JP2002274869A - Molding die for optical device and method of molding optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily set a minimum die processing diameter and to stably mold an optical device with a desired outside diameter and wall thickness by using a glass gob with a large volume. SOLUTION: In the molding die for the optical device by pressing a heated, softened glass gob with a heated pair of molding dies, the processing diameter of the molding die is determined by adding the outer diameter tolerance a and the outer diameter run-out tolerance b to the outer diameter L of a lens. The part of the molding die outside this processing diameter is formed on a plane so that the opposed pair of molding dies are away from each other.

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 die and an optical element molding method for molding an optical element by pressing a heat-softened glass material.

[0002]

2. Description of the Related Art Conventionally, a desired optical element has been obtained by sandwiching a heat-softened glass material with a pair of heated molds and pressing it. In recent years, the need for optical products that require high-precision image quality has increased, and the accuracy of the lens itself as an optical element has also been required to be of high quality. There is a demand for lenses, and it is difficult to supply lenses by molding easily.

[0003] When the outer peripheral thickness of the lens to be molded becomes thin, contact of the outer peripheral portion between a pair of molding dies becomes a problem when pressing and molding the lens, and it is possible to mold a lens having a large transfer surplus area outside the effective optical diameter of the lens. And no good accuracy can be obtained. For example, as disclosed in the manufacturing method of an aspherical molded lens in Japanese Patent No. 2661449,
By using a mold having a transfer surplus area on the outer periphery of the mold that is a flat surface, contact between the molds is prevented, thereby making it possible to manufacture a lens. Further, as disclosed in the aspherical lens mold of Japanese Patent No. 251405, the effective aspherical diameter of the mold is calculated by ((optical effective diameter of lens) + (lens contraction length from heating temperature to normal temperature) −). (Mold shrinkage length from heating temperature to room temperature), that is, shrinkage calculation of the mold optical effective surface at room temperature as the optical effective surface of the lens + the lens shrinkage-the mold shrinkage, thereby obtaining the mold outer periphery. , And it is possible to perform molding while securing the optical effective diameter of the desired lens.

[0004]

When molding a lens,
When a shift occurs in the charging position when the glass material is charged into the molding die, if the pressing is performed in that state, the amount of waste material in the shifted one becomes extremely large. Then, the waste material is formed in the flat part of the outer periphery of the mold beyond the surplus range of the lens, and the glass material becomes very difficult to flow, and under normal conditions, the thickness of the formed lens varies There was something. Also,
If the volume of the glass material is reduced in order to minimize waste, there are cases where a part that is not pressed and formed by a molding die occurs, and the molded lens becomes defective. Further, in a method of molding a lens with a transfer surplus range as a plane using a mold having a transfer surplus range portion as a plane,
If the shape of the lens is not deformed, it may not be possible to handle it, or if a mold using shrinkage calculation is used, the pressing conditions of the lens may be changed, the pressing load and temperature may not match the actual molding conditions, etc. there were.

[0005] Therefore, using a large glass material,
It was necessary to easily determine the shape (minimum die diameter) of the molding die so that even if the charging position of the glass material with respect to the molding die was displaced, the formed medium thickness did not vary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and it is possible to easily set a minimum processing diameter of a mold and use a glass material having a large volume to form an outer diameter and a medium thickness of an optical element. It is an object of the present invention to provide an optical element molding die and an optical element molding method capable of stably molding a desired size.

[0007]

According to a first aspect of the present invention, there is provided an optical element molding die according to the present invention, wherein a heated and softened glass material is pressed by a pair of heated molding dies to form an optical element. When molded, in the optical element molding die, the mold processing diameter of the molding die is defined as the outer diameter of the desired optical element + the misalignment tolerance + the outer diameter processing tolerance. It is characterized in that it is set as a plane or an R-plane so that the molds are separated from each other.

Further, in the optical element molding method according to the second aspect of the present invention, the glass material is heated and softened simultaneously with the pair of molds, or after the glass material is separately heated and softened with the pair of molds. Conveyed between the pair of molds, in the optical element molding method of molding an optical element by pressing the glass material in the pair of molds, measuring the molded optical element, at least the outer diameter of the optical element It is characterized in that an optical element molding die whose processing diameter of the die is modified as necessary so as to be secured is used.

