JP2003112930A - Forming method for optical element and forming device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method for optical elements which allows the forming of a high quality glass optical element free from a trouble such as burning in a short cycle time, suppresses the deterioration of a forming member such as die due to oxidation to the minimum and reduces cost of the optical element. SOLUTION: This forming method for optical elements consists of a preliminary heating process of heating glass blank to a temperature near the softening temperature, a preliminary forming process of conveying the heated glass blank between a pair of dies for forming which are heated up to a temperature of the glass transition temperature or less and, thereafter, pressurizing the same, a heating process of heating the glass blank and the pair of forming dies up to a temperature near the yield point of the glass blank while pressurizing the same, a forming process of pressurizing the glass blank and forming the optical element while retaining the glass blank and the pair of the forming dies at a temperature near the yield temperature, a cooling process of cooling the optical element and the pair of the forming dies in the almost isothermal state, and a releasing process of forcibly releasing the optical element from the pair of the forming dies when the optical element and the pair of the forming dies come to the glass transition temperature or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element molding method and molding apparatus for obtaining an optical element by press-molding a glass material softened by heating with a pair of molding dies.

[0002]

2. Description of the Related Art Conventionally, as a method or apparatus for molding an optical element such as a high precision glass lens, for example, Japanese Patent Laid-Open No. 11-
There are inventions described in Japanese Patent No. 171564 and Japanese Patent Application Laid-Open No. 11-100221.

The invention described in Japanese Patent Application Laid-Open No. 11-171564 discloses a step of pressing a preheated glass material with preheated upper and lower molds to form a glass molded body, a step of cooling the formed glass molded body, and a cooling step. The present invention relates to a method for producing a glass molded body by repeating a step of releasing the formed glass molded body from the upper and lower molds and a step of preheating the glass material and the upper and lower molds.

The invention described in Japanese Patent Application Laid-Open No. 11-100221 discloses a method in which a heated glass material is conveyed between upper and lower temperature-controllable molds each having independent heating means and external heat insulation means, and the glass is heated. The present invention relates to a device for press-molding a lens.

[0005]

However, in the invention described in Japanese Patent Application Laid-Open No. 11-171564, the preheating temperature of the glass material is set to a temperature corresponding to a viscosity of 10 ⁹ poise or less, and the preheating temperature of the mold is set to the glass material. However, if the mold preheat temperature is set to a temperature higher than the transition point of the glass material, seizure easily occurs between the mold and the glass material and stable molding of good products is not possible. . Also, because induction heating is used as the heating method,
It is difficult to make the temperature of the mold uniform, the surface accuracy of the molded lens deteriorates, and a high-frequency heating coil and cooling water piping are required, which makes the structure around the mold complicated and large. Further, since the glass material is heated and softened in the molding chamber replaced with a non-oxidizing atmosphere, the oxygen concentration in the non-oxidizing atmosphere rises due to the volatilization of oxygen contained in the glass, and the mold is damaged by oxidation. There was a problem.

Further, in the invention described in Japanese Unexamined Patent Publication No. 11-100221, the relationship between the temperature of the glass material and the temperature of the upper and lower molds is not described in detail, and even in the only described embodiment, the glass material is used. The heating temperature is low, below the transition point, and at such temperatures, glass materials that are thick in the center such as glass gobs and flat pieces can be used to form optical elements with thin centers such as biconcave lenses and concave meniscus lenses. Due to the high viscosity, there is a problem that the time for reheating on the mold during molding becomes very long.

The present invention has been made in view of the above-mentioned problems of the prior art. It is possible to mold a high-quality glass optical element having no problem such as image sticking in a short cycle time and to oxidize a molding member such as a mold. It is an object of the present invention to provide an optical element molding method and a molding apparatus capable of minimizing deterioration and reducing the cost of the optical element.

