on the outer periphery of a mold. (2) The method for manufacturing an optical element according to claim 1, wherein the glass fluid has a viscosity of 10 to 10^7 poise. (3) The method for manufacturing an optical element according to claim 2, wherein the glass fluid is a molten glass flow flowing down from an outflow nozzle of a glass melting furnace. (4) The method for manufacturing an optical element according to claim 2, wherein the glass fluid is made of a reheated rod or sheet glass material. (5) The glass fluid is heated at a temperature corresponding to a glass viscosity of 10^8 poise and a glass transition point (about 10^1 in glass viscosity).
3. The method for manufacturing an optical element according to claim 2, characterized in that pressure molding is carried out using a mold at a temperature that is 100° C. lower than 3 poise.