In general, at least the lens outer diameter, the effective diameter, the deviation of the outer diameter with respect to the optical axis, and the tolerance of each of the above-mentioned diameters are described in the lens drawing of the lens to be molded. It is possible to easily calculate the mold processing diameter from the lens drawing and to cope with the case where the volume of the glass material is relatively large. The effective diameter is a portion used optically, and since the lens outer diameter is used for fixing the lens, its diameter is set. The effective diameter is required to be on the order of submicron in terms of shape, but otherwise may be on the order of several tens of microns, and the lens outer diameter and the outer diameter deflection tolerance are each 50 mm.
It is about μm. Further, the effective diameter and the lens outer diameter usually have an interval of 0.5 mm or more.

In the optical element molding die of the first aspect, the first
Molding to the outside diameter of the lens (optical element) ensures sufficient transfer accuracy within the effective diameter of the lens even if the shrinkage of the glass is taken into account. Therefore, the mold processing diameter is obtained by adding the above-mentioned tolerance, that is, the misalignment tolerance and the outer diameter processing diameter tolerance to the outer diameter of the optical element. In addition, when the heat-softened glass material is pressed by a pair of forming dies facing each other, if the outer peripheral portions are close to each other or at least one of them is a flat shape, the flow of the glass material during press forming is obstructed. Therefore, when the glass material has a large volume and the glass protrudes from the processing diameter, it is difficult to secure the inner wall of the lens to be molded. For this reason, after the above-mentioned mold processing diameter is secured, the outer peripheral portion is appropriately configured to be a flat surface or an R surface so that the outer peripheral portions of the molding die are separated from each other.

According to the optical element molding method of the second aspect, the optical element actually molded by the optical element molding die of the first aspect is measured, and at that time, the outer diameter of the optical element is measured.
If the size of the outer diameter is insufficient due to the contraction of the optical element, the working diameter of the optical element forming die is corrected, and the optical element having a desired shape is formed by the optical element forming die. If there is no shortage in the outer diameter of the optical element, the optical element is pressed and formed with the same processing diameter.

[0012]

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing an optical element molding die of the present embodiment, FIG. 2 is a schematic configuration diagram showing a molding machine provided with the optical element molding die and molding an optical element, and FIG. 3 is a lens drawing of a lens to be molded. FIG.

The lens molded by the optical element mold of the present embodiment has an outer diameter L, an outer diameter tolerance a, and an outer diameter fluctuation tolerance b. The optical element mold is, as shown in FIG.
The mold processing diameters for molding the surfaces 10a and 10b are arranged so as to face each other. The mold processing diameters are the outer diameter L of the lens 10, the outer diameter tolerance a, and the outer diameter deflection tolerance as the misalignment tolerance with respect to the optical axis. The surface 10 of the lens 10 to be formed with the size obtained by adding the amount of b
It is formed in a shape inverted from the shape of a, 10b.
An outer peripheral portion that determines the outer diameter of the optical element molding die is provided outside the mold processing diameter, and the outer peripheral portion is formed in a tapered shape so that opposing outer peripheral portions are separated from each other. The surface is continuously connected by minute R. In addition,
The outer peripheral portion of the optical element molding die may be an R-shaped surface such that opposing outer peripheral portions are separated from each other.

As shown in FIG. 2, the molding machine used for molding the lens has an upper mold 1 and a lower mold 2 made of the above-mentioned optical element molding mold in a molding chamber 9 with the mold processing diameters facing each other. Are located in An upper heater 3 and a lower heater 4 are installed around the upper mold 1 and the lower mold 2, respectively.
Are configured to be independently heatable.
The upper die 1 and the lower die 2 are provided with an upper sensor 5 and a lower sensor 6, respectively.
And the lower sensor 6, respectively, to control the heating temperature. The glass material 8 is sucked by the transfer arm 7 that can move forward and backward, and can be transferred from the outside of the forming chamber 9 to the upper mold 1 and the lower mold 2 so that the glass material 8 can move forward and backward between the upper mold 1 and the lower mold 2. Has become.

When pressing the lens, the glass material 8 is sucked and conveyed by the transfer arm 7 between the upper mold 1 and the lower mold 2, and then the suction is released to remove the glass material 8 from the lower mold 2. The transfer arm 7 is placed on the upper side and retracted. Then, the upper mold 1 and the lower mold 2 are simultaneously heated to a predetermined temperature by using the upper heater 3 and the lower heater 4 so that the glass material 8 can be pressed. Thereafter, the lower mold 2 to which a servomotor (not shown) is connected is raised by driving the servomotor, and the glass material 8 is pressed by the upper mold 1 and the lower mold 2 to form a desired lens 1.