[0008]

In order to solve the above problems, in the method of molding an optical element according to the invention of claim 1, a glass material is heated and softened and pressed into a desired shape by a pair of molding dies. In the method of molding an optical element, a preliminary heating step of heating a glass material to a temperature near a softening point in advance, and a preliminary heating step of conveying the glass material between a pair of molding dies heated to a temperature of a glass transition point or less and then pressing Molding step, a heating step of heating the glass material and the pair of molding dies to a temperature near the sag point of the glass material while pressing, and the temperature of the glass material and the pair of molding dies near the sag point A molding step of molding the optical element by pressing the glass material while maintaining a certain period of time, a cooling step of cooling the optical element and the pair of molding dies while keeping them at substantially equal temperature, the optical element and the Mold pair is characterized in that it consists, a releasing step of releasing said optical element from forcing the pair of mold when it becomes below the glass transition point.

According to the present invention, since the glass material is heated to near the softening point, the glass material can be largely deformed at a low pressure at the initial stage of molding of the optical element, while the temperature of the molding die is below the glass transition point. Since it is low, the optical element can be molded in a short time without a problem such as seizure. In addition, since the mold temperature and the temperature of the glass material are almost equal to each other and the temperature is slightly increased from the vicinity of the glass transition point to the yield point, it takes no time to heat up the temperature and the molding cycle time can be shortened. Further, since the optical element and the molding die are cooled to a temperature not higher than the glass transition point and then the mold releasing means forcibly releases the mold, a highly accurate glass lens can be molded.

A method of molding an optical element according to a second aspect of the invention is
The optical element molding method according to claim 1, wherein the glass material is heated in the atmosphere in the preheating step, and the glass material is pressed in a non-oxidizing atmosphere in the preforming step.

According to the present invention, in addition to the function of the first aspect of the invention, since the glass material is heated in the atmosphere and is separated from the molding space kept in the non-oxidizing atmosphere, it is possible to heat the glass. Oxygen generated together does not increase the oxygen concentration in the molding space, and can prevent deterioration of the mold and jig due to oxidation.

According to a third aspect of the invention, there is provided an optical element molding apparatus,
A plurality of preheating means for heating the glass material to a temperature near the softening point in advance, a heating means for heating the pair of molding dies, and a molding for molding the optical element by pressing the glass material with the pair of molding dies. Means, a plurality of conveying means for conveying the heated glass material between the pair of molding dies, and carrying out a molded optical element from between the pair of molding dies, the optical element and the pair of Cooling means for cooling the molding die in a state where the molding die is kept substantially isothermal, and forcibly from the pair of molding dies to the optical element when the optical element and the pair of molding dies are below the glass transition point. And a releasing means for releasing.

According to the present invention, in addition to the function of the invention of claim 1, preheating means for heating the glass material in advance to a temperature near the softening point and the heated glass material are carried in between a pair of molding dies. At the same time, since it has a plurality of transporting means for carrying out the molded optical element from between the pair of molding dies, the molding time can be further shortened by simultaneously operating these on a plurality of glass materials. You can

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. (Embodiment 1) (Structure) FIGS. 1 to 5 show the structure of an optical element molding machine according to Embodiment 1 of the present invention. FIG. 1 is a side sectional view of a molding machine. FIG. 2 is an enlarged sectional view around the mold set of the molding machine. FIG. 3 is a top view showing the arrangement of the glass material transport system. 4 (a) and 4 (b) are perspective views of the sleeve constituting the mold set as seen from the front and side surfaces, respectively.
FIG. 5A and FIG. 5B are a front view and a plan view of the transfer arm, respectively.

A mold set 1 including an upper mold 1a, a lower mold 1b and a sleeve 1c is arranged in a purge chamber 20. The upper die 1a and the lower die 1b are fixed to the respective tips of an upper shaft 2 penetrating the upper wall surface of the purge chamber 20 and a lower shaft 3 penetrating the lower wall surface thereof, and are vertically opposed to each other. Two
And the lower shaft 3 are the upper cylinder 1 for driving, respectively.
3 and the lower shaft cylinder 15 are fixed. The upper shaft cylinder 13 is fixed on the upper wall surface of the purge chamber 20 via a mounting member, and the lower shaft cylinder 15 is fixed on the base 30. In the present embodiment, the mold set 1, the upper shaft 2, the lower shaft 3, the upper shaft cylinder 13, and the lower shaft cylinder 15 constitute a molding means.

