JPH0419172B2 - - Google Patents

Description

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

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

This press molding method generally includes a 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 surplus glass increases its outflow resistance and is cooled by the mold, increasing its viscosity, and is safely cut off between the mold and the anvil facing it. The molded product is cooled without being completely wet, and a protruding portion is formed on the outer periphery of the molded product. Therefore, after press forming, it is necessary to break the protruding portion and finish the broken surface. Furthermore, due to variations in the size of the molten glass flow, the glass thickness between the above-mentioned molded product and the protruding portion changes, causing variations in the thickness of the molded product, making it difficult to adjust the weight with high precision. There is also the problem of not having one.

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

In order to solve the above-mentioned problems, the present inventors arranged a pair of molds facing each other so as to narrow the glass fluid, and set a cavity of the mold, so that the glass fluid could be poured into the mold. A method for manufacturing an optical element has already been described, which comprises forming a molded part by pressing each other together, and then cutting and separating the molded part and other parts using a cutting member provided on the outer periphery of the mold. I have suggested it.

According to this method, the functional surface of the molded product can be formed while avoiding cut marks of the glass fluid, and the outer peripheral side surface of the molded product can be formed with high precision using the cutting member provided on the outer periphery of the mold, and shear marks can be formed. An optical element with excellent dimensional accuracy and weight accuracy can be obtained without surface defects such as .

In the apparatus applied to the above-mentioned optical element manufacturing method, the contact situation between the mold and the guide member that guides the movement of the mold is important for smooth pressing operation of the mold. This is a major factor. In particular, since the slidability of the mold is influenced by thermal expansion of the mold and the guide member due to temperature changes, it is important to provide means for controlling the thermal expansion of these members. In addition, as a conventional example of controlling the thermal expansion of a sliding shaft and a sliding bearing that guides the sliding movement of the sliding shaft, there is
There is a publication.

(Object of the invention) The present invention was made based on the above circumstances, and
To provide an optical element molding device that can perform molding so that the cut-out portion of the glass fluid is removed from the optically functional surface, and that can accurately and uniformly lower the weight of the material in the mold, and that can manufacture high-precision optical element molded products. The purpose is to provide.

(Means for Solving the Problem) In order to achieve this object, the present invention provides a pair of molding tools that are arranged horizontally opposite each other so as to sandwich the descending glass fluid and move in a direction substantially perpendicular to the glass fluid. a pair of molds, a heater for heating each of the molding molds, a plurality of guide pins on one side, and a plurality of fitting parts that fit on the guide pins on the other hand to guide the pressing operation of the molding molds; a cutting member that is provided on the outer periphery of at least one of the molding molds and forms a space for the optical element to be molded with the molding mold, and a cutting member that is fitted between the cutting member and the guide pin; A heating means for heating the guide member and a measuring means for measuring the temperature are arranged between the guide member and the joint part, and the guide member is heated by the heating means at the time of molding based on the temperature measurement by the measuring means. The guide member having the guide pin and the fitting portion is heated by the heating means and the measuring means at a temperature substantially equal to the temperature of the mold, and the axis of the mold and each guide on the guide member are heated. The present invention is characterized in that the distance between the pin and the fitting part is kept constant, and the misalignment of the axes of the pair of molds is corrected by the guide pin and the fitting part.

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

Furthermore, in the present invention, a plurality of guide members are provided. The guide members fit together and slide with each other as the mold is pressed, thereby preventing axis deviation of the mold and guiding the mold so that the pressing action of the mold can be performed smoothly. This guide member can be constituted by, for example, a hole and a pin that fits and slides into the hole.

By the way, since the glass fluid pressed by the mold is heated to a high temperature, when this heat is transmitted through the mold or the cutting member to the guide member, it is not necessarily conducted uniformly. However, there is a risk that variations in thermal expansion may occur.
In addition, to prevent molded products from warping and improve surface precision,
It becomes necessary to raise the temperature of each mold member. At this time,
Since the second mold member is in contact with the glass longer than the first mold member, the guide block located on the outer periphery of the second mold member is more easily heated.
A deviation occurs in the pitch between the guide member (for example, a pin) provided on the outer periphery of the first mold member and the guide member (for example, a hole) provided on the outer periphery of the second mold member. In such a case, the pitch between the plurality of guide members varies, and when the guide members fit together during press molding, they bite into each other, which not only makes it difficult to press smoothly during press molding, but also Due to pitch fluctuations in the guide member, chamfering may occur in the cutting member, and axis deviation may occur in the mold.

In the present invention, in order to eliminate such inconveniences, a heating device is provided near the mold and the cutting member to heat the mold and the cutting member to prevent pitch fluctuations of the guide member.