Next, a specific example of the optical element molding die will be described. In the present embodiment, taking the lens drawing of FIG. 3 as an example,
An optical element molding die for molding the lens was used. It should be noted that only the parts necessary for the present embodiment are shown in the lens drawings.

The lens 10 has an outer diameter φ as shown in FIG.
7.8 mm, outer diameter tolerance ± 0.03 mm, outer diameter deflection tolerance 0.02 mm, the first surface 10a side of the lens 10 is a convex spherical surface having a radius of curvature R80.32 mm, and an effective diameter φ7.12 mm.
The second surface 10b side is a convex aspheric surface with a paraxial R of 50.5 mm and has an effective diameter of 7.24 mm. The edge of the lens 10 is instructed to chamfer C0.1.

As shown in FIG. 1, an optical element molding die for molding the lens shown in the above lens drawing,
First, optical accuracy is ensured at each of the front end portions facing each other with a processing diameter of φ7.8 mm, and the first surface 1 of the lens 10 is
0a and the second surface 10b are respectively formed in an optical element molding die for forming an effective diameter of the first surface of the mold of 7.12 mm and an effective diameter of the second surface of the mold of 7.0.
Ensure surface accuracy of 24 mm. Next, the outer diameter φ7.8 mm
The outer diameter tolerance 0.03 mm and the outer diameter run-out tolerance 0.02 mm are added to the processing diameter of to secure a mold processing diameter up to 7.85 mm. And the diameter after each die machining diameter is about 15
It is processed to an outer diameter of 10 mm with a taper angle of degree, and the processing diameter of each die and the tapered surface are connected by a minute R (about 0.2).
The outer diameter of the optical element molding die is determined from the point of mold strength.

The optical element molding die was set in the molding machine shown in FIG. 2, and the lens 10 shown in FIG. 3 was pressed. The transfer arm 7 of the glass material 8 is accurately positioned and the lower die 2
Although the glass material 8 can be supplied on the upper side, the glass material 8 is not necessarily placed on the center of the lower mold 2 due to variations in the shape of the glass material 8 and vibration of the glass material 8 when the glass material 8 is placed on the lower mold 2. In some cases, it cannot be placed. Therefore, there is a molded product 10 ′ formed by pressing the glass material 8 at a position shifted from the center of the upper mold 1 and the lower mold 2, so that the glass material 8 has a volume increased by about 15% compared to the volume of the lens 10. It was set and manufactured.

The molding conditions are as follows: the glass material 8 is placed almost at the center of the lower mold 2; the temperature is 580 ° C .;
When the molding was performed at a setting of 80 N, a pressing time of about 1 minute was required until the molded product 10 ′ had a desired medium thickness. When the placement position of the glass material 8 on the lower mold 2 was shifted to the maximum under the same molding conditions, the molding was confirmed. In this case, too, the same as when the glass material 8 was placed at the center of the lower mold 2 It was medium thick. That is, the outer diameter of the lens 10 is added to the necessary minimum mold processing diameter by adding the outer diameter tolerance and the outer diameter runout tolerance. This is because the upper mold 1 and the lower mold 2 are formed in such a shape that the upper mold 1 and the lower mold 2 are separated from each other at a taper angle so that no resistance is generated in the flow of the glass when the glass is pressed. On the other hand, when a glass material is pressed and molded by a mold having flat flat portions as in the past, when the mounting position of the glass material is shifted to the maximum, the pressing time of about 1 minute 30 seconds is required. Was needed. In order to shorten the pressing time, it is necessary to raise the temperature or increase the pressing load, both of which are not preferable from the viewpoint of mold durability. Further, if the conditions are maintained, there is a problem that the thickness of the molded lens varies and the cycle time of molding becomes long.

The lenses molded this time were measured to determine whether or not the required lens outer diameter was secured. As a result, all the lenses passed. Further, the edge portion has C0.1.
The glass shrinkage could be absorbed by the tolerance when forming the die working diameter.

According to the present embodiment, it is possible to easily determine the minimum required processing diameter for forming a desired lens by using the tolerance value of the lens drawing. Since the outer peripheral portion has a shape in which the molds are separated from each other, stable molding of the lens can be easily performed even if the glass material 8 is set large. Further, the pressing time of the glass material 8 was shortened, and it was possible to contribute to the improvement of the mold durability.

(Embodiment 2) Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing an optical element molding die of the present embodiment, and FIG. 5 is a diagram showing a lens drawing of a lens to be molded. The molding machine for molding the lens by disposing the optical element molding die of the present embodiment is the same as that used in the first embodiment, and the illustration thereof is omitted.