Around the upper die 1a and the upper shaft 2, a ring-shaped lamp heater 4a and a reflection plate 5 surrounding the lamp heater 4a.
a is arranged. The reflection plate 5a is fixed to the upper wall surface of the purge chamber 20 via a reflection plate fixing tool 6a, and the lamp heater 4a is fixed to the reflection plate fixing tool 6 via a lamp heater fixing tool 7a.
It is fixed to a. The purge chamber 20 is fixed to the base 30 by columns 31.

On the other hand, around the lower die 1b and the lower shaft 3,
A ring-shaped lamp heater 4b and a reflector 5b are arranged so as to surround the lamp heater 4b. The reflection plate 5b is fixed to the lower wall surface of the purge chamber 20 via a reflection plate fixture 6b, and the lamp heater 4b is fixed to the reflection plate fixture 6b via a lamp heater fixture 7b. Lamp heaters 4a and 4
b may be any as long as it has the ability to heat the mold set 1 and the glass material to near the softening point of the glass. In the present embodiment, the lamp heaters 4a and 4b and the reflection plate 5 are provided.
The heating means is constituted by a and 5b.

Further, a ring-shaped cooling blow 32 as a cooling means is provided above the lamp heater 4b so as to surround the mold set 1, and a non-oxidizing gas (here, nitrogen) is supplied by a pipe (not shown). It can be supplied. A large number of holes for ejecting nitrogen gas for cooling the glass lens are provided on the inner peripheral side of the cooling blow 32.

The sleeve 1c is shown in FIGS. 4 (a) and 4 (b).
As shown in Fig. 2, large holes 1 are formed on both sides of the cylindrical body 1g.
with d. Main body 1g is upper mold 1a, lower mold 1b
Positioning and acting as a guide when sliding, hole 1d
Is provided for the purpose of allowing the transfer arm 26, which will be described later, to enter the sleeve 1c and for supporting the sleeve 1c by the release ring 8.

Further, the mold release ring 8 arranged so as to partially surround the tip of the upper mold 1a in proximity to the purge chamber 20 through the ring support rod 9 penetrating the upper wall surface of the purge chamber 20.
It is attached to the fixed plate 10 outside the
0 is fixed to a release air cylinder 11 for releasing the molded glass lens. In the portion where the ring support rod 9, the upper shaft 2 and the lower shaft 3 penetrate the purge chamber 20,
A shaft seal ring 12, a shaft seal 14a and a shaft seal 14b are provided respectively, and the airtightness of the purge chamber 20 is ensured by sealing the gap. In the present embodiment, the release ring 8 and the release air cylinder 11 constitute a release means.

On the side surface of the purge chamber 20, there is an opening 20a for carrying in the glass material and carrying out the molded lens.
Is provided, and the opening 20a is provided with a first shutter 18 that is opened / closed at the time of loading and unloading. The operation of the first shutter opening / closing cylinder 16 fixed to the inner upper wall surface of the purge chamber 20 is transmitted to the first shutter 18 via the joint 17, and is rotated about the shaft portion 18a. The first opening 20a of the purge chamber 20
A shutter seal ring 19 is provided at a portion in contact with the shutter 18 in order to ensure the airtightness of the purge chamber 20.

A spare chamber 21 is provided at the opening 20a of the purge chamber 20 by connecting the opening at one end thereof.
A second shutter 22 is provided at the opening on the other end side of the preliminary chamber 21 to ensure the airtightness of the preliminary chamber 21. The second shutter 22 is attached to a second shutter opening / closing cylinder 23 for opening / closing, and can be opened / closed in the vertical direction. The second shutter opening / closing cylinder 23 is fixed to a base 30 of the molding machine. Pipes (not shown) are connected to the purge chamber 20 and the spare chamber 21 so that a non-oxidizing gas (here, nitrogen) can be supplied.