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 . ) is preferably set within the range of 100°C lower than Tg (Tg - 100°C). 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 reaches a viscosity 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 perspective view of a press molding apparatus used in an embodiment of the present invention. 2 to 7 are sectional views of main parts taken along the line A--A in FIG. 1, showing the operating state of the apparatus in each process order.

In these figures, 1 is a nozzle through which molten glass flows out from a melting furnace (not shown), and a glass fluid 2 flows out from this nozzle (not shown in FIG. 1). 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 includes a first mold member 5 and a second mold member constituting a pair of molds. The members 6 are arranged to face each other so as to narrow the glass fluid 2 from a substantially right angle direction.

Each mold member 5, 6 has a molding surface 5a, 6a which is mirror-finished on each opposing surface. The first mold member 5 and the second mold member 6 are moved substantially perpendicularly to each other with respect to the outflow direction of the glass fluid 2 flowing down from above by a driving source such as a cylinder (not shown), and perform a pressing operation. will be carried out.
However, these first and second mold members 5 and 6 can be opened and closed independently by separately provided drive sources.

By adjusting the operating strokes of these mold members 5 and 6 and setting the distance between them during pressure molding, the thickness of the molded product to be manufactured can be adjusted.

Further, a cutting ring 7 is provided on the outer periphery of the second mold member 6.
is provided. This cutting ring 7 is configured to have an edge-shaped cutting blade 7a in the direction of the first mold member 5, and moves while sliding on the outer periphery of the mold member 6, so that the tip of the cutting ring 7 is attached to the outer periphery of the mold member 5. The configuration is such that they fit together. Further, an annular groove 18 is provided on the outer periphery of the mold member 5, and protruding dividing blades 17 are provided at the main parts (four locations in this embodiment) of the mold member 5 to abut on the edge-shaped slope at the tip of the cutting ring 7. There is. With this configuration, after the molded portion 23 of the glass fluid 2 is pressure-molded by the pressing operation of the mold members 5 and 6, the cutting ring 7 moves in the direction of the mold member 5 and comes into contact with the dividing blade 17. Then, the part to be formed 23 is cut and separated at the outer periphery of the mold members 5 and 6, and the excess glass 22 of the part to be formed 23 is divided into pieces by the dividing blade 16.

Further, a guide block 14 is provided on the outer periphery of the mold member 6 and is fixed to the cutting ring 7 to surround the cutting ring 7, and this guide block 14 is fixed to the support member 10. A guide block 13 is also provided on the outer periphery of the mold member 5 and surrounds the mold member 5, and this guide block 13 is supported by the support member 11. Support members 10, 11
are each connected to a drive source (not shown) such as a cylinder, and the support members 10 and 11 are actuated independently by the drive of the drive source. Due to the operation of the support member 10, the cutting ring 7 fixed to the guide block 14 cuts the outer periphery of the second mold member 6 into the first mold member 5.
It moves back and forth while sliding in the direction of. Moreover, the first mold member 5 reciprocates in the direction of the second mold member 6 by the operation of the support member 11 .

Further, a guide pin 15 is fixed to the guide block 13 so as to protrude toward the guide block 14, and the guide pin 15 is fixed to the guide block 14.
A guide hole 16 is provided that fits and slides therein. Also, a sleeve 1 is installed inside this guide hole 16.
6a is provided. Guide block 13,1
4 actuate and approach each other, the guide pin 15 slides within the guide hole 16 via the sleeve 16a and guides the pressing operation of the mold members 5 and 6.

A heater 30 is provided inside each of the mold members 5 and 6.
31 is provided, and the mold members 5 and 6 are heated to a predetermined temperature by this heater.

Further, heaters 32, 33 and thermocouples 34, 35 are provided in the guide blocks 13, 14, respectively. A plurality of heaters 32 and 33 are provided in the guide blocks 13 and 14 at positions where the guide pins 15 and guide holes 15 can be heated evenly so that the mutual pitches of the guide pins 15 and guide holes 15 are maintained at a predetermined distance.
The temperature is controlled by an external controller based on temperature detection by thermocouples 34 and 35.

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 this pressing operation, the guide pin 15 fits into the guide hole 16 and slides, so that even if the mold members 5, 6 are slightly misaligned, the mold members 5, 6 are guided by the guide member and the shafts of the mold members 5, 6 are guided by the guide member. The deviation is corrected.

In FIG. 8, T=0 indicates the timing at which both mold members 5 and 6 start operating. 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, and during this time, the mold members 5 and 6 press the molded part 21 on both surfaces of the molded part 21. Pressure transfer is performed using surfaces 5a and 6a.