The lens molded by the optical element molding die of the present embodiment has an outer diameter L, an outer diameter tolerance a, and an outer diameter fluctuation tolerance b, and has a spherical portion on the outer periphery of one lens surface. As shown in FIG. 4, the optical element molding die is arranged so that the processing diameters for molding the first surface 20a and the second surface 20b of the lens 20 are opposed to each other. The processing diameter of the optical element molding die 21 for molding the first surface 20a having no spherical portion is the outer diameter L of the lens 20.
Of the optical element molding die 22 for molding the second surface 20b side having the ball cutout portion by adding an outer diameter tolerance a and an outer diameter deflection tolerance b as a misalignment tolerance with respect to the optical axis. Is the size obtained by adding the above-mentioned outer diameter tolerance a and the outer diameter deflection tolerance b to the outer diameter with the ball diameter being the outer diameter. An outer peripheral portion for determining the outer diameter of the optical element molding die is provided outside the processing diameter of the optical element molding die 21, and the outer peripheral portion is separated from the outer peripheral portion of the optical element molding die 22 facing the optical element molding die 22. As described above, the mold processing diameter and the tapered surface are continuously connected with a small radius. Further, outside the processing diameter of the optical element molding die 22, there is provided a ball notch processing diameter, and the outer diameter of the outside diameter equal to the outer diameter of the optical element molding die 21 outside this ball notch processing diameter. The portion is formed in a tapered shape so as to be separated from the outer peripheral portion of the opposing optical element molding die 21, and the processing diameter of the ball cutout portion and the tapered surface are continuously connected by a minute radius. The opposing outer peripheral portions of the optical element molds 21 and 22 may have an R-shaped surface where the outer peripheral portions are separated from each other.

Next, a specific example of the optical element molding die will be described. In the present embodiment, the lens drawing of FIG.
An optical element molding die for molding the lens was used. It should be noted that only the parts necessary for the present embodiment are shown in the lens drawings.

The lens 20 has an outer diameter φ as shown in FIG.
18 mm, outer diameter tolerance ± 0.02 mm, outer diameter run-out tolerance 0.
05 mm, the first surface 20a side of the lens 20 has a radius of curvature R
A convex spherical surface of 405.87 mm has an effective diameter of 16.8 mm, the second surface 20b side has a concave aspheric surface having a paraxial R of 30.8 mm and an effective diameter of 13.2 mm, and the second surface 20b has a diameter of 15 mm and a tolerance of ± 0.02 mm. It has a spherical shape.

In the optical element molding die for molding the lens shown in the lens drawing, since the shape of the lens 20 to be molded has a spherical cutout on one surface, first, as shown in FIG. First surface 20a of lens 20 having no spherical portion
The first surface of the optical element molding die 21 for forming
The optical accuracy is ensured with a processing diameter of 15 mm, and the optical accuracy is ensured with a processing diameter of φ15 mm on the second surface of the optical element molding die 22 for forming the second surface 20 b of the lens 20 having the spherical portion. . And the effective diameter φ16.8m of the mold first surface
The surface accuracy of the effective diameter of m and the second surface of the mold is 13.2 mm.

Next, an outer diameter tolerance of 0.02 mm and a run-out tolerance of 0.05 mm are added to the processing diameters of the mold first surface and the mold second surface, respectively, so that φ18.07 mm and the mold second surface are added to the mold first surface. To φ1
A mold working diameter of 5.07 mm is secured. The diameter after each die processing diameter is processed to an outer diameter of 23 mm with a taper angle of about 15 degrees on the first die surface, and the die processing diameter and the tapered surface are connected by a small radius (about 0.2). The outer diameter of the optical element molding die 21 is determined from the point of the mold strength. Mold 2
The surface is convex and the opposing molding dies are in the direction away from each other, so it may be as it is, but it is easy to assume that biting of the glass waste occurs at the time of molding.
As in the case of the surface, the connection was made with a small R (about 0.2), and a processing was performed to an outer diameter of 23 mm with a taper angle of about 15 degrees.