On the extension line connecting the preliminary chamber 21 and the mold set 1, a transfer arm 26 as a transfer means for transferring the glass material before molding and the molded glass lens,
It is installed so that it can move in and out of the purge chamber 20 by a positioning robot (not shown). As shown in FIGS. 5 (a) and 5 (b), the tip of the transfer arm 26 has a transfer claw 25 having a substantially U-shaped opening having a step 25a.
Is provided. The transfer claw 25 has a transfer holder 34 placed on the step 25a thereof and transfers a glass material or a glass lens. The sectional shape of the transfer arm 26 is 0.
The clearance of 2 mm to 0.5 mm corresponds to the cross-sectional shape of the inside of the preliminary chamber 21, and when the transfer arm 26 is inserted into the preliminary chamber 21, the opening of the preliminary chamber 21 can be closed. ing.

As shown in FIG. 2, the transport holder 34 is formed in a cylindrical shape having a storage portion 34a for a glass lens (including a glass material; the same applies hereinafter) inside, and a glass lens 33 is provided at the lower inner periphery thereof. The mounting part 34b to be mounted is the lower mold 1
It is provided so as to form a hole 34c having a size capable of inserting the molding portion of b.

A push-up cylinder 28 and a push-up cylinder 29 for vertically driving the push-up cylinder 28 are provided outside the reserve chamber 21 on an extension line connecting the spare chamber 21 and the mold set 1, and the push-up cylinder 29 is a base. It is fixed on 30. The push-up 28 is for mounting the transport holder 34, which transports the glass material or the glass lens, on the transport claw 25, or for loading it into the heating furnace 27 described later.

Above the push-up 28, a heating furnace 27 as a preheating means for preheating the glass material is fixed to the base 30 via the heating furnace support plate 24. The heating furnace 27 may be of any type such as a resistance heating furnace or a lamp heater as long as it has the ability to heat the glass material to near the softening point of the glass.

Although not shown in the drawing, a transport holder 34 having a glass material placed on the transport claw 25 of the transport arm 26 is also provided.
The carrier holder supply / recovery device for supplying the carrier gas and recovering the carrier holder 34 on which the molded glass lens is mounted from the carrier claw 25 is preliminarily provided with respect to the heating furnace 27 on the extension line connecting the preliminary chamber 21 and the mold set 1. It is installed on the opposite side of the chamber 21.

WC having excellent heat resistance was used for the mold set 1 and the transport holder 34.

(Operation) A process of molding a glass lens using the molding machine having the above-described structure will be described. Nitrogen gas is introduced into the purge chamber 20 and the spare chamber 21 through a pipe (not shown) and is kept in a nitrogen atmosphere of 100 ppm or less. The upper mold 1a and the lower mold 1b are lamp heaters 4a and 4b.
Is heated in advance to a temperature below the glass transition point of the glass material.

The transport holder 34 on which the glass material is placed is
It is placed on the transfer claw 25 at the tip of the transfer arm 26 by a transfer holder supply / recovery device (not shown). The transfer arm 26 advances by a positioning robot (not shown), and stops when the transfer holder 34 is positioned immediately above the push-up 28. The push-up cylinder 29 is driven to raise the push-up cylinder 28, and the glass material is transported together with the transport holder 34 by the transport claw 25.
From the inside to the heating furnace 27. At this time, the heating furnace 27
Is set to a temperature above the softening point of the glass (for example, 800 ° C.). When the glass material is heated to a temperature near the softening point in the heating furnace 27, the push-up cylinder 29 lowers the push-up cylinder 28, and the transport holder 34 on which the softened glass material is placed is placed on the transport pawl 25 again. .

Immediately after the second shutter opening / closing cylinder 23 is driven to lower the second shutter 22 and open the opening of the preliminary chamber 21, the transfer arm 26 is advanced into the preliminary chamber 21. At this time, since there is almost no gap between the transfer arm 26 and the preliminary chamber 21, the nitrogen in the preliminary chamber 21 does not leak.

Next, the first shutter opening / closing cylinder 16 is driven to move the first shutter 18 via the joint 17 to open the opening 20a of the purge chamber 20, and the transfer arm 2
6 is further advanced and stopped when the transport holder 34 mounted on the transport claw 25 passes through the hole 1d of the sleeve 1c and is located at the center of the mold set 1.

Next, the lower shaft cylinder 15 is driven to drive the lower mold 1.
b is pushed up, the transfer holder 34 on which the glass material is placed is transferred from the transfer claw 25 onto the lower mold 1b, and moved to the molding position. Thereafter, the transfer arm 26 is retracted to the outside of the preliminary chamber 21, and the first shutter 18 and the second shutter 22 are sequentially closed to maintain the nitrogen concentration in the purge chamber 20 and the preliminary chamber 21 so as not to decrease. FIG. 6 shows changes in the temperature of the glass material and the upper mold 1a and the lower mold 1b (hereinafter referred to as mold temperature) and the pressing force applied to the glass material in the molding process. Process: In the process I), there is a large difference between the temperature of the glass material and the mold temperature, and the glass material is in a low viscosity state even after being discharged from the heating furnace 27 due to the heat retaining effect of the transport holder 34, and in a low viscosity state. Is maintained.

The upper die 1a is moved down by driving the upper shaft cylinder 13, and the glass material is press-molded between the lower die 1b and the lower die 1b into a desired shape of the glass lens (preforming step: step II). In this step II, as shown in FIG. 6, the temperature of the glass material is rapidly lowered by contact with the upper mold 1a, and the mold temperature is slightly increased to become isothermal. Does not happen.

After the glass material is molded into the general shape, the output of the lamp heaters 4a and 4b is increased to increase the temperature of the mold and the temperature of the glass material to the vicinity of the sag point while continuing pressing for finish molding ( Heating step: Step III).
When the mold temperature and the temperature of the glass material become isothermal near the sag point, take soak time as in step IV. In step III and step IV (molding step), the shape of the glass material formed into the approximate shape is transferred with desired surface accuracy.

When the finish molding is completed, the lamp heater 4
While reducing the outputs of a and 4b, nitrogen is blown from the cooling blow 32 to the outer periphery of the mold set 1 to cool it to a temperature below the glass transition point while maintaining the isothermal state of the mold and the glass lens (cooling step: step V).

Finally, when the temperature of the mold and the glass lens reaches the glass transition point or lower, the pressing is released, and the upper ring cylinder 13 raises the upper mold 1a to release the mold release ring 8 by the mold release air cylinder 11. By lowering, the outer periphery of the transport holder 34 and the glass lens 33 is pressed by the release ring 8, and the transport holder 34 and the glass lens 33 are left on the lower mold 1b (release process: process VI).

Next, the first shutter 18 and the second shutter 22 are opened, the transfer arm 26 is moved forward, and the transfer claw 25 is moved.
Is inserted immediately below the transport holder 34. Then, the lower die 1b is lowered by the lower shaft cylinder 15, and the glass lens 33
After placing the carrier holder 34 on which the carrier is mounted on the carrier claw 25,
The transfer arm 26 is retracted and carried out. The carried-out glass lens is collected together with the transport holder 34 by a transport holder supply / collection device (not shown).

In addition, immediately after carrying out the glass lens, the upper mold 1
The a and the lower mold 1b are heated again by the lamp heaters 4a and 4b to a temperature below the glass transition point of the glass material.
On the other hand, during the molding process, the transport holder 34 on which the glass material to be processed next is placed is placed on the transport claw 25 at the tip of the transport arm 26 by the transport holder supply / collection device (not shown), and the push-up cylinder 29 is pushed. Is driven into the heating furnace 27 and preheated.

By repeating the above steps, glass lenses can be molded one after another from a glass material.

(Effect) According to the present embodiment, the glass lenses can be successively molded from the glass material, and the molding efficiency is good. In addition, since the glass material is heated to near the softening point in the initial stage, it is possible to mold a glass material such as a glass gob or flat piece into a glass lens with a thin center wall such as a concave lens or a concave meniscus lens. Has good fluidity and can be molded in a short time. Further, since the mold temperature and the temperature of the glass material are molded and cooled in a state where the temperature of the glass material and the temperature of the glass material are nearly equal, it is possible to mold a highly accurate glass lens. Furthermore, since the heating furnace 27 is outside the purge chamber 20, the oxygen concentration in the purge chamber 20 does not rise due to the oxygen generated by the heating of the glass, and the sealing member improves the airtightness so that the outside air to the purge chamber 20 can be improved. By suppressing the inflow of oxygen, the oxygen concentration in the purge chamber 20 can be suppressed to a low level, and deterioration of the mold and jig due to oxidation can be prevented.

(Second Embodiment) FIG. 7 and FIG. 8 show the structure of an optical element molding machine according to a second embodiment of the present invention. FIG. 7 is a top view showing the arrangement of the glass material transport system, and FIG. 8 is a perspective view of the sleeve constituting the mold set.

The mold set 1 includes an upper mold 1a and a lower mold 1b (see FIG.
Reference chamber) and the sleeve 1e, and the purge chamber 20
It is located inside. The purge chamber 20 is provided with an opening on a side surface (an upper side surface in FIG. 7) different from the side surface provided with the opening 20a (see FIG. 1) connecting the preparatory chamber 21 in correspondence with the arrangement position of the mold set 1. A spare chamber 41 is provided in connection with the opening. A shutter for opening and closing the opening is provided in this opening similarly to the opening 20a, and a seal is provided to ensure the airtightness of the purge chamber 20. A shutter is also provided at the opening of the spare chamber 41 so that it can be opened and closed like the opening of the spare chamber 21. Further, a pipe (not shown) is connected to the preparatory chamber 41 so that a non-oxidizing gas (here, nitrogen) can be supplied.

The sleeve 1e, as shown in FIG.
The cylindrical main body has large holes 1f on the four side surfaces. The body of the sleeve 1e serves as a guide for positioning and sliding the upper die 1a and the lower die 1b, and the hole 1f is inserted into the purge chamber 20 through the transfer arm 26 and the preliminary chamber 41. It is provided for the purpose of supporting the sleeve 1e by the release ring 8 when the transfer arm 43 of FIG.

On the extension line connecting the preliminary chamber 41 and the mold set 1, a transfer arm 43 as a transfer means for transferring the glass material before molding and the molded glass lens,
It is movably installed by a positioning robot (not shown). At the tip of the transfer arm 43, a transfer claw 42 having a step 42a is provided, and the transfer holder 34 is placed on the transfer claw 42 to transfer the glass material or the glass lens. Transport arm 4
3, the shapes of the transfer claw 42 and the step portion 42a are similar to the shapes of the transfer arm 26, the transfer claw 25, and the step portion 25a of the first embodiment.

A push-up cylinder 45 and a push-up cylinder (not shown) for vertically driving the push-up cylinder 45 are provided outside the spare chamber 41 on the extension line connecting the spare chamber 41 and the mold set 1. It is fixed on the base 30. The push-up 45 is for mounting the transport holder 34, which transports the glass material or the glass lens, on the transport claw 42, or for loading it into the heating furnace 44 described later.

Above the push-up 45, a heating furnace 44 as a heating means for preheating the glass material is fixed to the base 30 via a heating furnace support plate (not shown).

Although not shown, the transport holder 34 having the glass material placed on the transport claw 42 of the transport arm 43.
Of the heating furnace 44 on the extension line connecting the preliminary chamber 41 and the mold set 1 with each other. It is installed on the opposite side of the chamber 41. Since other configurations are the same as those in the first embodiment, detailed description will be omitted.

(Operation) A process of molding a glass lens using the molding machine having the above-described structure will be described. In the following description, FIG. 1 will be referred to as necessary.

Nitrogen gas is introduced into the purging chamber 20, the preparatory chamber 21, and the preparatory chamber 41 through a pipe (not shown), and 100 p
It is kept in a nitrogen atmosphere of pm or less. Also, the upper mold 1a
The lower mold 1b is preheated to a temperature below the glass transition point of the glass material by the lamp heaters 4a and 4b.

The transport holder 34 on which the glass material is placed is
It is placed on the transfer claw 25 at the tip of the transfer arm 26 by a transfer holder supply / recovery device (not shown). The transfer arm 26 advances by a positioning robot (not shown), and stops when the transfer holder 34 is positioned immediately above the push-up 28. The push-up cylinder 29 is driven to raise the push-up cylinder 28, and the glass material is transported together with the transport holder 34 by the transport claw 25.
From the inside to the heating furnace 27. At this time, the heating furnace 27
Further, the heating furnace 44 is set to a temperature (eg, 800 ° C.) above the softening point of the glass. When the glass material is heated to a temperature near the softening point in the heating furnace 27, the push-up cylinder 29 lowers the push-up cylinder 28, and the transport holder 34 on which the softened glass material is placed is placed on the transport pawl 25 again. .

Since the steps of molding the glass material into a glass lens and carrying it out are the same as in the first embodiment, detailed description will be omitted.

Immediately after the glass lens is carried out, the upper mold 1a and the lower mold 1b are heated again by the lamp heaters 4a and 4b to a temperature below the glass transition point of the glass material. on the other hand,
During the molding process, the transport arm 43, in which the transport holder 34 on which the glass material to be molded next is placed, is placed on the transport claw 42.
However, it moves forward by a positioning robot (not shown), and when the transport holder 34 is located directly above the push-up 45, the push-up 45 is raised to bring the glass material together with the transport holder 34 from the transport claws 42 into the heating furnace 44 for preheating. Has been done.

The preheated glass material is pushed up 4
By the lowering of 5, the transport holder 34 and the transport holder 34 are placed on the transport claw 42 again.

Hereinafter, Embodiment 1 is applied to this glass material.
Molding is performed in the same process as. 2 through the above steps
By repeating the heating furnaces 27 and 44 and the two transfer arms 26 and 43 alternately, it is possible to successively form glass lenses from the glass material.

(Effects) According to the present embodiment, in addition to the effects obtained in the first embodiment, by having two heating furnaces 27 and 44, while one glass material is being formed, the other glass material is being formed. Can be preheated with a margin of time, or by having two transfer arms 26 and 43,
Since individual glass materials can be treated completely independently, it is possible to mold glass lenses from the glass material more efficiently one after another.

The technical idea of the following configuration is derived from the above-described specific embodiments. (Additional remarks) (1) In the method of molding an optical element in which a glass material is softened by heating and pressure-molded into a desired shape with a pair of molding dies, preheating in which the glass material is preheated to a temperature near its softening point in the atmosphere. A step, a preforming step of pressing the glass material between a pair of molding dies heated to a temperature not higher than the glass transition point and then pressing the glass material and the pair of molding dies while pressing the glass material. A heating step of heating to a temperature near the sag point, a molding step of molding the optical element by pressing the glass material while maintaining the glass material and the pair of molding dies at a temperature near the sag point for a certain period of time, A cooling step of cooling the optical element and the pair of molding dies while maintaining them at a substantially equal temperature, and forcibly forcing the pair of the optical element and the pair of molding dies at a temperature below a glass transition point. For molding A releasing step of releasing the optical element from the mold,
The method for molding an optical element, comprising: performing the preforming step to the releasing step in a non-oxidizing atmosphere.

(2) The method for forming an optical element as described in appendix (1), characterized in that the glass material to be formed next is preheated while the glass material is pressed in the forming step.

(3) Preheating means for preheating the glass material in the atmosphere to a temperature near the softening point, heating means for heating the pair of molding dies, and pressing the glass material with the pair of molding dies. Forming means for forming an optical element, conveying means for conveying the heated glass material between the pair of molding dies, and conveying out the molded optical element between the pair of molding dies, and the optical means. A cooling means for cooling the element and the pair of molding dies while maintaining them at substantially equal temperature,
The optical element and a mold releasing means for forcibly releasing the optical element from the pair of molding dies at a time when the pair of molding dies is below the glass transition point. A molding device for an optical element, characterized in that the means, the cooling means and the releasing means are arranged in a non-oxidizing atmosphere.

(4) The optical element molding apparatus as set forth in appendix (3), wherein one or two preheating means and conveying means are provided.