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

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

As shown in FIG. 5, the operation start timing T ₁ of the cutting ring 7 is determined at least when the cutting blade 4 finishes cutting the glass fluid 2 (T ₃ ) before the cutting ring 7 finishes cutting the outer periphery of the part to be formed 21 (T 3 ). T ₂ ). By doing this, the glass fluid 2 is already cut off by the cutting blade 4 when the cutting operation of the cutting ring 7 is finished, and the cut piece 22 cut by the cutting ring 7 is easily attached to the first mold member. 5 or into the annular groove 16. At this time, the cutting piece 22 has an edge-shaped inclined portion of the cutting blade 7
When the cutting ring 7 comes into contact with the cutting ring 7, it is separated, and when the cutting ring 7 returns, it falls naturally.

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.

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

Next, as shown in FIG. 6, the guide block 13 is operated to return the first mold member 5 to its original state. This operation start time is _T6 , the operation end time is _T7 , and the start time for returning the cutting ring 7 to its original state is the return end time of the first mold member 5.
At the same time as T ₇ or after its completion, cutting ring 7
Before the start of the operation, the part to be formed 21 is held by the cutting ring 7 and does not fall off naturally. Further, the cut pieces 22 separated by the cutting blade 17 fall naturally when the cutting ring 7 returns.

The part to be molded, that is, the molded part 23 is taken out at the same time as the cutting ring 7 completes its return (T ₈ ). 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 .

As shown in FIG. 7, when taking out the molded part 23, the molded product 23 is released from the state held by the cutting ring 7 by pushing out the mold member 6 in the direction of the molded member 5, and the molded product 23 It may be arranged to make it easier to take out.

In the above-described operation, press molding by the mold-like parts 5 and 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.

The cavity capacity formed by the mold members 5 and 6 can be set by the stroke of a cylinder (not shown) that presses each mold member. That is, the set stroke of the cylinder determines the shortest approach width between the mold members 5 and 6 during pressing, and this regulates the distance between the molding surfaces of the mold members 5 and 6.

In addition, in this embodiment, the pressing operation of the mold members 5 and 6 is guided by the guide member composed of the guide pin 15 and the guide hole 16, and the axis misalignment of these mold members 5 and 6 is corrected, so that the manufacturing process is improved. The molded product 23 can be used as an optical element having a highly accurate optical axis.

Furthermore, the heating means of the heaters 32 and 33, the thermocouples 34 and 35 for temperature control, and a controller (not shown) eliminate pitch fluctuations between the guide members due to variations in thermal expansion, and the guide members Fitting and sliding operations occur smoothly.

Further, the surface shape and properties of the molded product 23 are determined by the molding surfaces 5a, 6a of the mold members 5, 6, respectively. 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 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
mm, R ₂ = 40mm, glass capacity 0.636cc, weight 2.68g
A reheat press preform with a convex meniscus shape 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 these mold members 5 and 6 is 400℃ (Tg of SF8 = 443
Heater 30 so that the temperature is 43℃ lower than
Heat at 31. Further, the maximum approach width of each of the mold members 5 and 6 during the pressing operation is adjusted to 2.7 mm, so that the desired wall thickness can be obtained.

The cutting ring 7 and guide blocks 13 and 14 are
The sleeve 16a, which is made of SK3 and fitted into the inner periphery of the guide hole 16, is made of FC25. In addition, in order to prevent the pitch between each pin and guide hole from shifting due to temperature differences, heaters 32, 3 are installed.
3, the cutting ring 7, guide block 13,1
4. Heat to 400℃. At this time, the temperature difference between guide blocks 13 and 14 (guide pin 15
The pitch (30 to 50 mm) depends on each size, but good results were obtained when the pitch was within ±5°C.
Normally, it is preferable to heat the gap between the guide pin 175 and the guide hole 16 in a cold state so that the diameter thereof is about 5 to 10 μm. Therefore, in order to prevent pitch deviation even during high-temperature molding, it is preferable to control the temperature of the guide blocks 13 and 14 so that the pitch deviation due to thermal expansion is 5 μm or less.

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.
When the mold member 5 flows downward from a, 6a,
6 was activated, and at the same time, the cutting blade 4 was also activated. The operating pressures of the cylinders (not shown) that operate the mold members 5 and 6 are 120 kg and 300 kg, respectively, and the operating speeds of both cylinders are 200 mm/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) is used to control each cylinder so that the time from the time when the pressing operation of the mold members 5 and 6 is completed to the time when the cutting by the cutting ring 7 is completed is 0.2 seconds. Adjust the activation timing. The operating pressure of the cylinder (not shown) that drives this cutting ring 7 is 100 kg,
The operating speed is 200 mm/s.

Further, as shown in FIG. 5, when the cutting operation by the cutting ring 7 is completed, the cutting of the glass flow 2 by the cutting blade 4 is also completed. Further, as shown in the 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 maintaining the pressed state of the mold members 5 and 6, the state shown in FIG. Thereafter, as shown in FIG. 6, only the mold member 5 is operated to form the molded product 23.
I pulled it away. At this time, the molded product 23 remains held by the cutting ring 7 and does not fall off by itself.
Then, at the same time as the cutting ring 7 is pulled back, the molded product 23 is taken out by a handling device (not shown), and the mold member 6 is operated to return the mold member 6 to its original position. At this time, the cut pieces 22 on the outer periphery of the molded product are separated into pieces by the dividing blade 17 and removed from the mold member.