The optical element molding dies 21 and 22 are installed coaxially with the molding machine shown in FIG.
5, the optical element molding die 21 was a lower mold 21 and the optical element molding die 22 was an upper mold 22, and the lens 20 shown in FIG. The transfer arm 7 of the glass material 8 can be accurately positioned to supply the glass material 8 onto the lower mold 21, but the shape of the glass material 8 varies, and the glass material 8 vibrates when placed on the lower mold 21. In some cases, the glass material 8 cannot always be placed on the center of the lower mold 21. Therefore, there is a molded product 20 ′ which is formed by being pressed from the center of the lower mold 21 and the upper mold 22 and pressed against the glass material 8.
The glass material 8 was manufactured by setting the volume to be about 15% larger than the volume of the lens 20.

The molding conditions are such that the glass material 8 is substantially
When the molding was performed at a temperature of 600 ° C. and a pressing load of 1960 N, a pressing time of about 2 minutes was required until the molded product 20 ′ had a desired medium thickness. When the mounting position of the glass material 8 on the lower mold 21 was shifted to the maximum under the same molding conditions, the molding was confirmed. In this case as well, the same as when the glass material 8 was mounted on the center of the lower mold 21 It was medium thick. This is because the outer diameter of the lens 20, the outer diameter tolerance, and the outer diameter runout tolerance are added to the required minimum die processing diameter, and the outer circumference after the die processing diameter is the upper die 22 and the lower die 21.
This is an effect that the upper mold 22 and the lower mold 21 are formed in such a shape that the upper mold 22 and the lower mold 21 are separated from each other at a taper angle so that no resistance occurs in the flow of the glass when the glass material 8 is pressed and formed. When is made to have the same planar shape as before, the resistance at the time of extrusion of the glass at the time of press molding increases, and the same effect as in the first embodiment appears.

When the lens molded this time was measured to determine whether or not the required lens outer diameter was secured, it was found that about 20% of the first surface 20a of the molded product 20 'had an insufficient outer diameter of about 0.03 mm. Met. This is because the glass shrinkage could not be absorbed by a tolerance. In this case, the actually measured and insufficient value of 0.03 mm was added to the die processing diameter of the first surface of the die, and the die processing diameter was reduced to φ18.1 mm. And reset it when setting the expected value of the mold shape. Since it is difficult to determine the final shape of the mold at one time, it is not particularly inconvenient to reset the outer diameter after actually measuring the molded lens, and the merit of setting the minimum mold processing diameter is greater. . FIG. 4 shows a state in which the lens is being press-formed while the mold processing diameter is changed.

According to the present embodiment, it is possible to easily determine the minimum required mold processing diameter for molding a desired lens, and the outer peripheral portions of the opposing optical element molding dies 21 and 22 Since the shape of the glass material 8 is large, stable molding of the lens can be easily performed even if the glass material 8 is set large.

[0033]

As described above, according to the first aspect of the present invention,
According to the optical element molding die, the minimum processing diameter can be easily set by using a mold processing diameter obtained by adding a tolerance to the outer diameter of the optical element to be molded. An optical element having a desired outer diameter and desired thickness can be formed stably.

According to the optical element molding method of the second aspect of the present invention, the molded optical element is actually measured, and the working diameter of the optical element molding die is corrected in accordance with the actually measured value. An optical element having a desired outer diameter and medium thickness can be stably formed by using a glass material having a minimum mold processing diameter and a large volume.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical element molding die according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a molding machine for molding an optical element by disposing an optical element molding die according to the first embodiment of the present invention.

FIG. 3 is a lens drawing of a lens molded by the optical element molding die according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating an optical element molding die according to a second embodiment of the present invention.

FIG. 5 is a lens drawing of a lens molded by an optical element molding die according to Embodiment 2 of the present invention.

[Explanation of symbols]

 1,22 Upper die 2,21 Lower die 10,20 Lens L Lens outer diameter a Outer diameter tolerance b Outer diameter deflection tolerance

Claims (3)

[Claims] When a heated and softened glass material is pressed by a pair of heated molds to form an optical element, in the optical element mold, the mold processing diameter of the mold is set to a desired outer diameter of the optical element + core. An optical element molding die, characterized in that: a deviation tolerance + an outer diameter processing tolerance, and a diameter outside the die processing diameter is set as a plane or an R-plane so that the pair of molding dies facing each other are separated from each other. 2. The glass material is heated and softened simultaneously with the pair of molds, or the glass material is separately heated and softened with the pair of molds, and then conveyed between the pair of molds.
In an optical element molding method for molding an optical element by pressing a glass material in the pair of molding dies, the molded optical element is measured, and the mold is formed as necessary so that at least the outer diameter of the optical element is secured. An optical element molding method using an optical element molding die having a modified outer diameter. (3)