[0061]

According to the present invention, since the glass material is heated to the vicinity of the softening point, the glass material can be largely deformed at a low pressure in the initial stage of molding of the optical element, while the temperature of the molding die is glass transition. Since it is as low as the point or less, the optical element can be molded in a short time without causing problems such as image sticking. In addition, since the mold temperature and the temperature of the glass material are almost equal to each other and the temperature is slightly increased from the vicinity of the glass transition point to the yield point, it takes no time to heat up the temperature and the molding cycle time can be shortened. Further, since the optical element and the molding die are cooled to a temperature not higher than the glass transition point and then the mold releasing means forcibly releases the mold, a highly accurate glass lens can be molded.

Further, according to the present invention, since the glass material is heated in the air and is separated from the molding space kept in the non-oxidizing atmosphere, oxygen generated by the heating of the glass causes the molding space to grow. Oxygen concentration does not increase, and deterioration of the mold and jig due to oxidation can be prevented.

Further, according to the present invention, the preheating means for heating the glass material to a temperature near the softening point in advance, the heated glass material is carried between the pair of molding dies, and the molded optical element is provided. Since a plurality of conveying means for carrying out from a pair of molding dies are both provided, by simultaneously operating these on a plurality of glass materials, the molding time can be further shortened.

[Brief description of drawings]

FIG. 1 is a side sectional view of a molding machine according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view around a mold set of the molding machine according to the first embodiment of the present invention.

FIG. 3 is a top view showing the arrangement of the glass material transport system according to the first embodiment of the present invention.

[Fig. 4] Fig. 4 shows a sleeve constituting the mold set according to the first embodiment of the present invention, Fig. 4 (a) is a perspective view seen from the front and Fig. 4 (b) is a perspective view seen from the side.

5A and 5B show a transfer arm according to the first embodiment of the present invention, FIG. 5A being a front view and FIG. 5B being a plan view.

FIG. 6 is a diagram showing a molding process according to the first embodiment of the present invention.

FIG. 7 is a top view showing an arrangement of a glass material carrying system according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing a sleeve which constitutes a mold set according to a second embodiment of the present invention.

[Explanation of symbols]

Type 1 set 1a Upper mold 1b Lower mold 4a, 4b lamp heater 5a, 5b Reflector 8 Release ring 11 Release air cylinder 13 Upper shaft cylinder 15 Lower shaft cylinder 20 Purge chamber 21,41 Spare room 25,42 Transfer claw 26,43 Transfer arm 27,44 heating furnace 32 Cooling blow 33 glass lens 34 Transport holder

Claims (3)

[Claims] 1. A preheating step of heating a glass material to a temperature near a softening point in advance in a method of molding an optical element in which a glass material is softened by heating and pressure-molded into a desired shape with a pair of molding dies, A preforming step in which the glass material is heated to a temperature not higher than the glass transition point and conveyed between a pair of molding dies and then pressed, and the glass material and the pair of molding dies are pressed while pressing in the vicinity of the yield point of the glass material. A heating step of heating to a temperature, a molding step of pressing the glass material to form an optical element while maintaining the glass material and the pair of molding dies at a temperature near the sag point for a certain time, and the optical element. A cooling step of cooling the pair of molding dies while keeping them substantially isothermal, and forcibly from the pair of molding dies when the optical element and the pair of molding dies are below the glass transition point. The above A mold release step of releasing the optical element,
A method for molding an optical element, comprising: 2. The method for forming an optical element according to claim 1, wherein the glass material is heated in the atmosphere in the preheating step, and the glass material is pressed in a non-oxidizing atmosphere in the preforming step. 3. A plurality of preheating means for heating a glass material to a temperature near a softening point in advance, a heating means for heating a pair of molding dies, and an optical system for pressing the glass material with the pair of molding dies. Molding means for molding an element, a plurality of transportation means for transporting the heated glass material between the pair of molding dies, and unloading the molded optical element from between the pair of molding dies, and the optical A cooling means for cooling the element and the pair of molding dies while maintaining them at substantially equal temperature,
An optical device comprising: the optical element and a releasing means for forcibly releasing the optical element from the pair of molding dies when the pair of molding dies is below the glass transition point. Element molding equipment.