Thus, molded article 2 obtained in this example
3 is the outer diameter accuracy of ±0.005 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 for the shape of each mold member 5, 6, making it suitable for reheat press preforms. It could be used not only as an optical lens, 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 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 (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).

During the molding period (approximately 10 seconds) from the pressing start time T2 of the mold members 5 _{and 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. 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 30 and 31, respectively, so as to be maintained at 400°C until the end of pressing.
At this time, the glass temperature of the molded product 23 is this mold member 5,
It has approximately the same temperature as 6.

Example 2 In this example, optical glass F8 (Tg
= 445°C, specific gravity 3.36) using the same method as in Example 1 to obtain an outer diameter of 6 mm, a center wall thickness of 4 mm, an edge thickness of 3.08 mm, a curvature of R ₁ = R ₂ = 10 mm, and a 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).
g445℃ (70℃ lower temperature), guide member 15,1
The heaters 30 and 31 were adjusted so that the temperature of both the cutting ring 6 and the cutting ring 7 was 350°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 working pressures of the cylinders of the mold members 5, 6 and the cutting ring 7 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 is 10 ⁹
When the temperature reached 540°C, the second mold member 6 was taken out, and the molded product 23 obtained was
The outer diameter accuracy is ±0.01mm for the desired molded product.
The center wall thickness is within ±0.02, the weight is within ±3 mg (±0.9%), and the average sink mark at the center of the surface is 40μ.
It was of the order of m, and had a good surface condition and had sufficient precision to be used as a reheat press preform.

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

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

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

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

Then, the operating pressures of the mold members 5, 6 and the cutting ring 7 were set to 170 kg, 350 kg, and 150 kg, respectively, and 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, while maintaining the pressurized state of the mold members 5 and 6 and the cutting ring 7, the output of the heaters 30 and 31 and the external heater for heating the cutting ring is gradually weakened. ,6
and the temperature of the molded product 22 is 400℃ (about 400℃ in terms of glass viscosity)
After cooling the molded product 23 to a temperature of ^14.5 poise or higher), the molded product 23 is molded into the second mold member 6 in the same manner as in Example 1.
I took it out. The obtained molded product has an outer diameter accuracy of ±0.005 mm and a center wall thickness of ±0.005 mm relative to the desired molded product.
The variation at 0.01mm weight is within ±0.025g (±0.85%), the surface condition is good, and there is almost no surface deformation due to sink marks, so it can be used as is as a lens that does not require particularly high precision. Ta.

(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 high precision in cutting out 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. Furthermore, since the melting furnace is flexible in response to changes in the flow rate and temperature of the outflowing glass due to fluctuations in the glass liquid level in the melting furnace, the melting furnace may also be inexpensive.

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

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

In particular, according to the present invention, a heating device is provided near the mold and the cutting member so that the pitch of the guide members does not vary by evenly heating the mold and the cutting member. By preventing this and ensuring smooth fitting and sliding movement of the guide member and smooth pressing movement of the mold, it is possible to prevent axis deviation of the mold.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a press molding apparatus showing an embodiment of the present invention. 2 to 7 are sectional views of main parts of the device shown in FIG. 1 along line A-A,
The operating state of the device in the order of steps is shown. 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 fluid, 3... Cutting trace, 4... Cutting blade, 5... First mold member, 6...
Second mold member, 7... Cutting ring, 15... Guide pin, 16... Guide hole, 21... Molded part,
22... Cut piece, 23... Molded product, 32, 33...
...Heater inside the guide block.

Claims (1)

[Claims] 1. A pair of molds that are arranged horizontally to sandwich the descending glass fluid and move in a direction substantially perpendicular to the glass fluid, a heater that heats each of the molds, and a plurality of guide pins on one side. of,
a pair of guide members having a plurality of fitting parts that fit into the guide pins on the other hand and guiding the pressing operation of the mold, and a pair of guide members provided on the outer periphery of at least one of the molds and molded by the mold. a cutting member that blocks and forms a space for the optical element to be formed together with the mold; a heating means that heats the guide member and is arranged between the cutting member and the guide pin and the fitting portion; and a heating means that heats the guide member; and a measuring means for measuring the temperature of the guide member by the heating means based on the temperature measurement of the measuring means, the guide member having the guide pin and the fitting portion at a temperature approximately equal to the temperature of the molding die during molding. is heated by the heating means and the measuring means to maintain a constant distance between the axis of the mold and each guide pin and the fitting part on the guide member, and An apparatus for molding an optical element, characterized in that misalignment of the axes of the pair of molds is corrected by: